FOAMED SKIN COMPATIBLE SILICONE COMPOSITION

Abstract

A skin compatible component attachable to mammalian skin. The component is formed as a foamed silicone matrix comprising a polyorganosiloxane derived silicone polymer and moisture control particulate distributed within the polymer network being configured to absorb moisture from the skin. The foamed skin compatible component may be utilised as an ostomy wafer or flange to secure an ostomy appliance to the skin and in particular peristomal skin.

Claims

1. A skin compatible component attachable to mammalian skin comprising: a silicone polymer network derived from the addition curing of a first part including a vinyl functionalised siloxane polymer and a second part including a silicon hydride containing crosslinker, in the presence of a metal catalyst; and a superabsorbent particulate distributed within the polymer network configured to absorb moisture from the skin; wherein the silicone polymer network comprises a foamed structure.

2. The component as claimed in claim 1 wherein the superabsorbent particulate has an average particle size less than 150 μm.

3. The component as claimed in claim 1, wherein the superabsorbent particulate comprises an average particle size in the range 10 to 40 μm, 15 to 35 um or 20 to 30 μm.

4. The component as claimed in claim 1 wherein the superabsorbent particulate is distributed within the polymer network at a concentration in the range 5 to 45 wt %, 10 to 40 wt %, 15 to 35 wt % or 20 to 30 wt %.

5. The component as claimed in claim 1 wherein the superabsorbent particulate comprises any one or a combination of the set of: a naturally occurring hydrocolloid; a semi-synthetic hydrocolloid; or a synthetic hydrocolloid.

6. The component as claimed in claim 1, wherein the superabsorbent particulate comprises any one or a combination of: a polysaccharide; a cellulose; hydroxyethylcellulose; carboxymethylcellulose; or hydroxypropylcellulose.

7. The component as claimed in claim 1 wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

8. The component as claimed in claim 1, wherein the superabsorbent particulate comprises sodium polyacrylate.

9. The component as claimed in claim 1 wherein an organosilicone resin is included in the first or second part prior to addition curing.

10. The component as claimed in claim 9 wherein the organosilicone resin is an MQ resin.

11. The component as claimed in claim 1 wherein a cohesive strengthening agent is including in the first part or the second part prior to addition curing.

12. The component as claimed in claim 11 wherein the cohesive strengthening agent comprises any one or a combination of the set of: fumed silica, fumed alumina, colloidal silica, nanoclays, silicates, silane treated organic polymers, polymeric metal oxides, and non-polymeric metal oxides.

13. The component as claimed in claim 1 comprising a foaming agent.

14. The component as claimed in claim 13 wherein the foaming agent comprises any one or a combination of the following set of: water; a bicarbonate ion; a bicarbonate salt; a metal bicarbonate; azodicarbonamide; isocyanate; pentane; isopentane; cyclopentane; a fluorocarbon; a hydrofluorocarbon; a chlorinated fluorocarbon; a hydrocarbon; or carbon dioxide.

15. The component as claimed in claim 1 further comprising a reaction product, reactants or derivatives of an organic acid and an organic base.

16. The component as claimed in claim 1 wherein the foaming agent comprises an organic acid being any one or a combination of: a carboxylic acid, a sulfonic acid, lactic acid, acetic acid, foaming acid, citric acid, acetic acid tartaric acid, L-tartaric acid, oxalic acid uric acid, a compound comprising a thiol group, an enol group or a phenol group; and/or wherein the foaming agent comprises an organic base being any one or a combination of: anolcoxide, an amidines, an amine, a phosphine, a sulphate, ammonia, perodene, or acetone.

17. The component as claimed in claim 13 wherein the foaming agent comprises sodium bicarbonate.

18. The component as claimed in claim 17 wherein the foaming agent further comprises water.

19. The component as claimed in claim 18 wherein the foaming agent further comprises an organic acid and an organic base.

20. An ostomy coupling comprising: a moisture and gas permeable support layer; an ostomy appliance or ostomy appliance connection provided at a first surface of the support layer; and a skin compatible component as claimed in claim 1 attached to a second surface of the support layer.

