UV curable coatings have the advantages of fast curing speed, environmental friendliness, energy saving, low cost, etc. “, and are widely used in paper, rubber, plastic and other coating fields. Generally speaking, the photosensitive liquid resin can be directly converted into a cured resin by placing it under a UV lamp at air temperature Generally, it does not contain volatile organic compounds for one day. With the attention paid to environmental issues, the research, development and application of this environment-friendly “green” process are becoming more and more in-depth and popular. Hydrophilic coating is a kind of functional coating developed rapidly in recent years It is mainly used in aluminum and aluminum alloy products, such as aluminum fins of air conditioning heat exchanger. The traditional hydrophilic coating is usually made by baking the hydrophilic resin at 200C for tens of seconds, then curing and cross-linking to form a film. Although the preparation method has mature technology and good hydrophilicity, it consumes large energy, volatilizes more organic solvents and has poor construction environment. The preparation of pure organic hydrophilic coatings by UV curing and cross-linking can not only take advantage of the advantages of UV curing, but also meet the requirements of hydrophilicity. In this paper, a new synthesis idea was adopted. Based on low molecular weight acrylate copolymer, photosensitive monomer was introduced, and then photocurable cross-linked film was formed to prepare hydrophilic coatings. The effects of the introduction of GMA, monomer ratio, active diluent type and content on the hydrophilicity and water resistance of the coatings were investigated.
UV curable materials are usually hydrophobic, which is closely related to the composition of their formulations. Photoinitiators must be used in the UV curing formula. Sometimes, in order to increase the surface curing, some additives to promote the surface curing will be added. These photoinitiators and additives are usually hydrophobic, and the decomposition products of photoinitiators will migrate to the surface of the curing material, thus strengthening the hydrophobicity of UV curing materials. The resin and monomer in the UV curing formula are also basically hydrophobic in nature, and the contact angle is usually between 50 and 90 degrees.
Styrene sulfonate, polyethylene glycol acrylate, acrylic acid and other materials are hydrophilic themselves, but when used in UV curing materials, the hydrophilicity of cured materials will not be significantly increased, and the contact angle will generally remain greater than 50 degrees.
Hydrophilicity means that molecules or molecular aggregates are easy to absorb water or can be dissolved by water. The surface of solid materials formed by such molecules is easily wetted by water. The application of many coatings requires the material surface to have good enough hydrophilicity, such as film, offset printing, special adhesives, biocompatible materials, etc. In practical applications, the hydrophilicity is usually measured by the contact angle of water on the material surface obtained with an angle meter. Materials with contact angles less than 30 degrees are generally considered hydrophilic.
Post time: Nov-29-2022
