With the development of the past two decades, the application of silicone sealants has involved many fields such as curtain walls, doors and windows, automobiles, roads and bridges, new energy, electronic appliances, aerospace, electric power and environmental protection. Silicone sealants dominate the adhesive industry by virtue of their excellent weather resistance, wide temperature range, suitable physical and mechanical strength, and long service life.

Silicone glue is a kind of adhesive, and good adhesion is essential. However, in actual use, the problem of poor bonding occasionally occurs.

We discuss the following aspects:

1. Is the product selection correct?

Nowadays, silicone sealant has been involved in many fields, and there will be many application points in different application fields. Silicone sealants are divided into acid type glue, alcohol type glue and oxime type glue from the reaction type. The advantage of acid-based glue is rapid surface drying and deep curing, but during the curing process, acetic acid molecules will be released, which has a greater taste, and will corrode some substrates, such as concrete and metals; the advantage of alcohol-based glue is Neutral curing, the released ethanol molecules are non-toxic to the body, and can bond to a wide range of substrates. The disadvantage is that deep curing is not as good as acid type glue; the advantage of oxime type glue is that it is neutral curing, and deep curing is faster than alcohol type glue. The bonding substrate is also very extensive, but it will corrode copper-based substances. Different types of silicone sealants have different chemical systems, and the ways to form bonds are also different. If you want to form a good bond, you must choose a suitable product.

2. Is it a special substrate?

With the rapid development of the material industry, many new materials are widely available. A silicone sealant cannot guarantee good adhesion to all substrates; even if the same substrate, different surface treatments will cause silicon The bonding effects of ketone sealants are different; even the bonding effects of materials from different manufacturers in the same treatment are quite different. In this context, it is strongly required to conduct an adhesion test before the use of silicone sealants in order to select suitable products, cleaning agents and primers.

3. Is it cleaned in accordance with the cleaning process?

The two-piece cleaning method involves first wiping with a cotton cloth moistened with solvent, and then wiping with a second clean cloth. Note that white, clean, soft and non-linting cotton cloth should be used during the process.

4. Is the primer applied correctly?

The role of the primer is to promote the adhesion of the sealant to the substrate. The correct use of the primer helps to produce a strong and continuous bond on the surface that is not easy to bond. Before using the primer, the surface of the substrate should be dry and clean; when using it, a clean, lint-free cotton cloth should be used to apply a thin and even layer of primer on the interface surface. Use a brush for difficult or rough surfaces. Do not pour or Excessive use of primer; after use, the silicone sealant should be applied after the primer is completely dry.

5. Is the glue filling full?

The silicone sealant needs to be fully injected at the designed interface, and the width and thickness are both in line with the interface design requirements to achieve the expected performance requirements. At the same time, a spatula is required to make the glue and the substrate fully contact to form an effective bond. The correct sizing should be uniform and continuous sizing, and then modify it with a spatula within the operable time range. During the modification, the glue should be in good contact with the surface of the substrate to be bonded.