WO2017034293A1 - Method for preparing cellulose ether - Google Patents

Abstract

According to one aspect of the present invention, a method for preparing a cellulose ether provides the steps of: setting the target gel point of a cellulose ether; selecting a cellulose ether material having a viscosity corresponding to the target gel point; and hydrolyzing the cellulose ether material.

Description

Method for producing cellulose ether

The present invention relates to a method for producing cellulose ether, and more particularly, to control the gel point of the cellulose ether by controlling the viscosity of the raw cellulose ether before hydrolysis without controlling the substitution rate of the cellulose ether. It relates to a method for producing a cellulose ether which can be.

Cellulose ethers are industrially very useful compounds used as thickeners, binders, repair agents, etc. in medicine, construction, paints and the like. Cellulose ethers are widely used in pharmaceutical excipients such as tablet coating, sustained release formulations, granule bonding, capsule formation, disintegration aid, and drug delivery aid due to their excellent thickening and film forming ability.

Aqueous solutions of cellulose derivatives, such as cellulose ethers, have different rheological properties such as viscosity / elasticity, depending on the conditions of use (mixing ratio, climate, process temperature, etc.). This is because major changes in the expression of major physical properties. The aqueous solution of cellulose ether has a viscosity at low temperature and elasticity at high temperature. The temperature point at which the effect of elasticity starts to exceed the viscosity effect is called a gel point. Thus, different gel points may be required for different applications.

In general, cellulose derivatives such as cellulose ethers are known to have different gel points depending on the type and degree of substitution. Therefore, conventionally, there was only a method of changing the substitution rate in order to obtain a gel point suitable for the purpose of use in the production of cellulose ether.

However, controlling the substitution rate of the cellulose ether may cause various problems such as degradation of the disintegration rate, weakening of the bond strength, and deterioration of film strength due to changes in physicochemical properties other than the gel point. Therefore, there is a need for a production method for controlling gel points without a numerical change in substitution rate.

One of the technical problems to be achieved by the technical idea of the present invention is to provide a method for producing a cellulose ether capable of adjusting the gel point of the cellulose ether without changing the substitution rate of the cellulose ether.

Method for producing a cellulose ether according to an embodiment of the present invention, the step of setting a target gel point of the cellulose ether, the step of selecting a raw cellulose ether having a viscosity corresponding to the target gel point and the raw cellulose ether Disintegrating.

For example, the raw cellulose ether having a viscosity corresponding to the target gel point may be selected according to Equation 1 below.

[Equation 1]

y = ax + b

(Where y is the target gel point (° C.), x is the viscosity (cps) of a 2% by weight aqueous solution of raw cellulose ether, measured with a Brookfield viscometer at 20 ° C., −0.0007 ≦ a ≦ −0.0003, 55.315 ≦ b) ≤57.315)

For example, the raw cellulose ether and the cellulose ether may be hydroxypropyl methyl cellulose.

For example, the cellulose ether may have a methoxyl group substitution rate of 19 to 30% by weight, and a hydroxypropoxyl group substitution rate of 4 to 12% by weight.

For example, the 2% by weight aqueous solution of the raw cellulose ether may have a viscosity of 100 to 5,600 cps with a Brookfield viscometer at 20 ° C.

For example, the 2% by weight aqueous solution of cellulose ether may have a viscosity of 2.4-18.0 cps with a Ubbelohde viscometer at 20 ° C.

For example, the 20% by weight aqueous solution of cellulose ether may be a gel point of 50 ~ 60 ℃ by Anton Paar Physica MCR 301 rheometer.

According to one embodiment of the present invention, a method for preparing cellulose ether may provide a method for preparing cellulose ether which can adjust the gel point of cellulose ether after hydrolysis without changing the substitution rate by adjusting the viscosity of the raw cellulose ether before hydrolysis. Can be.

1 is a flow chart showing a method for producing a cellulose ether according to an embodiment of the present invention.

Figure 2 is a graph showing the substitution rate of methoxyl group (MO) and hydroxypropoxy group (PO) of Examples 1 to 5 and Comparative Examples 1 to 4.

