Factors affecting the waterproof performance of lamps and lanterns
1. Ultraviolet rays
Ultraviolet radiation has a destructive effect on the insulation layer of wires, protective coating of shell, plastic parts, pouring sealant, sealing rubber ring and adhesive outside the lamp.
After the aging and cracked insulation layer of electric wires, water vapor will permeate into the interior of lamps through the cracks in the wire core. Lamp shell coating aging, shell edge coating cracking or peeling, cracks will appear. Plastic shell aging, deformation and cracking. Electronic potting colloid aging will produce cracking. Seal ring rubber strip aging deformation, there will be gaps. The adhesive between the structural parts is aging, and cracks will appear after the adhesive force is reduced. These are ultraviolet damage to the waterproof ability of lamps and lanterns.
2. High and low temperature
Outdoor temperature varies a lot every day. In summer, the surface temperature of lamps can rise to 50 ~ 60℃ in the daytime, and drop to 10 ~ 20 qC in the evening. Outdoor lamps in the summer under the high temperature environment, materials accelerated aging deformation. When temperatures drop below zero, plastic parts become brittle, crushed by ice or crack.
3. Expand with heat and contract with cold
Lamp shell thermal expansion and cold contraction: the change in temperature leads to the thermal expansion and cold contraction of lamps and lanterns, different materials (such as glass and aluminum profile) line expansion coefficient is different, the two materials in the joint will appear displacement. Thermal expansion and contraction process is repeated, and the relative displacement is repeated, which damages the air tightness of lamps and lanterns.
Internal air expansion and contraction: on the ground of the square, you can often observe the condensation of water droplets on the glass of the buried lamp. This is the result of respiration when heat expands and cold contracts.
4, about the structure waterproof
Structural waterproof lamps are only made of pure mechanical structure assembly, with simple tools, less assembly process and process, short assembly cycle, convenient and quick repair on the production line. Lamps can be packaged and shipped after passing the electrical performance and waterproof test, which is suitable for engineering projects with short supply cycle.
However, the machining requirements of structural waterproof design lamps are higher, and the dimensions of each part must be precisely matched. Only suitable materials and construction can ensure its waterproof performance.
5, about the material waterproof
For lamps designed with waterproof material, filling and sealing adhesive is used to insulate and waterproof, and sealing adhesive is used to bond the joints between closed structural parts, so that the electrical parts are completely airtight and waterproof outdoor lamps can be achieved.
6. Sealing glue
With the development of waterproof material technology, various types and brands of special potting adhesives for lamps keep appearing, for example, modified epoxy resin, modified polyurethane resin, modified silicone and so on. With different chemical formulations, the physical and chemical performance indexes of the potting adhesive, such as elasticity, molecular structure stability, adhesion, uV resistance, heat resistance, low temperature resistance, hydrophobicity and insulation performance, are different.