JP2018002668A - Gel-like sheet composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gel-like sheet which has such an excellent water resistance that it can be used even under the environment of touching water such as a bathroom and it can be used in the water, furthermore which does not dry for a long time, and can be used for a long time while sleeping for example, and a method for producing the gel-like sheet.SOLUTION: The gel-like sheet composition is provided which contains: cellulose nanofiber satisfying the following conditions; polyvalent metal ion; and polyhydric alcohol, and in which an anionic functional group of cellulose nanofiber is crosslinked by polyvalent metal ion. The method for producing the gel-like sheet is also provided. (A) number average fiber diameter is 2 nm or more and 500 nm or less, (B) average aspect ratio is 50 or more and 1000 or less, (C) the cellulose nanofiber has a cellulose I type crystal structure, and (D) has an anionic functional group.SELECTED DRAWING: None

Description

  The present invention relates to a gel-like sheet composition and a method for producing the same.

  There is a gel sheet as a material used in cosmetics, and hydrogels in which active ingredients are dissolved are often used as gel sheets. Also, a polymer material is used to adjust the hydrogel. (Patent Documents 1 to 3).

JP 2011-116726 A Japanese Patent Laid-Open No. 2014-024828 JP 2014-073193 A

  Gel sheets using conventional hydrogels have insufficient water resistance, such as being dissolved in water when absorbed in water or absorbing and swelling water, so they can be used in environments where they come into contact with water or in water. On the other hand, there is a problem that it cannot be used for a long time because it takes a short time to dry due to evaporation of moisture. Then, an object of this invention is to provide the gel-like sheet composition which is excellent in water resistance, and is hard to dry, and its manufacturing method.

The present invention provides the following [1] to [6].
[1] A gel-like sheet comprising cellulose nanofibers, polyvalent metal ions and polyhydric alcohol satisfying the following conditions, wherein the anionic functional groups of the cellulose nanofibers are cross-linked by polyvalent metal ions Composition.
(A) Number average fiber diameter is 2 nm or more and 500 nm or less (B) Average aspect ratio is 50 or more and 1000 or less (C) It has a cellulose I type crystal structure (D) It has an anionic functional group
[2] The gel sheet composition according to [1], wherein the anionic functional group is a carboxyl group.
[3] The gel-like sheet composition according to [1] or [2], wherein the content of the anionic functional group of the cellulose nanofiber is 0.01 mmol / g or more and 2.5 mmol / g or less. .
[4] The polyhydric alcohol is one or two selected from polyethylene glycol, 1,3-butylene glycol, 1,2-pentanediol, isoprene glycol, propylene glycol, dipropylene glycol, glycerin, and diglycerin It is the above, The gel-like sheet composition as described in any one of [1] thru | or [3] characterized by the above-mentioned.
[5] The gel-like sheet composition according to any one of [1] to [4], wherein the content of the cellulose nanofiber is 1% by mass or more and 90% by mass or less.
[6] (I) Step of mixing cellulose nanofibers, water and polyhydric alcohol, (II) Step of drying the mixture to form a gel sheet, (III) An aqueous polyvalent metal salt solution of the gel sheet The gel-like sheet composition according to any one of [1] to [5], comprising a step of immersing in an anionic functional group of cellulose nanofibers and crosslinking the anionic functional group of the cellulose nanofiber with a polyvalent metal ion. Manufacturing method.

  Since the gel-like sheet composition of the present invention is excellent in water resistance, it can provide a cosmetic that can be used in an environment where it is exposed to water such as a bathroom and in water. In addition, since it does not dry for a long time, it can provide a cosmetic that can be used for a long time, for example, while sleeping.

  Next, embodiments of the present invention will be described in detail.

  The gel-like sheet composition of the present invention contains predetermined cellulose nanofibers, polyvalent metal ions, and polyhydric alcohols.

  The cellulose nanofiber of the present invention is a fiber obtained by defibrating a cellulose raw material to nano size.

  The cellulose nanofiber of the present invention has a number average fiber diameter of 2 nm to 500 nm, an average fiber aspect ratio of 50 to 1000, a cellulose I-type crystal structure, and an anionic functional group.

(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 3 nm to 80 nm. It is as follows. If the number average fiber diameter is less than 2 nm, the cellulose is dissolved and cannot be obtained as nanofibers, and a gel-like sheet may not be formed. If the number average fiber diameter exceeds 500 nm, the feeling of use is extremely high. May get worse. The maximum fiber diameter of the cellulose nanofiber is preferably 1000 nm or less, particularly preferably 500 nm or less, from the viewpoint of usability.
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 or more and 1000 or less, Preferably it is 100 or more and 1000 or less, More preferably, it is 200 or more and 1000 or less. When the average aspect ratio is less than 50, there is a problem that the obtained gel-like sheet is low in strength and easily collapses.

