Adhesive composition and plastic film covered fiberboard products produced therewith

Claim 1

A PLASTIC SHEET COVERED ACCOUSTICAL CEILING TILE COMPOSED OF A POROUS FIBERBOARD BODY HAVING A SUBSTANTIALLY PLANAR NORMALLY EXPOSED ACOUSTICAL PERFORATED SURFACE TERMINATING AT MARGINAL EDGES PROVIDING A GENERALLY RECTILINEAR CONFIGURATION AND THICKNESS SUBSTANTIALLY LESS IN DIMENSION THAN THE DIMENSION OF SAID SURFACE; A THIN SHEET OF RIGID SYNTHETIC PLASTIC MATERIAL COVERING SAID SURFACE AND HEAT FORMED OVER THE MARGINAL EDGES OF THE FIBERBOARD BODY; SAID PLASTIC SHEET MATERIAL BONDED AT THE MARGINAL EDGES TO THE FIBERBOARD BODY BY AN ADHESIVE MATERIAL COMPRISING ABOUT 100 PARTS BY WEIGHT OF A NATURAL THERMOPLASTIC RESIN DERIVED FROM HARDWOOD AND HAVING A SOFTENING POINT BY ASTM RING AND BALL OF AT LEAST 100*C.; ABOUT 200-300 PARTS BY WEIGHT OF A RUBBERY SYNTHETIC BUTADIENE ACRYLONITRILE AND 62-72% BY WEIGHT BUTADIENE; ABOUT 15 PARTS TO LESS THAN 30 PARTS BY WEIGHT OF NORMALLY SOLID DICYCLO-SUBSTITUTED PHTHALATE; AND UP TO ABOUT 20 PARTS BY WEIGHT OF A GREASELESS SYNTHETIC DETERGENT AS EMULSIFYING AGENT, SAID PLASTIC SHEET MATERIAL BEING LASTINGLY BONDED TO THE FIBERBOARD BODY BY REASON OF SAID ADHESIVE.