JPH0425501A - Production of low-viscosity carboxymethylcellulose sodium salt - Google Patents

Abstract

PURPOSE:To obtain a CMC-Na salt which is lowly viscous and has rheological characteristics near to those of a Newtonian fluid at good efficiency by mixing a CMC-Na salt with hydrogen peroxide and reacting them by heating while keeping the pH of the reaction system in a certain range. CONSTITUTION:A carboxymethylcellulose sodium salt is mixed with hydrogen peroxide. While the pH of the reaction system is kept at 6.5-3, they are reacted by heating to obtain a lowly viscous carboxymethylcellulose sodium salt. Although the pH in the reaction with hydrogen peroxide may be controlled by directly adding an acid to the reaction system, the control can be performed by adding an acid to the aqueous solution of hydrogen peroxide before the reaction. The obtained salt can be dissolved in a high concentration, and its 30wt.% aqueous solution has a viscosity of 100-10000cP and properties like those of gum arabic and can be desirably used as, e.g. an emulsifier for foods or medicines.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing low viscosity sodium carboxymethylcellulose. In detail, in the method of mixing hydrogen peroxide with carboxymethyl cellulose sodium (hereinafter abbreviated as CMCNa) and producing low-viscosity CMC-Na in a solid state, it efficiently has the rheological properties of a Newtonian fluid and has high The present invention relates to a method for producing low viscosity CM C-Na similar to gum arabic which can be dissolved in concentration.

(Prior Art) Various methods for producing low-viscosity cellulose derivatives have been proposed.

For example, a method is disclosed in which a powdered water-soluble cellulose ether is brought into contact with hydrogen halide gas, hydrogen halide absorbed into an aliphatic alcohol, or an aqueous hydrogen chloride solution (Japanese Patent Publication No. 4g-41037, 1983, Japanese Patent Application Laid-Open No. 6225101). has been done.

Another method is disclosed in which powdered CMC-Na is made to have a low viscosity by using bleaching powder (Japanese Patent Publication No. 5G-31081).

Another method is disclosed (Japanese Unexamined Patent Publication No. 145701/1983) in which dry or wet cellulose ether is reacted with a mixture of ozone and oxygen or air.

Another method is to irradiate solid water-soluble cellulose derivatives with gamma rays (Japanese Patent Publication No. 47-3964.41-3965).
(Government) has been disclosed.

Another method is disclosed in which powdered or wet cellulose ether is reacted with hydrogen peroxide to reduce the viscosity (Japanese Patent Publication No. 45-678, Japanese Patent Publication No. 48-19232).

(Problems to be Solved by the Invention) However, the above methods also have various drawbacks when producing low viscosity CMC-Na.

The method of lowering the viscosity of CMC-Na using hydrogen halide has the drawback that a portion of CMC-Na becomes water-insoluble acid type carboxymethylcellulose, resulting in the formation of gel-like insoluble matter.

In the method using bleached powder, when the reduced viscosity CMC-Na is used for foods, medicines, etc., purification treatment is required to remove by-products.

Furthermore, the method of applying ozone and the method of irradiating with gamma rays require special equipment, resulting in high costs, and the maintenance of the equipment is not easy.

Compared to these methods, the method of reducing viscosity by reacting hydrogen peroxide with CMC-Na is an excellent method that does not produce insoluble gels or by-products and can be produced using only a simple mixing device. In the conventionally disclosed method, even if a large amount of hydrogen peroxide is used, the viscosity of a 30% aqueous solution is 100 to 1000.
It was difficult to industrially produce ultra-low viscosity CM C-Na of 0 cps.

The present inventors efficiently produced ultra-low viscosity CMC-Na by reacting hydrogen peroxide with CMC-Na to reduce the viscosity.
As a result of extensive research on the method for producing , it was discovered that adjusting the pH of the reaction system is important, and based on this knowledge, the present invention was developed.

