GRANVILLE, OHIO - A 30-year-old pultrusion technology that replaces the traditional resin bath by pumping resin directly into the die could get new life because of improvements by Owens Corning, company officials said. Owens Corning held the first formal public showing of its modified injection die impregnation system April 29 in Granville, at the company's Science and Technology Center. It had been detailed in a technical paper published two years ago.
In traditional pultrusion, glass fibers are drawn through a bath of liquid resin, then formed by pulling the fibers through a die. Injection die impregnation, first developed in the early 1960s in Germany, pulls dry glass fibers into the die and introduces the resin there, according to Jim Gauchel, research associate at the sprawling Granville facility.
But Gauchel said the old process required pultruders to use highly specialized types of composite reinforcements, such as a bulk roving, or a roving run through an air jet to fluff out and separate individual glass fibers. But some of the strength of the pultruded rovings is lost, he said.
Owens Corning has modified the technology to accept standard glass reinforcements. One innovation is higher-pressure injection of the liquid resin into the die. Normal injection runs at about 60 pounds per square inch. Owens Corning is running its impregnation system at 400 psi.
Another benefit is a much lower rate of emissions because the system requires no open resin bath. Owens Corning claims modified injection die impregnation reduces styrene emissions more than 70 percent and improves resin use efficiency 5-10 percent.
Gauchel said one Chicago-area pultruder, Werner Ladder Co. of Franklin Park, Ill., uses the Owens Corning technology commercially. He said Owens Corning still is compiling tests to verify emissions reductions.
``This is a process in development,'' he said.
Reinforcements must be more carefully aligned than in traditional pultrusion, he said.
In Granville, Owens Corning demonstrated a line pultruding a flat piece - with two different colors and resins, one on top and one on bottom of the part - to show the resin injection system. The company conducted tours for the trade press and about 45 members of the Pultrusion Industry Council of the Society of the Plastics Industry Inc. of Washington. The council was holding its spring meeting in Columbus.
Processing improvements like die injection are needed to reduce the cost of pultruded products against steel, Gauchel said. Still, he cautioned that ``price is not going to buy us a lot,'' and that pultruded composites, with many characteristics superior to steel, will continue to carry a price premium.
Pultrusion remains a small part of the overall composites industry - just 5.6 percent of the North American industry.
But the sector is growing. Pultruded products grew by 8.7 percent a year from 1990-1995, and Owens Corning officials think growth will top 10 percent a year for the second half of the decade, Gauchel said.
Owens Corning employs 1,100 scientists and technologists around the world - about half of them in Granville.
Owens Corning filed 60 patents in 1995, three times more than in 1994, according to spokeswoman Sandra Krezmien-Funk.
Now the company is beefing up basic, molecular research as well. David Dwight, a veteran of 20 years of university teaching and industry, was hired two years ago to set up a laboratory to study the molecular relationship be-tween glass fibers, coupling agents and resin.
The lab opened last summer. Technicians painstakingly study single fibers, about one-fourth the size of a human hair. The lab also does molecular modeling. Dwight said the level of research and development is rare in the composite reinforcement industry.
In another area of the campus, crews are finishing work on a new design center, housed in a refurbished estate home on the Gran-ville grounds. Partner in the project is the Westerville, Ohio-based Product Design Center Inc., formed five years ago by former Owens Corning engineers.
Customers and Owens Corning employees will hatch new products at the center. Recent new products include:
The MiraVista Shake, a composite shingle that resembles cedar. The shake has a polyester resin base with a high level of inorganic filler. Test marketing in California will begin soon. An-drew Mafeld, vice president of global materials applications and the design center, said the shingle is made by compression molding, although other processes are being studied.
TruMelt packaging for Owens Corning's asphalt that itself is made from asphalt and a proprietary binder. When roofers empty the package, they toss it into the heating kettle and it melts down into the asphalt - eliminating disposable paper packaging. Although few details are being released, the drum-shaped package is made by injection molding, Mafeld said.
