Herbaceous fiber material and its wet-ground product, their manufacturing method and use

Abstract

To provide a new pretreatment technique to improve fibrillation properties of a herbaceous fibrous material, a new herbaceous fibrous material produced through the new pretreatment technique, and application products using the new herbaceous fibrous material.SOLUTION: A herbaceous fibrous material is provided, of which decrement of glucan percentage content (comparison to dried one, wt.%) is equal to or less than 30%, and of which decrement of xylan percentage content (comparison to dried one, wt.%) is from 5% or more to 50% or less. A production method for the herbaceous fibrous material is provided, including an acid treatment process for processing the herbaceous fibrous material under hydrogen gas atmosphere or processing it through contact with a mixed aqueous solution including hydrochloric acid and an electrolyte other than hydrochloric acid, which liberates chloride ions in water, at a temperature of substantially 10°C or more to 50°C or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a herbaceous fiber material and a wet-ground product thereof. More specifically, the present invention relates to a defibration pretreatment process that reduces environmental impact and production costs in order to provide a defibrated fibrous material made from herbaceous fiber as a raw material, and to a herbaceous fiber material and a wet-ground product thereof obtained thereby that have novel structural properties. [Background technology]

[0002] Biomass, which is mainly composed of cellulose such as plant stems and leaves, has been used mainly in the paper and textile industries through the recovery of fibrous materials such as pulp and hemp. Plant-derived fibrous materials are expected to have excellent value in terms of abundant resources, environmental impact compared to fibers derived from fossil resources, biocompatibility, biodegradability, etc.

[0003] In recent years, there has been active research into the application of these natural fibrous materials to new applications by highly defibrating and refining them to reveal new physical properties and functionality. One representative example of this research is the production and use of cellulose nanofibers (CNF). Highly defibrated and refined fibrous materials are being considered for use in functional additives (thickeners, ballpoint pen ink, water-based paints, adhesives, etc.), highly functional everyday products (shoe rubber, air filters, etc.), and reinforced resins (polypropylene, nylon 6, etc.).

[0004] Furthermore, efforts are underway to use raw materials such as pulp and absorbent cotton in strong acid hydrolysis using sulfuric acid, hydrochloric acid, etc. to break down the cellulose chains, recovering only the crystalline cellulose portion with a degree of polymerization of several hundred, and using it as a functional additive as cellulose nanocrystals (CNC), a type of CNF. Expectations are rising for industrial use of such defibrated and micronized fibrous materials, driven by the need to develop bioplastics for decarbonization and reducing the environmental burden.

[0005] However, the development and use of defibrated and finely divided fibrous materials has mainly been carried out using wood raw materials, and with the exception of cotton, which can be purified into cellulose by degreasing, many herbaceous fibers have been left behind in cutting-edge research into their advanced uses.

[0006] In this context, a method has been proposed and investigated in which herbaceous fiber is powdered and then wet-milled to defibrate and refine it (the grinder method). However, it has been pointed out that repeated grinding processes in this method increase energy consumption and production costs. Thus, in order to provide fibrous materials that are competitive in terms of production cost and have a reduced environmental impact, a pre-defibration process that improves the defibration properties of the raw material is considered necessary.

[0007] One known acid treatment technique for fibrous raw materials is hydrolysis by heating in an aqueous solution of hydrochloric acid or sulfuric acid. To date, processes have been proposed in which glucan and xylan are hydrolyzed in one step (e.g., concentrated sulfuric acid saccharification) or two steps (e.g., dilute sulfuric acid saccharification) to recover as many monosaccharides as possible, but no method has been investigated for hydrolysis that leaves most of the glucan and xylan intact.

[0008] The acid hydrolysis process, in which hydrogen chloride gas acts on fibrous raw materials, has long been considered a core process for wood saccharification. Unlike the hydrolysis mechanism in liquids, which proceeds from the solid-liquid interface, hydrogen chloride gas treatment dissolves the cellulose in the free water in the matrix, and the heat generated during dissolution is thought to result in localized and efficient hydrolysis. However, conventional hydrogen chloride gas treatments have been aimed at completely decomposing polysaccharides.

[0009] In recent years, it has been reported that an efficient CNC recovery process can be achieved by treating cellulosic raw materials such as filter paper powder with hydrogen chloride gas, which fragments the cellulose and allows CNC to be recovered (see Patent Document 1 and Non-Patent Document 1). However, there is no evidence that hydrogen chloride gas treatment promotes defibration of fibrous materials.

[0010] Furthermore, Patent Document 2 by the present inventors discloses a technology for producing a novel material that is soluble and dispersible by treating a material containing polysaccharides with an acid, causing the polysaccharides to swell and become smaller in molecular weight. However, "solubilization" and "dispersion" refer to a state in which particles are apparently uniformly distributed in water, and are therefore clearly different from the material that gives a bulky precipitate provided by the present disclosure. Furthermore, Patent Document 2 differs in that "polysaccharides" are swelled, whereas the present disclosure fluffs the entire stem and leaf tissue of herbs to increase their bulk. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Special Publication No. 2014-511907 [Patent Document 2] Patent No. 5190858 [Non-patent literature]

[0012] [Non-Patent Document 1] E. Kontturi, et al., Angew. Chem. Int. Ed., 55, 14455-14458 (2016) Summary of the Invention [Problem to be solved by the invention]

[0013] In light of the above circumstances, the present inventors have conducted extensive research into pretreatment processes for improving the defibration ability of herbaceous fibers. As a result, they have found that treating herbaceous fibers in a hydrogen chloride gas atmosphere or subjecting them to an acid treatment in which they are brought into contact with a solution that emits hydrogen chloride gas not only improves the defibration ability of the fibers but also significantly suppresses the decrease in their glucan and xylan content. Furthermore, the present inventors have found that wet grinding after this acid treatment produces a new material that is excellent in enzymatic saccharification and has a "network structure" in which the entire tissue is fluffy. Based on these findings, the present inventors have completed the present disclosure.

[0014] The objectives of the present invention are to provide a new pretreatment technology for improving the defibration ability of herbaceous fiber, to provide a new herbaceous fiber material obtained by said pretreatment technology, and to provide application products using said new material. [Means for solving the problem]

[0015] In order to solve the above problems, the present disclosure provides a herbaceous fiber material characterized by a reduction in glucan content (by weight of dry matter) of 30% or less and a reduction in xylan content (by weight of dry matter) of 5% to 50% compared to the composition of the raw herbaceous fiber material.

[0016] The herbaceous fiber material may be produced by a method including the following steps: An acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or contacted with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C. A step of washing and / or adjusting the pH of the treated product after the acid treatment step.

[0017] The present disclosure also provides: an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a wet-pulverization step in which the treated product that has been subjected to the acid treatment step is subjected to a wet-pulverization step; A wet-ground herbaceous fibrous material produced by a method comprising: Compared with a wet-ground product obtained by the same method except that the raw herbaceous fiber material was not subjected to the acid treatment step, The wet-ground product of herbaceous fiber material is characterized in that the apparent volume of the precipitate obtained when the wet-ground product is suspended in water and allowed to stand at room temperature for one hour or more is at least doubled, and / or the saccharification rate of glucan when the wet-ground product is treated with a fiber-degrading enzyme is at least 1.5 times higher.

[0018] Furthermore, the present disclosure also provides a method for producing a herbaceous fiber material, comprising the steps of: An acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or contacted with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C. A step of washing and / or adjusting the pH of the treated product after the acid treatment step.

[0019] The present disclosure also provides a method for producing a wet-ground herbaceous fibrous material, the method comprising the steps of: An acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or contacted with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C. A wet-pulverizing step in which the treated product that has undergone the acid treatment step is subjected to a wet-pulverizing step.

[0020] Furthermore, the present disclosure also provides products such as resins, plastics, rubbers, inks or paints; paper, nonwoven fabrics, fibers, seedling pots or boards; saccharification raw materials or feeds; which contain the herbaceous fiber material or a wet-ground product of the herbaceous fiber material, a fraction thereof, or a modified and / or altered product thereof. [Effects of the Invention]

[0021] The present disclosure provides a pretreatment technique for defibrating herbaceous fiber that can improve the defibration ability of herbaceous fiber while significantly suppressing the solubilization of glucan and xylan. Furthermore, the herbaceous fiber material obtained by this pretreatment technique can be further subjected to a wet milling process to obtain a material with excellent enzymatic saccharification properties and the unique property of forming fluffy tissues that form bulky sediments in water.

[0022] In other words, the present disclosure provides a new pretreatment technology for improving the defibration ability of herbaceous fiber, a new herbaceous fiber material obtained by the pretreatment technology, and application products using the new material. [Brief explanation of the drawings]

[0023] [Figure 1A] FIG. 1 is an image diagram of the formation of bulky precipitates according to the present disclosure. [Figure 1B] FIG. 1 is a photographic image comparing the sediment volume of a wet-milled product of the present disclosure (right) and a control sample (left). [Figure 1C] 1 is a micrograph of a wet-milled product according to the present disclosure (white bar: 50 μm) (Example 3). [Figure 2A] 2A is a graph showing the bulkiness of wet-ground materials derived from various raw materials (Example 2). In Fig. 2A, the vertical axis represents the volume of sediment (unit: mL) of the sample, and the horizontal axis represents, from left to right, rice straw, sugarcane bagasse, Miscanthus sinensis, and Erianthus. The left bar represents data for the hydrochloric acid-calcium chloride aqueous solution treatment group, and the right bar represents data for the control group (treated with calcium chloride aqueous solution). [Figure 2B] 2B is a graph showing the enzymatic saccharification rate of wet-ground materials derived from various raw materials (Example 2). In Fig. 2B, the vertical axis represents the enzymatic saccharification rate of glucan (unit: %), and the horizontal axis represents, from left to right, rice straw, sugarcane bagasse, Miscanthus sinensis, and Erianthus. The left bar represents data for the hydrochloric acid-calcium chloride aqueous solution treatment group, and the right bar represents data for the control group (treated with a calcium chloride aqueous solution). [Figure 3] FIG. 10 is a schematic diagram showing a method for a gas-phase treatment test in Example 3. [Figure 4]FIG. 1 is a photographic image showing a plate molded using the wet-ground material of the present disclosure (Example 8). [Figure 5] FIG. 1 is a photographic image of a sheet (nonwoven fabric) formed using the wet-ground product of the present disclosure (Example 9). [Figure 6] FIG. 11 is a photographic image showing the method of the gas phase treatment test in Example 11. [Figure 7] FIG. 1 is a photographic image showing a rod-shaped product formed using the wet-ground product of the present disclosure (Example 12). DETAILED DESCRIPTION OF THE INVENTION

[0024] This embodiment will be described in detail below.

