Coated fabrics for medical applications and methods for making and recycling same

Abstract

Coated fabrics for use in medical applications may include a thermoplastic elastomer coating on a nonwoven fabric. The coated fabrics may be weldable to make inflatable bladders, such as for blood pressure cuffs and deep vein thrombosis (DVT) sleeves. Beneficially, the coated fabrics may be recyclable.

Description

[0001] COATED FABRICS FOR MEDICAL APPLICATIONS AND METHODS FOR MAKING AND RECYCLING SAME

[0002] FIELD OF TECHNOLOGY

[0003] One or more aspects relate generally to coated fabrics for use in various medical applications, as well as methods for manufacturing and recycling the same.

[0004] BACKGROUND

[0005] Current blood pressure cuffs are made by extruding polyvinyl chloride (PVC) onto spunlace polyester fabrics. An alternative coating material is needed because various substances associated with PVC, such as plasticizers and other additives, have been identified as posing risks to people and the environment. A more sustainable material solution is also demanded by the medical device industry.

[0006] SUMMARY

[0007] In accordance with one or more aspects, a coated fabric for use in healthcare products is disclosed. The coated fabric may comprise a nonwoven fabric and a thermoplastic elastomer coating on the non woven fabric.

[0008] In some aspects, the nonwoven fabric may be a nonwoven polypropylene fabric. In other aspects, the nonwoven fabric may be a non woven polyester fabric. In some aspects, the nonwoven fabric may be a spunbond or spunlace fabric. In some aspects, the nonwoven fabric may have a weight of about 0.8 to 2 oz. / sq. yd.

[0009] In some aspects, the thermoplastic elastomer may comprise a styrenic block copolymer compound and / or a polyolefin blend. For example, the thermoplastic elastomer may comprise styrene-ethylene-butylene-styrene (SEBS) or styrene-ethylene-propylene-styrene (SEPS).

[0010] In some aspects, the thermoplastic elastomer may have a shore A hardness of about 60 to 95. In some aspects, the thermoplastic elastomer may be radio frequency (RF) weldable.

[0011] In some aspects, the thermoplastic elastomer may comprise a thermoplastic polyester elastomer.

[0012] In some aspects, a total thickness of the coated fabric may be from about 10 to about 18 mil. A total weight of the coated fabric may be about 7 to about 12 oz. / sq. yd. In some aspects, the coated fabric may be characterized by a 1” strip tensile strength in the fill or warp direction of about 12 lbs or greater. In some aspects, the coated fabric may be characterized by a grab tensile strength of greater than about 40 lbs.

[0013] In some aspects, the coated fabric is substantially free of polyvinyl chloride (PVC).

[0014] In some aspects, the thermoplastic elastomer coating and the nonwoven fabric may be miscible and can be melt blended to form a homogeneous compound for recycling.

[0015] In accordance with one or more aspects, a method of making a coated fabric is disclosed. The method may comprise steps of providing a nonwoven fabric and extrusion coating a melted thermoplastic elastomer on the non woven fabric.

[0016] In some aspects, the nonwoven fabric may comprise a nonwoven polypropylene fabric or a non woven polyester fabric. In some aspects, the melted thermoplastic elastomer may comprise styrene-ethylene-butylene-styrene (SEBS) or styrene-ethylene-propylene-styrene (SEPS). In other aspects, the melted thermoplastic elastomer may comprise thermoplastic polyester elastomer.

[0017] In accordance with one or more aspects, an inflatable bladder formed from any of the coated fabrics described herein is disclosed.

[0018] In some aspects, the inflatable bladder is associated with a medical-grade application. For example, the inflatable bladder may be a blood pressure cuff or a deep vein thrombosis (DVT) sleeve.

[0019] In accordance with one or more aspects, a method of making an inflatable bladder is disclosed. The method may involve steps of providing any of the coated fabrics described herein and welding the coated fabric together on an elastomeric side of the coated fabric to form the inflatable bladder.

[0020] In some aspects, welding the coated fabric may involve at least one of: radio frequency (RF) welding, ultrasonic welding and heat compression.

