Preparation method of high-viscosity hydroxypropyl methylcellulose

Abstract

The present invention provides a preparation method of high-viscosity hydroxypropyl methylcellulose. A preparation method of high-viscosity hydroxypropyl methylcellulose comprises the following steps: grinding and alkalizing refined cotton cellulose; adding methyl chloride and propylene oxide for etherification reaction; successively adding a crosslinking agent and an aqueous fulvic acid solution for reaction; adding potassium naphthylacetate, sodium sulfite and sodium molybdate and then drying. In the present invention, during the etherification reaction of alkalized cellulose, a crosslinking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate is added for crosslinking reaction, which can reduce the content of water-soluble groups of the prepared hydroxypropyl methylcellulose, achieving the effect of increasing the viscosity of hydroxypropyl methylcellulose. Coating the crop surface with the high-viscosity hydroxypropyl methylcellulose not only has a better surface glazing effect, but also can increase its sugar content.

Description

Technical Field

[0001] The present invention relates to the technical field of cellulose preparation, and particularly relates to a preparation method of high-viscosity hydroxypropyl methylcellulose. Background Art

[0002] 1 Hydroxypropyl methylcellulose is one of the non-ionic cellulose mixed ethers. Due to its properties such as dispersion, emulsification, thickening, and adhesion, it is widely used in fields such as textiles, synthetic resins, medicine, and food.

[0003] 2 Most of the existing hydroxypropyl methylcellulose is prepared by alkalizing cotton fiber, adding propylene oxide and methyl chloride for etherification, and then undergoing pickling neutralization, dehydration drying, and pulverization. The hydroxypropyl methylcellulose prepared by this method has a low crosslinking degree, resulting in insufficient viscosity. Moreover, due to the high water solubility of this hydroxypropyl methylcellulose, its properties such as thickening, dispersion, emulsification, and adhesion are reduced in high-temperature or acid-base environments. In addition, it also results in poor surface glazing on crops.

[0004] 3 Therefore, we propose a preparation method of high-viscosity hydroxypropyl methylcellulose that has good surface glazing on crops and increases the sugar content of crops. Summary of the Invention

[0005] 4 Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a preparation method of high-viscosity hydroxypropyl methylcellulose.

[0006] A preparation method of high-viscosity hydroxypropyl methylcellulose includes the following steps:

[0007] S1: Grinding and alkalizing refined cotton cellulose

[0008] Adding refined cotton cellulose into a sodium hydroxide solution, grinding it through a grinder while alkalizing to obtain alkalized cellulose;

[0009] S2: Adding methyl chloride and propylene oxide for etherification reaction

[0010] Adding methyl chloride and propylene oxide into the alkalized cellulose, heating to 70 - 80 °C for etherification reaction to obtain intermediate A;

[0011] S3: Sequentially adding a crosslinking agent and an aqueous fulvic acid solution for reaction

[0012] Adding the crosslinking agent into intermediate A for crosslinking reaction to prepare intermediate B, and then adding the aqueous fulvic acid solution into intermediate B for neutralization reaction to obtain intermediate C;

[0013] S4: Adding potassium naphthylacetate, sodium sulfite, and sodium molybdate and then drying

[0014] Potassium naphthylacetate, sodium sulfite and sodium molybdate are added to the intermediate C, stirred and mixed, and then dried by passing hot air. After crushing and grinding, high-viscosity hydroxypropyl methylcellulose is obtained.

[0015] Furthermore, the grinding and alkalizing of the refined cotton cellulose in step S1 specifically comprises the following steps:

[0016] S1.1: adding sodium hydroxide solution into the grinder, heating the sodium hydroxide solution by a first heater until a temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30-40° C., and the temperature sensor sends a signal to the controller;

[0017] S1.2: After receiving the signal sent by the temperature sensor, the controller controls the feed assembly of the grinder to open, and adds the refined cotton cellulose into the grinder through the feed assembly;

[0018] S1.3: When the first gravity sensor in the grinder detects that the gravity in the grinder exceeds a preset gravity range, the first gravity sensor sends a signal to the controller;

[0019] S1.4: After receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalizes the refined cotton cellulose to obtain alkalized cellulose.