[0025] (1) Herbaceous fiber material The herbaceous fiber material of this embodiment is characterized in that, compared to the composition of the raw herbaceous fiber material, the glucan content (based on dry matter, weight %) is reduced by 30% or less, and the xylan content (based on dry matter, weight %) is reduced by 5% or more and 50% or less.

[0026] "Herbaceous fiber raw material" refers to at least a part of a herbaceous plant, and may be, for example, the stems and leaves of herbaceous plants that are by-produced during agricultural production (rice straw, wheat straw, corn stover, sugarcane trash, etc.) and / or underground parts, residues that are by-produced during the primary processing of agricultural products and / or during food manufacturing (sugarcane bagasse, rice husks, corn cobs, etc.), the stems and leaves of purpose-cultivated herbaceous resource crops (erianthus, miscanthus, miscanthus, sorghum, switchgrass, napier grass, etc.), herbaceous plants and weeds (miscanthus, etc.) cut down from the waterside of rivers and / or lakes, on slopes next to roads, etc., or aquatic plants. Preferably, the "herbaceous fiber raw material" may be one or more selected from the group consisting of rice straw, wheat straw, corn stover, sugarcane bagasse, sugarcane trash, Miscanthus sinensis, Miscanthus saccharinus, Erianthus, sorghum, napier grass, judea, Danchiku, and hemp.

[0027] The herbaceous fiber raw material may be a shredded, crushed, pulverized, dried, defatted, bleached, mildly acid-treated, or mildly alkali-treated herbaceous fiber raw material. While it is preferable that cell wall components such as lignin are not removed from the herbaceous fiber raw material, it may also be a raw material from which the cell wall components have been partially removed. This is because it is considered difficult to improve defibration properties if cell wall components other than cellulose are completely removed before acid treatment. Therefore, raw materials with a very high glucan (mainly containing cellulose) content, such as highly refined pulp (specifically, raw materials with a glucan content of over 80%), are not preferred as herbaceous fiber raw materials for this embodiment. Similarly, raw materials from which cell wall components other than cellulose have been completely removed are not preferred as herbaceous fiber raw materials for this embodiment.

[0028] The herbaceous fiber material is prepared by subjecting the herbaceous fiber raw material to the aforementioned acid treatment step, followed by washing and / or pH adjustment. Herbaceous fiber raw materials contain glucan and xylan as polysaccharides, but these are largely decomposed and solubilized by conventional treatment with an aqueous acid solution. However, a major feature of the herbaceous fiber material of this embodiment is that the glucan and xylan contents (based on dry matter, weight %) are reduced by 30% or less and 50% or less, respectively, compared to the composition of the raw herbaceous fiber raw material. Preferably, the reduction in glucan content may be 30% or less, 25% or less, 20% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, or 10% or less. Preferably, the reduction in xylan content may be 50% or less, 45% or less, 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, or 35% or less. The lower limit of the reduction rate of the xylan content may be 5% or more.

[0029] Here, the glucan or xylan content is the weight ratio (%) of glucan or xylan to the dry weight of solids in the sample. The reduction in the glucan or xylan content is the ratio (%) obtained by subtracting the content after acid treatment from the content before acid treatment, divided by the content before acid treatment. The reduction in the glucan or xylan content must be evaluated based on the sample remaining after washing the acid-treated material. Because monosaccharides, oligosaccharides, and other hydrolysis products of the acid treatment remain in the acid-treated sample, measuring the glucan or xylan content without washing after acid treatment theoretically results in a sugar composition that is nearly identical to that of the herbaceous fiber material before acid treatment. The glucan and xylan amounts are evaluated as the amounts of glucose and xylose homopolymers, respectively. Detailed calculation methods for these values ​​are as described in Example 1.

[0030] The herbaceous fibrous material may contain lignin derived from the raw material. The lignin content (based on the dry matter, weight %) in the herbaceous fibrous material is not particularly limited, but is usually 30% or less, preferably 10% to 25%.

[0031] The herbaceous fibrous material of this embodiment also has improved defibrability due to the acid treatment process. Therefore, it is desirable to subsequently subject the herbaceous fibrous material to a defibration process, but this application is not limited to this. One method for confirming improved defibrability is to disperse the defibrated herbaceous fibrous material in water and measure the apparent volume of the precipitate observed after leaving it at room temperature for a certain period of time (e.g., one hour or more). The apparent volume of the mass of precipitated herbaceous fibrous material can be measured visually using a graduated container (e.g., a measuring cylinder). Increased defibrability makes the fibers more likely to fluff, resulting in a bulkier precipitate. When the defibration process is continued for a long period of time, even if there is no difference in final defibrability between a control sample that has not been subjected to the acid treatment process and a treated sample, it is important to be able to reduce the time to reach the final defibrated state or the severity of the defibration process.

[0032] The herbaceous fiber material according to this embodiment is a product invention, but its definition includes a manufacturing method. The inventors believe that the herbaceous fiber material possesses the seemingly contradictory structural properties of improved defibration and polysaccharide retention due to limited modification of the herbaceous fiber raw material with hydrogen chloride gas. However, this state of the herbaceous fiber material is transient, making it impossible to clearly describe the actual structure and properties of the material in words. Even if the morphology of the herbaceous fiber material were observed using a scanning electron microscope or other instrument, the defibration properties of the tissue vary depending on the type of raw material. Therefore, repeated measurements of numerous samples, statistical processing, and the need for extensive trial and error to identify the characteristics of the limited modification with hydrogen chloride gas would be highly impractical. Furthermore, the above-mentioned impossible or impractical circumstances also apply to wet-ground herbaceous fiber material.

[0033] (2) Manufacturing method of herbaceous fiber material Next, a method for producing a herbaceous fiber material will be described. This production method includes an acid treatment step and a post-acid treatment step of washing and / or adjusting the pH, as essential steps, and may optionally include a pre-step of subjecting the herbaceous fiber raw material before the acid treatment to physical and / or chemical treatment (such as chopping, crushing, pulverization, drying, defatting, bleaching, mild acid treatment, mild alkali treatment, etc.).

[0034] That is, according to this embodiment, an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a step of washing and / or adjusting the pH of the treated product that has been subjected to the acid treatment step; A method for producing a herbaceous fibrous material is provided.

[0035] Moreover, according to one embodiment, A pre-process of subjecting the herbaceous fiber raw material to one or more treatments selected from shredding, crushing, pulverizing, drying, degreasing, bleaching, mild acid treatment, and mild alkali treatment; an acid treatment step in which the treated product from the previous step is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water, at a temperature substantially between 10°C and 50°C; a step of washing and / or adjusting the pH of the treated product that has been subjected to the acid treatment step; A method for producing a herbaceous fibrous material is provided.

[0036] The preceding step in this production method may be, for example, a step of drying the herbaceous fiber raw material. The herbaceous fiber raw material can be acid-treated in a dry or wet state, but to improve the efficiency of the acid treatment, it is desirable to reduce the moisture content. The moisture content of the herbaceous fiber raw material can usually be 40% or less, preferably 20% or less, and more preferably 10% or less. When acid treatment is performed under low moisture content conditions, components or parts thereof located near the free water are preferentially hydrolyzed, which is thought to reduce the physical strength of the tissue and improve defibration ability while minimizing excessive hydrolysis and loss of polysaccharides.

[0037] Furthermore, the pre-processing step in this production method may be, for example, a step of chopping, finely crushing, pulverizing, etc. the herbaceous fiber raw material. Because acid evaporates from the gas phase or solid-liquid interface toward the solid surface, it is desirable to chop, finely crush, pulverize, etc. the herbaceous fiber raw material before acid treatment so that the herbaceous fiber raw material has a sufficient surface area and the gas can spread throughout the raw material in a short period of time. These treatments can be carried out using known methods, such as cutting with a sharp blade, cutting by impact force using a hammer mill or ball mill, or cutting by shear force using a grinder or extruder.

[0038] The pre-processing step in the present production method may include, for example, degreasing, bleaching, or mild acid or alkali treatment of the herbaceous fiber raw material, but preferably does not include a step of completely removing cell wall components other than cellulose. As mentioned above, if cell wall components other than cellulose are completely removed before acid treatment, it is considered difficult to improve defibration performance. However, the effects of the present disclosure may be achieved even with raw materials with mildly modified cell walls. Therefore, the pre-processing step in the present production method does not include a process that removes cell wall components other than cellulose to achieve a very high glucan (mainly containing cellulose) content like highly refined pulp (specifically, a glucan content of more than 80%). "Mild acid treatment" refers to, for example, a conventional acid treatment performed for a short period of time in an acid solution to slightly elute cell wall components (e.g., a glucan content of 80% or less). "Mild alkali treatment" may be, for example, a conventional alkali treatment performed for a short period of time for the purposes of desalting, dexylanization, delignification, etc. The degreasing and bleaching treatments can be carried out by conventionally known techniques.

[0039] In the acid treatment step of this production method, the herbaceous fiber material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution that emits hydrogen chloride gas. The application of hydrogen chloride gas partially decomposes the herbaceous fiber material, improving the efficiency of defibration. At the same time, it is important to minimize the loss of polysaccharides in the herbaceous fiber material. Reducing the loss of polysaccharides in the herbaceous fiber material is believed to maintain its value as fiber and enhance its value as a saccharification material.

