JPH07330801A - Aqueous cellulosic derivative and its production - Google Patents

Abstract

PURPOSE:To obtain a cellulosic derivative which has specific average substitution degrees of nitrate and carboxymethyl ether groups as well as a haze value lower than a certain level, thus is excellent in transparency, solubility and compatibility with a variety of resins. CONSTITUTION:This derivative is an aqueous cellulose derivative having 0.4-2.2 nitrate substitution degree and 0.2-1.5 carboxymethyl ether substitution degree and showing less than 30% haze value in its solution. A sodium carboxymethylcellulose having 0.2-1.5 carboxymethyl ether substitution degree (Ds) and an electrophoretic mobiliity distribution (DELTAU) represented by the expression: DELTAU X10<56cm<2>/sec.V, is nitrated to give this cellulosic derivative. The reaction is carried out using 2-300 pts., preferably 10-100 pts. of a mixed acid for nitration per 1 pts. of sodium carboxymethylcullose at -20-+30 deg.C. The cellculosic derivative holds the characteristics of the nitrocellulose (for example, drying properties and hardness).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous cellulose derivative and a method for producing the same. In recent years, in the fields of paints, inks, paper coats, etc., the change to water-based materials is progressing due to problems such as environmental protection, protection of workers and danger of fire. The present invention provides a water-based cellulose derivative that can be used as a water-based binder, a coating agent as a coating agent, a printing ink, a paper coating, a fiber processing and a functional coating such as a magnetic paint and a conductive paste, and a method for producing the same.

[0002]

Conventionally, as a water-based cellulose derivative, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and the like have been used as thickeners for aqueous coating agents. However, these are limited in their use due to insufficient compatibility with various resins for aqueous coating agents, and also because the pigment dispersibility is extremely insufficient,
It is rarely used as a pigment dispersant. For the purpose of improving this, an aqueous cellulose derivative having a nitrate ester group and a carboxyalkyl ether group has been proposed.
For example, JP-A-5-39301 and JP-A-5-393.
No. 02, JP-A-5-194912 hold the dryness, hardness, blocking resistance, and thickening property of nitrocellulose, which is conventionally mainly used in an organic solvent system,
Moreover, an aqueous cellulose derivative having excellent pigment dispersibility has been proposed. However, these inventions are insufficient in performance such as transparency and solubility as a cellulose derivative solution that affects the appearance of the product as a coating agent and compatibility with various resins for water-based coating agents, which are improved. Was desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides water and a mixed solvent of water and an organic solvent which retains the drying property, hardness, blocking resistance and thickening property of nitrocellulose and is excellent in pigment dispersibility. And a water-based cellulose derivative soluble in water. Furthermore, it is an object of the present invention to provide a water-based cellulose derivative having excellent transparency and solubility as a cellulose derivative solution that affects the appearance of a product as a coating agent and compatibility with various water-based coating agent resins, and a method for producing the same. It is a thing.

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventors have found that the nitrate ester group and carboxymethyl ether group of an aqueous cellulose derivative have a specific average degree of substitution, and the haze value of the solution is It is important that the content is 30% or less and that the degree of substitution of carboxymethyl ether groups of carboxymethyl cellulose sodium salt (hereinafter abbreviated as CMC), which is a raw material of the water-based cellulose derivative, is uniform in the production method. Heading The present invention has been completed.

That is, according to the present invention, the degree of substitution of nitrate ester group per anhydrous glucose residue is 0.4 to 2.2, the degree of substitution of carboxymethyl ether group is 0.2 to 1.5, and It proposes a water-based cellulose derivative having a haze value of 30% or less. Furthermore, the carboxymethyl ether group substitution degree (Ds) is 0.2 to 1.5, and the mobility distribution (ΔU) by the electrophoresis method is ΔU ×
The present invention proposes a method for producing the above-mentioned water-based cellulose derivative, which comprises nitrifying a cellulose sodium salt represented by 10 ⁵ <6 cm ² / sec · v.

When the degree of substitution x of the nitrate ester group is less than 0.4, the compatibility with the aqueous synthetic resin and the pigment dispersibility are insufficient,
When x exceeds 2.2, a large amount of organic solvent is required to dissolve or disperse in a mixed solvent of water and an organic solvent.
If the carboxymethyl ether group substitution degree y is less than 0.2, the solubility or dispersibility in a mixed solvent of water and the minimum amount of organic solvent is insufficient, and if y exceeds 1.5, the water resistance of the film is Sex becomes insufficient. The degree of substitution with the nitrate ester group can be controlled by the production conditions during esterification.

