CN116082084A - Interpenetrating network vegetable oil-based resin coated controlled release fertilizer and preparation method thereof - Google Patents

Abstract

The invention discloses an interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer and a preparation method thereof, belonging to the field of polymer materials and slow-controlled release fertilizers. The preparation method of the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer provided by the present invention comprises the following steps: (1) carrying out epoxidation reaction and ring-opening reaction on vegetable oil to prepare epoxy vegetable oil and vegetable oil polyol respectively; 2) Add isocyanate and amine curing agent to the vegetable oil polyol and epoxy plant oil to prepare a coating solution; add a catalyst to the coating solution and mix evenly, spray it on the surface of the core fertilizer, and form a polymer after curing reaction The film shell is obtained, that is, the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer is obtained. The fertilizer prepared by the method of the invention has high biomass content, excellent controlled release performance, low cost and easy degradation of residual film.

Description

Interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer and preparation method thereof

technical field

The invention relates to the field of polymer materials and controlled-release fertilizers, in particular to an interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer and a preparation method thereof.

Background technique

The application of chemical fertilizers has become the main way to increase the production and income of agricultural products in modern agricultural production. According to statistics, chemical fertilizers play an irreplaceable role in the development of agricultural production, with a contribution rate as high as 40% to 60%. Resin-coated fertilizer is a controlled-release fertilizer that uses various polymer materials to coat the surface of quick-acting fertilizers. It can achieve controlled release of nutrients by adjusting the coating structure and film thickness, thereby meeting the nutrient requirements of crops at each growth stage. It provides an effective way to solve problems such as fertilizer loss and agricultural non-point source pollution.

Polyurethane is a block copolymer composed of soft segment and hard segment formed by the reaction of polyol and isocyanate. Its performance can be changed by adjusting the two proportions and the composition of raw materials. It is the most common application of resin-coated fertilizers in recent years. A polymer coating material. Petrochemical raw materials are difficult to degrade and resources are non-renewable. With the implementation of the "Risk Control Guidelines for the Use of Fertilizer Coating Materials" (NY/T3502-2019), the biodegradation rate of membrane materials must reach more than 15% within 180 days. The development of vegetable oil Biodegradable resin-coated fertilizers such as biomass as raw materials have become a research hotspot in the fertilizer industry.

Vegetable oil has a wide range of sources, a variety of varieties, and low prices. After chemical modification, vegetable oil polyols can be synthesized. Such polyols can replace petroleum-based polyols and react with isocyanates to form polyurethane coatings. They are currently the most potential bio-based degradable coatings. one of the raw materials. CN106543397 discloses a vegetable oil-based coated fertilizer using modified palm oil as raw material. CN112159269 utilizes different kinds of vegetable oil polyols to directly react with isocyanate to prepare vegetable oil-based polyurethane-coated controlled-release fertilizer. Although vegetable oil-based coatings have good degradability and reproducibility, their application and popularization are severely restricted due to the fact that these materials are easy to absorb water, have many pores, and have poor nutrient control release effect in the film layer. Epoxy resin molecules contain epoxy groups and secondary hydroxyl groups. Due to the chemical activity of epoxy groups, various compounds containing active hydrogen can be used to open the ring, and then cured and cross-linked with isocyanate to form an interpenetrating network polymer. Polymers are more hydrophobic and abrasion resistant. CN107082706 uses dimer acid as the main raw material to synthesize an interpenetrating network polymer coated fertilizer with a coating rate of 5% to 9% and a controlled release period of 60 to 120 days. CN102320883 prepares a performance-adjustable polyurethane/epoxy resin composite-coated controlled-release fertilizer through in-situ reaction technology. Although these coated fertilizers have good controlled-release performance, the content of coated biomass is low, and the degradation of residual film is difficult, which makes it difficult to meet the new requirements of agricultural green development.

