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The performance of the sealant directly affects the energy-saving effect and service life of the insulating glass. At present, the most commonly used sealants for insulating glass in various countries are silicone sealants and polysulfide sealants. There are obvious differences in the performance of these two sealants. For example, polysulfide glue has lower water vapor permeability than silicone glue, and silicone glue is more elastic than polysulfide glue and has a good elastic recovery rate. 

However, there is no basic data for reference on the impact of the two sealants on the sealing performance, aging resistance, and inert gas retention of insulating glass. Especially when making spacers for bending double-pass sealing insulating glass, the effect of the low water vapor permeability of polysulfide glue relative to silicone glue on the performance of insulating glass is not known, which also makes insulating glass manufacturers choose to seal when gluing, the concept is vague and cannot be accurately judged.

In order to have a deeper understanding of the performance difference between silicone sealant and polysulfide sealant, and to provide help and guidance on the future use and performance improvement of the silicone sealant and the polysulfide sealant, it is very important to conduct in-depth, systematic testing and comparison of their performance. necessary.

Figure 1 The insulating glass silicone sealant

Figure 1 The insulating glass silicone sealant

Figure 2 The insulating glass polysulfide sealant

1. The performance comparison plan   

For scientific, fair, and accurate testing and comparison of the performance differences between silicone sealants and polysulfide sealants, we have formulated the following sampling and testing plans:

1.1 Sampling method

Select the sealant manufacturers for insulating glass that have a large scale of production worldwide and have a certain reputation in the industry to participate in this comparison test. Among them, there are 5 silicone sealant and polysulfide sealant manufacturers. The silicone rubber manufacturers are

DOWSIL™ 982 FS Silicone Insulating Glass Sealant

Onward Silicone Insulating Glass Sealant

Silicone from AU.

Solutions-ig Insulating Glass Sealant

Viracon Insulating Glass Sealant

The China National Glass Quality Supervision and Inspection Center is responsible for sampling, and randomly selecting products that have passed the self-inspection of the enterprise in the enterprise finished product warehouse, and each enterprise will sample 25 kilograms of one type of sample. The company sends the samples it takes to the China National Glass Quality Supervision and Inspection Center.

1.2 Production of insulating glass samples 

China National Glass Quality Supervision and Inspection Center contacted a large insulating glass manufacturer, and under the on-site supervision of personnel from China National Glass Quality Inspection Center, Jinan LIJIANG Glass Automatic Vertical Insulated Glass Production Line was used, and the extracted Sealant samples are used to make elbow trough aluminum gas-filled insulating glass. Each polysulfide sample is made into a set of 10 gas-filled hollow glass samples, and each silicone rubber sample is made into two sets of hollow glass samples (one set is The samples with the same thickness as the polysulfide glue layer, and the other group of samples with a thickness of 2mm than the polysulfide glue layer) 10 pieces each.

1.3 Test items

1) High temperature and high humidity durability test: According to the test method specified in the international industry standard "Insulating Glass", the dew point test shall be carried out after the test;

2) Water and air seal durability test: in accordance with the test method specified in the international industry standard "Insulating Glass for Building";

3) Gas seal durability test: The argon content test method of oxygen analysis is adopted. First, the insulating glass sample is tested for the initial argon content, then the sample is sealed, and the aging test is carried out according to industry standards, and then the argon content is carried out after the test. Detection

4) Water vapor permeability test: According to the method specified in the international industry standard "Elastic Sealant for Insulating Glass".

2. Production of hollow glass samples

After all the sealant samples were sent to the National Glass Quality Supervision and Inspection Center, Jinan LIJIANG Glass contacted the Qinhuangdao Yaohua Industrial Technology Glass Factory, which is well-known in the glass deep processing industry, to make hollow glass samples. In the production process, except for the sealant, all the hollow glass samples adopt the bending type of Lisec 9mm aluminum strip, the joints are sealed with butyl glue, and the two adjacent sides (one side is the long side and anothe one is the short side) are automatically filled. 3A molecular sieve, the inner sealant uses Le Jiefu butyl rubber, and the hollow glass composite is completed on the Jinan LIJIANG Glass Automatic Vertical Insulated Glass Production Line. Each type of polysulfide glue is used to make 10 samples, the thickness of the outer sealant is controlled at 3mm (referring to the outer edge of the aluminum strip to the edge of the glass), and the thickness of two kinds of outer sealant (respectively 3mm and 5mm) is made by each silicone glue. 

