SKIN COMPATIBLE SILICONE COMPOSITION

Abstract

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

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 μm 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 9 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 wherein the permeability modifying polymer is a water soluble polymer having hydrophobic domains.

14. The component as claimed in claim 1 wherein the permeability modifying polymer is not chemically bonded to the silicone polymer network.

15. The component as claimed in claim 1 wherein the permeability modifying polymer is any one of a combination of the following set of: polyvinyl alcohol (PVA); polyvinyl chloride (PVC); a poloxamer; a polyester; or polyvinyl pyrrolidone (PVP).

16. The component as claimed in claim 15 wherein the poloxamer comprises poloxamer 407 (EO.sub.100PO.sub.65EO.sub.100) or poloxamer P123 (EO.sub.19PO.sub.69EO.sub.19).

17. The component as claimed in claim 15 wherein the polyester comprise polycaprolactone (PCL).

18. The component as claimed in claim 15 wherein the permeability modifying polymer is PVA and comprises a molecular weight in a range 50,000 to 150,000; 60,000 to 120,000; 70,000 to 100,000; or 80,000 to 90,000.

19. The component as claimed in claim 15 wherein the permeability modifying polymer is PVP and comprises a molecular weight in a range 5,000 to 50,000; 10,000 to 40,000; 15,000 to 35,000; or 20,000 to 30,000.

20. The component as claimed in claim 15 wherein the permeability modifying polymer is PVC and comprises a molecular weight in a range 50,000 to 100,000 or 70,000 to 90,000.

21. The component as claimed in claim 1 comprising the permeability modifying polymer at 0.1 to 5.0 wt %; 0.1 to 4.0 wt %; 0.1 to 3.0 wt %; 0.1 to 2.0 wt %; 0.2 to 1.8 wt %; 0.2 to 1.6 wt %; 0.2 to 1.2 wt %; 0.2 to 1.0 wt %; 0.2 to 0.8 wt %; 0.2 to 0.4 wt %; or 0.6 to 1.0 wt %.

22. 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.

23. The coupling as claimed in claim 22 wherein the support layer comprises polyurethane.

24. The coupling as claimed in claim 22 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.

25. The coupling as claimed in any one of claim 22 wherein the ostomy appliance comprises a bag or pouch attached to the support layer directly or via an intermediate layer.

26. The coupling as claimed in claim 25 wherein the intermediate layer comprises polyethylene.

27. The coupling as claimed in claim 25 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.

28. The coupling as claimed in any one of claim 22 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.

29. The coupling as claimed in any one of claim 22 wherein the coupling comprises an opening extending through the support layer and the skin compatible component.

30. The coupling as claimed in any one of claim 22 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.

31. The coupling as claimed in claim 30 wherein the additional skin contact layer is formed as lines, dots, flecks or marks on the skin facing side of the skin compatible component.

32. The coupling as claimed in claim 31 wherein the lines, dots, flecks or marks create a pattern on the a skin facing surface of the skin compatible component that is substantially uniform across the skin facing surface.

33. The coupling as claimed in claim 30 wherein the additional skin contact layer is formed as lines or ridges extending over a skin facing surface of the skin compatible component.

34. The coupling as claimed in claim 33 wherein the lines or ridges are distributed at the skin facing surface to create geometric shapes.

35. The coupling as claimed in claim 33 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.

36. 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 a permeability modifying polymer; and curing the mix via a metal catalyst; wherein the superabsorbent particulate and the permeability modifying polymer are distributed within the resulting addition cured silicone polymer network.

37. The method as claimed in claim 36 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.

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

39. The method as claimed in claim 36 wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

40. The method as claimed in claim 36 wherein the superabsorbent particulate comprises sodium polyacrylate.

41. The method as claimed in any one of claim 36 wherein the first part or the second part further comprise an organosilicone resin.

42. The method as claimed in claim 41 wherein the organosilicone resin comprises an MQ resin.

43. The method as claimed in claim 42 wherein the organosilicone resin is a silicic acid, trimethylsilylester with silanol functionality.

44. The method as claimed in claim 43 wherein the organosilicone resin is included in the mix at 0.2 to 10 wt %, 1 to 9 wt %, 2 to 8 wt %; 3 to 7 wt % or 4 to 6 wt %.

45. The method as claimed in any one of claim 36 wherein the first or second part further comprises a cohesive strengthening agent.

46. The method as claimed in claim 45 wherein the cohesive strengthening agent comprises fumed silica.

47. The method as claimed in claim 46 wherein the fumed silica comprises a bulk density of 0.4 to 0.8 g/mL and a Brunauer-Emmitt-Teller (BET) specific surface area of 200 to 320 mm.sup.2/g, 210 to 310 mm.sup.2/g, 230 to 300 mm.sup.2/g or 230 to 290 mm.sup.2/g.

