Since the 1960s, when hollow glass first appeared in China, its production has evolved through various stages, including single and double glazing, manual single-channel sealing, double-channel sealing, and more recently, composite rubber-type insulating glass. After nearly four decades of development, the market has gradually matured. With increasing attention to building energy efficiency in China, the quality of insulating glass has become a key concern.
The main factors that affect the quality of insulating glass are the selection of raw materials and the production process. This article focuses on the importance of material selection, as it directly impacts the performance and lifespan of the final product.
Currently, three main types of insulating glass are used in China: slot aluminum single-channel sealed, slot aluminum double-channel sealed, and composite sealing strip type. The single-channel method is being phased out due to its weak sealing properties, which can lead to moisture ingress, condensation, and reduced service life. The other two types primarily use materials such as glass, aluminum strips, gussets, butyl rubber, two-component polysulfide or silicone sealants, desiccants, and composite sealing strips.
Let’s take a closer look at the selection of these key components:
**Glass Selection**
The original glass for insulating glass can be colorless float glass, coated glass, tempered glass, or laminated glass. Ordinary flat glass should be avoided because it lacks sufficient transparency and strength. All glass must meet relevant standards and pass inspection before use. Different batches from different manufacturers should be checked for color consistency, and large color differences should be used in different projects or areas of the building facade.
Glass cutting must strictly follow drawing specifications, and operators should ensure the surface is free of defects like scratches or bubbles.
**Aluminum Strips and Gussets**
Aluminum strips should be between 0.3–0.35 mm thick, with uniform thickness and evenly spaced vent holes. They must be anodized or cleaned properly. High-quality products are essential to maximize efficiency. Gussets should be clean and appropriately sized.
**Desiccant Selection**
There are three main types of desiccants used in insulating glass: those with high volatile absorption, those with low inert gas adsorption, and standard molecular sieves. Users should consult manufacturers to choose the right sieve based on their adhesive. Sieves should have a particle size of 1–1.5 mm and sufficient hardness. They must be stored in dry conditions and used within 1.5 hours after packaging to maintain quality.
**Sealant Selection**
- **Butyl Rubber**: Used as the first seal for aluminum strip insulating glass, it has a very low water vapor transmission rate and acts as an effective moisture barrier. It requires heating, pressure, and extrusion using specialized equipment. Quality varies among manufacturers, so users should select reliable products.
- **Polysulfide Rubber**: The most widely used sealant, it offers good oil and solvent resistance. It should be mixed with metal oxide as a curing agent in a 1:10 ratio. It can be applied manually or by machine. Key qualities include color consistency, long shelf life, UV resistance, and good flowability.
- **Silicone Rubber**: Known for structural strength, aging resistance, and UV protection, it has higher water vapor permeability. It is often used in curtain walls and must be paired with butyl rubber for the first seal. China has started producing certified silicone sealants, with companies like Zhengzhou Zhongyuan and Guangzhou Baiyun now meeting safety standards.
**Composite Sealing Strips**
Developed in the 1980s by American chemists, this material combines a support skeleton (wavy aluminum strip), a seal (butyl rubber), and a desiccant. Its advantages include easy operation, minimal waste, lower labor costs, and a better working environment. However, it absorbs moisture slowly and requires special equipment. When selecting, consider smooth surface finish, quality of the aluminum strip, glue content, and moderate viscosity.
Hebei Xingda Insulating Glass Aluminum Strip Factory
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Hebei Qianmu Fastener Manufacturing Co., Ltd , https://www.qmjgjfasteners.com