Shatterproof agent containing microfibrillary cellulose

Abstract

This invention provides a splatter inhibitor that uses cellulose-derived materials, has a good splatter-preventing effect, is less prone to gelation even when stored at high concentrations, can be easily dispensed with relatively weak stirring force when diluted for use, and reduces the color difference between sprayed and unsprayed areas. [Solution] A scattering prevention agent is prepared using microfibril cellulose with an average fiber width greater than 1.0 μm, a solvent, and a coloring agent. The microfibril cellulose may be chemically modified microfibril cellulose.

Description

Technical Field

[0001] The present invention relates to an anti-scattering agent containing microfibrillated cellulose and a solvent.

Background Art

[0002] Flying sand from the ground surface and dust scattered from construction sites, mining sites for metals, etc., reclamation sites, construction sites, waste disposal sites, various factories, etc. have an adverse impact on the working environment and the surrounding environment. Therefore, at locations where dust can be generated, dust scattering prevention measures are taken by spraying water or covering with a sheet, net, etc. In addition, spraying of a liquid dust scattering prevention agent may also be performed.

[0003] For example, Patent Document 1 discloses a dust scattering prevention agent containing a solvent and fibrous cellulose having a fiber width of 1000 nm or less, and it is disclosed that a dust scattering prevention effect can be obtained by spray coating (spray painting) this on an object generating dust.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 describes an example in which an aqueous dispersion of 0.4% by mass fine fibrous cellulose (CNF) was used as a splash suppressant and sprayed using a commercially available spray bottle. The inventors investigated and found that the splash suppressant described in Patent Document 1 can be sprayed with a spray bottle immediately after the production of fine fibrous cellulose (not long after strong dispersion treatment such as a high-pressure homogenizer or wet atomization device), but as time passes after production, gelation progresses, and strong stirring or strong dispersion treatment is required for redispersion before use. If the dispersion force before use is weak, gel-like clumps remain, clogging the spray bottle, or clumps remain at the bottom of the spray bottle, making it difficult to discharge the entire amount. Furthermore, this tendency was even more pronounced when the solution was stored at a higher concentration (e.g., 2% by mass) and then diluted before use. Considering the costs of transporting and storing the anti-scattering agent, it would be desirable to prepare a high-concentration anti-scattering agent in advance and dilute it at the site where the agent will be used. However, such sites often lack equipment capable of strong stirring or strong dispersion treatment, making it difficult to use the anti-scattering agent described in Patent Document 1 by storing it at a high concentration and diluting it at the site. Furthermore, when the anti-scattering agent described in Patent Document 1 is sprayed onto an object and dried, it forms a white film, resulting in a large color difference between the sprayed and unsprayed areas, which degrades the appearance.

[0006] This invention uses cellulose-derived materials and is less prone to gelling even when stored at high concentrations, and when used The objective is to provide a drift suppressant that can be dispensed smoothly with relatively weak stirring force even when diluted, and that reduces the color difference between sprayed and unsprayed areas. [Means for solving the problem]

[0007] As a result of diligent research, the present inventors have found that by using microfibril cellulose with an average fiber width greater than 1.0 μm as a scattering inhibitor, it is possible to produce a scattering inhibitor that maintains the same scattering inhibitory effect as the scattering inhibitor of Patent Document 1, while being less prone to gelation even when stored at high concentrations, and which can be easily dispensed by gentle stirring when diluted from a high concentration to a concentration suitable for use. The present invention is not limited to the following, but includes the following:

[0008] (1) A dust suppressant containing the following (A) to (C). (A) Microfibril cellulose having an average fiber width greater than 1.0 μm and a transmittance of 60% or less of light at a wavelength of 660 nm as a 1.0 mass% aqueous dispersion. (B) Solvent (C) A coloring agent for reducing the color difference between the object to which the anti-scattering agent is sprayed and the sprayed anti-scattering agent. (2) The anti-scattering agent according to (1), wherein the microfibril cellulose is chemically modified microfibril cellulose. (3) The anti-scattering agent according to any one of (1) to (2), characterized in that the coloring agent contains at least one selected from black dye, lignin, and ferrous sulfate. (4) A method for preventing scattering, comprising spraying a scattering prevention agent onto an object to be prevented from scattering, the scattering prevention agent comprising microfibril cellulose having an average fiber width greater than 1.0 μm and a transmittance of 60% or less of light at a wavelength of 660 nm as a 1.0 mass% aqueous dispersion, a solvent, and a coloring agent, A method for preventing scattering, characterized in that the blue color change rate (ΔB), expressed by the following formula, is 70% or less.

[0009] The rate of change in blue color (ΔB) = |(blueness of the object before spraying - blueness of the object after spraying) / (blueness of the object before spraying the blank solution - blueness of the object after spraying the blank solution)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that no coloring agent is added.) [Effects of the Invention]

[0010] The anti-scattering agent of the present invention has the advantage of having a good anti-scattering effect, being less prone to gelation even when stored at high concentrations, and being able to be easily dispensed by gentle stirring when diluting from a high concentration to a concentration suitable for use. Fine-diameter cellulose fibers are generally produced by wet defibration of pulp and are often shipped in slurry form. In this case, transporting and storing at low concentrations is costly, so it is more cost-effective to make it a slurry at the highest possible concentration. Compared to conventional anti-scattering agents using cellulose-derived materials, the anti-scattering agent of the present invention is less prone to gelation even when stored at high concentrations, and requires gentle stirring when redispersing during dilution. Therefore, it is cost-effective and can be easily diluted and used even in sites where there is no equipment for strong stirring, thus improving on-site workability. [Modes for carrying out the invention]

[0011] This invention relates to a splash suppressant comprising microfibril cellulose (hereinafter referred to as "MFC") having an average fiber width greater than 1.0 μm and a solvent. This invention is based on the discovery that by using microfibril cellulose with an average fiber width greater than 1.0 μm as a splash suppressant, it is possible to achieve a splash suppressant effect while being less prone to gelation even when stored at high concentrations, and when diluting from a high concentration to a concentration suitable for use, it can be easily dispensed by gentle stirring.

[0012] <mfc> MFCs are fibers obtained by moderately beating or defibrillating cellulose fibers using a refiner or the like to create fibrillation. MFCs include a variety of fibers, from those with a surface fluffiness of cellulose microfibrils to those defibrillated to a fiber width on the submicron order, due to the moderate beating or defibrillation process. Unlike cellulose nanofibers (hereinafter referred to as "CNF"), which are highly defibrillated to a nanoscale fiber width (for example, an average fiber width of 1000 nm or less), MFCs include fibers with a fiber width on the micron order.