48. The method as claimed in claim 46 wherein the fumed silica is included within the mix at 0.2 to 2.0 wt %, 0.3 to 2.0 wt %, 0.5 to 1.5 wt % or 0.8 to 1.2 wt %.

49. The method as claimed in any one of claim 36 wherein the superabsorbent particulate comprises a particle size in a range 10 to 40 μm, 15 to 35 μm or 20 to 30 μm.

50. The method as claimed in claim 49 wherein the superabsorbent particulate is included within the mix at 5 to 45 wt %, 15 to 35 wt % or 20 to 30 wt %.

51. The method as claimed in any one of claim 36 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.

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

53. The method as claimed in any one of claim 36 wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

54. The method as claimed in any one of claim 36 wherein the superabsorbent particulate comprises sodium polyacrylate.

55. The method as claimed in any one of claim 36 wherein the vinyl functionalized siloxane polymer comprises a vinyl-terminated polydimethylsiloxane (PDMS).

56. The method as claimed in any one of claim 36 wherein the silicon hydride containing crosslinker comprises a hydride-terminated polydimethylsiloxane (PDMS).

57. The method as claimed in claim 56 wherein the vinyl-terminated polydimethylsiloxane (PDMS) comprises a first vinyl-terminated PDMS having a mass average of 10,000 to 20,000 and a second vinyl-terminated PDMS having a mass average of 70,000 to 100,000.

58. The method as claimed in claim 36 wherein the vinyl functionalized siloxane polymer comprises a vinyl-terminated polydimethylsiloxane (PDMS) and the silicon hydride containing crosslinker comprises a hydride-terminated polydimethylsiloxane (PDMS).

59. The method as claimed in claim 58 wherein the first part is included within the mix at 30 to 40 wt % or 31 to 35 wt % and the second part is included within the mix at 30 to 40 wt % or 33 to 37 wt %.

60. The method as claimed in claim 59 wherein the superabsorbent particulate is included within the mix at 20 to 30 wt % or 22 to 28 wt %.

61. The method as claimed in claim 60 further comprising an MQ resin included in the mix at 2 to 8 wt % or 3 to 7 wt %.

62. The method as claimed in claim 61 further comprising fumed silica included within the mix at 0.2 to 2.0 wt %, 0.5 to 1.5 wt % or 0.8 to 1.2 wt %.

63. The method as claimed in claim 62 wherein the first part further comprises an organoplatinum catalyst and a silicone-vinyl containing inhibitor and the second part further comprises a vinyl-terminated polydimethylsiloxane (PDMS) and wherein the superabsorbant particulate is sodium polyacrylate.

64. The method as claimed in any one of claim 36 wherein the permeability modifying polymer is any one of a combination of the following set of: polyvinyl alcohol (PVA); polyvinyl chloride (PVC); a poloxamer; a polyester; or polyvinyl pyrrolidone (PVP).

65. The method as claimed in claim 64 wherein the poloxamer comprises poloxamer 407 (EO.sub.100PO.sub.65EO.sub.100) or poloxamer P123 (EO.sub.19PO.sub.69EO.sub.19).

66. The method as claimed in claim 64 wherein the polyester comprise polycaprolactone (PCL).

67. The component as claimed in any one of claim 36 wherein the permeability modifying polymer is incorporated within the mix at 0.1 to 5.0 wt %; 0.1 to 4.0 wt %; 0.1 to 3.0 wt %; 0.1 to 2.0 wt %; 0.2 to 1.8 wt %; 0.2 to 1.6 wt %; 0.2 to 1.2 wt %; 0.2 to 1.0 wt %; 0.2 to 0.8 wt %; 0.2 to 0.4 wt %; or 0.6 to 1.0 wt %.

68. A skin compatible component attachable to mammalian skin manufactured by the method of claim 36.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0067] 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:

[0068] FIG. 1 is a plan view of an ostomy appliance coupling according to a specific implementation of the present invention;

[0069] FIG. 2 is a cross sectional view through A-A of the ostomy coupling of FIG. 1;

[0070] FIG. 3 is a plan view of an ostomy appliance coupling according to a further specific implementation of the present invention;

[0071] FIG. 4 is a cross sectional view through B-B of the ostomy coupling of FIG. 3;

[0072] 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;

[0073] 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.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

[0074] 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 subject component 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 silicone matrix and additives (in the form of SAPs and moisture management polymer species) is advantageous to balance moisture absorption with moisture and water vapour transmission to avoid skin maceration.

[0075] 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.

[0076] 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.m.sup.−20.24 h.sup.−1 and preferably a MVTR of 700 to 950 g.m.sup.−20.24 h.sup.−1 using an upright cup method. According to the specific implementation, the polyurethane layer has an MVTR of 875 g.m.sup.−20.24 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.

