Additives and screening for water dispersible granules
WDG auxiliaries and fillers are a comprehensive system. Each material not only plays a role. For example, a good dispersant can disintegrate and wet itself. Starch is a filler and also sticks in some formulations. Knot and disintegration. The following classifications are only from their main performance: Seeking the truth: I have also seen some formulas with a lot of lactose and glucose. I don't know if it is necessary or not. I personally think that the formula of WDG does not need to be so complicated, that is, it needs to be evaluated, some ingredients. Is it necessary to add, if it is missing, then it is complicated and unreasonable. Liangbin9803: The principle of formula should be as simple as possible, which is conducive to the debugging of production and formulation. In addition to the problem, it is difficult to find some products, and some recipes have to be complicated. Huchao: You are right, the simpler the formula, the better, whether it is in the screening, production, processing and procurement! Support your point of view! However, some of the original drugs do require a variety of auxiliary additives and fillers, which is also very good! Yano Auxiliary: The landlord has not been exposed to Croda 550s (white) BB4 CBZ and so on is also a very good dispersant, and the landlord does not involve a wetting agent. Qm8609: The formulation of the two granulation methods is different. Some newcomers have misunderstood this problem. Extrusion granulation may be secondary to boiling or spray granulation in disintegration because there is "stress" in the material during extrusion and it is necessary to overcome this "stress" during disintegration.
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1. Dispersing Wetting Agents <br> This field has been ruled by foreign additives. In the past two or three years, domestically produced additives have been introduced. The foreign aids I contact are more T36, 2700 and D425. The former two are Rodia and Huntsman. The quality is good and stable, but the price is too high. Akzo's D425 is relatively cheaper, but because of It has a large amount of addition in the formula, and the comprehensive cost is also relatively high. Due to its color, it is also very limited in formula. Domestic auxiliaries, there are three more contacts: Guangyuan Yinong, Hanmok and Nanjing Ruoen (add one more: Nanjing Qingyu). The first two are similar, the price is not much lower than the 2700, the quality gap is still relatively large, some formulations are also very similar; Nanjing Ruoen's additives are not used a lot, according to industry friends, yes, and Compared with the 2700, the price is much cheaper and the price is good. It can be completely replaced in some formulas (the Atrazine is more obvious), but the recommended application formula is not many. These three domestic auxiliaries need to work hard on the application formula. Not every pesticide factory technician has time, energy and patience to investigate the auxiliaries and formula dosage forms. This is like the operating system of a computer. The newly developed system has superior performance and is not as good as WINDOWS because it is compatible with the most applications.
2, the binder <br> A good formulation of high-content WDG dosage form does not require a binder, but many formulations have to be used. I usually use glucose and lactose. If the amount is too much, the negative effect on disintegration is too obvious. I have seen that the recommended dosage of a formula is 30%, which is astounding! It has been said that the amount of addition is large, and it can increase the viscosity of the solution after being dissolved in water, which helps to increase the suspension rate. This view has not been systematically verified. Another disadvantage is that excessive addition, some sugars melt during the drying process to form a "sugar film" on the surface of the particles, and disintegration can be imagined. If the slowest dispersion time of all insolubles in the granules is set to A, the dissolution time of the solubles in the granules is B. The disintegration time is the maximum value max{A, B} of the two. If the amount of sugar added is excessive, the disintegration time is the sum of the two: A+B. (The stability of sugar fillers still needs to be solved. Whether it is drying discoloration or storage discoloration, I believe that there will be better fillers in the future! Some new fillers of resin, but the current price is too high, only Europe use!)
3, disintegration agent <br> From the cost considerations, disintegrants are mostly soluble inorganic salts, I commonly used: sodium sulfate, ammonium sulfate, urea and sodium chloride. Sodium sulphate is similar to ammonium sulphate, but it is the one that dissolves faster; urea has good disintegration performance, but it is easy to melt during granulation, making all materials more and more viscous; sodium chloride, relatively comparative Better, disintegration is less than sulfate. (If there is a filler that is directly superfine but very dry, inorganic water-soluble salt, it will save a lot of things, at least the damage rate of the extruded net is low!)
4, help dispersant
The concept of dispersant is present in the formulation of imported auxiliaries. It is considered from the synthesis process of polycarboxylates. A product is relatively concentrated in molecular weight distribution, and it is difficult to target the range of all materials. This auxiliary auxiliaries are To solve this problem, the general imported products have matching dispersing agents. Domestic additives are mostly NN0 and sodium polyphosphate. NNO disperses and suspends well on some products, but the addition is excessive, easy to absorb moisture and make the particles become sticky; sodium polyphosphate has obvious effect on improving the suspension rate performance, but its industrial grade and analytical grade are quite different, no Conducive to the purchase, and excessive addition, it is easy to harden the particles, which is not conducive to disintegration. Moreover, the thermal storage properties of these two additives are not ideal.
5, filler
The commonly used fillers for WDG are kaolin, bentonite, diatomaceous earth, white carbon black and starch. Bentonite and white carbon black are excessive from WP, and their self-disintegration is good, but excessive addition greatly affects the suspension rate; kaolin has a wide variety, easy to granulate, disintegration is not as good as starch, and personally recommended calcined 1250 mesh White kaolin; starch is outstanding in disintegration, and the suspension rate is slightly inferior to that of 1250 mesh white kaolin. It is said that there is a good modified starch. I have never been able to try it. It is a pity.
6. About boiling granulation (spray granulation) and extrusion granulation <br> The formulation of the two granulation methods is different, and some novices have gone wrong on this issue. Extrusion granulation may be secondary to boiling or spray granulation in disintegration because there is "stress" in the material during extrusion and it is necessary to overcome this "stress" during disintegration.
I have been working on the WDG formula. The working time is not very long. Now I will write my own experience and experience. If you have any problems, I hope that the masters can give pointers and you can share with the novices.
In addition, regarding the landlord said that the high cost of d425 is high, I admit that it is higher than domestic additives, but you can look at the cost comparison between the products made with our additives and pure white products, or have a considerable advantage (no way) At present, WDG's racial discrimination is still very serious!)