阅读说明：本技术 一种氨基酸改性半乳甘露聚糖及其制备方法和应用 (Amino acid modified galactomannan and preparation method and application thereof ) 是由 王若琳 徐玉枫 盖军旗 牛春梅 于 2020-06-19 设计创作，主要内容包括：本发明涉及多糖改性技术领域,具体公开一种氨基酸改性半乳甘露聚糖及其制备方法和应用。所述制备方法至少包括如下步骤：将氨基酸溶于碱性溶液中,加入环氧氯丙烷,于50-60℃反应1-3h,得产物a；将半乳甘露糖和强碱加入醇溶液中使其充分溶胀,加入所述产物a,于40-60℃反应1-3h,洗涤,干燥,得所述氨基酸改性半乳甘露聚糖。本发明制备的氨基酸改性半乳甘露聚糖中含氨基酸官能团的取代度为0.3-1.5,质量含量1wt％的氨基酸改性半乳甘露聚糖水溶液的表观粘度为2500-3200mPa·s,能有效增稠各类氨基酸型表面活性剂,具有良好的皮肤相容性,可生物降解,刺激小,完全满足日化用品增稠剂的要求。(The invention relates to the technical field of polysaccharide modification, and particularly discloses an amino acid modified galactomannan and a preparation method and application thereof. The preparation method at least comprises the following steps: dissolving amino acid in alkaline solution, adding epoxy chloropropane, and reacting at 50-60 ℃ for 1-3h to obtain a product a; adding galactomannan and strong base into alcoholic solution to fully swell, adding the product a, reacting at 40-60 ℃ for 1-3h, washing, and drying to obtain the amino acid modified galactomannan. The amino acid functional group-containing substitution degree of the amino acid modified galactomannan prepared by the invention is 0.3-1.5, the apparent viscosity of the amino acid modified galactomannan aqueous solution with the mass content of 1 wt% is 2500-3200 mPa.s, and the amino acid modified galactomannan aqueous solution can effectively thicken various amino acid surfactants, has good skin compatibility, is biodegradable, has little irritation, and completely meets the requirements of daily chemical product thickeners.)

1. An amino acid modified galactomannan characterized by the chemical structural formula shown in formula I:

wherein n is 200-4000, R₁，R₂，R₃And R₄Are respectively selected from

2. As claimed in claim 1The amino acid-modified galactomannan is characterized in thatThe molar substitution degree of (a) is from 0.3 to 1.5.

3. A method of producing the amino acid-modified galactomannan of claim 1 or 2, comprising at least the steps of:

step a, dissolving amino acid in alkaline solution, adding epoxy chloropropane, and reacting at 50-60 ℃ for 1-3h to obtain a product a;

and b, adding galactomannan and strong base into an alcohol solution to fully swell the galactomannan, adding the product a, reacting at 40-60 ℃ for 1-3h, washing and drying to obtain the amino acid modified galactomannan.

4. The method of claim 3, wherein in step a, the alkaline solution is sodium hydroxide solution, and the molar ratio of amino acid to NaOH is 1: 1.5-2.

5. The process for the preparation of amino acid-modified galactomannan of claim 3, wherein in step a, the molar ratio of epichlorohydrin to amino acid is from 0.9 to 1:1.

6. the method of claim 3, wherein in step b, the strong base is sodium hydroxide or potassium hydroxide, and the amount of the substance added is 0.2 to 1 times the molar amount of the amino acid.

7. The method of claim 3, wherein the amino acid to galactomannan molar ratio is from 0.5 to 2: 1.

8. The method of claim 3, wherein in step b, the alcoholic solution is an aqueous solution of isopropanol, wherein the concentration of isopropanol is 70-80% by mass; and/or

In the step b, the swelling time is 30-60 min.

9. The method of claim 8, wherein the alcohol solution is added in an amount of 2 to 2.5 times the total mass of the strong base and the galactomannan in step b.

10. Use of the amino acid-modified galactomannan of claim 1 or 2 as a thickener for household chemicals.

Technical Field

The invention relates to the technical field of polysaccharide modification, in particular to amino acid modified galactomannan and a preparation method and application thereof.

Background

In the modern society, with the gradual depletion of petroleum resources, natural biodegradable materials are receiving more and more attention. The galactomannan, as a natural polymer material, has the advantages of low price, wide source, biodegradability and the like, and is widely applied in various fields. Galactomannan is formed by mannose linked by beta-1, 4-glycosidic bonds, galactose linked to the backbone by alpha-1, 6-glycosidic bonds, and every few mannose residues have an alpha-D-galactose linked to the backbone by 1,6 bonds. The galactomannan is mainly derived from fenugreek gum, guar gum, locust bean gum, tara gum, etc., all of which have galactomannans with different degrees of branching. The guar gum is the most viscous colloid in natural gum, has the defects of high content of water-insoluble substances, low dissolution rate, difficulty in controlling viscosity, poor heat resistance, medium resistance, weak shear resistance and the like, and greatly limits the application of the guar gum, so that modification of the guar gum has very important significance for expanding the application range of the guar gum.