[0077] 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.

[0078] A silicone polymer matrix layer 102 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.

[0079] 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.

[0080] 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.

[0081] 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 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.

[0082] A specific embodiment of the polymer layer 102 will now be described by reference to the following examples. Polymer layer 102 is formed as a silicone polymer matrix derived from the addition curing of a first part and a second part. 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).

[0083] 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.

EXAMPLES

[0084]

TABLE-US-00001 TABLE 1 starting materials of liquid phase non-cured mix Concentra- tion Component % w/w Purpose Supplier Silicone 31-35 Part A silicone + Wacker Chemie Silpuran ® catalyst 2122 part A Silicone 33-37 Part B silicone Wacker Chemie Silpuran ® cross-linker 2122 part B Aquakeep ™ 22-27 Moisture control, Sumitomo Seika Sodium moisture transmis- Chemicals Co., Polyacrylate sion through Ltd silicone adhesive network MQ Silanol Resin 3-7 Tackifier Milliken ™ SiVance LLC Aerosil ™ 0.5-1.5 Cohesive Evonik Industries (Fumed silica) strengthener AG Permeability 0.1-2.0 Modify Sigma Oldridge modifying permeability Polymer polymer Laboratories

[0085] The following examples were prepared using different permeability modifying polymers forming part of the starting materials identified in table 1. The permeability modifying polymer is preferably included in the part B silicone composition but may be included in part A.

TABLE-US-00002 TABLE 2 example permeability modifying polymers incorporated within the starting materials of table 1 where mw is molecular weight. Example Permeability Modifying Polymer Concentration 1 Poly(2-vinylpyridine); mw/mn 1.15 0.8 2 Poly(vinylalcohol); mw 86,000 0.8 3 Poly(vinylchloride); mw 83,500 0.8 4 Polyvinylpyrrolidone); mw 24,000 0.8 5 Poly(vinylpyrrolidone); mw 10,000 0.8 6 Poloxamer F127 (EO.sub.100PO.sub.65EO.sub.100) 0.8 7 Polycaprolacetone diol mw 530 0.4 8 Poly(vinylpyrrolidone) mw 24,000 0.4 9 no permeability modifying polymer — (Comparative) 10  Hydrocolloid MED 5094 H — (Comparative)

[0086] Manufacture Method

[0087] 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 and in particular the SAPs (i.e., sodium polyacrylate) and permeability modifying polymer within the mix. This is advantageous to provide a complete heterogeneous dispersion of the components and in particular the complete distribution of the SAPs and permeability modifying polymer within the silicone matrix. In particular, thorough mixing reduces the risk of the SAPs and/or the permeability modifying polymer agglomerating which would be detrimental to the moisture-vapour management (absorption and transmission) 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 a liquid phase non-cured silicone formulation. The laminate assembly 100 of FIGS. 1 to 4 was manufactured by layering the 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.

TEWL Performance and Results

[0088] 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. Additionally, the present adhesive comprises the desired cohesive strength and tack adhesion so as to be maintained in position for extended wear times of the order of over 400 hours without degradation and loss of moisture absorption and transmission at the adhesive layer. 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.

[0089] Transepidermal water loss (TEWL) or the equivalent moisture vapour transmission rate (MVTR) are well established techniques to determine water and vapour transmission across a material. These characteristics are particularly important for a material composition attached to the skin. In accordance with the subject invention, it is important that the present silicone material does not leach SAPs, monomers or polymers, adheres to the skin appreciably but not to a significant extent that would otherwise damage the skin on removal (i.e. skin peeling or skin stripping). The example silicone base materials were assessed to determine relative TEWL ratings in both a ‘dry’ and a ‘wet’ environment to understand how permeability of the present silicone materials would perform as a dressing applied to the skin that may be, between two extremes i.e., dry and wet. It is important that the present silicone based materials have a degree of permeability and a moisture vapour transmission without being excessively absorbent. The addition of the permeability modifying polymer therefore provides a means of controlling hydrophilicity and hydrophobicity of the material to improve/enhance permeability of the silicone layer without contributing significantly or enhancing significantly the absorbent characteristics of the material (as this may be controlled by variation of the concentration and/or type and configuration of the SAPs).

[0090] Without being bound by theory, it is believed that the present permeability modifying polymers (added in relatively small quantities) sits between the silicone matrix forming a semi-interpenetrating polymer network and thereby modulating the permeability of the bulk material. It is important that this additive should not be too hydrophilic as this will encourage the bulk material to swell and absorb moisture. Accordingly, the permeability modifying polymers were selected to comprise hydrophobic domains causing entropic resistance to perfect dissolution and encouraging water permeability without becoming absorbent.

