POLYURETHANE BASED SWITCHABLE ADHESIVES

Abstract

The present disclosure relates to polyurethane based switchable adhesives. In at least one embodiment, a switchable adhesive composition comprises an adhesive component, which is formed from at least one isocyanate and a material or materials capable of undergoing cross-linking with isocyanate other than by free radical polymerization.

Claims

1-54. (canceled)

55. A switchable adhesive composition comprising, in proportions by weight based on the weight of the composition: 10% to 99.89% of an adhesive component; 5% to 80% of at least one curable molecule that is curable by free radical polymerisation; and 0.05% to 10% of photoinitiator, wherein the adhesive component is a polymer comprised of: a polyether or polyester polyol that is capable of undergoing cross-linking with isocyanate by a mechanism other than free radical polymerisation, the polyether or polyester polyol having an average of more than one functional group containing an active hydrogen atom and having a weight average molecular weight in the range 100 to 1,000,000 dalton; and (ii) at least one isocyanate having an average of more than one isocyanate functions to cross-link the material and having a weight average molecular weight in the range 100 to 1,000,000 dalton; characterized in that the at least one curable molecule comprises at least 2 unsaturated functional groups, and further characterized in that the switchable adhesive composition is adapted to irreversibly switch from a tacky state to a low-tack state responsive to irradiation by visible light or UV light.

56. A switchable adhesive composition as claimed in claim 55, wherein the curable molecules are oligomers of at least one of the following formulae (I) to (V):
CA(BA).sub.nC  (I) where n is 0, 1, 2, 3 or 4, A is a diisocyanate, a diepoxide, a diol or a dicarboxylic acid; B is a diol when A is a diisocyanate or a dicarboxylic acid; B is a dicarboxylic acid when A is a diepoxide or a diol; C is a hydroxyl containing acrylate ester when A is a diisocyanate or a dicarboxylic acid; C is an acrylic acid when A is a diepoxide or a diol;
C.sub.2E(BCE).sub.nC.sub.2  (II) where n is 0, 1, 2, 3 or 4, E is a tri-isocyanate, a triepoxide, a triol or a tricarboxylic acid; B is a diol when E is a tri-isocyanate or a tricarboxylic acid; B is a dicarboxylic acid when E is a triepoxide or a triol; C is a hydroxyl containing acrylate ester when E is a tri-isocyanate or a tricarboxylic acid; C is an acrylic acid when E is a triepoxide or a triol;
E.sub.(2n+1)F.sub.nC.sub.(3n+3)  (III) where n is 0, 1, 2, 3 or 4, E is a tri-isocyanate, a triepoxide, a triol or a tricarboxylic acid; F is a triol when E is a tri-isocyanate or a tricarboxylic acid; F is a tricarboxylic acid when E is a triepoxide or a triol; C is a hydroxyl containing acrylate ester when E is a tri-isocyanate or a tricarboxylic acid; C is an acrylic acid when E is a triepoxide or a triol;
G.sub.(n+1)B.sub.nC.sub.(2n+4)  (IV) where n is 0, 1, 2, 3 or 4, G is a tetra-isocyanate, a tetra-epoxide, a tetra-ol or a tetra-carboxylic acid; B is a diol when G is a tetra-isocyanate or a tetra-carboxylic acid; B is a dicarboxylic acid when G is a tetra-epoxide or a tetra-ol; C is a hydroxyl containing acrylate ester when G is a tetra-isocyanate or a tetra-carboxylic acid; C is a dicarboxylic acid when G is a tetra-epoxide or a tetra-ol;
DC.sub.3  (V) where D is a symmetrical isocyanurate trimeric ring structure or an asymmetric trimeric iminooxadiazinedione ring structure consisting of three diisocyanate molecules, or a linear trimeric biuret or allophanate structure, C is a hydroxyl containing acrylate ester; and wherein the oligomers have a weight average molecular weight of at least 500 dalton.

57. A switchable adhesive composition as claimed in claim 56, wherein the oligomers have a weight average molecular weight in the range 500 to 10,000 dalton.

58. A switchable adhesive composition as claimed in claim 55, wherein the curable molecules are unsaturated compounds having more than one unsaturated site.

59. A switchable adhesive composition as claimed in claim 58, wherein the curable molecules are selected from methacrylic acid esters, acrylic acid esters of alcohols, methacrylic acid esters of alcohols, glycols, pentaerythritol, trimethylpropane, glycerol, aliphatic epoxides, aromatic epoxides including bisphenol A epoxides, aliphatic urethanes, aromatic urethanes, silicones, polyesters, polyethers, or mixtures thereof.

60. A switchable adhesive composition as claimed in claim 55, comprising, in proportions by weight based on the weight of the composition: 40% to 98% of adhesive component; 2% to 60% of curable molecules curable by free radical polymerization; and 0.5% to 5% of photoinitiator.

61. A switchable adhesive composition as claimed in claim 55, comprising, in proportions by weight based on the weight of the composition: 60% to 95% of adhesive component; 5% to 40% of curable molecules curable by free radical polymerisation; and 0.5% to 5% of photoinitiator.

62. A switchable adhesive composition as claimed in claim 55, comprising, in proportions by weight based on the weight of the composition: 70% to 85% of adhesive component; 15% to 30% of curable molecules curable by free radical polymerisation; and 0.5% to 2% of photoinitiator.

63. A switchable adhesive composition as claimed in 55, wherein the polyol is a polyether polyol.

64. A switchable adhesive composition as claimed in claim 63, wherein the polyol is selected from ethoxylated or propoxylated species of glycerol, trimethylolpropane, pentaerythritol, dextrose, sorbitol, or di- or tri-ethers thereof.

65. A switchable adhesive composition as claimed in claim 63, wherein the polyol has an average of more than three and fewer than six hydroxyl functions.

66. A switchable adhesive composition as claimed in claim 55, wherein the weight average molecular weight of the isocyanate is in the range 100 to 2000 dalton.

67. A switchable adhesive composition as claimed in claim 55, wherein the isocyanate is selected from hexamethylene diisocyanate, isophorone diisocyanate, toluene 2,4-diisocyanate, 4,4′-methylenebis(phenyl isocyanate), 4,4′-methylenebis(cyclohexyl isocyanate), or their homopolymers, or a diisocyanate terminated reaction product with diol.

68. A switchable adhesive composition as claimed in claim 55, wherein the isocyanate is methacrylated oligomer having an average isocyanate functionality of at least two.

69. A switchable adhesive composition as claimed in claim 55, wherein the photoinitiator is reactive to visible light.

70. A switchable adhesive composition as claimed in claim 55, wherein the reduction in peel force of the adhesive after switching is 30 to 99% when determined according to FINAT test method FTM1 using high density polyethylene (HDPE) panels as the substrate surface with a peeling rate of 100 mm/min and a crosshead speed of 200 mm/s.

71. An adhesive medical product comprising a switchable adhesive composition as claimed in claim 55.

72. An adhesive medical product as claimed in claim 71, wherein the adhesive medical product is selected from an adhesive dressing including an absorbent wound pad, a surgical incision drape, a bacterial barrier for covering a wound wherein the bacterial barrier has no absorbent wound pad, or a skin closure device for closing together the edges of a wound.

