JPH03210301A - Production of alkali metal salt of carboxymethylcellulose ether - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing carboxymethyl cellulose ether alkali metal salt (hereinafter also referred to as CMC). More specifically, the present invention relates to a method for producing CMC which is excellent in various properties, has a high degree of carboxymethyl substitution (hereinafter also referred to as DS), and has a high viscosity.

[Prior art] As a recently disclosed method for manufacturing CMC, for example,
Examples include methods described in Japanese Patent Publication No. 8-45201, Japanese Patent Application Laid-Open No. 157501/1982, and Japanese Patent Publication No. Ei3-55523.

In the method described in JP-A-58-45201, when CMC is produced in a water-containing organic solvent, the amount of alkali after subtracting the amount of alkali used for neutralizing the etherification agent is equal to 1 mole of the etherification agent. The etherification reaction is carried out in a system with an excess of etherification agent such that the amount is 0.10 to 0.99 mol, and then 0.90 to 0.01 mol or more of the remaining alkali is added in portions to react. This is a method for producing CMC having a uniform substituent distribution by increasing the blind utilization rate of the etherifying agent, and products with a DS of 0.95 to 1.89 have been produced.

Furthermore, in the method described in JP-A-81-1!1701, when CMC is produced in a water-containing organic solvent, epichlorohydrin is further reacted to produce a DSO of 85 to 1.51.
This is a method for producing high viscosity CMC with excellent salt water resistance. Instead of cellulose, DSf, 54 C) Ic is used and DS2.55 CMC is produced by Ilco.

Furthermore, the method described in Japanese Patent Publication No. Sho H-55523 is
This is a method for producing CMC with a uniform DS by neutralizing a portion of the etherifying agent with alkali hydroxide before adding the etherifying agent when producing CMC in a water-containing organic solvent.

[Problems to be Solved by the Invention] However, what can be obtained by such a conventional method for producing CMC from cellulose through a one-stage reaction is DS1.
89 or so at most, which is the DS 2 that the market demands.
．． It is impossible to produce a high viscosity CMC with a DS of 2.0 or higher. Since it is necessary to perform a second stage etherification reaction as a raw material, productivity is low and manufacturing costs are high.
As an industrial manufacturing method, there are many problems.

Therefore, an object of the present invention is to provide an industrial method for producing high DS and high viscosity CMC at low cost by a one-stage reaction.

[Means for Solving the Problems] That is, in producing carboxymethyl cellulose ether alkali metal salt by etherifying a cellulosic raw material in a water-containing organic solvent, the present invention involves converting (1) a cellulosic raw material into (2) a monochloro After mixing with a water-containing organic solvent solution of an alkali metal salt of monochloroacetic acid prepared by adding an equimolar amount of alkali hydroxide to monochloroacetic acid, 2 to 5.55 moles of alkali hydroxide per single mole of glucose is added as a solid. The present invention relates to a method for producing carboxymethyl cellulose ether alkali metal salt, which is characterized in that the carboxymethyl cellulose ether alkali metal salt is added in the state and etherified.

[Function] Alkali cellulose in the CMC manufacturing method is produced by adding alkali hydroxide to cellulosic raw material in a water-containing organic solvent. The generated alkali cellulose is unstable in water, and the amount of alkali hydroxide adsorbed on the cellulosic raw material is also related to the reactivity with the etherification agent, so from the point of view of etherification, it is necessary to use a large amount of alkali hydroxide. It is preferable to increase the amount of adsorption. However, in the presence of a large amount of alkali hydroxide, cellulose depolymerization is promoted,
Furthermore, hydrolysis of the etherification agent is also promoted, increasing side reactions.

In order to reduce such problems, in the present invention, the etherification agent is neutralized with an equimolar amount of alkali hydroxide in a water-containing organic solvent, and the etherification agent is added in the form of an alkali metal salt in the water-containing organic solvent from which the heat of neutralization has been removed. The existing etherification agent is uniformly mixed with the cellulosic raw material, and the alkali hydroxide necessary for the etherification reaction is added in solid form to produce alkali cellulose.
An etherification reaction is also carried out at the same time. At this time, the added solid alkali hydroxide is dissolved and etherified while being alcelized and consumed, thereby suppressing the decomposition of the cellulosic raw material and the etherification agent.

[Example] In the present invention, a cellulosic raw material is prepared using an alkali metal salt of monochloroacetic acid (hereinafter also referred to as a specific etherification agent) prepared by adding an equimolar amount of alkali hydroxide to monochloroacetic acid in a water-containing organic solvent. is etherified and CMC
is manufactured.

