JP5939695B1 - Viscous aqueous composition and method for producing the same - Google Patents

Abstract

An aqueous viscous composition capable of preparing a cellulose nanofiber aqueous dispersion that can be easily diluted uniformly and thereby has sufficient thickening and dispersion stability even with a general stirring device, and a method for producing the same. To provide. A viscous aqueous composition containing cellulose nanofibers, water, and a water-miscible organic solvent satisfying the following conditions. (A) Number average fiber diameter of 2 nm to 500 nm (B) Average aspect ratio of 50 to 1000 (C) Cellulose I-type crystal structure (D) Anionic functional group (E) Organic in organic conceptual diagram An organic compound having a property value of 450 or less is bonded to an anionic functional group by an ionic bond [selection figure] None

Description

 The present invention relates to a viscous aqueous composition and a method for producing the same.

In recent years, biomass raw materials have attracted attention as environmentally friendly materials.
Among these, a material in which the biomass raw material is in the form of fine fibers has attracted particular attention. Among them, cellulose nanofibers have been actively researched and developed as resin-reinforced materials, gas barrier films, thickeners, and the like (Patent Document 1). , 2). These describe a method of using cellulose nanofibers as a thickener and a dispersion stabilizer.

JP 2010-037348 A JP 2011-057567 A

  When the cellulose nanofiber aqueous dispersion is used as a thickener or dispersion stabilizer, it is difficult to dilute uniformly due to the strong hydrogen bonding of cellulose, and it is necessary to use a stirrer having a large shearing force. For this reason, a special device is required to uniformly dilute the cellulose nanofiber aqueous dispersion to a predetermined concentration. If you do not have such a device, use an aqueous dispersion of cellulose nanofiber. There was a problem that it was difficult.

  Accordingly, the present invention is an aqueous viscous composition that can easily prepare a cellulose nanofiber aqueous dispersion having a sufficient viscosity increase and dispersion stability even with a general stirring device, and can be easily diluted uniformly. The purpose is to provide a manufacturing method.

The present invention provides the following [1] to [ 9 ].
[1] A viscous aqueous composition containing cellulose nanofibers, water, and a water-miscible organic solvent satisfying the following conditions ,
The cellulose nanofiber content is 0.1% by mass or more and 20% by mass or less, and the water-miscible organic solvent content is 5% by mass or more and 80% by mass or less.
A viscous aqueous composition, wherein the ratio of the content of cellulose nanofiber and the content of water-miscible organic solvent is cellulose nanofiber / water-miscible organic solvent = 1/100 to 1/4 in terms of mass ratio .
(A) Number average fiber diameter of 2 nm to 500 nm (B) Average aspect ratio of 50 to 1000 (C) Cellulose I-type crystal structure (D) Anionic functional group (E) Organic in organic conceptual diagram An organic compound having a property value of 450 or less is bonded to an anionic functional group by an ionic bond
[2] The viscous aqueous composition according to [1], wherein the anionic functional group is a carboxyl group.
[3] The organic compound having an organic value of 450 or less in the organic conceptual diagram (E) is one or more selected from nitrogen-containing compounds and organic phosphorus compounds [1] ] Or the viscous aqueous composition according to [2].
[4] The organic compound having an organic value of 450 or less in the organic conceptual diagram (E) is one or more selected from ammonium and phosphonium [1] to [3] The viscous aqueous composition according to any one of the above.
[5] The viscous aqueous composition according to any one of [1] to [4], wherein the water-miscible organic solvent is an alcohol.
[6] The water-miscible organic solvent is methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol. 3-methoxy-1,2-propanediol, 2-butene-1,4-diol, 1,3-butanediol, 2-methyl-1,4-butanediol, 2-methyl-2,4-pentanediol, It should be one or more selected from 1,5-pentanediol, 1,4-pentanediol, 3-methyl-1,3-pentanediol, and 2,4-diethyl-1,5-pentanediol. [5] The viscous aqueous composition according to any one of [1] to [5].
[ 7 ] The viscosity of the viscous aqueous composition according to any one of [1] to [ 6 ] is such that the cellulose nanofiber content is 0.2% by mass, and in the BM type viscometer, the rotational speed of the rotor is 0. A viscous aqueous composition characterized by having a viscosity of 100 mPa · s or more when measured at 3 rpm and a liquid temperature of 20 ° C.
[ 8 ] (I) Oxidation step for oxidizing cellulose, (II) Purification step for adjusting pH of oxidized cellulose dispersion to 2 or less, and (III) Purified cellulose having an organic value in the organic conceptual diagram [1] to [1], comprising a neutralization step of neutralizing with an organic compound of 450 or less, and (IV) a dispersion step of dispersing the neutralized cellulose in the presence of water and a water-miscible organic solvent. 7 ] The method for producing a viscous aqueous composition according to any one of [ 7 ].
[ 9 ] The production method according to [ 8 ], wherein the dispersion condition in the dispersion step (IV) is a treatment with a high-pressure or ultrahigh-pressure homogenizer, and the treatment pressure is 30 MPa or more.

  The water-based viscous composition of the present invention can be easily diluted uniformly, thereby enabling the cellulose nanofiber aqueous dispersion having sufficient thickening and dispersion stability to be prepared even with a general stirring device. Play.

Next, embodiments of the present invention will be described in detail.
The aqueous viscous composition of the present invention contains a predetermined cellulose nanofiber.

(A) Number average fiber diameter The cellulose nanofiber has a number average fiber diameter of 2 nm to 500 nm, preferably 2 nm to 150 nm, more preferably 2 nm to 100 nm, and particularly preferably 2 nm to 80 nm. It is as follows. If the number average fiber diameter is less than 2 nm, the cellulose nanofibers may be dissolved, so that sufficient thickening and dispersion stability may not be exhibited. When the number average fiber diameter exceeds 500 nm, the surface area of the fiber However, since a sufficient nanofiber network structure is not formed, the viscosity and dispersion stability may be inferior.

The maximum fiber diameter of the cellulose nanofiber is preferably 1000 nm or less, particularly preferably 500 nm or less, from the viewpoint of dispersibility of the cellulose nanofiber.
The number average fiber diameter and the maximum fiber diameter of the cellulose nanofiber can be measured, for example, as follows. That is, an aqueous dispersion of fine cellulose having a solid content of 0.05 to 0.1% by weight was prepared, and the dispersion was cast on a carbon film-coated grid that had been subjected to a hydrophilization treatment. (TEM) observation sample. In addition, when the fiber of a big fiber diameter is included, you may observe the scanning electron microscope (SEM) image of the surface cast on glass. Then, observation with an electron microscope image is performed at a magnification of 5000 times, 10000 times, or 50000 times depending on the size of the constituent fibers. At that time, an axis having an arbitrary vertical and horizontal image width is assumed in the obtained image, and the sample and observation conditions (magnification, etc.) are adjusted so that 20 or more fibers intersect the axis. Then, after obtaining an observation image that satisfies this condition, two random axes, vertical and horizontal, per image are drawn on this image, and the fiber diameter of the fiber that intersects the axis is visually read. In this way, images of at least three non-overlapping surface portions are taken with an electron microscope, and the fiber diameter values of the fibers intersecting with each of the two axes are read (thus, at least 20 × 2 × 3 = 120). Information on the fiber diameter of the book is obtained). The maximum fiber diameter and the number average fiber diameter are calculated from the fiber diameter data thus obtained.

