A method for preparing a high viscosity cationic starch

Abstract

The application discloses a preparation method of high-viscosity cationic starch and belongs to the technical field of modified starch, which is composed of the following steps: epichlorohydrin crosslinking, ball milling and cationization; the epichlorohydrin crosslinking comprises the following steps: mixing starch, calcium hydroxide and deionized water, stirring at 40-50 DEG C, adding sodium stearoyl lactylate, stirring at 50-55 DEG C, naturally cooling to room temperature, adding sodium chloride and epichlorohydrin, stirring, dropwise adding potassium hydroxide aqueous solution, stirring, adjusting the pH value to 6, filtering, washing and drying the filter residue to obtain crosslinked starch; the ball milling comprises the following steps: mixing calcium hydroxide, sucrose fatty acid ester SE-11 and deionized water and then ball milling to obtain a ball milling material; the high-viscosity cationic starch prepared by the method has high paste viscosity and cationic substitution degree, good stability of paste viscosity, uniform substitution degree and paste viscosity, and high reaction efficiency in cationization and low alkali consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of modified starch, and particularly relates to a preparation method of high-viscosity cationic starch. BACKGROUND

[0002] Starch is a natural high-molecular carbohydrate composed of a single type of sugar unit, and its basic unit is α-D-glucopyranose. After the water molecules are removed from the glucose, the starch molecules are formed by the glycosidic bond. Starch generally exists in the form of particles with a diameter of 1-10 μm or larger. These starch particles are mainly deposited in the seeds, tubers and roots of plants. Starch is not a homogeneous substance, but is composed of two very different polymers, amylose and amylopectin. The amylose is a linear polymer with a molecular weight of several hundred thousand to several million, and the glucose remaining groups are connected by α-D-(1→4) glycosidic bonds. The amylopectin is a branched polymer with a molecular weight of several million, and most of the glucose remaining groups are connected by α-D-(1→4) glycosidic bonds, and 2-4% of the glucose remaining groups are connected by α-D-(1→6) glycosidic bonds.

[0003] Natural starch is a water-soluble polymer, and although it has certain adhesion, film-forming properties and other characteristics, it is used in industry, but the characteristics are very limited, especially cannot meet the requirements of modern new technology, new process and new equipment. In order to improve the performance of starch, the most commonly used method at present is to modify the natural starch to prepare starch derivatives, for example: by oxidizing the natural starch to obtain oxidized starch with good bonding properties, so as to be applied in the preparation of adhesives; by grafting cationic groups on the natural starch to obtain cationic starch with strong adsorption capacity to negatively charged substances, so as to be applied in the preparation of papermaking strengthening agent, retention aid and filter aid; by grafting hydrophobic groups on the natural starch to obtain hydrophobic starch, so as to be applied in the preparation of biodegradable plastics. Now the starch derivatives have been widely used in various industries.

[0004] Cationic starch is prepared by reacting starch with cationizing reagents such as amino, imino, ammonium or phosphonium under alkaline conditions. The commonly used cationizing reagents are 3-chloro-2-hydroxypropyl trimethyl ammonium chloride and 2,3-epoxypropyl trimethyl ammonium chloride. In alkaline medium, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride can be converted into 2,3-epoxypropyl trimethyl ammonium chloride by removing one molecule of hydrogen chloride. As described in the article by Guo, Preparation and Application of Cationic Starch with High Degree of Substitution, Dalian University of Technology, December 2000, the commonly used cationizing reagent in the past was 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, while the cationizing reagent used in most of the research reports in recent years is 2,3-epoxypropyl trimethyl ammonium chloride. The reason for this is that when 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is used, it is necessary to convert it into 2,3-epoxypropyl trimethyl ammonium chloride in the reaction process, which requires at least one mole of alkali. This will inevitably result in the inclusion of a large amount of salt in the reaction product, and a large amount of solvent is required to remove the salt impurities, which increases the cost and causes environmental pollution. Furthermore, the reaction efficiency of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is lower. Therefore, the most commonly used cationizing reagent at present is 2,3-epoxypropyl trimethyl ammonium chloride.