[0020] Furthermore, the step S2 of adding methyl chloride and propylene oxide to carry out etherification reaction specifically comprises the following steps:

[0021] S2.1: adding the alkalized cellulose obtained in step S1.4 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor no longer increases, and the second gravity sensor sends a signal to the controller;

[0022] S2.2: After receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add methyl chloride and propylene oxide into the reactor;

[0023] S2.3: until the second gravity sensor detects for the second time that the gravity in the reactor no longer increases, the second gravity sensor sends a signal to the controller again;

[0024] S2.4: After the controller receives the signal sent by the second gravity sensor for the second time, it controls the second heater in the reactor to turn on, heating the inside of the reactor to 70-80° C. to perform an etherification reaction to obtain intermediate A.

[0025] Furthermore, step S3 of sequentially adding a cross-linking agent and a fulvic acid aqueous solution to react specifically comprises the following steps:

[0026] S3.1: After heating for 2-3 hours, the controller controls the heating temperature of the heater to be adjusted to 50-60°C;

[0027] S3.2: The controller then controls the feeder to add the crosslinking agent to the intermediate A obtained in step S2.4 to perform a crosslinking reaction to obtain intermediate B;

[0028] S3.3: After the reaction time is 1-3 hours, the controller controls the heating temperature of the heater to be adjusted to 80-90°C;

[0029] S3.4: Add the fulvic acid aqueous solution to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6-7, and stop adding the fulvic acid aqueous solution to obtain the intermediate C.

[0030] Further, the step S4 of adding potassium naphthylacetate, sodium sulfite and sodium molybdate and then drying specifically comprises the following steps:

[0031] S4.1: Add potassium naphthylacetate, sodium sulfite and sodium molybdate to the intermediate C obtained in step S3.4, and stir and mix with a stirrer to obtain intermediate D;

[0032] S4.2: placing the intermediate D in an insulated box, and passing hot air at 120-150° C. into the insulated box through a hot air blower to dry the intermediate D;

[0033] S4.3: until the solid moisture online measuring instrument in the insulation box detects that the moisture content of the intermediate D is 0-2%, the solid moisture online measuring instrument sends a signal to the controller, and after the controller receives the signal sent by the solid moisture online measuring instrument, it controls the hot air blower to turn off;

[0034] S4.4: Add the dried intermediate D into a grinding mill, grind it, and grind it for 1-2 hours to obtain high-viscosity hydroxypropyl methylcellulose.

[0035] Furthermore, the prepared high viscosity hydroxypropyl methylcellulose includes the following components in parts by weight:

[0036] 20-35 parts of refined cotton cellulose, 50-70 parts of sodium hydroxide solution, 25-30 parts of methyl chloride, 15-25 parts of propylene oxide, 10-20 parts of fulvic acid aqueous solution, 5-8 parts of potassium naphthylacetate, 2-3 parts of sodium sulfite, 1-3 parts of sodium molybdate and 18-25 parts of a cross-linking agent.

[0037] Furthermore, the cross-linking agent is prepared by mixing sodium tetraborate with sodium tripolyphosphate or sodium trimetaphosphate.

[0038] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0039] 1. The present invention reduces the water-soluble group content of the prepared hydroxypropyl methylcellulose by adding a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate during the etherification reaction of alkalized cellulose to carry out a cross-linking reaction, thereby achieving the effect of increasing the viscosity of the hydroxypropyl methylcellulose. The high-viscosity hydroxypropyl methylcellulose is coated on the surface of crops, which not only has a better surface polishing effect, but also increases its sugar content.

[0040] 2. The present invention adds an aqueous solution of fulvic acid to the reaction product after the cross-linking reaction and the etherification reaction are completed, which can not only neutralize the sodium hydroxide in the reaction system and simplify the preparation process, but also the fulvic acid salt generated after neutralization can stimulate the development of crop root system, promote absorption and enhance the disease resistance and stress resistance of crops.

[0041] 3. The present invention can synergistically promote the sweetening effect of the high-viscosity hydroxypropyl methylcellulose on crops by adding potassium naphthylacetate, sodium sulfite and sodium molybdate to the system after the neutralization reaction, so that the crops have a higher sugar content. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a flowchart of a method for preparing high-viscosity hydroxypropyl methylcellulose used in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific embodiments.

