JP6944677B2 - Composition - Google Patents

Description

The present invention relates to compositions. More specifically, the present invention relates to a composition that can be used as a material for a separator of an electric double layer capacitor or the like.

In the pulp and paper industry, cellulose, which is a major component of wood, is extracted as pulp. On the other hand, lignin, which is another main component, is used for incineration energy and the like. In recent years, for the purpose of promoting the effective utilization of woody biomass, attempts to add high added value by using lignin as another material have been studied (see, for example, Patent Documents 1 and 2).

The present inventors are searching for usefulness by using lignin as another material and adding high added value. Among them, the possibility of using it as a film material that can be used as a separator for an electric double layer capacitor is reported (see, for example, Non-Patent Document 1).

International Publication No. 2011/111664 Japanese Unexamined Patent Publication No. 2011-184230

Yasumitsu Uraki, 4 outsiders, "Development of Separator for Electric Double Layer Capacitors Derived from PEG Lignin", Japan Wood Society, Hokkaido Chapter Lectures, No. 47, November 2015

The film disclosed in Non-Patent Document 1 is highly flexible, has improved resistance and specific capacitance, and has been found to be usable as a separator. However, the breaking strength is not sufficient, and there is a problem in terms of practical use.

An object of the present invention is to provide a separator for an electric double layer capacitor and a composition capable of forming a film having appropriate strength that can be used for other uses as a novel use of lignin.

As a result of diligent studies on the above-mentioned problems, the present inventors have made the above-mentioned composition containing PEG lignin, acid anhydride, polyethylene glycol or poly (ethylene glycol) diglycidyl ether, and modified cellulose nanofibers. We have found that the above problems can be solved, and have completed the present invention.
That is, the present inventors provide the following [1] to [10].
[1] Component (A): (a1) Lignin source and (a2) PEG lignin, which is a reaction product of polyethylene glycol or poly (ethylene glycol) diglycidyl ether, which is liquid at 25 ° C., and component (B): acid anhydride. A composition containing a substance, a component (C): polyethylene glycol or poly (ethylene glycol) diglycidyl ether, and a component (D): modified cellulose nanofibers.
[2] The above (a1) is at least one selected from the group consisting of kraft lignin, lignin sulfonic acid, lignin acetate, organosolvrignin, blasted lignin, lignin sulfate, alkaline lignin and wood chips [1]. The composition according to.
[3] The composition according to the above [1] or [2], wherein (a2) is polyethylene glycol or poly (ethylene glycol) diglycidyl ether having an average molecular weight of 400 to 600.
[4] The component (B) is selected from the group consisting of maleic anhydride, succinic anhydride, phthalic anhydride, acetic anhydride, citraconic anhydride, itaconic anhydride, aconitic anhydride, hymic anhydride and benzoic anhydride. The composition according to any one of the above [1] to [3], which is at least one of the above.
[5] The composition according to any one of the above [1] to [4], wherein the component (C) is polyethylene glycol or poly (ethylene glycol) diglycidyl ether having an average molecular weight of 4 to 1,000,000.
[6] Any of the above [1] to [5], wherein the component (D) is at least one selected from the group consisting of carboxylated cellulose nanofibers, etherified cellulose nanofibers, and cationized cellulose nanofibers. The composition described in Crab.
[7] The ratio of each component ((A) component: (B) component: (C) component: (D) component) is 20% by mass to 60% by mass: 10% by mass to 40% by mass: 40% by mass or less. : The composition according to any one of the above [1] to [6], which is 0.5% by mass to 10% by mass (however, the total of the components (A) to (D) is 100% by mass).
[8] A film obtained by heat-treating the composition according to any one of the above [1] to [7].
[9] A separator made of the film according to the above [8].
[10] An electric double layer capacitor comprising a pair of polar electrode bodies, an electrolytic solution, and the separator according to the above [9].

According to the present invention, as a novel use of lignin, it is possible to provide a separator for an electric double layer capacitor and a composition capable of forming a film having strength that can be used for other uses.

FIG. 1 is a graph showing the tensile test results of Examples 1 to 3 and Comparative Example 1.

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.
In the present specification, when the range is described as "AA to BB", it means the range of AA or more and BB or less.

[1. Composition]
The composition of the present invention comprises (a1) a lignin source and (a2) PEG lignin, which is a reaction product of polyethylene glycol or poly (ethylene glycol) diglycidyl ether, which is liquid at 25 ° C., acid anhydride, polyethylene glycol or It contains poly (ethylene glycol) diglycidyl ether and modified cellulose nanofibers.
Since the component (A) contains a reaction product of (a1) a lignin source and (a2) a liquid polyethylene glycol or poly (ethylene glycol) diglycidyl ether at 25 ° C., it can be used as a novel use for lignin. Since it contains the component (B), it can react with other components by heat treatment to form the basic shape of the film. Since it contains the component (C), it can impart flexibility when the film is formed. Since it contains the component (D), it can impart appropriate strength to the film.

[1-1. (A) component]
The component (A) is PEG lignin, which is a reaction product of (a1) a lignin source and (a2) a liquid polyethylene glycol or poly (ethylene glycol) diglycidyl ether at 25 ° C.

Examples of the lignin source include kraft lignin purified from kraft pulp effluent, lignin sulfonic acid obtained from sulfite pulp effluent, lignin acetate, organosolv lignin, blasted lignin, lignin sulfate, alkaline lignin and other lignins; Examples include coniferous wood chips, broad-leaved wood chips such as beech and nara, and herbaceous wood chips such as rice straw, fir and bagus.

The molecular weight of the lignin source is preferably 1,000 to 50,000, more preferably 2,000 to 20,000.
The molecular weight of the lignin source can be calculated as a polystyrene-equivalent value by, for example, size exclusion chromatography (SEC).

