Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3922378 A
Publication typeGrant
Publication dateNov 25, 1975
Filing dateAug 19, 1974
Priority dateAug 4, 1972
Publication numberUS 3922378 A, US 3922378A, US-A-3922378, US3922378 A, US3922378A
InventorsWilliam M Kline
Original AssigneeMedical Evaluation Devices & I
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fluorinated hydrocarbon coating method
US 3922378 A
Abstract
This invention is directed to a method of forming an unbroken uniform transparent coating of a fluorinated hydrocarbon resin on a flexible coil spring, wire or similar substrate by immersing the substrate in a dispersion of the selected resin and removing the dispersion coated substrate therefrom, initially drying the disperson coated substrate, heating same to a predetermined temperature over a predetermined period of time, and then slowly cooling the thus heated coated substrate over a predetermined period of time to a temperature as low as or lower than a predetermined lower temperature.
Images(3)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 1 1 1111 3,922,378

Kline Nov. 25, 1975 54] FLUORINATED HYDROCARBON COATING 3,730,835 5/1973 Leeper et al 1. 128/349 R METHOD 3,749,086 7/1973 Kline et al 128 2 M 3,790,403 2/1974 Ribbans 117/113 x [75] Inventor: William M. Kline, Gloversville, NY.

['73] Assignee: Medical Evaluation Devices &

Instruments Corporation, Gloversville, N.Y.

[22] Filed: Aug. 19, 1974 Examiner-Harry Attorney, Agent, or FirmThomas E. Tate OTHER PUBLICATIONS Fitz Simmons et aI., Thin Films of. (Teflon) .for Metals, Naval Research Laboratory, June 15, 1956, pp. 24-29.

Related US. Application Data [63] Continuation-impart of Ser. No. 278,099, Aug. 4, [57] ABSTRACT I972, abandoned.

Tl'lIS invention is directed to a method of forming an [521 Cl 427/2; 128/349 R; 427/120; unbroken uniform transparent coating of a fluorinated 427/379; 427/388 hydrocarbon resin on a flexible coil spring, wire or 51 Int. Cl. I. 1344a 1/42; HOlb 3/44 Similar Substrate by immersmg the substrate in a [58] Field of Search... 117/94, 128.4, 132 CF, Perm of the Selected resin and removing the dispe" 7/113 119 2 232 119 128/348 351 sion coated substrate therefrom, initially drying the disperson coated substrate, heating same to a prede- [56] References Cited termined temperature over a predetermined period of UNITED STATES PATENTS time, and then slowly cooling the thus heated coated substrate over a predetermined period of time to a 6055 et al. temperature as 10w as or lower than a predetermined 3,522,089 7/1970 Takada et al. I 17/1 19.2 X

3,560,249 2/1971 Chereshkevich et a]. 117/132 CF 3,704,176 ll/1972 Oga et al. 117/132 CF 9 Claims, No Drawings lower temperature.

FLUORINATED HYDROCARBON COATING METHOD RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 278,099, filed Aug. 4, 1972, now abancloned.

THE INVENTION This invention relates generally to new and useful improvements in the application of fluorinated hydrocarbon coatings to metallic substrates and particularly seeks to provide a novel method of applying and firmly bonding such coatings to 'the exteriors of small diameter springs of the types included in the construction of spring guides used in surgical catheterization procedures, and to the exteriors of extremely fine flexible conducting wires of either circular or rectangular cross-section, such as those used in the indwelling sensing electrodes for cardiac monitoring instruments or in the connecting electrodes for cardiac pacemakers.

These spring guides, regardless of their internal construction, generally include a small diameter elongated body formed as a continuously wound helical spring with the helices thereof in contact with each other. The exterior of the spring body should be either sheathed within a tube of inert flexible plastic having a low coefficient of friction or coated by a similar type of plastic. In either case, it is desirable that the sheathing or coating be as thin as possible, consistent with the required end use so that the ultimate outside diameter of the completed spring guide, on a size-for-size basis, is kept at a practicable minimum.

Furthermore, since these spring guides are to be introduced into and advanced through the blood or other vessels of animate beings, their outer surfaces must be flexible and of a completely uniform character with no crazing, intermittent breaks or other types of discontinuities, nor should the outer surfaces be such as to become powdery or separable as discrete particles or flakes.

In the case of the above-mentioned conducting wires, the fluorinated hydrocarbon coatings serve as flexible external insulators having smooth unbroken surface characteristics and being of sufficient thinness as to enable a substantial number of such wires to be assembled into a bundle of very small total cross-section for insertion into and retention by a correspondingly small diameter flexible sheath formed from a tube of a similar type of fluorinated hydrocarbon.

