JP7180118B2 - Carboxymethylated cellulose nanofiber hydrophobe and method for producing the same - Google Patents

Description

The present invention relates to hydrophobes of carboxymethylated cellulose nanofibers. Specifically, the present invention relates to a hydrophobe of carboxymethylated cellulose nanofibers having a specific range of carboxymethyl substitution degree and cellulose type I crystallinity and exhibiting high transparency when dispersed in water, and a method for producing the same.

Carboxymethylated cellulose is a derivative of cellulose, and is obtained by ether-bonding carboxymethyl groups to some of the hydroxyl groups in the glucose residues that constitute the skeleton of cellulose. Carboxymethylated cellulose is used as various additives such as thickeners, caking agents, binders, water-absorbing materials, water-retaining materials, and emulsion stabilizers in cosmetics, pharmaceuticals, foods, various industrial products, and the like. Since carboxymethylated cellulose is derived from natural cellulose, it has moderate biodegradability and is an environmentally friendly material that can be disposed of by incineration.

As a method for producing carboxymethylated cellulose, generally, cellulose is treated with an alkali (mercerization), and then treated with an etherification agent (also referred to as a carboxymethylation agent) (carboxymethylation, also referred to as etherification). Methods are known, and a method in which both mercerization and carboxymethylation are performed using water as a solvent, and a method in which both mercerization and carboxymethylation are performed in a solvent mainly composed of an organic solvent (Patent Document 1 ) are known, the former being called the “aqueous method” and the latter being called the “solvent method”.

As the amount of carboxymethyl groups in carboxymethylated cellulose increases (ie, the degree of carboxymethyl substitution increases), the carboxymethylated cellulose becomes more soluble in water. On the other hand, by adjusting the degree of carboxymethyl substitution to an appropriate range, the fibrous shape of carboxymethylated cellulose can be maintained even in water. Carboxymethylated cellulose having a fibrous shape can be converted into nanofibers having a nanoscale fiber diameter by mechanical defibration (Patent Document 2).

JP 2017-149901 A WO2014/088072

Carboxymethylated cellulose is used as an additive in various fields such as rubber, resin, and paint. Carboxymethylated cellulose nanofibers, which are nanofibers made from carboxymethylated cellulose, are also expected to have effects such as increased strength when used as additives in various fields.

However, cellulose nanofibers obtained by fibrillating carboxymethylated cellulose obtained by the conventional solvent method have low transparency when made into an aqueous dispersion, and the range of use as an additive is limited. In addition, cellulose nanofibers obtained by fibrillating carboxymethylated cellulose obtained by the aqueous method require the use of large amounts of chemicals such as mercerizing agents and carboxymethylating agents in order to increase transparency. It was a big problem in terms of both business and economy.
In addition, since carboxymethylated cellulose is water-soluble, it has poor compatibility with rubber, resin, and organic solvent, and when mixed as it is, a sufficient strength-increasing effect cannot be obtained.
It is an object of the present invention to provide a carboxymethylated cellulose nanofiber hydrophobe that forms an aqueous dispersion with a high degree of crystallinity and a high degree of transparency.

The present inventors have conducted intensive studies for the above purpose, and as a result, in the carboxymethylation of cellulose, mercerization (alkali treatment of cellulose) is performed in a solvent mainly containing water, and then carboxymethylation. (also called etherification) in a mixed solvent of water and an organic solvent, the conventional aqueous medium method (method in which both mercerization and carboxymethylation are performed using water as a solvent) or solvent method (mercerization) Compared to the carboxymethylated cellulose obtained by the method in which both the conversion and the carboxymethylation are performed in a solvent mainly composed of an organic solvent), the cellulose nanofiber dispersion, which has extremely high transparency when defibrated, is obtained by carboxymethylation. We have found that it can be produced economically with a high effective utilization of the methylating agent. In addition, the hydrophobe of this carboxymethylated cellulose nanofiber is homogeneous, has excellent dispersion stability in rubber, resin, and organic solvent, and has high crystallinity and transparency, so that it can be suitably used in various fields including these. I found

The present invention includes, but is not limited to, the following.
(1) Light with a wavelength of 660 nm when the crystallinity of cellulose type I is 60% or more, the degree of carboxymethyl substitution is 0.50 or less, and the solid content is 1% (w / v). A method for producing a hydrophobic substance of carboxymethylated cellulose nanofibers, characterized by hydrophobizing carboxymethylated cellulose nanofibers having a transmittance of 60% or more.
(2) The carboxymethylated cellulose nanofibers are produced by subjecting the carboxymethylated cellulose nanofibers to a mercerization reaction in a solvent mainly containing water, and then a carboxymethylation reaction in a mixed solvent of water and an organic solvent. The production method according to (1), which is obtained by defibrating methylated cellulose.
(3) The production method according to (2), wherein the water-based solvent is a solvent containing more than 50% by mass of water.
(4) Hydrophobic substances of carboxymethylated cellulose nanofibers, wherein the cellulose type I crystallinity of the carboxymethylated cellulose nanofibers is 60% or more and the degree of carboxymethyl substitution is 0.50 or less. A hydrophobe of carboxymethylated cellulose nanofibers characterized by:
(5) The hydrophobic substance according to (4), wherein the hydrophobic substance of the carboxymethylated cellulose nanofibers has an average fiber diameter of 3 nm to 500 nm.
(6) A rubber composition using the hydrophobic carboxymethylated cellulose nanofiber of (4) or (5).

The hydrophobic substance of the carboxymethylated cellulose nanofibers of the present invention is homogeneous, has excellent dispersion stability in rubber, resin, and organic solvents, and has high crystallinity and transparency, so it is suitable for various fields including these. can be used.

<Nanofibers of carboxymethylated cellulose>
In the present invention, the degree of carboxymethyl substitution is 0.50 or less, the crystallinity of cellulose type I is 60% or more, and the wavelength when made into an aqueous dispersion with a solid content of 1% (w / v) The present invention relates to an additive containing carboxymethylated cellulose nanofibers having a transmittance of 660 nm light of 60% or more. Carboxymethylated cellulose has a structure in which some of the hydroxyl groups in glucose residues constituting cellulose are ether-bonded to carboxymethyl groups.

The nanofibers of carboxymethylated cellulose are obtained by converting carboxymethylated cellulose having the above structure into nanofibers having a nanoscale fiber diameter. The carboxymethylated cellulose may be in the form of a salt, for example a metal salt such as the sodium salt of carboxymethylated cellulose, and the carboxymethylated cellulose nanofibers may also be in the form of a salt.

The carboxymethylated cellulose nanofibers of the present invention maintain at least a part of the fibrous shape even when dispersed in water. That is, when an aqueous dispersion of carboxymethylated cellulose nanofibers is observed with an electron microscope, a fibrous substance can be observed. Also, when carboxymethylated cellulose nanofibers are measured by X-ray diffraction, peaks of cellulose type I crystals can be observed.

<Crystallinity of cellulose type I>
The crystallinity of cellulose in the carboxymethylated cellulose nanofibers used in the present invention is 60% or more, preferably 65% or more for crystalline type I. When the crystallinity of cellulose type I is as high as 60% or more, the proportion of cellulose that maintains the crystal structure without dissolving in the solvent is high, so when added to rubber or resin, it can increase the strength. You get the advantage. The crystallinity of cellulose can be controlled by the concentration of the mercerizing agent and temperature during treatment, as well as the degree of carboxymethylation. Since high concentrations of alkali are used in mercerization and carboxymethylation, type I crystals of cellulose tend to be converted to type II crystals. Desired crystallinity can be maintained by adjusting the degree. The upper limit of the crystallinity of cellulose type I is not particularly limited. Realistically, it is considered that the upper limit is about 90%.

