Development and Application Technology of Fluorescent Anti-counterfeiting Ink for Plastic Packaging (2)

Obviously, it is difficult to achieve the above requirements for a single solvent. Therefore, a mixed solvent is often used in a plastic gravure ink, and generally, solvents having different boiling points (medium boiling point, low boiling point, and high boiling point) are used together.

By comparing the dissolution parameters of the binder resin, and combining the above requirements, after repeated comparisons and calculations of the ratio dissolution and grinding experiments, we believe that the use of 2 to 3 solvents in combination can achieve the desired ink formation effect.

3. Development of fluorescent anti-counterfeiting pigments

Fluorescent pigments are important components of fluorescent anti-counterfeit inks. In addition to satisfying the printability of gravure inks, they must also have anti-counterfeiting effects that occur after UV irradiation. The special fluorescent pigment used in the fluorescent anti-counterfeiting printing ink for plastic packaging is itself a white substance. After the ink is printed on the substrate, it can exhibit bright yellow, bright blue, bright red and other hue under ultraviolet irradiation, and is suitable for high-grade Packaging and printing of goods.

Quinazolinone fluorescent pigments are commonly used fluorescent pigments. Its molecular structure is:

Compared with the inorganic zinc sulfide fluorescent pigment system, it has the characteristics of small density, fine particles, easy dispersion, easy to form ink, etc. Compared with rare earth metal chelate fluorescent pigments, it has good fluorescence intensity, strong durability and stability. For good characteristics, the ultraviolet absorption wavelength has a strong peak at 290-31 Onm and 461.4 nm, and therefore, the substance has obvious fluorescence characteristics.

In addition, in order to enable the fluorescent pigment to wet out with the binder during the ink formation process, the alcohol-alkaline mixture must be used to treat the fluorescent pigment to improve the printability of the fluorescent security ink. Experiments show that the fluorescent pigment has good water resistance, acid resistance, alkali resistance and alcohol resistance, and can completely meet the requirements of plastic gravure ink.

4. Matching ink and application

After determining the miscibility and ink-forming properties of the fluorescent pigment and the binder resin solution, orthogonal experiments were carried out with different blending ratios. The final identification of the plastic packaging fluorescent anti-counterfeiting ink is as follows:

Pigments 8%～20%

Material 50%～75%

Accessories 0-5%

Additives 0.2%～0.5%

Additives 0.4%～1%

Additives 0.5% to 1%

Mixed solvent 3%~5%

In practice, winter and summer should be adjusted according to the change of the ambient temperature, and the amount of the binder resin liquid in the ink formulation and the solvent content in the resin liquid should be adjusted appropriately. The study found that the proportion of the resin solution in the formulation did not change significantly with temperature. The ink was stored in the laboratory for one year, and there was no significant change in the performance of the ink, demonstrating that the storage stability can meet the practical requirements. After the ink was actually printed in the printing factory, it achieved a satisfactory printing effect and was well received by users.