FIG. 3 is a graph plotting the viscosity of raw cellulose ethers before hydrolysis and the gel points of cellulose ethers after hydrolysis in Examples 1 to 5 to fit.

In the present specification, the methoxyl group or hydroxypropoxyl group substitution rate refers to the ratio of the sum of the atomic weights of the elements constituting each substituent among the sum of the atomic weights of the elements constituting the repeating unit of the substituted cellulose, as shown in the following Formula 1 . The same meaning is used below.

[Formula 1]

Wherein R is independently from each other -CH ₃ , -CH ₂ CH ₃ , -CH ₂ CH ₂ OH or -CH ₂ CHOHCH ₃ , n is an integer of 1 or more.

When cellulose ether is used as a substitute for gelatin capsules as a medicament, the manufacturing process of the capsule may include the following steps: 1) After dispersing cellulose ether in hot water and cooling it to a certain temperature, the cellulose Partially dissolving the ether, 2) warming up again to mix the additives, and 3) dipping into capsule pins after passing through a filtration net. At this time, if the gel point is low, there is little viscosity expression during the process, so that the additive is easy to mix, and if the gel point is high, it is easy to pass through the filter network. Therefore, the gel point control of cellulose ether is required to obtain the optimum efficiency according to the capsule manufacturing process.

In the case of hydroxypropyl methyl cellulose, the gel point is inversely proportional to the substitution rate of the methoxyl group and tends to be proportional to the hydroxypropoxyl group. Therefore, the gel point may be adjusted by adjusting the substitution rate thereof. However, when the substitution rate is adjusted, other physical and chemical properties other than the gel point may also be changed. Thus, a method of controlling the gel point without changing the substitution rate is required.

1 is a flow chart showing a method for producing a cellulose ether according to an embodiment of the present invention.

Referring to Figure 1, the method for producing a cellulose ether according to an embodiment of the present invention, the step of setting the target gel point of the cellulose ether (S1), adjusting the viscosity of the raw cellulose ether according to the target gel point (S2) and hydrolyzing the raw cellulose ether to form the cellulose ether (S3).

In setting the target gel point of the cellulose ether (S1), the gel point of the cellulose ether suitable for the desired application may be set as the target value. For example, if the desired application is hard capsule manufacturing, the target value of the gel point may be 50-60 ° C., specifically, 53-57 ° C.

In step (S2) of selecting a raw cellulose ether having a viscosity corresponding to the target gel point, the raw cellulose ether having a viscosity corresponding thereto may be selected according to the target value of the gel point. Here, the viscosity of the corresponding raw cellulose ether according to the target value of the gel point may be selected to satisfy the following relational expression (1).

[Equation 1]

y = ax + b

(Where y is the target gel point (° C.), x is the viscosity (cps) of a 2% by weight aqueous solution of raw cellulose ether, measured with a Brookfield viscometer at 20 ° C., −0.0007 ≦ a ≦ −0.0003, 55.315 ≦ b) ≤57.315)

Raw material cellulose ether is a raw material for obtaining the final cellulose ether to be applied in the application, and is a material having a higher viscosity than the cellulose ether. For example, the raw cellulose ether may be prepared by the following process: 1) adding cellulose, the main raw material, in a reaction solvent, 2) alkalizing a predetermined time by adding an alkaline agent to form alkaline cellulose, 3) After adding an etherification agent (for example, an alkylene etherification agent (ethylene oxide)), the reaction is carried out by raising the temperature. 4) After cooling, an oxidizing agent is added to neutralize the reaction. 5) Separation, filtration, drying and grinding are performed. Obtain raw cellulose ether in powder form.

At this time, the physical properties of the raw cellulose ether are represented by the viscosity, which can be controlled through the degree of polymerization of the cellulose used as a raw material. Therefore, by adjusting the degree of polymerization of cellulose in accordance with the target gel point value, it is possible to obtain a raw cellulose ether having a controlled viscosity.

