JPS5828313B2 - Dojiyoukairiyouzaino Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing granules of a soil conditioner containing an acrylamide polymer as an active ingredient, and particularly to a method for producing granules with excellent storage stability.

Water-soluble polymers, such as polyvinyl alcohol, polyacrylamide, polyacrylic acid, and their salts, aggregate soil particles and change soil air permeability, water permeability, and thermal conductivity, making the soil suitable for plant growth. Modifications to suitable structures are well known.

Water-soluble polymers are usually prepared by polymerizing the corresponding monomers in aqueous solution or by precipitation (or suspension) polymerization in a non-solvent for the polymer, with the former in the form of an aqueous solution and the latter in the form of a powder. A shaped (or granular) polymer is obtained.

However, aqueous polymer solutions obtained by aqueous polymerization usually have extremely high viscosity and must be diluted with a large amount of water on site when applied to soil, which requires a great deal of labor in areas without water access.

In addition, powdered (or granular) polymers can be easily sprayed on the soil as is, but when applied to damp farmland, it is difficult to apply the water-soluble polymer to water. The so-called "mamako phenomenon" occurs, making it impossible to treat the soil uniformly.

Conventionally, as a solution to these problems, it has been known to dilute water-soluble polymers with various inert carriers and apply them to the soil in the form of granules.
In No. 22368, a method for producing granules with good performance consisting of a water-soluble polymer mainly composed of polyacrylamide and a calcined powder of silicic acid or silicate minerals (carrier) was proposed.

In this method, granules are usually produced by blending a carrier into an aqueous polymer solution, granulating it, and then drying it as appropriate. Subsequent research revealed that performance deteriorated significantly.

For example, the sodium salt of acrylamide-acrylic acid copolymer [acrylamide/acrylic acid = 85/15 (
Changes over time in the "wet disintegration rate" and "polymer elution rate" of granules when the residual moisture content of granules made of granules made of calcined diatoms ±95% by weight was varied and the average molecular weight was approximately 3,000,000% by weight. were as shown in Table 1 below.

(In addition, "wet disintegration rate" refers to approximately 50 m of granules of approximately 1 g.
After immersing the granules in pure water (1) and leaving them for 24 hours, the state of disintegration of the granules was observed and the ratio of completely disintegrated granules to the original granules was calculated as a percentage. The granules were immersed in an amount such that the polymer concentration was 0.1% by weight in 100ml of pure water, shaken for 2 hours, the suspension was centrifuged, and the resulting filtrate was analyzed for nitrogen. The ratio of the determined amount of polymer to the original polymer as a percentage
It was a hailstorm.

Granules applied to soil usually disintegrate when wet due to the action of irrigation or rainwater after application and spread over the soil surface, and then the polymer is eluted from the carrier and penetrates into the soil.

Therefore, in order to effectively utilize the polymer in the granules for soil treatment, it is necessary that the granules'"wet disintegration rate" and "polymer elution rate" are as high as possible, and the higher these values, the better the performance of the granules. In good condition.

) As is clear from Table 1, this granule shows little performance deterioration during storage as long as the residual moisture content after drying is small (2.0% or less in the table), but the G trick is that the residual moisture content increases. The performance deterioration during storage becomes significant, and the water content (
5.2% in the table), the performance deterioration reaches its maximum, and after that, the residual moisture content increases (therefore, there is a tendency that the performance deterioration during storage decreases).

Therefore, when manufacturing these granules, sufficient care must be taken in drying and the residual moisture content of the granules must be adjusted to an amount that will minimize performance deterioration during storage. is accompanied by various complications.

The present invention has been made in order to correct such drawbacks, and the present inventors have produced soil conditioner granules containing an acrylamide polymer and a calcined powder of silicic acid or silicate minerals as main components. As a result of various studies on methods of rubbing the granules to prevent the performance of the granules from deteriorating even when the residual moisture content in the granules after drying is reduced to 07, we found that The present invention was achieved based on the knowledge that the objective can be achieved by incorporating the compound into the compound.

That is, the present invention provides a method for producing granules of a soil conditioner containing (1) an acrylamide-based polymer and (2) at least one calcined powder selected from silicic acid or silicate minerals as a main component. , urea, guanylurea phosphate, sulfate or nitrate, guanidine phosphate, sulfate or nitrate, cyanamide, dicyandiamide and amidinothiourea. The gist of this paper is a method for producing a soil conditioner characterized by the following.

The present invention will be explained below.