Among the patented technologies for the synthesis of vegetable oil polyols published at home and abroad in recent years, the epoxy ring-opening process is the most widely used. The two-step synthesis process can produce both vegetable oil polyols and epoxy vegetable oils. The process is simple , Easy to industrialized production. US20070123725 synthesized vegetable oil-based polyether polyols through a two-step method of epoxidation and hydroxylation of soybean oil and rapeseed oil. CN104945256 uses organic acid and hydrogen peroxide to epoxidize vegetable oil, and selects water as a ring-opening agent to synthesize an environment-friendly vegetable oil polyol. Therefore, the epoxy vegetable oil and the vegetable oil polyol synthesized by modifying the vegetable oil through the epoxy ring-opening technology can be used for fertilizer coating, and the vegetable oil-based resin coating with an interpenetrating network structure can be prepared by compounding the two. Improving the controlled release performance of the membrane material can also increase the biomass content of the membrane material and improve the degradation performance of the membrane material.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention provides an interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer and a preparation method thereof. The fertilizer of the present invention has high biomass content, excellent controlled-release performance, low cost, and low residual Membranes are easily degraded.

The present invention firstly provides a kind of preparation method of interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer, comprising the following steps:

(1) Vegetable oil, hydrogen peroxide, organic acid and inorganic acid are mixed to carry out epoxidation reaction. After the reaction is finished, the layering is allowed to stand, and the water layer is removed to obtain an epoxidation intermediate product, which is then neutralized, washed with water, and rotary steamed to prepare Obtain epoxidized vegetable oil; directly add alcohol ring-opening agent to the epoxidized intermediate product, carry out ring-opening reaction, the product obtained after the reaction is directly rotary steamed, and obtains vegetable oil polyol;

(2) Add isocyanate and amine curing agent to the vegetable oil polyol and epoxy vegetable oil, and mix uniformly to form a coating liquid; add a catalyst in the coating liquid and spray it on the surface of the core fertilizer, and form it after curing reaction The polymer film shell is to obtain the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer; the biomass content of the polymer film shell is 60% to 80%.

In the above preparation method, in step (1), the hydrogen peroxide is added dropwise to the mixed solution of the vegetable oil, organic acid and inorganic acid;

In the above preparation method, in step (1), the mass ratio of the vegetable oil, hydrogen peroxide, organic acid and inorganic acid is 1:0.4～0.8:0.1～0.3:0.001～0.005;

Specifically, the mass ratio of the vegetable oil, hydrogen peroxide, organic acid and inorganic acid can be 1:0.8:0.3:0.005, 1:0.5:0.25:0.004 or 1:0.4:0.1:0.001; 1:0.8:0.25:0.004 ;1:0.7:0.25:0.001;

The vegetable oil is at least one of palm oil, rapeseed oil, soybean oil, olive oil, linseed oil, corn oil and peanut oil; preferably soybean oil and rapeseed oil, more preferably rapeseed oil;

Described hydrogen peroxide is the hydrogen peroxide solution that mass percent concentration is 30%;

The organic acid is formic acid or acetic acid; preferably formic acid; the mass percent concentration of the organic acid is greater than or equal to 99%;

The inorganic acid is at least one of sulfuric acid, phosphoric acid and hydrochloric acid; preferred sulfuric acid; the mass percent concentration of the sulfuric acid is 98%; the mass percent concentration of the phosphoric acid is 85%; the mass percent concentration of the hydrochloric acid The concentration is 36%;

The mass ratio of the epoxidized intermediate product to the alcohol ring-opener is 1:0.6 to 1.0; specifically, it can be 1:1, 1:0.8 or 1:0.6; preferably 1:0.8;

The alcohol ring-opening agent is any one of methanol, ethylene glycol, propanol and butanol; preferably methanol;

The mass percent concentration of the alcohol ring opener is greater than or equal to 98%;

In the above preparation method, the temperature of the epoxidation reaction is 50-70°C; the time is 3-6.5h;

The temperature of the ring-opening reaction is 40-60°C; the time is 1-4h;

The condition of the rotary distillation is 50～70°C rotary distillation for 2～4h;

The neutralization reaction uses a sodium bicarbonate solution with a concentration of 5% by mass; the washing temperature is 30-50°C.