  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.

  The cellulose nanofiber can be produced by a known method, specifically as follows. For example, it can be obtained by suspending natural cellulose in water and treating it with a high-pressure homogenizer or a grinder to make it fine.

  Natural cellulose is not particularly limited as long as it is cellulose derived from plants, animals, or microorganisms. Kraft pulp or dissolving pulp derived from conifers or hardwoods, cotton linter, lignocellulose with low cellulose purity, wood flour, plant cellulose, bacterial cellulose Etc.

  In addition, as the cellulose nanofiber, bacterial cellulose produced by bacteria can be used. Examples of the bacterium include the genus Acetobacter, and more specifically, Acetobacter aceti, Acetobacter subsp., Acetobacterxylinum, and the like. It is done. By culturing these bacteria, cellulose is produced from the bacteria. Since the obtained product contains bacteria and cellulose nanofibers (bacterial cellulose) that are produced from the bacteria and are connected to the bacteria, the product is removed from the medium, washed with water, or treated with alkali. By removing the bacteria, water-containing bacterial cellulose that does not contain bacteria can be obtained.

(D) Anionic functional group The cellulose nanofiber preferably has an anionic functional group. Specifically, examples of the cellulose having an anionic functional group include oxidized cellulose, carboxymethyl cellulose, phosphorylated cellulose, polyvalent carboxymethyl cellulose, and long-chain carboxycellulose. Of these, oxidized cellulose is preferred because of excellent hydroxyl group selectivity on the fiber surface and mild reaction conditions.

  Carboxymethyl cellulose is also preferred from the viewpoint of versatility and safety.

  Cellulose nanofibers obtained by fibrillating the oxidized cellulose are obtained by using natural cellulose as a raw material, using an N-oxyl compound as an oxidation catalyst in water, and oxidizing the natural cellulose by acting a co-oxidant. It can be obtained by a production method including an oxidation reaction step to be obtained, a purification step to obtain an oxidized cellulose impregnated with water by removing impurities, and a dispersion step of dispersing the oxidized cellulose impregnated with water in a solvent.

  In the oxidized cellulose, it is preferable that the hydroxyl group at the C6 position of each glucose unit in the cellulose molecule is selectively oxidized and modified to be any one of an aldehyde group, a ketone group, and a carboxyl group. The carboxyl group content (carboxyl group amount) is preferably 0.01 mmol / g or more and 2.5 mmol / g or less, more preferably 1.0 mmol / g or more and 2.0 mmol / g from the viewpoint of the strength and water resistance of the gel sheet obtained. It is a 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、原料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 the amount of carboxyl groups can be performed by controlling the addition amount and reaction time of the co-oxidant used in the raw material cellulose oxidation step, as will be described 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, there exists the outstanding effect that it is excellent in long-term stability.

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 oxidized cellulose 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.

上記酸化セルロースは、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、ケトン基およびカルボキシル基のいずれかとなっている。この酸化セルロース表面上のグルコースユニットのＣ６位の水酸基のみ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 oxidized cellulose, 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 become one of an aldehyde group, a ketone group and a carboxyl group. Whether or not only the hydroxyl group at the C6 position of the glucose unit on the oxidized cellulose surface 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 oxidized cellulose can also be performed using, for example, a Fehring reagent. 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.

  The cellulose nanofibers obtained by defibrating the oxidized cellulose are preferably produced by (1) an oxidation reaction step, (2) a reduction step, (3) a purification step, (4) a dispersion step (a refinement treatment step), Specifically, it is preferable to manufacture by the following steps.

(1) Oxidation reaction step After natural cellulose and an N-oxyl compound are dispersed in water (dispersion medium), a cooxidant is added to start 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 said natural cellulose means the refined cellulose isolated from the biosynthesis system of cellulose, such as a plant, an animal, and a bacteria production 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.

(2) Reduction step It is preferable that the oxidized cellulose further undergoes a reduction reaction after the oxidation reaction. Specifically, fine 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 weight, particularly preferably in the range of 1 to 3% by weight, 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.
By performing the above reduction reaction, 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 above reduction, the total content of aldehyde groups and ketone groups of the oxidized cellulose as measured by the semicarbazide method is preferably 0.3 mmol / g or less, particularly preferably in the range of 0 to 0.1 mmol / g. Most preferably, it is substantially 0 mmol / g. Thereby, it is preferable in that it is superior in long-term storage stability than a product simply oxidized and modified.

  After completion of the above reaction, 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 fine oxidized cellulose. Solid-liquid separation is performed until the electric conductivity of the filtrate is 5 mS / m or less.

