Solar panels why EVA film?What is a contraction?
Release date:2016-07-07 08:57 source:http://www.hzxz88.com Views:
Why do solar panels need EVA film?
1, curing conditions: fast type of film, heating to 135 ~ 135 ℃, temperature 15 ~ 20 min;Conventional type of film, heated to 145 ℃, the constant temperature for 30 min.
2, light transmittance: more than 90%.
3, crosslinking degree: fast type of film is more than 70%, the conventional type of film is more than 75%.
4, peel strength: glass/film is more than 30 n/cm, TPT/film is larger than 20 n/cm.
5, temperature resistance, high temperature 85 ℃, 40 ℃, low temperature - do not heat bilges cold shrink, good dimensional stability.
6, ultraviolet aging resistance, long time of ultraviolet irradiation not crack, not aging.
Why there will be a piece of film contraction in EVA film packaging?Usually, piece of membrane shrank from the EVA film packaging reasons mainly include the following aspects:
1, the die head draw ratio
Mouth mold flow velocity and the ratio of the traction speed, draw ratio, generally defined as the die for the expansion of the mold situation this way of calculation is not accurate.For EVA film production, due to the cold extrusion characteristics, expands the mold tall 4-5 times, so the computation should be expansion after the mold piece of the maximum thickness calculation of the embryo tensile condition.
2, the temperature of the embryo
High temperature in the embryo, embryo when being die drawing of relaxation time is short, it is not easy to form too cold drawn, the shrink film will get very good control of press roll and stretch film roll speed difference
3, the size of the pool
Large molten pool is equivalent to increase pressure roll and stretch film roll diameter, thus change speed difference, thus lead to a larger shrinkage;
4, press roller temperature
High temperature to melt is flabby, can reduce shrinkage, but high temperature can cause sticking, so should be on the premise of not sticky roller and improve the temperature as much as possible.
5, the line speed
At a lower rate if EVA film production line, will be conducive to shrinkage stress relaxation, low-speed production can get smaller shrinkage rate, this is one of the reasons for the current domestic production line speed slow
6, traction tension
Traction tension is film production in the process of winding and trimming operations such as the necessary requirements, but too much traction tension caused by the tensile deformation of the diaphragm, increase the contraction.Therefore, in the production line design must get low tension winding and trimming function.
7, annealing treatment
Add effective annealing unit in production line, can effectively reduce the shrinkage of the diaphragm, but need to form a proper annealing process.