The method for measuring the cellulose type I crystallinity of carboxymethylated cellulose nanofibers is as follows:
A sample is placed in a glass cell and measured using an X-ray diffraction measurement device (LabX XRD-6000, manufactured by Shimadzu Corporation). The crystallinity is calculated using the method of Segal et al., and the diffraction intensity at 2θ = 10 ° to 30 ° in the X-ray diffraction diagram is used as a baseline, and the diffraction intensity at 2θ = 22.6 ° 002 plane and 2θ = It is calculated by the following formula from the diffraction intensity of the amorphous portion at 18.5°.
Xc = (I002c - Ia)/I002c x 100
Xc = crystallinity of cellulose type I (%)
I002c: 2θ=22.6°, diffraction intensity of 002 plane Ia: 2θ=18.5°, diffraction intensity of amorphous portion.

The proportion of type I crystals in the carboxymethylated cellulose nanofibers is generally the same as in the carboxymethylated cellulose before nanofibers.

<Carboxymethyl substitution degree>
The carboxymethylated cellulose nanofibers used in the present invention have a degree of carboxymethyl substitution of 0.50 or less per anhydroglucose unit of cellulose. If the degree of carboxymethyl substitution exceeds 0.50, it is considered that the fiber dissolves in water and the fiber shape cannot be maintained. Considering the workability, the degree of substitution is preferably 0.02 to 0.50, more preferably 0.05 to 0.50, further preferably 0.10 to 0.40, It is more preferably 0.20 to 0.40. By introducing carboxymethyl groups into cellulose, the celluloses electrically repel each other, making it possible to defibrate into nanofibers. If it is too small, defibration will be insufficient, and cellulose nanofibers with high transparency may not be obtained. In the conventional aqueous method, it is difficult to obtain carboxymethylated cellulose nanofibers with a cellulose type I crystallinity of 60% or more when the degree of carboxymethyl substitution is in the range of 0.20 to 0.40. However, the present inventors have found, for example, by the method described later, that the degree of carboxymethyl substitution is in the range of 0.20 to 0.40 and the crystallinity of cellulose type I is 60% or more. We have found that cellulose nanofibers can be produced. The degree of carboxymethyl substitution can be adjusted by controlling the added amount of the carboxymethylating agent to be reacted, the amount of the mercerizing agent, the composition ratio of water and the organic solvent, and the like.

Anhydroglucose units in the present invention mean individual anhydroglucose (glucose residues) constituting cellulose. In addition, the degree of carboxymethyl substitution (also referred to as the degree of etherification) refers to the ratio of hydroxyl groups in glucose residues that constitute cellulose that are substituted with carboxymethyl ether groups (carboxymethyl ether per glucose residue). number of ether groups). The degree of carboxymethyl substitution may be abbreviated as DS.

The method for measuring the degree of carboxymethyl substitution is as follows:
About 2.0 g of the sample is precisely weighed and placed in a 300 mL Erlenmeyer flask with a common stopper. Add 100 mL of a liquid obtained by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol nitrate and shake for 3 hours to convert the salt of carboxymethylated cellulose nanofibers (CMC) to H-CMC (hydrogenated carboxymethylated cellulose nanofibers). . Accurately weigh 1.5 to 2.0 g of the absolute dry H-CMC and put it in a 300 mL Erlenmeyer flask with a common stopper. Wet the H-CMC with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. Excess NaOH is back-titrated with 0.1N—H ₂ SO ₄ using phenolphthalein as an indicator, and the degree of carboxymethyl substitution (DS value) is calculated by the following equation.
A = [(100 x F'-0.1N-H ₂ SO ₄ (mL) x F) x 0.1]/(absolute dry mass of H-CMC (g))
Carboxymethyl substitution degree = 0.162 × A / (1-0.058 × A)
F′: factor of 0.1N—H ₂ SO ₄ F: factor of 0.1N—NaOH.

The degree of carboxymethyl substitution in the nanofibers of carboxymethylated cellulose is generally the same as the degree of carboxymethyl substitution in the carboxymethylated cellulose before nanofibers.

<Transparency in water dispersion>
The carboxymethylated cellulose nanofibers used in the present invention are characterized by exhibiting high transparency when made into a dispersion using water as a dispersion medium (aqueous dispersion). Highly transparent nanofibers can also be used as additives for applications that require transparency, and are therefore preferred. In this specification, transparency refers to the transmittance of light with a wavelength of 660 nm when carboxymethylated cellulose nanofibers are dispersed in water with a solid content of 1% (w/v). The method for measuring the transparency of carboxymethylated cellulose nanofibers is as follows:
A cellulose nanofiber dispersion (solid content 1% (w / v), dispersion medium: water) was prepared, and a UV-VIS spectrophotometer UV-1800 (manufactured by Shimadzu Corporation) was used to prepare a square cell with an optical path length of 10 mm. is used to measure the transmittance of 660 nm light.

The carboxymethylated cellulose nanofibers of the present invention have a transparency of 60% or more. More preferably 60 to 100%, still more preferably 70 to 100%, still more preferably 80 to 100%, still more preferably 90 to 100%. Such cellulose nanofibers can be optimally used for applications requiring transparency. Carboxymethylated cellulose nanofibers having the aforementioned cellulose type I crystallinity and carboxymethyl substitution degree and such transparency can be produced, for example, by the method described below.

<Fiber diameter, aspect ratio>
The carboxymethylated cellulose nanofibers used in the present invention have a nanoscale fiber diameter. The average fiber diameter is preferably 3 nm to 500 nm, more preferably 3 nm to 150 nm, still more preferably 3 nm to 20 nm, still more preferably 5 nm to 19 nm, still more preferably 5 nm to 15 nm.

The aspect ratio of the carboxymethylated cellulose nanofibers is not particularly limited, but is preferably 350 or less, more preferably 300 or less, further preferably 200 or less, further preferably 120 or less. , is more preferably 100 or less, and more preferably 80 or less. When the aspect ratio is 350 or less, the fibers are not excessively long, the entanglement between the fibers is reduced, and the generation of clumps (lumps) of cellulose nanofibers can be reduced. Suitable. In addition, since it has high fluidity, it is easy to use even at a high concentration, and there is an advantage that it is easy to use even in applications where a high solid content is required. Although the lower limit of the aspect ratio is not particularly limited, it is preferably 25 or more, more preferably 30 or more. When the aspect ratio is 25 or more, the effect of improving thixotropy can be obtained from the fibrous shape. The aspect ratio of carboxymethylated cellulose nanofibers can be controlled by the mixing ratio of solvent and water during carboxymethylation, the amount of chemicals added, and the degree of carboxymethylation, and can be produced, for example, by the method described below. .
The average fiber diameter and average fiber length of nanofibers of carboxymethylated cellulose are measured using an atomic force microscope (AFM) when the diameter is 20 nm or less, and a field emission scanning electron microscope (FE-SEM) when the diameter is 20 nm or more. It can be measured by analyzing 200 randomly selected fibers and calculating the average. Also, the aspect ratio can be calculated by the following formula:
Aspect ratio = average fiber length/average fiber diameter.

