Agricultural polymer surfactant and preparation method thereof

Abstract

The invention relates to the field of macromolecular surfactants, and discloses an agricultural macromolecular surfactant and a preparation method thereof. The preparation method comprises the following steps: introducing a plurality of hydrophilic polyethylene glycol side chains into sodium lignin sulfonate molecules by adopting an electrophilic substitution reaction to prepare novel anionic sodium lignin sulfonate polyoxyethylene ether, introducing a tetramethyl piperidylamine monomer by virtue of a Mannich reaction to synthesize novel hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, the stable agricultural polymer surfactant is prepared by mixing a cationic surfactant hexadecyl trimethyl ammonium bromide and the cationic surfactant hexadecyl trimethyl ammonium bromide, and the agricultural polymer surfactant has strong surface activity, dispersing performance and photolysis resistance.

Description

Technical Field

[0001] The invention relates to the field of high molecular surfactants, and in particular to an agricultural high molecular surfactant and a preparation method thereof. Background Art

[0002] As the final form of pesticides, the characteristics and performance of the formulations directly affect the efficacy and safety of pesticides. The development of formulations is moving towards water-based, granular, low-toxic and high-efficiency. Dispersants are the most critical adjuvant in water-based pesticide formulations, and their development will determine the development of pesticide formulations.

[0003] At present, the most commonly used pesticide dispersants are lignin sulfonate, naphthalene sulfonate and its formaldehyde condensate, block copolymers and polycarboxylic acid comb copolymers. Except for lignin sulfonate, the other dispersants are all derived from petrochemical products, which are costly and even harmful to the human body, and cannot meet the needs of sustainable development. Lignin sulfonate dispersants are mainly derived from papermaking wastewater, and have the advantages of good compatibility with the original drug, environmental protection, complete biodegradability and low price. Although lignin sulfonate can be used in different industrial fields, due to its low molecular weight, insufficient functional groups, poor surface activity, general application performance, and poor dispersion stability as a specific dispersant. Therefore, it is of great significance for the development of pesticide preparations in my country to improve the application performance of lignin dispersants in pesticide preparations by means of physical and chemical modification so that they can meet the development needs of new pesticide preparations.

[0004] Since biological pesticides have poor rapid effectiveness, they require a longer period to exert their efficacy. However, the active ingredients of most biological pesticides are easily decomposed in the natural environment due to factors such as temperature, light, water pH and microorganisms, thereby reducing the insecticidal activity and control effect. Increasing the dosage to improve the efficacy will also bring a greater burden to the environment.

[0005] Prior art, such as Chinese patent application CN105557687A, discloses an avermectin aqueous suspension and a preparation method thereof. The method for improving the photostability of the pesticide is to directly add a small molecule photostability agent, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, which is a water-insoluble substance, has a poor dispersion effect in a water system and is easy to migrate, resulting in poor actual effect. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an agricultural polymer surfactant and a preparation method thereof, wherein the surfactant has strong surface activity, dispersibility and resistance to photolysis.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing an agricultural macromolecular surfactant comprises the following steps:

[0009] Step (1), mixing polyethylene glycol, boron trifluoride etherate and epichlorohydrin, and reacting them. After the reaction is completed, a chloropolyethylene glycol intermediate is obtained;

[0010] The sodium lignin sulfonate aqueous solution is mixed with the chloropolyethylene glycol intermediate, the pH is adjusted, the reaction is carried out, and after the reaction is completed, the sodium lignin sulfonate polyoxyethylene ether is purified to obtain;

[0011] Step (2), mixing sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine, adjusting the pH, adding formaldehyde aqueous solution and reacting, cooling after the reaction, and purifying to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0012] Step (3), mixing hexadecyltrimethylammonium bromide, hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol and water, stirring, standing and settling, and purifying to obtain an agricultural polymer surfactant.

[0013] Preferably, in the step (1), when preparing the chloropolyethylene glycol intermediate: epichlorohydrin is added by slow dropwise addition at a titration rate of 1-2 d / s; the molar ratio of epichlorohydrin to polyethylene glycol is (0.8-1.2):1, and the amount of boron trifluoride ether added is 0.1 wt% of the amount of polyethylene glycol added; and the reaction conditions are: reacting at a temperature of 50-60° C. for 1-3 h.

