URINARY CATHETER HAVING AN INJECTION MOLDED TIP

Abstract

A method for producing a urinary catheter comprises the steps: providing a tubular catheter shaft having an axially extending lumen therein; thermoforming an end of the tubular catheter shaft into a closed end; inserting said closed end of the tubular catheter shaft into an injection mold cavity; and injecting thermoplastic polymer material into the mold cavity to form a tip on the thermoformed end of the tubular catheter shaft. Hereby, a very effective method is obtained, forming securely attached tips. Alternatively, an end of the tubular catheter shaft with a non-closed opening may be inserted into the injection mold cavity; and thermoplastic polymer material be injected into the mold cavity to form a tip on the end of the tubular catheter shaft, whereby the injecting is controlled so that a limited amount of thermoplastic polymer enters into the lumen.

Claims

1. A method for producing a urinary catheter, comprising the steps: providing a tubular catheter shaft having an axially extending lumen therein; thermoforming an end of the tubular catheter shaft into a closed end; inserting said closed end of the tubular catheter shaft into an injection mold cavity; and injecting thermoplastic polymer material into the mold cavity to form a tip on the thermoformed end of the tubular catheter shaft.

2. The method of claim 1, wherein the forming of the tip further comprises cooling the mold cavity to solidify the injected thermoplastic polymer material, and removing the tubular catheter shaft with the formed tip from the mold.

3. The method of claim 1, further comprising the step of coating at least a part of the tubular shaft and the tip with a hydrophilic coating.

4. The method of claim 1, further comprising the step of inserting an elongate insert into the axially extending lumen prior to inserting an end of the catheter shaft into the mold, wherein the insert has a smaller outer diameter than the inner diameter of the lumen, forming a gap between an outer circumferential surface of the elongate insert and an inner circumferential surface of the lumen, the insert thereby being loosely arranged within the lumen.

5. The method of claim 1, wherein the thermoplastic polymer is heated to a temperature exceeding the melting temperature of the tubular catheter shaft immediately prior to being injection molded in to the mold cavity.

6. A method for producing a urinary catheter, comprising the steps: providing a tubular catheter shaft having an axially extending lumen therein; inserting an end of the tubular catheter shaft with a non-closed opening into said lumen into an injection mold cavity; and injecting thermoplastic polymer material into the mold cavity to form a tip on the end of the tubular catheter shaft, whereby the injecting is controlled so that a limited amount of thermoplastic polymer enters into the lumen.

7. The method of claim 6, further comprising providing an overpressure within the axially extending lumen during the injecting of the thermoplastic polymer material into the mold cavity.

8. The method of claim 6, wherein the forming of the tip further comprises cooling the mold cavity to solidify the injected thermoplastic polymer material, and removing the tubular catheter shaft with the formed tip from the mold.

9. The method of claim 6, further comprising the step of coating at least a part of the tubular shaft and the tip with a hydrophilic coating.

10. The method of claim 6, further comprising the step of inserting an elongate insert into the axially extending lumen prior to inserting an end of the catheter shaft into the mold, wherein the insert has a smaller outer diameter than the inner diameter of the lumen, forming a gap between an outer circumferential surface of the elongate insert and an inner circumferential surface of the lumen, the insert thereby being loosely arranged within the lumen.

11. The method of claim 6, wherein the thermoplastic polymer is heated to a temperature exceeding the melting temperature of the tubular catheter shaft immediately prior to being injection molded in to the mold cavity.

12. A urinary catheter comprising a tubular shaft extending between an insertable end and a discharge end, the discharge end being thermoformed to form a closed end, and a tip fixedly connected to said closed end of the tubular shaft.

13. The urinary catheter of claim 12, wherein the hardness of the tip is equal to or lower than 60 micro Shore A.

14. The urinary catheter of claim 12, wherein the hardness of the tip is equal to or lower than 50 micro Shore A.

15. The urinary catheter of claim 12, wherein the tip has a lower micro Shore A hardness than the tubular shaft.

16. The urinary catheter of claim 15, wherein the micro Shore A hardness is at least 10% lower.

17. The urinary catheter of claim 15, wherein the micro Shore A hardness is at least 50% lower.

18. The urinary catheter of claim 12, wherein the thermoformed end forms a tapered contacting surfaces for the tip.

19. The urinary catheter of claim 12, wherein the tip and the tubular shaft are formed of different materials.

20. The urinary catheter of claim 19, wherein a difference between a melting temperature of the material of the tip and a melting temperature of the material of the tubular shaft is less than 20 degrees C.