[0021] In accordance with one or more aspects, a blood pressure cuff comprising any of the coated fabrics described herein is disclosed.

[0022] In accordance with one or more aspects, a DVT sleeve comprising any of the coated fabrics described herein is disclosed.

[0023] In accordance with one or more aspects, a method of recycling a coated fabric is disclosed. The method may comprise steps of grinding any of the coated fabrics described herein and melt blending the ground coated fabric to form a homogeneous compound. In some aspects, the coated fabric is associated with a medical device. For example, the coated fabric may be associated with a blood pressure cuff or a deep vein thrombosis (DVT) sleeve.

[0024] In some aspects, the method may further comprise using the homogeneous compound as a thermoplastic elastomer feedstock. In some aspects, the method may further comprise using the homogeneous compound as a filler for impact modification of polypropylene products.

[0025] The disclosure contemplates all combinations of any one or more of the foregoing aspects and / or embodiments, as well as combinations with any one or more of the embodiments set forth in the detailed description and any accompanying examples.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0028] FIG. 1 is a schematic drawing of a coated fabric, according to one or more embodiments;

[0029] FIG. 2 is a schematic drawing of an inflatable bladder and associated medical device, according to one or more embodiments; and

[0030] FIGS. 3-4 presents data discussed in an accompanying Example.

[0031] DETAILED DESCRIPTION

[0032] In accordance with one or more embodiments, coated fabrics are disclosed for a variety of medical applications. Beneficially, the coated fabrics may be substantially free of PVC and may meet certain mechanical and / or material property requirements as specified by the medical device industry. The disclosed coated fabrics may find particular utility in making inflatable bladders for healthcare products such as blood pressure cuffs and deep vein thrombosis (DVT) sleeves.

[0033] In accordance with one or more embodiments, the coated fabrics may generally include a nonwoven fabric substrate and a thermoplastic elastomer coating. With reference to FIG. 1, coated fabric 100 includes thermoplastic elastomer coating 120 applied to nonwoven fabric substrate 110. In accordance with one or more embodiments, two and three-ply structures are both generally contemplated.

[0034] A wide range of mechanical performance and comfortableness can be achieved by combining thermoplastic elastomer at different hardness with nonwoven fabrics at different weight.

[0035] In accordance with one or more embodiments, various nonwoven fabrics having desired physical properties as described herein may be used as substrate. In some non-limiting embodiments, the nonwoven fabric may be a nonwoven polypropylene fabric. In at least some embodiments, the nonwoven polypropylene fabric may be a spunbond fabric. In other nonlimiting embodiments, the nonwoven fabric may be a nonwoven polyester fabric. In at least some embodiments, the nonwoven polyester fabric may be a spunlace fabric.

[0036] In accordance with one or more embodiments, a material, weight and / or thickness of the nonwoven fabric substrate may be selected to impact one or more properties of the overall coated fabric. A specific substrate may be selected in conjunction with engineering of the associated thermoplastic elastomer coating to impart various desired parameters to the resulting coated fabric. Such properties may include overall weight, thickness, hardness, strip tensile strength, strip tensile elongation, grab tensile strength, grab tensile elongation, and / or burst pressure. In some non-limiting embodiments, for example, the nonwoven fabric substrate may have a weight of about 0.8 to 2 oz / sq. yd.

[0037] In accordance with one or more embodiments, various thermoplastic elastomer coatings having desired physical properties as described herein may be used. The composition and / or formulation of the thermoplastic elastomer coating may be optimized to impact one or more of the properties noted above in order to meet various requirements of an intended application. For example, in some embodiments the thermoplastic elastomer may be characterized by a shore A hardness of about 60 to about 95. In some embodiments the thermoplastic elastomer may be characterized by a shore D hardness of about 30 to about 45. In some non-limiting embodiments, the thermoplastic elastomer may include styrenic block copolymer, polyester based elastomer, and / or polyolefin blends. In at least one embodiment, the thermoplastic elastomer may include a blend of a blend of a polypropylene elastomer with ethylene- vinyl acetate (EVA). In some specific non-limiting embodiments, the thermoplastic elastomer may include styrene-ethylene- butylene-styrene (SEBS) and / or styrene-ethylene-propylene-styrene (SEPS). In some non- limiting embodiments, the thermoplastic elastomer may include thermoplastic vulcanizate (TPV) and / or thermoplastic olefin (TPO). The thermoplastic elastomer may include a polyolefin blend.

