JPS60177001A - Preparation of water-insoluble alkali salt of carboxymethyl cellulose ether - Google Patents

Abstract

PURPOSE:To prepare the titled salt useful as a thickening agent, dispersion stabilizer, etc. in the field of foods, etc. without using a crosslinking agent and without destroying crystal structure of cellulose, by treating cellulose with am alkali and an etherifying agent at a specific temperature. CONSTITUTION:Cellulose such as a linter, pulp, etc. is treated with an alkali (e.g., NaOH, etc.) and an etherifying agent (e.g., monochloroacetic acid, etc.) in the presence of water or a water-containing organic solvent (e.g., ethylalcohol, isopropyl alcohol, etc.), to give an alkali salt of carboxymethyl cellulose ether (CMC for short). In the operation, the cellulose is treated with the alkali at >=45 deg.C reaction temperature, to give the desired CMC. In the reaction, first the cellulose is impregnated with the etherifying agent, the reaction temperature is kept at >=45 deg.C, the alkali is added to the cellulose, and the reaction is completed in a short time by neutralization heat.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a water-insoluble carboxymethyl cellulose ether alkali salt (hereinafter abbreviated as CMC). More specifically, when producing CMC by reacting cellulose such as linters and pulp with an alkali and an etherifying agent in the presence of water or a water-containing organic solvent, the reaction temperature when reacting the alkali with the cellulose is 45°C. A water-insoluble C characterized by having the following characteristics:
The present invention relates to a method for manufacturing MC.

CMC1d It is industrially produced in large quantities by reacting cellulose such as linters and pulp with water or a water-containing organic solvent as a reaction medium and an alkali and an etherifying agent.
It is a water-soluble polymer that is widely used as a thickener, dispersion stabilizer, adhesive, protective colloid agent, etc. in the fields of building materials, textiles, paper, petroleum polling, and other industries.

As described above, the water-soluble function of CMC is used in most applications9, and therefore, many studies have been conducted to improve the solubility in water in the research of CMC manufacturing methods. Generally, CMC becomes soluble in water when the average degree of substitution (hereinafter abbreviated as DS) of the sylboxymethyl group per anhydrous glucose unit is about 04 or more. Therefore, the DS of commercially available CMC is 04 to 1.6.

In addition, CMC has recently been used as a water-absorbent material for disposable diapers, etc.
is attracting attention. This is because CMC has excellent water retention properties. , DS0.1 to α5 are used. This is because CMC as a water-absorbing material does not necessarily have the function of being water-soluble, but rather it is often preferable that it absorbs a large amount of water and retains it, but does not dissolve it.

Even in such applications, the DS of C'MC should be set to an O
, O~1.2, but if the DS of CMC is increased, cMc manufactured by the conventional manufacturing method becomes water-soluble and cannot be used.

As a method of insolubilizing CMC with high DS, a method of crosslinking with a special crosslinking agent (JP-A-5O-85089) can be considered, but this requires an additional crosslinking step, and furthermore, crosslinking in the reaction solvent and in the product is considered. The use of this product is also limited because it is expected that the agent will remain. On the other hand, C
A method of making MC partially in acid form and crosslinking it by intramolecular and intermolecular ester bonding between the carboxyl group and hydroxyl group of CMC to make it water-insoluble (JP-A-54-935 and JP-A-56
-2875.5) is also considered, but the ester bond is generally unstable and has the drawback that the crosslinking easily comes off when it is made into an alkali salt type.

The present inventors have conducted extensive studies on a method for producing water-insoluble CMC without using a crosslinking agent and without crosslinking using some acid-type carboxyl groups. As a result, the present invention has been developed. They discovered a manufacturing method.

In the present invention, when producing CMC by making an alkali etherification agent act on cellulose such as linter or hyalf in the presence of water or a water-containing organic solvent, the reaction temperature when making an alkali act on cellulose is 45°C. This is a method for producing water-insoluble CMC characterized by carrying out the above steps.

