The insulating glass was invented by Americans in 1865. It is a good heat insulation, sound insulation, beautiful and applicable, and can reducebuildingDeadweightNew building materials。
It uses two (or three) piecesGlass, using high strength and high air tightness composite binderaluminium alloyFrame bonding, high efficiency sound insulationInsulating glass。The insulating glass is superior to the ordinary double glass in many properties, so it has been recognized by all countries in the worldSeptumThe glass products with dry gas space between the glass layers are bonded and sealed at the periphery.The main materials are glass, warm edge spacer strip, corner boltbutyl rubber , polysulfide adhesivedesiccant。
Chinese name
Hollow glass
Foreign name
Double-glazed
Invention time
1865
Features
Good optical performance;Thermal insulation;Anti condensation, etc
The insulating glass is composed of two or more layers of flat glass.Two or more pieces of glass are bonded and sealed with sealing strips and glass strips with high-strength and high air tightness composite adhesive around.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.According to the requirements, various glass sheets with different properties can be selected, such as colorless transparent float glass embossed glass, heat absorbing glass, heat reflecting glass, wired glass, tempered glass, etc., and the frame (aluminum frame or glass strip, etc.), which are made by cementation, welding or fusion.
Its structure is as shown in the figureDouble insulating glassprofile.The insulating glass can be 3, 4, 5, 6, 8, 10, 12mm thick original sheet glass, and the air layer thickness can be 6, 9, 12mm interval.
The heat conductivity of glass is 27 times that of air. As long as the insulating glass is sealed, the insulating glass will have the best heat insulation effect.
There is a certain space between the glass and the insulating glass.The frame is filled with desiccant to ensure the dryness of the air between the glass sheets.The distance between two layers of insulating glass is generally 8mm.
High performance insulating glass is different from ordinary insulating glass. In addition to sealing dry air in the middle of the two layers of glass, a special metal film with good thermal performance should be coated on the side of the middle air layer of the outer glass.It can cut off the considerable energy from the sun to the room, playing a greater heat insulation effect.
principle
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Because there is a desiccant that can absorb water molecules inside the insulating glass, the gas is dry, and when the temperature drops, condensation will not occur inside the insulating glass. At the same time, the dew point on the external surface of the insulating glass will also rise.For example, when the outdoor wind speed is 5m/s, the indoor temperature is 20 ℃, and the relative humidity is 60%, the 5mm glass starts to dew when the outdoor temperature is 8 ℃, while the 16mm (5+6+5) insulating glass starts to dew when the outdoor temperature is - 2 ℃ under the same conditions, and the 27mm (5+6+5+6+5) three-layer insulating glass starts to dew when the outdoor temperature is - 11 ℃.
There are three ways of energy transmission of insulating glass:radiationTransfer, convection transfer and conduction transfer.
Radiative transfer
Radiation transfer is the transfer of energy in the form of radiation through radiation, which includes visible light, infrared and ultraviolet radiation, just like the transfer of solar light.Reasonable configuration of insulating glass and reasonable thickness of insulating glass interlayer can minimize the transmission of energy through radiation, thus reducing energy loss.
Convection transfer
Convective transfer is due to the temperature difference on both 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 energy loss.There are several reasons for this phenomenon: First, the poor sealing between the glass and the surrounding frame system results in the direct exchange of gas inside and outside the window frame to generate convection, resulting in energy loss;Second, the internal space structure of the insulating glass is designed unreasonably, resulting in the convection of the gas inside the insulating glass due to the effect of temperature difference, driving the exchange of energy, thus causing the loss of energy;Third, the temperature difference between the inside and outside of the windows that constitute the whole system is large, resulting in a large temperature difference between the inside and outside of the insulating glass. With the help of cold radiation and heat conduction, air first generates convection on both sides of the insulating glass, and then passes through the insulating glass as a whole, resulting in energy loss.Reasonable design of insulating glass can reduce the convection of gas, thus reducing the convection loss of energy.
Conductive transmission
The conduction transmission is to drive the energy to move through the movement of object molecules to achieve the purpose of transmission, just like using an iron pan to cook food and using an electric soldering iron to weld things. The conduction transmission of energy by insulating glass is completed through the glass and the air inside.As we know, the thermal conductivity of glass is 0.77W/mk.The thermal conductivity of air is 0.028 W/mk, which shows that the thermal conductivity of glass is 27 times that of air. The presence of active molecules such as water molecules in the air is the main factor affecting the energy transmission and convection transmission performance of insulating glass. Therefore, improving the sealing performance of insulating glass is an important factor to improve the thermal insulation performance of insulating glass.[1]
characteristic
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Hollow glass
① Great energy-saving effect
High performance insulating glass, with a special metal film, can achieve a shielding coefficient of 0.22-0.49, reducing the load of indoor air conditioning (cooling).The heat transfer coefficient is 1.4-2.8W (m2. K), which is better than ordinary insulating glass.It also plays an important role in reducing indoor heating load.Therefore, the larger the window is opened, the more obvious the energy-saving effect will be.
