JP2014015443A - Spreader for suppressing dispersion of pesticide application liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-concentration sodium polyacrylate aqueous solution that gives a pesticide application liquid dispersion suppression properties and spreading properties, and facilitates its use simultaneously.SOLUTION: By adding, to a sodium polyacrylate aqueous solution, a water soluble solvent including polyoxyalkylene alkyl ether and dimethyl sulfoxide, a spreader that facilitates its use and has the function of suppressing pesticide dispersion is prepared.

Description

  The present invention relates to a technique for reducing spraying of a pesticide spray liquid and effectively spraying a pesticide.

When diluting and spraying pesticides with water, controlling the spraying of pesticides by suppressing the formation of fine water droplets that occur during spraying reduces the risk of remaining on non-target crops, as well as pesticide users. Can reduce the health damage. It is also an important technology for controlling the impact on nearby residents (health hazard, nasty smell, pesticide adhesion to laundry, etc.). At present, nozzles that increase the water droplet diameter and suppress the spraying of the agricultural chemical spray liquid have been put into practical use.
Also known is a technology that suppresses scattering by adding sodium polyacrylate, which is a water-soluble polymer compound, to the pesticide spray solution to increase the viscosity. Sodium polyacrylate 2% solution (trade name Aron A Toagosei Co., Ltd.) Company product (hereinafter referred to as “Aron A”) was registered as the only pesticide and was used only for aerial spraying in agricultural fields, but its registration expired in 2011.

Aron A agent is diluted 50 to 200 times and sprayed with pesticides, but many of the pesticides are often used in the dilution range of several hundreds to thousands of times. Required quantity. The viscosity of sodium polyacrylate increases as the molecular weight increases and the concentration increases. However, when a high-concentration product is prepared in consideration of economy, the solution loses fluidity and becomes difficult to handle. In addition, sodium polyacrylate does not have a spreading action that stabilizes the effect of pesticides. As a method for reducing the viscosity of a sodium polyacrylate preparation and facilitating its use, a method of mixing a water-soluble solvent containing a surfactant has been proposed.
Japanese Patent Application No. 2008-159742

  Sodium polyacrylate, which is an active ingredient that suppresses the scattering of agricultural chemical spray liquids, is used as a coagulating and precipitating agent for suspended matters in water, as a moisturizing agent for cosmetics, and as a food additive. In addition, polyoxyalkylene alkyl ethers that impart spreadability of agricultural chemical spray liquids are typical nonionic surfactants. They are not only surfactants for agricultural drugs, but also various detergents that are closely related to daily life, such as kitchen detergents. It is used for various scenes.

  In addition, a method of adding alcohols or glycols has been put to practical use as a method for reducing the viscosity of a sodium polyacrylate aqueous solution and preparing an easy-to-use product. Ethanol, isopropanol, and propylene glycol, which are water-soluble solvents that reduce the viscosity of a product and provide convenience during use, are used as beverages or food additives. In addition, glycols such as dipropylene glycol, tripropylene glycol, and polypropylene glycol, and dimethyl sulfoxide are also added to agricultural chemicals, pharmaceuticals, cosmetics, and the like as solvents with high safety and are used on a daily basis.

  In pursuit of food safety and security, the spraying of pesticide spray on non-target crops will have a significant impact. In particular, the introduction of a positive list system has taken prudent responses to pesticide residues, and if agricultural chemicals exceeding the standard value are detected, they are disposed of and disposed of. In addition, internationally, there are concerns about damage to pesticide workers and residents in the vicinity as OECD issues are raised. As a countermeasure against scattering of agricultural chemicals in Japan, a method of preparing a solid and heavy preparation such as fine granules, fine granules, granules, etc. with low scattering beforehand and directly spraying it, or a method of spreading a net for preventing scattering around, Alternatively, a method using a scattering suppression nozzle that enlarges water droplet particles is recommended. However, none of these methods are sufficient techniques in view of cost, effectiveness and practicality. On the other hand, the method of diluting and spraying high-concentration pesticides with water is considered to be an indispensable technology because it is simple and less expensive.

