Volume 37, Issue 4, April 2002

Simple and Affordable
        Using Liquid Resins for Glass Lamination
By Michael Burris and Jon Shay

According to UCB, liquid resins ease                                                                                                                                     the laminated glass manufacturing                                                                                                                                     process.

Liquid resins, once referred to as cast-in-place resins, offer small, medium and large glass operations innovative ways to provide laminated glass to the customer quickly and efficiently. The low startup costs of as little as $2,500 coupled with a quick, make-to-size laminating process, allows anyone to produce a ready-to-ship, high-quality, laminated glass in as little as 25 minutes.

Numerous Possibilities
The types of laminates available are virtually limited only by the imagination. Various pigments are available and after mixing with the resins can provide an almost unlimited array of laminate colors. Resins are used to laminate bent, all types of patterned, slump and ornamental glass. Like other laminate types, they adhere through mechanical adhesion but also have the added advantage of chemical adhesion by reacting with the glass to provide a chemical bond between the cured resin and the glass.

Safety and security issues have come to the forefront of people's minds, and the marketplace is increasingly asking for such protective measures from their windows. For instance, after the destructive power of Hurricane Andrew struck South Florida in 1992, liquid resin laminated glass was quick to respond by providing a hurricane-resistant glass option.

Resin laminates have since been used extensively in the growing hurricane market passing the most stringent building code standards including Dade County Florida's impact and cycling tests. Whether your application calls for hurricane resistance or just passing the safety standards CPSC 16 CFR 1201 and ANSI Z97.1, liquid resin laminates can give you and your customer the protection you both desire.

In addition to safety and security issues, noise pollution is a growing problem with the population boom in cities that is pushing homes and businesses closer to high traffic areas such as highways and airports. Using liquid resins, laminated glass can be made that will meet safety codes and provide the end user with an acoustical barrier to exterior noise.

Manufacturing Process
The process used to manufacture laminated glass using liquid resins is simple, and the equipment is relatively inexpensive. It involves just five easy steps:

• Cleaning two glass plies;
• Applying double-sided tape to the perimeter of one glass ply;
• Placing the second ply onto the previously taped ply to create a cavity;
• Filling the cavity by pumping in the resin; and
• Allowing the resin to cure.

The glass should be cleaned thoroughly to ensure a good glass surface to which the resin can bond. The double-sided tape serves two purposes. The tape acts as a barrier that confines the resin until it is cured and it helps set the interlayer thickness. After the second ply of glass is applied to the first ply, the edges are pressed together to form a secure seal. The resin is then pumped accurately into the cavity using a calibrated pumping system. Calculating the proper amount of resin to pump into the cavity is critical to ensuring the proper laminate thickness.

The final step is to cure the resin. The cure process is what differentiates the two main types of resin systems from each other.

Resin Types
There are two types of liquid resin systems available: ultraviolet (UV)-curable resins and chemical-curable resins. They are similar in the lamination or glass preparation process but differ drastically in the way they are cured. UV-curable resins cure by exposure to low-intensity UV lights (blacklight light bulbs) in as little as 20 minutes of exposure time.

Chemical curable resins cure with thermal energy, either at ambient temperatures for a period of hours or at elevated temperatures if faster cure is desired. UV-curable resins are single-component systems that do not require mixing prior to use. This helps to ensure a more consistent resin laminated product. Chemical-curable resins require the mixing of two or even three components, and inadequate mixing can alter the final properties of the laminate.

Since UV-curable resins do not begin to cure until exposed to UV light, they have a virtually limitless pot life. Chemically-cured resins begin the cure process immediately upon mixing, and have a limited time in which they need to be pumped between the glass and cured.

Chemical cure can be used when there will be a problem getting light to every section of the laminate. Anything that blocks UV light from getting to the liquid resin (e.g., embedded objects on art glass or opaque glass) will impede the cure of the resin, which would not be the case for a chemically curable system. Both UV and chemically cured systems can be used to make pigmented laminated glass.

Liquid resins have been around for more than 20 years, and have made their presence felt in the market in the past few years. They provide a top-quality laminate using a fast, simple and efficient process. The startup costs are comparatively inexpensive. By having the ability to laminate all types of glass available to the industry and not just a select few, resin laminating can provide the laminator with the flexibility to provide architects the products they need to be creative. With all of this information, the real question to ask is not, "Why use a liquid resin for laminating glass?" but rather, "Why am I not using a liquid resin to laminate glass?"

Michael Burriss and Jon Shaw serve as a chemist and technical manager, respectively, at UCB Chemicals in Smyrna, Ga.

USG