Technology Brief

Manufacture and Testing of Fire-Resistant Doors Using De-Inker Sludge or Wastepaper

Background

A technology for manufacturing cores for fire-resistant doors has been developed that has the potential for diverting de-inker wastes from the pulp and paper industry from disposal as solid waste in Washington State. Prototyping and testing of doors manufactured using this technology was conducted by Rockbilt Inc., in cooperation with Vancouver Door Company, under a contract with the Clean Washington Center (CWC).

As a prototype product, Rockbilt selected fire-resistant door cores because of: (1) the need for an innovative door core material, especially at a reduced cost; (2) few competitive products in the market place; (3) the abundance of de-inker sludges (DIS), which are produced at the rate of approximately 1 ton per 5 tons of recycled, inked paper; and (4) the short product development cycle time needed to obtain necessary certification.

Rockbilt's technology uses de-inker sludges that are produced during the processing of recycled paper, especially from coated papers, which typically contain clays for the glossy finish. During this recycling process, sludges are produced when the paper is pulped and the ink is removed. These sludges contain short wood fiber, as well as sizing agents, clays, and ink residues. Currently, this material has few commercial recycling uses and is landfilled.

The Vancouver Door Company's manufacturing facility was a suitable partner for several reasons, most significantly because they currently manufacture fire-resistant doors using competing technologies.

The raw materials used to make the Rockbilt product are commonly available and generally non-toxic in both manufacture and use.

Acceptance of these door cores into the fire-resistant door market requires certification by Warnock-Hersey's Intertek Testing Services (ITS) laboratory. An entire door unit consisting of the core, edge system, door skins, hardware (locks and hinges) and any special features (imbedded windows) must be certified by the laboratory.

Objectives

Objectives for the design element of the project were formulated as follows:
· Equipment and facility setup at the Vancouver Door plant to manufacture fire-resistant door cores using the Rockbilt DIS product;
· Manufacture of test doors (and prototype half-doors) with the same process which will be used for full-scale production, in sufficient quantities to obtain representative samples for laboratory testing;
· Pretest inspection by an ITS laboratory representative of the manufacturing process (required for full certification);
· Confirm key manufacturing parameters to facilitate Vancouver Door in its expansion to a full-scale production line at its Puyallup plant (once the doors are certified by the ITS laboratory);
· Prototype and full-scale certification testing at ITS laboratory in Pittsburg, California; and
· Document all test data and findings so that interested Washington State businesses can access the technology.

Testing of Prototypes

Furnace testing of prototypes occurred at the following locations: Warm Springs, Oregon, manufacturing facility, which was equipped with a test furnace for half-height doors; Rockbilt's Goldendale site, where Rockbilt constructed a test furnace using the Warm Springs furnace as an example; and Warnock-Hersey's ITS laboratory in Pittsburg, California, prior to the full-scale certification tests.

Rockbilt determined from tests performed at the Warm Springs site that it was necessary to build a test furnace similar to the type used at Warm Springs. Rockbilt performed a number of test burns with this furnace.

In-house burn tests were encouraging with the initial simple core material. For complete doors, an edge system is required to be bonded around the core material to provide structural strength for hardware (hinges and door locks). In these early tests, however, no edge system was used.

Two doors were cast using the initial formulation. Vancouver Door formed the cores into half-core doors for preliminary tests at ITS. Both systems passed the fire portion of the test but failed in the water spray, but not to the same extent. Observations during the fire portion of the test and examination of the failed panels revealed that, although the cores survived, both edge systems were failing because of shrinkage and curling. Rockbilt revised the original formulation for further testing.

Three doors were cast at Vancouver Door using a Georgia-Pacific edge system, assembled into full-size doors, and tested at ITS. The selected door from the two doors sent to ITS narrowly failed the test for 90-minute certification because: (1) the curl of the door at the end of the fire test, which promoted disbondment from the certified edge system; and (2) collapse of the door during the water spray portion of the test (only 7 seconds from passing the test). On this basis, Rockbilt decided to perform one last burn test on the remaining door, seeking 60-minute certification rather than 90-minute certification. This test was successful and the door passed both the fire and hose stream portions of the test.

Conclusions

Early certification testing results indicated that Rockbilt's concept of a castable fire door core with a significant content of recycled DIS is desirable, viable and practical. Difficulties with bonding the edge system to the door core, which resulted in door panel failure, can be overcome with slight modifications to the door manufacture.

This technology also has the potential for achieving a significant reduction in the amount of DIS currently disposed of in landfills.

Fact Sheet Issue Date: January 1998

Acknowledgments

This technology brief was prepared by CWC, the Managing Partner of the Recycling Technology Assistance Partnership (ReTAP). ReTAP is an affiliate of the national Manufacturing Extension Partnership (MEP), a program of the U.S. Commerce Department's National Institute of Standards and Technology. ReTAP is also funded by the U.S. Environmental Protection Agency and the American Plastics Council.