<Viscosity and thixotropy in water dispersion>
The carboxymethylated cellulose nanofibers used in the present invention preferably exhibit high thixotropic properties when formed into a dispersion (aqueous dispersion) using water as a dispersion medium. The thixotropic property (thixotropy) refers to the property that the viscosity gradually decreases when subjected to shear stress, and the viscosity gradually increases when it is at rest. Use the value divided by the viscosity measured at high shear rate. Specifically, viscosity and thixotropy are measured by the following methods:
A cellulose nanofiber dispersion (solid content 1% (w/v), dispersion medium: water) was prepared, left at 25 ° C. for 16 hours, and then stirred at 3000 rpm for 1 minute using a stirrer to obtain a sample for viscosity measurement. and Some of the obtained samples for viscosity measurement were measured using a Brookfield viscometer (manufactured by Toki Sangyo Co., Ltd.). Measure the viscosity after 3 minutes at 4 rotors/6 rpm. Another part of the sample for viscosity measurement (those whose viscosity has not yet been measured) was measured using a B-type viscometer (manufactured by Toki Sangyo). Measure the viscosity after 3 minutes at 4 rotors/60 rpm. The method of JIS-Z-8803 is followed when measuring the viscosity. A value obtained by dividing the obtained viscosity at 6 rpm by the viscosity at 60 rpm is used as an index of thixotropy.

The carboxymethylated cellulose nanofiber used in the present invention has a viscosity at 25 ° C. and 6 rpm when made into an aqueous dispersion with a solid content of 1% (w / v). The value obtained by dividing the viscosity at 25° C. and 60 rpm (also referred to simply as “the value obtained by dividing the viscosity at 6 rpm by the viscosity at 60 rpm”) is preferably 6.0 or more. The higher this value, the greater the change in viscosity due to the difference in shear stress, and the higher the thixotropy. Cellulose nanofibers with high thixotropy are suitable for use as a shape-retaining agent and a viscosity modifier. Although the upper limit of the value obtained by dividing the viscosity at 6 rpm by the viscosity at 60 rpm is not limited, the upper limit is considered to be about 15.0 in practice.

The viscosity of the carboxymethylated cellulose nanofibers at 6 rpm (1% solids (w/v) aqueous dispersion, 25°C) is preferably 15,000 mPa s or more, more preferably 20,000 mPa s or more. . Higher viscosity at low shear rate (6 rpm) can lead to higher thixotropy. Although the upper limit of the viscosity at 6 rpm is not particularly limited, it is considered to be about 50000 mPa·s in reality.

The viscosity of the carboxymethylated cellulose nanofibers at 60 rpm (solid content 1% (w/v) aqueous dispersion, 25° C.) is preferably about 1500 to 8400 mPa s, more preferably about 2000 to 7000 mPa s. is more preferably about 2500 to 7000 mPa·s, and even more preferably about 3000 to 7000 mPa·s.

Carboxymethylated cellulose nanofibers having such viscosity and thixotropy can be produced, for example, by the method described below.

<Hydrophobicization>
The carboxymethylated cellulose nanofibers used in the present invention may be those in which the carboxyl group (-COOH) derived from the carboxymethyl group is appropriately modified within a range that does not impair the effects of the present invention. Examples of such modification include bonding an amine-based compound or a phosphorus-based compound having an alkyl group, an aryl group, an aralkyl group, or the like to the carboxyl group to make the carboxymethylated cellulose nanofibers hydrophobic.

<Method for producing carboxymethylated cellulose nanofiber>
The crystallinity of cellulose I type is 60% or more, the degree of carboxymethyl substitution is 0.50 or less, and the transmittance of light at a wavelength of 660 nm when made into an aqueous dispersion with a solid content of 1% (w / v) The nanofibers of carboxymethylated cellulose having a ratio of 60% or more can be produced by, but not limited to, defibrating carboxymethylated cellulose produced by the following method.

Carboxymethylated cellulose is generally produced by treating (mercerizing) cellulose with an alkali, and then reacting the resulting mercerized cellulose (also referred to as alkali cellulose) with a carboxymethylating agent (also referred to as an etherifying agent). It can be manufactured by Carboxymethylated cellulose capable of forming nanofibers having the above characteristics of the present invention is subjected to mercerization (alkali treatment of cellulose) in a solvent mainly containing water, followed by carboxymethylation (also called etherification). ) in a mixed solvent of water and an organic solvent. The carboxymethylated cellulose obtained in this way can be processed by the conventional aqueous method (method in which both mercerization and carboxymethylation are performed using water as a solvent) or the solvent method (method in which both mercerization and carboxymethylation are performed using an organic solvent). Compared to the carboxymethylated cellulose obtained by the method performed in the presence of a solvent), it has a high effective utilization rate of the carboxymethylating agent, and when defibrated, it becomes a cellulose nanofiber dispersion with high transparency. can be converted.

<Cellulose>
In the present invention, cellulose means a polysaccharide having a structure in which D-glucopyranose (also referred to simply as "glucose residue" or "anhydroglucose") is linked by β-1,4 bonds. Cellulose is generally classified into natural cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose excluding non-crystalline regions, etc., according to its origin, production method, and the like. In the present invention, any of these celluloses can be used as a raw material for mercerized cellulose. It is preferable to use cellulose with a high degree of crystallinity as the raw material. The crystallinity of cellulose type I of the raw material cellulose is preferably 70% or more, more preferably 80% or more. The method for measuring the crystallinity of cellulose type I is as described above.

Examples of natural cellulose include bleached or unbleached pulp (bleached wood pulp or unbleached wood pulp); linters, purified linters; cellulose produced by microorganisms such as acetic acid bacteria. Raw materials for bleached or unbleached pulp are not particularly limited, and examples thereof include wood, cotton, straw, bamboo, hemp, jute, and kenaf. Also, the method for producing the bleached pulp or the unbleached pulp is not particularly limited, and may be a mechanical method, a chemical method, or a combination of the two. Examples of bleached pulp or unbleached pulp classified by manufacturing method include mechanical pulp (thermomechanical pulp (TMP), groundwood pulp), chemical pulp (softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP) ), softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP) and other kraft pulps). Further, dissolving pulp may be used in addition to paper pulp. Dissolving pulp is pulp that has been chemically refined, and is mainly used by dissolving it in chemicals, and serves as a main raw material for artificial fibers, cellophane, and the like.

Examples of regenerated cellulose include those obtained by dissolving cellulose in some solvent such as cuprammonium solution, cellulose xanthate solution, morpholine derivative, and spinning again.

The fine cellulose is obtained by subjecting cellulosic materials such as the natural cellulose and regenerated cellulose to depolymerization (for example, acid hydrolysis, alkaline hydrolysis, enzymatic decomposition, explosion treatment, vibration ball mill treatment, etc.). and those obtained by mechanically processing the above cellulosic materials.

<Mercerization>
Mercerized cellulose (also referred to as alkali cellulose) is obtained by using the aforementioned cellulose as a raw material and adding a mercerizing agent (alkali). According to the method described herein, by using water as the main solvent in this mercerization reaction and using a mixed solvent of an organic solvent and water in the subsequent carboxymethylation, the fibrillation becomes very Carboxymethylated cellulose that can be made into a cellulose nanofiber dispersion having high transparency can be obtained economically.