The polyethylene glycol or poly (ethylene glycol) diglycidyl ether may be liquid at 25 ° C. By using polyethylene glycol or poly (ethylene glycol) diglycidyl ether which is liquid at 25 ° C., the reactivity with the component (a1) is improved, and PEG lignin can be easily prepared.

The molecular weight of polyethylene glycol or poly (ethylene glycol) diglycidyl ether is preferably 400 to 600. When the molecular weight is in this range, polyethylene glycol or poly (ethylene glycol) diglycidyl ether can be liquid at 25 ° C. In addition, by introducing a hydroxyl group at a position away from the main skeleton of lignin, PEG lignin having less steric hindrance and showing good reactivity with other components can be prepared.
When commercially available products of polyethylene glycol or poly (ethylene glycol) diglycidyl ether are used, their average molecular weights are the values indicated on the product.

The method for reacting the lignin source with polyethylene glycol or poly (ethylene glycol) diglycidyl ether is not particularly limited, and a known method can be used.

As an example, when a lignin source is reacted with polyethylene glycol, PEG lignin can be prepared by adding an acid catalyst and reacting.
Examples of the acid catalyst include hydrochloric acid, sulfuric acid and the like. The amount of the acid catalyst added is usually 0.1 to 5.0% by mass with respect to polyethylene glycol.
Neither the reaction temperature nor the reaction time is particularly limited. For example, the reaction is carried out at a reaction temperature of 100 to 150 ° C. for about 30 to 240 minutes.
After completion of the reaction between the lignin source and polyethylene glycol, water can be added to the reaction system to recover PEG lignin as a water-insoluble precipitate.

As another example, when the lignin source is reacted with poly (ethylene glycol) diglycidyl ether, PEG lignin can be prepared by reacting under an alkaline aqueous solution.
When preparing an alkaline aqueous solution, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide and the like can be used.
Neither the reaction temperature nor the reaction time is particularly limited. For example, the reaction is carried out at a reaction temperature of 50 to 90 ° C. for about 30 to 180 minutes.
After the reaction between the lignin source and the poly (ethylene glycol) diglycidyl ether is completed, an acid is added to the reaction system to neutralize the reaction system. The acid to be added may be any acid as long as it does not adversely affect it, and for example, an inorganic acid such as hydrochloric acid, phosphoric acid or sulfuric acid; or an organic acid such as formic acid or acetic acid can be used.

The PEG lignin obtained by the reaction can be used as it is or may be subjected to ultrafiltration. Further, the PEG lignin obtained by the reaction may be completely dried by a conventionally used drying method such as a freeze dryer.

The amount of polyethylene glycol or poly (ethylene glycol) diglycidyl ether to react with the lignin source can be adjusted appropriately according to the type and molecular weight of the lignin source used. As an example, the amount of polyethylene glycol or poly (ethylene glycol) diglycidyl ether is preferably 100 to 1000 parts by mass, more preferably 100 to 600 parts by mass, still more preferably 100 parts by mass with respect to 100 parts by mass of the lignin source. It is 300 to 500 parts by mass.

[1-2. (B) component]
The component (B) is an acid anhydride. By containing the component (B), it can react with other components such as PEG lignin to form the basic shape of the film.

The component (B) is not particularly limited as long as it is an acid anhydride. For example, maleic anhydride, succinic anhydride, phthalic anhydride, acetic anhydride, citraconic anhydride, itaconic anhydride, aconitic anhydride, hymic acid anhydride, benzoic anhydride and the like can be mentioned. Of these, maleic anhydride is preferred.
As the component (B), one kind of acid anhydride may be used alone, or two or more kinds of acid anhydrides may be used in combination.

[1-3. (C) component]
The component (C) is polyethylene glycol or poly (ethylene glycol) diglycidyl ether. By containing the component (C), flexibility can be imparted to the film. In particular, when the film is used as a separator for an electric double layer capacitor, the resistance value and the specific capacitance can be improved.

The molecular weight of polyethylene glycol or poly (ethylene glycol) diglycidyl ether is preferably 4 to 1,000,000, more preferably 20,000 to 800,000, and even more preferably 200,000 to 600,000. When the numerical range of polyethylene glycol or poly (ethylene glycol) diglycidyl ether is in this range, flexibility can be imparted to the film.
When commercially available products of polyethylene glycol or poly (ethylene glycol) diglycidyl ether are used, their average molecular weights are the values indicated on the product.

[1-4. (D) component]
The component (D) is a modified cellulose nanofiber. By containing the component (D), an appropriate strength can be imparted when a film is formed.

Modified cellulose nanofibers are fine fibers obtained from a cellulose raw material through modification and defibration. The average fiber diameter of cellulose nanofibers is usually about 3 to 500 nm. The average fiber diameter and average fiber length can be obtained by averaging the fiber diameter and fiber length obtained from the results of observing each fiber using an atomic force microscope (AFM) or a transmission electron microscope (TEM). can.

The average aspect ratio of modified cellulose nanofibers is usually 50 or more. The upper limit is not particularly limited, but is usually 1000 or less. The average aspect ratio can be calculated by the following formula:
Aspect ratio = average fiber length / average fiber diameter

The origin of the cellulose raw material, which is the raw material of the modified cellulose nanofibers, is not particularly limited. For example, plants (eg, wood, bamboo, hemp, jute, kenaf, farm waste, cloth, pulp (conifer unbleached kraft pulp (NUKP), conifer bleached kraft pulp (NBKP), broadleaf unbleached kraft pulp (LUKP), Hardwood bleached kraft pulp (LBKP), conifer unbleached sulphite pulp (NUSP), conifer bleached sulphite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, used paper, etc.), animals (eg, squirrels), algae , Microorganisms (for example, acetic acid bacteria (acetactor)), microbial products and the like.
As the cellulose raw material, these may be used alone or in combination of two or more. Among them, a plant-derived or microbial-derived cellulose raw material is preferable, and a plant-derived cellulose raw material (for example, cellulose fiber) is more preferable.

