Talking about the latest glazing drying technology (1)

First, the continuous development of glazing drying technology in the print surface coating (or spray, printing) on ​​a layer of colorless and transparent paint, after leveling, drying, calendering, curing a thin and uniform transparent bright layer on the surface of the printed matter The glazing process, which enhances smoothness of the surface of the carrier and protects the finishing functions of printed graphics, has become an important means of finishing after printing and has achieved great results in the packaging and processing of foreign export products. In the technological innovation of prepress digital network and high-efficiency multi-color printing, post-press processing can only accomplish the complete revolution of printing technology by using high technology to achieve exquisite automation. The glazing process using clean energy and clean raw materials for the production of cleaning products will be used as an important post-print finishing tool for the 21st century to meet the ISO14000 environmental management international standards. It will be fully promoted in the printing and packaging industry.

With the increasing popularity of glazing processing, the research and development of glazing coatings and machinery are increasingly valued by related industries such as printing, packaging, chemicals, and machinery. Glazing coatings have evolved from oxidative, solvent-vapor-soluble to heat-curable and photocurable types. Reliance on oxygen in the air to polymerize the liquid glazing coating to dry the film investment equipment less; rely on the solvent solvent evaporation drying film forming a good leveling, processing performance and a wide range of adaptation, but the need for glazing, Two steps of calendering; Reliance on the active functional groups contained in the film-forming resin in the coating material and the catalyst of the coating in case of thermal cross-linking reactions. The automatic film coating machine has a high production efficiency; After absorbing the radiation energy of the coating, , The molecular internal structure of the polymerization reaction drying the conjunctiva UV glazing mechanism, can be synchronized with the printing, a multi-purpose machine. UV technology allows the printing and coating processes to be performed on a dedicated machine to be integrated into the printing unit at one time.

As an important polishing technology, the drying technology has also been continuously improved and developed. The coating drying process of glazing coatings has evolved from hot-air drying of oxidative polymerization and solvent evaporation to electrothermal and UV drying. With the development of hi-tech and the use of clean energy and the pursuit of clean energy, the electron beam drying method integrated with various advanced scientific and technological means has been used in developed countries in Europe and America. The rapid development of the latest UV/electron beam and thermal/electron beam hybrid drying systems will provide the latest high energy curing fundamentals and technologies for the printing and packaging industries at the turn of the century and the 21st century. The continuous application of technological innovation will make the coating drying process more scientific and further promote the quality improvement and economic development of the printing and packaging industry.

二、Comparison of several drying methods for polishing process

Solvent evaporation drying method

Solvent-based glazing coatings have different types and proportions of solvents for different coating formulations, and the evaporation rate during coating and drying is also different. The evaporation speed of the solvent is too fast, the leveling property of the coating material is not good, and the quality problems such as streaks and tresses that affect the surface smoothness appear on the surface after the film is dried. And in the process of solvent evaporation, it absorbs external heat and induces condensation of moisture, causing cracking or whitening of the dried coating. Solvent evaporation is too slow and can cause problems such as insufficient curing of the conjunctiva, poor resistance to stickiness, and the like.

UV curing drying method

UV curing is a glazing process that uses UV (Uitraviolet, ie, ultraviolet) irradiation energy to cure a film of a free-radical-polymerized acrylic ester. Photoinitiators in the components of this type of coating absorb the light energy of the ultraviolet light and generate free radicals in the excited state, which leads to a polymerization reaction.

[PI]-------[PI]--------[Free radicals]

Photoinitiator excited photoinitiator

[radical]+[monomer]+[oligomer]--[polymer]

Cured coating

UV curing has the characteristics of rapid curing and low temperature curing, which helps improve product quality, maintain consistent color, shorten printing time, prevent air pollution, reduce fire risk and improve working environment.