Adhesive composition

Abstract

The present invention relates to an adhesive composition comprising the reaction product of (A) and (B): (A) a polymer component having a weight average molecular weight in the range of from 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, where X represents a number having a value of at least 2; (B) a crosslinking component obtained by reacting (i) with at least one of (ii) and (iii): (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functions per molecule; (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group comprising an active hydrogen atom; (iii) at least one compound comprising nucleophilic functional groups comprising active hydrogen atoms and which does not comprise functional groups curable by free radical polymerization. The total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is in the range of 0.1 to 0.7; and the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.8. The invention also relates to a method of preparing the adhesive polyurethane composition, an adhesive medical device comprising the adhesive composition and a method of treating a wound using the adhesive medical device.

Description

[0001] introduction

[0002] The present invention relates to pressure-sensitive adhesive compositions. The present invention particularly relates to adhesive compositions having low cytotoxicity, which are therefore suitable for medical applications in which the adhesive composition directly contacts the skin. The present invention also relates to methods for preparing the adhesive composition and articles comprising the adhesive composition.

[0003] The adhesive compositions of the present invention can be used with a variety of substrates, but given their low cytotoxicity, they are particularly useful for application to the skin.

[0004] The adhesive composition of the present invention may include a curable portion and thus may be converted from a tacky state to a substantially non-tacky state upon initiation of curing of the curable portion by irradiation with light of a suitable wavelength. The loss of tack is evidenced by a decrease in the peel strength of the converted adhesive compared to the unconverted adhesive.

[0005] The switchable adhesive composition is particularly suitable for medical products applied to the patient's skin. Before switching, the adhesive forms a strong and durable bond with the skin. After switching, in a low-tack state, the medical product can be easily removed without causing pain or damage to the underlying tissue. This is particularly useful for injured patients or patients with long-term conditions who need repeated dressings, as well as patients with fragile skin (such as infants and the elderly). Background of the Invention

[0007] Many medical devices contain a pressure-sensitive adhesive layer to enable the device to adhere to the patient's skin. Examples of such medical devices include dressings, surgical drapes, and medical tapes. The adhesive used in medical devices must be sticky enough to form a strong bond with the skin that can resist peeling or accidental removal during the use of the medical product. However, when the dressing or bandage is removed from the skin, conventional adhesives with these properties can cause trauma and / or pain to the patient. This is especially true for patients with chronic conditions (e.g., ostomy patients) who need to repeatedly apply adhesive dressings to the same part of the body over a long period of time. This is also true for patients with fragile skin (especially the elderly and infants).

[0008] A class of "switchable" pressure sensitive adhesives has been developed to address this problem. These adhesives have a high initial peel strength, but prior to removal of the adhered product, can be subjected to a physical and / or chemical change that greatly reduces the peel strength. Thus, the medical product can be easily removed without causing local trauma or pain to the patient. In order for the adhesive medical product to have practical utility, it is further necessary that the reduction in peel strength be achieved in a controlled manner within a relatively short period of time (say from a few seconds to a few minutes at most). In addition, the adhesive itself and the switching mechanism must be suitable for use in contact with the skin.

[0009] For convenience, the term "switchable" is used herein to refer to adhesive compositions that can be changed from a tacky state to a substantially non-tacky state. Typically, the adhesives of the present invention have a peel force reduction of about 99% on polished stainless steel and a peel force reduction of about 90% on skin.

[0010] A form of switchable adhesive is disclosed in US 5,032,637, US 5,352,516, US 4,331,576 and US 5,182,323. These documents describe adhesives that become less viscous when in contact with water. However, such adhesives are not suitable for many medical applications where it is necessary to keep the patient's skin dry, such as at the site of a wound.

[0011] US2013 / 0123678, WO2010 / 129299 and WO2013 / 066401 disclose multilayer adhesive laminates that can be selectively released from a substrate when a liquid release agent is applied to the outer surface or periphery of the laminate. The laminate comprises an inner layer and a plurality of fluid channel conduits or holes extending through the inner layer, an adhesive layer disposed along the bottom surface of the inner layer, and a carrier layer disposed on the top surface of the inner layer. Removing the carrier layer and applying an effective amount of a liquid release agent results in a loss of adhesion.

[0012] EP 0863775, US 6,184,264 and US 6,610,762 disclose adhesives that are switchable when exposed to visible light or low-intensity UV light. The switchable adhesives described in these documents generally comprise acrylic adhesives based on copolymers of alkyl acrylates, acrylic acid and / or free radical polymerizable vinyl moieties "modified" or functionalized by curable moieties bound thereto. Typical bound-in curable moieties are those derived from anthracene, cinnamate, maleimide, coumarin, acrylate and / or methacrylate.

[0013] The inventor's WO2016 / 124339 and WO 2021 / 170711 disclose convertible adhesive compositions based on polyurethane adhesives. Unsaturated curable molecules can be mixed into and / or combined with the polyurethane polymer backbone. Photoinduced curing of the curable molecules leads to the formation of a crosslinked network, which results in a reduction in the peel strength of the adhesive.

[0014] Despite the developments described above, there is still a need in the art for improved switchable adhesives that exhibit the properties of high peel strength before switching, low peel strength after switching, and low switching time once switching has begun. It has been found that adhesive formulations with good adhesive properties typically exhibit poor switching capabilities, and adhesive formulations with good switching capabilities typically exhibit low peel strength and / or low cohesion (the adhesive has low internal strength so that the adhered material will separate from the surface, leaving residues of the adhesive on the surface). Therefore, in developing switchable adhesives, it is a particular challenge to simultaneously obtain high peel strength, high cohesion, and good switching capabilities.

[0015] Further need for improved switchable adhesive, wherein obtain desirable adhesive property and conversion property with low cytotoxicity.When adhesive is used for medical application, wherein adhesive may keep contact with skin for a long period of time, low cytotoxicity is particularly important.Adhesive with cytotoxicity exceeding a certain level can cause harmful skin effect, for example irritation and inflammation.Achieving low cytotoxicity and therefore achieving good biocompatibility is one of the most pressing challenges in the development of adhesive for medical application.

[0016] WO 2015 / 132551 of the present inventors also discloses a convertible adhesive composition based on a polyurethane adhesive and having reduced cytotoxicity. Specifically, the document identifies low molecular weight compounds (e.g., molecular weights in the range of 150-450) as the source of cytotoxicity, which is attributed to the ability of these compounds to penetrate cell membranes as well as the skin.

[0017] There is a continuing need in the art for switchable adhesive compositions having reduced cytotoxicity. SUMMARY OF THE INVENTION

[0019] The present invention has been designed in view of the disadvantages of known switchable pressure sensitive adhesive systems as set out above, and provides an improved switchable adhesive composition having high peel strength, high cohesion, fast switching time, low peel strength after switching and low cytotoxicity.

[0020] In a first aspect, the present invention provides an adhesive composition comprising the reaction product of (A) and (B):

[0021] (A) a polymer component having a weight average molecular weight in the range of 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2;

[0022] (B) a cross-linking component obtained by reacting (i) with at least one of (ii) and (iii):

[0023] (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functional groups per molecule;

[0024] (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom;

[0025] (iii) at least one compound which comprises a nucleophilic functional group containing an active hydrogen atom and which does not comprise a functional group curable by free radical polymerization;

[0026] wherein the total degree of substitution of the polyisocyanate component (i) by the compound (ii) and the compound (iii) is in the range of 0.1 to 0.7; and wherein the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.8.

[0027] In a second aspect, the present invention provides a method for preparing an adhesive composition, comprising:

[0028] (a) a first step of reacting (i) with at least one of (ii) and (iii) to form a crosslinking component (B):

[0029] (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functional groups per molecule;

[0030] (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom;

[0031] (iii) at least one compound which comprises a nucleophilic functional group containing an active hydrogen atom and which does not comprise a functional group curable by free radical polymerization;

[0032] wherein the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is in the range of 0.1 to 0.7;

[0033] (b) a second step of combining the crosslinking component (B) formed in step (a) with a polymer component (A), the polymer component (A) having a weight average molecular weight in the range of 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2,

[0034] The amounts of the crosslinking component (B) and the polyol component (A) are selected so that the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.8.

[0035] In a third aspect, the present invention provides an adhesive medical device comprising a layer of an adhesive composition as defined herein disposed on a first carrier film and a release liner disposed over the adhesive layer.

[0036] In a fourth aspect, the present invention provides a method of treating a wound using the adhesive medical product according to the third aspect, the method comprising removing the release liner and applying the adhesive dressing to the wound. DETAILED DESCRIPTION OF THE INVENTION

[0038] The adhesive composition of the present invention is the product of a reaction between a polymer component (component (A)) and a crosslinking component (component (B)). Specifically, the adhesive is formed by the reaction of nucleophilic functional groups on the polymer component with free isocyanate groups of the crosslinking component.

[0039] The crosslinking component (B) is obtained by partially reacting the polyisocyanate component (i) with at least one of the compound (ii) containing a curable functional group and the compound (iii) not containing a curable functional group. The total degree of substitution of the polyisocyanate component (i) by the compound (ii) and the compound (iii) is controlled within a specified range so that at least a portion of the isocyanate groups remain unreacted and are thus available for reaction with the hydroxyl groups of the polymer component (A) to form a crosslinked adhesive network containing a curable group.

[0040] The degree of substitution of the polyisocyanate component (i) represents the fraction of the isocyanate groups of the polyisocyanate component (i) substituted with the nucleophilic functional groups containing active hydrogen atoms from the compounds (ii) and (iii). It can be defined as follows:

[0041]

[0042] If compound (iii) is not present, the total degree of substitution of polyisocyanate component (i) relates to the degree of substitution via compound (ii). If compound (ii) is not present, the total degree of substitution of polyisocyanate component (i) relates to the degree of substitution via compound (iii). If both compound (ii) and compound (iii) are present, the total degree of substitution of polyisocyanate component (i) relates to the total degree of substitution via compound (ii) and compound (iii).

[0043] As a result of the partial reaction of the polyisocyanate component (i) with the compound (ii) and / or the compound (iii), a product mixture of a statistical mixture of substituted polyisocyanates is obtained. Some individual polyisocyanate molecules will be substituted by the compound (ii) and / or the compound (iii) on each isocyanate group, whereas other polyisocyanate molecules will not be substituted at all. Still other polyisocyanate molecules will contain one or more substituted isocyanate groups and one or more unsubstituted isocyanate groups in the same molecule. The unsubstituted isocyanate groups can be used to react with the nucleophilic functional groups of the polymer component (A).

[0044] In the case where a single polyisocyanate molecule is completely substituted by compound (ii) and / or compound (iii), the resulting compound will have no free isocyanate groups and will not be able to react with polyol component (A). However, if the compound is substituted by compound (ii), it can act as an unbound curable molecule that is able to participate in the curing reaction to convert the adhesive from a high viscosity state to a low viscosity state.

[0045] If the individual polyisocyanate molecules (i) are partially substituted or unsubstituted by compounds (ii) and / or (iii), they will be able to react with the nucleophilic functional groups of the polymer component and will thus become incorporated into the polyurethane adhesive via urethane / urea / amide bonds. The compounds with only one unsubstituted isocyanate group in the crosslinking component (B) will form a terminal bond with the polymer component and thus can serve to bind the curable molecules to the polymer backbone. The compounds with two unsubstituted isocyanate groups in the crosslinking component (B) can crosslink the two nucleophilic groups of the polymer component to form a crosslinked polymer network.

