JPS5935875B2 - Method for producing coated granular fertilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an inexpensive, poorly soluble coated granular fertilizer.

In recent years, with the advancement of agricultural technology, a large amount of fertilizer has been applied at one time for the purpose of increasing yield and saving labor by reducing the number of times of fertilization.

For this reason, the form of the fertilizer is adapted to the growth of the crop, and the rate of elution of the fertilizer into the soil is adjusted, concentration disturbance, runoff of the fertilizing ingredients, fixation, etc., in order to absorb the required amount of fertilizing ingredients at the required time. There is a growing demand for something that can prevent the loss of nutrients and supply various nutrients to crops over a long period of time.

For this purpose, granular fertilizers are conventionally known in which the surface of the fertilizer is coated with a water-resistant coating such as various organic polymer compounds, oils, fats, waxes, etc.; Gender-based blocking phenomenon is likely to occur;
When heat-treated coating raw materials are coated, pinholes tend to occur, making it difficult to prevent pinholes from occurring in a single treatment and requiring thick coating, which increases costs.Furthermore, mechanical strength under water is poor. The reality is that the effect of suppressing fertilizer elution has not been sufficiently achieved due to its weakness.

It is also possible to form a relatively durable film by mixing mineral powder such as Merck or diatom with liquid resin, or by spraying resin slime and then applying powdered resin and heat treating, but this is similar to multilayer treatment. This method has the disadvantage that unevenness tends to occur on the surface of the fertilizer particles, complicating the processing process.

Paraffin wax melts at low temperatures, is inexpensive, and is decomposed by microorganisms in the soil, making it suitable as a coating material, but it easily penetrates into fertilizer particles, so slow release cannot be expected when treated in small quantities, and it is not abrasion resistant. Because of its poor adhesiveness and adhesion, when it is coated on fertilizer particles, it may cause damage to the film such as cracking or localized peeling during transportation, and the effect of slowing release may not be expected.

Furthermore, it tends to soften during high temperatures in the summer (causing deformation and clumping).

Blend wax is a mixed wax containing paraffin wax, two or more types of polyalkylene, and a dispersant such as PVA alginic acid, starch, vegetable gum (gum arabic), or cellulose derivative (CMC), and is usually paraffin wax 80.
~20 parts by weight, 20 to 80 parts by weight of polyalkylene, and 1 to 5 parts by weight of a dispersant, which imparts water resistance to paraffin wax.
It has abrasion resistance, is inexpensive and has a high melting point (100
℃), but its mechanical strength is low (and its ability to suppress elution in water is poor, requiring a thick coating).

Polyalkylene used in this N includes polyethylene, polypropylene, polybutylene, polyhexylene, etc., but polyethylene and polypropylene are common.

On the other hand, rosin is inexpensive, decomposable in soil, and forms a hard film that has excellent mechanical strength in water, but when coating a molten material, it is highly agglomerated and stringy, forming a uniform film. It is difficult to remove pinholes.

The present inventors have discovered that paraffin wax, blended wax, and rosin are coating materials that have many drawbacks when used alone, but by combining paraffin wax and rosin or blended wax and rosin in any ratio, they can be eutectic and fluid. Focusing on the formation of a eutectic with good hardness, when treating granular fertilizer with a eutectic of both, the eutectic penetrates into the interior sufficiently and forms an extremely firm film in a small amount, resulting in improved hardness, abrasion resistance,
It has been found that the coating material has extremely good water resistance and adhesion.

The present invention has been achieved based on the above findings.-C-A The method of the present invention involves mixing paraffin wax or blended wax with 30 to 80% (weight i) of rosin and heating it to form a eutectic liquid. It is characterized by treating and coating granular fertilizer with a eutectic solution.

In this case, the coverage is usually 2 to 10%, preferably 3 to 5%.
%, but this depends on the set value of the elution rate and can be changed arbitrarily.

The granular fertilizers used in the present invention include phosphate fertilizers, potassium fertilizers, nitrogen fertilizers, and synthetic fertilizers containing nitrogen, phosphorus, and potassium, and all granular fertilizers manufactured by the commonly used transfer method, paddle mixer, etc. Be used.

On the other hand, to explain the eutectic solution of paraffin wax and rosin or blended wax and rosin, which are processing liquids, paraffin wax has a softening point of approximately 40 to 70°C, and waxes other than those with a particularly high melting point deform and solidify during high temperatures in summer. There is a risk that it will end.

Its hardness is low and its film is extremely fragile.

Also, the viscosity of blended wax is 450 cp at 150°C.
and high (lack of liquidity).

On the other hand, rosin includes Watt rosin, tall oil rosin, and gum rosin, and although the melting point is 80 to 90°C and the viscosity of the melt is low, granulation during coating is severe and it is difficult to perform a coating treatment with the melt.

However, both eutectic liquids have extremely high fluidity and are easy to coat, making it possible to form a film that exhibits a large elution-suppressing effect with a low coverage rate.

There is an optimal mixing composition range for the mixing ratio of paraffin wax and rosin or blended wax and rosin used in the method of the present invention, and outside this range, the abrasion resistance and
The effect of improving adhesion and suppressing fertilizer elution cannot be expected.

That is, the desired effect can be achieved by coating the granular fertilizer with a heated eutectic solution in which 30 to 80% (by weight), preferably 40 to 70%, of rosin is added to paraffin wax or blended wax. be.

