To enhance the surface gloss and texture of a vinyl naughty milk dragon ornament, a multi-step surface treatment process is needed, considering both the material's properties and the ornament's functional requirements. Vinyl, as a thermoplastic resin, is flexible, chemically resistant, and easy to process, but its surface energy is low, making direct coating prone to insufficient adhesion and uneven gloss. Therefore, surface treatment needs a systematic design encompassing cleaning, roughening, modification, coating, and curing to create a dense, uniform, and high-gloss coating.
Surface cleaning is fundamental to enhancing gloss and texture. During production, vinyl ornaments may contain residual mold release agents, fingerprints, or dust. These contaminants can hinder the adhesion between the coating and the substrate, leading to localized dullness or coating peeling. Cleaning should be done with a neutral detergent and a soft brush, avoiding strong acid or alkali solutions to prevent surface corrosion. After cleaning, rinse thoroughly with pure water and dry completely to ensure no moisture residue, providing a clean base for subsequent treatments.
Roughening enhances coating adhesion. The smooth surface of vinyl makes direct coating prone to peeling due to insufficient mechanical adhesion. Sandblasting or sanding increases surface roughness, creating a microscopic textured structure. For sandblasting, fine-grained alumina or glass beads should be used to avoid over-roughening and damaging the details of the piece. Sanding requires careful control of the pressure, removing only the surface gloss layer without damaging the main structure. After roughening, compressed air should be used to remove surface dust to prevent particles from embedding in the coating.
Flame treatment is a crucial step in enhancing the polarity of vinyl surfaces. Vinyl is a non-polar material with poor compatibility with polar coatings. Flame treatment uses high-temperature oxidation to generate polar groups on the surface, increasing surface energy and thus improving coating adhesion. During treatment, the flame temperature and distance must be controlled to avoid melting and deformation of the material. Typically, a blue flame is briefly swept across the surface, causing a slight whitening. Coating should be applied immediately after flame treatment to prevent the polar groups from re-passivating due to environmental factors.
Primer application seals surface micropores and enhances interlayer bonding. A specialized primer with good compatibility with vinyl, such as chlorinated polypropylene or polyurethane primers, should be used to evenly cover the surface by spraying or brushing. The primer must possess high adhesion and flexibility to accommodate potential deformations of the object. After application, it should be left to stand in a dry environment to allow the solvents to fully evaporate, forming a dense primer layer that provides a smooth base for the topcoat.
The topcoat application is the core step in determining the gloss and texture. A high-gloss acrylic or polyurethane topcoat should be selected, and uniform coverage should be achieved through electrostatic spraying or air spraying. During spraying, ambient humidity and temperature must be controlled to avoid sagging or orange peel effects. The topcoat must possess excellent weather resistance and abrasion resistance to withstand friction and UV exposure during daily use. After application, the surface should be inspected for particles or pinholes, and local repairs should be made as necessary to ensure overall uniform gloss.
The curing process can improve the coating's hardness and gloss stability. Vinyl object coatings are typically cured using either thermosetting or UV curing. Thermosetting requires staged heating in an oven to completely evaporate the solvents and fully cross-link the resin; UV curing requires the use of UV-curable coatings, achieving rapid curing through high-intensity UV radiation. After curing, allow it to cool naturally to room temperature to prevent cracking due to sudden temperature changes.
Post-treatment can further enhance the gloss and texture. For highly demanding ornaments, polishing can be performed after curing. A high-speed rotating polishing wheel combined with polishing compound can remove minor surface imperfections, creating a mirror-like effect. Polishing requires careful control of pressure and time to avoid excessive wear on the coating. Additionally, a thin layer of silicone oil or wax can be sprayed onto the coating surface to enhance gloss durability while providing fingerprint resistance and easy cleaning. Through a systematic surface treatment process, the vinyl naughty milk dragon ornament achieves a high-gloss, wear-resistant finish, meeting the dual needs of decorative items for both aesthetics and practicality.
