WO2019119208A1 - Hydroxypropyl guar gum, preparation method therefor and use thereof - Google Patents

Abstract

Provided are a hydroxypropyl guar gum, a preparation method therefor and the use thereof. The hydroxypropyl guar gum of the present application comprises the following preparation raw materials: a guar gum powder, an aqueous solution of sodium hydroxide, and propylene oxide, wherein the hydroxypropyl guar gum has a degree of hydroxypropyl molar substitution of 1 to 2, the mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5% to 30%, and the amount of the propylene oxide is 1 to 8 times the molar amount of the guar gum powder. The highly-substituted hydroxypropyl guar gum prepared in the present application has a high degree of hydroxypropyl molar substitution, which is 1 to 2; a 0.5% aqueous solution of the highly-substituted hydroxypropyl guar gum has a light transmittance at a wavelength of 600 nm of greater than 90%; and the highly-substituted hydroxypropyl guar gum has a good solubility and good thickening properties in a high concentration ethanol solution (the mass ratio of ethanol in the aqueous ethanol solution is 50% to 75%), and can be used as a thickening agent for an ethanol-based disinfecting gel.

Description

Hydroxypropyl guar and preparation method and use thereof Technical field

The application belongs to the technical field of daily chemicals, and relates to a hydroxypropyl guar and a preparation method and use thereof.

Background technique

Guar gum is a natural nonionic hydrophilic polygalactomannan extracted from the seeds of the leguminous plant (Cyamopsis tetragonoloba), mainly from India and Pakistan. The guar seeds used to prepare the guar gum consist of a pair of tough, non-brittle endosperm portions, commonly known as guar splits, with frangible embryos (germs) interposed therebetween. After dehulling, the seeds were cleaved and the germs were removed by sieving (43-47% of the seeds). The guar splits contain about 78-82% guar gum and a small amount of some proteinaceous materials, inorganic salts, water insoluble gums and cell membranes, as well as some residual seed epidermis and seed embryos.

Guar gum has a molecular weight of about 2 million. The molecule has a linear structure. The main chain contains D-mannose units, and the branches contain D-galactose units. The exact ratio of galactose to mannose varies with the growing season. Guar gum is highly dispersed in various types and salinities of hot and cold water and brine. Guar gum is used as an emulsifier, thickener, stabilizer, and is approved for a wide range of foods, cosmetics and pharmaceuticals.

Guar gum hydrates well in aqueous solutions, but with regard to solution clarity, alcohol solubility and improved thermal stability lead to the development of many chemically modified guar gums. Modified guar is a polymer obtained by chemically modifying guar gum. This chemical modification is often referred to as derivatization. This modification provides pendant groups on the guar polymer backbone. The pendant groups are typically attached to the backbone via an ether linkage. An average of three hydroxyl groups can be used for derivatization on D-mannose or D-galactose units in guar gum. The largest theoretical degree of substitution (DS) in this molecule is 3. Substitution of a hydroxyl group with an ether such as a hydroxypropyl group will allow the pendant group to extend, which may alter the solubility and other properties of the guar gum. The molar substitution (MS) is defined as the average number of hydroxyl-containing substituents per saccharide unit and may exceed three due to the additional availability of hydroxyl groups.

CN103641927A discloses a preparation method of instant guar gum suitable for continuous compounding under low temperature conditions, which is specifically prepared by using guar film for chemical modification and neutralization reaction in a kneader to obtain hydroxypropyl group. Guar film, adding nano-materials and surface treatment agents for surface modification to obtain surface-modified materials, and then applying surface-modified materials to four-roller rolling technology, secondary stretching and viscosity-increasing technology, and spoiler drying technology The airflow vortex micro-powder pulverization and sorting technology obtains the instant guar gum which is continuously mixed under low temperature conditions. However, this invention does not mention the problem of hydroxypropyl molar substitution and the sample has not been subjected to purification treatment.

CN103113486A discloses a sulfonic acid modified carboxymethyl hydroxypropyl guar and a preparation method and application thereof, the sulfonic acid modified carboxymethyl hydroxypropyl guar of the invention, wherein the structural formula is as follows: R = H, n = 0, 1, 2 or 3; or, R = OH, n = 0 to 6. The hydroxypropyl molar substitution degree in the invention is from 0.15 to 0.4.

CN104130337A discloses a method for preparing carboxymethylhydroxypropyl guar powder by a one-step method of guar film, which adds guar film to an organic solvent-water mixed solution, raises the temperature to 30-80 ° C, and adds hydrogen. Sodium oxide solution, alkalization reaction for 2 to 60 minutes, after the alkalization reaction is completed, the etherification agent is added, and the reaction is carried out at 30 to 80 ° C for 30 to 180 minutes, and after the reaction is finished, the temperature is lowered, filtered, washed, pulverized, and dried to obtain a finished product; The molar substitution of the hydroxypropyl groups involved is 0.8.