(B) Average aspect ratio Although the average aspect-ratio of the said cellulose nanofiber is 50-1000, Preferably it is 100-1000, More preferably, it is 200-1000. If the average aspect ratio is less than 50, the dispersion stability may be lowered.

  The average aspect ratio of the cellulose nanofiber can be measured, for example, by the following method, that is, the cellulose nanofiber is cast on a carbon film-coated grid that has been hydrophilized and then negatively stained with 2% uranyl acetate. From the TEM image (magnification: 10,000 times), the number average fiber diameter and the fiber length of the cellulose nanofiber were observed. That is, the number average fiber diameter and fiber length were calculated according to the methods described above, and the average aspect ratio was calculated according to the following formula (1) using these values.

（C）セルロースI型結晶構造
上記セルロースナノファイバーは、I型結晶構造を有する天然由来のセルロース原料を微細化した繊維である。すなわち、天然セルロースの生合成の過程においては、ほぼ例外なくミクロフィブリルと呼ばれるナノファイバーがまず形成され、これらが多束化して高次な固体構造を構成する。

(C) Cellulose I-type crystal structure The cellulose nanofiber is a fiber obtained by refining a naturally-derived cellulose raw material having an I-type crystal structure. That is, in the process of biosynthesis of natural cellulose, nanofibers called microfibrils are first formed almost without exception, and these form a multi-bundle to form a higher order solid structure.

The cellulose constituting the cellulose nanofiber has an I-type crystal structure, for example, in the diffraction profile obtained by wide-angle X-ray diffraction image measurement, in the vicinity of 2 theta = 14-17 ° and 2 theta = 22-23 °. It can be identified by having typical peaks at two nearby positions.

(D) Anionic functional group The cellulose nanofiber has an anionic functional group.

Although it does not restrict | limit especially as an anionic functional group of this invention, Specifically, a carboxyl group, a phosphonium group, a sulfonium group is mentioned, Among these,
A carboxyl group is preferable because it is easy to introduce an anionic functional group into cellulose.

  As a method of introducing carboxyl into cellulose, a method of reacting at least one selected from the group consisting of a compound having a carboxyl group at the hydroxyl group of cellulose, an acid anhydride of a compound having a carboxyl group and derivatives thereof, a hydroxyl group of cellulose The method of converting into a carboalkyl group by oxidizing is mentioned.

Although it does not specifically limit as a compound which has the said carboxyl group, Specifically, a halogenated acetic acid is mentioned, As a halogenated acetic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid etc. are mentioned.

  The acid anhydride of the compound having a carboxyl group is not particularly limited, but acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride, and the like. Can be mentioned.

  Although it does not specifically limit as a derivative | guide_body of the compound which has the said carboxyl group, The derivative of the acid anhydride of the compound which has a carboxyl group and the acid anhydride imidation of a compound which has a carboxyl group is mentioned. Although it does not specifically limit as an acid anhydride imidation thing of a compound which has a carboxyl group, Imidation thing of dicarboxylic acid compounds, such as maleimide, succinic acid imide, and phthalic acid imide, is mentioned. The acid anhydride derivative of the compound having a carboxyl group is not particularly limited. And those in which part of the hydrogen atoms are substituted with a substituent (eg, an alkyl group, a phenyl group, etc.).

The method for oxidizing the hydroxyl group of the cellulose is not particularly limited, and specifically, a method in which an N-oxyl compound is used as an oxidation catalyst and a cooxidant is allowed to act.
In the present invention, as a method for introducing a carboxyl group into cellulose, a method of oxidizing the hydroxyl group of cellulose is preferable because of excellent hydroxyl group selectivity on the fiber surface and mild reaction conditions. Hereinafter, cellulose having a carboxyl group introduced by oxidation of a hydroxyl group is referred to as oxidized cellulose.

  The oxidized cellulose uses natural cellulose as a raw material, uses an N-oxyl compound as an oxidation catalyst in water, and reacts with a co-oxidant to oxidize the natural cellulose to obtain reactant fibers, removing impurities. Thus, it can be obtained by a production method including a purification step of obtaining a reactant fiber impregnated with water and a dispersion step of dispersing the reactant fiber impregnated with water in a solvent.

  It is preferable that the hydroxyl group at the C6 position of each glucose unit in the cellulose molecule of the cellulose nanofiber of the present invention is selectively oxidized and modified to be either an aldehyde group or a carboxyl group. The carboxyl group content (carboxyl group amount) is preferably in the range of 0.5 mmol / g to 2.5 mmol / g, more preferably 1.5 mmol / g to 2.0 mmol / g in terms of dispersibility in water. Range.

  The measurement of the carboxyl group amount of the oxidized cellulose is, for example, preparing 60 ml of a 0.5 to 1% by weight slurry from a precisely weighed dry sample and adjusting the pH to about 2.5 with a 0.1 M aqueous hydrochloric acid solution. Then, 0.05M sodium hydroxide aqueous solution is dripped and electrical conductivity measurement is performed. The measurement is continued until the pH is about 11. The amount of carboxyl groups can be determined from the amount of sodium hydroxide consumed in the neutralization step of the weak acid with a gentle change in electrical conductivity (V) according to the following formula (2).

なお、カルボキシル基量の調整は、後述するように、天然セルロースの酸化工程で用いる共酸化剤の添加量や反応時間を制御することにより行うことができる。

In addition, adjustment of a carboxyl group amount can be performed by controlling the addition amount and reaction time of the co-oxidant used at the oxidation process of natural cellulose so that it may mention later.

  The oxidized cellulose is preferably reduced with a reducing agent after the oxidative modification. As a result, part or all of the aldehyde group and the ketone group are reduced to return to the hydroxyl group. Note that the carboxyl group is not reduced. And by the said reduction | restoration, it is preferable that the total content of the aldehyde group and the ketone group by the measurement by the semicarbazide method of the said cellulose nanofiber shall be 0.3 mmol / g or less, Most preferably, it is 0-0.1 mmol / g. , Most preferably substantially 0 mmol / g. Thereby, the molecular weight fall of a cellulose nanofiber is suppressed and dispersion stability can be maintained for a long time.

The oxidized cellulose is oxidized using a co-oxidant in the presence of an N-oxyl compound such as 2,2,6,6-tetramethylpiperidine (TEMPO), and an aldehyde group generated by the oxidation reaction. It is preferable that the ketone group is reduced with a reducing agent because the cellulose nanofiber can be easily obtained. Also, reduction with the reducing agent, the is by hydrogenation sodium borohydride (NaBH _4), more preferable from the viewpoint.

  Measurement of the total content of aldehyde groups and ketone groups by the semicarbazide method is performed, for example, as follows. Specifically, 50 ml of a semicarbazide hydrochloride 3 g / l aqueous solution adjusted to pH = 5 with a phosphate buffer is accurately added to the dried sample, sealed, and shaken for 2 days. Next, 10 ml of this solution is accurately collected in a 100 ml beaker, 25 ml of 5N sulfuric acid and 5 ml of 0.05N potassium iodate aqueous solution are added and stirred for 10 minutes. Thereafter, 10 ml of 5% potassium iodide aqueous solution was added, and immediately titrated with a 0.1N sodium thiosulfate solution using an automatic titrator. From the titration amount and the like, according to the following formula (3), The amount of carbonyl groups (total content of aldehyde groups and ketone groups) can be determined. Semicarbazide reacts with an aldehyde group or a ketone group to form a Schiff base (imine), but does not react with a carboxyl group. Therefore, it is considered that only the aldehyde group and the ketone group can be quantified by the above measurement.