[0013] The average fiber width of the MFC used in this invention is greater than 1.0 μm. More preferably, the average fiber width is 3.0 μm or more, and even more preferably 5.0 μm or more. By using an MFC that has undergone moderate fibrillation to maintain a certain average fiber width as a scattering suppressant, it becomes possible to provide a scattering suppressant that is less likely to gel even when stored at high concentrations, and that can be easily dispensed even with weak stirring force when redispersing before use. The upper limit of the average fiber width is not particularly limited, but is approximately 35.0 μm or less, more preferably 30.0 μm or less, and even more preferably approximately 29.0 μm or 25.0 μm.

[0014] The average fiber length of MFCs is not particularly limited, but is preferably 25 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. The upper limit of the average fiber length is not particularly limited, but is preferably 3000 μm or less, more preferably 1500 μm or less, and even more preferably 1000 μm or less.

[0015] The average fiber width and average fiber length of MFCs can be measured by the following method: A 300 mL aqueous dispersion of MFC diluted to contain 0.1 g of solids was subjected to an image-based fiber analyzer (product name: L&W Fiber Tester Plus, manufactured by ABB) and measured for 300 seconds to determine the length-weighted average fiber width and average fiber length (n=2). The measurement was performed after setting the Max value of Fines Limit to 0 and the Min value of Length class 1 to 0 on the Sample type screen where the measurement conditions are defined.

[0016] The aspect ratio of the MFC is preferably 5 or higher, and more preferably 10 or higher. While there is no particular upper limit to the aspect ratio, it is preferably 1000 or less, more preferably 100 or less, and even more preferably 50 or less. Having an aspect ratio within this range offers the advantages of being less prone to gelation when stored at high concentrations and being easily redispersible even with relatively weak stirring forces. The aspect ratio can be calculated using the following formula: Aspect ratio = Average fiber length (μm) / Average fiber width (μm) The cellulose fibers used as raw materials for obtaining MFCs are not particularly limited, but examples include those derived from plants, animals (e.g., sea squirts), algae, and microorganisms (e.g., Acetobacter). Examples of plant-derived materials include cellulose fibers derived from wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, and pulp (unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), unbleached softwood sulfite pulp (NUSP), bleached softwood sulfite pulp (NBSP), thermomechanical pulp (TMP), dissolved softwood pulp, dissolved hardwood pulp, recycled pulp, waste paper, etc.). Any one of these may be used, or two or more may be used in combination. Among these, cellulose fibers derived from plants or microorganisms are preferred, plant-derived cellulose fibers are more preferred, and wood-based pulp-derived cellulose fibers are even more preferred.

[0017] The average fiber width of the cellulose fiber used as the raw material is not particularly limited. In the case of softwood kraft pulp, which is a common pulp, it is about 30 to 60 μm, and in the case of hardwood kraft pulp, it is about 10 to 30 μm. In the case of other pulps, those经过一般精制的 are about 50 μm. For example, when using pieces several centimeters in size such as chips, it is preferable to perform mechanical treatment with a defibrator such as a refiner or a beater, adjust in advance so that the average fiber width becomes about 50 μm, and then use it as the raw material for MFC.

[0018] <Fibrillation> By appropriately beating or defibrating the cellulose fiber used as the raw material for MFC, MFC, which is a fibrillated cellulose fiber, can be obtained. The beating or defibrating in fibrillation is preferably carried out wet (that is, in the form of a dispersion with water or the like as the dispersion medium) using devices such as a disk type, conical type, or cylinder type refiner, a high-speed defibrator, a shear type stirrer, a colloid mill, a high-pressure jet disperser, cavitation, a beater, a PFI mill, a kneader, a disperser, etc., but it is not particularly limited to these devices, and any device that imparts a mechanical defibrating force wet may be used.

[0019] When performing fibrillation wet, first, a dispersion or slurry of the cellulose fiber used as the raw material is prepared. The solid content concentration in the dispersion or slurry of the cellulose fiber to be subjected to fibrillation is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and further preferably 1.0 mass% or more. As the upper limit of the concentration, 40 mass% or less is preferable, 30 mass% or less is more preferable, 10 mass% or less is more preferable, and 8 mass% or less is more preferable. The dispersion medium is preferably water.

[0020] The pH of the dispersion or slurry of cellulose fibers to be fibrillated is preferably 7.0 or lower, more preferably 6.0 or lower, and even more preferably 5.0 or lower. The lower limit of pH is not particularly limited, but is usually 2.0 or higher, preferably 3.0 or higher, and more preferably 3.5 or higher. pH can be adjusted by adding an acid such as hydrochloric acid.

[0021] Before preparing the dispersion or slurry for fibrillation, the cellulose fibers to be used as raw materials may be dried and pulverized beforehand. Then, the dry-pulverized raw materials may be dispersed in a dispersion medium and subjected to fibrillation (wet method). The apparatus used for dry-pulverizing the raw materials is not particularly limited, and examples include impact mills such as hammer mills and pin mills, medium mills such as ball mills and tower mills, and jet mills.

[0022] <Chemical modification> The MFC used in the present invention may be a chemically modified MFC, which is cellulose that has been chemically modified. Chemically modified MFCs tend to disperse more uniformly in a solvent and have a higher scattering prevention effect compared to unmodified MFCs. Chemical modification may be performed on the raw material cellulose fibers in advance, and then these (i.e., the chemically modified cellulose fibers) may be subjected to the fibrillation (i.e., appropriate beating or defibrillation) described above to produce chemically modified MFCs, or unmodified cellulose fibers may be fibrillated to produce MFCs, and then the MFCs may be subjected to chemical modification to produce chemically modified MFCs. Since fibrillation proceeds more easily with chemically modified cellulose, among the above methods, it is preferable from the standpoint of energy cost to chemically modify the raw material cellulose fibers in advance to produce chemically modified cellulose fibers, and then subject these to fibrillation to produce chemically modified MFCs.

[0023] The method of chemical modification is not particularly limited, but examples include oxidation, etherification, phosphorylation, esterification, silane coupling, fluorination, and cationization. Among these, oxidation (carboxylation), etherification, esterification, and cationization are preferred from the viewpoint of easy uniform dispersion in the solvent, with oxidation being particularly preferred. These will be explained in detail below.

