JP3396511B2 - Method for producing aqueous cellulose derivative - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cellulose derivative for aqueous coating which is useful as a pigment dispersant such as an aqueous paint, an aqueous ink, an aqueous paper coating agent, a drying agent, a heat resistance improver and a flammability agent. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as an aqueous cellulose derivative for an aqueous coating, a cellulose derivative such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose has been used as a thickener for an aqueous coating agent. These are not used as pigment dispersants because they have extremely insufficient pigment dispersibility.

On the other hand, nitrocellulose has a pigment dispersibility,
It has been widely used in solvent-based coating agents as a resin with excellent dryness, hardness, blocking resistance, and thickening properties.
Nitrocellulose is essentially insoluble in water or a mixed solvent of water and an organic solvent and cannot be used as an additive for an aqueous coating agent. Therefore, a lacquer emulsion has been proposed in which ordinary nitrocellulose is dissolved in an organic solvent together with an organic solvent-soluble plasticizer or resin and dispersed in water in the presence of a surfactant. For example, Japanese Patent Publication No. 45-277719 and Japanese Patent Publication No. 46-3.
In No. 666, nitrocellulose was dissolved in an organic solvent together with a plasticizer, and then dispersed in water in the presence of a surfactant,
A composition obtained by distilling off an organic solvent is also disclosed in JP-A-51-
No. 288188 proposes a composition obtained by dissolving ordinary nitrocellulose in a monomer capable of dissolving nitrocellulose, dispersing the nitrocellulose in water in the presence of a surfactant, and then polymerizing the dispersion. JP-A-59-71342 discloses that oxidized nitrocellulose having a carboxyl group content of 2 meq / 100 g or more, an oil phase containing at least a solvent which dissolves the nitrocellulose and is hardly soluble in water, and water. Emulsion compositions consisting of an aqueous phase as the main component have been proposed. Although these compositions have the characteristics of nitrocellulose in terms of drying property, hardness, and blocking resistance,
It could not be adsorbed on the surface of the pigment and did not function as a pigment dispersant for the aqueous coating agent.

As described above, the conventional cellulose derivatives for aqueous coating have a problem that they do not have pigment dispersibility, drying property and heat resistance.

[0005]

An object of the present invention is to provide a method for producing an aqueous cellulose derivative having excellent pigment dispersibility, drying property and heat resistance.

[0006]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, a nitrate ester group and a carboxyalkyl ether group are present at the same time per anhydrous glucose group, and nitric acid per anhydrous glucose group is present. Carboxyalkyl nitrocellulose having an ester group substitution degree of 0.2 or more and a carboxyalkyl ether group substitution degree of 0.05 or more is soluble in a mixed solvent of water and an organic solvent, and has drying property, hardness, and Blocking resistance, thickening,
The fact that the pigment dispersibility is extremely excellent was found and the present invention was completed.

That is, according to the present invention, the degree of carboxyalkyl ether group substitution per anhydrous glucose group is 0.
Carboxyalkyl ether cellulose having a degree of substitution of 0.2 or more per one anhydrous glucose group is obtained by subjecting a carboxyalkyl ether cellulose of 05 or more to a nitric acid reaction with a mixed acid of nitric acid / water or nitric acid / water / sulfuric acid. A method for producing an aqueous cellulose derivative having a degree of group substitution of 0.05 or more, wherein the composition ratio of nitric acid / water or nitric acid / water / sulfuric acid is 1% by weight or more and 99% by weight or less, and 1% by weight or less. Weight% or more, 30 weight% or less, sulfuric acid amount 90
A method for producing an aqueous cellulose derivative, characterized in that it is not more than wt%, the ratio of carboxyalkyl ether cellulose and mixed acid is 1/2 to 1/300 by weight, and the nitrification reaction temperature is -20 ° C to 30 ° C. It is about.

