| 摘要 |
1485202 Heat sealing of mixed polymers; seaming RESISTOFLEX CORP 29 April 1975 [1 July 1974] 17881/75 Headings B5A and B5K [Also in Division F2] A structure is made in fusing a body of perfluoroalkoxy fluorocarbon resin (PFA) to a body of polytetrafluorethylene (PTFE) by confining a quantity of PFA in a zone contiguous to the body of PTFE, heating the quantity of PFA and at least the PTFE which is in contact therewith to a temperature above the gel point of the PTFE and above the M.P. of the PFA, maintaining said temperature while compacting the PFA against the PTFE under pressure just sufficient to bring about intimate contact between the two resins in the area to be fused, slowly increasing the pressure to a predetermined level sufficient to prevent sinks and voids forming in the PFA but below the level where movement of PFA is induced and cooling slowly under pressure until the PFA has solidified. A dip pipe, Fig. 9, is constructed in a cylindrical mould chamber 40 is slipped over an assembly of PTFE jacket 33 and PTFE liner 32 encasing metallic wall of dip pipe 31. The mould core 43 is inserted in the lined tube. Clamp ring 44 is secured to the chamber 40 to effect a liquid-tight seal and a charge of PFA pellets is poured into cavity 46. A cylindrical ram 47 is placed around the jacket 33 and between the jacket and the mould face. A thermocouple 49 determines the temperature of the resin. The whole assembly is placed between adjustable pressure plates and immersed up to the lip of the mould in a salt bath. The process of fusing previously described is then carried out. |
