Analysis of advantages of silica gel for LED soft light strip

As an important member of the LED family, LED soft light strips are increasingly used in urban night beautification, building lighting and vehicle lighting. With the popularity of LED soft light strip, more and more manufacturers are faced with the problem of how to choose a suitable filling sealant for LED soft light strip.

At present, there are three systems of epoxy resin potting adhesive, polyurethane potting adhesive and silicone potting adhesive on the market. These three products have different characteristics. Epoxy resin potting adhesive is generally AB component packaging products with good light transmittance. Generally speaking, the light transmittance is between 85-92%; It has good stacking effect, and the appearance of the cured lamp strip is bright and round; It can be used at - 5 ℃ to 55 ℃; However, due to the low Tg point of the epoxy resin itself, it is easy to have poor toughness at high temperatures. In many cases, when the temperature exceeds 60 ℃, the soft light strip adhesive will soften and cause the gel to break easily; At the same time, when the temperature is lower than - 5 ℃, the colloid becomes hard and brittle, and the light bar shakes slightly, the phenomenon of colloid peeling and brittle fracture will occur; After the lamp bead has been lit for 400-700 hours for a long time, the epoxy resin colloid above the lamp bead becomes yellowish brown, resulting in the decrease of light brightness and the change of color temperature.

Polyurethane potting adhesive, also known as PU adhesive, is generally AB packaging product. The light transmittance of the cured lamp strip is 85-92%. The cured gel can be used for a long time between - 25 ℃ and 95 ℃; However, because the hardness of polyurethane gel cannot be very low, the product can only be used for drip type or semi sleeve type soft light strips. The flexibility of the light strip changes greatly with the decrease of temperature; High requirements for FPC surface and environmental humidity during potting. If the humidity is too high, the product surface is prone to white fog and insufficient adhesion; The colloid used outdoors for a long time usually turns yellow after 2-3 years.

The silicone potting adhesive is generally single component or AB component, and the light transmittance of packaged products is generally 84-92%. After curing, the hardness of the gel can be adjusted. It can be made into either jelly type gel or shore A30 degree hard adhesive. Therefore, the silicone potting adhesive can be used not only for drip type lamp strips, but also for semi sleeve type lamp strips. It can also be used for the whole sleeve type lamp strips. After curing, the gel can be used between - 45 ℃ and 200 ℃ and changes with temperature The mechanical and physical properties and optical properties will not change significantly. It is very suitable for use in cold regions such as Russia, Northern Europe and North America; Organic silicone potting adhesive lamp strip has good ozone, ultraviolet, acid and alkali resistance, and can be used outdoors to keep from yellowing for a long time; However, silicone potting adhesive also has some defects, such as its adhesion to FPC is lower than that of epoxy resin.

From the perspective of market development, the trend of silicone potting adhesive to replace other products is becoming increasingly obvious. If it is necessary to use silicone potting adhesive for lamp strips in harsh environments, silicone potting adhesive must be used.