A solvent mainly containing water (solvent mainly containing water) refers to a solvent containing water in a proportion higher than 50% by mass. Water in the solvent containing water as a main component is preferably 55% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, It is more preferably 90% by mass or more, and still more preferably 95% by mass or more. Particularly preferably, the water-based solvent is 100 mass % water (ie, water). The greater the proportion of water during mercerization, the higher the transparency of the cellulose nanofiber dispersion obtained by defibrating carboxymethylated cellulose. Examples of the solvent other than water (used in a mixture with water) in the solvent mainly containing water include the organic solvent used as the solvent for the subsequent carboxymethylation. For example, alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, tertiary butanol; ketones such as acetone, diethyl ketone, methyl ethyl ketone; and dioxane, diethyl ether, benzene, dichloromethane. and the like, and a mixture of these alone or two or more thereof can be added to water in an amount of less than 50% by mass and used as a solvent for mercerization. The organic solvent in the solvent mainly containing water is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, and still more preferably 20% by mass or less. , more preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 0% by mass.

The mercerizing agent includes, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and any one of these or a combination of two or more thereof can be used. The mercerizing agent is, but is not limited to, these alkali metal hydroxides, for example, 1 to 60% by weight, preferably 2 to 45% by weight, more preferably 3 to 25% by weight of aqueous solution in the reactor. can be added.

The amount of the mercerizing agent used is an amount that can maintain the cellulose type I crystallinity of 60% or more in the carboxymethylated cellulose. It is preferably 0.5 mol or less, more preferably 0.3 mol or more and 2.0 mol or less, and even more preferably 0.4 mol or more and 1.5 mol or less.

The amount of the solvent mainly composed of water during mercerization is preferably 1.5 to 20 times the weight of the cellulose raw material, more preferably 2 to 10 times the weight. Such an amount facilitates stirring and mixing of the raw materials, and allows the raw materials to react uniformly.

In the mercerization treatment, the bottom raw material (cellulose) and a solvent mainly composed of water are mixed, and the temperature of the reactor is adjusted to 0 to 70°C, preferably 10 to 60°C, more preferably 10 to 40°C. Then, an aqueous solution of a mercerizing agent is added and stirred for 15 minutes to 8 hours, preferably 30 minutes to 7 hours, more preferably 30 minutes to 3 hours. This gives mercerized cellulose (alkali cellulose).

The pH during mercerization is preferably 9 or higher, which allows the mercerization reaction to proceed. The pH is more preferably 11 or higher, still more preferably 12 or higher, and may be 13 or higher. The upper limit of pH is not particularly limited.
Mercerization can be performed using a reactor capable of mixing and stirring the above components while controlling the temperature, and various reactors conventionally used for mercerization reactions can be used. For example, a batch-type stirring device in which two shafts stir to mix the above components is preferable from the viewpoint of both uniform mixing and productivity.

<Carboxymethylation>
Carboxymethylated cellulose is obtained by adding a carboxymethylating agent (also referred to as an etherifying agent) to mercerized cellulose. According to the method described in this specification, by using water as a main solvent during mercerization and using a mixed solvent of water and an organic solvent during carboxymethylation, it is possible to Carboxymethylated cellulose that can be made into a cellulose nanofiber dispersion having high transparency can be obtained economically.

Carboxymethylating agents include monochloroacetic acid, sodium monochloroacetate, methyl monochloroacetate, ethyl monochloroacetate, isopropyl monochloroacetate and the like. Of these, monochloroacetic acid or sodium monochloroacetate is preferred in terms of availability of raw materials.

The amount of the carboxymethylating agent used is such that the crystallinity of cellulose type I can be maintained at 60% or more and the degree of carboxymethyl substitution is 0.50 or less. Although not particularly limited, in one embodiment, it is preferable to add in the range of 0.5 to 1.5 mol per anhydroglucose unit of cellulose. The lower limit of the above range is more preferably 0.6 mol or more, 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 carboxymethylating agent can be added to the reactor as, but not limited to, an aqueous solution of 5 to 80% by weight, more preferably 30 to 60% by weight, or in powder form without dissolving. can also

The molar ratio of the mercerizing agent to the carboxymethylating agent (mercerizing agent/carboxymethylating agent) is generally 0.9 to 2.45 when monochloroacetic acid or sodium monochloroacetate is used as the carboxymethylating agent. adopted by The reason is that if it is less than 0.9, the carboxymethylation reaction may be insufficient, and unreacted monochloroacetic acid or sodium monochloroacetate may remain and waste may occur, and 2.45 If it exceeds , there is a possibility that a side reaction with excessive mercerizing agent and monochloroacetic acid or sodium monochloroacetate will proceed to form an alkali metal glycolate, which may be uneconomical.

In carboxymethylation, the effective utilization rate of the carboxymethylating agent is preferably 15% or more. It is more preferably 20% or more, still more preferably 25% or more, and particularly preferably 30% or more. The effective utilization rate of the carboxymethylating agent refers to the proportion of carboxymethyl groups introduced into cellulose among the carboxymethyl groups in the carboxymethylating agent. By using a solvent mainly composed of water during mercerization and using a mixed solvent of water and an organic solvent during carboxymethylation, a high effective utilization rate of the carboxymethylating agent (i.e., carboxymethylating agent Without greatly increasing the amount used), carboxymethylated cellulose that can obtain a cellulose nanofiber dispersion having high transparency when defibrated can be produced. Although the upper limit of the effective utilization rate of the carboxymethylating agent is not particularly limited, the practical upper limit is about 80%. Note that the effective utilization rate of the carboxymethylating agent is sometimes abbreviated as AM.

The method for calculating the effective utilization of carboxymethylating agents is as follows:
AM = (DS × number of moles of cellulose) / number of moles of carboxymethylating agent DS: Degree of carboxymethyl substitution (measurement method is as described above)
Number of moles of cellulose: pulp mass (dry mass when dried at 100 ° C. for 60 minutes) / 162
(162 is the molecular weight per glucose unit of cellulose).
The concentration of the cellulose raw material in the carboxymethylation reaction is not particularly limited, but is preferably 1 to 40% (w/v) from the viewpoint of increasing the effective utilization rate of the carboxymethylating agent.

Simultaneously with the addition of the carboxymethylating agent, or before or immediately after the addition of the carboxymethylating agent, an organic solvent or an aqueous solution of an organic solvent is appropriately added to the reactor, or the pressure is reduced to remove water other than water during mercerization. is appropriately reduced to form a mixed solvent of water and an organic solvent, and the carboxymethylation reaction proceeds in this mixed solvent of water and an organic solvent. The timing of the addition or reduction of the organic solvent is not particularly limited as long as it is from the end of the mercerization reaction to immediately after the addition of the carboxymethylating agent. For example, 30 minutes before and after adding the carboxymethylating agent. Within is preferred.

