Cationic polypropylene derivative and application thereof in saline-alkali soil improvement

Abstract

The invention provides a cationic polypropylene derivative and application thereof in saline-alkali soil improvement, and belongs to the technical field of soil improvement. The cationic polypropylene derivative is cationic polyacrylate, in the implementation process, through selection of an emulsifier, the obtained cationic polyacrylate has higher solid content, and when the cationic polyacrylate is used for soil improvement, the water-retaining property and the fertilizer-retaining property of soil can be enhanced, the granular structure of the soil can be enhanced, and the water-retaining property and the fertilizer-retaining property of the soil can be improved. The permeability and the drought resistance of the soil are improved, and the yield and the quality of crops can be remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improvement, and in particular relates to a cationic polypropylene derivative and application thereof in improving saline-alkali land. Background Art

[0002] With the continuous development of society, soil resources are seriously insufficient, and due to some unreasonable utilization, such as large-scale unreasonable application of fertilizers, excessive spraying of pesticides, over-grazing, etc., the soil has been seriously degraded. The main manifestations are soil compaction and hardening, erosion, salinization, acidification, element imbalance, chemical pollution, organic matter loss and degradation of flora and fauna. The result of soil degradation is reduced soil productivity, reduced crop quality, and even enrichment of toxic elements. Therefore, how to maintain soil quality, improve acid-base soil, eliminate soil toxicity, and reduce the spread of soil-borne diseases has become the focus of people's attention.

[0003] The application of soil conditioners is one of the important measures to repair degraded soil. Soil conditioners can effectively improve the physical and chemical properties of soil and soil nutrient status, and have a positive effect on soil microorganisms, thereby improving the productivity of degraded soil. Soil properties include soil results, soil water content, soil temperature, soil enzyme activity, soil microbial population, soil aeration conditions, soil solution concentration, and soil hydrogen ion concentration. Different types of soil conditioners have different mechanisms of action on the soil, but they all effectively improve the physical structure of the soil, reduce soil bulk density, increase soil water content, change soil chemical properties, increase soil microbial activity, increase enzyme activity, increase soil trace element content, and adjust some or all of the soil water, fertilizer, air, and heat conditions to ultimately achieve the purpose of improving soil fertility.

[0004] Polyacrylamide is a water-soluble polymer compound that is widely used in the prior art. Chinese patent CN103351870A discloses a soil conditioner, which includes the following components in weight ratio: 10-15 of acrylamide-acrylate copolymer crosslinking material, 20-30 of acrylamide-sodium acrylic acid copolymer, and 55-60 of montmorillonite, and is formed by chelating the components. The soil conditioner is a light yellow powder particle, which is mixed with soil to form a very loose aggregate structure soil after agglomeration reaction and hydrophobic reaction. The aggregate structure soil has an excellent solid-liquid-gas three-phase structure of fertilizer retention, water retention, and air permeability, which is greatly beneficial to the growth of plant roots.

[0005] For example, Chinese patent CN107418585A discloses a saline-alkali soil conditioner, which includes the following components by mass: 30-60 parts of polymaleic acid, 10-30 parts of acrylic acid-2-acrylamide-2-methylpropanesulfonic acid multipolymer, 1-2 parts of surfactant, and water to 100 parts. The soil conditioner provided by the present invention can effectively change the salt content of saline-alkali soil, reduce the alkalinity of saline-alkali soil, improve the state of soil particles, and improve the water retention performance of soil.

[0006] However, there are few studies on other polypropylene derivatives in the prior art, and there are few studies on cationic polypropylene derivatives as soil conditioners. Therefore, it is necessary to develop a cationic polypropylene derivative that can effectively improve soil fertility and has water and fertilizer retention effects, and to study its soil improvement effect. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention aims to provide a cationic polypropylene derivative, which is a cationic polyacrylate. During the implementation process, by selecting an emulsifier, the obtained cationic polyacrylate has a higher solid content. Using it for soil improvement can enhance the water retention and fertilizer retention of the soil, enhance the soil's granular structure, improve the soil's permeability and drought resistance, and significantly improve the yield and quality of crops.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A cationic polypropylene derivative, wherein the cationic polypropylene derivative is a cationic polyacrylate, which is prepared according to the following method:

[0010] (1) Preparation of polymerization monomer pre-emulsion: adding water and a cationic emulsifier to an acrylate monomer, and emulsifying to obtain a polymerization monomer pre-emulsion;

[0011] (2) Preparation of cationic polyacrylate: half of the initiator and half of the pre-emulsion of the polymerization monomer are added to a reactor, and the temperature is raised until the emulsion emits a blue light, and the remaining initiator and the pre-emulsion of the polymerization monomer are added dropwise to the reactor. After the reaction is completed, an emulsion is obtained; the emulsion is sieved and freeze-dried to obtain the cationic polyacrylate.