[0040] The acid treatment step in this production method can be carried out by bringing the herbaceous fiber raw material (or its shredded, crushed, pulverized, dried, defatted, bleached, or mildly acid- or alkali-treated form) into the presence of hydrogen chloride gas. Hydrogen chloride gas can be supplied as commercially available hydrogen chloride gas, gas generated from a highly concentrated hydrochloric acid aqueous solution, or gas generated from a mixed aqueous solution that emits hydrogen chloride gas.

[0041] The "mixed aqueous solution that releases hydrogen chloride gas" may be a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water. The "electrolyte other than hydrochloric acid that liberates chloride ions in water" may be calcium chloride, magnesium chloride, ammonium chloride, or the like. Alternatively, the "mixed aqueous solution" may contain one or more electrolytes selected from calcium chloride, magnesium chloride, and ammonium chloride dissolved therein as the electrolyte other than hydrochloric acid that liberates chloride ions in water, or may contain a solute substantially equivalent to the aqueous solution in which the electrolyte is dissolved. Here, the "solute substantially equivalent to the aqueous solution in which the electrolyte is dissolved" may be, for example, lithium chloride, barium chloride, iron chloride, or the like, but is not particularly limited thereto. The concentration of hydrochloric acid to the concentration of the electrolyte other than hydrochloric acid in the "mixed aqueous solution" may be, for example, but is not limited to, a molar ratio of 10:1 to 1:20, preferably 5:1 to 1:5, more preferably 2:1 to 1:5, and particularly preferably 1:1 to 1:5. Specifically, the "mixed aqueous solution" may contain 0.2 to 11 M hydrochloric acid and an electrolyte other than hydrochloric acid, such as calcium chloride, at 2 to 5 M, preferably 3 to 5 M, but is not limited thereto.

[0042] Possible methods for coexisting herbaceous fiber raw material (substrate) with hydrogen chloride gas include, in addition to passing hydrogen chloride gas through a chamber filled with the substrate, placing the substrate and a hydrogen chloride gas source (such as a high-concentration hydrochloric acid solution or a mixed aqueous solution that emits hydrogen chloride gas) in a sealed container without contact, contacting the substrate with a solution that serves as a hydrogen chloride gas source (such as a high-concentration hydrochloric acid solution or a mixed aqueous solution that emits hydrogen chloride gas), and contacting a solid electrolyte other than hydrochloric acid with hydrochloric acid to generate hydrogen chloride gas as the electrolyte dissolves. However, this is not limited to these methods. In the "method of contacting the substrate with a solution that serves as a hydrogen chloride gas source" (hereinafter sometimes referred to as "liquid-phase treatment"), the entire substrate may be immersed in the solution, or at least a portion of the substrate may be above the liquid surface. Specifically, the amount of solution per 1 g of substrate can be 0.5 mL or more, 0.75 mL or more, 1 mL or more, 1.25 mL or more, 1.5 mL or more, 1.75 mL or more, 2 mL or more, 2.25 mL or more, 2.5 mL or more, 2.75 mL or more, or 3 mL or more. Note that the "method of passing hydrogen chloride gas through a chamber filled with a substrate" and the "method of placing the substrate and a hydrogen chloride gas source in a sealed container in a non-contact state" are sometimes referred to as "gas-phase treatment" in this disclosure. After use in a non-contact reaction (gas-phase treatment), a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water can be heated to evaporate and separate the hydrogen chloride gas and water, thereby increasing the concentration of the electrolyte in the aqueous solution and allowing the electrolyte to be reused or recycled.

[0043] The acid treatment step is carried out substantially within a temperature range of 10°C to 50°C. Here, "substantially" means that the total time spent on acid treatment at temperatures outside the above temperature range is 5% or less, preferably 3% or less, of the total acid treatment time. The preferred temperature conditions for the acid treatment step are 10°C to 40°C, 20°C to 35°C, and particularly room temperature (25±5°C). Regarding pressure conditions, increasing the partial pressure of hydrogen chloride gas accelerates the hydrolysis reaction, but the treatment can also be carried out under normal or reduced pressure conditions. The treatment time is not particularly limited, as it is affected by factors such as the structure of the raw material, moisture content, treatment temperature, hydrogen chloride gas partial pressure, treatment method, and size of the reaction chamber. Conversely, treatment conditions can be set so that the reduction rate of the glucan and xylan content in the herbaceous fiber material falls within a predetermined range. For example, when 1 mL to 3 mL of a mixed aqueous solution that emits hydrogen chloride gas is contact treated at room temperature (25±5°C) per 1 g of substrate (ground material), the acid treatment time can usually be from a few minutes to 4 days, and preferably from 1 hour to 3 days, from 3 hours to 2 days, from 6 hours to 36 hours, from 8 hours to 30 hours, from 10 hours to 24 hours, or from 12 hours to 20 hours.

[0044] In the method for producing a herbaceous fiber material, the acid-treated product after the acid treatment step is washed and / or pH adjusted. Washing is performed to separate and remove hydrogen chloride gas and hydrochloric acid remaining in the acid-treated product after the acid treatment step; monosaccharides, oligosaccharides, and other hydrolyzed products present as hydrolysis products; and deposits, water-extractable components, and acid-extractable components derived from the herbaceous fiber raw material. This improves the processing and usability properties of the herbaceous fiber material and suppresses quality deterioration when it is processed into boards, paper, etc.

[0045] pH adjustment is performed to reduce or eliminate the corrosiveness, danger, and toxicity of hydrochloric acid to containers and grinding equipment, etc., or when performing processes such as enzymatic reactions and biological culture. It can also include processes such as dilution with water, washing with water, or simple addition of water. pH adjustment can also be achieved by removing hydrogen chloride gas through heating or adjusting the pH in the gas phase with ammonia. The pH adjustment range varies depending on the subsequent operation and is not particularly limited. The introduction of a pH adjustment step is effective when adding water or a buffer solution to the acid-treated product without removing substances that would be removed by washing, followed by a wet grinding step, and then performing enzymatic saccharification directly while minimizing the loss of free sugars. In particular, a pH adjustment step, which replaces a washing step, is industrially advantageous in terms of improving sugar recovery rates and added value as a functional feed by minimizing the loss of functional components such as xylooligosaccharides, which are partial hydrolysates of xylan caused by acid.

[0046] However, as mentioned above, even if the pH is adjusted without washing, when evaluating the rate of decrease in the glucan or xylan content, it is necessary to measure and evaluate the sample after washing.

[0047] In this manner, the herbaceous fiber material of this embodiment can be produced. The herbaceous fiber material can be recovered as a water-insoluble matter after washing and / or pH adjustment. The glucan and xylan contents (evaluated as glucan or xylose homopolymers) of the recovered herbaceous fiber material are calculated to evaluate the component characteristics of the herbaceous fiber material. The glucan and xylan contents of the herbaceous fiber material can be modified by additionally performing a heat treatment in the presence of an acid or an enzyme treatment after the acid treatment step. However, even when such additional treatments that change the component characteristics of the material are performed, the herbaceous fiber material is still included in the scope of the herbaceous fiber material of this embodiment as long as the reduction rates of the glucan and xylan contents before and after the acid treatment step are within the respective predetermined ranges.

[0048] (3) Wet-ground herbaceous fibrous material The wet-ground herbaceous fiber material according to this embodiment is an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a wet-pulverization step in which the treated product that has been subjected to the acid treatment step is subjected to a wet-pulverization step; A wet-ground herbaceous fibrous material produced by a method comprising: Compared with a wet-ground product obtained by the same method except that the raw herbaceous fiber material was not subjected to the acid treatment step, The wet-ground material is characterized in that the apparent volume of the precipitate obtained when suspended in water and allowed to stand at room temperature for one hour or more is more than doubled, and / or the saccharification rate of the glucan when the wet-ground material is treated with a fibrous enzyme is more than 1.5 times higher.

[0049] The wet-ground herbaceous fiber material according to this embodiment (hereinafter sometimes simply referred to as "wet-ground material") is produced by a method that includes the acid treatment step and the wet-ground step as essential steps. The "acid treatment step" and the "herbaceous fiber material" are as explained above.

[0050] The acid treatment step improves the defibration ability of the herbaceous fibrous material, which in turn improves the efficiency of defibration in the subsequent wet-pulverization step. This effect can be evaluated, for example, by suspending the resulting wet-pulverized material in water and allowing it to stand at room temperature for at least one hour, based on the apparent volume of the precipitate obtained. Wet-pulverization of a herbaceous fibrous material can potentially produce a bulky precipitate that is at least two times, preferably at least three times, larger than that of a wet-pulverized sample that has not been subjected to the acid treatment step (e.g., a sample that has been contacted with a solution without hydrochloric acid, a sample that has been contacted with an aqueous solution of hydrochloric acid only, or a sample prior to the acid treatment step) (see Figure 1B). Detailed methods for evaluating bulky precipitates include, for example, the methods described below in the Examples.

[0051] The mechanism by which wet-milled materials gain bulk in water will be explained with reference to Figures 1A and 1C. The tissue of the herbaceous fibrous material is defibrated by the wet-milling process to become fluffy (Figure 1C), forming a defibrated mechanical pulp-like structure that occupies a large space, resulting in a bulky sediment (Figure 1A).

[0052] Furthermore, the wet-ground product according to this embodiment may have high saccharification potential, such that the saccharification rate of glucan when treated with a fibrous enzyme is 1.5 times or more, preferably 2 times or more, higher than that of a wet-ground product obtained without the acid treatment step. Because of its high saccharification potential, nano-sized materials such as lignocellulose nanofibers (LCNF) and CNF can be easily produced by further wet-grinding the wet-ground product. LCNF is cellulose partially bonded to other cell wall components and is expected to exhibit unique properties such as dispersibility, biodegradability, and derivatization properties. Furthermore, the cell walls of herbaceous fiber resources can be purified under milder conditions than the cell walls of woody fiber resources. Due to this property, the nano-sized wet-ground product obtained according to the present disclosure can be chemically modified using simple alkali treatment, oxidation treatment, or other conditions, which is expected to expand demand for herbaceous fiber resources.