上記セルロースナノファイバーは、繊維表面上のセルロース分子中の各グルコースユニットのＣ６位の水酸基が選択的に酸化変性されてアルデヒド基、またはカルボキシル基のいずれかとなっている。このセルロースナノファイバー表面上のグルコースユニットのＣ６位の水酸基が選択的に酸化されているかどうかは、例えば、¹³Ｃ−ＮＭＲチャートにより確認することができる。すなわち、酸化前のセルロースの¹³Ｃ−ＮＭＲチャートで確認できるグルコース単位の１級水酸基のＣ６位に相当する６２ｐｐｍのピークが、酸化反応後は消失し、代わりにカルボキシル基等に由来するピーク（１７８ｐｐｍのピークはカルボキシル基に由来するピーク）が現れる。このようにして、グルコース単位のＣ６位水酸基のみがカルボキシル基等に酸化されていることを確認することができる。

In the cellulose nanofiber, the hydroxyl group at the C6 position of each glucose unit in the cellulose molecule on the fiber surface is selectively oxidized and modified to be either an aldehyde group or a carboxyl group. Whether the hydroxyl group at the C6 position of the glucose unit on the surface of the cellulose nanofiber is selectively oxidized can be confirmed by, for example, a ¹³ C-NMR chart. That is, a 62 ppm peak corresponding to the C6 position of the primary hydroxyl group of the glucose unit, which can be confirmed by a ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead a peak derived from a carboxyl group or the like (178 ppm) The peak of is a peak derived from a carboxyl group). In this way, it can be confirmed that only the C6 hydroxyl group of the glucose unit is oxidized to a carboxyl group or the like.

  Moreover, the detection of the aldehyde group in the said cellulose nanofabric can also be performed with a Faring reagent, for example. That is, for example, after adding a Fering reagent (a mixed solution of sodium potassium tartrate and sodium hydroxide and an aqueous solution of copper sulfate pentahydrate) to a dried sample, the supernatant is obtained when heated at 80 ° C. for 1 hour. When blue and cellulose nanofiber parts are amber, it can be judged that aldehyde groups have not been detected, and when the supernatant is yellow and cellulose fiber parts are red, it can be judged that aldehyde groups have been detected. it can.

(E) Organic compound having an organic value of 450 or less in the organic conceptual diagram The cellulose nanofiber of the present invention has an organic value in the organic conceptual diagram (hereinafter sometimes simply referred to as an organic value) of 450 or less. The compound is bonded to the anionic functional group by an ionic bond.

  Here, the organic conceptual diagram is described in detail in, for example, “Organic conceptual diagram-basics and application” (written by Yoshio Koda, Sankyo Publishing, 1984). In other words, “organic conceptual diagram” means “organic” due to covalent bonds in the carbon region of all organic compounds and “inorganic” due to the influence of electrostatic properties present in substituents (functional groups). The “factor” is converted into a numerical value according to a predetermined rule, and the organic value is plotted on the X axis and the inorganic value is plotted on the Y axis. The above document states that the magnitude of the organic value in the organic conceptual diagram can be measured by the number of carbon atoms represented by the methylene group in the molecule of the organic compound. The organic value of one carbon atom is defined as 20 by taking an average boiling point increase of 20 ° C. by adding one carbon in the vicinity of 5 to 10 carbon atoms of the organic compound. .

  The organic value is 450 or less, preferably 400 or less, and more preferably 360 or less. If the organic value exceeds 450, the hydrophobicity is too high and the cellulose fibers may not be neutralized.

  The organic compound having an organic value of 450 or less in the organic conceptual diagram is preferably one or more selected from nitrogen-containing compounds and organic phosphorus compounds.

  Although it does not restrict | limit especially as said nitrogen-containing compound, Specifically, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium, etc. are mentioned.

  Among these nitrogen-containing compounds, preferably amines such as triethylamine, triethanolamine, dimethylbutylamine, dimethyloctylamine, monooctylamine, dimethylbenzylamine, triisopropanolamine, dimethyloctadecylamine, and tetramethylammonium hydroxide, tetraethyl And ammonium such as ammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, hexadecyltrimethylammonium hydroxide.

  Further, the organic phosphorus compound is not particularly limited, and specific examples thereof include quaternary phosphonium. Among these, tetramethylphosphonium hydroxide, tetraethylphosphonium hydroxide, tetrapropylphosphonium hydroxide, tetrabutyl are preferable. Phosphonium such as phosphonium hydroxide, benzyltrimethylphosphonium hydroxide, benzyltriethylphosphonium hydroxide, hexadecyltrimethylphosphonium hydroxide is preferable.

  Among these, the compound whose organic value is 400 or less includes dimethyloctadecylamine, and the compound whose organic value is 360 or less includes tetrabutylphosphonium hydroxide and tetrabutylammonium hydroxide.

  The viscous aqueous composition of the present invention contains a water-miscible organic solvent.

  The viscous aqueous composition of the present invention is presumed to contain a water-miscible organic solvent so that hydrogen bonding between cellulose nanofibers is inhibited, so that it can be diluted even with slight agitation.

  The water-miscible organic solvent is an organic solvent that dissolves 50 g or more in 1 L of ion-exchanged water at 25 ° C., and is not particularly limited. Specifically, as alcohols, monoalcohols such as methanol, ethanol, propanol, As polyhydric alcohols such as isopropanol, butanol, pentanol, hexanol, dodecanol, cyclohexanol, benzyl alcohol, and acetylene alcohol, ethylene glycol, diethylene glycol, thiodiethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and other ethylene Diols; Propanediol such as 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 3-methoxy-1,2-propanediol Butanediols such as 2-butene-1,4-diol, 1,3-butanediol, 2-methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentane Pentanediols such as diol, 1,4-pentanediol, 3-methyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol; hexanediols such as 1,2-hexanediol; Heptanediols such as 1,2,6-trimethyl-1,7-heptanediol and 2,4,6-triethyl-1,7-heptanediol; octane such as 3,6-dithia-1,8-octanediol Diols; other alkylenes such as propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol Alls: polyols such as glycerin, hexanetriol, thiodiglycol, trimethylolpropane, etc., and glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, Diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, trie Tylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl Examples of amines such as ether include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine, Yo Other polar solvents include, for example, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 3-methylsulfolane, 3-sulfolene, bis (2-hydroxyethyl) sulfone, 2-pyrrolidone N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone-5-carboxylic acid, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone, diacetone alcohol, 4-picoline etc. are mentioned. These may be used alone or in combination of two or more.

  Alcohols are preferable because the water-miscible organic solvent can form hydrogen bonds with the hydroxyl groups of cellulose nanofibers.

  Although it does not restrict | limit especially as said alcohol, Specifically, methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene diols, such as ethylene glycol, diethylene glycol, polyethyleneglycol, as a polyhydric alcohol; 2-methyl-1, Propanediols such as 3-propanediol, 2-ethyl-1,3-propanediol, 3-methoxy-1,2-propanediol; 2-butene-1,4-diol, 1,3-butanediol, 2 -Butanediols such as methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 3-methyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol One or more selected pentane diols and the like. These may be used alone or in combination of two or more.