73. An adhesive medical product as claimed in claim 71, comprising a layer of the switchable adhesive composition disposed between a first carrier film and a second carrier film wherein at least one of the carrier films includes a light occlusive layer on the surface of the carrier film remote from the adhesive composition.

74. An adhesive medical product as claimed in claim 73, wherein the carrier films have a low surface energy relative to skin so that the adhesive composition adheres preferentially to skin.

75. A method of treating a wound comprising applying an adhesive dressing as claimed in claim 72 to the wound site.

76. A method of preparing a site for surgical incision using a surgical incision drape as claimed in claim 74, the method comprising: (i) removing the first carrier film from the surgical incision drape to expose one surface of the adhesive composition layer; (ii) placing the exposed surface of the adhesive composition layer on a patient's skin at the intended site for surgical incision; (iii) subjecting the adhesive composition layer to visible light or UV irradiation through the second carrier film to effect cure of the curable molecules in the adhesive composition; and (iv) after curing of the curable molecules or curable moieties in the adhesive composition, removing the second carrier film to expose the other surface of the cured adhesive composition layer.

77. A method of covering a wound using a bacterial barrier as claimed in claim 74, the method comprising: (i) removing the first carrier film from the bacterial barrier to expose one surface of the adhesive composition layer; (ii) placing the exposed surface of the adhesive composition layer on a patient's skin over the wound; (iii) subjecting the adhesive composition layer to visible light or UV irradiation through the second carrier film to effect cure of the curable molecules in the adhesive composition; and (iv) after curing of the curable molecules or curable moieties in the adhesive composition, removing the second carrier film to expose the other surface of the cured adhesive composition layer.

78. A method of closing the edges of a wound using a skin closure device as claimed in claim 74, the method comprising: (i) removing the first carrier film from the skin closure device to expose one surface of the adhesive composition layer; (ii) placing one end of the exposed surface of the adhesive composition layer on a patient's skin in the vicinity of one end of the wound; (iii) bringing the edges of the wound together and progressively applying the adhesive composition layer along the wound from the one end to the other end of the wound; (iv) subjecting the adhesive composition layer to visible light or UV irradiation through the second carrier film to effect cure of the curable molecules in the adhesive composition; and (iv) after curing of the curable molecules or curable moieties in the adhesive composition, removing the second carrier film to expose the other surface of the cured adhesive composition layer.

79. A switchable adhesive composition comprising, in proportions by weight based on the weight of the composition: 90% to 99.95% of an adhesive component; and 0.05% to 10% of photoinitiator; wherein the adhesive component is a polymer comprising: (i) a polyether or polyester polyol that is capable of undergoing cross-linking with isocyanate by a mechanism other than free radical polymerisation, the polyether or polyester polyol having an average of more than one functional group containing an active hydrogen atom, a proportion of the functional groups containing an active hydrogen atom being reacted with and bonded to a curable moiety that is curable by free radical polymerisation, such that the adhesive composition comprises up to 98% by weight of such curable moieties, and having a weight average molecular weight in the range 100 to 1,000,000 dalton, and (ii) at least one isocyanate having an average of more than one isocyanate functions to cross-link the material and having a weight average molecular weight in the range 100 to 1,000,000 dalton; characterized in that the switchable adhesive composition is adapted to irreversibly switch from a tacky state to a low-tack state responsive to irradiation by visible light or UV light.

80. A switchable adhesive composition as claimed in claim 79, wherein at least 20% of the available functional groups comprising an active hydrogen atom in the material or materials capable of undergoing cross-linking with isocyanate other than by free radical polymerisation are bonded to curable moieties.

81. A switchable adhesive composition as claimed in claim 79, comprising at least 0.1% wt., based on the weight of the adhesive composition, of at least one curable acrylate moiety bound to the isocyanate.

82. A switchable adhesive composition as claimed in claim 79, wherein the curable moiety comprises an isocyanato C.sub.1-6alkyl 2-C.sub.0-6alkylacrylate or an isocyanato C.sub.1-3alkyl 2-C.sub.0-3alkylacrylates.

83. A switchable adhesive composition as claimed in claim 79, wherein the polyol is a polyether polyol.

84. A switchable adhesive composition as claimed in claim 83, wherein the polyol is selected from ethoxylated or propoxylated species of butyldiol, glycerol, trimethylolpropane, pentaerythritol, dextrose, sorbitol, or di- or tri-ethers thereof.

85. A switchable adhesive composition as claimed in claim 79, wherein the curable moiety comprises an isocyanate group with a pendant acrylate function or pendant acrylate functions bonded to the material capable of undergoing cross-linking with isocyanate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0188] The invention will be further described by way of example only and without limitation by reference to the drawings in which:

[0189] FIG. 1 is a cross-sectional view through an adhesive dressing in accordance with a first embodiment of the invention;

[0190] FIG. 2 is a perspective view showing the attempted removal from a patient's forearm of an adhesive dressing in accordance with the first embodiment of the invention and includes an enlargement bubble showing in partial cross-section how removal of the adhesive dressing causes the adhesive composition to extrude;

[0191] FIG. 3 is a perspective view showing removal of a light occlusive layer from the adhesive dressing in accordance with the first embodiment of the invention;

[0192] FIG. 4 is a perspective view showing the adhesive dressing in accordance with the first embodiment of the invention undergoing irradiation to effect switching of the adhesive;

[0193] FIG. 5 is a perspective view showing how the adhesive dressing in accordance with the first embodiment of the invention may be easily removed after switching of the adhesive;

[0194] FIG. 6 is a perspective view showing an incision being made through a surgical incision drape according to a second embodiment of the present invention;

[0195] FIG. 7 is a cross-sectional view through the surgical incision drape in accordance with the second embodiment of the invention;

[0196] FIG. 8 is a perspective view showing the act of removal of one of the release liners of the surgical incision drape according to the second embodiment of the present invention;

[0197] FIG. 9 is a perspective view of the surgical incision drape according to the second embodiment of the present invention in the act of being applied to the torso of a patient prior to surgery;

[0198] FIG. 10 is a perspective view of the surgical incision drape according to the second embodiment of the present invention in position on the torso of a patient and undergoing irradiation to effect cure of the adhesive;

[0199] FIG. 11 is a perspective view showing the act of removal of the remaining layer of the second release liner of the surgical incision drape according to the second embodiment of the invention;

[0200] FIG. 12 is a perspective view of a bacterial barrier in accordance with a third embodiment of the present invention in place on a patient's thigh, overlying a sutured wound;

[0201] FIG. 13 is a cross-sectional view of the bacterial barrier in accordance with the third embodiment of the present invention;

[0202] FIG. 14 is a perspective view showing the act of removal of the first release liner from the bacterial barrier according to the third embodiment of the invention;

[0203] FIG. 15 is a perspective view of the bacterial barrier according to the third embodiment of the present invention being applied to the thigh of a patient to cover a sutured wound;

[0204] FIG. 16 is a perspective view of the bacterial barrier according to the third embodiment of the invention in position on a patient's thigh and in the act of being irradiated to cure the adhesive;

[0205] FIG. 17 is a perspective view showing the act of removal of the siliconised release layer of the bacterial barrier of the third embodiment of the invention, leaving just the cured adhesive layer in place on the patient's thigh;

[0206] FIG. 18 is a perspective view showing a skin closure device according to a fourth embodiment of the invention in the act of being applied to a gaping wound on a patient's forearm as the skin edges are progressively brought together by a physician's thumb and fingers;

[0207] FIG. 19 is a cross-sectional view through the skin closure device in accordance with the fourth embodiment of the invention;

[0208] FIG. 20 is a perspective view showing the removal of the first release liner from the skin closure device in accordance with the fourth embodiment of the invention;

[0209] FIG. 21 is a perspective view of the skin closure device in accordance with the fourth embodiment of the invention in position on a patient's forearm and in the act of being irradiated to effect cure of the adhesive;

[0210] FIG. 22 is a perspective view showing the act of removal of the siliconised release layer of the skin closure device in accordance with the fourth embodiment of the invention, leaving just the cured adhesive layer in place on the patient's forearm;

[0211] FIG. 23 is a schematic diagram showing peel force direction relative to the plane of application of an adhesive test strip during peel force tests on skin.