The acrylamide-based polymer used in the present invention is a water-soluble polymer mainly composed of polyacrylamide or polymethacrylamide, and representative examples thereof include:
Examples include partial hydrolysates of each, and copolymers (or salts thereof) of acrylamide or methacrylamide with acrylic acid, particularly polyacrylamide with a hydrolysis rate of 5 to 30% or acrylic acid components of 5 to 30% by weight. An acrylamide-acrylic acid copolymer (or a salt thereof) containing the above is preferably used.

As these polymers, those having an average molecular weight of about 1 million to 8 million, prepared by a known method, are usually suitably used.

In the present invention, a fired powder of a substance belonging to silicic acid or silicate minerals is used as a carrier for the acrylamide polymer.

Although there are many types of carriers that can be used, calcined powders such as diatomaceous earth, kaolin, bentonite, and perlite are particularly suitable.

General (Powder made by calcining silicic acid or silicate minerals,
Compared to unfired products, the ability to adsorb acrylamide polymers is significantly lower.

Therefore, it is easier to elute the polymer from the granules in which the acrylamide-based polymer is supported than in the case of unfired granules, and the used polymer can be utilized for soil improvement.

In the present invention, in order to prevent performance deterioration during storage of the granules mainly composed of the acrylamide polymer and carrier, a series of additives such as urea, guanylurea, guanidine, cyanamide, dicyandiamide, and amidinothiourea are added to the granules. Contains at least one nitrogen compound.

Although the mechanism of action of these nitrogen compounds is not clear, all of them except cyanamide have the general formula H2N-C-NH- group (where X represents O, S, or 1 NH). This is presumed to be due to the unique action of cyanamide.

The present inventors have been conducting research on adding various fast-release and slow-release fertilizers to soil improvement granules made of acrylamide-based polymers and carriers in order to make them effective as fertilizers. In the course of research, we discovered that when granules contain nitrogen compounds such as those mentioned above, the performance hardly deteriorates during storage, no matter how the residual water content of the granules changes. This invention has been made.

The amount of these nitrogen compounds to be used may vary depending on the type and amount of the acrylamide polymer used, but is usually a small amount, such as the sodium salt of the acrylamide-acrylic acid copolymer mentioned above. % by weight, in the case of granules consisting of 95% by weight of calcined diatomaceous earth, 0% in the granules
．． Sufficient effects can be obtained by containing 1 to 5% by weight (based on completely dry matter).

In this case, it makes no difference even if the nitrogen compound is contained in an amount of 5% by weight or more, and it is preferable to use a large amount in order to give the granules sufficient fertilizing effect. Among the nitrogen compounds used in the present invention, Dicyandiamide, guanidine, guanylurea, amidinothiourea, and the like are also useful as slow-release nitrogen fertilizers.

Note that since guanylurea and guanidine are difficult to handle alone due to their deliquescent properties and strong basicity, salts such as phosphates, sulfates, and nitrates, which are industrially available and easy to handle, are actually used.

Particularly when phosphate is used, it is further advantageous because phosphate fertilizer can also be supplied to the soil.

To manufacture granules, add and mix appropriate water to each of the above ingredients,
This is achieved by granulating and then drying.

Although the mixing ratio of the acrylamide polymer and the mallet can be varied over a wide range, it is usually in the range of polymer: mallet = 5:95 to 50:50 (weight ratio).

Various methods can be used to mix each component, but
Usually polymer aqueous solution (or powdered polymer raw water) and d
A suitable method is to simultaneously charge and mix the nitrogen compound and the nitrogen compound in a mixer G such as a Nigu.

Usually, commercially available acrylamide polymer aqueous solutions have high viscosity even when the polymer concentration is quite low.
Since it is difficult to mix it with other components if it is left as is, in such a case, it should be diluted by adding water as appropriate.

In addition, in order to prevent the deterioration of the polymer, it is desirable to add a small amount of alkaline substance during mixing (for example, thorium carbonate, borax, helium phosphate, etc.), and add 100 ml of water to about 1 g of product granules. Sometimes the pH of the liquid is 7.
It is preferable to use an amount that shows a value of 9 to 9.

After mixing, the mixture is granulated to an appropriate size.

There are various methods for granulation, but for example, continuous granulation using a screw extruder is preferred because of its high productivity.

Usually, the particle size of granules is about 0.1 to 57n111, especially 0.1 to 57n111.
1-17n71 (It is better to rub.

The obtained granules are then suitably dried to obtain the desired soil conditioner granules.