[0024] <Chemical Modification - Oxidation> One example of chemical modification is oxidation (carboxylation), which involves introducing carboxyl groups into cellulose chains. In this specification, carboxylated cellulose fibers and carboxylated MFCs may be referred to as "oxidized cellulose fibers" and "oxidized MFCs," respectively. Furthermore, oxidized cellulose fibers and oxidized MFCs may be collectively referred to as "oxidized cellulose." Oxidized cellulose may be commercially available, or it may be produced by oxidizing the above-mentioned cellulose raw materials using known methods. The amount of carboxyl groups is preferably 0.1 to 2.5 mmol / g, more preferably 0.6 mmol / g to 2.5 mmol / g, and even more preferably 1.0 mmol / g to 2.0 mmol / g, relative to the oven-dry mass of the oxidized cellulose fibers or oxidized MFCs. The amount of carboxyl groups can be measured by the following method: Prepare 60 mL of a 0.5% by mass slurry (aqueous dispersion) of oxidized cellulose sample. Add 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5. Then, add 0.05 N sodium hydroxide aqueous solution dropwise until the pH reaches 11, and measure the electrical conductivity. From the amount of sodium hydroxide consumed during the neutralization stage of the weak acid, where the change in electrical conductivity is gradual (a), calculate the following using the formula below: Carboxyl group content [mmol / g] = a [mL] × 0.05 / oxidized cellulose sample content Amount [g].

[0025] The amount of carboxyl groups in oxidized cellulose fibers before fibrillation is usually the same as the amount of carboxyl groups in oxidized cellulose fibers (oxidized MFCs) after fibrillation.

[0026] One example of an oxidation method is to oxidize a cellulose raw material in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromide, iodide, and mixtures thereof. This oxidation reaction selectively oxidizes the primary hydroxyl group at the C6 position of the glucopyranose ring on the surface of the cellulose, yielding cellulose having an aldehyde group and a carboxyl group (-COOH) or carboxylate group (-COO-) on its surface (carboxylated (oxidized) cellulose). The concentration of the cellulose raw material during the reaction is not particularly limited, but 5% by mass or less is preferred.

[0027] An N-oxyl compound is a compound capable of generating a nitroxyl radical. Any compound that promotes the desired oxidation reaction can be used as the N-oxyl compound. Examples include 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and its derivatives (e.g., 4-hydroxyTEMPO). The amount of N-oxyl compound used is not particularly limited, as long as it is a catalytic amount that can oxidize the cellulose raw material. For example, 0.01 to 10 mmol is preferred, 0.01 to 1 mmol is more preferred, and 0.05 to 0.5 mmol is even more preferred, per 1 g of oven-dried cellulose raw material. Also, about 0.1 to 4 mmol / L relative to the reaction system is preferable.

[0028] Bromides are compounds containing bromine, and examples include alkali metal bromides that can dissociate and ionize in water. Iodides are compounds containing iodine, and examples include alkali metal iodides. The amount of bromide or iodide used can be selected within a range that promotes the oxidation reaction. The total amount of bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol per 1 g of oven-dried cellulose raw material.

[0029] As an oxidizing agent, known substances can be used, such as halogens, hypohalous acids, halogenous acids, perhalous acids or their salts, halogen oxides, and peroxides. Among these, sodium hypochlorite is preferred because it is inexpensive and has a low environmental impact. The appropriate amount of oxidizing agent to use is, for example, 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, even more preferably 1 to 25 mmol, and most preferably 3 to 10 mmol per 1 g of oven-dried cellulose raw material. Also, for example, 1 to 40 mol per 1 mol of N-oxyl compound is preferred.

[0030] The oxidation process of cellulose raw materials proceeds efficiently even under relatively mild conditions. Therefore, the reaction temperature may be in the range of 4 to 40°C, or even at room temperature of about 15 to 30°C. As the reaction progresses, carboxyl groups are generated in the cellulose chain, causing a decrease in the pH of the reaction solution. To ensure the oxidation reaction proceeds efficiently, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution at 8 to 12, preferably 10 to 11. Water is preferred as the reaction medium due to its ease of handling and low likelihood of side reactions. The reaction time in the oxidation reaction can be appropriately set according to the degree of oxidation, and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours.

[0031] Furthermore, the oxidation reaction may be carried out in two stages. For example, by filtering out the oxidized cellulose after the first stage of the reaction and then oxidizing it again under the same or different reaction conditions, the oxidation can be carried out efficiently without being inhibited by the salt produced as a by-product in the first stage of the reaction.

[0032] Another example of an oxidation method is to bring a cellulose raw material into contact with an ozone-containing gas. This oxidation reaction oxidizes at least the hydroxyl groups at positions 2 and 6 of the glucopyranose ring, and also causes decomposition of the cellulose chain. The ozone concentration in the ozone-containing gas is preferably 50 to 250 g / m³, and more preferably 50 to 220 g / m³. The amount of ozone added to the cellulose raw material is preferably 0.1 to 30 parts by mass, and more preferably 5 to 30 parts by mass, based on 100 parts by mass of the solid content of the cellulose raw material. The ozone treatment temperature is preferably 0 to 50°C, and more preferably 20 to 50°C. The ozone treatment time is not particularly limited, but is preferably about 1 to 360 minutes, and more preferably about 30 to 360 minutes. When the ozone treatment conditions are within these ranges, it is possible to prevent excessive oxidation and decomposition of the cellulose raw material, and a good yield of oxidized cellulose can be obtained.

[0033] After ozone treatment, a follow-up oxidation treatment may be performed using an oxidizing agent. The oxidizing agent used in the follow-up oxidation treatment is not particularly limited, but examples include chlorine compounds such as chlorine dioxide and sodium chlorite, as well as oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. For example, a follow-up oxidation treatment can be performed by dissolving these oxidizing agents in water or a polar organic solvent such as alcohol to prepare an oxidizing agent solution, and then immersing the cellulose raw material in the solution.

[0034] The amount of carboxyl groups in oxidized cellulose fibers or oxidized MFCs can be adjusted by controlling the reaction conditions, such as the amount of oxidizing agent added and the reaction time.

[0035] <Chemical modification - etherification> One example of chemical modification is etherification. Examples of etherification include CM modification, which involves ether bonding of carboxymethyl groups (hereinafter, "carboxymethyl" is referred to as "CM") to cellulose chains; methylation, which involves ether bonding of methyl groups; ethylation, cyanoethylation, hydroxyethylation, hydroxypropylation, ethylhydroxyethylation, and hydroxypropylmethylation using ethyl groups. Among these, CM modification will be described below as an example. In this specification, CM-modified cellulose fibers and CM-modified MFCs may be referred to as "CM-modified cellulose fibers" and "CM-modified MFCs." Commercially available CM-modified cellulose fibers may be used, or they may be produced by CM-modifying the above-mentioned cellulose raw material using a known method. The degree of CM substitution of cellulose is preferably 0.01 to 0.50. The upper limit is preferably 0.40 or less, and more preferably 0.35 or less. If the degree of CM substitution exceeds 0.50, dissolution in water becomes more likely, and the fiber form cannot be maintained in water. Furthermore, the degree of CM substitution is more preferably 0.02 or more, more preferably 0.05 or more, and more preferably 0.10 or more. The degree of CM substitution can be adjusted by controlling the amount of CM agent added, the amount of mercerizing agent, and the composition ratio of water to organic solvent.