After the sample is made and cured, randomly take 3 pieces from each type of sample to make an argon-filled sample, control the argon flow rate and filling time during the filling process, and monitor the argon content in the hollow glass, Ensure that the argon content of the sample is higher than 85%.

Using a vacuum mixer, each glue is evenly mixed and made into 2mm thick films each.

3. The test process

3.1 High temperature and high humidity durability test:

Take 2 samples, perform an initial dew point test on them, and put them in a high temperature and high humidity test box for 224 cycles after passing the test. Each cycle is divided into two stages: 1) Heating stage: the time is 140min±1min, the temperature in the box is raised to 55℃±3℃ within 90 min±1min, and the remaining time is kept warm; 2) Cooling phase: the time is 40min±1min, reduce the temperature in the box to 25℃±3℃ within 30 min±1min, keep the temperature for the rest of the time, and keep the relative humidity above 95%. After 224 cycles are completed, the sample is removed and placed for a week under the conditions of a temperature of 23°C ± 2°C and relative humidity of 30% to 75%, and then the final dew point is tested.

3.2 Water and air seal durability test    

Take 2 pieces of each kind of sample for the water-gas seal aging test. The test is divided into two stages. The first stage: 56 cycles, every 12h is a temperature cycle, the temperature is from -18℃±2℃~53℃±1℃, the temperature rise and fall rate are 14℃±2℃/h, the humidity of the test chamber is greater than 23℃ Should be greater than or equal to 95%; the second stage: the temperature is 58 ℃ ± 1 ℃, relative humidity greater than 95% of the ambient temperature for 7 weeks. After the test, determine the final moisture content Tf of the desiccant according to the new national standard method.

Take 2 samples to test the initial moisture content of the desiccant Ti according to the relevant international industry standards, and take the average value as the initial moisture content of the desiccant.

Take 1 sample to determine the standard moisture content Tc according to the relevant international industry standards.

The water permeability index is calculated according to the formula for the I value of the two samples and the average value Iav of the I values of the two samples.

3.3 Gas seal durability test

Perform an initial gas content test on 3 samples of gas-filled insulating glass. After the sealing treatment, they are put into an aging test box for a two-stage aging test. The first stage: 28 cycles, every 12h is a temperature cycle, the temperature is from -18℃±2℃~53℃±1℃, the temperature rise and fall rate is 14℃±2℃/h, the humidity of the test chamber is greater than 23℃ Should be greater than or equal to 95%; 2) Phase 2: The temperature is 58 ℃ ± 1 ℃, relative humidity is greater than 95% of the ambient temperature for 4 weeks. After the aging test, test the gas content of the sample.

3.4 Water vapor permeability test

Put the made 2mm thick film into a moisture-permeable cup, and measure the amount of water vapor permeated stably for 24 hours in an environment with a temperature of 23℃±2℃ and relative humidity of 90%.

4. Test results

4.1 High temperature and high humidity durability

Table 1 High-temperature and high-humidity durability test results
of silicone insulating glass
 
Enterprise numberTest result
SiliconeAQualified
BQualified
CQualified
DQualified
EQualified
FQualified
PolysulfideGQualified
HQualified
IQualified
JQualified
KQualified

4.2 Water and air seal durability   

Note: A total of 12 samples were made, of which 2 (B2 and C2) were destroyed.

Table 2 Silicone insulating glass (glue depth 5mm) water and air seal 
durability test results
Enterprise Number
Silicone (Glue depth 5mm)
II ay
A10.07130.0761
A20.0753
B10.1954
C10.1511
D10.0370
D20.0457
E10.0233
E20.0532
F10.0638
F20.0452
Excluding the maximum value of 0.1954 and the minimum value of 0.0233, the remaining average value is 0.0678.
Table 3 Silicone insulating glass (glue depth 3mm) water and air seal
durability test results
Enterprise Number
Silicone (Glue depth 3mm)
 
II ay
A10.12210.1112
A20.2450
B10.1884
B20.1751
C10.0342
C20.0812
D10.0632
D20.0230
E10.1871
E20.1475
F10.0451
F20.0226
Excluding the maximum value of 0.2450 and the minimum value of 0.0226, the remaining average value is 0.1070.
Table 4 Durability test results of water and air sealing of 
polysulfide insulating glass
Enterprise Number
polysulfide
II ay
G10.12980.01080
G20.1067
H10.1378
H20.1800
I10.0604
I20.1136
J10.1303
J20.1121
K10.0689
K20.0403
Excluding the maximum value of 0.1800 and the minimum value of 0.0403, the remaining average value is 0.0860.