The number average fiber diameter of the cellulose raw material is not particularly limited, but is about 30 to 60 μm in the case of softwood kraft pulp, which is a general pulp, and about 10 to 30 μm in the case of hardwood kraft pulp. In the case of other pulp, the one that has undergone general purification is about 50 μm. For example, when a chip or the like having a size of several cm is purified, it is preferable to perform mechanical treatment with a dissociator such as a refiner or a beater to adjust the size to about 50 μm.

[Degeneration]
Modified cellulose nanofibers can exhibit sufficient reinforcing properties. The reason is that the modification of the cellulose raw material sufficiently advances the fineness of the fiber, and a uniform fiber length and fiber diameter can be obtained. In addition, it is possible to secure a sufficient number of fibers having a fiber length and a fiber diameter effective for exhibiting reinforcing properties.

The modification method for modifying the cellulose raw material is not particularly limited, and examples thereof include chemical modification such as oxidation, etherification, phosphorylation, esterification, silane coupling, fluorination, and cationization. Of these, oxidation, carboxymethylation, and cationization using an N-oxyl compound are preferable.

[Oxidation]
When the cellulose raw material is modified by oxidation, the amount of carboxyl groups based on the absolute dry mass of the obtained cellulose oxide or cellulose nanofibers is preferably 0.5 mmol / g or more, more preferably 0.8 mmol / g or more, still more preferably 1. It is 0.0 mmol / g or more. The upper limit is preferably 3.0 mmol / g or less, more preferably 2.5 mmol / g or less, still more preferably 2.0 mmol / g or less. Therefore, 0.5 to 3.0 mmol / g is preferable, 0.8 to 2.5 mmol / g is more preferable, and 1.0 to 2.0 mmol / g is further preferable.

The method of oxidation is not particularly limited, but as an example, a cellulose raw material is used in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromide, iodide or a mixture thereof. Examples include a method of oxidizing. According to this method, the primary hydroxyl group at the C6 position of the glucopyranose ring on the surface of cellulose is selectively oxidized to generate at least one group selected from the group consisting of an aldehyde group, a carboxyl group, and a carboxylate group. The concentration of the cellulose raw material at the time of the reaction is not particularly limited, but is preferably 5% by mass or less.

The N-oxyl compound is a compound capable of generating a nitroxy radical. Examples of the nitroxyl radical include 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). As the N-oxyl compound, any compound can be used as long as it is a compound that promotes the desired oxidation reaction.

The amount of the N-oxyl compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing the cellulose raw material. For example, 0.01 mmol or more is preferable, and 0.02 mmol or more is more preferable with respect to 1 g of an absolute dry cellulose raw material. The upper limit is preferably 10 mmol or less, more preferably 1 mmol or less, and even more preferably 0.5 mmol or less. Therefore, the amount of the N-oxyl compound used is preferably 0.01 to 10 mmol, more preferably 0.01 to 1 mmol, still more preferably 0.02 to 0.5 mmol, based on 1 g of the dry cellulose raw material.

The bromide is a compound containing bromine, and examples thereof include alkali metals bromide (for example, sodium bromide) that can be dissociated and ionized in water. Further, the iodide is a compound containing iodine, and examples thereof include an alkali metal iodide. The amount of bromide or iodide to be used may be selected within a range in which the oxidation reaction can be promoted. The total amount of bromide and iodide is preferably 0.1 mmol or more, more preferably 0.5 mmol or more, based on 1 g of the dry cellulose raw material. The upper limit is preferably 100 mmol or less, more preferably 10 mmol or less, and even more preferably 5 mmol or less. Therefore, the total amount of bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol with respect to 1 g of the dry cellulose raw material.

The oxidizing agent is not particularly limited, and examples thereof include halogens, hypohalogenic acids, subhalogenic acids, perhalogenic acids, salts thereof, halogen oxides, and peroxides. Among them, hypochlorous acid or a salt thereof is preferable, hypochlorous acid or a salt thereof is more preferable, and sodium hypochlorite is further preferable because it is inexpensive and has a small environmental load. The amount of the oxidizing agent used is preferably 0.5 mmol or more, more preferably 1 mmol or more, still more preferably 3 mmol or more, based on 1 g of the dry cellulose raw material. The upper limit is preferably 500 mmol or less, more preferably 50 mmol or less, still more preferably 25 mmol or less. Therefore, the amount of the oxidizing agent used is preferably 0.5 to 500 mmol, more preferably 1 to 50 mmol, still more preferably 3 to 25 mmol, based on 1 g of the dry cellulose raw material. When an N-oxyl compound is used, the amount of the oxidizing agent used is preferably 1 mol or more with respect to 1 mol of the N-oxyl compound. The upper limit is preferably 40 mol. Therefore, the amount of the oxidizing agent used is preferably 1 to 40 mol with respect to 1 mol of the N-oxyl compound.

Conditions such as pH and temperature during the oxidation reaction are not particularly limited, and in general, the oxidation reaction proceeds efficiently even under relatively mild conditions. The reaction temperature is preferably 4 ° C. or higher, more preferably 15 ° C. or higher. The upper limit is preferably 40 ° C. or lower, more preferably 30 ° C. or lower. Therefore, the temperature is preferably 4 to 40 ° C, and may be about 15 to 30 ° C, that is, room temperature. The pH of the reaction solution is preferably 8 or more, more preferably 10 or more. The upper limit is preferably 12 or less, more preferably 11 or less. Therefore, the pH of the reaction solution is preferably about 8 to 12, more preferably about 10 to 11. Usually, the pH of the reaction solution tends to decrease because a carboxyl group is generated in the cellulose as the oxidation reaction progresses. Therefore, in order to allow the oxidation reaction to proceed efficiently, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution in the above range. Water is preferable as the reaction medium for oxidation because it is easy to handle and side reactions are unlikely to occur.