DETAILED DESCRIPTION OF THE DRAWINGS

First Embodiment

[0212] A first embodiment of an adhesive medical product using the switchable adhesive composition of the present invention will now be described with reference to FIGS. 1 to 5. The adhesive medical product in this example is an adhesive medical dressing.

[0213] FIG. 1 is a cross-sectional view through an adhesive medical dressing 100 attached to a patient's skin 20. The adhesive medical dressing 100 is a multi-layer product having the following structure. The dressing 100 comprises a wound facing absorbent layer 130 disposed beneath a protective backing layer 140. At opposed edges 150, the backing layer 140 is provided with a switchable adhesive composition 170 which includes curable molecules that can be cross-linked under the influence of UV and/or visible light.

[0214] The backing layer 140 is provided with a light occlusive cover layer 180 which is releasably secured to the backing layer 140 by a weak adhesive 190. In an alternative arrangement, not shown here, the light occlusive cover layer 180 may be laminated to the backing layer 140. For ease of removal, the light occlusive cover layer 180 overlaps the backing layer 140 at its edges 110.

[0215] Since the adhesive composition 170 loses tackiness on exposure to visible and/or UV light, it is desirable that the adhesive 170 is not exposed to such light for a substantial period when the dressing 100 is applied to a patient. Thus, the adhesive composition 170 may be initially provided on the surface with release paper (see FIG. 3) which is preferably opaque to UV and visible light and which can be readily removed from the adhesive so that the dressing is ready for use when required.

[0216] FIG. 2 is a perspective view showing the removal of an adhesive dressing 100 from the forearm 14 of a patient, prior to switching of the switchable adhesive composition. This may be done, for example, when the adhesive dressing 100 needs to be repositioned.

[0217] Before switching, the adhesive composition 170 is very tacky and sticks the adhesive dressing 100 to the patient's skin 20 quite firmly. Hence, when the patient attempts to peel the dressing 100 from his forearm 14 for repositioning, his skin 20 becomes stretched and the dressing 100 initially remains attached to the skin.

[0218] However, if the adhesive dressing 100 is peeled further from the skin, the adhesive layer 170 becomes extruded and forms “fingers” or “strings” 171 that extend between the stretched skin 20 and the backing layer 140. Because the surface properties of the backing layer 140 are selected to have a stronger affinity for the adhesive composition than a patient's skin, the adhesive detaches from the patient's skin and the adhesive layer 170 is re-formed.

[0219] FIG. 3 is a perspective view showing the first step in preparing the adhesive dressing for removal by switching the adhesive composition to its non-tacky or low-tack state (as distinct from removal for repositioning purposes). FIG. 3 shows the patient removing the light occlusive cover layer 180 from the adhesive dressing 100 to expose the underlying adhesive composition layer 170. In this view, the wound pad 130 can also be seen.

[0220] The light occlusive cover layer 180 can be gripped at its edges 110 and peeled from the backing layer 140 to expose the underlying adhesive composition layer 170. Irradiation of the adhesive composition layer 170 with UV or visible light acts so as to generate free radicals that cause the curable molecules in the adhesive composition to undergo a curing reaction which, after a certain time (depending upon the adhesive composition mixture used), causes the adhesive composition 170 to lose its tackiness to such an extent that the dressing 100 can be removed very easily and without causing trauma to the patient.

[0221] In order that the removal of the light occlusive cover layer 180 does not itself cause trauma to the patient, the peel strength of the adhesive 190 adhering the light occlusive cover layer 180 to the backing layer 140 should be less than the peel strength of the adhesive 170 adhering the dressing 100 to the patient's skin 20.

[0222] FIG. 4 is a perspective view showing the adhesive dressing undergoing irradiation, in this example from a lamp 60, to effect cure of the curable molecules in the adhesive composition 170. The light from the lamp 60 (UV light or visible light, preferably long wavelength UV light) causes the photoinitiator in the adhesive composition 170 to generate free radicals that initiate curing of the curable molecules in the adhesive composition. Curing transforms (switches) the adhesive composition 170 from its tacky state to a non-tacky or low-tack state.

[0223] FIG. 5 is a perspective view showing how, after switching of the adhesive composition, the patient is easily able to remove adhesive dressing 100 from his forearm 14.

Second Embodiment

[0224] A second embodiment of an adhesive medical product using the switchable adhesive composition of the present invention will now be described with reference to FIGS. 6 to 11. The adhesive medical product in this example is a surgical incision drape.

[0225] FIG. 6 is a perspective view showing a scalpel 80 making an incision 70 in the torso of a patient 10 through the adhesive layer 202 of a surgical incision drape in accordance with a second embodiment of the invention. The physician's hand holding the scalpel has been omitted from FIG. 6 for clarity.

[0226] As shown in cross-sectional view in FIG. 7, the surgical incision drape 200 is a multiple layer article. The adhesive layer 202 is sandwiched between a first release liner 201 and a second release liner 205.

[0227] The first release liner 201 is a layer of siliconised plastic film, siliconised on the surface that faces the adhesive layer 202. In addition, the first release liner 201 is an occlusive material that prevents UV light and/or visible light passing through it and reaching the underlying adhesive layer 202.

[0228] The second release liner 205 is siliconised on the surface that faces the adhesive layer 202. Siliconised second release liner 205 is transparent to UV radiation and/or visible light. The siliconised second release liner 205 remains in place whilst the curable molecules in the adhesive layer 202 undergo curing by irradiation with UV light or by irradiation with visible light.

[0229] The occlusive first release liner 201 prevents inadvertent curing of the curable molecules in the adhesive layer 202 before the intended time by preventing the adhesive layer 202 from being exposed to UV light or visible light.

[0230] FIG. 8 is a perspective view of the surgical incision drape 200 showing the removal of the first release liner 201 to expose the underlying adhesive layer 202. The second release liner 205 is still in place on the other side of the adhesive layer 202. After removal of the first release liner 201, the surgical incision drape 200 is quickly positioned over the site of the intended incision to minimise exposure of the adhesive layer 202 to any radiation that might bring about curing of the adhesive, and also to minimise exposure of the uncured adhesive to atmospheric oxygen. Positioning of the surgical drape is discussed in the next paragraph.

[0231] FIG. 9 is a perspective view showing the remaining layers of the surgical incision drape being applied to the torso of a patient 10 by the hands 20, 21 of a physician or nurse. In this view, the second release liner 205 is uppermost and the adhesive layer 202 is the layer that is brought into contact with the skin of the patient. The siliconised release surface of the second release liner 205 is next to the adhesive layer 202. Because the curable molecules of the adhesive composition of the adhesive layer 202 are uncured at this stage, the adhesive layer 202 is still in its viscoelastic state. In this state, the adhesive is able to flow into surface irregularities and pores of the skin to ensure intimate contact between the surgical incision drape and the patient's skin.

