1. The influence of temperature
The tackiness of pressure-sensitive adhesive tapes is mainly produced by adhesives. Adhesive (refers to the adhesive that has been made into tape, the same below) is a semi-fluid. There are irregular molecular motions (ie Brownian motion) inside. The temperature rises, the intermolecular force decreases, and the Brownian motion strengthens. The wetting and penetration of the sticky object is easy, and the stickiness is better; at the same time, the temperature rises, the surface molecules of the sticky object gain energy and move actively, and the binding force with the adhesive molecules is strengthened, and the sticking is firm. This is our common temperature when the temperature is high. The reason for the good adhesiveness of the tape. But when the temperature is higher than a certain limit, the force between the adhesive molecules will decrease too much, and the molecules will easily lose their “binding”, which will cause the phenomenon of “high temperature flow glue”. Conversely, when the temperature is lowered, the external energy of the adhesive molecules decreases, the Brownian motion of the adhesive molecules decreases, the “introverted force” of the adhesive increases, and when the temperature decreases, the activity of the molecules of the adhered object decreases, and the adhesive molecules and the adhered object molecules are separated. The van der Waals force decreases and the adhesiveness of the tape decreases; when the temperature drops to the glass transition temperature of the adhesive, the adhesiveness of the tape will lose, which is the phenomenon of “low temperature loss of adhesion”.
In addition, as the temperature increases, the thermal creep of the adhesive increases, which can also be broadly understood as melting of the adhesive. At the same time, the increase in temperature will accelerate the aging of the adhesive and reduce the viscosity of the adhesive.
2. The influence of humidity
The suitable humidity for the pressure-sensitive adhesive tape is about 55%~80%RH. When it is greater than 80% (such as during the rainy season), the tape (especially water glue) contains a small amount of solvent or moisture that is not easy to dissipate, which covers part of the adhesive tape. Adhesive, the surface of the adhered object will also absorb water to form a weak interface, which reduces the adhesive effect of the tape. When the relative humidity is lower than 55% (such as dry and cold in winter), the adhesive and the adhered object are too dry, which will hinder the wetting and penetration of the adhesive; when the humidity is reduced, the dust concentration in the air will increase, and it is easy to produce a weak interface when sticking. , Affect the adhesive to exert its viscosity. Therefore, whether the humidity is too high or too low, the adhesive will reduce the viscosity.