Examples of organic solvents include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol and tertiary butanol; ketones such as acetone, diethyl ketone and methyl ethyl ketone; and dioxane, diethyl ether, Benzene, dichloromethane and the like can be mentioned, and these can be used alone or as a mixture of two or more of them added to water as a solvent for carboxymethylation. Among these, monohydric alcohols having 1 to 4 carbon atoms are preferred, and monohydric alcohols having 1 to 3 carbon atoms are more preferred, because of their excellent compatibility with water.
The ratio of the organic solvent in the mixed solvent during carboxymethylation is preferably 20% by mass or more, more preferably 30% by mass or more, relative to the total sum of water and the organic solvent. It is more preferably 40% by mass or more, further preferably 45% by mass or more, and particularly preferably 50% by mass or more. The higher the proportion of the organic solvent, the higher the transparency of the cellulose nanofiber dispersion. 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 even more preferably 70% by mass or less.

The reaction medium for carboxymethylation (a mixed solvent of water, an organic solvent, etc. that does not contain cellulose) has a lower proportion of water than the reaction medium for mercerization (in other words, the proportion of the organic solvent is more) is preferred. By satisfying this range, it becomes easier to increase the degree of carboxymethyl substitution while maintaining the crystallinity of the obtained carboxymethylated cellulose, and the carboxymethylated cellulose becomes a highly transparent cellulose nanofiber dispersion when defibrated. can be obtained more efficiently. Further, when the reaction medium for carboxymethylation has a lower proportion of water than the reaction medium for mercerization (the proportion of organic solvent is higher), when transitioning from the mercerization reaction to the carboxymethylation reaction, There is also the advantage that the mixed solvent for the carboxymethylation reaction can be formed by a simple means of adding a desired amount of organic solvent to the reaction system after the mercerization reaction is completed.

After forming a mixed solvent of water and an organic solvent and adding the carboxymethylating agent to the mercerized cellulose, the temperature is preferably kept constant in the range of 10 to 40°C for 15 minutes to 4 hours, preferably 15 minutes. Stir for about 1 minute to 1 hour. The liquid containing mercerized cellulose and the carboxymethylating agent are preferably mixed in multiple batches or by dropwise addition in order to prevent the reaction mixture from becoming hot. After adding the carboxymethylating agent and stirring for a certain period of time, if necessary, the temperature is raised to raise the reaction temperature to 30 to 90° C., preferably 40 to 90° C., more preferably 60 to 80° C., for 30 minutes or more. An etherification (carboxymethylation) reaction is carried out for 10 hours, preferably 1 to 4 hours to obtain carboxymethylated cellulose.
In the carboxymethylation, the reactor used in the mercerization may be used as it is, or another reactor capable of mixing and stirring the above components while controlling the temperature may be used. .

After completion of the reaction, residual alkali metal salts may be neutralized with a mineral acid or an organic acid. If necessary, by-produced inorganic salts, organic acid salts, etc. may be removed by washing with water-containing methanol, dried, pulverized, and classified to obtain carboxymethylated cellulose or salts thereof. When washing to remove by-products, it may be converted to an acid form in advance to form a linear form, and then converted back to a salt form after washing. Examples of devices used for dry pulverization include impact mills such as hammer mills and pin mills, medium mills such as ball mills and tower mills, and jet mills. Devices such as homogenizers, mass colloiders, and pearl mills are examples of devices used for wet pulverization.

<Fibrillation into nanofibers>
By defibrating the carboxymethylated cellulose obtained by the above method, it can be converted into cellulose nanofibers having a nanoscale fiber diameter.

For defibration, a dispersion of carboxymethylated cellulose obtained by the above method is prepared. The dispersion medium is preferably water for ease of handling. The concentration of carboxymethylated cellulose in the dispersion during fibrillation is preferably 0.01 to 10% (w/v) in consideration of the efficiency of fibrillation and dispersion.

The device used for defibrating carboxymethylated cellulose is not particularly limited, and devices such as high-speed rotation type, colloid mill type, high pressure type, roll mill type, and ultrasonic type can be used. It is preferable to apply a strong shearing force to the carboxymethylated cellulose dispersion during defibration. In particular, for efficient fibrillation, it is preferable to use a wet high-pressure or ultrahigh-pressure homogenizer capable of applying a pressure of 50 MPa or more to the dispersion and applying a strong shearing force. The pressure is more preferably 100 MPa or higher, still more preferably 140 MPa or higher. In addition, prior to fibrillation and dispersion treatment with a high-pressure homogenizer, the dispersion may be pretreated, if necessary, using a known mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer. .

A high-pressure homogenizer pressurizes (high pressure) a fluid with a pump and ejects it from very fine gaps provided in the flow path, emulsifying and dispersing by total energy such as shear force due to collision between particles and pressure difference. , shredding, pulverizing, and micronizing.

Although the reason why cellulose nanofibers with high transparency can be obtained by the above method is not clear, according to the above method, a relatively high crystallinity of cellulose type I can be maintained, and therefore the degree of carboxymethyl substitution The present inventors have confirmed that the fibrous shape of carboxymethylated cellulose can be maintained even when the is relatively high. It is thought that increasing the degree of carboxymethyl substitution while maintaining the fibrous shape (that is, introducing a large number of carboxymethyl groups) will lead to improved fibrillation properties of carboxymethylated cellulose, and this will lead to high transparency. It is speculated that this is one of the reasons why nanofiber dispersions are obtained. However, it is not limited to this.

<Method for producing hydrophobic substance>
Carboxymethylated cellulose nanofibers obtained by the above-described production method having a degree of carboxymethyl substitution of 0.50 or less, a cellulose type I crystallinity of 60% or more, and a transparency of 60% or more are hydrophobized. By doing so, it is possible to obtain a hydrophobic carboxymethylated cellulose nanofiber that is homogeneous, has excellent dispersion stability in rubber, resin, and organic solvent, and can be suitably used in various fields including these.

A hydrophobizing agent (surfactant) is used for the hydrophobization.

Surfactants are substances that can have at least one hydrophilic group and at least one hydrophobic group in the molecule, and precursors thereof (e.g., substances that can have both groups in the presence of metal salts). ). Examples of surfactants include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants.

Cationic surfactants include, for example, aliphatic amines (e.g., oleylamine, stearylamine, tetradecylamine, 1-hexenylamine, 1-dodecenylamine, 9,12-octadecadienylamine (linoleamine), 9 , 12,15-octadecatrienylamine, linoleylamine, dodecylamine, propylamine, monoalkylamines such as methylamine, dialkylamines, trialkylamines), tetramethylammonium salts (e.g., tetramethylammonium chloride, water tetramethylammonium oxide), tetrabutylammonium salts (e.g. tetrabutylammonium chloride), alkyltrimethylammonium salts (e.g. alkyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethyl chloride ammonium, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, alkyltrimethylammonium bromide, hexadecyltrimethylammonium bromide), benzyltrialkylammonium salts (e.g., benzyltrimethylammonium chloride, benzyltriethylammonium chloride, benzalkonium chloride (chloride dodecyldimethylbenzylammonium), benzalkonium bromide), dibenzyldialkylammonium salts (e.g. benzethonium chloride), dialkyldimethylammonium salts (e.g. didecyldimethylammonium chloride, distearyldimethylammonium chloride), alkylpyridinium salts (e.g. , butylpyridinium chloride, dodecylpyridinium chloride, cetylpyridinium chloride), aliphatic amine salts (eg, monomethylamine hydrochloride, dimethylamine hydrochloride, trimethylamine hydrochloride).

