Heat-insulating and sound-insulating coating material

Abstract

To provide a novel coating material having both heat-insulating performance and sound-insulating performance.SOLUTION: A heat-insulating and sound-insulating coating material comprises thermally expanded volcanic glass powder, cellulose fine fibers, and a resin. The cellulose nanofibers are preferably chemically modified cellulose fine fibers.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a heat-insulating and sound-insulating paint containing a heat-expanded body of volcanic glass powder, cellulose microfibers, and a resin.

Background Art

[0002] In recent years, in the field of electric vehicles, since the power has changed from an engine to a motor, new problems regarding impacts such as noise, vibration, and harshness (NVH) have arisen. Specifically, noises such as running sounds and wind noise that were previously masked by the engine operating sound have surfaced, and new noises such as those from electric motors have become problems. Also, in electric vehicles, since engine heat cannot be used for cabin heating, a heat-insulating material for interior decoration is also required.

[0003] As a paint capable of improving both sound insulation and heat insulation, Patent Document 1 proposes a paint containing hollow particles with a vacuum in the hollow part and a structure-retaining agent that retains the array structure of the hollow particles after the coating film is formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, by using special hollow particles with a vacuum in the hollow part, heat conduction and air propagation of sound are prevented to obtain heat insulation and sound insulation effects. However, it is preferable that both heat insulation and sound insulation effects can be obtained without using special particles. Further, it is desirable to obtain a paint using a material with as little environmental impact as possible. Providing a new paint composition having both heat insulation and sound insulation properties also leads to expanding the options for measures for heat insulation and sound insulation. An object of the present invention is to provide a new paint having both heat insulation and sound insulation effects.

Means for Solving the Problems

[0006] As a result of intensive studies by the present inventors, it has been found that a paint obtained by combining a heat-expanded body of volcanic glassy powder with cellulose microfibers has both heat insulation and sound insulation properties, and the present invention has been completed. The present invention includes the following. (1) A paint for heat insulation and sound insulation, comprising a heat-expanded body of volcanic glassy powder, cellulose microfibers, and a resin. (2) The paint for heat insulation and sound insulation according to (1), wherein the average fiber diameter of the cellulose microfibers is 2 to 500 nm. (3) The paint for heat insulation and sound insulation according to (1) or (2), wherein the cellulose microfibers are chemically modified cellulose microfibers. (4) The paint for heat insulation and sound insulation according to (3), wherein the chemically modified cellulose microfibers are oxidized cellulose microfibers.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a paint that can impart both heat insulation and sound insulation properties to an object to be coated. The paint containing a combination of the heat-expanded body of volcanic glassy powder and cellulose microfibers of the present invention tends to have higher heat insulation and sound insulation properties than a paint containing a heat-expanded body of volcanic glassy powder and not containing cellulose microfibers. The reason for this is not clear, but the present inventors speculate as follows: The heat-expanded body of the volcanic glassy powder has a hollow shape, and the air layer in the hollow part can block heat and sound waves. When cellulose microfibers are combined with this expanded body, it is considered that hydrogen bonds are formed between the silanol groups (Si-OH) on the surface of the expanded body and the adsorbed water, and the cellulose microfibers. As a result, the expanded body is uniformly dispersed in the paint. When a paint film is formed, the expanded body is uniformly dispersed, enhancing the heat insulation and sound insulation effects. Moreover, it is considered that the strength of the paint film is increased, further enhancing these effects.

Embodiments for Carrying Out the Invention

[0008] The present invention relates to a heat insulation and sound insulation paint containing a heat-expanded body of volcanic glassy powder, cellulose microfibers, and a resin. (Heat-expanded body of volcanic glassy powder) The heat-expanded body of the volcanic glassy powder used in the present invention is a hollow particulate expanded body obtained by heating and expanding glassy volcanic ash powder at a high temperature. The heat-expanded body of the volcanic glassy powder can be easily obtained from the market. For example, a particulate hollow body called shirasu balloon, which is obtained by firing and expanding volcanic glassy powder mined from the shirasu plateau or the like at a temperature of about 1000 °C, is commercially available. The mining location of the volcanic glassy powder is not particularly limited, and a particulate hollow body obtained by similarly heating and expanding volcanic glassy powder mined outside the shirasu plateau may also be used. The heat-expanded body of the volcanic glassy powder is mainly composed of natural glassy material and is a material with a small environmental load.

[0009] The average particle size of the heat-expanded body of the volcanic glassy powder is preferably about 20 to 100 μm, more preferably 25 to 80 μm, and even more preferably 30 to 70 μm. The average particle size of the heat-expanded body of the volcanic glassy powder can be measured by a wet or dry measurement method using a laser diffraction / scattering particle size distribution measuring device.

[0010] The bulk density of the heat-expanded body of the volcanic glassy powder is not particularly limited, but is preferably about 0.05 to 1.00 g / mL, 0.10 to 0.50 g / cm 3is more preferable, and 0.15 to 0.40 g / mL is even more preferable. The bulk density of the heat-expanded product of the volcanic glassy powder can be measured by the following method: Gently place the weighed powder sample (m) of about 100 g into a dry 250 mL graduated cylinder (minimum scale unit: 2 mL) without compaction. If necessary, carefully level the upper surface of the powder layer without compaction and read the loose bulk volume (V0) to the minimum scale unit. Calculate the bulk density (g / mL) by m / V0.