(Means for Solving the Problems) The present invention is a method for producing low-viscosity sodium carboxymethylcellulose in a solid state by mixing hydrogen peroxide with sodium carboxymethylcellulose and heating the mixture, in which the pH of the reaction system is reduced to 6. This is a method for producing low viscosity carboxymethylcellulose sodium, characterized by carrying out the reaction while maintaining the viscosity at .5 to 3.0.

CMC-Na, which is the raw material of the present invention, is not particularly limited, and the average degree of substitution of carboxymethyl groups (
(hereinafter abbreviated as DS) has a viscosity of 0.6 to 3.1% aqueous solution of 1
A normal CM C-Na of 0-10000 cps can be used. It goes without saying that using CMC with low viscosity as a raw material is more advantageous in reducing the viscosity, but DS is 1.
It is preferably 0 or more. CM C with DS of 1.0 or less
- When Na is used as a raw material, the low viscosity reduction efficiency is low, and the obtained low viscosity CMC-Na has structural viscosity and has rheological properties close to Newtonian flow similar to gum arabic.
Difficult to obtain C-N a. CMC-Na may be used in the manufacturing process or as a product, but it is preferably in the form of a substantially dry powder or granules.

In the present invention, it is important to adjust the pH during the reaction of hydrogen peroxide, and it is necessary to keep the pH of the reaction system in the range of 6.5 to 3.0, preferably in the range of 6.0 to 4.5. be. P
When H is 6.5 or more, the low viscosity efficiency deteriorates, and 3.0
Below that, gel-like water-insoluble substances tend to form.

The prior art, Japanese Patent Publication No. 48-19232, states that oxidation with peroxide under mild alkaline conditions with a pH of approximately 8 to 11 is very effective; The results revealed that at pH 6.5 or higher, the viscosity-lowering efficiency deteriorates. This is thought to be because under alkaline conditions, the generation of active oxygen through the decomposition of hydrogen peroxide is better, but more is scattered into the atmosphere, which deteriorates the viscosity-lowering efficiency.

The pH during the hydrogen peroxide reaction may be adjusted by adding the acid directly to the reaction system, but it can also be done by adding the acid to the hydrogen peroxide aqueous solution in advance.

Although various inorganic acids and organic acids can be used as the acid for sub-adjustment of PH, acetic acid is preferably used because the PH can be easily adjusted.

In the present invention, the water content of the mixture at the start of the reaction is 17 to
It is desirable to keep it in the range of 10% by weight, preferably 15-12% by weight. If the water content of the mixture at the start of the reaction is 17% by weight or more, as the viscosity decreases, the powder or granules in the reactor will aggregate, forming lumps with a diameter of 1 to 10 cm, and forming powder or granules. It becomes impossible to maintain the state of When this happens, the inside of the lump becomes locally high temperature due to the heat of reaction,
The reaction may become uneven and may ignite, creating a dangerous situation. In addition, CMC-N a adheres to the side walls of the reactor and forms a laminated plate, which comes into contact with the mixing blades and interferes with the operation of the reactor. On the other hand, if the water content of the mixture at the start of the reaction is less than 10% by weight, this is undesirable because the viscosity reduction efficiency will be poor.

For addition of hydrogen peroxide and heat treatment, conventionally known methods may be used. Hydrogen peroxide is usually 30-40% by weight
Use as an aqueous solution. While mixing and stirring raw material powder or granular CMC-Na in a reaction device, dry CM C-N
After spraying 0.1 to 0.5% by weight of hydrogen peroxide to a at once or in several batches, heat and mix at 60 to 150°C for a sufficient time for the added hydrogen peroxide to react. to obtain a low viscosity CM C-Na.

(Effect of the invention) The method of the present invention has high viscosity reduction efficiency, and the viscosity of a 30% aqueous solution, which was difficult to produce in the past, is 100 to 10,000 cps.
The present invention provides a method for industrially producing ultra-low viscosity CMC-Na similar to gum arabic and having rheological properties close to Newtonian fluids. Since gum arabic is a natural product, its production volume and quality are not constant depending on the weather, and the industry has long been looking for a substitute for it.This problem will be solved by the present invention.

