JP2017043750A - Cellulose ester aqueous dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose ester aqueous dispersion excellent in dispersibility and coatability and capable of suppressing tackiness of a dry coating film.SOLUTION: The cellulose ester aqueous dispersion contains a cellulose ester (A) and an anionic resin (B). The cellulose ester (A) is preferably at least one selected from the group consisting of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous cellulose ester dispersion.

Cellulose esters are widely used in applications such as paints and films because they can improve drying properties. For example, Patent Document 1 discloses a coating resin composition containing an acrylic resin, and discloses that the drying property of a coating film is improved by using cellulose acetate butyrate.

JP 2008-156415 A

In recent years, water-based paints and film materials have been studied from the viewpoints of environmental protection and VOC reduction. However, since cellulose ester is hydrophobic, it is difficult to disperse in water alone. Moreover, it turned out that it is difficult to disperse | distribute a cellulose ester in the surfactant generally used in order to improve a dispersibility. Furthermore, since the surfactant tends to bleed out and the dried coating film tends to be tacky, it may not be used depending on the application. Then, this invention provides the cellulose-ester aqueous dispersion which is excellent in the dispersibility and coating property, and can suppress the tackiness of a dry coating film.

The cellulose ester aqueous dispersion according to the present invention contains a cellulose ester (A) and an anionic resin (B).

The cellulose ester (A) is preferably at least one selected from the group consisting of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.

The anionic resin (B) is preferably at least one selected from the group consisting of an anionic polyester resin and an anionic polyurethane resin.

The aqueous cellulose ester dispersion according to the present invention preferably further contains anion-modified cellulose nanofiber (C).

The anion-modified cellulose nanofiber (C) is preferably oxidized cellulose (C1).

The coating composition which concerns on this invention contains the said cellulose-ester aqueous dispersion.

According to the present invention, it is possible to obtain an aqueous cellulose ester dispersion that is excellent in dispersibility and paintability and that can suppress tackiness of a dried coating film.

The cellulose ester aqueous dispersion according to this embodiment contains a cellulose ester (A).

The cellulose ester (A) of the present invention is one in which at least a part of the hydroxyl groups contained in cellulose is substituted with an organic ester group.

Examples of the organic ester group include aliphatic acyl groups such as acetyl group, propionyl group, and butyryl group, and aromatic acyl groups such as benzoyl group and toluyl group. Of these, an aliphatic acyl group is preferable. Further, it preferably contains a butyryl group, and preferably contains an acetyl group and a butyryl group.

The cellulose ester (A) preferably contains 20 to 80% by mass of a butyryl group. By setting it within the above range, it is possible to further improve the drying property of the paint and the like and further improve the orientation of the pigment. The content of the butyryl group is more preferably 25 to 70% by mass, and further preferably 30 to 65% by mass.

Specific examples of the cellulose ester (A) include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose propionate, cellulose propionate butyrate, and cellulose butyrate. Among these, cellulose acetate butyrate and cellulose butyrate are preferable, and cellulose acetate butyrate is more preferable because drying properties of paints and the like can be further improved and pigment orientation can be further improved.

The average number of organic ester groups in the cellulose ester (A) is preferably 8 to 12 per 4 glucose units constituting the glucose unit. By setting it within the above range, it is possible to further improve the drying property of the paint or the like. The ratio is more preferably 9-12 per glucose unit, and even more preferably 10-12.

The cellulose ester (A) preferably has a hydroxyl group content of 0.5 to 8% by mass. By setting it within the above range, it is possible to further improve the drying property of the paint or the like. The hydroxyl group content is more preferably 0.8 to 5% by mass, and further preferably 1 to 3% by mass.

The manufacturing method of the said cellulose ester (A) is not specifically limited, It can obtain by a well-known method. Commercial products can also be used.

The concentration of the cellulose ester (A) in the aqueous cellulose ester dispersion is 1 to
It is preferable that it is 60 mass%. By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. As for the said density | concentration, it is more preferable that it is 5-50 mass%, and it is further more preferable that it is 10-40 mass%.

The cellulose ester aqueous dispersion according to this embodiment contains an anionic resin (B).

The anionic resin (B) is not particularly limited as long as it is a resin containing an anionic group such as a carboxyl group or a sulfo group. Examples of such resins include anionic polyester resins, anionic polyurethane resins, and anionic acrylic resins. Among these, it is preferable that the dry coating film is at least one selected from the polyester resin (B1) and the polyurethane resin (B2) because the tack can be further reduced and the manufacturing process becomes simpler.

Examples of the anionic polyester resin (B1) include esterified products of a hydroxyl group-containing compound and a carboxyl group-containing compound.

Examples of the hydroxyl group-containing compound include polyhydric alcohol, polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, polyacryl polyol, polyacetal polyol, polybutadiene polyol, polysiloxane polyol, and fluorine polyol.

Examples of the carboxyl group-containing compound include polycarboxylic acid, polycarboxylic acid anhydride, polycarboxylic acid halide, and polycarboxylic acid alkyl ester. Examples of the polycarboxylic acid include adipic acid, sebacic acid, maleic acid, isophthalic acid, and terephthalic acid. Examples of the polycarboxylic acid anhydride include the above polycarboxylic acid anhydrides. Examples of the polycarboxylic acid halide include chlorides of the above polycarboxylic acids and bromides of the above polycarboxylic acids. Examples of the polycarboxylic acid alkyl ester include methyl ester of the polycarboxylic acid, ethyl ester of the polycarboxylic acid, and the like.

For example, the anionic group contained in the polyester resin (B1) can be reacted under conditions where the carboxyl group is excessive with respect to the hydroxyl group to obtain a terminal carboxyl group-containing polyester resin.