21. The urinary catheter of claim 20, wherein the difference is less than 10 degrees C.

22. The urinary catheter of claim 1, wherein the melting temperature of the material of the tubular shaft is higher than the melting temperature of the material of the tip.

23. The urinary catheter of claim 20, wherein the melting temperature of the material of the tubular shaft is higher than the melting temperature of the material of the tip.

24. The urinary catheter of claim 1, wherein the catheter is at least partly coated with a hydrophilic surface coating, the coating covering at least a part of the tubular shaft and the tip, said hydrophilic surface coating exhibiting a low friction when wetted.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] By way of example embodiments will now be described with reference to the accompanying drawings in which:

[0072] FIG. 1 illustrates an embodiment of a catheter according to the invention.

[0073] FIG. 2 is a more detailed cross-sectional view of the catheter tip in the catheter of FIG. 1.

[0074] FIG. 3 is a cross-sectional view of a curved tip configuration, in accordance with another embodiment of the present invention.

[0075] FIG. 4 is a cross-sectional view of an overmolded tip of a catheter in accordance with an embodiment of the present invention.

[0076] FIG. 5 is a cross-sectional view of a catheter with a molded tip in accordance with another embodiment of the present invention.

[0077] FIG. 6 is a cross-sectional view of an injection molding apparatus for forming an injection molded tip in accordance with an embodiment of the present invention.

[0078] FIG. 7 is a cross-sectional view of an injection molding apparatus for forming an injection molded tip in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION

[0079] In the following detailed description preferred embodiments of the invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. It may also be noted that, for the sake of clarity, the dimensions of certain components illustrated in the drawings may differ from the corresponding dimensions in real-life implementations. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention.

[0080] The following discussion is in particular concerned with hydrophilic urinary catheters for intermittent use. However, the invention can also be used in relation to other types of urinary catheters.

[0081] In the following, embodiments of a catheter according to the invention, and producible by methods in accordance with embodiments of the invention, will first be discussed, and thereafter embodiments of methods in accordance with the invention.

[0082] A catheter 1 as illustrated in FIG. 1, comprises a flared rearward portion 2 and an elongate shaft or tube 3 projecting forwardly from the rearward portion 2. An open-ended internal lumen extends from the rear end of the rearward portion 2 to one or more drainage apertures 4 in a forward end of the catheter. At the forward end of the elongate shaft 3, a tip 5 is arranged, having a rounded tip end. The tip may have a tapering form, as in the illustrative example, but other shapes are also feasible, as will be discussed in more detail in the following. The rearward portion 2 may function as a connector of the catheter 1, being connectable to other devices, such as a urine collection bag, a drainage tube or the like.

[0083] The connector, i.e. the flared rearward portion 2 is optional, and catheters without any flared rearward portion may also be used. In case a flared connector is used, this may be formed integrally and monolithically at the rearward end of the tubular shaft. However, it may also be formed as a separate component, being connected to the tubular shaft by means of welding, adhesion or the like. It may also be injection molded directly in place. In this case, the injection molding of the tip at the forward end of the tubular shaft and the connector at the rearward end of the tubular shaft can be performed simultaneously.

[0084] The drainage openings are arranged in the forward end of the tubular shaft, so that the lumen does not need to continue into the tip, which may as a consequence be solid.

[0085] At least a part of the elongate tube 3 forms an insertable length to be inserted through a body opening of the user, such as the urethra in case of a urinary catheter. By insertable length is normally meant that length of the elongate tube 2 which is insertable into the urethra of the patient during ordinary use. In case a hydrophilic catheter is used, the insertable length is coated with a hydrophilic material, for example PVP, or is made of hydrophilic material. Typically, the insertable length is 80-140 mm for a female patient and 200-350 mm for a male patient.

