Introduction to insulating glass

Insulating glass was invented by the Americans in 1865. It is a new type of building material with good heat insulation, sound insulation, beauty and application, and can reduce the weight of the building. It uses two (or three) pieces of glass and uses high strength and high strength. The airtight composite adhesive bonds the glass sheet and the aluminum alloy frame containing the desiccant to make high-efficiency sound-insulating and heat-insulating glass. Insulating glass has many properties superior to ordinary double-layer glass, so it has been recognized by countries all over the world. Insulating glass is to effectively support two or more pieces of glass to be evenly separated and bonded and sealed around the glass to form a dry gas between the glass layers. Space glassware. The main materials are glass, aluminum spacers, angle bolts, butyl rubber, polysulfide rubber, and desiccant.
Principles of heat and sound insulation
　　 There are three ways of energy transfer: radiation transfer, convection transfer and conduction transfer.
　　Radiation transfer
　　Radiation transfer is the transfer of energy in the form of radiation through rays, which include visible light, infrared and ultraviolet radiation, just like the transfer of solar rays. Reasonably configured hollow glass and reasonable thickness of the insulating glass spacer layer can minimize the transmission of energy through the form of radiation, thereby reducing energy loss.
Convective transfer
Convection transfer is due to the temperature difference between the two sides of the glass, which causes the air to drop on the cold side and rise on the hot side, resulting in air convection and loss of energy. There are several reasons for this phenomenon: one is the poor sealing between the glass and the surrounding frame system, causing the gas inside and outside the window frame to be directly exchanged to produce convection, resulting in energy loss; the other is the design of the internal space structure of the hollow glass Unreasonable, causing the gas inside the hollow glass to produce convection due to the temperature difference, driving energy exchange, resulting in energy loss; third, the temperature difference between the inside and outside of the window that constitutes the entire system is large, resulting in the temperature difference between the inside and outside of the hollow glass. Larger, with the help of cold radiation and heat conduction, the air first produces convection on both sides of the hollow glass, and then passes through the hollow glass as a whole to form a loss of energy. Reasonable hollow glass design can reduce the convection of gas, thereby reducing the convective loss of energy.
Conduction
Conduction transfer is through the movement of object molecules to drive energy to move, and achieve the purpose of transfer, just like using an iron pan for cooking and soldering things with an electric soldering iron, and hollow glass conducts energy transfer through the glass and its interior. The air is done. We know that the thermal conductivity of glass is 0.77W/mk. The thermal conductivity of air is 0.028 W/ mk. It can be seen that the thermal conductivity of glass is 27 times that of air, and the presence of active molecules such as water molecules in the air affects the energy transfer and convection transfer performance of hollow glass. The main factor, thus improving the sealing performance of insulating glass, is an important factor in improving the thermal insulation performance of insulating glass.
Anti-condensation, reduce cold radiation and safety performance
Since there is a desiccant that can adsorb water molecules inside the hollow glass, the gas is dry, and when the temperature is lowered, condensation will not occur inside the hollow glass. At the same time, the dew point on the outer surface of the hollow glass will also increase. high. For example, when the outdoor wind speed is 5m/s, the indoor temperature is 20°C, and the relative humidity is 60%, 5mm glass starts to condense when the outdoor temperature is 8°C, while 16mm (5+6+5) insulating glass under the same conditions, Condensation occurs when the outdoor temperature is -2℃, and the 27mm (5+6+5+6+5) three-layer insulating glass starts to condense when the outdoor temperature is -11℃.
Due to the good heat insulation performance of insulating glass, the temperature difference between the two sides of the glass is large, and the effect of cold radiation can also be reduced; when the outdoor temperature is -10℃, the temperature in front of the indoor single-layer glass window is -2℃ and the hollow The temperature in front of the glass window is 13℃; in the same house structure, when the outdoor temperature is -8℃ and the indoor temperature is 20℃, the cold radiation area of ​​3mm ordinary single-layer glass accounts for 67.4% of the indoor space, and double-layer Insulating glass (3+6+3) is 13.4%.
The use of insulating glass can improve the safety performance of the glass. In the case of using the same thickness of the original glass, the wind pressure strength of the insulating glass is 1.5 times that of the ordinary single glass.