(3) Purification step Next, purification is performed for the purpose of removing unreacted co-oxidant (such as hypochlorous acid) and various by-products. Oxidized cellulose is not normally dispersed to the nanofiber unit at this stage, so high purity (99% by weight or more) oxidized cellulose and water can be obtained by repeating normal purification, that is, washing and filtration. A dispersion is used.

  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.

(4) Dispersion process (miniaturization process)
Dispersion treatment is performed by dispersing the oxidized cellulose (water dispersion) impregnated with water obtained in the purification step in a dispersion medium. Although water is used as a dispersion medium, a water-miscible organic solvent that is a component of the sunscreen cosmetic of the present invention may be used in combination. The viscosity increases with the treatment, and a defibrated cellulose nanofiber dispersion can be obtained. Thereafter, the cellulose nanofibers may be dried as necessary. Examples of the method for drying the cellulose nanofiber dispersion include spray drying, freeze drying, and vacuum drying when the dispersion medium is water. When the dispersion medium is a mixed solution of water and an organic solvent, a drying method using a drum dryer, a spray drying method using a spray dryer, or the like is used. The cellulose nanofiber dispersion may be used in the state of dispersion without drying.

  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 a more efficient and advanced downsizing is possible, and a gel-like sheet 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.

  Carboxymethyl cellulose, which is one type of cellulose nanofiber having an anionic functional group, can be produced by the following method using the cellulose raw material. That is, cellulose is used as a raw material, and the solvent is 3 to 20 times lower alcohol, specifically methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, etc. Or a mixture of two or more and water. In addition, the mixing ratio of a lower alcohol is 60-95 mass%. As the mercerizing agent, 0.5 to 20 times moles of alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide is used per glucose residue of cellulose. Cellulose is formed by mixing cellulose, a solvent, and a mercerizing agent. The reaction temperature at this time is 0 to 70 ° C., preferably 10 to 60 ° C., and the reaction time is 15 minutes to 8 hours, preferably 30 minutes to 7 hours. Thereafter, the etherification reaction is carried out by adding 0.05 to 10-fold mol of carboxymethylating agent per glucose residue. The reaction temperature at this time is 30 to 90 ° C., preferably 40 to 80 ° C., and the reaction time is 30 minutes to 10 hours, preferably 1 hour to 4 hours.

  Cellulose nanofibers can be obtained by defibrating the carboxymethylcellulose with a high-pressure homogenizer or the like. A high-pressure homogenizer is a device that pressurizes a fluid with a pump and ejects it from a very delicate gap provided in a flow path. It is possible to emulsify, disperse, defibrate, grind, and make ultrafine particles by using total energy such as collision between particles and shear force due to pressure difference.

  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, carboxymethyl cellulose can be pretreated using a known mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer as necessary. is there.

  In this invention, it is preferable that the carboxymethyl substitution degree per glucose unit of carboxymethylcellulose is 0.02 or more and 0.50 or less. By introducing a carboxymethyl substituent into cellulose, the celluloses are electrically repelled. For this reason, the cellulose which introduce | transduced the carboxymethyl substituent can be fibrillated easily. In addition, when the carboxymethyl substituent per glucose unit is smaller than 0.02, nano-defibration cannot be sufficiently performed, and the feeling of use may be deteriorated such as twisting. On the other hand, if the carboxymethyl substituent per glucose unit is larger than 0.50, it swells or dissolves, so that it cannot be obtained as nanofibers and may cause stickiness.

  The degree of carboxymethyl substitution per glucose unit of the carboxymethyl cellulose can be measured by the following method. In other words, carboxymethylcellulose was prepared in a 0.6% by mass slurry, and 0.1 M hydrochloric acid aqueous solution was added to adjust the pH to 2.4, and then 0.05 N sodium hydroxide aqueous solution was added dropwise until the pH reached 11. The amount of carboxyl groups can be measured from the amount of sodium hydroxide consumed in the neutralization step of the weak acid where the change in electrical conductivity is slow, and can be calculated using the following equation (4).

  The gel-like sheet composition of the present invention contains polyvalent metal ions.

  As the polyvalent metal salt containing a polyvalent metal ion, those generally used in the technical field of the present invention can be used, and although not particularly limited, specifically, for example, magnesium compound, calcium compound, zinc Examples thereof include compounds, cadmium compounds, aluminum compounds, titanium compounds, tin compounds, iron compounds, chromium compounds, manganese compounds, cobalt compounds, nickel compounds and the like. Among these, aluminum compounds, magnesium compounds, and calcium compounds are preferable in view of safety because they are attached to the human body. Specific examples of aluminum compounds include a wide range including aluminum hydroxide, inorganic salts, organic salts or chelate compounds such as aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum acetate, and aluminum stearate. The aluminum compound can be mentioned.