[0086] The tip may be straight, extending in the same direction as the tubular shaft and forming a rounded forward end, thereby forming a Nelaton type catheter. Such an embodiment is illustrated in FIGS. 1 and 2. The tip has an outer diameter dT which at all places is equal to or lower than the outer diameter d of the tubular shaft. The tip is preferably arranged conically tapering in the forward direction, to end in a rounded tip. However, alternative configurations are also feasible. For example, the tip may over part of its extension have a cylindrical configuration with the same diameter, may be arranged in a stepwise reduced diameter, may have parts being slightly enlarged, such as a ball shaped forward end, or the like. For example, the end may be provided with a slightly enlarged rounded or ball-shaped head portion, which, however, may have at least a slightly smaller diameter than the diameter of the tube, or a diameter slightly or significantly greater than the diameter of the tube.

[0087] The tip may also be curved, forming a Tiemann or Coude type catheter. Such a tip is illustrated in FIG. 3. The curved tip also has a diameter dT which at all places is equal to or lower than the outer diameter d of the tubular shaft. The curved tip preferably has a height K in a lateral direction which is higher than the diameter d of the tube, and preferably the relation K/d is in the range 1.5-2.

[0088] The tip of the catheter forms a free forward end which presents the free forward end of the catheter body, which is spaced apart from the forward end portion of the tubular shaft. Thus, the shaft extends rearwardly from the rear end of the tip portion. A lumen extends through the tubular shaft, from the discharge end to the forward end of the catheter. The lumen ends in drainage openings, so-called eyes. These eyes may be arranged in the forward end of the tubular shaft, in which case the lumen does not need to continue into the tip, which may as a consequence be solid.

[0089] The tip may have an outer diameter which at all places is equal to or lower than the outer diameter of the tubular shaft. However, alternatively, the tip may have a diameter which at least on some positions has a diameter exceeding the diameter of the shaft. For example, the tip may form a ball shape at the end of the catheter.

[0090] The tips may be designed, formed and connected to the tubular shaft in various ways, and some exemplary embodiments of this will now be discussed in more detail.

[0091] According to one embodiment for forming a urinary catheter, and in particular a urinary catheter tip, schematically illustrated in FIG. 4, the method comprises a first step of providing a tubular catheter shaft 3. The catheter shaft may e.g. be obtained by cutting a suitable length from a continuous extruded tube.

[0092] In a second step, a connector is arranged at one end of the catheter shaft. The connector may e.g. be made separately, and be connected to the catheter shaft by welding, adhesion or the like. However, alternatively, the connector may be formed directly from the shaft material, e.g. by thermoforming, to be integrally and monolithically connected to the shaft. In some embodiments, the connector may also be omitted.

[0093] In a further step, the insertion end of the catheter shaft, i.e. the end being opposite to the connector end, is thermoformed into a closed end 51. Such thermoforming of a closed end is per se well known in the art, and may e.g. by obtained by inserting the non-closed end into a heated die, e.g. forming a tapering and/or rounded tip.

[0094] In a further step, the thermoformed, closed end of the catheter shaft is inserted into an injection mold cavity, as will be discussed in more detail below, and a thermoplastic polymer material is injected into the mold cavity to form a tip 52 on the thermoformed, closed end 51 of the tubular catheter shaft. Hereby, the thermoformed, closed end of the catheter shaft is over molded by the tip in the tip forming injection molding step.

[0095] The steps may be performed in a different order. For example, the (optional) connector may be connected or formed to the catheter shaft before or after the injection molding of the tip.

[0096] The thermoformed end 51 preferably forms a tapered contacting surfaces for the tip 52. Hereby, a larger attachment area, and a stronger attachment, is obtained.

[0097] In another embodiment for forming a urinary catheter, and in particular a urinary catheter tip, shown schematically in FIG. 5, the method comprises a first step of providing a tubular catheter shaft 3. The catheter shaft may e.g. be obtained by cutting a suitable length from a continuous extruded tube.

[0098] In a second step, a connector is arranged at one end of the catheter shaft. The connector may e.g. be made separately, and be connected to the catheter shaft by welding, adhesion or the like. However, alternatively, the connector may be formed directly from the shaft material, e.g. by thermoforming, to be integrally and monolithically connected to the shaft. In some embodiments, the connector may also be omitted.

