Method for manufacturing balloon catheter

Disclosed is a method for manufacturing a balloon catheter. The method comprises the steps of: preparing a tube which is formed with a first lumen and a second lumen, the tube possessing a balloon expansion section in which a first hole for communicating an inside of the first lumen with an outside of the balloon catheter is defined; filling polymeric filler material into a part of the first lumen which extends from one end of the first lumen to a point where the first hole is defined, and attaching a tip member to one end of the tube; fitting a cap member around the tube except the balloon expansion section, and dipping the tube into releasing agent solution and solidifying the releasing agent solution, such that an outer surface of the balloon expansion section is coated with releasing agent and the first hole and another part of the first lumen which extends from the point where the first hole is defined to the other end of the balloon expansion section, are filled with releasing agent; removing the cap member from the resultant tube and dipping the tube into liquid silicone to form an over-coating layer onto an entire outer surface of the tube; and removing the releasing agent which is coated onto the outer surface of the balloon expansion section and filled into the first hole and the another part of the first lumen.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a method for manufacturing a balloon
 catheter, and more particularly, the present invention relates to a method
 for manufacturing a balloon catheter which is, as a medical appliance,
 fitted into a tube-shaped organ of the body and a portion of which is
 maintained in an expanded state to allow liquid medicine to be injected
 therein and liquid excrement to be removed therefrom.
 2. Description of the Related Art
 Generally, a balloon catheter is made of silicone to be medically superior.
 A method for manufacturing a balloon catheter will be described
 hereinafter with reference to U.S. Pat. No. 5,137,671.
 Referring to the drawings, a tube 10 as shown in FIG. 1 is provided. The
 tube 10 is formed with a first lumen 14 (a capillary tube of a smaller
 diameter) and a second lumen 12 (a tube of a larger diameter).
 In a state that the tube 10 as described above is prepared, a middle
 portion of the tube 10, that is, a balloon expansion section of the tube
 10 is, as shown in FIG. 2, formed with a first hole 16 which communicates
 an inside of the first lumen 14 with an outside of the tube 10. Then,
 polymeric filler material 18 such as silicone rubber is filled into a part
 of the first lumen 14 which extends from a lower end of the first lumen 14
 to a point where the first hole 16 is defined, and a tip member 20 is
 attached to a lower end of the tube 10 from which the polymeric filler
 material 18 is filled into the first lumen 14, whereby lower ends of the
 first and second lumens 14 and 12 are closed.
 Thereafter, a part of the tube 10 which extends from the lower end thereof
 and to an upper end of the balloon expansion section as shown by the line
 A--A in FIG. 3, is dipped into releasing agent solution (such as soapy
 water, Vaseline solution or the like), and the releasing agent solution is
 solidified to leave releasing agent 30 onto the part of the tube 10. At
 this time, releasing agent 30 is filled into the first hole 16 and another
 part of the first lumen 14 which extends from the point where the first
 hole 16 is defined to the upper end of the balloon expansion section as
 shown by the line A--A in FIG. 3. Consequently, the tube 10 has a
 cross-section as shown in FIG. 3. That is to say, the releasing agent 30
 is filled into the first lumen 14 from the upper end of the balloon
 expansion section as shown by the line A--A in FIG. 3 to the first hole
 16, and is coated onto an outer surface of the tube 10 between the upper
 end of the balloon expansion section as shown by the line A--A in FIG. 3
 and the end of the tip member 20 as shown in FIG. 3.
 Then, as shown in FIG. 4, another part of the tube 10 which extends from
 the lower end thereof to the lower end of the balloon expansion section as
 shown by the line B--B in FIG. 4 is dipped again into water or hot liquid,
 to remove the releasing agent coated onto the outer surface of the tube 10
 except the balloon expansion section, and a first over-coating layer 41
 and a second over-coating layer 42 are sequentially coated onto an entire
 outer surface of the tube 10, to define an over-coating layer 40.
 Then, the releasing agent which is filled into the first lumen 14 and the
 first hole 16 and coated onto the outer surface of the balloon expansion
 section, is removed through the first lumen 14, thereby defining a space
 part 44 as shown in FIG. 6 for allowing the balloon expansion section to
 be expanded.
