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WO1995025630A1 - Procede de production d'une structure polymere façonnee tubulaire - Google Patents

Procede de production d'une structure polymere façonnee tubulaire Download PDF

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Publication number
WO1995025630A1
WO1995025630A1 PCT/GB1995/000598 GB9500598W WO9525630A1 WO 1995025630 A1 WO1995025630 A1 WO 1995025630A1 GB 9500598 W GB9500598 W GB 9500598W WO 9525630 A1 WO9525630 A1 WO 9525630A1
Authority
WO
WIPO (PCT)
Prior art keywords
mould
polymer solution
fluid
polymer
inlet
Prior art date
Application number
PCT/GB1995/000598
Other languages
English (en)
Inventor
Anthony John Grant Sagar
Samuel Gordon Graham
Original Assignee
British Textile Technology Group
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Textile Technology Group filed Critical British Textile Technology Group
Priority to AU19002/95A priority Critical patent/AU1900295A/en
Publication of WO1995025630A1 publication Critical patent/WO1995025630A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
    • B29C67/02—Moulding by agglomerating
    • B29C67/06—Coagulating
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
    • A61F2/06—Blood vessels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
    • A61F2/06—Blood vessels
    • A61F2002/065—Y-shaped blood vessels

Definitions

  • This invention relates to a method of making a shaped tubular polymer structure.
  • a shaped tubular polymer structure is required is in the production of an aorto-coronary bypass graft such as is described in EP-A1-0, 269 , 254.
  • a graft is described as being produced by electrostatic spinning of polymer fibres .
  • the graft comprises a plate portion and at least one tube portion extending from the plate portion, the opening in the tube portion communicating with a corresponding opening in the plate portion.
  • Electrostatic spinning is not a particularly simple way to produce such a structure.
  • the present invention provides a relatively simple and straightforward method that is capable of quickly producing polymer structures of complex shapes on both a repetitive and a custom basis and with good control over product uniformity and dimension.
  • the invention comprises a method for making a shaped tubular polymer structure comprising casting a polymer on to a shaped surface and into a connected tube and hydrodynamically controlling the cast thickness to be uniform.
  • the hydrodynamic control may be by flowing a fluid in contact with a solution of the polymer.
  • the fluid may be a coagulating fluid and may be a gas, which may, for example, comprise nitrogen or air, or may be a liquid or a combination of gas and liquid applied in succession.
  • the hydrodynamic control may be effected by controlling the rate at which the fluid flows in contact with the polymer.
  • This control may have regard to the viscosity of the polymer solution and since the viscosity may change e.g. during coagulation or solvent removal the control may be dependent also on changes in viscosity.
  • the invention comprises, in another aspect, a method for coating a mould with a polymer comprising providing the mould with inlet and outlet means for a solution of the polymer, filling the mould with the polymer, introducing a fluid at the inlet means and removing polymer solution at the outlet means, and controlling the introduction of fluid and/or the removal of polymer solution to effect hydrodynamic control of the coating.
  • the mould may be arranged with inlet means and outlet means disposed vertically.
  • the fluid may flow upwardly through the mould, displacing polymer solution
  • the fluid will normally be of substantially lower viscosity than the polymer solution, viz a gas such as air or nitrogen or a coagulating liquid such as water.
  • the polymer solution is removed from the upper outlet means by suction while the inlet means is open to atmosphere to allow air to enter to displace the polymer solution.
  • the inlet means are connected to a supply of water or other coagulant for the polymer solution.
  • the admitted air passes as a "bubble" through the solution in the mould causing the solution to form into a layer against the wall of the mould.
  • the following water or other coagulant then removes solvent from the solution to leave the coagulated polymer lining the wall of the mould.
  • the mould will in general have a changing cross- sectional area, or at least a changing cross-section, proceeding from inlet means to outlet means.
  • a mould may comprise an inlet tube, a centre section of enlarged cross-section and an outlet tube.
  • a mould for making a bifurcated tube will comprise a bifurcated tubular mould which may be in the form of a Y or T shaped tube.
  • the cross-sectional area of the outlet tubes can be arranged to be equal to - A -
  • the inlet tube may be different, of course, and the two outlet tubes may themselves have different cross-sections and different cross-sectional areas.
  • the mould may, especially for the production of an aorto-coronary bypass graft, comprise a chamber having a plurality of tubular outlets .
  • the polymer solution may be removed from each of them by controlled suction; or the solution may be forced out against controllable restrictor means, by pressure from the inlet means .
  • Control may be exercised manually, by adjusting suction, inlet pressure, or outlet restrictor means according to circumstances so as to prevent the polymer solution/fluid (air or liquid) interface from collapsing.
  • a repeating cycle of applied pressure, suction or restriction may be controlled by a process timer which might comprise a teachable robot.
  • an appropriate variable or variables could be sensed and used in a feedback arrangement to control the flow of fluid in such manner as maintains the integrity of the interface.
  • the mould may comprise blown glass or PTFE or other suitable material, and may be an integral piece from which the cast, if sufficiently flexible, may be pulled or which may be broken to remove the cast, or may comprise two or more parts which can be disassembled to remove the cast.
  • a structure produced by the method may comprise an aorto-coronary bypass graft of the form described in EP-A1-0, 269, 254 or any other shaped structure such for example as a tube, for example for a vascular prosthesis, with a flanged or flared end, or a bifurcated tube.
  • Figure 1 is a cross-section through a structure in the form of a tube with a flange in the form of a flare;
  • Figure 2 is a diagrammatic representation of a sequence of operations in the production of the structure of Figure 1;
  • FIG. 3 is a representation like Figure 2 showing the production of a bifurcated tube
  • Figure 4 is a cross-section through an aorto- coronary bypass graft
  • Figure 5 is a diagrammatic representation of a sequence of operations in the production of the structure of Figure 4.
  • Structure 11, Figures 1 and 2 comprises a tube 11a with a flange lib in the form of a flare.