It is believed that, at the present time, a hexafluoropropylene-tetrafluoroethylene copolymer resin of the type commercially designated as Teflon FE? and a tetrafluoroethylene resin of the type commercially designated as Teflon TFE (sometimes PTFE) are the best available for such purposes. Although it is known that these materials have been used in the past for coating many different types of substrates, mostly rigid metallic articles, observation of several different makes of spring guides coated or sheathed with such materials, and similarly coated fine wires, indicates that none of them have been fabricated in such a manner as to properly meet either the end use requirements or to avoid the problems mentioned above.

However, through the use of this invention it is possible to apply and firmly bond such types of coatings to the exteriors of surgical spring guides, fine wires or 2 comparable substrates in a completely uniform manner and as unbroken continuous films having thicknesses ranging from a low micron measurement up to about 1 mil.

Therefore, an object of this invention is to provide a novel method for applying a fluorinated hydrocarbon coating or sheath to the exterior of an elongated, small diameter object such as the body of a spring guide used for surgical catheterization procedures, or a conducting wire to be contained within an instrument electrode.

Another object of this invention is to provide a method of the character stated in which the object to be coated is first slowly immersed in a dispersion or emulsion of the selected fluorinated hydrocarbon, slowly removed therefrom, subjected to a preliminary drying at moderate temperatures for a short time, then subjected to a higher temperature curing for a somewhat longer time, and then cooled slowly.

Another object of this invention is to provide a method of the character stated in which the immersion of the object to be coated preferably is maintained for a matter of minutes; the initial drying preferably takes place at a temperature of about 180F for about one half hour; the higher temperature curing takes place within a temperature range of from about 545 700F, preferably for about lr hours; and the final cooling takes place preferably over a period of about 2 hours to reduce the temperature to at least as low as about 150F, after which the coated object may be removed to the ambient temperature of the atmosphere.

Another object of this invention is to provide a method of the character stated in which the resultant coating is a transparent film.

A further object of this invention is to provide a method of the character stated in which the temperatures and treating times are such as to prevent any substantial degradation of the physical and mechanical qualities of the substrate such as loss of resiliency or major discoloration.

With these and other objects, the nature of which will become apparent, the invention will be more fully understood from the following detailed description and the appended claims.

A typical spring guide that may be coated in accordance with this invention is disclosed in the U.S. Pat. No. 3,749,086, granted July 31, 1973, to William M. Kline and Charles C. Roach.

Both FEP and TFE (or PTFE) types of fluorinated hydrocarbons and probably others, are suitable for use in the method of this invention and are commercially available from DuPont in dispersions, for example, as Teflon for the FEP dispersion and Teflon 30B for the TFE dispersion.

The following example describes a preferred method of this invention:

EXAMPLE 1. A spring guide, fine wire or its equivalent, to be coated first has its exterior subjected to a degreasing (cleaning) operation.

2. The spring guide or fine wire is then slowly immersed in the selected fluorinated hydrocarbon dispersion, under non-agitated conditions, for a sufficient time to permit full coating at least of the exterior of the spring guide or fine wire with the dispersion, which time generally is within the range of from 2-30 minutes, preferably about 10 minutes. The dispersion (on a 3 lOO-part basis by weight) should contain about l-40 parts by weight, preferably about 20, of the selected fluorinated hydrocarbon resin.

3. The spring guide or fine wire is then slowly removed from the dispersion and at least partly dried in a nonturbulent atmosphere at about 180F for about 120 minutes, preferably about A hour, and removed from that drying atmosphere and cooled to an ambient temperature not greater than about 90F.

4. The thus at least partly dried spring guide or fine wire then is placed in an oven at the approximate 90F ambient temperature and the temperature of the oven then is raised slowly over a period of 10 180 minutes, preferably about l- /2 hours, to a range of 550 600F, preferably about 575F, for the FEP dispersion coating; or to a range of 650 700F, preferably about 675F, for the TFB dispersion coating. In either case, the temperature then is slowly reduced over a period of 30 180 minutes, preferably about 2 hours, to at least as low as l50F in order to produce a clear, unbroken film, after which the thus coated or sheathed spring guide is removed to the ambient temperature of the open atmosphere. In this manner, through the controlled applications of heat, followed by controlled coolings, the non-resin portions of the selected dispersion or emulsion are driven off and the remaining resin forms a hot melt that becomes annealed and firmly bonded to the coils of the spring substrate as an unbroken transparent flexible and virtually colorless film. The final slow cooling from the 550 700F heating range (exact temperatures are, of course, dependent upon the selected type of resin) down to at least as low as 150F is the most critical part of this process, since appreciably faster cooling to 150F or lower will not produce either the desired fully bonded unbroken flexible film or a film that remains fully bonded and unbroken when the substrate to which it is applied subsequently is subjected to a physical distortion such as flexing.