In the viscous aqueous composition of the present invention, the cellulose nanofiber content is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.1% by mass or more and 5% by mass or less. If the content is less than 0.1% by mass, sufficient thickening and dispersion stability may not be exhibited. If the content exceeds 20% by mass, the thickening is too high and handling may be difficult.
In the viscous aqueous composition of the present invention, the content of the water-miscible organic solvent is preferably 5% by mass to 80% by mass, and more preferably 10% by mass to 60% by mass. If the content is less than 5% by mass, the effect of facilitating dilution may not be obtained sufficiently, and if it exceeds 80% by mass, it may be difficult to make cellulose fibers into nanofibers.

  The ratio of the content of the cellulose nanofibers to the content of the water-miscible organic solvent in the viscous aqueous composition of the present invention (hereinafter sometimes referred to as the content ratio) is cellulose nanofiber / water-miscible organic solvent = 1/1000 to 1/2 is preferable, and 1/100 to 1/4 is more preferable. It is preferable that the content ratio is within the above range in that the effect of facilitating dilution is easily obtained.

  The viscosity of the viscous aqueous composition of the present invention was measured under the conditions that the content of the cellulose nanofiber was 0.2% by mass, the rotational speed of the rotor was 0.3 rpm, and the liquid temperature was 20 ° C. in the BM type viscometer. In this case, it is preferably 100 mPa · s or more, and more preferably 300 mPa · s or more. When the said viscosity is less than 100 mPa * s, there exists a possibility that a viscosity increase and dispersion stability may become inadequate.

  The viscous aqueous composition of the present invention includes (I) an oxidation step for oxidizing cellulose, (II) a purification step for adjusting the pH of the oxidized cellulose dispersion to 2 or less, and (III) a purified cellulose with the above organic concept. It is preferable to include a neutralization step of neutralizing with an organic compound having an organic value of 450 or less in the figure, and (IV) a dispersion step of dispersing the neutralized cellulose in the presence of water and a water-miscible organic solvent, Specifically, it is preferable to manufacture by the following steps.

(I) Oxidation process After dispersing natural cellulose and N-oxyl compound in water (dispersion medium), a cooxidant is added to initiate the reaction. During the reaction, a 0.5 M aqueous sodium hydroxide solution is added dropwise to maintain the pH at 10 to 11, and the reaction is regarded as completed when no change in pH is observed. Here, the co-oxidant is not a substance that directly oxidizes a cellulose hydroxyl group but a substance that oxidizes an N-oxyl compound used as an oxidation catalyst.

  The natural cellulose means purified cellulose isolated from a cellulose biosynthetic system such as a plant, animal, or bacteria-producing gel. More specifically, softwood pulp, hardwood pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as straw pulp and bagasse pulp, bacterial cellulose (BC), cellulose isolated from sea squirt, seaweed Cellulose isolated from can be mentioned. These may be used alone or in combination of two or more. Among these, soft wood pulp, hardwood pulp, cotton pulp such as cotton linter and cotton lint, and non-wood pulp such as straw pulp and bagasse pulp are preferable. The natural cellulose is preferably subjected to a treatment for increasing the surface area such as beating, because the reaction efficiency can be increased and the productivity can be increased. In addition, if the natural cellulose that has been stored after being isolated and purified and not dried (never dry) is used, the microfibril bundles are likely to swell. This is preferable because the number average fiber diameter after the crystallization treatment can be reduced.

  The dispersion medium of natural cellulose in the above reaction is water, and the concentration of natural cellulose in the reaction aqueous solution is arbitrary as long as the reagent (natural cellulose) can be sufficiently diffused. Usually, it is about 5% or less based on the weight of the reaction aqueous solution, but the reaction concentration can be increased by using a device having a strong mechanical stirring force.

  Examples of the N-oxyl compound include compounds having a nitroxy radical generally used as an oxidation catalyst. The N-oxyl compound is preferably a water-soluble compound, more preferably a piperidine nitroxyoxy radical, particularly 2,2,6,6-tetramethylpiperidinooxy radical (TEMPO) or 4-acetamido-TEMPO. preferable. The N-oxyl compound is added in a catalytic amount, preferably 0.1 to 4 mmol / l, more preferably 0.2 to 2 mmol / l.

  Examples of the co-oxidant include hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogen acid or a salt thereof, hydrogen peroxide, a perorganic acid, and the like. These may be used alone or in combination of two or more. Of these, alkali metal hypohalites such as sodium hypochlorite and sodium hypobromite are preferable. And when using the said sodium hypochlorite, it is preferable to advance reaction in presence of alkali metal bromides, such as sodium bromide, from the point of reaction rate. The addition amount of the alkali metal bromide is about 1 to 40 times mol, preferably about 10 to 20 times mol for the N-oxyl compound.

  The pH of the aqueous reaction solution is preferably maintained in the range of about 8-11. The temperature of the aqueous solution is arbitrary at about 4 to 40 ° C., but the reaction can be performed at room temperature (25 ° C.), and the temperature is not particularly required to be controlled. In order to obtain a desired amount of carboxyl group and the like, the degree of oxidation is controlled by the amount of co-oxidant added and the reaction time. Usually, the reaction time is completed within about 5 to 120 minutes, at most 240 minutes.

(II) Purification step Next, purification is performed for the purpose of removing unreacted co-oxidant (such as hypochlorous acid) and various by-products. Specifically, the pH of the reaction mixture is adjusted to about 2 with various acids, and solid-liquid separation is performed with a centrifuge while sprinkling purified water to obtain cake-like oxidized cellulose. Solid-liquid separation is performed until the electric conductivity of the filtrate is 5 mS / m or less.

  As a purification method in the purification step, any apparatus can be used as long as it can achieve the above-described object, such as a method using centrifugal dehydration (for example, a continuous decanter). The aqueous dispersion of oxidized cellulose thus obtained has a solid content (cellulose) concentration in the range of about 10 wt% to 50 wt% in a squeezed state. Considering the subsequent dispersion step, if the solid content concentration is higher than 50% by weight, it is not preferable because extremely high energy is required for dispersion.

(III) Neutralization Step Next, the purified oxidized cellulose is neutralized with an organic compound having an organic value of 450 or less in the organic conceptual diagram. Specifically, the aqueous dispersion of oxidized cellulose is adjusted to a predetermined solid content concentration of water or water and the above water-miscible organic solvent, and an organic compound having an organic value of 450 or less is added. This can be done by stirring. In this case, the pH of the aqueous dispersion is preferably in the range of 5 to 10 (preferably in the range of 6 to 8). If the pH is less than the above range, the reactant fibers are entangled with each other and are not easily loosened, and cannot be dispersed at a high pressure in the subsequent dispersion step. This is because the viscosity decreases. An organic compound having an organic value of 450 or less may be diluted with water or a mixed solvent of water and the above organic solvent and added to the aqueous dispersion of reactant fibers.

