The temperature drops, the temperature difference between day and night is large, and the air becomes dry. During the construction of high quality SILICONE STRUCTURAL SEALANT products in winter, the curing speed and bonding speed of sealant will be affected by the low temperature and humidity of the environment.

1. The curing speed of high quality SILICONE STRUCTURAL SEALANT products is slow

The first problem caused by the sudden drop of ambient temperature to high quality SILICONE STRUCTURAL SEALANT products is that the curing is slow in the application process. The curing process of high quality SILICONE STRUCTURAL SEALANT products is a chemical reaction process, and the ambient temperature and humidity have certain effects on its curing speed. For one component high quality SILICONE STRUCTURAL SEALANT products, the higher the temperature and humidity, the faster the curing speed will be. The curing reaction of structural sealant is affected due to the sudden drop of temperature in winter and low humidity, so the curing of structural sealant is slow. In general, when the temperature is lower than 15 ℃, the curing of structural sealant becomes slower.

Solution: If the user wants to work in a low temperature environment, it is recommended to carry out a small area sealant application test and a peel adhesion test before use to confirm that high quality SILICONE STRUCTURAL SEALANT products can be cured, well bonded, and has no appearance problems before large-scale use. However, when the ambient temperature is lower than 4 ℃, the construction of high quality SILICONE STRUCTURAL SEALANT products is not recommended. If the sealant is applied in a factory where conditions permit, it can be considered to improve the temperature and humidity of the environment where high quality SILICONE STRUCTURAL SEALANT products is used.

2. Bonding of high quality SILICONE STRUCTURAL SEALANT products

With the decrease of temperature and humidity, the problem of adhesion between high quality SILICONE STRUCTURAL SEALANT products and substrate is accompanied by slow curing. The general requirements for the use environment of high quality SILICONE STRUCTURAL SEALANT products are: a clean environment with a temperature of - 5 ℃~45 ℃ and a relative humidity of 40%~80%. If the above minimum temperature requirements are exceeded, the bonding speed will be slowed down and the time for complete bonding with the substrate will be extended. At the same time, when the temperature is too low, the wettability of the adhesive and the substrate surface will be reduced, and there may be imperceptible fog or frost on the substrate surface, which will affect the adhesion of high quality SILICONE STRUCTURAL SEALANT products and the substrate.

Solution: When the temperature is 4 ℃ lower than the minimum construction temperature of high quality SILICONE STRUCTURAL SEALANT products, the adhesive test shall be carried out for the bonding substrate of high quality SILICONE STRUCTURAL SEALANT products under the actual low temperature construction environment, and the construction shall be carried out after the bonding is confirmed to be good. Factory injection of structural sealant can also speed up the curing of high quality SILICONE STRUCTURAL SEALANT products by increasing the temperature and humidity of the environment where the structural sealant is used, and at the same time, the curing time should be appropriately extended.

3. Thickening of high quality SILICONE STRUCTURAL SEALANT products

As the temperature decreases, the high quality SILICONE STRUCTURAL SEALANT products will become thicker and less fluid. For two-component silicone structural sealant, the thickening of high quality SILICONE STRUCTURAL SEALANT products will increase the pressure of the sealant beater and reduce the extrusion of high quality SILICONE STRUCTURAL SEALANT products. For the single component silicone structural sealant, the structural sealant thickens, and the pressure of the glue gun extruding the structural sealant increases, so manual operation may be time-consuming and laborious.

Solution: If there is no impact on the construction efficiency, low temperature thickening is a normal phenomenon, and no improvement measures are required. If the construction efficiency is affected, the use temperature of the structural sealant can be increased or some auxiliary heating measures can be taken, such as storing the structural sealant in the warm room or air conditioning room in advance, installing a heater in the gluing workshop for heating, increasing the ambient temperature of the gluing, etc. In addition, appropriate glue injection tools can be selected, such as manual glue gun with large thrust, pneumatic glue gun, electric glue gun, etc.

4. High quality SILICONE STRUCTURAL SEALANT products bulges - uneven appearance

In the low temperature environment, high quality SILICONE STRUCTURAL SEALANT products is prone to bulge. The curing speed of silicone structural sealant becomes slower, and the time required for its surface to cure to a sufficient depth will be longer. If the width change of the sealant joint (usually caused by the thermal expansion and cold contraction of the panel) is larger, the surface of the sealant joint will be affected, resulting in uneven bulge.

Solution: If the relative deformation of the glue joint is too large due to low humidity, temperature difference, glue joint size and other reasons, it is recommended to use one or more of the following methods for construction:

1) Appropriate sunshade measures shall be taken, such as using dust-proof net to shield the scaffold, so that the panel will not be directly exposed to the sun, reduce the panel temperature, and reduce the joint deformation caused by temperature difference.

2) Construction shall be arranged around noon as far as possible to avoid construction in the morning and evening.

3) The method of secondary gluing is adopted (that is, if the first gluing has sunken glue seams, it can be cured for 2-3 days, and then a layer of glue is added on the surface after it has elasticity).

Other precautions

1： How to store high quality SILICONE STRUCTURAL SEALANT products in winter?

The best storage temperature of high quality SILICONE STRUCTURAL SEALANT products is 5~27 ℃. If possible, it can be placed in an air-conditioned room with constant temperature and humidity. In addition, the construction temperature of high quality SILICONE STRUCTURAL SEALANT products should not be lower than - 5 ℃ or higher than 45 ℃.

2： Can I apply glue when the temperature is lower than - 5 ℃ and the relative humidity is 35%?

Users are not recommended to apply high quality SILICONE STRUCTURAL SEALANT products, because:

1. When the temperature is too low, the wettability of the adhesive and the substrate surface will be reduced, and there may be imperceptible fog or frost on the substrate surface, which will affect the adhesion between the sealant and the substrate.

2. Under low temperature, the curing speed of high quality SILICONE STRUCTURAL SEALANT products is slower than that under normal conditions. In case of seam change before the sealant has not been cured, it is easy to cause the surface of the sealant to bulge or crack, affecting the appearance of the sealant.