| 摘要 |
<p>A panel consisting of a support of wood or other hygroscopic material covered on at least one side with an impermeable plastic film bonded to the support, the film and its underlying layer having very fine perforations practically invisible to the eye but providing a means of escape for gas or vapour arising in the support layer when the temp. is increased. The impermeable film may be PVC, and may be bonded to the base with an acrylic, vinyl or neoprene adhesive. Both faces may be covered with film and the perforations may be at intervals of 1-20 mm. and of dia. about 0.1 mm. They may be made by a tool having fine points attached to a rotating cylinder or vibrating base. The perforated film avoids faults which usually develop because moisture and gases cannot escape.</p> |