21. The coupling as claimed in claim 20 wherein the support layer comprises polyurethane.

22. The coupling as claimed in claim 20 wherein the support layer comprises any one or a combination of the set of: a breathable silicone layer; a polyethylene block amide polymer; a polytetrafluoroethylene polymer; an acrylic latex polymer; or a polyolefin based layer.

23. The coupling as claimed in claim 20 wherein the ostomy appliance comprises a bag or pouch attached to the support layer directly or via an intermediate layer.

24. The coupling as claimed in claim 23 wherein the intermediate layer comprises polyethylene.

25. The coupling as claimed in claim 23 wherein the intermediate layer comprises any one or a combination of the set of: a polyester disc; a polyester gauze; a polyethylene gauze; a polypropylene disc; or a polypropylene gauze.

26. The coupling as claimed in claim 20 wherein the ostomy appliance connection comprises a first part of a bag or pouch connection assembly in which a second part of the connection assembly is mounted at a bag or pouch, the first part and the second part capable of releasable mating to detachably secure the bag or pouch to the coupling.

27. The coupling as claimed in claim 20 wherein the coupling comprises an opening extending through the support layer and the skin compatible component.

28. The coupling as claimed in claim 20 further comprising an additional skin contact layer positioned at a skin facing side of the skin compatible component, the additional skin contact layer being non-continuous over the skin facing side of the skin compatible component such that areas of the skin facing side of the skin compatible component are not concealed by the silicone adhesive layer, the areas capable of positioning directly adjacent and/or in contact with the skin.

29. The coupling as claimed in claim 28 wherein the additional skin contact layer is formed as lines, dots, flecks or marks on the skin facing side of the skin compatible component.

30. The coupling as claimed in claim 29 wherein the lines, dots, flecks or marks create a pattern on the skin facing surface of the skin compatible component that is substantially uniform across the skin facing surface.

31. The coupling as claimed in claim 28 wherein the additional skin contact layer is formed as lines or ridges extending over a skin facing surface of the skin compatible component.

32. The coupling as claimed in claim 31 wherein the lines or ridges are distributed at the skin facing surface to create geometric shapes.

33. The coupling as claimed in claim 31 wherein the lines or ridges are distributed at the skin facing surface to define concentric circles extending around a central aperture extending through the coupling.

34. A method of manufacturing a skin compatible component attachable to mammalian skin comprising: mixing a first part including a vinyl functionalized siloxane polymer with a second part including a silicon hydride containing crosslinker to form a mix; incorporating within the mix a superabsorbent particulate; incorporating within the mix at least one foaming agent; curing the mix via a metal catalyst; wherein the resulting addition cured silicone polymer network is a foam and the superabsorbent particulate is distributed within the foam.

35. The method as claimed in claim 34 wherein the superabsorbent particulate comprises any one or a combination of the set of: a naturally occurring hydrocolloid; a semi-synthetic hydrocolloid; or a synthetic hydrocolloid.

36. The method as claimed in claim 34 wherein the superabsorbent particulate comprises any one or a combination of: a polysaccharide; a cellulose; hydroxyethylcellulose; carboxymethylcellulose; hydroxypropylcellulose.

37. The method as claimed in claim 34 wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

38. The method as claimed in claim 34 wherein the superabsorbent particulate comprises sodium polyacrylate.

39. The method as claimed in claim 34 wherein the first or second part further comprises a cohesive strengthening agent.

40. The method as claimed in claim 39 wherein the cohesive strengthening agent comprises fumed silica.

41. The method as claimed in claim 34 wherein the superabsorbent particulate is included within the mix at 5 to 45 wt %, 15 to 35 wt % or 20 to 30 wt %.

42. The method as claimed in wherein the superabsorbent particulate comprises sodium polyacrylate.

43. The method as claimed in claim 34 wherein the foaming agent comprises any one or a combination of the following set of: water; a bicarbonate ion; a bicarbonate salt; a metal bicarbonate; azodicarbonamide; isocyanate; pentane; isopentane; cyclopentane; a fluorocarbon; a hydrofluorocarbon; a chlorinated fluorocarbon; a hydrocarbon; or carbon dioxide.

44. The method as claimed in claim 34 further comprising a reaction product, reactants or derivatives of an organic acid and an organic base.