The solid content concentration of the oxidized cellulose is not particularly limited as long as the aqueous dispersion of oxidized cellulose can be stirred, but specifically, 0.1 mass% to 20 mass%, preferably 0.2 mass%. The amount is 5% by mass or less. If the solid content concentration of the oxidized cellulose is within the above range, it is preferable because an organic compound having an organic value of 450 or less can be uniformly mixed. The stirring time is not particularly limited as long as the organic compound having an organic value of 450 or less can be uniformly dispersed in the aqueous dispersion of reactant fibers.
(IV) Dispersing Step The aqueous dispersion of oxidized cellulose obtained in the neutralization step is dispersed in water or a mixed solvent of water and the organic solvent to perform a dispersion treatment. With the treatment, the viscosity increases, and a dispersion of cellulose nanofibers that has been refined can be obtained.

  Dispersers used in the above dispersion step include homomixers under high speed rotation, high pressure homogenizers, ultra high pressure homogenizers, ultrasonic dispersion processors, beaters, disc type refiners, conical type refiners, double disc type refiners, grinders, etc. Use of a powerful and beating-capable device is preferable in that more efficient and advanced downsizing is possible, and a viscous aqueous composition can be obtained economically advantageously. Examples of the disperser include a screw mixer, paddle mixer, disper mixer, turbine mixer, disper, propeller mixer, kneader, blender, homogenizer, ultrasonic homogenizer, colloid mill, pebble mill, and bead mill grinder. It can be used. Further, two or more types of dispersers may be used in combination.

  The treatment conditions with the homogenizer of the present invention are not particularly limited, but the pressure conditions are 30 MPa or more, preferably 100 MPa or more, more preferably 140 MPa or more. In addition, prior to defibration / dispersion treatment with a high-pressure homogenizer, it is possible to pre-treat the oxidized cellulose using known mixing, stirring, emulsifying, and dispersing devices such as a high-speed shear mixer as necessary. is there.

(V) Reduction step In the production of the viscous aqueous composition of the present invention, it is preferable to further perform a reduction reaction after the (I) oxidation step. Specifically, the oxidized cellulose after the oxidation reaction is dispersed in purified water, the pH of the aqueous dispersion is adjusted to about 10, and the reduction reaction is performed with various reducing agents. As the reducing agent used in the present invention, a general reducing agent can be used, and preferred examples include LiBH ₄ , NaBH ₃ CN, NaBH _{4 and the} like. Of these, NaBH ₄ is preferable from the viewpoint of cost and availability.

  The amount of the reducing agent is preferably in the range of 0.1 to 4% by mass, particularly preferably in the range of 1 to 3% by mass, based on the oxidized cellulose. The reaction is usually carried out at room temperature or slightly higher than room temperature, usually 10 minutes to 10 hours, preferably 30 minutes to 2 hours.

  In the viscous aqueous composition of the present invention, a functional additive may be used as another component material. Examples of the functional additives include oily raw materials (oils, etc.), inorganic salts, organic salts, surfactants, moisturizers, preservatives, organic fine particles, used in cosmetics, pharmaceuticals, spray products, paints, etc. Inorganic fine particles, deodorants, fragrances, organic solvents and the like can be mentioned. These may be used alone or in combination of two or more. In particular, the present invention is advantageous when blending the oily raw material because the characteristics of the cellulose nanofiber can overcome the problem that the oily raw material is not emulsified and separated.

  Examples of the oily raw material include silicone oils such as methylpolysiloxane and silicone polyether copolymer, vegetable oils and fats, animal fats and oils, waxes, hydrocarbons, higher fatty acids, higher alcohols, esters and the like. These may be used alone or in combination of two or more.

  Among the above oily raw materials, as the vegetable oil, for example, avocado oil, almond oil, olive oil, kukui nut oil, grape seed oil, sesame oil, wheat germ oil, rice germ oil (Oryza oil), rice bran oil (rice oil), Safflower oil, shea butter (soy fat), soybean oil, tea oil (tea seed oil, tea seed oil), evening primrose oil, tepaki oil, corn germ oil, rapeseed oil, persic oil (apricot kernel oil, peach seed oil), pearl barley Oil, palm oil, palm kernel oil, castor oil, hydrogenated castor oil (castor wax), sunflower oil (sunflower oil), zelkova oil, macadamia nut oil, meadowweed oil, cottonseed oil, molasses, palm oil, peanut oil ( Peanut oil) and rosehip oil.

  Examples of animal fats include orange luffy oil, beef tallow, turtle oil (green turtle oil), mink oil, egg yolk oil, powdered egg yolk oil (hydrogenated egg yolk oil), and the like.

  Examples of the waxes include carnauba wax, whale wax, shellac, jojoba oil, beeswax, white beeswax (white wax), montan wax, lanolin, lanolin derivatives, reduced lanolin, hard lanolin, and adsorbed purified lanolin. .

  Examples of the hydrocarbon include α-olefin oligomer, squalane, vegetable squalane, CD squalane, ceresin (ground wax), solid paraffin, pristane, polyethylene powder, microcrystalline wax, liquid paraffin, petrolatum and the like. .

  Examples of the higher fatty acid include arachidonic acid, isostearic acid, undecylenic acid, oleic acid, stearic acid, palmitic acid, behenic acid, myristic acid, lauric acid, lanolin fatty acid, hard lanolin fatty acid, soft lanolin fatty acid, linoleic acid And linolenic acid.

Examples of the higher alcohol include isostearyl alcohol, oleyl alcohol, octyldodecanol, chimyl alcohol (glyceryl monocetyl ether), cholesterol (cholesterin), sitosterol (sitosterin), stearyl alcohol, cetanol (cetyl alcohol, Palmityl alcohol), cetostearyl alcohol, ceralkyl alcohol (monooleyl glyceryl ether), decyltetradecanol, batyl alcohol (glyceryl monostearyl ether), phytosterol (phytosterin), hexyldecanol, behenyl alcohol, lauryl alcohol, lanolin alcohol And hydrogenated lanolin alcohol.
Examples of the esters include acetylated lanolin (lanolin acetate), isocetyl isostearate (hexyldecyl isostearate), cholesteryl isostearate, octyldodecyl erucate (EOD), cetyl octanoate (cetyl 2-ethylhexanoate). ), Cetostearyl octoate (cetostearyl 2-ethylhexanoate, cetostearyl isooctanoate), octyldodecyl oleate, decyl oleate, hexyldecyl dimethyloctanoate, isocetyl stearate (hexyldecyl stearate), cholesteryl stearate, Butyl stearate, long chain α-hydroxy fatty acid cholesteryl (GL cholesteryl), glyceryl trimyristate, cetyl lactate, myristyl lactate, isopropyl palmitate (I P, isopropyl palmitate), cholesterol hydroxystearate, isotridecyl myristate (MITD), isopropyl myristate (1PM, isopropyl myristate), octyldodecyl myristate (MOD), myristyl myristate, hexyl laurate, lanolin fatty acid isopropyl, Examples include lanolin fatty acid cholesteryl and diisostearyl malate.

The inorganic salts are preferably those that can be dissolved / dispersed in water, for example, salts made of alkali metal, alkaline earth metal, transition metal, hydrogen halide, sulfuric acid, carbonic acid, etc., specifically, Examples thereof include NaCl, KCl, CaCl2, MgCl2, (NH4) 2SO4, Na2CO3 and the like. These may be used alone or in combination of two or more.
The organic salts are substantially water-soluble by neutralizing hydroxides such as alkali metals and alkaline earth metals, and organic amines and carboxyl groups, phosphoric acid groups and sulfonic acid groups present in the molecule. A substance that exhibits water dispersibility is preferred.