The reason for this is that if the amount of rosin mixed is less than 30%, the water resistance strength in water will decrease, the film will become brittle, the film will rapidly break down, and the ability to suppress elution will be lost. Consolidation is remarkable during high temperatures in summer.

On the other hand, if the amount of rosin exceeds 80%, the granules will aggregate when coated on the granular fertilizer, making it impossible to form a uniform film and preventing the formation of pinholes. This means that efficacy cannot be expressed.

The apparatus for coating the shed with paraffin wax-rosin or blended wax-rosin eutectic liquid used in the method of the present invention is a rotating drum, a dish-shaped rolling device, etc., in which granular fertilizer is placed and sprayed onto it. Alternatively, a method of coating by immersing in a eutectic liquid may be mentioned.

The granular fertilizer particles coated in this way are cooled and solidified while rolling the eutectic liquid adhering to the surface, or are removed using a centrifuge, etc., and cooled to below the softening point of the eutectic liquid using a rotary cooler. The particle shape can be adjusted by adding mineral powder such as talc.

As described above, by applying the method of the present invention, fertilizer grains that are normally water-soluble can be made slow-release, and there is no need for divided fertilization (even if paternity is to be achieved, the number of fertilization times can be significantly reduced).

In addition, there is no risk of unnecessary flow chambers or concentration disturbances, and the hardness of the fertilizer grains is high and the moisture absorption is significantly reduced, so there is no inconvenience during storage and handling, and the high fluidity makes it suitable for mechanical fertilization. It is also extremely convenient and contributes to labor saving in agriculture.

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Shiojiri Rin'an No. 1 (N:P2O5:N2O-
14=14:14) 2 kg was transferred in a rotating pan at 120°C, and paraffin wax (melting point 68-7
A coated fertilizer with a coverage rate of 4.2% was obtained by spraying a mixed melt at 130°C in which the blending ratio of 0°C) and rosin was sprayed onto granular fertilizer, and cooling and solidifying it by blowing cold air.

The results of measuring the dissolution rate of these fertilizers are shown in the table below.

(The elution rate is calculated by soaking 5 g of coated fertilizer in 100 ml of water,
After being left at 0°C for a certain period of time, the amount of ammonia nitrogen eluted was measured.

) Example 2 Using the method of Example 1, coated fertilizers with varying coverage ratios were obtained using a mixed melt of 50 parts of paraffin wax and 50 parts of rosin, and the elution ratios are shown below.

Example 3 2 kg of Shiojiri Rin'an No. 1 with a particle size of 4 to 5 yen was transferred in a rotary pan in an atmosphere of 120°C, and paraffin wax 60
After spraying a molten mixture of 50 parts of a blended wax consisting of 30 parts of polypropylene, 8 parts of polyethylene, and 2 parts of polyvinyl alcohol and 50 parts of rosin onto granular fertilizer, the mixture was cooled and solidified by blowing cold air, and the coverage was changed arbitrarily. A coated fertilizer was obtained.

The results of measuring the dissolution rate of these fertilizers are shown below.

Example 4 In the method of Example 3, 50 parts of paraffin socks,
A coated fertilizer with a coverage of 3.5% was prepared using a mixed melt of 50 parts of blended wax consisting of 25 parts of polypropylene, 23 parts of polyethylene, and 2 parts of polyvinyl alcohol and 50 parts of rosin, and the elution rate thereof is shown in the following table.

Example 5 2 kg of Shiojiri Rin'an No. 1 with a particle size of 4 to 51n11L was heated at 120°C
The fertilizer was rolled in a rotary pan in an atmosphere of A coated fertilizer was obtained.

Further, as Comparative Example 1, coated fertilizers were obtained with varying coverage rates using only blended wax, and the elution rates are shown below.

Example 6 Nitrogen-potassium chemical formation with a particle size of 4 to 5 mm (N: 20-18:1
6) 2 kg of fertilizer was produced in the same manner as in Example 1 to obtain a coated fertilizer with a coverage rate of 5% by arbitrarily changing the blending ratio of paraffin wax (melting point 68 to 70°C) and rosin.

The results of measuring the dissolution rate of these fertilizers are shown in the table below.

Example 7 2 kg of Shiojiri Rin'an No. 1 with a particle size of 3 to 4 mm was transferred in a rotary pan in an atmosphere of 120°C, and a mixed melt at 150°C was obtained by arbitrarily changing the blending ratio of the blended wax and rosin of Example 3. After spraying on granular fertilizer, cold air was blown to cool and solidify, to obtain a coated fertilizer with a coverage rate of 4.3%.

The results of measuring the dissolution rate of these fertilizers are shown in the table below.

Comparative Example 2 2 kg of Shiojiri Rin'an No. 1 with a particle size of 4 to 5 mm was transferred in a rotating pan in an atmosphere of 120°C, and a mixed melt of 30 parts of blended wax and 70 parts of petroleum resin (Vetrozin 130+) was sprayed onto the fertilizer. Afterwards, it was air cooled to obtain a coated fertilizer with an arbitrary coverage rate.

The results of measuring the dissolution rate of these fertilizers are shown in the table below.

Claims (1)

[Claims] 1. A method for producing coated granular fertilizer, which comprises mixing 30 to 80% (by weight) of rosin with paraffin wax or blended wax and coating the granular fertilizer as a heated eutectic solution.