Thin wall polyether block amide membrane tubing and module

Abstract

Composite polyether block amide (PEBA) copolymer tubes incorporate an ultra-thin PEBA layer that enables rapid moisture transfer and exchange through the tube. A composite PEBA film may include a porous scaffold support and may be formed or incorporated into the composite PEBA tube. A porous scaffold support may be coated or imbibed with PEBA to form a composite PEBA film. A composite PEBA film may be wrapped on a mandrel or over a porous scaffold support to form a composite PEBA tube. A film layer may be applied over a wrapped composite PEBA film to secure the layers together. The film layer by applied by dipping, spraying or painting.

Claims

1. An ultra-thin composite polyether block amides (PEBA) tube comprising: a) a composite PEBA film comprising: i) a porous scaffold support; and ii) a PEBA copolymer attached to the porous scaffold support; iii) a thickness of no more than 50 μm; b) an overlap area of the composite PEBA film that is fused to form said PEBA tube; c) an outside surface; d) an inside surface; e) a film layer configured on at least one of the outside surface or inside surface of the composite PEBA tube; wherein the film layer comprises a continuous polymer layer; f) an inlet; g) an outlet; and h) a length from said inlet to said outlet.

2. The ultra-thin composite PEBA tube of claim 1, wherein the composite PEBA film thickness is no more than 25 μm.

3. The ultra-thin composite PEBA tube of claim 1 wherein the composite PEBA film thickness is no more than 10 μm.

4. The ultra-thin composite PEBA tube of claim 1, wherein the composite PEBA film thickness is no more than 5 μm.

5. The ultra-thin composite PEBA tube of claim 1, wherein the overlap area is no more than 30% of an outside surface area of the composite PEBA tube.

6. The ultra-thin composite PEBA tube of claim 1, wherein the overlap area is no more than 20% of an outside surface area of the composite PEBA tube.

7. The ultra-thin composite PEBA tube of claim 1, wherein the overlap area is no more than 10% of an outside surface area of the composite PEBA tube.

8. The ultra-thin composite PEBA tube of claim 1, wherein the composite PEBA film is spirally wrapped to form said composite PEBA tube.

9. The ultra-thin composite PEBA tube of claim 1, wherein the composite PEBA film is longitudinally wrapped to form said composite PEBA tube.

10. The ultra-thin composite PEBA tube of claim 1, wherein the porous scaffold support is expanded polytetrafluoroethylene membrane.

11. The ultra-thin composite PEBA tube of claim 1, wherein the porous scaffold support comprises a porous polyethylene membrane.

12. The ultra-thin composite PEBA tube of claim 1, wherein the porous scaffold support comprises a porous polypropylene membrane.

13. The ultra-thin composite PEBA tube of claim 1, further comprising a biocide to prevent mold formation.

14. The ultra-thin composite PEBA tube of claim 1, wherein the film layer comprises PEBA.

15. The ultra-thin composite PEBA tube of claim 1, wherein the film layer is configured on the outside surface of the composite PEBA tube.

16. A pervaporation module comprising: a) an ultra-thin composite Polyether block amides (PEBA) tube comprising: i) composite PEBA film comprising: a porous scaffold support; and a PEBA copolymer attached to the porous scaffold support; a thickness of no more than 50 μm; ii) an overlap area of the composite PEBA film that is fused to form said PEBA tube; iii) an outside surface; iv) an inside surface; v) a film layer configured on at least one of the outside surface or inside surface of the composite PEBA tube; wherein the film layer comprises a continuous polymer layer; vi) an inlet; vii) an outlet; b) an inlet tube sheet sealed to the inlet of the composite PEBA tube; c) an outlet tube sheet sealed to the outlet of the composite PEBA tube; d) a flow of water through the composite PEBA tube from the inlet tube sheet to the outlet tube sheet; e) a flow of fluid over the ultra-thin composite PEBA tube; wherein water vapor passes through the composite PEBA tube and into the flow of fluid thereover to increase the relative humidity of the flow of fluid.

17. The pervaporation module of claim 16, comprising a plurality of composite PEBA tubes coupled to the inlet and outlet tube sheets.

18. The pervaporation module of claim 16, wherein the composite PEBA film comprises a biocide.

19. The pervaporation module of claim 16, further comprising a tube support configured around the ultra-thin composite PEBA tube.

20. The pervaporation module of claim 16, wherein the film layer comprises PEBA.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

(1) The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description explain the principles of the invention.

(2) FIG. 1 shows cross-sectional view of an exemplary porous scaffold support having a porous structure and pores therein, wherein the PEBA substantially fills the pores of the scaffold support.

(3) FIG. 2 show a cross-sectional view of an exemplary ultra-thin composite PEBA film having a layer of PEBA on either side of the porous scaffold support.

(4) FIG. 3 shows cross-sectional view of an exemplary ultra-thin composite PEBA film formed by imbibing PEBA copolymer into a porous scaffold support using solution casting process, wherein the PEBA substantially fills the pores of the scaffold support.

