Patent ES-8601275-A1 (ES)
Title: Process for remelting polyamides.
IPC: B29C48/92
Filed: 1984-08-14
Abstract: EP--92898 A In a process for remelting polyamide polymer, a controlled amt. of water is added to the polymer when molten or immediately prior to remelting. The remelting may be carried out in a screw extruder, e.g. with add. of water to the extruder barrel prior to the point where the polymer begins to melt, or with addn. of water to the polymer before it is charged to the extruder. - Pref. prior to moulding the polymer in granular form is heated under conditions for removal of volatile prods. to increase its mol.wt. after which a controlled amt. of water is added either to the granules or to molten polymer. Pref. when the water is added to the polymer remelting of the polymer is carried out within 10 hours, esp. with 8 hours and partic. within 5 hours from the addn of the water before the water has diffused completely through each granule. - Polymers can be conditioned for processing in a shorter time than previously. Process ensures polymers do not contain too much moisture (which causes depolymerisation on moulding) or too little moisture (which causes polymerisation during remelting and thus affects the physical properties of the material), thus giving a prod. with constant properties. (0/0) EPAB- EP--92898 B In a process for remelting polyamide polymer, a controlled amt. of water is added to the polymer when molten or immediately prior to remelting. The remelting may be carried out in a screw extruder, e.g. with add. of water to the extruder barrel prior to the point where the polymer begins to melt, or with addn. of water to the polymer before it is charged to the extruder. - Pref. prior to moulding the polymer in granular form is heated under conditions for removal of volatile prods. to increase its mol.wt. after which a controlled amt. of water is added either to the granules or to molten polymer. Pref. when the water is added to the polymer remelting of the polymer is carried out within 10 hours, esp. with 8 hours and partic. within 5 hours from the addn of the water before the water has diffused completely through each granule. - Polymers can be conditioned for processing in a shorter time than previously. Process ensures polymers do not contain too much moisture (which causes depolymerisation on moulding) or too little moisture (which causes polymerisation during remelting and thus affects the physical properties of the material), thus giving a prod. with constant properties. USAB- US4591468 A A process for remelting polyamide polymer to produce a molten polymer of set melt viscosity without prolonged preconditioning, comprises adding a controlled amt. of liq. water to the solid polymer, during or immediately prior to remelting within a time less than that normally required to reach equilibrium conditions. The controlled amt. of water is such as to produce in the molten polymer the set melt viscosity. - Pref. the remelting takes place in a screw extruder. Pref. water is added prior to the point on the extruder barrel where the polymer begins to melt. Pref. any deviation in the viscosity of the extruded molten polymer from a set value, causes an adjustment in the amt. of water added. (3pp)