1. Ordinary insulating glass
basic structure
Hollow glass
Insulating glass is composed of two or more layers of flat glass. Use high-strength and high-air-tight composite adhesives around to bond and seal two or more pieces of glass with sealing strips and glass strips. The middle is filled with dry gas, and the frame is filled with desiccant to ensure the dryness of the air between the glass sheets. Various original glass sheets with different properties can be selected according to requirements, such as colorless transparent float glass patterned glass, heat-absorbing glass, heat-reflective glass, laminated glass, tempered glass, etc. and frames (aluminum frame or glass strip, etc.), It is made by cementing, welding or welding.
Insulating glass can use 3, 4, 5, 6, 8, 10, 12mm thick slices of original glass, and the thickness of the air layer can use 6, 9, 12mm intervals.
(1) Technical requirements for insulating glass
The provisions of GB11944-89 are excerpted as follows:
① Material
a. The glass can be flat glass, laminated glass, patterned glass, heat-absorbing glass, coated heat-reflective glass, tempered glass, etc. Float glass should meet the first-class and first-class products specified in GB11614, laminated glass should meet the requirements of GB9962, and tempered glass should meet the requirements of GB9963.
b. The sealant should meet the following requirements. The color difference between the first and second sealant components used should be clear; the validity period is more than half a year; the second sealant for the hidden frame curtain wall must be silicone sealant; it must be hollow Glass performance requirements.
c. Spacer frame: When using aluminum spacer frame, it must be decontaminated and anodized.
d. The quality, specification and performance of the desiccant must meet the requirements of insulating glass manufacturing and performance.
②See the table for the allowable deviation of the length and width of the insulating glass.
Allowable deviation of length or width (mm)
<1000±2
1000-2000±2.5
>2000-2500±3
③The allowable deviation of the thickness of insulating glass is shown in the table.
Nominal thickness of glass thickness (mm) allowable deviation (mm)
≤6<18±1
18-25±1.5
>6>25±2
Note: The nominal thickness of insulating glass is the sum of the thickness of the two pieces of glass and the thickness of the spacer frame.
④The allowable deviation of the two diagonals of insulating glass is shown in the table.
Diagonal length (mm) allowable deviation (mm)
<10004
≥1000-25006
⑤ Width of insulating glass sealant: The width of a single sealant layer shall be calculated and determined, and its minimum width shall be 10±2mm, and the width of the outer sealant of a double seal shall be determined by calculation, and its minimum width shall be 5-7mm.
⑥Appearance: The inner surface of the hollow glass must not have stains and adhesive splashes that hinder the perspective.
⑦Performance requirements: The sealing, dew point, ultraviolet radiation, climate cycle, high temperature and high humidity performance of insulating glass are tested according to GB7020, and must meet the requirements of the following table.
·When the test pressure is lower than the ambient air pressure by 10±0.5KPa, the thickness increase must be ≥0.8mm. After the pressure is maintained at 2.5, the thickness increase deviation <15% means leakage. All samples are not allowed to leak.
·The dew point reduces the temperature of the dew point meter to ≤-40 degrees, and the dew point meter is in contact with the sample surface for 3 minutes. There is no condensation or frost on the inner surface of the sample.
·Ultraviolet radiation UV radiation for 168h, there should be no traces of fogging and pollution on the inner surface of the sample
·Climate cycle and high-temperature and high-humidity climate test were subjected to 320 cycles, high-temperature and high-humidity tests were subjected to 224 cycles, and the dew point test was performed after the test. A total of 12 samples, at least 11 without condensation or frost
When insulating glass is selected for the hidden frame curtain wall, the second sealant of the insulating glass must be silicone sealant, and it must be compatible with the sealant used for structural glass assembly, that is, the two must use mutually compatible sealants. When a certain silicone sealant is used for structural assembly, it is best to order the insulating glass sealant layer with the same factory silicone sealant.
(2) Performance of insulating glass
Hollow glass
The thermal conductivity of glass is 27 times that of air. As long as the insulating glass is sealed, the insulating glass has the best heat insulation effect.
(3) Features of insulating glass
There is a certain cavity between the glass and the glass of the hollow glass. Therefore, it has good heat preservation, heat insulation, sound insulation and other properties. If various light-diffusing materials or dielectrics are filled between the glass, better effects such as sound control, light control, and heat insulation can be obtained.