[0014] Preferably, in the step (1), when preparing sodium lignin sulfonate polyoxyethylene ether: the mass fraction of the sodium lignin sulfonate aqueous solution is 30%; the mass ratio of the 30wt% sodium lignin sulfonate aqueous solution to the chloropolyethylene glycol intermediate is 3:(0.5-1.5); the pH is adjusted by adding 30wt% sodium hydroxide aqueous solution to adjust the pH to 9-11; the reaction conditions are: reacting at pH = 9-11 and 60-80°C for 2-4h.

[0015] Preferably, in the step (1), when preparing sodium lignin sulfonate polyoxyethylene ether: the purification step is: extracting the sodium lignin sulfonate polyoxyethylene ether solution with butanone for 3-5 times, removing water and unreacted polyethylene glycol, filtering to obtain an extraction product, adding ethanol with a mass of 8-10 times that of the extraction product for washing 3-5 times, and drying at a temperature of 35-45°C for 20-24h to obtain purified sodium lignin sulfonate polyoxyethylene ether.

[0016] Preferably, in step (2), the pH is adjusted by adding 30 wt% sodium hydroxide aqueous solution to adjust the pH to 10-12; the formaldehyde aqueous solution added is 10 wt% formaldehyde aqueous solution, and the addition time is 30-40 min; the mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt% formaldehyde aqueous solution is 10:(60-80):(1-4):(2-8); the reaction conditions are: react at pH=10-12 and 65-85°C for 3-5 h.

[0017] Preferably, in step (2), the purification step is: adding 8-10 times the volume of ethanol precipitation to the reaction product, filtering, taking the precipitate, and drying it at 35-45°C for 20-24h.

[0018] Preferably, in step (3), the mass ratio of hexadecyltrimethylammonium bromide, hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether, ethanol and water is 50:(2-10):(150-630):(100-420); the stirring conditions are: stirring at a speed of 400-500 rpm for 30-40 minutes; and the precipitation time is 20-24 hours.

[0019] Preferably, in step (3), the purification step is: taking the precipitate, adding deionized water 8-10 times the mass of the precipitate to wash 3-5 times, centrifuging, filtering, taking the centrifuged precipitate, and drying it at 35-45°C for 20-24h.

[0020] Preferably, an agricultural high molecular surfactant is prepared by the preparation method of an agricultural high molecular surfactant as described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The molecular structure of lignin sulfonate contains functional groups such as phenylpropane hydrophobic skeleton, phenolic hydroxyl group, alcoholic hydroxyl group, carboxyl group, sulfonic acid group, etc., and has certain dispersibility. The invention adopts electrophilic substitution reaction to introduce multiple hydrophilic polyethylene glycol side chains into the sodium lignin sulfonate molecule to prepare a novel anionic sodium lignin sulfonate polyoxyethylene ether. The product has anionic functional groups and long polyethylene glycol hydrophilic chains, increases its molecular weight, and improves its surface activity and application performance.

[0023] The invention introduces tetramethyl piperidine amine monomer into the sodium lignin sulfonate polyoxyethylene ether molecule through Mannich reaction, synthesizes hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, realizes high molecular weight and water-based small molecule light stabilizer, obtains novel lignin-based water-soluble macromolecular light stabilizer, and uses it in pesticides, which has the dual effects of dispersion stability and anti-photolysis synergistic effect.

[0024] The present invention uses the positive charge groups of the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) and the negative charge groups of the prepared hindered amine grafted sodium lignin sulfonate polyoxyethylene ether to obtain a stable cationic and anionic polymer surfactant through electrostatic interaction. Due to the introduction of the long hydrophilic chain of polyethylene glycol, the steric hindrance between molecules is increased, and the flocculation and precipitation phenomenon is avoided under the dual influence of steric hindrance and electrostatic action. Compared with simple lignin-based anionic surfactants, it has stronger surface activity (the surface tension is as low as 34.28mN·m -1 ) and critical aggregation concentration, realizing the high-value utilization of lignin sulfonate, and obtaining an agricultural polymer surfactant with strong surface activity, dispersibility and resistance to photolysis.