[0012] Wherein, the cationic emulsifier described in the above step (1) is a mixture of dodecyldimethylbenzylammonium chloride and dodecyltrimethylammonium chloride;

[0013] Preferably, the mass ratio of dodecyldimethylbenzylammonium chloride to dodecyltrimethylammonium chloride is 1:3-5;

[0014] More preferably, the mass ratio of dodecyldimethylbenzylammonium chloride to dodecyltrimethylammonium chloride is 1:4.

[0015] The amount of the emulsifier added is 3-8% of the mass of the acrylate monomer; preferably 4-7%; more preferably 5-6% and further preferably 6%.

[0016] The emulsification temperature in step (1) is 20-30°C, preferably 25°C.

[0017] The emulsification speed is 8000-10000 r / min, preferably 9000 r / min.

[0018] The emulsification time is 5-8 minutes, preferably 6 minutes.

[0019] The initiator is azobisisobutylamidine hydrochloride, and the added amount of the initiator is 0.2-0.8% of the mass of the acrylate monomer; preferably 0.3-0.6%; more preferably 0.5%.

[0020] The acrylic acid monomer is butyl acrylate.

[0021] The heating temperature in the above step (2) is 70-80°C, preferably 75°C;

[0022] The above step (2) needs to be carried out under stirring conditions, and the stirring speed is 200-300r / min, preferably 300r / min.

[0023] The dropping time in the above step (2) is 2-3 hours, preferably 2.5 hours;

[0024] The time of the heat preservation reaction in the above step (2) is 1.5-2.5 hours, preferably 2.5 hours.

[0025] The present invention also provides application of the cationic polyacrylate in preparing a soil conditioner.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention uses dodecyldimethylbenzyl ammonium chloride and dodecyltrimethylammonium chloride as emulsifiers, and controls the mass ratio of dodecyldimethylbenzyl ammonium chloride to dodecyltrimethylammonium chloride so that the prepared cationic polyacrylate has a higher molecular weight and degree of substitution, and the obtained cationic polyacrylate latex particles have a higher solid content and better stability, and can better adsorb anions in the soil.

[0028] (2) Using the cationic polyacrylate prepared by the present invention as a component of a soil conditioner for soil improvement can significantly improve the water and fertilizer retention effect of the soil, enhance the soil aggregate structure, improve the soil permeability and drought resistance, and significantly improve the yield and quality of crops. DETAILED DESCRIPTION

[0029] The above features mentioned in the present invention or the features mentioned in the embodiments can be combined in any way. All the features explained in the specification of this case can be used in combination with any method form, and each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equal or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equal or similar features.

[0030] The present invention will be further described below in conjunction with specific examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In the following examples, the implementation methods for specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, all percentages and fractions are by weight.

[0031] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those known to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

[0032] Example 1 A cationic polypropylene derivative

[0033] The cationic polypropylene derivative is a cationic polyacrylate, which is prepared according to the following method:

[0034] (1) Preparation of polymerization monomer pre-emulsion: deionized water and a cationic emulsifier (dodecyldimethylbenzyl ammonium chloride and dodecyltrimethylammonium chloride in a mass ratio of 1:3, with an addition amount of 3% of the mass of the acrylate monomer) were added to butyl acrylate monomer, and emulsified at a speed of 8000 r / min and a temperature of 20° C. to obtain a polymerization monomer pre-emulsion;

[0035] (2) Preparation of initiator solution: Dissolve azobisisobutylamidine hydrochloride in deionized water, and the amount of initiator added is 0.2% of the mass of the acrylate monomer;

[0036] (3) Preparation of cationic polyacrylate: add half of the initiator and half of the pre-emulsion of the polymerization monomer into a reactor, heat to 70°C, stir at a speed of 200 r / min, and after the emulsion emits a blue light, add the remaining initiator and the pre-emulsion of the polymerization monomer dropwise into the reactor, keep warm and react for 2.5 hours. After the reaction is completed, an emulsion is obtained; sieve and freeze-dry to obtain the cationic polyacrylate.