The raw material cellulose derivative used in the present invention is a carboxyalkyl ether cellulose having a degree of carboxyalkyl ether group substitution per anhydroglucose group of 0.05 or more, such as carboxymethyl cellulose and carboxyethyl cellulose. Carboxyalkyl cellulose can be used. As the mixed acid for the nitrification reaction used in the present invention, nitric acid / water and nitric acid / water / sulfuric acid are preferably used. Nitric acid functions as a nitrification reaction agent, and water functions as a nitrification degree adjusting agent.
Sulfuric acid functions as a dehydrating agent that accelerates the nitrification reaction, so it is added when it is necessary to increase the reaction rate. In addition to sulfuric acid, other acid systems exhibiting a dehydrating effect, such as phosphoric acid,
It can also be used with acetic acid and the like. However, sulfuric acid is preferred because it is industrially inexpensive. The composition of nitric acid / water or nitric acid / water / sulfuric acid to be added is 1% by weight or more of nitric acid, 99
It is desirable that the content is less than 1% by weight, 1% by weight or more of water, 30% by weight or less and 90% by weight or less of sulfuric acid. When nitric acid is less than 1% by weight, the nitrification reaction does not substantially occur. If the amount of water exceeds 30% by weight, lumps are generated during nitrification and the quality of the product deteriorates. When the sulfuric acid exceeds 90% by weight, the raw material cellulose is decomposed and the degree of coloring increases. A more preferable range is 10% by weight to 98% by weight of nitric acid and 25% by weight of water.
% By weight and 80% by weight or less of sulfuric acid.

The ratio of the raw material cellulose derivative to the mixed acid for nitrification reaction in the present invention is 1/2 to 1/300 by weight. When it is less than 1/2, it is difficult to remove heat generated during the reaction, and when it exceeds 1/300, the yield of the aqueous cellulose derivative of the present invention obtained is small, and the productivity is industrially deteriorated. A more preferable range is 1/10 to 1 /
100.

The temperature of the nitrification reaction in the present invention is -20.
The temperature is not lower than 30 ° C and not higher than 30 ° C. Great expense for cooling is less than -20 ° C. is required, the yield of the aqueous cellulose derivative decreases, which is an object of the present invention obtained exceeds 30 ° C.. As for the nitrification reaction temperature, the mixed acid is nitric acid / water /
In the case of sulfuric acid, it is preferably -20 ° C to 21 ° C.
Yes. The aqueous cellulose derivative obtained in the present invention described above,
The molecular weight can be adjusted if necessary. Generally, there is a method of thermally depolymerizing the obtained carboxyalkyl nitrocellulose at 40 ° C to 170 ° C. Further, a method of performing depolymerization within the above temperature range by adding an oxidizing agent or the like can also be adopted.

An example of the production method of the present invention will be shown below. Carboxymethyl cellulose is placed in a reactor containing a mixed acid of nitric acid / water or nitric acid / water / sulfuric acid and stirred to cause nitrification reaction. After the reaction, the product is deoxidized with a centrifuge and immediately washed with a large amount of water to obtain the product. The nitrate ester group substitution degree and the carboxymethyl ether group substitution degree of the obtained aqueous cellulose derivative were measured by the following measuring methods.

0.1 g of the dried reaction product was precisely weighed and analyzed by elemental analysis to obtain a weight percentage of nitrogen atoms (hereinafter abbreviated as nitrogen percentage).
I asked. The reaction product was precisely weighed in an amount of 1 g, placed in a 300 ml Erlenmeyer flask with a stopper, and 15 ml of 80% methanol was added. Further, 100 ml of 1 / 10N sodium hydroxide solution was accurately added, and the mixture was kept at room temperature for 3 hours. After shaking, add phenolphthalein to 1
It was titrated with / 10 normal sulfuric acid.

The equivalent amount of carboxymethyl ether groups per 1 g of the sample was calculated by the following formula. A (equivalent / g) = (100-1 / 10 normal sulfuric acid ml) ×
f × 10000 where f; factor of 1/10 normal sulfuric acid Using the obtained nitrogen% and A equivalent / g, according to the following formula, the degree of substitution of nitrate ester group per anhydroglucose group and carboxymethyl ether group The degree of substitution was calculated.

X = 162n / (14-45n-58 × 14A) Y = 14XA / n Z = 3- (X + Y) where X: nitrate ester substitution degree Y; carboxymethyl ether substitution degree Z; residual hydroxyl group n; (Nitrogen%) / 100 An example of a method for preparing a solution of the aqueous cellulose derivative obtained in the present invention will be shown.

