Polybutyl as edge sealant: application, advantages and disadvantages

 Polybutyl (PB-1) is a polyolefin or saturated polymer which is used as edge sealant in solar PV modules

Edge sealant in Solar PV

Edge sealant is used for thin film and crystalline silicon PV modules. It helps in delaying moisture ingress, which protects cells, connections, and conductive oxide coatings from corrosion and degradation. Edge sealants also strengthens the electrical isolation for PV modules. The many advances in sealing systems help PV  manufacturers in finding ways to reduce costs and improve the protections of cells.Edge sealants are required to provide the following:
  • Very low MVTR (moisture vapor transmission rate)
  • Reliable bonding throughout a range of temperatures and conditions
  • Easy manufacturing process
  • UV temperature degradation resistance
  • Good adhesion properties.

Polybutyl as edge sealant

Polybutylene is a polyolefin which combines typical polyolefins characteristics with certain technical polymers properties. PB-1, can be applied as a pure reinforced resin, or as a blend element to improve the characteristics of other polyolefins like polypropylene. It is used in different applications, mainly flexible packaging, pressure piping and hot melt adhesives.It is used in adhesives as it is compatible with a wide range of resins and offers high adhesive and cohesive strength and helps tailor the adhesion time because of the slow crystallisation kinetics. The Polybutyl also helps improve both the thermal stability and the viscosity of the adhesive.Polybutyl as a material has many advantages that make manufacturers prefer it as an edge sealant material. These properties include having good mechanical properties, flexible, good impact resistance and elastic recovery. It also has good chemicals resistance. It is also environmentally friendly as it has been used in heat applications for more than 30 years.

Advantages of using Polybutyl as an edge sealant

For edge sealant applications, Polybutyl has many advantages like low-lamination temperature, excellent moisture insulation properties, good adhesion to most surfaces, weather and chemical resistance, good flow properties. It also forms an elastic and tight skin which can be capable of operation in different outdoor conditions.The main concern for Polybutyl as an edge sealant over long term operation would be delamination edge as when Polybutyl sealant becomes damp, it loses the ability to adhere, which can cause premature failure of the unit.
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