Switchable adhesive composition

Abstract

The present invention relates to a polyurethane-based pressure-sensitive adhesive composition containing a curable moiety. The adhesive composition is "switchable" from a tacky state to a non-tacky state by initiating curing of the curable moiety. The adhesive composition comprises the reaction product of: (A) a polymer component having at least two nucleophilic functional groups with active hydrogen atoms; and (B) a crosslinking component obtained by reacting a polyisocyanate component with a compound containing functional groups curable by free radical polymerization and further containing nucleophilic functional groups with active hydrogen atoms.

Description

[Technical Field]

[0001] The present invention relates to switchable adhesive compositions, and in particular to polyurethane-based pressure-sensitive adhesive compositions that contain curable moieties. The present invention also relates to methods of making the adhesive compositions and to articles that include the switchable adhesive compositions.

[0002] The adhesive compositions of the present invention are "switchable" from a tacky to a non-tacky state by initiating curing of the curable portion, which reduces the adhesive's tack, as evidenced by a decrease in the peel strength of the switched adhesive compared to the unswitched adhesive.

[0003] The adhesive composition of the present invention is useful in a variety of applications where an article needs to be adhered to a surface for a period of time and then removed. Although the adhesive composition of the present invention can be used with a variety of substrates, it is particularly useful in applications where a strong bond to delicate surfaces is required.

[0004] In particular, the adhesive compositions of the present invention find utility in adhesive medical products that are applied to a patient's skin, because switching the adhesive composition to a low tack state allows the medical product to be removed with less pain and / or damage to the underlying tissue. Such medical products are particularly useful for patients with sensitive skin (e.g., infants, particularly newborns, and the elderly), as well as patients with trauma or long-term medical conditions that require repeated application of dressings. [Background technology]

[0005] Many types of medical products, such as surgical or medical dressings and bandages, contain a layer of pressure-sensitive adhesive to allow the medical product to be attached to a patient's skin. Adhesives used for this purpose must be strong enough to form a strong bond to the skin so that they can resist peeling or accidental removal during use. However, traditional adhesives with these properties can cause local trauma and / or pain to the patient when the dressing or bandage is removed from the skin. This is particularly true for patients with long-term conditions, such as stoma patients, who require adhesive dressings to be applied repeatedly to the same body part over an extended period of time. It is also true for patients with fragile skin, particularly the elderly and children.

[0006] Thus, a need has been identified for providing a "switchable" pressure-sensitive adhesive that has a high initial peel strength but can be switched to a form with significantly lower peel strength when removal of the adhered product is desired. Such an adhesive would allow the medical product to be securely attached to the skin during use, but also allow it to be easily removed without causing local trauma and / or pain to the patient upon removal. For adhesive medical products to be useful, they would further need to be able to achieve a reduction in peel strength in a controlled manner and over a relatively short period of time, e.g., from a few seconds to at most a few minutes.

[0007] For convenience, the term "switchable" will be used to refer to an adhesive composition that can be changed from a tacky state to a non-tacky state, or more precisely to a very low tack state. Recognizing that the expression "low tack" is a relative term, it will be defined herein to mean the minimum tack state that the adhesive composition reaches after being switched from its tacky state. The reduction in peel force may be as much as 99% or as little as 30%. Typically, the reduction in peel force is about 99% for HDPE and about 90% for skin.

[0008] Switchable adhesive forms are disclosed in U.S. Patent Nos. 5,629,599; 5,729,599; 5,729,599; and 5,829,599. These documents describe adhesives that become less tacky when in contact with water. However, such adhesives are unsuitable for use on wound dressings where the patient's wound needs to remain dry.

[0009] Patent documents 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 191, 192, 193, 194, 195, 196, 200, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290

[0010] Patent documents 8 to 10 disclose adhesives that are switchable when exposed to visible light or low doses of UV light. The switchable adhesives described in these documents generally include acrylic adhesives based on copolymers of alkyl acrylates, acrylic acid, and / or free-radically polymerizable vinyl moieties that are "modified" or functionalized with attached curing moieties. Typical attached curing moieties are derived from anthracene, cinnamate, maleimide, coumarin, acrylate, and / or methacrylate.

[0011] Patent Document 11 discloses a radiation-curable tape including an adhesive disposed on a radiation-transparent substrate that can be cured by irradiation with ionizing radiation, such as UV or an electron beam. The radiation-curable adhesive is composed of an acrylic adhesive, a compound having a carbon-carbon double bond, and a silicone acrylate compound. This radiation-curable tape can be used in processing steps for producing semiconductor wafers, ceramics, and glass using a direct pickup system.

[0012] Patent Document 12 discloses a pressure-sensitive adhesive composition containing an acrylic copolymer (A), an energy beam-polymerizable urethane acrylate oligomer (B), and an energy beam-polymerizable compound (C) having one acryloyl or methacryloyl group in each molecule thereof. This composition preferably also contains a plasticizer (D), a crosslinker (E), and / or a photopolymerization initiator (F) as needed.

[0013] The present inventors' US Patent Application Publication No. 2007 / 0129999 (Patent Document 13) discloses a switchable adhesive composition based on a polyurethane adhesive. Unsaturated curable molecules can be mixed and / or bonded to the polyurethane polymer backbone. Photoinitiated curing of the curable molecules results in the formation of a crosslinked network, which reduces the peel strength of the adhesive.