  Examples of calcium compounds include calcium hydroxide, calcium carbonate, calcium sulfate, calcium nitrate, calcium chloride, calcium acetate, calcium oxide, and calcium phosphate.

  Magnesium compounds include magnesium hydroxide, magnesium carbonate, magnesium sulfate, magnesium acetate, magnesium silicate, magnesium chloride, magnesium oxide, magnesium hydroxide alumina, magnesium magnesium metasilicate, synthetic magnesium silicate, magnesium aluminate silicate, Examples thereof include magnesium stearate and synthetic hydrotalcite. Further, a plurality of these polyvalent metal compounds may be contained and used.

  The gel-like sheet composition of the present invention contains a polyhydric alcohol.

  As the above-mentioned hydric alcohol, those generally used in the technical field of the present invention can be used, and although not particularly limited, specifically, ethylene glycol, diethylene glycol, thiodiethylene glycol, triethylene glycol, tetraethylene glycol, Ethylene diols such as polyethylene glycol; propane diols such as 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 3-methoxy-1,2-propanediol; 2-butene- Butanediols such as 1,4-diol, 1,3-butanediol, 2-methyl-1,4-butanediol; 2-methyl-2,4-pentanediol, 1,5-pentanediol, 1,4- Pentanediol, 3-methyl-1,3-pentanediol, 2,4-di Pentanediols such as til-1,5-pentanediol; hexanediols such as 1,2-hexanediol; 1,2,6-trimethyl-1,7-heptanediol, 2,4,6-triethyl-1 , 7-heptanediol and other heptanediols; 3,6-dithia-1,8-octanediol and other octanediols; other propylene glycol, dipropylene glycol, polypropylene glycol and butylene glycol and other alkylene diols; glycerin Polyols such as hexanetriol, thiodiglycol, trimethylolpropane, etc., as glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Lenglycol 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, triethylene 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 ether, and the like. These may be used alone or in combination of two or more. Of these, polyethylene glycol, 1,3-butylene glycol, 1,2-pentanediol, isoprene glycol, propylene glycol, dipropylene glycol, glycerin, and diglycerin were selected from the viewpoints of versatility and moisture retention. 1 type or 2 types or more are preferable.

The gel-like sheet composition of this invention contains the said cellulose nanofiber, a polyvalent metal ion, a polyhydric alcohol, water, and other additions. The content of the cellulose nanofiber is preferably 1% by mass or more and 90% by mass or less, and more preferably 2% by mass or more and 50% by mass or less. When the content of the cellulose nanofiber is in the above range, it is preferable in that a gel-like sheet composition that is strong and excellent in flexibility is obtained. The polyvalent metal ion may be added in an amount sufficient to crosslink all the anionic functional groups of the cellulose nanofiber, and varies depending on the type of compound containing the polyvalent metal ion, but is 0.001% by mass or more. 10 mass% or less is preferable. The content of the polyhydric alcohol is preferably 10% by mass or more and 99% by mass or less, and more preferably 50% by mass or more and 98% by mass or less. When the content of the polyhydric alcohol is in the above range, it is preferable in that a gel-like sheet composition that is strong and excellent in flexibility is obtained. The content of the water is preferably 0.01% by mass or more and 70% by mass or less, and more preferably 40% by mass or less from the viewpoint of the gel-like sustainability and strength.
Moreover, the ratio of the content of the cellulose nanofiber and the polyhydric alcohol is preferably cellulose nanofiber / polyhydric alcohol = 1/99 to 90/10 in terms of mass ratio in terms of strength and flexibility of the gel sheet composition. 2/98 to 50/50 is more preferable.

  In the gel-like sheet composition of the present invention, components used in cosmetics and pharmaceuticals can be blended within a range that does not affect the purpose and effect of the present invention. Examples of components that can be formulated that are particularly advantageous for cosmetics and quasi-drug applications include whitening ingredients, anti-wrinkle ingredients, anti-inflammatory ingredients, blood circulation promoting ingredients, antibacterial ingredients, anti-pruritic ingredients, various vitamins and derivatives thereof, Antioxidant component dyes, fragrances and the like can be mentioned.

  Examples of the whitening component include, but are not limited to, ascorbic acid phosphate magnesium salt, ascorbic acid glucoside and its salts and acylated derivatives, ethyl ascorbic acid, vitamin C derivatives such as ascorbyl palmitate, α-albunane, β- Arbutin, Kojic acid, Placenta extract, Cysteine, Glutathione, Ellagic acid, Lucinol, Tranexamic acid, Baicalein, Adenosine and its sodium phosphate salt, Astaxanthin, Deer anteater, Oil-soluble licorice, Lavender, Lumpuyan, Waremokou, Resveratrol, Ganoderma and their extracts, tinctures or ingredients contained in them.

