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Analysis of Common Problems of Silicone Structural Sealants
In the previous issue, “Baiyun Online”, we introduced the design and calculation of silicone structural seals. Through good design, we ensured that the performance of silicone structural adhesives was well utilized to ensure the safety of curtain walls. In this issue, we will introduce to you the analysis of common problems in the construction of silicone structural sealants!
1. Silicone structural sealant and profile (sub-frame), glass do not bond
Structural adhesive and profiles, glass do not bond or bad bonding, "White Cloud Online" can be summarized for the following reasons:
1 The construction is not standardized, for example, the adhesive test is not done before the construction, the substrate is not cleaned as required, and the cleaned glass is not immediately assembled. Solution: Ensure that the substrate is clean and perform the construction according to the specifications;
2 During the construction process, the cleaning or primer coating method does not comply with the construction process. Solution: According to the "secondary rag method" cleaning, the next step of construction within 1 hour; the primer coating liquid should be thin and uniform, the next step construction within half an hour, the specific operation process can refer to "white cloud online" "building silicone Structural glue coating primer process";
3 substrate material issues, such as differences in the different batches of substrates. Solution: Strictly use materials that are consistent with the adhesion test. In the production process, different batches of materials need to be randomly tested on-site;
4 Bicomponent structure adhesive glue mixing process is uneven. Solution: Check the A and B components in the butterfly test before injection.
5 too much or too little amount of B component of the two-component structural adhesive exceeds the allowable range of the manufacturer. Solution: Before the injection of plastic by pull-off time test to confirm that A, B component of the glue ratio within the specified range of the manufacturer;
6 The low ambient temperature results in slow initial bonding, or short curing time, and no adhesion during tapping. Solution: Increase the use and maintenance of ambient temperature (especially one-component).
Poor bonding and good adhesion
Non-uniform primer results in poor adhesion
2. Silicone sealant cured slowly
Silicone structural adhesives cure slowly. According to the "Baiyun Online" expert group's many years of technical service experience, most of the following three types of reasons:
1 Slow curing due to low ambient temperature and humidity. Solution: improve the use of the environment and the maintenance of the ambient temperature, such as the use of confined space to set up a hot house, air conditioning, heating and other methods to maintain the temperature of the maintenance environment at 10-40 °C, humidity maintained at 50 to 90%;
2 Slow curing due to low ambient temperature and humidity. Solution: Through the pull-off time to confirm whether the proportion of A and B components is normal, the proportion of B component can be properly increased within the allowable adjustment ratio of the manufacturer to accelerate the curing speed.
3 silicone structural adhesive has expired or its own quality problems. Solution: Check the production lot number of the glue, and check whether the glue is within the shelf life, and use the silicone glue with quality and brand protection.
Pull-off time test
Silicone structural sealants are critical to the quality and safety of concealed curtain walls. Choosing “good glue” is a prerequisite for ensuring quality and safety. “Good use” of glue is an important process for the safe application of concealed frame curtain walls. The next issue of “Baiyun Online” will continue to bring you an analysis of the common problems in the construction of silicone structural adhesives!