45. The method as claimed in claim 34 wherein the foaming agent comprises an organic acid being any one or a combination of: a carboxylic acid, a sulfonic acid, lactic acid, acetic acid, foaming acid, citric acid, acetic acid tartarc acid, L-tartaric acid, oxalic acid uric acid, a compound comprising a thiol group, an enol group or a phenol group; and/or wherein the foaming agent comprises an organic base being any one or a combination of: anolcoxide, an amidines, an amine, a phosphine, a sulphate, ammonia, perodene, or acetone.

46. The method as claimed in claim 34 wherein the foaming agent comprises sodium bicarbonate.

47. The method as claimed in claim 46 wherein the foaming agent comprises water.

48. The method as claimed in claim 47 wherein the foaming agent comprises an organic acid and an organic base.

49. The method as claimed in claim 48 wherein the foaming agent is included within mix at 1 to 30 wt %.

50. The method as claimed in claim 46 comprising sodium bicarbonate included within the mix in the range 5 to 10 wt % or 10 to 15 wt %.

51. The method as claimed in claim 50 further comprising water included within the mix at 0.5 to 10 wt %, 0.5 to 5 wt % or 2 to 10 wt %.

52. A skin compatible component attachable to mammalian skin manufactured by the method of claim 34.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0058] A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

[0059] FIG. 1 is a plan view of an ostomy appliance coupling according to a specific implementation of the present invention;

[0060] FIG. 2 is a cross sectional view through A-A of the ostomy coupling of FIG. 1;

[0061] FIG. 3 is a plan view of an ostomy appliance coupling according to a further specific implementation of the present invention;

[0062] FIG. 4 is a cross sectional view through B-B of the ostomy coupling of FIG. 3;

[0063] FIG. 5A is a cross section through an ostomy coupling of the type of FIGS. 1 and 2 according to a further embodiment having an additional adhesive layer at the skin contact face of the coupling that is discontinuous over the skin contact face;

[0064] FIG. 5B is a cross section through an ostomy coupling of the type of FIGS. 3 and 4 according to a further embodiment having an additional adhesive layer at the skin contact face of the coupling that is discontinuous over the skin contact face; and

[0065] FIG. 6 is a magnified image of a foamed structure of a silicone material as described and claimed herein.

DETAILED Description OF PREFERRED EMBODIMENT OF THE INVENTION

[0066] A silicone polymer based skin compatible component according to the subject invention is particularly adapted for placement on mammalian skin to have a desired adhesion characteristic so as to remain in secure attachment to the skin (as the skin moves) when worn by a person whilst having the desired release characteristics to allow the component to be removed from the skin. The silicone based component is accordingly a hydrophilic humectant configured to absorb moisture into the silicone matrix without detriment to adhesion, cohesive properties and peel characteristics. The foamed component/material enables transmission of moisture vapour through the body of the matrix so as to allow the skin (in contact with the component) to breathe. Accordingly, the present silicone wafer, due in part, to the composition of the expanded/foamed silicone matrix is advantageous to balance moisture absorption with moisture and water vapour transmission to avoid skin maceration.

[0067] The subject invention is particularly suitable to secure medical appliances or devices to mammalian skin and in particular peri-stomal skin and peristomal skin. Such devices may include but are not limited to catheters, intravenous feeding lines, securement devices, wound dressings, therapeutic devices, drug delivery devices, ostomy appliances and the like.

[0068] The subject invention will now be described with reference to a specific implementation in which the moisture absorbing particulate silicone based matrix forms a component part of an ostomy appliance coupling referred to as a ‘base plate’ of a ‘two-piece’ system. However, the subject invention may be utilised within a ‘one-piece’ ostomy appliance as will be appreciated. Referring to FIGS. 1 and 2, a coupling assembly 100 comprises a moisture and water vapour permeable ‘breathable’ substrate layer 101 having a first surface 101a and a second surface 101b. According to the specific implementation, layer 101 comprises a polyurethane having a moisture vapour transmission rate (MVTR) of greater than 700 g.Math.m.sup.−2.Math.24 h.sup.−1 and preferably a MVTR of 700 to 950 g.Math.m.sup.−2.Math.24 h.sup.−1 using an upright cup method. According to the specific implementation, the polyurethane layer has an MVTR of 875 g.Math.m.sup.−2.Math.24 h.sup.−1 using an upright cup method. A polyethylene disc 105 is secured to substrate first layer 101a via RF or ultrasonic welding or using an adhesive. The polyethylene disc 105 provides a mount for a first part 106 of an ostomy appliance coupling mechanism to releasably engage with a second part of the coupling mechanism provided at an ostomy appliance, in particular an ostomy bag. Coupling first part 106 is preferably formed as an annular flange capable of frictionally integrating and releasably locking with the second part of the coupling mechanism so as to provide a sealed coupling between an ostomy bag (not shown) and the coupling arrangement 100 of FIGS. 1 and 2. According to the specific implementation, the first part 106 of the coupling mechanism (being any form of connection as will be appreciated and recognised by those skilled in the art) is secured to layer 105 via RF or ultrasonic welding. However, according to further implementations layer 105 may be a double sided adhesive tape (annular ring) suitable to bond to surface 101a and component part 106.