[0014] Despite the above developments, there remains a need in the art for improved curable adhesives that exhibit the following properties: high peel strength before switching, low peel strength after switching, and short switching times after switching is initiated. It has been found that adhesive formulations with good adhesive properties often demonstrate poor switching ability, and adhesive formulations with good switching ability often demonstrate low peel strength and / or low cohesion (the adhesive has low internal strength such that the bonded material will detach from the surface, leaving behind adhesive residue on the surface). Thus, when developing switchable adhesives, it is particularly challenging to simultaneously obtain high peel strength, high cohesion, and good switching ability.

[0015] Further desirable properties of switchable adhesives include stability in the unswitched state both during storage and when adhered to a substrate, as well as ease of manufacturing without complex synthesis steps, long processing times, or premature activation of the switching process during handling of the adhesive on an assembly line. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] US5,032,637 [Patent Document 2] US5,352,516 [Patent Document 3] US4,331,576 [Patent Document 4] US5,182,323 [Patent Document 5] US2013 / 0123678 [Patent Document 6] WO2010 / 129299 [Patent Document 7] WO2013 / 066401 [Patent Document 8] EP0863775 [Patent Document 9] US6,184,264 [Patent Document 10] US6,610,762 [Patent Document 11] US4,999,242 [Patent Document 12] US5,955,512 [Patent Document 13] WO2016 / 124339 A1 Summary of the Invention [Problem to be solved by the invention]

[0017] The present invention has been devised in view of the shortcomings of known switchable pressure-sensitive adhesive systems as described above, and provides an improved switchable adhesive composition having high peel strength, high cohesion, fast switching time, and low switched peel strength. [Means for solving the problem]

[0018] In a first aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: (A) a polymer component having a weight average molecular weight in the range of 500 to 100,000 daltons and having an average of X nucleophilic functional groups having active hydrogen atoms per molecule, where X represents a number having a value of at least 2; (B) (i) a polyisocyanate component having an average of at least Y isocyanate functional groups per molecule, where Y represents a number ranging from 1.8 to 6; (ii) at least one compound containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom; and (iii) optionally, at least one compound containing a nucleophilic functional group having an active hydrogen atom and no functional group curable by free radical polymerization; wherein the total degree of substitution of the polyisocyanate component (i) with the compounds (ii) and (iii) is at least 0.2 and is not more than the smaller value of 0.3Y or 0.8; The present invention provides an adhesive polyurethane composition comprising the reaction product of

[0019] Thus, crosslinking component (B) is the product of the reaction of polyisocyanate component (i) with compound (ii) containing curable functional groups. Optionally, polyisocyanate component (i) is also reacted with compound (iii) that does not contain curable functional groups. The total degree of substitution of polyisocyanate component (i) is controlled within a specified range so that at least a portion of the isocyanate groups remain unreacted. The unreacted isocyanate groups are available to react with nucleophilic functional groups of polymer component (A) to form a crosslinked adhesive network containing pendant curable groups.

[0020] The degree of substitution of the polyisocyanate component (i) represents the portion of the isocyanate groups of the polyisocyanate component (i) that has been substituted with nucleophilic functional groups having active hydrogen atoms from the compounds (ii) and (iii), and is as follows:

[0021]

number

[0022] When compound (iii) is not present, the total degree of substitution of polyisocyanate component (i) refers to the degree of substitution with compound (ii) only. When compound (iii) is present, the total degree of substitution of polyisocyanate component (i) refers to the total degree of substitution with both compound (ii) and compound (iii).

[0023] The partial reaction of polyisocyanate component (i) with compound (ii) and, optionally, compound (iii) results in a product mixture containing a statistical mixture of substituted polyisocyanates. Some individual polyisocyanate molecules will be substituted at all of their isocyanate groups with compound (ii) and / or (iii), while other polyisocyanate molecules will be completely unsubstituted. Still other polyisocyanate molecules will contain one or more substituted isocyanate groups and one or more unsubstituted isocyanate groups in the same molecule. Thus, the unsubstituted isocyanate groups are available for reaction with nucleophilic functional groups of polymer component (A).

[0024] When individual polyisocyanate molecules are fully substituted with compounds (ii) and / or (iii), the resulting compound does not have free isocyanate groups and cannot react with polymer component (A), but it may function as an unbound curing molecule that can participate in the curing reaction that switches the adhesive from a high tack to a low tack state.

[0025] When individual polyisocyanate molecules (i) are partially substituted with compounds (ii) and / or (iii) or are unsubstituted, they can react with the nucleophilic functional groups of the polymer component, thus bonding to the polyurethane adhesive. Compounds in crosslinking component (B) that have only one unsubstituted isocyanate group will form a terminal urethane / urea / amide bond to the polymer component, thus functioning to bond the curable molecule to the polyurethane adhesive. Compounds in crosslinking component (B) that have two unsubstituted isocyanate groups can crosslink two end groups of the polymer component to form the crosslinked polymer network characteristic of polyurethanes.

