Architectural Products

Laminated Glass

Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral (PVB), between its two or more layers of glass. The interlayer 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. Laminated glass offers greater protection for people and property by providing an effective barrier from attack. Although the glass will break if hit with a hammer, brick or similar object, the interlayer can resist penetration, ensuring any attempt to enter a premises will be slow and noisy.

Process
PVB laminated glass is manufactured by combining two or more annealed or heat treated glass sheets bonded with one or more of PVB interlayer's and subjected to heat and pressure, in order to ensure perfect adhesion between the constituent elements.

The lamination process comprises the following steps:

Glass Pre-Processing
(i)  Cutting and grinding
(ii) Washing
(iii) Drying
(iv) Lamination
(v) De-airing/edge sealing

Characterstics
Laminated glass, regard as “Safety glass”, consist of two or more panes of glass with one or more layers of polyvinyl butyral (PVB) sandwiched between them and treated. The glass panes can be basic float glass or tempered or heat strengthened panel. If the glass is broken fragments tend to adhere to the PVB interlayer thereby reducing the risk of injury from falling glass and helping to resist further impact or weather damage. PVB membrane has good tenacity performance and when the laminated glass breaks due to violent force, the PVB will absorb large amount of impact energy and disperse it rapidly. Therefore, it hard to break the laminated glass and the shape of the glass may be maintained even if being broken. Furthermore, personnel inside and outside the buildings will not be hurt by the glass fragment.
PVB laminated glass is manufactured by combining two or more annealed or heat treated glass sheets bonded with one or more of PVB interlayers and subjected to heat and pressure, in order to ensure perfect adhesion between the constituent elements.

Features of Laminated Glass:
Laminated glass provides durability, high-performance and multi-functional benefits and at the same time preserves the aesthetic appearance of glass. Laminated glass provides a solution to many architectural design problems and offers increased protection from the effects of disasters such as hurricane, earth quake and bomb blasts, if suitably designed.
Safety
Security
Sound Control
uv Control
Weather and Disaster Control
Durability
Design Versatility And Installation Ease
Low Visual Distortion

1. Automatic glass loader 5. Nip Rolling
2. Glass washer 6. Loading on racks
3. PVB application 7. Autoclave
4. Overlaying with top glass  

In a clean-room environment PVB interlayer is sandwiched between 2 layers of glass
The sandwich is passed through pressurized rollers and heating ovens to remove air and soften the PVB
The assembly is subject to extreme pressure (8-12 bar) at temperature of 100-150 degrees.

Laminated Glass “Chemistry”
PVB Lamination

PVB Laminated Glass is more than just ‘sticking’ glass to PVB
Under Temperature and Pressure conditions there are mechanical and chemical bonds that form between PVB and glass
It is the combination of Mechanical (adhesive) and Chemical bonds that provide PVB laminated glass its properties, and make delamination difficult.

Quality of Laminated Glass

Optical distortion
Laminated Glass using PVB is usually used in annealed form while providing safety. There are no roller wave distortions present in PVB laminated Glass
Resin laminates due to liquid-cast-in process could have thickness variation causing slight distortions

Delamination
Primarily occurs due to poor manufacturing process.
Occurs mainly at the edges where chemical bonds are weaker. Usually delamination does not extend beyond 10mm of the edges.
Occurs because of prolonged contact with water, improper cutting at site, usage of improper sealants in butt glazed systems

Waviness and Bending
These defects are mostly found in tempered laminated glass or raw glass that already had high degree of waviness
Bending of laminated glass could happen during the nip rolling process if attention is not paid to proper maintenance and operating procedures

There are only few key areas of concern

However, Lamination is a highly industrial process and needs to be carried out by highly professional people

Myths about Laminated Glass

Laminated Glass is Weak
Laminated Glass is no weaker than monolithic glass of similar thickness. In fact, the PVB interlayer provides laminated glass with some degree of flexibility allowing slightly higher deflection to wind-loads. A 22.2 (2mm+0.76+2mm) windshield used in all automobiles can take winds up to 200km per hour.

Laminated glass is prone to thermal breakage if used with solar control glass.
Laminated glass behaves much like monolithic glass as far as thermal breakage is concerned. Thermal breakage is determined by many factors. A simple study can determine if the risk of thermal breakage is high. Tempering is the “penicillin” that solves all thermal breakage related issues, but that is not required in 95% of the cases. Doing a case-by-case analysis solves the problem and reducuces cost

Laminated Glass Delaminates easily
Delamination depends upon the quality of lamination and sometimes on the sealants used. If a quality processor is used and the proper sealant is used there is no reason for delamination to occur. Automobiles over 50 years are still in use with laminated wind-shields.

Safety & Security (Protection against injury)  
Tempered Glass Laminated Glass
1. Resistance to impacts upto 5 times 1. Glass Fragments will stick to PVB interlayer
2. Breaks into small, relatively harmless fragments 2. Very low chance of glass related injury
3. Chance of superficial cuts  
   
   
Tempered Glass Breakage Min. 33.1 Laminated glass breakage

Properties & Application
Displays the visual appearance of monolithic float glass
Offers greater personal safety after breakage because it tends to remain in the frame
Can provide security against hurricanes, burglary, bombs, bullets, etc.
Provides improved sound control due to the sound-damping capabilities of the PVB interlayer
Provides UV protection and thus used for anti fading applications
Use of solar control glasses provide Solar and thermal control
Provides Sound control and thus used in acoustical protection

Application
Sloped/Overhead Glazing
Museums, Prisons, Government Buildings
Jewelry Stores, Banks, Airports
Safety Glazing Applications
Schools, Hospitals, Hotels
Interior Partitions, Office Buildings

Specification
Maximum Size: 2500mm x 4500mm
Minimum Size: 300mm x 450mm
Glass Thickness: 3mm - 80mm
Glass Types: Clear, Tinted, Reflective, Low e
PVB Thickness: 0.38mm, .76mm, 1.14mm, 1.52mm, 1.9mm, 2.28mm (As per specification)
PVB Color: Clear, Opaque, Milky and any other color on demand
Brand of PBV - Trosifol, DuPont, Solutia



 
 
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