 However, when a balloon catheter is manufactured by the processes of the
 conventional art, as described above, an amount of waste water which is
 generated when removing the releasing agent coated onto the outer surface
 of the tube 10 except the balloon expansion section after dipping the tube
 10 into releasing agent solution, is increased in the course of dipping
 the tube 10 into water, etc. through a number of times, thereby causing
 environmental pollution.
 Further, in the case that the releasing agent is not perfectly removed,
 when the balloon expansion section is expanded after the space part is
 formed, a portion of the over-coating layer adjoining the balloon
 expansion section is peeled off, thereby to be expanded together with the
 balloon expansion section.
 SUMMARY OF THE INVENTION
 Accordingly, the present invention has been made in an effort to solve the
 problems occurring in the related art, and an object of the present
 invention is to provide a method for manufacturing a balloon catheter
 which can actively cope with a problem of environmental pollution caused
 in the process of coating and removing releasing agent and eliminate a
 phenomenon that a portion of an over-coating layer adjoining a balloon
 expansion section is peeled off, thereby preventing the portion of the
 over-coating layer from being expanded together with the balloon expansion
 section.
 In order to achieve the above object, according to one aspect of the
 present invention, there is provided a method for manufacturing a balloon
 catheter, the method comprising the steps of: a first step of preparing a
 tube which is formed with a plurality of lumens including at least a first
 lumen and a second lumen, the tube possessing a balloon expansion section
 in which a first hole for communicating an inside of the first lumen with
 an outside of the balloon catheter is defined; a second step of filling
 polymeric filler material into a part of the first lumen which extends
 from one end of the first lumen to a point where the first hole is
 defined, and attaching a tip member to one end of the tube from which the
 polymeric filler material is filled; a third step of fitting a cap member
 around the one end of the tube to which the tip member is attached except
 at least the balloon expansion section in which the first hole is defined,
 and dipping the tube into releasing agent solution and solidifying the
 releasing agent solution, such that an outer surface of the balloon
 expansion section of the tube is coated with releasing agent and such that
 the first hole and another part of the first lumen which extends from the
 point where the first hole is defined to the other end of the balloon
 expansion section, are filled with releasing agent; a fourth step of
 dipping the resultant tube obtained from the third step into liquid
 silicone to form an over-coating layer onto an entire outer surface of the
 tube; and a fifth step of removing through the first lumen the releasing
 agent which is coated onto the outer surface of the balloon expansion
 section and filled into the first hole and the another part of the first
 lumen.
 By the features of the present invention, due to the fact that a cap member
 is used upon coating releasing agent, since the releasing agent is not
 coated onto a portion of a tube except a balloon expansion section, a
 problem of environmental pollution caused when removing an unnecessary
 portion of the releasing agent in the conventional art is solved, and it
 is possible to prevent a portion of an over-coating layer adjoining the
 balloon expansion section from being expanded along with the balloon
 expansion section when water is poured into the balloon expansion section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
 Reference will now be made in greater detail to a preferred embodiment of
 the invention, an example of which is illustrated in the accompanying
 drawings. Wherever possible, the same reference numerals will be used
 throughout the drawings and the description to refer to the same or like
 parts.
 First, as shown in FIGS. 1 and 2, a tube 10 which is formed with a first
 lumen 14 and a second lumen 12, is provided, and a middle portion of the
 tube 10, that is, a balloon expansion section of the tube 10 is formed
 with a first hole 16 which communicates an inside of the first lumen 14
 with an outside of the tube 10. Then, polymeric filler material 18 such as
 silicone rubber is filled into a part of the first lumen 14 which extends
 from a lower end of the first lumen 14 to a point where the first hole 16
 is defined, and a tip member 20 is attached to a lower end of the tube 10
 from which the polymeric filler material 18 is filled into the first lumen
 14, whereby lower ends of the first and second lumens 14 and 12 are
 closed.