[0026] Compounds in crosslinking component (B) having three (or more) unsubstituted isocyanate groups can crosslink three (or more) end groups of the polymer component, thus forming nodes (or branch points) in the polyurethane network where multiple polymer end groups are attached to the same polyisocyanate molecule.

[0027] It has been found that polyurethane-based adhesives formed from mixtures of polyisocyanates with different degrees of substitution result in improved adhesives. Polyurethane adhesives are typically formed by reacting a polymer component with only one type of polyisocyanate molecule (typically a diisocyanate). As a result, the polymer chains are crosslinked solely by the diisocyanate, and therefore the adhesive only has this type of crosslink.

[0028] In contrast, according to the present invention, polymer component (A) is reacted with a variety of different compounds having different numbers of isocyanate groups, resulting in a variety of different bonding modes of polymer component (A). As a result, adhesives with improved adhesive and cohesive properties are obtained. This simultaneously offers the advantage that a significant proportion of curable molecules are bonded to the polyurethane backbone, thereby resulting in adhesives with very low cytotoxicity.

[0029] The adhesive polyurethane compositions of the present invention generally have a gel-like viscosity with a relatively low crosslink density. They are capable of forming polar and van der Waals bonds with the substrate, which gives the adhesive composition its tackiness. When the curing (or switching) reaction is initiated, for example, by exposure to long-wavelength UV or visible light in the presence of a photoinitiator, the curable groups from compound (ii) form chemical bonds with other curable groups. This curing reaction significantly increases the crosslink density within the adhesive composition compared to an unswitched adhesive composition. This reduces the mobility and free volume of the polymer segments of the adhesive composition, meaning that the composition loses its fluidity and essentially becomes an elastic film with little or no tack.

[0030] When a conventional pressure-sensitive adhesive is peeled from a surface to which it is adhered, the energy required is approximately 10 times less than that required from a thermodynamic standpoint, as a result of internal energy losses in the adhesive bulk material, and because at least a portion of the peel force acts in a direction perpendicular to the surface. 2 From 10 4 In the switchable adhesive compositions of the present invention, the dense polymer network formed by the curable functional groups after adhesive switching reduces the tack and flexibility of the bulk material of the composition, thus reducing the required peel force to values ​​closer to those implied by thermodynamic considerations alone.

[0031] Detailed Description of the Invention The adhesive polyurethane composition is obtained by reacting a polymer component (A) (such as a polyether or polyester) with a crosslinking component (B).

[0032] Polymer component (A) The adhesive polyurethane composition of the present invention is formed from the reaction of a polymer component (A) with a crosslinking component (B), where the polymer component has a weight average molecular weight in the range of 500 to 100,000 daltons and has an average of X nucleophilic functional groups per molecule having active hydrogen atoms, where X is a number having a value of at least 2. The nucleophilic functional groups of the polymer component (A) react with the free isocyanate groups of the crosslinking component (B) to form a crosslinked polyurethane adhesive network.

[0033] X preferably has 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. In particular, it is preferred that at least a portion of the polymer molecules in the polymer component (A) have three or more nucleophilic functional groups. Polymer molecules having three or more nucleophilic functional groups can introduce additional crosslinks into the polymer network of the polyurethane adhesive, which contributes to improving the adhesive performance.

[0034] The polymer component (A) is preferably selected from hydroxy-terminated polymers / oligomers. For example, the polymer component (A) may be selected from hydroxy-terminated polyethers, hydroxy-terminated polyesters, amine-terminated polyethers, and amine-terminated polyesters. Preferably, the polymer component is a hydroxy-terminated polyether.

[0035] Suitable hydroxy-terminated polyethers include alkoxylated derivatives of compounds containing 2 to 5 hydroxy groups, or mixtures thereof. For example, suitable polymer components include alkoxylated derivatives of ethylene glycol, propylene glycol, butane-1,4-diol, glycerol, trimethylolpropane, di- or polyethers of trimethylolpropane, erythritol, pentaerythritol, pentane-1,2,4,5-tetrol, dextrose, and / or sorbitol. Preferably, the alkoxylated derivatives are ethoxylated, propoxylated, or ethoxylated-copropoxylated derivatives. Preferably, the hydroxy-terminated polyether may be an ethylene oxide-capped propoxylated derivative of pentaerythritol. Ethylene oxide capping is preferred because the less steric hindrance of the terminal hydroxyl groups promotes faster reaction with the isocyanate groups of crosslinking component (B).

[0036] 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, and preferably in the range of 1,500 to 10,000 daltons. Molecules within this range are generally understood to be less easily absorbed through cell walls and therefore to have low cytotoxicity. This is particularly important in medical applications where the adhesive composition or a medical product containing the adhesive composition is to be applied directly to the skin. However, if the molecular weight of the polymer component (A) is too high, the adhesive will have insufficient adhesive properties.

[0037] The polymer component preferably has an equivalent weight per nucleophilic functional group of from 200 to 5,000, preferably from 500 to 2,000, preferably from 1,000 to 2,000.

[0038] The polymer component preferably has a mono-ol content of 2 mol % or less, preferably 1 mol % or less, preferably 0.5 mol % or less. As mentioned above, a molecule of the polymer component having one nucleophilic functional group can only react with one free isocyanate group of the crosslinking component (B) and therefore cannot contribute to effective crosslinking.

