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Tri-functional acrylate diluent

Release time:

2024-09-10 23:31

Tri-functional acrylate diluent
Tri-functional acrylate diluent

Tri-functional acrylate diluents, as the name suggests, are compounds in which each molecule contains three acrylate functional groups. These diluents not only serve as diluents but also participate in the curing process, becoming an integral part of the cured film and thereby enhancing the crosslinking density and performance of the cured film. They typically exhibit characteristics such as low viscosity, high reactivity, and rapid curing.

Tri-functional acrylate reactive diluents typically exhibit excellent performance. Pentaerythritol triacrylate (PET3A) and trimethylolpropane triacrylate (TMPTA) are two of the most widely used tri-functional reactive diluents in the UV-curing industry.

I. Pentaerythritol Triacrylate (PET3A)

Pentaerythritol triacrylate, also known as a pure monomer, is a common trifunctional acrylate compound. Pentaerythritol triacrylate is typically obtained through the esterification reaction between pentaerythritol and acrylic acid. It has a low odor and appears as a colorless or pale yellow, transparent liquid. It is insoluble in water but exhibits excellent solubility and is miscible with other organic solvents. Pentaerythritol triacrylate is relatively stable at room temperature; however, care must be taken due to its flammable and explosive nature.

The PET3A molecule contains three acrylate functional groups and one side-chain hydroxyl group, which endow it with high reactivity. As a result, it can undergo copolymerization with other monomers—such as polyethylene glycol diacrylate—via free-radical polymerization or Michael addition reactions, forming crosslinked polymer networks with outstanding physical properties. In addition to the three acrylate functional groups, the PET3A molecule also features a side-chain hydroxyl group. This hydroxyl group not only enhances the molecular polarity and reduces volatility but also serves as a reactive site, enabling PET3A to be grafted onto other materials through grafting techniques, thus making it suitable for the preparation of composite materials. The molecular structure of PET3A is relatively complex; its spatial configuration allows it to form a dense and stable crosslinked network during polymerization, thereby imparting excellent physical properties to the cured film.

2,3-Butanediol triacrylate (TMPTA)

Trimethylolpropane triacrylate, also known as trimethylolpropane triacrylate ester or di(2-acryloyl)-2-ethyl-2-(acryloylmethoxy)-1,3-propanediol ester, is a low-odor, colorless to pale yellow, transparent liquid. It is almost insoluble in water but soluble in common solvents such as methanol. It is stable under normal temperature and pressure, but should be kept away from contact with oxides, light, heat, freezing, ultraviolet radiation, and inert gases.

The TMPTA molecule consists of an acrylate group and a hydroxymethylpropane backbone. The backbone of TMPTA is made up of hydroxymethylpropane, a propane derivative bearing three hydroxyl groups. The presence of these hydroxyl groups not only increases the polarity of TMPTA but also provides it with reactive sites for interaction with other compounds. Meanwhile, the three acrylate groups are linked to the three hydroxyl groups of hydroxymethylpropane via ester bonds.

Due to the highly reactive acrylate group contained in the TMPTA molecule, it exhibits strong reactivity. Under the influence of light, heat, or an initiator, TMPTA can rapidly participate in chemical reactions such as free-radical polymerization and crosslinking, yielding polymeric materials with outstanding performance.

III. Conclusion

Tri-functional acrylate reactive diluents play a crucial role in UV-curing and other radiation-curing systems thanks to their outstanding curing speed, high hardness of the cured products, and low volatility. These diluents are primarily used to finely control the rate of the curing process, significantly enhance the hardness of the dried coating film, and greatly improve the scratch resistance of the coating. Among them, pentaerythritol triacrylate (PET3A) and trimethylolpropane triacrylate (TMPTA) stand out as top performers in this category and are widely adopted by the UV-curing industry, with applications spanning multiple key sectors.

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