IMPROVED MATERIAL FOR MEDICAL GRADE TUBING

Abstract: A non-PVC, non-DEHP material is provided for medical grade tubing (14). The material comprises a blend of polyurethane and polyester. The resultant tubing of the present invention has good low temperature characteristics, is autoclavable, and RF sealable. Accordingly, the resultant tubing (14) can be utilized for applications which heretofore have been filled in the marketplace by DEHP plasticized PVC tubing. In an embodiment, the material includes a citrate ester.

Description: S P E C I F I C A T I O N "Improved Material for Medical Grade Tubing" BACKGROUND OF THE INVENTION The present invention relates generally to medical products and compositions for making same. More specifically, the present invention relates to non-PVC material and medical tubing made therefrom. Typically, medical tubing, for example for use in blood collection sets as the donor tubing, is constructed from plasticized polyvinyl chloride (PVC) . Usually, the PVC is plasticized with DEHP. Recently there has been concern with respect to the use of DEHP plasticized PVC. DEHP has been alleged to be a suspected carcinogen. However, the characteristics that are afforded by plasticized PVC are very desirable especially in the medical area and for uses such as the donor tube in blood collection systems. To this end, such tubing typically must have low temperature characteristics. Furthermore, it is desirable that the tubing can be solvent bonded to a PVC material: the containers to which the tubing is secured are usually constructed from PVC. It is also desirable that the tubing is RF sealable so as to be compatible with blood tubing sealing equipment presently used. Although there are other components in the art from which, arguably, medical tubing could be created, each of these components suffers disadvantages. Most importantly, the resultant product does not have the same desirable characteristics as a plasticized PVC product. For example, flexible polyester is not as RF responsive as is plasticized PVC. Aliphatic polyurethane is not autoclavable. Further, such tubings, due to their characteristics cannot be used on currently used commercial machinery in, for example, a blood collection system. U.S. Patent Application Serial No. 07/270,006, filed November 14, 1988, discloses a citrate ester in a non-PVC material. U.S. Patent Application Serial No. 07/494,045, filed May 15, 1990, is a divisional application to that patent application. Both of these Applications are assigned to the Assignee of the present invention. SUMMARY OF THE INVENTION The present invention provides a non-PVC and non- DEHP material that can be used for medical grade tubing. More particularly, the present invention provides medical grade tubing made from such material. The resultant tubing of the present invention has good low temperature characteristics, and unlike EVA tubing that also performs well at low temperatures, the tubing of the present invention is RF sealable even at low power levels. Therefore, the resultant tubing of the present invention is compatible with blood tubing sealing equipment presently used in the marketplace with plasticized PVC tubing. Additionally, the resultant product is autoclavable. To this end, in an embodiment, a medical grade tubing is provided comprising a blend of polyurethane and polyester, the resultant tubing being autoclavable and RF sealable. The present invention also provides a medical grade tubing comprising a blend of polyurethane, polyester, and a butryl trihexyl citrate. In an embodiment, a medical grade tubing is provided comprising approximately 30 to about 40 weight percent polyester and approximately 60 to about 70 weight percent polyurethane. Additionally, a non-PVC, non-DEHP material is provided for a medical grade tubing comprising approximately 30 to about 50 weight percent polyester and approximately 50 to about 70 weight percent polyurethane. In an embodiment, the material includes a citrate ester such as butryl trihexyl citrate. In a further embodiment, an assembly for the collection of blood is provided including a tubing comprising approximately 30 to about 50 weight percent polyester and approximately 50 to about 70 weight percent polyurethane. In an embodiment, the tubing includes a citrate ester. This tubing is autoclavable and RF sealable. Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings. BRIEF DESCRIPTION OF THE DRAWING Figure 1 illustrates a blood collection assembly including an embodiment of a medical grade tubing of the present invention. Figure 2 illustrates a perspective view of a tubing and membrane constructed pursuant to the present invention. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS A non-PVC, non-DEHP material is provided for medical grade tubing. The material comprises a blend of polyurethane and polyester. The resultant tubing of the present invention has good low temperature characteristics, is autoclavable, and RF sealable. Accordingly, the resultant tubing can be utilized for applications which heretofore have been filled in the marketplace by DEHP plasticized PVC tubing. Additionally, the material of the present invention is extrudable, injection moldable, and blow moldable. Because it is a non-PVC, non-DEHP material, it eliminates the environmental concerns of acid rain and the alleged carcinogenic properties of DEHP. Further, the resultant tubing is kink resistant. It has also been found that the resultant tubing of the present invention can be solvent bonded to PVC material that is currently utilized by using cyclohexanone. Additionally, the tubing is RF sealable allowing the tubing to make a donor tubing, or other tubing, that can be sealed on commercial blood collection equipment. Furthermore, the material can be autoclaved either through steam ETO or gamma sterilization. Preferably, the composition for creating the medical grade tubing comprises approximately 30 to about 50 weight percent polyester and approximately 50 to about 70 weight percent polyurethane. It has been found that a polyurethane available from Morton Thiokol under the trade name MORTHANE, PE-192-100 functions satisfactorily in the present invention. It has also been found that polyester available from Eastman Chemical Company under the trade name PCCE-9966 functions satisfactorily with the polyurethane available from Morton Thiokol. In an embodiment, the polyester and polyurethane are blended with a citrate ester. The citrate ester improves the flexibility of the resultant product. It has been found that butryl trihexyl citrate available from Moreflex under the designation CitroFlex B-6 functions satisfactorily in this regard - preferably approximately 5 to about 7.5 weight % citrate is used. Figure 1 illustrates a blood bag 10 and set 12 including a tubing 14 fabricated from the material of the present invention. Preferably, the blood bag 10 is constructed from PVC. The tubing 14 of the present invention allows the tubing to be solvent bonded to the bag 10. Additionally, the product can be autoclaved. Further, the tubing 14 is RF weldable allowing full use of commercial blood tube sealing equipment. An example of a blood bag system in which the tubing 14 of the present invention can be used is disclosed in U.S. Patent No. 4,608,178. By way of example and not limitation, examples of the present invention will now be set forth. Polyester (PCCE) available from Eastman Chemical Company under the designation PCCE-9966 and thermoplastic polyurethane (PE) available from Morton Thiokol under the designation PE-192-100 were utilized. Three formulation blends were created. The blends were as follows: Designation PCCE PE 1 40% (2 lbs) 60% (3 lbs) 2 35% (1.75 lbs) 65% (3.25 lbs) 3 30% (1.5 lbs) 70% (3.5 lbs) With the above formulations, the total blend of each formulation was 5 pounds. Approximately 0.1% Acrawax was added to each formulation. Each formulation was weighed and tumble-blended and kept in an oven at 150° for two hours prior to pelletizing. A total of 25 pounds of material was tumble-blended per formulation blend. The blended material was then pelletized. The following conditions were used: a 1 1/2" Killion extruder 24:1 L/D 3:1 C.R. Screen peek 40/100/200/100/40 Barrel zone #1 340'F zone #2 360 β F zone #3 375 β F Die zone #1 370 e F, melt temp. 380 β F RPM 50, Amps 15 Each formulation was pelletized and saved for extruding tubing. The pellets of each formulation were dried at 160"F for two hours. The extrusion conditions were as follows for each of samples 1, 2, and 3: Barrel zone #1 300 β F RPM 15 zone #2 330 β F Amps 11 zone #3 330 β F Killion 1 1/2" Die zone #1 340 β F L/D:24:l zone #2 340 β F C.R.:3:l Melt temp 343'F screen peak 40/100/200/100/40 Back pressure 4800-5000 psi Belt roller 3.8 Air pressure