KR20070070550A - Method for preparation of high yield hydroxyalkylalkylcellulose ethers - Google Patents

Abstract

Provided is a method for preparing hydroxyalkyl cellulose, which shows an improved reaction efficiency in the reaction materials, reduces introduction of the reaction materials into waste water, and increases the yield of hydroxyalkyl cellulose to 60% or higher. The method for preparing hydroxyalkyl cellulose via the reaction of cellulose with an etherifying agent comprises the steps of: introducing an alkali metal hydroxide to cellulose in a molar ratio of 0.5-4 moles per mole of the cellulose, agitating the mixture, introducing an alkylene oxide thereto in a molar ratio of 0.5-3 moles per mole of the cellulose, further introducing an alkyl halide thereto in an amount of 20-95 wt% of the total amount of the alkyl halide, and carrying out a reaction; and introducing an alkali metal hydroxide to the reaction mixture in an amount of 1-4 moles per mole of the cellulose, dispersing the mixture, further introducing an alkyl halide thereto in an amount of 5-8- wt% of the total amount of the alkyl halide, and carrying out a reaction.

Description

Method for preparation of high yield hydroxyalkylalkylcellulose ethers

The present invention relates to a method for producing a high yield of hydroxyalkylalkyl cellulose, and more particularly, to a finely pulverized pulp is treated with alkali metal hydroxide at room temperature first, and then reacted with alkylene oxide and alkyl halide and Reaction of alkali metal hydroxide with alkyl halide to obtain hydroxyalkylalkyl cellulose with high alkoxy and hydroxyalkoxy substitution degree in high yield of 60% or more. It is an economically advantageous way to reduce the environmental load by reducing. Hydroxyalkylalkylcelluloses prepared by the process of the present invention are very useful for joint compounds, tile cements and surfactants.

Hydroxyalkylalkylcellulose is an industrially useful compound used as an adjuvant or additive in medicine, construction, paint, etc. In particular, hydroxyalkylalkylcellulose, as is well known, has a variety of properties such as cement and gypsum due to its good water solubility and thickening power. It is an industrially useful water-soluble cellulose ether prepared from natural materials widely used in mortar production, emulsion polymerization, and oil drilling industries.

Generally known hydroxyalkylalkyl cellulose production method is as follows.

According to U.S. Patent No. 4,477,657, 50 wt% alkali metal hydroxide was treated in finely pulverized linter pulp, heated to 85 ° C, continuously injected 45 minutes of propylene oxide, and then reacted for 45 minutes, and slowly injected with methyl chloride for 60 minutes. The reaction was carried out at 85 ° C. for 2 hours to obtain 17% methoxy substitution degree, 24.8% hydroxypropoxy substitution degree, 37.8% methyl chloride yield and 26.2% propylene oxide yield. In addition, 50 wt% alkali metal hydroxide was treated in a finely ground cotton printer, heated to 85 ° C., propylene oxide was injected for 15 minutes, reacted at 90 ° C. for 30 minutes, and then 50% by weight aqueous alkali metal hydroxide solution was used. Methyl chloride was injected for 30 minutes and reacted for 30 minutes at 80 to 90 DEG C to obtain 28.0% of methoxy substitution degree and 12.3% of hydroxypropoxy substitution degree in methyl chloride yield of 42.1% and propylene oxide yield of 49.0%. However, the method has a disadvantage in that the yield of alkylene oxide is economically disadvantageous and the hydroxyalkoxy substitution degree is low as 25% or less.