Note that, in order to prevent thermal deterioration of the polymer used, it is desirable that the drying be performed at as low a temperature as possible, for example, at a temperature of 80° C. or lower.

The improvement of soil with the granules produced according to the method of the present invention is the same as that of conventionally known soil conditioner granules, and the water-soluble polymer is usually 0.01 to 0.
It is used in an amount of about 1% by weight.

As a result, soil with a single grain structure can be transformed into a water-resistant and stable soil structure in a short period of time by surface application alone.

Next, a typical example of the present invention will be explained from Example 1.

In addition, in each example, all parts or percentages refer to weight.

Example 1 7 parts of sodium salt powder of acrylamide-acrylic acid copolymer [acrylamide:acrylic acid=85:15 (weight ratio), average molecular weight about 3 million], 0.
4 parts of amidinothiourea, 5 parts of calcined diatoms, ±90 parts of calcined diatoms, and 50 parts of water were charged into a Nigu and mixed thoroughly, using a horizontal screw set extrusion machine with a diameter of 2 inches and a screen hole diameter of 1 at the discharge part. It was granulated.

Then, the obtained granules were dried at a temperature of 80°C, and the residual moisture content was 8.3%, 5.3%, 36%, 2.1%, respectively.
0.7%, each sample was produced.

After each sample was sealed and stored for one week and three months,
Table 2 shows the results of measuring the "wet disintegration rate,""polymer dissolution rate," and "sedimentation half-life of the F-polymer kaolin mixture."

The "wet disintegration rate" and "polymer elution rate" of each sample were measured according to the methods described above.

In addition, "the sedimentation half-life 1 of a polymer kaolin mixture means that the sample granules are mixed with 100 ml of pure water and the polymer concentration is 0.
After soaking in an amount such that the concentration is 1% by weight and shaking for 2 hours,
The suspension was treated with a centrifuge, and 2 ml of the obtained filtrate (polymer aqueous solution) was mixed with kaolin powder (5 g) to 100 g of the water suspension.
In addition to the sedimentation tube with an inner diameter of 22 mm containing m1, it was inverted 10 times and left to stand, and the kaolin flocculation-sedimentation interface was 507Il.
This is the time it takes to reach l.

The shorter this time, the better the cohesiveness of the polymer to the kaolin particles, and the greater the soil particle aggregation effect.

As is clear from Table 2, even if the residual moisture content of the granules is varied, there is very little deterioration in the performance of the granules during storage.

Comparative Example 1 All the same as Example 1 except that acydinothiourea was not used.
．． According to Method G, soil conditioner granules having various residual moisture contents were prepared and tested in the same manner as in Example 1.

As a result, the performance deterioration of each granule during storage was almost the same as in the case of Table 1 described above.

Example 2. ~4゜Example 1. Using urea (Example 2), cyanamide (Example 3), and dicyandiamide (Example 4) instead of amidinothiourea in Example 1. (Thus, soil conditioner granules with various residual moisture contents were produced in a similar manner as described above.

Tables 3 to 5 show the results of the same tests as in Example 1 for each granule.

As is clear from Tables 3 to 5, when urea, cyanamide, or dicyandiamide was used instead of amidinothiourea, almost the same good results as when using amidinothiourea were obtained.

Example 5, General Q Granules containing this acrylamide-based polymer are drying (this performance decreases when the drying time is increased, but the performance of the granules containing the nitrogen compound used in the present invention is improved even if the drying time is extended). There is little decline.

An example is shown below.

Example 1. 7 parts of acrylamide polymer similar to that used in , 0.4 part of sodium carbonate, 90 parts of calcined diatomaceous earth,
50 parts of water, 1 part of each of cyanamide, dicyandiamide, guanidine phosphate, urea, guanylurea phosphate, and amidinothiourea were charged into Nigu, and each of them was prepared in the same manner as in Example 1゜. It was granulated according to the following.

Each of the obtained granules was then dried at a temperature of 80° C. until almost no residual moisture was present.

(About 4 hours) For each dried granule, the "wet disintegration rate", "polymer elution rate", and "sedimentation half-life of the polymer kaolin mixture" were measured before and after drying. The results are shown in Table 6.

Claims (1)

[Claims] 1 (1) Acrylamide polymer and (2) At least one calcined powder selected from silicic acid and silicate minerals. A soil characterized by containing in granules at least one compound selected from the group consisting of phosphate, sulfate or nitrate of guanidine, phosphate, sulfate or nitrate of guanidine, cyanamide, dicyandiamide and amidinothiourea. Method of manufacturing improver.