JPH069702A - Production of modified cellulose ether - Google Patents

Abstract

PURPOSE:To provide a rational method of producing a modified cellulose ether wherein a modifier reacts at a high efficiency and there is no need of using a large amount of an organic solvent and which therefore is economical and contributes to the prevention of working-atmosphere pollution. CONSTITUTION:A water-soluble cellulose ether dispersed in an organic solvent is reacted with an epoxyalkane and/or an alkyl glycidyl ether each having an 8-24C alkyl in the presence of an alkali to replace the hydrogen atoms of part of the hydroxyl groups of the ether by the alkyl group, thereby giving a modified cellulose ether. The amount of the solvent is 0.5-3 times, preferably 0.5-1.0 time, by weight the amount of the ether. The reaction is conducted in a reactor equipped with a stirrer having two rotating blades 2. The ether is preferably hydroxypropylmethyl cellulose and/or hydroxyethyl cellulose.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a modified cellulose ether useful as a thickener.

[0002]

2. Description of the Related Art Japanese Examined Patent Publication No. 1-28041 and Japanese Examined Patent Publication No. 1
-28042, JP-A-1-144401,
JP-A-3-12401, JP-A-3-151330
In the publications, etc., as a thickener used in paints, cosmetics, pharmaceuticals, etc., a method of using long-chain alkyl-modified cellulose ethers in which hydrogen atoms of some hydroxyl groups are replaced with long-chain alkyl groups is proposed. ing.

As a method for producing such a long-chain alkyl-modified cellulose ether, a method is known in which a cellulose ether and a modifier are reacted in an organic solvent. Cellulose ether is dispersed in a slurry in an organic solvent. As such an organic solvent, for example, isopropyl alcohol, tert-butyl alcohol, etc. are used. An alkyl epoxide or an alkyl glycidyl ether having an alkyl group having 8 to 24 carbon atoms is used as the modifier. In the reaction, an aqueous sodium hydroxide solution is added to the reaction solution and heated while mixing.

[0004]

However, the above-mentioned conventional manufacturing method has a problem that it is uneconomical because it requires many modifiers in an amount equal to or larger than the ratio for actually substituting the cellulose ethers. It was Also, the cost is industrially high in that a large amount of alcohol-based organic solvent is required,
There is also a drawback that the large amount of volatile solvent deteriorates the manufacturing environment.

In order to solve the above problems, the present invention requires a high reaction efficiency of the modifier and a small amount of the organic solvent, resulting in a reasonably low cost and prevention of pollution of the manufacturing environment. An object of the present invention is to provide a method for producing a modified cellulose ether.

[0006]

The method for producing a modified cellulose ether of the present invention, which has been made to achieve the above object, comprises a water-soluble cellulose ether in a dispersed state and an alkyl group having an alkyl group having 8 to 24 carbon atoms. Epoxide or / and alkyl glycidyl ether in an organic solvent, in the presence of an alkali, in the method of producing a modified cellulose ether in which a hydrogen atom of a part of the hydroxyl groups of the cellulose ether is substituted with an alkyl group, the proportion of the organic solvent used In an amount of 0.5 to 3 times the weight of the cellulose ethers and reacted in a reactor having a twin-screw stirrer.

The water-soluble cellulose ethers to be reacted with the alkyl epoxide and the like in the present invention include, for example,
Water-soluble alkyl cellulose such as methyl cellulose may be mentioned. Also included are hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose. Also included are hydroxyalkylalkylcelluloses such as hydroxypropylmethylcellulose. These may be used alone or in combination. Among them, hydroxypropylmethyl cellulose or hydroxyethyl cellulose is most preferable.

In the present invention, such water-soluble cellulose ethers are reacted with a modifier. Examples of such modifiers include alkyl epoxides and alkyl glycidyl ethers. The number of carbon atoms in the alkyl group is 8 to
24 is good. Such alkyl epoxides include:
Examples include octyl epoxide. Examples of the alkyl glycidyl ether include decyl glycidyl ether and stearyl glycidyl ether.
These modifiers may be used alone or in combination of two or more.

The above water-soluble cellulose ethers and the modifier are reacted in a reaction organic solvent in the presence of an alkali. Examples of the reaction organic solvent in this case include lower alcohols such as isopropyl alcohol and tert-butyl alcohol, as well as acetone and dimethyl sulfoxide. These may be used alone or in combination. Examples of the alkali include alkali hydroxide.

In the case of the present invention, the amount of the modifier charged into the reaction system is 0.001-1.
0 is enough. The amount of the organic solvent used is 0.5 to 3 times, preferably 0.5 to 1 times the weight of the water-soluble cellulose ether. When the amount of the organic solvent used is more than three times the amount of the water-soluble cellulose ether used, the viscosity of the reaction solution decreases, but the amount of the modifier added must be increased accordingly. If the amount of the organic solvent used increases, the deterioration of the manufacturing environment accompanying it must be taken into consideration, which is not preferable. If the weight ratio is less than 3 times, the reaction efficiency of the modifier improves as the amount of the organic solvent decreases. However, if it is less than 0.5 times, unevenness occurs in the mixing of the water-soluble cellulose ethers and the modifier. Moreover, water-soluble cellulose ethers usually swell with an organic solvent, but if the ratio of the organic solvent is lower than 0.5 times, the swelling will be insufficient and the reaction efficiency of the modifier will also decrease, which is not preferable.

The amount of alkali used is preferably about 0.05 to 0.5 times the molar ratio of the cellulose ether used in the reaction to the anhydroglucose unit. Reaction temperature is 50
-80 ° C, and the reaction time is 3-8 hours.

