JPH0219083B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carrier for agricultural chemicals suitable for producing agricultural chemicals in the form of powders, granules, wettable powders, etc. Pesticides may be manufactured in the form of powders, granules, wettable powders, etc. depending on the properties of the pesticide raw material or the purpose of use. That is, various forms of agricultural chemicals are generally produced by mixing agricultural chemical raw materials, agricultural chemical carriers, diluents, and other additives. For example, one of the methods for producing powder
One method is to mix the agricultural chemical raw material and the agricultural chemical carrier in advance, adsorb the agricultural chemical raw material to the agricultural chemical carrier, and then crush the mixture.Additionally, mix talc, clay, etc. as a diluent, and then crush again. . In such a case,
Agricultural chemical carriers are particularly required to have a high rate of adsorption of agricultural chemical raw materials and properties such that the agricultural chemical raw materials do not leach out during mixing or pulverization after adsorption of the agricultural chemical raw materials. If the rate at which the agricultural chemical carrier adsorbs the agricultural chemical raw material is slow, mixing with the agricultural chemical raw material takes a long time, resulting in a decrease in production efficiency. In addition, if the agricultural chemical raw material is leached from the agricultural chemical carrier during mixing or crushing after adsorption, the carrier, diluent, etc. will adhere to equipment such as mixers or crushers, which will only lead to loss of these raw materials. There are handling problems, such as the possibility of clogging the piping in the equipment. On the other hand, oil absorption has traditionally been used as a criterion for determining the superiority of carriers for agricultural chemicals, and those with higher oil absorption have been considered to be superior as carriers for agricultural chemicals. Inorganic compounds with a large oil absorption capacity, such as powdered hydrated silicic acid and diatomaceous earth, are generally used as carriers for agricultural chemicals. Particularly recently, powdered hydrated silicic acid has attracted attention as a carrier for agricultural chemicals because of its large oil absorption compared to other inorganic compounds. however,
There are many types of powdered hydrated silicic acid depending on raw materials and manufacturing methods, and even powdered hydrated silicic acid with a high oil absorption does not necessarily satisfy the above-mentioned properties as a carrier for agricultural chemicals. That is, the properties of powdered hydrated silicic acid required for a carrier for agricultural chemicals cannot be judged simply by the amount of oil absorption, and there are no clear criteria for judgment. The applicant of the present application believes that there are factors other than oil absorption that affect the properties required as a carrier for agricultural chemicals, and that there are factors that affect the properties required as a carrier for agricultural chemicals, and that the pore size distribution, which has not been a problem in the past, has been discussed above in the case of powdered hydrated silicic acid. We have already suggested that the properties are significantly affected. As a result of further research, the present inventor found that by using powdered hydrated silicic acid having a specific amount of pores with a specific diameter, all the properties required as a carrier for agricultural chemicals can be satisfied. The present invention has now been completed. That is, the present invention has a pore radius of 75 Å to 75 Å in the pore size distribution.
The volume occupied by pores with a diameter of 150 Å is 0.6 cc/g or more, and the volume occupied by pores with a pore radius of 75 Å to 100 Å is 45% of the volume occupied by pores with a pore radius of 75 Å to 150 Å.
This is an agricultural chemical carrier made of powdered hydrated silicic acid, which accounts for the above. The pore size distribution and pore radius referred to in the present invention are those measured by a mercury porosimeter method and calculated using the following formula. r (Å) = 7.5×10 ⁴ /P (Kg/cm ² ) (where r is the pore radius and P is the pressure) For the calculation method of the above pore distribution and pore radius, see, for example, powder engineering research. Edited by Japan Powder Industry Association,
“Illustrated Guide to Powder Physical Properties” published by Industrial Technology Center Co., Ltd.