[0069] A silicone polymer foam layer 10 is applied to substrate second surface 101b by coating second surface 101b with a homogenous liquid phase non-cured silicone polymer mix that is then cured (i.e., room temperature vulcanised) in position at substrate 101. The silicone polymer layer 102 is coated and protected by a release liner 103. Release liner 103 according to the specific implementation comprises a fluoropolymer treated film. Liner 103 is releasably positioned over the silicone layer 102 and is removed prior to mounting of the coupling assembly 100 onto the skin of a person via mating contact with the silicone polymer layer surface 102b.

[0070] Layers 101, 102 are annular having a generally circular or oval disc shape profile. A through bore 104 extends through layers 101, 102 and is dimensioned to comprise an internal diameter slightly greater than an external diameter of a stoma with layers 101 and 102 having a generally circular outer perimeter 107 so that the present coupling may be regarded as a generally annular disc. Accordingly, coupling assembly 100 is configured for mounting in close fitting and sealing contact with the peristomal skin as is conventional with both one-piece and two-piece stoma appliances.

[0071] According to the specific implementation, polyurethane substrate 101 comprises a layer thickness of 20 μm to 50 μm and the silicone polymer layer 102 comprises a thickness of approximately 400 to 900 μm. Polyethylene disc 105 comprises a thickness of 80 to 150 μm and release liner 103 comprises a thickness in the range 40 to 150 μm.

[0072] FIGS. 2 to 4 illustrate an ostomy appliance coupling according to a second embodiment being a variation of the embodiment described with reference to FIGS. 1 to 2. According to the further embodiment, the breathable polyurethane layer 101, the silicone polymer foam layer 102 and the release liner 103 are as described for the first embodiment. However, in place of the polyethylene disc 105 a weldable non-woven layer 200 is secured to polyurethane first surface 101a. Non-woven layer 200 is also annular and comprises internal and external diameters corresponding to layers 101, 102 so as to form a welded extension of layers 101, 102 in the plane B-B. According to the specific implementation, a thickness of the non-woven layer 200 is 30 to 600 μm. The first part 106 of the appliance coupling mechanism is then welded to non-woven layer 200 via RF or ultrasonic welding.

[0073] A specific embodiment of the polymer layer 102 will now be described by reference to the following examples.

[0074] Polymer layer 102 is formed as a foamed silicone polymer matrix derived from the addition curing of a first part and a second part using a foaming/blowing agent. Supplementary components are included within the first and/or second parts to achieve the desired physical and mechanical characteristics of the resulting silicone network in addition to achieving the desired balance of viscoelastic properties, adhesive tack, adhesive peel, moisture absorption, cohesive strength and water vapour transmission rate (WVTR).

[0075] The two-part components may be cured/vulcanised at ambient temperatures (or elevated temperatures including in the range 30° to 150° . Curing/vulcanisation times may vary depending upon relative concentrations and components within the first and second parts. The base starting materials to create the resulting silicone network are detailed in table 1.

