Silicone separator coating

Abstract

A silicone separator having a surface coating is disclosed. The coated silicone septum may be incorporated into an intravenous catheter assembly. The coating reduces electrostatic charge among a plurality of vibrating silicone septums during manufacture of the intravenous catheter assembly. The surface coating includes a coating agent selected from the group consisting of bicarbonate and siloxane polyoxyalkylene copolymers. The bicarbonate may be an alkali metal bicarbonate. The siloxane polyoxyalkylene copolymer may include a copolymer group selected from the group consisting of ethylene oxide, octamethylcyclotetrasiloxane, and mixtures thereof. The silicon separator may be coated by contacting an outer surface of the silicone separator with a coating solution having a solvent and the coating agent for at least 5 minutes. The coating agent has a concentration in the solvent higher than 1% by weight. The excess coating solution is removed from the outer surface of the silicone separator. The outer surface is dried to remove the solvent, thereby forming the surface coating.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to coatings for silicone diaphragms of intravenous (IV) catheter assemblies. The present invention also relates to methods of coating silicone diaphragms. The silicone diaphragm coatings disclosed herein can reduce static charge among multiple vibrating silicone diaphragms and can facilitate the manufacture of intravenous catheter assemblies.

[0002] Intravenous catheter assemblies are one of various types of vascular access devices. The intravenous catheter assemblies disclosed herein include a catheter connected to a catheter hub.

[0003] A diaphragm is placed within the lumen of the intravenous catheter assembly to prevent or restrict fluid flow through the catheter hub. The diaphragm generally comprises a flexible or semi-flexible material that is compatible with blood, pharmaceuticals, and other fluids commonly encountered during an infusion procedure. The diaphragm can comprise a silicone material. A groove can be provided on the inner surface of the catheter hub, where the diaphragm is seated. Thus, the position of the diaphragm within the catheter hub is maintained.

[0004] During the manufacture of intravenous catheter assemblies, multiple silicone diaphragms are placed within a vibrating feeder bowl. The vibration separates the diaphragms and moves them through a feed line, where they are ultimately picked up and placed into the catheter hubs. The vibration also causes the diaphragms to bounce and rub against each other, thereby generating static charge. Under these conditions, the static charge causes the diaphragms to stick to each other and not move through the feed line at the required manufacturing speed.

[0005] There is a need to prevent or reduce static charge among multiple vibrating silicone diaphragms such that the diaphragms do not stick to each other and such that the diaphragms will move through the feed line during manufacture at a suitable feed rate, thereby facilitating the manufacture of intravenous catheter assemblies. SUMMARY OF THE INVENTION

[0006] The present invention generally relates to a coating for a silicone diaphragm used in a vascular access device, such as an intravenous catheter assembly. The present invention relates to an intravenous catheter assembly comprising a coated silicone diaphragm as disclosed herein. The present invention also relates to a method of coating a silicone diaphragm. The present invention relates to a method of reducing static charge among multiple vibrating silicone diaphragms by coating a silicone diaphragm as disclosed herein.

[0007] One general aspect of the disclosed invention includes a silicone diaphragm comprising a surface coating. The surface coating comprises a coating agent selected from bicarbonates and silicone polyalkylene oxide copolymers.

[0008] Non-limiting examples of bicarbonates include alkali metal bicarbonates, such as lithium bicarbonate, sodium bicarbonate, and potassium bicarbonate.

[0009] The silicone polyoxyalkylene copolymer may comprise copolymer groups selected from ethylene oxide, octamethylcyclotetrasiloxane, and mixtures thereof. An example of such a silicone compound is the L-8620 surfactant available from Momentive Performance Materials Inc.

[0010] Another general aspect of the disclosed invention includes an intravenous catheter assembly comprising a silicone diaphragm coated as disclosed herein.

[0011] One general aspect of the disclosed invention includes a method of coating a silicone diaphragm. The method includes contacting an outer surface of the silicone diaphragm with a coating solution. The coating solution may include a solvent and a coating agent. The coating agent is selected from bicarbonates and silicone polyoxyalkylene copolymers. The coating agent has a concentration in the solvent greater than 1 wt%.