② Improve indoor environment
High performance insulating glass can intercept considerable energy from the sun to the room, thus preventing discomfort caused by radiant heat and reducing glare caused by sunset sunlight.
③ Rich colors and artistry
High performance insulating glass has a variety of colors, which can be selected according to needs to achieve better artistic effect.
④ Use of high performance insulating glass
Applicable to office buildings, exhibition rooms, libraries and other public facilities, as well as computer rooms, precision instrument workshops, chemical plants and other requirementsConstant temperature and humiditySpecial buildings.In addition, it can also be used to prevent sunscreen and glare at sunset.
Precautions: The insulating glass is sealed with dry air in the middle, so the internal air pressure changes according to the changes of temperature and air pressure, but only a small deformation occurs on the glass surface.In addition, slight warpage may occur during manufacturing, and distortion may also occur during construction.Therefore, including such factors, sometimes there are corresponding changes in reflection, which should be paid attention to.The reflection varies with different colors.
Gold, copper and silverMetallic coatingIn the middle and far infrared region, that is, when the wavelength range is greater than 4 μ m, the reflectivity is very high.If the metal coating is of 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 of the inner and outer glass plates of the insulating glass module. Correspondingly, compared with the standard insulating glass component with the air layer of 12mm, its thermal insulation value can range from 0.3W/(m2. K).In addition, if the air in the component is replaced by heavy gas, its insulation value is 1.4W/(m2. K).By thinning the thickness of the metal layer, the light transmittance can be increased to about 60% - 60%.This extremely thin coating has a very good protective effect, while still having a very high infrared reflectance value, in the range of 85% or 75%.The air layer is 12mm, filled with heavy gas, and the insulation value of the coating can reach 1.6-1.9W/(m2. K).
Main purpose
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Insulated glass is mainly used on buildings that need heating, air conditioning, noise prevention or condensation, and no direct sunlight and special light.It is widely used in residential buildings, restaurants, hotels, office buildings, schools, hospitals, shops and other places where indoor air conditioning is required.It can also be used for doors and windows of trains, cars, ships, freezers, etc.[2]
Insulating glass is mainly used for decoration of outer glass.Its optical performance, thermal conductivity and sound insulation coefficient shall comply with national standards.The insulating glass with reasonable structure and standard design can play its role in heat insulation, sound insulation, anti-theft and fire prevention.The vacuum double tempered glass can reach the laboratory standard even more!There are also insulating glass with inert gas and colored pigment gas added on the market, as well as beauty bars added for reinforcement and decoration.
Function of insulating glass aluminum spacer: aluminum is called active metal element, but its surface will form a dense oxide film in the air, making it unable to continue to act with oxygen and water.At high temperature, it can react with oxygen to release a lot of heat. With this high reaction heat, aluminum can replace metal from other oxides (thermite method).
Common classification
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1、 Float insulating glass
2、 Tempered insulating glass
3、 Coated insulating glass
4、 LOW-E insulating glass
Common insulating glass: 5+9A+5 double-layer insulating glass.Shenghai Doors and Windows explained that the "5" here means the thickness of the glass is 5mm, the "9" means the hollow part is 9mm, and the letter A is the abbreviation of air.There are also models 5+15A+5, 5+22A+5, 5+27A+5, 5+32A+5 and so on in the market. It is easy to understand the meaning of the above.
Safety performance
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Hollow glass
Due to the good thermal insulation performance of insulating glass, the temperature difference between the two sides of the glass is large, which can also reduce the effect of cold radiation;When the outdoor temperature is - 10 ℃, the temperature in front of the indoor single glass window is - 2 ℃ and the temperature in front of the insulating glass window is 13 ℃;In the same building 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, while that of double insulated glass (3+6+3) is 13.4%.
The use of insulating glass can improve the safety performance of the glass. When the original piece of glass with the same thickness is used, the wind pressure strength of the insulating glass is 1.5 times that of ordinary single glass.