EXAMPLES

[0076]

TABLE-US-00001 TABLE 1 starting materials of liquid phase non-cured mix Concentration Component % w/w Purpose Supplier Silicone Silpuran ® 31-35 Part A silicone + Wacker 2122 part A catalyst Chemie Silicone Silpuran ® 33-37 Part B silicone Wacker 2122 part B cross-linker Chemie Aquakeep ™ 23-27 Moisture control, Sumitomo Sodium moisture Seika Polyacrylate transmission Chemicals through silicone Co., Ltd adhesive network MQ Silanol Resin 3-7 Tackifier Milliken ™ SiVance LLC Aerosil ™ 0.5-1.5 Cohesive Evonik (Fumed silica) strengthener Industries AG Foaming agent 0.5-25  Foaming or — blowing silicone matrix

[0077] Example formulations were prepared using different foaming agents and different combination of foaming agents forming part of the starting materials identified in table 1. It is preferred that the foaming agent is included in the part B silicone composition together with the MQ Silanol Resin and the Sodium Polyacrylate. Foaming agents tested include sodium bicarbonate; sodium bicarbonate and water; potassium bicarbonate; potassium bicarbonate and water; water; sodium bicarbonate, acid and water. The acid may comprise citric, acetic or 1-tartaric acid.

Sample Preparations

[0078] The Silpuran® based parts A and B were weighed and the other components, of the examples added at their respective concentrations. The components were mixed thoroughly to ensure complete dispersal of the components within the mix. In particular, thorough mixing reduces the risk of the SAPs agglomerating which would be detrimental to the moisture management characteristics across the full surface area of the skin compatible component. The above components were mixed using a medium to low shear mixing technique either by centrifusion or dispersal at 1000 to 3000 rpm. Surplus heat energy was removed by active cooling. Vacuum phase mixing was used as a final stage to provide an expanded/expanding liquid phase non-cured silicone formulation that was subsequently cured to solidify the foamed structure. A magnified image of the resulting foamed structure is shown in FIG. 6.

[0079] The laminate assembly 100 of FIGS. 1 to 4 was manufactured by layering the foamed liquid phase silicone formulation onto the polyurethane layer surface 101b followed by room temperate vulcanisation (RTV) under controlled conditions. The release liner 103, the polyethylene disc 105 and the coupling first part 106 was then attached to form the multi component assembly 100.

[0080] The mix of table 1 was prepared incorporating each of the various foaming agents as detailed in table 2 and 3. The silicone base mix was then coated on a 20 micron polyurethane film at 1000 μm thickness. The assembly was then cured at 120° C. for 10 minutes. Moisture vapour transmission rates were then measured in accordance with standard SATM E96/E96M using two methods, method 1—up-right cup and method 2—inverted cup.

Method 1

[0081] 1. The coated test material was positioned on a hard/flat surface with the adhesive side facing upward.

[0082] 2. The Si gasket was weighed.

[0083] 3. A careful cut was made around the Si gasket using this as a template to size.

[0084] 4. The EZ cup was filled with ˜100 ml of distilled water.

[0085] 5. The test material was assembled into the cup with the adhesive surface facing into and across the cup.

[0086] 6. A PTFE spacer was assembled at a second Si gasket.

[0087] 7. The EZ cup lid was screwed down, to be securely seated, but not so tight as to wrinkle the test material.

[0088] 8. The assembled cup and distilled water was weighed.

[0089] 9. The assembled cup was transferred horizontally onto an incubator at 37° C. (body temperature).

[0090] 10. The ‘In’ time and temperature was recorded.

[0091] 11. The cup left in the incubator for 24 h.

[0092] 12. After 24 hours the cup was removed and the ‘Out’ time and temperature recorded.

[0093] 13. The cup was re-weigh immediately.

[0094] 14. The cup unit was dismantled and the upper two gaskets removed. The test material and Si gasket was reweighed.

Method 2

[0095] 1. Steps 1 through 8 were followed under method 1.

[0096] 2. The cup was transferred to the incubator and placed on the horizontal surface with the cup inverted so that the distilled water contacted the Si adhesive surface.

[0097] 3. Points 10 through 13 of method 1 were followed.

[0098] 4. The cup unit was dismantled and the upper two gaskets removed. Any excess water/droplets were carefully removed from the test material and the test material and Si gasket reweighed.

