1. Waterborne UV cured resin refers to the introduction of water-based groups or chain segments on the basis of traditional UV cured resin, making the resin have a certain degree of hydrophilicity and water absorption.
There are two common methods for synthesizing waterborne UV cured resins: one is to introduce hydrophilic groups [such as UP (unsaturated polyester) resin] into the molecular chains of traditional resins; Another method is to react with acrylate to generate waterborne acrylate oligomers [such as PUA (polyurethane acrylate), EA (epoxy acrylate), etc.]. Waterborne UV cured resin has the advantages of no solvent odor, non-toxic, pollution-free, easy operation, easy cleaning of residual adhesive, high solid content, and safe and convenient storage and transportation. It is the development direction of environmentally friendly and energy-saving UV cured resin. Classification of waterborne UV cured resins
Oligomers are an important component of waterborne UV curing systems. Unlike traditional UV cured resins, the molecular structure of waterborne UV cured resin matrix must contain hydrophilic groups or hydrophilic chain segments to give the polymer a certain degree of water absorption. Waterborne UV cured oligomers can be divided into UP, PUA, and EA types according to the different matrix resins. The comprehensive performance of PUA is relatively good, while the chemical stability of EA is relatively good. Therefore, when selecting the components of the water-based UV curing system, the selection of prepolymers has a significant impact on the thickness, hardness, and shear strength of the Z final curing adhesive film.
UP resin is one of the raw materials used in UV curable coatings as early as Z. Waterborne UP refers to an ionic copolyester made by introducing ionic structural units into the molecular chain of traditional UP. The presence of ionic groups not only endows UP with good water solubility, but also endows it with excellent moisture absorption and ion conductivity characteristics.
The commonly used water-based modifiers mainly include volatile amines, sulfonates, etc. (which can be used alone or in combination), which can generate or introduce base groups on UP (control the acid value or neutralization degree of UP to make different dispersion systems), making the resin have good water solubility and water dispersibility. Satute et al. added different proportions of MA (maleic anhydride) and PA (phthalic anhydride) to PG (propylene glycol) to produce six different carboxyl terminated UPs.
The results show that when ammonia is used as the emulsifier of UP in water, the prepared film has excellent stability. The hardness, flexibility, water resistance, chemical stability and solvent resistance of UP lotion increase with the increase of MA content. Jankowski et al. used sodium 3-hydroxy-1-propane sulfonate or sodium dihydroxypropane sulfonate as sulfonate modifiers and prepared a novel waterborne UV curing resin containing water absorbing sulfonic groups through copolymerization. The coating had high hardness and good adhesion to glass and metal substrates.