Sealant refers to a sealing material that deforms with the shape of the sealing surface, is not easy to flow, and has a certain adhesiveness.
It is an adhesive used to fill configuration gaps for sealing. It has the functions of anti-leakage, waterproof, anti-vibration, sound insulation and heat insulation. Usually, dry or non-dry viscous materials such as asphalt, natural resin or synthetic resin, natural rubber or synthetic rubber are used as the base material, and inert fillers such as talc, clay, carbon black, titanium dioxide and asbestos are added. Plasticizers, solvents, curing agents, accelerators, etc. It can be divided into three categories: elastic sealant, liquid sealing gasket and sealing putty. It is widely used in the sealing of construction, transportation, electronic instruments and parts.
There are many types of sealants: Silicone sealants, polyurethane sealants, polysulfide sealants, acrylic sealants, anaerobic sealants, epoxy sealants, butyl sealants, neoprene sealants, PVC sealants, and asphalt sealants.
The main properties of sealant
(1)Appearance: The appearance of the sealant is mainly determined by the dispersion of the filler in the base. The filler is a solid powder. After being dispersed by a kneader, a grinder and a planetary machine, it can be evenly dispersed in the base rubber to form a fine paste. A small amount of slight fines or sand is acceptable and normal. If the filler is not well dispersed, many very coarse particles will appear. In addition to the dispersion of fillers, other factors will also affect the appearance of the product, such as mixing of particulate impurities, crusting, etc. These cases are considered rough in appearance.
(2) Hardness
(3) Tensile strength
(4) Elongation
(5) Tensile modulus and displacement ability
(6) Adhesion to substrate
(7) Extrusion: This is the performance of sealant construction An item used to indicate the difficulty of the sealant when it is used. Too thick glue will have poor extrudability, and it will be very laborious to glue when it is used. However, if the glue is made too thin simply considering the extrudability, it will affect the thixotropy of the sealant. The extrudability can be measured by the method specified in the national standard.
(8) Thixotropy: This is another item of the construction performance of the sealant. Thixotropy is the opposite of fluidity, which means that the sealant can only change its shape under a certain pressure, and can maintain its shape when there is no external force. shape without flowing. The determination of the sag specified by the national standard is the judgment of the thixotropy of the sealant.
Post time: Nov-04-2022