Transparent guar gum and preparation method thereof

Abstract

The invention relates to the technical field of guar gum processing, and particularly discloses transparent guar gum and a preparation method thereof. The preparation method of the transparent guar gum comprises the following steps: preparing nano microspheres from cocamidopropyl betaine and methyl methacrylate, and reacting the nano microspheres with acrylic acid and azodiisobutyronitrile to obtain a functional filler; the preparation method comprises the following steps: preparing 2, 3-epoxypropyl dimethylammonium sulfate from epoxy chloropropane, dimethylamine and concentrated sulfuric acid, reacting the 2, 3-epoxypropyl dimethylammonium sulfate with guar gum powder and an auxiliary agent to obtain modified guar gum, stirring the modified guar gum and a functional filler in ethanol, and drying to obtain the transparent guar gum. The method provided by the invention is simple in steps, the zwitterionic transparent guar gum is directly obtained in one step, the prepared transparent guar gum has high transparency, good water solubility and dispersity and excellent thermal stability, and the application range of the zwitterionic transparent guar gum in the industrial field is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of guar gum modification, and more particularly to transparent guar gum and a preparation method thereof. Background Art

[0002] Guar gum is a natural polysaccharide primarily derived from the endosperm of the seeds of the legume guar. Its backbone consists of D-mannose linked by β-1,4-glycosidic bonds, while its side chains are D-galactose linked by α-1,6-glycosidic bonds. The ratio of mannose to galactose is 2:1. Due to its unique physicochemical properties, such as good water solubility, thickening properties, and biocompatibility, it is widely used in the food industry, pharmaceuticals, cosmetics, and oil production. However, due to the large number of galactomannan units in its molecular structure, traditional guar gum solutions are often opaque in untreated form, limiting its use in applications requiring high transparency. In recent years, with increasing consumer demand for product quality, particularly in the high-end skincare and personal care market, the development of new guar gums that maintain both good functionality and meet visual aesthetic demands (i.e., high transparency) has become a research hotspot.

[0003] Currently, the main methods for improving guar gum transparency fall into two categories: chemical modification and physical treatment. While chemical modification methods, such as enzymatic hydrolysis and oxidation treatment, can improve the transparency of guar gum solutions to a certain extent, these processes are often associated with high costs and technical complexity. For example, enzymatic hydrolysis requires precise control of reaction conditions to avoid excessive degradation, while oxidation treatment can introduce harmful byproducts or affect the safety of the final product. These chemical modifications can also destroy hydrophilic groups in the guar gum molecular structure or introduce chemical structures that hinder dispersion, thereby affecting its water solubility and dispersibility. Meanwhile, physical treatment methods, such as ultrasonic treatment and high-pressure homogenization, can effectively improve the homogeneity and transparency of guar gum solutions. However, at high temperatures, the treated guar gum may experience reduced structural stability and poor thermal stability. These limitations not only increase the complexity of the production process but also limit the potential for transparent guar gum to be applied in a wider range of industrial fields. Therefore, it is crucial to develop new methods that can both simplify the preparation process and significantly improve the overall performance of the product. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention has simple preparation steps and can directly obtain transparent guar gum in one step, thereby providing a transparent guar gum with high transparency, good water solubility and excellent thermal stability.

[0005] In a first aspect, the present invention provides a method for preparing transparent guar gum, which adopts the following technical solution:

[0006] A method for preparing transparent guar gum comprises the following steps:

[0007] S1. Preparation of functional fillers:

[0008] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature until a stable emulsion is formed, adding an initiator, stirring continuously at 80-95° C. for 4-6 hours, and then centrifuging, washing, and drying to obtain nanospheres;

[0009] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically treating for 30-60 minutes, adding acrylic acid and azobisisobutyronitrile, stirring at 60-70° C. for 2-3 hours under nitrogen protection, and then centrifuging, washing, and drying to obtain a functional filler;

[0010] S2. Preparation of transparent guar gum:

[0011] S21. Dissolve epichlorohydrin in ethanol, add dimethylamine aqueous solution dropwise, stir continuously at 40-60° C. for 3-5 hours, filter and wash, dissolve the intermediate product in water, add concentrated sulfuric acid dropwise, stir continuously at 40-60° C. for 3-5 hours, filter, wash, and dry to obtain 2,3-epoxypropyldimethylammonium sulfate;

[0012] S22, dissolving 2,3-epoxypropyldimethylammonium sulfate in an aqueous solution of 1-ethyl-3-methylimidazolium chloride, adding guar gum powder, sodium hydroxide and a carboxylating agent, stirring continuously at 40-60° C. for 3-5 hours, and then filtering and washing to obtain modified guar gum;

[0013] S23. Dissolve the modified guar gum in ethanol, add functional filler, and continue stirring at room temperature for 20-40 minutes, then dry to obtain transparent guar gum.

[0014] Preferably, the initiator in step S11 is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 1-3:1.

[0015] Preferably, in step S11, the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:5-10:2-4:0.5-1.5.

[0016] Preferably, in step S12, the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid and azobisisobutyronitrile is 1:8-15:1-3:1-3.

[0017] Preferably, in step S21, the molar ratio of epichlorohydrin, ethanol, dimethylamine aqueous solution and concentrated sulfuric acid is 1:5-10:1-2:0.5-1.

[0018] Preferably, the carboxylating agent in step S22 is at least one of sodium chloroacetate, succinic anhydride and acrylic acid.

[0019] Preferably, the ingredients in step S22 are 1-3 parts by weight of 2,3-epoxypropyldimethylammonium sulfate, 3-5 parts of 1-ethyl-3-methylimidazolium chloride, 15-20 parts of water, 5-8 parts of guar gum powder, 0.3-0.6 parts of sodium hydroxide and 1-2 parts of a carboxylating agent.

[0020] Preferably, in step S23, the components include 2-5 parts of modified guar gum, 5-10 parts of ethanol, and 0.3-0.5 parts of functional filler in parts by weight.

[0021] In a second aspect, the present application also provides a transparent guar gum, which adopts the following technical solution:

[0022] A transparent guar gum is prepared by the above preparation method.

[0023] In summary, the present invention has the following beneficial effects:

[0024] 1. The present invention proposes a method for preparing transparent guar gum. Nanospheres are produced by reacting cocamidopropyl betaine with methyl methacrylate, which are then reacted with acrylic acid to produce a functional filler. Simultaneously, 2,3-epoxypropyldimethylammonium sulfate is generated by reacting epichlorohydrin with dimethylamine. This is then reacted with guar gum powder and an additive to produce a modified guar gum. Finally, the modified guar gum and the functional filler are stirred in ethanol and dried to produce the transparent guar gum. The functional filler is obtained by carboxylating specific nanospheres and can be evenly distributed in the modified guar gum, promoting the uniform distribution of guar gum particles in the aqueous phase, effectively reducing light scattering, and significantly improving the transparency of the product. The introduction of 2,3-epoxypropyldimethylammonium sulfate imparts a zwitterionic structure to the transparent guar gum, imparting high-temperature stability. It also adds hydrophilic groups to the guar gum molecules, enhancing the guar gum's solubility and dispersibility in water. The entire preparation process minimizes the use of hazardous substances and employs mild reaction conditions, such as low-temperature polymerization under nitrogen protection, to reduce environmental impact and ensure product safety and biocompatibility. In summary, the transparent guar gum of the present invention not only has high transparency, good water solubility and dispersibility, but also has excellent thermal stability, conforming to the principles of green chemistry.

[0025] 2. Functional fillers are obtained by polymerizing cocamidopropyl betaine and methyl methacrylate in the presence of an initiator to form nanospheres, which are then carboxylated. The combination of ammonium persulfate and sodium bisulfite as initiators can control the polymerization rate and product molecular weight distribution, reduce side reactions, and improve product purity and performance. The carboxylation treatment allows the nanospheres to form a tight three-dimensional network structure, providing mechanical support at high temperatures to prevent softening or deformation. The introduction of groups enhances the water solubility and dispersibility of guar gum. Furthermore, the nanospheres are evenly distributed throughout the modified guar gum, reducing light scattering and significantly improving the transparency of the final product.