[0038] In accordance with one or more embodiments, the two layered structure of the coated fabric may be made by extrusion coating. A melted thermoplastic elastomer may generally be extruded onto the nonwoven fabric substrate. Various methods of extrusion coating will be recognized by those of skill in the relevant art. In some embodiments, thermoplastic elastomer resins may be fed into a single screw extruder. The melt sheet may then be extruded out of a film die and contacted with nonwoven fabric at the nip roll to be bonded together. The temperature profile associated with various barrel zones may vary, as well as the temperature associated with any die and / or adapters. Head pressure and / or barrel speed may also be varied. Roll stack temperature and / or speed may be varied as well.

[0039] In accordance with one or more embodiments, the two layered structure of the coated fabric may be made by lamination.

[0040] In some non-limiting embodiments, the coating may be applied at a weight of about 7 to about 10 oz / sq. yd.

[0041] In accordance with one or more embodiments, the resulting coated fabric may have various desirable material and / or mechanical properties such as those which meet certain specifications required by the medical device industry. For example, the coated fabric may have a total thickness of about 10 to about 18 mil and a total weight of about 7 to about 12 oz / sq. yd. The coated fabric may be characterized by a strip tensile elongation in the fill direction of greater than about 14%. The coated fabric may be characterized by a grab tensile strength of greater than about 60 lbs.

[0042] In accordance with one or more embodiments, the coated fabric may be substantially free of polyvinyl chloride (PVC).

[0043] In accordance with one or more embodiments, the coated fabric may be weldable. Specifically, the coated fabric may be weldable via radio frequency (RF) welding, ultrasonic welding and / or heat compression. Welding may generally occur on the elastomer side of the coated fabric. In at least some embodiments, an associated weld strength may be at least about 20 Ib / inch.

[0044] In accordance with one or more embodiments, the coated fabric may be used to make various products for the healthcare industry. For example, the disclosed coated fabrics may find utility as pillow ticking fabric. In some embodiments, a product may be a medical device as described herein.

[0045] In accordance with one or more embodiments, the coated fabric may be used to make an inflatable bladder. The inflatable bladder may be associated with a medical-grade application. In at least some non-limiting embodiments, the inflatable bladder may be characterized by a hydrostatic mullen burst pressure of at least about 50 psi.

[0046] With reference to FIG. 2, coated fabric 200 may be used to manufacture inflatable bladder 230 which is integrated into medical device 240. Medical device 240 may be a blood pressure cuff or a deep vein thrombosis (DVT) sleeve in certain non-limiting embodiments. Other inflatable applications are envisioned.

[0047] In accordance with one or more embodiments, the coated fabrics may be recyclable at end of product life. Spent coated fabric may be shredded and melt to form a homogeneous blend as a thermoplastic elastomer feedstock or for use as a filler. The thermoplastic elastomer and nonwoven fabric substrate may be miscible and can be melt blended to form a homogeneous compound for recycling.

[0048] Glass transition temperature (Tg) values may generally be one parameter which may inform compatibility with respect to any recycled composite material. Different polymer materials typically have different Tg values. Similar materials may have similar Tg values. Upon melt mixing, there will generally be only a single Tg value for a miscible system. If immiscible, the mixed compound will show more than one Tg value on a differential scanning calorimetry (DSC) curve. Thus, uniform Tg value and / or SEM morphology of the composite material may be indicative of compatibility. For example, when spunbond polypropylene is the nonwoven fabric substrate, miscible coating resins may include styrenic block copolymer and polyolefin based elastomer. Likewise, when the nonwoven fabric substrate is polyester spunlace, the coating resin may be thermoplastic polyester elastomer for miscibility. The resulting recycled materials can be used as feedstock for thermoplastic elastomer, and a filler as impact modifier for polypropylene or polyester products. More specifically, a SEBS and PP blend can be used as an impact modifier for polypropylene material. A polyester elastomer and polyester spunlace blend can be fed to the typical polyethylene terephthalate (PET) recycle stream. The function and advantages of these and other embodiments can be better understood from the following example. This example is intended to be illustrative in nature and is not considered to be limiting the scope of the invention.

