Skin compatible 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 moisture control particulate distributed within the polymer network being configured to absorb moisture from the skin. 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-skin.

Claims

1. A skin compatible component attachable to mammalian skin comprising: a silicone polymer network derived from 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 at a concentration in a range of 5 to 45 wt % and having an average particle size in a range of 10 to 40 μm, the superabsorbent particulate configured to absorb moisture from the skin, wherein the first part or the second part includes a MQ resin, and the first part or the second part includes fumed silica.

2. The component as claimed in claim 1, wherein the average particle size of the superabsorbent particulate is in a range of 15 to 35 μm or 20 to 30 μm.

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

4. 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.

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

6. 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.

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

8. 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, the first part or the second part including an MQ resin, and the first part or the second part including fumed silica; incorporating within the mix a superabsorbent particulate having an average particle size in a range 10 to 40 μm; and addition curing the mix via a metal catalyst to form a silicone polymer network, wherein the superabsorbent particulate is distributed within the silicone polymer network at a concentration in a range of 5 to 45 wt %.

9. The method as claimed in claim 8, 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.

10. The method as claimed in claim 8, wherein the superabsorbent particulate comprises any one or a combination of: a polysaccharide; a cellulose; hydroxyethylcellulose; carboxymethylcellulose; hydroxypropylcellulose.

11. The method as claimed in claim 8, wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

12. The method as claimed in claim 8, wherein the superabsorbent particulate comprises sodium polyacrylate.

13. The method as claimed in claim 8, wherein the MQ resin is included in the mix at 2 to 8 wt % or 3 to 7 wt %.

14. The method as claimed in claim 8, 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.

15. The method as claimed in claim 8, 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 %.

16. The method as claimed in claim 8, wherein the average particle size of the superabsorbent particulate is in a range of 15 to 35 μm or 20 to 30 μm.

17. The method as claimed in claim 16, wherein the superabsorbent particulate is included within the mix at 15 to 35 wt % or 20 to 30 wt %.

18. The method as claimed in claim 8, 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.

19. The method as claimed in claim 8, wherein the superabsorbent particulate comprises any one or a combination of: a polysaccharide; a cellulose; hydroxyethylcellulose; carboxymethylcellulose; hydroxypropylcellulose.

20. The method as claimed in claim 8, wherein the superabsorbent particulate comprises any one or a combination of: carboxymethyl β-glucan; cross-linked sodium carboxymethyl cellulose; sodium carboxymethyl cellulose; or methylcellulose.

21. The method as claimed in claim 8, wherein the superabsorbent particulate comprises sodium polyacrylate.

22. The method as claimed in claim 8, wherein the vinyl functionalized siloxane polymer comprises a vinyl-terminated polydimethylsiloxane (PDMS).

23. The method as claimed in claim 8, wherein the silicon hydride containing crosslinker comprises a hydride-terminated polydimethylsiloxane (PDMS).

24. The method as claimed in claim 23, 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.

25. The method as claimed in claim 8, wherein the vinyl functionalized siloxane polymer comprises a vinyl-terminated polydimethylsiloxane (PDMS) and the silicon hydride containing crosslinker comprises a hydride-terminated polydimethylsiloxane (PDMS).

26. The method as claimed in claim 25, 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 %.

27. The method as claimed in claim 26, wherein the superabsorbent particulate is included within the mix at 20 to 30 wt % or 22 to 28 wt %.

28. The method as claimed in claim 27, wherein the MQ resin is included in the mix at 2 to 8 wt % or 3 to 7 wt %.

29. The method as claimed in claim 28, wherein the fumed silica is included within the mix at 0.2 to 2.0 wt %, 0.5 to 1.5 wt % or 0.8 to 1.2 wt %.

30. The method as claimed in claim 29, 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.

31. A skin compatible component attachable to mammalian skin manufactured by the method of claim 8.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) 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:

(2) FIG. 1 is a plan view of an ostomy appliance coupling according to a specific implementation of the present invention;

(3) FIG. 2 is a cross sectional view through A-A of the ostomy coupling of FIG. 1;

(4) FIG. 3 is a plan view of an ostomy appliance coupling according to a further specific implementation of the present invention;

(5) FIG. 4 is a cross sectional view through B-B of the ostomy coupling of FIG. 3;

(6) 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;

(7) 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

(8) 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 is advantageous to balance moisture absorption with moisture and water vapour transmission to avoid skin maceration.