[0011] The floating rate of the heat-expanded product of the volcanic glassy powder is not particularly limited, but about 10 to 90% by mass is preferable, 20 to 85% by mass is even more preferable, and 30 to 85% by mass is even more preferable. The floating rate of the heat-expanded product of the volcanic glassy powder can be measured by the following method: Transfer the weighed 20 g sample to a 200 mL beaker, gently pour about 100 mL of water, and stir. After standing for 2 hours, transfer the whole amount to a floating and sedimentation separator, add water to make the whole amount 300 to 500 mL. After the water between the floating matter and the sediment becomes clear, separate the floating matter and the sediment, dry each, and weigh. The floating rate is calculated as the ratio (mass%) of the floating matter to the total mass of the powder.

[0012] (Cellulose microfibrils) The cellulose microfibers used in the present invention are microfibers made from cellulose as a raw material, and can be obtained by defibrating the cellulose raw material to reduce its fiber diameter. The average fiber diameter of the cellulose microfibers is not particularly limited, but is about 2 nm to 10 μm. The average fiber diameter is preferably 2 nm to 1 μm, more preferably 2 nm to 500 nm, still more preferably 2 nm to 100 nm, and even more preferably 2 nm to 50 nm. Among these ranges, in particular, when the average fiber diameter of the cellulose microfibers is 100 nm or less, the effect of improving heat insulation and sound insulation is enhanced, which is preferable. The average fiber diameter and average fiber length of the cellulose microfibers can be obtained by appropriately selecting and using a fiber tester manufactured by ABB Ltd., a fractionator manufactured by Valmet, a scanning electron microscope (SEM), an atomic force microscope (AFM), or a transmission electron microscope (TEM) according to the size of the fiber diameter, and averaging the fiber diameter and fiber length obtained from the results of observing each fiber. When measuring the fiber diameter on the nanoscale, it is preferable to obtain it by measuring the cross-sectional height of the shape image of the fiber observed using an atomic force microscope (AFM). The average fiber diameter can be obtained by measuring the fiber diameter of 50 randomly selected fibers by the above method and calculating the length-weighted average fiber diameter. Also, when measuring the fiber length of nanoscale fibers, it is preferable to use a transmission electron microscope (TEM) or an atomic force microscope (AFM). The average fiber length can be obtained by measuring the fiber length of 200 randomly selected fibers by the above method and calculating the length-weighted average fiber length.

[0013] The aspect ratio of the cellulose microfibers is preferably 10 to 1000, more preferably 10 to 500, and still more preferably 10 to 200. The aspect ratio can be calculated by the following formula: Aspect ratio = average fiber length (nm) / average fiber diameter (nm).

[0014] The cellulose raw material serving as the raw material for cellulose microfibers only needs to contain cellulose and is not particularly limited. Examples thereof include those derived from plants, animals (e.g., tunicates), algae, and microorganisms (e.g., acetic acid bacteria (Acetobacter)) products. Examples of those derived from plants include wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), softwood dissolving pulp, hardwood dissolving pulp, recycled pulp, waste paper, etc.). Also, cellulose powder obtained by pulverizing the above-mentioned cellulose raw material may be used. As the cellulose raw material, any one or a combination of these may be used, but preferably cellulose fibers derived from plants or microorganisms, more preferably cellulose fibers derived from plants, and even more preferably woody pulp.

[0015] (Chemically modified cellulose microfibers) Cellulose has three hydroxyl groups per glucose unit and can undergo various chemical modifications. As an example of cellulose microfibers, using chemically modified cellulose microfibers obtained by defibrating a chemically modified cellulose raw material (chemically modified cellulose fibers) is preferable not only from the viewpoint of promoting the progress of defibrillation but also from the viewpoint of improving heat insulation and sound insulation.

[0016] As chemical modifications, anion modifications that introduce anionic groups into cellulose are preferred. Specifically, anion modification means introducing an anionic group into the pyranose ring of cellulose by a substitution or oxidation reaction. Examples of anion modifications include, but are not limited to, oxidation (also called carboxylation) that introduces a carboxy group into a cellulose chain, carboxyalkylation that ether-bonds a carboxyalkyl group such as a carboxymethyl group (hereinafter, "carboxymethyl" is referred to as "CM") to a cellulose chain, phosphoric esterification that introduces a phosphate group into a cellulose chain, and the like. Among them, oxidation (carboxylation) is preferred.

[0017] Examples of the chemically modified cellulose microfibrils include TEMPO-oxidized cellulose microfibrils, ozone-oxidized cellulose microfibrils, CM-cellulose microfibrils, carboxyalkylated cellulose microfibrils, phosphoric esterified cellulose microfibrils, phosphorous esterified cellulose microfibrils, cationized cellulose microfibrils, sulfonated cellulose microfibrils, xanthated cellulose microfibrils, and the like. Among them, oxidized cellulose microfibrils are more preferred.