 Thereafter, as being characterizing features of the present invention,
 processes for coating and removing releasing agent are performed. To be
 more detailed, as shown in FIG. 8, a cap member 50 is fitted around a part
 of the tube 10 which extends from the end of the tip member 20 attached to
 the lower end of the tube 10 to a lower end of the balloon expansion
 section as shown by the line B--B in FIG. 8, and thereafter, the tube 10
 is dipped into releasing agent solution to an upper end of the balloon
 expansion section as shown by the line A--A in FIG. 8. Then, after the
 releasing agent solution is solidified, the cap member 50 is removed.
 After performing the above processes, the tube 10 has the cross-section as
 shown in FIG. 4.
 In the above dipping process into the releasing agent, although the cap
 member 50 is fitted around the tube 10 only over a lower portion thereof,
 it is to be readily understood that another cap member can be fitted
 around an upper portion of the tube 10 downward to the upper end of the
 balloon expansion section as shown by the line A--A in FIG. 8.
 In this case, while it is possible to dip the entire tube 10 into the soapy
 water, it is not preferred in view of environmental pollution.
 Here, the cap member 50 is made of metal or synthetic resin. In an example
 in which the tube 10 is dipped into the releasing agent solution, the tube
 10 is dipped into soapy water having a low concentration, at a temperature
 of 40-50.degree. C. At this time, Vaseline solution can be used as the
 releasing agent solution.
 Then, the tube 10 is taken out from the releasing agent solution, and is
 dried using air of a temperature of 50.degree. C., to solidify the
 releasing agent solution.
 In the above process, since the releasing agent is only coated onto an
 outer surface of the balloon expansion section of the tube 10 and is only
 filled into the first hole 16 and the first lumen 14, a process for
 removing an unnecessary portion of releasing agent in the conventional art
 is not needed. Also, due to the fact that only a small amount of releasing
 agent is removed when defining a space part for allowing the balloon
 expansion section to be expanded, the balloon catheter is more
 advantageous than the conventional art from the viewpoint of environmental
 pollution.
 Moreover, because the releasing agent is brought into contact only with the
 balloon expansion section, an over-coating layer 40 which defines the
 space part for allowing the balloon expansion section to be expanded can
 come into close contact with the outer surface of the tube 10, whereby a
 phenomenon that a portion of the over-coating layer adjoining the balloon
 expansion section is peeled off when water is poured into the space part
 thereby to be expanded together with the balloon expansion section, is
 prevented from occurring.
 Next processes are implemented in the same way as in the conventional art.
 In other words, as shown in FIG. 5, a first over-coating layer 41 and a
 second over-coating layer 42 are sequentially coated onto the entire outer
 surface of the tube 10, to define the over-coating layer 40. Then, the
 releasing agent which is filled into the first lumen 14 and the first hole
 16 and coated onto the outer surface of the balloon expansion section, is
 removed through the first lumen 14, thereby defining the space part 44 as
 shown in FIG. 6 to allow the balloon expansion section to be expanded.
 Also, by perforating a second hole which is communicated with an inside of
 the second lumen 12, through the over-coating layer 40 at the lower end of
 the tube 10 adjacent the tip 20, the balloon catheter according to the
 present invention is completed.
 As described above, by manufacturing a balloon catheter by the method
 according to the present invention, advantages are provided in that since
 a portion of a tube except a balloon expansion section is not brought into
 contact with releasing agent when the releasing agent is coated on the
 balloon expansion section, a process for removing an unnecessary portion
 of the releasing agent can be eliminated in the conventional art, whereby
 the number of manufacturing processes is decreased and environmental
 pollution is prevented. Further, it is possible to prevent a portion of an
 over-coating layer adjoining the balloon expansion section from being
 peeled off therefrom when water is poured into a space part defined in the
 balloon expansion section due to the fact that the releasing agent remains
 on the portion of the tube except the balloon expansion section. Moreover,
 if a cap member is precisely fitted around the tube when dipping the tube
 into releasing agent solution, next processes can be manually performed in
 an easy manner.
 In the drawings and specification, there have been disclosed typical
 preferred embodiments of the invention and, although specific terms are
 employed, they are used in a generic and descriptive sense only and not
 for purposes of limitation, the scope of the invention being set forth in
 the following claims.