Paint is a type of liquid or solid material that can form a thin film under certain conditions to protect, decorate or perform other special functions (insulation, rust prevention, mold resistance, heat resistance, etc.) when applied to the surface of an object. Most of the early paints were made of vegetable oil as the main raw material, so they were also called paints. Now synthetic resins have mostly or completely replaced vegetable oils.
There are many ways to classify paints, and they are divided into water-based paints, solvent-based paints, powder paints, high solids paints, etc. according to their forms.
The cleavage-type photoinitiator, i.e., the I-type photoinitiator, means that after the initiator molecule absorbs light energy, it transitions to an excited singlet state, and then jumps to an excited triplet state through intersystems. In its excited singlet state or triplet state, the molecular structure is In an unstable state, the weak bonds in it will be homogenized and primary active free radicals will be generated, thereby initiating the polymerization of vinyl monomers. The structure of this type of photoinitiator is mostly based on aryl alkyl ketone compounds, and the photochemical process is mostly a single-molecule mechanism, unless a photosensitizer is used.
Cleavage-type free radical photoinitiators are mostly aryl alkyl ketone derivatives, basf micronized wax and representative ones include benzoin derivatives, benzil ketal derivatives, dialkoxy acetophenone, a-hydroxyl Alkyl phenones, c-amino alkyl phenones, acyl phosphine oxides, esterified oxime ketone compounds, aryl peroxy ester compounds, halogenated methyl aryl ketones, organic sulfur compounds, benzoyl formate, etc.
1. Benzoin and its derivatives
It mainly includes benzoin ether derivatives, with common structures such as formula (7-2).
HR=H, -CHy, -CH, CHa, -CH(CH)) a,
-C–CHyCHzCH: CH, one CH, CH(CH;) z, (7-2)
OORCH, -OC OCH,
Benzoin, commonly known as benzoin, was once a mainstream photoinitiator commercialized earlier. It was widely used in the 1970s and 1980s, and benzoin isopropyl ether is more commonly used . This type of photoinitiator is 300~ 400nm has strong absorption, and the maximum absorption wavelength is generally above 320nm. Benzoin ether has a fast photoreaction and is seldom affected by other components in the formulation. It is suitable for photo-initiated polymerization of monomers with strong quenching properties, such as styrene.
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