Moreover, the polyester resin which has an anionic group can be obtained by using the compound which has a carboxyl group, a sulfo group, and its salt. For example, a carboxyl group-containing polyester resin can be obtained by using a carboxyl group-containing polyol such as dimethylolpropionic acid or dimethylolbutanoic acid as the hydroxyl group-containing compound and reacting under the condition that the carboxyl group is not esterified. In addition, by using a polycarboxylic acid having a sulfo group or a salt thereof such as sodium 5-sulfoisophthalate, dimethyl sodium 5-sulfoisophthalate, or sodium 2-sulfoterephthalate, a polyester resin having a sulfo group can be obtained. it can.

The anionic group can be neutralized with a known neutralizing agent. Examples of such a neutralizing agent include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine and tripropylamine, and bases such as ammonia.

As an anionic polyurethane resin (B2), what contains an active hydrogen containing compound and an isocyanate group containing compound as a structural component is mentioned, for example. In addition, in this specification, the component of an anionic polyurethane resin (B2) means the raw material for obtaining an anionic polyurethane resin (B2).

Examples of the active hydrogen group-containing compound include monool, polyol, monoamine, and polyamine.

As monool, for example, methanol, ethanol, propanol, butanol,
Monoalcohols such as hexanol, octanol, decanol, dodecanol, octadecanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, etc. And oxyalkylene group-containing monools.

Examples of the polyol include polyhydric alcohol, polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, polyacryl polyol, polyacetal polyol, polybutadiene polyol, polysiloxane polyol, and fluorine polyol. Moreover, anionic group containing polyol is also mentioned.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, butanediol, propylene glycol, hexanediol, 3-methyl-1,5-pentanediol, bisphenol A, bisphenol B, bisphenol S, hydrogenated bisphenol A, and dibromo. Bisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether, trimethylolpropane, glycerin, pentaerythritol and the like can be mentioned.

Examples of the polyether polyol include oxyalkylene derivatives of polyhydric alcohols, polytetramethylene glycol, and polythioether polyols.
Specifically, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene bisphenol A, polyoxypropylene bisphenol A, polyoxyethylene polyoxypropylene bisphenol A
, Polyoxyethylene glyceryl ether, polyoxypropylene glyceryl ether,
Examples include polyoxyethylene polyoxypropylene glyceryl ether, polyoxyethylene trimethylol propane, polyoxypropylene trimethylol propane, polyoxyethylene polyoxypropylene trimethylol propane, and the like.

Examples of polyester polyols include esterified products of hydroxyl group-containing compounds such as polyhydric alcohols and polyether polyols and carboxylic acid derivatives such as polycarboxylic acids, polycarboxylic anhydrides and polycarboxylic esters. . Specifically, at least one diol selected from ethylene glycol, butanediol, hexanediol, methylpentaneol, neopentyl glycol and 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, And esterified products with at least one dicarboxylic acid selected from isophthalic acid and terephthalic acid. As the polyester polyol, commercially available products can also be used. -63, Teslak 2505
-63, test rack 2506-63, test rack 2508-70, test rack 5001-
40T, Teslak TA22-325B (all trade names of Hitachi Chemical Co., Ltd.), Nippon Run 136, Nippon Run 141, Nippon Run 152, Nippon Run 163, Nippon Run 16
4, Nippon Run 1004, Japan Run 3027, Japan Run 4002, Japan Run 400
9, Nippon Run 4010, Japan Run 4040, Japan Run 4042, Japan Run 407
3, Nippon Run 5018, Nippon Run 5035 (both are trade names of Tosoh Corporation), and the like. Moreover, as a polyester polyol, a castor oil polyol, a polycaprolactone polyol, etc. can be used.

As polycarbonate polyol, what consists of carbonate derivatives, such as a dimethyl carbonate, and the said polyhydric alcohol is mentioned, for example. Specifically, dimethyl carbonate, ethylene glycol, butanediol, hexanediol, 3-methyl-1
Polycarbonate polyol having at least one selected from 1,5-pentanediol and 1,4-cyclohexanediol as constituent components. Commercially available products can be used as the polycarbonate polyol, for example, BeNeBiOL NLDB.
Series, BeNeBiOL B series, BeNeBiOL NLB series, BeN
eBiOL HSB series, BeNeBiOL HS series (Brand name of Mitsubishi Chemical Corporation), Kuraray polyol C series (Brand name of Kuraray Co., Ltd.), ETERN
ACOLL UH series, ETERRNACOLL UHC series, ETERNACO
LL UC series, ETERNACOLL UM series (both are trade names of Ube Industries, Ltd.) and the like.

Examples of the polyolefin polyol include polybutadiene polyol, polyisoprene polyol, and hydrogenated products thereof.

Of these, polyether polyol, polyester polyol, and polycarbonate polyol are preferred. These polyols have a number average molecular weight of 500 to 5,000.
0 is preferred. In addition, these can use 1 type, or 2 or more types.

Moreover, in order to improve the water dispersibility of an anionic polyurethane resin (B2), it is preferable to use an anionic group containing polyol. Examples of the anionic group-containing polyol include dimethylolpropionic acid and dimethylolbutanoic acid.

  Examples of monoamines include taurine.

Examples of polyamines include ethylenediamine, propylenediamine, hexylenediamine, isophoronediamine, xylylenediamine, piperazine, diphenylmethanediamine, ethyltolylenediamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, piperazine, isophorone. Examples include diamines.

Examples of the isocyanate group-containing compound include tolylene diisocyanate and 2,2 ′.
-Diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate,
4,4′-diphenylmethane diisocyanate (MDI), 4,4′-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,
Aromatic polyisocyanates such as 3-phenylene diisocyanate and 1,4-phenylene diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate and araliphatic polyisocyanates such as α, α, α, α-tetramethylxylylene diisocyanate, tetramethylene Diisocyanate,
Dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate and 3-methylpentane-1 Aliphatic polyisocyanates such as 1,5-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate and 1,3-bis (isocyanate methyl) And alicyclic polyisocyanates such as cyclohexane. In addition, a large amount of the polyisocyanate modified body (biuret body, carbodiimide body, isocyanurate body, etc.) can also be used.