Amino acid surfactants have the advantages of excellent surface activity, mildness, no allergy, high safety, strong antibacterial ability and the like, and therefore, the amino acid surfactants become important targets of people to select as thickeners for daily chemical products. However, the amino acid surfactants have large surface active head groups, generally only form spherical micelles, and are difficult to form closely arranged rod-shaped micelles, so that the thickening difficulty of the amino acid daily chemical products is high. In recent years, studies on modification of polysaccharides with amino acids have been focused.

However, few studies on amino acid-modified polysaccharides have been reported so far, and they are in the early stage of research. The modification method mainly reported is to modify polysaccharide by amino acid through Schiff base reaction, esterification reaction and the like. These modification methods not only require a large amount of organic solvents and require complicated operation steps, but also hardly retain amino groups and carboxyl groups of amino acids in the prepared amino acid-modified polysaccharides and hardly maintain the biological properties of amino acids.

Disclosure of Invention

Aiming at the problems that a large amount of organic solvents are needed, the operation is complicated and the prepared amino acid modified polysaccharide is difficult to retain the biological characteristics of amino acid in the existing amino acid modified polysaccharide method, the invention provides the amino acid modified galactomannan and the preparation method and the application thereof.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

an amino acid modified galactomannan having a chemical formula as shown in formula I:

wherein n is 200-4000, R₁，R₂，R₃And R₄Are respectively selected from

or-H, R is an alkyl chain, and R is₁，R₂，R₃And R₄Cannot be simultaneously-H or

Compared with the prior art, the amino acid functional group-containing substitution degree in the amino acid modified galactomannan provided by the invention is 0.3-1.5, the apparent viscosity of the amino acid modified galactomannan aqueous solution with the mass content of 1 wt% is 2500-3200mPa & s, the light transmittance is more than 90%, various amino acid type surfactants can be effectively thickened, the amino acid modified galactomannan has good skin compatibility, is biodegradable, has small stimulation and good thickening effect, and completely meets the requirements of daily chemical product thickeners.

As described above

Is an amino acid general formula, wherein R is an alkyl chain in the amino acid general formula.

Preferably, the

The molar substitution degree of (a) is from 0.3 to 1.5.

The invention also provides a preparation method of the amino acid modified galactomannan, which at least comprises the following steps:

step a, dissolving amino acid in alkaline solution, adding epoxy chloropropane, and reacting at 50-60 ℃ for 1-3h to obtain a product a;

and b, adding galactomannan and strong base into an alcohol solution to fully swell the galactomannan, adding the product a, reacting at 40-60 ℃ for 1-3h, washing and drying to obtain the amino acid modified galactomannan.

The preparation method of the amino acid modified galactomannan provided by the invention takes alcoholic solution as solvent and epichlorohydrin as a connecting agent, and adopts a two-step method to prepare the amino acid modified galactomannan. Firstly, reacting alkali-protected amino acid with epoxy chloropropane to make amino of amino acid and epoxy group of epoxy chloropropane undergo the process of ring-opening reaction to obtain product a, so that the epoxy chloropropane can be prevented from making galactomannan undergo the process of cross-linking reaction; then strong base is used for activating hydroxyl of semi-milk mannan through deprotonation reaction, and galactomannan oxyanion is used for etherification reaction with the product a, so that the reaction efficiency is high, amino and carboxyl groups of amino acid are retained, the biological characteristics of the amino acid are maintained, and the biodegradable macromolecular thickener which has obvious thickening effect on the amino acid surfactant is synthesized.

The principle of the invention for preparing the amino acid modified galactomannan is as follows:

the reaction formula of the reaction of the amino acid and the epichlorohydrin is shown as the formula (1) to the formula (2):

the reaction formula of the product a and galactomannan is shown as formula (3) to formula (4):

wherein R is₁，R₂，R₃And R₄Are respectively selected from

or-H, R is an alkyl chain, and R is₁，R₂，R₃And R₄Cannot be simultaneously-H or

Preferably, in step a, the alkaline solution is a sodium hydroxide solution, wherein the molar ratio of the amino acid to the NaOH is 1: 1.5-2.

