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The insulating glass materials and quality control③

4. The hollow glass in the corner (or corner) group frame has low water permeability and long life 

Several aluminum spacers are inserted into the group frame, and there is an empty gap between the gusset and the spacers, and there is no barrier between the metal layer, and the moisture can directly penetrate through the glue layer. The high moisture permeability at this place has attracted people’s attention. The process improvement measure is to fill the vacant gap with butyl sealant when inserting the angle; the structural improvement is to cancel the connector, directly frame a spacer, or use ∏ metal The spacers are folded to form the frame to eliminate the corner penetration channel and make the corner penetration rate zero. Compared with the gusset single element, its annual water permeability will be significantly reduced (Table 3), and the functional life will be extended (Table 4) 

Table 3 Estimation of water permeability of standard specimens of frame-type insulating glass with curved corners

TypeSealed formAngular permeabilitySeam permeabilityAnnual water permeability
CornerDouble seal00.070.11
Single seal01.201.94
GussetDouble seal0.550.070.66
Single seal0.701.202.64

Table 4 Estimation of the theoretical life of the hollow glass saturated with water absorption in the curved corner group frame

TypeSealed formProduct SizeDesiccantAnnual water permeabilityEstimated life
Filling amountSaturated water absorption value
CornerDouble sealStandard52.09.380.1185.3
Single sealStandard52.09.381.944.8
GussetDouble sealStandard48.68.700.6613
Single sealStandard48.68.702.623.3

It can be seen from Tables 3 and 4 that the water permeability of the angled frame hollow glass has decreased by 300-500%, the theoretical life span is extended by 3-6 times, and the life span is not greatly affected by the size of the product, generally more than 80 years.

Figure 1 The corner of insulating glass aluminum strip bar 1

Figure 1 The corner of insulating glass aluminum strip bar

Figure 2 The gusset of insulating glass aluminum strip bar 1

Figure 2 The gusset of insulating glass aluminum strip bar 1

The influence of sealing material on the water permeability of a single unit Sealant is the main path for moisture to penetrate the unit. Butyl sealant has the lowest moisture permeability, but because it cannot be cured, it has low strength and "cold flow". It is suitable for the first seal. For this analysis, please refer to ASTMC1249—935.5 (8) section, polysulfide adhesive has a low moisture permeability, good bonding strength, aging resistance, and process practicability. It is currently the main material for the secondary sealing of insulating glass (7); silicone sealant is used for glass Stable adhesion, weathering resistance, but high moisture permeability, only for safety considerations used for the hollow glass unit parts of the hidden frame glass curtain wall, but must have a good barrier seal with butyl sealant (see ASTM C1249 for details).

The data shows (2) that the standard unit parts (size 35 mm * 50 mm) that use butyl sealant to close the installation gap of the connector are tested by different types of sealant bonding systems under exposure conditions and the moisture permeability is found to be very high. The big difference is that the water permeability of the butyl-polysulfide sealing system unit is about 0.1 g/year, the butyl-two-component silicone sealing system is 0.30-0.35 g/year; the butyl one-component silicone sealing system is 0.5-0.6 g/year. From this, it can also be calculated that the theoretical life of each system product is about 80 years, 31 years, and 17 years. If the influence of the use conditions is considered, the actual functional life will be proportionally discounted. Therefore, the silicone sealant should be controlled in the hollow The scope of application in the glass.

Testing methods and standards of insulating glass     

The testing method of insulating glass was published in 1986, the international industry standard "Testing Method for insulating glass producing". The five indicators of insulating glass (initial dew point, sealing experiment, ultraviolet radiation. High temperature, and climate cycle experiment) are tested strictly by the most authoritative testing organization in the country where the product is used to ensure the fairness of the test results. The purpose of the inspection method introduced in this article is not for the enterprise to inspect on its own, but to increase the quality of the insulating glass by understanding the inspection equipment, inspection steps, and inspection conditions of the insulating glass:

The production environment is closely related to the quality of insulating glass. It can also be said that the environment determines the quality of insulating glass. The production environment mainly refers to the environmental temperature, environmental humidity, environmental accuracy, and environmental factors of the operator.     