[0018] Chemically modified cellulose microfibrils such as anion-modified cellulose microfibrils may take a form in which anionic groups such as carboxy groups, CM groups, and phosphate groups have metal ions such as sodium ions and potassium ions as counterions (this form is called the "salt form"). In addition, they may also take a form in which an anionic group has a proton as a counterion (this form is called the "hydrogen form").

[0019] The chemically modified cellulose fiber, which is the raw material for the chemically modified cellulose microfiber, is such that at least a part of the fibrous shape of cellulose is maintained even when dispersed in water. That is, when the aqueous dispersion of the chemically modified cellulose fiber is observed with an electron microscope or the like, fibrous substances can be observed, and when measured by X-ray diffraction, peaks of cellulose I-type crystals can be observed. The crystallinity of cellulose in the chemically modified cellulose fiber or the chemically modified cellulose microfiber is preferably 50% or more, more preferably 55% or more, in terms of crystalline form I. The crystallinity of cellulose can be controlled by the degree of chemical modification. The upper limit of the crystallinity of cellulose I-type is not particularly limited. Realistically, it is considered that about 90% is the upper limit. The method for measuring the crystallinity of cellulose I-type is as follows: Place the sample in a glass cell and measure it using an X-ray diffraction measuring device (product name: LabX XRD-6000, manufactured by Shimadzu Corporation). The crystallinity is calculated using the method of Segal et al. Using the diffraction intensity in the range of 2θ = 10° to 30° of the X-ray diffraction pattern as the baseline, it is calculated from the diffraction intensity of the 002 plane at 2θ = 22.6° and the diffraction intensity of the amorphous part at 2θ = 18.5° by the following formula: X c =(I 002c ―I a ) / I 002c ×100 X c =Degree of crystallinity of cellulose I-type (%) I 002c : Diffraction intensity of the 002 plane at 2θ = 22.6° I a : Diffraction intensity of the amorphous part at 2θ = 18.5°.

[0020] In order to obtain a chemically modified cellulose fiber having a peak of cellulose I-type crystal, it is preferable to use a cellulose raw material having a high crystallinity of cellulose I-type. The crystallinity of cellulose I-type in the cellulose raw material is preferably 50% or more, more preferably 60% or more.

[0021] (Oxidation) One example of chemically modified cellulose microfibrils is oxidized cellulose microfibrils (also referred to as "carboxylated cellulose microfibrils"), which can be obtained by defibrating oxidized cellulose fibers obtained by oxidizing (carboxylating) the above-mentioned cellulose raw materials by a known method. 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 based on the absolute dry mass of the oxidized cellulose. The amount of carboxyl groups in the oxidized cellulose fibers can be measured by the following method: Prepare 100 mL of a 0.3% by mass slurry (aqueous dispersion) of oxidized cellulose fibers, add a 10% aqueous hydrochloric acid solution to adjust the pH to 2.39, then dropwise add a 0.05 N aqueous sodium hydroxide solution and measure the electrical conductivity until the pH reaches 11. Calculate from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid where the change in electrical conductivity is gentle using the following formula: Amount of carboxyl groups [mmol / g oxidized cellulose fibers] = a [mL] × 0.05 / mass of oxidized cellulose fibers [g].

[0022] The amount of carboxyl groups in the oxidized cellulose fibers and the amount of carboxyl groups in the oxidized cellulose microfibrils obtained by defibrating the oxidized cellulose fibers are usually the same. As an example of the oxidation method, a method of oxidizing 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 bromides, iodides, and mixtures thereof can be mentioned. By this oxidation reaction, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized to obtain a cellulose raw material (oxidized cellulose fibers) having an aldehyde group and a carboxyl group (-COOH) or a carboxylate group (-COO-) on the surface. The concentration of the cellulose raw material during the reaction is not particularly limited, but is preferably 5% by mass or less.

[0023] An N-oxyl compound refers to a compound capable of generating a nitroxyl radical. As the N-oxyl compound, any compound can be used as long as it promotes the target oxidation reaction. For example, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and its derivatives (e.g., 4-hydroxy TEMPO) can be mentioned. The amount of the N-oxyl compound used only needs to be a catalytic amount capable of oxidizing the cellulose raw material and is not particularly limited. For example, for 1 g of absolutely dry cellulose raw material, 0.01 to 10 mmol is preferable, 0.01 to 1 mmol is more preferable, and 0.05 to 0.5 mmol is even more preferable. Also, about 0.1 to 4 mmol / L is good for the reaction system.

[0024] A bromide is a compound containing bromine, and examples thereof include alkali metal bromides that can dissociate and ionize in water. Also, an iodide is a compound containing iodine, and examples thereof include alkali metal iodides. The amount of the bromide or iodide used can be selected within a range capable of promoting the oxidation reaction. The total amount of the bromide and iodide is, for example, preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol with respect to 1 g of absolutely dry cellulose raw material.

[0025] As the oxidizing agent, known ones can be used. For example, halogen, hypohalous acid, halous acid, perhalic acid or their salts, halogen oxides, peroxides, etc. can be used. Among them, sodium hypochlorite, which is inexpensive and has a low environmental impact, is preferable. The appropriate amount of the oxidizing agent used is, for example, preferably 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 with respect to 1 g of absolutely dry cellulose raw material. Also, for example, 1 to 40 mol is preferable with respect to 1 mol of the N-oxyl compound.

