Why pressure sensitive tape does not stick in winter?

The failure of pressure sensitive adhesive in extremely cold weather is mainly caused by interface failure. The main reason is that the adhesion between the pressure sensitive adhesive and the substrate is insufficient. Pressure sensitive adhesive with sufficient adhesion requires the following conditions:

Apply uniform pressure at the appropriate temperature to make the pressure sensitive adhesive realize effective contact with the adhesive surface, and then infiltrate the adhesive surface through molecular movement and achieve adhesion. At low temperature, the molecular movement of pressure-sensitive adhesive is slow and it is difficult to quickly infiltrate the adhesive surface. At the same time, the modulus of pressure-sensitive adhesive increases at low temperature. When the same pressure is applied, the adhesive deformation is smaller and the effective contact area is smaller than that at room temperature, which eventually leads to the lower bonding strength.

Provide a certain curing time to make the molecular chain of the pressure sensitive adhesive and the substrate surface close enough to establish the bonding strength. As a kind of polymer product, pressure sensitive adhesive requires sufficient time for its molecular movement, which generally requires curing at appropriate temperature for 72 hours.

Only in this way can the bonding strength between pressure sensitive adhesive and the adhesive surface develop from the weak initial strength to the final bonding strength, so as to achieve the ideal bonding effect. Temperature is also an important factor in this process and at low temperatures the molecules move slower and it takes longer to build up their strength.

Through field visits to customers, we found that many pressure-sensitive adhesive users were not prepared enough for cold weather, and the ambient temperature used for construction was much lower than our recommended temperature, which was the main reason for the failure of a large number of unconventional pressure-sensitive adhesives in winter.

In addition, the low ambient temperature in the storage or post-construction maintenance period of pressure-sensitive adhesives was also an important reason for the bonding failure. It is recommended to choose low temperature adhesive tape to complete the adhesive application in winter. The ability of these tapes to maintain molecular motion at lower temperatures ensures cryogenic performance.

In addition, it can also be improved from storage, construction and maintenance conditions to ensure the winter performance of pressure-sensitive adhesive products.

Storage conditions: low temperature storage will not only make the molecular movement is “frozen” can not be effectively infiltrated, but also will change it from a semi-solid to a brittle non-viscous glass state, resulting in the initial viscosity decline or even disappear. In addition. When the belt is moved directly from the low-temperature storage environment to the greenhouse, the surface is easy to condensation, which will cause the pressure sensitive adhesive release paper to be affected by moisture and fold, which will affect the normal use of the belt. In order to obtain the best performance of pressure-sensitive adhesive, it is recommended that pressure-sensitive adhesive tape be sealed in its original packaging and stored at 23℃ and 50% relative humidity. For rolled pressure-sensitive tape, place the roll core vertically to avoid adhesive overflow caused by local pressure on the tape. If multiple rolls are to be stacked, place the release paper between different rolls to prevent the sides of the rolls from sticking to each other. If the storage conditions cannot meet the above requirements, place the adhesive tape in the original package in the oven or near the heater for a period of time before use to ensure that the adhesive tape temperature is higher than the operating temperature recommended by the manufacturer.

Construction conditions: as far as possible to ensure that the construction environment temperature above 15℃, if necessary, can use the hot air gun and other local heating method. Take measures to warm the tape before use to ensure that the temperature of the tape and the attached position is higher than the recommended temperature. If construction must be carried out at low temperature due to technological conditions, low temperature pressure sensitive tape should be selected. For example, 525 product series can be carried out at 0℃ environment. For more severe application environment, it is recommended to use low-temperature adhesive tape at the same time to pretreat the adhesive surface to improve the affinity between the adhesive surface and the adhesive tape, and speed up the establishment of adhesive strength.

Curing conditions: The establishment process of bonding strength is related to temperature and time. The bonded parts need to be cured in the appropriate temperature environment for a certain period of time to reach the final strength. During this process, the bonded parts should be avoided to be placed in a low temperature environment or subjected to load too early. It is recommended to use fixtures to extend the pressure action time and cooperate with insulation measures to accelerate the strength establishment.