An anionic polyurethane resin (B2) can contain an oxime compound etc. further as a structural component.

The anionic polyurethane resin (B2) can be obtained by a known production method.
As such a production method, for example, a hydroxyl group-containing component such as monool or polyol and an isocyanate group-containing component such as aliphatic polyisocyanate or alicyclic polyisocyanate are reacted to form an isocyanate group-terminated urethane prepolymer. A method of neutralizing an anionic group using ammonia or a tertiary amine (such as triethylamine) and dispersing it in water and performing a chain extension reaction with water and a polyamine, hydroxyl groups such as monools and polyhydric alcohols The component and an isocyanate group-containing component such as aliphatic polyisocyanate or alicyclic polyisocyanate are reacted to form a hydroxyl-terminated urethane prepolymer, and if necessary, an anionic group using ammonia or a tertiary amine (such as triethylamine) Neutralize and disperse it in water Law and the like.

The anionic polyurethane resin (B2) has a carboxyl group content of 0.1 to 1.0 m.
It is preferably mol / g. By being in the said range, the dispersibility and coating property of a cellulose-ester aqueous dispersion will become more excellent. The carboxyl group content includes a carboxyl group content neutralized by ammonia or a tertiary amine.

Commercially available products can be used as the anionic polyurethane resin (B2) of the present invention. For example, Superflex 126, Superflex 130, Superflex 150,
Superflex 150HS, Superflex 170, Superflex 210
, Superflex 300, Superflex 420, Superflex 460,
Superflex 470, Superflex 740, Superflex 800, Superflex 820, Superflex 830HS, Superflex 860,
Superflex 870 (both are trade names of Daiichi Kogyo Seiyaku Co., Ltd.).

The concentration of the anionic resin (B) in the aqueous cellulose ester dispersion is 0.1 to
It is preferable that it is 50 mass%. By setting it within the above range, the dispersibility and paintability of the aqueous cellulose ester dispersion are further improved. The concentration is more preferably 0.3 to 40% by mass, and further preferably 0.5 to 30% by mass.

The aqueous cellulose ester dispersion according to this embodiment preferably contains anion-modified cellulose nanofibers (C).

The anion-modified cellulose nanofiber (C) preferably has a maximum fiber diameter of 1000 nm or less. By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. The maximum fiber diameter is more preferably 500 nm or less.

The anion-modified cellulose nanofiber (C) has a number average fiber diameter of 1 to 500 nm.
It is preferable that By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. The number average fiber diameter is more preferably 2 to 150 nm, further preferably 2 to 100 nm, and particularly preferably 3 to 80 nm.

The maximum fiber diameter and the number average fiber diameter of the cellulose fiber 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. And 5000 times, 10000 times or 50 depending on the size of the constituent fibers
Observation with an electron microscope image at any magnification of 000 times. At that time, assuming an axis of arbitrary vertical and horizontal image width in the obtained image, so that 20 or more fibers intersect the axis,
Adjust the sample and observation conditions (magnification, etc.). 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.

The anion-modified cellulose nanofiber (C) preferably has an aspect ratio of 50 or more. By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. More preferably, the aspect ratio is 100 or more.
More preferably, it is 00 or more.

The aspect ratio of the cellulose fiber can be measured, for example, by the following method. That is, from the TEM image (magnification: 10000 times) which was negatively stained with 2% uranyl acetate after the cellulose fibers were cast on a carbon film-coated grid that had been subjected to hydrophilic treatment, the number of cellulose fibers was determined according to the method described above. The average fiber diameter and fiber length are calculated, and the aspect ratio can be calculated using these values according to the following equation (1).

      Aspect ratio = number average fiber length (nm) / number average fiber diameter (nm) (1)

In the anion-modified cellulose nanofiber (C), the constituting cellulose preferably has an I-type crystal structure. By having an I-type crystal structure, the dispersibility becomes more excellent. Here, the cellulose constituting the cellulose fiber (A) has an I-type crystal structure, for example, in a diffraction profile obtained by wide-angle X-ray diffraction image measurement.
It can be identified by having typical peaks at two positions near theta = 14 to 17 ° and 2 theta = 22 to 23 °.

In the anion-modified cellulose nanofiber (C), the hydroxyl group on cellulose is preferably substituted with an anionic group. Examples of such an anionic group include a substituent containing a carboxyl group such as a carboxyl group or a carboxymethyl group or a salt thereof. When the hydroxyl group on cellulose is substituted with an anionic group, the dispersibility of the aqueous cellulose ester dispersion is further improved. Further, the anionic group preferably forms a salt with an inorganic alkali metal or organic amine because the dispersibility of the cellulose ester (A) is further excellent, and a salt with an inorganic alkali metal is more preferable. Further preferred are salts with alkali metals such as potassium and potassium.

Examples of the anion-modified cellulose nanofiber (C) include oxidized cellulose (C1), carboxymethylated cellulose (C2), polyvalent carboxymethylcellulose,
Long chain carboxycellulose and these inorganic salts are mentioned. Among these, since dispersibility and paintability are more excellent, at least one selected from oxidized cellulose (C1), carboxymethylated cellulose (C2), and inorganic salts thereof is preferable. Moreover, since it can suppress the tack property of a dry coating film more, it is preferable that it is at least 1 sort (s) selected from an oxidized cellulose (C1) and its inorganic salt. The reason why the tackiness of the dried coating film can be further suppressed is not clear, but it is assumed that the dried oxidized cellulose is difficult to dissolve in water. Furthermore, since the dispersibility of the aqueous cellulose ester dispersion is further improved, an inorganic salt of oxidized cellulose (C1) is preferable. Examples of the inorganic salt include alkali metal salts such as sodium salt and potassium salt.