[0026] Even under relatively mild conditions, the oxidation process of the cellulose raw material can proceed efficiently. Therefore, the reaction temperature is preferably 4 to 40 °C, and it may also be at room temperature of about 15 to 30 °C. As carboxyl groups are generated in the cellulose chain as the reaction proceeds, a decrease in the pH of the reaction solution is observed. In order to efficiently proceed the oxidation reaction, 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 about 10 to 11. The reaction medium is preferably water in view of ease of handling and difficulty in occurring side reactions. The reaction time in the oxidation reaction can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours.

[0027] Also, the oxidation reaction may be carried out in two steps. For example, the oxidized cellulose obtained by filtration after completion of the first-stage reaction is oxidized again under the same or different reaction conditions, so that it can be efficiently oxidized without being inhibited by the reaction with sodium chloride by-produced in the first-stage reaction.

[0028] As another example of the oxidation method, a method of oxidizing by bringing a gas containing ozone into contact with the cellulose raw material can be mentioned. By this oxidation reaction, at least the hydroxyl groups at the 2-position and 6-position of the glucopyranose ring are oxidized and the decomposition of the cellulose chain occurs. The ozone concentration in the gas containing ozone is preferably 50 to 250 g / m 3 and preferably 50 to 220 g / m 3It is more preferable. When the solid content of the cellulose raw material is 100 parts by mass, the ozone addition amount to the cellulose raw material is preferably 0.1 to 30 parts by mass, and more preferably 5 to 30 parts by mass. 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 about 1 to 360 minutes, and preferably about 30 to 360 minutes. When the ozone treatment conditions are within these ranges, it is possible to prevent the cellulose raw material from being excessively oxidized and decomposed, and the yield of the oxidized cellulose fiber becomes good. After the ozone treatment, a post-oxidation treatment may be performed using an oxidizing agent. The oxidizing agent used for the post-oxidation treatment is not particularly limited, and examples thereof include chlorine-based compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, peracetic acid, and the like. For example, these oxidizing agents can be dissolved in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and the post-oxidation treatment can be performed by immersing the cellulose raw material in the solution.

[0029] The amount of carboxyl groups in the oxidized cellulose fiber can be adjusted by controlling the reaction conditions such as the addition amount of the above-mentioned oxidizing agent and the reaction time. (Carboxyalkylation, CM modification) Carboxyalkylated cellulose microfibrils, an example of chemically modified cellulose microfibrils, preferably CM cellulose microfibrils, can be obtained by defibrating carboxyalkylated cellulose fibers, preferably CM cellulose fibers, obtained by known methods. The degree of carboxyalkyl substitution per anhydrous glucose unit of cellulose is preferably from 0.01 to 0.50. The upper limit is preferably 0.40 or less. When the degree of carboxyalkyl substitution exceeds 0.50, dissolution in water tends to occur and the fiber form cannot be maintained in water. In order to obtain the effects of carboxyalkylation, it is necessary to have a certain degree of substitution. For example, when the degree of substitution is less than 0.02, depending on the application, the advantages of introducing a carboxyalkyl group may not be obtained. Therefore, the degree of carboxyalkyl substitution is preferably 0.02 or more, more preferably 0.05 or more, and still more preferably 0.10 or more. The degree of carboxyalkyl substitution can be adjusted by controlling the amount of carboxyalkylating agent to be reacted, the amount of mercerizing agent, the composition ratio of water and organic solvent, and the like.

[0030] In this specification, the anhydrous glucose unit means an individual anhydrous glucose (glucose residue) constituting cellulose. The degree of carboxyalkyl substitution (also referred to as the degree of etherification) indicates the ratio of the hydroxyl groups in the glucose residue constituting cellulose that are substituted with carboxyalkyl ether (the number of carboxyalkyl ethers per glucose residue). The degree of carboxyalkyl substitution may be abbreviated as DS.

[0031] The method for measuring the degree of carboxyalkyl substitution is as follows: Precisely weigh about 2.0 g of the sample and place it in a 300 mL Erlenmeyer flask with a stopper. Add 100 mL of nitric acid - methanol (a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol), shake for 3 hours to convert the salt - type carboxyalkylated cellulose fiber into the hydrogen - type carboxyalkylated cellulose fiber. Precisely weigh 1.5 - 2.0 g of the hydrogen - type carboxyalkylated cellulose fiber (absolutely dry) and place it in a 300 mL Erlenmeyer flask with a stopper. Moisten it with 15 mL of 80% methanol, add 100 mL of 0.1N - NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, back - titrate the excess NaOH with 0.1N - H2SO4, and calculate the degree of carboxyalkyl substitution (DS) according to the following formula. A = [(100×F’ - 0.1N - H2SO4 (mL)×F)×0.1] / (absolute dry mass of hydrogen - type carboxyalkylated cellulose fiber (g)) Degree of carboxyalkyl substitution (DS)=0.162×A / (1 - 0.058×A) F’: Factor of 0.1N - H2SO4 F: Factor of 0.1N - NaOH.

[0032] The DS in the carboxyalkylated cellulose fiber and the DS in the carboxyalkylated cellulose micro - fiber obtained by defibrating the carboxyalkylated cellulose are usually the same.