According to US Pat. No. 4,661,589, the following method was used to solve the low yield problem. After treating 50 wt% alkali metal hydroxide aqueous solution to finely pulverized cotton printer, it was maintained at 60 ° C. for 15 minutes, reduced to 200 mmHg, and slowly injected continuously in small amounts in propylene oxide. Dilute the dimethyl ether slowly for 30 minutes, increase the temperature to 80 ℃, react for 30 minutes, add 50% by weight aqueous alkali metal hydroxide solution, inject a very small amount of methyl chloride, and react at 80 ℃ for 1 hour. Toxic degree of substitution of 19.3% and hydroxypropoxy degree of substitution of 27.5% yielded methyl chloride yield of 52.4% and propylene oxide yield of 44.7%. However, the above method has a slight improvement in the yield of methyl chloride and propylene oxide, but the production time is long due to the continuous injection of the reactants, resulting in low productivity, which is difficult to use commercially.

According to Korean Patent No. 511087, in order to solve the problem of longer production time due to the continuous injection of the reactants, alkali metal hydroxides are added in primary and secondary portions, but alkylene is added when the primary alkali metal hydroxide is added. The entire amount of oxide is added in a batch, and when the secondary alkali metal hydroxide is added, the total amount of alkyl halide is added in a batch, and after the primary alkali metal hydroxide reaction, a diluent gas containing dialkyl ether is added. By adding a mixture to efficiently weaken the crystalline structure of the cellulose within a short time, the time required for the manufacturing process was shortened, and the yield of alkylene oxide reaction was partially improved, but the extent was negligible, and the yield of alkyl halide was almost Did not improve.

The present invention simplifies the production process of hydroxyalkylalkyl cellulose, shortens the production time and improves the reaction yield, which is economically advantageous as well as the production of high yield hydroxyalkylalkyl cellulose which can reduce the waste water load by reducing unreacted materials. Provide a method.

The present invention relates to a method for preparing hydroxyalkylalkyl cellulose by reacting cellulose with an etherifying agent,

0.5 to 4 mole ratio of alkali metal hydroxide to cellulose was added to the cellulose and stirred, and then 0.5 to 3 mole ratio of alkylene oxide was added to the cellulose, and the alkyl halide was added to the total amount of the first and second reactions. The first reaction with a weight ratio of ~ 95,

After completion of the first reaction, the alkali metal hydroxide is dispersed by adding 1 to 4 molar ratios of cellulose, and the second reaction is performed by adding 5 to 80 weight ratios of alkyl halides to the total amount of the first and second reactions. It provides a method for producing a high yield hydroxyalkylalkyl cellulose comprising a.

In the present invention, it is characterized in that the alkyl halide is divided into two times, which is because in addition to the purpose of increasing the yield of alkylene oxide, it has a key function in terms of physical properties, such as increasing the water retention and work time of the final product. As a result of optimizing the input ratio, the objective of the present invention was secured.

Treatment of cellulose with an alkali metal hydroxide before the alkylene oxide reacts with cellulose has three hydroxyl groups that can be chemically substituted in the cellulose, which are hard crystals by connecting cellulose chains by hydrogen bonding. It does not dissolve in hydrophilic components such as water and does not change its structure. Therefore, in order to induce chemical reactions, these hydroxyl groups must be activated. Alkali metal hydroxides can be activated by breaking these bonds as catalysts. Therefore, the alkali metal hydroxide is to determine the degree of substitution and thus can change the type of chemical to be replaced. Industrially used cellulose derivatives refer to the number of chemical substituents (eg methyl chloride) attached to a DS (Degree of Substitution) (AGU; Anhydrous Glucose Unit) in most cases. If all the reactions, the DS value is 3, DS is the maximum value 3. Also, depending on the type of the substituent (eg propylene oxide), there is a hydroxyl group having a reactivity, they react with cellulose Another hydroxyl group possessed in the substituent structure is activated to form a chain, such as two, three, not one, and the degree of reaction is expressed as the ratio of the number of moles of substituents per mole of cellulose units. This is called the MS (Molar Substitution), so that they are bound to insoluble cellulose Sodium is changed to water so that it can be used industrially, and the ratio of hydrophilicity and hydrophobicity varies depending on the degree and form of the substituents, and the physical properties exerted when mixed with cement, gypsum, sand, etc. The present invention is to provide an economically advantageous technology by providing a low supply price to the user by improving the yield while lowering the manufacturing cost while adjusting the physical properties.

