Classification and application of polyurethane sealants

1: Classification

Polyurethane sealants are generally divided into two basic types: single-component and two-component. The single-component is moisture curing type, and the two-component is reaction curing type. One-component sealant is easy to construct, but it cures slowly; two-component sealant has the characteristics of fast curing and good performance, but it requires preparation when used and the process is more complicated. Both have their own prospects for development.

According to whether there is fluidity, polyurethane sealant can be divided into non-sagging type and self-leveling type. The non-sagging type is used in vertical surfaces, inclined surfaces, ceilings and other situations. Before curing, the strip will not shift, slide or flow due to its own weight; while the self-leveling type is specially used in horizontal situations. According to the properties after use, it can also be divided into non-drying type, semi-drying type and fully cured elastic type.

2: Application

The main uses of polyurethane sealants are in the civil construction industry, transportation industry, etc. For example, in Japan, about 75~80% of polyurethane sealants are used in construction, 15% are used in automobiles, machinery manufacturing, etc., and 5% are used in civil engineering and other aspects.

Specific applications in construction include: connecting prefabricated concrete parts and other building materials and filling and sealing construction joints, sealing caulking around the wooden frames of doors and windows and between concrete walls, and pasting lightweight structures on buildings. Caulking, waterproof caulking of balconies, swimming pools, bathrooms and other facilities, sealing of connections between air conditioners and other systems, sealing of insulated double-glazed glass, insulated window frames.

The applications of polyurethane sealants in automobiles include: assembly and sealing of windows, assembly of car bodies and other parts.

In civil engineering, polyurethane sealant is used for caulking sealing of elastic joints in high-grade roads, bridges, airport runways, etc., and pipe joints such as sewers, underground gas pipelines, wire and circuit pipes made of concrete, ceramics, and PVC. Connection sealing, sealing of subway tunnels and other underground tunnel connections.

Polyurethane sealant can also be used for flexible joints of cables and potting of electronic components to prevent dust and earthquakes; it can also be used for bonding and sealing of thermal insulation systems such as refrigerated trucks, cold storage insulation layers and low-temperature containers.