[0053] Examples of "fibrous enzymes" include cellulolytic enzymes such as cellobiohydrolase, endoglucanase, lytic polysaccharide monooxygenase, cellobiose dehydrogenase, cellooligosaccharide phosphorylase, cellobiose phosphorylase, and β-glucosidase; xylan-degrading enzymes such as xylanase, xylosidase, arabinofuranosidase, galactosidase, glucuronidase, and acetyl xylan esterase; pectin-degrading enzymes such as pectinase, pectolyase, arabinanase, galactanase, and pectin methylesterase; xyloglucan-degrading enzymes such as xyloglucanase; (1-3),(1-4)-β-glucan-degrading enzymes such as lichenase; and lignin-degrading enzymes such as lignin peroxidase and laccase. Two or more of these fibrous enzymes can be used in combination. Preferably, a cellulolytic enzyme can be used as the fibrous enzyme. A detailed method for evaluating the saccharification property is, for example, the method described below in the Examples.

[0054] The wet-ground product according to this embodiment may be a fraction obtained by fractionating a fraction mainly composed of wet-ground material having a particle size of less than 1 μm after the wet-ground process, or may be a modified and / or altered product in which at least a portion of the surface has been modified and / or altered. Here, "mainly composed of wet-ground material having a particle size of less than 1 μm" means that the wet-ground product contains a concentration sufficient to significantly express the properties of particles having a particle size of less than 1 μm, for example, 50% or more. Note that the wet-ground product to be obtained by this disclosure also contains particles with a large aspect ratio, and therefore "wet-ground product having a particle size of less than 1 μm" may include particles with a major axis exceeding 1 μm. Furthermore, "modified and / or altered product" refers to, for example, chitosan, xyloglucan, carbohydrates, etc. KishiThese can be polysaccharides such as methylcellulose sodium salt, alginate, galactomannan, gellan gum, carrageenan, and (1-3), (1-4)-β-glucan physically adsorbed onto the surface of wet-milled materials. Adding other substances during wet-milling allows for surface modification and / or alteration. This modification and / or alteration not only improves the functionality of the resulting wet-milled material during use, but also suppresses particle reassociation during wet-milling, potentially improving milling efficiency.

[0055] One application of the wet-ground material according to this embodiment is as a filler for resins, plastics, rubber, inks, paints, and the like. By mixing the wet-ground material with various resins, including polypropylene and nylon 6, and other modifiers, it is possible to modify the physical properties of the material, such as strength, while reducing the environmental impact of plastics that are burned or biodegraded. Furthermore, by converting it into lignocellulose nanoparticles that exhibit dispersing properties, it can be used as a highly functional filler. In other words, this embodiment provides resins, plastics, rubbers, inks, or paints containing the herbaceous fiber material, its wet-ground product, fractions thereof, or modified and / or altered products thereof.

[0056] Other uses of the wet-ground material according to the present embodiment include mass-produced materials such as paper, nonwoven fabrics, fibers, filters, hardboard, plates, and three-dimensional molded objects. Because this material exhibits high biodegradability, it can be used as a material for agricultural mulch, seedling pots, and other applications that are expected to degrade in the environment. The above-mentioned mass-produced materials can be produced by molding the herbaceous fiber material according to the present disclosure, its wet-ground product, or a fraction or modified product thereof, alone or in combination with any auxiliary raw material, using conventional methods. In other words, according to the present embodiment, paper, nonwoven fabrics, fibers, filters, seedling pots, boards, or three-dimensional molded objects containing the herbaceous fiber material, its wet-ground product, a fraction thereof, or a modified and / or altered product thereof, are provided. Furthermore, compared to when wet-pulverization is performed without acid treatment, compression-molded products using wet-pulverized material after acid treatment have stronger binding properties and / or higher density and / or have a lower expansion rate and water absorption rate after water absorption, and are therefore highly useful industrially.

[0057] Another use of the wet-ground material according to the present embodiment can be as a saccharification raw material. Linking enzymatic saccharification, microbial saccharification and fermentation with the production of valuable resources can lead to the production of food, biofuels, and biomaterials. It can also be used as a highly digestible feed for ruminants. The herbaceous fibrous material according to the present disclosure, its wet-ground product, or its fractions, modified products, etc., can be used in stages. For example, the wet-ground material according to the present embodiment can be used as a board and then reused as a saccharification raw material. In this case, by subjecting the discarded molded product to a wet-ground process again, it is possible to obtain an enzymatic saccharification rate equivalent to or higher than that of the original wet-ground product. Furthermore, three-dimensional molded products, such as rods, bars, and blocks, containing the wet-ground material can be manufactured for storage until further use or reuse. That is, according to the present embodiment, a saccharification raw material or feed containing the herbaceous fibrous material, its wet-ground product, a fraction thereof, or a modified and / or altered product thereof is provided.

[0058] (4) Method for producing wet-ground herbaceous fibrous material Next, a method for producing a wet-ground herbaceous fiber material will be described. This production method includes an acid treatment step and a wet-grinding step as essential steps, and may optionally include a pre-step of subjecting the herbaceous fiber raw material before the acid treatment to physical and / or chemical treatment (such as chopping, finely crushing, grinding, drying, defatting, bleaching, mild acid treatment, mild alkali treatment, etc.); a post-acid treatment step of washing and / or adjusting the pH; a step of modifying and / or altering at least a portion of the surface of the wet-ground material; and a step of recovering a fraction mainly composed of wet-ground material with particle sizes less than 1 μm from the wet-ground material obtained in the wet-grinding step. The terms "herbaceous fiber raw material" and "acid treatment step" are as described above.

[0059] According to this embodiment, an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a wet-pulverization step in which the treated product that has been subjected to the acid treatment step is subjected to a wet-pulverization step; The present invention provides a method for producing a wet-ground herbaceous fibrous material, comprising:

[0060] Moreover, according to one embodiment, A pre-process of subjecting the herbaceous fiber raw material to one or more treatments selected from shredding, crushing, pulverizing, drying, degreasing, bleaching, mild acid treatment, and mild alkali treatment; an acid treatment step in which the treated product from the previous step is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water, at a temperature substantially between 10°C and 50°C; a wet-pulverization step in which the treated product that has been subjected to the acid treatment step is subjected to a wet-pulverization step; The present invention provides a method for producing a wet-ground herbaceous fibrous material, comprising:

[0061] According to another embodiment, A pre-process of subjecting the herbaceous fiber raw material to one or more treatments selected from shredding, crushing, pulverizing, drying, degreasing, bleaching, mild acid treatment, and mild alkali treatment; an acid treatment step in which the treated product from the previous step is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water, at a temperature substantially between 10°C and 50°C; a step of washing and / or adjusting the pH of the treated product that has been subjected to the acid treatment step; a wet-pulverization step of subjecting the processed product that has undergone the above steps to a wet-pulverization step; a step of recovering a fraction mainly composed of wet-ground material having a particle size of less than 1 μm from the wet-ground material that has been subjected to the wet-ground step; The present invention provides a method for producing a wet-ground herbaceous fibrous material, comprising:

[0062] The "wet grinding step" can be performed using known grinding devices such as an electric millstone-type defibrator, a bead mill, a ball mill, or other impact grinding devices, as well as an extruder, a high-pressure homogenizer, an ultrasonic crusher, a mortar and pestle, a blender, a Polytron homogenizer, etc. When using these grinding devices, a grinding treatment can be introduced as a pretreatment as needed to match the raw material receiving size of each grinding device. In addition, the wet-ground product according to this embodiment can be kneaded with a hydrophobic material during grinding treatment, either directly or after being subjected to a hydrophobic treatment such as acetylation, and then molded.

[0063] During wet milling, various additives can be added to promote defibration and refinement and to confer new functions. For example, the addition of polysaccharides such as chitosan, xanthan gum (tamarind seed gum), guar gum, carboxymethylcellulose, xyloglucan, alginate, galactomannan, gellan gum, carrageenan, and salts of (1-3)(1-4)-β-glucan, which interact with cellulose, the exposure of which increases during milling, can modify and / or alter the surface of the wet-milled product, thereby imparting new material properties to the wet-milled product. Examples of material properties that can be imparted to wet-milled products through surface modification and / or alteration include altering the association and aggregation properties between wet-milled particles, imparting hydrophilic or hydrophobic properties, imparting positive or negative charges to the surface, imparting antibacterial properties, and modifying the structure and function of the wet-milled product by binding other molecules that recognize the characteristic structure of the polysaccharide.

[0064] The acid treatment step improves the defibration properties of the herbaceous fibrous material, allowing for efficient defibration in the subsequent wet grinding step. As a result, the herbaceous fibrous material exhibits a defibrated mechanical pulp-like structure, occupying a large space and forming a network structure, which forms a bulky precipitate when suspended in water and allowed to stand.

[0065] Furthermore, because the acid treatment process significantly improves the enzymatic saccharification of the polysaccharides in the herbaceous fiber material, by continuing the wet-grinding process, it becomes possible to easily prepare nano-sized wet-grinded material with particle sizes of less than 1 μm.

[0066] The "step of fractionating and recovering a fraction mainly composed of wet-ground particles having a particle size of less than 1 μm from the wet-ground product obtained by the wet-ground process" refers to a step of recovering the wet-ground product that has been pulverized to nano-size in the wet-ground process so that it can be used as a raw material for functional materials such as the aforementioned plastics and boards. The fractionation method is not particularly limited, and methods that can be used include fractionation based on particle size using a mesh or filter, or fractionation with a precipitate based on dispersion characteristics in water or a dispersion medium. Furthermore, "mainly composed of wet-ground particles having a particle size of less than 1 μm" means that the material contains a concentration sufficient to significantly express the properties of particles having a particle size of less than 1 μm, for example, 50% or more.