[0036] The degree of CM substitution (also called the degree of etherification) indicates the proportion of hydroxyl groups in glucose residues constituting cellulose that are substituted with CM ethers (the number of CM ethers per glucose residue). The degree of CM substitution is sometimes abbreviated as DS. The method for measuring the degree of CM substitution is as follows: Accurately weigh approximately 2.0 g of the sample and place it in a 300 mL stoppered Erlenmeyer flask. Add 100 mL of methanol nitrate (a solution of 100 mL of special grade concentrated nitric acid added to 1000 mL of methanol) and shake for 3 hours to convert the salt-type CM-modified cellulose to the hydrogen-type CM-modified cellulose. Accurately weigh 1.5 to 2.0 g of the hydrogen-type CM-modified cellulose (dry) and place it in a 300 mL stoppered Erlenmeyer flask. Wet it with 15 mL of 80% methanol, add 100 mL of 0.1 N-NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, back titrate the excess NaOH with 0.1 N-H2SO4 and calculate the degree of CM substitution (DS) using the following formula. A = [(100 × F' - 0.1N - H2SO4 (mL) × F) × 0.1] / (Oven-dry mass of hydrogenated CM cellulose (g)) CM substitution degree (DS)=0.162×A / (1-0.058×A) F': Factor of N-H2SO4 F: Factor of 0.1N-NaOH.

[0037] The DS in CM-modified cellulose fibers before fibrillation and the DS in CM-modified cellulose fibers after fibrillation (CM-modified MFCs) are usually the same.

[0038] The method for mercerizing a cellulose raw material is not particularly limited, but one example is to mercerize the cellulose raw material and then etherify it. Examples of solvents used in the CM reaction include water, alcohol (e.g., lower alcohol), or a mixture thereof. Examples of lower alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, and tertiary butanol. When using a mixed solvent, the mixing ratio of alcohols is usually about 60 to 95% by mass. The amount of solvent is usually about 3 to 20 times the mass of the cellulose raw material.

[0039] Mercellation is usually carried out by mixing a cellulose raw material with a mercellizing agent. Examples of mercellizing agents include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. The amount of mercellizing agent used is preferably 0.5 to 20 moles per anhydrous glucose residue of the cellulose raw material, more preferably 1.0 to 10 moles, and even more preferably 1.5 to 5.0 moles. The reaction temperature for mercellation is usually 0 to 70°C, preferably 10 to 60°C. The reaction time is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours.

[0040] The etherification reaction is usually carried out by adding a CM agent to the reaction system after mercerization. Examples of CM agents include sodium monochloroacetate. The amount of CM agent added is preferably 0.05 to 10.0 moles per glucose residue of the cellulose raw material, more preferably 0.5 to 5.0 moles, and even more preferably 0.8 to 3.0 moles. The reaction temperature is usually 30 to 90°C, preferably 40 to 80°C. The reaction time is usually 30 minutes to 10 hours, preferably 1 hour to 4 hours. The reaction mixture may be stirred as needed during the CM reaction.

[0041] <Chemical modification - esterification> Esterification can be cited as an example of chemical modification. As an example of esterification, phosphate esterification, which involves introducing phosphate groups into cellulose chains, is described below. As phosphate esterified cellulose fibers, commercially available products may be used, or they may be produced by phosphate esterifying the above-mentioned cellulose raw material using a known method. The degree of phosphate group substitution per glucose unit of cellulose is preferably 0.001 or more and less than 0.40. The degree of phosphate group substitution in phosphate esterified cellulose fibers before fibrillation and the degree of phosphate group substitution in phosphate esterified cellulose fibers (phosphate esterified MFCs) after fibrillation are usually the same.

[0042] Methods for phosphate esterification include mixing a powder or aqueous solution of a compound having a phosphate group with a cellulose raw material, and adding an aqueous solution of a compound having a phosphate group to a slurry of a cellulose raw material. Examples of compounds having a phosphate group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium phosphite, potassium phosphite, sodium hypophosphite, potassium hypophosphite, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium metaphosphate. One or more of these can be used in combination to introduce a phosphate group into the cellulose raw material. Of these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred from the viewpoint of high efficiency in introducing a phosphate group and ease of industrial application. Sodium dihydrogen phosphate and disodium hydrogen phosphate are particularly preferred. Furthermore, it is desirable to use the compounds having a phosphate group as aqueous solutions so that the reaction can proceed uniformly and the efficiency of introducing a phosphate group is high. The pH of an aqueous solution of a compound containing a phosphate group is preferably 7 or less because it increases the efficiency of phosphate group introduction, but a pH of 3 to 7 is preferable from the viewpoint of suppressing hydrolysis of the fibers.

[0043] One example of a method for producing phosphate-esterified cellulose is as follows: A compound having a phosphate group is added to a suspension of cellulose raw material with a solid content concentration of 0.1 to 10% by mass while stirring to introduce a phosphate group into the cellulose. When the cellulose raw material is 100 parts by mass, the amount of compound having a phosphate group added is preferably 0.2 to 500 parts by mass, and more preferably 1 to 400 parts by mass, as the amount of phosphorus element. In this case, in addition to the compound having a phosphate group, a powder or aqueous solution of a nitrogen-containing compound that exhibits basicity may also be mixed. "Exhibiting basicity" means that the aqueous solution turns pink to red in the presence of a phenolphthalein indicator, or the pH of the aqueous solution is greater than 7. As the nitrogen-containing compound that exhibits basicity, a compound having an amino group is preferred. Examples include, but are not limited to, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine. Among these, urea is preferred because it is low-cost and easy to handle. The amount of nitrogen-containing compound exhibiting basicity added is preferably 2 to 1000 parts by mass, and more preferably 100 to 700 parts by mass. The reaction temperature is preferably 0 to 95°C, and more preferably 30 to 90°C. The reaction time is not particularly limited, but is about 1 to 600 minutes, and more preferably 30 to 480 minutes. After dehydrating the resulting suspension of phosphate-esterified cellulose, it is preferable to heat-treat it at 100 to 170°C from the viewpoint of suppressing hydrolysis of cellulose. Furthermore, while water is present during the heat treatment, it is preferable to heat at 130°C or lower, preferably 110°C or lower, and after the water has been removed, it is preferable to heat-treat it at 100 to 170°C.