It is sufficient to follow the explanation on pages 116 to 117 (published on May 1, 1975). As mentioned above, various types of powdered hydrated silicic acid can be obtained depending on the types of raw materials, manufacturing methods, etc. Furthermore, the oil absorption amount of the powdered hydrated silicic acid can be increased as necessary. However, even if powdered hydrated silicic acid has a large oil absorption capacity, its properties as a carrier for agricultural chemicals are rarely satisfied as described above. In other words, the total oil absorption of the agricultural chemical raw material is determined by the amount of oil absorbed by the powdered hydrated silicic acid, but the aforementioned handling, the oil absorption rate of the agricultural chemical raw material, the ability to retain the agricultural chemical raw material during crushing, etc. are determined by the oil absorption. It is not a factor that depends on the size of the amount. As a result of various statistical experiments, the present inventor has determined that the handling, oil absorption rate, and ability to retain pesticide ingredients during crushing are based on the volume occupied by pores of 150 Å or less in the pore size distribution of powdered hydrated silicic acid. It was confirmed that it is determined by The properties of the powdered hydrated silicic acid required as a carrier for agricultural chemicals are the pore size distribution of the powdered hydrated silicic acid, particularly the volume occupied by pores with a pore radius of 75 Å to 150 Å, and the volume occupied by pores with a pore radius of 75 Å to 100 Å. The phenomenon that is influenced by the ratio of the volume occupied by the pores to the volume occupied by the pores has been clarified for the first time by the present invention. Of course, the absolute requirements for a carrier for agricultural chemicals are that, as mentioned above, the amount of adsorption of the active ingredient of the agricultural chemical is large and the rate of oil absorption of the active ingredient of the agricultural chemical is fast. In this sense, those with small oil absorption cannot be used, and in general, the volume occupied by pores with a pore radius of 10,000 Å or less in the pore size distribution is 2.5 cc/g or more, preferably 2.7
It is preferable that it is cc/g or more. In addition, in order to increase the rate of adsorption of agricultural chemical ingredients onto the carrier, it is necessary that the volume occupied by pores with a radius of 75 Å to 150 Å in the pore size distribution be 0.6 cc/g or more.
In the above pore size distribution, the volume occupied by pores with a pore radius of 75 Å to 150 Å is preferably as large as possible; for example, 0.7 cc/g or more, more preferably 0.8 cc/g.
It is preferable to choose one with a value of 100 g or more. However, it is industrially difficult to produce a material in which the volume occupied by pores in the pore radius range of 75 Å to 150 Å is extremely large. This is probably the upper limit that can be obtained. On the other hand, in the pore size distribution, for pores with a pore radius of less than 75 Å, the volume occupied by pores with a pore radius of 75 Å to 150 Å is 0.6 cc/
If the active ingredient is more than 75 Å, the adsorption of commonly used agricultural chemical ingredients is surprisingly low.According to the confirmation of the present inventor, the active ingredient of agricultural chemicals that are adsorbed to pores with a pore radius of less than 75 Å are The volume occupied by pores is less than 25%, and at most 40%. Therefore, the pore radius is 75 Å~
The pore radius compared to the volume occupied by the pore between 150 Å
It can be said that the volume occupied by pores of less than 75 Å has little effect on the properties of agricultural chemical carriers. The biggest feature of the agricultural chemical carrier of the present invention is that the volume occupied by pores with a pore radius of 75 Å to 100 Å in the pore size distribution accounts for 45% or more of the volume occupied by pores with a pore radius of 75 Å to 150 Å. Hydrous silicic acid in which the volume occupied by pores with a pore radius of 75 Å to 150 Å in the pore size distribution is 0.6 cc/g or more has an extremely high oil absorption rate for agricultural chemical raw materials. However, carriers adsorbed with agricultural chemical ingredients are generally pulverized, and if the agricultural chemical ingredients are leached during the pulverization process, this will cause a decisive defect in handling as described above. Moreover, as in recent years, attempts have been made to increase the amount of agricultural chemical ingredients used in agricultural chemical carriers, the more the defects become more serious. In this sense, the force with which the agricultural chemical ingredient is held in the carrier during crushing is a major factor as it can increase the amount of agricultural chemical used per ingredient. However, the increase in the amount of agricultural chemicals used and the ability to retain agricultural chemical ingredients during crushing are due to the volume occupied by pores with a pore radius of 75 Å to 150 Å in the pore size distribution, and the volume occupied by pores with a pore radius of 75 Å to 100 Å in this volume. It is affected by the proportion of volume occupied by pores. This finding is a completely surprising phenomenon, but as is clear from the Examples and Comparative Examples described later, it is no exaggeration to say that the above relationship 100% determines the properties of agricultural chemical carriers. More than 45% of the volume occupied by pores with a pore radius of 75 Å to 150 Å in the pore distribution is 75 Å to 100 Å.