[0025] The reaction process of the invention is carried out at normal pressure and low temperature, and is easy to operate and control. Since the polyoxyethylene ether hydrophilic group and the tetramethylpiperidinamine functional group are directly introduced into the lignin sulfonate molecule through the grafting reaction, there are few side reactions, the damage to the lignin structure is very small, the reaction time is short, and the product has good water solubility, is environmentally friendly and non-toxic. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of preparing agricultural macromolecular surfactant in the present invention;

[0027] Figure 2 It is a histogram of surface tension in comprehensive performance test of agricultural macromolecular surfactants prepared in Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0028] Figure 3 is a bar graph of average particle sizes of samples 1-8 prepared from Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0029] Figure 4 is a histogram of the suspension rates of samples 1-8 prepared from Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0030] Figure 5 It is a bar graph of the light retention rate of samples 1-8 prepared from Examples 1-5 and Comparative Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0034] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0035] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 50°C for 3h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0036] The molar ratio of epichlorohydrin to polyethylene glycol is 1.2:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0037] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:1.5, the pH is adjusted to 11 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 80°C for 2h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0038] The sodium lignin sulfonate polyoxyethylene ether solution was extracted with butanone for 5 times, water and unreacted polyethylene glycol were removed, and the extracted product was filtered to obtain the extracted product, and ethanol with a mass of 10 times that of the extracted product was added to wash the product for 5 times, and the product was dried at 45°C for 20 hours to obtain the purified sodium lignin sulfonate polyoxyethylene ether;

[0039] Step (2), preparing hindered amine grafted sodium lignin sulfonate polyoxyethylene ether;

[0040] Mix sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine (Temp), adjust the pH to 12 with 30wt% sodium hydroxide solution, stir at 70°C for 15min, add 10wt% formaldehyde aqueous solution for 30min, react at 85°C for 3h after the addition, cool to room temperature after the reaction to obtain a reaction product, add 10 times the volume of ethanol to the reaction product for precipitation, filter, take the precipitate, and dry at 45°C for 20h to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0041] The mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:60:1:2;

[0042] Step (3), cetyltrimethylammonium bromide (CTAB), hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol, and water are mixed in a mass ratio of 50:2:150:100, stirred at a speed of 500 rpm for 30 minutes, allowed to stand for precipitation for 24 hours, filtered, the precipitate is taken, and deionized water 10 times the mass of the precipitate is added to wash 5 times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 45°C for 20 hours to obtain an agricultural polymer surfactant.

[0043] Example 2

[0044] This embodiment discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0045] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0046] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 60°C for 1h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0047] The molar ratio of epichlorohydrin to polyethylene glycol is 0.8:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0048] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:0.5, the pH is adjusted to 9 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 60°C for 4h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0049] The sodium lignin sulfonate polyoxyethylene ether solution was extracted three times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was obtained by filtration, and ethanol with a mass of 8 times that of the extracted product was added for washing three times, and dried at 35°C for 24 hours to obtain purified sodium lignin sulfonate polyoxyethylene ether;

[0050] Step (2), preparing hindered amine grafted sodium lignin sulfonate polyoxyethylene ether;

[0051] Mix sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine (Temp), adjust the pH to 10 with 30wt% sodium hydroxide solution, stir at 50°C for 35min, add 10wt% formaldehyde aqueous solution for 40min, react at 65°C for 5h after the addition, cool to room temperature after the reaction to obtain a reaction product, add 8 times the volume of ethanol to the reaction product for precipitation, filter, take the precipitate, and dry at 35°C for 24h to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0052] The mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:80:4:8;

[0053] Step (3), cetyltrimethylammonium bromide (CTAB), hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol, and water are mixed in a mass ratio of 50:10:630:420, stirred at a speed of 400 rpm for 40 minutes, allowed to stand for precipitation for 20 hours, filtered, the precipitate is taken, and deionized water 8 times the mass of the precipitate is added to wash 3 times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 35°C for 24 hours to obtain an agricultural polymer surfactant.