[0005] As described in the article by Guo, Preparation and Application of Cationic Starch with High Degree of Substitution, Dalian University of Technology, December 2000, the commonly used methods for preparing cationic starch at present are organic solvent method, aqueous solvent method and dry method. The organic solvent method and the aqueous solvent method have the advantages of mild reaction conditions, simple production equipment and high reaction conversion rate. However, the organic solvent method and the aqueous solvent method have the following disadvantages: first, the cationizing reagent used must be purified, otherwise the residual epichlorohydrin and by-products will affect the quality of the cationic starch; second, chemical reagents such as catalysts and anti-gel agents must be added during preparation; third, the post-treatment is complex and a large amount of water is required for washing and drying. The dry method is to spray a mixture of cationizing reagent and alkali onto dry starch and stir at 60-80°C to obtain cationic starch. Compared with the organic solvent method and the aqueous solvent method, the dry method has the following advantages: first, the cationizing reagent used does not need to be purified; second, no additional chemical reagents are required during preparation; third, the post-treatment is simple and there is basically no problem of three wastes. In addition, the dry method also has the advantages of mild reaction conditions and high conversion rate. Therefore, in the preparation of cationic starch, especially in the preparation of cationic starch with high degree of substitution, the dry method is the most widely used preparation method at present.

[0006] For the technical indicators of cationic starch, as described in the above-mentioned, the most important technical indicators are the degree of substitution and the paste viscosity, wherein the paste viscosity is an easily measured indicator that can reflect the performance characteristics of the cationic starch. The paste viscosity can not only reflect the degree of substitution of the cationic starch, but also reflect the degradation degree of the starch in the preparation reaction of the cationic starch and the cross-linking degree of the cationic starch. The paste viscosity and the degree of substitution have a good mutual relationship under certain conditions. The increase of the degree of substitution causes the rapid increase of the paste viscosity, which is due to the result of the strengthened interaction between the quaternary ammonium cation and the hydroxyl group of the starch. When the temperature and the water content of the paste are constant, the higher the paste viscosity is, the higher the degree of substitution and the molecular weight of the cationic starch are, and the greater the cross-linking degree is.

[0007] Further, as described in the above-mentioned, there is a certain mutual relationship between the degree of substitution and the paste viscosity. The degree of substitution can be inferred by conveniently testing the paste viscosity. Moreover, the test of the paste viscosity can be completed within half an hour, while the test of the degree of substitution takes a long time. Therefore, the test of the paste viscosity can be used as a simple method for the industrial production control of the cationic starch. Thus, the high-viscosity cationic starch has the characteristics of high degree of substitution, high molecular weight and large cross-linking degree. At present, the demand for the high-viscosity cationic starch is increasing, especially when the cationic starch is used as a fixing agent, a retention aid, a flocculating agent, a dewatering agent, a dispersing agent and a natural sizing material. In these cases, the cationic starch needs to have high degree of substitution and high molecular weight, i.e. the high-viscosity cationic starch.

[0008] In addition, as described in the above-mentioned, the cationic starch is widely used as a wet-end additive in the papermaking industry to increase the strength of the paper and improve the retention ability of the fine particles, and is also a good filler. However, the viscosity of the cationic starch changes greatly between 50-95°C, which affects the stability of the paste viscosity of the cationic starch. The cross-linking can increase the paste viscosity and the stability of the paste viscosity. Further, the Chinese patent CN102382197B discloses a preparation method of the high-viscosity cationic starch. The three modification methods of etherification, cross-linking and acidification are organically combined, the process design is scientific and reasonable, and various chemical bonds are connected to the molecular structure of the starch, so that the starch paste has high viscosity and high acid and alkali stability. It is illustrated that, when the high-viscosity cationic starch is prepared, the appropriate cross-linking can improve the stability of the paste viscosity.