[0039] Crosslinking component (B) The crosslinking component (B) of the adhesive polyurethane composition of the present invention is obtained by reacting the polyisocyanate component (i) with at least one compound (ii) containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom. The free radical curable functional group provides the switching capability of the adhesive composition of the present invention, and the nucleophilic functional group having an active hydrogen atom allows the bonding of compound (ii) to the polyisocyanate component (i).

[0040] The polyisocyanate component (i) may optionally be reacted with at least one compound (compound (iii)) that contains a nucleophilic functional group having an active hydrogen atom but does not contain a functional group curable by free radical polymerization. Thus, compound (iii) may be attached to the polyisocyanate component (i) but does not contribute to the switching ability of the adhesive composition of the present invention.

[0041] The total degree of substitution of the polyisocyanate component (i) with compounds (ii) and (iii) is not more than the smaller of 0.3Y and 0.8, preferably not more than the smaller of 0.28Y and 0.8, and preferably not more than the smaller of 0.28Y and 0.75.

[0042] Although effective adhesives can be obtained with very high degrees of substitution of polyisocyanate component (i), such compositions will require a higher total amount of polyisocyanate to ensure that sufficient free isocyanate groups are still available for reaction with polymer component (A), which may be undesirable for cost reasons.

[0043] The total degree of substitution of the polyisocyanate component (i) with compounds (ii) and (iii) is at least 0.2, preferably at least 0.3, and preferably at least 0.4. At very low degrees of substitution, the crosslinking component (B) contains a high relative amount of unsubstituted or monosubstituted polyisocyanate. This results in closer crosslinking of the polymer components, with more polymer end groups bonded to nodes, for example, three or more polymer end groups bonded. This has been found to result in reduced peel strength of the adhesive. Therefore, by ensuring that the total degree of substitution of the polyisocyanate component (i) is at least 0.2, preferably at least 0.3, or at least 0.4, improved peel strength can be achieved. Particularly good adhesive performance is observed, for example, when the total degree of substitution of the polyisocyanate component (i) is at least 0.45 or at least 0.5.

[0044] For example, the total degree of substitution of polyisocyanate component (i) with compounds (ii) and, if present, (iii) is at least 0.2 and not more than the smaller of 0.3Y and 0.8; at least 0.2 and not more than the smaller of 0.28Y and 0.8; at least 0.2 and not more than the smaller of 0.28Y and 0.75; at least 0.3 and not more than the smaller of 0.3Y and 0.8; at least 0.3 and not more than the smaller of 0.28Y and 0.8; at least 0.3 and not more than the smaller of 0.28Y and 0.75; at least 0.4 and not more than the smaller of 0.3Y and 0.8 at least 0.4 and not more than the smaller of 0.28Y and 0.8; at least 0.4 and not more than the smaller of 0.28Y and 0.75; at least 0.45 and not more than the smaller of 0.3Y and 0.8; at least 0.45 and not more than the smaller of 0.28Y and 0.8; at least 0.45 and not more than the smaller of 0.28Y and 0.75; at least 0.5 and not more than the smaller of 0.3Y and 0.8; at least 0.5 and not more than the smaller of 0.28Y and 0.8; or at least 0.5 and not more than the smaller of 0.28Y and 0.75.

[0045] The crosslinking component (B) is preferably obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii) so that the total degree of substitution of the polyisocyanate component (i) is within the above-mentioned range. As mentioned above, partial substitution of the polyisocyanate component (i) is desirable to obtain a distribution of different isocyanate-containing compounds in the crosslinking component (B). However, achieving the required degree of substitution of the polyisocyanate component (i) with only the compound (ii) tends to result in an adhesive containing far more curable groups than necessary to obtain good switching performance. While effective adhesives can be obtained with a very high degree of substitution of the polyisocyanate component (i) with the compound (ii), it is preferable that the adhesive composition does not contain far more curable groups than necessary for adhesive switching. Excessive amounts of curable groups can require careful handling during the manufacture of adhesives and products containing the adhesive. Excessive substitution of the polyisocyanate component (i) with the compound (ii) is also undesirable for cost and biocompatibility reasons.

[0046] One particular consequence of compositions containing a high concentration of curing groups is that shear forces in the equipment used to handle the adhesive during the manufacturing process (e.g., pumps, flow lines, etc.) can initiate premature curing of the curing groups. This can lead to poor tack in the adhesive product and, in some cases, can cause blockages in the manufacturing equipment. Therefore, the use of compound (iii) can alleviate these problems by allowing for a sufficient degree of substitution of polyisocyanate component (i) without introducing excessive curing groups into the adhesive composition.

[0047] When polyisocyanate component (i) is substituted with both compound (ii) and compound (iii), the degree of substitution of polyisocyanate component (i) with compound (ii) is 0.6 or less, preferably 0.55 or less, preferably 0.5 or less, preferably 0.4 or less, preferably 0.3 or less, preferably 0.25 or less, preferably 0.2 or less, preferably 0.18 or less.

[0048] When polyisocyanate component (i) is substituted with both compound (ii) and compound (iii), to ensure sufficient content of curable groups for effective switching performance, the degree of substitution of polyisocyanate component (i) with compound (ii) is preferably at least 0.05, preferably at least 0.06, preferably at least 0.07, preferably at least 0.08, preferably at least 0.1, preferably at least 0.12. At very low degrees of substitution of polyisocyanate component (i) with compound (ii), the relative amount of curable groups will be low, which may reduce the switching performance of the adhesive after curing.

