What are the requirements for the printing process of aluminum foil steaming bags?

The printing process of aluminum foil steaming bags needs to meet the following requirements to ensure product high temperature resistance, safety, and printing quality:

1、 Ink selection and processing

Specialized Steam resistant Ink

It is necessary to use polyurethane ink that is resistant to high temperatures and penetration to avoid pigments from penetrating into the BOPA or RCPP layer and contaminating the contents at high temperatures.

High temperature cooking ink from different manufacturers cannot be mixed and must be accompanied by a dedicated dilution solvent (purity ≥ 99%).

Curing agent addition

Large scale use of spot color and white ink requires the addition of 1% -3% curing agent, and the amount added must strictly follow the technical specifications of the ink manufacturer.

The remaining ink cannot be used for printing high-temperature steamed products and needs to be disposed of in a timely manner.

2、 Substrate pretreatment and printing environment

Substrate quality control

BOPA or BOPET substrates must meet the requirements of corona value ≥ 52 dyne, uniform thickness, and no pollution. BOPA recommends using synchronous stretching process to enhance stability.

Before printing, the BOPA film needs to be preheated (placed at 35 ℃ for 2 hours) and the humidity in the printing workshop should be controlled to be ≤ 75%.

Drying and temperature gradient

During printing, a temperature gradient should be set in the oven, and the drying temperature should be adjusted according to the ink area: the temperature in the large-area ink area should be increased by 10-15 ℃.

3、 Printing process control

Solvent residue control

It is necessary to adjust the oven temperature, air volume, and printing speed to ensure the minimization of solvent residue (total residue<5mg/m ²).

Overprint accuracy guarantee

During the printing process, it is necessary to avoid moisture and shrinkage of BOPA film, and ensure printing accuracy through preheating and humidity control.

4、 Post printing processing

Moisture proof packaging

The printed BOPA film needs to be wrapped and sealed with aluminum foil or composite aluminum plated film to prevent moisture and performance changes.

Timeliness requirements

The printing material with added curing agent needs to complete the composite process within 3 days. It is recommended to first rewire and use it as soon as possible.

5、 Special design requirements

Printing patterns should avoid full page design, and it is recommended to keep the heat sealed edges transparent to enhance the heat sealing strength; Simplifying the pattern can reduce the amount of ink used and the risk of penetration.