Method for manufacturing of plastic wood-fiber pellets
US5938994A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Aug 29, 1997 |
| Grant date | Aug 17, 1999 |
| Priority date | — |
| Expiry date | Aug 29, 2017 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2311/14
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A wood-plastic composite material is produced in a twin screw extruder with parallel intermeshing segmented screws. The screw segments are positioned on two spline shafts and perform the various required functions of mixing, deaerating and removal of moisture followed by extrusion. A polymer is fed to the main throat of the extruder where the plastic is conveyed along a barrel formed by the case of the extruder. Cellulosic fiber is positively fed into the extruder approximately one-quarter of the way down the extruder barrel by a twin screw side stuffer. A vent is provided for entrained air in the cellulosic material to escape. The molten mixture of polymer and cellulosic material is then conveyed to a devolatilization area having a first atmosphere devolatilization area and a second vacuum devolatilization area separated by a melt seal. A pumping section raises the pressure of the mixture of polymer and cellulosic material to between 1,000 and 6,000 psi which is then extruded through a multiplicity of small holes and separated into individual pellets by a four bladed rotating knife. Calcium carbonate, talc, or other mineral is blown onto the pellets as they are formed to prevent t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.