(4) Uses of insulating glass
Insulating glass is mainly used in buildings that require heating, air conditioning, noise prevention or condensation, and no direct sunlight and special light. It is widely used in residences, restaurants, hotels, office buildings, schools, hospitals, shops and other occasions that require indoor air-conditioning. It can also be used for doors and windows of trains, automobiles, ships, and freezers.
Insulating glass is mainly used for outer glass decoration. Its optical performance, thermal conductivity, and sound insulation coefficient should all comply with national standards.
2. High-performance insulating glass
High-performance insulating glass is different from ordinary insulating glass. In addition to enclosing dry air between the two layers of glass, a special metal film with good thermal performance is also applied to the side of the outer glass intermediate air layer. It can cut off the considerable energy from the sun into the room and play a greater heat insulation effect.
(1) Features of high-performance insulating glass
①Greater energy saving effect
High-performance insulating glass, due to a special metal film, can achieve a shielding coefficient of 0.22-0.49, which reduces the load of indoor air conditioning (air-conditioning). The heat transfer coefficient is 1.4-2.8W (m2.K), which is better than ordinary insulating glass. It also exerts great efficiency in reducing the load of indoor heating. Therefore, the larger the window is opened, the more obvious the energy-saving effect
②Improve the indoor environment
High-performance insulating glass can intercept considerable energy from the sun into the room, thus preventing discomfort caused by radiant heat and reducing dazzling caused by sunset sunlight.
③Rich tones and artistry
High-performance insulating glass has a variety of colors, which can be selected according to needs to achieve a more ideal artistic effect.
④Use of high-performance insulating glass
It is suitable for office buildings, exhibition rooms, libraries and other public facilities and special buildings that require constant temperature and humidity, such as computer rooms, precision instrument workshops, and chemical factories. In addition, it can also be used for sun protection and anti-dazzling places.
Note: Dry air is enclosed in the hollow glass. Therefore, according to changes in temperature and air pressure, the internal air pressure also changes, but only a small deformation occurs on the glass surface. In addition, slight warpage may occur during manufacturing, and distortion may also be formed during construction. Therefore, including such factors, sometimes there are corresponding changes in reflection, which should be paid attention to. Different colors have different reflections.
(2) Performance of high-performance insulating glass
Gold, copper and silver metal coatings have high reflectivity in the mid-to-far infrared region, that is, when the wavelength range is greater than 4μm. If the metal coating has a typical thickness, the total reflectivity can reach 90%-95%, and the high infrared reflectivity is equivalent to the low emissivity (Low-e), which will reduce the radiation conversion between the inner and outer glass plates of the hollow glass module. Correspondingly, compared with a standard hollow glass member with an air layer of 12mm, the thermal insulation value can be from 0.3W/(m2.K). In addition, if the air in the component is replaced by heavy gas, the insulation value is 1.4W/(m2.K). By reducing the thickness of the metal layer, the light transmittance can be increased to about 60%-60%. This kind of extremely thin coating has a very good protective effect, while still having a high infrared reflectance value, in the range of 85% or 75%. The air layer is 12mm filled with heavy gas in the middle, and the insulation value of the coating can reach 1.6-1.9W/(m2.K).
The development of the glass industry
The upgrading of the consumption structure of residents, the encouragement of independent innovation by enterprises, the construction of new rural areas and the process of urbanization will all ensure that the growth trend of the domestic market for glass products in the medium and long term remains unchanged. With the development of construction, automobile, decoration, furniture, information industry technology and other industries and the improvement of people's requirements for living space environment, functional processed products such as safety glass and energy-saving insulating glass have been widely used. The supply and demand pattern and consumption structure of flat glass are changing.
The development of the glass industry is related to many industries in the national economy, and the glass industry plays a positive role in promoting the development of the entire national economy. Therefore, the "Eleventh Five-Year Plan" also put forward specific requirements for the development of the glass industry. Various laws and regulations have also been promulgated to regulate the healthy development of the glass industry. Under the new situation, the glass industry must change the growth mode and effectively adjust the industrial structure in accordance with the requirements of the scientific development concept, in order to promote the healthy development of the industry.
