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Production method for polyurethane enveloped controlled release fertilizer

A polyurethane and coating technology, which is applied in the field of polyurethane coated fertilizer preparation, can solve problems such as difficult automatic continuous operation, difficult control of reaction products, and interruption of operation, so as to shorten the probability and time of particle contact, shorten the distribution and reaction time , prevent moisture and bonding effect

Active Publication Date: 2013-12-04
INST OF AGRI RESOURCES & REGIONAL PLANNING CHINESE ACADEMY OF AGRI SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] To sum up, in the process currently used for the production of polyurethane coated fertilizers, the reaction materials are added intermittently, the operation is relatively complicated, and it is difficult to carry out automatically and continuously, and there are some disadvantages:
[0007] 1. Most of the reaction materials are added separately and successively. After each reaction monomer is added, it takes a period of time to make it evenly distributed. There are shortcomings of uneven distribution of reaction materials and difficult control of reaction products;
[0008] 2. The reaction material is added intermittently, and it needs to go through three stages of uniform coating, reaction, and curing film formation. Especially in the curing stage, the viscosity of the polymer suddenly increases, and the phenomenon of particles sticking into groups is prone to occur, which makes the operation Interruption, and strong agitation of the sticky mass is easy to destroy the film layer, so the controlled release performance is very unstable;
[0009] 3. The coating equipment is a drum or a disc, and the particles can only do rolling motion in the drum. The particles are in close contact with each other, and they are prone to adhesion and wear.

Method used

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  • Production method for polyurethane enveloped controlled release fertilizer
  • Production method for polyurethane enveloped controlled release fertilizer
  • Production method for polyurethane enveloped controlled release fertilizer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1 Continuous Spray Coating Experiment of Reaction Material

[0030] The fluidized bed cylindrical section used in this embodiment has a diameter of 150 mm, a length of 450 mm, a cone bottom diameter of 100 mm, and a cone angle of 65°.

[0031] The coating operation method and steps are as follows: First, adjust the coating parameters so that the fluidizing gas volume is 200m 3 / h, the compressed gas pressure is 0.2MPa, the gas volume is 200L / h, and the fluidized gas temperature is 85°C; secondly, weigh 1.5kg of large particle urea, add it from the exhaust port, and preheat for 2min; then, spray 10g of liquid Paraffin wax, pretreatment of urea, the treatment time is 2min; the fourth step, according to the molar ratio of isocyanate and polyol is 1.1:1, weigh about 12g of PAPI and 30g of castor oil (hydroxyl value 163), respectively according to 0.4 Add gPAPI / min and 1g castor oil / min into the nozzle with a peristaltic pump, and atomize the coating through the nozzl...

Embodiment 2

[0033] Embodiment 2 The influence of reaction material addition mode on coating operation

[0034] In order to verify the effect of rapid spray (mixed spray) coating operation after external mixing on coating operation, several different addition methods were used in the study, and the effects of addition methods on coating operation and fertilizer release performance were compared.

[0035] Addition methods of reaction materials include: intermittent successive dripping, intermittent simultaneous dripping, continuous simultaneous dripping, continuous simultaneous spraying, rapid spraying after external mixing (same as Example 1), and spraying after prepolymerization. Six treatment schemes, experimental conditions and control Parameter is the same as embodiment 1. The obtained experimental samples were tested for release performance by water immersion method. The experimental results are shown in Table 1.

[0036] Table 1 Effects of reaction material addition methods on coat...

Embodiment 3

[0039] Example 3 Effect of External Mixing Spray Treatment on the Reaction of Different Polyurethane Coatings

[0040] Using the same process conditions as in Example 1, the reaction materials were added in the form of external mixing spray coating, and the differences in reaction coating between three polyols with hydroxyl values ​​of 415, 163 and 55 and isocyanate (PAPI) were compared. The release rate of the coated sample was measured by water immersion method, and the structure is shown in Table 2.

[0041] Table 2 Effect of external mixing spray treatment on the reaction of different polyurethane coatings

[0042]

[0043] The reaction rate between polyols with different hydroxyl values ​​and PAPI is quite different. Three kinds of polyols with different hydroxyl values ​​were used in this experiment. In the test, it was found that No. 1 treatment had the best fluidization state in the whole process. Therefore, as a polyurethane coating, the reaction speed of the reac...

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Abstract

The invention relates to a production method for polyurethane enveloped controlled release fertilizer. The production method comprises the following steps: preheating granulated fertilizer in a fluidized bed in a fluidizing state; atomizing liquid paraffin, and pretreating the surface of the granulated fertilizer; mixing polyatomic alcohol and isocyanate in a nozzle, atomizing the mixture fast, and spraying the mixture onto the surface of the granulated fertilizer; controlling material adding speeds to ensure that polyurethane reaction can be fulfilled fast; adding liquid paraffin and carrying out surface anti-sticking treatment after the filling of reaction materials. According to the invention, the fluidized bed is adopted as enveloping equipment, polyatomic alcohol and isocyanate are used for spraying and enveloping after being premixed, and the adding speeds are regulated in a matched manner, so that the whole enveloping reaction process is fast and continuous. The production method can improve the polyurethane enveloping efficiency to a relatively large extent, and ensure relatively stable and reliable quality of the enveloped fertilizer due to continuous reaction.

Description

technical field [0001] The invention relates to a preparation method of polyurethane coated fertilizer. The method can continuously distribute the reaction materials to the surface of the particles in a fluidized state, can promote the rapid completion of the polyurethane reaction process, make the mixing, coating, reaction and curing process of the reaction materials uniform and rapid, and effectively prevent the particle-to-particle contact. The adhesion between them solves the problem that large-grained fertilizers are easy to bond and damage the controlled-release performance of the film layer during the coating process. The method can continuously atomize castor oil and other vegetable oil polyols and isocyanate onto the surface of fertilizer particles to prepare coated fertilizers with controlled release performance. The method is mainly used for the coating operation of polyurethane reaction film formation, and is especially suitable for continuous production of film-c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C05G3/00
Inventor 杨相东赵秉强李燕婷李娟林治安袁亮
Owner INST OF AGRI RESOURCES & REGIONAL PLANNING CHINESE ACADEMY OF AGRI SCI
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