In the above preparation method, in step (2), in the coating liquid, the mass percentage of the vegetable oil polyol is 20% to 70%; specifically, it can be 25%, 36%, 42%, 56% or 63% %; the mass percentage of the isocyanate is 20% to 30%; specifically it can be 24%, 25%, 27% or 28%; the mass percentage of the epoxy vegetable oil is 8% to 40%; it can be specifically 8%, 16%, 24%, 32% or 40%; the mass percentage of the amine curing agent is 2% to 10%; specifically, it can be 2%, 4%, 6%, 8% or 10% ;

The mass of the catalyst is 0% to 1% of the mass of the coating liquid, and the mass of the catalyst is not 0; specifically, it can be 0.1%, 0.5% or 1%;

In the above-mentioned preparation method, the isocyanate is polymethylene polyphenyl polyisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate (MDI), liquefied MDI, isophorone diisocyanate , 1,6-hexamethylene diisocyanate (HDI), trimer of HDI, trimethylhexamethylene diisocyanate, xylylene diisocyanate and dimethyl biphenyl diisocyanate;

The amine curing agent is any one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylenepolyamine;

The catalyst is any one of triethylamine, triethanolamine, stannous octoate, dibutyltin dilaurate and stannous oleate;

The core fertilizer is any one of large particle urea and granular compound fertilizer; the average particle diameter of the core fertilizer particles is 2-6mm.

In the above preparation method, in step (2), the preparation temperature of the coating solution is 30-90°C;

The temperature of the curing reaction is 60-70°C;

The curing reaction is carried out in a drum or a fluidized bed.

The present invention further provides the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer prepared by the above preparation method.

In the above interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer, the quality of the resin coating is 2% to 5% of the mass of the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer; specifically, it can be 2%, 2.8%, 3%, 3.7% or 5%; the biomass content of the resin coating is 60%-80%; specifically, it can be 64%, 66%, 68%, 70% or 71%.

The present invention has following beneficial effect:

In the present invention, vegetable oil with abundant sources and low price is used as a raw material, and the vegetable oil is modified to synthesize epoxy vegetable oil and vegetable oil polyol through epoxy ring-opening technology, and the two are compounded to prepare an interpenetrating network vegetable oil-based resin coating for controlled release fertilizer. The raw material formula of the invention is simple, no chain extender and additives are added to the reaction system, the amount of isocyanate is reduced, and the biomass content of the coating is significantly increased, which not only improves the utilization rate of vegetable oil, but also reduces the cost of coating . The invention not only meets the requirements of biodegradable and green environmental protection, but also effectively improves the controlled release performance and degradation performance of the membrane material, and adjusts the controlled release and degradation performance of the membrane material by adjusting the ratio of raw materials, so that it can be prepared Degradable bio-based resin-coated controlled-release fertilizers with different controlled-release periods.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, and the given examples are only for clarifying the present invention, not for limiting the scope of the present invention.

The experimental methods in the following examples are conventional methods unless otherwise specified.

The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

The polymethylene polyphenyl polyisocyanates used in the following examples were purchased from Yantai Wanhua Company; diphenylmethane diisocyanate (MDI) was purchased from Bayer, Germany; toluene diisocyanate was purchased from Yantai Wanhua Company; 1,6 - Hexamethylene diisocyanate (HDI) was purchased from Bayer, Germany.

In the following examples, the method for determining the controlled-release performance of fertilizers by water immersion method is as follows: take 10 g of coated fertilizers and place them in a 100-mesh nylon mesh bag, and place the bag in a plastic container filled with 250 mL of distilled water after sealing. After sealing, put it in a constant temperature incubator at 25°C, and take samples at 1, 3, 7, 14, 28, 35, and 42 days to measure the nutrient dissolution data.

The release period refers to the number of days required for the cumulative release rate of the coated controlled-release fertilizer to reach 80% in water at 25°C.

Initial dissolution rate (%) = 24-hour cumulative dissolved nutrient amount/the content of this nutrient in the sample×100%.