In the step (S3) of hydrolyzing the raw cellulose ether, a raw cellulose ether having a viscosity selected according to a target gel point value may be hydrolyzed to obtain a cellulose ether having a desired gel point.

The hydrolysis is for obtaining a low viscosity cellulose ether by breaking the ether bond of the raw cellulose ether to reduce the degree of polymerization. The hydrolysis can be carried out, for example, by adding an acid catalyst such as hydrogen chloride gas or hydrogen halide gas to the raw cellulose ether on dry powder in a mixing device of a rotary mixer.

The raw cellulose ether and the cellulose ether may be hydroxyalkyl alkyl cellulose or hydroxyalkyl cellulose, and specifically, hydroxypropyl methyl cellulose or hydroxypropyl cellulose. (hydroxypropyl cellulose).

When the raw cellulose ether and the cellulose ether are hydroxypropyl methyl cellulose, the methoxyl group substitution rate of the raw cellulose ether may be 19-30 wt%, and the hydroxypropoxy group substitution rate may be 4-12 wt%. . In addition, the raw material cellulose ether 2% by weight aqueous solution may have a viscosity of 100 ~ 5,600 cps with a Brookfield viscometer at 20 ℃, the cellulose ether 2% aqueous solution is Ubbelohde at 20 ℃ Viscometer may have a viscosity of 2.4 ~ 18.0 cps. In addition, the 20% by weight aqueous solution of cellulose ether may have a gel point of 50 ~ 60 ℃ by Anton Paar Physica MCR 301 rheometer.

Hereinafter, embodiments of the present invention will be described in detail.

The embodiments may be modified in other forms or various embodiments may be combined with each other, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments are provided to more completely explain the present invention to those skilled in the art.

Example  1-5 and Comparative example  1 ~ 4

Examples 1 to 5 and Comparative Examples 1 to 4 are about 0.2 to about 0.3 ~ 3 in the ENG Lab reactor system 10L equipment of Samsung Fine Chemical raw material hydroxypropyl methyl cellulose having different viscosity as shown in Table 1 below It is a cellulose ether obtained by adding about 1.0 kg to about 0.5 ~ 2L of Hanyang synthesis gas hydrochloric acid gas at 70 ~ 80 ° C, and then hydrolyzing for 30 ~ 90 minutes.

Table 1 below shows the viscosity of raw material cellulose ether of Examples 1 to 5 and Comparative Examples 1 to 4, the substitution rate of raw cellulose ether, the viscosity of cellulose ether, and the gel point of cellulose ether.

	Viscosity of raw cellulose ether (cps)	Methoxyl group		Hydroxypropoxyl group		Viscosity of Cellulose Ether (cps)	Gel point of cellulose ether (℃)
		Substitution rate (wt%)	Classification	Substitution rate (wt%)	Classification
Example 1	155	28.86	medium	8.96	medium	4.53	56.27
Example 2	327	28.90	medium	9.08	medium	4.48	56.20
Example 3	2.529	28.77	medium	8.96	medium	4.63	54.85
Example 4	3,785	28.86	medium	8.98	medium	4.50	54.45
Example 5	4,229	28.76	medium	9.01	medium	4.58	54.28
Comparative Example 1	152	29.09	Go	9.28	Go	4.48	55.89
Comparative Example 2	159	29.11	Go	8.68	that	4.50	55.01
Comparative Example 3	148	28.39	that	9.49	Go	4.52	56.69
Comparative Example 4	145	28.46	that	8.90	that	4.48	56.19

Referring to Table 1, the raw cellulose ethers used in Examples 1 to 5 do not differ greatly from each other in the substitution rate of the methoxyl group and the hydroxypropoxyl group. However, the raw cellulose ethers used in Comparative Examples 1 to 4 are not, which can be confirmed through FIG. 2.

Figure 2 is a graph showing the substitution rate of methoxyl group (MO) and hydroxypropoxy group (PO) of Examples 1 to 5 and Comparative Examples 1 to 4.