The degree of substitution of hydroxypropyl guar prepared in the prior art is generally low, and the solubility and thickening properties need to be further improved.

Summary of the invention

In a first aspect, in view of the deficiencies of the prior art, one of the objects of the present application is to provide a hydroxypropyl guar having a high degree of hydroxypropyl molar substitution of 1 to 2, having good solubility and thickening. Sex.

To this end, the application uses the following technical solutions:

A hydroxypropyl guar comprising the following raw materials: guar powder, aqueous solution of sodium hydroxide and propylene oxide; and the hydroxypropyl molar substitution of the hydroxypropyl guar is 1~ 2. The mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5 to 30%, and the amount of the propylene oxide is 1 to 8 times the molar amount of the guar powder.

Hydroxypropyl guar gum is a kind of guar gum derivative obtained by etherification reaction of guar gum with propylene oxide. Its dissolution rate, water insoluble content and stability are obviously better than guar collagen powder. . The molar substitution (MS) of hydroxypropyl is one of the main factors affecting the performance of hydroxypropyl guar. It should be noted that the high degree of substitution described in the present application means that the hydroxypropyl molar substitution degree of the guar gum is 1 or more, especially the hydroxypropyl molar substitution degree of the guar gum is 1-2.

Highly substituted hydroxypropyl guar is a derivative of natural polysaccharide guar gum, guar gum derivatives are widely used in the cosmetics industry, and the addition of guar gum derivatives can increase the skin feel of daily chemical products. In the present application, the mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5 to 30%, for example, the mass concentration of sodium hydroxide in the aqueous solution of the sodium hydroxide is 5%, 6%, 7%. , 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24 %, 25%, 26%, 27%, 28%, 29%, 30%. The propylene oxide is used in an amount of 1 to 8 times the molar amount of the guar powder, for example, the propylene oxide is used in an amount of 1 time, 2 times, or 3 times the molar amount of the guar powder. 4 times, 5 times, 6 times, 7 times, 8 times.

Further, the propylene oxide is used in an amount of 2 to 5 times the molar amount of the guar powder.

Further, the mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5 to 20%.

In a second aspect, the second object of the present application is to provide a method for preparing hydroxypropyl guar in the first aspect, which comprises the steps of: adding an aqueous solution of sodium hydroxide to the guar powder. And reacting propylene oxide in a divided manner with stirring to obtain the hydroxypropyl guar, wherein the sodium hydroxide has an aqueous solution having a mass concentration of 5 to 30%, the epoxy The amount of propane used is 1 to 8 times the molar amount of the guar powder.

Further, the total reaction time for the stepwise addition of propylene oxide is 1 to 5 hours, for example, the total reaction time for the propylene oxide addition is 1 h, 2 h, 3 h, 4 h, 5 h.

Further, when propylene oxide is added in portions, the amount of propylene oxide added is 1/4 to 1/3 of the total amount of propylene oxide added, for example, the amount of propylene oxide added in portions is propylene oxide added to the total amount. 1/4, 1/3 of the amount until all are added.

Further, the temperature of the reaction is 50 to 70 ° C, for example, the reaction temperature is 50 ° C, 55 ° C, 60 ° C, 65 ° C, 70 ° C.

Further, after the propylene oxide reaction is added in portions, the following steps are further included: after the propylene oxide reaction is added in portions, the temperature is lowered, the acid is neutralized, and the reacted product is washed with an acetone solution and dried under vacuum to obtain the hydroxypropyl group. Kegua gum.

Further, after adding an acid, it is neutralized to neutral, and the pH is about 7.

Further, the acid is one of acetic acid, hydrochloric acid and sulfuric acid.

Further, the drying temperature is 80 to 120 ° C, for example, the drying temperature is 80 ° C, 90 ° C, 100 ° C, 110 ° C, 120 ° C.

As a preferred embodiment of the preparation method of the hydroxypropyl guar of the present application, the preparation method comprises the steps of: adding an aqueous solution of sodium hydroxide to the guar powder, and stirring at a temperature of 50 to 70 ° C; Adding propylene oxide to react for 1 to 5 hours, lowering the temperature, adding acid to neutralization, and the product after the reaction is washed with acetone solution and dried under vacuum at 80 to 120 ° C to obtain the hydroxypropyl guar, wherein the hydrogen The concentration of sodium hydroxide in the aqueous solution of sodium oxide is 5 to 30%, and the amount of the propylene oxide is 1 to 8 times the molar amount of the guar powder.