[0046] The compound having three (or more) unsubstituted isocyanate groups in the crosslinking component (B) is capable of crosslinking three (or more) nucleophilic groups of the polymer component and thus forming a node (or branch point) in which multiple polymer end groups are bonded to the same polyisocyanate molecule (network).

[0047] The degree of substitution of compound (ii) and / or compound (iii) to polyisocyanate component (i) has an important influence on the property of adhesive composition. If the degree of substitution is too low, polymer component (A) becomes too tightly integrated into the node as defined above. As a consequence, the fluidity of adhesive is reduced, resulting in insufficient viscosity. On the other hand, if the degree of substitution is too high, the cross-linking component comprises relatively few molecules comprising two or more unsubstituted isocyanate groups that can cross-link polymer component (A). In the case of low cross-linking degree, the cohesiveness of adhesive composition is poor, and therefore it is difficult to apply and remove adhesive without leaving residue.

[0048] It has also been found that the viscosity of the adhesive composition depends on the ratio of isocyanate groups in the cross-linking component to nucleophilic groups in the polymer. This ratio is crucial in polyurethane chemistry and is usually expressed as a percentage ([NCO] / [OH]×100%). It was previously believed that the NCO index of polyurethane adhesives for medical applications should be much lower than 100% because the additional mobility of polymer chains adjacent to unbound hydroxyl groups and the hydrogen bonding ability of unbound hydroxyl groups contribute to the viscosity of the adhesive. For example, WO 2021 / 170711 teaches that the molar ratio of isocyanate functional groups in the cross-linking component to hydroxyl groups in the polyol component is preferably 0.5 to 0.7. WO2015 / 075448 also relates to polyurethane medical adhesives and specifies that the NCO index is in the range of 0.45 to 0.69. EP2179749 discloses a pressure-sensitive polyurethane adhesive for medical use and specifies that the NCO index is in the range of 0.03 to 0.5.

[0049] It has been found that unbound nucleophilic groups and adjacent polymer chains play an important role in the cytotoxicity of polyurethane adhesives. Up to now, efforts to reduce the cytotoxicity of polyurethane adhesives have focused on the presence of low molecular weight impurities and by-products that have the ability to penetrate the skin and cell membranes. However, the inventors have identified that the adhesive polymer itself may have cytotoxic effects depending on its structure. It is believed that this cytotoxicity is due to the ability of unbound polymer chains to behave similarly to surfactants, the ability to destroy cell membranes.

[0050] It has been found that when the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups (e.g. hydroxyl groups) in the polymer component (A) is at least 0.8 (i.e., the isocyanate index is at least 80%), a significant reduction in cytotoxicity is observed. A high isocyanate index ensures that a high proportion of polymer chains are bound by the crosslinking component (B) and are therefore unable to contribute to cytotoxicity as a surfactant.

[0051] It is further found that when the cross-linking component is a polyisocyanate partially substituted by compound (ii) and / or compound (iii) as defined herein, sufficient viscosity (peel strength) is achieved. The partial substitution of polyisocyanates not only promotes the incorporation of curable groups into the composition, but also adjusts the bonding of polymer components and polyisocyanates, so that relatively few polymer chains are closely integrated into the nodes, and the adhesive keeps a larger chain mobility, thereby helping to improve viscosity. It is further found that compared with the adhesive formed by the unsubstituted polyisocyanate with less isocyanate group number per molecule, the statistical mixture of the partially substituted isocyanate compounds obtained according to the present invention provides an improved adhesive. In addition, less plasticization and better cohesive strength are obtained when there are less unbonded polymer molecules, because this causes crosslinking to be more evenly distributed throughout the adhesive composition.

[0052] The adhesive composition of the present invention generally has a gel-like consistency with a relatively low crosslink density. The composition is capable of forming polar bonds and van der Waals bonds with the substrate, and this gives the adhesive composition its adhesive properties.

[0053] When the cross-linking component (B) contains a curable portion from compound (ii), a curing (or conversion) reaction can be initiated, for example, by exposure to long wavelength UV or visible light in the presence of a photoinitiator. Compared to an unconverted adhesive composition, the curing reaction significantly increases the crosslinking density in the adhesive composition. This reduces the fluidity and free volume of the polymer segments of the adhesive composition, meaning that the composition loses its fluidity and becomes essentially an elastic film with no or minimal viscosity.

[0054] When peeling a pressure sensitive adhesive from a surface to which it is adhered, the energy required may be about 10 2 Up to 10 4 times greater than the energy that would be required from a thermodynamic point of view. In the switchable adhesive composition of the present invention, compound (ii) is contained in the crosslinking component, and the dense polymer network formed by the curable functional groups during the adhesive conversion reduces the viscosity and flexibility of the bulk material of the composition. Therefore, the required peel force is reduced to a value closer to that derived from thermodynamic considerations alone.

[0055] Polymer component (A)

[0056] The polymer component has a weight average molecular weight in the range of 1,000 to 100,000 Daltons and contains an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2. The nucleophilic groups of the polymer component (A) react with the free isocyanate groups of the crosslinking component (B) to form a crosslinked adhesive network.

[0057] The adhesive composition of the present invention is preferably a polyurethane adhesive. When the polymer component is a polyol, and therefore the nucleophilic group is a hydroxyl group, a polyurethane adhesive is formed. However, it is not excluded that the adhesive composition of the present invention can be formed from an amine-terminated polymer (which reacts with the isocyanate component to form a urea bond) or a carboxyl-terminated polymer (which reacts with the isocyanate component to form an amide bond).

[0058] Preferred polyols contain an average of 3 or more hydroxyl groups per molecule, preferably an average of 3 to 5 hydroxyl groups per molecule.

[0059] Preferably, at least 50 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 70 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 80 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 90 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups.

[0060] More preferably, at least 50 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups, or wherein at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups, or wherein at least 70 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups, or wherein at least 80 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups, or wherein at least 90 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups.

[0061] More preferably, at least 50 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups, or wherein at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups, or wherein at least 70 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups, or wherein at least 80 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups, or wherein at least 90 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups.

[0062] Although diols are routinely used in the art to prepare polyurethane adhesives, it has been found that certain diols, including diols formed from polypropylene glycols capped with polyethylene glycol, have a greater effect on cytotoxicity than similar polyols containing 3 or more hydroxyl groups. Without being bound by theory, it is believed that the polyurethane portion derived from the diol retains some surfactant properties even after reaction with the crosslinking component (B).

[0063] At the same time, it has also been found that adhesive compositions comprising a high proportion of polyols containing 3 to 5 hydroxyl groups maintain adequate adhesion even at high molar ratios of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A). This is particularly true for adhesive compositions comprising a high proportion of polyols containing 3 or 4 hydroxyl groups, still more particularly for adhesive compositions comprising a high proportion of polyols containing 3 hydroxyl groups.

[0064] The use of polyols containing 3 or more hydroxyl groups provides another source of crosslinking in the polyurethane structure. While this is beneficial to a certain extent, the use of polyols containing very large amounts of hydroxyl groups can lead to excessive crosslinking and loss of viscosity. Therefore, it is preferred that the polyol component mainly contains polyols containing 3 to 5 hydroxyl groups, preferably 3 or 4 hydroxyl groups, preferably 3 hydroxyl groups.

[0065] The polymer component (A) is preferably selected from hydroxyl-terminated polyethers (i.e., polyether polyols) and hydroxyl-terminated polyesters (i.e., polyester polyols). Most preferably, the polymer component is a hydroxyl-terminated polyether, more preferably a hydroxyl-terminated polyether derived from ether units (monomers) containing 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms. In particular, preferred hydroxyl-terminated polyethers contain repeating units derived from ethylene oxide and / or propylene oxide.

[0066] Suitable hydroxyl-terminated polyethers can be obtained by alkoxylation of a starting molecule having a desired number of nucleophilic groups. Preferred hydroxyl-terminated polyethers include alkoxylated derivatives of compounds containing 3 to 5 hydroxyl groups, or mixtures thereof. For example, suitable compounds containing 3 to 5 hydroxyl groups that can be used as starting molecules for forming polyethers by alkoxylation include glycerol, trimethylolpropane, erythritol, pentaerythritol, penta-1,2,4,5-tetrol, glucose, and mixtures thereof.

[0067] Preferred alkoxylated derivatives are ethoxylated derivatives, propoxylated derivatives or ethoxylated-co-propoxylated derivatives. Optionally, the hydroxyl-terminated polyether may be an ethylene oxide-terminated propoxylated derivative of a compound containing 3 to 5 hydroxyl groups, or a mixture thereof, including those described above. More preferably, the hydroxyl-terminated polyether may be selected from ethoxylated derivatives of glycerol or trimethylolpropane, or ethylene oxide-terminated propoxylated derivatives of glycerol or trimethylolpropane. Ethylene oxide termination is preferred because the low steric hindrance of the terminal hydroxyl group promotes a faster reaction with the isocyanate groups of the crosslinking component (B).

[0068] The polymer component (A) preferably has a weight average molecular weight (as measured by GPC) in the range of 1,000 to 50,000 Daltons, preferably in the range of 1,000 to 20,000 Daltons, preferably in the range of 1,500 to 10,000 Daltons. The equivalent weight per nucleophilic functional group containing an active hydrogen atom of the polymer component (per hydroxyl group in the case where the polymer component is a polyol) is preferably 200 to 5,000, preferably 500 to 2,500, preferably 1,000 to 2,000.

[0069] X preferably represents a number having a value of at least 2.2, preferably at least 2.4, preferably at least 2.6, preferably at least 2.8, preferably at least 3, preferably at least 3.2. In particular, it is preferred that at least a portion of the polymer molecules in polymer component (A) contain three or more nucleophilic functional groups. Polymer molecules having three or more nucleophilic functional groups containing active hydrogen atoms can introduce further crosslinking into the polymer network of the polyurethane adhesive, which helps to improve adhesive properties.

[0070] The value of X represents the nominal functionality of the polymer component. In the case where the polymer component is formed from a single starting molecule, the nominal functionality of the polymer is equal to the functionality of the starting molecule (for example, if trimethylolpropane is used as the starting molecule, the nominal functionality is 3). The nominal functionality can also be calculated as follows:

[0071]

[0072] In practice, this is equivalent to the number average molecular weight of the polymer (as measured by GPC) divided by the equivalent weight of each nucleophilic functional group containing an active hydrogen atom.

[0073] Cross-linking component (B)

[0074] The crosslinking component (B) of the adhesive composition of the present invention is obtained by reacting the polyisocyanate component (i) with at least one of the following: a compound (ii) comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom; and / or a compound (iii) comprising a nucleophilic functional group containing an active hydrogen atom but not comprising a functional group curable by free radical polymerization.