  As the surfactant, those which can be dissolved / dispersed in water are preferable, for example, sulfonic acid surfactants such as alkylsulfosuccinic acid soda, alkylsulfonic acid soda, alkylsulfuric acid ester salts, polyoxyethylene alkylphosphoric acid esters and the like. Nonionic surfactants such as phosphate ester surfactants, higher alcohol alkylene oxide adducts, alkylarylphenol alkylene oxide adducts, anionic surfactants, cationic surfactants, amphoteric surfactants, high Examples thereof include molecular surfactants. These may be used alone or in combination of two or more.

  Examples of the humectant include hyaluronic acid, glycerin, 1,3-butylene glycol, sorbitol, dipropylene glycol and the like. These may be used alone or in combination of two or more.

  Examples of the organic fine particles include styrene-butadiene latex, acrylic emulsion, urethane emulsion and the like. These may be used alone or in combination of two or more.

  Examples of the inorganic fine particles include titanium oxide, silica compounds, and carbon black. These may be used alone or in combination of two or more.

  Examples of the preservative include methyl paraben and ethyl paraben, and these may be used alone or in combination of two or more.

  Examples of the deodorant / fragrance include D limonene, decyl aldehyde, menthone, pulegone, eugenol, cinnamaldehyde, benzaldehyde, menthol, peppermint oil, lemon oil, orange oil, plants (for example, burdock, wolfberry, tsuga, ginkgo biloba) , Deodorized active ingredients extracted from water, hydrophilic organic solvents, etc. from various organs such as black pine, larch, red pine, giraffe, holly mushroom, lilac, buttercup, hornbill, camellia and forsythia. These may be used alone or in combination of two or more.

  Examples of the organic solvent include water-soluble alcohols (methanol, ethanol, isopropanol, isobutanol, sec-butanol, tert-butanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, glycerin, etc.), ethers (ethylene Glycol dimethyl ether, 1,4-dioxane, tetrahydrofuran and the like), ketones (acetone, methyl ethyl ketone), N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and the like. These may be used alone or in combination of two or more.

  Moreover, the compounding quantity of the said functional additive is used by the compounding quantity required in order for the functional additive to express the target effect.

  As described above, the viscous aqueous composition of the present invention can be obtained by blending cellulose nanofibers, water, a water-miscible organic solvent, and a functional additive as necessary, followed by a mixing treatment. .

  More specifically, as the mixing treatment, for example, various homogenizers such as vacuum homomixer, disper, propeller mixer, kneader, various pulverizers, blender, homogenizer, ultrasonic homogenizer, colloid mill, pebble mill, bead mill pulverizer, Examples thereof include a mixing process using a high-pressure homogenizer, an ultrahigh-pressure homogenizer, or the like.

  The viscosity of the viscous aqueous composition of the present invention thus obtained varies depending on the desired function, but is preferably 0.01 Pa · s or more, particularly preferably 0 from the viewpoints of feeling of use, thickening, dispersion stability and the like. The range is from 1 to 80 Pa · s. Moreover, when mix | blending a functional additive, 0.01 Pa.s or more is preferable, Especially preferably, it is the range of 0.1-20 Pa.s. The viscosity can be measured using, for example, a BH viscometer (No. 4 rotor).

  The viscous water-based composition of the present invention thus obtained includes, for example, various products having a cream, gel, emulsion or liquid dosage form (cosmetics, pharmaceuticals, agricultural chemicals, toiletries, spray products, paints) Etc.) can be suitably used as a thickener. Specifically, lotion, emulsion, cold cream, burnishing cream, massage cream, emollient cream, cleansing cream, essence, pack, foundation, sunscreen cosmetic, suntan cosmetic, moisture cream, hand cream, whitening milk, Cosmetics for skin such as various lotions, shampoos, rinses, hair conditioners, rinse-in shampoos, hair styling agents (hair foam, gel-like hair conditioners, etc.), hair treatment agents (hair creams, treatment lotions, etc.), hair dyes and lotions Hair cosmetics such as types of hair restorers or hair nourishing agents, as well as detergents such as hand cleaners, pre-shave lotions, after-shave lotions, automotive and indoor fragrances, deodorants, dentifrices, ointments Plasters, pesticides, spray products, can be used in applications of the paint or the like.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples. In the examples, “%” means mass basis unless otherwise specified.

[Production of cellulose nanofiber]
[Production Example 1: Preparation of cellulose fiber A1 (for Examples)]
After adding 150 ml of water, 0.25 g of sodium bromide, and 0.025 g of TEMPO to 2 g of softwood pulp, and thoroughly stirring and dispersing, 13 wt% sodium hypochlorite aqueous solution (co-oxidant) was added to the pulp 1. The reaction was started by adding sodium hypochlorite so that the amount of sodium hypochlorite was 10 mmol / g with respect to 0 g. The temperature was kept at 20 ° C. during the reaction. Since the pH decreased with the progress of the reaction, the reaction was continued until no change in pH was observed while dropping a 0.5N aqueous sodium hydroxide solution so that the pH was maintained at 10-11 (reaction time: 120 minutes). ). After completion of the reaction, 0.1N hydrochloric acid was added to adjust the pH to 2 or less, and then filtration and washing were repeated for purification to produce cellulose fiber A1 having an oxidized fiber surface.

[Production Example 2: Preparation of cellulose fiber A2 (for Examples)]
Pure water was added to the cellulose fiber whose surface was oxidized in the same manner as the cellulose fiber A1 to adjust the solid content concentration to 4%. Thereafter, the pH of the slurry was adjusted to 10 with a 24% NaOH aqueous solution. The slurry was reduced to 30 ° C. by adding 0.2 mmol / g of sodium borohydride to the cellulose fiber and reacting for 2 hours. After the reaction, the reaction mixture was neutralized by adding 0.1N hydrochloric acid, and then purified by repeated filtration and washing to obtain cellulose fibers. After adjusting the pH to 2 or less, the filtration and washing were repeated and purified, and cellulose fibers A2 Manufactured.

[Production Example 3: Preparation of cellulose fiber A3 (for Examples)]
Cellulose fiber A3 was produced according to the production of cellulose fiber A2, except that the amount of sodium hypochlorite added was 6 mmol / g.

[Production Example 4: Preparation of cellulose fiber A4 (for Examples)]
Cellulose fiber A4 was produced according to the production of cellulose fiber A2, except that the amount of sodium hypochlorite added was 3 mmol / g.

[Production Example 5: Preparation of cellulose fiber A′1 (for comparative example)]
Cellulose fiber A′1 was produced according to the production of cellulose fiber A1, except that the amount of sodium hypochlorite added was 1 mmol / g.

[Production Example 6: Preparation of cellulose fiber A′2 (for comparative example)]
According to the production of cellulose fiber A1, except that regenerated cellulose is used in place of the raw conifer pulp and the amount of sodium hypochlorite aqueous solution added is 27.0 mmol / g with respect to 1.0 g of regenerated cellulose. Thus, cellulose fiber A′2 was produced.

[Production of aqueous viscous composition]
[Example 1]
Pure water and methanol as a water-miscible organic solvent were added to the cellulose fiber A1 to prepare a final concentration of 2% by weight of cellulose fiber and 20% by weight of methanol. Tetrabutylammonium hydroxide (TBAH, organic value 320) was added thereto to adjust the pH to 7. This was treated once at a pressure of 100 MPa using a high-pressure homogenizer (manufactured by Sanwa Engineering Co., Ltd., H11) to produce a viscous aqueous composition.

