Photoinitiators, also known as photosensitizers or photocuring agents, are commonly used in photocuring systems, such as UV adhesives, UV coatings, UV inks, etc. They absorb a certain wavelength of energy in the ultraviolet light region (250-420nm) or visible light region (400-800nm), which can generate free radicals, cations and some others, thereby initiating polymerization, crosslinking and curing of monomers.
Nantong Synasia New Material Co., Ltd. has many years of experience in photoinitiators and other products. Due to stable quality and extremely competitive price, our products have been sold to numerous countries at home and abroad.
自由基型光引发剂 / Free-Radical Photoinitiator
Depending on their reaction, free-radical photoinitiators are mainly divided into the following two categories:
Norrish Type II photoinitiators, also called hydrogen abstraction type photoinitiators, are generally based on aromatic ketone structures, and also include certain fused-ring aromatic hydrocarbons, which have certain light absorption properties, and the matching co-initiator, namely hydrogen donor, itself is not absorpted in the range of commonly used long-wave ultraviolet light. The hydrogen abstraction type photoinitiator absorbs light energy and has bimolecular interaction with the co-initiator in the excited state to generate active free radicals.
The photoinitiator KIP-100F produced by Synasia is composed of 1173 and KIP-150.
According to its structure, 1173 is a derivative of acetophenone. It belongs to a kind of free radical photoinitiator. As a liquid, 1173 is very easy to blend, suitable for compounding with other photoinitiators. For the UV curing system of unsaturated polyester systems and multifunctional monomers, 1173 has the characteristics of low odor, non-yellowing property and good color stability. It can be used for UV curing varnishes of acrylic ester series on paper, metal and plastic surfaces. It is especially recommended for UV coatings that require only slight yellowing even when exposed to sunlight for a long time.
In the UV curing system, small molecular photoinitiators are easy to volatilize and migrate during storage. On the one hand, it will reduce the initiation efficiency of photo-polymerization, and on the other hand, it may cause odor and toxicity of the product. In particular, the photocurable ink printed on food packaging bags is strictly prohibited from migrating small molecule photoinitiators or photosensitizers, otherwise it will pollute the internal food through the food bags. Bonding the small molecule photoinitiator to the polymer chain can reduce this migration effect. Therefore, polymeric photoinitiators have become an important research and development direction.
KIP-150 is a polymeric photoinitiator with good miscibility with resin systems, which provides low volatility and low migration. It can also be made into water emulsion and used as water-based photocuring initiator. The molecular chain of KIP-150 contains multiple initiator units, which can simultaneously form multiple free radicals on one macromolecule when irradiated by light, and the local free radical concentration can be very high. The local high concentration effect can effectively deal with oxygen inhibition and accelerate photopolymerization, but the probability of mutual coupling termination of active free radicals in macromolecules will also increase. By designing molecular structure, intramolecular free radical coupling can be reduced.
Due to the characteristics of high reactivity, low odor and good color stability, KIP-100F is generally used in various coatings and adhesives, etc. It involves in industries like plastics, wood, metal, etc.
Cationic photoinitiators are also very important type of photoinitiators, including diazonium salts, diaryliodonium salts, triarylsulfonium salts, alkylsulfonium salts, iron aromatic hydrocarbon salts, sulfonyloxy ketones and triarylsiloxane ether. They are suitable for cationic photopolymerization with monomers which mainly include epoxy compounds and vinyl ethers, followed by lactones, acetals, cyclic ethers, etc.
Nantong Synasia New Material Co., Ltd. provides two different cationic photoinitiators, UVI-6976 and UVI-6992, which are suitable for use with Synasia cycloaliphatic epoxy resin (S-06E or S- 21), as well as Synasia oxetane product (S-101 or S-221). Our products are widely used in microelectronics and information materials.
UVI-6976 is a mixed type triaryl sulfonium hexafluoroantimonate cationic photoinitiator, mainly used for curing systems which contain epoxy groups. It has the remarkable characteristics of fast initiation speed, low internal stress and excellent deep curing. Applications include cutting-edge manufacturing industries, such as printed circuit boards, liquid crystal displays and large-scale integrated circuits.
UVI-6992 is a mixed triacylsulfonium hexafluorophosphate cationic photoinitiator. Similar to UVI-6976, it is also used for curing epoxy systems. When the initiator concentration is low, the initiating activity of UVI-6976 is much higher than that of UVI-6992, but when the initiator concentration is high, the initiating activity of the two is similar. The volume shrinkage of the polymer obtained by the two initiation systems is lower. Our product is usually applied in inks, adhesives and thick coatings which use titanium dioxide as pigment.