  Examples of the moisturizing component include lactic acid, urea, sorbitol, amino acid, acetylglucosamine, and the like.

  The anti-wrinkle component is not particularly limited. For example, retinoids such as retinol, retinoic acid, retinol acetate, and retinol palmitate, α-hydroxy acids such as citric acid, fruit acid, glycolic acid, and lactic acid, and α-hydroxy acid cholesterol , Rutin sugar derivatives, N-methylserine, elastin, collagen, sericin, camellia extract, golden extract, and the like.

  Examples of the anti-inflammatory component include, but are not limited to, for example, glycyrrhetic acid, glycyrrhetinic acid 2K, allantoin, epsilon-aminocaproic acid, azulene, shikonin, tranexamic acid and auren, licorice, terminaria, yarrow, sunflower, finflower, aloe Examples include butcher bloom, maronier, peach leaf, loquat leaf and their extracts, tinctures or components contained in them.

  The blood circulation promoting component is not particularly limited, and examples thereof include vitamin E, nicotinic acid, nicotinamide, benzyl nicotinate, nicomol, caffeine, capsaicin, nonanoic acid vanillylamide, gingerol, gingerol, and the like.

  Antibacterial components are not particularly limited. For example, cationic surfactants such as isopropylmethylphenol, triclosan, triclocarban, trichlorohydroxyphenol, halocarban, benzalkonium chloride, and benzethonium chloride, photosensitizers, zinc oxide, and titanium oxide. , Chitin, chitosan, hinokitiol and anise.

  The anti-pruritic component is not particularly limited, and examples thereof include diphenhydramine hydrochloride, chlorpheniramine maleate, crotamiton, glycyrrhizic acids, menthol, camphor, rosemary oil, capsaicin, nonanoic acid vanillylamide, dibucaine and the like.

  Vitamins are not particularly limited. For example, vitamin A oil, liver oil, retinol acetate, retinol palmitate, retinol, dehydroretinol, vitamin A3, retinoic acid, vitamin D, vitamin D2 (ergocalciferol) ), Vitamin D3 (cholecalciferol), vitamin derivatives, vitamin E (tocopherol), dl-α-tocopherol acetate, dl-α-tocopherol, tocopherol butyrate, tocopherol nicotinate, benzyl nicotinate, natural vitamin E, vitamin K , Vitamin U and the like. Further, as water-soluble vitamins, vitamin B1 (thyamine), vitamin B2 (riboflavin butyrate ester), vitamin B6 (fatty acid ester such as pyridoxine dicaprylate and pyridoxine dipalmitate), vitamin B12 (cobalamin), vitamin B13, vitamin B14, Vitamin B15 (pangamic acid), folic acid, carnitine, thioctic acid, pantotenyl alcohol, pantotenyl ethyl ether, pantothenic acid, nicotinic acid, nicotinic acid amide, choline, inositol, vitamin C (ascorbic acid), ascorbyl stearate, pantothenic acid Examples include ascorbyl, ascorbyl dipalmitate, vitamin H (biotin), vitamin P (hesperidin), and aplesia.

  The antioxidant component is not particularly limited, but examples include polyphenols such as anthocyanin, catechin, green tea polyphenol, apple polyphenol, carotenoids such as ascorbic acid, sodium ascorbate, sodium ascorbate sulfate, β-carotene, astaxanthin, and tocopherols. , Tocopherol acetate, natural vitamin E, tocomonoenol, tocotrienol, β-diketones such as curcumin, lignans such as sesamin and sesamolin, phenols such as eugenol, and the like.

  The anti-allergic component is not particularly limited, and examples thereof include glycyrrhetic acid derivatives such as glycyrrhetic acid and glycyrrhizic acid 2K, licorice, chlorella, comfrey, button pi, jujube, sage, perilla, mugwort and extracts thereof. Examples include tincture or components contained therein.

The method for producing a gel-like sheet composition of the present invention comprises (I) a step of mixing cellulose nanofibers, water, and a polyhydric alcohol, (II) a step of drying the mixture to form a gel-like sheet, (III) A step of immersing the gel-like sheet in an aqueous polyvalent metal salt solution to crosslink the anionic functional group of the cellulose nanofiber with the polyvalent metal ion.
The step of mixing (I) cellulose nanofiber, water, and polyhydric alcohol is a predetermined amount after the cellulose having an anionic functional group is defibrated by a high-pressure homogenizer or the like in the cellulose nanofiber production step. The polyhydric alcohol may be added and mixed, and a predetermined amount of polyhydric alcohol is added to the aqueous dispersion of cellulose having an anionic functional group before the defibrating treatment and simultaneously with the defibrating treatment by a high-pressure homogenizer or the like. Mixing may be performed. When mixing is performed after the defibrating treatment, the components are not particularly limited as long as each component can be mixed uniformly, but specifically, it is preferable to mix using a homodisper, a homomixer, or the like.

