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What is hollow glass? What's the difference with ordinary glass?
DATE：2023-08-23
First, what is insulating glass
Concept:
Insulating glass is composed of two or more pieces of glass, separated and sealed by spacer bars to form a unit, with one or more gas spacer layers in the middle, and air or inert gas is injected inside. Insulating glass is a kind of glass deep processing products, is a kind of excellent performance, widely used energy-saving products.
Basic performance:
It has excellent thermal insulation, thermal insulation, sound insulation and anti-frost fog performance.
Categories:
Common hollow tempered glass, hollow laminated glass, hollow low-e glass in doors and Windows.
The main manufacturing process of insulating glass includes glass cutting → glass edging → glass cleaning → spacing bar assembly → closing → sealing, which is mostly carried out by equipment.
Second, insulating glass production process
Glass cutting
The two pieces of glass (which can be tempered glass, float glass, Low-e glass) used to make the sealing unit are measured and cut by hand or by an automatic cutting table. When cutting glass, the use of automated CNC equipment can reduce errors and improve the overall efficiency and thus reduce costs.
Glass cleaning
Glass cleaning generally adopts equipment cleaning method. Before cleaning, it is necessary to check the surface quality of the glass and meet the requirements before cleaning. Need to dry after cleaning, do not allow water stains on the surface of the glass. The cleaned glass should be finished within 1 hour.
Spacer assembly
Once the cleaned glass is ready, you need to use spacer strips to connect two or more glass units into a single unit. Glass and spacer bars are spacer components located around the edge of the glass. The spacer bar is filled with desiccant to absorb excess water in the glass cavity. The desiccant should be made of 3A molecular sieve from regular manufacturers and used within 24 hours after opening.
lamination
The composite is to synthesize two or more pieces of glass into a unit (hollow glass unit), and more equipment is used for the composite. The combined film has extremely high environmental requirements, and the winter temperature is required to be 10 to 20 degrees, and the summer temperature is required to be 20 to 30 degrees. The humidity must be less than 20%RH. Note that the edges of the glass should be aligned.
seal
Apply butyl glue on both sides of the spacer strip, assemble the spacer strip between two pieces of glass, and apply polysulfide glue or silicone structural glue on the outside. Butyl adhesive has low permeability and can prevent water vapor from entering the glass cavity, but its bonding ability is poor. Polysulfide adhesive has high permeability and good bonding ability, and can be used with butyl adhesive to make the life of empty glass reach more than 20 to 30 years. If only butyl glue or polysulfide glue is used, then the life of insulating glass will be greatly reduced, and it can only reach about 5 years.
Three, hollow glass structure composition
In general, insulating glass is composed of glass, spacer, desiccant, air layer or inert gas layer, sealant these parts.
1. Spacer bar
Functions:
The spacer bar connects two or more glass units into a whole, provides side sealing and stability for the insulating glass, affects the thermal insulation performance of doors and Windows, and is also related to the generation of condensation. It can be said that it is one of the indispensable materials for the production of insulating glass.
Categories:
In the "insulating glass spacer bar Part III: Warm edge spacer bar" (JC/T 2069-2018), it is stipulated that the thermal conductivity factor of the spacer bar is not greater than 0.007W/K, the spacer bar is called the warm edge spacer bar, and on the contrary, it is called the cold edge spacer bar.
Cold edge spacer: aluminum spacer
Warm edge spacer: stainless steel spacer, TGI stainless steel composite spacer, flexible spacer.
TGI stainless steel composite spacer is made of stainless steel and polypropylene composite. The use of warm edge spacers in cold areas can improve the anti-condensation performance of doors and Windows more effectively.
Process:
Common integrated bending process and corner splicing process in the door and window market, generally speaking, integrated bending is carried out by equipment, and the quality is relatively controllable.
One piece bending is more beautiful than the corner plug appearance, and its price is relatively higher, but it has little impact on the overall price of doors and Windows.
2, desiccant
Categories:
Class A desiccant: 3A molecular sieve.
Class B desiccant: spherical dry material with attapulgite as the main material.
Functions:
The main function of desiccant is to absorb the moisture and organic matter in the hollow glass cavity, so that the hollow glass will not be dewable even at minus 40 degrees.
Why choose 3A molecular sieve:
Molecular sieves have many pores with uniform pore size and neatly arranged pores in structure. Molecular sieves with different pore sizes separate molecules of different sizes and shapes. It has high adsorption capacity, strong selectivity and high temperature resistance.
Class B desiccant is mainly made of attapulgite and calcium chloride processing, because calcium chloride is corrosive, so processed into desiccant, water molecules, after a period of adsorption, the skin falls off, corrosive substances flow out, will corrode the aluminum strip and sealant, resulting in the failure of insulating glass.
3. Inert gas
Types and options:
The inert gases used in insulating glass are argon (Ar), Krypton (Kr), xenon (Xe).
Argon is the most ideal inert gas material for insulating glass air spacer.
Functions:
1, not only can effectively protect the oxidation of Low-E glass coating layer, but also improve the thermal insulation performance of glass.
This is because the off-line Low-E coating is easy to oxidize with oxygen in the air and lose its functionality. The inert gas argon has the characteristic of low activity, and its outer layer is saturated with electrons, which is difficult to react with other molecules. As a result, argon does not react chemically with the off-line Low-E coating, rendering the coating ineffective. In general, off-line Low-E glass needs to be used in conjunction with the inert gas argon.
2, for large glass and has the effect of preventing glass self-priming.
The area of the insulating glass is more than 2.5m2 of large glass, because of the large area, the middle of the insulating glass is prone to internal suction phenomenon, after filling the inert gas (more than 80%), because the pressure in the hollow glass chamber is greater than the outside of the chamber, so as to solve the concave phenomenon in the middle of the large area of insulating glass.
The initial aerated concentration of inert gas should not be less than 90%; Inert gas filling is an additional item that needs to be negotiated with the merchant when purchasing doors and Windows.
4. Sealant
Apply butyl glue on both sides of the spacer strip, assemble the spacer strip between two pieces of glass, and apply polysulfide glue or silicone structural glue on the outside.
Butyl adhesive: Low permeability, can prevent water vapor into the glass cavity, but its bonding ability is poor.
Polysulfide adhesive: high permeability, but good bonding ability, and butyl adhesive used together, can make the insulating glass life of more than 20 to 30 years.
If only butyl glue or polysulfide glue is used, then the life of insulating glass will be greatly reduced, and it can only reach about 5 years.
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