[0044] Example 1

[0045] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown, the following steps are included:

[0046] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0047] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0048] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate in a mass ratio of 1:1 to the intermediate A obtained in step S2, and a cross-linking reaction is performed to obtain an intermediate B. After the reaction for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of a fulvic acid aqueous solution are added to the intermediate B to perform a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then the addition of the fulvic acid aqueous solution is stopped to obtain an intermediate C;

[0049] S4: Add 5 parts of potassium naphthylacetate, 2 parts of sodium sulfite and 1 part of sodium molybdate to the intermediate C obtained in step S3, stir and mix with a stirrer to obtain an intermediate D, then put the intermediate D into an insulated box, and pass hot air at 120° C. into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%, and the solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0050] Then, the above hydroxypropyl methylcellulose was tested:

[0051] First, 50 g of high-viscosity hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. The homogeneous solution was then placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 20352.3 mPs and recorded.

[0052] Secondly, the homogeneous solution was sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution was leveled, it was observed that the surface of the watermelon seedling leaves had a good glossiness, and the result was recorded.

[0053] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines to see if there are any insect pests, and record them;

[0054] Finally, after the watermelons grew and matured, they were picked and the sweetness of the watermelons was detected to be 15 using a fruit sugar content non-destructive detector and recorded. At the same time, the watermelon vines were pulled out with their roots and their well-developed root systems were observed and recorded.

[0055] Example 2

[0056] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown, the following steps are included:

[0057] S1: Add 60 parts of sodium hydroxide solution into the grinder, and heat the sodium hydroxide solution through the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 35°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and adds 27.5 parts of refined cotton cellulose into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds a preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalizes the refined cotton cellulose to obtain alkalized cellulose;

[0058] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 27.5 parts of methyl chloride and 20 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 75° C., and perform etherification reaction to obtain intermediate A;

[0059] S3: After heating for 2.5 hours, the controller controls the heating temperature of the heater to be adjusted to 55°C, and then the controller controls the feeder to add 20 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate in a mass ratio of 1:3 to the intermediate A obtained in step S2, and a cross-linking reaction is carried out to obtain an intermediate B. After reacting for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 85°C, and 15 parts of a fulvic acid aqueous solution are added to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6.5, and the addition of the fulvic acid aqueous solution is stopped to obtain an intermediate C;

[0060] S4: 6.5 parts of potassium naphthylacetate, 2.5 parts of sodium sulfite and 2 parts of sodium molybdate are added to the intermediate C obtained in step S3, and the mixture is stirred with a stirrer to obtain an intermediate D, and then the intermediate D is placed in an insulated box, and hot air at 135° C. is introduced into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 1%. The solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to close, and then the dried intermediate D is added to a grinding mill for grinding, and then ground for 1.5 hours to obtain hydroxypropyl methylcellulose.

[0061] Example 3

[0062] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown, the following steps are included:

[0063] S1: 70 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 40°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 35 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds a preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalizes the refined cotton cellulose to obtain alkalized cellulose;

[0064] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 30 parts of methyl chloride and 25 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 80° C., and perform etherification reaction to obtain intermediate A;

[0065] S3: After heating for 3 hours, the controller controls the heating temperature of the heater to be adjusted to 60°C, and then the controller controls the feeder to add 25 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate in a mass ratio of 1:4 to the intermediate A obtained in step S2, and a cross-linking reaction is performed to obtain an intermediate B. After the reaction for 3 hours, the controller controls the heating temperature of the heater to be adjusted to 90°C, and 20 parts of a fulvic acid aqueous solution are added to the intermediate B to perform a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 7, and the addition of the fulvic acid aqueous solution is stopped to obtain an intermediate C;

[0066] S4: 8 parts of potassium naphthylacetate, 3 parts of sodium sulfite and 3 parts of sodium molybdate are added to the intermediate C obtained in step S3, and the mixture is stirred with a stirrer to obtain an intermediate D, and then the intermediate D is placed in an insulated box, and hot air at 150° C. is introduced into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 2%. The solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to close, and then the dried intermediate D is added to a grinding mill for grinding, and then ground for 2 hours to obtain hydroxypropyl methylcellulose.

[0067] Comparative Example 1

[0068] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown in Table 1, the following steps are included:

[0069] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0070] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0071] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of sodium tetraborate crosslinking agent to the intermediate A obtained in step S2 to carry out a crosslinking reaction to obtain an intermediate B. After the reaction for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of fulvic acid aqueous solution are added to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then stops adding the fulvic acid aqueous solution to obtain an intermediate C;

[0072] S4: Add 5 parts of potassium naphthylacetate, 2 parts of sodium sulfite and 1 part of sodium molybdate to the intermediate C obtained in step S3, stir and mix with a stirrer to obtain an intermediate D, then put the intermediate D into an insulated box, and pass hot air at 120° C. into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%, and the solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0073] Then, the above hydroxypropyl methylcellulose was tested:

[0074] First, 50 g of hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. Then, the homogeneous solution was placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 3065.2 mPs and recorded.