CMC is usually manufactured by the following method called the Arcel method. That is, alkali cellulose is prepared by immersing or stirring and mixing cellulose raw materials such as linters and pulp in water containing sodium hydroxide or a water-containing organic solvent at a temperature of 10 to 40°C for 30 to 180 minutes, and then the water is removed. When used as a solvent, excess sodium hydroxide aqueous solution is removed by squeezing or the like. When using a water-containing organic solvent, this removal operation is not performed because the minimum necessary amount of sodium hydroxide and water is used.

Next, as an etherification agent, monochloroacetic acid or sodium monochloroacetate is dissolved in water or an organic solvent and added little by little. After stirring and mixing at 10 to 45°C for about 30 minutes, ~50℃ for about 4 to 10 hours, or 60 to 80℃ when using a water-containing organic solvent.
Run the etherification reaction for ~120 minutes. After the reaction is complete, excess sodium hydroxide is neutralized with sulfuric acid or acetic acid to remove crude C.
Get MC. Next, if necessary, wash with a 60-80% methyl alcohol aqueous solution to remove by-products such as salt, sodium glycolate, sodium acetate, etc., and dry.
Grind to obtain purified CMC.

In addition, a manufacturing method called the direct method or the mono-chloric acid method is adopted in some cases.

In this method, sodium monochloroacetate is added as a powder or aqueous solution to water or a water-containing organic solvent containing cellulose such as linter or pulp, and after stirring and mixing at 10 to 40°C for 30 to 180 minutes, the necessary amount of hydroxyl is added. ) Add IJum as a solid or aqueous solution and stir and mix at 10 to 45°C for about 30 minutes. After that, if water is used as a solvent, 20 to 5
The etherification reaction is carried out at 0°C for 4 to 10 hours, or if a water-containing organic solvent is used, at 60 to 80°C for 60 to 120 minutes.

After the reaction is completed, excess sodium hydroxide is neutralized with sulfuric acid, acetic acid, etc. to obtain crude CMC. The purification method is exactly the same as the Arcel method.

In addition, the water-containing organic solvent used as a reaction solvent c,
Ethyl alcohol, 1so-propyl alcohol, t
A 2% solution of ert-butyl alcohol, acetone, and a mixed solvent of ethyl alcohol and benzene is used.

However, in both production methods, the reaction temperature when sodium hydroxide is applied to cellulose such as linter or pulp in water or a water-containing organic solvent is 10 to 40°C. This is because when a sodium hydroxide aqueous solution at a temperature of 10 to 40°C is applied to cellulose, the destruction of the crystal structure of cellulose progresses and the cellulose fibers swell significantly. The process progresses uniformly and CMC with good water solubility can be obtained.

In addition, before adding an alkali to cellulose such as linter or pulp in the presence of water or a water-containing organic solvent and allowing it to act, an etherifying agent is added to impregnate the cellulose.
In the so-called direct method mentioned above, sodium monochloroacetate is used as the etherification agent, and a method of directly impregnating cellulose with monochloroacetic acid is not carried out.

Therefore, the present inventors believe that it is possible to produce water-insoluble CMC by carrying out the CMC reaction under conditions that suppress as much as possible the swelling of cellulose caused by destruction of the cellulose crystal structure. As a result of various studies, we have arrived at the present invention. In other words, water-insoluble cMc can be obtained by setting the temperature of the reaction system to 45°C or higher when adding an alkali to cellulose such as linter or pulp in the presence of water or a water-containing organic solvent. I found out that it can be done.゛The production method of the present invention can be carried out by either the aforementioned Arcel method or the direct method, and can also be carried out by either the so-called aqueous medium 4T, which uses water as a solvent, or the so-called solvent method, which uses a water-containing organic solvent. It is possible.

In addition, in order to carry out the present invention more effectively, monoclopa acetic acid is used as an etherification agent, and cellulose such as linter or pulp is treated in the presence of water or a water-containing organic solvent.
It is preferable to impregnate cellulose with monochloroacetic acid in advance before adding an alkali and reacting with the alkali after maintaining the reaction temperature at 45° C. or higher.