(9) The subject invention is particularly suitable to secure medical appliances or devices to mammalian skin and in particular peri-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.

(10) 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.

(11) 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.

(12) 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.

(13) 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.

(14) 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.

(15) A specific embodiment of the polymer layer 102 will now be described by reference to the following examples.

(16) 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).

(17) 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.

Example 1—MIX #548

(18) TABLE-US-00001 TABLE 1 starting materials of liquid phase non-cured mix example 1 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 33.60 Part A silicone + Wacker Chemie 2122 part A catalyst Silicone Silpuran ® 35.40 Part B silicone Wacker Chemie 2122 part B cross-linker Aquakeep ™ 25.00 Moisture control, Sumitomo Seika Sodium Polyacrylate moisture transmission Chemicals Co., through silicone Ltd adhesive network MQ Silanol Resin 5.00 Tackifier Milliken ™ SiVance LLC Aerosil ™ (Fumed 1.00 Cohesive strengthener Evonik silica) Industries AG

Example 2—MIX #546

(19) TABLE-US-00002 TABLE 2 starting materials of liquid phase non-cured mix example 2 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 31.25 Part A silicone + Wacker Chemie 2122 part A catalyst Silicone Silpuran ® 33.75 Part B silicone Wacker Chemie 2122 part B cross-linker Aquakeep ™ 30.00 Moisture control, Sumitomo Seika Sodium moisture transmission Chemicals Co., Polyacrylate through silicone Ltd adhesive network LIR-310 Kurraray 5.00

Example 3—MIX #543

(20) TABLE-US-00003 TABLE 3 starting materials of liquid phase non-cured mix example 3 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 38.46 Part A silicone + Wacker Chemie 2122 part A catalyst Silicone Silpuran ® 41.54 Part B silicone Wacker Chemie 2122 part B cross-linker Aquakeep ™ 20.00 Moisture control, Sumitomo Seika Sodium moisture transmission Chemicals Co., Polyacrylate through silicone Ltd adhesive network

Example 4—MIX #535

(21) TABLE-US-00004 TABLE 4 starting materials of liquid phase non-cured mix example 4 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 52.40 Part A silicone + Wacker Chemie 2122 part A catalyst Silicone Silpuran ® 47.60 Part B silicone Wacker Chemie 2122 part B cross-linker

Example 5—MIX #27

(22) TABLE-US-00005 TABLE 5 starting materials of liquid phase non-cured mix example 5 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 45.00 Part A silicone + Wacker Chemie 2130 part A catalyst Silicone Silpuran ® 45.00 Part B silicone Wacker Chemie 2130 part B cross-linker Aquakeep ™ 8.00 Moisture control, Sumitomo Seika Sodium moisture transmission Chemicals Co., Polyacrylate through silicone Ltd adhesive network Aerosil ™ (Fumed 1.00 Cohesive strengthener Evonik silica) Industries AG Glycerol 1.00

Example 6—MIX #11

(23) TABLE-US-00006 TABLE 6 starting materials of liquid phase non-cured mix example 6 Concen- tration Component % w/w Purpose Supplier Silicone Silpuran ® 46.95 Part A silicone + Wacker Chemie 2117/2140 part A catalyst Silicone Silpuran ® 46.95 Part B silicone Wacker Chemie 2117/2140 part B cross-linker Sodium 5.00 carboxymethylcellulose Aqualon CMC 7HF PH Aerosil ™ (Fumed silica) 0.10 Cohesive Evonik strengthener Industries AG Glycerol 1.00
Manufacture Method

(24) 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 SAP (i.e., sodium polyacrylate) within the mix. This is advantageous to provide a complete heterogeneous dispersion of the components and in particular the complete distribution of the moisture absorbing particulate (SAP) within the silicone matrix. 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 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.