The reaction time in oxidation can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 hours or more. The upper limit is not particularly limited, but is usually 6 hours or less, preferably 4 hours or less. Therefore, the reaction time in oxidation is usually 0.5 to 6 hours, preferably about 0.5 to 4 hours.

Oxidation may be carried out in two or more steps. For example, by oxidizing the oxidized cellulose obtained by filtration after the completion of the first-stage reaction again under the same or different reaction conditions, the efficiency is not affected by the reaction inhibition by the salt produced as a by-product in the first-stage reaction. Oxidation reaction can be carried out well.

Another example of the carboxylation (oxidation) method is a method of oxidizing by ozone treatment. By this oxidation reaction, the hydroxyl groups at at least the 2nd and 6th positions of the glucopyranose ring constituting the cellulose are oxidized, and the cellulose chain is decomposed. Ozone treatment is usually carried out by bringing a gas containing ozone into contact with a cellulose raw material. The ozone concentration in the gas ^{is preferably 50 g / m 3} or more. The upper limit is ^{preferably 250 g / m 3} or less, and ^{more preferably 220 g / m 3} or less. Therefore, the ozone concentration in the gas is preferably 50 to 250 g / ^{m 3,} more preferably 50~220g / ^{m 3.}
The amount of ozone added is preferably 0.1 part by mass or more, and more preferably 5 parts by mass or more, with respect to 100 parts by mass of the solid content of the cellulose raw material. The upper limit is usually 30 parts by mass or less. Therefore, the amount of ozone added is preferably 0.1 to 30 parts by mass, more preferably 5 to 30 parts by mass, based on 100 parts by mass of the solid content of the cellulose raw material.
The ozone treatment temperature is usually 0 ° C. or higher, preferably 20 ° C. or higher. The upper limit is usually 50 ° C. or lower. Therefore, the ozone treatment temperature is preferably 0 to 50 ° C, more preferably 20 to 50 ° C. The ozone treatment time is usually 1 minute or more, preferably 30 minutes or more. The upper limit is usually 360 minutes or less. Therefore, the ozone treatment time is usually about 1 to 360 minutes, preferably about 30 to 360 minutes. When the ozone treatment conditions are within the above range, it is possible to prevent the cellulose from being excessively oxidized and decomposed, and the yield of the oxidized cellulose becomes good.

The product obtained after the ozone treatment may be further subjected to an additional oxidation treatment using an oxidizing agent. The oxidizing agent used for the additional oxidation treatment is not particularly limited, and examples thereof include chlorine compounds such as chlorine dioxide and sodium chlorite; oxygen, hydrogen peroxide, persulfate, and peracetic acid. Examples of the method of the additional oxidation treatment include a method of dissolving these oxidizing agents in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and immersing the cellulose raw material in the oxidizing agent solution.

The amount of carboxyl group, carboxylate group, and aldehyde group contained in the cellulose oxide nanofiber can be adjusted by controlling the oxidation conditions such as the amount of the oxidizing agent added and the reaction time.

An example of a method for measuring the amount of carboxyl groups will be described below. Prepare 60 ml of a 0.5 mass% slurry (aqueous dispersion) of cellulose oxide, and add a 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5. Then, a 0.05 N aqueous sodium hydroxide solution is added dropwise, and the electrical conductivity is measured until the pH reaches 11. It can be calculated from the amount of sodium hydroxide (a) consumed in the neutralization step of a weak acid with a gradual change in electrical conductivity using the following formula:
Carboxyl group amount [mmol / g cellulose oxide or cellulose nanofiber] = a [ml] x 0.05 / mass of cellulose oxide [g]
The amount of carboxyl groups in cellulose oxide and the amount of carboxyl groups in cellulose nanofibers are usually the same.

[Carboxymethylation]
When the cellulose raw material is modified by carboxymethylation, the degree of carboxymethyl substitution per anhydrous glucose unit in the obtained carboxymethylated cellulose or cellulose nanofiber is preferably 0.01 or more, more preferably 0.05 or more, and 0. .10 or more is more preferable. The upper limit is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.35 or less. Therefore, the degree of carboxymethyl substitution is preferably 0.01 to 0.50, more preferably 0.05 to 0.40, and even more preferably 0.10 to 0.30.

The method of carboxymethylation is not particularly limited, and examples thereof include a method of marcelifying a cellulose raw material as a starting material and then etherifying it. A solvent is usually used in the carboxymethylation reaction. Examples of the solvent include water, alcohol (for example, lower alcohol) and a mixed solvent thereof. Examples of the lower alcohol include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol and t-butyl alcohol. The mixing ratio of the lower alcohol in the mixed solvent is usually 60 to 95% by mass. The amount of the solvent is usually three times or more that of the cellulose raw material in terms of mass. The upper limit is not particularly limited, but is 20 times or less. Therefore, the amount of the solvent is preferably 3 to 20 times by mass with respect to the cellulose raw material in terms of mass.

Mercerization is usually carried out by mixing a starting material and a mercerizing agent. Examples of the mercerizing agent include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide. The amount of the mercerizing agent used is preferably 0.5 times or more, more preferably 1.0 times or more, still more preferably 1.5 times or more, per anhydrous glucose residue of the starting material in terms of molars. The upper limit is usually 20 times or less, preferably 10 times or less, more preferably 5 times or less, therefore 0.5 to 20 times, more preferably 1.0 to 10 times, and 1.5 to 5 times. Double is more preferred.

The reaction temperature for mercerization is usually 0 ° C. or higher, preferably 10 ° C. or higher. The upper limit is usually 70 ° C. or lower, preferably 60 ° C. or lower. Therefore, the reaction temperature is usually 0 to 70 ° C, preferably 10 to 60 ° C. The reaction time is usually 15 minutes or longer, preferably 30 minutes or longer. The upper limit is usually 8 hours or less, preferably 7 hours or less. Therefore, the reaction time is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours.