[0033] As an example of the method for producing carboxyalkylated cellulose fiber, an example of the production of CM - cellulose fiber will be described below. First, mix the cellulose raw material with a solvent and a mercerizing agent, and carry out the mercerization of the cellulose raw material at a reaction temperature of 0 - 70°C, preferably 10 - 60°C, and a reaction time of 15 minutes - 8 hours, preferably 30 minutes - 7 hours. Then, add 0.05 - 10.0 times the molar amount of the CM - agent per glucose residue, and carry out the CM - reaction at a reaction temperature of 30 - 90°C, preferably 40 - 80°C, and a reaction time of 30 minutes - 10 hours, preferably 1 hour - 4 hours.

[0034] As the solvent, 3 to 20 times by mass of water or an organic solvent or a mixture thereof can be used. Examples of the organic solvent include, but are not limited to, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, and tert-butanol, ketones such as acetone, diethyl ketone, and methyl ethyl ketone, and dioxane, diethyl ether, benzene, dichloromethane, etc. Among these, monohydric alcohols having 1 to 4 carbon atoms are preferred because of their excellent compatibility with water, and monohydric alcohols having 1 to 3 carbon atoms are more preferred. As the mercerizing agent, it is preferable to use 0.5 to 20 times the molar amount of an alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide, per anhydrous glucose residue of the cellulose raw material. Examples of the CM agent include monochloroacetic acid, sodium monochloroacetate, methyl monochloroacetate, ethyl monochloroacetate, and isopropyl monochloroacetate. Among these, monochloroacetic acid or sodium monochloroacetate is preferred in terms of the availability of the raw materials. The amount of the CM agent used is not particularly limited, but it is preferably added in the range of 0.5 to 1.5 mol per anhydrous glucose unit of cellulose. The lower limit of the above range is more preferably 0.6 mol or more, still more preferably 0.7 mol or more, and the upper limit is more preferably 1.3 mol or less, still more preferably 1.1 mol or less. The CM agent may be added to the reactor, for example, as an aqueous solution of 5 to 80% by mass, more preferably 30 to 60% by mass, or may be added in a powder state without dissolving in a solvent such as water.

[0035] When using monochloroacetic acid or sodium monochloroacetate as the carboxymethylating agent, the molar ratio of the mercerizing agent to the carboxymethylating agent (mercerizing agent / carboxymethylating agent) is generally 0.90 to 2.45. The reasons are as follows: If it is less than 0.90, the carboxymethylation reaction may be insufficient, and unreacted monochloroacetic acid or sodium monochloroacetate may remain, resulting in waste. And if it exceeds 2.45, side reactions may occur between the excess mercerizing agent and monochloroacetic acid or sodium monochloroacetate, leading to the formation of an alkali metal salt of glycolic acid, which may be uneconomical.

[0036] When performing the carboxymethylation of the cellulose raw material, generally, there are a method of performing both mercerization and carboxymethylation under a water-based solvent (aqueous medium method) and a method of performing both mercerization and carboxymethylation under a mixed solvent of water and an organic solvent (solvent method), and either method can be used. Also, a water-based solvent may be used for mercerization, and a mixed solvent of an organic solvent and water may be used for carboxymethylation. By doing so, even when maintaining the crystallinity of cellulose at 50% or more, carboxymethylated cellulose with CM groups introduced uniformly rather than locally can be obtained economically.

[0037] Using water as the main solvent (a water-based solvent) means a solvent containing water at a ratio higher than 50% by mass. The water in the water-based solvent is preferably 55% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Particularly preferably, the water-based solvent is 100% by mass of water (i.e., water). The greater the proportion of water during mercerization, the advantage of more uniform introduction of CM groups by cellulose can be obtained. As the solvent other than water (used in mixture with water) in the water-based solvent, the above-described organic solvents can be used. The amount of the organic solvent in the water-based solvent is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, still more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, and more preferably 0% by mass.

[0038] Simultaneously with the addition of the CM agent, or before or immediately after the addition of the CM agent, an organic solvent or an aqueous solution of an organic solvent is appropriately added to the reactor, or an organic solvent other than water during the mercerization treatment is appropriately reduced by reduced pressure or the like to form a mixed solvent of water and an organic solvent, and it is preferable to proceed with the CM reaction under this mixed solvent of water and an organic solvent. The timing of the addition or reduction of the organic solvent may be between after the end of the mercerization reaction and immediately after the addition of the CM agent, and is not particularly limited. For example, within 30 minutes before and after the addition of the CM agent is preferable.

[0039] When CM is formed, the proportion of the organic solvent in the mixed solvent is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, still more preferably 45% by mass or more, and particularly preferably 50% by mass or more, based on the total of water and the organic solvent. The higher the proportion of the organic solvent, the easier it is for uniform substitution of the CM group to occur, and thus the quality of the resulting CM cellulose is stabilized. The upper limit of the proportion of the organic solvent is not limited and may be, for example, 99% by mass or less. Considering the cost of the organic solvent to be added, it is preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, and still more preferably 70% by mass or less.

