Which kind of sealant are your best choice for windows and doors caulking?

    Structural adhesive focuses on bond strength, mainly used in the bond position of curtain wall glass and profiles, as well as the bond of sunlight roof glass, 

and the bond strength of structural adhesive can replace welding to a certain extent.

    The doors and Windows are mainly based on the use of sealant and weather resistant sealant, and deal with the wind and rain at the joints and switch 

vibration and other doors and Windows displacement. This requires a sealant with strong weather resistance and strong displacement resistance that can 

cope with various expansion changes at the joint without tearing the wall and door and window paint at the bonding point. At the same time, good silicone 

adhesive will maintain its shape at 204°C after full curing, and will not become sticky.

1. Displacement capacity and modulus

   
   

The higher the displacement capacity of the sealant, the better the elasticity, and the anti-displacement capacity of the door and window installation 

should be a product above 12.5, so as to ensure that the joint is always sealed when it is displaced. At present, the displacement capacity is

 divided into five levels: 35, 25, 20, 12.5 and 7.5.

At the same time, according to the tensile modulus, it can be divided into high modulus (HM) and low modulus (LM) two levels.

Tensile modulus of high modulus: (MPa) > 0.4 or > 0.6

Tensile modulus of low modulus: (MPa) ≤0.4 or ≤0.

Low modulus sealant and high modulus sealant are very different, if the modulus of the sealant is too high in the joint deformation, the sealant

 is easy to occur in the wall and frame paint adhesive damage, because the tensile strength is greatly greater than the interface strength. 

The sealant is a low modulus, its tensile strength is very low, in the joint displacement deformation, because its tensile strength is lower than

 the interface bond strength, there will be no bond damage at the interface position, so we choose the sealant in the door and window seam when 

we find that the wall interface is relatively fluffy (cement mortar, steam gas block, etc.) or recommend the use of low mold sealant, At the same time, 

the low mold sealant can effectively avoid the problem of sealant cracking caused by the increase of internal stress. At present, only a few foreign companies 

can produce, most of us are also highly customized, and there are not many in circulation on the market