[0026] 3. Transparent guar gum is obtained by modifying guar gum powder with 2,3-epoxypropyldimethylammonium sulfate and a carboxylating agent in an aqueous solution of 1-ethyl-3-methylimidazolium chloride, adding functional fillers, and drying. 2,3-epoxypropyldimethylammonium sulfate is a zwitterionic compound. Its introduction into the guar gum molecule imparts additional cationic and anionic groups, enhancing its hydrophilicity and improving its high-temperature stability. The introduction of carboxyl groups by the carboxylating agent modulates the molecular chain structure and interactions of the guar gum, optimizing its rheological properties. 1-Ethyl-3-methylimidazolium chloride is an ionic liquid. As a reaction medium, its high polarity and good solubility can improve reaction efficiency. It also has low volatility and high thermal stability. Using it as a reaction medium can reduce the use of organic solvents, which is in line with the principles of green chemistry. The synergistic effect of the three not only simplifies the production process, but also significantly improves the overall performance of transparent guar gum, making it have high transparency, good water solubility and dispersibility, and excellent thermal stability, making it suitable for a variety of industrial applications. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Unless otherwise specified, the materials, reagents, etc. used in the Examples and Comparative Examples of the present invention can be obtained from commercial sources. The quantitative tests in the following examples were all repeated three times, and the data are the average or average ± standard deviation of the three repeated experiments.

[0029] Guar gum powder, brand: Sixinjie, CAS number: 9000-30-0, purchased from Shandong Aicai Biotechnology Co., Ltd.

[0030] Example 1

[0031] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0032] S1. Preparation of functional fillers:

[0033] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 400 r / min, stirring continuously at 80° C. for 6 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:5:2:0.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 1:1;

[0034] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 30 kHz for 60 min, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 400 r / min under nitrogen protection, stirring continuously at 60° C. for 3 h, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:8:1:1;

[0035] S2. Preparation of transparent guar gum:

[0036] S21. Dissolve epichlorohydrin in ethanol in a molar ratio of 1:5:1:0.5, add a 40% by mass aqueous solution of dimethylamine dropwise at a rate of 1 mL / min, control the stirring rate to 400 r / min, continue stirring at 40° C. for 5 h, filter and wash, dissolve the intermediate product in water, add a 95% by mass concentrated sulfuric acid dropwise at a rate of 1 mL / min, continue stirring at 40° C. for 5 h, filter, wash, and dry to obtain 2,3-epoxypropyldimethylammonium sulfate;

[0037] S22. Dissolve 3 parts of 1-ethyl-3-methylimidazolium chloride in 15 parts of water, add 1 part of 2,3-epoxypropyldimethylammonium sulfate, 5 parts of guar gum powder, 0.3 parts of sodium hydroxide and 1 part of sodium chloroacetate, control the stirring rate to 400 r / min, continue stirring at 40° C. for 5 hours, and then filter and wash to obtain modified guar gum;

[0038] S23. Dissolve 2 parts of modified guar gum in 5 parts of ethanol, add 0.3 parts of functional filler, control the stirring rate to 400 r / min, continue stirring at room temperature for 40 minutes, and then dry to obtain transparent guar gum.

[0039] Example 2

[0040] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0041] S1. Preparation of functional fillers:

[0042] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 450 r / min, stirring continuously at 85° C. for 5 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:6:3:0.8, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1;

[0043] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 35 kHz for 50 min, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 450 r / min under nitrogen protection, continuously stirring at 64° C. for 2.8 h, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:10:2:2;

[0044] S2. Preparation of transparent guar gum:

[0045] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:7:2:0.8, and a 45% by mass aqueous solution of dimethylamine was added dropwise at a rate of 1.5 mL / min, with a stirring rate of 450 r / min. The mixture was stirred at 45° C. for 4.5 h, and then filtered and washed. The intermediate product was dissolved in water, and 96% by mass concentrated sulfuric acid was added dropwise at a rate of 1.2 mL / min. The mixture was stirred at 45° C. for 4.5 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0046] S22. Dissolve 4 parts of 1-ethyl-3-methylimidazolium chloride in 16 parts of water, add 2 parts of 2,3-epoxypropyldimethylammonium sulfate, 6 parts of guar gum powder, 0.4 parts of sodium hydroxide and 1 part of succinic anhydride, control the stirring rate to 450 r / min, continue stirring at 45° C. for 4.5 hours, and then filter and wash to obtain modified guar gum;

[0047] S23. Dissolve 3 parts of modified guar gum in 6 parts of ethanol, add 0.4 parts of functional filler, control the stirring rate to 450 r / min, continue stirring at room temperature for 35 minutes, and then dry to obtain transparent guar gum.

[0048] Example 3

[0049] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0050] S1. Preparation of functional fillers:

[0051] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 500 r / min, stirring continuously at 90° C. for 5 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.2, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 2:1;

[0052] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 40 kHz for 35 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 500 r / min under nitrogen protection, continuously stirring at 67° C. for 2.4 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:12:3:2;

[0053] S2. Preparation of transparent guar gum:

[0054] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:8:1:0.8, and a 48% by mass aqueous dimethylamine solution was added dropwise at a rate of 2 mL / min, with a stirring rate of 500 r / min. The mixture was stirred at 55° C. for 3.5 h, and then filtered and washed. The intermediate product was dissolved in water, and 97% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 55° C. for 3.5 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0055] S22. Dissolve 4 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, add 2 parts of 2,3-epoxypropyldimethylammonium sulfate, 7 parts of guar gum powder, 0.5 parts of sodium hydroxide and 1 part of acrylic acid, control the stirring rate to 500 r / min, continue stirring at 55° C. for 3.5 hours, and then filter and wash to obtain modified guar gum;

[0056] S23. Dissolve 4 parts of modified guar gum in 8 parts of ethanol, add 0.4 parts of functional filler, control the stirring rate to 500 r / min, continue stirring at room temperature for 25 minutes, and then dry to obtain transparent guar gum.

[0057] Example 4

[0058] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0059] S1. Preparation of functional fillers:

[0060] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3:1;

[0061] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0062] S2. Preparation of transparent guar gum:

[0063] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0064] S22. Dissolve 5 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, add 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, control the stirring rate to 550 r / min, continue stirring at 60° C. for 3 hours, and then filter and wash to obtain modified guar gum;

[0065] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0066] Comparative Example 1

[0067] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0068] S1. Preparation of nanospheres:

[0069] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3:1;

[0070] S2. Preparation of transparent guar gum:

[0071] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0072] S22. Dissolve 5 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, add 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, control the stirring rate to 550 r / min, continue stirring at 60° C. for 3 hours, and then filter and wash to obtain modified guar gum;

[0073] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of nanospheres, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0074] Comparative Example 2

[0075] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0076] S1. Preparation of functional fillers:

[0077] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature until a stable emulsion is formed, adding ammonium persulfate thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5;

[0078] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0079] S2. Preparation of transparent guar gum:

[0080] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0081] S22. Dissolve 5 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, add 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, control the stirring rate to 550 r / min, continue stirring at 60° C. for 3 hours, and then filter and wash to obtain modified guar gum;

[0082] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0083] Comparative Example 3

[0084] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0085] S1. Preparation of functional fillers:

[0086] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding sodium bisulfite thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5;

[0087] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0088] S2. Preparation of transparent guar gum:

[0089] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0090] S22. Dissolve 5 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, add 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, control the stirring rate to 550 r / min, continue stirring at 60° C. for 3 hours, and then filter and wash to obtain modified guar gum;

[0091] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0092] Comparative Example 4

[0093] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0094] S1. Preparation of functional fillers:

[0095] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3:1;

[0096] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0097] S2. Preparation of transparent guar gum:

[0098] S21, by weight, dissolving 5 parts of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, adding 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, controlling the stirring rate to 550 r / min, stirring continuously at 60° C. for 3 h, and then filtering and washing to obtain modified guar gum;

[0099] S22. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0100] Comparative Example 5

[0101] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0102] S1. Preparation of functional fillers:

[0103] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3:1;

[0104] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0105] S2. Preparation of transparent guar gum:

[0106] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0107] S22, dissolving 5 parts by weight of 1-ethyl-3-methylimidazolium chloride in 18 parts of water, adding 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, and 0.6 parts of sodium hydroxide, controlling the stirring rate to 550 r / min, stirring continuously at 60° C. for 3 h, and then filtering and washing to obtain modified guar gum;

[0108] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0109] Comparative Example 6

[0110] A method for preparing transparent guar gum specifically comprises the following preparation steps:

[0111] S1. Preparation of functional fillers:

[0112] S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature to form a stable emulsion, adding an initiator thereto, controlling the stirring rate to 550 r / min, stirring continuously at 95° C. for 4 h, and then centrifuging and drying to obtain nanospheres, wherein the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:8:4:1.5, and the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3:1;

[0113] S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically dispersing at 45 kHz for 30 minutes, adding acrylic acid and azobisisobutyronitrile, controlling the stirring rate to 550 r / min under nitrogen protection, stirring continuously at 70° C. for 2 hours, and then centrifuging, washing, and drying to obtain a functional filler, wherein the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid, and azobisisobutyronitrile is 1:15:3:2;

[0114] S2. Preparation of transparent guar gum:

[0115] S21. Epichlorohydrin was dissolved in ethanol in a molar ratio of 1:10:2:1, and a 50% by mass aqueous dimethylamine solution was added dropwise at a rate of 2.5 mL / min, with a stirring rate of 550 r / min. The mixture was stirred at 60° C. for 3 h, and then filtered and washed. The intermediate product was dissolved in water, and 98% by mass concentrated sulfuric acid was added dropwise at a rate of 1.5 mL / min. The mixture was stirred at 60° C. for 3 h, and then filtered, washed, and dried to obtain 2,3-epoxypropyldimethylammonium sulfate.

[0116] S22, taking 18 parts of N,N-dimethylformamide, by weight, adding 3 parts of 2,3-epoxypropyldimethylammonium sulfate, 8 parts of guar gum powder, 0.6 parts of sodium hydroxide and 2 parts of sodium chloroacetate, controlling the stirring rate to 550 r / min, stirring continuously at 60° C. for 3 h, and then filtering and washing to obtain modified guar gum;

[0117] S23. Dissolve 5 parts of modified guar gum in 10 parts of ethanol by weight, add 0.5 parts of functional filler, control the stirring rate to 550 r / min, continue stirring at room temperature for 20 minutes, and then dry to obtain transparent guar gum.

[0118] Performance Testing

[0119] The following performance tests were performed on a transparent guar gum prepared in the above experiment:

[0120] 1. Apparent viscosity: The apparent viscosity of transparent guar gum was tested in accordance with GB / T 10247-2008. The test results are shown in Table 1.

[0121] 2. Light transmittance: Prepare a 0.5% aqueous solution, adjust the pH to below 6 with citric acid, and measure the transmittance using a spectrophotometer with a 1 cm cuvette at 600 nm using distilled water as a reference. The test results are shown in Table 1.

[0122] 3. Water-insoluble matter: The water-insoluble matter of transparent guar gum was tested according to SY / T 5764-2007. The test results are shown in Table 1.

[0123] 4. Temperature resistance: The samples of Examples 1-4 and Comparative Examples 1-6 were tested for temperature resistance. The viscosity at different temperatures was measured using a Haake rheometer. The test was stopped when the viscosity was less than 100 mPa·s. The corresponding temperature was the temperature resistance of transparent guar gum.