[0054] Example 3

[0055] This embodiment discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0056] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0057] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 52°C for 3h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0058] The molar ratio of epichlorohydrin to polyethylene glycol is 1.1:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0059] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with the chloropolyethylene glycol intermediate at a mass ratio of 3:1.2, the pH is adjusted to 11 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 75°C for 2h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0060] The sodium lignin sulfonate polyoxyethylene ether solution was extracted 5 times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was obtained by filtration. The extracted product was washed 5 times with ethanol 10 times the mass of the extracted product, and dried at 42°C for 21 hours to obtain purified sodium lignin sulfonate polyoxyethylene ether;

[0061] Step (2), preparing hindered amine grafted sodium lignin sulfonate polyoxyethylene ether;

[0062] Mix sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine (Temp), adjust the pH to 12 with 30wt% sodium hydroxide solution, stir at 65°C for 20min, add 10wt% formaldehyde aqueous solution for 32min, react at 80°C for 3h after the addition, cool to room temperature after the reaction to obtain a reaction product, add 10 times the volume of ethanol to the reaction product for precipitation, filter, take the precipitate, and dry at 42°C for 21h to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0063] The mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:65:2:3.5;

[0064] Step (3), cetyltrimethylammonium bromide (CTAB), hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol, and water are mixed in a mass ratio of 50:2.5:180:120, stirred at a speed of 475 rpm for 32 minutes, allowed to stand for precipitation for 23 hours, filtered, the precipitate is taken, and deionized water 10 times the mass of the precipitate is added to wash 5 times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 42° C. for 21 hours to obtain an agricultural polymer surfactant.

[0065] Example 4

[0066] This embodiment discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0067] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0068] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 55°C for 2h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0069] The molar ratio of epichlorohydrin to polyethylene glycol is 1:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0070] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:1, the pH is adjusted to 10 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 70°C for 3h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0071] The sodium lignin sulfonate polyoxyethylene ether solution was extracted 4 times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was obtained by filtration, and 9 times the mass of the extracted product was added with ethanol to wash 4 times, and dried at 40°C for 22 hours to obtain purified sodium lignin sulfonate polyoxyethylene ether;

[0072] Step (2), preparing hindered amine grafted sodium lignin sulfonate polyoxyethylene ether;

[0073] Mix sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine (Temp), adjust the pH to 11 with 30wt% sodium hydroxide solution, stir at 60°C for 25min, drop 10wt% formaldehyde aqueous solution for 35min, react at 75°C for 4h after the dropwise addition, cool to room temperature after the reaction to obtain a reaction product, add 9 times the volume of ethanol to the reaction product for precipitation, filter, take the precipitate, and dry at 40°C for 22h to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0074] The mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:70:2.5:5;

[0075] Step (3), cetyltrimethylammonium bromide (CTAB), hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol, and water are mixed in a mass ratio of 50:3:210:140, stirred at a speed of 450 rpm for 35 minutes, allowed to stand for precipitation for 22 hours, filtered, the precipitate is taken, and deionized water of 9 times the mass of the precipitate is added to wash 4 times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 40°C for 22 hours to obtain an agricultural polymer surfactant.

[0076] Example 5

[0077] This embodiment discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0078] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0079] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 58°C for 1h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0080] The molar ratio of epichlorohydrin to polyethylene glycol is 0.9:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0081] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:0.8, the pH is adjusted to 9 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 65°C for 4 hours. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0082] The sodium lignin sulfonate polyoxyethylene ether solution was extracted three times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was filtered to obtain the extracted product, and ethanol with a mass of 8 times that of the extracted product was added to wash the product three times, and the product was dried at 38°C for 23 hours to obtain the purified sodium lignin sulfonate polyoxyethylene ether;

[0083] Step (2), preparing hindered amine grafted sodium lignin sulfonate polyoxyethylene ether;

[0084] Mix sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine (Temp), adjust the pH to 10 with 30wt% sodium hydroxide solution, stir at 55°C for 30min, add 10wt% formaldehyde aqueous solution for 38min, react at 70°C for 5h after the addition, cool to room temperature after the reaction to obtain a reaction product, add 8 times the volume of ethanol to the reaction product for precipitation, filter, take the precipitate, and dry at 38°C for 23h to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether;

[0085] The mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:75:3:6.5;

[0086] Step (3), cetyltrimethylammonium bromide (CTAB), hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol, and water are mixed in a mass ratio of 50:5:330:220, stirred at a speed of 425 rpm for 38 minutes, allowed to stand for precipitation for 21 hours, filtered, the precipitate is taken, and deionized water 8 times the mass of the precipitate is added to wash 3 times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 38°C for 23 hours to obtain an agricultural polymer surfactant.