The oxidized cellulose (C1) preferably contains 0.1 to 3.0 mmol / g of an anionic group. When the content of the anionic group is within the above range, the dispersibility of the aqueous cellulose ester dispersion is further improved. The content of the anionic group is 0.6.
More preferably, it is -2.5 mmol / g, and it is further more preferable that it is 1.0-2.2 mmol / g.

The oxidized cellulose (C1) preferably has a total content of aldehyde groups and ketone groups of 0.3 mmol / g or less as measured by a semicarbazide method. By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. The content is preferably 0.1 mmol or less.

Measurement of the total content of aldehyde groups and ketone groups by the semicarbazide method is performed, for example, as follows. That is, first, a dried sample is p-treated with a phosphate buffer.
Add exactly 50 ml of 3 g / l aqueous solution of semicarbazide hydrochloride adjusted to H = 5, and seal tightly.
Shake for two days. Next, 10 ml of this solution was accurately taken into a 100 ml beaker and 5 ml.
Add 25 ml of N sulfuric acid and 5 ml of 0.05N aqueous potassium iodate solution and stir for 10 minutes. Then, 10 ml of 5% potassium iodide aqueous solution was added and immediately using an automatic titrator,
Titration with a 0.1N sodium thiosulfate solution and the amount of carbonyl groups (total content of aldehyde groups and ketone groups) in the sample can be determined from the titration amount and the like according to the following formula (3).

Carbonyl group amount (mmol / g) = (D−B) × f × [0.125 / w] (3
)
D: Sample titration (ml)
B: Titrate of blank test (ml)
f: Factor of 0.1N sodium thiosulfate solution w: Sample amount (g)

In the oxidized cellulose (C1), it is preferable that an aldehyde group is not detected by a failing reagent. When the content of the aldehyde group is so small that it cannot be detected by the failing reagent, the dispersibility of the aqueous cellulose ester dispersion is further improved. In addition, the detection method of the aldehyde group by a Fehring reagent, for example, to a dried sample, a Fehring reagent (a mixed solution of sodium potassium tartrate and sodium hydroxide,
When an aqueous solution of copper sulfate pentahydrate is added and heated at 80 ° C. for 1 hour, the supernatant is blue and the cellulose portion is amber, and it can be determined that no aldehyde group has been detected. It can be determined that the aldehyde group has been detected when yellow and the cellulose part is red.

Examples of the oxidized cellulose (C1) include those obtained by oxidizing a hydroxyl group on a constituting glucose unit, and it is particularly preferable that the hydroxyl group at the 6-position on the glucose unit is selectively oxidized. It can be confirmed, for example, by a ¹³ C-NMR chart that the oxidized cellulose (C1) is obtained by selectively oxidizing the hydroxyl group at the 6-position on the glucose unit. 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, C6 of the glucose unit
It can be confirmed that the hydroxyl group is selectively oxidized to a carboxyl group or the like.

The oxidized cellulose (C1) is, for example, (1) an oxidation reaction step, (2) a reduction step, (3
It can be produced by a purification step, (4) a dispersion step (miniaturization treatment step), etc., and specifically, it is preferably produced 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, pH of 0.5M sodium hydroxide solution was added dropwise.
The reaction is considered to be completed when no change in pH is observed. here,
A co-oxidant is not a substance that directly oxidizes a cellulose hydroxyl group, but a substance that oxidizes an N-oxyl compound used as an oxidation catalyst.

The natural cellulose means purified cellulose isolated from cellulose biosynthetic systems such as plants, animals, and bacteria-producing gels. 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 bundle is easily swollen. This is preferable because the number average fiber diameter after the crystallization treatment can be reduced.

The dispersion medium of natural cellulose in the 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, especially 2,2.
, 6,6-Tetramethylpiperidinooxy radical (TEMPO) or 4-acetamido-TEMPO is preferred. 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 bromide metals, 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.),
In particular, temperature control is not required. 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, and the pH of the aqueous dispersion is about 10%.
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, but preferably LiBH ₄ , NaBH ₃ CN, Na
BH ₄ etc. are mentioned. Among these, NaBH ₄ is preferable from the viewpoint of cost and availability.

The amount of the reducing agent is preferably in the range of 0.1 to 4% by mass, particularly preferably in the range of 1 to 3% by mass, based on fine 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.

After completion of the 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. At this stage, the reactant fibers are usually not dispersed evenly to the nanofiber unit. Therefore, by repeating the usual refining method, that is, water washing and filtration, the reactant fibers are highly purified (99% by mass or more). Use water dispersion.

As the 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, continuous decanter). The aqueous dispersion of reactant fibers thus obtained is in the range of approximately 10% by mass to 50% by mass as the solid content (cellulose) concentration in the squeezed state. Considering the subsequent dispersion step, if the solid content concentration is higher than 50% by mass, it is not preferable because extremely high energy is required for dispersion.

(4) Dispersion process (miniaturization process)
The reaction fiber (water dispersion) impregnated with water obtained in the purification step is dispersed in a dispersion medium and subjected to a dispersion treatment. With the treatment, the viscosity increases, and a dispersion of cellulose nanofibers that has been refined 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. Law is used,
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 dispersion step include a homomixer under high-speed rotation, a high-pressure homogenizer, an ultra-high pressure homogenizer, an ultrasonic dispersion processor, a beater, a disk type refiner, a conical type refiner, a double disk type refiner, a grinder, and the like. Use of a powerful and beating-capable device is preferable in that a more efficient and advanced downsizing is possible, and a water-containing lubricant 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.

As said carboxymethylated cellulose (C2), what carboxymethylated the hydroxyl group on the glucose unit to comprise is mentioned, for example. Specifically, it is preferable to manufacture by the following steps.

As a manufacturing method of the said carboxymethylated cellulose (C2), it can manufacture with the following method using the said cellulose raw material, for example. 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 to 4 hours. Examples of the carboxymethylating agent include sodium monochloroacetate.

Cellulose nanofibers can be obtained by defibrating the carboxymethylated cellulose 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 14
0 MPa or more. In addition, prior to defibration / dispersion treatment with a high-pressure homogenizer, carboxymethylated cellulose may be pretreated using a known mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer as necessary. Is possible.