The preparation process of the interpenetrating network vegetable oil-based resin-coated controlled-release fertilizer of the present invention is as follows: (1) Mix the vegetable oil, organic acid and inorganic acid uniformly in a certain proportion, add hydrogen peroxide dropwise at a constant speed in situ, and carry out the ring at 50-70°C. Oxidation reaction, after the reaction is finished, let it stand for stratification and remove the water layer to obtain an epoxidized intermediate product, and neutralize, wash, and rotate part of the product to obtain an epoxy vegetable oil; (2) add to the above-mentioned epoxidized intermediate product Alcohol ring-opening agent carries out ring-opening reaction to obtain vegetable oil polyol, and the reaction temperature is 40～60 ℃; This step omits the water washing step, and directly rotary steams after reaction to obtain vegetable oil polyol; (3) vegetable oil polyol and epoxy vegetable oil Mix evenly with isocyanate and amine curing agent to prepare coating solution, the reaction temperature is 30-90°C; (5) input the granular fertilizer into the drum or fluidized bed, and preheat at 60-70°C; (5) Spray the coating solution and catalyst on the granular fertilizer and solidify for 3-8 minutes; (6) Cool the fertilizer to room temperature and pack it.

Example 1

The preparation of epoxidized palm oil and palm oil polyol: take by weighing 200g palm oil, 60g acetic acid (99.8wt%) and 1g sulfuric acid (concentration 98wt%) join in the 500mL that has stirrer, condenser and constant pressure dropping funnel Put the three-necked flask in a 40°C oil bath for heating and stirring, then put 160g of hydrogen peroxide (30wt%) into the constant-pressure dropping funnel and drop it into the three-necked flask at a constant speed, and adjust the temperature to 65°C for 6.5 hours. Use a separating funnel to stand for stratification, remove the water layer, and obtain an epoxidized intermediate product; weigh 100g of an epoxidized intermediate product and 100g of methanol (99.5wt%) and add them to a three-necked flask to react at 60°C for 2.5h. The reaction product was rotary distilled at 60°C for 3 hours to obtain palm oil polyol; the remaining epoxidized intermediate product was neutralized with a 5% sodium bicarbonate solution by mass percentage, and then deionized water at 30°C Washing with water, and finally rotary steaming (conditions as above) to obtain epoxy palm oil.

Preparation of interpenetrating network palm oil-based coated controlled-release fertilizer: Weigh 1 kg of urea particles with a particle size of 2 to 4 mm, place them in a fluidized bed, and preheat to 60 ° C; Add 2.7g of polymethylene polyphenyl polyisocyanate and 0.2g of triethylenetetramine to oxygen palm oil and mix evenly to make a coating solution at 60°C, then add 0.1g of stannous octoate and spray it on the surface of the preheated fertilizer granules , solidified at 60°C to form a film, the spraying process was carried out 3 times, and the coating rate was 3%. After the spraying is completed, the interpenetrating network palm oil-based coated fertilizer is obtained by cooling, and the coated biomass content is 70%. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.6%, and the controlled-release period was 72 days.

Example 2

The preparation of epoxidized rapeseed oil and rapeseed oil polyol: take by weighing 200g rapeseed oil, 50g acetic acid (99.8wt%) and 0.8g sulfuric acid (concentration 98wt%) join to have agitator, condenser and constant pressure drop Put a 500mL three-necked flask with a liquid funnel in a 40°C oil bath for heating and stirring, then put 100g of hydrogen peroxide (30wt%) into the constant-pressure dropping funnel and drop it into the three-necked flask at a constant speed, and adjust the temperature to 70°C for 6 hours. After the reaction, the separatory funnel was used to stand to separate the layers, and the water layer was removed to obtain the epoxidized intermediate product. Take by weighing 100g epoxidation intermediate product and 80g methanol (99.5wt%) and join in there-necked flask and react at 50 DEG C for 4h, and the reaction product is rotary distilled at 50 DEG C for 4h to obtain rapeseed oil polyol; The epoxidized intermediate product was neutralized with 5% sodium bicarbonate solution by mass percentage, washed with deionized water at 40° C., and finally rotated (same as above) to obtain epoxidized rapeseed oil.