[0067] The "step of modifying and / or altering at least a portion of the surface of the wet-ground product" is a step that can be added when a step of modifying and / or altering at least a portion of the surface of the wet-ground product is performed separately from the wet-ground process, such as the wet-ground process performed by adding the polysaccharide described above. This step can be performed at any stage in the production method. For example, it can be performed during wet-ground process, after the wet-ground process, or between the acid treatment step and the wet-ground process. This step can be, for example, a step of physically adsorbing the polysaccharide described above onto the surface of the wet-ground product.

[0068] As mentioned above, the "acid treatment step" in this embodiment is positioned as a defibration pretreatment step for improving the defibration properties of the herbaceous fiber raw material to be subsequently defibrated. Therefore, this embodiment also provides a defibration pretreatment method characterized by treating the herbaceous fiber raw material in a hydrogen chloride gas atmosphere or contacting it with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water. [Example]

[0069] The present embodiment will be described in detail below with reference to examples.

[0070] Example 1: Liquid-phase treatment of 1 g of coarsely crushed rice straw, bagasse, Miscanthus sinensis, and Erianthus As herbaceous fiber raw materials, rice straw powder (fineness of crushing 4mm or less, moisture content 9.7%), sugarcane bagasse powder (fineness of crushing 2mm or less, moisture content 1.1%), Miscanthus sinensis powder (fineness of crushing 2mm or less, moisture content 3.3%), and Erianthus powder (fineness of crushing 2mm or less, moisture content 7.3%) were subjected to acid treatment (liquid phase treatment), and the reduction rate of glucan and xylan content was investigated.

[0071] (1) Acid treatment (liquid phase treatment) test 1.00 g of each of the above raw materials was weighed and placed in a plastic tube. 10 mL of a hydrochloric acid-calcium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L) was added to the tube, and the tube was immersed at room temperature (25±5°C, same below). The tube was then capped and left to stand for 18 hours, thereby carrying out the acid treatment. At this point, each raw material was completely immersed in the aqueous solution.

[0072] (2) Measurement of glucan and xylan content The acid-treated sample was placed on a Büchner funnel lined with filter paper and washed with 200 mL of ion-exchanged water. The solid material on the filter paper was collected. The solid material was dried in an oven at 105 °C until constant weight was reached. After returning to room temperature, the dry weight was measured. The sample was then finely ground using a ball mill (MM301, Verder Scientific). The glucan and xylan contents in the sample were measured according to the National Renewable Energy Laboratory method (Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., Crocker, D., Determination of structural carbohydrates and lignin in biomass, laboratory analytical procedure. National Renewable Energy Laboratory, Golden, CO, USA. (2008)). The glucan and xylan contents of the raw material before acid treatment were also measured in the same manner.

[0073] Specifically, according to the method of the National Renewable Energy Laboratory, 20 mg of sample was thoroughly mixed with 1 mL of 72% (w / w) sulfuric acid and allowed to stand at 30 °C for 1 hour. Subsequently, 0.15 mL of this mixture was mixed with 1.05 mL of ion-exchanged water and treated at 100 °C for 2 hours for acid hydrolysis. This acid hydrolyzate was centrifuged at 10,000 × g for 10 minutes, and 1 mL of the supernatant was removed. 1 mL of calcium carbonate suspension (1 g of calcium carbonate suspended in 3 mL of ion-exchanged water) was added to neutralize it. A portion of this neutralized product was used to measure the glucose content using a Glucose CII-Test Wako (Fujifilm Wako Pure Chemical Corporation) and the xylose content using a D-Xylose Assay Kit (Megazyme). The amounts of linear glucan and linear xylan were calculated, respectively. The moisture content was calculated as the value (%) obtained by subtracting the bone-dry weight (the weight of the sample dried at 105°C until it reached a constant weight and then returned to room temperature) from the air-dry weight of the sample and dividing the result by the air-dry weight of the sample.

[0074] (3) Results As a result, as shown in Table 1, in the herbaceous fiber material obtained after acid treatment, the glucan content decreased by within 4% and the xylan content decreased by within 30% compared to the composition of the herbaceous fiber raw material (before acid treatment). In addition, the sample recovery rate after acid treatment was 77% or more.

[0075] The reason why some treatments had a higher glucan content after acid treatment than before is that glucan is relatively stable to acid treatment, while components other than glucan are eluted by acid treatment, resulting in an increase in the proportion of glucan in the total sample. On the other hand, xylan has low crystallinity and is easily solubilized by acid treatment, so conventional acid treatment involving heating easily hydrolyzes xylan down to monosaccharides. Thus, by performing the acid treatment of the present disclosure on herbaceous fiber raw materials, a herbaceous fiber material was obtained in which xylan solubilization was suppressed.

[0076] [Table 1] *Dry weight of sample before and after acid treatment, respectively **Calculated as {(content before acid treatment - content after acid treatment) / content before treatment} x 100 (%). *** Calculated as (dry weight of sample after acid treatment / dry weight of sample before acid treatment) x 100 (%). ****Calculated as (amount of linear glucan or linear xylan in sample / dry weight of sample) x 100 (%).

[0077] Example 2: Liquid-phase treatment and wet-grinding treatment of 0.05 g of coarsely ground rice straw, bagasse, Miscanthus sinensis, and Erianthus The herbaceous fiber raw materials used were rice straw powder (fineness of crushing 4mm or less, moisture content 9.7%), sugarcane bagasse powder (fineness of crushing 2mm or less, moisture content 1.1%), Miscanthus sinensis powder (fineness of crushing 2mm or less, moisture content 3.3%), and Erianthus powder (fineness of crushing 2mm or less, moisture content 7.3%), and were subjected to acid treatment (liquid phase treatment) and wet grinding treatment.

[0078] (1) Acid treatment (liquid phase treatment) test 50 mg of each of the above raw materials was weighed out and placed in a 2 mL plastic tube. Two types of zirconia beads (Nikkato Corporation, equivalent to 500 mg of 0.6 mm diameter beads and one 5 mm diameter bead) were added to this, followed by 400 μL of hydrochloric acid-calcium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L), mixing, and the tube was sealed and left to stand at room temperature for 18 hours, thereby carrying out the acid treatment. At this time, each raw material was completely immersed in the aqueous solution. As a control, the same amount of the above raw materials was treated in the same way, except that calcium chloride aqueous solution (4 mol / L) was added instead of the hydrochloric acid-calcium chloride aqueous solution.

[0079] (2) Wet grinding test After the above treatment, the tube was centrifuged at room temperature (12,000 × g for 5 minutes) and the supernatant was removed. 2 mL of ion-exchanged water was added and the tube was inverted to wash the solid matter (herbaceous fiber material). The tube was then centrifuged again (12,000 × g for 5 minutes) and the supernatant was removed. This washing procedure was repeated three more times. Ion-exchanged water was then added to the tube to adjust the total weight of the sample (total weight of the tube contents) to 1 g. The tube was then placed in a bead mill (Micro Smash MS-100R, TOMY) and subjected to wet milling at room temperature at 4000 rpm for 20 seconds x 6 times.

[0080] (3) Measurement of sediment volume The precipitate volume of the sample (wet-milled product) obtained after the above treatment was measured. Specifically, the contents of the tube after wet-milling, together with the zirconia beads, were suspended in a small amount of ion-exchanged water and transferred to a 15 mL plastic tube. Further ion-exchanged water was added to bring the apparent volume to 5 mL. The tube was stirred in a vortex mixer for 30 seconds to suspend the sample, and then allowed to stand at room temperature for 1 hour, resulting in the formation of a precipitate. The apparent volume occupied by this precipitate was measured using the scale on the plastic tube. The apparent volume occupied by the sample (wet-milled product) within the precipitate was calculated by subtracting (0.25 mL) from this measurement.

[0081] (4) Measurement of enzymatic saccharification rate The enzymatic saccharification rate of glucan using fibrolytic enzymes was measured for the sample (wet-milled product) obtained after the above treatment. Specifically, a cellulase preparation (Cellic CTec2, Novozymes) and a β-glucosidase preparation (Novozyme 188, Novozymes) were used as fibrolytic enzymes. After wet-milling, the sample was placed in a 2 mL plastic tube and 100 mM (final concentration) of sodium acetate buffer (pH 5.0), 0.6 FPU (final amount) of the cellulase preparation, and 0.6 CbU (final amount) of the β-glucosidase preparation were added. To prevent microbial growth during saccharification, sodium azide (Nacalai Tesque) at 0.05% (w / v) (final concentration), chloramphenicol (Nacalai Tesque) at 50 μg / mL (final concentration), and tetracycline (Nacalai Tesque) at 50 μg / mL (final concentration) were added. Further ion-exchanged water was added to the tube to adjust the total volume to 1 mL, and the tube was capped. A saccharification reaction was carried out at 50°C for 48 hours while the tube was inverted. After the reaction, the sample temperature was returned to room temperature, and a portion of the sample was used to perform acid hydrolysis of the saccharified solution according to the method described in paragraph 0071, and the amount of free glucose was measured using a Glucose CII-Test Wako (Fujifilm Wako Pure Chemical Industries, Ltd.). The total glucan content of each herbaceous fiber raw material was measured using the method described in Example 1 (2). The glucose release rate (enzymatic saccharification rate) was calculated by converting the amount of free glucose measured above into glucan and dividing the converted value by the total glucan content of the raw material.