[0075] If the polyisocyanate component (i) is reacted with the compound (ii), the functional groups curable by free radical polymerization provide the adhesive composition with switching capability. The polyisocyanate component (i) may also optionally react with the compound (iii). The additional reaction of the polyisocyanate component (i) with the compound (iii) does not contribute to the switching capability of the adhesive, however it allows further control of the degree of substitution of the polyisocyanate component (i), regardless of the content of the curable part in the adhesive.

[0076] If the polyisocyanate component (i) is reacted only with compound (iii) and compound (ii) is omitted, the resulting adhesive cannot be converted via a curing reaction. However, polyurethane adhesives are still useful in medical applications due to the low cytotoxicity achieved by the present invention and the gentle behavior of the gel adhesive when peeled from the skin.

[0077] The total degree of substitution of compound (ii) and / or compound (iii) to polyisocyanate component (i) is 0.2 to 0.7. At very low degrees of substitution, crosslinking component (B) comprises a relatively high relative amount of unsubstituted polyisocyanate or monosubstituted polyisocyanate. This results in a tighter crosslinking of the polyol component, wherein more polymer end groups are incorporated into nodes (e.g., three or more polymer end groups are connected). It has been found that this produces an adhesive having insufficient peel strength under a high isocyanate index required for obtaining low cytotoxicity. Although effective adhesives can be obtained even if the degree of substitution of polyisocyanate component (i) is very high, such compositions will require a higher total amount of polyisocyanates to ensure that there are still enough free isocyanate groups available for crosslinking polyol component (A). For cost reasons, this may be undesirable. For example, when the total degree of substitution of compound (ii) and / or compound (iii) (if present) to polyisocyanate component (i) is in the range of 0.25 to 0.65, preferably in the range of 0.3 to 0.6, particularly good adhesive properties are found.

[0078] Polyisocyanate component (i)

[0079] The polyisocyanate component (i) has an average of 1.8 to 6 isocyanate functional groups per molecule. Preferably, the average number of isocyanate functional groups per molecule is in the range of 2 to 4, preferably in the range of 2.1 to 3.6, preferably in the range of 2.1 to 3.5, preferably in the range of 2.2 to 3.4, preferably in the range of 2.5 to 3.4. The term "average" is used herein to refer to the following average value based on quantity:

[0080]

[0081] It should be understood that the polyisocyanate component (i) may be a single polyisocyanate compound, or may comprise a mixture of different polyisocyanate compounds, as long as the average number of polyisocyanate groups per molecule is within the specified range.

[0082] The polyisocyanate component (i) can in principle be selected from any of the polyisocyanate compounds known in the art for making polyisocyanates, and mixtures thereof. For example, the polyisocyanate component (i) may comprise one or more polyisocyanate compounds selected from polyisocyanates containing 2 to 10 isocyanate functional groups per molecule and mixtures thereof, as long as the average number of isocyanate functional groups per molecule is in the range of 1.8 to 6. Preferably, the polyisocyanate component (i) comprises one or more polyisocyanate compounds, wherein the polyisocyanate component has an average of 2 to 4 isocyanate functional groups per molecule, preferably an average of 2.1 to 3.6 isocyanate functional groups per molecule, preferably an average of 2.1 to 3.5 isocyanate functional groups per molecule, preferably an average of 2.2 to 3.4 isocyanate functional groups per molecule, preferably an average of 2.5 to 3.4 isocyanate functional groups per molecule.

[0083] Optionally, the polyisocyanate component (i) may comprise a mixture of a diisocyanate and at least one polyisocyanate having an average of at least 3 isocyanate functional groups per molecule. It has been observed that mixtures of diisocyanates with other polyisocyanates produce adhesives that are more resistant to moisture. This is beneficial for medical applications where the adhesive must adhere to sweaty skin.

[0084] Examples of suitable polyisocyanates include diisocyanates of formula OCN-R-NCO, wherein R independently represents a linear, branched or cyclic alkylene group having 2 to 15 carbon atoms or an arylene group having 6 to 20 carbon atoms. Examples of diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, toluene 2,4-diisocyanate, 4,4'-methylene bis(phenyl isocyanate) and 4,4'-methylene bis(cyclohexyl isocyanate). Further suitable polyisocyanates include polymers based on diisocyanates (e.g., dimers, trimers, tetramers, etc.).

[0085] Preferred polyisocyanates are trimerized diisocyanates of formula D(R-NCO)3, wherein D represents a ring structure selected from isocyanurates and iminooxadiazinediones, or a branched structure selected from biuret and allophanate, and mixtures thereof, and each R independently represents a linear, branched or cyclic alkylene group having 2 to 15 carbon atoms, or an arylene group having 6 to 20 carbon atoms. A particularly preferred polyisocyanate in this category is trimerized hexamethylene diisocyanate.

[0086] Compound (ii)

[0087] The crosslinking component (B) can be obtained by reacting the polyisocyanate component (i) with at least one compound (ii) comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom.

[0088] The term "nucleophilic functional group containing active hydrogen atoms" refers herein to a functional group that can undergo addition reaction with an isocyanate group to form an adduct. For example, the nucleophilic functional group containing active hydrogen atoms can be -OH, -COOH, -NH, -SH, etc. Preferably, the nucleophilic functional group containing active hydrogen atoms is a hydroxyl group (-OH). Preferably, the nucleophilic functional group containing active hydrogen atoms is a hydroxyl group (i.e., a group of formula -CH2OH) connected to a primary carbon atom. The nucleophilic hydroxyl group can easily react with the isocyanate group of the polyisocyanate component (i), and a hydroxyl-containing compound containing a curable portion can be easily obtained in the art. Preferably, at least one compound (ii) comprises a single nucleophilic functional group containing active hydrogen atoms.

[0089] At least one compound (ii) preferably comprises an olefin moiety as a functional group that can be cured by free radical polymerization. At least one compound (ii) can be a single compound or a mixture of different compounds, each of which comprises an olefin moiety as a functional group that can be cured by free radical polymerization. Olefin moieties (e.g., acrylates and methacrylates) tend to have high yields in polymerization reactions, and are therefore excellent curable groups for achieving effective conversion performance via a free radical-induced curing process.

[0090] Preferably, at least one compound (ii) comprises an olefinic moiety as a functional group curable by free radical polymerization and a hydroxyl group as a nucleophilic functional group containing an active hydrogen atom.

[0091] In the broadest sense, any unsaturated compound that can be cured by free radical polymerization and further comprises a nucleophilic functional group containing an active hydrogen atom can be used as compound (ii). Examples of suitable compounds include hydroxy-substituted acrylates and hydroxy-substituted methacrylates, and mixtures thereof. Preferably, at least one compound (ii) is selected from hydroxy-substituted -(C2-C20 ) alkyl methacrylate, hydroxy-substituted-(C2-C 20 )alkyl acrylates, polyalkoxylated monomethacrylates containing 2 to 10 ether functional groups, polyalkoxylated monoacrylates containing 2 to 10 ether functional groups, and mixtures thereof. More preferably, at least one compound (ii) is selected from hydroxy-substituted-(C2-C6)alkyl methacrylates.

[0092] For example, compound (ii) can be selected from 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, polypropylene glycol monomethacrylate and polypropylene glycol monoacrylate. Preferred compound (ii) is 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate and mixtures thereof.

[0093] At least one compound (ii) may be a single compound, or may be a mixture of compounds, each of which has a functional group that can be cured by free radical polymerization and a nucleophilic functional group containing an active hydrogen atom. In the case where compound (ii) is a mixture of compounds, each compound preferably contains the same type of curable functional group, and more preferably each compound contains an olefin group. For example, compound (ii) may be a mixture of 2-hydroxypropyl methacrylate and isomeric hydroxyisopropyl methacrylate.

[0094] Other examples of hydroxyl-containing acrylates are methacrylate hydroxyl (CH2) n Esters (where n is 4-8), hydroxyethyl methacrylate caprolactone (2-(methacryloyloxy)ethyl caprolactone), 3-(acryloyloxy)-2-hydroxypropyl methacrylate and glycerol dimethacrylate.

[0095] Compound (ii) may be used in combination with compound (iii) as appropriate. As described above, the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is in the range of 0.1 to 0.7, and preferably in the range of 0.15 to 0.65, more preferably in the range of 0.2 to 0.6, more preferably in the range of 0.25 to 0.6, and more preferably in the range of 0.3 to 0.6.

[0096] The degree of substitution of compound (ii) to polyisocyanate component (i) is preferably in the range of 0.05 to 0.5; or in the range of 0.05 to 0.45, or in the range of 0.05 to 0.4, or in the range of 0.8 to 0.35, or in the range of 0.8 to 0.3, or in the range of 0.1 to 0.25, or in the range of 0.1 to 0.2, or in the range of 0.12 to 0.18. The amount of compound (iii) (if any) can then be selected to achieve the total degree of substitution as stated above. In the case where the degree of substitution of compound (ii) to polyisocyanate component (i) is very low, the relative amount of curable groups is low, which can lead to a reduction in the conversion performance of the adhesive when cured. However, much higher levels of curable groups exceed the level necessary for effective conversion, and therefore increase the cost of producing the adhesive without any substantial performance benefits.

[0097] Compound (iii)

[0098] The crosslinking component (B) can be obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii).

[0099] As stated above, partial substitution of polyisocyanate component (i) is desirable for obtaining different distributions of isocyanate-containing compounds in cross-linking component (B). However, obtaining the desired degree of substitution of polyisocyanate component (i) with only compound (ii) tends to produce an adhesive containing significantly more curable groups than necessary to obtain good conversion performance. Excessive curable groups may make it necessary to carefully handle during the manufacture of adhesives and products containing adhesives to avoid premature conversion. For cost and biocompatibility reasons, excessive substitution of compound (ii) to polyisocyanate component (i) is also disadvantageous.

[0100] A particular consequence of compositions containing high concentrations of curable groups is that shear forces in equipment (e.g., pumps and flow lines) used to handle adhesives or their precursors during the manufacturing process can cause premature curing of the curable groups. This can result in reduced viscosity of the adhesive product and in some cases cause clogging of the manufacturing equipment. Therefore, the use of compound (iii) allows these problems to be alleviated by achieving the desired degree of substitution of the polyisocyanate component (i) without introducing too many curable groups in the adhesive composition.

[0101] In an alternative embodiment, the crosslinking component (B) can be obtained by reacting the polyisocyanate component (i) with the compound (iii), wherein the compound (ii) is omitted. In this case, the compound (iii) alone provides partial substitution of the polyisocyanate component (i) in the absence of a curable component.

[0102] In the case where compound (ii) is omitted, the total degree of substitution of polyisocyanate component (i) is equal to the degree of substitution of compound (iii) for polyisocyanate component (i), and is therefore in the range of 0.2 to 0.7, and preferably in the range of 0.25 to 0.65, more preferably in the range of 0.3 to 0.6, more preferably in the range of 0.35 to 0.6, more preferably in the range of 0.4 to 0.6.

[0103] At least one compound (iii) comprises a nucleophilic functional group containing an active hydrogen atom, but does not comprise a functional group curable by free radical polymerization. At least one compound (iii) may be a single compound, or it may be a mixture of different compounds, none of which comprises a functional group curable by free radical polymerization.