[0009] However, when the etherification and the cross-linking are combined and the high-viscosity cationic starch is prepared by the dry method, the following problems exist:

[0010] First, as described in Quanyi et al. Synthesis and functional properties of cross-linked cationic corn starch. Journal of Jiangsu University of Science and Technology. December 1996, there are two methods for preparing cross-linked cationic corn starch, namely cationization first and then cross-linking, and cross-linking first and then cationization. In the former method, the viscosity of the prepared cross-linked cationic corn starch is greatly affected by the cross-linking agent, but in the latter method, since a large number of hydroxyl groups are available for cationization reaction after cross-linking, the effect of cross-linking on the cationization reaction rate is very small. Therefore, the commonly used method for preparing cross-linked cationic corn starch is cross-linking first and then cationization. However, as described in Gu Shuwei. Preparation and application research of high-substitution cationic starch. Dalian University of Technology. December 2000, when using the method of cross-linking first and then etherification, it is difficult for the cross-linked starch granules to swell or for the structure of the cross-linked starch to relax. If the degree of swelling of the starch granules or the relaxation of the starch structure is not sufficient, it is not conducive for the cationization reagent to penetrate into the starch granules, and therefore more alkali catalysts are needed. However, as described in Zhang Peng. Performance research of high-substitution cationic starch. Shandong University. May 2010, with the increase of the amount of alkali, the cationization reaction efficiency and the degree of substitution increase in direct proportion, but when the amount of alkali exceeds a certain degree, it will cause the hydrolysis reaction of the epoxy group and the quaternary amine group in the cationization reagent, and also accelerate the decomposition of the formed cationic starch, which in turn reduces the reaction efficiency. Further, it leads to the decrease of the reaction efficiency in cationization and the decrease of the paste viscosity of the prepared high-viscosity cationic starch.

[0011] Second, as described in Qi Xiaoyan et al. Research on preparation of cationic starch by new dry process. China Oils and Fats. February 2012, although the dry process has the advantages of less water consumption, high yield, and no pollution, the reaction reagent is difficult to penetrate into the interior of the starch granules, which leads to the non-uniformity of the degree of substitution of the prepared cationic starch, and further leads to the non-uniformity of the degree of substitution and the paste viscosity of the prepared high-viscosity cationic starch.

[0012] In view of the above problems, the commonly used method is as described in Feng Bo. Preparation of cross-linked cationic cassava starch and its application in Cr 6+Scientific and Technological and Engineering. March 2014 and as Luowenzheng et al. Microwave technology in the production of high viscosity and high degree of substitution cationic starch. China high-tech enterprises. December 2016, as described, by ultrasonic or microwave to promote the reaction of crosslinked starch and cationic reagent, to reduce the amount of alkali, promote cationic reagent into the interior of starch granules, but as Zhang Hui. Preparation method and the relationship between the physical and chemical properties of cationic starch and the distribution of substituent groups. Shandong Agricultural University. May 2016, as described, the uneven degree of distribution of substituent groups of cationic starch prepared by different processes: ultrasonic wet method > microwave dry method > dry method, the reason may be that the dry method destroys part of the starch crystalline region, so the molecular chain can enter the crystalline region, and the ultrasonic wet method and the microwave dry method are less destructive to the crystalline region, so most of the groups are distributed in the non-crystalline region, resulting in the concentration of group distribution, and the high degree of unevenness will lead to the degradation of amylopectin in the preparation, in addition, ultrasonic and microwave itself also exist which will lead to the degradation of amylopectin, further, the degradation of amylopectin will lead to the decrease of the viscosity of the paste of the prepared high viscosity cationic starch. SUMMARY

[0013] In view of the deficiencies of the prior art, the present application provides a preparation method of high viscosity cationic starch, which has high paste viscosity and cationic degree of substitution, good stability of paste viscosity, uniform degree of substitution and paste viscosity, high reaction efficiency in cationization and low alkali consumption.

[0014] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0015] A preparation method of high viscosity cationic starch, comprising the following steps: epichlorohydrin crosslinking, ball milling and cationization.