The etherification reaction is usually carried out by adding a carboxymethylating agent to the reaction system after mercerization. Examples of the carboxymethylating agent include sodium monochloroacetate. The amount of the carboxymethylating agent added is usually preferably 0.05 times or more, more preferably 0.5 times or more, still more preferably 0.8 times or more per glucose residue of the cellulose raw material in terms of molar amount. The upper limit is usually 10 times or less, preferably 5 times or less, and more preferably 3 times or less. Therefore, the amount of the carboxymethylating agent added is preferably 0.05 to 10 times, more preferably 0.5 to 5 times, still more preferably 0.8 to 3 times.

The reaction temperature is usually 30 ° C. or higher, preferably 40 ° C. or higher. The upper limit is usually 90 ° C. or lower, preferably 80 ° C. or lower. Therefore, the reaction temperature is usually 30 to 90 ° C, preferably 40 to 80 ° C. The reaction time is usually 30 minutes or more, preferably 1 hour or more. The upper limit is usually 10 hours or less, preferably 4 hours or less. Therefore, the reaction time is usually 30 minutes to 10 hours, preferably 1 to 4 hours. If necessary, the reaction solution may be stirred during the carboxylation reaction.

The degree of carboxymethyl substitution per glucose unit of carboxymethylated cellulose nanofibers can be measured, for example, by the following method. That is, 1) Approximately 2.0 g of carboxymethylated cellulose (absolutely dried) is precisely weighed and placed in an Erlenmeyer flask with a 300 mL stopper. 2) Add 100 mL of a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol nitrate, and shake for 3 hours to convert the carboxymethyl cellulose salt (CM-modified cellulose) into acid-type carboxymethyl cellulose. 3) Weigh 1.5 to 2.0 g of acid-type carboxymethylated cellulose (absolutely dry) and place in a 300 mL Erlenmeyer flask with a stopper. 4) Wet acid-type carboxymethylated cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. 5) Using phenolphthalein as an indicator, back titrate excess NaOH with _{0.1 N H 2} SO _4. 6) Calculate the degree of carboxymethyl substitution (DS) by the following formula:
A = [(100 x F'-(0.1 N H ₂ SO ₄ ) (mL) x F) x 0.1] / (absolute dry mass (g) of acid-type carboxymethylated cellulose)
DS = 0.162 × A / (1-0.058 × A)
A: 1N NaOH amount (mL) required to neutralize 1 g of acid-type carboxymethylated cellulose
F: 0.1N H ₂ SO ₄ factor F': 0.1N NaOH factor

The degree of carboxymethyl substitution of the carboxymethylated cellulose nanofiber and the degree of carboxymethyl substitution of the carboxymethylated cellulose are usually the same.

[Cationation]
When the cellulose raw material is modified by cationization, the obtained cationized cellulose nanofiber may contain a cation such as ammonium, phosphonium, sulfonium, or a group having the cation in the molecule. The cationized cellulose nanofibers preferably contain a group having ammonium, and more preferably contain a group having quaternary ammonium.

The cationization method is not particularly limited, and examples thereof include a method in which a cationizing agent and a catalyst are reacted with a cellulose raw material in the presence of at least one of water and alcohol.

Examples of the cationizing agent include glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrialkylammonium hydrite (eg, 3-chloro-2-hydroxypropyltrimethylammonium hydrate), and halohydrin types thereof. Be done. By using any of these, a cationized cellulose having a group containing a quaternary ammonium can be obtained.
The amount of the cationizing agent is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more with respect to 100 parts by mass of the cellulose raw material. The upper limit is usually 800 parts by mass or less, preferably 500 parts by mass or less.

Examples of the catalyst include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide.
The amount of the catalyst is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more with respect to 100 parts by mass of the cellulose fiber. The upper limit is usually 7 parts by mass or less, preferably 3 parts by mass or less.

Examples of the alcohol include alcohols having 1 to 4 carbon atoms.
The amount of alcohol is preferably 50 parts by mass or more, and more preferably 100 parts by mass or more with respect to 100 parts by mass of the cellulose fiber. The upper limit is usually 50,000 parts by mass or less, preferably 500 parts by mass or less.

The reaction temperature at the time of cationization is usually 10 ° C. or higher, preferably 30 ° C. or higher. The upper limit is usually 90 ° C. or lower, preferably 80 ° C. or lower. The reaction time is usually 10 minutes or more, preferably 30 minutes or more. The upper limit is usually 10 hours or less, preferably 5 hours or less. If necessary, the reaction solution may be stirred during the cationization reaction.

The degree of cationization of cationized cellulose nanofibers per glucose unit can be adjusted by controlling the amount of cationizing agent added and the composition ratio of at least one of water and alcohol. The degree of cationization indicates the number of cationizing groups introduced per unit structure (glucopyranose ring) constituting cellulose. In other words, the degree of cationization is defined as "the value obtained by dividing the number of moles of the introduced cationizing group by the total number of moles of the hydroxyl groups of the glucopyranose ring". Since pure cellulose has three hydroxyl groups per unit structure (glucopyranose ring), the theoretical maximum value of the degree of cationization is 3 (minimum value is 0).

The degree of cationization of the cationized cellulose nanofibers per glucose unit is preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more. The upper limit is preferably 0.40 or less, more preferably 0.30 or less, and even more preferably 0.20 or less. Therefore, the degree of cationization is preferably 0.01 to 0.40, more preferably 0.02 to 0.30, and even more preferably 0.03 to 0.20.
By cationizing the cellulose, the celluloses electrically repel each other. Therefore, the cationized cellulose can be easily nano-defibrated. When the degree of cationization per glucose unit is 0.01 or more, nano-defibration can be sufficiently performed. On the other hand, when the degree of cationization per glucose unit is 0.40 or less, swelling or dissolution can be suppressed, whereby the fiber morphology can be maintained. Therefore, it is possible to prevent a situation that cannot be obtained as nanofibers.

