All About the Insulating Glass Sealants

Glass using sealant is different from insulating glass sealants. Glass using sealant usually refers to the ordinary silicone sealant.

Insulating glass sealants could usually be divided into two types: hot melt type and chemical curing type. Hot-melt sealants are usually butyl hot-melt sealants, and chemical-cure sealants are usually polysulfide sealants, silicone sealants, and polyurethane sealants. Generally speaking, butyl hot-melt sealant is mostly used for the first seal of insulating glass, and chemical curing adhesives such as polysulfide and silicone are mainly used for the second seal of insulating glass.

Generally speaking, the secondary sealant of insulating glass is made of silicone sealant or polysulfide sealant, which should have:

(1) It has a certain bonding strength and elasticity, enough to withstand the deflection and deformation of the insulating glass due to the air pressure difference, and prevent the deformation of the insulating glass from exceeding the displacement tolerance of the butyl sealant.

(2) It has good air tightness and aging resistance, which ensures that the insulating glass has a long service life.

(3) Polysulfur insulating glass sealant or silicone sealant is used for the secondary sealant of the exposed frame glass curtain wall; silicone structural sealant is used for the secondary sealant of the hidden frame, semi-hidden frame, and point-supported glass curtain wall.

The most commonly used secondary sealants for insulating glass are polysulfide sealant and silicone sealant.

Polysulfide sealant is an elastic sealant prepared from liquid polysulfide sealant as the base polymer and adding curing agent and additives. It has good air tightness and is mainly used for sealing framed insulating glass, such as insulating glass for doors, windows, and exposed frame curtain walls.

Silicone sealant is an elastic sealant prepared by adding liquid silicone sealant as the base polymer and adding curing agents and additives. It has excellent weather resistance and aging resistance. According to the packaging form, it is divided into one-component silicone sealant and two-component silicone sealant. Divided into silicone structural sealant and silicone sealant by application. Silicone structural sealant is mainly used for the structural assembly of curtain walls and sealing of hidden frames, semi-hidden frames, and point-supported glass curtain wall insulating glass; silicone sealant is mainly used for sealing of framed insulating glass, such as insulating glass for doors, windows, and exposed frame curtain wall.

Insulating glass polysulfide sealant and silicone sealant are selected according to their different characteristics, and there is no better way to say.

Polysulfide sealant and silicone sealant have their advantages and disadvantages. The advantages of polysulfide sealant are good air tightness, excellent oil resistance, solvent resistance, and water resistance; the disadvantage is poor UV resistance. The advantage of silicone sealant is that it has high strength and excellent weather resistance and aging resistance; the disadvantage is that it has a high water vapor transmission rate and poor oil resistance. When selecting the sealant, it should be selected according to the location where the sealant is used and the characteristics of the material. If used for structural assembly of curtain wall and a insulating glass of the hidden frame, semi-hidden frame, and point-supported glass curtain wall, silicone structural sealant must be selected; framed insulating glass (such as doors and windows, exposed frame glass curtain wall, etc.) should use polysulfide sealant and silicone sealant can also be used.

Silicone adhesive is divided into silicone sealant and silicone structural adhesive. Silicone structural sealant is mainly used for the structural assembly of glass curtain walls and sealing of hidden frame, semi-hidden frame, and point-supported glass curtain wall insulating glass; silicone sealant is mainly used for sealing framed insulating glass, such as insulating glass for doors, windows, and exposed frame curtain walls.

Because the open frame curtain wall has a frame to fix the glass, sunlight (ultraviolet rays) will not irradiate the surface of the sealant. In addition, compared with silicone sealant, polysulfide sealant has lower water and air tightness. Therefore, polysulfide sealant should be preferred for open glass in the open frame curtain wall, and silicone sealant can also be used. If silicone sealant is used, under the same service life conditions, the bonding width of silicone sealant should be appropriately increased.

If one of the sealants is completely cured, it is okay to use another sealant. If one of the sealants is not cured, it is not possible to use the other sealant. The weather-resistant sealant for construction is incompatible with the polysulfide sealant before curing. If the two sealants are not fully cured and contact each other, one will affect the curing and the other will affect the adhesion.