[0016] In the epichlorohydrin crosslinking, the starch, calcium hydroxide and deionized water are mixed, then stirred at 40-50℃ for 1-1.5h, the stirring speed is 100-300rpm, sodium stearoyl lactate is added, then stirred at 50-55℃ for 2-3h, naturally cooled to room temperature, sodium chloride and epichlorohydrin are added, stirred for 0.5-1h, then dropwise added with potassium hydroxide aqueous solution, continued to stir for 18-20h after the dropwise addition is completed, the pH value is adjusted to 6, filtered, the filter residue is taken, the filter residue is washed with deionized water for 2-3 times, dried, and crosslinked starch is obtained.

[0017] In the epichlorohydrin crosslinking, the starch is one of corn starch, cassava starch, wheat starch and potato starch.

[0018] The mass concentration of the potassium hydroxide aqueous solution is 80%.

[0019] The mass ratio of oven-dried starch, calcium hydroxide, deionized water, sodium stearoyl lactylate, sodium chloride, epichlorohydrin, and potassium hydroxide aqueous solution in starch is 100:0.45-0.5:150-160:0.6-0.7:2.8-3:0.4-0.5:11-12.

[0020] The potassium hydroxide aqueous solution is added dropwise over a period of 10-15 minutes.

[0021] Use glacial acetic acid to adjust the pH to 6.

[0022] The ball milling process involves mixing calcium hydroxide, sucrose fatty acid ester SE-11, and deionized water, followed by ball milling to obtain the ball milling material.

[0023] In the ball milling process, the mass ratio of calcium hydroxide, sucrose fatty acid ester SE-11, and deionized water is 0.45-0.5:0.5-0.6:9-10.

[0024] In ball milling, agate grinding balls with a diameter of 6mm are used, the ball milling speed is 400-450rpm, the ball-to-material ratio is 3-4:1, and the ball milling time is 10-15min;

[0025] The cationization process involves mixing ball milled material and cross-linked starch, stirring at 60-65°C for 10-15 minutes at a stirring speed of 200-300 rpm, adding a mixture of 2,3-epoxypropyltrimethylammonium chloride, potassium hydroxide, and deionized water, and continuing stirring for 3.5-4 hours. The mixture is then removed, the pH is adjusted to 6.5-7, dried, and repeatedly washed with an ethanol-water solution and filtered until the filtrate is free of chloride ions. After drying, high-viscosity cationic starch is obtained.

[0026] The mass ratio of the oven-dried starch in the starch used in the epichlorohydrin crosslinking, the calcium hydroxide used in the ball milling, and the 2,3-epoxypropyltrimethylammonium chloride, potassium hydroxide, and deionized water in the mixture used in the cationization is 100:0.45-0.5:54-56:28-30:52-55.

[0027] During the cationization process, a 1 mol / L hydrochloric acid aqueous solution is used to adjust the pH value to 6.5-7.

[0028] During drying, dry until the moisture content is 12-14%;

[0029] The volume concentration of the ethanol aqueous solution is 80%.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) As Xiao Luteng et al. Ca(OH)2 on the gel properties of rice starch. Food and fermentation industry. August 2022, as described, Ca 2+ At low concentrations, it can promote the dissolution of amylose and form a "cross-linking" complex with amylose molecules through van der Waals force, which enhances the mechanical strength of the swollen starch granules; As Gong Benqian et al. Effect of emulsifier on the aging properties of waxy wheat starch. China food additives. April 2012, as described, amylose and emulsifier can form a complex, and different emulsifiers can be compounded; First, the calcium ion is used to promote the dissolution of amylose, and then the emulsifier sodium stearoyl lactate is added, which can complex with amylose to fix it, and then cross-linking with epichlorohydrin to achieve uniform cross-linking between starches. As Tang Peipei et al. Effect of calcium hydroxide on corn starch gelatinization. Food science and technology. September 2016, as described, at a higher pH, calcium hydroxide can interact with starch and promote starch swelling, emulsifier sucrose fatty acid ester SE-11 can improve the flowability of calcium hydroxide by combining with it, and further complex with emulsifier sodium stearoyl lactate to further complex with amylose, to promote the relaxation of the starch structure, further, promote the penetration of cationizing reagents into the starch granules, shorten the cationization time, reduce the amount of alkali, and improve the uniformity of the cationization reaction;

[0032] (2) The preparation method of the present application has less alkali dosage; The viscosity of the 2% paste of the high-viscosity cationic starch prepared is 19100-21500 mPa•s, the nitrogen content is 3.012-3.124%, the degree of substitution is 0.506-0.535, the reaction efficiency is 87.63-90.93%, the paste viscosity thermal stability is 96.6-97.5%, and the paste viscosity and nitrogen content are uniform. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described.