[0049] EXAMPLE

[0050] Various coated fabrics in accordance with one or more aspects described above were made and select material properties thereof were tested against a control fabric to assess their suitability for use in medical-grade applications.

[0051] The control fabric was a medical grade two-ply PVC coated polyester spunlace fabric commercially available from Applicant. The test samples varied in terms of the substrate fabric weight and the amount of applied coating (see varying total weight and total thickness of the coated fabric samples).

[0052] An extrusion coating process was used to make two-layer structured samples. Thermoplastic elastomer resins were fed into a single screw extruder. The melt sheet was extruded out of a film die and contacted with nonwoven fabric at the nip roll to bond together. The extruded samples were then die cut into certain dimensions for further evaluations of mechanical performance.

[0053] FIGS. 3-4 summarize the associated data at Tables 1 and 2.

[0054] The polymer blends referenced in the data of Table 2 were as follows:

[0055] Table 3:

[0056] Due to the lower specific gravity of the coating materials used in these examples, the sample coated fabrics generally have lower weight at same thickness, or same weight at thicker thickness.

[0057] Some of the test samples clearly did not meet required specifications (control) which illustrates the criticality of the presently disclosed combinations of nonwoven fabric and thermoplastic elastomer coating. For example, Samples 2, 4 and 5 illustrate that with a too low fabric weight or elastomer hardness, one does not get the desired tensile strength or mullen burst pressure.

[0058] Sample 8 was a soft version which had relatively low value in 1-in strip tensile strength and a burst pressure below 44 psi. The grab tensile strength and trapezoid tear were comparable to control. Sample 13 is thicker and heavier than sample 11 which can also contribute to higher strength. Sample 11 was a stiff version which was intended to meet all properties of control, with increased fabric weight and coating material hardness. Sample 11 appeared to be most comparable to the control.

[0059] Overall, it was illustrated that a wide range of mechanical and performance characteristics can be achieved by combining different thermoplastic elastomer at varying weights and thicknesses with nonwoven fabrics at different weight. Depending on an intended application, e.g. disposable products, materials associated with different performance values may be selected. Beneficially, the coating material is versatile and can be blended with many other materials.

[0060] Weldability

[0061] The final product needs to be welded on the coating material side to form an air inflatable bladder. To evaluate the weldability, two pieces of coated fabrics would be welded together on elastomer sides with different welding technologies, such as RF welding and Ultrasonic welding. The adhesion between fabrics and coating material would be measured according to ASTM D751. It is anticipated that at least some of the Samples of this Example would meet weldability requirements for inflatable bladders. It has been demonstrated that various materials disclosed herein are weldable by ultrasonic welding.

[0062] Recyclability

[0063] At the end of the product life, coated fabrics in accordance with various embodiments can be reground and blended, such as with addition of SEBS, TPV, PP to tailor the performance for recycle and re-use.

[0064] DSC and SEM would be used to characterize the coated fabrics recyclability as a single material product. The coated fabrics would be shredded into small pieces that can be fed into a twin screw extruder or internal mixer, such as brabender mixer. Under heat and shear, the fabrics and coating material melt and form a homogeneous compound. DSC results would show a single Tg from the compound as indicative of a miscible system. SEM pictures would confirm the homogeneous mixing of fabrics and coating materials. It is anticipated that at least some of the Samples of this Example would meet desired recyclability requirements. Associated Tg data measured by DSC is summarized in Table 4 below for individual components and the total mix (coating resins and non woven fabrics together).

[0065] Table 4: Tg measured by DSC It was demonstrated that the disclosed material systems are versatile and can be recycled and blended with various materials and at different ratio to reuse and repurpose the materials. Beneficially, there is no need to separate the coating from substrate for recycling.

