Prevent plastic bottle deformation

The deformation occurs in the packaging of plastic bottles of pesticide emulsifiable concentrate, its deformation can be divided into three categories according to their causes: in the season of pesticide sales or some special cases, filling plastic bottles with the pesticide's temperature will be much higher than the ambient temperature. And the general pesticide filling immediately after sealing the cover tight. To avoid pesticide filling spilled or overflow bottle, a bottle of the product than the general content required to fill liquid volume of at least 10% more. In other words, more than 10% of the temperature of the remaining air in the bottle is the same as that of the pesticide. When after some time, pesticide and internal air temperature drop, the bottle will be negative pressure due to thermal expansion and contraction of the liquid liquefied and saic. When the negative pressure exceeds the strength of the bottle wall, it will cause the plastic bottle wall.

Two, due to mutual dissolution, weight loss caused deformation. This deformation is derived from the principle of polar solubility of chemical substances. Polar organic solvent emulsion pesticide Their natures are much the same. when the polarity of plastic bottles and packaging materials each different, there will be mutual solubility. As time goes on, mutual dissolution will develop into penetration. The organic solvent will penetrate from the molecular packaging bottle body material clearance to escape. A bottle of 100 ml of pesticide after a certain time will become 90 mL, 80 ml, or even less. Because this pesticide bottle lid is sealed, the leakage caused by weightlessness will produce negative pressure, eventually making the bottle deform, in general, when the high-density polyethylene (PE) bottles used for packaging or aliphatic esters and ketones, or aromatic solvent; when the polyester bottle packing (PET) two methyl formamide (DMF) when the inner bottle; when CO extruded polyvinyl alcohol (EVOH) packaging aromatic or ester and ketone solvents, this kind of phenomenon will happen. Three, due to oxidation caused by negative pressure deformation. The pesticide composition is very complicated, the ingredients contained in some special solvents or emulsifiers, or unknown impurities in the raw material are often stored in the bottle and the oxygen in the air oxidation reaction occurs, resulting in negative pressure and deformation. In this case, we have done several rapid aging tests to confirm. As we will test 1.8% abamectin pesticides into the plastic bottle lid tightly open a small hole on the cover and put a U - some water pipes are connected. Then, we put the bottle of pesticide and its connected U-shaped tube into 50 degrees + 2 degrees in the oven for heat storage for 5 days, while the daily record of the U tube surface height changes. At the beginning of heating and after some time, due to pesticide bottles in the liquid and air heated expansion, positive pressure in the bottle. The liquid level of the U-shaped tube communicated with the bottle is lower than that of the outer atmosphere. However, with time, the liquid level height becomes smaller, 30-hour flush. Then, the atmosphere with the liquid surface began to be lower than the same level with the bottle, which shows that the bottle has begun to appear negative pressure. When the full five days to remove the test pesticide and return to room temperature, the measured liquid level difference into negative pressure value of -12.9 kPa (Kpa), the time, the oxygen content of the bottle from the original 20%~21% to 5%~7%. Several methods to solve the deformation given plastic bottle deformation is a common phenomenon, plastic bottle manufacturers need to work together with pesticide manufacturers to explore and strive to solve this problem.

A method to overcome the deformation caused by hot filling. Very simple and very direct, as far as possible at room temperature filling. To achieve this purpose, the pesticide manufacturer shall take or prolong the circulation of the pipe or increase the cooling device to overcome the temperature of the reactor. If these methods can not be achieved, the pesticide should be filled into a plastic bottle, it will be cooled to room temperature, and then a sealed cap.

Two, due to mutual dissolution, weight loss is caused by the deformation of the solution. The main method is according to the different solvents on pesticides, choosing different plastic bottles for the material of barrier effect, and the selection before the compatibility test to confirm. In general, liquid pesticides, water agents, the deformation of the suspension agent, and ordinary plastic bottles have been fully qualified. Because the pesticides containing solvents are more aggressive, so in the new China promulgated on March 1, 2001, and since the implementation of the "packaging" in specific pesticides EC should be used glass bottles, HDPE bottles, and other equivalent fluoride materials such as packaging bottle (bag). , polyester bottle (PET) also has a good barrier effect of some pesticide use solvents, but PET because of its easy to absorb moisture in the environment, resulting in water, and even exceeds the standard of pesticide decomposition failure this in the world congenitally deficient, the restriction of the use of. On the barrier effect of bottles, glass bottles, aluminum bottles, bottle coextrusion (inner nylon or polyvinyl fluoride bottles) and have good performance. But relatively speaking, the glass bottle because of its vulnerability to the fatal weakness of the application of pollution and reduce. Aluminum bottles are more expensive. In terms of price, the multilayer bottle is less than the fluoride bottle; the effect is concerned, 100 ml and below the multi-layer bottle is better than the fluoride bottle, but the greater the specification, the stronger the competitiveness of fluoride bottles. Because the multilayer bottle's inner layer selects the type of nylon or polyvinyl alcohol depends on the pesticide solvent, the inner wall of the bottle for four polyvinyl fluorides ( plasticwang ) fluorine plastic layers, the composition is very complicated, so in the selection of the two barrier bottle, compatibility test must be carried out to confirm that the product, barrier effect.

Three, due to the negative pressure caused by the oxidation solution. As far as the pesticide manufacturer is concerned, it is possible to replace the solvent or emulsifier to control the impurity content of the raw material to improve the purity and decrease the oxidation potential. meanwhile