Volume 49, Issue 4 - April 2014

NewsAnalysis:Trends

EVA Finds Popularity Among Decorative Fabricators

While polyvinyl butyral, or PVB, has been a recognized component of laminated glass for decades, an increasing number of fabricators are easing into producing laminated glass using ethylene vinyl acetate (EVA) interlayers, particularly when it comes to producing decorative laminated glass.

“In the last year, the demand for EVA has increased drastically,” says Daniel Boari, technical sales and account specialist for Interlayer Solutions Inc., a Montreal-based distributor of products for glass lamination.

EVA offers a number of attractive enticements for fabricators looking to expand their product offerings. For starters, EVA requires a significantly smaller upfront investment.

One reason, explains Rick Dominguez, with machinery distributor Jordon Glass Group in Miami, is that EVA is simpler to store than PVB. “Both of these [interlayers] will benefit from a clean room, but with EVA you can store it with a clean room and that’s it, whereas with PVB you need to have climate control,” he says. If the PVB is not stored in a chilled environment with humidity control, you run the risk of a bubbling effect within the material, he explains.

“It’s a difficult climate to reach, especially for us in the Midwest where we suffer power outages, and we’ve got 115 degree summer days with 60 percent relative humidity outside,” points out Robert Carlson, mechanical engineer with Tristar Glass in Tulsa, Okla. “We can reach it, we have the equipment, but we save a ton of energy by not keeping a room refrigerated.”

These fabricators say that today’s EVA offers excellent clarity, although that’s to admit that clarity has been an issue in the past. And Carlson finds that, in many instances, PVB is clearer still. “EVA has great clarity, don’t get me wrong,” he says. “If you saw a piece of glass laminated with EVA you’d think that’s really clear, but then if you held up a piece of PVB laminated glass next to the EVA you’d realize the PVB is clearer.”

“Clarity-wise, good quality EVA is very comparable to PVB, if not clearer,” Dominguez contends. In the past, there might have been some haze due to plasticizers, he notes, but this is rarely the case today.

“An EVA should be as clear as the PVB,” Boari agrees, but he adds, “over the time and with aging, the yellowing index of EVA is much lower than with PVB, which means that the glass, laminated with EVA, will stay exactly as it was.”

In addition, these individuals say that EVA allows more options than PVB.

According to Boari, “The adhesion with other materials (glass, PET, PVC or others) is superior to what PVB can offer.” Or, as Carlson puts it, EVA “sticks to just about anything.” He explains, “If you are going to put cloth or rice paper or other substrates into your laminate, EVA is a very sticky, highly adhesive product. PVB likes to stick to glass and pretty much just to glass. Your adhesion is going to go way down if you try to laminate PVB to, for example, a PET film or a fabric substrate or cheese cloth.”

“[EVA] has the ability to adhere to and be compatible with a multitude of materials whereas PVB tends to stick only to glass and itself,” agrees Larry Cripps with Wixom, Mich.-based fabricator Glass and Mirror Craft’s decorative division. He points out that for PVB, “That is not a bad trait when you need strength and weatherability, but when you need quality decorative interior products, EVA works wonderfully.”

As far as weatherability, Cripps finds, “EVA is primarily used for interior applications where weatherability is not a factor.”

However, others say that certain EVA products can offer protection against water.

“When you are using the proper EVA, your laminated glasses could be used frameless and there will be no moisture or water infiltration,” Boari says.

“They say [EVA] is waterproof; once it’s crosslinked it can’t absorb moisture,” Carlson explains, citing product manufacturers’ explanation of the chemical process EVA undergoes when its polymers bond during lamination. “It is significantly better in exposed edge applications. You could use EVA and you wouldn’t have to worry about it potentially absorbing moisture over time and delaminating.”

Although some fabricators choose to use both products, in many cases cost will determine a single product of choice.

“Usually when we talk about final products that promote volume and low pricing, over added value and quality, the manufacturer would rather use PVB than EVA,” Boari finds.

“PVB is significantly cheaper,” Carlson agrees. He says the interlayer can be roughly a quarter of the cost of EVA. EVA is typically the product of choice for Glass & Mirror Craft because of the company’s use of decorative interlayers alongside the EVA. “EVA makes a good choice for a decorative application when you have the time to make it right and the tools to make it stay that way,” Cripps says. “When there are as many different options for decorative interlayers, it is nice to have many types of adhesive at hand to decide in-house which product is best suited for that decorative product, for the customer in that situation.”

—Megan Headley

 


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