To determine whether
Polyurethane Adhesive is fully cured, it can be judged comprehensively from four aspects: appearance, feel, performance, and environmental conditions. Avoid making a wrong judgment by only looking at the surface drying.
1.Appearance judgment
The surface of a fully cured adhesive layer is uniform, smooth, not sticky, not shiny, with stable color, no whitening, bubbling or delamination. When not fully cured, the surface is prone to stickiness, moisture absorption, and stickiness, and the edges are prone to wrinkling.
2.Hand feel and finger touch method
Using a clean finger to gently press the adhesive layer, if the finger does not stick, leaves no fingerprints, and the pressing does not cause obvious indentation and rebound, it indicates that the surface has cured; for deep curing, it needs to be judged in combination with time and thickness. The thicker the adhesive layer, the longer the curing time.
3.Bending and peeling test
Gently bend the bonded part, the adhesive layer does not break, does not turn white, does not peel off, and has toughness without cracking. When slightly peeling, the interface bonding is firm, without wire pulling, and no un-cured adhesive is pulled out, which can be considered as fully cured.
4.Judging based on curing conditions
Single-component moisture curing depends on the moisture in the air. When the temperature is low, humidity is small, and the adhesive layer is thick, the curing is slow. For two-component, it needs to be mixed thoroughly according to the ratio. If not mixed evenly or the ratio is incorrect, it will cause local long-term non-curing. Only when the curing time meets the process requirements and the environment meets the temperature and humidity requirements can it be judged as fully cured.
5.Auxiliary simple judgment
Using a knife to lightly scratch the adhesive layer, if the internal texture is uniform, without softness, no sticking to the knife phenomenon, the cross-section is dense without air holes, it is fully cured. If the internal part is still soft, sticky, or has fluidity, it is not fully cured.