[Examples 2 to 4]
A viscous aqueous composition was produced in the same manner as in Example 1 except that cellulose fibers A2, A3, and A4 were used in place of cellulose fiber A1.

[Examples 5 to 8]
The same as Example 2 except that dimethylbenzylamine (DMBzA,), dimethyloctadecylamine (DMODA), tetraethylammonium hydroxide (TEAH), and tetrabutylphosphonium hydroxide (TBPH) were used instead of tetrabutylammonium hydroxide. A viscous aqueous composition was produced by the method described above.

[Examples 9 and 10]
A viscous aqueous composition was produced in the same manner as in Example 2 except that the cellulose fiber concentration was adjusted to 0.3 and 10% by weight.

[Examples 11 to 13]
A viscous aqueous composition was produced in the same manner as in Example 2 except that ethanol (EtOH), isopropanol (IPA), and butylene glycol (BG) were used as the water-miscible organic solvent to be added instead of methanol.

[Examples 14 to 16]
A viscous aqueous composition was produced in the same manner as in Example 2 except that ethanol (EtOH) was used instead of methanol as the water-miscible organic solvent to be added, and the final concentrations were 5, 40, and 75% by weight. did.

[Comparative Examples 1 and 2]
A viscous aqueous composition was produced in the same manner as in Example 1 except that cellulose fibers A′1 and A′2 were used instead of cellulose fiber A1.

[Comparative Example 3]
A viscous aqueous composition was produced in the same manner as in Example 1 except that 10% aqueous sodium hydroxide (NaOH) was used instead of tetrabutylammonium hydroxide.

[Characteristic evaluation of viscous aqueous composition]
About the viscous aqueous composition of Examples 1-16 obtained as mentioned above and Comparative Examples 1-3, each characteristic was evaluated according to the following reference | standard. The results are also shown in Table 1 below.

<Number average width of short side>
The number average width of cellulose was observed using a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-1400). That is, from the TEM image (magnification: 10000 times) negatively stained with 2% uranyl acetate after each cellulose fiber was cast on a hydrophilized carbon film-coated grid, The number average width of was calculated.

<Average aspect ratio>
From the TEM image (magnification: 10000 times) that was negatively stained with 2% uranyl acetate after the cellulose was cast on a hydrophilic membrane-coated carbon film grid, the number average width and the long width of the short width of cellulose The number average width of was observed. That is, according to the method described above, the number average width of the shorter width and the number average width of the longer width are calculated, and the average aspect ratio is calculated according to the following formula (1) using these values. did.

＜結晶構造＞
X線回折装置（リガク社製、ＲＩＮＴ‐Ｕｌｔｉｍａ３）を用いて、各セルロース繊維の回折プロファイルを測定し、２シータ＝１４〜１７°付近と、２シータ＝２２〜２３°付近の２つの位置に典型的なピークが見られる場合は結晶構造（I型結晶構造）が「あり」と評価し、ピークが見られない場合は「なし」と評価した。

<Crystal structure>
Using an X-ray diffractometer (Rigaku Corporation, RINT-Utima3), the diffraction profile of each cellulose fiber was measured, and two positions of 2 theta = 14-17 ° and 2 theta = 22-23 ° were obtained. When a typical peak was observed, the crystal structure (type I crystal structure) was evaluated as “present”, and when no peak was observed, it was evaluated as “none”.

<Measurement of carboxyl group content>
After preparing 60 ml of a cellulose aqueous dispersion in which 0.25 g of cellulose fiber was dispersed in water, the pH was adjusted to about 2.5 with 0.1 M hydrochloric acid aqueous solution, and 0.05 M sodium hydroxide aqueous solution was added dropwise. Electrical conductivity measurements were made. The measurement was continued until the pH was 11. The amount of carboxyl groups was determined from the amount of sodium hydroxide consumed V (ml) in accordance with the following formula (2) in the neutralization step of weak acid where the change in electrical conductivity was gradual.

＜カルボニル基量の測定（セミカルバジド法）＞
粘性水系組成物を１０５℃のオーブンにて絶乾した後、約０．２ｇ精秤し、これに、リン酸緩衝液によりｐＨ＝５に調整したセミカルバジド塩酸塩３ｇ／ｌ水溶液を正確に５０ｍｌ加え、密栓し、二日間振とうした。ついで、この溶液１０ｍｌを正確に１００ｍｌビーカーに採取し、５Ｎ硫酸を２５ｍｌ、０．０５Ｎヨウ素酸カリウム水溶液５ｍｌを加え、１０分間撹拌した。その後、５％ヨウ化カリウム水溶液１０ｍｌを加えて、直ちに自動滴定装置を用いて、０．１Ｎチオ硫酸ナトリウム溶液にて滴定し、その滴定量等から、下記の式（３）に従い、試料中のカルボニル基量（アルデヒド基とケトン基との合計含量）を求めた。

<Measurement of amount of carbonyl group (semicarbazide method)>
After the viscous aqueous composition was completely dried in an oven at 105 ° C., about 0.2 g was accurately weighed, and precisely 50 ml of a semicarbazide hydrochloride 3 g / l aqueous solution adjusted to pH = 5 with a phosphate buffer was added thereto. Sealed and shaken for 2 days. Then, 10 ml of this solution was accurately collected in a 100 ml beaker, 25 ml of 5N sulfuric acid and 5 ml of 0.05N potassium iodate aqueous solution were added, and the mixture was stirred for 10 minutes. Thereafter, 10 ml of 5% potassium iodide aqueous solution was added, and immediately titrated with a 0.1N sodium thiosulfate solution using an automatic titrator. From the titration amount and the like, according to the following formula (3), The amount of carbonyl groups (total content of aldehyde groups and ketone groups) was determined.

＜粘度＞
粘性水系組成物に純水を加えて全量が２００ｇ、セルロース繊維濃度が０．２重量％となるように調製し、ホモミキサー（プライミクス社製ホモミクサーＭＡＲＫII ２．５型）で８，０００ｒｐｍで１０分間撹拌した。これを脱気した後、１００ｍｌのサンプル瓶に移し、室温で２４時間静置した。２４時間後、ＢＭ型粘度計（０．３ｒｐｍ、２０℃、３ｍｉｎ）を用いて粘度を測定した。

<Viscosity>
Pure water was added to the viscous aqueous composition to prepare a total amount of 200 g and a cellulose fiber concentration of 0.2% by weight, and the mixture was homomixed with a homomixer (homixer MARK II model 2.5 manufactured by Primics) at 8,000 rpm for 10 minutes. Stir. This was deaerated and then transferred to a 100 ml sample bottle and allowed to stand at room temperature for 24 hours. After 24 hours, the viscosity was measured using a BM viscometer (0.3 rpm, 20 ° C., 3 min).