The aqueous cellulose derivative obtained in the present invention is weighed in a closed container equipped with a stirrer, a predetermined amount of water and a solvent are added, and the mixture is stirred. Next, a predetermined amount of neutralizing agent is added and dissolved. In the method for producing an aqueous cellulose derivative of the present invention, the yield of the reaction product is high, and since the raw material cellulose derivative uniformly causes a nitrification reaction, the obtained aqueous cellulose derivative has a high solubility in water and a pigment dispersion. It is used as a pigment dispersant for water-based paints, water-based inks, water-based paper coatings, etc., as a drying and heat resistance improver. To be

[0016]

EXAMPLES The present invention will be described in more detail below by showing Examples of the present invention.

[0017]

Example 1 100 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.7) and sulfuric acid /
3 liters of acid mixture consisting of nitric acid / water = 57.3 / 20.1 / 22.6% by weight (raw material / acid = 1/50 weight ratio) was placed in a 5 liter reaction vessel and stirred at 5 ° C. for 60 minutes. While performing the nitrification reaction. The product is deoxidized with a centrifuge and immediately washed with a large amount of water. 100 g of reaction product was obtained. The generated carboxyalkyl nitrocellulose,
It is dried at 80 ° C. for 2 hours, and each substitution degree is measured. The obtained reaction product had a degree of substitution of a nitrate ester group of 1.1 and a degree of substitution of a carboxymethyl ether group of 0.7 per anhydrous glucose group.

100 g of the product obtained are treated at 130 ° C. with 3
Depolymerization was carried out for 0 minutes to obtain 90 g of carboxyalkyl nitrocellulose.

[0019]

Example 2 The same procedure as in Example 1 was carried out except that only carboxymethyl cellulose used was replaced with a carboxymethyl ether group substitution degree = 0.5. As a result, 110 g of a reaction product was obtained. As a result of measurement in the same manner as in Example 1, the obtained reaction product had a nitrate ester group substitution degree of 1.2 and a carboxymethyl ether group substitution degree of 0.5 per anhydrous glucose group.

100 g of the product obtained are treated at 140 ° C. with 4
Depolymerization was carried out for 5 minutes to obtain 90 g of carboxyalkyl nitrocellulose.

[0021]

[Example 3] The same procedure as in Example 1 was repeated except that the carboxymethyl cellulose used was replaced with a carboxymethyl ether group substitution degree of 1.6. As a result, 80 g of a reaction product was obtained. As a result of measurement in the same manner as in Example 1, the obtained reaction product had a degree of substitution with a nitrate ester group of 0.3 per one anhydrous glucose group and a degree of substitution with a carboxymethyl ether group of 1.6.

80 g of the obtained product and 4 g of hydrogen peroxide
Was depolymerized at 95 ° C. for 60 minutes to obtain 72 g of carboxyalkyl nitrocellulose.

[0023]

Example 4 100 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.5) and sulfuric acid /
3 liters of an acid mixture consisting of nitric acid / water = 62.6 / 24.8 / 12.6% by weight (raw material / acid = 1/50) was placed in a 5 liter reaction vessel and stirred at 5 ° C. for 60 minutes. Deoxidize the product with a centrifuge, immediately wash with plenty of water, and
30 g of reaction product was obtained.

As a result of measurement in the same manner as in Example 1, the reaction product obtained had a nitrate ester group substitution degree of 2.1 and a carboxymethyl ether group substitution degree of 0.5 per anhydrous glucose group. It was 100 g of the obtained product was added to 1
Decomposition polymerization was carried out at 55 ° C. for 60 to obtain 50 g of carboxyalkyl nitrocellulose.

[0025]

Example 5 150 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.7) and sulfuric acid /
3 liters of acid mixture consisting of nitric acid / water = 66.8 / 27.7 / 5.5% by weight (acid / raw material = 1/30) was put into a 5 liter reaction vessel, and stirred at 12 ° C. for 60 minutes. Deoxidize the product with a centrifuge, immediately wash with plenty of water, and
65 g of reaction product was obtained.

As a result of measurement in the same manner as in Example 1, the reaction product obtained had a degree of substitution with a nitrate ester group of 1.8 per one anhydrous glucose group and a degree of substitution with a carboxymethyl ether group of 0.7. It was 100 g of the obtained product was added to 1
45 decomposition polymerization was carried out at 40 ° C. to obtain 90 g of carboxyalkyl nitrocellulose.