[0012] In one embodiment of the method, the outer surface of the silicone diaphragm is contacted with the coating solution for at least 5 minutes.

[0013] The method further includes removing excess coating solution from the outer surface of the silicone diaphragm.

[0014] The method further includes drying the outer surface of the silicone diaphragm.

[0015] In one non-limiting embodiment of the method, the coating agent has a concentration in the solvent of 1 wt% to 10 wt%. In another non-limiting embodiment, the coating agent has a concentration in the solvent of 1 wt% to 5 wt%. In another non-limiting embodiment, the coating agent has a concentration in the solvent of 2 wt% to 4 wt%.

[0016] In one embodiment, the solvent is water.

[0017] In one embodiment, the coating agent comprises sodium bicarbonate. In another embodiment, the coating solution contains 2 wt% to 3 wt% sodium bicarbonate.

[0018] In one embodiment, the coating agent comprises a silicone polyoxyalkylene copolymer containing ethylene oxide. In one embodiment, the coating agent comprises a silicone polyoxyalkylene copolymer containing octamethylcyclotetrasiloxane. In one embodiment, the coating agent comprises a silicone polyoxyalkylene copolymer containing ethylene oxide and octamethylcyclotetrasiloxane. In another embodiment, the coating solution contains 2.5 wt% to 3.5 wt% silicone polyoxyalkylene copolymer.

[0019] According to another set of embodiments, a silicone diaphragm comprising a surface coating as disclosed herein is incorporated into an intravenous catheter assembly.

[0020] A catheter assembly generally can include a catheter connected to a catheter hub. In some embodiments, the catheter can be used in combination with a metal introducer needle commonly known and used in the art.

[0021] In some embodiments of the present invention, a coated septum as disclosed herein is placed within the lumen of the catheter assembly to prevent or restrict fluid flow through the catheter hub. The coated septum generally includes a flexible or semi-flexible silicone material that is compatible with blood, medicaments, and other fluids commonly encountered during an infusion procedure.

[0022] In some embodiments of the present invention, closed or partially closed passageways, such as slits or apertures, are also provided in the barrier surface of the septum. The passageways permit fluid to bypass the septum and flow through the catheter hub. In some embodiments, the passageway is a slit that is closed prior to being opened or activated by a probe or septum activator placed within the lumen of the catheter hub. Prior to being opened or activated, the slit prevents fluid from passing through the catheter hub.

[0023] Another general aspect of the disclosed invention relates to a method of reducing static charge among a plurality of vibrating silicone septa. Static charge can be reduced by coating the plurality of silicone septa according to the coating methods disclosed herein.

[0024] It is to be understood that the foregoing summary and the following detailed description are merely exemplary and explanatory and are not restrictive of the invention as claimed. The various embodiments are not limited to the arrangements and instrumentalities shown in the drawings. Embodiments can be combined, or other embodiments can be utilized, and structural changes (unless so required) can be made without departing from the scope of the various embodiments of the invention. Accordingly, the following detailed description is not to be taken in a limiting sense. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments will be described and illustrated with additional features and details by using the drawings, in which:

[0026] Figure 1 is an exploded cross-sectional view of a coated silicone septum included within an intravenous catheter assembly.

[0027] Figure 2 is a perspective view of an embodiment of a septum according to the disclosed invention. DETAILED DESCRIPTION

[0028] The following description provides specific details to provide a thorough understanding of the coatings for silicone diaphragms used in vascular access devices, such as intravenous catheter assemblies, and the method of coating such silicone diaphragms. The following description also discloses an intravenous catheter assembly comprising a coated silicone diaphragm. The following description also describes a method of reducing static charge among multiple vibrating silicone diaphragms by coating the silicone diaphragm as disclosed herein, thereby facilitating the manufacture of intravenous catheter assemblies.

[0029] Those skilled in the art will understand that the silicone diaphragm coatings, vascular access devices containing the coated diaphragms, the related methods of coating silicone diaphragms, and the method of reducing static charge of multiple vibrating silicone diaphragms represent only the presently preferred embodiments of the invention, and the details disclosed herein may be arranged and implemented in a variety of different configurations without being limited to the specifically disclosed embodiments. In fact, the disclosed coated silicone diaphragms may be practiced by modifying the devices shown and may be used in combination with any other instruments and techniques commonly used in the industry.

