Insulated glass has been widely used in buildings as an energy-saving transparent structural member for building exterior walls. It also has many applications in other industries such as trains, airplanes, refrigeration equipment, greenhouses and other industries. Because the production process does not pay enough attention to the sealing of the insulating glass, it is very easy to cause the sealing failure of the insulating glass and lose the energy-saving performance of the insulating glass.

 The direct reason that affects the effective use time of insulating glass is the speed of moisture accumulation in the middle layer. There are many factors that affect the speed of moisture accumulation in the middle layer, such as material properties, manufacturing processes and controls, installation methods, environmental aging, etc. The dew point of insulating glass refers to the temperature when the air humidity sealed in the air layer reaches a saturated state. Below this temperature, the water vapor in the air layer will condense into liquid or solid water.

 The higher the water content, the higher the dew point temperature of the air. When the temperature of the inner surface of the glass is lower than the dew point of the air in the air layer, the water vapor in the middle cavity air will accumulate in the hollow glass, causing the dew point to rise. When the ambient temperature decreases and the temperature on the inner surface of the glass is lower than the dew point of the air layer, the water vapor inside the air layer will form condensation or frost on the inner surface of the glass (condensation occurs when the temperature on the inner surface of the glass is above 0 ℃, frost occurs below 0 ℃). Due to condensation or frost on the inner surface of the glass, it will seriously affect the perspective of the insulating glass and reduce the insulation effect of the insulating glass. At the same time, long-term condensation will cause mildew or alkali return on the inner surface of the glass, causing white spots. , seriously affecting the use of insulating glass. The dew point temperature of insulating glass is <-40°C. The dew point rises mainly due to the fact that external moisture enters the air layer and cannot be absorbed by the desiccant. The following three reasons can cause the dew point of insulating glass to rise:

 (1) Impurities in the sealant or capillary pores caused by incomplete compression during the injection process, under the action of pressure difference or concentration gradient inside and outside the air layer, water in the air oxygen flows or diffuses into the air layer through gas flow, increasing the moisture content in the air layer of the insulating glass.

 (2) Water vapor diffuses into the air layer through the polymer (butyl sealants are generally polymers). No polymer is absolutely airtight, and the same is true for sealants commonly used for insulating glass: butyl rubber, polysulfide rubber, silicone structural adhesives, etc. For these polymer materials, the presence of fugacity differences (pressure differences or concentration differences) on both sides of them constitute the driving force for isothermal diffusion of polymers. On the side with higher fugacity, polymer molecules enter the solid polymer due to adsorption of gas molecules (air and water), move and pass through the polymer chain array from the other side of the polymer - the side with lower fugacity. side release. For insulating glass sealants, the main diffuser is moisture in the air.

 (3) The effective adsorption capacity of desiccants is low. The effective adsorption capacity of insulating glass desiccant refers to the adsorption capacity of the desiccant after being sealed in the air layer. It is a function of factors such as the performance of the desiccant, air humidity, filling amount, and time spent in the air. The desiccant sealed in the air layer of insulating glass has two main functions. One is to adsorb the moisture sealed in the air during production, so that the insulating glass has a qualified initial dew point; The second is to continuously absorb the water that penetrates into the hollow layer through the sealant from the environment, maintaining a dew point that meets the usage requirements for the hollow glass at all times.Therefore, it is required that desiccants have strong adsorption capacity. If the adsorption capacity of the desiccant is poor and cannot effectively adsorb the water that enters the air layer through diffusion, it will lead to the accumulation of water in the middle cavity, increase the water pressure, and increase the dew point of the insulating glass.

Improving the service life of insulating glass and extending its effective use time to meet standard requirements should be controlled from various aspects such as material selection, processing and manufacturing, structural design, and installation.