Coating processes – Medical or dental purpose product; parts; subcombinations;... – Implantable permanent prosthesis
Patent
1992-08-04
1994-10-18
Beck, Shrive
Coating processes
Medical or dental purpose product; parts; subcombinations;...
Implantable permanent prosthesis
4273935, 4273899, B05D 302
Patent
active
053566688
DESCRIPTION:
BRIEF SUMMARY
The subject of this invention is a process for modifying a surface on a polymer by forming a fluorinated surface on the polymer.
It frequently happens that an article made from a polymer which is particularly suitable for making that article displays undesirable characteristics or side effects when used in the environment to which the article is exposed. These characteristics may spring from so-called "active" atoms, which may principally be hydrogen or oxygen atoms, present in the molecules of a polymer. Vascular grafts are a case in point. Polymers in general, and polyesters in particular, are among the most suitable materials for use in making such a graft. Polymers such as polyester are, however, thrombogenic when exposed to blood as of course they are when used to form a vascular graft.
Blood platelets tend to adhere to the polymer and initiate blood clotting. Polymers such as polyester are also known to activate the blood complement system. This is undesirable as complement activation is one of the first stages of an inflammatory response to foreign material. There is therefore a need to modify the polymer surface to reduce its thrombogenicity and/or to reduce its platelet adhesion characteristics.
It has previously been proposed to eliminate or reduce the undesired surface activity of a polymer by fluorinating the polymer or at least its surface; this has been explained as replacing the active atoms in the polymer molecules, at the surface at least, by fluorine atoms.
One previously proposed method of fluorinating the surface of a polymer is disclosed in U.S. Pat. No. 4,264,750 and U.S. Pat. No. 4,404,256 and comprises exposing the polymer to a cold plasma containing ions and/or radicals of a fluorine-containing substance under conditions to cause substitution of hydrogen and/or other active atoms at the surface of the polymer with fluorine atoms. Other, similar, processes require the deposition of a thin layer of a fluoropolymer formed from the gaseous monomer through plasma discharge (Yasuda et al, Biomat., Med. Dev., Art. Org., 4(3&4), 307-372 (1976) and Fowler et al, The Third World Biomaterials Congress, 21st to 25th Apr. 1988, Kyoto, Japan, Abstracts 2C1-35, page 99).
The known plasma and glow discharge processes require very close control, not only to provide effective fluorination but also to minimise the degradation of the polymer which always takes place as a result of such a treatment. It is also difficult to ensure a consistent surface coverage over all the bare polymer and, in the case of plasma polymerisation, the chemical structure of the deposited polymer is prone to variability and hence to having a hererogenous structure.
It might be thought that the problem could be avoided simply by preparing articles such as vascular grafts from a fluoropolymer, such as polytetrafluoroethylene (PTFE). In practice, however, this is not the case. Fabric grafts, particularly knitted ones, are preferred to those made of continuous, or microporous, material, to allow better tissue ingrowth once the graft is in situ in the patient. PTFE fabric grafts are prone to fraying as a result of yarn slippage caused by the low coefficient of friction of PTFE; this is an important consideration as fraying can cause the disruption of a sutured attachment of a graft to the host blood vessel.
The problem therefore still remains, and the present invention seeks to address it. It has now been found that a fluorine-containing layer can be deposited on a polymer without the need for the complex physico-chemical conditions of a plasma discharge process: instead, a fluoropolymer can be deposited from solution onto the underlying polymer.
According to a first aspect of the present invention, there is therefore provided a process for forming a fluorinated surface on a polymer, the process comprising dissolving a fluorocarbon in a solvent for the fluorocarbon, bringing the resulting solution into contact with the polymer and removing the solvent from the polymer.
By means of the invention, the polymer may present a non-acti
REFERENCES:
patent: 3839743 (1974-10-01), Schwarcz
patent: 4153745 (1979-05-01), Hart
patent: 4167045 (1979-09-01), Sawyer
patent: 4391844 (1983-07-01), Baczek et al.
patent: 4413074 (1983-11-01), Wrasidlo et al.
patent: 4414280 (1983-11-01), Silva
patent: 4470859 (1984-09-01), Benezra et al.
patent: 4902290 (1990-02-01), Fleckenstein
patent: 4981727 (1991-01-01), Brinduse et al.
patent: 4985280 (1991-01-01), Scholz
patent: 5061738 (1991-10-01), Solomon et al.
patent: 5171611 (1992-12-01), Porter et al.
patent: 5242995 (1993-09-01), Kim et al.
patent: 5246451 (1993-09-01), Trescony et al.
Ashton Timothy R.
Maini Roshan
Paton Duncan M.
Beck Shrive
Dudash Diana
Irons Edward S.
Vascutek Limited
LandOfFree
Fluorinating polymer surfaces does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluorinating polymer surfaces, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluorinating polymer surfaces will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2370914