The present invention will be described in more detail as follows.

In the present invention, the alkali metal hydroxide and the alkyl halide were added in two portions to prepare a high yield, highly substituted hydroxyalkylalkyl cellulose.

The substitution rate of the substituent varies depending on the treatment rate of alkali metal hydroxide in a certain amount of cellulose. In order to obtain a desired product and to obtain desired properties, the treatment rate of the alkali metal hydroxide is very important. The alkali metal hydroxide is used to weaken the crystalline structure of the hard cellulose so that the finely pulverized cellulose can easily react with the etherifying agent, and an alkali metal hydroxide in a solid or aqueous solution can be used. Sodium hydroxide (caustic soda), potassium hydroxide, lithium hydroxide and the like are used. The alkali metal hydroxides bind to cellulose and expand the crystal structure to help various chemicals bind or react. The alkali metal hydroxide amount should be treated at about 0.5 to 4 molar ratios, preferably about 0.5 to 2 molar ratios, relative to cellulose. At this time, the temperature is about 15 to 60 ° C., and the alkali metal hydroxide is uniformly dispersed in cellulose. It is important to spray. When the amount of alkali metal hydroxide used is less than 0.5 molar ratio relative to cellulose, the crystal structure of cellulose is weakened to a degree that is insufficient to react with alkylene oxide, so that not only the desired degree of substitution can be obtained but also the yield is lowered, and more than 4 molar ratio. Due to the excessive alkali metal hydroxide, alkylene oxide has a disadvantage in that the degree of substitution is lowered and the yield is also lowered than that of the reaction of cellulose with cellulose, thereby generating higher side reactions such as polypropylene glycol.

After a certain time of stirring after alkali metal hydroxide treatment, the cellulose is in a good state to bond with the alkylene oxide. At this time, a diluent gas is added and mixed evenly with stirring for about 10 minutes to 1 hour to allow the cellulose to react uniformly. The diluent gas is not particularly limited, but a diluent gas containing 65 to 95 weight ratio of dialkyl ether and 5 to 35 weight ratio of gas selected from methyl chloride, ethyl chloride and propyl chloride is preferable.

The alkylene oxide is then added at a molar ratio of 0.3 to 3 moles relative to cellulose, preferably from 1 to 2.5 mole ratios of alkylene oxide, depending on the degree of substitution desired, and the alkyl halide is added to the total amount of the first and second reactions. It is added at a weight ratio of ~ 95, preferably 50-90, and reacted at 60 ° C to 110 ° C, preferably 60 ° C to 90 ° C to bond the alkylene oxide and the alkyl halide to cellulose. The alkylene oxide is generally one having 2 to 5 carbon atoms in the alkylene group, and preferably propylene oxide is used. The alkyl halide is generally one having from 1 to 24 carbon atoms in the alkyl group, preferably methyl chloride. When the alkyl halide is included in less than 20% by weight relative to the total amount of the total primary and secondary reactions, there is a problem that the substitution rate of the alkyl halide is low, so that it is difficult to obtain a desired product in a desired yield. There is a problem that the yield increase of the seed is insignificant and the properties of the product are also changed. The reaction time is 30 minutes to 2 hours, preferably 45 minutes to 1.5 hours.