[0044] <Chemical Modification - Cationization> One example of chemical modification is cationization, which involves introducing a cationic group into the cellulose chain. Cationized cellulose contains cations such as ammonium, phosphonium, and sulfonium in its molecule. Among these, it is preferable to include a group containing ammonium, and more preferably to include a group containing quaternary ammonium.

[0045] The method of cationization is not particularly limited, but one example is a method in which a cationizing agent and a catalyst are reacted with a cellulose raw material in the presence of water and / or alcohol. Examples of cationizing agents include glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrialkylammonium hydrate (e.g., 3-chloro-2-hydroxypropyltrimethylammonium hydrate), or their halohydrin forms. By using any of these, cationized cellulose having a group containing a quaternary ammonium can be obtained. Examples of catalysts include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Examples of alcohols include alcohols having 1 to 4 carbon atoms. The amount of cationizing agent is preferably 5 to 800% by weight, more preferably 10 to 500% by weight, per 100% by weight of the cellulose raw material. The amount of catalyst is preferably 0.5 to 7% by weight, more preferably 1 to 3% by weight, per 100% by weight of the cellulose fibers. The amount of alcohol is preferably 50 to 50000% by weight, more preferably 100 to 500% by weight, per 100% by weight of the cellulose fibers.

[0046] The reaction temperature during cationization is typically 10 to 90°C, preferably 30 to 80°C. The reaction time is typically 10 minutes to 10 hours, preferably 30 minutes to 5 hours. The reaction mixture may be stirred during the cationization reaction as needed.

[0047] The degree of cation substitution per glucose unit in cationized cellulose can be adjusted by controlling the amount of cationizing agent added and the composition ratio of water to alcohol. The degree of cation substitution indicates the number of substituents introduced per glucose residue (glucopyranose ring) constituting cellulose. In other words, the degree of cation substitution is defined as "the number of moles of introduced substituents divided by the total number of moles of hydroxyl groups in the glucopyranose ring." Since pure cellulose has 3 replaceable hydroxyl groups per unit structure (glucopyranose ring), the theoretical maximum degree of cation substitution is 3 (minimum is 0).

[0048] The degree of cation substitution of cationized cellulose is preferably 0.01 to 0.40, more preferably 0.02 to 0.30, and even more preferably 0.03 to 0.20. The degree of cation substitution can be measured by the following method: After drying the sample (cationized cellulose), the nitrogen content is measured using a total nitrogen analyzer TN-10 (manufactured by Mitsubishi Chemical Corporation), and the degree of cationization is calculated using the following formula: Degree of cation substitution = (162 × N) / (1 - 151.6 × N) N: Nitrogen content.

[0049] <Transparency> The MFC used in this invention preferably has a transmittance (hereinafter referred to as "transparency") of light at a wavelength of 660 nm when dispersed in an aqueous dispersion with a concentration of 1.0 mass% of 60%, more preferably 50% or less, and even more preferably 45% or less. The lower limit is not particularly limited and may be 0% or higher. Transparency can be measured by the following method: An aqueous dispersion of MFC (solid content concentration 1.0 mass%) was prepared, and the transmittance of light at a wavelength of 660 nm was measured using a UV-VIS spectrophotometer UV-1800 (Shimadzu Corporation) with a square cell having a path length of 10 mm.

[0050] <Crystallization degree of cellulose type I> In the MFC used in this invention, the crystallinity of cellulose is preferably 50% or more of type I cellulose, and more preferably 60% or more. There is no particular upper limit, and it may be 100% or less. Natural cellulose is type I cellulose, and when MFC is unmodified, it usually exhibits type I cellulose. In the case of chemically modified MFC, in order to maintain type I cellulose crystals, it is preferable to use cellulose with a high degree of type I crystallinity as the raw material. The crystallinity of type I cellulose in the cellulose raw material when obtaining chemically modified MFC is preferably 70% or more, and more preferably 80% or more. The crystallinity of type I cellulose can be measured by the following method: The sample is placed on a glass cell and measured using an X-ray diffraction analyzer (product name: LabX XRD-6000, manufactured by Shimadzu Corporation). The degree of crystallinity is calculated using the method of Segal et al., with the diffraction intensity at 2θ = 10° to 30° of the X-ray diffraction pattern as the baseline, and calculated from the diffraction intensity of the 002 plane at 2θ = 22.6° and the diffraction intensity of the amorphous portion at 2θ = 18.5° using the following formula. Xc = (I002c - Ia) / I002c × 100 Xc = Degree of crystallinity of type I cellulose (%) I002c: 2θ = 22.6°, diffraction intensity of the 002 plane Ia: 2θ = 18.5°, diffraction intensity of the amorphous region.

[0051] <Solvent> The anti-scattering agent of the present invention comprises the above-mentioned MFC and a solvent. Considering the impact on the environment and its affinity with MFC, the solvent is preferably mainly composed of water. That is, it is preferable that the solvent contains 50% by mass or more water when the total solvent is considered to be 100% by mass. More preferably, it contains 70% by mass or more water, and even more preferably 90% by mass or more. The solvent may also be water only (100% by mass).

[0052] Examples of solvents other than water, but not limited to those listed above, include organic solvents. Examples of organic solvents include alcoholic solvents such as methanol, ethanol, 1-propanol, 2-propanol, isopropanol, n-butanol, isobutanol, salicylic alcohol, cinnamyl alcohol, beraryl alcohol, cinnabyl alcohol, diphenylmethanol, vanillyl alcohol, benzyl alcohol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 3-nitrile benzyl alcohol, 4-methylbenzyl alcohol, α-methylbenzyl alcohol, allyl alcohol, propagyl alcohol, phenethyl alcohol, hydroxybenzyl alcohol, and hydroxyphenethyl alcohol; ethylene glycol derivatives such as ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol acetate monoethyl ether; and diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether. Examples include: diacetone alcohol; pyrrolidone compounds such as 2-pyrrolidone, 3-pyrrolidone, N-alkyl-2-pyrrolidone (e.g., N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone), 5-alkyl-2-pyrrolidone (e.g., 5-methyl-2-pyrrolidone, 5-ethyl-2-pyrrolidone, 5-propyl-2-pyrrolidone), N-vinyl-2-pyrrolidone, and N-alkyl-3-pyrrolidone (e.g., N-methyl-3-pyrrolidone, N-ethyl-3-pyrrolidone, N-propyl-3-pyrrolidone); nitrogen-containing solvents such as formamide, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, and N,N-dimethylacetamide; and chlorine-based solvents such as chloroform, carbon tetrachloride, methylene chloride, trichloroethylene, or tetrachloroethylene.

