Volume 39, Issue 6, June  2004

Laminated Glass: 
Looking at its Evolution and Future
by Robert Inderlin 

Over the last 100 years, the concept of adhering two lites of glass together has gone from an accidental finding (the discovery of a celluloid adhered to a flask by Edouard Benedictus), to a diverse component that is used throughout the world for safety, security, acoustical performance and aesthetic appeal. In fact, there have been more launches of laminated glass products in the last ten years than there have been since its inception. 

Laminated glass has gained ground as a preferred option for applications such as burglar resistance in urban areas, impact resistance in windborne regions, acoustical performance for sound deadening in high traffic areas and around airports, high security for correctional institutions and blast-resistance in buildings that are now vulnerable to terrorist attacks. In addition, there is a significant increase in laminated glass usage in decorative, architectural applications for both interior and exterior use. 

Changing Times 
With the adoption of new impact codes, numerous residential and commercial window and door companies are getting involved in testing programs so that they can meet the demands of the ever-growing need for protection against mother nature and other unexpected threats. With this need comes new developments and improved interlayer materials. In the United States, nearly one third of our new construction is within a coastal region or windborne area, and requires higher performing laminates to achieve necessary design pressures. In addition to new construction, many existing windows and doors in older homes are being replaced with impact systems. Consumers have become more educated about the products available to them and do not mind spending a few extra dollars for 24-hour piece of mind, not to mention avoiding the pain-stacking duty of installing and breaking down hurricane shutters. 

Unbalanced laminates are also gaining in popularity. Both nationally and internationally, local and federal agencies are now requiring glass-to-polycarbonate laminates be used for high-security applications. Glass-clad polycarbonates are also becoming popular in the jewelry industry, as insurance companies now require jewelry cases in stores be more resistant to burglaries and smash-and-grabs than they have in the past. New developments in laminated glass are also being launched in the marine industry and in applications where water and moisture are inevitable. Our industry now has interlayers that can be fully immersed in water with no effect on the products adhesion or performance when encapsulated by glass. 

Changes and Trends
Another trend becoming popular in laminated glass is in-house fabrication. More and more window and door companies are manufacturing impact-resistant glass in there own facility as opposed to outsourcing to the large glass fabricator. With these new technologies, such a company can set itself up to laminate its own glass. For a small capital investment, fabricators can manufacture products that can be approved as impact glass and are more cost effective than buying it. Other benefits of in-house laminating include substantial savings when laminating shapes, less waste, better quality control, shorter lead times and, most important from a business perspective, bigger profit margins. 

Decorative Glass
In the decorative glass industry, laminated glass is being used in applications with opaque, translucent and transparent colors, decorative rice papers, prints transferred onto films and open weave materials, leaves, feathers, chicken wire and anything else imaginable, giving architects and designers infinite ideas and endless opportunities. New, high-performance interlayers provide for unprecedented adhesion when laminating float glass to patterned or kilned glass with deep voids, thus providing an added safety feature to an already popular product. Recent developments in decorative glass may soon “raise the eyebrows” of the beveled glass industry, as more cost-effective ways to produce doorlites and stained glass with safety features are now on the launching pad. Within my own company, we are now working on a high-speed method of re-producing lead or brass came lines with decorative textures and bevels. Colors can also be incorporated into this process, giving it the look of traditional stained glass. This is the laminated glass industry’s response to low-cost Chinese imports. 

In the early years of the twentieth century, those who knew of laminated glass were ecstatic to know that a safety feature could be applied to a car windshield. Almost 100 years later, laminated glass is still saving lives and has diversified into a growing number of applications, both simple and complex. With continued innovation and new technologies, one can only imagine where laminated glass will be applied in the next century. 

The Glass Association of North America’s (GANA) Laminated Glazing Reference Manual, 2003 edition, describes four types of interlayer material:

• Plasticized Poly Vinyl Butyral (PVB): PVB is used most often for mass production of stock glass sizes and custom products. PVB-laminated glass with a .015-inch interlayer may comply with the Category I requirements of the Consumer Product Safety Commission (CPSC) 16 CFR 1201 standard. PVB-laminated glass with an interlayer .030-inch or thicker may meet both Category I and II of CPSC 16 CFR 1201, and may also meet ANSI Z97.1 test requirements. (As defined in the GANA Laminated Glazing Reference Manual: Category I glazing must withstand one 150 foot-pound impact produced by impacting the glazing material with a 100-pound shot bag from a vertical height of 18 inches or break into a pattern that is acceptable, as defined in the standard, when impacted. Category II glazing must withstand one 400 foot-pound impact produced by impacting the glazing material with a 100-pound shot bag from a vertical height of 4 feet or break into a pattern that is acceptable, as defined in the standard, when impacted.) In addition, a PVB interlayer of .015 inch may comply with CAN2-12.1-M79, Category I of the Canadian Standard for Glass, Safety, Tempered or Laminated. Laminated glass made with a .030-inch PVB interlayer may meet both Category I and II of the Canadian Standard.

• Aliphatic Polyurethane Sheet: This interlayer is used for laminating glass-clad and all non-coated polycarbonate or acrylic units. It is used between one or more layers of glass and plastic. Glass-clad polycarbonate is used in forced-entry and ballistic applications. A laminated polycarbonate is used in applications for forced-entry, ballistics and bomb-blast with no-spall performance. Laminated polycarbonates can meet CPSC 16 CFR 1201 Category I and II test requirements, as well as ANSI Z97.1 without breakage.
 
• Cured Resins: This process involves pouring or pumping a liquid laminating system between layers of glass and/or plastic. As the GANA glazing manual explains, a double-sided tape acts as a dam and spacer to provide the required thickness. The resin is cured by exposure to ultraviolet light, heat or chemicals. Laminated architectural glass made with a .030-inch cured resin interlayer may meet CPSC 16 CFR 1201 test requirements for Category I and II, as well as ANSI Z97.1 requirements.

• Ionoplast: These thermal plastic resin interlayers are more rigid than PVB and are typically used in high-load and security applications.

For more information about laminated glass refer to GANA’s Laminated Glazing Reference Manual. To order, visit www.glasswebsite.com.

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