[0232] FIG. 10 is a perspective view of the surgical incision drape in position on the torso of the patient 10 and undergoing irradiation, in this example from a lamp 60, to effect cure of the curable molecules in the adhesive composition of the adhesive layer 202. The light from the lamp 60 (UV light or visible light, preferably long wavelength UV light) passes through the transparent siliconised release liner 205 to the underlying adhesive layer 202 to initiate curing of the curable molecules in the adhesive composition. Curing transforms the adhesive composition layer from its viscoelastic state to an elastic state.

[0233] The transparent siliconised release liner 205 is retained in place over the adhesive layer 202 during the curing step to prevent oxygen in the ambient air from reacting with the adhesive composition as the curable molecules in the adhesive mixture undergo curing. Exposure to oxygen during curing causes the upper surface (i.e., the non skin contact surface) of the adhesive composition to remain slightly tacky after curing is complete. This slight tackiness is preferably avoided in a surgical incision drape because it may result in foreign objects (fluff, dust, etc.) becoming stuck to the surgical incision drape. Also, the slight tackiness may increase the possibility that parts of the surgical incision drape will be prematurely removed, for example by being abraded by contact with the physician's gloves. By retaining the siliconised release liner 205 in place over the adhesive layer 202 and curing the curable molecules in the adhesive layer 202 by irradiation through the siliconised release liner 205, the occurrence of surface tackiness in the cured adhesive composition layer is avoided.

[0234] FIG. 11 is a perspective view showing the physician's hand 21 removing the siliconised release liner 205 from the adhesive layer 202 of the surgical incision drape after the curable molecules in the adhesive composition of the adhesive layer 202 have been cured. After removal of the siliconised release liner 205, only the cured adhesive composition layer 202 remains on the patient's skin.

[0235] Preferably, the cured adhesive composition layer is transparent so that the physician can see the site of the intended incision and any markings that may have been made on the patient's skin prior to commencement of the surgical procedure.

[0236] As mentioned above, in the cured state, the adhesive composition of the adhesive layer 202 is transformed from its initial viscoelastic state to an elastic state. In this state, the adhesive remains firmly stuck to the patient's skin but, by virtue of its elasticity, the adhesive layer is able to move with the patient's skin as the skin moves. Moreover, the cured adhesive layer is an effective barrier to bacteria. Any bacteria that remained on the surface of the patient's skin after the preliminary antibacterial swabbing step become immobilised in the cured adhesive layer and migration to the incision site is thereby inhibited.

[0237] Referring again to FIG. 6, the cured adhesive composition layer 202 of the surgical incision drape remains in position on the patient's skin and is incised, along with the patient's skin, when a physician (not depicted in FIG. 6) makes an incision 70 with a scalpel 80.

[0238] After surgery, the adhesive layer 202 at the edges of the incision may be peeled away so that the incision can be closed without interposition of any adhesive layer material between the mating skin edges. Closure of the incision may be performed in the usual way, for example by suturing or by means of surgical staples or surgical tapes. Alternatively, the adhesive composition layer 202 may be left in place during closure of the incision. If left in place, the adhesive composition layer 202 is gradually sloughed away with the shedding of skin cells from the surface of the patient's skin as healing takes place.

Third Embodiment

[0239] A third embodiment of an adhesive medical product using the switchable adhesive composition of the present invention will now be described with reference to FIGS. 12 to 17. The adhesive medical product in this example is a bacterial barrier, a type of wound covering that is similar to a dressing but having no absorbent wound pad.

[0240] FIG. 12 is a perspective view showing a bacterial barrier 300 in accordance with the third embodiment of the invention in place on a patient's thigh 12, overlying a sutured wound 13. The bacterial barrier 300 in this view consists of a single layer 302 of cured adhesive composition, as will be explained in more detail below.

[0241] As shown in cross-sectional view in FIG. 13, the bacterial barrier 300 is a multiple layer article. The adhesive layer 302 is sandwiched between a first release liner 301 and a second release liner 303.

[0242] The first release liner 301 is a layer of siliconised plastic film, siliconised on the surface that faces the adhesive layer 302. In addition, the first release liner 301 is an occlusive material that prevents UV light and/or visible light passing through it and reaching the underlying adhesive layer 302.

[0243] The second release liner 305 is also siliconised on the surface that faces the adhesive layer 302. Siliconised release liner 305 is transparent to UV radiation and visible light. The siliconised second release liner 305 remains in place whilst the curable molecules in the adhesive layer 302 undergo curing by irradiation with UV light or by irradiation with visible light.

[0244] The occlusive first release liner 301 prevents inadvertent curing of the curable molecules in the adhesive layer 302 before the intended time by preventing the adhesive layer 302 from being exposed to UV light or visible light.

[0245] FIG. 14 is a perspective view of the bacterial barrier 300 showing the removal of the first release liner 301 to expose the underlying adhesive layer 302. The second release liner 305, comprising its siliconised release surface, is still in place on the other side of the adhesive layer 302. After removal of the first release liner 301, the bacterial barrier 300 is quickly positioned over the site of the wound to be covered (see FIG. 12) so as to minimise exposure of the adhesive layer 302 to any radiation that might bring about curing of the curable molecules in the adhesive composition, and also to minimise exposure of the uncured adhesive composition layer to atmospheric oxygen. Positioning of the bacterial barrier is discussed in the next paragraph.

[0246] FIG. 15 is a perspective view showing the remaining layers of the bacterial barrier being applied to the thigh 12 of a patient by the hands 20, 21 of a nurse or physician. In this view, the second release liner 305 is uppermost and the adhesive layer 302 is the layer that is brought into contact with the skin of the patient. The siliconised release surface of the second release liner 305 is next to the adhesive layer 302. Because the curable molecules of the adhesive composition of the adhesive layer are uncured at this stage, the adhesive layer 302 is still in its viscoelastic state. In this state, the adhesive is able to flow into surface irregularities and pores of the skin to ensure intimate contact between the bacterial barrier in a surface and the patient's skin.

[0247] FIG. 16 is a perspective view of the bacterial barrier 300 in position on the thigh 12 of the patient and undergoing irradiation, in this example from a lamp 60, to effect cure of the curable molecules in the adhesive composition of the adhesive layer 302. The light from the lamp 60 (UV light or visible light, preferably long wavelength UV light) passes through the transparent siliconised second release liner 305 to the underlying adhesive layer 302 to initiate curing of the curable molecules in the adhesive composition. Curing transforms the adhesive composition layer from its viscoelastic state to an elastic state.

[0248] The transparent siliconised release liner 305 is retained in place over the adhesive layer 302 during the curing step to prevent oxygen in the ambient air from reacting with the adhesive composition as the curable molecules in the adhesive mixture undergo curing. Exposure to oxygen during curing causes the upper surface (i.e., the non skin contact surface) of the adhesive composition layer to remain slightly tacky after curing is complete. This slight tackiness is preferably avoided in a bacterial barrier because it may result in foreign objects (fluff, dust, etc.) becoming stuck to the bacterial barrier. Also, the slight tackiness may cause the bacterial barrier to be unintentionally removed, for example by being abraded by contact with the patient's clothes. By retaining the siliconised release liner 305 in place over the adhesive layer 302 and curing the curable molecules in the adhesive layer 302 by irradiation through the siliconised release liner 305, the occurrence of surface tackiness in the cured adhesive composition layer is avoided.