An example of a method for measuring the degree of cationization per glucose unit of cationized cellulose nanofibers will be described below. After the sample (cationized cellulose) is dried, the nitrogen content is measured with a total nitrogen analyzer TN-10 (manufactured by Mitsubishi Chemical Corporation), and the degree of cationization is calculated by the following formula. The degree of cationization referred to here is an average value of the number of moles of cationizing groups per mole of anhydrous glucose unit.
Degree of cationization = (162 × N) / (1-151.6 × N)
N: Nitrogen content

The degree of cationization of the cationized cellulose nanofiber and the degree of cationization of the cationized cellulose are usually the same value.

[Distributed]
When the cellulose raw material is subjected to the modification treatment or the defibration treatment, the cellulose raw material may be subjected to the dispersion treatment to prepare a dispersion of the cellulose raw material. The solvent for dispersing the cellulose raw material is preferably water because the cellulose raw material is hydrophilic.

[Defibration]
The defibration may be performed before the modification treatment of the cellulose raw material or after the modification treatment. Further, the defibration may be performed at one time or a plurality of times. When defibrating is performed multiple times, there is no particular limitation on the timing of each defibration. The defibration treatment refers to a physical treatment as shown below.

The apparatus used for defibration is not particularly limited, and examples thereof include types such as high-speed rotary type, colloid mill type, high-pressure type, roll mill type, and ultrasonic type. The method of physically defibrating using these devices is preferable because a strong shearing force can be applied to the cellulose raw material or the modified cellulose (usually a dispersion liquid) and the defibration can be efficiently performed. The pressure that can be applied by the device is preferably 50 MPa or more, more preferably 100 MPa or more, and even more preferably 140 MPa or more. As the apparatus, a high-pressure or ultra-high pressure homogenizer capable of applying the above pressure to a cellulose raw material or modified cellulose (usually a dispersion liquid) and applying a strong shearing force is preferable, and a wet high-pressure or ultra-high pressure homogenizer is used. Is more preferable.

When defibration is performed on a dispersion of a cellulose raw material, the solid content concentration of the cellulose raw material in the dispersion is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3. It is mass% or more. As a result, the amount of liquid becomes appropriate with respect to the amount of the cellulose fiber raw material, which is efficient. The upper limit is usually 10% by mass or less, preferably 6% by mass or less. This makes it possible to maintain liquidity.

Prior to defibration (preferably defibration with a high-pressure homogenizer) or, if necessary, a dispersion treatment before defibration, pretreatment may be performed if necessary. The pretreatment may be performed using a mixing, stirring, emulsifying, or dispersing device such as a high-speed shear mixer.

[Form of modified cellulose nanofibers]
The form of the modified cellulose nanofibers is not particularly limited. Examples thereof include a dispersion of modified cellulose nanofibers, a dry solid of the dispersion, and a wet solid of the dispersion. The wet solid is a solid of an intermediate aspect between the dispersion and the dry solid.

[Dry]
The dry solids and wet solids of the modified cellulose nanofibers may be prepared by drying a dispersion of the modified cellulose nanofibers.
The drying method is not particularly limited, and examples thereof include spray drying, squeezing, air drying, hot air drying, and vacuum drying.
Examples of the drying device include a continuous tunnel drying device, a band drying device, a vertical drying device, a vertical turbo drying device, a multi-stage disk drying device, an aeration drying device, a rotary drying device, an air flow drying device, and a spray dryer drying device. Equipment, spray drying device, cylindrical drying device, drum drying device, screw conveyor drying device, rotary drying device with heating tube, vibration transport drying device, etc., batch type box drying device, aeration drying device, vacuum box drying device, Examples include a stirring and drying device. Among these, the reason is that heat energy can be uniformly supplied directly to the object to be dried and energy efficiency can be improved, and the reason that the dried object can be recovered immediately without applying heat more than necessary. Therefore, a drum drying device is preferable.
These drying devices may be used alone or in combination of two or more.

[1-5. Optional ingredient]
The composition of the present invention may contain other optional components as long as a film can be formed by heat treatment. Other optional components include compounds having heat resistance up to 200 ° C., such as solvents, thermoplastics, antibacterial agents, and glycerin. By changing the type of other arbitrary components, various functions can be imparted to the film obtained by heat-treating the composition. For example, by containing an antibacterial agent, the film can be used as a packaging material that can be stored for a long period of time.

The solvent is not particularly limited. Water; alcohols such as methanol and ethanol; amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane.

[1-6. Composition ratio]
In the composition of the present invention, the ratio of the components (A) to (D) (component (A): component (B): component (C): component (D)) is 20% by mass to 60% by mass: 10 Mass% to 40% by mass: 40% by mass or less: preferably 0.5% by mass to 10% by mass. However, the total of the components (A) to (D) is 100% by mass.
When the ratio of the component (A) to the component (B) is in the above range, the basic shape of the film by heat treatment can be formed. When the ratio of the component (C) is in the above range, the film can be given flexibility and can be applied to various uses. In particular, when the film is used as a separator for an electric double layer capacitor, the resistance value and the specific capacitance can be improved. When the ratio of the component (D) is in the above range, it can impart appropriate strength to the film and can be applied to various uses.
That is, by adjusting the ratio of the component (C) and the component (D), the flexibility and strength of the film can be adjusted, and the physical characteristics according to the use of the film can be obtained.

[2. the film]
The film of the present invention is obtained by heat-treating the above composition. In particular, the flexibility and strength of the film can be easily adjusted by adjusting the molecular weight and ratio of the component (C) and the ratio of the component (D), so that application to various applications can be expected.
Applications include separators for electric double layer capacitors, separation membranes for gases such as oxygen, and UV-blocking packaging materials.