(II) The step of drying the mixture to form a gel-like sheet is performed by pouring or applying the mixture into a container so that the cellulose nanofibers are 2 g / m ² or more and 100 g / m ² or less. Drying is performed at 130 ° C. or lower. When the cellulose nanofibers in the gel sheet are 2 g / m ² or more and 100 g / m ² or less, it is preferable in that a flexible and strong gel-like sheet can be obtained.

  (III) The step of immersing the gel-like sheet in a polyvalent metal salt aqueous solution and cross-linking the anionic functional group of cellulose nanofibers with the polyvalent metal ion is performed by adding the polyvalent metal salt aqueous solution having a predetermined concentration to the above. By immersing the gel sheet obtained in the step (II) at a predetermined temperature and time, the anionic functional group of the cellulose nanofiber can be crosslinked with polyvalent metal ions.

  The concentration of the polyvalent metal aqueous solution is preferably 0.01% by mass or more and 10% by mass or less because the crosslinking rate is appropriate. The temperature of the aqueous polyvalent metal salt solution is preferably 10 ° C. or higher and 70 ° C. or lower because the process can be easily managed. Further, the immersion time is preferably 0.5 hours or more and 12 hours or less because it is appropriate as the time required for crosslinking. The gel sheet composition of the present invention can be obtained by washing excess polyvalent metal salt from the gel sheet composition obtained in this step.

  In addition, when mix | blending the component used for cosmetics and a pharmaceutical, you may add at any said process.

  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 nanofiber A1 (for Examples)]
100 g of softwood pulp was placed in a mixed solution of 435 g of isopropanol (IPA), 65 g of water and 9.9 g of NaOH, and stirred at 30 ° C. for 1 hour. To this slurry system, 23.0 g of 50% monochloroacetic acid IPA solution was added, heated to 70 ° C. and reacted for 1.5 hours. The obtained reaction product was washed with 80% methanol, then substituted with methanol and dried to produce carboxymethylated cellulose fibers. Next, pure water was added to the cellulose fiber to dilute it to 2%, and the fiber was treated once at a pressure of 100 MPa using a high-pressure homogenizer (manufactured by Sanwa Engineering, H11) to produce cellulose fiber A1.

[Production Example 2: Preparation of cellulose nanofiber A2 (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% by mass 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 6 mmol / g with respect to 0 g. 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 for neutralization, followed by purification by repeated filtration and washing to obtain cellulose fibers having oxidized fiber surfaces. Next, pure water was added to the cellulose fiber to dilute it to 2%, and the fiber was treated once with a high-pressure homogenizer (manufactured by Sanwa Engineering, H11) at a pressure of 100 MPa to produce cellulose fiber A2.

[Production Example 3: Preparation of cellulose nanofiber A3 (for Examples)]
Pure water was added to the cellulose fiber whose surface was oxidized in the same manner as the cellulose fiber A2 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, 0.1N hydrochloric acid was added for neutralization, followed by purification by repeated filtration and washing to obtain cellulose fibers, the pH was adjusted to 2 or less, and then filtration and washing were repeated for purification. Next, pure water was added to the cellulose fiber to dilute it to 2%, and the fiber was treated once with a high pressure homogenizer (manufactured by Sanwa Engineering Co., H11) at a pressure of 100 MPa to produce cellulose fiber A3.

[Production Example 4: Preparation of cellulose nanofiber A4 (for comparative example)]
50 g of softwood bleached kraft pulp (NBKP) was dispersed in 4950 g of water to prepare a dispersion having a pulp concentration of 1% by mass. This dispersion was treated 10 times with Serendipeater MKCA6-3 (manufactured by Masuko Sangyo Co., Ltd.) to obtain cellulose nanofiber A4.

[Production Example 5: Preparation of cellulose nanofiber A5 (for comparative example)]
According to the production of cellulose fiber A2, except that regenerated cellulose is used instead of the raw conifer pulp, and the addition amount of the sodium hypochlorite aqueous solution is 12.0 mmol / g with respect to 1.0 g of regenerated cellulose. Thus, cellulose nanofiber A5 was produced.
About each cellulose nanofiber obtained as mentioned above, each characteristic was evaluated according to the following reference | standard. The results are also shown in Table 1 below.

