On the latest glazing and drying technology I

2022-08-07
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Talking about the latest glazing and drying technology (I)

I. 5 The polishing and drying technology developed continuously since the experiment

a layer of colorless and transparent paint is applied (or sprayed and printed) on the surface of the printed matter. After leveling, drying, calendering and curing, a thin and uniform transparent bright layer is formed on the surface of the printed matter, which plays a polishing process of enhancing the smoothness of the carrier surface and protecting the finishing processing function of the printed text, As an important means of finishing, it has developed rapidly with the change of social tide after printing, and has achieved great results in the packaging and processing of foreign trade export products. In the technological innovation of realizing pre press digital networking and printing multi-color and high efficiency, the overall revolution of printing technology can be completed only by using high-tech to achieve exquisite automation in post press processing. The polishing process of using clean energy and clean raw materials to produce clean products will be widely promoted in the printing and packaging industries as an important post press finishing means facing the 21st century that meets the ISO14000 international environmental management standard

with the continuous popularization of glazing processing, the research and development of glazing coatings and machinery have been paid more and more attention by printing, packaging, chemical industry, machinery and other related industries. Glazing coatings have developed from oxidation polymerization and solvent volatilization to heat curing and light curing. Relying on the oxygen in the air to produce polymerization reaction to dry the liquid glazing coating into a film, the equipment investment is less; Depending on the solvent volatilization in the coating, the film has good leveling, processing performance and wide application range, but it needs two processes: glazing and calendering; Depending on the active functional groups contained in the polymer structure of the film-forming resin in the coating and the catalyst of the coating, the automatic glazing equipment for drying the film-forming has high production efficiency; After the coating absorbs the radiant light energy, the molecule is within ± 1% of the set value; When the speed is ≥ 0.05%fs/s, the internal structure is polymerized. The UV polishing mechanism for drying the conjunctiva can be synchronized with printing, and one machine can be used for multiple purposes. UV technology enables the process operations of printing and polishing on special machinery to be combined into the printing unit at one time

as an important drying technology of glazing process, it has also been continuously improved and developed. The drying treatment of glazing coating film-forming has developed from the hot air drying type of oxidation polymerization and solvent volatilization to the electric heating and ultraviolet drying type. With the development of high-tech, the use of clean energy and the pursuit of the maximum use of clean energy, the electron beam drying method, which integrates various advanced scientific and technological means, has been used in developed countries in Europe and the United States. It has rapidly developed into the latest UV/e-beam and thermal/e-beam hybrid drying treatment system, which will provide the printing and packaging industry with the highest level at the turn of the century and the 21st century. The basic principle and technology can be cured by cutting graphene micro sheets into a length about the width of human hair. The continuous application of technological innovation will make the glazing drying treatment more scientific, and further promote the quality improvement and economic development of the printing and packaging industry

II. Comparison of several drying methods for glazing process

solvent evaporation drying method

solvent based glazing coatings have different evaporation rates during coating and drying due to different paint formulations, different types and proportions of solvents used. The solvent volatilizes too fast, the leveling property of the polishing coating is not good, and there are quality problems affecting the surface smoothness such as streaks and sand holes on the surface after drying and film forming. Moisture condensation is induced by absorption of external heat during solvent volatilization, resulting in cracking or whitening of the dried coating. The solvent volatilizes too slowly, which will cause insufficient drying, poor conjunctival solidification, poor anti adhesion and other problems

UV curing drying method

UV curing refers to the glazing process that uses UV (ultraviolet) irradiation energy to cure the free radical polymerized acrylate coating into a film. The photoinitiator in the components of this kind of coating absorbs the light energy of ultraviolet ray, generates free radicals through the excited state, and leads to polymerization reaction

[pi]--------[pi]-------- [free radical]

photoinitiator excited photoinitiator

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

cured coating

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

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