There are many problems in the practical application of silicone structural adhesive, mainly in the following five aspects:

1. No adhesion and compatibility test was carried out before construction

So far, there have also been many quality and safety accidents caused by the failure of the structural adhesive to bond with the substrate. Compatibility reflects whether there is a physical or chemical reaction between the structural adhesive and the phase contact attachment, such as unqualified compatibility, which will directly lead to discoloration of the structural adhesive, bond damage and performance decline. Therefore, it is necessary to carry out adhesion and compatibility tests before construction.

2, resistance to the use of primer during construction

On the one hand, the construction side will increase the construction cost, in fact, the key is the construction side's understanding of the undercoat is not enough, the undercoat mainly plays a bridge role, it can improve the adhesion and shorten the bonding time, but also improve the water resistance and durability of the bond;

3, the maintenance environment and maintenance time did not meet the requirements

According to the standard, the two-component complete curing requires maintenance for 14 days and the single component for 21 days, but according to the test results, the two-component curing for 3 days and the single component curing for 7 days can basically achieve the curing and bonding effect. When the temperature is low, the maintenance time should be extended appropriately.

4, improper selection of profiles

In Specification 102, 3.1.2 clearly states: "Aluminum alloy materials shall be anodized on the surface, electrophoretic coating, powder spraying or fluorocarbon coating treatment." And the thickness of the surface treatment layer of aluminum alloy profiles has also been clearly specified, such as the average film thickness of anodic oxidation treatment is ≥15 microns, and the local film thickness is ≥12 microns. However, there is no clear provision in the relevant standards and specifications for the treatment of aluminum profile gluing surface, experience has proved that the anodized profile and silicone adhesive bonding effect is better, followed by electrophoretic painting and network treatment, and again powder spraying and fluorocarbon paint spraying treatment. In addition, the adhesion and durability of the surface treatment layer of aluminum profiles treated by powder spraying and fluorocarbon paint spraying are relatively poor. If the design uses the spray profile, it is recommended to collate before spraying, and then protect the adhesive surface with film, and then spray.

5, after construction, no stripping and unit cutting test was carried out

The glue cutting test of the unit is the damage test of the finished product, which is suitable for the inspection of the adhesion of the structural seal in the assembly field test, and is used to find the problems in the field application. Such as the substrate is not clean, the use of inappropriate primer, improper use of primer, incorrect joint assembly, unreasonable design of bonding joints and other problems that affect bonding (such as the surface treatment of the substrate, the temperature and humidity of the curing environment, the width and thickness of the colloid, air permeability, etc.).

With the batch stripping, that is, non-finished product damage test, it is suitable for the detection before construction, and can preliminarily judge the bonding effect of structural adhesive and substrate. Although the surface treatment is the same as the actual state of the project, after all, it is tested by a special person, which basically excludes the factors of human error, and the colloidal thickness and air permeability are different from the actual situation, and can not completely replace the results of the cutting glue test of the unit.