<Crystal structure>
The diffraction profile of each cellulose nanofiber was measured using an X-ray diffractometer (Rigaku Corporation, RINT-Utima3), and two positions of 2 theta = 14-17 ° and 2 theta = 22-23 °. 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”.

<Number average width of short side>
The number average width of the cellulose nanofibers 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.

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

＜カルボキシル基量の測定＞
酸化セルロース０．２５ｇを水に分散させたセルロース水分散体６０ｍｌを調製し、０．１Ｍの塩酸水溶液によってｐＨを約２．５とした後、０．０５Ｍの水酸化ナトリウム水溶液を滴下して、電気伝導度測定を行った。測定はｐＨが１１になるまで続けた。電気伝導度の変化が緩やかな弱酸の中和段階において、消費された水酸化ナトリウム量Ｖ(ml)から、下記の式（２）に従いカルボキシル基量を求めた。

<Measurement of carboxyl group content>
After preparing 60 ml of a cellulose aqueous dispersion in which 0.25 g of oxidized cellulose was dispersed in water, the pH was adjusted to about 2.5 with a 0.1 M aqueous hydrochloric acid solution, and then a 0.05 M aqueous sodium hydroxide 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）＞
酸化セルロースを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 drying the oxidized cellulose in an oven at 105 ° C., weigh accurately about 0.2 g, and add exactly 50 ml of a semicarbazide hydrochloride 3 g / l aqueous solution adjusted to pH = 5 with a phosphate buffer solution. And shaken for two 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.

＜グルコース単位当たりのカルボキシメチル置換度＞
カルボキシメチルセルロースを０．６質量％スラリーに調製し、０．１Ｍ塩酸水溶液を加えてｐＨ２．４とした後、０．０５Ｎの水酸化ナトリウム水溶液を滴下してｐＨが１１になるまで電気伝導度を測定し、電気伝導度の変化が緩やかな弱酸の中和段階において消費された水酸化ナトリウム量からカルボキシル基量を測定し、下記の式（４）に従いグルコース単位当たりのカルボキシメチル置換度を求めた。

<Degree of carboxymethyl substitution per glucose unit>
Prepare a 0.6 mass% slurry of carboxymethylcellulose and add 0.1M aqueous hydrochloric acid to pH 2.4, then add 0.05N aqueous sodium hydroxide solution dropwise until the pH reaches 11. The amount of carboxyl groups was measured from the amount of sodium hydroxide consumed in the neutralization step of a weak acid with a slow change in electrical conductivity, and the degree of carboxymethyl substitution per glucose unit was determined according to the following equation (4). .

上記表１の結果から、実施例用のセルロースＡ１およびＡ２は、いずれも短幅の方の数平均幅が２〜５００ｎｍの範囲内で、アスペクト比が５０以上であり、セルロースI型結晶構造を有していた。

From the results of Table 1 above, the cellulose A1 and A2 for Examples all have a short average number average width of 2 to 500 nm, an aspect ratio of 50 or more, and a cellulose I-type crystal structure. Had.

[Adjustment of gel-like sheet composition]
[Example 1]
Pure water and 1,3-butylene glycol (BG) are added to the cellulose nanofiber A1 to prepare a final concentration of 0.2% by mass of cellulose fiber and 2% by mass of BG. The mixture was stirred at 8,000 rpm for 10 minutes using a homomixer MARK II 2.5 type manufactured by PRIMIX Corporation. This was transferred to a plastic petri dish so that the amount of cellulose was 15 g / m ^2, and dried by evaporating water in a high-temperature bath at 50 ° C. for 36 hours. The gel sheet obtained by drying was immersed in a 1M calcium chloride aqueous solution (polyvalent metal salt) and allowed to stand for 30 minutes to crosslink the cellulose fibers. This was washed with running water to obtain a gel-like sheet composition.

[Examples 2 and 3]
A gel-like sheet composition was prepared in the same manner as in Example 1 except that cellulose nanofibers A2 and A3 were used instead of cellulose nanofiber A1.

[Examples 4 to 6]
A gel-like sheet composition was prepared in the same manner as in Example 3 except that the amount of BG added was 0.3, 5, and 10% by mass.

[Examples 7 and 8]
A gel sheet composition was prepared in the same manner as in Example 3 except that glycerin and propylene glycol (PG) were used instead of BG.

[Examples 9 and 10]
A gel-like sheet composition was prepared in the same manner as in Example 3, except that magnesium chloride and potassium alum were used instead of the calcium chloride as the crosslinking agent.

[Comparative Examples 1 and 2]
A gel-like sheet composition was prepared in the same manner as in Example 2 except that cellulose nanofibers A4 and A5 were used instead of cellulose nanofiber A2.

[Comparative Example 3]
A gel-like sheet composition was prepared in the same manner as in Example 2 except that BG was not blended.

