Frame Sealing & Structural Parts: Responding to Silicone Sealant Chalking and Water-Blocking Failure

Sealant is the last line of defense in the module's water-blocking system - when it fails, the entire module loses protection

I. Mechanism and path of sealant failure

Sealant ageing starts at the surface: UV across 280-400 nm breaks the silicone chain, then moisture and acid work inward.

Silicone sealant aging is a classic starts at the surface, progresses inward process:

1. UV-initiated chain scission: 280-400 nm UV breaks the siloxane backbone, first generating hydroxyl groups and low-molecular-weight siloxanes at the surface;
2. Oxidation and crosslinking together: the small fragments produced by scission react with air to form a network structure, appearing as a surface chalk layer (chalking);
3. Adhesion-interface degradation: the chalk layer thickens continuously and peel strength declines linearly;
4. Water-blocking failure: once adhesion is lost, moisture and ions penetrate along the interface, triggering corrosion and PID, and ultimately module failure.

II. Tiangang's liquid HALS solution

Compared with powder HALS, liquid HALS has clear advantages in silicone systems: it can be pre-blended directly into the silicone sealant base, disperses evenly, and does not settle or agglomerate in low-viscosity systems the way powders do.

III. Formulation matrix by part

Module frame sealants use UV-531 or UV-P together with the liquid HALS HS-508 in a silicone or MS adhesive.

IV. Tiangang's extended capabilities in coatings and weather resistance

Benzotriazoles (UV-326/UV-328) have lighter color and suit color-sensitive applications.

It should be noted that sealants and coatings are not exclusive to PV. Tiangang has mature positions in coatings, plastics, automotive, textiles, agricultural film and rotational molding, and the weather-resistance formulation experience accumulated in these fields transfers directly to PV sealing and coating steps.