[0075] Secondly, the homogeneous solution is sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution is leveled, the glossiness of the surface of the watermelon seedling leaves is observed to be average and recorded;

[0076] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines to see if there are any insect pests, and record them;

[0077] Finally, after the watermelons grew and matured, they were picked and the sweetness of the watermelons was detected to be 12 using a fruit sugar content non-destructive detector and recorded. At the same time, the watermelon vines were pulled out with their roots and their well-developed root systems were observed and recorded.

[0078] From the comparison of the above test results with Example 1, it can be seen that by adding a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate to the etherification reaction of alkalized cellulose for cross-linking reaction, the water-soluble group content of the prepared hydroxypropyl methylcellulose can be reduced, thereby achieving the effect of increasing the viscosity of the hydroxypropyl methylcellulose. The high-viscosity hydroxypropyl methylcellulose is coated on the surface of crops, which not only has a better surface polishing effect, but also increases its sugar content.

[0079] Comparative Example 2

[0080] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown in Table 2, the following steps are included:

[0081] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0082] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0083] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of sodium tripolyphosphate cross-linking agent to the intermediate A obtained in step S2 to carry out a cross-linking reaction to obtain an intermediate B. After the reaction for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of fulvic acid aqueous solution are added to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then stops adding the fulvic acid aqueous solution to obtain an intermediate C;

[0084] S4: Add 5 parts of potassium naphthylacetate, 2 parts of sodium sulfite and 1 part of sodium molybdate to the intermediate C obtained in step S3, stir and mix with a stirrer to obtain an intermediate D, then put the intermediate D into an insulated box, and pass hot air at 120° C. into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%, and the solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0085] Then, the above hydroxypropyl methylcellulose was tested:

[0086] First, 50 g of hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. Then, the homogeneous solution was placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 3024.6 mPs and recorded.

[0087] Secondly, the homogeneous solution is sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution is leveled, the glossiness of the surface of the watermelon seedling leaves is observed to be average and recorded;

[0088] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines to see if there are any insect pests, and record them;

[0089] Finally, after the watermelons grew and matured, they were picked and the sweetness of the watermelons was detected to be 12 using a fruit sugar content non-destructive detector and recorded. At the same time, the watermelon vines were pulled out with their roots and their well-developed root systems were observed and recorded.

[0090] From the comparison of the above test results with Example 1, it can be seen that by adding a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate to the etherification reaction of alkalized cellulose for cross-linking reaction, the water-soluble group content of the prepared hydroxypropyl methylcellulose can be reduced, thereby achieving the effect of increasing the viscosity of the hydroxypropyl methylcellulose. The high-viscosity hydroxypropyl methylcellulose is coated on the surface of crops, which not only has a better surface polishing effect, but also increases its sugar content.

[0091] Comparative Example 3

[0092] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown in Table 3, the following steps are included:

[0093] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0094] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0095] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium trimetaphosphate in a mass ratio of 1:1 to the intermediate A obtained in step S2, and a cross-linking reaction is performed to obtain an intermediate B. After the reaction for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of a fulvic acid aqueous solution are added to the intermediate B to perform a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then the addition of the fulvic acid aqueous solution is stopped to obtain an intermediate C;

[0096] S4: Add 5 parts of potassium naphthylacetate, 2 parts of sodium sulfite and 1 part of sodium molybdate to the intermediate C obtained in step S3, stir and mix with a stirrer to obtain an intermediate D, then put the intermediate D into an insulated box, and pass hot air at 120° C. into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%, and the solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0097] Then, the above hydroxypropyl methylcellulose was tested:

[0098] First, 50 g of hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. Then, the homogeneous solution was placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 3279.5 mPs and recorded.

[0099] Secondly, the homogeneous solution is sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution is leveled, the glossiness of the surface of the watermelon seedling leaves is observed to be average and recorded;

[0100] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines to see if there are any insect pests, and record them;

[0101] Finally, after the watermelons grew and matured, they were picked and the sweetness of the watermelons was detected to be 12 using a fruit sugar content non-destructive detector and recorded. At the same time, the watermelon vines were pulled out with their roots and their well-developed root systems were observed and recorded.