  • a structure made of appropriate polymer material might be used as a vascular prosthesis, the flared end flange lib being intended to facilitate fitting the prosthesis to an end of a natural vascular body in surgery.
  • the structure 11 could have a flange at each end, of course.
  • Structure 31 is a bifurcated tube, shown in Figure 3.
  • Structure 41 is more complex, comprising an aorto-coronary bypass graft and having a flange 41b of generally elliptical form and sized to form a "patch" in the wall of the aorta with connected tubes 41a, to communicate with the coronary arteries.
  • aorto-coronary bypass graft and having a flange 41b of generally elliptical form and sized to form a "patch" in the wall of the aorta with connected tubes 41a, to communicate with the coronary arteries.
  • Hydro ⁇ dynamic control of cast thickness on the interior of a simple tubular mould is effected in GB-2,197 , 658B by passing a fluid which is filled with a coagulatable polymer solution.
  • the final coagulant may be air or an inert gas such as nitrogen to evaporate a volatile solvent, or a liquid which is miscible with the original solvent and which is a non-solvent for the polymer, or a mixture of solvent and non-solvent.
  • Structure 11 is produced from a tubular mould 12 with an increased diameter portion 13.
  • the mould 12 is partially filled with the polymer solution 14 and the fluid coagulant, whether it be air or another gas or a liquid, is introduced as by suction (or pressure from the other end) to create the central orifice.
  • the process forms a substantially uniformly thick coating on the inner wall of the mould 12. This can be encouraged if required by rotation either with the mould axis arranged vertically so as to avoid thickening towards the lower part of the portion 13 or with the mould axis arranged horizontally to hold the coagulant against the walls of the mould centrifugally so that there is no tendency to differential wall thickness from one side to the other.
  • the rotational speed required is not large - of the same order of magnitude as may be effected by rolling between the fingers .
  • the thickness of the coating on the inner wall of the mould 12 is directly related to both the viscosity of the polymer solution and to the suction/pressure applied to draw the polymer through the mould 12.
  • a computer control system may be programmed to produce shaped structures 11 of defined wall thicknesses by varying either the viscosity of the polymer solution, for example, by heating, or by local application of ultrasound, or by altering the speed at which the polymer solution is drawn through the mould by adjusting the suction and/or pressure.
  • a computer control system may control the coagulation process, together with additional washing, lining and other operations .
  • the structure 11 which is flexible, is easily pulled out of the mould, though care must be taken to ensure that the wider portion can in fact be sufficiently deformed as to allow it to pass through the narrower part of the mould unless the mould is to be broken (or is already formed in two parts) .
  • the structure 11 is produced, then, simply by cutting the resulting casting at the position indicated by "C" in Figure 2.
  • Structure 31, Figure 3 is produced by filling the bifurcated tube mould 32 which has an inlet tube 32a and two outlet tubes 32b and attaching suction tubes 33 to the outlet tubes 32b.
  • the polymer solution 34 filling the mould 32 is sufficiently viscous not to run out.
  • Suction is applied at the tubes 33 with the inlet tube 32a lowermost and open to atmosphere. Air is drawn into the inlet tube 32a and a column of air 35 climbs up the tube 32a displacing the central core of the polymer solution 34, to leave an annular lining 36 of polymer solution.
  • the air column divides at the junction of the tubes 32a,32b as does the following water column. Eventually the air is sucked completely out of the tubes and the water coagulates the polymer from the lining of polymer solution into the bifurcated tube 31.
  • the tube mould need not be completely filled to begin with.
  • the branches 32b are of like cross- section, but need not be. Especially when they are not, adjustable restrictors 39 on the suction tubes 33 can be used to control the rate at which the air, and the following water, travel in the branches 32b, it being clearly desirable to balance the rate of flow in these tubes. This is, of course, amenable to automatic control in which the relative level of the polymer solution/interface in the tubes is sensed, e.g. photo- electrically, and used to adjust the restrictors 39.
  • the structure 41 is made in similar fashion but using a more complex mould 42 which might be produced, as might the mould 12, by glass-blowing techniques.
  • the tubes 41a are formed in the tubular parts 42a of the mould, the flange 41b being formed as a layer on a flange surface 42b the thickness and uniformity of which may be controlled by rotating the mould 42.
  • the structure 41 is produced by simply cutting the resulting casting at position "C" in Figure 5.
  • the structures may comprise an outer skin layer by virtue of contact of the cast surface with the mould surface during the casting operation. If desired, for example, in order to render the structure uniformly porous, the skin layer 11,31,41 may be removed, for example, by hydrolysis.
  • the method facilitates the introduction of fillers which are not intended to be dissolved out for pore forming purposes but which are intended to be left in as a functional inclusion - and this may be beneficial even for the tubular prosthesis of GB-B-2,197,658.
  • fillers are haemostatic agents, wound healing agents such as chitinous or alginate materials, bound enzymes and other therapeutic agents.
  • a filter may be assembled from a plurality of tubes made from polymer which contains a filler, for example chitinous material which can bind metal ions and other substances . Such a filter may be particularly useful in dialysis; blood may be pumped into one end of each tube while the other end is sealed.
  • the blood would thus be forced throughout the body of the tube and through the outer walls, ensuring that the blood contacts the filler to enable impurity extraction. Purified blood would then be collected by an outer casing enclosing the plurality of tubes . Further, specific antibodies, for example an antibody to the AIDS virus, could be incorporated as a filler.
  • fluids for example plasma, serum, cell extracts may be passed through a microfiltration system described above contacting different fillers.
  • biotransformation reactions may be carried out on biological solutions using specific bound enzymes as fillers . Products of such reactions may be collected from the exuded solutions and further purified.
  • the size of the pores in tubular prostheses used for such microfiltration system may be controlled.
  • barium sulphate (BaSO. ), which is opaque to X-rays.
  • a structure produced by the method of this invention implanted into a human body could thus be readily located by X-ray and its condition within the body regularly checked.
  • the structures may be reinforced for added strength by inclusions of fibre.