[0030] The disclosed invention addresses problems observed during the manufacture of intravenous catheter assemblies including silicone diaphragms, such as the Safe Intravenous Catheter Assembly of Becton, Dickinson and Company.

[0031] Such silicone diaphragms were initially coated with a Parylene coating to improve the operation and manufacture of the Safe Intravenous Catheter Assembly. It was found that the Parylene coating degraded the performance of the catheter assembly. The Parylene coating was removed from the silicone diaphragm. However, despite the design of the manufacturing equipment, it was found that due to the static charge generated by the silicone diaphragms vibrating in a vibrating bowl, the uncoated diaphragms could not achieve the required manufacturing feed rate through the vibrating bowl. The disclosed invention relates to two different silicone diaphragm coatings that exhibit minimal static charge during the vibration cycle and improve the manufacturing feed cycle rate.

[0032] In one embodiment, the silicone diaphragm comprises a surface coating containing a bicarbonate coating agent. The bicarbonate may be an alkali metal bicarbonate. Non-limiting examples of alkali metal bicarbonates include lithium bicarbonate, sodium bicarbonate, and potassium bicarbonate.

[0033] In one embodiment, the silicone diaphragm comprises a surface coating containing a siloxane polyalkylene oxide copolymer coating agent. The siloxane polyalkylene oxide copolymer may include a copolymer group containing ethylene oxide, a copolymer group containing octamethylcyclotetrasiloxane, or a copolymer group containing ethylene oxide and octamethylcyclotetrasiloxane. An example of such a siloxane compound is available from Momentive Performance Materials Inc. L-8620 surfactant.

[0034] The disclosed invention includes a method for coating a silicone diaphragm. The method includes contacting the outer surface of the silicone diaphragm with a coating solution. The coating solution includes a solvent and a coating agent. The coating agent is selected from bicarbonates and silicone polyoxyalkylene copolymers. In a non-limiting embodiment, the solvent is water. The coating agent has a concentration greater than 1% by weight in the solvent.

[0035] In the method, the outer surface of the silicone diaphragm is contacted with the coating solution for at least 5 minutes.

[0036] Excess coating solution is removed from the outer surface of the silicone diaphragm. The solvent is removed by drying, thereby depositing the coating agent on the outer surface of the silicone diaphragm.

[0037] In a non-limiting embodiment, the coating agent may have a concentration of 1% to 10% by weight in the solvent. In another non-limiting embodiment, the coating agent has a concentration of 1% to 5% by weight in the solvent. In another non-limiting embodiment, the coating agent has a concentration of 2% to 4% by weight in the solvent.

[0038] In one embodiment, the coating agent includes sodium bicarbonate. In another embodiment, the coating solution contains 2% to 3% by weight of sodium bicarbonate.

[0039] In another embodiment, the coating solution contains 2.5% to 3.5% by weight of a silicone polyoxyalkylene copolymer. In one embodiment, the coating agent includes a silicone polyoxyalkylene copolymer containing ethylene oxide. In one embodiment, the coating agent includes a silicone polyoxyalkylene copolymer containing octamethylcyclotetrasiloxane. In one embodiment, the coating agent includes a silicone polyoxyalkylene copolymer containing ethylene oxide and octamethylcyclotetrasiloxane.

[0040] Other features and advantages of the present invention are apparent from the following various examples. The following examples illustrate different aspects and embodiments of the present invention and how to make and practice them. The examples do not limit the claimed invention.

[0041] Example 1. Coating and deposition methods for siloxane polyalkylene oxide copolymers

[0042] Mix 3% by weight of L-8620 silicone polyoxyalkylene copolymer with distilled water to form a coating solution. Mix this coating solution using a mechanical mixer. The L-8620 silicone polyoxyalkylene copolymer is manufactured by Momentive Performance Materials Inc. of Friendly, West Virginia. The copolymer contains ethylene oxide and octamethylcyclotetrasiloxane.

