Self-adhesive labels, also known as self-adhesive label materials or instant labels, are composite materials made of paper, film, or special materials as the face stock, coated with adhesive on the back, and with silicone-coated release paper as the backing paper. The standard structure typically includes three layers: the surface substrate (printing surface), the release layer (silicone oil substrate), and the adhesive. Self-adhesive label materials were invented by R. Stanton A. E. Lee in the 1930s. This technology was introduced to China in the late 1970s. Compared with traditional labels, self-adhesive labels have advantages such as not requiring glue, paste, or water, being pollution-free, and saving labeling time.
The main printing methods for self-adhesive labels include letterpress printing, offset printing, flexographic printing, gravure printing, and screen printing. Among these, offset printing is the primary method used by Chinese label printing plants for printing paper-based self-adhesive labels, characterized by its fine graphics and rich detail. Flexographic printing produces quality comparable to offset printing, and uses water-based and UV inks, resulting in less environmental pollution. With technological advancements, traditional flatbed die-cutting machines have been improved in terms of speed, automatic registration, and post-printing inline operation. Their short die-cutting blade manufacturing cycle and low price make them more suitable for short-run production. Meanwhile, rotary die-cutting remains suitable for long-run production. Gravure printing is a common method for film printing, boasting a high degree of automation. Screen printing is the most adaptable printing method, characterized by rich ink color and strong three-dimensional effect. Adhesive for self-adhesive labels is divided into water-based adhesive and hot melt adhesive.
With the rapid development of digital printing technology and the application of technologies such as the Internet of Things and big data, the self-adhesive label industry is gradually achieving digitalization and intelligentization. Digital printing technology meets the diverse and rapidly evolving needs of the market. Digital-flexographic combined printing technology combines the variable data capabilities of digital printing with the batch production efficiency of flexographic printing. Simultaneously, intelligent methods such as AI quality inspection systems and cloud printing platforms are also improving production efficiency and reducing defect rates.