In the reaction with the modifier, water-soluble cellulose ethers are dispersed in an organic solvent. A twin-screw stirrer is used for the reactor. 1 and 2 show an example of a twin-screw agitator with the upper lid removed. The twin-screw agitator is provided with a plurality of parallel flat blades 2 having horizontal rotary shafts 1 that rotate in the same or opposite directions. The plurality of rotary blades 2 simultaneously rotate to knead the highly viscous reaction liquid. In carrying out the present invention, a commercially available twin-screw stirrer may be used for actual use. In a vertical reactor, the viscosity of the reaction liquid is too high to drive, and it is difficult to generate a sufficiently uniform reaction, which is not appropriate.

In the present invention, when the water-soluble cellulose ethers and the modifier are reacted in this manner, a crude modified cellulose ether is obtained in the reaction solution. A known method may be used for purification. The modified cellulose ether produced by such a method can be preferably used as a thickener for cement mortar, extrusion molding material, paint, cosmetics, pharmaceuticals and the like.

[0014]

By reducing the amount of the organic solvent used, it is possible to reduce the amount of the modifier used which has been required in the past. When the amount of the organic solvent used is reduced, the viscosity of the reaction solution increases, but in the twin-screw stirrer, a plurality of flat rotary blades kneads the reaction solution with loads that simultaneously flow in different directions. This allows for a uniform reaction that is even.

[0015]

INDUSTRIAL APPLICABILITY As described above in detail, the method for producing a modified cellulose ether of the present invention has a high reaction efficiency of a modifier and a small amount of an organic solvent, which is practically low in cost. It also helps prevent environmental pollution.

[0016]

EXAMPLES Examples of the present invention will be described below. Example 1 In a 5 L reactor equipped with a twin-screw stirrer, 400 g of hydroxypropylmethyl cellulose, 200 g of isopropyl alcohol (IPA), an aqueous solution of sodium hydroxide 163.
g and stearyl glycidyl ether (SGE) 7 g were charged, and hydroxypropylmethyl cellulose and stearyl glycidyl ether were reacted at 80 ° C. for 5 hours. The hydroxypropylmethyl cellulose used had a methoxyl group MS of 1.87 and a hydroxypropoxyl group MS of 0.24. The concentration of the aqueous sodium hydroxide solution was 49% by weight.

FIG. 1 is a plan view showing the inside of the twin-screw agitator used in this embodiment, and FIG. 2 is an elevation view. In a twin-screw stirrer, a bottom plate having two shallow U-shaped grooves formed in parallel with each other is surrounded by high-perimeter peripheral walls on four sides to form a box 5 having a deep bottom. Rotor blades 2 are provided in parallel at the bottom of the box body as if they rub the inner surface of the U-shaped groove. The rotary blade 2 is formed of an elongated flat plate cut out in an S-shape, and both ends in the longitudinal direction are axially supported by the peripheral wall above the U-shaped groove, and one end of the rotary shaft 1 penetrates the peripheral wall to cover the cover 3. Is covered with. The other end is driven by a motor 6 mounted on the box body 5 through a drive transmission means.

After carrying out a predetermined reaction in the reactor described above and terminating it, the reaction solution obtained is filtered to collect the reaction slurry, which is neutralized with acetic acid and then cooled, and 1200 g of hexane are added. Wash 3 times, wash further with 5 liters of hot water,
It was dried and then crushed. A high-purity stearyl-modified hydroxypropylmethylcellulose was obtained. The reaction efficiency of stearyl glycidyl ether was 60%.

Examples 2 and 3 The procedure of Example 1 was repeated, except that the amounts of isopropyl alcohol, sodium hydroxide aqueous solution and stearyl glycidyl ether charged were as shown in Table 1. The results are shown in Example 1.
The results are shown in Table 1 together with.

[0020]

[Table 1]

Comparative Examples 1 and 2 The same procedure as in Example 1 except that the charged amounts of isopropyl alcohol, sodium hydroxide aqueous solution and stearyl glycidyl ether are shown in Table 1. The results are shown in Table 1.

From the above results, the ratio of isopropyl alcohol used was 3% of hydroxypropylmethylcellulose.
It was found that the reaction efficiency of the denaturing agent decreases when the weight is exceeded.

[Brief description of drawings]

FIG. 1 is a plan view of a twin-screw agitator used in an example of the present invention.

FIG. 2 is an elevational view of a twin-screw agitator used in an example of the present invention.

[Explanation of symbols]

 Reference numeral 1 is a rotary shaft, 2 is a rotary blade, and 6 is a motor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Maruyama 1 of 28, Nishi-Fukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture Shin-Etsu Chemical Co., Ltd. Synthetic Technology Laboratory (72) Inventor Yasuaki Muto Niigata Prefecture 28, Nishi-Fukushima, Kikugi-mura, Gunma 1 Shin-Etsu Chemical Co., Ltd. Synthetic Technology Laboratory

Claims (3)

[Claims] 1. A water-soluble cellulose ether in a dispersed state is reacted with an alkyl epoxide having an alkyl group having 8 to 24 carbon atoms and / or an alkyl glycidyl ether in an organic solvent in the presence of an alkali to give one of the cellulose ethers. In the method for producing a modified cellulose ether in which a hydrogen atom of a hydroxyl group of a part is substituted with an alkyl group, the proportion of the organic solvent used is 0.5 times by weight to 3 times that of the cellulose ether.
A method for producing a modified cellulose ether, which comprises doubling the weight and reacting in a reactor having a twin-screw stirrer. 2. The use ratio of the organic solvent is 0.5 to 1.0 times by weight that of the cellulose ethers.
The method for producing a modified cellulose ether according to 1. 3. The method for producing a modified cellulose ether according to claim 1, wherein the cellulose ether is hydroxypropylmethyl cellulose and / or hydroxyethyl cellulose.