Examples of anionic surfactants include carboxylic acids (e.g., sodium octanoate, sodium decanoate, sodium laurate, sodium myristate, sodium palmitate, sodium stearate, perfluorononanoic acid, sodium N-lauroylsarcosinate, sodium cocoyl glutamate, alphasulfo fatty acid methyl ester salt), sulfonic acid (for example, sodium 1-hexanesulfonate, sodium 1-octanesulfonate, sodium 1-decanesulfonate, sodium 1-dodecanesulfonate, perfluorobutanesulfonic acid, Sodium linear alkylbenzenesulfonate, sodium toluenesulfonate, sodium cumenesulfonate, sodium octylbenzenesulfonate, sodium naphthalenesulfonate, disodium naphthalenesulfonate, trisodium naphthalenetrisulfonate, sodium butylnaphthalenesulfonate), sulfate (eg sodium lauryl sulfate, sodium myristyl sulfate, sodium laureth sulfate, sodium polyoxyethylene alkylphenol sulfonate, ammonium lauryl sulfate), phosphate esters (eg lauryl phosphate, sodium lauryl phosphate, potassium lauryl phosphate).

Examples of nonionic surfactants include glycerin fatty acid esters (e.g., glycerin laurate, glycerin monostearate), sorbitan fatty acid esters, polyoxyethylene alkyl ethers (e.g., pentaethylene glycol monododecyl ether, octaethylene glycol monostearate). dodecyl ether), alkylphenol alkylates (e.g. polyoxyethylene alkylphenyl ether, octylphenol ethoxylate, nonylphenol ethoxylate), polyoxyalkylene glycols (e.g. polyoxyethylene polyoxypropylene glycol), polyoxyalkylene sorbitan fatty acid esters (e.g. , polyoxyethylene sorbitan fatty acid ester, polyoxyethylene hexitane fatty acid ester, sorbitan fatty acid ester polyethylene glycol), alkanolamides (e.g., lauric acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, cocamide DEA), alkyl glucosides ( Examples include octyl glucoside, decyl glucoside, lauryl glucoside).

Amphoteric surfactants include, for example, higher alcohols (e.g., cetanol, stearyl alcohol, oleyl alcohol), betaine compounds (e.g., betaine lauryldimethylaminoacetate, betaine stearyldimethylaminoacetate, dodecylaminomethyldimethylsulfopropylbetaine, octadecyl Aminomethyldimethylsulfopropyl betaine, cocamidopropyl betaine, cocamidopropyl hydroxyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine), alkyl amino acid salts (e.g. sodium lauroyl glutamate, potassium lauroyl glutamate) , lauroylmethyl-β-alanine), alkylamine oxides (eg, lauryldimethylamine N-oxide, oleyldimethylamine N-oxide).

Preferred surfactants are amphoteric surfactants and cationic surfactants.

The amphoteric surfactant is more preferably a betaine-based compound, and more preferably dodecylaminomethyldimethylsulfopropylbetaine, octadecylaminomethyldimethylsulfopropylbetaine, cocamidopropylbetaine.

Preferably, the surfactant comprises at least one aliphatic amine and its derivatives. The aliphatic amine is not particularly limited, but has 20 or less carbon atoms (preferably 2 to 20 or 3 to 20, more preferably 10 to 20, still more preferably 12 to 20, still more preferably 14 to 20, especially 1 selected from the group consisting of preferably 15 to 20), containing at least one (preferably one) unsaturated bond in its structure, and being a primary amine (monoalkylamine) It is preferable to satisfy the above conditions, and more preferable to satisfy all of them. Examples of aliphatic amines include oleylamine, stearylamine, tetradecylamine, 1-hexenylamine, 1-dodecenylamine, 9,12-octadecadienylamine (linoleamine), 9,12,15-octadecatrienylamine. monoalkylamines such as , linoleylamine, dodecylamine, propylamine, methylamine; dialkylamines; trialkylamines; , and propylamine are more preferred, and oleylamine is even more preferred. Examples of aliphatic amine derivatives include compounds other than the aliphatic amines listed as specific examples of cationic surfactants.

The surfactant used may be a single surfactant or a combination of two or more surfactants.

The field in which the hydrophobic substance of carboxymethylated cellulose nanofiber is used is not limited, and various fields in which additives are generally used, such as rubber, resin, cosmetics, medicine, paper manufacturing, various chemical products, paints, sprays, etc. Agrochemicals, civil engineering, construction, electronic materials, flame retardants, household goods, adhesives, detergents, fragrances, lubricating compositions, compounding materials for rubber and plastics, additives for paints, additives for adhesives, paper manufacturing additives, thickeners, gelling agents, thickeners, excipients, abrasives, water retention agents, shape retention agents, viscosity modifiers, emulsion stabilizers, dispersion stabilizers, slurry modifiers, filtration It can be used as an auxiliary agent, anti-flooding agent, and the like.

In the field of rubber, when a hydrophobe of carboxymethylated cellulose nanofibers is used in a rubber composition, it is common to use a mixture of the rubber component and the hydrophobe. A rubber component is a raw material of rubber, and refers to a material that is crosslinked to form rubber. The rubber component includes a rubber component for natural rubber and a rubber component for synthetic rubber. Examples of rubber components for natural rubber include narrowly defined natural rubber (NR) without chemical modification; chemically modified natural rubber such as chlorinated natural rubber, chlorosulfonated natural rubber, and epoxidized natural rubber; hydrogenated natural rubber; Rubber; includes deproteinized natural rubber. Examples of rubber components for synthetic rubber include butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber, styrene-isoprene copolymer Diene rubbers such as coalesced rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber; butyl rubber (IIR), ethylene-propylene rubber (EPM, EPDM), acrylic rubber (ACM), epichlorohydric Non-diene rubbers such as rubber (CO, ECO), fluorine rubber (FKM), silicone rubber (Q), urethane rubber (U), and chlorosulfonated polyethylene (CSM).

The rubber component may be used singly or in combination of two or more.

The content of the hydrophobic substance in the rubber composition is not particularly limited, but the preferred content is as follows.

The content of the hydrophobic material is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, relative to 100 parts by mass of the rubber component. Thereby, the effect of improving the tensile strength can be sufficiently exhibited. The upper limit is preferably 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less. Thereby, workability in the manufacturing process can be maintained. Therefore, it is preferably from 1 to 50 parts by mass, more preferably from 2 to 40 parts by mass, and even more preferably from 3 to 30 parts by mass.

<Optional component>
The rubber composition may contain one or more optional components depending on the use of the rubber composition, which will be described later. Optional components include, for example, reinforcing agents (e.g., carbon black, silica, etc.), silane coupling agents, cross-linking agents, vulcanization accelerators, vulcanization accelerator aids (e.g., zinc oxide, stearic acid), oil, curing Compounding agents that may be used in the rubber industry, such as resins, waxes, anti-aging agents, colorants and the like. Among these, vulcanization accelerators and vulcanization accelerator aids are preferred. The content of the optional component may be appropriately determined according to the type of the optional component, etc., and is not particularly limited.

If the rubber composition is an unvulcanized rubber composition or final product, it preferably contains a cross-linking agent. Examples of cross-linking agents include sulfur, halogenated sulfur, organic peroxides, quinone dioximes, organic polyvalent amine compounds, alkylphenol resins having methylol groups, and the like. Among these, sulfur is preferred. The content of the cross-linking agent is preferably 1.0 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 1.7 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 10 parts by mass or less, preferably 7 parts by mass or less, and more preferably 5 parts by mass or less.

