Take the packaging bag as an example, whether it is an ordinary packaging bag or a retort bag, there is no abnormal situation in the production process of printing, compounding, bag making, etc. However, in the process of customer's use, there is always a phenomenon that some bags are damaged by spraying codes, ink is removed by high temperature sterilization, and the imprint color becomes lighter and lighter after coding. However, finding the cause from the production process failed, causing many difficulties to customers. In general, there are the following situations, let's analyze them.

1. leakage

PA // CPP combination, solvent-free composite, retort pouch products. There was no abnormal situation in printing and composite production, but during the use of customers, some bags were not sprayed with codes, accounting for about 10%.

2. drop code

High-temperature cooking bag structure: PET // AL // BOPA // RCPP, after high-temperature sterilization, code drop phenomenon occurs

3. spray code to absorb moisture

PA // PE, boiled bag, bag spray code absorb moisture, stick together, this situation is more serious in summer. After the bag is made, it will be sent to the customer's warehouse. The spray code is sprayed by the customer himself on the date of production. The date of use by the customer is only a few days before the bag leaves the factory. The longer the time, the worse it is to spray.

The reasons are summarized as follows:

1. Part of the surface of the BOPA film absorbs moisture, or the ultra-low smooth PA film, the bag runs irregularly, folds together or slides over, resulting in local leakage of spray.

2. In the production workshop of a general food factory, if the environmental water vapor is very large, the smoothness of the film surface is different, the water absorption rate of the film is different, the outer layer is PA, the type of coding machine ink is not easy to type, and the coding ink for frozen products is generally Japanese coding ink.

3. The time for bag use and coding should be arranged reasonably. Use it immediately after receiving the goods. The coding and coding effect should be better. The placing time of printed products should be minimized.

4. The low-molecular substances in the raw materials are not heat-resistant and float up through high-temperature additives, which hinders the coding ink from causing code drop.

Summary

1, absolutely can not use recycled recycled materials, the use of recycled materials will make the film surface smoothness decreased. The use of raw materials PA is synchronous, reducing the problem of difficult coding caused by raw materials.

2. The higher surface tension value of the film is good for coding. Generally, the surface tension of BOPP film should reach 40 dynes, PET 50 dynes and BOPA 52 dynes. Below these tensions, there is no adsorption fastness to the ink.

3. The temperature and humidity control in the workshop is very important, and the environmental humidity is properly controlled during production. Especially solvent-free composite, the general relative humidity is below 70%.