A Silicone sealant has the advantage of long service life and aging resistance compared with other sealants. Forty-six years after the Founding Plaza dome was built in 1970, silicone sealant joints are still in use. Data show that the service life of silicone sealant can reach 50 years.

A Environmental factors have a significant effect on the curing properties of sealant. The first is the effect of temperature, the higher the temperature, the faster the curing reaction. If the temperature is very low, such as 5℃ below, sealant curing will be very slow. And if the temperature is too high, such as 40℃ or above, the sealant will be too dry to use. Humidity also has a significant effect on the curing performance of sealant, because sealant curing reaction needs water in the air, so too dry weather such as relative humidity below 40 DEG C is not good for sealant curing. But it is not the higher the humidity, the better, because the sealant curing to release volatile small molecules, if the air humidity is too high, small molecules are not easy to volatile, which is not conducive to sealant curing. Experiments have proved that when the relative humidity is higher than 80℃, the deep curing will be affected, sometimes after 2-3 days, the surface of the sealant is still with viscosity. The standard condition of the sealant performance stipulated by the national standard is the temperature (23±2) ℃, relative humidity (50±5) ℃

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A Environmental factors have a significant effect on the curing properties of sealant. The first is the effect of temperature, the higher the temperature, the faster the curing reaction, the phenomenon is dry, desticking are relatively fast, if the temperature is very low, such as 5℃ below, sealant curing will be very slow. And if the temperature is too high, such as 40℃ or above, the sealant will be too dry to use. Humidity also has a significant effect on the curing performance of sealant, because sealant curing reaction needs water in the air, so too dry weather such as relative humidity below 40 DEG C is not good for sealant curing. But it is not the higher the humidity, the better, because the sealant curing to release volatile small molecules, if the air humidity is too high, small molecules are not easy to volatile, which is not conducive to sealant curing. Experiments have proved that when the relative humidity is higher than 80℃, the sealant desticking and deep curing will be affected, sometimes after 2-3 days, the surface of the sealant is still with viscosity. The standard condition of the sealant performance stipulated by the national standard is the temperature (23±2) ℃, relative humidity (50±5) ℃.

A The one-component sealant is stable inside the container and will solidify when exposed to air. This is a chemical reaction process, sealant is originally paste, and after contacting with the air, the base glue, crosslinking agent, catalyst and water in the air will begin a chemical reaction. The result of this chemical reaction is to make the paste gradually become a kind of elastic solid, this is the sealant curing. After the sealant is hit, because the first contact with water is the surface of the sealant, so the surface is also firstly cured. After the surface cured, water from the surface has been into the inside, sealant is thus gradually cured from the surface to the inside. The longer the curing time is, the thicker the cured layer is. The thicker the sealant, the longer time it takes to fully cure, such as 10mm thick glue, usually need more than a week to fully cure. 

The two-component sealant is carried out by chemical reactions between components A and B. Separate sealed storage of components A and B is stable, as soon as components A and B are mixed, they start to react, so components A and B should be used immediately after mixing. Two-component curing reaction does not need water in the air to participate in, so its curing is carried out by the internal and the surface at the same time, the complete curing time is unrelated to the thickness of the glue, so the reaction is unrelated to whether the contact with the air, as long as the A and B components mixed together, even in a closed state will be cured.

The following are several concepts of sealant curing performance:

Surface dry: sealant is paste, with fingers or other materials to contact its surface, glue will adhere to the finger or material. After the sealant is hit, the surface contact with water begins to solidify the crust, when the epidermis is formed, and then contact the surface with fingers or materials, there will be no glue adhesion on the finger or material. This is called the surface stem.

Surface dry time: sealant from the container to start counting, to its surface dry time required is the table dry time.

Degluing: after the sealant surface is dry, contact the surface with the finger, although there is no glue adhesive on the finger, but you can still feel a certain adhesion between the glue surface and the finger, this phenomenon is called not degluing. This is the adhesive surface curing reaction has not been fully performed. With the extension of time, it will further cure, until the surface of a certain elasticity and strength of the skin, touch with the fingers feel dry, no sense of adhesion, we call it antisticking.

Degluing time: sealant from the container to start counting, to its surface degluing time is needed to degluing time. 

A Silicone building sealant is mainly composed of base glue, filler, crosslinking agent, catalyst and other additives. The base glue is the basic material of sealant, which determines the performance of sealant. The base rubber is 107 RT-silicone rubber, the chemical structure is hydroxyl-terminated polydimethylsiloxane, the filler is some inorganic powder, such as silica, calcium carbonate, heavy calcium, etc., the role of the filler is to provide strength, hardness, rheological properties, etc. Crosslinking agent and catalyst is the sealant curing system, sealant is through the base glue and crosslinking agent and catalyst and water in the air reaction from the liquid state to elastomer.
 
The production process of sealant is the process of mixing the various components of sealant. The usual production method is to mix the base material and filler with a kneader and, if necessary, with a grinder, and then use a planetary machine to mix the cross-linking agent, catalyst and other additives evenly under vacuum. 

Compared with other kinds of sealant, silicone building sealant has good elasticity, good resistance to high temperature and good flexibility at low temperature, good weather resistance, good ozone resistance, good uv resistance performance, long service life, but organic silicon costs are relatively high, usually is a bit more expensive than other types of sealant, strength especially the tensile strength is not very good. There is information about that the water resistance of polyurethane sealant is better than silicone sealant, and the oil resistance polysulfide sealant is also better than silicone sealant.