It also should be mentioned that at a temperature below about 545F for the FEP resin or below about 645F for the TFE resin, the applied coating will be non-uniform and will readily powder off. Furthermore, if the temperatures exceed the stated maximums, i.e. 600F for FEP or 700F for TFE, the coating will char and become discontinuous as by crazing or flaking. In neither event is the coating completely and firmly bonded to the substrate.

Here, the film, under the stated conditions, forms a melt after the emulsifier has been driven off by heat as the temperature progressively rises; and the resultant unbroken clear film becomes annealed and firmly bonded to the substrate during the above described slow cooling. Furthermore, the temperatures and times of heating are such that the strength and resiliency of the spring or wire substrate are substantially unaffected nor does the substrate become appreciably discolored.

The method described in the foregoing Example produces a coating film or sheath whose thickness is in the low micron range; but ifit is desired to increase the ultimate thickness of the applied film, the coating procedures may be repeated in their entirety, one or more times until the desired ultimate coating thickness, up to about 1 mil, has been achieved.

Although, in the appended claims, the phrase liquid dispersion has been used to define the physical state of the solids-containing liquid to be applied to the substrate, it will be understood that this phrase also is intended to include emulsions and other types of solidscontaining liquids.

It also should be understood that while the above description generally relates to a method of coating coil springs or single wires of circular or rectangular crosssection, the method is equally effective for coating small diameter wires of either twisted or braided multistrand construction.

I claim:

1. A method of applying and firmly bonding a fluorinated hydrocarbon resin coating to the exposed surface of a clean flexible metallic substrate selected from the group consisting of a coil spring in which the helices thereof are in mutual contact and a fine conducting wire of small area cross-section and comprising the steps of: supplying a liquid dispersion bath of a fluorinated hydrocarbon resin selected from the group consisting of hexafluoropropylene-tetrafluoroethylene copolymer and tetrafluoroethylene; slowly immersing said substrate in said dispersion bath under nonagitated conditions for about 2-30 minutes to effect a coating of said dispersion thereon and then slowly removing said substrate from said dispersion bath; then subjecting said removed dispersion coated substrate to a preliminary heating in a non-turbulent atmosphere at a temperature not exceeding about 180F for about 10-120 minutes; then cooling said prelimarily heated dispersion coated substrate to about the ambient temperature of the atmosphere; then subjecting said preliminarily heated and cooled dispersion coated substrate to a further heating to a temperature of about 545 700 F for about 10-180 minutes whereby to drive off any non-resin portions of said dispersion coating and to cause the resin thereof to form as a hot melt in contact with said substrate; and then slowly cooling the thus further heated resin coated substrate to a temperature at least as low as about 150F over a period of about 30-180 minutes, whereby to cause the resin coating thereof to become firmly bonded thereto as an unbroken flexible transparent film.

2. The method of claim 1 in which said liquid dispersion on a parts by weight basis contains about 10-40 parts by weight of said resin.

3. The method of claim 2 in which said liquid dispersion contains about 20 parts by weight of said resin.

4. The method of claim 1 in which said further heating of said hexafluoropropylene-tetrafluoroethylene copolymer dispersion coated substrate is performed over a period of about ninety minutes at atemperature of about 545-600F.

5. The method of claim 4 in which said further heating temperature is about 575F.

6. The method of claim 1 in which said further heating of said tetrafluoroethylene dispersion coated substrate is performed over a period of about ninety minutes at a temperature of about 645-700F.