(5) FIG. 4 shows a cross-sectional view of a composite PEBA film having a butter-coat layer of PEBA on the surface of a porous scaffold support.

(6) FIG. 5 shows a cross-sectional view of an overlap region of a composite PEBA tube having two layers of composite PEBA film.

(7) FIG. 6 shows a perspective view of an exemplary PEBA tube that is a spirally wrapped PEBA tube comprising a spirally wrapped composite PEBA film having overlap areas that are attached form a spiral wrapped PEBA tube.

(8) FIG. 7 shows a perspective view of an exemplary PEBA tube that is a longitudinally wrapped PEBA tube comprising a spirally wrapped composite PEBA film having overlap areas that are attached form said cigarette wrapped PEBA tube.

(9) FIG. 8 shows pervaporation module compromising a plurality of composite PEBA pervaporation tubes.

(10) FIG. 9 shows a cross sectional view of an exemplary composite PEBA tube having a PEBA polymer layer on the outside surface of the porous scaffold support and a film layer configured over the PEBA layer.

(11) FIG. 10 shows a cross sectional view of an exemplary composite PEBA tube having a PEBA polymer layer on the inside surface of the porous scaffold support and a film layer configured over the PEBA layer.

(12) FIG. 11 shows a cross sectional view of an exemplary composite PEBA tube having a PEBA polymer layer on both the inside and the outside surface of the porous scaffold support and a film layer over both PEBA layers.

(13) Corresponding reference characters indicate corresponding parts throughout the several views of the figures. The figures represent an illustration of some of the embodiments of the present invention and are not to be construed as limiting the scope of the invention in any manner. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

(14) As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

(15) Certain exemplary embodiments of the present invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications, combinations and improvements of the described embodiments, will occur to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

(16) As shown in FIG. 1, an exemplary an ultra-thin porous scaffold support 10 is a thin sheet or porous membrane having a top side 12, bottom side 14 and pores 16 therethrough from the top to the bottom. An exemplary porous scaffold support is a planar sheet of material having a thickness of less than 50 μm, and preferably less than 25 μm, as described herein.

(17) As shown in FIG. 2, an exemplary ultra-thin composite PEBA film 40 has PEBA polymer 30 imbibed into the pores 16 of the porous scaffold support 10. This may be accomplished by melt laminating and pressing PEBA resin into the pores of the porous scaffold material, or through solution casting or imbibing. The composite PEBA film has a top surface 42 and a bottom surface 44 and a thickness 43 therebetween. The thickness of the composite PEBA film is preferably less than 50 μm, more preferably less than 25 μm and even more preferably less than 10 μm or 5 μm. There is a PEBA butter coat layer 48, 48′ extending across the top side 12 and bottom side 14 of the porous scaffold support, respectively. A butter coat layer is a think layer of the PEBA copolymer extending over the porous scaffold support. A butter-coat layer may be on one or both surfaces of the composite PEBA film.

(18) As shown in FIG. 3, an exemplary ultra-thin composite PEBA film 40 has PEBA polymer 30 imbibed into the pores 16 of the porous scaffold support 10. This may be accomplished by melt laminating and pressing PEBA resin into the pores of the porous scaffold material, or through solution casting or imbibing. In this embodiment, there is no butter-coat layer.

(19) As shown in FIG. 4, a composite PEBA film 40 has a butter-coat layer 48 of PEBA copolymer 30 on the top side 12 or surface of a porous scaffold support 10. This thin composite PEBA film may be used in a flat sheet in a pervaporation module or in a humidification vent application to allow humidity to pass therethrough but to exclude other contaminants or particles from entering an enclosure. As shown in FIG. 4, a flat sheet of a composite PEBA film may be made for plate and frame configurations. IT may be preferable to use this single sided butter-coat layer composite PEBA film for these applications as the PEBA may be very thin, such as less than 10 μm or even more preferably less than 5 μm.

(20) FIG. 5 shows a cross-sectional view of an overlap area 58 of a composite PEBA tube having two layers of composite PEBA film 40 and 40′. The overlap area is fused together along the fused interface 20 which may include PEBA from one butter-coat layer melting into the PEBA of the adjacent butter-coat layer. Note that PEBA from one composite PEBA film may melt into the pores or other PEBA polymer in an adjacent composite PEBA film. The thickness 23 of the overlap area 58 or layers is greater than the thickness of a single composite PEBA film, and therefore reducing the overlap area is important to increase throughput and permeation rates through the tube.

