| 摘要 |
A wet press in a paper-making machine has an endless supplemental belt movable in an endless path inside the endless path of the papermakers felt, the belt being formed from substantially incompressible film of a synthetic polymer and having a plurality of perforations therein of a size sufficient to enable the retention of moisture therein by capillary action. The film is preferably a crystalline structure and may be made of polyethylene terephthalate, a polyamide, a polycarbonate, a polyolefin, or vinyl and vinylidene polymer or copolymer. The belt may be composed of several plies of the material and have several sheets side by side to obtain the desired width and/or length of the belt. The sheets are joined (see Division B5) to form the endless belt by ultrasonic welding, adhesive or tape. The perforations may comprise circular or square holes arranged in rows parallel and transverse to the machine direction. The belt is heat-conditioned after being perforated. Between the holes there may be protuberances or grooves to form water channels. To increase the surface friction of the belt there may be a coating of colloidal or ground silica or alternatively either or both surfaces may have stuck thereto a layer of a polyether or polyesterurethane resin foam, or a layer of a woven fabric, or a p fibrous bat which may be pre-formed as by needling, felting, or chemical bonding, the fabric or bat being composed of natural or synthetic fibres-e.g. nylon-or blends thereof. The laminated sheet is perforated after formation. The felt may be conventional one of wool, or synthetic material, or a duplex felt (see Specification 1,002,095) or a belt similar to the above may be used. Water is removed from the belt and felt by means of air jets and suction boxes.ALSO:To increase the surface friction of an endless belt formed of substantially incompressible film of a synthetic polymer in a paper-making machine (see Division D2) there is on one or both surfaces a coating of colloidal silica, or a coating of an abrasive material-for example ground silica-held in place by heating the belt above its softening temperature or by curing it with various thermosetting resins. The belt has a plurality of perforations therein of a size sufficient to enable the retention of moisture therein by capillary action. The film is preferably a crystalline structure and may be made of polyethylene terephthalate, a polyamide, a polycarbonate, a polyolefin, or vinyl and vinylidene polymer or copolymer. The belt may be composed of several plies of the material and have several sheets side by side to obtain the desired width and/or length of the belt. The sheets are joined (see Division B5) to form the endless belt by ultrasonic welding, adhesive or tape. The perforations may comprise circular or square holes arranged in rows parallel and transverse to the machine direction. The belt is heat conditioned after being perforated. Between the holes there may be protuberances or grooves to form water channels. |