Examples of vulcanization accelerators include Nt-butyl-2-benzothiazolylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide. The content of the vulcanization accelerator is preferably 0.1 parts by mass, more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more relative to the component (D). The upper limit is preferably 5 parts by mass or less, preferably 3 parts by mass or less, and more preferably 2 parts by mass or less.

In the rubber composition, the hydrophobe, rubber component and optional ingredients may each exist independently or as a composite such as a reactant of at least two components. The content of each component in the rubber composition is usually according to the amount used as the raw material.

<Application>
The use of the rubber composition of the present invention is not particularly limited as long as it is a composition for obtaining rubber as a final product. That is, it may be an intermediate (masterbatch) for rubber production, an unvulcanized rubber composition containing a vulcanizing agent, or a rubber as a final product. The use of the final product is not particularly limited, and examples include transportation equipment such as automobiles, trains, ships, and airplanes; electrical appliances such as personal computers, televisions, telephones, and clocks; mobile communication devices such as mobile phones, etc.; Equipment, image reproducing equipment, printing equipment, copying equipment, sporting goods, etc.; building materials; office equipment such as stationery, etc.; In addition to these, it can be applied to members using rubber or flexible plastic, and is suitable for application to tires. Examples of tires include pneumatic tires for passenger cars, trucks, buses, and heavy vehicles.

In addition, the hydrophobic substance of the formed carboxymethylated cellulose nanofibers of the present invention can be used for manganese dry batteries, alkaline manganese batteries, silver oxide batteries, lithium batteries, lead storage batteries, nickel-cadmium storage batteries, nickel-hydrogen storage batteries, nickel-zinc storage batteries. , silver oxide-zinc batteries, lithium ion batteries, lithium polymer batteries, various gel electrolyte batteries, all-solid-state batteries, zinc-air batteries, iron-air batteries, aluminum-air batteries, fuel cells, solar cells, sodium-sulfur batteries, It can be used as a member of various batteries such as polyacene batteries, electrolytic capacitors, electric double layer capacitors (also referred to as electric double layer capacitors). It can be used as an insulating film (separator), an electrolyte film, and the like.

Cosmetic additives include, but are not limited to, cosmetic water retention agents, shape retention agents, viscosity modifiers, emulsion stabilizers, and dispersion stabilizers. Examples of cosmetics include lotions, serums, milky lotions, moisture creams, all-in-one gels, facial cleansing foams, foaming agents, cleansers, packs, sunscreens, massage products, whitening cosmetics, anti-aging products, skin care such as beauty masks. Goods; Make-up products such as foundation, lipstick, eyebrow, mascara, eyeliner, eye shadow, manicure, nail care, face powder, lip balm, lip gloss, lip liner, blush, BB cream, concealer; shampoo, hair color, treatment, Hair sprays, liquid hair styling products, hair creams, hair waxes, hair gels, set lotions, scalp care cosmetics, eyelash care cosmetics, eyebrow care cosmetics, perming agents, hair dye solutions, hair dye creams, hair restorers, etc. hair care products; body care products such as body creams, hand creams, body shampoos and soaps; In addition, the product is not limited to oil, liquid, wax, stick, powder, or sheet-like product, and may be an aerosol type product that is used together with a propellant such as liquefied petroleum gas.

For example, by blending the additive of the present invention into powdery makeup products such as foundation, eyebrow, and mascara, it improves the dispersibility of pigments, prevents lumps, and imparts shape retention or thixotropic properties to the product. Effects such as improved ease of use, fixability, and glossiness can be obtained.

Further, for example, by blending the additive of the present invention into cream-like, liquid-like, or gel-like cosmetics such as BB cream, moisture cream, hair cream, liquid hair dressing, hair gel, and hair wax, powder raw materials such as pigments can be obtained. Improvement of dispersibility of liquid ingredients, improvement of emulsification of liquid ingredients, ease of application by imparting thixotropy, improvement and maintenance of hair styling by imparting shape retention and thixotropy, and improvement of suppleness and glossiness. effect is obtained.

In addition, for example, by blending the additive of the present invention in cosmetics used in the form of foam such as shampoo, soap, body shampoo, facial cleanser, foaming agent, etc., the stability of the foam is improved by imparting shape retention, and the foam Effects such as improving and sustaining smoothness and moisture on the skin after rinsing can be obtained.

In addition, for example, by blending the additive of the present invention in cosmetics expected to impart moisture to the skin, such as lotions and serums, a high moisturizing effect can be obtained by imparting water retention with carboxymethylated cellulose nanofibers. be able to.

Further, for example, when the additive of the present invention is used in a mist-type lotion or the like, it is possible to obtain the effect of imparting thixotropic properties to facilitate spraying.

In addition, for example, when the additive of the present invention is used in a cosmetic pack, it is possible to obtain the effects of thixotropic properties and shape-retaining properties, such that it is difficult to drip after being applied to the skin and is easy to use.

Examples of pharmaceutical excipients include, but are not limited to, pharmaceutical water retention agents, shape retention agents, viscosity modifiers, emulsion stabilizers, and dispersion stabilizers. Foods that can be used include, but are not limited to, tablets, ointments, plasters, poultices, hand creams, toothpaste, and the like.

Examples of papermaking additives include, but are not limited to, papermaking water retention agents, shape retention agents, viscosity modifiers, emulsion stabilizers, and dispersion stabilizers. For example, it can be used as a surface sizing agent, a yield improver, a paper strength agent, a coating agent, an additive for bulky paper, and the like.

Paint additives include, but are not limited to, paint water retention agents, shape retention agents, viscosity modifiers, emulsion stabilizers, and dispersion stabilizers. Examples of paints include clear paints, matte paints, architectural paints, automobile interior paints, and the like.

In addition, dispersion stabilizers, reinforcing materials, etc. for daily necessities such as detergents, wraps, films, and bath agents; filtration of edible oils and various solvents (moisture removal); reinforcing materials for building materials such as fiber walls, sand walls, and gypsum boards; air bubble shields , civil engineering such as continuous wall waterproofing agents; resin fillers such as styrene foam, biodegradable resins, rubber, ceramics, and vinyl chloride, compounds, or reinforcing materials; fine particle carbon black, barium sulfate (X-ray contrast agent), titanium oxide and Dispersants such as zinc oxide dispersions; Moisture absorbent aids such as improving shape retention when deliquescent agents such as calcium chloride absorb moisture; fiber (fabric, thread) modifiers; liquid carriers; lubricating oils; ceramics cat litter; water-absorbing material for desiccant; greening method; binder.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these. Unless otherwise specified, parts and % indicate parts by mass and % by mass.

(Production example 1)
130 parts of water and 20 parts of sodium hydroxide dissolved in 100 parts of water are added to a twin-screw kneader whose rotation speed is adjusted to 150 rpm. 100 parts of the dry mass when dried for 1 minute were charged. The mixture was stirred and mixed at 35°C for 80 minutes to prepare mercerized cellulose. Further, 230 parts of isopropanol (IPA) and 60 parts of sodium monochloroacetate were added with stirring, and after stirring for 30 minutes, the temperature was raised to 70° C. and carboxymethylation reaction was carried out for 90 minutes. The concentration of IPA in the reaction medium during the carboxymethylation reaction is 50%. After completion of the reaction, the mixture was neutralized with acetic acid until the pH reached 7, washed with water-containing methanol, deliquored, dried and pulverized to obtain sodium salt of carboxymethylated cellulose.

