Pesticide flexible packaging in the production process of process issues

a) Composite process

The composite process is the same as that of food packaging composites, which is just to pay attention to the following issues:

※The matching of base film tension should be well controlled, which is an important means to prevent wrinkles and tunnels, as well as a measure to improve the yield and ensure economic benefits.

※The preparation of adhesive should be accurate, the proportion of the main agent and curing agent, the amount of diluent should strictly follow the provisions of the product specification, and should be fully stirred before use.

※ The amount of adhesive requirements than other composite materials, a little more per square meter to 4.5 ~ 4.8 grams of dry glue, too little will affect the peeling force, too much and increase the cost in vain. Therefore, in accordance with the operation of the concentration of glue (30% to 35%), to select the number of anilox rollers and the depth of the anilox line to ensure that the amount of glue needed.

※ drying process is determined to control the amount of residual solvents, appearance and internal quality and labor productivity factors, in general, the three-stage heating baking channel, the first section of the temperature in 60 ~ 650C, the second section in 75 ~ 80 ℃, the third section in 83 ~ 850C this condition is more appropriate. This condition is suitable for many kinds of base film, and the production speed can be about 100 meters per minute when the air blowing and exhausting are open.

The control of residual solvent is very important, and we hope to achieve 5mg/M2 or less. Therefore, if the process parameters of drying and start-up speed as described above do not achieve this goal, it is necessary to make corrections.

b. Aging process

※ Conventional maturation process

Usually, the composite winding is placed in the ripening room at 50 ℃ for 48 to 72 hours for ripening, of course, a little longer for the quality of good, but too long and reduce labor productivity, but also increase energy consumption.

※ Special aging process

Aging is the process of reacting the main agent and curing agent of polyurethane adhesive for compounding, under the conditions of temperature and time. In the case of polyurethane, it is a kind of adhesive that can react and cross-link and cure at room temperature, but it takes a long time to complete. For its bonding with other materials, since it is hoped that it and the surface of other materials should also have a chemical reaction to generate chemical bonds, more resistant to peeling off, the effect of heating is very obvious, so we have worked out a special aging process. That is, after 48 hours of aging at 50 ℃, if the CPP is used as the inner film, it will be placed at 90 ℃ for three hours of heat preservation, and if the PE is used as the inner film, it will be placed at 70 ℃ for eight hours. In this way, the peeling force and corrosion resistance of the composite film are improved. Shanghai Zijiang Color Printing & Packaging Co., Ltd. has adopted the special aging process recommended by us, which has also proved its effect.

Problems of bag making

※The temperature, pressure and time are the three main elements of bag making, among which the temperature plays a leading role. We have to use the best process parameters to achieve the best quality of the bag, but also pay attention to the angle of the hot knife, do not cause heat sealing of the innermost line, because the pressure is too large to make the thickness of the two layers of the inner membrane thinning, losing the original strength, therefore, the hot knife to have a certain angle.

※ Most of the automatic filling and bag making is with roller teeth type heat sealing. Roller teeth teeth edges too sharp or teeth marks too deep, often to damage the composite film, especially when containing a small elongation of aluminum foil or PET, it is easy to break it off, leaving only good elongation of CPP or PE, this bag is filled with pesticides, the leakage will soon occur, so it must pay attention to this problem.

Adaptability problem (actual test)

a. Determination of temperature and time for the actual test conditions. In the past, 56 soil 40C placed four weeks on behalf of the practice of a year, in recent years, many people say that 60 ℃ can be used to place a week on behalf of a year, what conditions are appropriate? It is difficult to determine. At present, Shanghai Zijiang Color Printing Co., Ltd. and Shanghai Lieyin Chemical Co., Ltd. use 60 ℃ for two weeks on behalf of a year of this practice.

b. Destructive test of solvent resistance --- corrosive solvent formula. Ltd. according to the liquid emulsion type pesticides, the formulation of the “strong corrosive”, “medium corrosive” and “low corrosive” of the three general-purpose formulations, the The content of DMF (i.e. N,N dimethylformamide) is 20%, and the rest is toluene, xylene, cyclohexanone, butanone, acetone, ethyl esterate, methanol and kerosene.

c, resistance to specific pesticide destructive test --- good composite bags filled with specific pesticides, put into the 60 ℃ constant temperature box to go, every day for observation and inspection, to see what 変化, there is no pockmarking, blistering, off the layer or leakage, if so, and on the first few days of the emergence of the records should be made, and to invite pesticide factories to participate in the test together, the two sides should be jointly retained samples to confirm. If both parties have confirmed, then both parties should not make any changes in the future, and should work together with the sealed samples.