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In recent years, photoinitiated polymerization has been widely used in the fields of UV-curable adhesives, UV-curable inks, UV-curable coatings, 3D printing, etc. The photopolymerization process is generally considered as a "green chemistry", which uses light as the driving force to form suitable initiating active species, such as free radicals, cations, etc., by absorbing photon energy and accompanying photochemical reactions, thus inducing the polymerization reaction. Therefore, it is very important to choose a suitable light-absorbing material, namely photoinitiator. The internal reason is that the absorption property (mainly wavelength and molar extinction coefficient) and reaction activity of the photoinitiator directly determine its initiation performance, and the external reason is that whether the absorption spectrum of the photoinitiator matches the emission spectrum of the light source directly affects the efficiency of the photoinitiator system. Next, we will explain the above concepts and their interrelationships one by one, hoping to enlighten the industry colleagues a little.

        Photoinitiator, also known as photosensitizer or photocuring agent, is a kind of compound that can absorb energy of a certain wavelength in the ultraviolet light region (250~420nm) or visible light region (400~800nm), produce free radicals, cations, etc., and thus initiate monomer polymerization, crosslinking and curing. In the UV curing system, including UV adhesive, UV coating, UV ink, etc., after receiving or absorbing external energy, it will undergo chemical changes and decompose into free radicals or cations, thus initiating polymerization reaction. All substances that can produce free radicals and further initiate polymerization under light are collectively referred to as photoinitiators. After some monomers are illuminated, the absorption photons form the excited state M *: M+hv → M *; The excited active molecules are split to produce free radicals: M * → R ·+R ′ ·, and then initiate monomer polymerization to form polymers. Radiation curing technology is a new technology of energy conservation and environmental protection. UV and electron beam (EB), infrared, visible, laser, chemical fluorescence and other radiation light irradiation and curing fully conform to the "5E" characteristics: Efficient (efficient), Enabling (practical), Economic (economic), Energy Saving (energy saving), Environmental Friendly (environmentally friendly), so it is known as "green technology". The photoinitiator is one of the important components of the photocurable adhesive, which plays a decisive role in the curing rate. After being irradiated by ultraviolet light, the photoinitiator absorbs the energy of light and splits into two active free radicals, which leads to the chain polymerization of the light-emitting curing resin and the active diluent, making the adhesive crosslinked and solidified. Its characteristics are fast, environmental protection and energy saving.

The number of registered visitors from three channels has exceeded 1400, and the "China Pharmaceutical CMC Industry Chain Technology Exchange and Entrepreneurs and Scientists Summit Forum" in 2022 will be held in Hangzhou on September 15-16

On August 9, sponsored by the Radiation Curing Professional Committee of the Chinese Photosensitive Society, and hosted by China Tongfu Co., Ltd. and Zhongshan Yibigu Electron Beam Technology Co., Ltd., the China Isotope and Radiation Industry Association, the Radiation Research and Application Branch of the Chinese Nuclear Society, and the Guangdong Packaging Technology Association

The 8th Youth Symposium on Total Synthesis of Natural Products of the Chinese Chemical Society……