[0040] The reaction medium (a mixed solvent of water and an organic solvent, etc., not containing cellulose) during CM formation preferably has a lower proportion of water (in other words, a higher proportion of the organic solvent) than the reaction medium during mercerization. By satisfying this range, it becomes easier to maintain the crystallinity of the resulting CM cellulose. Also, when the reaction medium during CM formation has a lower proportion of water (a higher proportion of the organic solvent) than the reaction medium during mercerization, an advantage is obtained in that a mixed solvent for the CM formation reaction can be formed by a simple means of adding a desired amount of the organic solvent to the reaction system after the completion of the mercerization reaction when shifting from the mercerization reaction to the CM formation reaction.

[0041] (Phosphoric acid esterification) Phosphoric acid esterified cellulose microfibrils, which are an example of chemically modified cellulose microfibrils, can be obtained by defibrating phosphoric acid esterified cellulose fibers. As the phosphoric acid esterified cellulose fibers, commercially available ones may be used, or they may be produced by phosphoric acid esterifying the above cellulose raw materials by a known method. The degree of substitution of phosphoric acid groups per glucose unit of the phosphoric acid esterified cellulose fibers is preferably 0.001 or more and less than 0.40. The degree of substitution of phosphoric acid groups in the phosphoric acid esterified cellulose fibers and the degree of substitution of phosphoric acid groups in the phosphoric acid esterified cellulose microfibrils obtained by defibrating the phosphoric acid esterified cellulose fibers are usually the same.

[0042] Examples of the method for phosphorylating include a method of mixing a powder or aqueous solution of a compound having a phosphate group with a cellulose raw material, a method of adding an aqueous solution of a compound having a phosphate group to a slurry of a cellulose raw material, and the like. Examples of the compound 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, ammonium metaphosphate, and the like. One or more of these can be used in combination to introduce a phosphate group into the cellulose raw material. Among these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferable from the viewpoints of high efficiency of introducing a phosphate group and easy industrial application. In particular, sodium dihydrogen phosphate and disodium hydrogen phosphate are preferable. Further, since the reaction can proceed uniformly and the efficiency of introducing a phosphate group is high, it is desirable to use the compound having a phosphate group as an aqueous solution. The pH of the aqueous solution of the compound having a phosphate group is preferably 7 or less because the efficiency of introducing a phosphate group is high, but pH 3 to 7 is preferable from the viewpoint of suppressing hydrolysis of the fiber. When reacting the compound having a phosphate group, a basic compound (for example, a compound having an amino group exhibiting basicity such as urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, etc.) may be added to the reaction system.

[0043] As a specific example of the method for producing phosphorylated cellulose fibers, the following method can be mentioned. A compound having a phosphate group is added to a suspension of a cellulose raw material having 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 addition amount of the compound having a phosphate group is preferably 0.2 to 500 parts by mass, more preferably 1 to 400 parts by mass, in terms of the amount of phosphorus element.

[0044] After dehydrating the obtained suspension of phosphorylated cellulose fibers, from the viewpoint of suppressing hydrolysis of cellulose, it is preferable to perform heat treatment at 100 to 170°C. Further, while water is contained during the heat treatment, it is preferably heated at 130°C or lower, preferably 110°C or lower, and after the water is removed, it is preferably heat-treated at 100 to 170°C.

[0045] (Defibrination) By defibrinating the above-mentioned cellulose raw material or chemically modified cellulose raw material (chemically modified cellulose fiber), cellulose microfibers or chemically modified cellulose microfibers can be obtained. The apparatus used for defibrination is not particularly limited. For example, apparatuses capable of applying a strong shearing force such as a high-pressure type, a high-speed rotation type, a colloid mill type, a roll mill type, an ultrasonic type, a cavitation type, etc., or refiners such as a disk type, a conical type, or a cylinder type, a high-pressure homogenizer, a colloid mill, a high-pressure jet disperser, a beater, a PFI mill, a kneader, a disperser, etc. can be used.

[0046] Defibrination is preferably carried out wet (that is, in the form of a dispersion using water or the like as a dispersion medium). When performing defibrination wet, first, a dispersion of a cellulose raw material or a chemically modified cellulose fiber is prepared. The solid content concentration in the dispersion to be subjected to defibrination is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. As the upper limit of the concentration, 40% by mass or less is preferable, 30% by mass or less is more preferable, 10% by mass or less is more preferable, and 8% by mass or less is more preferable. The dispersion medium is preferably water.

[0047] (Resin) The paint of the present invention contains a resin. Examples of the type of resin include, but are not limited to, ethylene vinyl acetate resin, vinyl acetate resin, vinyl chloride resin, acrylic resin, urethane resin, epoxy resin, vinylidene chloride resin, styrene-butadiene resin, etc.

[0048] (Other Components) In addition to the above materials, the paint of the present invention may contain other components that can be used in the paint. Examples of other components include, but are not limited to, various solvents, film-forming aids, pigments, fillers, dyes, defoamers, leveling agents, thickeners, viscosity reducers, dispersants, fungicides, preservatives, anti-settling agents, anti-freezing agents, rust inhibitors, etc.

[0049] The paint of the present invention may or may not contain inorganic particles, pigments other than the heated foam of volcanic glassy powder, or organic particles. Even when such particles are not contained, the effects of heat insulation and sound insulation can be obtained.