When the reaction of the alkylene oxide and the alkyl halide is completed, the alkali metal hydroxide is treated secondly so that the unreacted hydroxy group in the cellulose crystal structure can react with the chemical. At this time, the alkali metal hydroxide used is 1 to 4 molar ratio compared to the cellulose and it is important to spray evenly. At this time, when the amount of the secondary alkali metal hydroxide is less than 1 mole ratio to cellulose, the alkyl halide may not react sufficiently, resulting in low alkoxy substitution degree and lower yield. Since excessive amounts are not economical as well as excessive moisture, salt production is promoted and the yield of alkylene oxide and alkyl halide is lowered. The primary addition rate of alkali metal hydroxide separation has a decisive effect on the yield of alkylene oxide, and a weight ratio of 20 to 70 weight ratio is appropriate for the total charge of the primary and secondary reactions. In the case of alkali treatment as described above, the hydroxy group in the cellulose is completely exposed to the outside of the crystal structure to be in a state of reacting well with the alkyl halide. An alkyl halide (generally methyl chloride, etc.) is added in an amount of 5 to 80 parts by weight, preferably 10 to 40 parts by weight based on the total amount of primary and secondary reactions, and 70 ° C to 120 ° C, preferably 80 ° C to When the reaction is performed at 100 ° C. for about 1 hour, a high yield of hydroxyalkylalkyl cellulose having a desired degree of substitution can be obtained.

The hydroxyalkylalkyl cellulose prepared by the above method has a high yield of hydroxyalkylalkyl cellulose not only having a uniform degree of substitution, but also having excellent insoluble matter content of 0.02% by weight or less, and having an alkoxy substitution degree of 15% to 35%. %, Hydroxyalkoxy substitution degree is 2% to 30%, preferably 3 to 25%, alkyl halide yield is 60 to 70%, alkylene oxide yield is 60 to 75% can be obtained.

The hydroxyalkylalkyl cellulose prepared by the above method has very suitable physical properties for joint compounds, tile cements and surfactants widely used in industry.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are intended to illustrate the present invention and do not limit the present invention.

Production Example  1: Preparation of hydroxypropylmethylcellulose

6 kg finely pulverized natural pulp is added to a high pressure reactor using a horizontal / vertical stirred high pressure reactor, and then 5.1 kg of a 50 wt% aqueous solution of caustic soda is sprayed evenly onto the pulp with stirring through a spray nozzle. As a diluent gas, 5.3 kg of a mixture of 95% by weight of dimethyl ether and 5% by weight of methyl chloride was added thereto, and then 0.68 kg of propylene oxide and 4.1 kg of methyl chloride were added at once, followed by stirring well. The reactor temperature is raised and then reacted at 90 ° C. for 1 hour. In this case, the reactor pressure is 10 kg / cm 2 or less.

After completion of the reaction, the reactor was cooled to 50 ° C for 10 minutes, and then 4.9 kg of 50 wt% caustic soda solution was evenly sprayed, followed by 2.0 kg of methyl chloride. When the addition was completed, the temperature was raised to 90 ° C and reacted for 30 minutes. When the reaction was completed, the pressure was released and then filtered using boiling water, dried and pulverized to prepare hydroxypropylmethylcellulose, which was used as Example 1.

Example 2 to Example 8 was carried out in the same manner as in Example 1, but the hydroxypropyl methyl cellulose was prepared by varying the amount of caustic soda and methyl chloride in the content of Table 1, Comparative Examples 1 to 3 is Table 1 As described above, hydroxypropylmethylcellulose was prepared in the same manner as in Example 1 without separately adding caustic soda or methyl chloride.

Caustic Soda Addition (kg) Methyl chloride addition amount (kg) Primary Secondary Primary Secondary Example 1 5.1 4.9 4.1 2.0 Example 2 5.1 4.9 4.5 1.6 Example 3 5.1 4.9 5.0 1.1 Example 4 5.1 4.9 5.5 0.6 Example 5 6.0 4.0 4.1 2.0 Example 6 6.0 4.0 4.5 1.6 Example 7 6.0 4.0 5.0 1.1 Example 8 6.0 4.0 5.5 0.6 Comparative Example 1 10.0 0.0 8.5 0.0 Comparative Example 2 11.0 0.0 9.5 0.0 Comparative Example 3 4.5 5.0 0.0 7.0

Experimental Example  1: Determination of substitution degree, yield and insoluble matter

The methoxy substitution degree and the hydroxypropoxy substitution degree were measured by gas chromatography, and the methyl chloride and propylene oxide yields were determined by calculating the ratio of cellulose to the amount charged, and the content of insoluble matter was Measured by a method using a turbidimeter, the viscosity was prepared in 2 (w / v)% aqueous solution and measured at 20 ℃, 20 rpm with a Brookfield viscometer, the results are shown in Table 2.

