Fiberboards

Fiberboard boxes Fiber bonding resins Fiber boxes Fiber braiding Fiber can packaging Fiber diffraction... 

Woodell s scale Wooden barrels Wooden matches Wood fiberboards Wood fillers Wood finishing Wood flake boards Wood flour... 

Plywood furniture core panels, also about 19 mm (3/4 in.) thick, were normally made of a number of layers of relatively thick, 1.5—3.0 mm (1 /16—1 /8 in.) lower value wood veneers combined with thin surface pHes of the decorative veneer. These assembhes were laid-up from glued veneers and then pressed while the bonding occurred. Both lumber core and plywood core have been almost totally displaced in recent years by particleboard or medium-density fiberboard, both discussed herein. This change resulted from the increasing availabiHty and improved finishing characteristics of composites and from decreasing suppHes of core lumber or veneer of suitable quaHty. 

Fig. 6. The dry-process hardboard (and medium-deasity fiberboard) process.

Production, Processing, and Shipment. Medium-density fiberboards (MDF) are panels made of fibrous raw material and used ia most of the same appHcations as particleboard. MDF products generally have more smooth surfaces and edges than particleboards and are thus preferred for some uses, even though the manufacture of MDF is more cosdy and the product is significantly more expensive. 

Medium-Density Fiberboard (MDF), ANSI A208.2-1994, American National Standards Institute, New York, 1994. 

Eresh fmit and vegetable packaging is often in bulk in a variety of traditional wooden boxes and crates, and cormgated fiberboard cases. At or near the retail level, bulk produce may be repackaged in oxygen-permeable flexible materials such as PVC, with or without a tray of foamed polystyrene. 

A fiber dmm is a cylindrical shipping container made of convolutely wound layers of fiberboard adhered to each other to form a soHd wall. Constmction materials for the ends include metal, plastic, and fiberboard. Fiber dmms are subject to DOT and, for international shipment, U.N. regulations when used forha2ardous materials. Reference to these regulations is necessary before selecting a fiber dmm. 

M1 multiwaU bag of at least three pHes, sift-proof 6PG2 6PH1 within a fiberboard box... 

When selecting a particular paster adhesive, coating material, and coating process for sohd fiber packaging, the fact that sohd fiberboard lacks the open-flute stmcture (to facihtate exit of moisture from internal phes of paperboard) should be considered. It is generally desirable to minimize the amount of process water added with the adhesive or coating with sohd fiber products. Moisture trapped in the filler phes can result in pin holes or bhsters in the coating and/or warp of the sheet (15). 

Wood Bonding. This appHcation requires large volumes of phenoHc resins (5—25% by weight) for plywood, particle board, waferboard, and fiberboard. Initially, phenoHc resins were used mainly for exterior appHcations, whereas urea—formaldehyde (UF) was used for interiors. However, the concern over formaldehyde emission has caused the replacement of UF by phenol-formaldehyde adhesives. 

Fiberboard or hardboard is made of low grade wood and wood waste. In the wet production process, a sheet is produced on a papermaking machine, such as a fourdrinier. A Hquid resole is usually added to the beater section and precipitated onto the wood fibers by adjusting the pH. The moderately dry felt is further dried and cured in an off-line press. 

Reconstituted Wood Products. This category includes three general varieties wood flake board, particle board, and wood fiberboard. The manufacturiag processes are similar for all these products except for the size of the wood particles that are glued together. 

Medium density wood fiberboards (MDF) are semistmctural products used mainly in furniture appHcations (95% of the market). The total shipment of MDF in 1989 was approximately 302 million. 

Roofiag panels have been made from polyisocyanurate foams, both foam- and felt-reiaforced with glass fiber. PhenoHc resias are used especially for decorative laminates for paneling. The substrate may be fiberboard or a core of expanded polystyrene beads. In one case the beads are coated with phenoHc resia, then expanded ia a mold to form a stmctural foam panel. 

FIG. 21-49 Application of a noncontact inkjet printing system used for coding plastic bottles and corrugated fiberboard cartons. (VIDEOJET shown, couitesy of VIDEOJET Systems International, Inc., 1500 Mittal Blvd., Wood Dale, IL 60191-1073.)... 

Medium-density fiberboard (MDF) a flat pressed wood composite panel composed of randomly oriented wood fibers obtained by thermomechanical wood pulping and bonded by hot-pre.ssing by using thermosetting adhesive resins. The panel has generally a density of approximately 850 kg/m- and the average amount of resin solids in the board core section is between 11 % and 14% on dry wood. 

Adhesives based on isocyanate (especially PMDl, polymethylene diisocyanate, more exactly polymeric 4,4 -diphenylmethane diisocyanate) have been used for more than 25 years in the wood-based panel industry [88], but still have a low market value in the wood-working industry compared to systems based on UF-, MUF- or PF-resins. The main application is the production of waterproof panels, but also the production of panels from raw materials that are difficult to glue, like straw, bagasse, rice shells or sugar cane bagasse. They can be used as adhesives for wood-based products like particleboard, oriented strandboard (OSB), laminated strand lumber (LSL), medium-density fiberboard (MDF) or... 

Formaldehyde (bp = — 21°C) is ordinarily found in the laboratory in the form of a concentrated water solution (37% HCHO) known as formalin. At one time it was widely used as a preservative for biological specimens. That application has declined now that formaldehyde has been shown to be carcinogenic. Industrially, it is still used as a component of adhesives used in making plywood and fiberboard. 

Frozen Foods. Corrosion caused by the reaction of foods with aluminum containers is unusual if the products are handled and stored at 0°F or lower. However, the inevitable bad handling of frozen foods during commercial distribution causes undesirable thawing. In this condition, not only does the food deteriorate, but it can also attack the container. Such unwanted reactions can be effectively controlled by using coated aluminum containers. Since aluminum is highly compatible with frozen fruits and citrus juices, it has been used extensively as a liner for fiberboard composite cans, as complete aluminum cans, or as ends in combination with steel can bodies in the frozen food industry. 

On occasion the polyethylene has been blamed for odors caused by other parts of the container design such as screw cap liners, printing inks on the bottle exterior, adhesives used to laminate polyethylene to paper, and the fiberboard or the lining of material used in the separate exterior overpack in which a polyethylene container is held. Careful selection of all of these related materials is always advisable with liquid food products. 

Liners for Fiberboard Cartons, Proc. P1RA/1APRI Int. Conf. Packag. Technol., London (March 27, 1972). 

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