[0050] (Heat Insulating and Sound Insulating Paint) The heat insulating and sound insulating paint of the present invention contains at least the heated foam of the volcanic glassy powder described above, cellulose microfibers, and a resin.

[0051] The content (solid content) of the heated foam of the volcanic glassy powder in the paint is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass. Generally, when the content of the heated foam is high, the effects of heat insulation and sound insulation tend to increase. However, if the content is too high, the coating film may become brittle and the effects may instead decrease. The content of the heated foam may be selected according to the composition of the paint. For example, when the affinity between the resin and the heated foam is high, the content of the heated foam can be relatively increased. When the affinity is low, the content of the heated foam can be set lower, for example, within the above range, considering the stability of the paint.

[0052] The content (solid content) of the cellulose microfibers in the paint is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass. When it is in such a range, generally, the viscosity of the paint is appropriate and it is easy to apply, and the effect of improving the heat insulation and sound insulation effects can also be easily obtained.

[0053] The content (solid content) of the resin in the paint is preferably 1 to 30% by mass, more preferably 2 to 20% by mass. The paint may be an aqueous paint or a non-aqueous paint. An aqueous paint is preferred because of its good affinity with cellulose microfibers.

[0054] (Manufacture of paint) When manufacturing the paint, although not limited thereto, it is preferable to knead a heat-expanded body of volcanic glassy powder, a resin, and, if necessary, a medium for the paint, and gradually add cellulose microfibers thereto and further knead.

[0055] As the cellulose microfibers, it is preferable to use cellulose microfibers in a state of being dispersed in a dispersion medium (a dispersion of cellulose microfibers). By gradually adding the cellulose microfibers in a state of a dispersion, it becomes easy to uniformly disperse the cellulose microfibers in the paint. Also, it becomes easy to adjust the viscosity of the paint to an appropriate range. Also, as the resin, it is preferable to use a resin emulsion.

[0056] The method of kneading is not particularly limited. Kneading may be performed by a usual method used for manufacturing the paint while applying an appropriate shear so that the hollow shape of the fine particles of the heat-expanded body is not damaged too much.

[0057] (Use) The paint of the present invention can form a coating film having both heat shielding and sound insulation effects, and can be applied and used on various substrates for the purpose of obtaining these effects or one of these effects. For example, but not limited to, it can be applied on various substrates such as metal, concrete, mortar, ceramic, glass, porcelain, plaster, galvanized steel sheet, plastic, wood, wallpaper, etc. In addition, it can be applied to the roofs, ceilings, outer walls, inner walls, etc. of various structures or buildings such as vehicles, ships, airplanes, trains, storage tanks, containers, silos, pipes, houses, factories, etc.

[0058] The coating method is not particularly limited, and various methods such as a brush, a roller, a spray, a dip coating, etc. can be used. After coating, the paint can be dried by methods such as natural drying or heat drying to form a coating film on the substrate.

Examples

[0059] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto. Unless otherwise specified, parts and % indicate parts by mass and mass %.

[0060] <Production of oxidized cellulose microfiber 1> 500 g (bone-dry) of bleached and unbeaten kraft pulp derived from coniferous trees (brightness 85%) was added to 20 L of an aqueous solution in which TEMPO (Sigma Aldrich) (0.025 mmol / g based on the cellulose raw material) and sodium bromide (1 mmol / g based on the cellulose raw material) were dissolved, and the mixture was stirred until the pulp was uniformly dispersed. An aqueous sodium hypochlorite solution was added to the reaction system to a concentration of 5.2 mmol / g to initiate the oxidation reaction. During the reaction, the pH of the system decreased, but 3M aqueous sodium hydroxide solution was sequentially added 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. The mixture after the reaction was filtered through a glass filter to separate the pulp, and the pulp was thoroughly washed with water to obtain oxidized pulp (oxidized cellulose fibers). The yield at this time was 90%, the time required for the oxidation reaction was 100 minutes, and the amount of carboxyl groups was 1.4 mmol / g.

[0061] The oxidized cellulose fibers obtained in the above process were adjusted to 1.0% (w / v) with water and treated 3 times with an ultra-high pressure homogenizer (20 °C, 150 MPa) to obtain a dispersion of oxidized cellulose microfibers 1. The obtained fibers had an average fiber diameter of 4 nm and an aspect ratio of 220.

[0062] <Production of Oxidized Cellulose Microfibers 2> 500 g (dry weight) of bleached softwood-derived dissolved kraft pulp (DKP manufactured by Bakai Co., Ltd.) was added to 50 L of an aqueous solution in which TEMPO (Sigma Aldrich, 0.5 mmol with respect to the cellulose raw material) and sodium bromide (7.4 mmol with respect to the cellulose raw material) were dissolved, and the mixture was stirred until the pulp was uniformly dispersed. After adding 1.6 L of 2 M aqueous sodium hypochlorite solution to the reaction system, the pH was adjusted to 10.3 with 0.5 N aqueous hydrochloric acid solution to initiate the oxidation reaction (oxidation treatment). During the reaction, the pH in the system decreased, but 0.5 N aqueous sodium hydroxide solution was sequentially added to adjust the pH to 10. The reaction was carried out for 2 hours, followed by filtration through a glass filter and thorough washing with water to obtain oxidized cellulose fibers. This was made into a slurry at 5.0% (w / v) with water, and hydrogen peroxide was added to this at 2% by mass with respect to the oxidized cellulose fibers, and the pH was adjusted to 11.3 with 3 M sodium hydroxide. This slurry was left at 80 °C for 2 hours for hydrolysis. This was adjusted to 5.0% (w / v) with water and treated 5 times with an ultra-high pressure homogenizer (20 °C, 140 MPa) to obtain a dispersion of oxidized cellulose microfibrils 2. The amount of carboxyl groups in the obtained oxidized cellulose microfibrils 2 was 1.7 mmol / g, the average fiber diameter was 4 nm, and the aspect ratio was 117.