[0124] Table 1

[0125] Apparent viscosity / mPa·s Transmittance / % Water insoluble matter / % Temperature resistance / ℃ Example 1 3698 97.6 2.01 81 Example 2 3813 98.1 1.95 82 Example 3 3985 98.7 1.92 84 Example 4 4280 99.5 1.85 88 Comparative Example 1 2854 92.5 6.27 68 Comparative Example 2 3285 96.1 2.58 78 Comparative Example 3 3072 95.6 2.91 75 Comparative Example 4 2102 84.4 7.55 62 Comparative Example 5 2554 88.7 5.34 69 Comparative Example 6 2633 94.2 3.87 73

[0126] From the results shown in Table 1 above, it can be seen that the comprehensive properties of the transparent guar gum prepared in Examples 1-4 of the present invention are far superior to those in Comparative Examples 1-6.

[0127] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing transparent guar gum, characterized in that: The method comprises the following preparation steps: S1. Preparation of functional fillers: S11, dissolving cocamidopropyl betaine in deionized water, adding methyl methacrylate, stirring at room temperature until a stable emulsion is formed, adding an initiator, stirring continuously at 80-95° C. for 4-6 hours, and then centrifuging, washing, and drying to obtain nanospheres; S12, dispersing the nanospheres in tetrahydrofuran, ultrasonically treating for 30-60 minutes, adding acrylic acid and azobisisobutyronitrile, stirring at 60-70° C. for 2-3 hours under nitrogen protection, and then centrifuging, washing, and drying to obtain a functional filler; S2. Preparation of transparent guar gum: S21. Dissolve epichlorohydrin in ethanol, add dimethylamine aqueous solution dropwise, stir continuously at 40-60° C. for 3-5 hours, filter and wash, dissolve the intermediate product in water, add concentrated sulfuric acid dropwise, stir continuously at 40-60° C. for 3-5 hours, filter, wash, and dry to obtain 2,3-epoxypropyldimethylammonium sulfate; S22, dissolving 2,3-epoxypropyldimethylammonium sulfate in an aqueous solution of 1-ethyl-3-methylimidazolium chloride, adding guar gum powder, sodium hydroxide and a carboxylating agent, stirring continuously at 40-60° C. for 3-5 hours, and then filtering and washing to obtain modified guar gum; S23. Dissolve the modified guar gum in ethanol, add functional filler, and continue stirring at room temperature for 20-40 minutes, then dry to obtain transparent guar gum.

2. The preparation method of transparent guar gum according to claim 1, wherein In step S11, the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 1-3:

1.

3. The preparation method of transparent guar gum according to claim 1, wherein In step S11, the mass ratio of cocamidopropyl betaine, deionized water, methyl methacrylate and initiator is 1:5-10:2-4:0.5-1.

5.

4. The preparation method of transparent guar gum according to claim 1, wherein In step S12, the mass ratio of the nanospheres, tetrahydrofuran, acrylic acid and azobisisobutyronitrile is 1:8-15:1-3:1-3.

5. The preparation method of transparent guar gum according to claim 1, wherein In step S21, the molar ratio of epichlorohydrin, ethanol, dimethylamine aqueous solution and concentrated sulfuric acid is 1:5-10:1-2:0.5-1.

6. The preparation method of transparent guar gum according to claim 1, characterized in that, In step S22, the carboxylation reagent is at least one of sodium chloroacetate, succinic anhydride and acrylic acid.

7. The preparation method of transparent guar gum according to claim 1, wherein The pH range in step S22 is 9-11.

8. The method for preparing transparent guar gum according to claim 1, wherein In step S22, the components by weight include 1-3 parts of 2,3-epoxypropyldimethylammonium sulfate, 3-5 parts of 1-ethyl-3-methylimidazolium chloride, 15-20 parts of water, 5-8 parts of guar gum powder, 0.3-0.6 parts of sodium hydroxide, and 1-2 parts of a carboxylating agent.

9. The method for preparing transparent guar gum according to claim 1, wherein In step S23, the modified guar gum, the ethanol and the functional filler are 2-5 parts by weight, 5-10 parts by weight and 0.3-0.5 parts by weight.

10. A transparent guar gum, characterized in that: The transparent guar gum is prepared by the preparation method of any one of claims 1 to 9.