[0053] <Shatterproof agent> The splash inhibitor of the present invention comprises the above-mentioned MFC, a solvent, and a coloring agent. The concentration of MFC in the splash inhibitor is preferably about 0.4 to 2.5% by mass, and more preferably about 0.5 to 1.5% by mass, at the time of use. However, as will be described later, the splash inhibitor of the present invention does not easily gel even when stored at high concentrations, and can be well dispersed with gentle stirring when diluted to an appropriate concentration at the time of use. Therefore, when transporting or storing before use, it may be stored at a higher concentration, for example, a concentration of MFC higher than 2.5% by mass, more preferably 3.0% by mass or higher.

[0054] The coloring agent included in the anti-scatter agent of the present invention is contained to reduce the color difference between the surface to which the anti-scatter agent is sprayed and the sprayed anti-scatter agent. Since the above-mentioned MFC forms a white film when sprayed on an object as an anti-scatter agent and dried, for example, if the object has a black or dark gray hue, the color difference will be large and only the sprayed area will stand out in color, resulting in a poor appearance. Therefore, it is important to include a coloring agent to reduce the color difference.

[0055] Various colorants can be selected and used to reduce such color differences depending on the chromaticity of the object, but it is preferable to include at least one selected from black dye, lignin, and ferrous sulfate.

[0056] As for the black dyes mentioned above, any commonly used black dyes can be used as appropriate, but those that interact with cellulose are preferred in order to stably interact with MFCs and be maintained on the sprayed surface for a long period of time. Examples of such dyes include Direct Paper Black (manufactured by Nippon Chemical Industrial Co., Ltd.), which is used as a paper filler.

[0057] The concentration of the coloring agent in the anti-scattering agent of the present invention is preferably 0.01 to 15 parts by mass, more preferably 0.05 to 10 parts by mass, and even more preferably 0.08 to 5 parts by mass, per 100 parts by mass of MFC in the anti-scattering agent. By including the coloring agent within this range, the effects of the present invention can be exhibited more effectively.

[0058] The anti-scattering agent of the present invention may contain components other than MFC, solvent, and colorant, to the extent that they do not impair the effects of the present invention. Examples of such components include surfactants, defoamers, antioxidants, stabilizers, and preservatives. When such components are included, the content of these components is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the total mass of the anti-scattering agent.

[0059] The dust suppressant of the present invention can be used to prevent the scattering of soil or sand scattered from the ground surface, dust scattered from construction sites, metal mining sites, land development sites, construction sites, waste disposal sites, various factories, and fine particles such as PM2.5. It can also be used to prevent the scattering of mulching materials used in agricultural fields.

[0060] Mulching materials are used to cover the soil surface of planted plants to prevent weed growth, drying due to moisture evaporation, and the occurrence of pests and diseases. Examples of mulching materials include artificial or inorganic materials such as vinyl sheets, woven fabrics, non-woven fabrics, colored plastics, crushed stone, gravel, pebbles, crushed blocks, asphalt, mortar, and waste rubber (artificial mulching materials). As an alternative to artificial mulching materials, organic mulching materials (organic mulching materials) are also used, such as straw, tea leaves, bark, branches and leaves, wood chips, waste wood chips, bamboo chips, sawdust, rice straw, wheat straw, herbaceous plant stems (such as Japanese pampas grass, reeds, and cogon grass), grass clippings, rice hulls, corn cob hulls, coffee grounds, crushed oyster shells, seashells, and rice bran. The scattering prevention agent of the present invention can also be used as a scattering prevention agent for these mulching materials laid in agricultural land such as fields. In particular, organic mulch materials are preferred as targets for the scattering prevention agent of the present invention. Organic mulch materials are environmentally friendly materials that are attracting attention from the perspective of effective utilization of agricultural residues and food waste, and from the perspective of reducing plastic use. Furthermore, when the material is no longer needed, such as after the harvest of crops, it can be plowed directly into the soil, and has the advantage of not needing to be collected and disposed of. The scattering prevention agent of the present invention uses cellulose-derived material (MFC), so it has a low environmental impact and has the advantage of being able to be plowed into the soil together with the material when it is plowed into the soil.

[0061] <How to prevent scattering> By spraying the anti-scattering agent of the present invention onto the above-mentioned objects, an effect of preventing the objects from scattering can be obtained. The spraying method is not particularly limited and includes spraying with a sprayer such as a spray bottle, electric sprayer, or engine-driven sprayer; spraying from a nozzle while circulating with a pump; and spraying a fixed amount at once with a watering can or ladle. The amount sprayed may be adjusted as appropriate depending on the object and environment, but for example, 0.3 to 3.0 L / m 2 Approximately, more preferably 0.5 to 2.0 L / m³ 2 It is approximately 1-20 g / m². Furthermore, the amount of MFC to be sprayed can be adjusted as appropriate depending on the target object and environment, but for example, 1-20 g / m² 2 Approximately, more preferably 3-15 g / m 2 It is to that extent.

[0062] By spraying the anti-scattering agent of the present invention onto an object and allowing it to dry, a coating with reduced color difference and anti-scattering effect can be obtained. For such a coating with reduced color difference, it is preferable that the blue color change rate (ΔB), red color change rate (ΔR), and green color change rate (ΔG), as described later, are within predetermined ranges.

[0063] <Blue color change rate> The blue color change rate (ΔB), expressed by the following formula, is preferably 70% or less, more preferably 60% or less, and particularly preferably 50% or less and 40% or less. There is no particular limit to the lower limit, but since it becomes difficult to determine the sprayed area if there is no color difference at all, it is preferably 1% or more, more preferably 5% or more, and particularly preferably 10% or more.

[0064] Blue color change rate (ΔB) = |(Blueness of the object before spraying - Blueness of the object after spraying and drying to form a film) / (Blueness of the object before spraying the blank solution - Blueness of the object after spraying the blank solution and drying to form a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that no coloring agent is added.)

[0065] The term "object after spraying" refers to an object that has been sprayed with a drift suppressant, dried, and had a film formed on its surface. The chromaticity of this film was then measured. Such a dried film can be obtained by allowing the drift suppressant to air dry to a certain extent after spraying, usually until the moisture content is 50% or less. The same applies to the red and green change rates described below.

[0066] <Redness Change Rate> The red color change rate (ΔR), expressed by the following formula, is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. There is no particular limit to the lower limit, but since it becomes difficult to determine the sprayed area if there is no color difference at all, it is preferably 1% or more, more preferably 2% or more, and particularly preferably 5% or more.

