What is laminated glass?

 Laminated glass is a type of safety glass made by bonding two or more sheets of glass together with a transparent interlayer. Thanks to this interlayer, when laminated glass shatters upon impact, the glass fragments remain bonded together.

The fragments remain adhered to the interlayer film rather than scattering, minimizing the risk of injury. Even after breaking, the glass retains a certain degree of visibility, thereby providing a protective barrier.

Laminated glass offers transparency, sound insulation, and safety. Compared to ordinary glass, it has distinct advantages in protecting both people and property.

(1) Safety: The safety characteristics of laminated glass are demonstrated through its impact resistance, penetration resistance, and wind pressure resistance. When laminated glass breaks, the interlayer holds the glass fragments in place, preventing shards from scattering and causing injury or property damage. Laminated glass outperforms tempered glass in withstanding hurricanes and earthquakes; when used as an exterior building envelope, it can resist impacts from wind-borne debris.

(2) Security: Laminated glass offers excellent protection against burglary, bullets, explosions, and typhoons. Due to its superior impact and penetration resistance, laminated glass cannot be completely destroyed within a certain period of time when subjected to explosions, gunfire, or attacks with tools such as sledgehammers.

As the thickness of the PVB interlayer increases, the impact resistance of laminated glass increases significantly. For PVB films of the same thickness, the impact resistance of laminated glass also increases as the glass thickness increases.

(3) Sound Insulation: Doubling the thickness of the PVB film increases sound insulation by 1 dB. The sound insulation provided by the film results from a damping effect; this effect varies with temperature, and higher temperatures enhance sound insulation performance. Therefore, climatic and geographical differences can affect the sound insulation performance of laminated glass.

(4) Fire Resistance: Laminated composite fire-resistant glass with fire-retardant properties is a specialized type of laminated glass composed of two or more glass panes bonded together with a transparent interlayer, which consists of intumescent fire-retardant adhesive or fire-resistant film. When exposed to flames, laminated composite fire-resistant glass acts as a barrier against fire, withstanding flame exposure for approximately 90 minutes. It effectively limits heat transfer across the glass surface and becomes opaque when heated.

(5) UV Protection: PVB interlayers can block up to 99.9% of UV rays, preventing valuable furniture, exhibits, or merchandise from fading due to UV radiation.

(6) Thermal Insulation: By modifying standard PVB interlayers, various energy-efficient PVB interlayers can be produced. For example, laminated glass made with thermal insulation interlayers can effectively block infrared radiation while maintaining high visible light transmittance.

Types of Laminated Glass

Laminated glass is classified into two types based on production methods: dry-process and wet-process laminated glass.

Dry-process laminated glass is a composite transparent glass product made by sandwiching organic adhesive films between two or more glass panes, followed by preheating, pre-pressing, degassing, and then bonding under high temperature and pressure. The primary organic adhesive films include PVB (polyvinyl butyral) film, EN (EVA) (ethylene-vinyl acetate) film, and PU (polyurethane) film, Currently, PVB film is the most widely used. The dry method is also known as the film hot-pressing method.

Wet laminated glass is produced by pouring a prepared organic adhesive slurry between two or more pre-assembled glass sheets. Through photothermal polymerization, the glass and the organic adhesive bond to form a single unit, creating a transparent composite glass product. The base glass can be float glass, wire-reinforced glass, mesh-reinforced glass, tempered glass, semi-tempered glass, or surface-modified glass. Dry-process laminated glass exhibits significantly better UV resistance and aging resistance than wet-process laminated glass, and it also performs better at low temperatures. In many wet-process laminated glass products, the organic interlayer becomes noticeably brittle at -15°C, resulting in a significant reduction in penetration resistance.

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