Landscapes

  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Biomedical Technology (AREA)
  • Vascular Medicine (AREA)
  • Cardiology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Gastroenterology & Hepatology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Pulmonology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Moulding By Coating Moulds (AREA)

Abstract

Procédé de production d'une structure polymère façonnée tubulaire comprenant le coulage d'un polymère sur une surface façonnée et dans un tube raccordé, ainsi que l'ajustement hydrodynamique de l'uniformité de l'épaisseur de la coulée.
PCT/GB1995/000598 1994-03-18 1995-03-17 Procede de production d'une structure polymere façonnee tubulaire WO1995025630A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU19002/95A AU1900295A (en) 1994-03-18 1995-03-17 Method for making a shaped tubular polymer structure

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9405376A GB9405376D0 (en) 1994-03-18 1994-03-18 Method for making a shaped tubular polymers structure
GB9405376.6 1994-03-18

Publications (1)

Publication Number Publication Date
WO1995025630A1 true WO1995025630A1 (fr) 1995-09-28

Family

ID=10752116

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/000598 WO1995025630A1 (fr) 1994-03-18 1995-03-17 Procede de production d'une structure polymere façonnee tubulaire

Country Status (3)

Country Link
AU (1) AU1900295A (fr)
GB (1) GB9405376D0 (fr)
WO (1) WO1995025630A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2382996A1 (fr) * 1977-03-10 1978-10-06 Anvar Perfectionnements apportes aux procedes de fabrication de protheses d'organes, et protheses obtenues par ces procedes
GB2197658A (en) * 1986-11-07 1988-05-25 Shirley Inst Vascular prosthesis
FR2666502A1 (fr) * 1990-09-10 1992-03-13 Roux Daniel Greffon vasculaire synthetique.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2382996A1 (fr) * 1977-03-10 1978-10-06 Anvar Perfectionnements apportes aux procedes de fabrication de protheses d'organes, et protheses obtenues par ces procedes
GB2197658A (en) * 1986-11-07 1988-05-25 Shirley Inst Vascular prosthesis
FR2666502A1 (fr) * 1990-09-10 1992-03-13 Roux Daniel Greffon vasculaire synthetique.

Also Published As

Publication number Publication date
AU1900295A (en) 1995-10-09
GB9405376D0 (en) 1994-05-04

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