The 30th Anniversary Commemorative Conference of the RadTech China Committee and the 23rd and 24th RadTech China Conferences were held in Yixing Taodou Peninsula Hotel from July 19th to July 21st after 2 years.
During the conferences, we exhibited a series of products such as cycloaliphatic epoxy resin DE021E, cycloaliphatic epoxy acrylate DR321 and hydroxybutyl acrylate HBA, providing various solutions for on-site consulting customers.
Just on June 14th, the European Chemicals Agency officially announced the addition of the photoinitiator TPO to the candidate list of substances of very high concern. This news also became one of the hot topics of this annual meeting.
The free-radical photoinitiator TPO has reproductive toxicity. Compared with free-radical photoinitiators, the cationic photoinitiation system is healthier and is also one of the important options for UV curing.
According to inquiries from on-site customers, we proposed targeted solutions to some problems in the radiation-curing industry:
Strong odor & irritation
The diluents HDDA and DPGDA commonly used in industry formulations have been listed as suspected carcinogens B. Although they are temporarily available, they are often accompanied by problems of strong odor and irritation.
In response to increasingly stringent emission reduction regulations and environmental health requirements, Donghua has launched hydroxybutyl acrylate HBA, which has the advantages of low odor and no irritation and can be used in acrylic coatings, water stabilizers, paper processing, textile treatment agents, photosensitive coatings, adhesives and other fields. The following is a set of comparative evaluation data:
Poor adhesion
Acrylic coatings have characteristics of high hardness and low elasticity and are prone to cracks and peeling when in contact with the substrate, resulting in easy damage and peeling of the coating and poor adhesion.
Compared with the 10-15% shrinkage rate of acrylate, the shrinkage rate of the cycloaliphatic epoxy-based cationic curing system launched by Donghua is only 1-3%. It can be used on different substrates such as metal, glass and plastic (such as PET, etc.), providing excellent adhesion.
Oxygen inhibition
Currently, most of the raw materials used in UV-curable coatings on the market are free-radical photosensitive resins and photoinitiators. As a result, the coatings prepared after UV radiation often have a narrow range of product applications, and also due to the existence of oxygen inhibition, the coating is not easy to cure, and the surface is often sticky even cannot be used.
In contrast, cationic polymerization technology has the advantages of fast curing speed, high efficiency, less energy consumption, not easily inhibited by oxygen, and does not require solvents during the curing process. Therefore, Donghua has developed a cycloaliphatic epoxy-based cationic system, which adopts high-efficiency, energy-saving and environmentally friendly cationic curing technology, and can be applied in inks, coatings, adhesives, electronic packaging and other fields.
Poor resistance to yellowing
Currently in many application fields, such as wood lacquer topcoats, the cost of polyurethane/acrylate is relatively high, and also ordinary epoxy acrylate has poor yellowing resistance. Donghua launched cycloaliphatic epoxy-modified acrylate 321, which has outstanding advantages such as low viscosity, fast curing speed, excellent yellowing resistance, and high gloss. For details, please refer to the comparison data:
Limited curing depth & incomplete curing of shaded areas/dark colors
The cationic polymerization of cycloaliphatic epoxy resin can be initiated by light or heat, or a combination of light and heat. Donghua has launched thermal curing and UV- and thermal curing solutions. You can choose epoxy-based thermal cationic polymerization, cationic thermal and photo-cationic polymerization, or thermal cationic and free-radical polymerization.
Thermal curing and photothermal initiating system can not only get rid of the limitations of the thickness of the cured sample and the shape of the substrate but also release the reaction stress, which results in more prominent bonding strength and mechanical properties.
In addition, cycloaliphatic epoxy resins are also featured in coating applications. The coating made of this kind of resin as the base material can withstand high temperature, and the cycloaliphatic structure endows the surface resistance and tracking resistance of the electrical coating, which helps to maintain the color and durability of the outdoor coating.
The cycloaliphatic epoxy-based UV-curable coating has strong weatherability, high hardness, good adhesion, as well as good resistance to abrasion, impact and chemical corrosion. It can be used for PCB solder mask inks, optical disc coatings, as well as metal or plastic cover protection, etc.
Cycloaliphatic epoxy resin DE021E
Cycloaliphatic epoxy acrylate DR321
Hydroxybutyl acrylate HBA