[0082] (5) Results The results are shown in Table 2, Table 3, and Figure 2. As shown in Table 2 and Figure 2A, the sediment volumes of the wet-ground products of rice straw, sugarcane bagasse, Miscanthus sinensis, and Erianthus increased by 5 times, 3 times, 5.7 times, and 3.6 times, respectively, compared to the control. Furthermore, as shown in Table 3 and Figure 2B, the enzymatic saccharification rates of the wet-ground products increased by 1.9 times, 2.7 times, 2.1 times, and 3.4 times, respectively, compared to the control. Thus, it was demonstrated that the ground products obtained by wet-grinding herbaceous fiber materials after acid treatment according to the present disclosure gave bulky precipitates when suspended in water and allowed to stand, and that the enzymatic saccharification rate of glucan by fibrous enzymes was improved.

[0083] [Table 2]

[0084] [Table 3] *Calculated as [amount of glucan converted from the amount of free glucose / total amount of glucan in the raw material] x 100 (%).

[0085] (Example 3) Gas-phase treatment of 0.05 g of coarsely crushed rice straw, sugarcane bagasse, Miscanthus sinensis, and Erianthus Rice straw powder (fineness of crushing 4mm or less, moisture content 9.7%), sugarcane bagasse powder (fineness of crushing 2mm or less, moisture content 1.1%), Miscanthus sinensis powder (fineness of crushing 2mm or less, moisture content 3.3%), and Erianthus powder (fineness of crushing 2mm or less, moisture content 7.3%) were used as herbaceous fiber raw materials and acid treatment (vapor phase treatment) and wet grinding treatment were performed.

[0086] (1) Acid treatment (vapor phase treatment) test 50 mg of each of the above raw materials was weighed out and placed in a 2 mL plastic tube. As shown in Figure 3, 100 μL of a hydrochloric acid-calcium chloride aqueous solution (hydrochloric acid concentration: 1 mol / L, calcium chloride concentration: 4 mol / L) was placed as a droplet in the same tube so as not to come into contact with the raw material. The tube was then capped and allowed to stand at room temperature for 96 hours, thereby carrying out the acid treatment. As a control, the same amount of raw material was left to stand for 96 hours without the addition of the hydrochloric acid-calcium chloride aqueous solution.

[0087] (2) Wet grinding test After the treatment, the liquid droplets were removed from the tube by suction, and 950 μL of ion-exchanged water was added. Zirconia beads (Nikkato Corporation, 500 mg of 0.6 mm diameter beads and one 5 mm diameter bead) were added. The tube was then placed in a bead mill (Micro Smash MS-100R, TOMY Corporation) and wet-milled at room temperature at 4000 rpm for 20 seconds x 6 times. A portion of the resulting wet-milled material was collected and observed at 200x magnification using a microscope (BX51, Olympus Corporation) (Figure 1C, white bar: 0.05 mm). Figure 1C shows that the tissue became fluffy due to the milling treatment.

[0088] (3) Measurement of sediment volume and its results The sediment volumes of the samples (wet-ground products) obtained after the above treatment were measured using the method described in (3) of Example 2. As a result, as shown in Table 4, the apparent volumes of the sediments of the wet-ground products of rice straw, sugarcane bagasse, Miscanthus sinensis, and Erianthus increased by 3.7 times, 2.8 times, 6.3 times, and 2.2 times, respectively, compared to the control.

[0089] [Table 4]

[0090] Example 4: Liquid-phase treatment and wet-milling treatment of 10 g of coarsely ground rice straw Rice straw powder (fineness of crushing less than 4mm, moisture content 9.7%) was used as a herbaceous fiber material and was subjected to acid treatment (liquid phase treatment) and wet grinding treatment.

[0091] (1) Acid treatment (liquid phase treatment) test 10 g of the above raw material was weighed into a plastic tube, and 40 mL of a hydrochloric acid-calcium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L) was added to immerse the raw material in the aqueous solution. The tube was sealed and left to stand at room temperature for 18 hours to carry out acid treatment (liquid phase treatment). At this time, the raw material was completely immersed in the aqueous solution. As a control, the same treatment was carried out using 40 mL of water instead of the hydrochloric acid-calcium chloride aqueous solution.

[0092] (2) Wet grinding test The acid-treated sample was filtered through a Buchner funnel with filter paper placed on it, and the solid matter recovered as the non-passed material was washed with 200 mL of ion-exchanged water and then recovered. 300 mg of the dried material from the recovered sample was suspended in 50 mL of ion-exchanged water and wet-pulverized using a Polytron (PT1200E, KINEMATICA) at room temperature for 60 seconds.

[0093] (3) Measurement of sediment volume and its results The water-insoluble fraction from the wet-milled sample was collected and dispersed in 30 mL of ion-exchanged water. While vigorously stirring this dispersion, 5 mL was collected using a glass pipette with a large tip and transferred to a 15 mL plastic tube. The precipitate volume was then measured using the method described in Example 2(3). As shown in Table 5, the apparent volume of the precipitate in the wet-milled sample was 3.5 times higher than that in the control.

[0094] [Table 5]

[0095] (Example 5) Effect of composition of mixed aqueous solution used in liquid phase treatment Rice straw powder (ground to 4 mm or less, moisture content 9.7%) was used as a herbaceous fiber raw material, and acid treatment (liquid phase treatment) was performed using mixed aqueous solutions of different compositions to investigate the effect on the enzymatic saccharification rate of the wet-ground material.

[0096] (1) Acid treatment (liquid phase treatment) test and wet grinding treatment test The raw material was subjected to acid treatment in the same manner as in Example 2(1), except that instead of the hydrochloric acid-calcium chloride aqueous solution, a hydrochloric acid-magnesium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, magnesium chloride concentration 4 mol / L) or a hydrochloric acid-ammonium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, ammonium chloride concentration 5.56 mol / L) was used. However, in the hydrochloric acid-ammonium chloride aqueous solution, the immersion time was extended from 18 hours (Example 2) to 66 hours. Subsequently, the acid-treated sample (herbaceous fiber material) was subjected to washing and wet-pulverization in the same manner as in Example 2(2).

[0097] (2) Measurement of enzymatic saccharification rate The sample (wet-pulverized product) prepared as above was subjected to an enzymatic saccharification reaction in the same manner as in (4) of Example 2, and the enzymatic saccharification rate of the glucan was measured. As a control, the same treatment was carried out using 1 mol / L hydrochloric acid instead of the hydrochloric acid-magnesium chloride aqueous solution and the hydrochloric acid-ammonium chloride aqueous solution.

[0098] (3) Results As a result, as shown in Table 6, in the treatment areas with hydrochloric acid-magnesium chloride aqueous solution and hydrochloric acid-ammonium chloride aqueous solution, the saccharification rate of total glucan increased by 1.9 times and 1.6 times, respectively, compared to the control. This suggests that changing the type of "electrolyte other than hydrochloric acid that liberates chloride ions in water" contained in the mixed aqueous solution used for acid treatment also has the effect of improving the enzymatic saccharification rate of glucan.

[0099] [Table 6] *Calculated as [amount of glucan converted from the amount of free glucose / total amount of glucan in the raw material] x 100 (%).

[0100] (Example 6) Wet grinding test with added polysaccharide Rice straw powder (fineness of grinding: 4 mm or less, moisture content: 9.7%) was used as the herbaceous fiber raw material. Liquid-phase processing and wet-milling with the addition of different polysaccharides were performed, and the apparent volume of the precipitates was measured. The polysaccharides used were chitosan (Chitosan 100, Fujifilm Wako Pure Chemical Industries), tamarind seed gum (Tamarind Gum (derived from tamarind seeds), Tokyo Chemical Industry Co., Ltd.), and gellan gum (Gellan Gum, Fujifilm Wako Pure Chemical Industries).

[0101] (1) Acid treatment (liquid phase treatment) test and wet grinding treatment test The above raw materials were subjected to acid treatment and water washing in the same manner as in (1) and (2) of Example 2. Next, ion-exchanged water (polysaccharide-free group), or chitosan, tamarind seed gum, or gellan gum was added to the sample (herbaceous fiber material) to a final concentration of 0.2% (w / v), and then wet-pulverized in the same manner as in (2) of Example 2. The control group was treated in the same manner, except that the acid treatment was performed using a calcium chloride aqueous solution (4 mol / L) instead of the hydrochloric acid-calcium chloride aqueous solution.

[0102] (2) Measurement of sediment volume and its results The volumes of the precipitates from the samples (wet-pulverized products) prepared as described above were measured and compared using the method in Example 2(3). As a result, as shown in Table 7, the apparent volumes of the precipitates in the polysaccharide-free group and the groups with chitosan, tamarind seed gum, and gellan gum added were 4.3-fold, 2.7-fold, 4.3-fold, and 4.1-fold, respectively, compared to the control group. This demonstrates that wet-pulverization with the addition of polysaccharides also yields bulky precipitates, similar to the case of no polysaccharide addition.

[0103] By adding polysaccharides to a sample and then wet-milling it, the polysaccharides chemically or physically bond to at least a portion of the surface of the wet-milled material, allowing for surface modification and / or alteration. Surface modification or alteration with chitosan can impart properties such as antibacterial and anionic flocculation properties to the wet-milled material. In the case of tamarind seed gum and gellan gum, it is possible to impart properties such as altered dispersion properties and cellulolytic properties to the wet-milled material. In the case of other polysaccharides, it is expected to contribute to the modification of physical properties, altered biorecognition properties, imparting charge, and stabilizing material properties during freezing and drying.

[0104] [Table 7]

[0105] (Example 7) Wet grinding treatment using a ball mill Rice straw powder (fineness of 4mm or less, moisture content 9.7%) was used as a herbaceous fiber material, and liquid-phase treatment and wet-milling treatment using a ball mill were carried out, and the apparent volume of the precipitate of the wet-milled product was investigated.

[0106] (1) Acid treatment (liquid phase treatment) test 1 g of the above raw material was weighed into a plastic tube, and 8 mL of a hydrochloric acid-calcium chloride aqueous solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L) was added to bring the raw material into contact with the aqueous solution. At this point, the raw material was completely immersed in the aqueous solution. The tube was sealed and left to stand at room temperature for 18 hours to carry out acid treatment (liquid phase treatment). As a control, a similar treatment was carried out using a hydrochloric acid aqueous solution (1 mol / L) instead of the hydrochloric acid-calcium chloride aqueous solution.