[0104] At least one compound (iii) is preferably selected from linear, branched or cyclic C1-C 30 Aliphatic alcohols, preferably linear, branched or cyclic C1-C 18 Aliphatic alcohols, more preferably linear, branched or cyclic C1-C 12 Preferably, at least one compound (iii) is selected from branched C3-C 12 aliphatic alcohol, or selected from branched C6-C 18 Aliphatic alcohols. An example of a suitable compound is 2-ethyl-1-hexanol. Such compounds occupy one or more isocyanate bonding sites in order to obtain the desired reaction product distribution from the reaction of the polyisocyanate component (i) with the compound (iii) and optionally the compound (ii).

[0105] However, the further advantage of comprising compound (iii) is that the aliphatic carbon chain adds fatness to the adhesive composition. This reduces the water solubility of the adhesive as a whole, and particularly reduces the ability of any component of the relatively low molecular weight of the adhesive to penetrate the skin. Therefore, compound (iii) further reduces the cytotoxicity of the adhesive. In addition, the aliphatic carbon chain acts as a plasticizer in the adhesive, reducing the interaction between the polymer chains. Therefore, the adhesive becomes softer, cheaper and easier to produce.

[0106] At least one compound (iii) also enables other functional groups to be incorporated into the adhesive composition without affecting initial peel force or conversion performance. Molecules containing these functional groups will be mixed into the adhesive polyurethane composition as small molecules in addition. Therefore, by adding them into the polyurethane network, the cytotoxicity of the adhesive is reduced. For example, at least one compound (iii) may include one or more photoinitiators or be composed of one or more photoinitiators, and the photoinitiator contains a nucleophilic functional group (such as a hydroxyl) containing an active hydrogen atom for connection with the polyisocyanate component (i). For purposes of the present invention, the photoinitiator is considered to be a molecule that initiates a curing reaction but is not curable itself. Therefore, the photoinitiator combined with polyisocyanates is considered to be a compound (iii) that does not include a functional group that can be cured by free radical polymerization.

[0107] Other examples of compounds that may be incorporated as compound (iii) in the adhesive composition of the present invention include biocides and catalysts.

[0108] Typically, at least one compound (iii) comprises a single nucleophilic group containing an active hydrogen atom. However, it is not excluded that at least one compound (iii) may comprise more than one nucleophilic functional group containing an active hydrogen atom, in which case compound (iii) may link two polyisocyanate molecules together.

[0109] Adhesive composition

[0110] The relative amounts of polymer component (A) and crosslinking component (B) are defined herein by reference to the molar ratio of unsubstituted isocyanate groups in the crosslinking component (B) to available nucleophilic groups in the polymer component (A). As described above, it has been found that the cytotoxicity of the adhesive is reduced when the molar ratio of unsubstituted isocyanate groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is at least 0.8.

[0111] Preferably, the molar ratio of the unsubstituted isocyanate groups in the crosslinking component (B) to the nucleophilic groups containing active hydrogen atoms in the polymer component (A) is at least 0.81, or at least 0.82, or at least 0.83, or at least 0.84, or at least 0.85, or at least 0.86, or at least 0.87, or at least 0.88, or at least 0.89, or at least 0.90, or at least 0.91, or at least 0.92, or at least 0.93, or at least 0.94, or at least 0.95.

[0112] If compound (ii) is used in the reaction to obtain the crosslinking component (B), the adhesive polyurethane preferably contains 0.05 to 1 meq / g, preferably 0.06 to 0.5 meq / g, preferably 0.08 to 0.4 meq / g, preferably 0.1 to 0.3 meq / g, preferably 0.12 to 0.25 meq / g, preferably 0.15 to 0.2 meq / g of functional groups curable by free radical polymerization. As mentioned above, although high levels of curable groups are feasible, the benefits of conversion performance are small and increase the cost of producing the adhesive without any substantial performance benefits.

[0113] The reactants used to form the adhesive composition of the present invention are preferably substantially free of water. Water may be present in the polyol component (A) or in the compound (ii) and the compound (iii) as a small amount of impurities, for example. Water reacts with the isocyanate groups of the cross-linking component (B), and thus reduces the number of unsubstituted isocyanate functional groups in the cross-linking component (B) that can be used to react with the nucleophilic functional groups in the polymer component (A). For the avoidance of doubt, when referring to the molar ratio of the unsubstituted isocyanate functional groups in the cross-linking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A), the degree of substitution of water to the polyisocyanate component (i) is taken into account, and the content of the unsubstituted isocyanate functional groups is adjusted accordingly.

[0114] Preferably, the maximum degree of substitution of water for polyisocyanate component (i) does not exceed 0.1, preferably does not exceed 0.08, preferably does not exceed 0.06, preferably does not exceed 0.05, preferably does not exceed 0.04. Considering that water is a bifunctional molecule, the total degree of substitution of water for polyisocyanate component (i) is calculated as follows:

[0115]

[0116] Photoinitiator

[0117] For the adhesive composition of the present invention that is switchable and contains compound (ii) in the crosslinking component (B), the adhesive polyurethane composition preferably comprises a photoinitiator, preferably 0.05 to 5 wt% of a photoinitiator, preferably 0.1 to 5 wt% of a photoinitiator, preferably 0.2 to 2 wt% of a photoinitiator. These particular ranges of photoinitiators enable the curable groups to react with each other upon activation and allow the adhesive to achieve a desirable switching time.

[0118] The photoinitiator may be mixed into the adhesive composition and / or bonded to the polymer chains of the adhesive composition. Optionally, a photoinitiator may be used as compound (iii), provided that it has a suitable nucleophilic functional group for attachment to the polyisocyanate component and provided that the photoinitiating function is not thereby hindered.

[0119] The photoinitiator may be any species capable of generating free radical species under mild conditions (eg UV or visible light) so as to promote free radical initiated polymerization of the curable functional groups of compound (ii).

[0120] Preferably, the photoinitiator is reactive to UV radiation with a wavelength in the range of 200 to 400 nm, preferably UVA radiation (315 to 400 nm). UVA is particularly preferred for medical applications and other applications requiring exposure of humans or animals to UV radiation. The range of 200 to 400 nm is referred to herein as "long wavelength UV".

[0121] Alternatively, the photoinitiator may generate free radical species upon exposure to visible light, but the product that is curable upon exposure to visible light requires careful handling and / or the incorporation of additional visible light blocking materials into the product to avoid premature conversion of the adhesive. When conversion is required, the visible light blocking material needs to be removed from the product at the appropriate time.

[0122] The UV-reactive photoinitiator can be selected from any conventional photoinitiator known in the art. For example, the UV-reactive photoinitiator can be appropriately selected from benzoin and derivatives (e.g., ethyl ether, isopropyl ether or isobutyl ether of benzoin); benzophenone and derivatives (e.g., 4-phenylbenzophenone); acetophenone and 4-phenoxyacetophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone; 2-dimethyl amino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one; 2-ethylanthraquinone; benzil dimethyl ketal; 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropanone; 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)benzyl)-phenyl]-2-methylpropan-1-one; 2-hydroxy-2-methylpropiophenone; and ethyl-4-(dimethylamino)benzoate.

[0123] Free radical initiators suitable for visible light activation include titanocene photoinitiators; dye / co-initiator systems such as thionine / triethanolamine; dye / peroxide systems and 1,2-diketone / co-initiator systems such as camphor-quinone / tertiary amine. Examples of visible light photoinitiators are: phenanthrenequinone; titanocene; and bis(2,4,6-trimethyl-benzoyl)-phenylphosphine oxide.

[0124] Solvents

[0125] The adhesive composition may further comprise a solvent. The solvent must be an aprotic solvent so that it does not react with the isocyanate groups of the polyisocyanate component (i). Preferably, the solvent has low toxicity, preferably, the solvent is non-toxic. An example of a preferred solvent is ethyl acetate.

[0126] Stabilizer

[0127] If the adhesive composition comprises curable functional groups, it may also contain a stabilizer. As used herein, the term "stabilizer" refers to a substance added to the adhesive composition to remove free radicals in order to prevent premature reaction of the curable functional groups in the adhesive during manufacture and / or storage of the adhesive composition. These substances are well known in the field of curable materials and may also be referred to as antioxidants.

[0128] Examples of suitable stabilizers include 1-piperidinyloxy-4,4′-[1,10-dioxo-1,10-decanediyl]bis(oxy)]bis[2,2,6,6-tetramethyl] and phenolic derivatives such as methoxyphenol, di-tert-butyl-4-methylphenol and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate).

[0129] Optional Ingredients

[0130] If the adhesive composition contains curable functional groups, it may also contain a photosensitizer. Because the photosensitive species generally absorb energy in different parts of the spectrum from the photoinitiator, more efficient use of the light source can be achieved by incorporating the photosensitizer into the composition. Many photosensitizers are complex organic molecules that absorb the long wavelength UV and / or visible light portions of the spectrum.

[0131] The adhesive composition may also incorporate scattering particles to increase the radiative effect of the adhesive mixture by scattering the radiated UV or visible light through the thickness of the adhesive mixture. Preferably, the light scattering particles are inorganic compounds, such as silica powder, alumina powder, silica-alumina powder or mica powder, having a particle size of about 10 nm or more, typically up to 1 μm.

[0132] For switchable adhesive compositions, the reactivity of the composition can be increased by increasing the concentration of curable groups in the adhesive (meq / g), using compounds (ii) having two or more curable groups, and / or using more reactive functional groups in the adhesive, such as partially or completely exchanging methacrylates with acrylates (acrylates are more reactive, but also slightly more toxic).

[0133] The interaction between the adhesive molecules and thus the viscosity of the adhesive before the conversion can be reduced by using bulky groups in the crosslinking component (B) (e.g., by adding methyl groups or by branching the polyol component (A)) and / or introducing asymmetry or higher hydrophobicity. This can be achieved by using a polyisocyanate component (i) with bulky groups, for example, by exchanging hexamethylene diisocyanate with trimethylhexamethylene diisocyanate, exchanging isocyanurate with iminooxadiazinedione, exchanging butanediol with methylpentanediol, exchanging polyethylene glycol with polypropylene glycol, etc. Alternatively, this can also be achieved by using at least one compound (iii) in the crosslinking component (B), wherein at least one compound (iii) comprises bulky groups.

[0134] The adhesive compositions of the present invention exhibit a reduced peel force after switching of at least 30%, and preferably 50% to 99%, preferably 70% to 99%, when measured according to the method described below.

[0135] According to the first aspect of the present invention, there is further provided an adhesive composition according to the following aspects 1-1 to 1-20.

[0136] Aspect 1-1: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0137] (i) X represents a number having a value of at least 2.2;

[0138] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0139] (iii) at least 60 mol % of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups;

[0140] (iv) the polyisocyanate component (i) has an average of 2 to 4 isocyanate functional groups per molecule;

[0141] (v) compound (ii) is present, and the degree of substitution of compound (ii) on polyisocyanate component (i) is in the range of 0.05 to 0.5, preferably in the range of 0.05 to 0.45;

[0142] (vi) the total degree of substitution of compound (ii) and optionally compound (iii) on the polyisocyanate component (i) is from 0.25 to 0.65; and

[0143] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.82.

