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The market application of high-performance insulating glass flexible (super) warm edge spacers.
Abstract】Combined of composite materials, the warm edge spacer with flexible bonding support and containing desiccant has been widely used in the fields of doors, windows and curtain walls due to its excellent thermal insulation properties, reliable sealing performance, and beautiful appearance. It has been widely used; especially in recent years, passive ultra-low energy consumption buildings have flourished in developing country, making flexible warm edge spacers widely used in the market. This article expounds the influence of flexible (super) warm-edge spacer insulating glass technology on energy-saving doors and windows, and conducts a detailed comparative analysis through simulation, test experiments and other data, and has important implications for the application and design of flexible (super) warm-edge spacers
【Keywords】energy saving; super warm edge spacer; insulating glass

1. Introduction

The development of warm edge spacers is closely related to the development of building energy saving, doors and windows, and insulating glass. The rise and promotion of passive buildings in my country has made the relevant market put forward higher requirements for the requirements and performance of related parts. At the same time, with the gradual improvement of building energy-saving standards and the promotion and application of passive buildings as an important part of the building envelope, the requirements for energy-saving characteristics have also gradually increased, the heat transfer coefficient of doors and windows, the stability of inert gas, Condensation, heat insulation, thermal insulation and other properties have also become important indicators of building energy saving, reducing building energy consumption and improving indoor comfort.According to statistics, in 1990, the insulating glass with cold edge (that is, using aluminum as the main raw material) in developed countries in Europe and the United States accounted for 85% of the market share, while the market share of warm edge accounted for only 15%; but by 2000, the market share of warm edge The share rose to 80%, and the cold edge dropped to 20%. The main raw materials of warm edge spacers can be roughly divided into three categories, one is metals with a conductivity lower than aluminum, such as stainless steel; the other is non-metallic materials, such as fiberglass strips, flexible (super) warm edge spacers (hereinafter referred to as "" Super spacer”), warm edge; the third is metal and non-metal composite materials, such as broken bridge spacers, composite rubber strips, etc. The insulating glass with super spacer has been widely used in the field of building energy saving due to its superior energy saving characteristics. This article discusses the second category, the super warm edge spacer, which has developed rapidly in recent years.

2. The warm edge spacer
The international industry standard "Insulating Glass Spacer - Warm Edge Spacer Industry Labeling" stipulates that the warm edge spacer is defined as a spacer composed of low thermal conductivity materials, which is used to reduce the heat conduction at the edge of the insulating glass. The standard stipulates that the thermal conductivity value of the warm edge temperature difference of the warm edge spacer should not be greater than 0.007W/K, that is, the material thickness d and the thermal conductivity score <0.007W/K, that is, Σ (dxλ) <0.007.According to 4.1 classification of the international industry standard "Insulating Glass Spacer - Warm Edge Spacer Industry Labeling", the warm edge spacer is divided into two types: rigid warm edge and flexible warm edge. Rigid warm edge spacers: generally include polypropylene + stainless steel, PVC + stainless steel, glass reinforced composite material + composite film, etc., which are represented by GN [1]. Flexible warm edge spacers: generally include polyisobutylene, etc., denoted by RN. The super spacer is a flexible spacer with good thermal and mechanical properties.

3. The super spacer

Super warm edge spacer: It is a thermosetting elastic microporous structure, with silicone/EPDM as the base material, integrated with desiccant and adhesive; it is a completely non-metallic warm edge spacer.

Super spacer structure notes: 

  1. soft color, no metal glare surface; 
  2. microporous elastic structure, containing 3A molecular sieve (desiccant);
  3. initial structural adhesive; 
  4. very dense multi-layer polyester moisture-proof film to prevent water vapor , Argon gas permeation; 
  5. Reserve butyl rubber coating to achieve three sealing structures.
Figure 1 The insulating glass super spacer 1

4. Advantages of super warm edge spacer insulating glass

Insulating glass itself has excellent properties such as high thermal insulation, anti-condensation, sound insulation, etc. to improve the thermal and optical properties of the entire window. 

Table 1 Advantages of super spacers

Excellent thermal performance
Excellent anti-condensation performance
Complete sealing performance
Super weather resistance
Third seals, one more seal than mainstream glass in the market
Argon loss rate is less than 0.19% per year
Solved the problem of overflow of butyl rubber in insulating glass
The material and performance of the spacer have a great impact on the service life and performance of the entire insulating glass, and a good spacer can effectively ensure the performance of the insulating glass.

4.1 Excellent thermal performance

The edge heat loss of the insulating glass accounts for a large part of the heat loss of the whole insulating glass, and the loss of argon will dissipate more energy. Therefore, improving the thermal conductivity of the edge of the insulating glass is of great significance to improve the energy-saving performance of the entire window.

Table 2 Thermal comparison of aluminum spacer insulating glass, impermeable steel spacer insulating glass and super warm edge spacer
130 aluminum-clad-wood door and window glass configurationGlass configuration: 5 Low-E + 16 Ar + 5 + 16Ar +5 Low-E
The transmission coefficient of the glass: Ug=0.74 W/(㎡*K)
Heat transfer coefficient of 130 aluminum-clad-wood window frameUf=0.8 W/(㎡*K), see Figure 2
Insulating glass edge linear heat transfer coefficientAluminum spacer insulating glass (Figure 3)Stainless steel spacer insulating glass (Figure 4)Super warm edge spacer insulating glass (picture 5)
It can be clearly seen from the comparison of the line chart (Figure 6);
The marginal heat transfer coefficient of the super warm edge spacer insulating glass is the smallest, that is, the heat loss of the super warm edge spacer insulating glass is the least.

