Sealants have numerous uses in construction, industry, and other fields, but with many types available on the market, selecting the right sealant can be confusing. Different adhesives have obvious differences in curing methods, weather resistance, bonding strength, flexibility, etc. In order to ensure the best performance, it is very important to correctly distinguish and use various types of sealants. This article will introduce the characteristics of different types of sealants in detail to help you make a more appropriate choice.
Definition of Sealant
So, what is a sealant? As can be seen from the name alone, sealant is a material specially used for sealing and bonding. Before construction, it is a fine paste and can be easily extruded to fill various joints. After curing, it can form a layer of elasticity. The sealing layer effectively prevents the penetration of water, air, dust, etc., and can also buffer vibration and adapt to displacement to ensure a long-term sealing effect.
History Of Sealants
In the 19th century, with the advent of rubber vulcanization technology, sealing materials based on natural rubber began to be used in the industrial field. In the middle of the 20th century, with the rapid development of aerospace technology, the demand for high-performance sealants increased dramatically. In this context, silicone sealants with excellent weather resistance and extreme temperature resistance were produced.
In the 1970s, in order to meet a wider range of bonding needs, more adaptable sealants such as acrylic acid and MS polymer came out one after another, which could form a strong bond between different materials such as metal, plastic, and glass.
Nowadays, environmental awareness continues to increase, and the market prefers formaldehyde-free, low-VOC green sealant products, driving the industry to develop in a more sustainable direction.
Types Of Sealant
First of all, according to different materials, sealants are divided into the following types:
- Acrylic Sealant
Acrylic sealant is mainly composed of water-based acrylic emulsion or solvent-based acrylic resin. It is environmentally friendly, non-toxic, tasteless, and has strong adhesive properties. It can be applied to concrete, wood, metal, plastic, and other substrates. It has good elasticity after curing and can effectively adapt to the substrate. Thermal expansion and contraction avoid cracks caused by environmental changes. In addition, it also has excellent weather resistance and ultraviolet resistance, and is not easy to age and turn yellow under long-term outdoor exposure.
- Silicone Sealant
Silicone sealant is a high-performance sealing material based on silicone polymer. It has excellent weather resistance, elasticity, and temperature resistance, as well as excellent waterproof and moisture-proof effects. After curing, it can form a soft and tough elastic colloid, which can effectively resist ultraviolet rays and aging, and has a service life of up to 20 years. According to its performance characteristics, it can be subdivided into high-temperature resistant, weather-resistant, and medium-sized silicone sealants to meet the needs of different application scenarios.
- MS polymer sealant
This is a high-performance elastic adhesive based on silane-modified polyether, which has the weather resistance of silicone and the high adhesion of polyurethane. It has excellent ultraviolet resistance and aging resistance, and can be used stably for a long time in extreme temperatures or humid environments. Its environmentally friendly formula has no solvent and no irritating smell, meets international environmental protection standards, remains flexible after curing, and can withstand dynamic displacement. In addition, the surface can be spray-painted, which is convenient for later beautification and meets diverse decoration needs.
This is a high-performance elastic sealing material based on polyurethane (PU). It has extremely strong adhesion, oil stain resistance, and chemical corrosion resistance, and can remain stable at extreme temperatures from-40 °C to 80 °C. Adapt to severe cold or high temperature environments, while providing excellent shock absorption and cushioning effects, effectively absorbing mechanical shock and structural deformation, ensuring long-lasting and reliable seals without cracking.
- Polysulfide Sealants
Polysulfide sealant is composed of liquid polysulfide rubber, filler, plasticizer, and curing agent. It has excellent oil resistance, solvent resistance, chemical corrosion resistance, good flexibility and aging resistance, and can be used in oil stains, acid and alkali. Long-term stable use in harsh environments such as alkali.
Sealants made of butyl rubber as the main component have strong waterproof properties, anti-aging, and strong flexibility. According to the construction method, they are divided into two types: hot-melt type and non-vulcanizing type. Hot-melt type sealants need to be used after heating and melting, and solidified after cooling. The non-vulcanizing type relies on solvent volatilization or the viscoelasticity of butyl rubber itself to maintain sealing.
According to the curing method, it is divided into:
- Moisture-curing type: It is a material that cures by reacting with moisture in the air, including silicone sealants, polyurethane sealants, and modified silicone sealants.
- Oxidation curing type: It is a type of sealing material that cures by reacting with oxygen in the air. It is mainly used for filling, bonding, and sealing. Its typical representatives include butyl rubber sealants and some oil-based (putty) sealants.
- Thermal curing type: Thermal curing sealant is a type of sealing material that needs to be heated to complete curing. Its curing relies on external heat sources, has a fast curing speed and stable performance, including epoxy resin sealant and silicone sealant.
- UV/light curing type: It does not require heating and relies on photoinitiators to absorb specific wavelengths of energy to trigger the polymerization reaction. It has the characteristics of fast curing speed, precise control of the curing area, and low energy consumption, such as UV acrylic adhesive, UV silicone sealant, etc.
Sealants can be divided into the following categories according to their uses:
Construction sealant
It is used to seal joints such as doors and windows, bathroom toilets, bathtubs, curtain walls, expansion joints, and roof waterproofing. It has excellent weather resistance, corrosion resistance, and waterproofing properties. Commonly used types include silicone sealants, polyurethane sealants, and acrylic sealants.
Industrial sealant
This sealant is suitable for mechanical assembly, pipeline sealing, and equipment protection. It has excellent oil stain resistance, chemical corrosion resistance, and vibration resistance. Common types include anaerobic thread sealant and RTV silicone rubber.
Automotive sealant
It is mainly used to seal key parts such as automobile windshields, engine compartments, fuel tanks, and car bodies. It has excellent high temperature resistance, aging resistance, seismic buffering and sound insulation, and noise reduction properties. Common types include butyl sealants, polysulfide sealants, and epoxy sealants etc.
Electronic sealant
It has excellent insulation, moisture resistance, thermal conductivity, and flame retardancy, and is suitable for electronic and electrical fields such as circuit board potting, LED packaging, battery sealing, and junction box waterproofing. Common types include UV curing adhesive, silicone sealant, etc..
In addition, sealants can also be single-component, two-component, neutral-curing curing and acid-curing according to their characteristics. Single-component sealants are easy to use, do not require mixing, and are suitable for on-site construction. Two-component sealants need to be mixed in proportion, and the performance after reaction curing is stronger, making them suitable for scenarios with higher requirements. Neutral curing sealants are non-corrosive to the substrate and are especially suitable for bonding sensitive materials such as metal and glass. Acid-curing sealant has a fast curing speed and high bonding strength, but it may corrode some materials.
Summarize
As an important material in modern engineering, the type and selection of sealant directly affect the sealing effect and service life. They each have their advantages in weather resistance, elasticity, adhesion, and environmental protection. When choosing sealant, you need to comprehensively consider the characteristics of the base material, construction environment (such as temperature, humidity,) and durability requirements to ensure the best sealing performance.