[0144] Aspect 1-2: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0145] (i) X represents a number having a value of at least 2.4;

[0146] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0147] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups;

[0148] (iv) the polyisocyanate component (i) has an average of 2.1 to 3.6 isocyanate functional groups per molecule;

[0149] (v) compound (ii) is present, and the degree of substitution of compound (ii) on polyisocyanate component (i) is in the range of 0.05 to 0.4, preferably in the range of 0.08 to 0.35;

[0150] (vi) the total degree of substitution of compound (ii) and optionally compound (iii) on the polyisocyanate component (i) is from 0.3 to 0.6; and

[0151] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.86.

[0152] Aspect 1-3: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0153] (i) X represents a number having a value of at least 2.6;

[0154] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0155] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0156] (iv) the polyisocyanate component (i) has an average of 2.2 to 3.4 isocyanate functional groups per molecule;

[0157] (v) compound (ii) is present, and the degree of substitution of compound (ii) on polyisocyanate component (i) is in the range of 0.08 to 0.3, preferably in the range of 0.1 to 0.25;

[0158] (vi) the total degree of substitution of compound (ii) and optionally compound (iii) on the polyisocyanate component (i) is from 0.35 to 0.6; and

[0159] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.9.

[0160] Aspects 1-4: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0161] (i) X represents a number having a value of at least 2.8;

[0162] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0163] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0164] (iv) the polyisocyanate component (i) has an average of 2.5 to 3.4 isocyanate functional groups per molecule;

[0165] (v) compound (ii) is present, and the degree of substitution of compound (ii) on polyisocyanate component (i) is in the range of 0.1 to 0.2, preferably in the range of 0.12 to 0.18;

[0166] (vi) the total degree of substitution of compound (ii) and optionally compound (iii) on the polyisocyanate component (i) is from 0.4 to 0.6; and

[0167] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.92.

[0168] Aspects 1-5: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0169] (i) X represents a number having a value of at least 2.2;

[0170] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0171] (iii) at least 60 mol % of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups;

[0172] (iv) the polyisocyanate component (i) has an average of 2 to 4 isocyanate functional groups per molecule;

[0173] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.05 to 0.5, preferably in the range of 0.05 to 0.45;

[0174] (vi) the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is from 0.25 to 0.65; and

[0175] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.82.

[0176] Aspects 1-6: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0177] (i) X represents a number having a value of at least 2.4;

[0178] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0179] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups;

[0180] (iv) the polyisocyanate component (i) has an average of 2.1 to 3.6 isocyanate functional groups per molecule;

[0181] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.05 to 0.4, preferably in the range of 0.08 to 0.35;

[0182] (vi) the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is from 0.3 to 0.6; and

[0183] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.86.

[0184] Aspects 1-7: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0185] (i) X represents a number having a value of at least 2.6;

[0186] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0187] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0188] (iv) the polyisocyanate component (i) has an average of 2.2 to 3.4 isocyanate functional groups per molecule;

[0189] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.08 to 0.3, preferably in the range of 0.1 to 0.25;

[0190] (vi) the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is from 0.35 to 0.6; and

[0191] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.9.

[0192] Aspects 1-8: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0193] (i) X represents a number having a value of at least 2.8;

[0194] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0195] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0196] (iv) the polyisocyanate component (i) has an average of 2.5 to 3.4 isocyanate functional groups per molecule;

[0197] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.1 to 0.2, preferably in the range of 0.12 to 0.18;

[0198] (vi) the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is from 0.4 to 0.6; and

[0199] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.92.

[0200] Aspects 1-9: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0201] (i) X represents a number having a value of at least 2.2;

[0202] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 20,000 Daltons, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0203] (iii) at least 60 mol % of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups;

[0204] (iv) the polyisocyanate component (i) has an average of 2 to 4 isocyanate functional groups per molecule;

[0205] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.05 to 0.5, preferably in the range of 0.05 to 0.45;

[0206] (vi) the total degree of substitution of compound (ii) and compound (iii) for polyisocyanate component (i) is from 0.25 to 0.65;

[0207] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.82;

[0208] (viii) at least one compound (ii) selected from hydroxy-substituted -(C2-C 20 ) alkyl methacrylate and hydroxy-substituted-(C2-C 20 ) alkyl acrylate; and

[0209] (ix) at least one compound (iii) selected from C1-C 30 Aliphatic alcohol.

[0210] Aspects 1-10: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0211] (i) X represents a number having a value of at least 2.4;

[0212] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 20,000 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0213] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups;

[0214] (iv) the polyisocyanate component (i) has an average of 2.1 to 3.6 isocyanate functional groups per molecule;

[0215] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.05 to 0.4, preferably in the range of 0.08 to 0.35;

[0216] (vi) the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is from 0.3 to 0.6;

[0217] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.86;

[0218] (viii) at least one compound (ii) is selected from hydroxy-substituted-(C2-C6)alkyl methacrylates; and

[0219] (ix) at least one compound (iii) selected from linear, branched or cyclic C1-C 18 Aliphatic alcohol.

[0220] Aspects 1-11: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0221] (i) X represents a number having a value of at least 2.6;

[0222] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,500 to 10,000 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0223] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0224] (iv) the polyisocyanate component (i) has an average of 2.2 to 3.4 isocyanate functional groups per molecule;

[0225] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.08 to 0.3, preferably in the range of 0.1 to 0.25;

[0226] (vi) the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is from 0.35 to 0.6;

[0227] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.9;

[0228] (viii) at least one compound (ii) selected from 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, polypropylene glycol monomethacrylate and polypropylene glycol monoacrylate; and

[0229] (ix) at least one compound (iii) selected from linear, branched or cyclic C1-C 12 Aliphatic alcohol.

[0230] Aspects 1-12: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0231] (i) X represents a number having a value of at least 2.8;

[0232] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 2,500 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0233] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0234] (iv) the polyisocyanate component (i) has an average of 2.5 to 3.4 isocyanate functional groups per molecule;

[0235] (v) compound (ii) and compound (iii) are present, and the degree of substitution of compound (ii) for polyisocyanate component (i) is in the range of 0.1 to 0.2, preferably in the range of 0.12 to 0.18;

[0236] (vi) the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is from 0.4 to 0.6;

[0237] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.92;

[0238] (viii) at least one compound (ii) selected from 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, and mixtures thereof; and

[0239] (ix) at least one compound (iii) selected from branched C3-C 12 Aliphatic alcohol.

[0240] Aspects 1-13: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0241] (i) X represents a number having a value of at least 2.2;

[0242] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0243] (iii) at least 60 mol % of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups;

[0244] (iv) the polyisocyanate component (i) has an average of 2 to 4 isocyanate functional groups per molecule;

[0245] (v) the absence of compound (ii);

[0246] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.25 to 0.65; and

[0247] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.82.

[0248] Aspects 1-14: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0249] (i) X represents a number having a value of at least 2.4;

[0250] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0251] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups;

[0252] (iv) the polyisocyanate component (i) has an average of 2.1 to 3.6 isocyanate functional groups per molecule;

[0253] (v) the absence of compound (ii);

[0254] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.3 to 0.6; and

[0255] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.86.

[0256] Aspects 1-15: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0257] (i) X represents a number having a value of at least 2.6;

[0258] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0259] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0260] (iv) the polyisocyanate component (i) has an average of 2.2 to 3.4 isocyanate functional groups per molecule;

[0261] (v) the absence of compound (ii);

[0262] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.35 to 0.6; and

[0263] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to hydroxyl groups in the polyol component (A) is at least 0.9.

[0264] Aspects 1-16: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0265] (i) X represents a number having a value of at least 2.8;

[0266] (ii) polymer component (A) is a polyol, preferably a polyether polyol, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0267] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0268] (iv) the polyisocyanate component (i) has an average of 2.5 to 3.4 isocyanate functional groups per molecule;

[0269] (v) the absence of compound (ii);

[0270] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.4 to 0.6; and

[0271] (vii) The molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.92.

[0272] Aspects 1-17: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0273] (i) X represents a number having a value of at least 2.2;

[0274] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 20,000 Daltons, preferably a polyether polyol comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0275] (iii) at least 60 mol % of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups;

[0276] (iv) the polyisocyanate component (i) has an average of 2 to 4 isocyanate functional groups per molecule;

[0277] (v) the absence of compound (ii);

[0278] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.25 to 0.65;

[0279] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.82; and

[0280] (viii) at least one compound (iii) selected from C1-C 30 Aliphatic alcohol.

[0281] Aspects 1-18: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0282] (i) X represents a number having a value of at least 2.4;

[0283] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 20,000 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0284] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 or 4 hydroxyl groups;

[0285] (iv) the polyisocyanate component (i) has an average of 2.1 to 3.6 isocyanate functional groups per molecule;

[0286] (v) the absence of compound (ii);

[0287] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.3 to 0.6;

[0288] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.86; and

[0289] (viii) at least one compound (iii) selected from linear, branched or cyclic C1-C 18 Aliphatic alcohol.

[0290] Aspects 1-19: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0291] (i) X represents a number having a value of at least 2.6;

[0292] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,500 to 10,000 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0293] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0294] (iv) the polyisocyanate component (i) has an average of 2.2 to 3.4 isocyanate functional groups per molecule;

[0295] (v) the absence of compound (ii);

[0296] (vi) the total degree of substitution of compound (iii) for the polyisocyanate component (i) is from 0.35 to 0.6;

[0297] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.9; and

[0298] (viii) at least one compound (iii) selected from linear, branched or cyclic C1-C 12 Aliphatic alcohol.

[0299] Aspects 1-20: The adhesive polyurethane composition according to the first aspect of the present invention, wherein:

[0300] (i) X represents a number having a value of at least 2.8;

[0301] (ii) polymer component (A) is a polyether polyol having a weight average molecular weight in the range of 1,000 to 2,500 Daltons, preferably comprising repeating units derived from ethylene oxide and / or propylene oxide;

[0302] (iii) at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 hydroxyl groups;

[0303] (iv) the polyisocyanate component (i) has an average of 2.5 to 3.4 isocyanate functional groups per molecule;

[0304] (v) the absence of compound (ii);

[0305] (vi) the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is from 0.4 to 0.6;

[0306] (vii) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to the hydroxyl groups in the polyol component (A) is at least 0.92; and

[0307] (viii) at least one compound (iii) selected from branched C3-C 12 Aliphatic alcohol.

[0308] It should be understood that any preferred / optional features disclosed herein in relation to the first aspect of the present invention that fall within the scope of Aspects 1-1 to 1-20 described above are also preferred / optional features of Aspects 1-1 to 1-20. Similarly, any features of the dependent claims that fall within the scope of Aspects 1-1 to 1-20 described above should also be interpreted as if those claims also belong to Aspects 1-1 to 1-20.

[0309] Method for preparing adhesive composition

[0310] According to a second aspect of the present invention, there is provided a method for preparing an adhesive composition, comprising:

[0311] (a) a first step of reacting (i) with at least one of (ii) and (iii) to form a crosslinking component (B):

[0312] (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functional groups per molecule;

[0313] (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom;

[0314] (iii) at least one compound which comprises a nucleophilic functional group containing an active hydrogen atom and which does not comprise a functional group curable by free radical polymerization;

[0315] wherein the total degree of substitution of compound (ii) and / or compound (iii) for polyisocyanate component (i) is in the range of 0.2 to 0.7;

[0316] (b) a second step of combining the crosslinking component (B) formed in step (a) with a polymer component (A), the polymer component (A) having a weight average molecular weight in the range of 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2,

[0317] The amounts of the crosslinking component (B) and the polyol component (A) are selected so that the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.8.