Development prospect
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Hollow glass
Upgrading the consumption structure of residents, encouraging independent innovation of enterprises, new rural construction and urbanization process will ensure that the medium and long-term demand growth trend for glass products in the domestic market will remain 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 processing products such as safety glass, 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 connected with many industries of the national economy, and the glass industry plays a positive role in promoting the development of the entire national economy.Therefore, the 11th Five Year Plan also puts forward specific requirements for the development of glass industry.Various laws and regulations have also been promulgated to regulate the healthy development of the glass industry.In the new situation, the glass industry must change its growth mode and effectively adjust its industrial structure in accordance with the requirements of the Scientific Outlook on Development in order to promote the healthy development of the industry.[3]
Key points of design
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1 groove aluminum double sealing insulating glass, butyl rubber for the first sealing, with extremely lowWater vapor transmittance；The second sealant mainly includes polysulfide adhesive and silicone adhesive.Polysulfide glue has less water vapor transmission than silicone glue, but its UV resistance is not as good as silicone glue, so it is suitable for windows or framesglass screen wall(Because the aluminum frame can shade the sun, avoid direct sunlight);Silicone glue is suitable forHidden frame glass curtain wallIts UV resistance and strength are higher than those of polysulfide adhesive.When buildings have high decorative requirements for insulating glass, milky white or transparent silicone glue can be used.Wooden windows should not use silicone glue as the second seal. Because of its poor resistance to wood preservatives, the sealant will be damaged due to migration.
2. The interval aluminum frame should be of continuous long pipe corner type, and the joints should be sealed with butyl rubber;If the spacer aluminum frame adopts the four corner plug-in type, its joints should also be sealed with butyl rubber. The service life of the insulating glass made of this type is not as long as that of the former.When the second sealant of insulating glass is silicone glue, the insulating glass with four corner plug-in aluminum frame shall not be used.
3 Since sealant is used for sealing, it should not be used at a temperature of 70 ℃ or higher, otherwise the service life of insulating glass will be greatly affected.
4. The change of the internal pressure of the air layer of the insulating glass will deform the glass and cause image distortion. Therefore, when the insulating glass is used at an altitude of 1000m or above, the air pressure of the air layer must be adjusted. When placing an order, it should be discussed with the glass supplier.
5 The thermal insulation performance of windows is closely related to the window frame materials, so the window frame materials with good thermal insulation performance should be selected.
6 If it is used as a daylighting ceiling, the interior side glass should use sandwich or explosion-proof membrane.
7 For Low-E insulating glass, the membrane surface is located on the second or third side, which shall be selected according to the design needs.If the designed insulating 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 side supporting insulating glass is 1.5 times the maximum allowable area of the insulating glass calculated according to the thickness of two single glass sheets.
9 The following technical performance requirements shall be put forward during architectural design: thermal insulation performance, thermal insulation performance, sound insulation performance, daylighting performance, sealing performance, weather resistance performance.
Warm edge sealing system
Hollow glass
(1) The insulating glass used for doors and windows can be sealed in a single way by using a separate strip sealing system, which can ensure the service life of the insulating glass to be more than 10 years.Insulated glass for curtain wall must be coated with
The outer sealing structural adhesive of the strip is used as the secondary sealant to ensure that the insulating glass has sufficient structural strength.
(2) It is particularly suitable for making special-shaped insulating glass and inflatable insulating glass, especially for special-shaped inflatable Low-E insulating glass. Because the adhesive strip itself has no volatile gas that has adverse effects on Low-E film, it can ensure that Low-E insulating glass has a long service life.
(3) Super spacer insulating glass
The insulating glass for windows can be sealed with hot-melt butyl rubber of sufficient depth on the outside of the super spacer strip to ensure that the insulating glass sealing system has sufficient water vapor permeability resistance.The insulating glass used for curtain wall must be sealed with a third layer of structural adhesive with sufficient depth outside the hot-melt butyl adhesive to ensure that the insulating glass has sufficient structural strength and service life.
Traditional warm edge spacing system
(1) U-shaped strip insulating glass
The insulating glass for windows can only use hot-melt butyl rubber as a separatesealing material use.The insulating glass used for curtain wall must be sealed with structural adhesive with sufficient depth outside the hot-melt butyl adhesive to ensure sufficient bonding strength and service life.When used as an inflatable insulating glass, attention must be paid to the sealing at the U-shaped strip joint.
It is basically the same as the traditional aluminum strip insulating glass. It should be noted that this product is used between two aluminum stripsThermal insulation materialTherefore, the thickness of the entire aluminum strip must be more than 12mm to achieve bonding. Due to the characteristics of the intermediate insulation material, it is difficult to achieve corner treatment at the corner. Therefore, attention should be paid to the sealing control at the corner when designing and using the inflatable insulating glass.
process conditions
1. According to the wind load, control the specified size of the opening and the thickness of the required glass.
2. The insulating glass shall be made into a structure, and the size shall not be changed. The opening for assembling the insulating glass shall be rectangular and vertical, and the accuracy of its specification shall be checked.