Referring to FIG. 2, it can be seen that the methoxyl group (MO) substitution rate and the hydroxypropoxyl group (PO) substitution rate of Examples 1 to 5 both have values in the middle region of FIG. 2. On the other hand, it can be seen that the methoxyl group (MO) substitution rate and the hydroxypropoxyl group (PO) substitution rate of Comparative Examples 1 to 4 each have values of different regions as shown in FIG. 2.

Referring back to Table 1, through Comparative Examples 1 to 4, the gel point of the cellulose ether can be adjusted by controlling the substitution rate of the methoxyl group and the hydroxypropoxyl group, even though the viscosity of the raw cellulose ether is the same level. It can be seen that. Specifically, through Comparative Example 1 and Comparative Example 2, lowering the substitution rate of the hydroxypropoxyl group, the gel point is dropped, and through Comparative Example 1 and Comparative Example 3, it is understood that the gel point is increased by lowering the substitution rate of the methoxyl group Can be.

However, when looking at the relationship between the viscosity and the gel point of the raw material cellulose ether of Examples 1 to 5 shown in Table 1, although the substitution rate is almost unchanged, the gel point of the cellulose ether increases You can see that it is falling. This can be confirmed in detail through FIG. 3.

Figure 3 is a graph of the viscosity of the raw material cellulose ether before hydrolysis of Example 1 to Example 5 and the gel point of the cellulose ether after hydrolysis to fit the plot.

3, the gel point of the cellulose ether and the viscosity of the raw material is a cellulose ether, it can be seen that the correlation between the straight line having a negative slope of approximately after fitting the correlation coefficient (R ²⁾ is 0.9862. Specifically, the viscosity of the raw cellulose ether and the gel point of the cellulose ether satisfy the following relational expression.

[Equation 2]

y = -0.0005x + 56.315

(Where y is the gel point of cellulose ether (° C.) and x is the viscosity (cps) of 2 wt% aqueous solution of raw cellulose ether as measured by Brookfield viscometer at 20 ° C.)

From this, it can be seen that by adjusting the viscosity of the raw cellulose ether without adjusting the substitution rate of the raw cellulose ether, a cellulose ether having a gel point suitable for each application can be obtained.

The present invention described above is not limited to the above-described embodiment, and various substitutions, modifications, and alterations are possible within the scope without departing from the technical spirit of the present invention. It will be obvious to him.

Claims (7)

1. Setting a target gel point of cellulose ether;

   Selecting a raw cellulose ether having a viscosity corresponding to the target gel point; And

   Hydrolyzing the raw cellulose ether; Method of producing a cellulose ether comprising a.
2. The method of claim 1,

   The raw material cellulose ether having a viscosity corresponding to the target gel point is selected according to Equation 1 below.

   [Equation 1]

   y = ax + b

   (Where y is the target gel point (° C.), x is the viscosity (cps) of a 2% by weight aqueous solution of raw cellulose ether, measured with a Brookfield viscometer at 20 ° C., −0.0007 ≦ a ≦ −0.0003, 55.315 ≦ b) ≤57.315)
3. The method of claim 1,

   The raw material cellulose ether and the cellulose ether are hydroxypropyl methyl cellulose (hydroxypropyl methyl cellulose) method for producing a cellulose ether, characterized in that.
4. The method of claim 3,

   The raw cellulose ether has a methoxyl group substitution rate of 19 to 30% by weight, and a hydroxypropoxyl substitution rate of 4 to 12% by weight.
5. The method of claim 3,

   2% by weight aqueous solution of the raw cellulose ether has a viscosity of 100 ~ 5,600 cps with a Brookfield viscometer at 20 ℃.
6. The method of claim 3,

   The 2% by weight aqueous solution of the cellulose ether has a viscosity of 2.4 ~ 18.0 cps with a Ubbelohde viscometer at 20 ℃.
7. The method of claim 3,

   20% by weight aqueous solution of the cellulose ether is a method of producing a cellulose ether, characterized in that it has a gel point of 50 ~ 60 ℃ by Anton Paar Physica MCR 301 rheometer.

Images