Among the above applications, the film of the present invention is preferably used as a separator for an electric double layer capacitor because it has a large strain energy and is unlikely to break.

The method of forming the film is not particularly limited. As an example, a known method such as hot pressing after stirring the component (A), the component (C), and the component (D) in water, adding the component (B) to the freeze-dried dried product, and mixing the mixture. A film can be formed by heat-treating with.
The hot press conditions are not particularly limited as long as the film can be formed. As an example, the conditions of a heating temperature of 150 to 200 ° C., a heating time of 30 to 240 minutes, and a pressure of 0.1 to 10 MPa can be mentioned.

The thickness of the film is not particularly limited and can be appropriately adjusted according to the intended use. As an example, when used as a separator, 10 to 100 μm is preferable.

[3. Separator]
The separator of the present invention is made of the above film. Since the strain energy is large and the film is unlikely to break, it can be expected to be put into practical use.

[4. Electric Double Layer Capacitor]
The electric double layer capacitor of the present invention includes a pair of polar electrode bodies, an electrolytic solution, and the above-mentioned separator.
Since the electric double layer capacitor of the present invention uses the above-mentioned separator, it has a large strain energy and is unlikely to break the film during use.

Conventionally known materials can be used for the pair of polar electrode bodies. For example, a mixture of activated carbon, carbon black and PTFE can be mentioned.

Conventionally known materials can be used as the electrolytic solution. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, 4- (trifluoromethyl) -1,3-dioxolan-2-one; Diethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl n-propyl carbonate, methyl isopropyl carbonate, n-butyl methyl carbonate, diethyl carbonate, ethyl n-propyl carbonate, ethyl isopropyl carbonate, n-butyl ethyl carbonate, di n-propyl carbonate , Diisopropyl carbonate, din-butyl carbonate, fluoroethyl methyl carbonate, difluoroethyl methyl carbonate, trifluoroethyl methyl carbonate and other chain carbonates; ethyl isopropyl sulfone, ethyl methyl sulfone, ethyl isobutyl sulfone and other chain sulfones; 3-Methylsulfolane, γ-butyrolactone, acetonitrile, 1,2-dimethoxyethane, N-methylpyrrolidone, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, 2-methyltetrahexyl, 1,3-dioxolane, nitromethane, ethylene glycol, ethylene glycol dimethyl ether , Ethyl glycol diethyl ether, water or mixtures thereof.

Hereinafter, the present invention will be described in detail with reference to Examples. The following examples are for the purpose of preferably explaining the present invention, and do not limit the present invention.

[Tensile test]: Measured according to JIS K 7161 (ISO 527-1).

[Average fiber diameter, average fiber length, aspect ratio]: The average fiber diameter and the average fiber length were analyzed for 200 randomly selected fibers using an atomic force microscope (AFM). The aspect ratio was calculated by the following formula.
Aspect ratio = average fiber length / average fiber diameter

[Carboxyl group amount]: 60 ml of a 0.5 mass% slurry (aqueous dispersion) of cellulose oxide was prepared, and a 0.1 M hydrochloric acid aqueous solution was added to adjust the pH to 2.5. Then, a 0.05 N aqueous sodium hydroxide solution was added dropwise, and the electrical conductivity was measured until the pH reached 11. It was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization step of a weak acid with a gradual change in electrical conductivity.
Carboxyl group amount [mmol / g cellulose oxide or cellulose nanofiber] = a [ml] x 0.05 / mass of cellulose oxide [g]

[Carboxymethyl Substitution]: Measured by the following method.
Approximately 2.0 g of the sample was precisely weighed and placed in a 300 ml Erlenmeyer flask. Add 100 ml of methanol nitrate (1 L of anhydrous methanol plus 100 ml of special grade concentrated nitric acid) and shake for 3 hours to change the sodium salt of carboxymethylated cellulose (hereinafter, also referred to as "Na-CMC") to carboxymethylated cellulose (hereinafter, also referred to as "Na-CMC"). Hereinafter, it is also referred to as "H-CMC"). 1.5 to 2.0 g of the absolutely dried H-CMC was precisely weighed and placed in a 300 ml Erlenmeyer flask. The H-CMC was moistened with 15 ml of 80% methanol, 100 ml of 0.1 N NaOH was added and shaken at room temperature for 3 hours. Using phenolphthalein as an indicator _{, excess NaOH was back titrated with 0.1 N H 2} SO ₄ , and the degree of carboxymethyl substitution was calculated using the following formula.
[{100 x F- (0.1 N H ₂ SO ₄ (ml)) x F'} / (absolute dry mass of H-CMC (g))] x 0.1 = A
Carboxymethyl degree of substitution = 0.162A / (1-0.058A)
A: Amount of 1N NaOH required to neutralize 1 g of H-CMC (ml)
F': 0.1N H ₂ SO ₄ factor F: 0.1N NaOH factor

(Production Example 1: Preparation of PEG-lignin)
60 g of air-dried wood chips were suspended in 300 g of polyethylene glycol 400. To this suspension was added 0.9 g of a 95% aqueous sulfuric acid solution and heated at 160 ° C. for 240 minutes. After cooling to room temperature, 1.2 L of an 80% 1,4-dioxane aqueous solution was added, and the mixture was filtered. The concentrated solution obtained by distilling off the filtrate under reduced pressure was stirred at 140 ° C. for 150 minutes. The solution was poured into 4 L of water, stirred for 30 minutes, centrifuged at 11600 G for 15 minutes to collect the precipitate, and lyophilized to obtain PEG-lignin powder.