<Easy dispersibility>
Pure water was added to the viscous aqueous composition to prepare a total amount of 200 g and a cellulose fiber concentration of 0.2% by weight, and the mixture was homomixed with a homomixer (homixer MARK II model 2.5 manufactured by Primics) at 8,000 rpm for 10 minutes. Stir. This was deaerated and then transferred to a 100 ml sample bottle and allowed to stand at room temperature for 24 hours. After 24 hours, the homomixer dispersion viscosity was measured using a BM viscometer (0.3 rpm, 20 ° C., 3 min).
Further, pure water was added to the viscous aqueous composition to prepare a total amount of 200 g and a cellulose fiber concentration of 0.2 wt%, and the mixture was stirred for 10 minutes at 300 rpm using a propeller type stirring blade. This was deaerated and then transferred to a 100 ml sample bottle and allowed to stand at room temperature for 24 hours. After 24 hours, the propeller dispersion viscosity was measured using a BM viscometer (0.3 rpm, 20 ° C., 3 min). From the respective viscosities, easy dispersibility was determined according to the following formula (4).

＜分散安定性＞
粘性水系組成物に純水、酸化チタン（石原産業製タイペークＣＲ−５０）を加えて全量が２００ｇ、セルロース繊維濃度が０．２重量％、酸化チタン濃度が１０重量％となるように調製し、プロペラ型撹拌羽根を用いて３００ｒｐｍで１０分間撹拌した。これを脱気した後、２５ｍｌ目盛付試験管に２５ｍｌ移し、室温で１週間静置した。１週間後、下記の式（５）に従い、分散安定性を求めた。

<Dispersion stability>
To the viscous water-based composition, pure water and titanium oxide (Ishihara Sangyo's Taipei CR-50) were added to prepare a total amount of 200 g, a cellulose fiber concentration of 0.2% by weight, and a titanium oxide concentration of 10% by weight. The mixture was stirred for 10 minutes at 300 rpm using a propeller-type stirring blade. After deaeration, 25 ml was transferred to a 25 ml graduated test tube and allowed to stand at room temperature for 1 week. One week later, the dispersion stability was determined according to the following formula (5).

＜経時安定性＞
粘性水系組成物を耐熱容器に入れ、５０度の恒温槽で４週間静置した。４週間後、粘性水系組成物を取り出し、純水を加えて全量が２００ｇ、セルロース繊維濃度が０．２重量％となるように調製し、ホモミキサー（プライミクス社製ホモミクサーＭＡＲＫII ２．５型）で８，０００ｒｐｍで１０分間撹拌した。これを脱気した後、１００ｍｌのサンプル瓶に移し、室温で２４時間静置した。２４時間後、ＢＭ型粘度計（０．３ｒｐｍ、２０℃、３ｍｉｎ）を用いて粘度を測定した。
この粘度から、下記の式（６）に従い、経時安定性を求めた。

<Stability over time>
The viscous aqueous composition was placed in a heat-resistant container and allowed to stand in a thermostatic bath at 50 degrees for 4 weeks. After 4 weeks, the viscous aqueous composition was taken out and pure water was added to prepare a total amount of 200 g and a cellulose fiber concentration of 0.2% by weight. Using a homomixer (Homomixer MARKII 2.5 type, manufactured by Primix) Stir at 8,000 rpm for 10 minutes. This was deaerated and then transferred to a 100 ml sample bottle and allowed to stand at room temperature for 24 hours. After 24 hours, the viscosity was measured using a BM viscometer (0.3 rpm, 20 ° C., 3 min).
From this viscosity, the temporal stability was determined according to the following formula (6).

実施例については、いずれも高い易分散性、分散安定性が確認された。加えて、カルボニル基量が０．３ｍｍｏｌ／ｇ以下の実施例２〜１６においては高い経時安定性が確認された。

In all of the examples, high dispersibility and dispersion stability were confirmed. In addition, high stability over time was confirmed in Examples 2 to 16 in which the amount of carbonyl group was 0.3 mmol / g or less.

  Regarding Comparative Example 1, the short fiber width and aspect ratio of the cellulose fiber are outside the scope of the claims, and the fiber is too thick to be sufficiently dispersed by slight dilution, and the viscosity and easy dispersibility are low. It was. Moreover, the dispersion stability effect by a fine fiber was not seen, but the dispersion stability of titanium oxide was low.

  Regarding Comparative Example 2, the fiber width and aspect ratio could not be evaluated because the cellulose had no crystal structure and became water-soluble. The resulting viscous aqueous composition had low viscosity and easy dispersibility, and no titanium oxide dispersion stabilizing effect was observed.

  Regarding Comparative Example 3, the physical properties of the cellulose fiber were within the scope of the claims, but since it was a sodium salt, hydrogen bonding of the fiber could not be inhibited, and easy dispersibility and dispersion stability were low.

  The viscous aqueous composition of the present invention uses a cellulose fiber that is a natural material as a thickener or an emulsion stabilizer, and is also rich in compounding properties with various functional additives. In addition, it can be used widely and suitably as a toiletry base material such as a fragrance.

Claims (9)

A viscous aqueous composition containing cellulose nanofibers that satisfy the following conditions, water, and a water-miscible organic solvent ,
The cellulose nanofiber content is 0.1% by mass or more and 20% by mass or less, and the water-miscible organic solvent content is 5% by mass or more and 80% by mass or less.
A viscous aqueous composition, wherein the ratio of the content of cellulose nanofiber and the content of water-miscible organic solvent is cellulose nanofiber / water-miscible organic solvent = 1/100 to 1/4 in terms of mass ratio .
(A) Number average fiber diameter of 2 nm to 500 nm (B) Average aspect ratio of 50 to 1000 (C) Cellulose I-type crystal structure (D) Anionic functional group (E) Organic in organic conceptual diagram An organic compound having a property value of 450 or less is bonded to an anionic functional group by an ionic bond The viscous aqueous composition according to claim 1, wherein the anionic functional group is a carboxyl group.   3. The organic compound having an organic value of 450 or less in the organic conceptual diagram (E) is one or more selected from a nitrogen-containing compound and an organic phosphorus compound. The viscous aqueous composition as described. 4. The organic compound having an organic value of 450 or less in the organic conceptual diagram (E) is one or more selected from ammonium and phosphonium. 5. 2. The viscous aqueous composition according to 1. The viscous water-based composition according to any one of claims 1 to 4, wherein the water-miscible organic solvent is an alcohol. The water-miscible organic solvent is methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 3- Methoxy-1,2-propanediol, 2-butene-1,4-diol, 1,3-butanediol, 2-methyl-1,4-butanediol, 2-methyl-2,4-pentanediol, 1,5 -One or more selected from pentanediol, 1,4-pentanediol, 3-methyl-1,3-pentanediol, and 2,4-diethyl-1,5-pentanediol The viscous aqueous composition according to any one of claims 1 to 5. The viscosity of the viscous aqueous composition according to any one of claims 1 to 6, wherein the cellulose nanofiber content is 0.2% by mass, and in the BM type viscometer, the rotational speed of the rotor is 0.3 rpm, A viscous aqueous composition having a viscosity of 100 mPa · s or more when measured at a liquid temperature of 20 ° C. (I) an oxidation step for oxidizing cellulose,
(II) a purification step in which the pH of the oxidized cellulose dispersion is adjusted to 2 or less and purified;
(III) A neutralization step of neutralizing the purified cellulose with an organic compound having an organic value of 450 or less in the organic conceptual diagram,
(IV) The method for producing a viscous aqueous composition according to any one of claims 1 to 7 , further comprising a dispersion step of dispersing the neutralized cellulose in the presence of water and a water-miscible organic solvent. . The production method according to claim 9, wherein the dispersion condition in the dispersion step (IV) is a treatment with a high-pressure or ultrahigh-pressure homogenizer, and the treatment pressure is 30 MPa or more.