The aqueous cellulose derivative of the present invention is represented by the following general formula. [GLU. (ONO ₂ ) _x (OCH ₂ COOH) _y (OH)
_z ] _n (where GLU. is a glucose residue, 0.4 ≦ x ≦
2.2, 0.2 ≦ y ≦ 1.5, x + y <3, x + y + z
= 3, n is preferably an integer of 20 or more and 1000 or less) Here, the haze value of the solution means a solution when the aqueous cellulose derivative is neutralized and dissolved in water or a mixed solvent of water and an organic solvent. It represents the haze value, that is, the degree of transparency, and its measuring method will be described in detail in Examples. The solution haze value of the present invention is required to be 30% or less, and when it exceeds 30%, when it is used as a coating agent in paints, fine knurls are generated on the surface and gloss is lowered, resulting in a remarkable commercial value. descend. The haze value is preferably 20% or less, more preferably 10% or less. The lower limit of the haze value is not particularly limited, but is preferably 1% or more from the viewpoint of ease of production. It should be noted that the haze value of 30% or less can be achieved by adjusting the raw material and the conditions for nitric acid esterification.

Next, a method for producing the aqueous cellulose derivative of the present invention will be described. The method for producing the aqueous cellulose derivative of the present invention comprises the step of nitric esterification using CMC having a specific carboxymethyl ether group substitution degree and its substitution degree distribution as a raw material. That is, in the method for producing an aqueous cellulose derivative of the present invention, the degree of carboxymethyl ether group substitution (Ds) is 0.2 to 1.5, and the mobility distribution (ΔU) by electrophoresis is ΔU × 10 ⁵ <.
It is necessary to esterify CMC represented by 6 cm ² / sec · v with nitrate. In this case, the substitution degree of the carboxymethyl ether group of the raw material CMC is preferably 0.4 to
1.2.

It is well known that the substitution degree distribution of a polyelectrolyte such as CMC is represented by a mobility distribution obtained by electrophoresis. For example, Polymer Journal Vol. 8 No. 44
9-455 (1976), Terashima et al., Show that the CMC substitution degree distribution can be measured by electrophoresis. In the present invention, the substitution degree distribution measurement by the electrophoresis method is carried out at 25 ± 0.1 ° C. by using the Tizerius electrophoresis apparatus HTB-2A (Schlieren optical system). Sample concentration 0.2 g / 100 ml solvent 0.1 N NaCl aqueous solution electrophoretic current 2 mA The mobility U when electrophoresis is performed under the above measurement conditions is shown by the following formula. U = (K · A / i) · (h / t) K: specific electric conductivity of solvent 1.067 × 10 ⁻² Ω ⁻¹ cm ⁻¹ A: cell cross-sectional area 0.300 cm ² i: migration current 0 0.002A h: migration distance (cm) t: migration time (sec)

As for the mobility U, when the movement at the rising interface is measured every time and plotted on the reciprocal of the time on the horizontal axis, the extrapolation point of the maximum mobility of time infinity and the minimum mobility of time infinity are obtained. The difference between the extrapolated points of is the mobility distribution. That is, the mobility distribution (ΔU) represents the difference between the highest substitution degree and the lowest substitution degree of CMC, that is, the uniformity of the substitution degree distribution. Formula (1) shows the upper limit of the mobility distribution. ΔU × 10 ⁵ in the present invention needs to be 6 or less, preferably 5 or less, and more preferably 4 or less. When this value exceeds 6, the transparency and solubility of the cellulose derivative solution and the compatibility with various water-based coating agent resins decrease.
Further, the yield at the time of producing the cellulose derivative of the present invention decreases. The lower limit of the value of ΔU × 10 ⁵ is not particularly limited, but is preferably 1 or more from the viewpoint of ease of manufacturing.

Next, the CMC is produced by treating it with a known nitric acid for esterification, for example, nitric acid, sulfuric acid / nitric acid, acetic acid / nitric acid, phosphoric acid / nitric acid or a nitric acid esterifying acid consisting of these and water. Practically and economically, these acids are recycled and reused. The above-mentioned degree of substitution of the nitrate ester group can be controlled especially by changing the composition ratio of sulfuric acid / nitric acid / water.

In the method for producing an aqueous cellulose derivative of the present invention, the ratio of the raw material CMC to the nitric acid-mixing mixed acid is 2 to 300 of the mixed acid with respect to CMC1 by weight. Mixed acid is 2
If it is less than 300, it is difficult to remove the heat of reaction, and if it exceeds 300, the amount of acid to be recovered is too large, which is economically disadvantageous. The preferred range is 10-100. The temperature of the nitrification reaction in the method for producing an aqueous cellulose derivative of the present invention is -20 to 20.
30 ° C. is preferred. If the temperature is lower than -20 ° C, a large amount of cost is required for cooling, and if the temperature exceeds 30 ° C, the yield of the obtained aqueous cellulose derivative of the present invention is lowered. A more preferable range is -10 to 20 ° C.