[0043] A plurality of silicone diaphragms are dropped into a lubricating oil tank and oscillated on a mechanical oscillator (Heidolph TM Vibramax vibrating platform oscillator, factory serial number 036130120) at 100 RPM for 5 minutes.

[0044] A plurality of silicone diaphragms are separated from the coating solution by pouring the mixture through a sieve (US standard size 6, Fisher Scientific part number 048841AB). The sieve aperture is 3.35 mm nominal sieve opening.

[0045] A plurality of silicone diaphragms are left in the sieve and placed on an oscillator at 1100 RPM for 3 hours.

[0046] After oscillating the diaphragms to remove excess solution, the diaphragms are dried overnight. In the laboratory, the diaphragms coated with Silwet L-8620 silicone polyoxyalkylene copolymer are tested on a vibrating bowl similar to the production vibrating bowl. The concentration of the coating is confirmed in the laboratory. Thereafter, the silicone diaphragms coated with 3.0% Silwet L-8620 silicone polyoxyalkylene copolymer are also tested on the manufacturing equipment. The empirical results show that the silicone diaphragms coated with Silwet L-8620 silicone polyoxyalkylene copolymer meet and exceed the required manufacturing feed rate.

[0047] Example 2. Coating and deposition methods for alkali metal bicarbonates

[0048] 2.5 wt% sodium bicarbonate is mixed with distilled water to form a coating solution. This coating solution is mixed using a mechanical mixer.

[0049] A plurality of silicone diaphragms are dropped into a lubricating oil tank and oscillated on a mechanical oscillator (Heidolph TM Vibramax vibrating platform oscillator, factory serial number 036130120) at 100 RPM for 5 minutes.

[0050] A plurality of silicone diaphragms are separated from the coating solution by pouring the mixture through a sieve (US standard size 6, Fisher Scientific part number 048841AB). The sieve aperture is 3.35 mm nominal sieve opening.

[0051] A plurality of silicone diaphragms are left in the sieve and placed on an oscillator at 1100 RPM for 3 hours.

[0052] After oscillating the diaphragm to remove excess solution, the diaphragm was dried overnight. In the laboratory, the sodium bicarbonate-coated diaphragm was tested on a vibrating bowl similar to the production vibrating bowl. The concentration of the sodium bicarbonate coating was confirmed in the laboratory. Thereafter, a silicone diaphragm coated with 2.5% sodium bicarbonate was also tested on the manufacturing equipment. The empirical results showed that the silicone diaphragm coated with sodium bicarbonate met and exceeded the required manufacturing feed rate. Some sodium bicarbonate crystals remained on the diaphragm.

[0053] Another general aspect of the disclosed invention relates to a method of reducing static charge among a plurality of vibrating silicone diaphragms. The static charge can be reduced by coating a plurality of silicone diaphragms according to the coating methods disclosed herein.

[0054] Another general aspect of the disclosed invention includes an intravenous catheter assembly comprising a coated silicone diaphragm as disclosed herein.

[0055] A non-limiting example of a prior art catheter assembly is disclosed in U.S. Publication No. 2011 / 0160663A1, which is incorporated herein by reference. A non-limiting example of a commercially available catheter assembly is the Safety Intravenous Catheter Assembly of Becton Dickinson and Company.

[0056] Now referring to Figure 1 , a disassembled cross-sectional view of the catheter assembly 10 is shown. The catheter assembly 10 generally includes a catheter 12 connected to the distal end of a catheter hub 14. The catheter 12 and the catheter hub 14 are integrally connected such that the lumen 16 of the catheter hub 14 is in fluid communication with the lumen 18 of the catheter 12. The catheter 12 generally comprises a biocompatible material having sufficient stiffness to withstand the pressures associated with inserting the catheter into a patient. In some embodiments, the catheter 12 comprises a rigid polymeric material such as vinyl resin.

[0057] The catheter hub 14 includes various design features and components to control and / or restrict fluid flow through the catheter assembly 10. For example, in some inventive embodiments, a diaphragm 50 comprising a surface coating 51 as disclosed herein is disposed within the lumen 16 of the catheter hub 14.

