In this article, the common paper-plastic separation in solvent-free composite process is analyzed in detail.
Separation of paper and plastic
The essence of paper plastic composite is to use the adhesive as the intermediate medium, on the roller of the film laminating machine, under the action of external force of heating and pressure, bi-directional wetting, penetration, oxidation, and conjunctiva drying of the plant fiber of the paper, the non-polar polymer film of the plastic and the ink layer, to produce effective adsorption and make the paper plastic firmly bonded.
The phenomenon of paper plastic separation is mainly manifested in the insufficient peel strength of the composite film, the glue does not dry, and the paper printed matter is separated from the adhesive layer on the plastic film. This phenomenon is easy to appear in products with large printing area and large field. Due to the thick ink layer on the surface, the glue is difficult to wet, diffuse and penetrate.
- 1. Principal Consideration
There are many factors affecting the separation of paper and plastic. The smoothness, uniformity, water content of paper, various properties of plastic film, thickness of printing ink layer, number of auxiliary materials, temperature and pressure during paper-plastic composite, production environmental sanitation, temperature and relative humidity will all have a certain impact on the result of paper-plastic composite.
- 2. Treatment
1) The ink layer of the ink is too thick, resulting in the penetration and diffusion of the adhesive, resulting in the separation of paper and plastic. The treatment method is to increase the coating weight of adhesive and increase the pressure.
2) When the ink layer is not dry or fully dry, the residual solvent in the ink layer weakens the adhesion and forms paper-plastic separation. The treatment method is to wait for the product ink to dry out before compounding.
3) The residual powder on the surface of the printed matter will also hinder the adhesion between the paper and the plastic film to form the separation of paper and plastic. The treatment method is to use mechanical and manual methods to erase the powder on the surface of printed matter and then compound.
4) The operation process is not standardized, the pressure is too small, and the machine speed is fast, resulting in the separation of paper and plastic. The treatment method is to operate in strict accordance with the process specifications, appropriately increase the pressure of film coating and reduce the machine speed.
5) The adhesive is absorbed by paper and printing ink, and the paper plastic separation caused by insufficient coating weight. The adhesive shall be reformulated, and the coating weight shall be determined according to the manufacturer’s requirements.
6) The corona treatment on the surface of plastic film is insufficient or exceeds the service life, resulting in the separation of paper and plastic caused by the failure of the treatment surface. Corona the plastic substrate or renew the plastic film according to the corona standard of film coating.
7) When using single component adhesive, if the paper and plastic are separated due to insufficient air humidity, manual humidification shall be carried out according to the humidity requirements of single component adhesive processing technology.
8) Ensure that the adhesive is within the warranty period and stored and used according to the manufacturer’s requirements. For example, the two-component automatic mixer is in good condition to ensure the accuracy, uniformity, and sufficiency of the ratio.
Post time: Dec-30-2021