Experiment procedure Test step
Dew point testDew point meter: measuring tube H=300mm
All samples are placed for one week under the conditions of temperature 23±2℃ and relative humidity 30`75%A. Inject ethanol or acetone with a depth of about 25mm into the container of the dew point meter, and then add dry ice to cool it to a temperature equal to or lower than -40°C, and maintain this temperature during the experiment.
B. Place the sample horizontally, apply a layer of ethanol or acetone on the upper surface, make the dew point meter closely contact the surface, and stay for 3 minutes.
C. Remove the dew point meter and immediately observe whether there is condensation or frost on the inner surface of the glass sample.
Sealing testThe vacuum box is equipped with a bracket and a dial indicator for measuring thickness changesThe sample should be placed in an ambient temperature of 23±2℃ for more than 12hA. Put the samples into the vacuum box in batches and install them on the bracket equipped with a dial indicator.
B. Adjust the dial indicator to zero or record the initial reading of the dial indicator.
C. During the test, reduce the pressure in the vacuum box to 10 ± 5 kpa (10 ± 5 mbar) lower than the ambient pressure. Write down the number of dial indicators within 5-10 minutes after reaching the low temperature, and calculate the thickness increase value d1.
D. After maintaining the low pressure for 2.5 hours, record the reading of the dial indicator within 5 minutes to calculate the thickness increase value d2.
E. Judgment of leakage deviation.
1) The thickness increase value d must be ≥0.8mm for no leakage.
2) Thickness growth deviation after 2.5h=(d2-d1/d2)*100%<15% means no leakage.
Climate cycle testClimate test device: It is composed of heating, cooling, water spraying, blowing and components that can meet the requirements of simulating climate changeTake 4 samples that have not been tested by ultraviolet radiation and install them on the frame of the climate test device. One surface of the sample is exposed to the climate cycle conditions, and the other surface is exposed to the ambient temperature.A. The climate test is carried out in 320 continuous cycles, and each special cycle cycle is divided into three phases.
1. Heating stage: the time is 90±1min, heating to 52±2℃ within 60±30min, the remaining time is kept warm.
2. Cooling stage: The time is 90±1min. After cooling for 25min, 24±3℃ water is sprayed on the surface of the sample for 5min, and the remaining time is ventilated and cooled.
3. Refrigeration phase: the time is 90±1min, the temperature is reduced to -15±2℃ within 60±30min, and the remaining time is kept warm.In the first 50 special rings of the test, a maximum of 2 specimens are allowed to rupture, which can be replaced with spare specimens, and the test shall be continued after replacement.
B. After 320 cycles are completed, remove the sample and place it for a week under the conditions of 23±2℃ and relative humidity of 30~75%, and then measure the dew point.
High temperature and humidity testHigh-temperature and high-humidity test chamber: It is composed of heating and water spraying devices that can reach the temperature and humidity required by the test.Take samples that have not been subjected to ultraviolet radiation test and climate cycle test and place them in a high-temperature and high-humidity test box with a relative humidity greater than 95%, and spray water continuously between the wall of the box and the partition. Make the temperature change regularly between 25±3℃~75%.A. The test needs to go through 224 cycles, and each cycle is divided into two stages:
1. Heating stage: reduce the temperature in the box to 25±3°C within 40±1min, and keep it warm for the rest of the time.
2. Cooling stage: The time is 40±1min. After cooling for 25min, water at 25±3℃ is sprayed on the surface of the sample for 5min, and the remaining time is ventilated and cooled. B. In the first 50 cycles of the test, a maximum of 2 specimens are allowed to rupture and can be replaced. Continue the test after replacement. C. Remove the sample after 224 cycles are completed, and place it for one week at a temperature of 23±2°C and a relative humidity of 30~75%, and then measure the dew point.