[0063] <Manufacture of Paint 1> In a 200 mL beaker, 6.7 parts by mass of a heat-expanded volcanic glassy powder (manufactured by Maruwa Clay Co., Ltd., trade name: Marlite (registered trademark) 722B, average particle size 30 - 40 μm, bulk density 0.15 g / mL, floating water ratio 75 - 85% by mass), 6.0 parts by mass of an aqueous dispersion of 55% by mass resin solids of an ethylene / vinyl acetate copolymer (manufactured by Artec Co., Ltd., trade name: Power Ace (registered trademark) Quick-Drying Clear), and 17.3 parts by mass of water were charged, and the mixture was kneaded with a spatula for about 5 minutes until uniform. Then, 50 parts by mass of an aqueous dispersion of 1% by mass solids of oxidized cellulose microfibrils 1 was added, and the mixture was stirred until uniform to obtain Paint 1.

[0064] <Manufacture of Paint 2> Paint 2 was obtained in the same manner as the manufacture of Paint 1, except that 10 parts by mass of an aqueous dispersion of 5% by mass solids of oxidized cellulose microfibrils 2 was added instead of the aqueous dispersion of oxidized cellulose microfibrils 1.

[0065] <Manufacture of Comparative Paint 3> Comparative Paint 3 was obtained in the same manner as the manufacture of Paint 1, except that the aqueous dispersion of oxidized cellulose microfibers 1 was not added.

[0066] <Comparative Paint 4> As Comparative Paint 4, a commercially available heat insulating and sound insulating paint (manufactured by Nisshin Sangyo Co., Ltd., trade name: GAINA (registered trademark)) was used.

[0067] <Heat Insulation Test> Approximately 3.5 g of each paint that had been degassed under reduced pressure was weighed and applied with a spatula to an area of 70 × 50 mm on one side of an 80 × 60 × 0.5 mm copper plate. After drying at room temperature for 12 hours, it was dried in an oven at 80°C for 1.5 hours to obtain a coated plate. Note that the fluidity of each paint used was approximately the same.

[0068] The coated plate sandwiched between two thermocouples was placed on a hot plate, and the temperature was set to rise from room temperature to 100°C in approximately 1 minute. The temperature difference between the front and back of each coated plate was recorded every 30 seconds from the start of temperature rise until 180 seconds later. Also, for the copper plate without the paint applied, the temperature difference between the front and back was recorded every 30 seconds until 180 seconds later in the same manner. At each second, the difference (°C) between the temperature difference between the front and back of each coated plate and the temperature difference between the front and back of the copper plate alone was calculated. For each difference obtained every second, the average value was calculated for each coated plate. The greater this difference, the higher the heat insulation. The results are shown in Table 1.

[0069] <Sound Insulation Test 1> A coated plate was prepared in the same manner as in the heat shielding test. The coated plate was placed horizontally, and a speaker was installed 1 cm above the paint application surface (the surface of the coated plate). Sounds of each frequency of 440, 600, 1000, 2000, 3000, 5000, and 7000 Hz were emitted, and the sound pressure (dB) was measured with a sound level meter installed at a position 0.5 cm below the back surface of the coated plate. Also, the sound pressure at each frequency was measured in the same manner for a copper plate without paint application. For each frequency, the difference (dB) between the measured value of the sound pressure of each coated plate and the measured value of the sound pressure of the copper plate was calculated. For each coated plate, the average value was calculated for the sound pressure differences obtained for each frequency. The greater the sound pressure difference, the higher the sound insulation performance. The results are shown in Table 1.

[0070] <Sound Insulation Test 2> Table 1 shows the difference between the sound pressure of the coated plate and the sound pressure of the copper plate at 440 Hz measured and calculated in Sound Insulation Test 1.

[0071]

Table 1

[0072] As shown in Table 1, the paint of the present invention has both heat shielding and sound insulation properties, and has a high effect even when compared with a commercially available heat shielding and sound insulation paint (Comparative Paint 4).

Claims

Claim 1 A heat-insulating and sound-insulating paint containing a heat-expanded body of volcanic glass powder, cellulose microfibers, and a resin. Claim 2 The heat-insulating and sound-insulating paint according to Claim 1, wherein the average fiber diameter of the cellulose microfibers is 2 to 500 nm. Claim 3 The heat-insulating and sound-insulating paint according to Claim 1 or 2, wherein the cellulose microfibers are chemically modified cellulose microfibers. Claim 4 The heat-insulating and sound-insulating paint according to Claim 3, wherein the chemically modified cellulose microfibers are oxidized cellulose microfibers.

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