  A high-concentration preparation of sodium polyacrylate having a large molecular weight is very difficult to use because it gels, and a low-concentration product must be used at a low dilution factor. On the other hand, in the case of sodium polyacrylate having a small molecular weight, the viscosity is greatly reduced upon dilution, and it must be used at a low dilution ratio. The molecular weight of sodium polyacrylate used so far is about several hundred thousand, the dilution rate is 200 times or less, and the concentration in the diluted solution is 100 ppm or more. The products currently required are highly diluted products capable of exhibiting sufficient scattering suppression ability when sprayed together with agricultural chemicals, while having good workability and a viscosity that can be easily handled.

  On the other hand, the action of reducing fine water droplets and suppressing splashing has a negative result such as reducing the amount of agrochemicals adhering to the target or making the adhesion uneven. It is a well-known fact that the reduction of fine water droplets resulting in inhomogeneity lowers the original effect, particularly in drugs lacking the ability to penetrate and migrate. Therefore, there is a concern that the increase in the viscosity of the spray liquid due to the sodium polyacrylate increases the particle diameter of the water droplets and suppresses the scattering while reducing the effect. Conventionally, spreading agents have been widely used to prevent non-uniform adhesion of agricultural chemical spray liquids, and nonionic surfactants are particularly widely used because of their low surface tension reducing effect.

Means to solve the problem

  Nonionic surfactants used as spreading agents include polyoxyethylene alkylphenyl ether, polyoxyethylene sugar fatty acid ester, polyoxyethylene alkyl ether and the like. Among these, polyoxyethylene alkylphenyl ether is excellent in spreadability but inferior in biodegradability, and tends to be refrained from use due to concern about environmental pollution. The polyoxyethylene sugar fatty acid ester has a problem that the spreadability is slightly inferior although there is little phytotoxicity to crops, and there is much foaming. Some polyoxyethylene alkyl ethers have excellent spreading properties, but many foams. However, among these polyoxyethylene alkyl ethers, those having a branched carbon chain in the alkyl group and those having a polyoxyalkylene alkyl ether copolymer of ethylene and propylene are used in combination with sodium polyacrylate. It was also found that the foaming was suppressed, the defoaming speed was fast, and the convenience during use was excellent. At the same time, it has been found that these nonionic surfactants have the effect of lowering the viscosity of an aqueous sodium polyacrylate solution, similar to water-soluble solvents.

  In general, polyoxyalkylene alkyl ethers are likely to cause phytotoxicity to crops. The spreadability and phytotoxicity vary depending on the number of moles of polyoxyethylene group added in addition to the molecular weight and concentration. In consideration of chemical damage and spreadability, in the case of polyoxyalkylene alkyl ethers having 8 to 16 carbon atoms, the concentration during use is desirably 300 ppm or less, and more desirably 30 ppm to 150 ppm.

  It is already known that the viscosity of a preparation can be reduced by adding a water-soluble solvent such as alcohols and glycols to an aqueous sodium polyacrylate solution. However, when the concentration of these water-soluble solvents is increased to reduce the viscosity, the sodium polyacrylate becomes suspended and may separate and precipitate under low temperature and long-term storage, making resuspension difficult. It was. As a result of examining the solvent that suppresses separation and precipitation, it was found that separation and precipitation can be suppressed by replacing a part of the water-soluble solvent with dimethyl sulfoxide having a large specific gravity.

  The higher the product concentration of sodium polyacrylate, the more economical, but considering the fluidity of the product at the time of use, that is, the convenience of use, 4 weight in the case of sodium polyacrylate having a molecular weight of 200,000 to 400,000 Percent to 6 weight percent is desirable. The concentration of the polyoxyalkylene alkyl ether used in this sodium polyacrylate concentration region is preferably adjusted to 0.5 to 1.5 times the sodium polyacrylate concentration in consideration of phytotoxicity to plants. Although the content of the polyoxyalkylene alkyl ether and the water-soluble solvent varies depending on the content of sodium polyacrylate used, the total amount of the water-soluble solvent containing the surfactant polyoxyalkylene alkyl ether and dimethyl sulfoxide is 20 From weight percent to 30 weight percent.