The cellulosic raw material is not particularly limited, and may be any material obtained by pulverizing pulp such as linter pulp or wood pulp, which is normally used in the production of CMC.

As the above-mentioned water-organic solvent, any one can be used without particular limitation as long as it is commonly used in the production of CMC to etherify the cellulosic raw material. Specific examples of such water-containing organic solvents include lower alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol (IPA), butyl alcohols, aromatic hydrocarbons such as benzene and toluene, acetone, and ethyl methyl. Ketones such as ketones, ethers such as ethylene glycol dimethyl ether, etc. At least IN selected from alcohols and aromatic hydrocarbons, methanol and (
or) a mixture of ethanol and water is preferred.

Further, the composition of this water-containing organic solvent is preferably such that the weight ratio of organic solvent/water is 70/30 to 90/to. If the ratio of organic solvent/water in the water-containing organic solvent is less than 70/30, the effective utilization rate (AM) of the etherification agent tends to decrease significantly, and if it exceeds 90/lO, the etherification reaction becomes uneven. Easy to use, especially IPA,
A water-containing organic solvent consisting of three components of methyl alcohol and water is preferred, with IPA 50-70% (wt%, same hereinafter), methyl alcohol 15-25% and water 15-2
A water-containing organic solvent containing 5% is preferably used because the effective utilization rate of the etherifying agent is high and the product viscosity and stability of the product aqueous solution are good.

The alkali metal salt of monochloroacetic acid, which is the specific etherification agent, is prepared by mixing 1 mole of alkali hydroxide to 1 mole of monochloroacetic acid, and is substantially free of monochloroacetic acid and alkali hydroxide. If the amount of alkali hydroxide used per mole of monochloroacetic acid exceeds 1 mole, the residual alkali hydroxide will accelerate the side decomposition of monochloroacetic acid, so the neutralization reaction of monochloroacetic acid with alkali hydroxide will be less than 1 mole per mole of monochloroacetic acid. It is preferable to do so.

The above-mentioned specific etherification agent can be added by dissolving alkali hydroxide in the above-mentioned water-containing organic solvent and adding it to a solution of monochloroacetic acid in the water-containing organic solvent while removing the heat of neutralization. It is prepared by

When monochloroacetic acid solution is added to alkaline hydroxide solution to neutralize it, side reactions of the etherification agent are promoted due to excess alkali hydroxide during the neutralization process, resulting in effective utilization of the etherification agent in the etherification reaction of CMC. decreases.

The temperature at which the two liquids are mixed is preferably a temperature at which monochloroacetic acid does not hydrolyze or becomes close to the boiling point of the organic solvent used and becomes easily diffused, and is preferably below 50°C. It is preferable to carry out the neutralization while removing the heat of neutralization.

When a mixed solvent consisting of 50 to 70% IPA, 15 to 25% methyl alcohol, and 15 to 25% water as described above is used as a water-containing organic solvent containing a specific etherification agent, alkali hydroxide does not dissolve in IPA, but Since 19% by weight of alkali hydroxide is dissolved in methyl alcohol, the amount of alkali hydroxide dissolved can be increased while reducing the amount of water in the solvent.

The specific etherification agent prepared in the aqueous organic solvent is then mixed with the cellulosic raw material.

The specific etherification agent and the cellulosic raw material are mixed by charging the cellulosic raw material, for example, into a reactor equipped with two stirring blades, and adding the specific ether north side-containing liquid to the reactor at once. The method is not limited. Further, if necessary, a water-containing organic solvent may be added at a necessary stage.

The liquid temperature of the specific ether north side containing liquid during the mixing is 2
It is preferable to maintain the temperature at about 5 to 30°C.

The ratio of the specific etherification agent to the cellulosic raw material varies depending on the desired DS, but is usually 2.0 to 5.0% per mole of glucose constituting the cellulose.
It is 5 moles.

Note that the single position mole of glucose that constitutes cellulose refers to the unit of co HID os that basically constitutes cellulose.

In addition, the amount of water-containing organic solvent relative to the cellulosic raw material varies depending on the target DS and product viscosity, and although it cannot be generally specified, it is usually about 3.5 to 10 times the amount of water-containing organic solvent to the weight of the cellulosic raw material. is used.

After the specific ether north-containing solution is added to the cellulosic feedstock and stirred for 10-30 minutes, the alkali hydroxide required for the etherification reaction is 2.5% per mole of glucose per single positional mole of glucose. OO
~5.55 mol is added as a solid.

Alkali hydroxide is added under strict conditions in which it remains solid, but since it is added after thoroughly mixing the specific etherification agent and the cellulosic raw material, the alkaline reaction and etherification reaction occur in a water-containing organic solvent. occurs at the same time, and the desired high DS and high viscosity CMC can be easily changed.