[0066] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of’ and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0067] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0068] Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and / or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.

[0069] What is claimed is:

Claims

CLAIMS1. A coated fabric for use in healthcare products, comprising: a nonwoven fabric; and a thermoplastic elastomer coating on the nonwoven fabric.

2. The coated fabric of claim 1, wherein the nonwoven fabric is a nonwoven polypropylene fabric.

3. The coated fabric of claim 1, wherein the nonwoven fabric is a nonwoven polyester fabric.

4. The coated fabric of claim 1, wherein the nonwoven fabric is a spunbond or spunlace fabric.

5. The coated fabric of claim 4, wherein the nonwoven fabric has a weight of about 0.8 to 2 oz. / sq. yd.

6. The coated fabric of claim 1, wherein the thermoplastic elastomer comprises a styrenic block copolymer compound and / or a polyolefin blend.

7. The coated fabric of claim 6, wherein the thermoplastic elastomer comprises styrene- ethylene-butylene-styrene (SEBS) or styrene-ethylene-propylene-styrene (SEPS).

8. The coated fabric of claim 1, wherein the thermoplastic elastomer has a shore A hardness of about 60 to 95.

9. The coated fabric of claim 1, wherein the thermoplastic elastomer is radio frequency (RF) weldable.

10. The coated fabric of claim 1, wherein the thermoplastic elastomer comprises a thermoplastic polyester elastomer.

11. The coated fabric of claim 1, wherein a total thickness of the coated fabric is about 10 to about 18 mil.

12. The coated fabric of claim 1, wherein a total weight of the coated fabric is about 7 to about 12 oz. / sq. yd.

13. The coated fabric of claim 1 characterized by a 1” strip tensile strength in the fill or warp direction of about 12 lbs or greater.

14. The coated fabric of claim 1, characterized by a grab tensile strength of greater than about 40 lbs.

15. The coated fabric of claim 1, wherein the coated fabric is substantially free of polyvinyl chloride (PVC).

16. The coated fabric of claim 1, wherein the thermoplastic elastomer coating and the nonwoven fabric are miscible and can be melt blended to form a homogeneous compound for recycling.

17. A method of making a coated fabric, comprising: providing a nonwoven fabric; and extrusion coating a melted thermoplastic elastomer on the nonwoven fabric.

18. The method of claim 17, wherein the non woven fabric comprises a nonwoven polypropylene fabric or a nonwoven polyester fabric.

19. The method of claim 17, wherein the melted thermoplastic elastomer comprises styrene- ethylene-butylene-styrene (SEBS) or styrene-ethylene-propylene-styrene (SEPS).

20. The method of claim 17, wherein the melted thermoplastic elastomer comprises thermoplastic polyester elastomer.

21. An inflatable bladder formed from the coated fabric of any of claims 1-16.

22. The inflatable bladder of claim 21, wherein the inflatable bladder is associated with a medical-grade application.

23. The inflatable bladder of claim 21, wherein the inflatable bladder is a blood pressure cuff or a deep vein thrombosis (DVT) sleeve.

24. A method of making an inflatable bladder, comprising: providing the coated fabric of any of claims 1-16; and welding the coated fabric together on an elastomeric side of the coated fabric to form the inflatable bladder.

25. The method of claim 24, wherein welding the coated fabric involves at least one of: radio frequency (RF) welding, ultrasonic welding and heat compression.

26. A blood pressure cuff comprising the coated fabric of any of claims 1-16.

27. A DVT sleeve comprising the coated fabric of any of claims 1-16.

28. A method of recycling a coated fabric, comprising: grinding the coated fabric of any of claims 1-16; and melt blending the ground coated fabric to form a homogeneous compound.

29. The method of claim 28, wherein the coated fabric is associated with a medical device.

30. The method of claim 29, wherein the coated fabric is associated with a blood pressure cuff or a deep vein thrombosis (DVT) sleeve.

31. The method of claim 28, further comprising using the homogeneous compound as a thermoplastic elastomer feedstock.

32. The method of claim 28, further comprising using the homogeneous compound as a filler for impact modification of polypropylene products.

Images