Abstract
Using organic coatings helps to protect PET (polyethylene terephthalates) surfaces, improve surface hardness, scratch resistance, and solvent resistance, prolong the service life of PET film, and to expand their scope of applications. There were some disadvantages, including poor flexibility and impact resistance in high-hardness coatings; organic coatings should also be modified to improve the toughness. Herein, a UV (ultraviolet curing) curable high-hardness organic coating used in PET surface protection was prepared and modified with inorganic nanoparticles, such as OVPOSS (octavinyl-polyhedral oligomeric silsesquioxane). The effects of the categories of nanoparticles on the coating performance were studied. UV-Vis spectra (ultraviolet visible light spectra), FT-IR (Fourier transform infrared spectrometer), TGA (thermogravimetric analysis), DMA (dynamic-mechanical), SEM (field emission scanning electron microscope), and AFM (atomic force microscope) were used to characterize the properties of the coatings. The results showed that the addition of eight-vinyl POSS to the organic coating significantly increased its glass transition temperature (Tg) from 100 to 120 °C, improved its storage modulus from 167.6 to 258.9 MPa, and raised its impact resistance and flexibility. The SEM and AFM images displayed that the eight-vinyl POSS particles were dispersed homogeneously in the coating, arranged in an ordered network, and had good compatibility with organic components. The film displayed excellent properties, including 4 H of the pencil hardness, 100 g cm of impact resistance, excellent flexibility, and 90% of light transmittance, with the addition of 0.3 wt % OVPOSS. TGA analysis revealed that the coating had good thermal stability, with 5% weight loss temperature up to 335 °C.
Highlights
Polyethylene terephthalate (PET) film has been widely used in packaging decoration, screen protection, and optical grade mirror surface protection due to its excellent light transmission, heat resistance, toughness, and insulation [1]
A UV-curable high-hardness organic coating used in PET surface protection was prepared and modified with nanoparticles
The results indicated that the coated PET film displays excellent properties, including 4 H of the pencil hardness, good impact resistance, excellent flexibility, and high light transmittance, with the addition of 0.3 wt % octavinyl-polyhedral oligomeric silsesquioxane (OVPOSS) [17,18]
Summary
Polyethylene terephthalate (PET) film has been widely used in packaging decoration, screen protection, and optical grade mirror surface protection due to its excellent light transmission, heat resistance, toughness, and insulation [1]. The use of solvent-free, high solid coatings with very low VOC (volatile organic compound) emissions permits to meet the increasingly stringent legal regulations in the industry. These coatings include UV-curable coatings that have low VOC contents, and provide products of superior finished properties, such as gloss, durability, or abrasion resistance. The results indicated that the coated PET film displays excellent properties, including 4 H of the pencil hardness, good impact resistance, excellent flexibility, and high light transmittance, with the addition of 0.3 wt % OVPOSS [17,18]
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