[0027]

Example 6 150 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.7) and sulfuric acid /
3 liters of a mixture of nitric acid / water = 58.1 / 19.2 / 22.7% by weight (raw material / acid = 1/30) was placed in a 5 liter reaction vessel, and stirred at 21 ° C. for 60 minutes, The product was deoxidized with a centrifuge and immediately washed with a large amount of water.
3 g of reaction product was obtained.

As a result of measurement in the same manner as in Example 1, the reaction product obtained had a degree of substitution of nitrate ester groups of 1.1 and a degree of substitution of carboxymethyl ether groups of 0.7 per anhydrous glucose group. It was

[0029]

Example 7 300 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.7) and sulfuric acid /
3 liters of a mixture consisting of nitric acid / water = 58.1 / 19.2 / 22.7% by weight (raw material / acid = 1/10) was placed in a 5 liter reaction vessel and stirred at 5 ° C. for 60 minutes, The product is deoxidized with a centrifuge and immediately washed with a large amount of water.
4 g of reaction product was obtained.

As a result of measurement in the same manner as in Example 1, the reaction product obtained had a degree of substitution with a nitrate ester group of 0.5 and a degree of substitution with a carboxymethyl ether group of 0.7 per anhydrous glucose group. It was

[0031]

Example 8 100 g of carboxymethyl cellulose (carboxymethyl ether group substitution degree = 0.7) and nitric acid /
3.5 liter of a mixture of water = 98.0 / 2.0% by weight (raw material / acid = 1/50) was put into a 5 liter reaction vessel, stirred at 30 ° C. for 60 minutes, and the reaction solution was added to 20 liters. Add to liter of water and stir. The obtained product was dewatered with a centrifuge and washed with a large amount of water to obtain 130 g of a reaction product.

As a result of measurement in the same manner as in Example 1, the reaction product obtained had a degree of substitution of nitrate ester groups of 2.1 and a degree of substitution of carboxymethyl ether groups of 0.7 per anhydrous glucose group. It was

[0033]

INDUSTRIAL APPLICABILITY According to the method for producing an aqueous cellulose derivative of the present invention, the yield of the reaction product is high and the raw material cellulose derivative undergoes a uniform nitrification reaction. Therefore, the obtained aqueous cellulose derivative is soluble in water. It is also high and exhibits extremely excellent pigment dispersibility, drying property, and heat resistance.

Therefore, the derivative obtained by the production method of the present invention is extremely useful as a vehicle or an additive for an aqueous coating agent such as an aqueous coating material, an aqueous ink and an aqueous paper coating agent. It can greatly contribute to performance improvement.

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Claims (2)

(57) [Claims] 1. Anhydroglucose group obtained by nitrifying a carboxyalkyl ether cellulose having a degree of carboxyalkyl ether group substitution per anhydroglucose group of 0.05 or more with a mixed acid of nitric acid / water / sulfuric acid. A method for producing an aqueous cellulose derivative having a degree of substitution of nitrate ester groups of 0.2 or more and a degree of substitution of carboxyalkyl ether groups of 0.05 or more, wherein the mixed acid composition ratio of nitric acid / water / sulfuric acid is nitric acid. 1% by weight or more, 99
% By weight, water content 1% by weight or more, 30% by weight or less, sulfuric acid amount 1% by weight or more, 90% by weight or less, and the ratio of carboxyalkyl ether cellulose and mixed acid is 1 / by weight.
The method for producing an aqueous cellulose derivative, wherein the nitrification reaction temperature is 2 to 1/300, and the nitrification reaction temperature is -20 ° C to 21 ° C. 2. Anhydroglucose group 1 is obtained by nitrifying a carboxyalkyl ether cellulose having a degree of carboxyalkyl ether group substitution per anhydroglucose group of 0.05 or more with a dilute acid consisting of nitric acid / water. A method for producing an aqueous cellulose derivative, wherein the degree of substitution of nitric acid ester group is 0.2 or more and the degree of substitution of carboxyalkyl ether group is 0.05 or more, and the composition ratio of dilute nitric acid / water is 1 nitric acid. % By weight or more and 99% by weight or less, water content is 1% by weight or more and 30% by weight or less, the ratio of carboxyalkyl ether cellulose to the acid is 1/2 to 1/300 by weight, and the nitrification reaction temperature is 30. The method for producing an aqueous cellulose derivative is characterized in that the temperature is 0 ° C.