In this invention, it is preferable that the carboxymethyl substitution degree per glucose unit of carboxymethylated cellulose (C2) 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 nano-defibrated easily.
When the carboxymethyl substituent per glucose unit is 0.02 to 0.50, the dispersibility of the aqueous cellulose ester dispersion is further improved.

The concentration of the anion-modified cellulose nanofiber (C) in the aqueous cellulose ester dispersion is preferably 0.01 to 2% by mass. By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. The concentration is 0.0
It is more preferably 5 to 1% by mass, and further preferably 0.1 to 0.5% by mass.

The content of the anionic resin (B) is preferably 1 to 5000 parts by mass with respect to 100 parts by mass of the cellulose ester (A). By setting it within the above range, the dispersibility and paintability of the aqueous cellulose ester dispersion are further improved. As for the said content, it is more preferable that it is 5-3000 mass parts with respect to 100 mass parts of cellulose ester (A), and it is further more preferable that it is 10-1000 mass parts.

The content of the anion-modified cellulose nanofiber (C) is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the cellulose ester (A). By setting it within the above range, the dispersibility of the aqueous cellulose ester dispersion becomes more excellent. As for the said content, it is more preferable that it is 0.5-10 mass parts with respect to 100 mass parts of cellulose ester (A), and it is further more preferable that it is 1-5 mass parts.

The content of the anion-modified cellulose nanofiber (C) is determined by the anionic resin (
B) It is preferable that it is 0.1-50 mass parts with respect to 100 mass parts. By making it within the above range, the paintability of the cellulose ester aqueous dispersion becomes more excellent. As for the said content, it is more preferable that it is 0.5-40 mass parts with respect to 100 mass parts of anionic resin (B), and it is further more preferable that it is 1-25 mass parts.

The cellulose ester aqueous dispersion of the present invention contains water as a solvent, but may further contain an organic solvent. Examples of such an organic solvent include alcohol solvents such as ethanol, propanol, and butanol, ketone solvents such as acetone and methyl ethyl ketone, benzene, toluene, tetrahydrofuran, methyl chloride, and chloroform. The content of the organic solvent in the cellulose ester aqueous dispersion is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less. The organic solvent may be one in which the solvent used in the production of the aqueous cellulose ester dispersion remains, or may be a mixture separately after the production of the aqueous cellulose ester dispersion.

The cellulose ester aqueous dispersion of the present invention may contain known additives within a range that does not impair the effects of the present invention. Examples of such additives include preservatives and antioxidants. Can be mentioned.

As a manufacturing method of the cellulose ester aqueous dispersion of the present invention, for example, cellulose ester (A) and anionic resin (B), and optionally anion-modified cellulose nanofiber (C) are emulsified in a solvent containing water, If necessary, a method of distilling off the organic solvent can be mentioned.
Specifically, for example, an organic solvent solution containing cellulose ester (A) and an anionic resin (
A method of mixing an organic solvent solution containing B) and a solution containing anion-modified cellulose nanofibers (C) if necessary, emulsifying by adding water, and further distilling off at least a part of the organic solvent under reduced pressure, At least a part of the organic solvent is emulsified by mixing an organic solvent solution containing the cellulose ester (A) and an aqueous dispersion of the anionic resin (B) and, if necessary, a solution containing the anion-modified cellulose nanofiber (B). The method of distilling off under reduced pressure, etc. are mentioned. In addition, the said mixing process and emulsification process can be performed by a well-known method.

When an aqueous cellulose ester dispersion is produced by the above-described production method, the anionic resin (
The content of B) is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the cellulose ester (A). By making it within the above-mentioned range, the stability of the aqueous cellulose ester dispersion becomes more excellent. The content of the anionic resin (B) is 2 to 100 parts by mass of the cellulose ester (A). More preferably, it is 40 mass parts, 3-30
More preferably, it is part by mass.

Moreover, as a manufacturing method of the cellulose-ester aqueous dispersion at the time of using anionic polyurethane resin (B2) as anionic resin (B), the urethane prepolymer which is a precursor of a cellulose ester (A) and a polyurethane resin (B2) is used. A polyurethane resin (B) is obtained by emulsifying a polymer in a solvent containing water and subsequently performing a chain extension reaction of the urethane prepolymer.
2) and at least a part of the organic solvent is distilled off. Specifically, for example, an organic solvent solution containing a cellulose ester (A) and an organic solvent solution containing an isocyanate group-terminated urethane prepolymer are mixed and then emulsified by adding water, and if necessary, chained using the polyamine. Examples include a method in which an elongation reaction is performed and at least a part of the organic solvent is distilled off under reduced pressure. In addition, the said mixing process and emulsification process can be performed by a well-known method. In addition, when using anion-modified cellulose nanofiber (C), it may be mixed at any stage of the above process, and the manufacturing process becomes simpler. Is preferred.

When an aqueous cellulose ester dispersion is produced by the above-described production method, the anionic resin (
The content of B) is 200 to 5000 with respect to 100 parts by mass of the cellulose ester (A).
It is preferable that it is a mass part. By making it in the above range, the stability of the cellulose ester aqueous dispersion becomes more excellent, and the content of the anionic resin (B) is 250 to 100 parts by mass of the cellulose ester (A). It is more preferably 4000 parts by mass, and further preferably 300 to 3000 parts by mass.

The coating composition of this invention contains the said cellulose-ester aqueous dispersion. The aqueous cellulose ester dispersion is preferably used so that the content of the cellulose ester (A) in the coating composition is 0.1 to 10% by mass. The content is more preferably 0.5 to 7% by mass, and further preferably 1 to 5% by mass.

The coating composition of the present invention further includes resins other than the anionic resin (B), pigments, antifoaming agents, thickeners, antisettling agents, rust preventives, ultraviolet absorbers, surface conditioners, pigment dispersants, and the like. Can be contained.

