This article mainly introduces the FAQ about neutral silicone sealant in the application.
1. Analysis of the Causes of Silicone Sealant Bubbling?
(1) Air is trapped during injection
(2) The interface is damp during injection
(4) The glue is exposed to the sun before it is cured
(5) The surface temperature of the substrate is too high
(6) The temperature difference between day and night is large, and the interface expands and contracts greatly
2. Why does the sealant crack after curing?
Cracking after curing mainly refers to the debonding phenomenon on one side of the substrate caused by poor adhesion to the substrate. There are several main reasons for this:
1. No compatibility test was performed, that is, the colloid and the substrate are incompatible, resulting in cracking.
2. The substrate surface is not cleaned or the construction is improper, such as construction before the solvent is dry or it is contaminated after cleaning for too long.
3. Why does neutral transparent glue (ketoxime type) turn yellow after curing?
Ketoxime transparent glue (including light-colored glue) will turn yellow to varying degrees after curing for about 20 days, and the yellowing will tend to intensify with the increase of time. Here, the yellowing of ketoxime transparent glue is not a problem of individual manufacturers, but a problem of the entire industry of a product, including foreign manufacturers. After analysis, it may be due to the addition of coupling agents with amino groups.
4. Why are there uneven conditions such as mottled lines after the sealant is extruded?
This phenomenon is mainly caused by pollution during production or packaging, which is a problem of quality control of the manufacturer.
5. What is the reason for the wrinkling of the surface after the neutral glue is cured?
Generally there are several reasons:
(1) The expansion coefficient of the substrate is large;
(2) There is displacement or vibration;
(3) Some low-grade glue is too thin, with less filler and more plasticizer (white oil). During the curing process, the plasticizer (white oil) evaporates to a certain extent, which makes the volume of the glue smaller, so the glue will shrink and wrinkle;
(4) If the glue is applied too thinly, it is easy to shrink and wrinkle after curing. Increasing the thickness of the glue can reduce the occurrence of this phenomenon (it is recommended to apply glue more than 2mm).
We are going to make a series on this topic, and feel free to send us more FAQ about neutral silicone sealant.