Sodium hydroxide is added to react with the carboxyl of the amino acid, so that the self-polycondensation reaction of the amino acid in the reaction process is prevented, and the reaction efficiency of the amino acid and the epichlorohydrin is improved.

The preferable addition amount of the sodium hydroxide can not only prevent the self-polycondensation reaction of the amino acid, but also open the ring of the epichlorohydrin, thereby being beneficial to the full reaction of the epichlorohydrin and the amino acid.

More preferably, the mass concentration of the alkaline solution is 25 to 30%.

Preferably, in step a, the molar ratio of epichlorohydrin to amino acid is 0.9-1: 1.

the amount of the epoxy chloropropane is not more than the amino acid, so that the epoxy chloropropane can fully react with the amino acid, the amount of unreacted epoxy chloropropane is reduced, and the phenomenon that the unreacted epoxy chloropropane causes the galactomannan to generate a crosslinking reaction during the reaction is further avoided.

Preferably, in step b, the strong base is sodium hydroxide or potassium hydroxide, and the amount of the added substance of the strong base is 0.2-1 times of the molar amount of the amino acid.

And (b) adding alkali liquor to destroy hydrogen bonds in the semi-galactomannan, weakening acting force among molecular chains, enabling the molecular chains to become more stretched, facilitating the subsequent modification reaction, improving the reaction efficiency, and simultaneously activating hydroxyl groups of the semi-galactomannan by deprotonation reaction of strong base, so that the reaction efficiency of the product a and the galactomannan is improved.

The addition amount of strong base is small, so that hydrogen bonds among galactomannan molecules cannot be effectively destroyed, the hydroxyl groups of the galactomannan cannot be fully activated, and the reaction probability of amino acid is reduced; excessive addition of strong base results in degradation of the galactomannan molecules, which reduces the viscosity of the product. The preferable addition amount of the strong base can ensure that the product has high viscosity and transparency.

Preferably, the molar ratio of the amino acid to galactomannan is 0.5-2: 1.

Preferably, in step b, the alcohol solution is an aqueous solution of isopropanol, wherein the mass concentration of isopropanol is 70-80%.

Preferably, in step b, the alcohol solution is added in an amount of 2 to 2.5 times the total mass of the strong base and the galactomannan.

The addition of the preferred alcohol solution is beneficial to the full swelling of the galactomannan, and the reaction efficiency is improved.

Preferably, in step b, the swelling time is 30-60 min.

Preferably, the epichlorohydrin is added in step a by dropwise addition at a rate of 0.08-0.12 mL/min.

Preferably, in the step b, the reactant a is added in a dropwise manner, and the dropwise adding time is controlled to be 10-30 min.

The preferable mode of dripping in the step a and the step b can ensure the full progress of the reaction.

Optionally, the galactomannan of the present invention may be guar gum, tara gum, carob gum, guava gum, locust bean gum, and the like, all of which may achieve substantially equivalent results.

Alternatively, the amino acid of the present invention may be glycine, alanine, valine, leucine, isoleucine, phenylalanine, proline, tryptophan, serine, tyrosine, cysteine, methionine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine or histidine, and the conformations of the amino acids include L and D forms.

The invention also provides application of the amino acid modified galactomannan as a daily chemical product thickener.

Furthermore, the invention also provides the application of the amino acid modified galactomannan as an amino acid shampoo thickener.

At present, the thickening of an amino acid shampoo system is generally realized by selecting synthetic ester as a thickening agent, and through acid thickening, the viscosity of hydroxypropyl guar gum, carbomer and xanthan gum can be adjusted to below 1000mPa & s generally, so that the viscosity of the amino acid shampoo is low. The amino acid modified galactomannan prepared by the method is added into an amino acid shampoo system in an amount of 0.45 wt%, so that the viscosity of the shampoo can be increased to 2300mPa & s, and the requirement on the viscosity of the shampoo (more than 1500mPa & s) is completely met.

The invention takes natural degradable galactomannan as a matrix, takes the theoretical knowledge of high molecular structure and performance as guidance, only surrounds the hot problem which is urgently needed to be solved by daily chemical products, and adopts a reasonable and feasible green process to modify the galactomannan. Aiming at the technical problem that the amino acid surface active head groups are large and the compact rod-shaped micelles are not easy to form to cause the thickening difficulty of daily chemical products, the biodegradable macromolecular thickener with obvious thickening effect on the amino acid surfactant is synthesized by strictly controlling the process conditions, has high light transmittance and wide application prospect in the daily chemical products, and particularly has high application prospect in the field of amino acid shampoo thickeners.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In order to better illustrate the invention, the following examples are given by way of further illustration.