Classification by physical form
- Sealant
1.1 Classification according to sealant vulcanization method
(1) Moist air vulcanized sealant
This series of sealants cure with moisture in the air. It mainly includes single-component polyurethane, silicone rubber and polysulfide rubber. The polymer base material contains active groups, which can react with water in the air to form cross-linking bonds and vulcanize the sealant into a network structure.
(2) Chemically vulcanized sealant
Two-component polyurethane, silicone rubber, polysulfide rubber, neoprene rubber and epoxy resin sealants all fall into this category and are generally vulcanized at room temperature. Some one-component chlorosulfonated polyethylene and neoprene sealants and polyvinyl chloride sol paste sealants must be vulcanized through chemical reaction under heating conditions.
(3) Thermal transition sealant
Sealants using plasticizer-dispersed polyvinyl chloride resin and asphalt-containing rubber are two different types of thermal transition systems. Vinyl resin plasticizer is a liquid suspension at room temperature and is converted into a solid by heating and hardened; while the rubber-asphalt sealant is hot-melt.
(4) Oxidation hardening sealant
Surface-dry sealant for inlaying or installing glass is mainly based on dry or semi-dry vegetable oil or animal oil. This type of oil can be refined polymerized, blown or chemically modified.
(5) Solvent evaporation solidifying sealant
This is a sealant based on a non-sticky polymer after the solvent evaporates. This type of sealant mainly includes butyl rubber, high molecular weight polyisobutylene, acrylates with a certain degree of polymerization, chlorosulfonated polyethylene and neoprene rubber.
1.2 Classification by sealant form
(1) Paste sealant
This type of sealant is basically used in static joints, and its service life is generally 2 years or more. Three main materials are usually used: oil and resin, polybutylene, and asphalt.
(2) Liquid elastomer sealant
These sealants consist of liquid polymers that are vulcanized to a truly elastic state, giving them the ability to withstand repeated joint deformation. Polymer elastomers used in elastomer sealants include liquid polysulfide rubber, thiol-terminated polypropylene ether, liquid polyurethane, room temperature vulcanized silicone rubber and low molecular butyl rubber. This type of sealant is usually formulated into two components, and the two components are mixed when used.
(3) Hot melt sealant
Hot melt sealant is also called hot construction sealant. Refers to a sealant based on a blend of elastomer and thermoplastic resin. This type of sealant is usually extruded directly into the joint through a certain mouth mold under heating (150~200℃). Thermal application can improve the sealant's ability to wet the adhered base material, so it has good adhesion to most adhered base materials. Once placed in place, it cools and forms or forms into a film, becoming a strong elastomer with very little shrinkage. The main materials of thermal construction sealants are mainly isobutylene polymers, EPDM rubber and thermoplastic styrene block copolymers. They are usually blended with thermoplastic resins such as EVA, EEA, polyethylene, polyamide, polyester, etc.
(4) Liquid sealant
This type of sealant is mainly used for sealing mechanical joint surfaces, replacing solid sealing materials, that is, solid gaskets, to prevent internal fluids from leaking from the joint surfaces. This type of sealant is usually made of polymer materials such as rubber, resin, etc. as the main material, and is supplemented with fillers and other components. Liquid sealants are usually divided into four categories: non-drying adhesive type, semi-drying viscoelastic type, dry adhesive type and dry peelable type. Choose according to specific use parts and requirements.