Foam double-sided tape has special viscoelasticity, which produces viscosity under the action of external force, so as to achieve close contact with the adhered object, and wet and penetrate the surface of the adhered object. The adhesive molecule and the adherend molecule are close to 5 ×10～10m, form a paste. From this we can see that there are two elements for the adhesive to exert its adhesive force: the viscoelasticity of the adhesive and the action of external force. The viscoelasticity of the double-sided foam tape is mainly related to the type and formula of the adhesive elastomer. It is the main and internal element. The external force includes the use environment (temperature, humidity) of the double-sided foam tape, bonding method and bonding size , The material of the adhered object and its surface cleanliness, surface shape, etc., are external influencing factors. Only the influence of temperature and humidity on the use of double-sided foam tape is discussed here.
1. The influence of temperature The viscosity of double-sided foam tape is mainly produced by the adhesive. Adhesive (refers to the adhesive that has been made into double-sided foam tape, the same below) is a semi-fluid, with irregular molecular motion (ie Brownian motion) inside, the temperature rises, the intermolecular force decreases, and the Brownian motion Strengthen, the wetting and penetration of the adhered object is easy, and the viscosity is good; at the same time, the temperature rises, the surface molecules of the adhered object gain energy and move actively, and the bonding force with the adhesive molecules is strengthened, and the sticking is firm. This is what we are common When the temperature is high, the foam double-sided adhesive has good adhesion. 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 decreases, 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 strength of the foam is reduced, and the adhesiveness of the foam double-sided adhesive decreases; when the temperature drops to the glass transition temperature of the adhesive, the double-sided foam adhesive will lose its viscosity, which is the phenomenon of “low temperature loss of adhesion”. In addition, as the temperature rises, 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 foam double-sided adhesive.
2. The influence of humidity. The suitable humidity for double-sided foam tape is about 55%~80%RH. When it is greater than 80% (such as during the rainy season), the double-sided foam tape (especially water glue) contains a small amount of solvent or moisture. Disperse, cover the stickiness of part of the adhesive tape, and the surface of the sticky object will also absorb water to form a weak interface, which reduces the sticky effect of the foam double-sided 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.
The main feature of the weather in autumn and winter is that the air is dry and the temperature is significantly lower. From the foregoing analysis, we know that the use of foam glue this season will feel less sticky and more difficult to stick. It requires production and sales to work hard at the same time to overcome the adverse effects of seasonal changes on the use of foam double-sided tape.
1. The factory should adjust the adhesive formula in time according to seasonal changes. This is a proactive measure.
2. Sales personnel should understand the adverse effects of seasonal changes on the use of double-sided foam tape, promptly make publicity and explanations to customers, and assist customers in improving the environmental conditions of production and storage, such as heating and humidification, etc. , In order to facilitate the normal performance of the foam double-sided tape.