[0318] The method of the second aspect of the present invention can be used for producing the adhesive composition of the first aspect of the present invention. Therefore, any feature described as optional or preferred with reference to the first aspect of the present invention should also be understood as constituting the optional or preferred features of the characteristics (identity), amount and ratio of the corresponding components used in the method of the second aspect of the present invention. For example, the method of the second aspect of the present invention can be used for producing the adhesive composition of any one in the aspect 1-1 to aspect 1-18 described above.

[0319] Step (a) and / or step (b) of the method for preparing the adhesive polyurethane composition may be carried out in the presence of a catalyst. Suitable catalysts include dibutyltin dilaurate, zirconium (IV) acetylacetonate, dibutyltin 2-ethylhexanoate, zinc (II) 2-ethyl-1-hexanoate and tertiary amines.

[0320] Step (a) and / or step (b) may be carried out in the presence of a solvent. Suitable solvents are aprotic solvents such as ethyl acetate, toluene and tetrahydrofuran.

[0321] Preferably, the photoinitiator is combined with the product of step (a) or the polyol component prior to step (b).Most preferably, the photoinitiator is combined with the polyol component prior to step (b).

[0322] Adhesive medical devices

[0323] According to a third aspect of the present invention, there is provided an adhesive medical device comprising a layer of an adhesive composition as defined in any one of claims 1 to 28 disposed on a first carrier film and a release liner disposed over the adhesive layer.

[0324] The adhesive medical device may include a product selected from the group consisting of adhesive dressings including absorbent wound pads, surgical incision drapes, bacterial barriers for covering wounds, and skin closure devices for closing the edges of a wound together.

[0325] When the medical product comprises a switchable adhesive, suitably the first carrier film of the medical device may be translucent to UV and / or visible light. Optionally, a removable light blocking layer is laminated to the first carrier film on the surface opposite to the adhesive composition.

[0326] Exemplary materials for the carrier film for carrying the switchable adhesive composition layer include polyethylene, polypropylene, polyurethane, ethylene / propylene copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, silicone elastomer, polydimethylsiloxane, chloroprene rubber, polyisobutylene, polyacrylate, chlorinated polyethylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, cross-linked polymethacrylate polymer (hydrogel), polyvinylidene chloride, polyethylene terephthalate, butyl rubber, epichlorohydrin rubber, ethylene-vinyl alcohol copolymer, ethylene-vinyloxyethanol copolymer; silicone copolymers, such as polysiloxane-polycarbonate copolymer, polysiloxane-polyethylene oxide copolymer, polysiloxane-polymethacrylate copolymer, polysiloxane-olefin copolymer (e.g., polysiloxane-ethylene copolymer), polysiloxane-alkylene silane copolymer (e.g., polysiloxane-ethylene silane copolymer), etc.; cellulosic polymers, such as methyl cellulose or ethyl cellulose, hydroxypropyl methylcellulose and cellulose esters; polycarbonate; polytetrafluoroethylene, etc. More preferred are medical grade polyether or polyester polyurethanes, thermoplastic polyester elastomers, porous polyethylene, polypropylene and PET films, and medical grade woven or nonwoven materials.

[0327] Adhesive wound dressings typically consist of an absorbent pad for absorbing exudate from a bandaged wound, surrounded by an adhesive region used to secure the wound pad in position over the wound. The adhesive region and wound pad are supported on a carrier film, which is typically flesh-colored or may sometimes have an attractive design on its visible surface. The switchable adhesive composition according to the present invention is an ideal candidate for use as an adhesive in the adhesive region around a wound pad of an adhesive wound dressing.

[0328] Adhesive wound dressings are typically applied by non-professional users in their own homes, and not necessarily by medical practitioners. Since few households have access to suitable UV radiation equipment, adhesive wound dressings for home use preferably comprise an adhesive that can be cured by visible light. In some cases, it is preferred that the convertible adhesive wound dressing comprise an adhesive that can be cured by UV light, so that the timing of removal of the dressing is controlled by a medical practitioner. In the case where the adhesive can be cured by UV light, a removable light blocking layer may not be necessary.

[0329] The adhesive wound dressing intended for home use will preferably include a light blocking layer to prevent premature conversion of the switchable adhesive composition. The first light blocking layer is located on the side of the carrier film opposite to the adhesive, and remains in place until the time when the user wants to remove the adhesive wound dressing. At this time, the first light blocking layer is removed, and the following switchable adhesive composition is exposed to visible light, causing the adhesive composition to be converted from a viscous state to a non-viscous state or a low-viscous state. Optionally, the second light blocking layer can form a part of a release liner placed on the adhesive side of the dressing. Just before the adhesive wound dressing is applied above the wound, the second light blocking layer is removed. In the case where the adhesive wound dressing is provided in a light blocking package, the second light blocking layer may be optional.

[0330] In the case where the adhesive wound dressing comprises an adhesive that can be cured by UV light, a light blocking layer may not be necessary. Instead, the carrier film of the adhesive wound dressing only needs to be UV translucent. When it is desired to remove the adhesive wound dressing, a trained practitioner shines a suitable UV light source over the adhesive wound dressing to initiate the curing reaction. The adhesive loses its tack within seconds and the wound dressing is easily removed.

[0331] The release liner may be selected from any covering material having a low surface energy so that it can be easily removed from the adhesive layer. Suitable release liners include paper films and plastic films provided with a silicone coating on the surface contacting the adhesive composition.

[0332] In case the adhesive wound dressing does not comprise an adhesive composition having a curable part (ie wherein component (ii) is not used in the reaction to obtain the cross-linking component (B), the use of a light blocking layer is not necessary.

[0333] According to a fourth aspect of the present invention there is provided a method of treating a wound using an adhesive medical product as defined herein, wherein the method comprises removing the release liner and applying the adhesive medical device to the wound.

[0334] The present invention will now be further described, by way of example only and not limitation, with reference to the accompanying drawings, in which:

[0335] Figure 1 is a cross-sectional view through an adhesive dressing according to a first embodiment of the present invention;

[0336] Figure 2 is a perspective view showing an attempted removal of an adhesive dressing according to a first embodiment of the present invention from a patient's forearm and includes an enlarged bubble diagram showing in partial cross-section how removal of the adhesive dressing results in squeeze-out of the adhesive composition;

[0337] Figure 3is a perspective view showing an adhesive dressing according to a first embodiment of the present invention subjected to radiation to effect conversion of the adhesive;

[0338] Figure 4 is a perspective view showing how an adhesive dressing according to a first embodiment of the present invention can be easily removed after conversion of the adhesive;

[0339] Figure 5 and Figure 6 It is a graph showing the results of Example 5 to Example 14.

[0340] Detailed Description of the Drawings

[0341] Now refer to Figures 1 to 4 The adhesive medical device using the adhesive polyurethane composition of the present invention is described. The adhesive medical product in this example is an adhesive medical dressing.

[0342] Figure 1 1 is a cross-sectional view through an adhesive medical dressing 100 adhered 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 opposite edges 150, the backing layer 140 is provided with an adhesive polyurethane composition 170.

[0343] The backing layer 140 is optionally provided with a light blocking cover layer 180 which is detachably secured to the backing layer 140 by a weak adhesive 190. For ease of removal, the light blocking cover layer 180 overlaps the backing layer 140 at its edge 110. In the case where the adhesive is a switchable adhesive composition 170 and contains a photoinitiator driven by UV radiation, or in the case where the adhesive composition is not switchable, the light blocking cover layer 180 may be omitted.

[0344] Figure 2 1 is a perspective view showing an attempt to remove a switchable adhesive dressing 100 from a patient's forearm 14 prior to switching of a switchable adhesive composition comprising a curable portion. Prior to switching, the adhesive composition 171 is very sticky and adheres the adhesive dressing 100 fairly firmly to the patient's skin 20. Therefore, when the patient attempts to peel the dressing 100 from the forearm 14, the dressing 100 remains adhered to the skin 20 unless some force is used to peel the dressing off.

[0345] Figure 31 is a perspective view showing subjecting a switchable adhesive dressing to radiation (in this example from lamp 60) to effect curing of the curable molecules in adhesive composition 170. Light from lamp 60 (UV light or visible light, preferably long wavelength UV) causes the photoinitiator in adhesive composition 170 to generate free radicals, which initiate the curing of the curable molecules in the adhesive composition. Curing transforms (converts) adhesive composition 170 from its viscous state to a non-viscous state or a low-viscous state.

[0346] Figure 4 is a perspective view showing how, after conversion of the adhesive composition, a patient can easily remove the adhesive dressing 100 from the forearm 14 without undue force. Example

[0347] Example 1-2- Cross-linking component (B)

[0348] The reaction was carried out at room temperature with stirring. The solvent B was dried with 1% methacrylate and 2-ethyl-1-hexanol. The components except the catalyst shown in Table 1 below were then added to a reagent bottle and mixed into a uniform solution, after which the catalyst was added. The mixture was left overnight to allow the reaction to complete. After confirming by GPC measurement that no unreacted hydroxypropyl methacrylate or 2-ethyl-1-hexanol was left, the isocyanate functionalized acrylate oligomer was ready for use.

[0349] GPC was performed by diluting the sample with tetrahydrofuran at a ratio of 1:100 and injecting it in an amount of 20 μl into the injection valve of a Waters HPLC 1515 pump using a tetrahydrofuran flow rate of 1 ml / min. The instrument was equipped with a Styragel HR1 column connected to a Waters 2414 refractive index detector.

[0350] The components shown in Table 1 are as follows:

[0351] A polyisocyanate component (i)

[0352] B Solvent

[0353] C Catalyst

[0354] D Stabilizer

[0355] E Compound (ii)

[0356] F compound (iii)

[0357] G Water (iv)

[0358] Table 1

[0359]

[0360] Example 3 - Preparation of polyol component (A)

[0361] All components in Table 2 were placed in a sealable glass jar under protection from UV sources (radiation) and mixed using a magnetic stirrer until all solid materials were dissolved.

[0362] The components shown in the table are as follows:

[0363] H Polyol

[0364] I Photoinitiator I

[0365] C Catalyst

[0366] D Stabilizer, used to prevent premature conversion during storage

[0367] J Surfactant

[0368] K Photoinitiator II

[0369] Table 2

[0370] Reagents Example 3 H Lupranol 2095 (X = 3) 480.00g I Omnirad369 1.12g C BorchiKat22 0.52g D Songnox1010 0.54g J BYK378 0.16g K Omnirad2959 12.50g

[0371] Example 4 - Preparation of polyol component (A)

[0372] The polyol component (A) was prepared in a similar manner to Example 3 using the reagents in Table 3 below.