[0034] The corn starch used in Examples 1-3 and Comparative Examples 1-3 is of the same production batch, and the moisture content of the corn starch is 12%, and the nitrogen content is 0.05%.

[0035] Example 1

[0036] A method for preparing high-viscosity cationic starch, specifically comprising the following steps:

[0037] Step 1: epichlorohydrin cross-linking

[0038] Put 113.6 g of corn starch (containing 100 g of absolute dry corn starch), 0.45 g of calcium hydroxide, 150 g of deionized water into a three-necked flask, control the temperature in the three-necked flask to 40℃, control the stirring speed to 100 rpm, stir for 1 h, then add 0.6 g of sodium stearoyl lactylate to the three-necked flask, control the temperature in the three-necked flask to 50℃, stir for 2 h, naturally cool the temperature in the three-necked flask to room temperature, add 2.8 g of sodium chloride, 0.4 g of epichlorohydrin to the three-necked flask, stir for 0.5 h, add 11 g of 80% mass concentration potassium hydroxide aqueous solution dropwise to the three-necked flask, control the dropwise time to be 10 min, continue to stir for 18 h after the dropwise addition is completed, add glacial acetic acid to adjust the pH value to 6, filter, take the filter residue, wash the filter residue with deionized water for 2 times, dry to obtain cross-linked starch;

[0039] Step 2: Ball milling

[0040] Put 0.45 g of calcium hydroxide, 0.5 g of sucrose fatty acid ester SE-11, 9 g of deionized water into a ball mill, use 6 mm diameter agate grinding balls, control the ball milling speed of the ball mill to 400 rpm, control the ball-to-material ratio to 3:1, ball mill for 10 min to obtain a ball milling material;

[0041] Step 3: Cationization

[0042] Put all the ball milling material obtained in step 2 and all the cross-linked starch obtained in step 1 into a mixer, control the temperature in the mixer to 60℃, control the stirring speed to 200 rpm, stir for 10 min, then add a mixed solution composed of 54 g of 2,3-epoxypropyltrimethylammonium chloride, 28 g of potassium hydroxide, 52 g of deionized water to the mixer, continue to stir for 3.5 h, take out, add 1 mol / L hydrochloric acid aqueous solution to adjust the pH value to 6.5, dry to a moisture content of 12%, then repeat the washing, filtering until the filtrate is free of chloride ions, and drying to obtain a high-viscosity cationic starch.

[0043] Example 2

[0044] A method for preparing a high-viscosity cationic starch, specifically comprising the following steps:

[0045] Step 1: Epichlorohydrin cross-linking

[0046] Put 113.6g of corn starch (containing 100g of absolute dry corn starch), 0.47g of calcium hydroxide, 155g of deionized water into a three-necked flask, control the temperature in the three-necked flask to 45℃, control the stirring speed to 200rpm, stir for 1.5h, then add 0.65g of sodium stearoyl lactylate into the three-necked flask, control the temperature in the three-necked flask to 52℃, stir for 2.5h, naturally cool the temperature in the three-necked flask to room temperature, add 2.9g of sodium chloride, 0.5g of epichlorohydrin into the three-necked flask, stir for 1h, drop 11.5g of 80% mass concentration potassium hydroxide aqueous solution into the three-necked flask, control the dropping time to 12min, continue to stir for 19h after the dropping is completed, add glacial acetic acid into the three-necked flask to adjust the pH value to 6, filter, take the filter residue, wash the filter residue with deionized water for 3 times, dry to obtain cross-linked starch;

[0047] Step 2: Ball milling

[0048] Put 0.47g of calcium hydroxide, 0.55g of sucrose fatty acid ester SE-11, 9.5g of deionized water into a ball mill, use 6mm diameter agate grinding balls, control the ball milling speed of the ball mill to 450rpm, control the ball-to-material ratio to 4:1, ball mill for 12min to obtain a ball milling material;