[0091] TEWL testing was undertaken to determine the moisture vapour transmission across the silicone materials of examples 1 to 8 in addition to the comparative examples 9 and 10. Comparative 9 is a silicone material comprising the components of table A without a permeability modifying polymer and comparative 10 is the silicone material comprising the components of table A with addition of a hydrocolloid.

Equipment

[0092] A Heidolph Hei-Toeque 100 was used for high speed stirring of silicone resins. The draw down bar (1000 micron thickness) was used to spread the silica across a PU film. TEWL values were recorded on a Delfin Technologies Vapometer (Serial SWL5316) equipped with room sensor S/N RHD 1236.

Recording Sample TEWL

[0093] Silicone matrix samples were prepared from the materials of tables 1 and 2 and the mix spread across a PU film and then incubated for 10 minutes and incubated at 100° C. The water permeability of coatings was measured with a handheld device calibrated to measure the TEWL of skin and surfaces in relation to the ambient temperature and humidity. Coating measurements were not carried out in a specifically air-regulated room although in all cases the ambient temperature was 22-24° C. and the sample was heated to 32° C. to mimic the temperature at the skins surface. Room humidity varied from 40 to 49% and an anova comparison of the data found there was no significant correlation between the room humidity and the TEWL observed.

[0094] To measure the TEWL of adhesive materials it was not possible to directly connect the vapometer to the adhesive. Instead, to mimic the application of these in medical dressings, the TEWL was measured through a sandwich design with the adhesive contained between two barrier sheets. The upper PU Film to mimic the protective layer on the medical dressing and the lower to separate the adhesive from moisture sources. The lower barrier layer was tested with both PU film and Wattman filter paper, to compare different occlusive materials. Below the lower barrier layer a standard piece of tissue paper was used, either wet or dry, in an experimental design created to mimic the skin surface where a high moisture content is separated from the adhesive by a thin dermal barrier. Samples were incubated at 32° C. with a wet/dry tissue for 1 hour to ensure they were fully acclimatised to their environment, and the samples were measured immediately upon removal from the incubating oven. In most cases the TEWL was measured on 4 different points in each surface, and each material was repeated 4 times, giving us an n=16 to determine sample variation. This experimental design also allowed us to compare the changing TEWL of the material in both dry and wet conditions—as it will be important for adhesives not to decrease their TEWL as the relative moisture level increases, as this kind of occlusive behaviour has identified as being detrimental to the wearer.

Samples

[0095] Small quantities of the permeability modifying polymer (0.8%) were included in the mixture of table 1 for testing. Examples 7 and 8 were variations on examples 1 to 6 in that 0.4 w/w % of the permeability modifying polymer was added to the mixture of table 1 not 0.8 w/w %.

Results

[0096] The results of the TEWL testing are shown in table 3

TABLE-US-00003 TABLE 3 TEWL testing of examples 1 to 10 where mw is molecular weight. % % change Exam- Dry Wet change from ple TEWL TEWL dry/wet original 1 Poly(2-vinylpyridine) 7.09 8.5 +20 +33 mw/mn 1.15 2 Poly(vinylalcohol) mw 10.32 11.82 +15 +93 86,000 3 Poly(vinylchloride) mw 8.27 10.86 +31 +55 83,500 4 Polyvinylpyrrolidone) 9.61 12.46 +30 +80 mw 24,000 5 Poly(vinylpyrrolidone) 9.94 12 +21 +86 mw 10,000 6 Poloxamer F127 9.23 12.94 +40 +73 (EO.sub.100PO.sub.65EO.sub.100) 7 Polycaprolacetone Diol 7.19 10.04 +40 +35 mn 530 8 Poly(vinylpyrrolidone) 5.71 8.44 +48 +7 mw 24,000 9 Without permeability 5.34 7.53 +41 0 modifying polymer 10 MED 5094 H 2.10 1.73 −17.6 0 (Hydrocolloid)

[0097] The results confirm that incorporating a permeability modifying polymer increases the transepidermal water loss as a measure of the moisture vapour transmission rate across the silicone matrix relative to a silicone material without a permeability modifying polymer (comparative example 9). The examples 1 to 8 all exhibit an increase in the moisture vapour transmission in both dry and wet conditions. As indicated, it is believed the silicone matrix permeability is modified due to the incorporation of the relatively small amounts of modifying polymer to change the bulk hydrophilicity of the material.

Further Embodiments

[0098] 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 FIG. 5B being a variation of the embodiment of FIGS. 3 and 4 with all embodiments comprising the silicone matrix with SAP and polymer additive according to any of examples 1 to 8 herein. 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. In a preferred embodiment layer 300 comprises the silicone polymer matrix formed from the components of table 1 but without the SAP and the permeability modifying polymer.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.