(Production Example 2: Preparation of carboxylated cellulose nanofibers)
5.00 g (absolutely dry) of bleached unbeaten kraft pulp (whiteness 85%) derived from coniferous trees, 39 mg (0.05 mmol per 1 g of absolute dry cellulose) of TEMPO (Sigma Aldrich) and 514 mg (absolute dry) of sodium bromide. It was added to 500 ml of an aqueous solution in which 1.0 mmol) was dissolved in 1 g of cellulose, and the mixture was stirred until the pulp was uniformly dispersed. An aqueous sodium hypochlorite solution was added to the reaction system so that the sodium hypochlorite content was 6.0 mmol / g, and the oxidation reaction was started. Although the pH in the system decreased during the reaction, a 3M aqueous sodium hydroxide solution was sequentially added to adjust the pH to 10. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system did not change. The mixture after the reaction was filtered through a glass filter to separate the pulp, and the pulp was thoroughly washed with water to obtain oxidized pulp (carboxylated cellulose). The pulp yield at this time was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.6 mmol / g. This was adjusted to 1.0% (w / v) with water and treated three times with an ultra-high pressure homogenizer (20 ° C., 150 MPa) to obtain an oxidized cellulose nanofiber dispersion. The average fiber diameter was 3 nm and the aspect ratio was 250.

(Production Example 3: Production of Ethered Cellulose Nanofibers)
In a stirrer capable of mixing pulp, 200 g of pulp (NBKP (coniferous bleached kraft pulp), manufactured by Nippon Paper Industries) by dry mass and 111 g of sodium hydroxide by dry mass (per anhydrous glucose residue of the base material). 25 times the molar amount) was added, and water was added so that the pulp solid content was 20% (w / v). Then, after stirring at 30 ° C. for 30 minutes, 216 g of sodium monochloroacetate (in terms of active ingredient, 1.5 times by mole per glucose residue of pulp) was added. After stirring for 30 minutes, the temperature was raised to 70 ° C. and the mixture was stirred for 1 hour. Then, the reaction product was taken out, neutralized and washed to obtain a carboxylmethylated pulp having a carboxymethyl substitution degree of 0.25 per glucose unit. This was made into a solid content of 1% with water, and treated with a high-pressure homogenizer at a pressure of 20 ° C. and 150 MPa five times to obtain carboxymethylated cellulose nanofibers. The average fiber diameter was 15 nm and the aspect ratio was 50.

(Example 1: Production of film)
The PEG-lignin prepared in Production Example 1, polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight of 500,000) and the modified cellulose nanofibers prepared in Production Example 2 were stirred in water and freeze-dried. Maleic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) is added to the dried product, and hot press (200 ° C, 5 MPa, 4 hours) using the trade name "HP-300 TL-S" (manufactured by Eucalyptus Giken). The film was manufactured.
The ratio of each component was 41.3% by mass of PEG-lignin, 29.7% by mass of polyethylene glycol, 1% by mass of modified cellulose nanofibers, and 28% by mass of maleic anhydride.

(Example 2: Production of film)
The same as in Example 1 except that the ratio of each component was changed to 39.5% by mass of PEG-lignin, 28.5% by mass of polyethylene glycol, 5% by mass of modified cellulose nanofibers, and 27% by mass of maleic anhydride. Manufactured the film.

(Example 3: Production of film)
The same as in Example 1 except that the ratio of each component was changed to 37.5% by mass of PEG-lignin, 27% by mass of polyethylene glycol, 10% by mass of modified cellulose nanofibers, and 25.5% by mass of maleic anhydride. Manufactured the film.

(Comparative Example 1: Film production)
The same as in Example 1 except that the ratio of each component was changed to 41.3% by mass of PEG-lignin, 29.7% by mass of polyethylene glycol, 0% by mass of modified cellulose nanofibers, and 29% by mass of maleic anhydride. Manufactured the film.

A tensile test was performed using the films produced in Examples 1 to 3 and Comparative Example 1. The results are shown in FIG. 1, and the strain energies are shown in Table 1 below.

As is clear from Table 1, it can be seen that the strain energy of the film is increased by using the composition containing the modified cellulose nanofibers as the component (D). Therefore, it can be seen that the film is less likely to break. Therefore, it can be expected to be applied to various uses.

Claims (9)

Ingredients (A): (a1) lignin source and (a2) PEG lignin, which is a reaction product of polyethylene glycol or poly (ethylene glycol) diglycidyl ether, which is liquid at 25 ° C.
(B) Ingredients: acid anhydride and
Component (C): Polyethylene glycol or poly (ethylene glycol) diglycidyl ether,
Ingredient (D): Containing modified cellulose nanofibers ,
The component (B) contains at least one selected from the group consisting of maleic anhydride, succinic anhydride, phthalic anhydride, citraconic anhydride, itaconic anhydride, aconitic anhydride, and hymic anhydride.
Composition. The composition according to claim 1, wherein (a1) is at least one selected from the group consisting of kraft lignin, lignin sulfonic acid, lignin acetate, organosolvrignin, blasted lignin, lignin sulfate, alkaline lignin and wood chips. thing. Wherein (a2) A composition according to claim 1 or 2 is polyethylene glycol. The component (C), the composition according to any one of claims 1 to 3 which is a polyethylene glycol. The invention according to any one of claims 1 to 4 , wherein the component (D) is at least one selected from the group consisting of carboxylated cellulose nanofibers, etherified cellulose nanofibers, and cationized cellulose nanofibers. Composition. The ratio of each component ((A) component: (B) component: (C) component: (D) component) is 20% by mass to 60% by mass: 10% by mass to 40% by mass: 40% by mass or less: 0. The composition according to any one of claims 1 to 5 which is 5% by mass to 10% by mass (however, the total of the components (A) to (D) is 100% by mass). A film obtained by heat-treating the composition according to any one of claims 1 to 6. The separator made of the film according to claim 7. A pair of polar electrode bodies and
With electrolyte
An electric double layer capacitor comprising the separator according to claim 8.

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