[0087] Comparative Example 1

[0088] This comparative example discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0089] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0090] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 60°C for 1h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0091] The molar ratio of epichlorohydrin to polyethylene glycol is 0.8:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0092] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:0.5, the pH is adjusted to 9 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 60°C for 4h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0093] The sodium lignin sulfonate polyoxyethylene ether solution was extracted three times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was filtered to obtain the extracted product, and ethanol with a mass of 8 times that of the extracted product was added to wash it three times, and dried at 35°C for 24 hours to obtain an anionic polymer surfactant: sodium lignin sulfonate polyoxyethylene ether;

[0094] Comparative Example 2

[0095] This comparative example discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0096] Step (1), preparing sodium lignin sulfonate polyoxyethylene ether;

[0097] Mix polyethylene glycol and catalyst boron trifluoride ether, slowly add epichlorohydrin, the titration rate is 1-2d / s, after the addition is completed, react at 60°C for 1h, after the reaction is completed, obtain chloropolyethylene glycol intermediate;

[0098] The molar ratio of epichlorohydrin to polyethylene glycol is 0.8:1, and the amount of boron trifluoride ether added is 0.1wt% of the amount of polyethylene glycol added;

[0099] The sodium lignin sulfonate is prepared into an aqueous solution with a mass fraction of 30%, the 30wt% sodium lignin sulfonate aqueous solution is mixed with a chloropolyethylene glycol intermediate at a mass ratio of 3:0.5, the pH is adjusted to 9 with a 30wt% sodium hydroxide aqueous solution, and the reaction is carried out at a temperature of 60°C for 4h. After the reaction is completed, a 0.1mol / L hydrogen chloride aqueous solution is added as a regulator to adjust the pH to neutral to obtain a sodium lignin sulfonate polyoxyethylene ether solution;

[0100] The sodium lignin sulfonate polyoxyethylene ether solution was extracted three times with butanone, water and unreacted polyethylene glycol were removed, and the extracted product was obtained by filtration, and ethanol with a mass of 8 times that of the extracted product was added for washing three times, and dried at 35°C for 24 hours to obtain purified sodium lignin sulfonate polyoxyethylene ether;

[0101] Step (2), mixing hexadecyltrimethylammonium bromide (CTAB), sodium lignin sulfonate polyoxyethylene ether, ethanol and water in a mass ratio of 50:10:630:420, stirring at a rotation speed of 400 rpm for 40 minutes, standing for precipitation for 20 hours, filtering, taking the precipitate, adding deionized water 8 times the mass of the precipitate, washing three times, centrifuging, filtering, taking the centrifuged precipitate, and drying it at 35°C for 24 hours to obtain an agricultural polymer surfactant.

[0102] Comparative Example 3

[0103] This comparative example discloses an agricultural polymer surfactant and a preparation method thereof, comprising the following steps:

[0104] Step (1), preparing hindered amine-grafted sodium lignin sulfonate;

[0105] Sodium lignin sulfonate, water and 2,2,6,6-tetramethylpiperidinamine (Temp) were mixed, the pH value was adjusted to 10 with 30 wt % sodium hydroxide solution, the mixture was stirred at 50° C. for 35 min, 10 wt % formaldehyde aqueous solution was added dropwise for 40 min, and after the addition was completed, the mixture was reacted at 65° C. for 5 h. After the reaction was completed, the mixture was cooled to room temperature to obtain a reaction product, 8 times the volume of ethanol was added to the reaction product for precipitation, the mixture was filtered, the precipitate was taken, and it was dried at 35° C. for 24 h to obtain hindered amine-grafted sodium lignin sulfonate;

[0106] The mass ratio of sodium lignin sulfonate, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt % formaldehyde aqueous solution is 10:80:4:8;

[0107] Step (2), cetyltrimethylammonium bromide (CTAB), hindered amine-grafted sodium lignin sulfonate, ethanol, and water are mixed in a mass ratio of 50:10:630:420, stirred at a speed of 400 rpm for 40 minutes, allowed to stand for precipitation for 20 hours, filtered, the precipitate is taken, and deionized water 8 times the mass of the precipitate is added to wash three times, centrifuged, filtered, the centrifuged precipitate is taken, and dried at 35° C. for 24 hours to obtain an agricultural polymer surfactant.

