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【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. 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.

Figure 1 The insulating glass warm edge spacer 1

Figure 1 The insulating glass warm edge spacer 1

3. 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: 

①soft color, no metal glare surface; 

②microporous elastic structure, containing 3A molecular sieve (desiccant); 

③initial structural adhesive; 

④very 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 2 The insulating glass super spacer bar 1

Figure 2 The insulating glass super spacer bar 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. 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.

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.

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.

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

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

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

4.6 Excellent performance Argon gas loss rate is less than 0.19% per year.

The super warm edge spacer insulating glass has the characteristics of flexibility of the spacer, which can be bent arbitrarily with the shape of the glass, and always maintains a seamless fit between the glass, effectively reducing the leakage of argon gas. According to the EN 1279-3 standard, the argon gas loss test conducted by an independent laboratory in North America shows that the argon gas loss is less than 1% after 5 years, and less than 0.19% per year, which effectively guarantees the performance of insulating glass.

4.7 Solved the situation of insulating glass seal overflow

The super warm edge spacer insulating glass has an independent butyl rubber groove, which effectively prevents the internal overflow of the butyl rubber and meets the high standard appearance requirements. And in the production process, the high degree of automation and high standard processing, so that the butyl glue application will not appear uneven, glue overflow and other phenomena, the phenomenon is shown in Figure 16, Figure 17, effectively eliminate the situation of glue overflow in the insulating glass seal.

5. Super warm edge four-glass three-chamber insulating glass and super warm edge three-glass two-chamber insulating glass

As a new generation of high-performance insulating glass supporting products, super warm edge has better thermal performance, which greatly reduces the influence of glass edge line heat transfer loss on glass performance. Four-glass three-insulation and three-glass two-insulation high-performance glass with super warm edge spacers are the preferred solutions for passive ultra-low energy consumption buildings.

6. Conclusion

From thermal simulation to test results, the application of super (flexible) warm edge spacers can alleviate the "breathing effect", improve the service life of low-e coating glass and insulating glass, improve the edge linear heat transfer coefficient of insulating glass, reduce the heat around the glass The transfer and edge condensation can effectively reduce the K value of the whole window and improve the excellent performance such as the retention rate of argon in the hollow cavity. The advent of super warm edge spacers has greatly improved the performance of energy-saving doors and windows, and has become a necessary guarantee for passive windows and passive ultra-low energy buildings. With the development of passive ultra-low energy buildings in my country, super (flexible) The application prospects of insulating glass with warm edge spacers will become more and more extensive.

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[1] Industry standard "Insulating Glass Spacer Part 3: Warm Edge Spacer"

[2]ASTM E 2188-10, Standard Test Method for Insulating Glass Unit Performance[S], ASTM International.

[3]ASTM E 2189-10, Standard Test Method for Testing Resistance to Fogging in Insulating Glass Units[S], ASTM International.

[4]ASTM E 2190-10, Standard Specification for Insulating Glass Unit Performance and Evaluation[S], ASTM International.

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