[0373] Table 3

[0374] Reagents Example 4 H Voranol CP6001 (X = 3) 480.00g I Omnirad369 1.12g C BorchiKat22 0.50g D Songnox1010 0.50g J BYK378 0.16g K Omnirad2959 12.49g

[0375] Example 5-9 - Adhesive Polyurethane Composition

[0376] Examples 5 to 9 are examples of adhesive compositions according to the present invention, which are formulated to contain the crosslinking component (B) from Example 1 and the polymer component (A) from Example 3 in the amounts shown in Table 4. Since these compositions contain a curable compound (ii) in the crosslinking component (B), the adhesive compositions are convertible.

[0377] Under protection from ultraviolet light (radiation), both the A component and the B component in Examples 5 to 9 were placed in a sealable glass jar and mixed to a uniform solution using a magnetic stirrer over a period of about 10 minutes. Then, a spreader with a specification of 150 μm was used to spread the resulting adhesive solution onto a flexible medical polyurethane film (medical film 48938) with a removable carrier film. The adhesive coating was then cured at 130° C. for 10 minutes in an oven assisted by a ventilation fan. After this step, the thickness of the adhesive coating was about 70-90 μm.

[0378] Table 4

[0379] Example 5 Example 6 Example 7 Example 8 Example 9 Cross-linking component (B) Example 1 13.02g 12.52g 12.03g 11.84g 11.44g Polymer Component (A) Example 3** 25.02g 25.03g 25.02g 25.04g 25.01g NCO / OH* 0.969 0.932 0.895 0.881 0.852

[0380] *NCO / OH represents the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic hydroxyl groups in the polyol component (A)

[0381] **The water content of Lupranol 2095 is 0.038 wt%

[0382] Examples 10 to 14 - Adhesive Polyurethane Compositions

[0383] Examples 10 to 14 are examples of switchable adhesive compositions according to the present invention, which are formulated to contain the crosslinking component (B) from Example 2 and the polymer component (A) from Example 4 in the amounts shown in Table 5.

[0384] The adhesives were prepared according to the procedures set out in Examples 5 to 9.

[0385] Table 5

[0386] Example 10 Embodiment 11 Example 12 Example 13 Embodiment 14 Cross-linking component (B) Example 2 10.39g 10.12g 9.70g 9.52g 9.31g Polymer Component (A) Example 4 25.02g 25.02g 25.02g 25.10g 25.04g NCO / OH 0.981 0.955 0.916 0.896 0.878

[0387] *NCO / OH represents the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic hydroxyl groups in the polyol component (A)

[0388] **The water content of Lupranol 2095 is 0.038 wt%

[0389] Peel force measurement

[0390] The peel force before and after switching was measured for each of the adhesives of Examples 5 to 14. In preparation for the peel force measurement, a very easy release liner was transferred to the exposed side of the adhesive. The removable carrier film was then removed from the medical film and replaced with a high adhesion PET tape. The PET tape was secured to the medical film in order to counteract the elastic effect of the medical film on the measured peel force.

[0391] The peel force was measured after a dwell time of 20 minutes using an Instron 5943 test stand equipped with a 100 N load cell according to FINAT test method FTM1, except that stainless steel was used as the substrate surface and a peel rate of 100 mm / min and a crosshead speed of 200 mm / s were used in order to collect all necessary data within the time frame of one peel force measurement.

[0392] Adhesive switching was achieved by exposing the adhesive (adhered to the steel plate) to a light intensity of approximately 50 W / m 2, from a XeLED-Ni3UV-R4-365-E27-SS lamp with a narrow spectrum of about 365nm. The conversion time for different coatings is measured as the time between the start time of the radiation and the time when the substantial instantaneous loss of viscosity occurs during a continuous peel strength test of about 1.5 minutes (i.e., peeling the adhesive for a period of time while irradiating). The peel force measurement is continued under radiation until the peel force reaches a plateau value, which usually occurs 5-10 seconds after the conversion time. The peel force and conversion time at the plateau value are measured in quadruplicate, and the average values ​​of the conversion time and peel force (before and after conversion) are reported in Table 6.

[0393] Cytotoxicity assessment

[0394] The cytotoxicity of the adhesive forming examples was measured according to the guidelines of ISO 10993-5, Biological evaluation of Medical Devices, Part 5: Test for In Vitro Cytotoxicity, and the criteria for the elution test are shown below in Table 6. In order to determine whether a sample passes the test, the measured viability must meet or exceed a value of 70%.

[0395] The results of the peel force measurements are shown together with the viability results from the cytotoxicity measurements in Table 6. If not mentioned otherwise, a clean adhesive failure between the substrate steel surface and the adhesive was achieved.

[0396] Table 6

[0397]

[0398] As can be seen in Table 6, in all cases, a peel force reduction of about 99% was achieved, and the switched peel force appeared to be independent of the unswitched peel force.

[0399] The survival rate measurement results of the adhesives in Examples 5-9 and Examples 10-14 vs. their NCO index are shown in the graphs Figure 5 and Figure 6 middle.

[0400] Figure 5 Results of cytotoxicity tests of adhesives based on the triol Lupranol 2095 with different ratios of A to B components are presented.

[0401] Figure 6 Results of cytotoxicity tests of adhesives based on the triol Voranol CP6001 with different ratios of A to B components are presented.

[0402] As in Figure 5 and Figure 6 As can be seen in the Figure 1, there is a strong correlation between the survival rate and the NCO index, and because the concentration changes of the components involved are relatively small at the current ratios, without wishing to be bound by theory, it is believed that the increase in survival rate with the NCO index is due to the reduction of remaining unreacted polyol hydroxyls. One possible reason for the toxicity of unbound polyols is that the polyols have some surface activity and thus damage cell membranes, similar to many other detergents, such as ordinary soaps.

[0403] Example 15 - Cross-linking component (B)

[0404] A crosslinking component (B) was prepared in a similar manner to Example 1 and Example 2 using the following components.

[0405] Table 7

[0406]

[0407] Example 16 and Example 17 - Adhesive Polyurethane Compositions

[0408] The adhesive polyurethane compositions of Examples 16 and 17 were prepared in a similar manner to Examples 5-9.

[0409] Table 8

[0410] Example 16 Embodiment 17 Cross-linking component (B) Example 15 8.74g 9.08g Polymer Component (A) Example 3 20.05g 20.05g

[0411] Peel force and survival rate measurements were obtained and the values ​​are shown in Table 9.

[0412] Table 9

[0413]

[0414] Examples 18-20 - Cross-linking component (B)

[0415] The reaction was carried out at room temperature with stirring. The solvent B was dried with 1% methacrylate and 2-ethyl-1-hexanol. The components except the catalyst shown in Table 1 below were then added to a reagent bottle and mixed into a uniform solution, after which the catalyst was added. The mixture was left overnight to allow the reaction to complete. After confirming by GPC measurement that no unreacted hydroxypropyl methacrylate or 2-ethyl-1-hexanol was left, the isocyanate functionalized acrylate oligomer was ready for use.

[0416] GPC was performed by diluting the sample with tetrahydrofuran at a ratio of 1:100 and injecting it in an amount of 20 μl into the injection valve of a Waters HPLC 1515 pump using a tetrahydrofuran flow rate of 1 ml / min. The instrument was equipped with a Styragel HR1 column connected to a Waters 2414 refractive index detector.

[0417] After confirming that all hydroxyl-containing species have reacted, the NCO content is measured according to ASTM Standard D 2572-97 (Reapproved 2003).

[0418] The components shown in Table 10 are as follows:

[0419] A polyisocyanate component (i)

[0420] B Solvent

[0421] C Catalyst

[0422] D Stabilizer

[0423] E Compound (ii)

[0424] F compound (iii)

[0425] G Water (iv)

[0426] Table 10

[0427]

[0428] Example 21 - Preparation of polyol component (A)

[0429] All components in Table 11 were placed in a sealable glass jar under protection from UV sources (radiation) and mixed using a magnetic stirrer until all solid materials were dissolved.

[0430] The components shown in Table 11 are as follows:

[0431] H Polyol

[0432] I Photoinitiator I

[0433] B Solvent

[0434] C Catalyst

[0435] D Stabilizer, used to prevent premature conversion during storage

[0436] J Surfactant

[0437] K Photoinitiator II

[0438] Table 11

[0439] Reagents Embodiment 21 H Voranol CP6001 (X = 3) 452.5g I Omnirad369 0g B Ethyl acetate 0g C BorchiKat22 0.34g D Songnox1010 0g J BYK378 0g K Omnirad2959 0g

[0440] Examples 22-24 - Adhesive Polyurethane Compositions

[0441] Examples 22-24 are adhesive compositions according to the present invention, which are formulated to contain the crosslinking component (B) from Example 18 and the polymer component (A) from Example 21 in the amounts shown in Table 12. Since these compositions contain a curable compound (ii) in the crosslinking component (B), the adhesive compositions are convertible.

[0442] Under protection from ultraviolet light (radiation), both the A component and the B component in Example 22 to Example 24 were placed in a sealable glass jar and mixed to a uniform solution using a magnetic stirrer over a period of about 10 minutes. Then, a spreader with a specification of 150 μm was used to spread the resulting adhesive solution onto a flexible medical polyurethane film (Medical Film 48938) with a removable carrier film. The adhesive coating was then cured at 130° C. for 10 minutes in a ventilation fan-assisted oven. After this step, the thickness of the adhesive coating was about 70-90 μm.

[0443] Table 12

[0444] Embodiment 22 Embodiment 23 Embodiment 24 Cross-linking component (B) Example 18 5.57g 5.28g 5.15g Polymer Component (A) Example 21 15.08g 15.19g 15.03g NCO / OH 1.048 0.987 0.973

[0445] Examples 25-27 - Adhesive Polyurethane Compositions

[0446] Examples 25-27 are examples of switchable adhesive compositions according to the present invention formulated to contain the crosslinking component (B) from Example 19 and the polymer component (A) from Example 21 in the amounts shown in Table 13.

[0447] The adhesive was prepared according to the procedures set forth in Examples 22-24.

[0448] Table 13

[0449] Embodiment 25 Embodiment 26 Embodiment 27 Cross-linking component (B) Example 19 4.76g 4.65g 4.54g Polymer Component (A) Example 21 15.16g 15.17g 15.15g NCO / OH 0.919 0.898 0.878

[0450] Examples 28-29 - Adhesive Polyurethane Compositions

[0451] Examples 28-29 are examples of switchable adhesive compositions according to the present invention formulated to include the crosslinking component (B) from Example 20 and the polymer component (A) from Example 21 in the amounts shown in Table 14.

[0452] The adhesive was prepared according to the procedures set forth in Examples 22-24.

[0453] Table 14

[0454] Embodiment 28 Embodiment 29 Cross-linking component (B) Example 20 6.13g 5.97g Polymer Component (A) Example 21 15.12g 15.19g NCO / OH 0.986 0.948

[0455] Peel force measurement

[0456] The peel force before and after conversion was measured for each of the adhesives of Examples 22 to 29. In preparation for the peel force measurement, the release liner was transferred to the exposed side of the adhesive. The removable carrier film was then removed from the medical film and replaced with a high adhesion PET tape. The PET tape was secured to the medical film in order to counteract the elastic effect of the medical film on the measured peel force.

