Process for producing polymeric materials
AssigneeBritish Technology Group Limited
InventorsIan M. Ward, Peter J. Hine, Keith Norris
Life of this patent
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Abstract
Process for the production of a homogenous polymeric monolith wherein an assembly of oriented thermoplastic polymer fibres is maintained under a contact pressure sufficient to ensure intimate contact at an elevated temperature high enough to melt a proportion of the polymer. The assembly is subsequently compressed at a compaction pressure higher than the contact pressure while still being maintained at the elevated temperature. The resulting polymeric products are useful, for example as orthodontic brackets, bone prostheses and in body armor.
Claims33
A process for the production of a homogeneous polymeric monolith from thermoplastic polymer fibers, the monolith having improved mechanical properties in a direction transverse to said fibers, said process comprising the steps of:
- forming an assembly of oriented thermoplastic polymer fibers;
- applying a contact pressure to said assembly of oriented thermoplastic polymer fibers sufficient to ensure intimate contact of the polymer fibers with each other, heating said assembly of polymer fibers to an elevated temperature sufficient to selectively melt a proportion of the polymer fibers while in intimate contact with each other, the molten polymer on cooling recrystallizing to form a melt phase which has a melting point less than the melting point of the fibers and which binds said fibers together;
- and
- subsequently compressing said bound fibers at a compaction pressure higher than said contact pressure while still maintaining said assembly at an elevated temperature to produce said monolith.
A process for the production of homogeneous polymeric monolith from thermoplastic polymer fibers, the monolith having improved mechanical properties in a direction transverse to said fibers, said process comprising the steps of:
- forming an assembly of oriented thermoplastic polymer fibers;
- applying a contact pressure to said assembly of oriented thermoplastic polymer fibers to ensure intimate contact of the polymer fibers with each other, heating said assembly of polymer fibers to a temperature not greater than the temperature of which the endotherm measured by Differential Scanning Calorimetry of the polymer fibers reaches its highest point, to selectively melt a proportion of the polymer fibers while in intimate contact with each other, the molten polymer on cooling recrystallizing to form a melt phase having a melting point less than the melting point of the fibers and which binds said fibers together;
- and
- subsequently compressing said bound fibers at a compaction pressure higher than said contact pressure while still maintaining said assembly at an elevated temperature to produce said monolith.
A process for the production of homogeneous polymeric monolith from thermoplastic polymer fibers, the monolith having improved mechanical properties in a direction transverse to said fibers, said process comprising the steps of:
- forming an assembly of oriented thermoplastic polymer fibers;
- applying a contact pressure to said assembly of oriented thermoplastic polymer fibers sufficient to ensure intimate contact of the polymer fibers with each other, heating said assembly of polymer fibers to an temperature sufficient to selectively melt no more than 20% by weight of the polymer fibers while in intimate contact with each other, the molten polymer on cooling recrystallizing to form a melt phase which has a melting point less than the melting point of the fibers and which binds said fibers together;
- and
- subsequently compressing said bound fibers at a compaction pressure higher than said contact pressure while still maintaining said assembly at an elevated temperature to produce said monolith.
Dependencies are inferred from the claim text.