Preparation of interpenetrating network rapeseed oil-based coated controlled-release fertilizer: Weigh 1 kg of compound fertilizer particles (Beijing Futelai Compound Fertilizer Co., Ltd.) ℃; Add 2.8g diphenylmethane diisocyanate (MDI) and 0.6g diethylenetriamine to 4.2g rapeseed oil polyol and 2.4g epoxy rapeseed oil and mix evenly to prepare a coating solution at 30°C, then Add 0.01 g of triethylamine and spray on the surface of the preheated fertilizer granules, solidify and form a film at 70° C., the spraying process is carried out 5 times, and the coating rate is 5%. After the spraying is completed, the interpenetrating network rapeseed oil-based coated fertilizer is obtained by cooling, and the coated biomass content is 66%. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.1%, and the controlled-release period was 120 days.

Example 3

The preparation of epoxidized soybean oil and soybean oil polyol: Weigh 200g soybean oil, 20g formic acid (99wt%) and 0.2g phosphoric acid (85wt%) and join in a 500mL three-port with agitator, condenser and constant pressure dropping funnel Put the flask in a 40°C oil bath for heating and stirring, then put 80g of hydrogen peroxide (30wt%) into a constant pressure dropping funnel and drop it into the three-necked flask at a constant speed, adjust the temperature to 50°C for 3 hours, and use a separate The liquid funnel was left to stand for stratification, and the water layer was removed to obtain an epoxidized intermediate product. Take by weighing 100g epoxidation intermediate product and 60g ethylene glycol (98wt%) and join in there-necked flask and react at 60 DEG C for 1h, and the reaction product is rotary distilled at 70 DEG C for 2h to obtain soybean oil polyol; The epoxidized intermediate product was neutralized with 5% sodium bicarbonate solution by mass percentage, washed with deionized water at 30° C., and finally rotated (same as above) to obtain epoxidized soybean oil.

Preparation of interpenetrating network soybean oil-based coated controlled-release fertilizer: Weigh 1 kg of urea particles with a particle size of 3 to 6 mm, place them in a fluidized bed, and preheat to 65 ° C; add 2.5 g of soybean oil polyol and 4 g of epoxy Add 2.5g of toluene diisocyanate and 1g of tetraethylenepentamine to soybean oil and mix them evenly to make a coating solution at 50°C, then add 0.1g of dibutyltin dilaurate and spray on the surface of the preheated fertilizer granules, and then cure at 65°C For film formation, the spraying process is carried out twice, and the coating rate is 2%. After the spraying is completed, the interpenetrating network soybean oil-based coated fertilizer is obtained by cooling, and the coated biomass content is 64%. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 1.6%, and the controlled-release period was 40 days.

Example 4

The preparation of epoxy rapeseed oil and rapeseed oil polyol: take by weighing 200g rapeseed oil, 50g formic acid (99wt%) and 0.8g sulfuric acid (98wt%) join in with agitator, condenser and constant pressure dropping funnel In a 500mL three-necked flask, put it in a 40°C oil bath for heating and stirring, then put 160g of hydrogen peroxide (30wt%) into the constant pressure dropping funnel and drop it into the three-necked flask at a constant speed, adjust the temperature to 65°C for 6.5h, and react After the completion, the separatory funnel was used to stand for stratification, and the water layer was removed to obtain the epoxidation intermediate product. Weigh 100g of epoxidized intermediate product and 100g of propanol (99.5wt%) and join in a three-necked flask to react at 40°C for 4h, and rotate the reaction product at 65°C for 2.5h to obtain rapeseed oil polyol; The remaining epoxidized intermediate product was neutralized with 5% sodium bicarbonate solution by mass percentage, washed with deionized water at 30° C., and finally rotated (same as above) to obtain epoxidized rapeseed oil.

Preparation of interpenetrating network rapeseed oil-based coated controlled-release fertilizer: weigh 1 kg of urea particles with a particle size of 3 to 5 mm, place them in a fluidized bed, and preheat to 65 °C; add 5.6 g of rapeseed oil polyol and 1.6 Add 2.4g 1,6-hexamethylene diisocyanate (HDI) and 0.4g triethylenetetramine to 1g epoxy rapeseed oil and mix evenly to prepare coating solution at 65°C, then add 0.1g stannous octoate to spray on the preheated fertilizer The particle surface is cured to form a film at 65°C. The spraying process is carried out three times, and the coating rate is 2.8%. After the spraying is completed, the interpenetrating network rapeseed oil-based coated fertilizer is obtained by cooling, and the coated biomass content is 71%. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.7%, and the controlled-release period was 65 days.