[0249] FIG. 17 is a perspective view showing the physician's or nurse's hand 21 removing the siliconised second release liner 305 from the adhesive layer 302 of the bacterial barrier after the curable molecules in the adhesive composition of the adhesive layer 302 have been cured. After removal of the siliconised second release liner 305, only the cured adhesive composition layer 302 remains on the patient's thigh 12.

[0250] As mentioned above, in the cured state, the adhesive composition of the adhesive layer 302 is transformed from its initial viscoelastic state to an elastic state. In this state, the adhesive layer remains firmly stuck to the patient's skin but, by virtue of its elasticity, the adhesive layer is able to move with the patient's skin as the patient moves. The cured adhesive composition layer is an effective barrier to bacteria. Any bacteria that remained on the surface of the patient's skin after preliminary antibacterial swabbing become immobilised in the cured adhesive composition layer and migration to the site of the wound is thereby inhibited. The bacterial barrier is also a mechanical barrier against dirt and other foreign particles and substances.

[0251] Referring again to FIG. 12, the cured adhesive composition layer 302 of the bacterial barrier remains in position on the patient's skin over the wound 13. In practice, the wound 13 may be a wound that has arisen as a result of trauma to the patient or, as discussed above in relation to the second embodiment, the wound 13 may be the site of a surgeon's incision which has been sutured, stapled or taped closed after completion of the surgery.

[0252] The bacterial barrier is breathable and allows moisture to escape from the pores of the patient's skin. Moreover, the cured adhesive composition layer 302 has good water resistance and does not require special care by the patient when bathing or showering. Preferably, the cured adhesive composition layer 302 is transparent to allow inspection of the underlying skin surface without needing to remove the bacterial barrier.

[0253] The adhesive composition layer 302 is gradually sloughed away with the shedding of skin cells from the surface of the patient's skin as wound healing progresses.

Fourth Embodiment

[0254] A fourth embodiment of an adhesive medical product using the switchable adhesive composition of the present invention will now be described with reference to FIGS. 18 to 22. The adhesive medical product in this example is a skin closure film.

[0255] FIG. 18 is a perspective view showing a skin closure film 400 in accordance with the fourth embodiment of the invention being applied in place on a patient's forearm 14 for closing a gaping wound 15. The skin edges of the gaping wound 15 are shown being progressively urged together by the physician's or nurse's hand 21 as the skin closure film 400 is applied over the newly closed part of the wound 15. The second hand that the physician or nurse uses to apply the skin closure film 400 progressively to the newly closed part of the wound 15 is omitted from this view for reasons of clarity. The skin closure film 400 applied at this stage is a multiple layer product, as will be explained in more detail below.

[0256] As shown in cross-sectional view in FIG. 19, the skin closure laminate 400 is a multiple layer article. The adhesive layer 400 is sandwiched between a first release liner 401 and a second release liner 405.

[0257] The first release liner 401 is a layer of siliconised plastic film, siliconised on the surface that faces the adhesive layer 402. In addition, the first release liner 401 is an occlusive material that prevents UV light and/or visible light passing through it and reaching the underlying adhesive layer 402.

[0258] The second release liner 405 is also siliconised on the surface that faces the adhesive layer 402. Siliconised release liner 405 is transparent to UV radiation and visible light.

[0259] The occlusive first release liner 401 prevents inadvertent curing of the curable molecules in the adhesive layer 402 before the intended time by preventing the adhesive layer 402 from being exposed to UV light or visible light.

[0260] FIG. 20 is a perspective view of the skin closure laminate 400 showing the removal of the first release liner 401 to uncover the underlying adhesive layer 402. The second release liner 405 is still in place on the other side of the adhesive layer 402. After removal of the first release liner 401, the skin closure laminate 400 is preferably quickly positioned over the site of the wound to be closed (see FIG. 18) so as to minimise exposure of the adhesive layer 402 to any radiation that might bring about curing of the curable molecules in the adhesive, and also to minimise exposure of the uncured adhesive composition to atmospheric oxygen. Positioning of the skin closure laminate is discussed in the next paragraph.

[0261] Returning to FIG. 18, this is a perspective view showing the remaining layers of the skin closure laminate being applied to the forearm 14 of a patient by a nurse or physician. In this view, the second release liner 405 is uppermost and the adhesive layer 402 is the layer that is brought into contact with the skin of the patient. Because the curable molecules in the adhesive composition of the adhesive layer are uncured at this stage, the adhesive layer 402 is still in its gelled state. In this state, the adhesive is able to flow into surface irregularities and pores of the skin to ensure intimate contact between the skin closure film and the patient's skin.

[0262] The adhesive layer 402 is beneath the siliconised second release liner 405 and in contact with the skin of the patient's forearm 14. The second siliconised release layer 405 is transparent to UV light and/or visible light, for reasons which will be explained below.

[0263] FIG. 21 is a perspective view of the skin closure laminate 400 in position on the forearm 14 of the patient and undergoing irradiation, in this example from a lamp 60, to effect cure of the curable molecules in the adhesive composition of the adhesive layer 402. The light from the lamp 60 (UV light or visible light—long wavelength UV is the preferred form of UV light) passes through the transparent siliconised release liner 405 to the underlying adhesive layer 402 to initiate curing of the curable molecules in the adhesive composition. Curing transforms the adhesive composition layer from its viscoelastic state to an elastic state.

[0264] The transparent siliconised release liner 405 is retained in place over the adhesive layer 402 during the curing step to prevent oxygen in the ambient air from reacting with the adhesive as the curable molecules in the adhesive mixture undergo curing. Exposure to oxygen during curing causes the upper surface (i.e., the non skin contact surface) of the adhesive composition layer 402 to remain slightly tacky after curing is complete. This slight tackiness is preferably avoided in a skin closure product because it may result in foreign objects (fluff, dust, etc.) becoming stuck to the skin closure film. Also, the slight tackiness may cause the skin closure film to be prematurely removed, for example by being abraded by contact with the patient's clothes. By retaining the siliconised release liner 405 in place over the adhesive layer 402 and curing the curable molecules in the adhesive layer 402 by irradiation through the siliconised release liner 405, the occurrence of surface tackiness in the cured adhesive composition layer is avoided.

[0265] FIG. 22 is a perspective view showing the physician's or nurse's hand 21 removing the siliconised release liner 405 from the adhesive layer 402 of the skin closure film after the curable molecules in the adhesive composition of the adhesive layer 402 have been cured. After removal of the siliconised release liner 405, only the cured adhesive composition layer 402 remains on the patient's forearm 14.

[0266] As mentioned above, in the cured state, the adhesive composition of the adhesive layer 402 is transformed from its initial viscoelastic state to an elastic state. In the elastic state, the adhesive composition layer 402 remains firmly stuck to the patient's skin but, by virtue of its elasticity, the adhesive layer is able to move with the patient's skin as the patient moves. The cured adhesive composition layer is an effective barrier to bacteria. Any bacteria that remained on the surface of the patient's skin after preliminary antibacterial swabbing become immobilised in the cured adhesive composition layer and migration to the site of the wound is thereby inhibited. The cured adhesive composition layer 402 is also a mechanical barrier against dirt and other foreign particles and substances.