[0049] For example, if polyisocyanate component (i) is substituted with both compound (ii) and compound (iii), the degree of substitution of polyisocyanate component (i) with compound (ii) is: at least 0.05 and not more than 0.5; or at least 0.05 and not more than 0.4; or at least 0.05 and not more than 0.3; or at least 0.05 and not more than 0.25; or at least 0.05 and not more than 0.2; or at least 0.06 and not more than 0.4; or at least 0.06 and not more than 0.3; or at least 0.06 and not more than 0.25; or at least 0.06 and 0.2 or less; or at least 0.08 and 0.4 or less; or at least 0.08 and 0.3 or less; or at least 0.08 and 0.25 or less; or at least 0.08 and 0.2 or less; or at least 0.1 and 0.3 or less; or at least 0.1 and 0.25 or less; or at least 0.1 and 0.2 or less; or at least 0.1 and 0.18 or less; or at least 0.12 and 0.3 or less; or at least 0.12 and 0.25 or less; or at least 0.12 and 0.2 or less; or at least 0.12 and 0.18 or less.

[0050] Polyisocyanate component (i) The polyisocyanate component (i) has an average of at least Y isocyanate functional groups per molecule, where Y represents a number that can be in the range of 1.8 to 6, preferably in the range of 2 to 4, preferably in the range of 2 to 3.6, preferably in the range of 2.1 to 3.5, preferably in the range of 2.2 to 3.4. It will be understood that the polyisocyanate component (i) may be a single polyisocyanate compound or may comprise a mixture of different polyisocyanate compounds, so long as the average number of polyisocyanate groups per molecule is within the specified range. In this context, the term "average" refers to the average number of isocyanate functional groups per isocyanate-containing molecule (i.e., [total moles of isocyanate functional groups] / [total moles of isocyanate-containing molecules]).

[0051] When Y is within these ranges, polyisocyanate component (i) comprises an appropriate mixture of substituted polyisocyanates having different degrees of substitution, which has been found to result in improved adhesion.

[0052] The polyisocyanate component (i) may, in principle, be selected from any of the numerous isocyanate group-containing compounds known in the art for producing polyisocyanates, as well as mixtures thereof. For example, the polyisocyanate component (i) may comprise one or more polyisocyanate compounds selected from the group of polyisocyanates having 2 to 10 isocyanate functional groups per molecule and mixtures thereof, so long as Y is within the range of 1.8 to 6. Preferably, the polyisocyanate component (i) comprises one or more polyisocyanate compounds selected from the group of polyisocyanates having 2 to 4 isocyanate functional groups per molecule.

[0053] Optionally, the polyisocyanate component (i) may comprise a mixture of a diisocyanate and at least one polyisocyanate having an average of at least three isocyanate functional groups per molecule. It has been observed that mixtures of diisocyanates with other polyisocyanates result in adhesives that are more resistant to humidity. This is beneficial in medical applications where the adhesive must adhere to the skin, which can be subject to sweat secretion.

[0054] Examples of suitable polyisocyanates include diisocyanates of the formula OCN-R-NCO, where 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'-methylenebis(phenylisocyanate), and 4,4'-methylenebis(cyclohexylisocyanate). Further suitable polyisocyanates include polymers (e.g., dimers, trimers, tetramers, etc.) based on diisocyanates.

[0055] A preferred polyisocyanate is a trimerized diisocyanate of the formula D(R-NCO)3, where D represents a ring structure selected from isocyanurates, iminooxadiazinedione, and mixtures thereof, and each R independently represents a linear, branched, or cyclic alkylene group having from 2 to 15 carbon atoms, or an arylene group having from 6 to 20 carbon atoms. A particularly preferred polyisocyanate is trimerized hexamethylene diisocyanate.

[0056] Compound (ii) The crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with at least one compound (ii) containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom.

[0057] As used herein, the term "nucleophilic functional group having an active hydrogen atom" refers to a functional group that can undergo an addition reaction with an isocyanate group to form an adduct. For example, the nucleophilic functional group having an active hydrogen atom may be -OH, -COOH, -NH, -SH, etc. Preferably, the nucleophilic functional group having an active hydrogen atom is a hydroxyl group (-OH). Preferably, the nucleophilic functional group having an active hydrogen atom is a hydroxyl group bonded to a primary carbon atom (i.e., a group of the formula -CHOH). The nucleophilic hydroxyl group can readily react with the isocyanate group of the polyisocyanate component (i), and hydroxyl-containing compounds having curable moieties are readily available in the art. Preferably, at least one compound (ii) contains a single nucleophilic functional group having an active hydrogen atom.

[0058] At least one compound (ii) preferably contains an olefin moiety as a functional group curable by free radical polymerization. At least one compound (ii) may be a single compound or a mixture of different compounds, each containing an olefin moiety as a functional group curable by free radical polymerization. Olefin moieties (e.g., acrylates and methacrylates) tend to have high yields in polymerization reactions and are therefore good curable groups for achieving effective switching performance through a free radical-initiated curing process.