Examples of resins other than the anionic resin (B) include acrylic resins, polyester resins, polyurethane resins, polyolefin resins, acrylic urethane resins, and melamine resins.

Examples of the pigment include titanium oxide, carbon black, bengara, aluminum, mica, clay, barita, calcium carbonate, silica, aluminum phosphomolybdate, and aluminum tripolyphosphate.

Next, although it demonstrates based on an Example and a comparative example, this invention is not limited to these Examples.

  The compounds used in this example are as follows.

<Cellulose ester (A)>
(A-1) Cellulose acetate butyrate (trade name: CAB-551-0.2, manufactured by Eastman Chemical Co., Ltd., average number of organic ester groups: 11 per 4 glucose units, hydroxyl group content 1.8% by mass, butyryl Group content: 52% by mass)
(A-2) Cellulose acetate butyrate (trade name: CAB-381-0.5, manufactured by Eastman Chemical Co., Ltd., average number of organic ester groups: 11 per 4 glucose units, hydroxyl group content: 1.3% by mass, butyryl Group content: 37% by mass)
(A-3) Cellulose acetate butyrate (trade name: CAB-553-0.4, manufactured by Eastman Chemical Co., Ltd., average number of organic ester groups: 9 per 4 glucose units, hydroxyl group content: 4.8% by mass, butyryl Group content: 46% by mass)

<Anionic resin (B)>
(Anionic polyester resin (B1))
Water dispersion (b1-1) of anionic polyester resin: Pluscoat Z-561 (trade name, manufactured by Kyoyo Chemical Co., Ltd., anionic group: sodium sulfonate, solid content: 25% by weight)
Water dispersion (b1-2) of anionic polyester resin: Pluscoat Z-687 (trade name, manufactured by Kyoyo Chemical Co., Ltd., solid content: 25% by weight)

(Anionic polyurethane resin (B2))
The anionic polyurethane resin obtained by the following manufacture examples 1-5 was used. Production Example 1
The polyols (1) to (3) in ˜5 are as follows.

Polyol (1): NIPPOLAN 4010 (trade name, polyester polyol, number average molecular weight: 2000, manufactured by Nippon Polyurethane Industry Co., Ltd.)
Polyol (2): Teslac 2477 (trade name, polyester polyol, number average molecular weight: 1700, manufactured by Hitachi Chemical Co., Ltd.)
Polyol (3): ETERNACOLL UH-200 (trade name, polycarbonate polyol, number average molecular weight: 2000, manufactured by Ube Industries, Ltd.)

(Production Example 1)
720 g of polyol (1) and 800 g of methyl ethyl ketone were added and stirred to obtain a uniform solution. 180 g of tolylene diisocyanate was added thereto and reacted at 75 ° C. for 1 hour. Thereafter, 60 g of dimethylolpropionic acid and 45 g of triethylamine were added and reacted at 75 ° C. to obtain a prepolymer solution having a terminal isocyanate group having an NCO content of 1.8% by weight. Next, this prepolymer was cooled to 40 ° C., 1857 g of water was added, and the mixture was stirred at high speed with a homomixer and emulsified. This was heated under reduced pressure to distill off methyl ethyl ketone to obtain a solid content of 30
An aqueous dispersion (b2-1) of an anionic polyurethane resin at a weight percent was obtained. (Carboxyl group content: 0.45 mmol / g)

(Production Example 2)
The same procedure as in Production Example 1 was performed except that the polyol (2) was changed to 730 g instead of the polyol (1) and the amount of tolylene diisocyanate used was changed to 190 g, and the solid content was 30% by weight.
An aqueous dispersion (b2-2) of an anionic polyurethane resin was obtained. (Carboxyl group content:
0.44 mmol / g)

(Production Example 3)
An aqueous dispersion (b2-3) of an anionic polyurethane resin having a solid content of 30% by weight, except that 720 g of polyol (3) was used instead of polyol (1), and the same operation as in Production Example 1 was performed.
Got. (Carboxyl group content: 0.44 mmol / g)

(Production Example 4)
The same procedure as in Production Example 1 was performed except that 670 g of polyol (1), 230 g of hexamethylene diisocyanate, 100 g of dimethylolpropionic acid, and 75 g of triethylamine were changed, and an anionic polyurethane resin having a solid content of 30% by weight was obtained. Water dispersion (b2-
4) was obtained. (Carboxyl group content: 0.69 mmol / g)

(Production Example 5)
The same procedure as in Production Example 1 was repeated, except that 800 g of polyol (1), 150 g of hexamethylene diisocyanate, 30 g of dimethylolpropionic acid, and 23 g of triethylamine were used. Dispersion (b2-5)
Got. (Carboxyl group content: 0.22 mmol / g)

<Anion-modified cellulose nanofiber (C)>
(Production Example 6)
2 g of softwood pulp, 150 ml of water, 0.25 g of sodium bromide, TEMPO 0.02
After 5 g was added and sufficiently stirred to disperse, a 13 wt% sodium hypochlorite aqueous solution (co-oxidant) had a sodium hypochlorite amount of 5.2 mmol / g with respect to 1.0 g of the pulp. The reaction was started. Since the pH decreases with the progress of the reaction, the pH is adjusted to 10 to 10.
The reaction was continued until no pH change was observed while adding a 0.5N aqueous sodium hydroxide solution dropwise so as to maintain 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. Solid-liquid separation was performed with a centrifuge, and pure water was added to adjust the solid content concentration to 4% by weight. Sodium hydroxide having an amount equivalent to the amount of carboxyl groups contained in the obtained oxidized cellulose was added, and the mixture was treated once at a pressure of 100 MPa using a high pressure homogenizer (manufactured by Sugino Machine, Starburst). This was diluted with pure water so that the concentration of the anion-modified cellulose nanofiber was 2% by weight. K. 10 at 8000 rpm with a homomixer (manufactured by PRIMIX)
By stirring for 2 minutes, a 2% by weight aqueous solution (c1-1) of oxidized cellulose sodium salt was obtained.