[0049] Step 3: Cationization

[0050] Put all the ball milling material obtained in step 2 and all the cross-linked starch obtained in step 1 into a mixer, control the temperature in the mixer to 62℃, control the stirring speed to 250rpm, stir for 12min, then add a mixed solution composed of 55g of 2,3-epoxypropyltrimethylammonium chloride, 29g of potassium hydroxide, 54g of deionized water into the mixer, continue to stir for 4h, take out, add 1mol / L hydrochloric acid aqueous solution to adjust the pH value to 6.5, dry to a moisture content of 12%, then repeat the washing, filtering until the filtrate is free of chloride ions, and drying to obtain high-viscosity cationic starch.

[0051] Example 3

[0052] A method for preparing high-viscosity cationic starch, specifically comprising the following steps:

[0053] Step 1: Epichlorohydrin cross-linking

[0054] Put 113.6 g of corn starch (containing 100 g of absolute dry corn starch), 0.5 g of calcium hydroxide, 160 g of deionized water into a three-necked flask, control the temperature in the three-necked flask to 50℃, control the stirring speed to 300 rpm, stir for 1.5 h, then add 0.7 g of sodium stearoyl lactylate into the three-necked flask, control the temperature in the three-necked flask to 55℃, stir for 3 h, naturally cool the temperature in the three-necked flask to room temperature, add 3 g of sodium chloride, 0.5 g of epichlorohydrin into the three-necked flask, stir for 1 h, add 12 g of 80% mass concentration potassium hydroxide aqueous solution into the three-necked flask dropwise, control the dropwise time to be 15 min, continue to stir for 20 h after the dropwise addition is completed, add glacial acetic acid into the three-necked flask to adjust the pH value to 6, filter, take the filter residue, wash the filter residue with deionized water for 3 times, dry to obtain cross-linked starch;

[0055] Step 2: Ball milling

[0056] Put 0.5 g of calcium hydroxide, 0.6 g of sucrose fatty acid ester SE-11, 10 g of deionized water into a ball mill, use 6 mm diameter agate grinding balls, control the ball milling speed of the ball mill to 450 rpm, control the ball-to-material ratio to 4:1, ball mill for 15 min to obtain a ball milled material;

[0057] Step 3: Cationization

[0058] Put all the ball milled material obtained in step 2 and all the cross-linked starch obtained in step 1 into a mixer, control the temperature in the mixer to 65℃, control the stirring speed to 300 rpm, stir for 15 min, then add a mixed solution composed of 56 g of 2,3-epoxypropyltrimethylammonium chloride, 30 g of potassium hydroxide, 55 g of deionized water into the mixer, continue to stir for 4 h, take out, add 1 mol / L hydrochloric acid aqueous solution to adjust the pH value to 7, dry to a moisture content of 14%, then repeat the washing, filtering until the filtrate is free of chloride ions, and dry to obtain high-viscosity cationic starch.

[0059] Comparative Example 1

[0060] The preparation method of the high-viscosity cationic starch is basically the same as that of Example 2, except that in step 1: epichlorohydrin cross-linking, the use of calcium hydroxide is omitted, and specifically step 1: epichlorohydrin cross-linking is changed to:

[0061] Put 113.6 g of corn starch (containing 100 g of absolute dry corn starch), 155 g of deionized water into a three-necked flask, control the temperature in the three-necked flask to 45℃, control the stirring speed to 200 rpm, stir for 1.5 h, then add 0.65 g of sodium stearoyl lactylate into the three-necked flask, control the temperature in the three-necked flask to 52℃, stir for 2.5 h, naturally cool the temperature in the three-necked flask to room temperature, add 2.9 g of sodium chloride, 0.5 g of epichlorohydrin into the three-necked flask, stir for 1 h, add 11.5 g of 80% mass concentration potassium hydroxide aqueous solution into the three-necked flask dropwise, control the dropwise time to be 12 min, continue to stir for 19 h after the dropwise addition is completed, add glacial acetic acid into the three-necked flask to adjust the pH value to 6, filter, take the filter residue, wash the filter residue with deionized water for 3 times, dry to obtain the cross-linked starch.