[0037] Example 2 A cationic polypropylene derivative

[0038] The cationic polypropylene derivative is a cationic polyacrylate, which is prepared according to the following method:

[0039] (2) Preparation of polymerization monomer pre-emulsion: deionized water and a cationic emulsifier (dodecyldimethylbenzyl ammonium chloride and dodecyltrimethylammonium chloride in a mass ratio of 1:5, with an added amount of 8% of the mass of the acrylate monomer) were added to butyl acrylate monomer, and emulsified at a speed of 10,000 r / min and a temperature of 30° C. to obtain a polymerization monomer pre-emulsion;

[0040] (2) Preparation of initiator solution: Dissolve azobisisobutylamidine hydrochloride in deionized water, and the amount of initiator added is 0.8% of the mass of the acrylate monomer;

[0041] (3) Preparation of cationic polyacrylate: add half of the initiator and half of the pre-emulsion of the polymerization monomer into a reactor, heat to 80°C, stir at a speed of 300 r / min, and after the emulsion emits a blue light, add the remaining initiator and the pre-emulsion of the polymerization monomer dropwise into the reactor, keep warm and react for 1.5 hours. After the reaction is completed, an emulsion is obtained; sieve and freeze-dry to obtain the cationic polyacrylate.

[0042] Example 3 A cationic polypropylene derivative

[0043] The cationic polypropylene derivative is a cationic polyacrylate, which is prepared according to the following method:

[0044] (3) Preparation of polymerization monomer pre-emulsion: deionized water and a cationic emulsifier (dodecyldimethylbenzyl ammonium chloride and dodecyltrimethylammonium chloride in a mass ratio of 1:4, with an addition amount of 6% of the mass of the acrylate monomer) were added to butyl acrylate monomer, and emulsified at a speed of 9000 r / min and a temperature of 25° C. to obtain a polymerization monomer pre-emulsion;

[0045] (2) Preparation of initiator solution: Dissolve azobisisobutylamidine hydrochloride in deionized water, and the amount of initiator added is 0.5% of the mass of the acrylate monomer;

[0046] (3) Preparation of cationic polyacrylate: add half of the initiator and half of the pre-emulsion of the polymerization monomer into a reactor, heat to 75°C, stir at a speed of 300 r / min, and after the emulsion emits a blue light, add the remaining initiator and the pre-emulsion of the polymerization monomer dropwise into the reactor, keep warm and react for 2.5 hours. After the reaction is completed, an emulsion is obtained; sieve and freeze-dry to obtain the cationic polyacrylate.

[0047] Comparative Example 1

[0048] The difference from Example 3 is that the emulsifier is only dodecyl dimethyl benzyl ammonium chloride, and the rest is the same as Example 3.

[0049] Comparative Example 2

[0050] The difference from Example 3 is that the emulsifier is only dodecyltrimethylammonium chloride, and the rest is the same as Example 3.

[0051] Comparative Example 3

[0052] The difference from Example 3 is that the emulsifier is dodecyldimethylbenzyl ammonium chloride and dodecyltrimethylammonium chloride in a mass ratio of 1:1, and the rest is the same as Example 3.

[0053] Comparative Example 4

[0054] The difference from Example 3 is that the emulsifier is only hexadecyltrimethylammonium chloride, and the rest is the same as Example 3.

[0055] Performance data

[0056] 1. Cationic degree detection

[0057] The colloid titration method was used for determination. The test results are shown in Table 1 below.

[0058] Table 1

[0059] Cationicity % Example 1 21.5 Example 2 20.8 Example 3 23.4 Comparative Example 1 16.6 Comparative Example 2 17.2 Comparative Example 3 18.3 Comparative Example 4 17.5

[0060] According to the test results in Table 1 above, the present invention uses a mixture of dodecyldimethylbenzylammonium chloride and dodecyltrimethylammonium chloride as an emulsifier, and controls the ratio of the two to be 1:3-5, so that the prepared cationic polyacrylate has a higher cationic degree. Changing the type and ratio of the emulsifier will affect the cationic degree of the polymer to a certain extent, thereby affecting the soil improvement effect of the polyacrylate.

[0061] 2. Emulsion solid content detection

[0062] Weigh the emulsion sample M1g and place it in a 115℃ oven to dry to a constant weight of M2g. The solid content is calculated according to the following formula:

[0063] X=M2 / M1×100%

[0064] Where: X-solid content of emulsion sample; %;

[0065] M1-mass of sample before drying, g;

[0066] M2-mass of sample after drying, g.

[0067] The test results are shown in Table 2 below.