[0107] (2) Wet grinding test The sample (herbaceous fiber material) after the above treatment was placed on a Büchner funnel equipped with filter paper and washed with a sufficient amount of ion-exchanged water. The washed solid was divided into two equal parts, each suspended in 10 mL of ion-exchanged water, and sealed in a 50 mL stainless steel jar along with a 2 cm diameter stainless steel ball. This was then wet-milled using a ball mill (Mixer Mill MM400, Verder Scientific, 15 strokes per second, 4 minutes).

[0108] (3) Measurement of sediment volume and its results The treated sample (wet-ground material) was added to a 50 mL measuring cylinder, made up to 50 mL with ion-exchanged water, and thoroughly suspended. The sample was then allowed to stand for 1 hour, and the apparent volume of the wet-ground material precipitate was measured. As shown in Table 8, the apparent volume of the precipitate in the hydrochloric acid-calcium chloride aqueous solution treatment group (average value of two samples) was 3.4 times that of the control group.

[0109] [Table 8]

[0110] (Example 8) Plate made from wet-ground material For the ball-milled rice straw-treated samples (two samples) prepared in Example 7, the sediment volume was measured, and 10 mL of the supernatant was removed to leave a 40 mL volume. The resulting solution was then centrifuged at 6,320 × g for 1 minute, after which the supernatant was discarded and the sediment was recovered. The recovered wet-milled material was dried at 60 °C to reduce the moisture content to approximately 80%, and then molded into a plate. Specifically, a portion of the dried wet-milled material was placed in a φ14 disk-shaped heat-press mold (1-6002-18, AS ONE Corporation) with an inner diameter of 14 mm. The mold was heated from room temperature to 160 °C at 20 MPa (equivalent to a 5.5 cm diameter), maintained at 160 °C for 20 minutes, and then air-cooled to room temperature. The resulting molded plate, shown in Figure 4, was obtained. The molded product measured 14 mm in diameter, 3 mm thick, and had a density of 1.24 g / cm. 3 This is what happened.

[0111] (Example 9) Sheet (nonwoven fabric) made from wet-ground material The Polytron-pulverized rice straw sample prepared in Example 4 was adjusted to a 1% (w / v) concentration (based on raw material). 40 mL of this was taken and centrifuged at 6,320 × g for 1 minute. The supernatant was discarded and the precipitate was recovered. The recovered wet-pulverized material was diluted to 20 mL with ion-exchanged water and stirred to form a suspension. 10 mL of this suspension was poured into a 10 cm diameter plastic dish and allowed to dry at 50 °C for at least 12 hours to obtain a sheet-like product (nonwoven fabric) (Figure 5). As shown in Figure 5, the defibrated herbaceous fibrous material bonded together to form a sheet.

[0112] (Example 10) Forming of plate using wet-ground material and evaluation of properties Rice straw powder (fineness of 4 mm or less, moisture content 9.7%) was used as the herbaceous fiber raw material, and liquid-phase processing and wet-pulverization processing were performed using a single-axis wet pulverizer. The resulting wet-pulverized material was compressed into a plate and dried, and the properties of the obtained sample were evaluated.

[0113] 1 kg of the rice straw powder was mixed with 2 L of a hydrochloric acid-calcium chloride solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L) in a plastic bag and left to stand at room temperature for 16 hours to obtain a herbaceous fiber material. As a control, the same amount of calcium chloride solution (calcium chloride concentration 4 mol / L) was used instead of the hydrochloric acid-calcium chloride solution, and the mixture was treated under the same conditions.

[0114] The treated sample (herbaceous fiber material) was neutralized with 25% (w / w) aqueous ammonia solution and then washed with tap water. The excess water was then squeezed out to obtain a wet solid, which was then wet-ground in a single-axis wet grinder (Shokusenki: Kobe Steel Engineering Co., Ltd.) to obtain 17.3 g (moisture content: 71.1%) of the "acid-treated ground sample." The control sample was treated in the same way as above, without the addition of aqueous ammonia solution, to obtain 19.7 g (moisture content: 69.1%) of the "control ground sample."

[0115] The acid-treated and control crushed samples obtained above were each placed in a 70mm x 70mm plate-making mold with a 69mm x 69mm cooking sheet (manufactured by ZHI JIN HOME Co., Ltd.) underneath. The mold was then pressurized at 10MPa for 5 minutes, and after wiping off any leaked liquid, it was dried at 105°C for 12 hours. The mold was then pressurized at 20MPa for 10 minutes, and the resulting plate-shaped sample was then removed from the mold.

[0116] The density of the obtained plate-shaped sample was measured by measuring its mass and volume, and then a 20 mm x 20 mm piece was prepared and its weight and thickness were measured. The piece was then immersed in 20 mL of distilled water at room temperature for 12 hours, removed, drained on a paper towel for 5 seconds, and its weight and thickness were measured again. The water absorption thickness swelling (TS) and water absorption (WA) were calculated using the following equations (I) and (II).

[0117]

number

[0118]

number

[0119] The results are shown in Table 9. The density of the acid-treated plate sample was 0.70 g / cm 3 The value of the control plate sample (0.58 g / cm 3 ) and it was confirmed that the samples were more consolidated than the acid-treated samples. The TS and WA values ​​were 10.1% and 85.2%, respectively, for the acid-treated plate samples, and 23.3% and 121%, respectively, for the control plate samples. These results confirmed that hydrochloric acid treatment produces stable molded products that are less likely to swell in water. [Table 9]

[0120] The plate-shaped sample prepared in the mold was torn by hand and then dry-pulverized in a blender (Force Mill, manufactured by Osaka Chemical Industry Co., Ltd.) for 10 seconds x 4 times. This dry-pulverized material (50 mg) was either directly or further wet-pulverized in the presence of zirconia beads as in Example 2, and then subjected to enzymatic saccharification as in Example 2 to evaluate the release rates of glucose and xylose. The amounts of glucose residues and xylose residues contained in the acid-treated pulverized sample and the control pulverized sample in this example were used as denominators when measuring the release rates.

[0121] The results are shown in Table 10. The glucose release rates for the acid-treated pulverized sample, the sample obtained by processing the same sample into a plate and then dry-pulverizing it (the acid-treated dry-pulverized sample), and the sample obtained by wet-pulverizing it with zirconia beads (the acid-treated wet-pulverized sample) were 79.0%, 45.4%, and 76.6%, respectively, and the xylose release rates were 66.4%, 42.2%, and 76.8%, respectively. The glucose release rates for the control pulverized sample, the sample obtained by processing the same sample into a plate and then dry-pulverizing it (the control dry-pulverized sample), and the sample obtained by wet-pulverizing it with zirconia beads (the control wet-pulverized sample) were 29.7%, 25.0%, and 30.9%, respectively, and the xylose release rates were 11.5%, 16.7%, and 24.5%, respectively. Thus, the acid-treated crushed sample before processing into plates showed high glucose and xylose release rates during enzymatic saccharification, whereas the values ​​decreased in the dry-crushed sample after processing into plates. Furthermore, wet-crushing significantly restored the glucose and xylose release rates. This increase in sugar release rate was limited in the control crushed sample. It became clear that by applying an appropriate crushing process after processing into plates, the material can be reused as a saccharification raw material.

[0122] [Table 10]

[0123] (Example 11) Production and saccharification of herbaceous fiber material 2.22 g of rice straw powder (finely ground to 4 mm or less, moisture content 9.7%) was placed in the bottom of a 200 mL glass bottle (mouth diameter × body diameter × height: φ47 × φ62 × 109 mm, Figure 6) along with a magnetic stirrer (30 mm long, φ5 mm). Four 10 mm thick, 30 mm long sponge pieces were attached to the inside of the bottle with double-sided tape. A 42 mm φ, 15 mm deep polypropylene dish was placed on top of the sponge pieces and held at a height of 70 mm from the bottom. 10 mL of a hydrochloric acid-calcium chloride solution (hydrochloric acid concentration 1 mol / L, calcium chloride concentration 4 mol / L) was added to the dish and the bottle was sealed with the lid. The bottle was placed on a magnetic stirrer and stirred at 20 rpm at room temperature for 3 days. The lid was then opened, the dish removed, and the post-vapor-phase-treated rice straw powder sample was collected. Approximately 1 g of the sample was weighed into a weighed aluminum dish, dried at 105°C for 18 hours, and the moisture content was measured, which was found to be 10.4%.

[0124] 55 mg of the gas-phase treated rice straw powder was weighed into four 2 mL plastic tubes. Two tubes were washed three times with 1.5 mL of ion-exchanged water, following the procedure in Example 2, to prepare washed samples. The remaining two tubes were used as unwashed samples. For the washed samples, zirconia beads (equivalent to 500 mg of 0.6 mm diameter beads and one 5 mm diameter bead) from Example 2 were added to each tube, and then ion-exchanged water was added to adjust the total weight of the samples to 1 g, as in Example 2. These samples were then wet-ground using a bead mill (acid-treated, washed samples). For the unwashed samples, 950 μL of ion-exchanged water was added to each tube (to adjust the pH), followed by the addition of zirconia beads, and then wet-ground using a bead mill (acid-treated, unwashed samples), following the procedure in Example 3. A control sample (untreated, unwashed sample) was prepared using rice straw powder before acid treatment, and subjected to the same wet-ground procedure as the acid-treated, unwashed samples.