w/bleed 3.5 psi for tubing die Belt roller setting 3.8 Tubing size .118" X .020 WL X 100 FTL The tubing of each formulation was extruded and saved for functional testing. The tubing of formulations 2 and 3 were tacky during coiling. The tubing of formulation 1 was heat aged at 240'F for 50 minutes in a circulating air oven. At that temperature and time, the tubing survived without deformation to the tube. This condition was used to simulate an autoclave cycle. Also, the material was tried on a Hematron, with and without water, to investigate the RF sealability of the tubing. In both cases, the tubing of formulation 1 sealed the same as PVC tubing, using a presently available Hematron heat sealer. Also the tubing of formulation 1 was tried with the present design of a roller clamp to verify its functionality. The formulation 1 tubing performed the same as did PVC tubing. The formulation 1 tubing was tested for solvent bondability to itself, a presently used donor port and a commercially available PVC blood bag bushing were used. The tubing was attached using a presently used cyclohexanone solvent system. It was found that the tubing broke before the solvent bonding failed. Also, the formulation 1 tubing was found to be kink resistant. The formulation 1 tubing was tried for stripping the air from the tubing. The tubing was filled with colored water, sealed using a Hematron and stripped with a tubing stripper. The performance of the tubing was as good as that of PVC tubing. The clarity of formulation 1 tubing was found to be contact clear: the same as presently used PVC. Clarity can be improved during extrusion processing, for example, by proper orientation of the tubing during inline extrusion process. The tubing made from formulation 1 was attached to a needle assembly by being frictional fit. The attached tubing and needle assembly was sterilized and tested on an Instron and was found to perform as well as a PVC tubing and needle assembly. The results of the tests are as follows: Results Sample Pull Force, tubing To Needle Post. Tubing 1 20.8 Lbs., TBG Broke Formulation 2 20.9 " , TBG Broke No. 1 3 22.6 " , TBG Broke 4 21.6 " , TBG Broke 5 21.1 " , TBG Broke It should also be noted that if tackiness of the material on coiling is a problem, the increased addition of a small amount of an amide wax such as Acrawax, available from Glyco, can resolve the problem. The above examples demonstrate that the present invention provides a non-PVC, non-DEHP material that can be made into medical tubing. The material can be RF sealed at low frequency and power, such as on a Hematron dielectic sealer. The resultant tubing is kink resistant and solvent bondable. It has similar functional properties to standard PVC tubes. The tubing is autoclavable, gamma sterilizable, can be radiated by an E beam process, or Eto sterilized. Hot stamping can be achieved using standard hotstamp foil. The tubing is contact clear to clear. Formulations including a citrate ester were also created. These formulations were as follows: All of the above percents are weight percents. PCCE was purchased from Eastman, Polyurethane from Morton Thiokol, BTHC (Butryl Trihexyl Citrate) from Moreflex, and Acrawax from Glyco. Formula No. 4 was created as follows: A 20 pound batch was produced by weighing 11 pounds of PE-192-100 (Morthane) available from Morton Thiokol, 8 pounds of PCCE-9966 from Eastman, (these weights are dry weights) , and one pound of CitroFlex B-6 from Moreflex. The PE was added to a mixer and mixed at low speed (<1,000 RPM) for five minutes. CitroFlex was added and was also mixed at the low speed. PCCE was then added to the mixture and mixing was continued at a low speed for five minutes. The resultant mixture was discharged into a polyliner. The mixture was then pelletized into a blend. Formulations 5-8 were as created in this manner except, to improve tackiness Acrawax was added to the mixtures. The resultant mixtures (4-8) are flexible, have improved tackiness and are RF responsive on a Hematron sealer. These formulations are autoclavable, kink resistant, gamma sterilizable, and solvent bondable using cyclohexane. The formulations can be used for creating tubing for a medical container. Also, the formulations can be used for creating a tubing 20 and membrane 22 as illustrated in Figure 2. The tubing 20 can be created from a formulation such as No. 4 while the membrane 22, that is pierced by a spike to access an interior 24 of the tube is constructed from a formulation such as No. 5. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims: I CLAIM AS MY INVENTION: 1. A medical grade tubing comprising a blend of polyurethane and polyester, the tubing being autoclavable and RF sealable. 2. The medical grade tubing of Claim 1 comprising approximately 30 weight percent polyester and approximately 70 weight percent polyurethane. 3. The medical grade tubing of Claim 1 comprising approximately 35 weight percent polyester and approximately 65 weight percent polyurethane. 4. The medical grade tubing of Claim 1 comprising approximately 40 weight percent polyester and approximately 60 weight percent polyurethane. 5. The medical grade tubing of Claim 1 including an amide wax. 6. A medical grade tubing comprising approximately 30 to 50 weight percent polyester and approximately 50 to 70 weight percent thermoplastic polyurethane. 7. The medical grade tubing of Claim 6 including an amide wax. 8. The medical grade tubing of Claim 6 wherein the tubing comprises approximately 40 weight percent polyester and approximately 60 weight percent thermoplastic polyurethane. 9. An assembly for the collection of blood including a tubing comprising approximately 30 to about 50 weight percent polyester and approximately 50 to about 70 weight percent polyurethane, the tubing being autoclavable and RF sealable. 10. The assembly of Claim 9 wherein the tubing comprises approximately 40 percent polyester and approximately 60 percent polyurethane. 11. The assembly of Claim 9 wherein the tubing includes an amide wax. 12. A non-PVC non-DEHP material for medical grade tubing comprising approximately 30 to about 50 weight percent polyester and approximately 50 to about 70 weight percent polyurethane. 13. The non-PVC, non-DEHP material of Claim 12 comprising approximately 40 weight percent polyester and 60 weight percent polyurethane. 14. The non-PVC, non-DEHP material of Claim 12 comprising approximately 35 weight percent polyester and 65 weight percent polyurethane. 15. The non-PVC, non-DEHP material of Claim 12 comprising approximately 30 weight percent polyester and approximately 70 weight percent polyurethane. 16. The non-PVC, non-DEHP material of Claim 12 including an amide wax. 17. A medical grade tubing comprising approx¬ imately 30 to 50 weight percent polyester, approximately 50 to 70 weight percent polyurethane, and approximately 5 to about 7.5 weight percent citrate ester.' 18. The medical grade tubing of Claim 17 including an amide wax. 19. The medical grade tubing of Claim 17 wherein the tubing comprises approximately 40 weight percent polyester, approximately 55 weight percent polyurethane, and approximately 5 weight percent citrate ester. 20. The medical grade tubing of Claim 17 wherein the citrate ester is butryl trihexyl citrate. 21. An assembly for the collection of blood including a tubing comprising approximately 30 to about 45 weight percent polyester, approximately 50 to about 70 weight percent polyurethane, and approximately 5 to about 7.5 weight percent citrate ester, the tubing being autoclavable and RF sealable. 22. The assembly of Claim 21 wherein the tubing comprises approximately 40 percent polyester, approximately 55 percent polyurethane, and approximately 5 weight percent citrate ester. 23. The assembly of Claim 21 wherein the tubing includes an amide wax. 24. A non-PVC, non-DEHP material for medical grade tubing comprising approximately 30 to about 45 weight percent polyester, approximately 50 to about 70 weight percent polyurethane, and approximately 5 to about 7.5 weight percent citrate ester. 25. The non-PVC, non-DEHP material of Claim 24 comprising approximately 40 weight percent polyester, approximately 55 weight percent polyurethane, and approximately 5 weight percent citrate ester. 26. The non-PVC, non-DEHP material of Claim 24 co rising approximately 45 weight percent polyester and approximately 47 to about 50 weight percent polyurethane. 27. The non-PVC, non-DEHP material of Claim 25 wherein the citrate ester is butryl trihexyl citrate. 28. The non-PVC, non-DEHP material of Claim 25 including an amide wax.

Inventors: PATEL INDRAJIT, PATEL, INDRAJIT
Applicants: BAXTER INT, BAXTER INTERNATIONAL INC.
Application year: 1991
Main classification: A61B19
IPC codes: A61J1, A61L29, A61M25, A61M39, C08K5, C08L67, C08L75