Is your screen-printed glass bottle always peeling? A UV lamp manufacturer reveals the key elements of "complete curing"
In the glass packaging industry, screen printing is widely used in cosmetics, high-end beverages, and fine chemicals due to its unique texture and three-dimensional effect. However, "insufficient ink adhesion," "paint peeling," and "easily scraped off with a fingernail" remain persistent problems for production managers. Many manufacturers attribute this to ink quality or the cleanliness of the glass surface, but as a professional UV curing equipment supplier, we have discovered through thousands of experiments that 80% of paint peeling problems stem from incomplete UV curing. To achieve true "complete curing," the following three core elements must be mastered.
I. Wavelength Matching: Grasping the "First Hook" on the Glass Surface
Glass is a non-porous material, preventing ink from penetrating like paper. UV ink curing relies on a photoinitiator absorbing specific wavelengths of ultraviolet light to trigger a chemical reaction.
Pain Point:
If the UV lamp's spectrum doesn't match the wavelength required by the ink, the ink surface may appear dry, but the underlying layer in contact with the glass remains "half-cooked," which is the root cause of paint peeling.
Solution:
Currently, mainstream UV-LED curing systems typically use wavelengths of 365nm, 385nm, or 395nm. For thicker screen printing layers, we recommend using a narrow-band high-energy UV-LED light source.
- 365nm is more conducive to surface drying.
- 395nm has stronger penetrating power, reaching directly to the bottom of the ink, allowing the ink to form a strong chemical bond with the glass surface, firmly "grabbing" the bottle.
II. Irradiation Energy (J/cm²): Not Just "Irradiation," But "Penetrating"
Many customers have a misconception: they believe that as long as the UV lamp is on, curing is complete. In fact, the curing effect depends on the product of irradiation intensity (Power) and effective energy (Energy).
Pain Point:
When the production line speed increases, if the energy density of the UV lamp is insufficient, the ink molecular chains cannot fully cross-link, resulting in insufficient ink film hardness and failure to pass the cross-cut adhesion test or alcohol wipe test.
Solution:
- High Power Density: The selected UV lamp peak intensity should reach 12W/cm² or higher to ensure sufficient free radicals are instantly generated.
- Energy Closed-Loop Monitoring: Our intelligent curing system supports real-time energy monitoring and automatically compensates for the attenuation caused by lamp aging, ensuring completely consistent curing effects from the first bottle to the 10,000th bottle on the production line.
III. Infrared Thermal Effect Control: Solving the Brittleness Caused by Overheating
After screen printing on glass bottles, if the infrared heat emitted by the UV lamp is too high, it will cause a sudden rise in the glass surface temperature, creating internal stress in the ink.
Problem:
Excessive temperature causes the ink to become brittle. Even after curing, the ink film will peel off in sheets like a shell when subjected to impact or temperature changes.
Solution:
Switch to UV-LED cold light source technology. Compared to traditional mercury lamps, UV-LEDs do not produce infrared heat radiation, and the temperature rise of the bottle can be controlled within $5°C. This not only protects the glass bottle from breakage due to uneven heating but also maintains the flexibility of the ink, ensuring excellent impact resistance while maintaining hardness.
Improving the quality of screen-printed glass bottles is not simply a matter of changing the ink; it's an art of balancing light source, energy, and temperature. As a technology leader with years of experience in UV curing, Shenzhen Super-curing Opto-Electronic CO., Ltd. not only provides lighting fixtures but also offers complete turnkey curing solutions.
Say goodbye to paint peeling problems by upgrading to a scientifically designed UV curing system.
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