A New Dry Process Multi-Ply Board

A description is given of a new dry process for making composition board from whole, relatively thick, cross-cut wafers with ends tapered in thickness. Core stock with a modulus of rupture of over 3,000 psi at density of 0.65 can be made with less than 1-1/2 percent phenolic resin. Fully automatic equipment was designed for producing, storing, feeding, felting, and pressing the wafers, loading and unloading a new type of multi-opening press, and heat treating, conditioning, trimming, and cutting the finished boards. The first cross-cut wide particles or wafers experimented with had vertical square cut ends. When they were mixed with resin and felted together it was found that, unless they were cut very thin, the effect of the abrupt ends was to introduce hairline cracks in the body of the board. Failure in bending invariably started from one of these cracks. A waferizer was therefore developed to make the elements with tapered ends. Then, wafers 2 inches long and about 0.030 inch thick were mixed with only 1-1/2 percent phenol resin to yield a board of a density of 0.75 with a MOR of over 4,000 psi.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member