How to apply sealant in cold weather?
Curing method and influencing factors of sealant:
At present, the common one-component silicone sealant and modified silicone sealants on the market are moisture-curing types. After extrusion, they need to contact the moisture in the air to cure from the surface to the inside. The lower the ambient temperature and humidity, the slower the curing speed. The thicker the gel, the slower the curing speed of the inner gel.
Precautions for winter construction:
1. Suitable temperature construction.
When the temperature is low, the wettability of the adhesive and the substrate surface decreases, and condensation and frost may appear on the substrate surface, affecting the adhesion between the sealant and the substrate.
Generally speaking, the recommended construction temperature range of sealant is 5 ℃ - 45 ℃, and the construction temperature of structural adhesive is 10 ℃ - 40 ℃ (humidity 40% - 80%). If the construction is required to be carried out under the condition of lower than 5 ℃ due to special circumstances, the cohesiveness test shall be carried out on site to ensure that the cohesiveness is qualified before large-scale construction. During the construction, the substrate surface shall be cleaned to ensure that the bonding surface is dry and clean, and the on-site tapping inspection frequency shall be increased.
2. Increase the environmental humidity and accelerate the construction progress.
During the construction of the workshop, the window sash sealant cannot be turned over quickly due to slow curing, which affects the construction progress. The ambient temperature and humidity can be appropriately increased, and the sizing surface should be kept dry.
3. The internal and external walls shall be constructed to avoid deformation caused by human touch.
During the construction of sealant for internal and external walls, due to slow curing, no other adverse effects will be caused, and no other measures need to be taken, but a reminder should be made to avoid the deformation of sealant due to human touch during curing.
4. The curtain wall joints shall be constructed with quick-drying products or on cloudy days.
During the construction of curtain wall joint sealant, bulging and deformation are easy to occur due to slow curing, especially for aluminum plate curtain walls and large plate glass curtain walls. It is recommended to select "antas 193 neutral silicone weather resistant sealant " quick drying product; Select cloudy days for construction (small temperature difference, small joint displacement) or apply glue twice.
5. One-component structural adhesive construction, extending the curing time.
During the construction of one component silicone structural adhesive, if the uncured one-component silicone structural adhesive is in a closed state, it is difficult for the moisture in the air to enter the interior of the adhesive layer, resulting in the colloid cannot be completely cured.
It is recommended to extend the curing time properly until the sealant is completely cured, and the next operation can be carried out after the rubber tapping test is qualified; Or replace it with two-component silicone structural adhesive (Note: the strength of two-component structural adhesive after curing will also be affected if it is completely sealed before curing).
6. It is recommended to store the sealant indoors.
When the temperature of silicone sealant is low, the extrudability will decrease, which is shown by the heavy hand feeling of sealant application. It is normal. Generally, the manufacturer will make appropriate adjustments to the extrudability according to seasonal changes to meet the construction needs. During winter construction, it is recommended to store the sealant indoors, and if possible, use an electric glue gun for construction.
7. Confirm whether it can be cured normally during use.
Silicone adhesive products are stored at low temperatures for too long. When they continue to be used after the temperature rises, it is necessary to confirm the curing condition of the sealant. If the sealant can be cured normally and within the warranty period, it can be used normally. If there is any abnormality, please report it to the manufacturer in time.
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Guangzhou Jointas Chemical Co., Ltd.