This is because the etherification reaction is completed in a short time due to the heat of neutralization between the monochloroacetic acid and the alkali that has been added in advance, so the amount of alkali in the reaction mixture becomes faster and the cellulose and the alkali come into contact with each other. This is probably because the time is shorter.

Thus, it is preferable that the temperature at which the alkali is added to the reaction mixture is 45°C or higher, particularly 55°C or higher. However, the upper limit of the temperature is not particularly limited, although it is industrially desirable to keep it below the boiling point of the reaction solvent used since this allows the use of a normal pressure reaction vessel.

Further, the DS of the water-insoluble CMC that can be constructed according to the present invention is 0.1 to 1.2. If the DS is 13 or more, even if the method of the present invention is carried out, it will not be possible to achieve the objective because water-soluble substances will be predominant, although a considerable amount of water-insoluble substances will be contained.

EXAMPLES Examples and comparative examples specifically explaining the present invention will be shown below, but the present invention is not limited to the examples shown below. Further, in Examples and Comparative Examples, "part" means part by weight, and "chi" means % by weight.

The method for measuring the average degree of substitution, ie, DS and water insolubility of the produced CMC is as follows.

(1) Average degree of substitution (DS) Purified CMCI, 9 (absolutely dry) was accurately weighed, placed in a platinum crucible or porcelain crucible, and incinerated at 600°C. The sodium oxide produced by the ashing was Neutralize and titrate phenolphthalein with sulfuric acid as an indicator, and calculate the titration amount A W
The calculation was performed by putting Le into the following equation, and the DS was determined.

10000 - 80 Therefore, when the CMC of the present invention is added to water at a concentration of 0.25 to 1%, it absorbs water significantly, swells, and settles. However, it is difficult to separate P from the swollen CMC using a glass filter or the like. Therefore, in order to evaluate the solubility in water, 4% saline solution19
After adding 9 g of CMC of the present invention and 1 g of comparative CMC (absolutely dry), stirring and mixing thoroughly, the mixture was allowed to stand at room temperature for 24 hours. Thereafter, the mixture was further stirred and mixed, and the mixture was filtered under reduced pressure through a glass filter of known weight 1G2 to separate the insoluble matter. Next, 75 dimethyl alcohol aqueous solution 100
After washing twice with g, 100 g of 99-thimethyl alcohol
Wash once more and separate the P with a glass filter. Next, after air drying, the glass filter was dried in a hot air drying volume of 105±2°C, and after cooling in a desiccator, the weight was measured to determine the insoluble content.

The insolubility in water was evaluated based on the weight percent of the insoluble content with respect to this 4-T saline solution.

Example 1 1650 parts of %l5O-propyl alcohol and 150 parts of pure water were placed in a 31 separable flask equipped with a stirring mixer and a reflux condenser.
part and crushed linter (moisture 5 t, degree of polymerization 2200
) Prepare j5 parts. Next, 401 parts of monochloroacetic acid was dissolved in 40.1 parts of 1so-propyl alcohol while stirring and mixing, and the temperature of the mixture was brought to 55°C. Next, 376 parts of sodium hydroxide was dissolved in 376 parts of pure water, and after stirring and mixing at 55 to 60°C for 10 minutes,
The temperature was raised to 70°C and the etherification reaction was carried out for 60 minutes.

Next, excess sodium hydroxide was neutralized with acetic acid, cooled, and separated by f to obtain crude CMC. Washed twice with 1,800 parts of a 75% methylalcohol aqueous solution, and once with 1,500 parts of 99-thimethylalcohol, and separated from P.

Next, the CMC of the present invention was obtained by drying at 80 to 100° C. for 4 hours in a steam dryer. The DS and water insolubility of the produced CMC are listed in Table 1.