[0068] Table 2

[0069] Solid content% Example 1 30.58 Example 2 31.25 Example 3 35.53 Comparative Example 1 25.14 Comparative Example 2 25.07 Comparative Example 3 26.15 Comparative Example 4 25.10

[0070] According to the test results in Table 2 above, the present invention uses a mixture of dodecyldimethylbenzylammonium chloride and dodecyltrimethylammonium chloride as an emulsifier, and controls the ratio of the two to be 1:3-5, which can make the surface of the latex particles in the reaction system be closely arranged, thereby improving the stability between the latex particles, improving the stability of the emulsion during the polymerization process, and then improving the conversion rate of the monomer, thereby increasing the solid content. In the comparative example, the type or ratio of the emulsifier is changed, so that the surface of the latex particles is difficult to be closely arranged, thereby reducing the stability between the latex particles, reducing the monomer conversion rate, and then reducing the solid content of the emulsion.

[0071] 3. Water absorption test of cationic polyacrylate

[0072] Weigh the cationic polyacrylate dried to constant weight as m1, then place it in deionized water for 48 hours, absorb excess water on the surface of the sample and weigh it as m2. The water absorption rate is calculated according to the following formula:

[0073] W=m2-m1 / m1

[0074] Where, W = water absorption, %;

[0075] m1 = mass of the sample before immersion, g;

[0076] m2 = mass of the sample after immersion in water, g.

[0077] The test results are shown in Table 3 below.

[0078] Table 3

[0079] Water absorption % Example 1 12.58 Example 2 13.14 Example 3 15.26 Comparative Example 1 10.42 Comparative Example 2 10.58 Comparative Example 3 11.34 Comparative Example 4 10.16

[0080] According to the test results in Table 3 above, it can be seen that the cationic polyacrylates prepared in Examples 1-3 of the present invention have better water absorption effect, while in the comparative example, by changing the type or ratio of the emulsifier, the water absorption of the cationic polyacrylate obtained is significantly reduced, indicating that the cationic polyacrylate prepared by the present invention can better absorb water and promote plant growth when used for soil improvement.

[0081] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered as the protection scope of the present invention.

Claims

1. A cationic polypropylene derivative, wherein the cationic polypropylene derivative is a cationic polyacrylate, characterized in that: Prepared as follows: (1) Preparation of polymerization monomer pre-emulsion: adding water and a cationic emulsifier to an acrylate monomer, and emulsifying to obtain a polymerization monomer pre-emulsion; (2) Preparation of cationic polyacrylate: half of the initiator and half of the pre-emulsion of the polymerization monomer are added to a reactor, and the temperature is raised until the emulsion emits a blue light, and then the remaining initiator and the pre-emulsion of the polymerization monomer are added dropwise to the reactor. After the reaction is completed, an emulsion is obtained; the emulsion is sieved and freeze-dried to obtain the cationic polyacrylate; The cationic emulsifier described in step (1) is a mixture of dodecyldimethylbenzylammonium chloride and dodecyltrimethylammonium chloride.

2. The cationic polypropylene derivative according to claim 1, characterized in that: The mass ratio of dodecyldimethylbenzylammonium chloride to dodecyltrimethylammonium chloride is 1:3-5.

3. The cationic polypropylene derivative according to claim 2, characterized in that: The mass ratio of dodecyldimethylbenzylammonium chloride to dodecyltrimethylammonium chloride is 1:

4.

4. The cationic polypropylene derivative according to claim 1, characterized in that: The added amount of the emulsifier is 3-8% of the mass of the acrylic ester monomer.

5. The cationic polypropylene derivative according to claim 1, characterized in that: The emulsification temperature in step (1) is 20-30°C.

6. The cationic polypropylene derivative according to claim 1, characterized in that: The emulsification speed is 8000-10000r / min.

7. The cationic polypropylene derivative according to claim 1, characterized in that: The emulsification time is 5-8 minutes.

8. The cationic polypropylene derivative according to claim 1, characterized in that: The initiator is azobisisobutylamidine hydrochloride, and the added amount of the initiator is 0.2-0.8% of the mass of the acrylate monomer.

9. The cationic polypropylene derivative according to claim 1, characterized in that: The heating temperature in step (2) is 70-80°C; step (2) needs to be carried out under stirring conditions, and the stirring speed is 200-300r / min; the insulation reaction time is 1.5-2.5 hours.

10. Use of the cationic polyacrylate according to any one of claims 1 to 9 in the preparation of a soil conditioner.