Classification and application scope of silicone building sealants

1. Classification of sealants

The classification of silicone building sealants depends on different criteria, and there are many different classification methods according to different criteria. The following is a brief description of several commonly used classification methods.

(1) Classification by the packaging method of sealants. Common building sealants can be divided into single-component and two-component types. The use process of single-component sealants is simple, and no weighing and mixing is required before construction. After construction, the cross-linking and curing is completed with the help of moisture in the air. Two-component sealants must be mixed in proportion before use. They can be applied using a special glue machine or manually mixed. The two components can be cross-linked and cured after mixing.

(2) Classification by the function of sealants. According to the function of sealants, they are roughly divided into two categories: ordinary silicone sealants (general type) and elastic silicone sealants for curtain walls.

Elastic silicone sealants for curtain walls occupy a position that is difficult to replace by other sealants in building curtain wall projects. The characteristic of building curtain wall structures is that the curtain wall panels are fixed to the keel of the main frame of the building using a gluing and sealing process. The glue used is mainly elastic silicone sealants for curtain walls. Its application scope includes the bonding of curtain wall panels, the joints of panel components and the caulking and sealing of joints between components.

According to the different application parts and the requirements for sealant indicators, elastic silicone sealants for curtain walls are divided into silicone structural sealants (referred to as structural sealants) and joint sealants (also known as silicone weathering sealants). Among them, silicone structural sealants are elastic bonding and sealing materials that can withstand stress and strain caused by the building structure itself or external forces, and are also an important functional engineering material. Weathering sealants focus on their elastic strain capacity and their excellent weather resistance, durability and waterproof sealing properties. They are also important supporting sealing materials in curtain wall projects and are generally supplied in a single component form.

2. Application scope of silicone building sealants

According to the cross-linking and curing mechanism of sealants, the common silicone building sealants are deacetic acid type, deketoxime type and dealcohol type. Among them, general silicone sealant products are mainly used for bonding and sealing of joints between glass components, joints between glass suspension, glass sink and frame, metal joints, stone, concrete joints, plexiglass, polycarbonate, engineering plastics and glass panels.

With the rapid development of modern construction industry, a large number of large frame hanging plate structures and large curtain wall structures of different materials have been adopted. This kind of advanced flexible building structure needs to be bonded and sealed with elastic silicone sealant with good adaptability to various substrates, high bonding strength, strong resistance to large deformation and displacement, weather resistance, UV radiation resistance, water resistance and excellent durability. This kind of silicone structural sealant grade product is mainly suitable for use in SSG construction method and glass curtain grid construction method.

2. Characteristics of silicone sealant

1. High and low temperature resistance

The high and low temperature resistance of polysiloxane and its elastomer is mainly reflected in the small performance changes in its physical properties, mechanical strength and other aspects within the selected high and low temperature range. These characteristics that are not available in carbon chain polymers should be attributed to the unusual molecular chain structure of polysiloxane. One reason is the inherent flexibility of the polysiloxane molecular chain; the second is the excellent heat resistance and thermal oxygen degradation resistance of polysiloxane molecules.

2. Weather resistance

It has good tolerance to corrosion from natural environments such as oxidation, ultraviolet rays, acid and alkali, and is not prone to aging and embrittlement after long-term use.

3. Excellent adhesion

It has excellent adhesion to a variety of common substrates such as glass, aluminum, stainless steel, stone, ceramic tile, concrete, etc.

4. Chemical corrosion resistance

It has good tolerance to common chemicals such as acid mist, water, ethanol, chloride, etc., and is suitable for environments that need to withstand chemical corrosion. ‌

5. Easy construction performance

The construction performance of silicone sealant is less affected by ambient temperature, and the viscosity does not change much when the daily temperature changes. It is an ideal product for all-season construction.