7. The method of claim 6 in which said further heating temperature is about 675F.

8. The method of claim 1 in which said substrate is a coil spring in which the helices thereof are in mutual contact.

9. The method of claim 1 in which said substrate is a fine conducting wire of small area cross-section.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2838829 *Sep 5, 1956Jun 17, 1958Toefco Engineering CompanyMethod of making bearings
US3522089 *May 1, 1967Jul 28, 1970Fujikisa Cable Works Ltd TheMethod of preparing insulated electric wires coated with foamed synthetic resin
US3560249 *Sep 23, 1968Feb 2, 1971Chegodaev Dmitry DmitrievichMethod for production of polytetra-fluoroethylene multilayer coatings on heat-resistant materials
US3704176 *Feb 24, 1970Nov 28, 1972Sumitomo Electric IndustriesMethod of resin coating a metal and resin-coated metal product thereof
US3730835 *Apr 15, 1971May 1, 1973Alza CorpNovel device coated with a prosta-glandin and preparation thereof
US3749086 *Jul 24, 1972Jul 31, 1973Medical Evaluation Devices & ISpring guide with flexible distal tip
US3790403 *Jan 13, 1972Feb 5, 1974Du PontGlass fabric coated with crack-free fluorocarbon resin coating and process for preparing
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4318947 *Jan 26, 1981Mar 9, 1982The Kendall CompanyPolymer coating and curing process for catheters
US4534363 *Apr 26, 1984Aug 13, 1985Cordis CorporationCoating for angiographic guidewire
US4536179 *Sep 24, 1982Aug 20, 1985University Of MinnesotaImplantable catheters with non-adherent contacting polymer surfaces
US4548206 *Jul 21, 1983Oct 22, 1985Cook, IncorporatedCatheter wire guide with movable mandril
US4649916 *Jul 11, 1984Mar 17, 1987Med-Inventio AgStiffening probe and tensioning device therefor
US4895168 *Jan 21, 1988Jan 23, 1990Schneider (Usa) Inc., A Pfizer CompanyGuidewire with movable core and external tubular safety cover
US4917670 *Mar 22, 1988Apr 17, 1990Hurley Ronald JContinuous spinal anesthesia administering apparatus and method
US5107852 *Apr 2, 1990Apr 28, 1992W. L. Gore & Associates, Inc.Catheter guidewire device having a covering of fluoropolymer tape
US5209734 *Mar 21, 1989May 11, 1993Brigham And Women's Hospital, Inc.Continuous spinal anesthesia administering apparatus
US5211636 *Oct 31, 1990May 18, 1993Lake Region Manufacturing Co., Inc.Steerable infusion guide wire
US5386828 *Aug 17, 1993Feb 7, 1995Sims Deltec, Inc.Guide wire apparatus with location sensing member
US5419340 *Oct 27, 1993May 30, 1995Stevens; Robert C.Guidable catheter assembly using coated deflector wire and method of using same
US5498251 *Nov 29, 1994Mar 12, 1996Dalton; Michael J.Tissue perfusion catheter
US5607407 *Aug 14, 1995Mar 4, 1997Tolkoff; Marc J.Catheter assembly
US5645065 *Apr 11, 1995Jul 8, 1997Navion Biomedical CorporationCatheter depth, position and orientation location system
US5853394 *Dec 31, 1996Dec 29, 1998Tolkoff; Marc JoshuaCatheter
US6350266Apr 26, 2000Feb 26, 2002Scimed Life Systems, Inc.Hybrid stone retrieval device
US6368328Sep 16, 1999Apr 9, 2002Scimed Life Systems, Inc.Laser-resistant medical retrieval device
US6752811Nov 20, 2001Jun 22, 2004Scimed Life Systems, Inc.Laser-resistant medical retrieval device
US6872211Jan 24, 2002Mar 29, 2005Scimed Life Systems, Inc.Hybrid stone retrieval device
US7476246Dec 7, 2004Jan 13, 2009C. R. Bard, Inc.Implantable medical devices with fluorinated polymer coatings, and methods of coating thereof
US7892280Nov 7, 2008Feb 22, 2011C. R. Bard, Inc.Implantable medical devices with fluorinated polymer coatings, and methods of coating thereof
US8007502May 19, 2004Aug 30, 2011Scimed Life Systems, Inc.Laser-resistant medical retrieval device
US8828022Jan 7, 2005Sep 9, 2014Boston Scientific Scimed, Inc.Hybrid stone retrieval device
US20050033313 *May 19, 2004Feb 10, 2005Scimed Life Systems, Inc.Laser-resistant medical retrieval device
DE4124606A1 *Jul 25, 1991Jan 28, 1993Ruesch Willy AgMandrel for medical instrument e.g. catheter - has external protective rubber coating contg. antithrombotic, microbicidal and fungicidal agents
WO1989009079A1 *Mar 21, 1989Oct 5, 1989Brigham & Womens HospitalContinuous spinal anesthesia administering apparatus and method
Classifications
U.S. Classification427/2.24, 427/120, 427/2.28, 427/379, 427/388.4, 600/585
International ClassificationH01B19/04, H01B13/06, A61M25/09, B05D3/02, B05D7/20, B05D5/12
Cooperative ClassificationB05D7/16, H01B19/04, H01B13/065, B05D3/0209, B05D3/0254, B05D1/18, B05D5/083
European ClassificationB05D5/08C, B05D3/02H, B05D7/16, H01B19/04, H01B13/06C
Legal Events
DateCodeEventDescription
Aug 11, 1980AS99Other assignments
Free format text: MEDICAL EVALUATION DEVICES & INSTRUMENTS, 6 DIVISION ST., GLOVERSVILLE, NY 120 * INTERNAL REVENUE SERVICE : 19800729 OTHER CASES: NONE; RELEASE OF LEVY BY IRS