Coating processes – Medical or dental purpose product; parts; subcombinations;... – Implantable permanent prosthesis
Patent
1992-12-11
1994-07-19
Lusignan, Michael
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Implantable permanent prosthesis
8506, 427316, 623 1, A01N 102
Patent
active
053307828
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for preparing a colored porous polytetrafluoroethylene material. The present invention can be applied in various fields, for example, an artificial blood vessel having a reference line formed by the coloring.
RELATED ART
A porous material made of polytetrafluoroethylene (abbreviated as "PTFE") has excellent properties possessed by PTFE, such as thermal resistance, chemical resistance, electrically insulating properties, non-tackiness, flame retardant properties, lubricating ability and the like and it is utilized in various fields. In particular, a porous PTFE material prepared by an expanding method has a fine fibrous structure consisting of very fine fibers and nodes connecting to one another through the fibers, and a pore size and a porosity thereof can be freely changed. Accordingly the porous PTFE material is utilized in an extensive range of applications, for example, a filter material such as a membrane filter, a permeable membrane, an electrically insulative material, a material for an artificial organ such as an artificial blood vessel and an artificial lung, and an endoscope tube.
Depending on the application of the porous PTFE material, for example, the presence of a colored line representing a straight line or lattice is required so that the presence of the sag or torsion is evaluated or a size is indicated.
Hitherto, the following methods for the coloring were known: (1) a method comprising coating a paint such as an ink on a porous material prepared by the expansion and calcination, to physically adhere a colorant to a porous material surface, (2) a method comprising mixing a PTFE resin with a colorant during the preformation of the PTFE resin, and then expanding and calcining the mixture to support the colorant by the thermal fusion, and (3) a method comprising coating a colorant on a porous material prepared by the expansion and calcination, and then wrapping a PTFE tape around the porous material to support the colorant.
The physical adhesion method (1) is an easy method for the coloring. However, it gives a large amount of a deposits, and accordingly is unsuitable for a filter material, an artificial organ and a medical material. The paint is generally prepared by dissolving or dispersing a pigment in a solvent. Since the paint is coated on the porous PTFE material surface and the pigment is merely physically adhered or absorbed to the surface, the pigment is necessarily deposited when the paint contacts with a liquid. The thermal fusion method (2) has the defects that the procedure for preparing the porous material is complex, the distortion of the colored line cannot be prevented during the preparation, and the deposition of the colorant cannot be sufficiently suppressed only by the thermal fusion on the resin. In the method (3), since the PTFE tape is wrapped around the coated surface, the deposition can be prevented to some extent, but porosity inherently possessed by the porous PTFE material is easily damaged and the preparation procedure is complex.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a method for preparing a colored porous PTFE material in which the deposition of a colorant is suppressed without damaging the porosity.
Another object of the present invention is to provide a method for preparing a colored porous PTFE material in which a colored line can be easily provided on a porous PTFE material to evaluate the shape (e.g. linearity and distortion) thereof and indicate the size, and the colored line is not distorted during the preparation procedure.
Accordingly, the present invention provides a method for preparing a colored porous polytetrafluoroethylene material which comprises impregnating a colorant in a porous polytetrafluoroethylene material having a structure consisting of fibers and nodes connected to one another through the fibers, and then heating a portion impregnated with the colorant at a temperature of at least a melting point of the porous material.
Accordin
REFERENCES:
patent: 5064593 (1991-11-01), Tamara et al.
patent: 5104400 (1992-04-01), Berguer et al.
Lusignan Michael
Sumitomo Electric Industries Ltd.
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