Example 5

The preparation of epoxidized corn oil and corn oil polyol: take by weighing 200g corn oil, 50g acetic acid (99.8wt%) and 0.2g hydrochloric acid (36wt%) join in the 500mL that has stirrer, condenser tube and constant pressure dropping funnel In the three-necked flask, place it in a 40°C oil bath for heating and stirring, then put 140g of hydrogen peroxide (30wt%) into the constant-pressure dropping funnel and drop it into the three-necked flask at a constant speed, adjust the temperature to 65°C for 6 hours, and use The separatory funnel was allowed to stand for stratification, and the water layer was removed to obtain the epoxidized intermediate product. Take by weighing 100g epoxidation intermediate product and 80g butanol (99.5wt%) and join in there-necked flask and react at 60 DEG C for 2.5h, and the reaction product is rotary distilled at 60 DEG C for 3h to obtain corn oil polyol; The epoxidized intermediate product was neutralized with a 5% sodium bicarbonate solution by mass percent concentration, washed with deionized water at 50° C., and finally rotated (same as above) to obtain epoxidized corn oil.

Preparation of interpenetrating network corn oil-based coated controlled-release fertilizer: Weigh 1 kg of urea particles with a particle size of 2 to 5 mm, place them in a fluidized bed, and preheat to 65 ° C; Add 2.4g polymethylene polyphenyl polyisocyanate and 0.8g polyethylene polyamine to oxycorn oil and mix evenly at 90°C to make a coating solution, then add 0.05g stannous oleate and spray it on the surface of the preheated fertilizer granules , solidified at 65°C to form a film, the spraying process was carried out 4 times, and the coating rate was 3.7%. After the spraying is completed, the interpenetrating network corn oil-based coated fertilizer is obtained by cooling, and the coated biomass content is 68%. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.3%, and the controlled-release period was 93 days.

Comparative example 1

The same as the preparation of palm oil polyols in Example 1, the difference is that in the process of preparing coated fertilizers, only palm oil polyols are used as raw materials and isocyanates to form films through in-situ reaction to obtain vegetable oil-based polyurethane coated controlled release Fertilizers, not IPN resin-coated fertilizers. Compared with the coated fertilizer prepared in Example 1, the controlled release of the coated fertilizer is reduced, indicating that the interpenetrating network vegetable oil-based resin coated controlled-release fertilizer prepared by compounding epoxy vegetable oil and vegetable oil polyol is controlled-release Performance is better.

Concrete method is as follows: the preparation of palm oil polyol: take by weighing 200g palm oil, 60g acetic acid (99.8wt%) and 1g sulfuric acid (98wt%) join in the 500mL there-necked flask that has stirrer, condenser tube and constant pressure dropping funnel placed in a 40°C oil bath for heating and stirring, then put 160g of hydrogen peroxide (30wt%) into a constant pressure dropping funnel and drop it into a three-necked flask at a constant speed, adjust the temperature to 65°C for 6.5 hours, and use a separate The liquid funnel was left to stand for stratification, and the water layer was removed to obtain an epoxidized intermediate product. Weigh 100g of epoxidized intermediate product and 100g of methanol (99.5wt%) into a three-necked flask to react at 60°C for 2.5h, and rotate the reaction product at 60°C for 3h to obtain palm oil polyol.

Preparation of palm oil-based coated controlled-release fertilizer: Weigh 1 kg of urea particles with a particle size of 2 to 4 mm, place them in a fluidized bed, and preheat to 60°C; mix 6.5 g of palm oil polyols and 3.5 g of polymethylene Polyphenyl polyisocyanate was mixed at 60°C to form a coating solution, then 0.1g of stannous octoate was added and sprayed on the surface of the preheated fertilizer granules, and solidified at 60°C to form a film. The spraying process was carried out 3 times, and the coating rate was 2.9 %. After the spraying is completed, the palm oil-based coated fertilizer is obtained by cooling. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 1.2%, and the controlled-release period was 21 days.