[0059] Preferably, at least one compound (ii) comprises an olefinic moiety as the functional group curable by free radical polymerization and a hydroxyl group as the nucleophilic functional group having an active hydrogen atom.

[0060] In the broadest sense, any unsaturated compound that is curable by free radical polymerization and further contains a nucleophilic functional group with an active hydrogen atom can be used as compound (ii). Examples of suitable compounds include hydroxy-substituted acrylate esters and hydroxy-substituted methacrylate esters. Preferably, at least one compound (ii) is a hydroxy-substituted -(C2-C 20) Alkyl methacrylate ester, hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters, polyalkoxylated monomethacrylate esters having 2 to 10 ether functional groups, polyalkoxylated monoacrylate esters having 2 to 10 ether functional groups, and mixtures thereof. More preferably, the at least one compound (ii) is selected from hydroxy-substituted -(C2-C6) alkyl methacrylate esters.

[0061] For example, compound (ii) may be selected from 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, polypropylene glycol monomethacrylate, and polypropylene glycol monoacrylate. Preferred compounds (ii) are 2-hydroxypropyl methacrylate, hydroxyethyl methacrylate, and mixtures thereof.

[0062] At least one compound (ii) may be a single compound or a mixture of compounds, each of which has a functional group curable by free radical polymerization and a nucleophilic functional group having an active hydrogen atom. When 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.

[0063] Other examples of hydroxyl-containing acrylates include hydroxyl (CH2) esters where n is 4 to 8. n Methacrylic acid ester, hydroxyethyl methacrylate caprolactone ester (caprolactone 2-(methacryloyloxy)ethyl ester), 3-(acryloyloxy)-2-hydroxypropyl methacrylate, and glycerol dimethacrylate.

[0064] Compound (iii) The crosslinking component (B) may optionally be obtained by reacting the polyisocyanate component (i) with both at least one compound (ii) and at least one compound (iii). The at least one compound (iii) contains a nucleophilic functional group having an active hydrogen atom but does not contain a functional group curable by free radical polymerization. The at least one compound (iii) may be a single compound or a mixture of different compounds, none of which contains a functional group curable by free radical polymerization.

[0065] As mentioned above, only a certain content of curing groups is required to achieve good switching performance. Therefore, compound (iii) can be included in the adhesive composition of the present invention to obtain an advantageous distribution of compounds with different numbers of isocyanate groups in the crosslinking component (B) without including an excessive amount of curing groups.

[0066] At least one compound (iii) is a 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 a branched C3-C aliphatic alcohols. 12 From aliphatic alcohols or branched C6-C 18Preferably, the alcohol is selected from aliphatic alcohols. An example of a suitable compound is 2-ethyl-1-hexanol. This type of compound simply serves to occupy one or more isocyanate bond sites to obtain the desired distribution of reaction products from the reaction of polyisocyanate component (i) with compounds (ii) and (iii). One advantage of including this type of compound is that the aliphatic carbon chain adds a degree of fattiness to the adhesive composition. This makes the low molecular weight components of the adhesive more water-soluble, thereby reducing their likelihood of penetrating the skin more easily, further reducing the adhesive's cytotoxicity. In addition, the aliphatic carbon chain acts as a plasticizer in the adhesive, reducing interactions between polymer chains. As a result, the adhesive becomes softer, cheaper, and easier to produce.

[0067] The at least one compound (iii) also allows other functionalities to be incorporated into the adhesive composition without affecting the initial peel strength or switching performance. Molecules with these functionalities would otherwise be incorporated into the adhesive polyurethane composition as small molecules. Therefore, by adding them to the polyurethane network, the adhesive becomes less cytotoxic. For example, the at least one compound (iii) may comprise or consist of one or more hydroxy-substituted photoinitiators.

[0068] Other examples of compounds that can be included in the adhesive composition of the present invention as compound (iii) include biocides and catalysts.

[0069] Typically, at least one compound (iii) contains a single nucleophilic group having an active hydrogen atom, but it is not excluded that at least one compound (iii) may contain two or more nucleophilic functional groups having active hydrogen atoms, in which case compound (iii) may link two polyisocyanate molecules together.

[0070] adhesive composition It will be understood that crosslinking of the polyisocyanate within the polyurethane network can be the result of reaction of a polyisocyanate component containing at least three unreacted isocyanate groups and / or reaction of a polymer component containing at least three nucleophilic functional groups with active hydrogen atoms. To ensure a sufficient level of crosslinking in the polyurethane adhesive composition of the present invention, it is preferred that the sum of X and Y is at least 4.5, preferably at least 5, preferably at least 5.5, preferably at least 6. Preferably, the sum of X and Y is 10 or less, preferably 9 or less, preferably 8 or less.

[0071] The relative amounts of polymer component (A) and crosslinking component (B) can be defined as the molar ratio of free isocyanate groups in crosslinking component (B) to available nucleophilic groups from polymer component (A). A lower molar ratio for a particular degree of substitution results in an adhesive that is more tacky but has less cohesive strength. Thus, one skilled in the art can easily adjust the ratio of crosslinking component (B) to polymer component (A) to obtain an adhesive with the desired balance of adhesive versus cohesive properties.