If the volume is occupied by the pores between the grains, not only can the amount of the agricultural chemical active ingredient described above be increased, but also the ability to retain the agricultural chemical active ingredient during pulverization will be significantly improved. However, if the ratio is less than 45%, the holding power of the active ingredient during pulverization is low, and it is impossible to increase the amount of active ingredient used. Of course, the above-mentioned ability to retain the active ingredient during pulverization is greatly affected by the amount of active ingredient used, so the required ability to retain the active ingredient during pulverization is determined and the amount of pesticide used that corresponds to the retention power is determined. is common. In the pore size distribution of powdered hydrated silicic acid as in the present invention, the volume occupied by pores with a pore radius of 75 Å to 150 Å is
Powdered hydrated silicic acid having a particle size of 0.6 cc/g or more and in which the volume occupied by pores with a pore radius of 75 Å to 100 Å accounts for 45% or more of the volume occupied by pores with a pore radius of 75 Å to 150 Å is conventionally known. It is almost impossible to find powdered hydrated silicic acid, such as commercially available hydrated silicic acid. For example, typical commercially available hydrated silicic acid will be shown in the comparative example below, but in general, it is 0.11 to 0.45 cc/g even if only the volume occupied by pores of 150 Å or less in the pore size distribution is considered. Most of them are. Therefore, it can be said that in the powdered hydrated silicic acid of the agricultural chemical carrier of the present invention, the volume occupied by pores with a pore radius of 75 Å to 150 Å in the pore size distribution is significantly larger than that of commercially available hydrated silicic acid. Furthermore, as described above, the volume occupied by pores with a radius of 75 Å to 100 Å in the above volume is extremely large. The particle diameter of the powdered hydrated silicic acid in the present invention is not particularly limited, and may be determined depending on the intended usage form of the agricultural chemical. Generally, the primary particle size is 10~
Those in the range of 50 mμ are preferably used. The method for producing the powdered hydrated silicic acid having the properties of the present invention is not particularly limited, and any production method may be used as needed as long as it can impart the properties. The most typical manufacturing method is as follows. That is, when a raw material such as an alkali silicate is decomposed with a mineral acid such as sulfuric acid, the mineral acid is added in two parts to an aqueous solution of an alkali silicate. In this case, the initial addition amount and addition time of the mineral acid is within the range of the pore radius 75 to 150 Å.
The volume occupied by the pores and the pore radius in the volume of 75 Å
~100 Å has a significant effect on the proportion of volume occupied by pores. In general, 37% for the total amount of mineral acid added.
Preferably ~45% is added initially as quickly as possible, eg within 10 minutes. In addition, the temperature when adding a mineral acid to the alkali silicate aqueous solution to decompose the alkali silicate is preferably high, and is generally 85°C.
Temperatures of ~95°C are preferred. Of course, these conditions need to be determined in advance since they vary depending on the type of raw materials, reaction equipment, etc. As is clear from the Examples and Comparative Examples described below, the carrier for agricultural chemicals of the present invention has a fast adsorption rate of the agricultural chemical raw material and a large retention power for the agricultural chemical raw material, so that it is easy to mix and crush the agricultural chemical raw material after adsorbing the agricultural chemical raw material. It also has excellent workability with no leaching of agricultural chemical ingredients. Therefore, the use efficiency of agricultural chemical ingredients is good, and the stability during storage is also excellent, so the contribution of the present invention is immeasurable. EXAMPLES In order to explain the present invention in more detail, Examples and Comparative Examples will be given below, but the present invention is not limited to these Examples. In addition, the pore size distribution, pore volume, oil absorption rate, and agricultural chemical substance retention ability during crushing of the powdered hydrated silicic acid in Examples and Comparative Examples were measured by the following methods. Measurement method 1 Pore size distribution The pore size distribution and its pore volume were measured using a mercury porosimeter model 1520 (Dilatometer type) manufactured by CARLOERBA.