[0067] Redness change rate (ΔR) = |(Redness of the object before spraying - Redness of the object after spraying, drying, and forming a film) / (Redness of the object before spraying the blank solution - Redness of the object after spraying the blank solution, drying, and forming a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that no coloring agent is added.)

[0068] <Rate of change in green color> The green color change rate (ΔG), expressed by the following formula, is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. There is no particular limit to the lower limit, but since it becomes difficult to determine the application area if there is no color difference at all, it is preferably 1% or more, more preferably 2% or more, and particularly preferably 5% or more.

[0069] Green change rate (ΔR) = |(Greenness of the target object before spraying - Greenness of the target object after spraying, drying, and forming a film) / (Greenness of the target object before spraying the blank solution - Greenness of the target object after spraying the blank solution, drying, and forming a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that no coloring agent is added.)

[0070] As described above, by adjusting the blue color change rate, red color change rate, and green color change rate, a coating with reduced color difference between the target object and the anti-scatter agent can be created. While it is not possible to determine the exact amount of colorant to be added for achieving such a color change rate, a calibration curve can be created by obtaining results at several points using arbitrary amounts of colorant within the aforementioned range, thereby adjusting the anti-scatter agent to exhibit a desirable color change rate.

[0071] The anti-scattering agent of the present invention is characterized by its resistance to gelation even when stored at high concentrations, and its ability to disperse well with gentle stirring when diluted to an appropriate concentration for use. Therefore, it is possible to keep the MFC at a high concentration during transport and storage, and then dilute it to an appropriate concentration on-site before use. This reduces the costs associated with transport and storage. For example, during transport and storage, the MFC may be kept at a concentration higher than 2.5% by mass, more preferably 3.0% by mass or higher, and left in this state for a while. When used, it may be diluted to a concentration suitable for use, for example, 0.4 to 2.5% by mass, more preferably 0.5 to 1.5% by mass. The storage period is not particularly limited. For example, it may be at least 30 minutes or several days. Stirring is not necessary during storage. When diluting, stirring is preferable, but the stirring may be gentle. For example, it may be manual stirring or stirring at the level of a pump pressure (circulating stirring), or if a rotary stirrer is used, stirring may be performed at 100 to 2500 rpm for about 5 to 120 seconds. In many situations where anti-scattering agents are used, there is often no equipment capable of strong stirring or strong dispersion treatment. However, the anti-scattering agent of the present invention can be easily diluted and redispersed even in such situations, which is advantageous in terms of cost and workability. [Examples]

[0072] The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these. It is not limited to these. Unless otherwise specified, parts and % refer to parts by mass and % by mass. show.

[0073] (MFC manufacturing) 40 kg (oven-dry) of bleached, unbeaten kraft pulp derived from coniferous trees (whiteness 85%: manufactured by Nippon Paper Industries Co., Ltd.) was added to 4000 L of an aqueous solution containing 312 g of TEMPO (manufactured by Sigma Aldrich Co., Ltd.) (0.05 mmol per 1 g of oven-dry cellulose) and 4112 g of sodium bromide (1.0 mmol per 1 g of oven-dry cellulose), and the mixture was stirred until the pulp was uniformly dispersed. Sodium hypochlorite aqueous solution was added to the reaction system until the sodium hypochlorite concentration reached 5.5 mmol / g, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, but 3M sodium hydroxide aqueous solution was added sequentially to adjust the pH to 10. The reaction was terminated when the sodium hypochlorite was consumed and the pH in the system no longer changed. After adjusting the pH of the reaction mixture to 2 by adding hydrochloric acid, the pulp was thoroughly washed by repeated dehydration and dilution with water, and finally dehydration was performed until the pulp solids content was 20% by mass to obtain chemically modified pulp (oxidized cellulose fibers). The pulp yield was 90%, and the carboxyl group content was 1.41 mmol / g. The obtained oxidized cellulose fibers with a solids content of 20% by mass were dispersed in tap water, and then sodium hydroxide was added and stirred to obtain an aqueous dispersion of oxidized pulp with a pH of 7.6 and a solids content of 4.6% by mass. 80 kg of the obtained aqueous dispersion of oxidized cellulose fibers was beaten for 14 minutes using a laboratory refiner (manufactured by Aikawa Iron Works Co., Ltd.) to obtain oxidized MFCs. The number of beaten passes was 20. The average fiber width was 9.6 μm, the average fiber length was 138 μm, and the transmittance of light at a wavelength of 660 nm when used as a 1.0% by mass aqueous dispersion was 11%.

[0074] (CNF manufacturing) The oxidation reaction was carried out in the same manner as in the production of MFCs, and the reaction was terminated when the pH in the system stopped changing. The reaction mixture was filtered through a glass filter to separate the pulp, and the pulp was thoroughly washed with water to obtain chemically modified pulp (oxidized cellulose fibers). This was adjusted to a solid content concentration of 1.0 mass% with water and treated three times in an ultra-high pressure homogenizer (20°C, 150 MPa) to obtain an oxidized CNF dispersion. The number-average fiber width of the oxidized CNF measured by transmission electron microscopy was 3 nm and the aspect ratio was 250.

[0075] (Example 1: Preparation of spray solution 1) Using the MFCs manufactured as described above, tests were conducted to produce spray solutions for preventing scattering.

[0076] First, an aqueous dispersion of MFC at 3.0% by mass was prepared. The day after these dispersions were prepared, five times the amount of tap water was added to each dispersion to a concentration of approximately 0.5% by mass, and the mixture was stirred by gently shaking the container by hand. Next, Direct Paper Black NWS Liquid (manufactured by Nippon Chemical Industries, Ltd.) was added as a black dye at a rate of 0.1 g per 1 kg of MFC solids, and the mixture was stirred at 1000 rpm for 30 seconds using a homodisperser. This was then put into a spray bottle to prepare spray solution 1.

[0077] The material used was white sand (Sarasa Asobi Sand White, manufactured by Tokai Gravel Sales Co., Ltd.), which was air-dried and passed through a 1.18mm sieve. This sand was then spread to a height of 3-4cm from the bottom of a container (166mm x 106mm x 86mm, manufactured by Trusco Nakayama Co., Ltd.), and then compacted evenly with a 180g tamping stick. This process was repeated a total of three times to prepare a container filled with approximately 1940g of white sand.

[0078] The RGB values ​​of the obtained objects were measured on their surfaces according to the color difference observation evaluation method described later, before the spraying.

[0079] When the aforementioned spray solution 1 was dispensed onto the target object from a spray bottle at a rate of 2 L / m2 (35.2 g / container of spray solution), the entire amount of MFC dispersion was dispensed without clogging. From these results, it was found that the MFC dispersion can be dispensed well even with weak agitation such as 1000 rpm for 30 seconds, and that a spray solution for preventing scattering can be manufactured with simpler operation compared to the CNF dispersion described later.