Effect of the invention

  Provided is a preparation technology of high-concentration sodium polyacrylate that suppresses scattering during spraying of agricultural chemicals and has spreadability of agricultural chemical spray liquid, and at the same time, is easy to use and maintains stable physicochemical properties.

The superiority of this drug will be clarified by test examples below.
In the following table, sodium polyacrylate, surfactant, and solvent are indicated as shown in Table 1 below.

(Test Example 1) Effect of sodium polyacrylate concentration, nonionic surfactant and water-soluble solvent concentration on viscosity and product stability Nonionic surfactant and water-soluble solvent were mixed, and the average molecular weight was mixed 350,000 sodium polyacrylate (trade name Aron A20P Toagosei Co., Ltd.) alone or sodium polyacrylate with an average molecular weight of 200,000 (trade name Aron A20PX Toagosei Co., Ltd.) is added and stirred in distilled water with stirring. Alternatively, an aqueous suspension was prepared. After standing in a 40 ° C. incubator for 3 days and cooling to 20 ° C., 50 g of each solution was slowly put into a 100 ml glass bottle with an inner diameter of 36 mm and a commercial anti-scattering agent Aron A (sodium polyacrylate 2 %) And the relative viscosity were compared with the degree of fluidity.
The viscosity was evaluated as follows.
○ Fluidity equal to or better than Aron A agent △ Fluidity slightly lower than Aron A agent × Clearly lower fluidity than Aron A agent Each preparation was left in a refrigerator at 5 ° C for one month and observed for precipitation separation And evaluated as follows.
○ No precipitation separation △ Slight precipitation separation but homogenization if shaked × Precipitation separation that does not become uniform even if shaken For the above results, the preparations mixed with dimethyl sulfoxide are shown in Table 2-1, Table 2-2, It shows in Table 2-3 and Table 2-4. In addition, preparations not using dimethyl sulfoxide as a control are shown in Tables 2-5 and 2-6.

(Test Example 2) Viscosity and spreadability of diluting solution Test Example 1 had fluidity equal to or better than Aron A agent, and was stored at 5 ° C for one month and no separation was observed. 1 g to 2 g of the preparation that can be suspended was placed in a 1 L plastic container, and tap water (hardness 70 ± 10) at 21 ° C. was added and stirred to prepare a 500-fold diluted solution. The solubility during stirring and dissolution was observed, and the state of foaming after standing for 15 minutes was observed. The diluted solution was measured for viscosity (mPa · s) twice at 60 rpm using a viscometer (Toki Sangyo Co., Ltd., TVB-10 type), and the average value was obtained. Moreover, the diluted adjustment liquid was taken into a beaker, and cabbage leaves cut into about 2 cm × 3 cm were immersed to observe the adhesion state of the solution. For comparison, a commercially available Aron A agent 200-fold diluted solution, a commercially available spreading agent squash (mixed product of 70% sorbitan fatty acid ester and 5.5% polyoxyethylene resin acid ester, Kao Corporation product) 1000-fold diluted solution, and Tap water was used.
The solubility was evaluated as follows.
○ Easily dissolved △ Relatively easily dissolved × Sufficient stirring is required for dissolution The foaming state was evaluated as follows.
○ Foam is present in 1/3 or less of the surface area of the container Δ Foam is present in 1/3 to 2/3 of the surface area of the container × Foam is present in 2/3 or more of the surface area of the container The spreadability was evaluated as follows.
○ The whole surface of the cabbage leaf gets wet. △ The cabbage leaf gets wet in spots. × All water drops fall from the cabbage leaf.