The method of the present invention has a high viscosity efficiency and can reduce viscosity with a small amount of hydrogen peroxide, so there is less danger in the manufacturing process, and since less water is produced by decomposing hydrogen peroxide, powder or granules can be produced. It is suitable for industrial production because it is unlikely to cause agglomeration or clumping.

(Examples) Examples of the present invention will be shown below, but the present invention is not limited thereto.

Examples 1 and 2, Comparative Example 1, and Reference Example 5 kg of CMC-N a 1 with different DS were placed in a blender, heated to 70 to 80°C, and the initial pH was adjusted to 6.5 or less with acetic acid. After adjustment, 200 ml of a 35% hydrogen peroxide aqueous solution was added in three portions to perform a viscosity reduction reaction. The reason why the reaction was divided into three times was to adjust the water content at the start of the reaction to 17 to 10% by weight. Table 1 shows the results. As you can see from this result, DS is 1.0
In Comparative Example 1 below, it can be seen that even if the viscosity is about the same at a concentration of 10% by weight, the viscosity is not very different at a concentration of 30% by weight. In addition, looking at the flow characteristics at a concentration of 30% by weight, P is the ratio of the viscosity at a rotational speed of 6 orpm and the viscosity at a rotational speed of 6 rpm measured by a rotational viscometer.
It can be seen that although there is a large difference in VI value compared to the reference gum arabic, Example 1.2 with a DS of 1.0 or more shows the same value.

The following margins Examples 3, 4.5 and Comparative Example 2 DS is 1.55.2% by weight aqueous solution has a viscosity of 445
Add 2 kg of cps CMC-Na to blender, 7
After heating to 0 to 80°C and changing the initial pH by changing the amount of acetic acid added, 120 m of a 35% hydrogen peroxide aqueous solution was added.
A viscosity-lowering reaction was carried out by adding 1 in 3 portions. As the reaction progresses, the pH decreases, but in Comparative Example 2, the P
The reaction was carried out while controlling with an aqueous sodium carbonate solution to maintain H at 7.0 or higher. Table 2 shows the results. As can be seen from this result, Comparative Example 2, in which the pH of the reaction system was 7.0 or higher, had a lower viscosity than CMC, even when using the same amount of hydrogen peroxide, compared to Examples 3 and 4.5, in which the pH of the reaction system was 6.5 or lower. It can be seen that the viscosity of -Na is high and the reaction efficiency is low.

The following margins Example 6 and Comparative Example 3 DS is 1.54.2% by weight aqueous solution has a viscosity of 91.0
cps, CM C-N a2.5k with moisture 9.9% by weight
g was placed in a blender, heated to 70 to 80°C, and the initial pH was adjusted to 7.0 or less with acetic acid, and then 120 ml of a 35% hydrogen peroxide aqueous solution was added to perform a viscosity-lowering reaction. In Example 6, the aqueous hydrogen peroxide solution was added in three parts, but in Comparative Example 3, it was added all at once. As a result, the water content at the start of the reaction was as shown in Table 3. As can be seen from the results in Table 3, when the water content at the start of the reaction is 17% by weight or more, lumps are formed during the reaction, and CMC-N
a adhered to it, forming a laminated plate shape, and eventually the mixing blade stopped moving. However, when the water content at the start of the reaction was 17% by weight or less, this did not occur, and the mixture could be mixed smoothly to the end, and low-viscosity CMC-Na could be produced.

Margin below = =

Claims (1)

[Claims] In a method for producing low-viscosity sodium carboxymethylcellulose in a solid state by mixing hydrogen peroxide with sodium carboxymethylcellulose and heating the mixture, the reaction is carried out while maintaining the pH of the reaction system between 6.5 and 3.0. Characteristic method for producing low viscosity carboxymethyl cellulose sodium.