[0080] Furthermore, after spraying, the objects were left to dry at room temperature for two days. Then, the RGB values ​​of the objects before spraying were measured on the surface of the objects on which the MFC coating had formed, in accordance with the color difference observation evaluation method described later.

[0081] (Comparative Example 1: Production of spray solution 2) Spray solution 2 was prepared in the same manner as in Example 1, except that Direct Paper Black NWS Liquid was not added to the aqueous dispersion of MFC, and was sprayed onto the target object.

[0082] (Example 2: Production of spray solution 3) Spray solution 3 was prepared in the same manner as in Example 1, except that Direct Paper Black NWS Liquid was added to the aqueous dispersion of MFC at a ratio of 1 g per 1 kg of MFC solid portion, and then sprayed onto the target object.

[0083] <Evaluation Method> (External observation) The appearance of the surface of the object after spraying the solution was visually observed and evaluated according to the following criteria. ○: There is little color difference between the treated and untreated areas, resulting in a good appearance. △: There is a slight difference in color between the treated and untreated areas, but it has been improved. ×: There is a significant color difference between the treated and untreated areas, resulting in an inferior appearance.

[0084] (Color difference observation) A pre-defined observation area (43mm x 26mm section) on the surface of the object was photographed using a microscope (VHX-8000, manufactured by Keyence Corporation) under the following conditions: objective lens: E20 x 20, reflected light illumination: ring illumination.

[0085] The obtained images were subjected to color extraction using the image analysis and measurement software WinROOF2021, and the R value (redness), G value (greenness), and B value (blueness) were obtained.

[0086] (Blue color change rate) From the B values ​​of each object obtained by the method described above, the blue color change rate for each example was calculated using the following formula.

[0087] Blue color change rate (ΔB) = |(Blueness of the object before spraying - Blueness of the object after spraying and drying to form a film) / (Blueness of the object before spraying the blank solution - Blueness of the object after spraying the blank solution and drying to form a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that a coloring agent was not added. In Examples 1 to 3, this corresponds to spray solution 2 of Comparative Example 1.)

[0088] (Red change rate) From the R values ​​of each object obtained by the method described above, the red color change rate for each example was calculated using the following formula.

[0089] Redness change rate (ΔR) = |(Redness of the object before spraying - Redness of the object after spraying, drying, and forming a film) / (Redness of the object before spraying the blank solution - Redness of the object after spraying the blank solution, drying, and forming a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that a coloring agent was not added. In Examples 1 to 3, this corresponds to spray solution 2 of Comparative Example 1.)

[0090] (Rate of change to green) From the G-values ​​of each object obtained by the method described above, the green color change rate for each example was calculated using the following formula.

[0091] Green change rate (ΔG) = |(Greenness of the target object before spraying - Greenness of the target object after spraying, drying, and forming a film) / (Greenness of the target object before spraying the blank solution - Greenness of the target object after spraying the blank solution, drying, and forming a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that a coloring agent was not added. In Examples 1 to 3, this corresponds to spray solution 2 of Comparative Example 1.)

[0092] TIFF2026053147000001.tif19150

[0093] (Example 3) Except for using ash sand (play sand for sandboxes, manufactured by Seiryo Stage Co., Ltd.) as the target material, spray solution 1 was sprayed onto the target material in the same manner as in Example 1.

[0094] (Comparative Example 2) Except for using ash sand (play sand for sandboxes, manufactured by Seiryo Stage Co., Ltd.) as the target material, spray solution 2 was applied to the target material in the same manner as in Comparative Example 1.

[0095] (Example 4) Except for using ash sand (play sand for sandboxes, manufactured by Seiryo Stage Co., Ltd.) as the target material, spray solution 3 was applied to the target material in the same manner as in Example 2.

[0096] (Example 5: Preparation of spray solution 4) Spray solution 4 was prepared in the same manner as in Example 1, except that ash sand (play sand for sandboxes, manufactured by Seiryo Stage Co., Ltd.) was used as the target material, and Direct Paper Black NWS Liquid was added to the aqueous dispersion of MFC at a ratio of 10 g per 1 kg of MFC solid portion. This spray solution 4 was then sprayed onto the target material in the same manner as in Example 1.

[0097] TIFF2026053147000002.tif22150

[0098] (Comparative Example 3: Production of the spray solution 5) Spray solution 5 was prepared in the same manner as in Example 1, except that CNF was used instead of MFC. When attempting to dispense it from a spray bottle, clogging occurred, preventing the entire amount from being dispensed, resulting in uneven spraying on the target object.

[0099] As shown in Tables 1 and 2, by using MFC as the anti-scattering agent of the present invention and adding a coloring agent in an appropriate amount depending on the chromaticity of the target object, it is possible to form a highly effective, uniform anti-scattering film with good discharge properties, while also blurring the sprayed area to make it less noticeable and maintaining a good appearance. In particular, it was found that the appearance can be maintained by keeping the rate of change of each color within a certain range compared to the blank solution. On the other hand, dust suppressants using CNF with a small average fiber diameter were unsuitable for use as dust suppressants because they caused clogging during application.< / mfc>

Claims

1. A dust suppressant including the following (A) to (C). (A) Microfibril cellulose having an average fiber width greater than 1.0 μm and a transmittance of 60% or less of light at a wavelength of 660 nm as a 1.0 mass% aqueous dispersion. (B) Solvent (C) A coloring agent for reducing the color difference between the object to which the anti-scattering agent is sprayed and the sprayed anti-scattering agent.

2. The anti-scattering agent according to claim 1, wherein the microfibril cellulose is chemically modified microfibril cellulose.

3. The anti-scattering agent according to any one of claims 1 to 2, characterized in that the coloring agent comprises at least one selected from black dye, lignin, and ferrous sulfate.

4. A method for preventing scattering, comprising spraying a scattering prevention agent onto an object to be prevented from scattering, the agent comprising microfibril cellulose having an average fiber width greater than 1.0 μm and a transmittance of 60% or less of light at a wavelength of 660 nm as a 1.0 mass% aqueous dispersion, a solvent, and a coloring agent, A method for preventing scattering, characterized in that the blue color change rate (ΔB), expressed by the following formula, is 70% or less. Blue color change rate (ΔB) = |(Blueness of the target object before spraying - Blueness of the target object after spraying, drying, and forming a film) / (Blueness of the target object before spraying the blank solution - Blueness of the target object after spraying the blank solution, drying, and forming a film)| × 100 (A blank solution is a composition prepared in the same manner as a splash inhibitor, except that no coloring agent is added.)

Images