Further, in the method for producing an aqueous cellulose derivative of the present invention, the molecular weight can be adjusted as necessary. Generally, the nitrification reaction product is 40-170.
There is a method of performing thermal depolymerization at ℃. Further, a method of performing depolymerization within the above temperature range by adding an oxidizing agent or the like can also be adopted.

When the aqueous cellulose derivative of the present invention is used as an aqueous coating agent or the like, it is necessary to neutralize the carboxyl group. For neutralization, one or more cations such as alkali metal ions, alkaline earth metal ions, ammonium ions and organic amines can be used. In this case, the degree of neutralization is arbitrarily determined according to the composition of the target solution such as water and organic solvent, but generally 50% or more of the contained carboxyl groups are neutralized. It is preferable. In this case, the contained carboxyl group is ammonium ion or has a boiling point of 1.
It is preferably neutralized with one kind or a combination of two or more kinds of organic amines having a temperature of 00 ° C. or lower. When the carboxyl group is neutralized with an alkali metal ion or an organic amine having a boiling point of 100 ° C. or higher, insolubilization in water by heating and drying cannot be expected, and it is necessary to add a crosslinking agent for insolubilization. When the water-based cellulose derivative of the present invention is used as a water-based coating agent, it is preferably contained in an amount of 1 to 35% based on the total weight of the water-based coating agent.

As the water-soluble resin and water-dispersible resin to be combined with the water-based cellulose derivative of the present invention, any of those used in water-based paints, water-based inks and the like can be used. For example, water-soluble alkyd resin, acrylated alkyd resin, polyamide resin, polyurethane resin, polyester resin, styrene-maleic acid resin, acrylic ester resin, polyvinyl alcohol, shellac, casein, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc. Synthetic resins and combinations of these can be used.

Further, emulsion latex described in "Emulsion / Latex Handbook", page 24, Table 2-3 (published by Taisei Co., Ltd.), for example, styrene / butadiene type polymer, acrylonitrile / butadiene type polymer, methyl methacrylate / butadiene type. Polymer, polychloroprene, vinyl pyridine copolymer, polyisoprene, butyl rubber, polysulfide rubber, polyurethane, polybutene, polyacrylate, vinyl chloride polymer, vinyl acetate polymer, vinylidene chloride copolymer, polyethylene, vinyl acetate・ Emulsion latex such as ethylene copolymers or emulsion or colloid of synthetic resin such as alkyd resin, acrylated alkyd resin, epoxidized alkyd resin, polyester resin, styrene-acrylic resin, epoxy resin, fluororesin There is Rudy Spurgeon like, may be used in combination. Furthermore, depending on the intended use of the water-based coating agent, pigment, magnetic powder,
It may contain a heat stabilizer, an ultraviolet absorber, a light stabilizer, a surfactant, a cross-linking agent and the like.

[0017]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The raw material CMC used in the examples of the present invention and the method for measuring the haze value are shown below. <Raw material CMC> Raw material a: carboxymethyl ether group substitution degree (Ds) =
0.65 ΔU × 10 ⁵ = 3.4 Raw material b: Carboxymethyl ether group substitution degree (Ds) =
1.05 ΔU × 10 ⁵ = 2.6.

<Measurement Method of Haze Value> A mixed solution of water: butyl cellosolve = 70: 30 weight ratio is added to the water-based cellulose derivative so that the solid content is 10% by weight.
Further, 10% ammonia water is added so that the degree of neutralization becomes 1.0, and the mixture is heated to 50 ° C. with stirring in a hermetically sealed glass container to dissolve it. After the dissolution, the haze value is measured by allowing it to reach room temperature. The measuring device is a direct-reading haze computer (HGM-2D manufactured by Suga Test Instruments Co., Ltd.)
P) was used for measurement in a quartz cell having a cell thickness of 1 cm.

[0019]

Example 1 100 g of raw material a (Ds = 0.65) and 5000 g of an acid mixture consisting of sulfuric acid / nitric acid / water = 63/25/12% by weight were put in a reaction vessel of 5 liter, and 5-1
The nitrification reaction is carried out while continuing stirring at 0 ° C for 60 minutes. The reaction product is deoxidized with a centrifuge and immediately washed with a large amount of water.