(21) As shown in FIG. 6, a composite PEBA tube 50 is a spirally wrapped PEBA tube 60 having a composite PEBA film 40 spirally wrapped to form the outer wall 52 and conduit 51 of the spirally wrapped PEBA tube. The spirally wrapped PEBA tube has overlap areas 58 that spiral around the tube. The composite PEBA film that may be attached or bonded to each other to form bonded area 59. The bonding may be formed by fusing the layers together, wherein the PEBA from one layer is intermingled with the PEBA of the second, or overlapped layer. This bonding may be accomplished through heat, such as by fusing or by the addition of a solvent that enables intermingling of the polymers. The composite PEBA tube 50 has a length 55 from an inlet 54 to an outlet 56 and a length axis 57 extending along the center of the tube. A first layer of the composite PEBA film is bonded to the PEBA polymer of a second layer of the composite PEBA film to form the bonded area. As described herein, the overlap width may be fraction of the tape width, such as no more than about 30% of the tape width, no more than about 25% of the tape width, no more than about 20% of the tape width, no more than about 10% of the tape width, or even no more than about 5% of the tape width to provide a high percentage of the spiral wrapped tube that is only a single layer, thereby increase the rate of transfer of ions through the tube and also reduce the total usage of film thus lower cost.

(22) As shown in FIG. 7, a composite PEBA tube 50 is a longitudinally wrapped PEBA tube 70 having a composite PEBA film 40 longitudinally wrapped to form the longitudinally wrapped PEBA tube and tube conduit 51. The longitudinally wrapped PEBA tube has an overlap area 58 of the composite PEBA film that extends down along the length 55 or length axis 57 of the tube. The length extends from the inlet 54 to the outlet 56. The overlap area may be attached or bonded to each other to form a fused area 59 wherein the layers of the composite PEBA film are bonded or fused together, wherein the PEBA from one layer is intermingled with the PEBA of a second layer through melting or solvent bonding. The bonding may be formed by fusing the layers together, wherein the PEBA from one layer is intermingled with the PEBA of the second, or overlapped layer. This bonding may be accomplished through heat, such as by fusing or by the addition of a solvent that enables intermingling of the polymers. An exemplary composite PEBA pervaporation tube comprises a longitudinally wrapped, or “cigarette wrapped” composite PEBA film sheet to form a longitudinal wrapped PEBA pervaporation tube. The composite PEBA film is wrapped around the longitudinal axis of the tube. In this embodiment the length of the tube is the width of the composite PEBA film, and the wrap angle is perpendicular to the longitudinal axis. The longitudinal wrapped composite PEBA film has an overlap area having an overlap width. Again, the overlap width may be no more than about 30% of the tape width, no more than about 25% of the tape width, no more than about 20% of the tape width, no more than about 10% of the tape width, or even no more than about 5% of the tape width to provide a high percentage of the spiral wrapped tube that is only a single layer, thereby increase the rate of permeation and transfer of ions through the tube.

(23) FIG. 8 shows a pervaporation module 80 comprises a plurality of PEBA pervaporation tubes 82 that are composite PEBA pervaporation tubes 84, as described herein 32.

(24) Each of the tubes is coupled to an inlet tube sheet 85 and outlet tube sheet 89. A flow of water flows through the plurality of tubes from the inlet 54 to the outlet 56 of the tube. An airflow 87 passes over the tubes to pull away moisture. The inlet relative humidity 86 may be much lower than the outlet relative humidity 88. Each of the composite PEBA tubes may further comprise a tube support 90, which is an additional support structure or tube that extends around the composite PEBA tubes to prevent expansion of the composite PEBA tubes under pressure. The water flowing through the tubes may be pressurized to increase permeation therethrough and a tube support may prevent diameter creep or swelling. A tube support may be a net or screen that is resistant to radial forces that would increase the diameter and may be made of rigid polymer material and/or a metal, such as a porous metal tube including, but not limited to a, perforated metal tube or woven metal tube.

(25) As shown in FIG. 9, an exemplary composite PEBA tube 50 has a PEBA polymer layer 32 on the outside surface 64 of the composite tube comprising a porous scaffold support 10. The composite PEBA tube has a film layer 100 configured over the wrapped composite PEBA film 40 to provide additional support and prevent leakage. An exemplary film layer may be thin, having a thickness no more than about 15 μm more than about 10 μm, no more than about 5 μm, no more than about 2 μm, no more than about 1 μm and any range between and including the thickness values provided. When the film layer is or comprises PEBA, the thinner the better for moisture transfer rates.

(26) As shown in FIG. 10 an exemplary composite PEBA tube 50 has a PEBA polymer layer 32 on the inside surface 62 of the composite tube comprising a porous scaffold support 10. The composite PEBA tube has a film layer 100 configured over the wrapped composite PEBA film 40 to provide additional support and prevent leakage.

(27) As shown in FIG. 11, an exemplary composite PEBA tube 50 has a PEBA polymer layer 32 on both the inside surface 62 and the outside surface 64 of the composite tube comprising a porous scaffold support 10. The composite PEBA tube has a film layer 100, 100′ configured over the wrapped composite PEBA film 40 on the outside surface and inside surface, respectively, to provide additional support and prevent leakage.

(28) It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and/or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.