Key points of design selection
1 Trough aluminum double-pass sealing insulating glass uses butyl rubber for the first sealing, which has extremely low water vapor transmission rate; the second sealing rubber mainly includes polysulfide rubber and silicone rubber. The water vapor transmission rate of polysulfide glue is lower than that of silicone glue, but its UV resistance is not as good as silicone glue, so it is suitable for windows or framed glass curtain walls (because the aluminum frame can shade and avoid direct sunlight); silicone glue is suitable for Hidden frame glass curtain wall, its anti-ultraviolet ability and strength are higher than polysulfide glue. When the building has higher decorative requirements for insulating glass, milky white or transparent silicone glue can be used. For wooden windows, silicone glue should not be used as the second seal. Because of its poor resistance to wood preservatives, the sealant will be damaged due to migration.
2 The partition aluminum frame should adopt the continuous long tube elbow type, and the joints should be sealed with butyl rubber; if the partition aluminum frame adopts the four-corner plug-in type, the joints of the partition should also be sealed with butyl rubber. Insulating glass, the service life is not as good as the former. When the second sealant of insulating glass adopts silicone glue, the insulating glass with four-corner plug-in spacer aluminum frame should not be used.
3 Because the sealant is used for sealing, it should not be used at a temperature of 70°C or higher, otherwise it will greatly affect the service life of the insulating glass.
4 The change in the internal pressure of the air layer of insulating glass will deform the glass and cause image distortion. Therefore, when insulating glass is used at an altitude of 1000m or above, the air pressure of the air layer must be adjusted, and the glass supplier should be consulted when placing an order.
5 The thermal insulation performance of a window is closely related to the material of the window frame, so a window frame material with good thermal insulation performance should be selected.
6 If it is used as a lighting ceiling, the indoor side glass should be laminated or explosion-proof film.
7 Low-E insulating glass, the membrane surface is located on the second or third surface, which should be selected according to the design requirements. If the designed hollow glass must be in the form of large and small pieces, the membrane surface must be placed on the third side.
8 The maximum allowable area of ​​the four-sided supporting insulating glass is 1.5 times the maximum allowable area of ​​the insulating glass calculated based on the thickness of two single glass sheets.
9 The following technical performance requirements should be put forward during building design: thermal insulation performance, thermal insulation performance, sound insulation performance, lighting performance, sealing performance, and weather resistance.
Insulating glass warm edge system
1) Warm edge sealing system for thermoplastic materials
(1) Insulating glass used for doors and windows can be sealed with a single rubber strip sealing system as a single-channel sealing method, which can ensure that the insulating glass has a service life of more than 10 years. Insulating glass used for curtain walls must be sealed with structural glue on the outside of the rubber strip as a secondary sealant to ensure that the insulating glass has sufficient structural strength.
(2) It is especially suitable for the production of special-shaped hollow glass and gas-filled hollow glass, especially suitable for special-shaped gas-filled Low-E hollow glass. Because the strip itself does not have volatile gas that adversely affects the Low-E film, it can ensure Low-E hollow glass. Glass has a long service life.
(3) Super spacer strip type insulating glass
Insulating glass for windows can be sealed with hot melt butyl glue of sufficient depth on the outer side of the super spacer to ensure that the insulating glass sealing system has sufficient resistance to water vapor penetration. Insulating glass for curtain walls must be sealed with a sufficiently deep third layer of structural glue outside the hot melt butyl glue to ensure that the insulating glass has sufficient structural strength and service life.
2) Warm-side partition system in the traditional sense
(1) U-shaped strip hollow glass
Insulating glass for windows can only use hot-melt butyl glue as a separate sealing material. Insulating glass for curtain walls must be sealed with structural glue of sufficient depth on the outside of the hot melt butyl glue to ensure sufficient bonding strength and service life. When used as gas-filled insulating glass, you must pay great attention to the sealing of the U-shaped strip joint.
(2) Glue-injected aluminum hollow glass
It is basically the same as the traditional aluminum strip insulating glass. It should be noted that because this product uses a heat insulation material to bond between two aluminum strips, the thickness of the entire aluminum strip must exceed 12mm to achieve it. Due to the characteristics of the material, it is difficult to achieve bend processing at the corners, so when designing the use of inflatable insulating glass, it is necessary to pay attention to the sealing control at the corners.