As the alkali hydroxide, sodium hydroxide, potassium hydroxide, etc. can be used, but sodium hydroxide is preferred for economical reasons.

The CMC obtained by the method of the present invention as described above has a DS of 1
．． 3 to 2.80, and the viscosity varies slightly depending on the DS, etc., but it is possible to have an apparent viscosity of about 300 to 17,000 P even if it contains an anhydride at a concentration of 2%.

Next, the manufacturing method of the present invention will be explained in more detail using Examples, but the present invention is not limited to these Examples.

Example 1 (Preparation of specific etherification agent) IPA 735 parts (weight parts, the same applies hereinafter), methanol 1
Part IH of sodium hydroxide was dissolved in a mixed water-containing organic solvent of 89 parts and 128 parts of water, and the solution was cooled to a temperature of 35° C. (the resulting solution was referred to as Solution A).

Meanwhile, 152 parts of IPA, 39 parts of methanol and 2 parts of water
A solution was prepared by dissolving 326 parts of monochloroacetic acid in 6 parts of the above solution (the resulting solution is referred to as Solution B).

A specific etherification agent was prepared by dropping Solution A into the obtained Solution B while cooling the solution to maintain the temperature at 48° C. or below.

(Synthesis of CMC) 300 parts of coarsely crushed linter pulp was charged into a 5 g reactor equipped with a twin-shaft stirring blade, and the entire amount of the specific etherification agent obtained was added under a N2 gas atmosphere, and the mixture was heated at 30°C for 30 minutes. After mixing, 140 parts of sodium hydroxide necessary for the etherification reaction was added while cooling to maintain the temperature below 45° C. and mixed for 30 minutes. Thereafter, the mixture was heated and the temperature was raised to allow a reaction to take place at the boiling point of 78° C. for 70 minutes.

After the reaction is completed, the reaction product is neutralized with acetic acid, the reaction solvent is separated, and then purified with 75% methanol, dried and pulverized to obtain CMC.
I got (product).

The physical properties of the obtained CMC are DS, viscosity of 2% liquid, 2
The transparency of the % liquid was measured by the following method.

The results are shown in Table 1 along with the reaction rate.

(a) DS (degree of substitution) CMC (anhydride) Ig was accurately weighed, placed in a porcelain crucible, and
Ash at 60 to 600°C, add an excess amount of O, 1N sulfuric acid aqueous solution to the sodium oxide produced by the ashing, and add 0.0% excess sulfuric acid using phenolphthalein as an indicator. , perform back titration with a 1N potassium hydroxide aqueous solution, and calculate DS from the following formula.

os-w 1B2X (B-A) floooo-8
0X (B-A)f (where A is the titration amount of 0.1N potassium hydroxide aqueous solution (
ml), B is blank, r is 0. The titration m (ml) of IN potassium hydroxide aqueous solution is shown. ) φ) Viscosity CMC (anhydrous) 2.2g was accurately weighed, and the inner diameter was 5511.
The solution was dissolved in pure water to a 2% solution in a container with a depth of 115 mm, and rotated for 3 minutes at a rotation speed of tiOrpm using a BM type viscometer in a constant temperature water bath at 25 ± 0.2 °C. Find the viscosity of

(C) Transparency Transparency is the transparency of a 2% CMC liquid under a constant light source expressed in terms of the height of the liquid column. This method is commonly used in the art, and if the reaction is non-uniform, the transparency will decrease due to unreacted cellulose, undissolved portions, swollen gel bodies, etc., and the transparency value will become small. Therefore, the higher the uniformity of the reaction, the higher the solution clarity.

(Small reaction rate Reaction rate - Concave - x 100 MCA DS = Degree of substitution MCA: Number of moles of monochloroacetic acid per mole of glucose at a single position Example 2 (Preparation of a specific etherification agent) 945 parts of IPA, 243 parts of methanol and water 162
Solution A was prepared by dissolving 207 parts of sodium hydroxide in 1 part of a mixed water-containing organic solvent and cooling the solution to a temperature of 35°C.

Meanwhile, 228 parts of IPA, 58 parts of methanol and 3 parts of water
Solution B was prepared by dissolving 489 parts of monochloroacetic acid in 9 parts.

A specific etherification agent was prepared by dropping Solution A into the obtained Solution B while cooling the solution to maintain the temperature at 48° C. or below.