(25) Performance and Results

(26) 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.

(27) To assess the wear performance characteristics, a series of wear tests were undertaken using the above examples 1 to 7. All wear tests were untaken on a male, in the age range 51-60.

(28) TABLE-US-00007 TABLE 8 Standard Hydrocolloid Adhesives (control) Wear Edge lift Adhesion Adhesion Moisture Skin time during during on under condition on Trauma Residue Coating Formulation # Form (h) wear wear removal adhesive removal on removal on removal Substrate 90 mins Cardio-vascular activity/1 × shower Control - CP Wafer 72 Low Feels secure Very high None Healthy High None PE base Sensura 10021 Some creasing Some reddening plate Base plate due to stiffness caused by trauma. of coated Very tight on substrate removal 60 mins Cardio-vascular activity/4 × showers Control - CP Wafer 98 High Feels secure High None Dry High Slight PE base Sensura 10021 Significant edge Very Slight plate Base plate lift on top uncomfortable. residues side of Skin reddening at edges outer diameter due to trauma of wafer of removal.

(29) TABLE-US-00008 TABLE 9 Co-polyester Film substrate - PT RTV Cure Silicone (2) Edge lift Adhesion Moisture Skin Wear during during Adhesion on under condition on Trauma Residue Coating Formulation # Form time (h) wear wear removal adhesive removal on removal on removal Substrate Normal activity - recorded as fail due to edge lift & channels with this formulation & coating substrate. High levels of creasing leading to channels for leak with this substrate 11 (2117/2140) Wafer 74 High Does not High None Healthy Acceptable Co-polyester feel secure Film

(30) TABLE-US-00009 TABLE 10 PU/Polyester Non-woven - 2PT RTV Cure Silicone (1) Wear Edge lift Adhesion Adhesion Moisture Skin Trauma Residue time during during on under condition on on on Formulation # Form (h) wear wear removal adhesive removal removal removal Coating Substrate Normal activity - recorded as fail due to edge lift and channels. Overall adhesion needs to be increased Uncomfortable in wear. Substrate causes creases and channels leading to edge lift. Substrate has insufficient elasticity. 27 (2130) Wafer 39 Medium Feels secure Medium None Healthy None None PU/Polyester non-woven Normal activity - recorded as fail due to edge lift and channels. Overall adhesion needs to be increased Wafer fell off when showering. Lots of wrinkling. 27 (2130) Wafer 66 Low Feels secure Medium Not Moist None None PU/Polyester non-woven determined Normal activity - 6× showers. Coating substrate leads to some wrinkling during wear. Overall adhesion needs to increase to improve security. 27 (2130) Wafer 144 None Feels secure High None Healthy None None PU/Polyester non-woven Normal activity - Only short wear time achieved. Failure caused by creasing. Sub optimal film substrate. Overall adhesion needs to increase. 27 (2130) Wafer 29 None Feels secure Fails None Healthy None Accept- PU/Polyester non-woven Creasing able Normal activity - Adhesive cohesion needs to be improved. Overall adhesion needs to increase. Poor cohesion of silicone gel to coating substrate causes edge lift and slight residues 27 (2130) Wafer 86 Medium Feels secure High None Healthy None Slight PU/Polyester non-woven with bag in-situ. 200 g load Normal activity - Adhesive cohesion needs to be improved. Some skin chafing occurred where ring sits. Overall adhesion needs to increase. Poor cohesion of silicone gel to coating substrate causes edge lift and slight residues 27 (2130) Wafer 76 Medium Feels secure High None Slight None None PU/Polyester non-woven with bag reddening in-situ. 200 g load

(31) TABLE-US-00010 TABLE 11 PU Film - 2PT RTV Cure Silicone (2) Wear Edge lift Adhesion Adhesion Moisture Skin Trauma Residue time during during on under condition on on on Coating Formulation # Form (h) wear wear removal adhesive removal removal removal Substrate Normal activity - recorded as fail due to edge lift. Formulation prone to leaving skin residues. 11 (2117/2140) Wafer 74 Low Feels secure High None Healthy Acceptable None PU Film Normal activity - recorded as fail due to edge lift. 11 (2117/2140) Wafer 74 Low Feels secure High None Healthy None None PU Film