In a third aspect, the third object of the present application is to provide a use of the hydroxypropyl guar in the first aspect, which uses the hydroxypropyl guar as an ethanol-based disinfecting gel thickener. The high-substituted hydroxypropyl guar prepared by the present application has a hydroxypropyl molar substitution MS ranging from 1 to 2. The prepared 0.5% high-substituted hydroxypropyl guar aqueous solution has a light transmittance of greater than 90% at a wavelength of 600 nm. In a high concentration aqueous solution of ethanol (high concentration means that the mass ratio of ethanol in the aqueous ethanol solution is 50% to 75%), it has good solubility and can be used as a thickener for an ethanol-based disinfecting gel. In the existing disinfectant gel formulation patent, a synthetic thickener, carbomer or hydroxypropylcellulose, is used to provide a viscosity in the aqueous phase of the high concentration alcohol. The high-substituted hydroxypropyl guar prepared by the present application provides good thickening ability and provides a good thickening system for the ethanol-based disinfecting gel; in addition to the conventional thickeners carbomer and hydroxypropylcellulose A new thickener for ethanol-based disinfecting gels has been added.

Compared with the prior art, the beneficial effects of the present application are:

(1) The high-substituted hydroxypropyl guar prepared by the present invention has a high degree of substitution with hydroxypropyl molar of 1 to 2; the transmittance of 0.5% high-substituted hydroxypropyl guar aqueous solution at a wavelength of 600 nm is greater than 90%.

(2) The high-substituted hydroxypropyl guar prepared by the present invention has good solubility and thickening property in a high concentration ethanol solution (the mass ratio of ethanol in the ethanol aqueous solution is 50% to 75%). Used as a thickener for ethanol-based disinfecting gels.

DRAWINGS

1 is a nuclear magnetic resonance spectrum of a guar powder in the prior art;

2 is a nuclear magnetic resonance spectrum of the high-substituted hydroxypropyl guar of Example 1 of the present application.

Detailed ways

The technical solutions of the present application are further described below with reference to the accompanying drawings 1 and 2, and by specific embodiments.

Example 1

162 g of guar powder, 100 g of a 25% aqueous solution of sodium hydroxide was added over 10 minutes, and the mixture was stirred for 15 minutes while being protected by a nitrogen atmosphere. Then, the mixture was heated to 70 ° C while a total of 160 g of propylene oxide was added in multiple portions, and the addition was completed in 2 hours and maintained at 70 ° C for 3 hours. The mixture was cooled to room temperature and neutralized to pH 7 by the addition of glacial acetic acid. The mixture was washed twice with 1000 ml of a 50% aqueous acetone solution and washed with 1000 ml of acetone; the solid was dried in vacuo and pulverized to give a high-substituted hydroxypropyl guar.

The high-substituted hydroxypropyl guar prepared by the present application has a hydroxypropyl molar substitution MS of 1.5. The viscosity of a solution of 1% high-substituted hydroxypropyl guar at 25 ° C is 1900 cp (Brookfield viscometer, 20 rpm), and the transmittance of a solution of 0.5% high-substituted hydroxypropyl guar at 600 nm 92%. The NMR spectrum of the raw material guar powder used is shown in Fig. 1. The NMR spectrum of the high-substituted hydroxypropyl guar prepared in the present application is shown in Fig. 2. Compared with Figure 1, there is a distinct characteristic peak at about 6.4 ppm in Figure 2, indicating that the hydroxypropyl group has been substituted into the molecular chain of guar gum.

Example 2-12

The amount of the raw material of the high-substituted hydroxypropyl guar was changed. The specific amount was as shown in Table 1. The procedure similar to that of Example 1 was repeated to obtain different MS values, and 1% high-substituted hydroxypropyl amide at 25 ° C. The viscosity of the solution of the gelatin and the light transmittance of the 0.5% high-substituted hydroxypropyl guar solution are shown in Table 2.

Table 1

Table 2

The high-substituted hydroxypropyl guar prepared in Examples 1-12 was used to prepare a transparent disposable sterilizing gel, and the specific formulation of the transparent disposable sterilizing gel is shown in Table 3. For the disinfectant effect in the disinfectant gel formulation, a well-recognized solution with an ethanol content of more than 60% and a chlorhexidine acetate content of 0.5% or more has a very excellent disinfecting effect.

table 3

Transparent disposable disinfectant gel raw materials	Percentage of mass (%)
Chlorhexidine acetate	0.5
Ethanol	60
Highly substituted hydroxypropyl guar	1.5
pH regulator	0.1
glycerin	5
water	Make up to 100

The transparent disposable disinfecting gel prepared according to the formulation of Table 3 was used as Example 13-24, and its viscosity (cp, Brookfield viscometer, 20 rpm) and light transmittance (600 nm) were measured. The experimental results are shown in Table 4.

