Technical requirements and selection of finishing varnish

Release time:

2023-12-07

I. Technical Requirements for Varnish Ideal varnish, in addition to being colorless, odorless, highly glossy, quick-drying, and chemical-resistant, must also possess the following properties: 1. High film transparency and no discoloration To achieve excellent varnishing effects on decorative prints, a colorless and transparent film must be formed on the surface of the printed sheet, and the images and text must not discolor after drying. Moreover, it should not discolor or yellow due to sun exposure or prolonged use.

Technical requirements and selection of finishing varnish

I. Technical Requirements for Varnishing

In addition to being colorless, odorless, highly glossy, quick-drying, and chemical-resistant, the ideal varnish must also possess the following properties.

1. High film transparency and no discoloration

To achieve excellent varnishing effects on decorative prints, a colorless, transparent film must be formed on the surface of the print, and the images must not discolor after drying. Furthermore, it should not discolor or yellow due to sun exposure or prolonged use.

2. The film layer has a certain degree of abrasion resistance

Some varnished prints require a certain degree of abrasion and scratch resistance after varnishing. Because high-speed box-making machines, cardboard packaging machines, and book-covering production lines are used, the surface of the print is subjected to friction; therefore, it must have abrasion resistance.

3. Possesses a certain degree of flexibility

The bright film formed by any varnish on the surface of a print must maintain good elasticity to adapt to the flexibility of the paper or cardboard, preventing breakage, cracking, or peeling.

4. The film layer must have good environmental resistance

Some varnished prints are used to make various packaging boxes. To provide good protection for the packaged products, the varnish film layer must have good environmental resistance. For example, the packaging of food, cigarettes, cosmetics, and clothing must have moisture-proof and mildew-proof properties. In addition, the chemical properties of the dried film layer must be stable. It should not change properties due to contact with weak acids or weak alkalis in the environment.

5. Has a certain adhesion to the surface of the printed matter

Due to the influence of the surface ink layer integral density value of the printed matter, the surface adhesion is greatly reduced. To prevent cracking and peeling of the film layer during use after drying, the film layer must have strong adhesion and a certain degree of adhesion to the ink and various auxiliary materials used in ink adjustment.

6. Good leveling properties and a smooth film surface

The printing substrates are diverse, and due to the influence of the printed images, the surface absorbency, smoothness, and wettability vary greatly. In order for the varnish to form a smooth film layer on different product surfaces, the varnish must have good leveling properties, and the film surface must be smooth after film formation.

7. Wide post-printing processing suitability

After varnishing, prints generally undergo post-processing, such as embossing, hot stamping, and electro-aluminum foil stamping. Therefore, the varnish film layer must have wide post-printing processing suitability. For example, it must have good heat resistance and not stick after hot stamping electro-aluminum foil; it must have high solvent resistance, and the dried film layer must not bubble, wrinkle, or become sticky due to the influence of adhesives during post-processing.