Claims (8)

1. The preparation method of the interpenetrating network vegetable oil-based resin coated controlled release fertilizer comprises the following steps:

(1) Mixing vegetable oil, hydrogen peroxide, organic acid and inorganic acid, performing epoxidation reaction, standing for layering after the reaction is finished, removing a water layer to obtain an epoxidation intermediate product, and performing neutralization, water washing and rotary steaming to obtain the epoxy vegetable oil; directly adding an alcohol ring-opening agent into the epoxidation intermediate product, carrying out ring-opening reaction, and directly performing rotary evaporation on the product obtained after the reaction to obtain vegetable oil polyol;

(2) Adding isocyanate and amine curing agent into the vegetable oil polyol and the epoxy vegetable oil, and uniformly mixing to prepare coating liquid; adding a catalyst into the coating liquid, spraying the coating liquid on the surface of the core fertilizer, and forming a polymer film shell after curing reaction to obtain the interpenetrating network vegetable oil-based resin coated controlled release fertilizer; the biomass content of the polymer membrane shell is 60% -80%.

2. The method of manufacturing according to claim 1, characterized in that: the mass ratio of the vegetable oil to the hydrogen peroxide to the organic acid to the inorganic acid is 1:0.4-0.8:0.1-0.3:0.001-0.005;

the mass ratio of the epoxidation intermediate product to the alcohol ring-opening agent is 1:0.6-1.0;

the vegetable oil is at least one of palm oil, rapeseed oil, soybean oil, olive oil, linseed oil, corn oil and peanut oil;

the organic acid is formic acid or acetic acid;

the inorganic acid is at least one of sulfuric acid, phosphoric acid and hydrochloric acid;

the alcohol ring-opening agent is any one of methanol, glycol, propanol and butanol.

3. The preparation method according to claim 1 or 2, characterized in that: the temperature of the epoxidation reaction is 50-70 ℃ and the time is 3-6.5 h;

the temperature of the ring-opening reaction is 40-60 ℃ and the time is 1-4 h;

the rotary distillation condition is that the rotary distillation is carried out for 2-4 hours at 50-70 ℃.

4. A production method according to any one of claims 1 to 3, characterized in that: in the coating liquid, the mass percentage of the plant oil polyol is 20% -70%; the isocyanate accounts for 20-30% by mass; the mass percentage of the epoxy vegetable oil is 8% -40%; the mass percentage of the amine curing agent is 2% -10%;

the mass of the catalyst is 0-1% of the mass of the coating liquid, and the mass of the catalyst is not 0.

5. The method according to any one of claims 1 to 4, wherein: the isocyanate is at least one of polymethylene polyphenyl polyisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate (MDI), liquefied MDI, isophorone diisocyanate, 1, 6-Hexamethylene Diisocyanate (HDI), trimer of HDI, trimethyl hexamethylene diisocyanate, xylylene diisocyanate and dimethylbiphenyl diisocyanate;

the amine curing agent is any one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethylene polyamine;

the catalyst is any one of triethylamine, triethanolamine, stannous octoate, dibutyl tin dilaurate and stannous oleate;

the core fertilizer is any one of large-particle urea and particle compound fertilizer; the average grain diameter of the core fertilizer grains is 2-6 mm.

6. The production method according to any one of claims 1 to 5, characterized in that: in the step (2), the preparation temperature of the coating liquid is 30-90 ℃;

the temperature of the curing reaction is 60-70 ℃;

the curing reaction is carried out in a rotating drum or a fluidized bed.

7. The interpenetrating network vegetable oil-based resin coated controlled release fertilizer prepared by the preparation method of claims 1-6.

8. The interpenetrating network vegetable oil-based resin coated controlled release fertilizer according to claim 7, characterized in that: the mass of the resin coating accounts for 2% -5% of the mass of the interpenetrating network vegetable oil-based resin coating controlled release fertilizer; the content of the resin coated biomass is 60% -80%.