Examples 2 to 3, 4 Reactions were carried out under exactly the same conditions as in Example 1 except that the amounts of monochloroacetic acid and sodium hydroxide used were different, and CMCs of the present invention having different DS were obtained. However, Example 4
Only when reacting with alkali, set the reaction temperature to 65-7.
The temperature was 0°C. The amounts of monochloroacetic acid and sodium hydroxide charged and the insolubility of the produced CMC in DS and water are listed in Table 1.

Example 5, instead of 1so-propyl alcohol in Example 1, t
CMC of the present invention was obtained by carrying out the reaction in exactly the same manner as in Example 1 except for using ert-butyl alcohol.

Details are listed in Table 1.

Comparative Example 1 A comparative CMC was obtained by carrying out the reaction under the same conditions as in Example 1, except that the temperature of the reaction mixture during addition and mixing of the aqueous sodium hydroxide solution was 20 to 30°C. Details are listed in Table 1.

Example 6゜34 separable 7 laths with stirring mixer and reflux condenser:
1650 parts of 7K, 1so-7" Lobil alcohol, 150 parts of pure water and crushed pulp (moisture 5 t, degree of polymerization 850)
) Prepare 75 copies. Next, the temperature of the reaction mixture was raised to 55°C while stirring and mixing, and then 376 parts of sodium hydroxide was added to 3 parts of pure water.
The mixture was dissolved in 76 parts and mixed with stirring at 55 to 60°C for 20 minutes. Next, 1 part of monochloroacetic acid 4α was added to 1 so
- Dissolve and prepare in 40.1 parts of propyl alcohol, 5
After stirring and mixing at 6 to 60°C for 10 minutes, the temperature was raised to 70°C and an etherification reaction was performed for 60 minutes. Next, excess sodium hydroxide is neutralized with acetic acid, and then cooled and the reaction solvent is separated to obtain crude CMC. Next, the CMC of the present invention was obtained by purification and drying in the same manner as in Example 1. Details are listed in Table 1.

Comparative Example 2 A CMC of a comparative example was obtained by carrying out the reaction under exactly the same conditions as in Example 6, except that the temperature of the reaction mixture during addition and mixing of the aqueous sodium hydroxide solution was 20 to 30°C. Details are listed in Table 1.

Example 7 Linter (moisture 5%, degree of polymerization 2200) a, o crushed in a 51 kneader with two-shaft stirring blades.

of monochloroacetic acid while stirring and mixing at room temperature.
A solution of 40.6 parts dissolved in 320.8 parts of pure water was added little by little to a linter, and stirred and mixed for 20 minutes. After that, the temperature was raised to 55°C, and sodium hydroxide 22
5.6 parts, dissolved in 150.4 parts of pure water and added, 55~
The mixture was stirred and mixed at 65° C. for 180 minutes to carry out the etherification reaction.

Next, it was poured into 5000 parts of 80-thimethyl alcohol,
Stir and mix for 30 minutes at room temperature.

At this time, excess sodium hydroxide is neutralized with acetic acid. It was further washed twice with 5,000 parts of a 75% methyl alcohol aqueous solution, then washed with 4,500 parts of 99% methyl alcohol, and centrifuged.

The CMC of the present invention was obtained by drying for 4 hours in a steam drying volume of 80 to 100°C. Details are listed in Table 1.

Commercially available products A and B The measured values of DS and water insolubility for commercially available products A (product of Company A) and B (product of Company B) are also listed in Table 1 for reference. As is clear from Table 1, the CMC produced by the method of the present invention has significantly greater insolubility in water than the comparative examples and commercially available products.

Claims (1)

[Claims] fil In producing carboxymethyl cellulose ether alkali salt by reacting cellulose with an alkali and an etherifying agent in the presence of water or a water-containing organic solvent, the reaction temperature when reacting cellulose with an alkali is 4
1. A method for producing a water-insoluble carboxymethyl cellulose ether alkali salt, which is carried out at a temperature of 5° C. or higher. (2) The production method according to claim 1, wherein cellulose is first impregnated with monochloroacetic acid as an etherifying agent in the presence of water or a water-containing organic solvent, and then an alkali is applied.