What is polyurethane sealant?

Polyurethane sealant is a kind of field filling, bonding joint curing material at room temperature. Before curing, it is paste, can be extruded to fill the gap, after curing as an elastic body, play the interface bonding, anti-leakage, waterproof, dust-proof, withstand vibration or thermal expansion cold contraction caused by displacement and other roles.Polyurethane sealant (referred to as PU sealant), is based on polyether polyols and polyisocyanate as the main raw materials, supplemented by filler, plasticizer, coupling agent, catalyst mixed into the elastomer.

1.Classification of polyurethane sealants

Polyurethane sealant is generally divided into one component and two components of two basic types, single group is divided into wet gas consolidation type, two groups are divided into reaction consolidation type. One component sealant construction is convenient, but curing is slow; The two components have the characteristics of fast curing and good performance, but it needs to be prepared and the process is complicated. Both have a future.

According to the fluidity, the polyurethane sealant can be classified as non-sagging and self-leveling. Non-hanging type is used in vertical plane, inclined plane, ceiling and other occasions. Before curing, it will not offset, slide or flow due to the weight of the adhesive strip. The self leveling type is specially used in horizontal situations. According to the nature of use can also be divided into dry type, half dry type and full curing elastic type.

2.Characteristics of polyurethane sealant

Polyurethane sealant is available in single-component and two-component packaging types. Two-component polyurethane sealant is two components respectively packaged, one is a component containing NCO, the other is a curing agent containing active hydrogen, when used, the two components are mixed in a certain proportion, through the reaction of NCO and active hydrogen and solidified into an elastomer. Its advantage is that the room temperature curing speed is faster than the single component, the cost is low, but the operation is not convenient. One component polyurethane sealant is composed of NCO sealing end prepolymer and filler and additives, sealed storage, use and reaction with moisture in the air and solidified into a network structure of elastic body.

Because polyurethane sealant has good adhesion to a variety of materials (such as concrete, metal, glass), and has the characteristics of UV resistance, low temperature resistance, chemical resistance, high cost performance, it has been widely used in construction engineering, transportation, aerospace and automotive fields.

3.Application of polyurethane sealant

The main use of polyurethane sealant is civil construction, transportation and so on.

Specific applications in architecture are: Concrete prefabricated parts and other building materials of the connection and sealing of the construction joint, the wood frame around the doors and Windows and between the wall of the concrete seal caulking, light structure on the building (such as curtain wall) paste caulking, balcony, swimming pool, bathroom and other facilities of waterproof caulking, air conditioning and other system of sealing, insulation double glass, insulation window frame seal.

The application of polyurethane sealant in automobile is: the assembly of Windows (mainly windscreen glass), the assembly of body and other parts, etc.

In civil engineering, polyurethane sealant used for high-grade roads, Bridges, airstrips and other flexible joints of the caulking seal and concrete, ceramic, PVC and other materials such as sewage, underground gas pipelines, wire circuit pipelines and other pipe joints of the connection seal, subway tunnel and other underground tunnel joints.

Polyurethane sealant can also be used for flexible joints of cables (such as underground cables) and sealing of electronic components to prevent dust and earthquake. Used for heat insulation system such as refrigerated truck, cold storage insulation layer and low temperature container bonding seal and so on.