[0062] Comparative Example 2

[0063] The preparation method of the high-viscosity cationic starch is basically the same as that of Example 2, except that in step 1: epichlorohydrin cross-linking, the use of sodium stearoyl lactylate is omitted, and specifically, step 1: epichlorohydrin cross-linking is changed to:

[0064] Put 113.6 g of corn starch (containing 100 g of absolute dry corn starch), 0.47 g of calcium hydroxide, 155 g of deionized water into a three-necked flask, control the temperature in the three-necked flask to 45℃, control the stirring speed to 200 rpm, stir for 1.5 h, naturally cool the temperature in the three-necked flask to room temperature, add 2.9 g of sodium chloride, 0.5 g of epichlorohydrin into the three-necked flask, stir for 1 h, add 11.5 g of 80% mass concentration potassium hydroxide aqueous solution into the three-necked flask dropwise, control the dropwise time to be 12 min, continue to stir for 19 h after the dropwise addition is completed, add glacial acetic acid into the three-necked flask to adjust the pH value to 6, filter, take the filter residue, wash the filter residue with deionized water for 3 times, dry to obtain the cross-linked starch.

[0065] Comparative Example 3

[0066] The preparation method of the high-viscosity cationic starch is basically the same as that of Example 2, except that in step 2: ball milling, the use of sucrose fatty acid ester SE-11 is omitted, and specifically, step 2: ball milling is changed to:

[0067] Put 0.47 g of calcium hydroxide, 9.5 g of deionized water into a ball mill, use 6 mm diameter agate grinding balls, control the ball milling speed of the ball mill to 450 rpm, control the ball-to-material ratio to 4:1, ball mill for 12 min to obtain the ball milled material.

[0068] Test Example 1

[0069] The paste viscosity and nitrogen content of the high viscosity cationic starch prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and then the degree of substitution (DS) and reaction efficiency (RE%) were calculated according to the calculation method disclosed in the paper "Preparation and Application of High Substitution Cationic Starch", Dalian University of Technology, December 2000. In the calculation of the reaction efficiency, the weight of the starch used was the weight of the absolute dry corn starch, i.e. 100 g.

[0070] In the test of the paste viscosity of the high viscosity cationic starch, 2 g of cationic starch was dissolved in 98 g of water, and after standing for 24 h, the paste viscosity was tested at 25°C using a rotary viscometer. The rotor used in the test was No. 4 rotor, and the rotation speed was 12 rpm.

[0071] In the test of the nitrogen content of the high viscosity cationic starch, the Kjeldahl method was used.

[0072] The results of the paste viscosity, nitrogen content, and reaction efficiency are as follows (in the test of the paste viscosity and nitrogen content, 10 samples were taken, and the average value was taken, and in the calculation of the degree of substitution, the average nitrogen content was used for calculation):

[0073]

[0074] Further, after the test of the paste viscosity was completed, the paste was transferred into a constant temperature water bath, the stirring speed in the constant temperature water bath was controlled at 20 rpm, and the temperature was heated to 50°C, and the paste was kept at this temperature for 1 h, and then the paste viscosity was tested. Then, the paste viscosity was tested every 2 h, a total of 5 times (i.e. at 50°C, the paste was kept for 1 h, 3 h, 5 h, 7 h, and 9 h, respectively, and then the paste viscosity was tested). Then, the paste viscosity stability was calculated according to the following formula:

[0075] Paste viscosity stability = [1 - (maximum paste viscosity in 5 tests - minimum paste viscosity in 5 tests) / paste viscosity at 50°C for 1 h] x 100%;

[0076] The calculation results are as follows:

[0077]

[0078] Further, in order to verify the uniformity of the degree of substitution and paste viscosity of the high viscosity cationic starch prepared, in the test of the paste viscosity and nitrogen content, the difference between the maximum paste viscosity and the minimum paste viscosity, and the difference between the maximum nitrogen content and the minimum nitrogen content were calculated, and the calculation results are as follows:

[0079]

[0080] From the results of the test example, it can be seen that, compared with Comparative Examples 1-3, the high-viscosity cationic starch prepared in Example 1-3 has the advantages of high paste viscosity, high degree of substitution and reaction efficiency, good thermal stability of paste viscosity, and good uniformity of paste viscosity and nitrogen content.