[0058] The septum 50 generally comprises a flexible or semi-flexible polymeric plug having an outer diameter configured to fit suitably within a groove or channel 60 formed in the inner surface 24 of the catheter hub 14. In some embodiments, the septum 50 is cylindrical, having a barrier surface 52 including the distal end of the septum 50, and further having an opening 54 including the proximal end of the septum 50. When placed within the channel 60, the barrier surface 52 of the septum 50 divides the lumen 16 of the catheter hub 14 into a forward fluid chamber 62 and a rearward fluid chamber 64. Thus, the presence of the septum 50 controls or restricts fluid passage between the forward fluid chamber 62 and the rearward fluid chamber 64. Specifically, the selected configuration of the barrier surface 52 of the septum 50 largely determines the ability of fluid to flow through the lumen 16 of the catheter hub 14.

[0059] For example, in some embodiments the barrier surface 52 of the septum 50 is configured to include a slit 56. The slit 56 is configured to provide a selective passage or flow of fluid across the barrier surface 52. In some embodiments, the slit 56 is configured to remain in a closed, leak-proof position until activated or opened by advancing a septum activator 80 in the distal direction 92 through the slit 56. In some embodiments, the barrier surface 52 includes one slit 56. In other embodiments, the septum 50 may include more than one slit. In some embodiments, the septum 50 consists essentially of a silicone rubber material.

[0060] Now referring Figure 2 , an embodiment of a septum 150 is shown. The outer surface 66 of the septum 150 is provided with a surface coating as disclosed herein. In some embodiments, the outer surface 66 of the septum 150 is modified to include a plurality of grooves 72. The grooves 72 provide a passage between the forward chamber 62 and the rearward chamber 64 through which air and / or fluid can flow. Thus, in some embodiments the outer surface 66 of the septum 150 is modified to provide a desired flow between the forward chamber 62 and the rearward chamber 64.

[0061] The features of the catheter assembly can be used in combination with an over-the-needle catheter assembly. For example, a flexible or semi-flexible polymeric catheter can be used in combination with a rigid introducer needle to enable the catheter to be inserted into a patient. A surgically implantable catheter can also be used.

[0062] An over-the-needle catheter assembly is a common IV catheter configuration. As the name implies, the over-the-needle catheter is mounted on an introducer needle having a sharp distal tip. The introducer needle is generally a venipuncture needle that is attached to a needle assembly that helps guide the needle and facilitate its engagement with the catheter. At least the inner surface of the distal portion of the catheter closely engages the outer surface of the needle to prevent the catheter from peeling away and thus facilitate catheter insertion into a blood vessel. The catheter and the introducer needle are typically assembled such that the sharp distal tip of the introducer needle extends beyond the distal tip of the catheter to facilitate insertion into a blood vessel through the patient's skin.

[0063] After the catheter and introducer needle are inserted into the blood vessel at the catheter insertion site, the introducer needle is removed leaving the catheter in the blood vessel. Once inserted into the patient, the catheter 12 and catheter adapter 14 provide a fluid passageway to facilitate delivery of fluid to and / or retrieval of fluid from the patient as required by a desired infusion procedure. Thus, in some embodiments, the materials of the catheter 12 and catheter adapter 14 are selected to be compatible with biological fluids and agents commonly used in infusion procedures. The catheter 12 can be used to inject fluids (such as saline solution, blood, agents, and / or total parenteral nutrition) into the patient, withdraw fluids (such as blood) from the patient, and / or monitor various parameters of the patient's vascular system. The removed introducer needle is considered a "blood-contaminated sharp" and must then be handled and discarded appropriately.

[0064] To increase safety, intravenous catheters and needle assemblies can be manufactured with retractable needles. Some exemplary catheter and needle assemblies can include a hollow handle, a gripping portion, a catheter tip containing a catheter, and an elongate needle having a first position in which the elongate needle is slidably disposed within the catheter and a second position in which the elongate needle is slidably removed from the catheter and at least partially retracted into the hollow handle. As disclosed herein, the catheter tip can include a septum 50 configured to form a leak-proof seal when the elongate needle is in the second position. The elongate needle passes through the septum when in the first position.

