Why PP corrugated sheet need corona treatment?
1. What is corona treatment?
Corona treatment is an electric shock treatment that gives the surface of the substrate a stronger adhesion.
2. Corona treatment principle:
The principle is to use a high frequency and high voltage to corona discharge on the surface of the treated plastic to produce a low temperature plasma.These ions are destroyed by electromagnetic shock and penetration into the surface of the substrates to oxidize and polarize the surface’s molecules. Ion shocks and erodes the surface, increasing the adhesion of the substrate surface.
3. How to judge whether the corona treatment is qualified?
Dyne test pens (≥38 mN/m) can be used as a quick test tool for surface energy after corona treatment, but are not suitable for tests for printed or coated surfaces. If the test pen draws a continuous line on the corona treated surface, we can say the surface energy of the material is not less than 38 mN/m. If the line is intermittent, the surface energy of the material is less than 38mN/m, indicating it is insufficient or even untreated, and thus does not meet the printing requirements.
4. Can I use the same corona treatment machine for polypropylene corrugated sheets with different thicknesses?
PP corrugated sheets for advertising need to be corona treated, and the thickness of the sheets is usually 2-6mm;
Generally speaking, the power required for corona treatment of thin sheets (2-6 mm) is small, but the power required for corona treatment of thick sheets (8-10 mm) is double more.
If the power of the corona treatment machine is can be adjustable, then the machine can operate the corona treatment on either thick pp hollow sheets or thin ones.
5. What should I pay attention to when using a corona-treated PP corrugated sheet?
1）Try not to paste a temporarily used sticker on the corona-treated PP sheet because it has a strong adsorption to the glue. The glue will penetrate into the surface of the sheet and is difficult to remove.
2）Keep clean of pp corrugated sheet. The corona treated sheet has a strong adsorption force for dust.
3）Corona treated sheets have an optimum life span of six months. After six months, the corona effect will become weak. Therefore it is recommended to print and use the polypropylene corrugated sheets within half a year to ensure the best effect.