[0457] The peel strength was determined after a 20 minute dwell time using an Instron 5943 test stand equipped with a 100 N load cell according to FINAT test method FTM1, except that stainless steel was used as the substrate surface, and a peel rate of 100 mm / min, a crosshead speed of 200 mm / s was used, so that all necessary data were collected within the time frame of one peel force measurement. The results are shown in Table 15.

[0458] Table 15

[0459]

[0460] As can be seen from Table 5, as previously shown, a decrease in the NCO index results in an increase in the peel force for all three series, which means that the peel force can be adjusted by the NCO index. It should also be noted that the highest peel forces in each series (Example 24, Example 27 and Example 29) represent the maximum achievable peel force values ​​for each combined A component and B component that can be achieved without cohesive failure. In addition, it can be expected that the true NCO index of the final adhesive is somewhat lower than the actual calculated NCO index, because in this case, the isocyanate functional groups can also be expected to react internally and with ambient moisture.

[0461] Material

[0462] The following materials were used in the examples described above.

[0463]

[0464]

Claims

1. An adhesive composition comprising the reaction product of (A) and (B): (A) a polymer component having a weight average molecular weight in the range of 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2; (B) a cross-linking component obtained by reacting (i) with at least one of (ii) and (iii): (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functional groups per molecule; (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom; (iii) at least one compound which comprises a nucleophilic functional group containing an active hydrogen atom and which does not comprise a functional group curable by free radical polymerization; wherein the total degree of substitution of the polyisocyanate component (i) by the compound (ii) and the compound (iii) is in the range of 0.1 to 0.7; and wherein the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.

8.

2. The adhesive composition of claim 1, wherein X has a value of at least 2.2, or at least 2.4, or at least 2.6, or at least 2.8, or at least 3, or at least 3.

2.

3. An adhesive composition according to any one of claims 1 or 2, wherein the polymer component is a polyol, preferably a polyol containing an average of 2.8 to 5 hydroxyl groups per molecule.

4. The adhesive composition of claim 3, wherein at least 50 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 60 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 70 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 80 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups, or wherein at least 90 mol% of the hydroxyl groups in the polyol are found in polyol molecules containing 3 to 5 hydroxyl groups.

5. The adhesive polyurethane composition according to any preceding claim, wherein the polymer component (A) is a polyol selected from hydroxyl terminated polyethers and hydroxyl terminated polyesters.

6. The adhesive polyurethane composition according to claim 5, wherein the hydroxyl terminated polyether is an alkoxylated derivative of a compound containing 3 to 5 hydroxyl groups, or a mixture thereof.

7. The adhesive polyurethane composition according to claim 6, wherein the compound containing 3 to 5 hydroxyl groups is selected from glycerol, trimethylolpropane, erythritol, pentaerythritol, penta-1,2,4,5-tetrol, glucose, and mixtures thereof, preferably wherein the alkoxylated derivative is an ethoxylated derivative, a propoxylated derivative or an ethoxylated-co-propoxylated derivative.

8. An adhesive polyurethane composition according to any preceding claim, wherein the polymer component has a weight average molecular weight in the range of 1,000 to 50,000 Daltons, preferably in the range of 1,000 to 20,000 Daltons, preferably in the range of 1,500 to 10,000 Daltons.

9. The adhesive polyurethane composition according to any preceding claim, wherein the polymer component has an equivalent weight per nucleophilic functional group of 200 to 5,000, preferably 500 to 2,500, preferably 1,000 to 2,000.

10. The adhesive polyurethane composition according to any preceding claim, wherein the polyisocyanate component (i) comprises an average of 2 to 4 isocyanate functional groups per molecule, preferably an average of 2.1 to 3.6 isocyanate functional groups per molecule, preferably an average of 2.1 to 3.5 isocyanate functional groups per molecule, preferably an average of 2.2 to 3.4 isocyanate functional groups per molecule, preferably an average of 2.5 to 3.4 isocyanate functional groups per molecule.

11. The adhesive polyurethane composition according to claim 10, wherein the polyisocyanate component (i) comprises a trimerized diisocyanate of the formula D(R-NCO)3, wherein D represents a ring structure selected from isocyanurate and iminooxadiazinedione or a branched structure selected from biuret and allophanate, and mixtures thereof, and each R independently represents a linear, branched or cyclic alkylene group having 2 to 15 carbon atoms or an aryl group having 6 to 20 carbon atoms, preferably wherein the trimerized diisocyanate is trimerized hexamethylene diisocyanate.

12. Adhesive composition according to any preceding claim, wherein the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with compound (ii) and optionally the compound (iii).

13. The adhesive polyurethane composition of claim 12, wherein the degree of substitution of the compound (ii) for the polyisocyanate component (i) is in the range of 0.05 to 0.5; or in the range of 0.05 to 0.45, or in the range of 0.05 to 0.4, or in the range of 0.8 to 0.35, or in the range of 0.8 to 0.3, or in the range of 0.1 to 0.25, or in the range of 0.1 to 0.2, or in the range of 0.12 to 0.

18.

14. The adhesive polyurethane composition according to claim 12 or claim 13, wherein the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is in the range of 0.15 to 0.65, or in the range of 0.2 to 0.6, or in the range of 0.25 to 0.6, or in the range of 0.3 to 0.

6.

15. The adhesive polyurethane composition according to any one of claims 12 to 14, wherein the at least one compound (ii) comprises an olefin moiety as a functional group curable by free radical polymerization.

16. The adhesive polyurethane composition according to claim 15, wherein the at least one compound (ii) is selected from hydroxy-substituted acrylates, hydroxy-substituted methacrylates, and mixtures thereof; preferably wherein the at least one compound (ii) is selected from hydroxy-(C2-C 20 ) alkyl-substituted methacrylates, polyalkoxylated monomethacrylates containing 2 to 10 ether functional groups, and mixtures thereof; preferably wherein the compound (ii) is selected from 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, and mixtures thereof.

17. The adhesive polyurethane composition according to any one of claims 12 to 16, comprising 0.05 to 1 meq / g, preferably 0.06 to 0.5 meq / g, preferably 0.08 to 0.4 meq / g, preferably 0.1 to 0.3 meq / g, preferably 0.12 to 0.25 meq / g, preferably 0.15 to 0.2 meq / g of the functional group curable by free radical polymerization.

18. The adhesive polyurethane composition according to any one of claims 12 to 17, wherein the adhesive has a peel force reduction of 30% to 99%, preferably 50% to 99%, preferably 70% to 99% after switching.

19. The adhesive polyurethane composition according to any one of claims 1 to 11, wherein the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with the compound (iii), and wherein the compound (ii) is not present.

20. The adhesive polyurethane composition according to claim 19, wherein the degree of substitution of the compound (iii) to the polyisocyanate component (i) is in the range of 0.15 to 0.65, or in the range of 0.2 to 0.6, or in the range of 0.25 to 0.6, or in the range of 0.3 to 0.

6.

21. The adhesive polyurethane composition according to any one of claims 12 to 20, wherein the at least one compound (iii) comprises or consists of: One or more C1-C 30 Aliphatic alcohols, preferably linear, branched or cyclic C1-C 18 Aliphatic alcohols, preferably linear, branched or cyclic C1-C 12 Aliphatic alcohol, preferably branched C3-C 12 Aliphatic alcohols, or branched C6-C 18 Aliphatic alcohol.

22. The adhesive polyurethane composition of any preceding claim, wherein the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups containing active hydrogen atoms in the polymer component (A) is at least 0.81, or at least 0.82, or at least 0.83, or at least 0.84, or at least 0.85, or at least 0.86, or at least 0.87, or at least 0.88, or at least 0.89, or at least 0.90, or at least 0.91, or at least 0.92, or at least 0.93, or at least 0.94, or at least 0.

95.

23. An adhesive polyurethane composition according to any preceding claim, wherein the maximum degree of substitution of the polyisocyanate component (i) by water does not exceed 0.1, preferably does not exceed 0.08, preferably does not exceed 0.06, preferably does not exceed 0.05, preferably does not exceed 0.

04.

24. The adhesive polyurethane composition according to any preceding claim further comprising a photoinitiator, preferably 0.05 to 5 wt% photoinitiator, preferably 0.1 to 5 wt% photoinitiator, preferably 0.2 to 2 wt% photoinitiator.

25. The adhesive polyurethane composition according to claim 24, wherein the at least one compound (iii) comprises or consists of one or more hydroxyl-substituted photoinitiators.

26. An adhesive polyurethane composition according to claim 24 or claim 25, wherein the photoinitiator is reactive to UV light.

27. The adhesive polyurethane composition according to any one of claims 24 to 26, wherein the photoinitiator is selected from benzoin and derivatives; benzophenone and derivatives; acetophenone; 4-phenoxyacetophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone; 2-dimethylamino-2-( 4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one; 2-ethylanthraquinone; benzil dimethyl ketal; 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropanone; 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)benzyl)-phenyl]-2-methylpropan-1-one; 2-hydroxy-2-methylpropiophenone; and ethyl-4-dimethylaminobenzoate.

28. The adhesive polyurethane composition of any preceding claim further comprising a solvent.

29. The adhesive polyurethane composition of any preceding claim further comprising a stabilizer.

30. A method for preparing an adhesive polyurethane composition comprising: (a) a first step of reacting (i) with at least one of (ii) and (iii) to form a crosslinking component (B): (i) a polyisocyanate component having an average of 1.8 to 6 isocyanate functional groups per molecule; (ii) at least one compound comprising a functional group curable by free radical polymerization and further comprising a nucleophilic functional group containing an active hydrogen atom; (iii) at least one compound which comprises a nucleophilic functional group containing an active hydrogen atom and which does not comprise a functional group curable by free radical polymerization; wherein the total degree of substitution of the compound (ii) and the compound (iii) for the polyisocyanate component (i) is in the range of 0.1 to 0.7; (b) a second step of combining the crosslinking component (B) formed in step (a) with a polymer component (A), the polymer component (A) having a weight average molecular weight in the range of 1,000 to 100,000 Daltons and containing an average of X nucleophilic functional groups containing active hydrogen atoms per molecule, wherein X represents a number having a value of at least 2, The amounts of the crosslinking component (B) and the polyol component (A) are selected so that the molar ratio of the unsubstituted isocyanate functional groups in the crosslinking component (B) to the nucleophilic functional groups containing active hydrogen atoms in the polymer component (A) is at least 0.

8.

31. The process according to claim 30, wherein step (a) and / or step (b) is performed in the presence of a catalyst.

32. A process according to claim 30 or claim 31 , wherein step (a) and / or step (b) is carried out in the presence of a solvent.

33. A method according to any one of claims 30 to 32, wherein the adhesive composition is as defined in any one of claims 1 to 29.

34. An adhesive medical device comprising a layer of an adhesive composition as defined in any one of claims 1 to 29 disposed on a first carrier film and a release liner disposed over the adhesive layer.

35. The adhesive medical device of claim 34, wherein the first carrier film is UV translucent, optionally wherein a removable UV blocking layer is laminated to the first carrier film on the surface opposite the adhesive composition.

36. A method of treating a wound using an adhesive medical device as defined in claim 34 or claim 35, the method comprising removing the release liner and applying the adhesive medical device to the wound.

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