SM3, Capillary: 3mmφ0.07065
cm ² }. In addition, the pore volume has a pore radius of 50 to 150 Å, 75 to 100 Å, 75 to 150 Å, and 50 to 10000 Å.
Expressed as volume in Å. 2 Oil Absorption Rate Figures 1, 2, and 3 are schematic diagrams showing a method for measuring oil absorption rate. Take the hydrated silicic acid sample in the 32 mesh fluid 1 shown in Fig. 1, and while rubbing it with a brush, apply the sample to a diameter of 70 m/m and a height of 16 m/m as shown in Fig. 1.
Place sample 3 in container 2 with an open top up to its angle of repose. Next, as shown in Figure 2, weigh the diameter of 120mm.
Gently place the watch glass 4 weighing 51.8 g on it, and pull up the watch glass 4 after 30 seconds. Next, as shown in Figure 3, 0.3 ml of boiled oil 5 was dropped onto the compressed sample surface 3, and the time required from the time the boiled oil and the sample came into contact until all the boiled oil was absorbed into the sample was measured. and the oil absorption rate. Note that the measurements were performed indoors at room temperature (20°C). 3. Pesticide drug substance retention test during pulverization Weigh 5 g of the hydrated silicic acid sample using a flat balance and place it in an evaporation dish. Add 12.5ml of boiled oil to this,
Mix well and absorb. The adsorbed sample is ground using a Philips coffee mill (HR2170). As the grinding continues, the boiling oil gradually leaches out, and eventually the ground material becomes paste-like and the coffee mill spins idly. The time from the start of the grinding to idle rotation was measured and determined as the agricultural chemical drug substance retention force (hereinafter sometimes simply abbreviated as holding force) during the grinding. Example 1 Commercially available sodium silicate (SiO ₂ /Na ₂ O molar ratio =
_3.03SiO2 26.4%) ^7.6m3 _{and Na2SO4} ( _Na2O1.35 %)
Pour 37 m ³ and 0.4 m ³ of water into a 60 m ³ internally heated reaction tank with stirring blades and add 1.95 sulfuric acid (22 g/100 ml) while stirring.
m ³ is added in about 10 minutes to perform the first stage of acid addition.
After the addition is complete, blow in steam while stirring.20
Raise the temperature to 95℃ in minutes. After raising the temperature, ripening is performed at the same temperature for 7 minutes. After that, neutralization is restarted, and 2.68 m ³ of the above-mentioned sulfuric acid is added over 90 minutes to neutralize the remaining alkali, and the reaction is completed by bringing the pH of the solution within the range of 5.5 to 6.5. . This solution is then added to the product PH of the hydrated silicic acid after drying.
Adjust the pH to 4.4 so that the pH is 5.5 to 6.5. This solution is washed with water using a filter press to obtain a filter cake containing hydrated silicic acid. This filter cake is slurried again using a dispersion device to create a highly concentrated silicic acid suspension with hot air at a temperature of 400°C.
Spray drying is carried out at a rotating disk speed of 6000 rpm to obtain fine granular hydrated silicic acid. This hydrated silicic acid is crushed,
After degassing, the product was obtained. Using this product, pore diameter volume, adsorption retention power, and oil absorption rate were measured. The results are shown in Table 1. Example 2 In Example 1, the amount of sulfuric acid added in the first stage was
Hydrated silicic acid was obtained in the same manner as in Example 1 except that the amount of sulfuric acid added was changed to 1.75 m ³ and the remaining amount of sulfuric acid was changed to 2.95 m ³ . The same tests and measurements as in Example 1 were carried out using this hydrated silicic acid. The results are shown in Table 1. Example 3 Using the same apparatus as in Example 1, powdered hydrated silicic acid was obtained in the same manner as in Example 2, except that the reaction temperature was changed to 85°C. The same tests and measurements as in Example 1 were also carried out using this hydrated silicic acid. The results are shown in Table 1. Comparative Example 1 Commercially available sodium silicate (SiO ₂ /Na ₂ O molar ratio =
3.05, _SiO2 : 28.4%) _282ml and _Na2SO4 ( _Na2O1.78
%) 1124ml and 594ml of water into 3 glass containers,
While stirring, add 68.1ml of sulfuric acid (22g/100ml) to approx.