As described above, the NO. 1 to NO. It is difficult to put into practical use 47 that has a relative viscosity that is clearly lower than that of Aron A agent and that causes precipitation separation that is difficult to redisperse at low temperatures. Moreover, what is judged to be usable in Table 2 is 500 times as compared with the viscosity of Aron A agent 200-fold diluted solution (average molecular weight of 350,000 sodium polyacrylate concentration 100 ppm) as shown in Table 3. NO. Becomes the same concentration as the Aron A 200-fold solution. 3, NO. 4, NO. 5, NO. 7, NO. 9, and NO. 32, NO. 36, NO. 39, NO. 43, NO. The viscosity of 46 was clearly reduced. No. 1 shows almost the same viscosity as Aron A 200-fold solution. No. 10 500 times (average molecular weight 350,000 sodium polyacrylate concentration 110 ppm), NO. 14, NO. A 500-fold solution of 17 (average molecular weight 350,000 sodium polyacrylate concentration 120 ppm) showed a slightly higher viscosity than Aron A agent. In addition, NO. 3 is a mixture of sodium polyacrylate having an average molecular weight of 350,000 and sodium polyacrylate having an average molecular weight of 200,000. 19, NO. 22 (average molecular weight 313,000) 500 times (120 ppm) solution also showed almost the same viscosity as Aron A agent 200 times solution. The NO. 10 (average molecular weight 350,000 sodium polyacrylate 5.5%) and NO. 19 (average molecular weight 313,000 sodium polyacrylate 6.0%) has the same content of surfactant and water-soluble solvent, but NO. 19 compared with Aron A agent. The relative viscosity of 19 preparations is NO. Slightly lower than the relative viscosity of the 10-tone product.
As described above, it is clear that the addition of the water-soluble solvent and the nonionic surfactant causes a decrease in the viscosity of the preparation and at the same time a decrease in the viscosity of the diluted solution. At the same time, as shown in Table 2-5 and Table 2-6, when only alcohols and glycols essential for reducing the viscosity of the preparation are used, a 500-fold diluted solution having a viscosity equal to or higher than that of Aron A 200-fold diluted solution is used. It was difficult to obtain a preparation that could be adjusted.

  In addition, as shown in Table 2-1, Table 2-2, and Table 2-3, separation and precipitation of sodium polyacrylate by replacing part of alcohols or glycols that are water-soluble solvents with dimethyl sulfoxide. It became possible to suppress. The water-soluble solvent mixed with dimethyl sulfoxide contains glycols (NO.3, NO.4, NO.5) rather than alcohols (NO.7, NO.8) from the viscosity of the preparation, separation, and tolerance to precipitation. It was excellent. NO. Prepared with only dimethyl sulfoxide. 23 (average molecular weight 275,000) was not able to obtain excellent results in any of the viscosity of the preparation, the precipitate separation, and the viscosity of the diluted solution.

  In addition, as shown in Table 3, when dimethyl sulfoxide was mixed, the solubility of the preparation in water was slightly reduced, but it was determined that it was relatively easily dissolved by stirring and that there was no practical problem.

  In addition, in the existing polyoxyalkylene alkyl ether-based agricultural spreading agent, the lower limit range of use is from 60 ppm to 100 ppm. The spreading property was almost the same as that of 55 ppm oxyethylene resin acid ester. Foaming which was not preferable in use could be suppressed by using a polyoxyethylene secondary alkyl ether having a slightly smaller number of moles of ethylene oxide added.

Claims (3)

  Contains 4 to 6 weight percent of sodium polyacrylate having a molecular weight of 200,000 to 400,000, and is selected from polyoxyalkylene alkyl ethers as surfactants, alcohols and glycols as water-soluble solvents An aqueous solution or suspension for the purpose of suppressing scattering of agricultural chemicals and spreading of agricultural chemicals containing one or more of them and dimethyl sulfoxide.   The purpose of the present invention is to prevent the spread of agricultural chemicals and spread the agricultural chemicals according to claim 1, which contains at least one polyoxyethylene alkyl ether in which the alkylene group of the polyoxyalkylene alkyl ether is ethylene and the alkyl group is a branched alkyl. Aqueous solution or water suspension.   The water-soluble solvent is at least one selected from ethanol, isopropanol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol and dimethyl sulfoxide, and these water-soluble solvent and surfactant. The aqueous solution or water suspension for the purpose of suppressing scattering of agricultural chemicals and spreading of agricultural chemicals according to claim 1, wherein the total amount of polyoxyalkylene alkyl ethers is 20 to 30 weight percent.