(Production Example 7)
The amount of 13% by weight aqueous sodium hypochlorite solution added was 6 per 1.0 g of softwood pulp.
. Except having been 5 mmol / g, operation similar to manufacture example 6 was performed and 2 weight% aqueous solution (c1-2) of the oxidized cellulose sodium salt was obtained.

(Production Example 8)
13% by weight of sodium hypochlorite aqueous solution added to 1.0 g of softwood pulp
Except having been set to 2.0 mmol / g, the same operation as in Production Example 6 was performed to obtain a 2% by weight aqueous solution (c1-3) of oxidized cellulose sodium salt.

(Production Example 9)
To the stirrer, 200 g of pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) in dry mass and 106 g of sodium hydroxide in dry mass were added, and water was added so that the pulp solid content concentration was 15 wt%.
Then, after stirring at 30 ° C. for 30 minutes, the temperature was raised to 70 ° C., and sodium monochloroacetate was added to 1
40 g (in terms of active ingredient) was added. After reacting for 1 hour, the reaction product was taken out, neutralized and washed. Thereafter, water is added to the carboxymethylated cellulose to obtain a solid content concentration of 5% by weight, and the mixture is treated 5 times with a high-pressure homogenizer at 20 ° C. and a pressure of 140 MPa.
A 5% by weight aqueous solution (c2-1) of carboxymethylated cellulose was obtained.

(Production Example 10)
The amount of sodium hydroxide used was 176 g, and the amount of sodium monochloroacetate used was 23
The same operation as in Production Example 9 was performed except that the amount was 4 g (in terms of active ingredient) to obtain a 5% by weight aqueous solution (c2-2) of carboxymethylated cellulose.

(Production Example 11)
The amount of sodium hydroxide used was 308 g, and the amount of sodium monochloroacetate used was 41
The same operation as in Production Example 9 was performed except that the amount was changed to 0 g (in terms of active ingredient) to obtain a 5% by weight aqueous solution (c2-3) of carboxymethylated cellulose.

About the anion modified cellulose nanofiber obtained as mentioned above, each characteristic was evaluated according to the following reference | standard. The results are shown in Table 1.

<Crystal structure>
The diffraction profile of the anion-modified cellulose nanofiber was measured using an X-ray diffractometer (RINT-Ultima 3 manufactured by Rigaku Corporation), and 2 theta was around 14-17 ° and 2
When typical peaks are observed at two positions near theta = 22-23 °, the crystal structure (I
Type crystal structure) was evaluated as “Yes”, and when no peak was observed, it was evaluated as “None”.

<Measurement of number average fiber diameter and aspect ratio>
Pure water was added to the anion-modified cellulose nanofiber to dilute it to 1%, and it was treated once at a pressure of 100 MPa using a high-pressure homogenizer (H11, manufactured by Sanwa Engineering Co., Ltd.).
The number average fiber diameter and fiber length of the anion-modified cellulose nanofiber at that time were observed using a transmission electron microscope (TEM, JEM-1400 manufactured by JEOL Ltd.). That is, each anion-modified cellulose nanofiber was cast on a hydrophilized carbon film-coated grid and then negatively stained with 2% uranyl acetate (magnification: 1).
(0000 times), the number average fiber diameter and fiber length were calculated according to the method described above. Further, using these values, the aspect ratio was calculated according to the above-described formula (1).

<Measurement of carboxyl group content of oxidized cellulose>
60 ml of an aqueous cellulose dispersion in which 0.25 g of oxidized cellulose is dispersed in water is prepared.
. The pH was adjusted to about 2.5 with a 1M aqueous hydrochloric acid solution, and a 0.05M aqueous sodium hydroxide solution was added dropwise to measure the electrical conductivity. The measurement was continued until the pH was 11. The amount of carboxyl groups was determined from the amount of sodium hydroxide consumed (V) in accordance with the following formula (4) in the neutralization step of the weak acid with a gradual change in electrical conductivity.

  Amount of carboxyl groups (mmol / g) = V (ml) × [0.05 / cellulose weight] (4)

<Measurement of degree of carboxymethyl substitution per glucose unit of carboxymethylated cellulose>
Prepare a 0.6% by weight slurry of carboxymethylated cellulose and add 0.1M aqueous hydrochloric acid to pH 2.4, then add 0.05N aqueous sodium hydroxide dropwise to adjust the pH to 1.
The electrical conductivity was measured until it reached 1, and the amount of carboxyl groups was measured from the amount of sodium hydroxide consumed in the weak acid neutralization stage where the change in electrical conductivity was gradual, and was calculated according to the following formula (5).

Carboxymethyl substitution degree = (162 × C) / (1-58 × C) (5)
(In the formula, C represents the carboxyl group amount (mmol / g).)

<Measurement of carbonyl group content of oxidized cellulose (semicarbazide method)>
About 0.2 g of oxidized cellulose was precisely weighed, and precisely 50 ml of a semicarbazide hydrochloride 3 g / l aqueous solution adjusted to pH = 5 with a phosphate buffer was added thereto, sealed, and shaken for 2 days. Next, 10 ml of this solution was accurately collected in a 100 ml beaker, 25 ml of 5N sulfuric acid,
5 ml of 0.05N potassium iodate aqueous solution was 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, etc., the carbonyl in the sample was determined according to the above formula (3). The base amount (total content of aldehyde group and ketone group) was determined.

<Detection of aldehyde group of oxidized cellulose>
0.4 g of cellulose oxide was precisely weighed, and after adding a Feling reagent (5 ml of a mixed solution of sodium potassium tartrate and sodium hydroxide and 5 ml of an aqueous solution of copper sulfate pentahydrate) prepared according to the Japanese Pharmacopoeia, Heated for 1 hour. And when the supernatant was blue and the anion-modified cellulose nanofiber part was amber, it was judged that no aldehyde group was detected, and was evaluated as “none”. Moreover, when the supernatant was yellow and the anion-modified cellulose nanofiber portion was red, it was judged that an aldehyde group was detected, and was evaluated as “present”.