[0099] In a further step, the non-closed end 51 of the catheter shaft is inserted into an injection mold cavity (to be discussed in further detail in the following), and a thermoplastic polymer material is injected into the mold cavity to form a tip 52 on the non-closed end 51 of the tubular catheter shaft. Hereby, the tip material enters into the lumen of the catheter shaft to a controlled degree. To this end, the injecting of the thermoplastic polymer material into the mold cavity is controlled so that a limited amount of thermoplastic polymer enters into the lumen. How far the injection molded material penetrates into the lumen of the catheter shaft may be controlled by controlling the injection molding parameters, such as one or several of injection speed, injection time, the melt temperature, and volume of injected material. Hereby, the injected material forms a controlled stub shaft 53 protruding into the opening and lumen of the non-closed end 51, and with the rest of the tip 52 extending out from the catheter shaft in a proximal, forward direction. Hereby, a strong bond to the shaft is formed.

[0100] Also in this embodiment the steps may be performed in a different order. For example, the (optional) connector may be connected or formed to the catheter shaft before or after the injection molding of the tip.

[0101] In order to provide a stronger connection between the tip and the tubular shaft, the inner surface of the tubular shaft may be provided with a surface texture or surface features, e.g. to form a mechanical engagement. For example, the tubular shaft may, on an interior wall of the lumen and closed to the end, be provided with indent elements, such as holes, grooves or the like.

[0102] With reference to FIG. 6, the mold apparatus may comprise a mold 6, forming a mold cavity therein. The mold may comprise two separable parts 61, 62, which are brought together to form the mold cavity, and which may be separated for extraction of the catheter when the tip has been formed. However, alternatively, the mold may be formed by a single part. The mold cavity further comprises an open end 63, through which the catheter shaft 3, illustrated with dashed lines, may be inserted. The cavity opening 63 is preferably dimensioned to snuggly received the catheter shaft, so that the internal diameter of the opening is essentially equal to, or only slightly larger, than the outer diameter of the catheter shaft. The mold cavity is shaped in correspondence with the shape of the tip to be formed. A gate 64 is provided to allow melted, liquefied material to be inserted into the mold cavity. The gate may e.g. be positioned in one of the parts 61, 62, and relatively close to the end of the inserted catheter shaft. However, other positions are also feasible, such as in a centerline of the catheter shaft, in front of the forward most part of the tip to be formed, i.e. at the apex of the tip. Multiple gates may also be used. A small depression can be designed into the internal end of the gate, so that any gate residue in the formed part is not protruding from the surface of the tip.

[0103] The mold may be non-heated, whereby the only heat is provided by the melted, liquefied material injected through the gate. However, alternatively, the mold may be heated. A mold may be heated in various ways, such as by arranging an internal heater within the mold, or by an external heater. In the illustrative example of FIG. 7, an external heater 66 is schematically illustrated. The heater may heat the mold by irradiation, by hot air, etc, as is per se known in the art.

[0104] When the inserted catheter shaft presents a closed end, the end of the catheter shaft serves as a stop for the material injected into the mold cavity. Thus, in this case, the inserted catheter end may be seen as forming one of the walls of the mold cavity. This ensures that the mold cavity will fill properly, resulting in a well formed tip of controlled geometry.

[0105] When a catheter shaft with a non-closed end is inserted into the mold cavity, there is no such stop. However, by adequate control of the injection molding, the degree of penetration into the lumen of the catheter shaft of the injected material may be controlled, so that a suitable stub-shaft is formed.

[0106] However, to further control the degree of penetration of the injected material into the lumen, a controllable counter pressure may also be provided, by a pressure device 65. This may e.g. be provided through the lumen of the catheter shaft. Such an overpressure may then be controlled to provide a resistance for the thermoplastic polymer material to enter into the lumen, and the overpressure may be controlled to provide an adequate length of penetration. Providing a higher overpressure will provide a stronger resistance and a lower depth of penetration, whereas a lower overpressure, or no overpressure at all, will provide less resistance and a corresponding deeper penetration.