4.3 Initial gas content and gas seal durability 

Table 5 Silicone insulating glass (glue depth 5mm) water and air seal
durability test results
Enterprise number/silicone (glue depth 5mm)Initial concentration of argon (%)Final content of argon (%)Argon reduction (%)
A192.779.213.5
A293.081.611.4
A388.077.011.0
B188.981.37.6
B290.879.611.2
B392.685.37.3
C189.278.211.0
C293.080.512.5
C393.982.511.4
D190.168.122.0
D284.872.412.4
D394.474.919.5
E193.480.113.3
E294.281.113.1
E388.773.415.3
F189.474.914.5
F292.985.27.7
The final argon content above 80% is qualified A total of 17 pieces, of which 8 pieces are qualified, the pass rate is 47.1%

Note: A total of 18 samples were made, of which 1 (F3) was destroyed    

Table 6 Silicone insulating glass (glue depth 3mm) air seal
 durability test results
Enterprise number/silicone (glue depth 3mm)Initial concentration of argon (%)Final content of argon (%)Argon reduction (%)
A195.280.714.5
A289.273.415.8
A391.082.58.5
B193.284.29.0
B291.080.610.4
B392.376.316.0
C193.781.811.9
C288.677.611.0
C390.477.512.9
D195.677.618.0
D295.274.420.8
E193.477.116.3
E296.575.421.1
F189.473.515.9
F295.674.621.0
The final argon content above 80% is qualifiedA total of 15 pieces, of which 5 pieces are qualified, with a pass rate of 33.3%
Table 7 Polysulfide insulating glass air seal durability test results
Enterprise number/silicone (glue depth 3mm)Initial concentration of argon (%)Final content of argon (%)Argon reduction (%)
A195.280.714.5
A289.273.415.8
A391.082.58.5
B193.284.29.0
B291.080.610.4
B392.376.316.0
C193.781.811.9
C288.677.611.0
C390.477.512.9
D195.677.618.0
D295.274.420.8
E193.477.116.3
E296.575.421.1
F189.473.515.9
F295.674.621.0
The final argon content above 80% is qualified. A total of 15 pieces, of which 5 pieces are qualified, with a pass rate of 33.3%
Table 7 Polysulfide insulating glass gas seal durability test results
Enterprise number/silicone (glue depth 3mm)Initial concentration of argon (%)Final content of argon (%)Argon reduction (%)
G187.082.84.2
G297.993.14.8
H187.184.03.1
H287.084.22.8
H393.292.01.2
I192.089.62.4
I287.084.22.8
I391.188.82.3
J190.188.12.0
J296.186.29.9
K196.695.31.3
k295.090.54.5
K391.288.32.9
The final argon content above 80% is qualified. A total of 13 pieces, of which 13 pieces are qualified, the pass rate is 100%.

Note: A total of 15 samples were made, of which 2 (G3 and J3) were damaged

4.4 Water vapor permeability 

Table 8 The test results of film water vapor permeability
Enterprise numberWater vapor permeability
(g/m² *d)
Water vapor permeability avg (g/m² *d)
SiliconeA127.222.64

 
A217.3
B124.5
B221.9
C321.8
C322.8
D424.1
D419.9
E526.8
E520.0
F123.5
F221.9

Polysulfide
G17.411.42
G211.4
H19.9
H212.9
I110.9
I26.8
J113.0
J215.6
K113.6
K212.7

5. Result in analysis

The durability of high temperature and high humidity and the durability of water vapor sealing are both to investigate the resistance of the insulating glass system to water vapor. Therefore, the performance of the external sealant directly affects the durability of the insulating glass system. The high temperature and high humidity durability test is a qualitative test of the durability of the insulating glass system, and the water-gas seal durability test chamber is a quantitative test of its durability. From the test results in Table 1, it can be seen that whether it is silicone insulating glass or polysulfide insulating glass, its high temperature and high humidity durability can meet the standard requirements. In the water and gas seal durability test, the water vapor penetration resistance of insulating glass systems with different outer sealants and different glue layer thicknesses meets the requirements of relevant international industry standards. The specific test results parameters are shown in Tables 2, 3, and 4. However, there is still a significant difference in the value of the water permeability index. The average water vapor permeability index of silicone insulating glass and polysulfide insulating glass with a glue depth of 3mm and 5mm are 0.1112, 0.0761, and 0.1080, respectively. It can be seen from the results that the water vapor penetration resistance of silicone insulating glass with thick outer glue layer is significantly better than that of silicone insulating glass with shallow glue layer; under the condition of the same glue layer thickness, polysulfide hollow glass The water vapor penetration resistance of glass is better than that of silicone insulating glass. Taking into account the influence of external conditions, the above conclusions can still be obtained after removing the data with large deviations.