Calculation and Reporting

[0099] 1. WVTR calculation [0100] a. Calculate the weight loss from the cup (G) in the 24 h period [0101] b. Calculate the WVTR using the following; [0102] i. G/0.003166=g.Math.m.sup.−2.Math.24 h.sup.−1 [0103] 2. Absorption calculation [0104] a. Calculate the initial and separately the final weight of the test material by subtracting weight of Si gasket. [0105] b. Calculate the weight increase of the test material and express the weight change as a percentage using; [0106] i. G (weight−gain)/G (weight−initial)×100=% w/w
The results of the WVTR assessment are shown in table 2.

TABLE-US-00002 TABLE 2 MVTR values for silcone matrix test materials incorporating various foaming agents NaHCO.sub.3 or 3N Foaming WVTR KHCO.sub.3 H.sub.2O Citric acid Agent (g .Math. m.sup.−2 .Math. 24 h.sup.−1) Vacuum SUBSTRATE w/w % w/w % w/w % Temp ° C. PULL No foaming 114 Yes-Speed mix 20 μm PU 0.0 0.00 0.00 100 1,000 agent NaHCO.sub.3 520 No-Speed mix 20 μm PU 16.7 0.00 0.00 100 1,000 NaHCO.sub.3 461 No-Speed mix 20 μm PU 1.0 0.00 0.00 150 1,000 NaHCO.sub.3 401 No-Speed mix 20 μm PU 14.3 0.00 0.00 100 1,000 NaHCO.sub.3 397 No-Speed mix 20 μm PU 4.7 0.00 0.00 100 1,000 NaHCO.sub.3 355 No-Speed mix 20 μm PU 9.0 0.00 0.00 100 1,000 NaHCO.sub.3 237 No-Speed mix 20 μm PU 7.5 0.00 0.00 100 1,000 KHCO.sub.3 376 No-Hand mix 20 μm PU 1.0 0.00 0.00 125 1,000 KHCO.sub.3 373 No-Speed mix 20 μm PU 1.0 0.00 0.00 125 1,000 NaHCO.sub.3 + 834 No-Speed mix 20 μm PU 15.4 7.70 0.00 100 1,000 Water NaHCO.sub.3 + 714 No-Speed mix 20 μm PU 8.9 1.80 0.00 100 1,000 Water NaHCO.sub.3 + 321 No-Speed mix 20 μm PU 10.0 1.00 0.00 100 1,000 Water NaHCO.sub.3 + 758 No-Speed mix 20 μm PU 1.5 2.00 0.00 125 1,000 Citric Acid + Water NaHCO.sub.3 + 328 No-Speed mix 20 μm PU 1.5 0.00 0.00 125 1,000 Citric Acid + without Water
MVTR values for a selection of the foamed materials of table 2 and some further foamed materials are shown in table 3.

Summary Results

[0107]

TABLE-US-00003 TABLE 3 MVTR values for silcone matrix test materials incorporating various foaming agents where A and B are acid-base compounds that comprise the citric acid and the bicarbonate respectively. NaHCO.sub.3 or 3N Foaming WVTR KHCO.sub.3 H.sub.2O Citric acid Agent (g .Math. m.sup.−2 .Math. 24 h.sup.−1) Vacuum SUBSTRATE w/w % w/w % w/w % Temp ° C. PULL TD NaHCO.sub.3 + 8.34 No-Speed mix M124B-20 15.4 7.70 0.0 100 1,000 Water A/B + Water 758 No-Speed mix M124B-20 1.5 2.00 0.0 125 1,000 TD NaHCO.sub.3 + 714 No-Speed mix M124B-20 8.9 1.80 0.0 100 1,000 Water A/B + Water 600 Yes-Speed mix M124B-20 0.9 0.00 10.0 125 760 TD NaHCO.sub.3 520 No-Speed mix M124B-20 16.7 0.00 0.0 100 1,000

[0108] As will be noted, whilst the above examples include water as an additive to formulations incorporating a bicarbonate salt, the blowing agent may comprises water exclusively or compositionally as a majority component of the blowing/foaming agent within the material composition of table 1.

[0109] In further example embodiments, the blowing agent of the material composition of table 1 comprises any one or a combination of a metal a bicarbonate salt; an azodicarbonamide; isocyanate; a volatile alkane; pentane; isopentane; cyclopentane; a gas phase compound to blow or expand the Si matrix, a fluorocarbon; a hydrofluorocarbon; a chlorinated fluorocarbon; a hydrocarbon; carbon dioxide or air.