[0125] These wet-ground samples were transferred to 15 mL plastic tubes, and after adding water, the precipitate volume was measured according to the method described in Example 2. The results are shown in Table 11. The values ​​in the table are the average of the results for two samples under each condition. The volume was 2.85 mL for the acid-treated and washed sample, 2.5 mL for the acid-treated and unwashed sample, and 0.75 mL for the untreated and unwashed sample. Thus, it was confirmed that even gas-phase acid-treated samples in glass bottles formed bulky suspensions after wet-ground. The hydrochloric acid-calcium chloride aqueous solution used in the non-contact reaction can be heated to evaporate and separate the hydrogen chloride gas and water, thereby increasing the calcium chloride concentration in the aqueous solution and allowing the calcium chloride to be reused or recycled.

[0126] [Table 11] *Values ​​are the average of two samples

[0127] The samples obtained after the bead-crushing treatment (acid-treated and washed sample, acid-treated and unwashed sample, and untreated and unwashed sample) were subjected to enzymatic saccharification and the amounts of free glucose and free xylose were measured by the method of Example 2. Using these values, the glucose release rate and xylose release rate relative to the total glucan and total xylan amounts in the rice straw powder before acid treatment were calculated as the average of the results for two samples under each condition.

[0128] The results are shown in Table 12. The glucose release rates for the acid-treated and washed samples, the acid-treated and unwashed samples, and the untreated and unwashed samples were 69.5%, 76.0%, and 35.0%, respectively, and the xylose release rates were 46.9%, 110%, and 11.6%, respectively. These results confirm that the samples obtained by gas-phase acid treatment exhibited a high saccharification rate. Furthermore, the unwashed samples exhibited a higher sugar recovery rate than the washed samples. The unwashed samples contained functional components such as xylooligosaccharides, which are partial hydrolyzates of xylan, due to the pH adjustment achieved by adding water without washing. Therefore, minimizing washout during washing and controlling the effects of acid by removing hydrogen chloride through heating, adjusting the pH from the gas phase with ammonia, or adjusting the pH so that the wash water remains may enable the production of industrially useful materials with high sugar recovery rates and value as functional feed.

[0129] [Table 12] *Values ​​are the average of two samples

[0130] One gram of the vapor-phase-treated rice straw powder obtained above was ball milled at 15 strokes per second for 4 minutes using the method described in Example 1. After drying the resulting fine powder at 105°C, 500 mg was transferred to a 15 mL plastic tube, and 12 mL of ion-exchanged water was added and vortexed for 5 minutes. The resulting powder was then centrifuged at 10,000 × g for 5 minutes, and the supernatant was aspirated and removed for washing. The entire residue was transferred to a weighed 5 cm aluminum dish, dried at 105°C, and weighed to obtain 415 mg of washed residue. 20 mg of each of the pre-washed sample (rice straw powder after vapor-phase treatment) and the post-washed sample (washed residue) was weighed, and the glucan and xylan contents were measured using the method described in Example 1.

[0131] The results are shown in Table 13. The glucan and xylan contents of the sample before washing were 164 mg and 53 mg, respectively, and those of the sample after washing were 151 mg and 37 mg, respectively. Thus, the glucan content relative to the total glucan and xylan contents in the rice straw powder before acid treatment increased from 32.8% to 36.3%, and the xylan content decreased from 10.6% to 8.92% (a decrease of 15.8%). These results demonstrate that acid treatment in a gas-phase process produces a herbaceous fiber material in which xylan solubilization is significantly suppressed. The herbaceous fiber material according to the present disclosure combines seemingly contradictory structural properties—improved defibration ability and polysaccharide retention—and possesses unprecedented functionality. Its industrial utility is high even before wet-milling.

[0132] [Table 13]

[0133] (Example 12) Molding of rod-shaped material using wet-ground material 1.00 kg of the acid-treated crushed sample (moisture content: 74.3%) prepared by the method described in Example 10 was weighed and packed into a mold for a bar. The mold was divided into three sections: a bottom section, a middle section, and an upper section. First, a cooking sheet (manufactured by ZHI JIN HOME Co., Ltd.) was laid on the bottom and sides of the tapered section of the bottom mold, and the sample was placed on top of it and pressed down by hand. Once the bottom mold was filled, a middle mold was installed and the sample was similarly packed into the middle section. Once the middle section was filled to its highest position, a silicone sheet was placed on top and the upper mold was set on top. Next, the entire mold was pressurized at 10 MPa for 10 minutes, and then dried at 105°C for 72 hours. Finally, the mold was returned to room temperature and further pressurized at 20 MPa for 5 minutes. The sample was then removed from the mold to obtain a bar-shaped molded product.

[0134] A photograph of the molded product is shown in Figure 7. The size of the molded product is 5 mm in height at the bottom + 29 mm at the tapered part, the bottom surface length x width: 66 mm x 180 mm, the top surface length x width: 52 mm x 165 mm, the weight is 289 g, and the density is 0.64 g / cm3 By molding into a rod shape, it was possible to create a structure suitable for storing the wet-ground material. In this way, it was confirmed that rod-shaped molded products could be produced using the acid-treated ground sample.

[0135] Although the embodiments and examples of the present disclosure have been described in detail above, the specific configurations are not limited to these, and design changes that do not deviate from the gist of the present disclosure are included in the present disclosure.

Claims

1. An acid treatment process in which a herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or contacted with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water, at a temperature substantially between 10°C and 50°C; a step of washing and / or adjusting the pH of the treated product that has been subjected to the acid treatment step; and Compared with the composition of the raw herbaceous fiber raw material, the glucan content (based on the dry matter, weight %) is reduced by 30% or less, and the xylan content (based on the dry matter, weight %) is reduced by 5% or more and 50% or less, The "content" of glucan or xylan is the weight ratio (%) of glucan or xylan to the dry mass of solids in the sample; The "reduction rate" of glucan or xylan is calculated by the following formula: The herbaceous fiber material is calculated by [(content before acid treatment - content after acid treatment) / content before acid treatment] x 100 (%), where "content after acid treatment" is the content in the solid residue obtained after washing the treated product that has undergone the acid treatment step.

2. The herbaceous fiber material according to claim 1, characterized in that the mixed aqueous solution contains one or more electrolytes selected from calcium chloride, magnesium chloride, and ammonium chloride dissolved therein as electrolytes other than hydrochloric acid that liberates chloride ions in water, or contains a solute substantially equivalent to that of an aqueous solution in which the electrolytes are dissolved.

3. 2. The herbaceous fiber material according to claim 1, wherein the herbaceous fiber raw material is one or more selected from the group consisting of rice straw, wheat straw, corn stover, sugarcane bagasse, sugarcane trash, Miscanthus sinensis, Miscanthus sacchariflorus, Erianthus, sorghum, Napier grass, Judea japonica, Danchiku, and hemp.

4. A wet-ground product of the herbaceous fibrous material described in claim 1.

5. A wet-ground herbaceous fibrous material as described in claim 4, produced by adding one or more polysaccharides selected from the group consisting of chitosan, xyloglucan, carboxymethylcellulose sodium salt, alginate, galactomannan, gellan gum, carrageenan, and (1-3), (1-4)-β-glucan to the treated material that has undergone the acid treatment step, and then wet-grounding the mixture.

6. 5. The wet-ground herbaceous fiber material according to claim 4, wherein at least a portion of the surface of the wet-ground material has been modified and / or altered.

7. The wet-ground herbaceous fibrous material according to claim 4, characterized in that it contains wet-ground material having a particle size of less than 1 μm.

8. an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a step of washing and / or adjusting the pH of the treated product that has been subjected to the acid treatment step; A method for producing the herbaceous fiber material according to claim 1, comprising:

9. an acid treatment step in which the herbaceous fiber raw material is treated in a hydrogen chloride gas atmosphere or brought into contact with a mixed aqueous solution containing hydrochloric acid and an electrolyte other than hydrochloric acid that liberates chloride ions in water at a temperature substantially between 10°C and 50°C; a wet-pulverization step in which the treated product that has been subjected to the acid treatment step is subjected to a wet-pulverization step; A method for producing the wet-ground herbaceous fibrous material according to claim 4, comprising:

10. 10. The method according to claim 8 or 9, wherein the mixed aqueous solution dissolves one or more electrolytes selected from calcium chloride, magnesium chloride, and ammonium chloride as an electrolyte other than hydrochloric acid that liberates chloride ions in water, or the mixed aqueous solution contains a solute substantially equivalent to that of an aqueous solution in which the electrolyte is dissolved.

11. 10. The manufacturing method according to claim 8 or 9, wherein the herbaceous fiber raw material is at least one selected from the group consisting of rice straw, wheat straw, corn stover, sugarcane bagasse, sugarcane trash, Miscanthus sinensis, Miscanthus sacchariflorus, Erianthus, sorghum, Napier grass, Judea japonica, Danchiku, and hemp.

12. The method according to claim 9, wherein in the wet-grinding step, one or more polysaccharides selected from the group consisting of chitosan, xyloglucan, carboxymethylcellulose sodium salt, alginate, galactomannan, gellan gum, carrageenan, and (1-3),(1-4)-β-glucan are added to the treated product that has been subjected to the acid treatment step.

13. The method according to claim 9, further comprising the step of modifying and / or altering at least a portion of the surface of the wet-ground material.

14. The method according to claim 9, further comprising a step of separating and recovering a fraction mainly composed of wet-ground material having a particle size of less than 1 μm from the wet-ground material obtained in the wet-ground step.

15. A resin, plastic, rubber, ink or paint characterized by containing a wet-ground herbaceous fiber material according to any one of claims 1 to 3 or a wet-ground herbaceous fiber material according to any one of claims 4 to 7, or a fraction thereof, or a modified and / or altered product thereof.

16. A paper, nonwoven fabric, fiber, seedling pot, board or three-dimensional molded product, characterized by containing the herbaceous fiber material according to any one of claims 1 to 3 or the herbaceous fiber material according to any one of claims 4 to 7, or a fraction thereof, or a modified and / or altered product thereof.

17. A saccharified raw material or feed characterized by containing a wet-ground herbaceous fiber material according to any one of claims 1 to 3 or a herbaceous fiber material according to any one of claims 4 to 7, or a fraction thereof, or a modified and / or altered product thereof.

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