[0108] In the above examples and comparative examples: polyethylene glycol comes from Guangdong Guanghua Technology Co., Ltd., Mw=600, CAS No.: 25322-68-3; boron trifluoride ethyl ether comes from Sinopharm Chemical Reagent Co., Ltd., CAS No.: 109-63-7; epichlorohydrin comes from Shanghai Denuo Chemical Co., Ltd., CAS No.: 106-89-8; sodium lignin sulfonate is provided by Jilin Shixian Paper Co., Ltd., from poplar acid sodium sulfite paper pulping waste liquid, CAS No.: 8061-51-6; sodium hydroxide comes from Sinopharm Chemical Reagent Co., Ltd., CAS No.: 14014-06-3; Butanone was from Nanjing Shengqinghe Chemical Co., Ltd., CAS No.: 78-93-3; N,N-dimethylformamide was from Guangdong Guanghua Technology Co., Ltd., CAS No.: 68-12-2; 2,2,6,6-tetramethylpiperidinamine was from Shanghai Aladdin Chemical Reagent Co., Ltd., CAS No.: 36768-62-4; formaldehyde was from Guangzhou Chemical Reagent Factory, CAS No.: 50-00-0; ethanol was from Guangdong Guanghua Technology Co., Ltd., CAS No.: 64-17-5; hexadecyltrimethylammonium bromide (CTAB) was from Guangzhou Chemical Reagent Factory, CAS No.: 57-09-0.

[0109] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0110] Test example

[0111] The surface activity performance of the agricultural high molecular surfactant prepared in Examples 1-5 and Comparative Examples 1-3 was tested; Examples 1-5 and Comparative Examples 1-3 were used as dispersants to prepare dimethomorph aqueous suspensions, recorded as samples 1-8, and the preparation method included: mixing 40wt% of the original drug (dimethomorph) and 4wt% of the dispersant, and filling the remaining amount with water to 100%, and ball milling for 3h using a QM-3SP2 planetary ball mill produced by Nanjing University Instrument Factory to obtain dimethomorph aqueous suspensions; the specific test results are shown in Table 1:

[0112] Table 1

[0113]

[0114] The indicators in Table 1 were tested according to the following methods: the surface tension was measured by using the DCAT21 surface / interfacial tension meter of Dataphysics Company of Germany; the average particle size was measured by using the MS2000 laser particle size analyzer of Malvern Company of Britain, and the average value was taken after three tests, wherein the hot storage condition was placed in a room temperature oven at 54°C for 14 days; the suspension rate was measured by using the test method of GB / T14825-2006, wherein the hot storage condition was placed in a room temperature oven at 54°C for 14 days; the test method of the light retention rate was as follows: after irradiation under a 30W, 310nm ultraviolet lamp for 60 hours, the samples 1-8 irradiated with ultraviolet light were ultrasonically dissolved with 5mL of methanol, and then the original drug content therein was detected by HPLC, and each sample was measured in parallel 3 times to take the average value.

[0115] It can be seen from the test results in Table 1 that the agricultural macromolecular surfactant prepared by the present invention has strong surface activity, dispersibility and resistance to photolysis.

[0116] In Comparative Example 1, only polyethylene glycol is grafted into sodium lignin sulfonate. After the polyethylene glycol long chain is connected, the molecules become stretched and loose, so that the sodium lignin sulfonate polyoxyethylene ether molecules are loosely arranged at the gas / liquid interface. At the same time, the hydrophobic core of the sodium lignin sulfonate itself will also become loose, and because the hydrophilicity of the sodium lignin sulfonate polyoxyethylene ether is stronger than that of the sodium lignin sulfonate, the tendency of desorption and dissolution in water increases. The above reasons make the sample of Comparative Example 1 have a lower coverage rate at the gas / liquid interface, making its surface activity and dispersibility worse than those of the embodiments. At the same time, since the hindered amine is not grafted, the light stabilization effect of lignin is reduced, so that the light retention rate of sample 6 prepared by Comparative Example 1 is lower than that of samples 1-5.

[0117] In Comparative Example 2, no hindered amine was grafted, which reduced the light stabilization effect of lignin, so that lignin could not inhibit the photo-oxidative decomposition of oxadiazine while acting as a dispersant. Therefore, the light retention rate of sample 7 prepared in Comparative Example 2 was lower than that of samples 1-5.