[0081] Test Example 2

[0082] In order to verify the influence of the amount of alkali, the amount of potassium hydroxide used in step 3: cationization in Example 1-3 and Comparative Example 1-3 was multiplied by 1.2, and then the nitrogen content of the high-viscosity cationic starch prepared was tested. During the test, 10 samples were taken each time, and the average value was taken. The results are as follows:

[0083]

[0084] From the results of the test example, it can be seen that, after increasing the amount of alkali in cationization, the average nitrogen content of the high-viscosity cationic starch prepared in Example 1-3 fluctuates little, indicating that in the preparation method of Example 1-3, the starch has been fully expanded when the amount of alkali is low. However, in the preparation method of Comparative Example 1-3, the starch has not been fully expanded when the amount of alkali is low, which further affects the nitrogen content of the high-viscosity cationic starch prepared.

Claims

1. A process for the preparation of a high viscosity cationic starch, characterized in that, It is composed of the following steps: epichlorohydrin crosslinking, ball milling, cationization; The epichlorohydrin crosslinking, after mixing the starch, calcium hydroxide, deionized water, stirring at 40-50℃, adding sodium stearoyl lactylate, stirring at 50-55℃, naturally cooling to room temperature, adding sodium chloride, epichlorohydrin, stirring, adding potassium hydroxide aqueous solution dropwise, stirring, adjusting the pH value to 6, filtering, taking the filter residue, washing, drying, to obtain crosslinked starch; The ball milling, after mixing the calcium hydroxide, sucrose fatty acid ester SE-11, deionized water, ball milling, to obtain the ball milling material; The cationization, after mixing the ball milling material and crosslinked starch, stirring at 60-65℃, adding the mixed solution composed of 2,3-epoxypropyl trimethylammonium chloride, potassium hydroxide, deionized water, stirring, taking out, adjusting the pH value to 6.5-7, drying, repeating washing with ethanol aqueous solution, filtering to the filtrate containing no chloride ion, drying, to obtain high viscosity cationic starch.

2. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the epichlorohydrin crosslinking, the starch is one of corn starch, cassava starch, wheat starch, potato starch; The mass concentration of the potassium hydroxide aqueous solution is 80%.

3. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the epichlorohydrin crosslinking, the mass ratio of the absolute dry starch in the starch, calcium hydroxide, deionized water, sodium stearoyl lactylate, sodium chloride, epichlorohydrin, potassium hydroxide aqueous solution is 100:0.45-0.5:150-160:0.6-0.7:2.8-3:0.4-0.5:11-12.

4. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the epichlorohydrin crosslinking, the dropwise adding time of the potassium hydroxide aqueous solution is 10-15min; When adjusting the pH value to 6, use glacial acetic acid to adjust.

5. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the ball milling, the mass ratio of calcium hydroxide, sucrose fatty acid ester SE-11, deionized water is 0.45-0.5:0.5-0.6:9-10.

6. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the ball milling, the grinding ball uses agate grinding ball with a diameter of 6mm, the ball milling speed is 400-450rpm, the ball to material ratio is 3-4:1, and the ball milling time is 10-15min.

7. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the epichlorohydrin crosslinking, the mass ratio of the absolute dry starch in the starch used, the calcium hydroxide used in the ball milling, 2,3-epoxypropyl trimethylammonium chloride, potassium hydroxide, deionized water in the mixed solution used in the cationization is 100:0.45-0.5:54-56:28-30:52-55.

8. The process for the preparation of high viscosity cationic starch according to claim 1, characterized in that, In the cationization, when adjusting the pH value to 6.5-7, use 1mol / L hydrochloric acid aqueous solution to adjust; When drying, dry to a moisture content of 12-14%; The volume concentration of the ethanol aqueous solution is 80%.

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