[0267] The cured adhesive composition layer 402 of the skin closure film remains in position on the patient's skin over the wound 15. The skin closure film is breathable and allows moisture, including sweat, to escape from the pores of the patient's skin. Moreover, the cured adhesive composition layer 402 has good water resistance and does not require special care by the patient when bathing or showering. Preferably, the cured adhesive composition layer 402 is transparent to allow inspection of the underlying skin surface without needing to remove the skin closure film.

[0268] The adhesive composition layer 402 is gradually sloughed away with the shedding of skin cells from the surface of the patient's skin as wound healing progresses.

[0269] Although the first, second, third and fourth embodiments have been described above in terms of a particular construction for the laminated product, the present invention is not limited to such a construction.

[0270] For example, at least the first carrier layer or the first release liner may have a tab that is not coated with the adhesive composition, the tab serving to facilitate handling of the laminated product so that the carrier layer or the release liner can be separated from the adhesive composition layer without the adhesive composition layer coming into contact with the patient's fingers (for example, when a patient is applying a dressing to himself) or the physician's or nurse's fingers or gloves (for example, when a dressing, a surgical incision drape, a bacterial barrier or a wound closure device is being applied by a medical practitioner).

[0271] A non-adhesive-coated tab may also be provided on the second carrier layer of the wound dressing described in the first embodiment to assist in removal of the second carrier layer with the film of switched adhesive after the curable molecules in the adhesive composition layer have undergone their curing reaction to transform the adhesive composition layer from its tacky state to its non-tacky or low-tack state.

[0272] Similarly, a non-adhesive-coated tab may also be provided on the second release liner of the surgical incision drape, the bacterial barrier or the wound closure device described in the second to fourth embodiments to assist in removal of the second release liner from the adhesive composition layer after the curable molecules in the adhesive composition layer have undergone their curing reaction to transform the adhesive composition layer from its viscoelastic state to its elastic state.

[0273] The first release liner does not need to be formed of a light occlusive material. If the packaging for the laminated product is light occlusive, the first release liner may be transparent. However, in these circumstances, the first release liner will need to be removed quickly and the laminated product will need to be applied quickly to the patient's skin if the photoinitiator in the adhesive composition layer is activated by visible light. The need for quick deployment of the laminated product is not as critical for adhesive composition layers that use a photoinitiator responsive to UV light but not responsive to visible light.

[0274] Similarly, the second release liner does not need to have a light occlusive layer. However, if the second release liner in the second, third and fourth embodiments described above consists of two layers (a light occlusive layer as well as siliconised release liners 205, 305 and 405), the layers may be stuck together using a low peel strength adhesive. As an alternative, they may be heat laminated together.

[0275] The release liners may be siliconised paper rather than siliconised plastic films.

[0276] 100% transparency is not essential for the second carrier layer or the second release liner. It may be semi-transparent provided that it allows sufficient light (UV light and/or visible light) to pass through it to enable photoinitiated radical reaction of the curable molecules in the underlying adhesive composition layer.

EXAMPLES

[0277] The invention will now be further illustrated with reference to Examples. Firstly, we will describe how exemplary oligomeric curable molecules for use in the switchable adhesive compositions of the present invention may be prepared.

Example of Synthesized Acrylate Oligomer

[0278] In Example 1 below, the constituents are listed in the order:

TABLE-US-00002 A Isocyanate B Solvent, if present C Catalyst D Stabilizer for preventing premature switch during storage E Hydroxyl containing methacrylate ester.

Example 1

[0279]

TABLE-US-00003 Component Amount (g) A Desmodur N3900 353.5 B Ethyl acetate 234 C DBTDL 0.314 D Irganox 1010 2.02 E1 Bisomer PPM5 LI 339.5 E2 Bisomer HPMA 144.1

Reaction 1. Synthesis of Methacrylated Oligomers

[0280] The reaction was carried out at 60° C. under stirring. The isocyanate-containing component, catalyst (if not added previously), solvent and inhibitor were placed in a reaction vessel and stirred. Then the hydroxyl-containing methacrylic ester was added slowly to avoid a steep rise in temperature and in order to maintain the reaction temperature below 70° C. Since two different hydroxyl-containing methacrylic esters were used, the one with the higher molecular weight was added first. The lower molecular weight hydroxyl-containing methacrylic ester was added later, after confirming by GPC measurements that the higher molecular weight hydroxyl-containing methacrylic ester had completely reacted. After all reactants been added, the temperature was raised to 70° C. and the mixture was left under stirring for a period of two hours.

[0281] Since the formation of the polyurethane adhesive also is based on the reaction between an isocyanate and a hydroxyl component, it is necessary that the oligomer is synthesized in a manner so that residual amounts of isocyanate or hydroxyl groups are kept to a minimum. In the synthesis described here, a slight excess of the lower molecular weight hydroxypropyl methacrylate was used, which was removed in a rotary evaporator at a temperature of 80° C. under an air inlet so that a pressure of around 2 mbar could be with maintained during the evaporation process. The removal of hydroxypropyl methacrylate was continued until the area representing hydroxypropyl methacrylate in the GPC chromatogram decreased to about 0.1%.

Examples of Switchable Adhesive Compositions Incorporating the Oligomeric Curable Molecules of Example 1

[0282] Examples 2 to 6 are examples of switchable adhesive compositions in accordance with the present invention formulated to include “mixed-in” curable oligomers from Example 1 above.

[0283] In Examples 2 to 6 below, the constituents are listed in the order:

TABLE-US-00004 F Baymedix AR602 G curable molecules/oligomer H photoinitiator I Catalyst J Baymedix AP501

Example 2

[0284]

TABLE-US-00005 Component Amount (g) F Baymedix AR602 20.0 G Oligomer from Example 1 19.2 H Irgacure 369 0.39 I Tin(II) 2-ethylhexanoate 0.091 J Baymedix AP501 1.92

Example 3

[0285]

TABLE-US-00006 Component Amount (g) F Baymedix AR602 20.0 G Oligomer from Example 1 19.2 H Irgacure 369 0.39 I Tin(II) 2-ethylhexanoate 0.11 J Baymedix AP501 2.02

Example 4

[0286]

TABLE-US-00007 Component Amount (g) F Baymedix AR602 20.0 G Oligomer from Example 1 19.0 H Irgacure 369 0.37 I Tin(II) 2-ethylhexanoate 0.064 J Baymedix AP501 2.13

Example 5

[0287]

TABLE-US-00008 Component Amount (g) F Baymedix AR602 20.0 G Oligomer from Example 1 19.2 H Irgacure 369 0.39 I Tin(II) 2-ethylhexanoate 0.11 J Baymedix AP501 2.22

Example 6

[0288]

TABLE-US-00009 Component Amount (g) F Baymedix AR602 20.0 G Oligomer from Example 1 19.2 H Irgacure 369 0.39 I Tin(II) 2-ethylhexanoate 0.11 J Baymedix AP501 2.33

Reaction 2. Preparation of Switchable Adhesive Compositions

[0289] All components in Examples 2 to 6 except for Baymedix AP501 were loaded into a sealable glass jar and mixed to a homogenous solution using a magnetic stirrer over a period of approximately 60 minutes under protection from ultraviolet sources.