(32) TABLE-US-00011 TABLE 12 PU Film - 2PT RTV Cure Silicone (3) - Ratio Adjustment Wear Edge lift Adhesion Adhesion Moisture Skin Trauma Residue time during during on under condition on on on Coating Formulation # Form (h) wear wear removal adhesive removal removal removal Substrate Normal activity - Recorded as fail due to edge lift 546 (2122) Strip 48 Some edge lift Feels secure High None Healthy None None PU Film Normal activity - Recorded as fail due to edge lift 543 (2122) Strip 24 Some edge lift Feels secure High None Healthy None None PU Film Normal activity - recorded as fail due to excess adhesion/tack & poor handleability Very tacky with poor anchorage to film substrate. Silicone rubs off to form residues. Handling of wafer problematic. 535 (2122) Strip 24 Excessive Feels secure High None Healthy Removal High PU Film adhesion & Tack problematic

(33) TABLE-US-00012 TABLE 13 PU Film - 2PT RTV Cure Silicone (3) Optimisation Wear Edge lift Adhesion Adhesion Moisture Skin Trauma Residue time during during on under condition on on on Coating Formulation # Form (h) wear wear removal adhesive removal removal removal Substrate Normal activity/3 × showers 548 (2122) - Best Wafer  72 None Feels secure High None Healthy Low None PU Film Performing with bag Low - in-situ. acceptable 200 g 180 mins Cardio-vascular activity/Swimming - Badminton - Sauna & Steam room 548 (2122) - Best Wafer 163 Acceptable Feels secure High None Healthy Acceptable Acceptable PU Film Performing V. Minor edge Very secure lift at the top outer diameter after 5 day of wear Normal activity 548 (2122) - Best Wafer 144 Acceptable Feels secure High None Healthy None None PU Film Performing V. Minor edge lift. 548 (2122) - Best Strip  96 Acceptable Feels secure High None Healthy Acceptable Acceptable PU Film Performing Normal activity 548 (2122) - Best Strip 144 Acceptable Feels secure High None Healthy Acceptable Acceptable PU Film Performing No residues Normal activity 548 (2122) - Best Strip 432 Acceptable Feels secure High None Healthy Acceptable Acceptable PU Film Performing V. Minor edge Excellent lift after 18 adhesion days wear.

(34) Comments referring to table 8—Wear tests highlight the shortcomings of the standard skin covering adhesive particularly in terms of trauma on removal and edge lift caused by the stiff base plate material.

(35) Comments referring to table 9—Change of coating substrate to co-polyester film and silicone formulation did not improve wear performance in terms of edge lift and security during wear time.

(36) Comments referring to table 10—Introduction of a PU/polyester non-woven coating substrate gives some overall improvement in the wear performance characteristics. Edge lift and adhesion are of concern and the overall strength of adhesion needs was considered not optimised.

(37) Comments referring to table 11—Change to silicone polymer formulation and coating substrate give further improvement. Further improvement required due to reduce edge lift and to reduce residues on removal.

(38) Comments referring to table 12—PU film coating substrates presenting best comfort and conformability. Change to higher adhesion silicone polymer formulation to improve overall adhesion and security during wear time.

(39) Mix #535 demonstrated desired tack and adhesion but poor handling and removal. Tack and adhesion were considered too high and formulation refinement was considered required. Mix #543 demonstrated reduced adhesion and tack resulting in edge lift. Mix #546 due to addition of tackifier at 5 wt % and super-absorbent polymer at 30 wt %, still demonstrated some edge lift.

(40) Comments referring to table 13—PU film provides excellent comfort and conformability in wear. The silicone formulation Mix #548 provides optimises tack/adhesion, security during wear and the other associated wear performance characteristics. Mix #548 (Example 1) provides the desired performance across all attributes and offers wear times in excess of 70 hours and potentially up to or beyond 400 hours continuous attachment.

(41) 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. 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.

(42) 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.

(43) 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.

(44) 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.

(45) 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.