Decorative Films Served by Multilayer Structure

Allied Converters Inc., reportedly the largest sheeter of cellophane and polypropylene in the US, has just gotten bigger. The driving force behind this growth, and the subsequent expansion of the New Rochelle, NY-based company's production facility to 55,000 sq ft, is the growing popularity of Allied's proprietary ALUphane decorative film.

The five-layer film, which Allied says has the same affinity for crinkle and deadfold as colored cellophane produced overseas, also is claimed to be superior to the tinted PP film on the market. Allied sheets, slits, rolls, prints, and forms the decorative film using proprietary, in-house-built equipment up to 60 in. in width. The film is used in a variety of ways, such as wrapping gift baskets and trays of food. Allied also sheets other films up to 144 in. wide.

According to Allied president Rich Ellenbogen, one of the advantages of ALUphane is that, unlike other tinted decorative wraps made from PP, the color in ALUphane film does not contaminate the food due to the use of K-Resin styrene-butadiene copolymer (SBC) and a proprietary five-layer film structure.

That is critical for consumer use, says Ellenbogen, because most PP-based films are printed, and the ink will migrate from the film onto sandwiches and the like. And, adds Ellenbogen, "There's nothing worse for a caterer than to put out a platter of sandwiches with blue-tinted mayonnaise!"

The Development Process
First available in the early 1990s, the ALUphane film took almost three years to develop and perfect so it was color-stable and cost-effective to produce. After extensive research, Allied determined that a structure with caps of K-Resin styrene-butadiene copolymer could provide the required premium look, feel, and performance.

"Our goal," explains Ellenbogen, "was to have a highly transparent film with bright colors and a crisp feel that would be cost-effective for the end-user."

Ellenbogen actually began his search for a replacement for colored cellophane--which he had been importing from Europe and South America since DuPont stopped producing it domestically in 1981-in the mid-1980s when fluctuations in exchange rates and overall product quality made it increasingly difficult to consistently meet its own customer demands.

"We had to find an alternative," says Ellenbogen. Allied ultimately chose Phillips Chemical's K-Resin styrene-butadiene copolymer to be the dominant part of the five-layered structure. (Allied briefly ran the film as a three-layer structure, but Ellenbogen ultimately determined that only a five-layer structure could offer the required characteristics.) The color is an additive buried in the layers, with the clear layers on the surface.

The company tried monolayer K-Resin SBC but ran into the same problem it had when PP was used: color migration. Coating both sides of the film was required but was too expensive, and Ellenbogen came up with the idea of coextruding. Trial and error plus modifying the extruding screws got the color values exactly where Ellenbogen wanted them.

Trial runs were done at the Phillips Plastics Technical Center (PTC) at the Phillips Petroleum headquarters. Ellenbogen describes the facility as "a first-class operation. It has actual production equipment to test the different formulations. PTC helped with selecting the right grade of K-Resin that would blend well and eliminate gels. I can't say enough good things about the people there. I wouldn't have a product today if it wasn't for them. We developed a formulation with K-Resin SBC as the keystone that provides excellent deadfold retention and stiffness and also gives the colors extra snap. The trick was to produce it."

Putting It Together
A nationwide search for a company that could produce the product led Allied Converters to Barrier Films. Barrier had both the proper equipment and technical expertise required to mass produce such a complicated film with up to three different resins in each of the five layers, reports Ellenbogen.

The challenge, Ellenbogen explains, was getting the eye appeal and functionality at the right levels, including the proper balance of color, and putting the resin together in the proper configuration. Barrier Films hit the mark.

Originally, Ellenbogen and Barrier Films selected and used K-Resin KR10 SBC from Phillips, recently switching to a newer grade, DK11. The new grade possesses K-Resin's inherent clarity and high surface gloss, and it has the proper amount of stiffness, making it the ideal alternative to use in a cellophane replacement, suggests Ellenbogen.

Roland Planeta, process engineer at Barrier, says that K-Resin DK11 SBC adds stiffness to the multilayered structure. "Our major work centered around getting the colors even," says Planeta. "It's no trick to run film that has streaky or spotty colors."

Adds Bill Wright, Barrier's president, "When we got the assignment from Rich, we thought it would be a slam-dunk. After all, we've been in the film business for many years and successfully met some tough challenges, but we didn't realize we were in for such an odyssey." Barrier Films is licensed to produce the ALUphane film for Allied Converters only.

In 1998 Barrier installed its first seven-layer blown film line on which it runs its multilayered films made with materials such as metallocenes, other polyethylenes, ethylene vinyl alcohol, nylons, PPs, and K-Resin SBC.

"We like to use K-Resin because is has high gloss, stiffness, and heat resistance," says Planeta. "It plays a big part in what we want to do."

"Dead-on" OTR (oxygen transmission rate) is realized by a continuous process of added ingredients, not by a batch process that Planeta says is used typically. OTR is verified in Barrier Film's quality control lab on a Mocon 2/20 oxygen transmission unit.

The film, which is available in stock colors of clear, yellow, orchid, pink, blue, amber, green, and red, can be custom converted to meet specific requirements. Allied, at times, finds itself in the role of contract converter, selling rolls of the film to other converters for further processing, such as slitting/rewinding.

Ellenbogen says, recalling the development process and the choice of suppliers: "I knew what I wanted and speculated on the resins that would be needed. But it was the help I received from Barrier and the people at Phillips' Plastics Technical Center that made what I thought would work a reality."

Converter Information
Allied Converters Inc., New Rochelle, NY; ph: 800/634-3707; fax: 914/235-7123.

Supplier Information
Phillips Chemical Co., Bartlesville, OK; ph: 713/669-3666; fax: 713/669-3541.

Barrier Films, Sparks, NV; ph: 775/331-1179; fax: 775/331-3603.

Mocon/Modern Controls, Minneapolis, MN; ph: 612/493-6370; fax: 612/493-6358.


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