[0290] In preparation for coating, the solution was vacuum boiled in order to remove all present air bubbles, whereafter Baymedix AP501 was gently blended into the solution avoiding any new dispersal of air. After stirring the solution for approximately 30 minute or until it had reached a viscosity similar to syrup, the resulting adhesive solution was then spread onto a release liner using a spreader having a gauge of 150 μm and left to dry at room temperature for 10 minutes.

[0291] The adhesive coating was then further dried in a ventilated fan assisted oven at 110° C. for an additional 10 minutes. After drying, the thickness of the adhesive coating was about 60-80 μm.

Peel Force Measurements

[0292] For one set of peeling studies, a 23 μm Hostaphan RNK 2600 (polyester) film was transferred to the exposed side of the adhesive in preparation for peel force measurements.

[0293] For a second set of peeling studies, a medical film was transferred to the exposed side of the adhesive. The carrier film attached to the flexible medical film was removed after attaching the adhesive laminate to skin.

[0294] Peel strengths were determined after a dwell time of 20 minutes using an Instron 5943 testing rig, equipped with a 100 N load cell, according to FINAT test method FTM1, with the exception that high density polyethylene (HDPE) panels were used as the substrate surface and that a peeling rate of 100 mm/min crosshead speed 200 mm/s was used in order to collect all of the necessary data within the time frame of one peel force measurement.

[0295] Unswitched peel force was measured before exposing the adhesive to light while adhesive switching was achieved by exposing the adhesive film (adhered to the HDPE plate) to light through the PET carrier film backing with a light intensity of approximately 5 mW/cm.sup.2 from a XeLED-Ni3UV-R4-365-E27-SS lamp having a narrow spectrum around 365 nm. Switching times for the different coatings were measured as the time between the starting time of irradiation and the time when the substantially instantaneous loss of tack occurred, during a continuous peel strength test of about 1.5 minutes (i.e., the adhesive was peeled for a period of time whilst being irradiated). This while the switched peel force was measured after that the peel force had reached a plateau value, which usually occurred 5-10 seconds after the switch time. Peel strengths and switch times were measured in quadruple and the average values of switch time and peel strength (before and after switch) were calculated.

Peel Force Measurements on Skin

[0296] One forearm of a group of volunteers was washed gently with water and ordinary soap and dried a few minutes before application of four test strips onto the volar aspect of each volunteer's cleaned forearm. The test strips consisted of the adhesive to be tested sandwiched in between a release liner (Transparent PET Release film, 50 um, silicone 1720, quality 1876) and a medical film (Code 48938), and measured 20×100 mm. The strips were applied in a room protected from any UV light. All strips were attached by rolling a standard Finat test roller three times forward and back over each tape at a speed of lcm per second, thus firming them to the skin in a controlled manner.

[0297] After one hour, two strips where peeled at a 135 degree angle using an Instron 5943 tensile tester machine with a speed of 600 mm/minute according to the illustration in FIG. 23.

[0298] The remaining two strips were then illuminated for about 10 seconds to effect switching using a XeLED-Ni3UV-R4-365-E27-SS light source held at a distance of approximately 20 cm from the strips. The peel forces were recorded and the average values were calculated.

Test Results

[0299]

TABLE-US-00010 TABLE 2 Adhesive composition peel force and switch properties Tests performed on HDPE Tests performed on skin Peel force Peel force Peel force Peel force Ex- before after Switch before after ample switch switch time switch switch no. (N/25 mm) (N/25 mm) (s) (N/20 mm) (N/20 mm) 2 3.09 0.038 1.9 2.69 0.16 3 1.78 0.036 1.8 1.96 0.15 4 1.54 0.034 2 1.55 0.1 5 1.58 0.038 2 0.96 0.09 6 1.02 0.033 2.1 0.65 0.07

[0300] From Table 2 above it can be seen that the initial peel force can be varied in a controlled fashion by adjusting the amount of the curing component Baymedix AP 501 from a low to a high value. Even though the data is not presented here, the addition of higher or lower amounts of the curing component Baymedix AP 501 than used in Examples 2 to 6 results in initial peel forces outside the ranges listed in the table.

Example of Synthesized Isocyanate Methacrylate Oligomer

[0301] In the Example below, the constituents are listed in the order:

TABLE-US-00011 K Isocyanate L Solvent, if present M Catalyst N Stabilizer for preventing premature switch during storage O Hydroxyl containing methacrylate ester.

Example 7

[0302]

TABLE-US-00012 Component Amount (g) K Desmodur N3600 20.3 L Ethyl acetate 6.01 M Bismuth (III) neodecanoate 0.086 N Irganox 1010 0.078 O Bisomer HPMA 9.06

Reaction 3. Preparation of Isocyanate Functional Methacrylated Oligomers

[0303] The reaction was carried out at room temperature under stirring. All the components except for the hydroxyl functional methacrylate were added into a reagent bottle and mixed into a homogeneous solution, after which the hydroxyl functional methacrylate was added. The mixture was left overnight for the reaction to be completed. After confirming by GPC measurements that no residual hydroxyl functional acrylate was present, the isocyanate functional acrylate oligomer was ready to be used.

Gel Permeation Chromatography (GPC)

[0304] Samples were diluted with tetrahydrofuran in a ratio of 1:100 and injected in an amount of 20 μl into the injection valve of a Waters HPLC 1515 pump using a flow rate of 1 ml/min of tetrahydrofuran. The instrument was equipped with Styragel HR3 and HR1 columns connected to a Waters 2414 refractive index detector. Calibration was done with polystyrene standards.

Examples of Switchable Adhesive Compositions Incorporating the Oligomeric Curable Molecules of Example 7

[0305] Examples 8 to 10 are examples of switchable adhesive compositions in accordance with the present invention formulated to include “partially bound-in” oligomers from Example 7 above.

[0306] In Examples 8 to 10 below, the constituents are listed in the order:

TABLE-US-00013 F Baymedix AR602 P Curable molecules/oligomer from example 7 H Photo initiator L Ethyl acetate

Example 8

[0307]

TABLE-US-00014 Component Amount (g) F Baymedix AR602 30.1 P Oligomer from Example 7 8.27 H Irgacure 369 0.37 L Ethyl acetate 3.0

Example 9

[0308]

TABLE-US-00015 Component Amount (g) F Baymedix AR602 30.2 P Oligomer from Example 7 7.05 H Irgacure 369 0.359 L Ethyl acetate 3.0

Example 10

[0309]

TABLE-US-00016 Component Amount (g) F Baymedix AR602 30.1 P Oligomer from Example 7 7.51 H Irgacure 369 0.359 L Ethyl acetate 3.0

Test Results

[0310] In Table 3, test results are presented for Examples 8 to 10.

TABLE-US-00017 TABLE 3 Adhesive composition peel force and switch properties Tests performed on HOPE Tests performed on skin Peel force Peel force Switch Peel force Peel force Example before switch after switch time before switch after switch no. (N/25 mm) (N/25 mm) (s) (N/20 mm) (N/20 mm) 8 0.64 0.016 1.6 0.93 0.07 9 1.93 0.017 1.5 2.44 0.15 10 1.42 0.016 1.4 1.63 0.13

Examples of Switchable Adhesive Compositions Incorporating Curable Moieties Fully Bound-In to a Polyurethane Adhesive Component

[0311] Following are examples of switchable adhesive compositions in accordance with the present invention formulated to include “fully bound-in” curable moieties that are bound to the polyurethane polyol backbone.