[0107] In both the above-discussed methods, a very strong bond between the shaft and the injection molded tip is created, inter alia due to the large overlapping areas.

[0108] The mold cavity may further be heated during molding, whereby the material of the shaft will be softened not only by the heated injection molded thermoplastic polymer material, but also by the heating of the mold. This ensures an even stronger attachment of the tip to the shaft, since the materials will hereby also be fused together. However, alternatively the heat provided by the heated thermoplastic polymer that is injected is in itself sufficient to provide adequate heating to form a strong attachment, in which case no additional heating of the mold is necessary.

[0109] Preferably, the thermoplastic polymer to be injected is heated to a temperature exceeding the melting temperature of the tubular catheter shaft immediately prior to being injection molded in to the mold cavity, and preferably exceeding said melting temperature with at least 10 degrees C. Hereby, it has been found, a very strong adhesion between the shaft and the tip is obtained, without any risk of damage and deformation of the shaft.

[0110] The material for injection molding is preferably one that is compatible with the catheter shaft material, to ensure good bonding between the molded tip and the catheter shaft.

[0111] After the injected tip material cools, optionally the mold halves are separated and the catheter shaft and tip are removed from the cavity. Alternatively, the mold may be one piece, and the catheter shaft with the tip may just be pulled free of the mold. The result is a formed tip of desired geometry that is integral with the end of the catheter shaft.

[0112] In these methods, the forming of the tip may further comprise cooling of the mold cavity to solidify the injected thermoplastic polymer material, before removing the tubular catheter shaft with the formed tip from the mold. Cooling of the mold, after having introduced the thermoplastic polymer material, and thereby having formed the tip, ensures the integrity of the shaped tip, and also facilitates removal from the mold cavity.

[0113] The methods may further comprise the step of inserting an elongate insert into the axially extending lumen prior to inserting an end of the catheter shaft into the mold, wherein the insert has a smaller outer diameter than the inner diameter of the lumen, forming a gap between an outer circumferential surface of the elongate insert and an inner circumferential surface of the lumen, the insert thereby being loosely arranged within the lumen. The elongate insert may e.g. be a narrow steel rod or the like. Insertion of such an elongate insert does not affect the penetration of the injected thermoplastic polymer material, but ensures that the shape of the catheter shaft is not altered during the injection molding process. For example, it prevents inadvertent collapsing of the shaft. Thus, the elongate insert ensures that the shaft remain straight, and with an equally sized lumen along its length. However, in many cases, depending on the materials used and the process parameters, such as the temperature, there is no need for such an additional precaution, and in such cases there is no need for use of such an elongate insert.

[0114] The catheter can be non-coated, and can e.g. be used together with a gel lubricant or the like for insertion. The catheter may also be formed by a material having low friction, and can e.g. be made by a hydrophilic material. However, the catheter is preferably coated, as have been discussed in the foregoing. In particular, for catheters, it is preferred to coat the outer surface, at least of the insertable part, with a hydrophilic coating. Many different types of well-known hydrophilic surfaces can be used.

[0115] In case a hydrophilic coating is used, it is preferred that both the tip and an insertable part of the tubular shaft are provided with said coating. The coating may be applied after joining of the tip and the tubular shaft, but may alternatively be provided separately to the tip and the tubular shaft, prior to joining.

[0116] Upon use, the catheter, when being provided with a hydrophilic coating, or being made by a hydrophilic material, is wetted by a wetting fluid, whereby the hydrophilic surface becomes slippery and easy to insert into e.g. the urethra of the patient, i.e. to provide a low-friction character of the surface. The wetting fluid is preferably a water-based liquid, i.e. using water as a solvent.

[0117] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For instance, the tip need not be continuously tapering, but have other geometrical shapes. Further, the tip may be either straight, pointing directly in the longitudinal direction of the catheter, or be slightly curved, so that the end of the tip points in a direction which is non-parallel to the longitudinal direction of the catheter. Further, many different materials and material combinations may be used to produce the tubular shaft and the tip, and still obtain the desired material properties. Still further, the access openings/drainage eyes may be provided in either the tip or in the forward end of the tubular shaft, or even in both. Such and other modifications should be construed to fall within the scope of the appended claims.