Further, the reaction product was subjected to 1 in an autoclave.
A 0 wt% water slurry was prepared, treated at 140 ° C. for 30 minutes, and then separated with a Buchner funnel to collect a reaction product.
The reaction product was dried at 80 ° C. for 2 hours to obtain 129 g of carboxymethyl cellulose nitrate ester. The substitution degree of nitrate ester of carboxymethyl cellulose, which is an aqueous cellulose derivative, was measured by the following method.

0.1 g of the dried reaction product was precisely weighed and the weight% of nitrogen atomic weight (hereinafter referred to as N%) was determined by elemental analysis. Precisely weigh 1 g of the dried reaction product and put it in a 300 ml Erlenmeyer flask with a ground stopper.
15 ml of% methanol was added, 100 ml of N / 10 sodium hydroxide solution was accurately added, the mixture was shaken at room temperature for 3 hours, phenolphthalein was added, and the mixture was titrated with N / 10 sulfuric acid. The equivalent amount of carboxymethyl ether group per 1 g of the sample (hereinafter referred to as A equivalent / g) was calculated by the following formula.

A = (100−N / 10 sulfuric acid ml) × f × 10 ⁻⁴ where f: N / 10 sulfuric acid factor The obtained N% and A equivalent / g are used to give an anhydrous product according to the following equation. The degree of nitrate ester group substitution, the degree of carboxymethyl ether group substitution, and the number of residual hydroxyl groups per glucose residue were calculated. x = 162n / (14-45n-58 * 14A) y = 14xA / n z = 3- (x + y) Here, x: Nitric acid ester group substitution degree y: Carboxymethyl ether group substitution degree z: Residual hydroxyl group n: (N %) / 100 As a result of measurement by the above method, the obtained nitrification reaction product had a nitrate ester group substitution degree of 1.93 and a carboxymethyl ether group substitution degree of 0.66 per anhydrous glucose residue. (Hereinafter, referred to as water-based cellulose derivative A). The yield calculated based on the measured substitution degree was 90% of the theoretical value. The haze value of the aqueous cellulose derivative A solution was 7%.

[0023]

Example 2 Using the raw material b (Ds = 1.05), the same procedure as in Example 1 was carried out except that the treatment was carried out at 130 ° C. for 30 minutes in an autoclave, to obtain 90 g of dried nitrate ester of carboxymethyl cellulose. It was The nitrification reaction product obtained had a degree of substitution with a nitrate ester group of 0.86 and a degree of substitution with a carboxymethyl ether group of 1.04 per anhydrous glucose residue (hereinafter, referred to as an aqueous cellulose derivative B.
And). The yield calculated based on the measured substitution degree was 87% of the theoretical value. In addition, the water-based cellulose derivative B
The haze value of the solution was 9%.

[0024]

Comparative Example 1 Carboxymethyl ether group substitution degree (D
Using a commercially available CMC having s) of 0.70 and ΔU × 10 ⁵ = 6.5, nitric acid esterification was performed under the same conditions as in Example 1. The nitric acid reaction product had a nitrate ester group substitution degree of 1.8 and a carboxymethyl ether group substitution degree of 0.70 per anhydrous glucose residue. The yield calculated based on the measured substitution degree was 71% of the theoretical value. The haze value of the cellulose derivative solution was measured and found to be 42%.

[0025]

Industrial Applicability The water-based cellulose derivative of the present invention has a specific carboxymethyl ester group and a nitrate ester group, has a uniform degree of substitution distribution, and is a mixed system of water and water and a minimum necessary amount of an organic solvent. Can be used. It retains the characteristics of nitrocellulose such as drying property, hardness, blocking resistance, thickening property, and pigment dispersibility. Furthermore, since the substitution degree distribution is uniform, it is an aqueous binder, a coating agent as a coating agent, a printing agent. When used in inks, paper coatings, fiber processing and functional coatings such as magnetic paints and conductive pastes, it exhibits excellent effects in transparency, solubility and compatibility with various resins for water-based coating agents. Further, in the production of the water-based cellulose derivative, the use of the raw material CMC having a uniform substitution degree distribution has the effect of increasing the yield.

Claims (2)

[Claims] 1. A nitrate ester group substitution degree per anhydrous glucose residue is 0.4 to 2.2, a carboxymethyl ether group substitution degree is 0.2 to 1.5, and a haze of the solution. A water-based cellulose derivative having a value of 30% or less. 2. The degree of carboxymethyl ether group substitution (D
s) is 0.2 to 1.5 and the mobility distribution (ΔU) according to the electrophoretic method is a nitric acid esterification of sodium carboxymethyl cellulose represented by the following formula (1), Method for producing derivative. ΔU × 10 ⁵ <6 cm ² / sec · v Equation (1)