[0072] For example, the molar ratio of unsubstituted isocyanate functional groups in crosslinking component (B) to nucleophilic groups in polymer component (A) is generally at least 0.3, preferably at least 0.4, preferably at least 0.5. Preferably, the molar ratio of unsubstituted isocyanate functional groups in crosslinking component (B) to nucleophilic groups in polymer component (A) is less than 1, preferably 0.8 or less, preferably 0.7 or less. For example, the molar ratio of unsubstituted isocyanate functional groups in crosslinking component (B) to nucleophilic groups in polymer component (A) may be 0.3 to 0.8, preferably 0.4 to 0.75, preferably 0.5 to 0.7.

[0073] The ratio of unsubstituted isocyanate functional groups in crosslinking component (B) to nucleophilic groups in polymer component (A) is preferably at least 0.8n and not more than the smaller of 1.2n and 0.8, where n represents the total degree of substitution of polyisocyanate component (i). Controlling the ratio within these ranges has been found to provide an optimum balance of adhesive tack and cohesion for different degrees of substitution of polyisocyanate component (i).

[0074] The adhesive polyurethane compositions of the present invention preferably contain from 0.05 to 1 meq / g, preferably from 0.06 to 0.5 meq / g, preferably from 0.08 to 0.4 meq / g, preferably from 0.1 to 0.3 meq / g, preferably from 0.12 to 0.25 meq / g, preferably from 0.15 to 0.2 meq / g of functional groups curable by free radical polymerization.

[0075] Photopolymerization initiator The adhesive polyurethane composition of the present invention 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. The photoinitiator may be mixed into the adhesive composition and / or attached to the polymer chains of the adhesive composition.

[0076] The photoinitiator may be any species capable of generating radical species under mild conditions, such as UV or visible light, to promote free-radical initiated polymerization of the curable functional groups of compound (ii).

[0077] Preferably, the photoinitiator is responsive to UV radiation having 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 200 to 400 nm range is referred to herein as "long wavelength UV."

[0078] Photoinitiators can alternatively generate radical species upon exposure to visible light, but products that are curable by exposure to visible light require careful handling to avoid premature switching of the adhesive and / or require additional visible light blocking materials to be incorporated into the product, which must be removed from the product in a timely manner when switching is desired.

[0079] The UV-sensitive photoinitiator may be selected from any of the conventional photoinitiators known in the art. For example, the UV-sensitive photoinitiator may be suitably selected from the group including benzoin and derivatives (e.g., benzoin ethyl, isopropyl, or isobutyl ether, etc.); 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-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one; 2-ethylanthraquinone; benzil dimethyl ketal; 2-hydroxy-2-methylpropiophenone; and ethyl 4-(dimethylamino)benzoate.

[0080] 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 camphorquinone / tertiary amine. Examples of visible light photoinitiators are phenanthrenequinone, titanocene, and bis(2,4,6-trimethyl-benzoyl)-phenylphosphine oxide.

[0081] The adhesive polyurethane composition preferably contains 0.05 to 5 wt. % photoinitiator, preferably 0.2 to 2 wt. % photoinitiator. These specific photoinitiator ranges allow the curable groups to react with each other after activation, allowing the adhesive to achieve the desired switching time.

[0082] solvent The adhesive polyurethane composition may further comprise a solvent. The solvent must be an aprotic solvent so as not to react with the isocyanate groups of the polyisocyanate component (i). Preferably, the solvent has low toxicity, and preferably, the solvent is non-toxic. An example of a preferred solvent is ethyl acetate.

[0083] stabilizers The switchable adhesive composition may also have a stabilizer. As used herein, the term "stabilizer" refers to a substance added to the adhesive composition to scavenge free radicals to prevent premature reaction of the curable functional groups in the adhesive during manufacturing and / or storage of the adhesive composition. These substances are well known in the field of curable materials and are sometimes referred to as antioxidants.

[0084] Examples of suitable stabilizers include 1-piperidinyloxy-4,4'-[1,10-dioxo-1,10-decanediyl)bis(oxy)]bis[2,2,6,6-tetramethyl] and phenol derivatives such as methoxyphenol, di-tert-butyl-4-methylphenol, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate).

[0085] Optional Components The switchable adhesive composition can also include a photosensitizer. Because the sensitizing species often absorbs energy in a different part of the spectrum than the initiator, more efficient use of the light source may be achieved through the inclusion of a sensitizer in the composition. Many photosensitizers are complex organic molecules that absorb in the long wavelength UV and / or visible parts of the spectrum.

[0086] The adhesive polyurethane composition can also contain scattering particles to improve the irradiation effect of the adhesive mixture by scattering UV or visible light irradiating 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, and have a particle size of 10 nm or more, typically up to 1 μm.

[0087] The adhesive polyurethane composition may also contain a component (second release liner) with an aliphatic thiol group to reduce oxygen inhibition of radical polymerization at the surface and prevent the surface from remaining tacky after curing if the surface is not protected by a film. In addition to possessing oxygen scavenging properties, aliphatic thiols can also participate in the radical polymerization of curable molecules via a thiol-ene reaction. For more effective contribution to the curing reaction, components with two or more thiol groups, such as trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetrakis(2-mercaptoacetate), can be used. Amine synergists, such as triethanolamine, ethyl 4-dimethylaminobenzoate, or acrylated amines, can also be used to reduce oxygen inhibition of radical polymerization at the adhesive surface if the adhesive surface is not protected by a film.