The resulting sodium salt of carboxymethylated cellulose was dispersed in water to form a 1% solids (w/v) aqueous dispersion. This was treated with a high-pressure homogenizer at 140 MPa three times to obtain a dispersion of carboxymethylated cellulose nanofibers. The transparency and viscosity of the resulting dispersion, the average fiber diameter of cellulose nanofibers, the degree of carboxymethyl substitution, the crystallinity of cellulose type I, and the effective utilization rate of the carboxymethylating agent were measured by the methods described above. .

(Production example 2)
A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Production Example 1 except that the concentration of IPA in the reaction solution during the carboxymethylation reaction was changed to 90% by changing the amount of IPA added. The degree of carboxymethyl substitution was 0.47, the crystallinity of cellulose type I was 63%, and the effective utilization of the carboxymethylating agent was 56%. The obtained sodium salt of carboxymethylated cellulose was fibrillated in the same manner as in Production Example 1 to obtain a dispersion of carboxymethylated cellulose nanofibers.

(Production example 3)
A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Production Example 1, except that the concentration of IPA in the reaction solution during the carboxymethylation reaction was changed to 30% by changing the amount of IPA added. The obtained sodium salt of carboxymethylated cellulose was fibrillated in the same manner as in Production Example 1 to obtain a dispersion of carboxymethylated cellulose nanofibers.

(Production example 4)
Instead of dissolving 20 parts of sodium hydroxide in 100 parts of water during the mercerization reaction, a solution of 40 parts of sodium hydroxide dissolved in 100 parts of water was used, and sodium monochloroacetate was used as the carboxymethylating agent during the carboxymethylation reaction. A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Production Example 1, except that 50 parts of monochloroacetic acid was used instead of 60 parts. The degree of carboxymethyl substitution was 0.31, the crystallinity of cellulose type I was 60%, and the effective utilization rate of the carboxymethylating agent was 36%. The obtained sodium salt of carboxymethylated cellulose was fibrillated in the same manner as in Production Example 1 to obtain a dispersion of carboxymethylated cellulose nanofibers.

(Comparative Production Example 5)
The solvent for the carboxymethylation reaction was 100% water, and 45 parts of sodium hydroxide dissolved in 100 parts of water was used instead of 20 parts of sodium hydroxide dissolved in 100 parts of water during the mercerization reaction. A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Production Example 1, except that 150 parts of sodium monochloroacetate was used instead of 60 parts of sodium monochloroacetate as the carboxymethylating agent in the methylation reaction. The degree of carboxymethyl substitution was 0.28, the crystallinity of cellulose type I was 45%, and the effective utilization rate of the carboxymethylating agent was 13%. The obtained sodium salt of carboxymethylated cellulose was fibrillated in the same manner as in Production Example 1 to obtain a dispersion of carboxymethylated cellulose nanofibers.

(Example: Rubber composition)
<Example 1>
4.15 g of oleylamine was added while stirring 1000 g of the 1% solid content aqueous dispersion of carboxymethylated cellulose nanofibers obtained in Production Example 1 with a TK homomixer (4000 rpm), and the mixture was stirred for 30 minutes to obtain carboxymethylated cellulose. Nanofiber hydrophobes were obtained. Further, this hydrophobe was mixed with 500 g of a suspension having a solid content of 10% natural rubber latex so that the mass ratio of the rubber component to the hydrophobe was 100:20, and the mixture was stirred with a TK homomixer (8000 rpm) for 10 minutes. . Furthermore, while stirring with a three-one motor (150 to 300 rpm), a 10% by mass aqueous solution of aluminum sulfate was added until the concentration of aluminum sulfate reached 0.35% by mass, and after solid-liquid separation with a nylon mesh with an opening of 5 μm, ion exchange was performed. A masterbatch was obtained by washing with water and drying in a heating oven at 70° C. for 10 hours.

Solid natural rubber is added to this masterbatch so that the mass ratio of rubber component:modified cellulose nanofiber is 100:5, and 168 g is kneaded at 40° C. for 5 minutes with an open roll (manufactured by Kansai Roll Co., Ltd.). did. Next, 0.7 g of stearic acid (0.5 parts by mass with respect to 100 parts by mass of rubber component), 8.4 g of zinc oxide (6 parts by mass with respect to 100 parts by mass of rubber component), 4.9 g of sulfur (100 parts by mass of rubber component) 3.5 parts by mass per part), vulcanization accelerator (manufactured by Ouchi Shinko Chemical Co., Ltd., MSA-G, N-oxydiethylene-2-benzothiazolylsulfenamide)) 1 g (per 100 parts by mass of the rubber component 0.7 parts by mass) was added and kneaded at 60°C for 10 minutes using an open roll (manufactured by Kansai Roll Co., Ltd.) to obtain an unvulcanized rubber composition sheet.

This sheet was sandwiched between molds and press-vulcanized at 150° C. for 10 minutes to obtain a vulcanized rubber composition sheet having a thickness of 2 mm. This was cut into a test piece of a predetermined shape, and the tensile strength, which is one of the reinforcing properties, was measured according to JIS K6251 "Vulcanized rubber and thermoplastic rubber-Determination of tensile properties". The larger each numerical value, the better the vulcanized rubber composition is reinforced, indicating that the mechanical strength of the rubber is excellent.

<Example 2>
The procedure of Example 1 was repeated except that the carboxymethylated cellulose nanofibers obtained in Production Example 2 were used instead of the carboxymethylated cellulose nanofibers obtained in Production Example 1.

<Example 3>
The procedure of Example 1 was repeated except that the carboxymethylated cellulose nanofibers obtained in Production Example 3 were used instead of the carboxymethylated cellulose nanofibers obtained in Production Example 1.

<Example 4>
The procedure of Example 1 was repeated except that the carboxymethylated cellulose nanofibers obtained in Production Example 4 were used instead of the carboxymethylated cellulose nanofibers obtained in Production Example 1.

<Comparative Example 1>
The procedure of Example 1 was repeated except that the carboxymethylated cellulose nanofibers obtained in Comparative Production Example 5 were used instead of the carboxymethylated cellulose nanofibers obtained in Production Example 1.

<Tensile strength>
Tensile strength was measured by the method described above. As a result, Examples 1 to 4 using carboxymethylated cellulose nanofiber hydrophobic material having a cellulose type I crystallinity of 60% or more exhibited higher tensile strength than Comparative Example 1. The rubber compositions of Examples are well reinforced and have excellent rubber mechanical strength.

Claims (2)

The crystallinity of cellulose I type is 60% or more, the degree of carboxymethyl substitution is 0.50 or less, and the transmittance of light at a wavelength of 660 nm when made into an aqueous dispersion with a solid content of 1% (w / v) A method for producing a hydrophobic substance of carboxymethylated cellulose nanofibers, characterized by hydrophobizing carboxymethylated cellulose nanofibers having a is 60% or more ,
Carboxymethylated cellulose produced by subjecting the carboxymethylated cellulose nanofibers to a mercerization reaction in a solvent mainly containing water, and then a carboxymethylation reaction in a mixed solvent of water and an organic solvent. A method for producing a hydrophobic substance of carboxymethylated cellulose nanofibers, which is obtained by defibrating. 2. The production method according to claim 1, wherein the water-based solvent is a solvent containing more than 50% by mass of water.