3. The insulating glass is not allowed to have any surface covered by paint or paper, because this will cause local overheating and breakage.
4. The insulating glass shall not be in direct contact with the frame.
5. The installation requirements shall vary according to the type of materials used to inlay the insulating glass.
Main problems
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As an energy-saving building material, insulating glass is widely used because of its good heat insulation and sound insulation performance.At the same time, the quality of insulating glass is required to be higher and higher.It is understood that the biggest quality problem of insulating glass is the condensation of air layer in use, and the reason for the condensation of air layer is that the dew point of air layer increases during use.Therefore, controlling the dew point of insulating glass is the key to control the quality of insulating glass.
During the use of insulating glass, when the ambient temperature drops to the dew point in the dry air layer, the surface of the dry air layer will generate condensation or frost.The performance of insulating glass is affected by the condensation or frost on the inner surface of glass.If it is ensured that the air layer is not dewed above - 40 ℃, the insulating glass will not be dewed in the air layer during use.
Dew point of insulating glass refers to the temperature when the air humidity sealed in the air layer reaches saturation.Below this temperature, the water vapor in the air layer will condense into liquid water.It can be inferred that 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 moisture in the air will condense or frost on the inner surface of the glass.
The dew point rise of insulating glass is caused by the external moisture entering the air layer without being absorbed by the desiccant. There are three reasons that may cause the dew point rise:
(1) There are bubbles in the sealant, causing air moisture to enter.
(2) Water vapor diffuses into the air layer through the polymer.
(3) The effective adsorption capacity of desiccant is low.
control measures
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(1) Strictly control the production environment temperature
The production environment mainly affects the adsorption capacity and residual adsorption capacity.
(2) Reduce the diffusion of water through polymer
It mainly depends on the selection of sealant with low permeability coefficient to determine a reasonable sealing thickness and reduce the internal and external temperature difference of insulating glass (that is, control the production within a certain temperature range without making the temperature range too large).
(3) Reduce production process time
Try to reduce the contact time between the desiccant and the atmosphere, and reduce the loss of adsorption capacity so that the desiccant has a high adsorption capacity.
(4) Select appropriate aluminum profile
The air guide slot of its pores should be small to reduce the water absorption of molecular sieve during operation.
(5) Select suitable desiccant
Desiccant with high adsorption rate and long duration shall be selected.
It is believed that the quality of insulating glass will be obviously controlled through the control of material selection, processing, environment and other aspects.
Production process
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1 The heated glass should be pressed to the required thickness gradually by using multiple sets of rollers.Each group of pressing rollers shall be parallel to each other to ensure uniform thickness of pressed glass.
2 The temperature of the rubber strip at the outlet of the press shall be controlled at 40-55 ℃.
3. The sealing of composite adhesive strip insulating glass adopts three-step procedure, namely pressing, turning and kneading procedure, to complete the final sealing operation of insulating glass.
① Pressing: extrude the outer rubber strip along the vertical direction of the edge to another piece of rubber strip until the two pieces of rubber strips are completely fused together;
② Crank: smooth the excess glue along the space layer in the middle of the insulating glass, so that there is no excess glue outside;
③ Pinch: pinch the two pieces of glass inward to eliminate the gap caused by the outward separation of glass caused by pressing and turning.
Attention
① The temperature at which the rubber strip leaves the hot press;
② Sealing temperature, thickness, flatness and displacement of rubber strip;
③ Bonding integrity of sealing surface of adhesive strip;
④ Tightness of sealing.
the way to distinguish
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1. Filling inert gases argon and krypton
According to experts in the design and construction of energy-saving residential buildings, as far as a window is concerned, the heat loss in the house is mainly through the window frame conduction, glass radiation, the gap convection between the window leaf and the door frame, and so on, so the "insulating glass" came into being.In fact, "insulating glass" is not "empty". According to the technical requirements, the distance between two layers of insulating glass is generally 8mm. The test proves that if the distance of 8mm is completely vacuum, the atmospheric pressure will crush the glass.Therefore, qualified insulating glass.The interlayer, that is, the 8mm thick spacing space, must be filled with inert gases argon and krypton.After filling, the test shows that its K value (the limit value of heat transfer coefficient) can also decrease by 5% compared with that under vacuum, which means that the thermal insulation performance is better.