[0118] In Comparative Example 3, polyethylene glycol is not grafted, which reduces the relative molecular weight of the lignin-based high molecular surfactant and makes it less hydrophilic. However, the charge density of lignin sulfonate is relatively high, which makes it easy to produce flocculation and precipitation when compounded with cationic surfactants, resulting in poor compounding effect. For the above reasons, the surface tension of Comparative Example 3 is lower than that of the embodiment, and the average particle size of Sample 8 prepared by Comparative Example 3 is larger than that of Samples 1-5, while the suspension rate and light retention rate are lower than those of Samples 1-5.

[0119] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an agricultural polymer surfactant, characterized in that: The following steps are involved: Step (1), mixing polyethylene glycol, boron trifluoride etherate and epichlorohydrin, and reacting them. After the reaction is completed, a chloropolyethylene glycol intermediate is obtained; The sodium lignin sulfonate aqueous solution is mixed with the chloropolyethylene glycol intermediate, the pH is adjusted, the reaction is carried out, and after the reaction is completed, the sodium lignin sulfonate polyoxyethylene ether is purified to obtain; Step (2), mixing sodium lignin sulfonate polyoxyethylene ether, water, and 2,2,6,6-tetramethylpiperidinamine, adjusting the pH, adding formaldehyde aqueous solution and reacting, cooling after the reaction, and purifying to obtain hindered amine-grafted sodium lignin sulfonate polyoxyethylene ether; Step (3), mixing hexadecyltrimethylammonium bromide, hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol and water, stirring, standing and settling, and purifying to obtain an agricultural polymer surfactant.

2. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (1), when preparing the chloropolyethylene glycol intermediate: epichlorohydrin is added by slow dropwise addition, with a titration rate of 1-2 d / s; the molar ratio of epichlorohydrin to polyethylene glycol is (0.8-1.2):1, and the amount of boron trifluoride ether added is 0.1 wt% of the amount of polyethylene glycol added; the reaction conditions are: reacting at a temperature of 50-60° C. for 1-3 h.

3. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (1), when preparing sodium lignin sulfonate polyoxyethylene ether: the mass fraction of the sodium lignin sulfonate aqueous solution is 30%; the mass ratio of the 30wt% sodium lignin sulfonate aqueous solution to the chloropolyethylene glycol intermediate is 3:(0.5-1.5); the pH is adjusted by adding 30wt% sodium hydroxide aqueous solution to adjust the pH to 9-11; the reaction conditions are: reacting at pH = 9-11 and a temperature of 60-80°C for 2-4h.

4. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (1), when preparing sodium lignin sulfonate polyoxyethylene ether: the purification step is: extracting the sodium lignin sulfonate polyoxyethylene ether solution with butanone for 3-5 times, removing water and unreacted polyethylene glycol, filtering to obtain an extraction product, adding ethanol with a mass of 8-10 times that of the extraction product to wash for 3-5 times, and drying at a temperature of 35-45°C for 20-24h to obtain purified sodium lignin sulfonate polyoxyethylene ether.

5. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (2), the pH is adjusted by adding a 30 wt % sodium hydroxide aqueous solution to adjust the pH to 10-12; the formaldehyde aqueous solution added is a 10 wt % formaldehyde aqueous solution, and the addition time is 30-40 min.

6. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (2), the mass ratio of sodium lignin sulfonate polyoxyethylene ether, water, 2,2,6,6-tetramethylpiperidinamine, and 10 wt% formaldehyde aqueous solution is 10:(60-80):(1-4):(2-8); the reaction conditions are: reacting at pH=10-12 and 65-85°C for 3-5 hours.

7. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (2), the purification step is: adding 8-10 times the volume of ethanol precipitation to the reaction product, filtering, taking the precipitate, and drying it at 35-45° C. for 20-24 hours.

8. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (3), the mass ratio of hexadecyltrimethylammonium bromide, hindered amine grafted sodium lignin sulfonate polyoxyethylene ether, ethanol and water is 50:(2-10):(150-630):(100-420); the stirring conditions are: stirring at a rotation speed of 400-500 rpm for 30-40 minutes; and the precipitation time is 20-24 hours.

9. The method for preparing an agricultural macromolecular surfactant according to claim 1, characterized in that: In the step (3), the purification step is as follows: taking the precipitate, adding deionized water 8-10 times the mass of the precipitate to wash 3-5 times, centrifuging, filtering, taking the centrifuged precipitate, and drying it at 35-45°C for 20-24h.

10. An agricultural high molecular surfactant prepared by the method for preparing an agricultural high molecular surfactant as claimed in any one of claims 1 to 9.

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