[0065] Continuing reference Figure 1 , the septum activator 80 includes a probe-like structure that is primarily housed within the rear chamber 64 of the catheter adapter 14. The septum activator 80 generally includes a tubular body 82 having a distal end 84 and a proximal end 86. The tubular body 82 includes a rigid or semi-rigid material, such as a plastic or metallic material. The tubular body 82 also includes a lumen 88 to facilitate the flow of fluid and / or liquid through the septum activator 80.

[0066] The distal end 84 of the tubular body 82 is configured to be suitably inserted into the opening 54 of the septum 50. The distal end 84 also includes a probe surface 90 that extends through the opening 54 of the septum 50 to a position adjacent to the barrier surface 52 of the septum 50. As the septum activator is advanced in the distal direction 92 through the catheter adapter 14, the probe surface 90 is advanced through the slit 56 or through the leak hole 58.

[0067] It will be understood that the disclosed invention provides a coating for a silicone septum of an intravenous catheter assembly. The disclosed invention also provides a method of coating a silicone septum. The silicone septum coatings disclosed herein can reduce static charge among multiple vibrating silicone septa to facilitate the manufacture of intravenous catheter assemblies.

[0068] The present invention may be embodied in other specific forms without departing from the structures, methods, or other essential features as generally described herein and as required below. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Accordingly, the scope of the present invention is indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A silicone diaphragm comprising a surface coating, wherein the surface coating comprises a coating agent selected from bicarbonate and siloxane polyoxyalkylene copolymer.

2. The silicone diaphragm according to claim 1, wherein the coating agent comprises an alkali metal bicarbonate.

3. The silicone diaphragm according to claim 1, wherein the coating agent comprises sodium bicarbonate.

4. The silicone diaphragm according to claim 1, wherein the coating agent comprises a siloxane polyoxyalkylene copolymer, which comprises copolymer groups selected from ethylene oxide, octamethylcyclotetrasiloxane, and mixtures thereof.

5. An intravenous catheter assembly comprising the silicone diaphragm according to claim 1.

6. An intravenous catheter assembly comprising the silicone diaphragm according to claim 2.

7. An intravenous catheter assembly comprising the silicone diaphragm according to claim 4.

8. A method of coating a silicone diaphragm, comprising: contacting an outer surface of the silicone diaphragm with a coating solution comprising: a solvent; and a coating agent, wherein the coating agent is selected from bicarbonate and siloxane polyoxyalkylene copolymer, and wherein the coating agent has a concentration higher than 1% by weight in the solvent, wherein the outer surface of the silicone diaphragm is contacted with the coating solution for at least 5 minutes; removing excess coating solution from the outer surface of the silicone diaphragm; and drying the outer surface of the silicone diaphragm.

9. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent has a concentration of 1% to 10% by weight in the solvent.

10. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent has a concentration of 1% to 5% by weight in the solvent.

11. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent has a concentration of 2% to 4% by weight in the solvent.

12. The method of coating a silicone diaphragm according to claim 8, wherein the solvent is water.

13. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent comprises sodium bicarbonate.

14. The method of coating a silicone diaphragm according to claim 13, wherein the coating solution contains 2% to 3% by weight of sodium bicarbonate.

15. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent comprises a siloxane polyoxyalkylene copolymer containing ethylene oxide.

16. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent comprises a siloxane polyoxyalkylene copolymer containing octamethylcyclotetrasiloxane.

17. The method of coating a silicone diaphragm according to claim 8, wherein the coating agent comprises a siloxane polyoxyalkylene copolymer containing ethylene oxide and octamethylcyclotetrasiloxane.

18. The method of coating a silicone diaphragm according to claim 17, wherein the coating solution contains 2.5% to 3.5% by weight of siloxane polyoxyalkylene copolymer.

19. A method of reducing static charge among a plurality of vibrating silicone diaphragms, comprising coating a silicone diaphragm according to the method of claim 8.

20. A method for reducing static charge among a plurality of vibrating silicone diaphragms, comprising coating a silicone diaphragm according to the method of claim 11.

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