Matte UV formulas have higher requirements for UV light transparency.
UV light transparency is the prerequisite for UV curing. UV resins or matte coatings and inks without transparency do not have good photoactivity. This is different from traditional matte products, especially LED curing, which is the basic premise.
Matte UV formula is not allowed to add wax paste or silicone.
There are strict requirements for the amount of matt powder added to the formula. It is not just a matter of thickening if too much is added. Matt powder has an inflection point in the UV formula. If too much is added, it will only act as a filler and thickener. It will no longer have a matting effect. Instead, it will affect the curing due to poor dispersion, resulting in a series of problems such as scratch resistance, powdering, white spots, and softening, not to mention hardness, wear resistance, water resistance, and chemical resistance.
This inflection point is usually 10-15%. If matte powder is directly added for dispersion, the UV system can only produce a semi-matte product, not a fully matte product. This is also related to the glossiness of the substrate. Directly adding matte powder can usually only reduce the matte to half of the substrate, otherwise there will be problems. If wax slurry or silicone is added, more serious problems will occur, such as oil floating after curing, poor curing, softening, no recoating, and no hot stamping. Therefore, it is forbidden to add wax slurry or silicone to the UV matte formula, which is a completely different design principle from traditional products.
Matte UV formula powder or pigment, dye combination needs to have synergistic matting properties. UV matte production still relies on the diffuse reflection principle of matte powder. However, due to the need for UV permeability curing, it leads to excessive transmission and reflection of light and lack of light absorbing components, resulting in a different design principle of matte from traditional products.
The main consideration is the high photosensitivity of the resin. It must have deep and deep-level curing capabilities and be able to have a certain degree of photon stability and synergistic photosensitization. Secondly, it is necessary to add enough light-absorbing components as much as possible to reduce the amount of reflection, make the formula as transparent and transmissive as possible for curing, stabilize photons, diffusely reflect and extinct, and absorb non-curing light as much as possible. Therefore, when choosing powders or pigments and dyes, it is necessary to fully consider their dispersibility, stability, anti-settling properties, light transmittance, visible light absorption ability, and fully consider the synergistic extinction of inorganic fillers. At present, tests have found that powders below 3000 mesh have no light permeability and are not conducive to UV curing, while powders above 6000 mesh have good permeability, but many powders will cause the product to turn white in a liquid state. This is okay, as long as there is no precipitation, no stratification, and it is transparent after curing.
This is because most powders tend to form a colloidal state after being mixed with matte resin, especially powders that are easy to absorb water. The amount of synergistic powder added is usually 3-10%. The main powders that can be used are as follows, and their functions are as follows: 6000 mesh talcum powder synergistic matting and permeability, with a certain anti-settling synergistic effect. 6000 mesh calcined kaolin synergistic matting, with good hiding power. 6000 mesh barium sulfate synergistic matting, with good hiding power and comprehensiveness. 3000 mesh and above ATH (aluminum hydroxide) synergistic matting, but it is easy to appear white in the liquid state, fire retardant, good anti-settling properties, good permeability after curing, good hiding power, and good synergistic whitening effect. 8000 mesh quartz powder synergistic matting, with good wear resistance. 3000 mesh and above ceramic powder synergistic matting, with good wear resistance, but poor permeability, small dosage. Usually, only synergistic matting is used, mainly talcum powder, followed by other powders added according to function, and the total amount is controlled at 3-10%.