| 摘要 |
Methods and machines for forming a non-woven web. In one embodiment, the machine includes one or more forming boxes. Each box has an associated fiber inlet. The forming boxes are positioned above a conveyor table. Fibrous material travels from the inlet through each forming box. A vacuum source is located underneath the conveyor table and generates an air current that pulls the fibrous material onto the conveyor table to form a web or sheet of fibrous material. In one embodiment, the fibrous sheet is formed in three layers. Vapor or steam boxes are placed adjacent to each forming box. In one embodiment, a steam box is located within the entrance of an oven. The sheet is subjected to a vapor, mist, fog, spray, or steam (generically referred to as a "suspension") as it passes under each steam box. In one embodiment, the suspension is generated with water. Applying a water suspension to the fibrous materials provides hydrogen atoms to help create hydrogen bonding between at least some of the fibers. As compared to wet laid forming, hydrogen bonds are created with much less water and with an associated reduction of cost in water handling and utility expenses to dry or remove water. In addition, mixtures of natural and synthetic fibers and relatively longer fibers may be used as compared to wet-laid processes to improve strength. Bulk density may be controlled by forming patterned layers of material and laminating the patterned layersrOne benefit of applying vapor to the forming web is -that vapor helps-with laying down fibers and smoothing of the sheet. This is more particularly noticed with sheets where relatively longer synthetic fibers have been added to increase strength. |