Figure 2 Heat transfer coefficient of 130 aluminum clad wood window frame
Figure 3 Edge heat transfer coefficient of aluminum spacer insulating glass
Figure 4 Edge heat transfer coefficient of stainless steel spacer insulating glass
Figure 5 Edge heat transfer coefficient of super spacer insulating glass
Figure 6 Line chart of linear heat transfer coefficient of insulating glass edge with different material spacers

4.2 Excellent anti-condensation performance

Because of the low thermal conductivity of the warm edge spacer, the glass edge can obtain excellent thermal insulation properties and avoid the loss of linear heat transfer at the glass edge. Because of the excellent thermal insulation performance, the temperature of the indoor side window surface in cold winter can be kept closer to the indoor ambient temperature to prevent fogging and condensation on the glass or window frame. In order to verify the dew point temperature of spacers of different materials, the flixo software was used to set the outdoor temperature -10 °C, the indoor temperature 20 °C, and the relative humidity of 65% for simulation calculation.

Figure 7 The Thermal Simulation Test of Ordinary Insulating Glass
Figure 8 The Thermal Simulation Test of Super Spacer Insulating Glass
Figures 7 and 8 show that the super warm edge spacer insulating glass has excellent anti-condensation performance, and the surface temperature of its edge is generally about 6 °C higher than that of ordinary insulating glass. According to the table "Dew Point Temperature under Different Temperature and Humidity", it can be seen intuitively that when the relative humidity is 65% and the indoor temperature is 20°C, condensation will occur on the surface of the object at 13.3°C. Through the simulation calculation, it can be intuitively concluded that the super warm edge spacer insulating glass exhibits extremely high anti-condensation performance, which eliminates the condensation phenomenon on the edge of the glass, eliminates the related health problems caused by mold, and makes the insulating glass cleaner and transparent. .

4.3 Complete sealing performance

There is air (or inert gas) in the hollow glass cavity. Due to the temperature difference between the temperature when the hollow glass is made and the outside temperature when the hollow glass is actually used, to keep the pressure in the hollow glass cavity unchanged, the gas volume must be changed accordingly. , that is, "respiration" occurs. This gas volume change will squeeze or stretch the edge sealing material, and the aluminum spacer has a small expansion coefficient, which will squeeze the butyl glue and migrate into the glass, resulting in glue overflow or sealing failure. The use of super spacer bars can effectively avoid the above-mentioned situation.

Figure 9 The ordinary insulating glass breathing
Figure 10 The super spacer insulating glass breathing

Table 4 Influence of butyl sealant in the breathing process of insulating glass

Influence of ordinary insulating glass on butyl rubber in the process of breathingInfluence of butyl rubber on breathing process of super warm edge spacer insulating glass
Ordinary insulating glass cannot be compressed, and the stress of the pump effect acts on the butyl rubber and the structural adhesive. After continuous extrusion and pushing and pulling, the butyl rubber is eventually torn and disengaged, resulting in seal failure.The butyl in the Super Warm Edge Spacer glass is locked between the acrylic adhesive and the structural adhesive, preventing butyl ingress and spillage, maintaining an intact butyl seal at all times, after expansion and contraction the total is able to return to its original shape.

4.4 Super weather resistance

The super warm edge spacer insulating glass is under the standard of ASTM E2188/2189/2190, the most severe experimental conditions in the industry, high temperature and high humidity, climate cycle, and ultraviolet irradiation are carried out at the same time, as shown in Table 5 and Table 6. The experimental conditions are shown. After multiple rounds of testing, the sealing performance of the insulating glass of the super warm edge spacer is still intact, and the weather resistance is super strong. The test report is shown in Figure 11.

Table 5 Ultraviolet performance requirements and testing methods

StandardASTM E 2190-10 / ASTM E 2189-10
Sample2 pieces (505±6)mm*(355±6)mm samples
Performance requirementsAfter the experiment, there is no condensation on the inner surface of the sample
Irradiation source and specimen placement1 set 300W UV bulb, placed in the center of the test box, 2 samples are placed obliquely above the light source
Temperature inside the box(50±3)℃ 
Cooling water temperature(21±2)℃
Irradiation time7 days
Observation time after irradiationObserve immediately, if there is fog, observe again the next day, and observe again on the seventh day if there is still fog
Observation conditionsDark room, 2 20W white light cold lights behind the sample, at least 1.5m away from the light source, 500-700mm away from the sample, projection and reverse observation

Table 6 High temperature, high humidity and climate cycle performance requirements and testing methods

StandardASTM E 2190-10 / ASTM E 2189-10
Experiment nameHigh temperature experimentClimate cycle experiment
Sample6 samples (505±6)mm*(365±6)mm
after dew point detection
Experimental temperature(60±3)℃(29±3)-(60±3)℃
Relative humidity95%±5%At room temperature -60°C, the highest temperature > 90%
Ultraviolet radiationNoneAbove room temperature, there is ultraviolet radiation
Each experiment time14 days before the climate cycle experiment, 28 days after the experiment6h per cycle, 252 cycles (63 days)
Total test time105 Days
Total humidification time52.5 Days
Total radiation time31.5 Days

Figure 11 Super warm edge spacer insulating glass seal durability trest report

4.5 Three seals One more seal than mainstream glass in the market

Figure 12 The super spacer sealing structure
The super spacer has three sealing structures, one more seal than most spacers on the market, which effectively ensures the air tightness inside the insulated cavity. Eliminate the generation of problems such as fogging and inert gas leakage inside the insulated cavity.

Figure 13 The ordinary insulating glass secondary seal structure
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