Methoxy substitution degree (%) Hydroxypropoxy substitution degree (%) Methyl chloride yield (%) Propylene Oxide Yield (%) Insoluble matter (% by weight) Example 1 28.5 6.5 61.2 62.5 0.015 Example 2 28.9 6.7 61.6 62.7 0.011 Example 3 29.0 6.6 61.6 62.5 0.017 Example 4 29.0 7.5 61.6 67.5 0.018 Example 5 28.6 6.9 61.2 65.4 0.012 Example 6 28.7 6.8 61.4 65.3 0.017 Example 7 28.8 7.0 61.5 66.5 0.013 Example 8 29.1 7.5 61.8 67.7 0.016 Comparative Example 1 26.1 3.5 41.3 22.1 1.02 Comparative Example 2 27.9 6.3 31.3 19.5 0.91 Comparative Example 3 20.8 4.2 45.2 16.7 1.95

As shown in Table 2, Examples 1 to 8 of the present invention not only have a uniform degree of substitution, but also have excellent quality as an insoluble substance content of 0.02% by weight or less, and a degree of methoxy substitution of 15% to 35. %, Hydroxypropoxy substitution degree was 2% to 30%, methyl chloride yield was 60-70%, propylene oxide yield was 60-75%, and high-substituted high yield hydroxypropylmethylcellulose could be obtained. there was.

As described in detail above, the present invention increases the degree of substitution of cellulose, but it is economically disadvantageous because the synthesis time is excessive by continuously injecting the reactants in order to obtain a high degree of substitution. Separation and addition of ly metal hydroxide and alkyl halide can be achieved to simplify the process and achieve the desired degree of substitution in high yield of 60% or more. In addition, it is an economically advantageous way to reduce the environmental load by improving the efficiency of the reactants to reduce the waste water inflow of the reactants.

Claims (7)

In the method for producing hydroxyalkylalkyl cellulose by reacting cellulose with an etherification agent, 0.5 to 4 mole ratio of alkali metal hydroxide to cellulose was added to the cellulose and stirred, and then 0.5 to 3 mole ratio of alkylene oxide was added to the cellulose, and the alkyl halide was added to the total amount of the first and second reactions. The first reaction with a weight ratio of ~ 95, After completion of the first reaction, the alkali metal hydroxide is dispersed by adding 1 to 4 molar ratios of cellulose, and the second reaction is performed by adding 5 to 80 weight ratios of alkyl halides to the total amount of the first and second reactions. Method for producing a high yield of hydroxyalkylalkyl cellulose comprising a. The method according to claim 1, The first reaction is carried out in the range 60 to 110 ℃, the secondary reaction is a method for producing a high yield of hydroxyalkyl alkyl cellulose, characterized in that carried out in the range of 70 to 120 ℃. The method according to claim 1, The alkylene oxide is a method for producing a high yield hydroxyalkyl alkyl cellulose, characterized in that the alkylene group has 2 to 5 carbon atoms. The method according to claim 1, The alkyl halide is a method for producing a high yield of hydroxyalkyl alkyl cellulose, characterized in that the alkyl group has 1 to 24 carbon atoms. The method according to claim 1, A method for producing a high yield hydroxyalkylalkyl cellulose, characterized in that the yield of alkylene oxide is 60 to 75%. The method according to claim 1, A method for producing a high yield of hydroxyalkylalkyl cellulose, characterized in that the yield of the alkyl halide is 60 to 70%. A hydroxyalkylalkyl cellulose prepared by any one method selected from claims 1 to 6.