Overview

Laminated glass (LG) as a type of safety glass is considered a fantastic alternative to normal glass. It offers a tough, robust structure that is hard to break and holds together when shattered.

The reason for being held in place even in the case of breaking, is a thin polymer interlayer, typically of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), lonoplast polymers, cast in place (CIP) liquid resin, or thermoplastic polyurethane (TPU), between its two or more layers of glass. The interlayer, made through heat and pressure, keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic “spider web” cracking pattern when the impact is not enough to completely pierce the glass.

In the process of designing any building, safety along with beauty and comfort is of special and high priority. Considering the glass nature, the selection of thier usage in different parts of a building, needs accurate knowledge and attention.

Laminated glass, along with preserving the prper characteristics of light and energy, will protect the lives and property of residents of the building while protecting against natural disasters such as storms and earthquakes, as well as certain accidents such as theft, sabotage, shooting and explosion. 

In addition to its specialized features, the glass also prevents ultraviolet rays from passing through and these issues will be explained in detail later.

Applications

So, the robust nature and thickness of laminated glass lend it a whole host of benefits:

• Increased security: The strength of laminated glass makes it almost impossible to break. Even if a break was to occur, the interlayers holdup the strength of the structure so that widening the gap is extremely difficult to do.
• Reduced emissions:  Low-emissivity glass can help to reduce heat gain from the sun, which allows air conditioning to be used less frequently, reducing energy consumption and emissions to be reduced.
• Reduced noise pollution: Installing a thick piece of laminated glass causes noise waves to become disrupted when they travel through the material, helping to reduce noise pollution.
• Increased safety: As the glass doesn’t shatter when broken, there is a reduced risk of someone being cut or injured by shards of glass.
• Protection from natural disasters: In the arrival of natural disasters, laminated glass will remain in its frame, reducing the risk of accidents and making a life-threatening situation slightly safer.
• More design choice: Laminated glazing is available in many colours, tints or tones, and can be manufactured straight or curved for greater versatility in appearance.
• An additional property of laminated glass for windows is that an adequate TPU, PVB or EVA interlayer can block nearly all ultraviolet radiation. A thermoset EVA, for example, can block up to 99.9% of all UV rays.

• Also, colored PC films can be combined with the thermoset EVA material, during the laminatingprocess, in order to obtain a colored glass. Digital printing is now available for architectural applications by either printing directly to the glass, and then laminating or printing directly to the PVB as is the case with the trademarked Dupont SentryGlas Expressions process. Full CMYK images can be printed to the interlayer prior to the autoclave process, and present vivid translucent representations. This process has become popular in architectural, Interior design, and signage industries.

Laminated glass provides a very strong, yet transparent layer with a variety of uses

• For use in buildings where hurricanes or other natural disasters are a high risk
• As windows for companies or homes at higher risk of break-ins
• As display cabinets for valuables, such as jewelry stores
• Aquariums or animal enclosures
• Glass floors
• Glass stairs
• Skylights
• Glass roofs

Process

Modern laminated glass is produced by bonding two or more layers of ordinary annealed or tempered glass together with a plastic interlayer, usually polyvinyl butyral (PVB), Thermoplastic Polyurethane (TPU) or ethylene-vinyl acetate (cross-linked EVA). The interlayer is meant to improve the mechanical properties such as impact strength, fracture toughness, and failure modes in laminated glass. The plastic interlayer is sandwiched by the glass, which is then passed through a series of rollers or vacuum bagging systems to expel any air pockets. Then the assembly is heated for the initial melt. These assemblies are then heated under pressure in an autoclave (oven) to achieve the final bonded product (fully crosslinked in the case of the thermoset EVA).

Once a thermoset EVA is properly laminated during the process, the glass can be exposed frameless. There should be no water/moisture infiltration, very little discoloration, and no delamination. Newer developments have increased the thermoplastic family for the lamination of glass. Beside PVB, other important thermoplastic glass lamination materials today are ethylene-vinyl acetate (EVA), thermoset EVA, and thermoplastic polyurethane (TPU). The adhesion of TPU is not only high to glass, but also to polymeric interlayers. Since 2004, metallized and electroconductive polyethylene terephthalate (PET) interlayers are used as substrate for light emitting diodes and laminated to or between glass.

• Top layer: Glass
• Interlayer: Transparent thermoplasticmaterials (TPU or PVB, EVA) or transparent thermoset material (EVA)
• Interlayer: LED (light emitting diodes) on transparent conductive Polymer
• Interlayer: Transparent thermoplasticmaterials (TPU or PVB, EVA) or transparent thermoset material (EVA)
• Bottom layer: Glass 

Bullet-proof Glass

Bulletproof glass is a laminet one in which, depending on the safety degree of glass, two or more layers of glass with special Pvb layers and suitable thicknesses are laminated. in the process of producing this product, the glass and polycarbonate are glued together at high pressure and heat so thatno seams remain between the layers. when the bullet hits the glass, the first layer of the glass is punctured, but the plastic layer absorbs the pressure of the bullet and stops it. In this way, the bullet can not reach the last layer of the glass.

Zarin Glass bulletproof glass test

Characteristics

This type of glass is quite resistant to shooting, so that after the bullet hit:

1. No aperture is created on the glass surface and this prevents the bullet from entering the inside space.
2. After being cracked and broken down, no particles or chips from the glass will be discarded or thrown, thereby protecting the occupants from any damage.
3. In recent years, bombing has become one of the usual methods of terrorist attacks. Explosion waves cause damage, injury, fire and hearing damage. Broken pieces of the glass are the most important cause of injury at the site of explosion. Bulletproof glass shows the best performance against explosion, and the damage caused by the throw of the broken pieces will be minimized.

The classification of these glasses is based on the variety of weapons and ammunitions. The orientation of their installation is so significant in their function.