[0110] As detailed in table 2 and 3, the moisture vapour transmission rates of the present silicone matrix material increased significantly due to the presence of the foaming agent. The WVTR values indicate an increase porosity of the Si matrix. Based on the results, the combination of a bicarbonate salt and water appreciably increased the WVTR. It will be appreciated that bicarbonate salts liberate carbon dioxide under thermal decomposition at the curing temperature range. Additionally, the aqueous phase represented as a gel evaporates at the cure temperature range to provide the blowing effect. Additionally, an acid-base reaction is effective to liberate a gaseous phase to expand the Si matrix during curing. This may be achieved via incorporation of bicarbonate salts and organic acids into the silicone formulation. Curing temperature was also found to effect the extent of foaming as indicated above. Without being bound by theory, it is believed the increased temperature during curing enhances decomposition of the bicarbonate salt to increase gas liberation during setting of the silicone matrix that in turn enhances the expanded/blown structure. Concentrations of the foaming additives were selected to avoid increasing/decreasing pH levels that would be detrimental to skin compatibility of the silicone formulations. It is believed the addition of water enhances the reaction of the bicarbonate and/or acid to increase the WVTR.

[0111] The present silicone adhesive is advantageous to provide a ‘soft’ atraumatic release from the skin so as to reduce the potential for skin stripping/damage. The present invention provides a balance of wear performance characteristics for skin compatibility including in particular edge lift, adhesion during wear, adhesion on removal, moisture control, skin condition after wear, skin trauma on removal and skin residue on removal. The present silicone adhesive is advantageous so as to be capable of being worn continuously during low, modest and high physical activity levels and movement as a wearer engages in such physical activity. The present skin adhesive is further advantageous to satisfy other ergonomic factors such as comfort during wear and conformity to skin/body topography.

[0112] The present foamed silicone polymer matrix incorporates an open or closed foam cell structure comprising holes, channels, voids, cavities or internal bubbles providing a porous structure to increase the water vapour transmission rate across the silicone layer. The foaming agent was configured specifically to expand the silicone polymer network to create the blown open structure. It is believed the enhanced open structure allows the through flow of vapour or moisture to enhance the moisture management characteristics of the silicone material in addition to facilitating moisture absorption by the SAPs within the silicone matrix.

[0113] Further embodiments of the present invention are illustrated referring to FIGS. 5A and 5B, with FIG. 5A being a variation of the embodiment of FIGS. 1 and 2 and FIGS. 5B being a variation of the embodiment of FIGS. 3 and 4. According to both further embodiments, an additional skin contact layer 300 is adhered to and positioned at surface 102b of silicone polymer matrix layer 102. The additional skin contact layer 300 is preferably formed from the same material as layer 102. However, different materials may be used such as silicones or hydrocolloid based materials.

[0114] The additional skin contact layer 300 may be regarded as an additional adhesive layer formed from narrow ridges that are discontinuous over surface 102b such that additional skin contact layer 300 does not coat completely the surface 102b and there is provided regions 301 that are devoid of additional skin contact layer 300 with regions 301 being exposed surface areas of the silicone polymer matrix layer 102.

[0115] According to embodiments of FIG. 5A the pattern of the additional skin contact layer 300 at surface 102b is a rectangular grid pattern or concentric circles formed by uniform ridges extending across surface 102b. The spaces between the ridges may be equal in the respective directions across surface 102b.

[0116] The embodiment of FIG. 5B comprises the additional skin contact layer 300 formed as a regular repeating array of nodes or bumps. The bumps may be separated from one another by a regular or uniform discreet separation distance such that the skin contact surface 102b of the silicone polymer matrix layer 102 is exposed at spacings 301 between the bumps 300.

[0117] According to a specific embodiment the additional skin contact layer 300 at surface 102b is formed as a series of concentric circles extending radially between central bore 104 and outer perimeter 107. The concentric circles (or other polygonal (i.e., rectangular) or non-polygonal (i.e., oval) shapes) may be spaced apart from one another in the radial direction to be formed as discreet ridges separated by regions of exposed surface 102b. Such an embodiment is further beneficial to increase the strength and integrity of the moisture seal of the present coupling and reduce the risk of fluid leakage from under the coupling between the surface 102b and the skin.