The first stage of acid addition is carried out by adding the acid in minutes. After pouring, external heating is performed using a mantle heater for approximately 20 minutes.
Raise the temperature in minutes to 95℃. After raising the temperature, ripening is performed at the same temperature for 5 minutes. Thereafter, neutralization is restarted, and 126 ml of the sulfuric acid is added over a period of about 100 minutes to neutralize the remaining alkali, and the reaction is completed when the pH of the solution falls within the range of 3.5 to 4.5. Next, this solution was filtered through a Buchner funnel, washed with water, dried in a microwave oven, and then ground in a coffee mill manufactured by Philips to obtain powdered hydrated silicic acid. Example 1 Using this hydrated silicic acid
The same tests and measurements were carried out. The results are shown in Table 1. Comparative Example 2 Commercially available sodium silicate (SiO ₂ /Na ₂ O molar ratio = 3.05,
_SiO2 : 28.4%) _282ml and _Na2SO4 ( _Na2O1.78 %)
1,124 ml and 594 ml of water were placed in a glass container, and 77.6 ml of sulfuric acid (22 g/100 ml) was added over about 3 minutes while stirring to perform the first acid addition. After pouring, heat externally using a mantle heater and raise the temperature to 70℃ in about 20 minutes. After raising the temperature, ripening is performed at the same temperature for 5 minutes. Thereafter, neutralization is restarted, and 116.5 ml of the above-mentioned sulfuric acid is added over about 100 minutes to neutralize the remaining alkali, and the reaction is completed when the pH of the solution falls within the range of 3.5 to 4.5. Next, put 400 ml of this reaction solution into an autoclave with an internal volume of 500 ml. Stir the reaction solution in the autoclave with a magnetic stirrer for about 30 minutes.
The pressure was increased to 3 kg/cm ² G in 1 minute, and stirring was continued at the same pressure for 2 hours. Thereafter, the pressure is reduced to atmospheric pressure by natural slow cooling. Thereafter, the autoclaved liquid was filtered through a Buchner funnel, washed with water, dried in a microwave oven (home use), and then ground in a Philips coffee mill to obtain powdered hydrated silicic acid. The same tests and measurements as in Example 1 were carried out using this hydrated silicic acid. The results are shown in Table 1. Example 4 Using the powdered hydrated silicic acid obtained in Example 1, the retention power of agricultural chemical raw materials was measured. The measurement method is the same as in 3 above, except that in 3 above "Pesticide drug substance retention test during pulverization", the boiled oil and the amount of boiled oil used were the pesticide drug substances listed below and the amounts used as shown in Table 2. The same procedure was carried out. The results were as shown in Table 2. Type of agricultural chemical used

【table】

[Table] Comparative Example 3 Regarding the commercially available powdered hydrated silicic acid shown in Table 3, the apparent specific gravity, oil absorption, volume of 50 to 150 Å pores, and oil absorption rate were measured. The results are shown in Table 3.

【table】 [Brief explanation of drawings]

FIGS. 1, 2, and 3 are schematic diagrams showing a method for measuring oil absorption rate, respectively. In the figure, 1 is a sieve, 2 is a container, 3 is a sample, 4 is a watch glass, and 5 is boiled oil.

Claims (1)

[Claims] 1. The volume occupied by pores with a pore radius of 75 Å to 150 Å in the pore size distribution is 0.6 cc/g or more, and the volume occupied by pores with a pore radius of 75 Å to 100 Å is the pore radius.
A carrier for agricultural chemicals made of powdered hydrated silicic acid that occupies 45% or more of the volume occupied by pores between 75 Å and 150 Å. 2. The agricultural chemical carrier according to claim 1, wherein the volume occupied by pores with a pore radius of 10,000 Å or less in the pore size distribution is 2.7 cc/g or more. 3. The agricultural chemical carrier according to claim 1, wherein the volume occupied by pores with a pore radius of 75 Å to 150 Å is 0.7 cc/g or more.