1. The environmental requirements of trough aluminum insulating glass     

(1) Temperature requirement: 

generally in the range of 10-30℃;    

(2) Humidity requirement: 

The relative temperature requirement of trough aluminum insulating glass is slightly lower, and it is normal. However, it should be noted that the desiccant should be qualified from a regular manufacturer to ensure the effective use of the desiccant. The desiccant should be used up within 24 hours after opening because the polysulfide glue has greater air permeability and poor sealing performance, so double-channel sealing is required. Use butyl rubber as the first seal, which acts as a gas barrier, and polysulfide rubber as the second seal, which is mainly used for bonding. The second is the gas barrier function. The practice has proved that the single-channel (traditional) sealed insulating glass has a life span of only about 5 years, while the dual-channel sealed insulating glass has a life span of 20 to 40 years.

Figure 3 The trough aluminum type of insulating glass 1

Figure 3 The trough aluminum type of insulating glass 1

2. The requirements for the environment of rubber-strip insulating glass    

(1) Temperature requirements: 

The production temperature of rubber strip type insulating glass is generally between 10 and 20°C in winter, and 20-30°C in summer.    

(2) Temperature requirements: 

The solid glue strip desiccant is in powder form, and the desiccant will work slowly after mixing with the glue, so the relative temperature of the glue strip assembly area should be kept slightly lower.    

The following introduces a measure to improve environmental quality during the production of trough-type and rubber-strip insulating glass, which can be used as a reference for manufacturers during production and can also be used as a reference for manufacturers of insulating glass products when choosing.     

The production of insulating glass is generally carried out in a larger space. Therefore, temperature, humidity, and dust are difficult to control. An effective measure is to transport the exit of the glass washing and drying machine to the sheet. Use a smaller operating room to seal, and if possible, install an air conditioner. One is to prevent the sweat of the operators from dripping into the environment in summer, and the other is to separate from the dust in the larger space. The packing space does not need to be too large (length×width×height) enough.    

Figure 4 The aluminum rubber-strip type of insulating glass 1

Figure 4 The aluminum rubber-strip type of insulating glass 1

Placement of insulating glass   

Whether the hollow glass is placed correctly or not will affect the final quality of the hollow glass. Whether it is production, transportation, or site storage, it must be placed on a stacking rack. The design of the stacking rack should refer to the characteristics of insulating glass, and the stacking rack should have a certain inclination. However, the bottom plane and the sides should always be kept at 90 degrees, to ensure that the two glass-bottom edges of the insulating glass can be placed vertically on the stacking rack, and the glass is stressed at the same time so that it will not be misaligned due to placement.     

In addition, be careful not to get oil, lime, and other solvents on the bottom of the insulating glass, because these gases will corrode the second sealant of the insulating glass to varying degrees, thereby affecting the sealing performance of the insulating glass.     

Selection of insulating glass    

The selection of insulating glass is a comprehensive problem. The key is product quality, followed by price. This is an introduction to several links and simple methods that need to be mastered when selecting insulating glass for reference by manufacturers of insulating glass selection.     

1. Qualifications of insulating glass manufacturers

Complete and complete production equipment: equipment level and production capacity, quality assurance system in the production process, production time, and production experience.     

2. With complete technical documents "Instructions for Use", "Qualification Certificate", "Quality Inspection Certificate", "Production License", etc.

3. Several simple methods to detect hollow glass    

(1) Look

Look at the appearance; look at the quality of glass selection; look at the coating quality of butyl glue; look at the coating quality of polysulfide glue; look at whether there is any misalignment after the two layers of glass are formed.     

(2) Listen

Knock the insulating glass with your hand, and the qualified product with sufficient pressure will have a crisp sound. Otherwise, the glass-forming pressure or the whole will be uneven;     

(3) Quantity

Measure whether the thickness of a single piece of glass meets the standard requirements; whether the opposite side and diagonal dimensions of the measured glass meet the requirements of the relevant standards; whether the combined thickness of the measured hollow glass meets the requirements of the relevant standards.     

(4) Touch

Check whether the edge of the glass is ground and chamfered; check whether the glue around the insulating glass is even and neat, whether there is glue sagging and under the glue.

For more information about Jinan LIJIANG Glass insulating glass processing equipment and insulating glass processing accessories, please click here to learn more. 

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