Example 1
30 g of cellulose ester (a-1) and an aqueous dispersion of an anionic polyester resin (b1
-1) 10 g was dissolved in 80 g of methyl ethyl ketone. This solution was treated with T.W. K. The emulsion was emulsified by gradually dropping 60 g of water while stirring at 5000 rpm using a homomixer (manufactured by PRIMIX). Subsequently, the solvent (methyl ethyl ketone) was distilled off with an evaporator to obtain a cellulose ester aqueous dispersion having a solid content of 36% by weight.

(Example 2)
30 g of cellulose ester (a-1) and an aqueous dispersion of an anionic polyester resin (b1
-1) 10 g was dissolved in 80 g of methyl ethyl ketone. This solution was treated with T.W. K. While stirring at 5000 rpm using a homomixer (manufactured by PRIMIX), a mixture of 10 g of a 2% by weight aqueous solution of oxidized sodium sodium salt (c1-1) obtained in Production Example 6 and 50 g of water was gradually added dropwise. Emulsified. Subsequently, the solvent (methyl ethyl ketone) was distilled off with an evaporator to obtain a cellulose ester aqueous dispersion having a solid content of 33% by weight.

(Examples 3 to 31)
The same operation as in Example 2 was performed except that the compounds and ratios shown in Table 2 and Table 3 were used.
A cellulose ester aqueous dispersion was obtained.

(Example 32)
720 g of polyol (1) and 800 g of methyl ethyl ketone were added and stirred to obtain a uniform solution. 180 g of tolylene diisocyanate was added thereto and reacted at 75 ° C. for 1 hour. Thereafter, 60 g of dimethylolpropionic acid and 45 g of triethylamine were added and reacted at 75 ° C. to obtain a prepolymer solution having a terminal isocyanate group having an NCO content of 1.8% by weight. Next, this prepolymer solution and 45 g of cellulose ester (a-1) were mixed, and 4
Cool to 0 ° C. and add 1857 g of water. K. The mixture was stirred and emulsified at 5000 rpm using a homomixer (manufactured by PRIMIX). Subsequently, the solvent (methyl ethyl ketone) was distilled off with an evaporator to obtain a cellulose ester aqueous dispersion having a solid content of 32% by weight. (Carboxyl group content of anionic polyurethane resin: 0.45 mmol / g)

(Example 33)
Before distilling off the solvent (methyl ethyl ketone) with an evaporator, the same operation as in Example 32 was carried out except that 200 g of a 2 wt% aqueous solution (c1-1) of oxidized cellulose sodium salt was mixed, and cellulose having a solid content of 29 wt% An ester aqueous dispersion was obtained. (Carboxyl group content of anionic polyurethane resin: 0.45 mmol / g)

(Comparative Example 1)
The same operation as in Example 1 was performed except that 10 g of water was used instead of the aqueous dispersion (b1-1) of the anionic polyester resin, but a cellulose ester dispersion could not be obtained.

(Comparative Example 2)
Instead of the aqueous dispersion (b1-1) of the anionic polyester resin, 10 g of a 30 wt% aqueous solution of an anionic surfactant (trade name: Hytenol NF-13, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used. The same operation as in Example 1 was performed, but a cellulose ester dispersion could not be obtained.

Dispersibility was evaluated by the following methods using the cellulose ester aqueous dispersions obtained in Examples 1 to 33. The results are shown in Table 4 and Table 5.

(Average particle size)
The 50% volume average particle diameter (μm) was measured according to JIS Z8825.

(Dispersibility)
The obtained cellulose ester aqueous dispersion was allowed to stand at 20 ° C. and 40 ° C. The presence or absence of a precipitate or separation was confirmed every day (24 hours), and the number of days until either precipitation or separation was observed was used as the evaluation result.

3 g of the cellulose ester aqueous dispersion obtained in Examples 1 to 33 and 100 g of a commercially available water-based paint (trade name: water paint Big 10 multipurpose, manufactured by Asahi Paint Co., Ltd.) were mixed to obtain a coating composition. . Dispersibility, paintability and tack were evaluated by the following methods using the obtained coating composition. The results are shown in Table 4 and Table 5.

(Dispersibility)
The coating composition was allowed to stand at 20 ° C., and the presence or absence of precipitates or separation was confirmed every day (24 hours). The number of days until either precipitation or separation was observed was used as the evaluation result.

(Paintability)
The coating composition was applied with a coater so as to have a dry film thickness of 20 μm. 5
It dried at 0 degreeC for 3 hours, and evaluated the coating-film state on the following reference | standard.
○: There is no coating unevenness and pinhole.
X: There are uneven coating or pinholes.

(tack)
Water was applied to the surface of the coating film prepared by the evaluation of the paintability. The presence or absence between tacks on the surface of the coating film after wiping off water was evaluated by finger touch according to the following criteria.
○: There is no tackiness.
X: There is a feeling of tack.

Claims (6)

An aqueous cellulose ester dispersion containing a cellulose ester (A) and an anionic resin (B). The cellulose ester aqueous dispersion according to claim 1, wherein the cellulose ester (A) is at least one selected from the group consisting of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. The aqueous cellulose ester dispersion according to claim 1 or 2, wherein the anionic resin (B) is at least one selected from the group consisting of an anionic polyester resin and an anionic polyurethane resin. Furthermore, the cellulose-ester aqueous dispersion of any one of Claims 1-3 containing an anion modified cellulose nanofiber (C). The cellulose ester aqueous dispersion according to claim 4, wherein the anion-modified cellulose nanofiber (C) is oxidized cellulose (C1). The coating composition containing the cellulose-ester aqueous dispersion of any one of Claims 1-5.