Table 4

Example	Viscosity (cp)	Transmittance(%)
Example 13	10290	85
Example 14	12180	80
Example 15	11050	88
Example 16	9770	88
Example 17	12990	87
Example 18	10580	83
Example 19	12120	82

Example 20	8640	90
Example 21	13920	85
Example 22	12200	86
Example 23	11800	87
Example 24	13100	81

The high-substituted hydroxypropyl guar of the present application has a high degree of substitution with a hydroxypropyl group of 1 to 2; a 0.5% high-substituted hydroxypropyl guar aqueous solution has a light transmittance of greater than 90% at a wavelength of 600 nm. The high-substituted hydroxypropyl guar of the present application has good solubility and thickening property and can be used as a thickener for an ethanol-based disinfecting gel, and is particularly suitable for a high-concentration ethanol solution (the mass ratio of ethanol in an aqueous ethanol solution is 50). Thickeners from % to 75%).

The above embodiments are only used to describe the detailed method of the present application, and the present application is not limited to the above detailed methods, that is, it does not mean that the present application must rely on the above detailed methods to be implemented. It should be apparent to those skilled in the art that any modification of the present application, the equivalent replacement of each raw material of the product of the present application, the addition of an auxiliary component, the selection of a specific manner, and the like, are all within the scope of protection and disclosure of the present application.

Claims (13)

1. A hydroxypropyl guar comprising the following raw materials: guar powder, aqueous solution of sodium hydroxide and propylene oxide; and the hydroxypropyl molar substitution of the hydroxypropyl guar is 1~ 2. The mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5 to 30%, and the amount of the propylene oxide is 1 to 8 times the molar amount of the guar powder.
2. The hydroxypropyl guar according to claim 1, wherein the propylene oxide is used in an amount of from 2 to 5 times the molar amount of the guar powder.
3. The hydroxypropyl guar according to claim 1 or 2, wherein the aqueous solution of the sodium hydroxide has a mass concentration of sodium hydroxide of 5 to 20%.
4. A method for producing hydroxypropyl guar according to any one of claims 1 to 3, wherein the preparation method comprises the steps of: adding an aqueous solution of sodium hydroxide to the guar powder, The hydroxypropyl guar is obtained by adding propylene oxide in a divided manner with stirring, wherein the hydroxypropyl guar in the aqueous solution of the sodium hydroxide has a mass concentration of 5 to 30%, and the propylene oxide is The amount is 1 to 8 times the molar amount of the guar powder.
5. The production method according to claim 4, wherein the total reaction time in which the propylene oxide is added in portions is from 1 to 5 hours.
6. The process according to claim 5, wherein the propylene oxide is added in an amount of from 1/4 to 1/3 of the total amount of propylene oxide added each time the propylene oxide is added in portions.
7. The production method according to any one of claims 4 to 6, wherein the temperature of the reaction is from 50 to 70 °C.
8. The preparation method according to any one of claims 4 to 7, wherein after the stepwise addition of the propylene oxide reaction, the method further comprises the steps of: adding propylene oxide after the reaction, cooling, adding acid neutralization, and reacting. The product was washed with an acetone solution and dried in vacuo to give the hydroxypropyl guar.
9. The production method according to claim 8, wherein the acid is added to neutralize to neutrality.
10. The production method according to claim 9, wherein the acid is one of acetic acid, hydrochloric acid and sulfuric acid.
11. The production method according to claim 10, wherein the drying temperature is 80 to 120 °C.
12. The preparation method according to any one of claims 4 to 11, wherein the preparation method comprises the steps of: adding an aqueous solution of sodium hydroxide to the guar powder, stirring at a temperature of 50 to 70 ° C; Adding propylene oxide reaction for 1 to 5 hours, cooling, neutralization with acetic acid to neutrality, washing the product with acetone solution, drying at 80-120 ° C under vacuum to obtain the hydroxypropyl guar, and The mass concentration of sodium hydroxide in the aqueous solution of sodium hydroxide is 5 to 30%, and the amount of the propylene oxide is 1 to 8 times the molar amount of the guar powder.
13. Use of the hydroxypropyl guar according to any one of claims 1 to 3 as an ethanol-based disinfecting gel thickener.

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