[Comparative Example 4]
A gel-like sheet composition was prepared in the same manner as in Example 2 except that immersion (crosslinking) in an aqueous calcium chloride solution was not performed.

[Comparative Examples 5 and 6]
A gel sheet composition was prepared in the same manner as in Example 2 except that carbomer (Carbopol 940 polymer, manufactured by Lubrizol Advanced Materials) and xanthan gum (KELTROL CG, manufactured by CP Kelco) were used instead of cellulose nanofiber A2. I did it.

  The following physical property evaluation was performed using the gel-like sheet composition obtained above, and the results are shown in Table 2 below.

[Evaluation of gel sheet composition]
<Cellulose fiber content>
The cellulose fiber content [% by mass] in the gel-like sheet composition was calculated from the weight of the cellulose fibers poured into the plastic petri dish and the weight of the gel-like sheet composition finally obtained.

<Water resistance>
The obtained gel-like sheet composition was immersed in pure water and allowed to stand at 25 ° C. for 24 hours, and the amount of change in weight [%] was measured according to the following formula (5).

＜高温安定性＞
得られたゲル状シート組成物を９０℃の高温槽に２時間静置し、下式(6)のとおり重量変化量［％］を測定した。

<High temperature stability>
The obtained gel-like sheet composition was allowed to stand in a high-temperature bath at 90 ° C. for 2 hours, and the amount of weight change [%] was measured as shown in the following formula (6).

実施例に記載のゲル状シート組成物は、いずれも耐水性が高く、純水に浸漬した後もほとんど重量が変化しなかった。さらに、高温安定性も高く、９０℃での乾燥後もほとんど重量が変化しなかった。

All of the gel-like sheet compositions described in the Examples had high water resistance, and the weight hardly changed even after being immersed in pure water. Furthermore, the stability at high temperature was high, and the weight hardly changed after drying at 90 ° C.

On the other hand, since the gel-like sheet composition of Comparative Example 1 has thick cellulose fibers and does not have an anionic group, it cannot form a dense network structure, and has the ability to retain polyhydric alcohol in the gel-like sheet composition. As a result, both water resistance and high temperature stability were low.
Since the gel-like sheet composition of Comparative Example 2 did not have a crystal structure, the performance of holding polyhydric alcohol was low, and a gel-like sheet could not be prepared.

  Moreover, since the gel-like sheet composition described in Comparative Example 3 did not contain a polyhydric alcohol and consisted only of water and cellulose fibers, the high-temperature stability was low. Since the gel-like sheet composition described in Comparative Example 4 did not use a crosslinking agent, the performance of holding polyhydric alcohol was low, and both water resistance and high-temperature stability were low. In particular, in the water resistance test, the gel sheet swelled during the test, and subsequent measurements could not be performed.

  Furthermore, since Comparative Examples 5 and 6 did not contain cellulose fibers and only contained a thickener that is used for general purposes, a gel-like sheet composition could not be formed.

The gel-like sheet composition of the present invention can be used for cosmetics, skin external medicines or external goods, and is particularly preferably used for cosmetics.

Claims (6)

A gel-like sheet composition comprising cellulose nanofibers, polyvalent metal ions, and polyhydric alcohols that satisfy the following conditions, wherein the anionic functional groups of the cellulose nanofibers are crosslinked with polyvalent metal ions.
(A) Number average fiber diameter is 2 nm or more and 500 nm or less (B) Average aspect ratio is 50 or more and 1000 or less (C) It has a cellulose I type crystal structure (D) It has an anionic functional group The gel-like sheet composition according to claim 1, wherein the anionic functional group is a carboxyl group.   The gel-like sheet composition according to claim 1 or 2, wherein the content of the anionic functional group of the cellulose nanofiber is 0.01 mmol / g or more and 2.5 mmol / g or less.   The polyhydric alcohol is one or more selected from polyethylene glycol, 1,3-butylene glycol, 1,2-pentanediol, isoprene glycol, propylene glycol, dipropylene glycol, glycerin, and diglycerin. The gel-like sheet composition according to any one of claims 1 to 3, wherein the gel-like sheet composition is provided.   The gel-like sheet composition according to any one of claims 1 to 4, wherein the content of the cellulose nanofiber is 1% by mass or more and 90% by mass or less. (I) a step of mixing cellulose nanofibers, water, and a polyhydric alcohol,
(II) a step of drying the mixture to form a gel sheet;
(III) A step of immersing the gel-like sheet in an aqueous polyvalent metal salt solution to crosslink anionic functional groups of cellulose nanofibers with polyvalent metal ions,
The method for producing a gel-like sheet composition according to any one of claims 1 to 5, comprising: