Glass - Laminated Glass

Topics Covered

Background

Key Properties

Applications

Building Industry

Transport Industry

Security Applications

Background

As the name suggests, laminated glass comprises layers of glass in a sandwich type arrangement. In this case, the normal configuration is a layer of flexible polymeric material sandwiched between two layers of glass. Laminated glass is produced using one of two methods:

         Poly Vinyl Butyral (PVB) laminated glass

         Cast in Place (CIP) laminate

PVB laminated glass is produced using a heat and pressure process, sandwiching a flexible interlayer between layers of glass. Generally, the interlayer has a thickness of 0.38mm, except for applications such as automotive windscreens, which use a 0.76mm thick interlayer.

CIP laminated glass is manufactured by pouring resin into the cavity between two adjacent panes of glass. Interlayer thicknesses of 1.0 to 1.5mm are common for CIP laminated glasses.

Laminated glass has the advantage over standard glass in that it will not shatter as the polymeric interlayer is not subject to brittle failure as is the glass. Furthermore, the interlayer provides a barrier against penetration. Tinted interlayer materials can be used to help minimise heat transmission, while the polymeric material also acts as a sound deadening layer, damping sound transmission in a manner equivalent to glass twice as thick.

Key Properties

         Increased safety factor compared to standard float glass

         Resistant to shattering

         Improved acoustic damping properties compared to standard float glass

Applications

Building Industry

Many building applications require a glass exterior but at the same time need to minimise sound transmission, such as a restaurant on a busy street. For this reason, laminated glasses with good acoustic dampening properties are used. Such glasses also offer many of the advantages outlined in `security applications’ below.

Transport Industry

Laminated glasses are used for windscreens for all forms of transport from cars to trains. They are typically PVB laminated glass using a thicker interlayer of about 0.76mm. This gives the material a good resistance to penetration from rocks etc while at the same time providing excellent light transmission.

Security Applications

Many applications require transparent panels for viewing purposes. At the same time they may also need to keep out burglars or bullets, or just provide a safer alternative to float glass. In these cases laminated glasses can provide the solution due to their resistance to shattering and penetration. Safety applications (e.g. shower screens) may use thicknesses as low as 6.38mm (comprising 2 layers of 3mm thick glass with a 0.38mm interlayer), while burglar resistant grades may utilise similar structures, but thicker glass panels. Bullet resistant glasses range in thickness from 24mm to 53mm, depending on what type of weapon they are trying to stop. These glasses may involve several layers of glass each separated by a polymeric interlayer.

 

Primary author: AZoM.com

 

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