UV is a coating that can be rapidly cured to form a film in a few seconds under the irradiation of ultraviolet (ultraviolet, UV for short). UV coating is automatically rolled and sprayed onto the furniture board by machinery and equipment. Under the irradiation of ultraviolet light, the initiator is decomposed, free radicals are generated, resin reaction is initiated, and it is instantly cured to form a film without solvent volatilization, so it is more efficient. ,Green.
Under the general trend of water-based, water-based UV coatings are also successfully applied in many fields such as woodware, plastics, printing, and daily chemicals due to their environmental friendliness and construction friendliness. Raw materials play an important role. The performance, characteristics and applications of water-based coatings The continuous innovation of solutions promotes the process of resin water-based.
Major Improvement System
1 Epoxy acrylate/urethane acrylate composite system
The photosensitive oligomer is the main part of the UV curable resin and determines the basic properties of the cured resin. All kinds of matrix resins have their irreplaceable advantages, but they also inevitably have defects. For example, epoxy resin-based cured film has high hardness, good adhesion, high gloss and excellent chemical resistance, but it has the disadvantage of poor flexibility. Another example is the polyurethane-based resin has excellent properties such as abrasion resistance and scratch resistance, but its weather resistance is insufficient. The researchers combine the two by blending or hybridization, so as to make up for the insufficiency of a single resin and develop a system with both excellent properties.
2 Dendritic or hyperbranched systems
Aqueous UV-curable dendrimers or hyperbranched oligomers are a new class of polymers with spherical or dendritic structures without entanglement between molecular chains. Moreover, the highly branched polymer structure contains a large number of active end groups, which can be modified to adjust the properties of the polymer and make it applicable to specific fields. Compared with linear polymers of the same molecular weight, hyperbranched oligomers have excellent properties such as low melting point, low viscosity, easy solubility and high reactivity, and are ideal materials for water-based photocurable matrix resins. The water-based hyperbranched polyester composed of polyhydroxy functional aliphatic polyester as the core has good water solubility and low viscosity, so it can reduce the dilution water and show a good viscosity reduction effect.
3 Epoxidized soybean oil acrylate
Epoxidized soybean oil has low cost, environmental protection, long molecular chain and moderate cross-linking density, which can significantly improve the flexibility and adhesion of coatings. In recent years, it has become a research hotspot in the field of coatings at home and abroad. Domestic epoxidized soybean oil acrylate and modified epoxy soybean oil acrylate UV free radical curing coatings have achieved good results. CUB companies in the United States have already carried out commercial production, such as Ebercy860. The synthesis method of epoxidized soybean oil acrylate is generally a half-ester modification method, which is to carry out an esterification reaction between epoxidized soybean oil and acrylic acid.
Prospects of Waterborne UV Resin Coatings
Waterborne UV resin coatings can be quickly cross-linked and cured under the action of photoinitiators and ultraviolet light. The biggest advantage of water-based resin is that the viscosity is controllable, clean, environmentally friendly, energy-saving and efficient, and the chemical structure of the prepolymer can be designed according to actual needs. However, this system still has shortcomings, such as the long-term stability of the coating water dispersion system needs to be improved, and the water absorption of the cured film needs to be improved.
Some scholars have pointed out that the future water-based light curing technology will develop in the following aspects, evonik epoxy curing agents.
(1) Preparation of new oligomers: including low viscosity, high activity, high solid content, multifunctionality and hyperbranching.
(2) Develop new reactive diluents: including new acrylate reactive diluents, with high conversion rate, high reactivity and low volume shrinkage.
(3) Research on new curing systems: In order to overcome the defects of incomplete curing sometimes caused by limited UV light penetration, dual curing systems are used, such as free radical photocuring/cationic photocuring, free radical photocuring, thermal curing, free radical photocuring, and free radical photocuring. Based on photocuring/anaerobic curing, free radical photocuring/moisture curing, free radical photocuring/redox curing, etc., the synergistic effect of the two can be fully exerted, which promotes the further development of the application field of waterborne photocurable materials.
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