Reaction 4. Synthesis of Methacrylated Polyol

[0312] The reaction was carried out at room temperature under stirring and all the reactants except for diisocyanate were added at the same time into a reagent bottle and left over night for the reaction to be completed.

Reaction 5. Preparation of Switchable Adhesive Compositions

[0313] After confirming by GPC measurements that no residual acrylated isocyanate was present, the solution was vacuum boiled in order to remove all present air bubbles, whereafter diisocyanate was gently blended into the solution avoiding any new dispersal of air. After stirring the solution for approximately 10 minute or until it had reached a viscosity similar to syrup, the resulting adhesive solution was then spread onto a release liner using a spreader having a gauge of 150 μm and left to dry at room temperature for 10 minutes.

[0314] The adhesive coating was then further dried in a ventilated fan assisted oven at 110° C. for an additional 10 minutes. After drying, the thickness of the adhesive coating was about 60-80 μm.

Examples of Switchable Adhesives Incorporating Polyol with “Fully Bound-In” Methacrylate Moieties

[0315] In Examples 11 to 13 below, the constituents are listed in the order:

TABLE-US-00018 F Polyol L Solvent M Catalyst Q Acrylated isocyanate H Photo initiator J Diisocyanate

Example 11

[0316]

TABLE-US-00019 Component Amount (g) F Baymedix AR602 30.1 L Ethyl acetate 6.0 M Bismuth (III) neodecanoate 0.043 Q 2-Isocyanatoethyl methacrylate 1.30 H Irgacure 369 0.372 J Baymedix AP501 2.95

Example 12

[0317]

TABLE-US-00020 Component Amount (g) F Baymedix AR602 30.2 L Ethyl acetate 6.0 M Bismuth (III) neodecanoate 0.038 Q 2-Isocyanatoethyl methacrylate 1.14 H Irgacure 369 0.351 J Baymedix AP501 3.20

Example 13

[0318]

TABLE-US-00021 Component Amount (g) F Baymedix AR602 30.1 L Ethyl acetate 6.0 M Bismuth (III) neodecanoate 0.058 Q 2-Isocyanatoethyl methacrylate 1.02 H Irgacure 369 0.345 J Baymedix AP501 2.88

Test Results

[0319] In table 4, the test results are presented for Examples 11 to 13.

TABLE-US-00022 TABLE 4 Adhesive composition peel force and switch properties Tests performed on HDPE Tests performed on skin Peel force Peel force Switch Peel force Peel force Example before switch after switch time before switch after switch no. (N/25 mm) (N/25 mm) (s) (N/20 mm) (N/20 mm) 11 1.80 0.014 1.4 1.83 0.12 12 0.24 0.013 1.4 0.64 0.078 13 2.29 0.010 1.4 2.37 0.11

Non-Medical Applications

[0320] The present invention is not limited to use in adhesive medical products. Examples of other technical applications are listed below in Table 5.

TABLE-US-00023 TABLE 5 Non-medical applications Application Format Description Labels, posters or A two or three-layer Labels comprising an Notices product. adhesive according to the invention can be used in product tags, pricing tags, advertisement posters put onto the varnish of vehicles. There will result a strong fixation and an easy removal without any adhesive residues left on the surface Or, in the case of a two layer film, easily removable residues after switching the adhesive. Protection Films A two or three-layer Goods may get scratched product. during transportation, storage, handling etc; by using an adhesive according to the invention in combination with protective films, the goods will be protected from scratches and similar surface damage. When removing the film, no strong peeling force is necessary and, in the case of a three layer film, no adhesive residues left on the goods; or, in the case of a two layer film, easily removable residues after switching the adhesive. Fixation of A three-layer Products and/or product Sensitive Parts product. parts that are very fragile During and/or have a sensitive Manufacture or surface can be adhered to a Transport substrate using an adhesive according to the present invention during transportation or manufacturing processes for achieving a very accurate position and fixation; after processing, the product can still be detached from the adhesive when desired without high peel forces and without leaving residues on its surface. Shop Floor or Wall A two-layer product. Using an adhesive according Marker Labels to the present invention on shop floor marker labels in different shapes, a very strong fixation to the floor or wall surface is possible. When the marker label is removed, adhesive residues may be left on the surface which are very easy to rub off when switched. Wallpaper A three-layer Using an adhesive according product. to the invention on wall paper, a very strong fixation to the wall is possible. When the wallpaper is removed after switching the adhesive, the wall surface is left without any damage or residuals. Masking or A two or three-layer Using an adhesive according Fixation Tapes product. to the invention for the (fixation of purpose of temporary non-fragile or non- fixation or masking, a very delicate articles) strong fixation to the surface is possible. When the tape is removed after switching the adhesive using a three layer design, the surface is left without any residues or, in the case of a two layer film, easily removable residues after switching the adhesive. De-bond on A two or three-layer Using an adhesive according demand (DOD) product. to the invention for the applications, such purpose of strongly attaching as opening of different components into packages and product or package. When recycling of the product or package needs different materials to be disassembled, the light in a product by occlusive layer is removed detaching them and, after switching the after the end of adhesive, the different parts service lifetime. can easily be detached. Should adhesive residues be left on the component or product surface, these can be easily removed after switching the adhesive.

TABLE-US-00024 TABLE 6 Table of Suppliers Component Description Company Desmodur N Hexamethylene polyisocyanate Covestro UK Ltd. 3900 (iminooxadiazindione) NCO content 23.7 w/w % Desmodur N Hexamethylene polyisocyanate Covestro UK Ltd. 3600 (isocyanurate) NCO content 23.0 w/w % Bisomer Hydroxypropyl methacrylate GEO Specialty HPMA Chemicals UK Ltd Bisomer Polypropyleneglycol GEO Specialty PPM5 LI monomethacrylate Chemicals UK Ltd Hydroxyl value 149.6 mgKOH/g Irganox Pentaerythritol Tetrakis(3-(3,5-di- BASF AG 1010 tert-butyl-4-hydroxyphenyl) propionate Irgacure 369 2-Benzyl-2-dimethylamino-1-(4- BASF AG morpholinophenyl)-butanone-1 Code 48938 Medical film Shanghai ISO Medical Products Co. Ltd HDPE Panels for peel test measurements ChemInstrument Inc. panels Hostaphan Polyester film Mitsubishi Polyester RNK 2600 Film GmbH Transparent Release liner Huhtamaki Oyj PET Release film, 50 um, silicone 1720, quality 1876 Baymedix Polyether polyol based on a tetra- Covestro UK Ltd. AR 602 functional starter molecule. Hydroxyl value 34 mgKOH/g Baymedix Aliphatic NCO-terminated Covestro UK Ltd. AP501 prepolymer based on hexamethylene diisocyanate. NCO content 12.9 w/w % Catalyst Dibutyl tin dilaurate Sigma Aldrich Catalyst Tin(II) 2-ethylhexanoate Sigma Aldrich Catalyst Bismuth (III) neodecanoate Sigma Aldrich XeLED- LED ultra violet light source Xenopus Electronix Ni3UV-R4- 365-E27-SS Isocyanate 2-Isocyanatoethyl methacrylate Sigma Aldrich methacrylate