[0102] From the comparison of the above test results with Example 1, it can be seen that by adding a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate to the etherification reaction of alkalized cellulose for cross-linking reaction, the water-soluble group content of the prepared hydroxypropyl methylcellulose can be reduced, thereby achieving the effect of increasing the viscosity of the hydroxypropyl methylcellulose. The high-viscosity hydroxypropyl methylcellulose is coated on the surface of crops, which not only has a better surface polishing effect, but also increases its sugar content.

[0103] Comparative Example 4

[0104] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown in Table 4, the following steps are included:

[0105] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0106] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0107] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate to the intermediate A obtained in step S2 to carry out a cross-linking reaction to obtain an intermediate B. After reacting for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of hydrochloric acid are added to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then stops adding hydrochloric acid to obtain an intermediate C;

[0108] S4: Add 5 parts of potassium naphthylacetate, 2 parts of sodium sulfite and 1 part of sodium molybdate to the intermediate C obtained in step S3, stir and mix with a stirrer to obtain an intermediate D, then put the intermediate D into an insulated box, and pass hot air at 120° C. into the insulated box through a hot air blower to dry the intermediate D until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%, and the solid moisture online measuring instrument sends a signal to the controller. After receiving the signal sent by the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0109] Then, the above hydroxypropyl methylcellulose was tested:

[0110] First, 50 g of hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. Then, the homogeneous solution was placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 20149.9 mPs and recorded.

[0111] Secondly, the homogeneous solution was sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution was leveled, it was observed that the surface of the watermelon seedling leaves had a good glossiness, and the result was recorded.

[0112] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines and find that they are moderately infested, and record them;

[0113] Finally, after the watermelons grew and matured, they were picked and the sweetness of the watermelons was detected to be 9 using a fruit sugar content non-destructive detector and recorded. At the same time, the watermelon vines were pulled out with their roots and their root systems were observed to be underdeveloped, which was also recorded.

[0114] From the comparison of the above test results with Example 1, it can be seen that by adding an aqueous solution of fulvic acid to the reaction product after the cross-linking reaction and the etherification reaction are completed, not only can the sodium hydroxide in the reaction system be neutralized to simplify the preparation process, but the fulvic acid salt generated after neutralization can also stimulate the development of the crop root system, promote absorption, and enhance the disease resistance and stress resistance of the crop.

[0115] Comparative Example 5

[0116] A method for preparing high-viscosity hydroxypropyl methylcellulose, such as Figure 1 As shown in Table 5, the following steps are included:

[0117] S1: 50 parts of sodium hydroxide solution are added into the grinder, and the sodium hydroxide solution is heated by the first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30°C, the temperature sensor sends a signal to the controller, and after receiving the signal sent by the temperature sensor, the controller controls the feed component of the grinder to open, and 20 parts of refined cotton cellulose are added into the grinder through the feed component, and when the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller, and after receiving the signal sent by the first gravity sensor, the controller controls the grinder to start and grind, and at the same time alkalize the refined cotton cellulose to obtain alkalized cellulose;

[0118] S2: adding the alkalized cellulose obtained in step S1 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor is no longer increasing, the second gravity sensor sends a signal to the controller, and after receiving the signal sent by the second gravity sensor, the controller controls the agitator to stir, and at the same time controls the hydraulic pump to add 25 parts of methyl chloride and 15 parts of propylene oxide into the reactor, until the second gravity sensor detects that the gravity in the reactor is no longer increasing for the second time, the second gravity sensor sends a signal to the controller again, and after receiving the signal sent by the second gravity sensor for the second time, the controller controls the second heater in the reactor to turn on, heat the inside of the reactor to 70° C., and perform etherification reaction to obtain intermediate A;

[0119] S3: After heating for 2 hours, the controller controls the heating temperature of the heater to be adjusted to 50°C, and then the controller controls the feeder to add 18 parts of a cross-linking agent prepared by mixing sodium tetraborate and sodium tripolyphosphate to the intermediate A obtained in step S2, and a cross-linking reaction is carried out to obtain an intermediate B. After the reaction for 1 hour, the controller controls the heating temperature of the heater to be adjusted to 80°C, and 10 parts of a fulvic acid aqueous solution are added to the intermediate B to carry out a neutralization reaction until the pH detector in the reactor detects that the pH of the intermediate B is 6, and then the addition of the fulvic acid aqueous solution is stopped to obtain an intermediate C;