2. Confused double glazing on the market
In other words, if the interlayer of the insulating glass you purchased is really "empty", it undoubtedly means that its thermal insulation or thermal insulation and cold insulation performance is at best double glass, and the efficiency of thermal insulation and energy conservation is inevitably poor. Scientific testing has proved that qualified insulating glass can reduce the limit value of heat transfer coefficient k of ordinary window glass from 3.5 to 2.8,The decline of heat transfer performance can make the heat in the house not easy to dissipate.Most of the fake insulating glass in the market simply fix two pieces of glass together, and its thermal insulation performance is undoubtedly very poor.
3. Aluminium strip with holes between glasses
The "double glass" with poor heat insulation performance often causes fog and flowers in the interlayer, even mildew spots, due to the entry of air and moisture. Therefore, some enterprises often use the "processing" method of sandwiched aluminum strips with holes between two pieces of glass, and putting granular desiccant in the holes of aluminum strips, which actually only serves as a temporary cover up,It does not improve any heat insulation performance of the double glass, and the desiccant will still be exposed after a long time.
One of the tricks of "checking the body" is to check whether there is ice between the glasses in winter and whether there is water vapor in spring and summer.Of course, most of them are embedded with aluminum strips, which are often false vacuum.
technical parameter
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The provisions of GB11944-2002 are extracted as follows:
① Materials
a. The glass can be float glass, laminated glass, embossed glass, heat absorbing glass, coated glass, tempered glass, tempered and semi tempered glass for curtain wallTinted glassEtc.Float glass shall comply with GB11614, laminated glass shall comply with GB9962, and tempered glass shall comply with GB9963Heat-strengthened glass Comply with GB17841.Other types of glass shall conform to corresponding standards or shall be negotiated by both parties.
b. The sealant shall meet the following requirements:
Plastic sealant for insulating glass shall comply with relevant regulations;
The color difference between the components of the first and second sealant used shall be clear;Valid for more than half a year;
The second sealant for concealed frame curtain wall must beSilicone sealant；Must meet the performance requirements of insulating glass.
C Adhesive strip: adhesive strip made of plastic sealant containing desiccant and wavy aluminum strip, and its performance shall comply with corresponding standards.
c. Spacer frame: when using metal spacer frame, decontamination or chemical treatment shall be carried out.
d. The quality, specification and performance of the desiccant shall meet the corresponding standards.
② The allowable deviation of the length and width of insulating glass is as follows:
Allowable deviation of length or width (mm)
L<1000 ±2.0
1000≤L<2000 +2、-3
L≥2000 ±3.0
③ The allowable thickness deviation of insulating glass is as follows:
Note: The nominal thickness of insulating glass is the sum of the thickness of two pieces of glass and the thickness of the spacer frame.
④ The allowable deviation of two diagonal lines of insulating glass is shown in the table.
The difference between the diagonal of square and rectangular insulating glass shall not be greater than 0.2% of the average length of the diagonal.
⑤ The width of insulating glass sealant: the width of single sealing glue layer shall be calculated and determined, and the minimum width shall be 10mm ± 2mm. The width of double sealing outer layer sealant shall be calculated and determined, and the minimum width shall be 5-7mm. The thickness of rubber strip sealing glue layer shall be 8mm ± 2mm. Products with special specifications or special requirements shall be agreed by the supplier and the demander.
⑥ Appearance: The inner surface of the insulating glass shall be free of stains, inclusions and sealant splashes that hinder perspective.
⑦ Performance requirements: the sealing, dew point, ultraviolet radiation, climate cycle, high temperature and high humidity performance of insulating glass shall be tested according to GB7020, and must meet the following requirements.
※When the test pressure of the seal is 10 ± 0.5KPa lower than the ambient air pressure, the thickness growth must be ≥ 0.8mm. When the pressure is kept at 2.5, the thickness growth deviation is less than 15%, which means that all samples are not allowed to leak.
※Dew point Reduce the temperature of the dew point meter to ≤ - 40 ° C, and make the dew point meter contact the sample surface for 3min. There is no condensation or frost on the internal surface of all samples.
※Ultraviolet irradiation The inner surface of the sample after 168h of ultraviolet irradiation shall be free of fogging and pollution traces.
※After 320 cycles of climate cycle and high temperature and high humidity climate test, 224 cycles of high temperature and high humidity climate test, the dew point test is conducted after the test.There are 12 samples in total, and at least 11 samples are free of condensation or frost.
When hollow glass is selected for concealed frame curtain wall, the second sealant of hollow glass must be silicone sealant and compatible with sealant used for structural glass assembly, that is, the two must use mutually compatible sealant.When a certain silicone sealant is used for structural assembly, the best ordered insulating glass sealing adhesive layer also uses the silicone sealant from the same factory[3]。
