Pesticide formulations blog:
of: Hu Zhibiao, Wang Yongqiang, has wide Peng, Hong Xin Lin *, Gao-Yong Zhang
Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072
1. Dispersants products Ordinary Design < br> In order to make room for more effective stabilization, the polymer coated particles must be done: (1) to strong adsorption to the particle surface; (2) polymer particles to cover the entire surface; (3) was adsorbed polymer must be spread to the media, enough to form stable layer thickness of the space.
so the structural design of polymer dispersions for the two main components: A group is anchored on the particle surface has a strong adsorption ; B is to be solvent, with the base resin has good compatibility, can form a stable polymer chain space.
anchored surface groups on the adsorption of particles, mostly through hydrogen bonding, ionic The combination of keys, a few cases there are covalent bonds. commonly used anchor groups are tertiary amine, quaternary ammonium, carboxyl, carboxylic acid, sulfonic acid, phosphate, imidazole, etc..
2. polymer dispersed agent (super-dispersant) design developed in the past 20 years
polymer dispersant, often called super-dispersant, dispersant has become mainstream. it is different from surface active agent, a dispersing agent molecule contains more than one anchor group, and these anchor groups together than scattered throughout the polymer chain in the dispersion of particles is much better.
group under the anchor (A) and steric group ( B) the order can be divided into the following four types.
(1)
(2)
(3)
(4)
in four types of dispersing agents, (1) and (4), the most common type in both. BYK company's products, Disperbyk-2000 and Disperbyk-2001 belonging to AB-type block copolymer dispersant; Disperbyk-140, Disperbyk-160, Disperbyk-190, Disperbyk- 191, Disperbyk-182, Disperbyk-184 belongs to comb polymer dispersant. (2) synthesis of complex, distributed or less effective than type AB. (3) random copolymer, the introduction of the appropriate anchor groups, but also to achieve good dispersion, but compared with other types, dispersion to badly.
3. acrylate amphiphilic comb polymer dispersant
according to these principles, we designed the acrylate amphiphilic comb polymer dispersant structure shown in Figure 14:
Figure 14 comb polymer dispersant in which the basic structural design
, R can be the main chain with anchoring groups the functional monomer, such as glycidyl methacrylate (GMA), dimethyl amino ethyl methacrylate, etc., may also be common acrylic monomers. for the dispersed pigment or filler surface physical and chemical properties can make different modifications. through the carboxylic acid side chain and to provide the necessary in the water-soluble.
4. Hyperdispersant Fipronil 5% of microemulsion screened acrylic
class of amphiphilic comb polymer dispersant number WHU-1, and UNIQEMA company ATLOX 4913 were compared. microemulsion basic formula is: Fipronil 5% of the original drug; solvent content of 20% A; non-ionic emulsifier B content of 12%; comb polymer dispersant WHU-1 content of 6%; water content was 57%.
literature verifiable Fipronil formulations are: 5% EC, 5% SC, 80 % of dispersed particles etc., There is no micro-emulsion of 5% coverage. The fifth laboratory research projects in the national commitment to 1 5% of the successful development of microemulsion formulation of fipronil through the frozen (-15 ℃) and thermal energy storage (54 ℃) 14 天 experiment, and showed excellent stability dilution (diluted 1000 times, 4 hours, no pesticides crystal precipitation.) temperature range of its transparency: -5 ℃ -60 ℃, in line with national standards, but its transparent use of ATLOX4913 the preparation temperature does not exceed the maximum temperature range of 53 ℃, do not meet national standards.
dilution stability Comparative experimental results (visual observation) the following table.
dilution stability results in Table 4
category
dispersants and emulsifiers B ratio in the preparation
0:18
6 : 12 (ATLOX 4913)
6:12 (WHU-1)
dilution stability at room temperature
(1000 times)
8 minutes to the microscopic observation of crystal precipitation
24 minutes observed precipitation of tiny crystals
system 4 and a half hours of standing side has tiny crystals precipitated
cold thermal energy storage stability of the preparation results shown below. have passed 14 days frozen (-15 ℃) and heat storage (54 ℃) experiments, frozen samples stored at room temperature after 6 minutes dissolution of restitution, and geothermal reservoir samples become darker in color due to pesticide partially decomposed at this temperature the reason.
cold thermal energy storage in Figure 15 the experimental results, After 14 days left for the samples stored frozen after the experiment just remove the heat when the state right is the room temperature for 6 hours after the state. picture on the left of the heat storage test samples, the right to test samples frozen.
using polarized light microscopy microemulsion system in the Central Plains after 1000 times dilution of drug crystal precipitates. The following two graphs are ATLOX 4913 and the WHU-1 system, the figure shows, WHU-1 can inhibit the active ingredient in the crystal system precipitated the problem.
Figure 16 ATLOX 4913 1000 times diluted microemulsion system at different times after standing POM images, from left to right: 15 min, 30min, 120min.
Figure 17 WHU-1 micro- 1000 times diluted milk system, standing at different times after the POM images, from left to right: 30min, 120min, 240min.
Table 55% Fipronil microemulsion cost accounting and economic benefits. < br> component
price (yuan / kg)
preparation content (wt.%)
Regent original drug
1000
5
solvent
65
20
non-ionic emulsifier
13
12
WHU-1
60
6
water 57
preparations according to the price and the percentage of each component content, calculated by the product costs about 70 yuan / kg. At present, widely used on the market Fipronil 5% SC 10 ml is generally packed, which sells for 2.3-2.5 million, equivalent to estimate the price per kg into not less than 230. So Fipronil 5% microemulsion with broad margins.
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