(Synthesis of CMC) In the same manner as in Example 1, 300 parts of coarsely crushed linter pulp was charged into a 5 g reactor equipped with a twin-shaft stirring blade, the entire amount of the obtained specific etherification agent was added, and the mixture was heated at 30°C for 30 minutes. After mixing for a minute, add the sodium hydroxide 2 necessary for the etherification reaction.
0.09 parts as a solid was cooled and added to maintain the temperature below 45°C, mixed for 30 minutes, heated and heated to a boiling point of 7.
The reaction was carried out at 8°C for 70 minutes.

After the reaction was completed, CMC (product) was obtained by neutralization, purification, drying, and pulverization in the same manner as in Example 1, and its physical properties were evaluated. The results are shown in Table 1 along with the reaction rate.

Example 3 (Preparation of specific etherification agent) Solution A was prepared by dissolving 184 parts of sodium hydroxide in 910 parts of IPA, 234 parts of methanol, and 156 parts of water.

On the other hand, a solution B was prepared by dissolving 434 parts of monochloroacetic acid in 202 parts of IPA, 52 parts of methanol, and 35 parts of water.

A specific etherification agent was prepared by dropping Solution A into the obtained Solution B.

(Synthesis of CMC) Add the entire amount of the specific etherification agent obtained to 200 parts of coarsely crushed linter pulp, mix for 30 minutes, and then add 186 parts of sodium hydroxide, which is necessary for the etherification reaction, as a solid at a temperature below 45°C. The mixture was cooled and added to maintain the same temperature, and the mixture was mixed for 30 minutes.Then, the mixture was heated and the temperature was raised to react for 70 minutes at the boiling point of 78°C.

After the reaction is completed, CMC (product) is prepared in the same manner as in Example 1.
The physical properties were evaluated. The results are shown in Table 1 along with the reaction rate.

Example 4 (Preparation of specific etherification agent) Solution A was prepared by dissolving 230 parts of sodium hydroxide in 1050 parts of IPA, 270 parts of methanol, and 180 parts of water.

On the other hand, Solution B was prepared by dissolving 543 parts of monochloroacetic acid in 253 parts of IPA, 65 parts of methanol, and 43 parts of water.

A specific etherification agent was prepared by adding Solution A to the obtained Solution B.

(Synthesis of CMC) After adding the entire amount of the specific etherification agent obtained to 200 parts of coarsely crushed linter pulp and mixing for 30 minutes, 231 parts of sodium hydroxide necessary for the etherification reaction was added as a solid at a temperature below 45°C. The mixture was cooled and added to maintain the temperature of
Allowed to react for minutes.

After the reaction is completed, CMC (product) is prepared in the same manner as in Example 1.
The physical properties were evaluated. The results are shown in Table 1 along with the reaction rate.

[Left below] [Effects of the invention] In order to produce C14C with a high DS using the conventional CMC production method, it is possible to first prepare alkali cellulose from cellulose and alkali hydroxide, and then add an etherification agent, or Since the method involves further etherification of CMC, the former method tends to cause depolymerization of cellulose by alkali hydroxide and side reactions of the etherification agent.
It is difficult to produce CMC with high DS and high viscosity, and on the other hand, when CMC is further etherified using the latter method, productivity is significantly reduced, which is a big problem both industrially and economically. .

In the method of the present invention, an alkali metal salt of monochloroacetic acid is prepared by adding an equimolar amount of alkali hydroxide to monochloroacetic acid, and the alkali metal salt of monochloroacetic acid is further added in a solid state, which is different from the conventional method for preparing alkali cellulose. It is possible to prevent depolymerization and side reactions caused by alkali hydroxide in the process and the ether north side dropping process, and it is possible to industrially produce CMC with high DS and high viscosity easily in a one-stage reaction.

Claims (1)

[Claims] 1. In producing a carboxymethyl cellulose ether alkali metal salt by etherifying a cellulosic raw material in a water-containing organic solvent, (1) a cellulosic raw material is mixed with (2) monochloroacetic acid in an equimolar amount of water. After mixing with a water-containing organic solvent solution of an alkali metal salt of monochloroacetic acid prepared by adding alkali oxide to monochloroacetic acid, etherification is carried out by further adding 2 to 5.55 mol of alkali hydroxide in a solid state per mole of glucose at a single position. A method for producing a carboxymethyl cellulose ether alkali metal salt, characterized by: 2. The manufacturing method according to claim 1, wherein the temperature when adding alkali hydroxide to monochloroacetic acid to prepare the alkali metal salt of monochloroacetic acid is 50°C or less. 3. The method according to claim 1, wherein the carboxymethylcellulose ether alkali metal salt produced after etherification has a carboxymethyl substitution degree (DS) of 1.30 or more. 4 Water-containing organic solvent/cellulosic raw material weight ratio is 3.5
2. The method according to claim 1, wherein the ratio is from /1 to 10/1.