[0120] S4: The intermediate C obtained in step S3 is placed in an insulated box, and hot air at 120° C. is introduced into the insulated box through a hot air blower to dry the intermediate C until the solid moisture online measuring instrument in the insulated box detects that the moisture content of the intermediate D is 0%. The solid moisture online measuring instrument sends a signal to the controller. After receiving the signal from the solid moisture online measuring instrument, the controller controls the hot air blower to turn off, and then adds the dried intermediate D to a grinding mill for grinding, and grinds it for 1 hour to obtain hydroxypropyl methylcellulose.

[0121] Then, various performance tests were performed on the above hydroxypropyl methylcellulose:

[0122] First, 50 g of hydroxypropyl methylcellulose was added to 500 ml of deionized water, and the mixture was stirred and dispersed into a homogeneous solution. Then, the homogeneous solution was placed on a rotary viscometer for viscosity testing. The viscosity was measured to be 20305.6 mPs and recorded.

[0123] Secondly, the homogeneous solution was sprayed on the surface of the watermelon seedling leaves. After the homogeneous solution was leveled, it was observed that the surface of the watermelon seedling leaves had a good glossiness, and the result was recorded.

[0124] Then, after the watermelon seedlings have grown for 30 days, observe the insect pests on the watermelon vines to see if there are any insect pests, and record them;

[0125] Finally, after the watermelon grows and ripens, pick the watermelon, and use a non-destructive fruit sugar detector to detect that the sweetness of the watermelon is 8 and record it. At the same time, pull out the watermelon vine with its roots and observe that its roots are well-developed and record it.

[0126] The summary of the test comparison results between Comparative Example 1 and Example 1 is shown in Table 1 as follows:

[0127] Table 1

[0128]

[0129] The summary of the test comparison results between Comparative Example 2 and Example 1 is shown in Table 2 as follows:

[0130] Table 2

[0131]

[0132] The summary of the test comparison results between Comparative Example 3 and Example 1 is shown in Table 3 as follows:

[0133] Table 3

[0134]

[0135] The summary of the test comparison results between Comparative Example 4 and Example 1 is shown in Table 4 as follows:

[0136] Table 4

[0137]

[0138] The summary of the test comparison results between Comparative Example 5 and Example 1 is shown in Table 5 as follows:

[0139] Table 5

[0140]

[0141] Comparing the above test results with Example 1, it can be seen that by adding potassium naphthylacetate, sodium sulfite, and sodium molybdate to the system after the neutralization reaction, the synergistic effect can promote the sweetening effect of the prepared high-viscosity hydroxypropyl methylcellulose on crops, making the crops have a higher sugar content.

[0142] The above examples only illustrate the principle and its effects of the present invention by way of example, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation method of high-viscosity hydroxypropyl methylcellulose, characterized in that, it comprises the following steps: S1: Grinding and alkalizing refined cotton cellulose Adding refined cotton cellulose into a sodium hydroxide solution, grinding it through a grinder, and alkalizing it simultaneously to obtain alkalized cellulose; S2: Adding methyl chloride and propylene oxide for etherification reaction Adding methyl chloride and propylene oxide into the above-mentioned alkalized cellulose, heating to 70 - 80 °C, and carrying out an etherification reaction to obtain intermediate A; S3: Adding a cross-linking agent and an aqueous solution of fulvic acid for reaction successively Adding the cross-linking agent into intermediate A for cross-linking reaction to prepare intermediate B, and then adding the aqueous solution of fulvic acid into intermediate B for neutralization reaction to obtain intermediate C; S4: Adding potassium naphthylacetate, sodium sulfite and sodium molybdate and then drying Adding potassium naphthylacetate, sodium sulfite and sodium molybdate into intermediate C, stirring and mixing, then passing hot air for drying, and through pulverizing and grinding, high-viscosity hydroxypropyl methylcellulose is obtained; The cross-linking agent is prepared by mixing sodium tetraborate with sodium tripolyphosphate or sodium metaphosphate, and the mass ratio of sodium tetraborate to sodium tripolyphosphate or sodium metaphosphate is 1:

1.