By comparing the argon retention data of insulating glass in Tables 4, 5, and 6, it can be found that the performance of silicone and polysulfide insulating glass in gas sealing durability is far apart. The gas retention rate of polysulfide insulating glass is very good. After the durability test according to the new national standard, the gas content is not less than 80%, which meets the gas durability requirements in the international industry standard; the silicone insulating glass sample with thick glue layer A total of 17 samples, of which only 8 have a gas content greater than 80% after the test, and the pass rate is only 47.1%. The gas sealing durability of silicone insulating glass with a shallow adhesive layer is even worse. A total of 15 samples, of which only 5 The block meets the requirements of international industry standards, and the pass rate is only 33.3%. The average argon leakage of the silicone insulating glass sample with a thick glue layer is 12.6%, the average argon leakage of the silicone insulating glass sample with shallow glue layer is 14.9%, and the average argon leakage of the polysulfide insulating glass sample The air leakage is only 3.4%. In terms of gas sealing durability, polysulfide insulating glass is superior to silicone insulating glass.

In the water vapor transmission rate test, the average water vapor permeability of polysulfide glue is 11.42g/m² •d, the average water vapor permeability of silicone glue is 22.64g/m² •d, and the water vapor of silicone glue The permeability is twice that of polysulfide glue, indicating that the water vapor penetration resistance of polysulfide glue is better than that of silicone glue.

The water vapor permeability of polysulfide rubber is twice that of silicone rubber, but the difference in the durability of water and gas sealing between the two is not very large. The reason for analysis is that this is due to the selection of Jinan LIJIANG Glass. The width of the bent aluminum strip structure and the butyl rubber is greater than 5mm, and the joints of the aluminum strips are sealed with butyl rubber to form a good internal water vapor sealing barrier, which effectively prevents most of the water vapor from entering. In the actual production process, most of the products do not reach this level of production.

6. The use suggestions

In view of the differences in water and gas seal durability, gas seal durability, and water vapor permeability between silicone rubber and polysulfide rubber, we make the following recommendations to insulating glass manufacturers:

(1) Both silicone glue and polysulfide glue can be used to make insulating glass. When using a bent metal spacer and a double-channel sealing structure, under the premise of ensuring the quality of a butyl rubber seal, when making ordinary insulating glass without argon gas, there is no significant difference between the two types of adhesives on the performance of the insulating glass.

(2) When making insulating glass for doors and windows, especially gusseted insulating glass, polysulfide glue should be used as the external sealant as far as possible. If silicone glue is selected as the external sealant, the durability of silicone insulating glass can be improved by appropriately increasing the thickness of the glue layer.

(3) Since silicone rubber and polysulfide rubber have a big difference in argon retention capacity, polysulfide rubber should be used first when making argon-filled insulating glass.

7. Suggestions for a further comparison test

Globally, there are nearly 10,000 manufacturers of insulating glass sealants, and the quality of sealants varies. The low overall quality of sealants and vicious market competition has seriously affected the healthy development of the insulating glass industry in various countries. In order to gain an in-depth understanding of the quality of the insulating glass sealant industry in various countries, vigorously promote superior companies in the insulating glass sealant industry, and guide insulating glass manufacturers to choose high-quality sealant products, Jinan LIJIANG Glass suggests using polysulfide for insulating glass this time. Based on the comparison of the performance of rubber and silicone rubber, other external sealants are randomly selected from the market for durability testing, and then compared with the test results this time.
In addition, Jinan LIJIANG Glass hopes to hold an insulating glass sealant technology seminar at a suitable time and announce the results of the two comparisons, so that the insulating glass industry can fully understand the market status, quality differences, and inferior quality of insulating glass sealants products in various countries around the world. The effect of the product on the performance of the insulating glass achieves the purpose of supporting the advantages and limiting the disadvantages.


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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