2. The preparation method of a high-viscosity hydroxypropyl methylcellulose according to claim 1, characterized in that, the grinding and alkalizing of refined cotton cellulose in step S1 specifically comprises the following steps: S1.1: Adding the sodium hydroxide solution into the grinder, heating the sodium hydroxide solution through a first heater until the temperature sensor in the grinder detects that the temperature of the sodium hydroxide solution reaches 30 - 40 °C, and the temperature sensor sends a signal to the controller; S1.2: After the controller receives the signal sent by the temperature sensor, it controls the feeding component of the grinder to open, and adds refined cotton cellulose into the grinder through the feeding component; S1.3: When the first gravity sensor in the grinder detects that the gravity in the grinder exceeds the preset gravity range, the first gravity sensor sends a signal to the controller; S1.4: After the controller receives the signal sent by the first gravity sensor, it controls the grinder to start grinding, and alkalizes the refined cotton cellulose simultaneously to obtain alkalized cellulose.

3. The preparation method of a high-viscosity hydroxypropyl methylcellulose according to claim 2, characterized in that, the adding of methyl chloride and propylene oxide for etherification reaction in step S2 specifically comprises the following steps: S2.1: Adding the alkalized cellulose prepared in step S1.4 into the reactor until the second gravity sensor in the reactor detects that the gravity in the reactor no longer increases, and the second gravity sensor sends a signal to the controller; S2.2: After the controller receives the signal sent by the second gravity sensor, it controls the stirrer to stir, and at the same time controls the hydraulic pump to add methyl chloride and propylene oxide into the reactor; S2.3: Until the second gravity sensor detects for the second time that the gravity in the reactor no longer increases, the second gravity sensor sends a signal to the controller again; S2.4: After the controller receives the signal sent by the second gravity sensor for the second time, it controls the second heater in the reactor to turn on, heats the interior of the reactor to 70 - 80 °C, and conducts an etherification reaction to obtain intermediate A.

4. A method for preparing high-viscosity hydroxypropyl methylcellulose according to claim 3, characterized in that in step S3, a crosslinking agent and an aqueous fulvic acid solution are added successively for reaction, which specifically includes the following steps: S3.1: After heating for 2 - 3 h, the controller adjusts the heating temperature of the heater to 50 - 60 °C; S3.2: Subsequently, the controller controls the feeder to add the crosslinking agent into intermediate A prepared in step S2.4 for a crosslinking reaction to obtain intermediate B; S3.3: After reacting for 1 - 3 h, the controller adjusts the heating temperature of the heater to 80 - 90 °C; S3.4: Add the aqueous fulvic acid solution to the above intermediate B for a neutralization reaction until the pH detector in the reactor detects that the pH of intermediate B is 6 - 7, then stop adding the aqueous fulvic acid solution to obtain intermediate C.

5. A method for preparing high-viscosity hydroxypropyl methylcellulose according to claim 4, characterized in that in step S4, potassium naphthylacetate, sodium sulfite, and sodium molybdate are added and then dried, which specifically includes the following steps: S4.1: Add potassium naphthylacetate, sodium sulfite, and sodium molybdate to intermediate C prepared in step S3.4, and stir and mix them with a stirrer to obtain intermediate D; S4.2: Put the above intermediate D into an incubator, and pass hot air at 120 - 150 °C into the incubator through a hot air blower to dry intermediate D; S4.3: Until the on-line moisture meter for solids in the incubator detects that the moisture content of intermediate D is 0 - 2%, the on-line moisture meter for solids sends a signal to the controller. After the controller receives the signal sent by the on-line moisture meter for solids, it controls the hot air blower to turn off; S4.4: Add the dried intermediate D into a grinding and pulverizing machine for pulverization, and then grind for 1 - 2 h to obtain high-viscosity hydroxypropyl methylcellulose.

6. A method for preparing high-viscosity hydroxypropyl methylcellulose according to claim 1, characterized in that the prepared high-viscosity hydroxypropyl methylcellulose includes the following components: 20 - 35 parts of refined cotton cellulose, 50 - 70 parts of sodium hydroxide solution, 25 - 30 parts of chloromethane, 15 - 25 parts of propylene oxide, 10 - 20 parts of aqueous fulvic acid solution, 5 - 8 parts of potassium naphthylacetate, 2 - 3 parts of sodium sulfite, 1 - 3 parts of sodium molybdate, and 18 - 25 parts of crosslinking agent.

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