[0088] The reactivity of the composition can be increased by increasing the concentration (meq / g) of curable groups in the adhesive, by using compounds (ii) with two or more curable groups, and / or by using more reactive functionality in the adhesive, for example, by partially or completely replacing methacrylate with acrylate (acrylate is more reactive but also slightly more toxic).

[0089] The intermolecular interactions of the adhesive, and therefore its viscosity, can be reduced by using bulky groups (e.g., by adding methyl groups or branching the molecular chain) and / or by introducing asymmetry or greater hydrophobicity into the crosslinking component (B). This may be achieved by using a polyisocyanate component (i) with bulky groups, for example, by replacing hexamethylene diisocyanate with trimethylhexamethylene diisocyanate, isocyanurate with iminooxadiazinedione, butanediol with methylpentanediol, or polyethylene glycol with polypropylene glycol. Alternatively, this may also be achieved by using at least one compound (iii) in the crosslinking component (B), where at least one compound (iii) contains a bulky group.

[0090] The adhesive polyurethane compositions of the present invention exhibit a reduction in peel force after switching of at least 30%, preferably 50 to 99%, preferably 70 to 99%, when measured according to the method described below.

[0091] According to a first aspect of the present invention, there is further provided an adhesive polyurethane composition according to the following aspects 1-1 to 1-18.

[0092] Aspect 1-1: An adhesive polyurethane composition according to a first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; and (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; Adhesive polyurethane composition.

[0093] Aspect 1-2: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; and (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; Adhesive polyurethane composition.

[0094] Aspects 1-3: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; and (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; Adhesive polyurethane composition.

[0095] Aspects 1-4: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); and (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.05 to 0.5; Adhesive polyurethane composition.

[0096] Aspects 1-5: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); and (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.08 to 0.4; Adhesive polyurethane composition.

[0097] Aspects 1-6: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); and (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.1 to 0.3; Adhesive polyurethane composition.

[0098] Aspects 1-7: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters; Adhesive polyurethane composition.

[0099] Aspects 1-8: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters; Adhesive polyurethane composition.

[0100] Aspects 1-9: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20) alkyl acrylate esters; Adhesive polyurethane composition.

[0101] Aspects 1-10: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.05 to 0.5; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters; and (ix) At least one compound (iii) is a C1-C 30 selected from fatty alcohols; Adhesive polyurethane composition.

[0102] Aspects 1-11: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.08 to 0.4; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters; and (ix) At least one compound (iii) is a C1-C 30 selected from fatty alcohols; Adhesive polyurethane composition.

[0103] Aspects 1-12: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); and (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.1 to 0.3; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) At least one compound (ii) is a hydroxy-substituted -(C-C 20 ) alkyl methacrylate esters and hydroxy-substituted -(C2-C 20 ) alkyl acrylate esters; and (ix) At least one compound (iii) is a C1-C 30 selected from fatty alcohols; Adhesive polyurethane composition.

[0104] Aspects 1-13: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) at least one compound (ii) is selected from hydroxy-substituted (C2-C6) alkyl methacrylate esters; Adhesive polyurethane composition.

[0105] Aspects 1-14: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) at least one compound (ii) is selected from hydroxy-substituted (C2-C6) alkyl methacrylate esters; Adhesive polyurethane composition.

[0106] Aspects 1-15: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; (v) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; and (vi) at least one compound (ii) is selected from hydroxy-substituted (C2-C6) alkyl methacrylate esters; Adhesive polyurethane composition.

[0107] Aspects 1-16: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.2; (ii) Y represents a number ranging from 2 to 4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.3 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.3 to 0.8; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.05 to 0.5; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) at least one compound (ii) is selected from hydroxy-substituted -(C2-C6) alkyl methacrylate esters; and (ix) At least one compound (iii) is a branched C3-C 12 selected from fatty alcohols; Adhesive polyurethane composition.

[0108] Aspects 1-17: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.6; (ii) Y represents a number ranging from 2.1 to 3.5; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.4 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.4 to 0.75; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.08 to 0.4; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) at least one compound (ii) is selected from hydroxy-substituted -(C2-C6) alkyl methacrylate esters; and (ix) At least one compound (iii) is a branched C3-C 12 selected from fatty alcohols; Adhesive polyurethane composition.

[0109] Aspects 1-18: An adhesive polyurethane composition according to the first aspect of the present invention, comprising: (i) X represents a number having a value of at least 2.8; (ii) Y represents a number ranging from 2.2 to 3.4; and (iii) the total degree of substitution of the polyisocyanate component (i) is at least 0.5 and not more than the lesser of 0.28Y and 0.75; (iv) the molar ratio of unsubstituted isocyanate functional groups in the crosslinking component (B) to nucleophilic groups in the polymer component (A) is from 0.5 to 0.7; (v) the crosslinking component (B) is obtained by reacting the polyisocyanate component (i) with both the compound (ii) and the compound (iii); and (vi) the degree of substitution of polyisocyanate component (i) with compound (ii) is from 0.1 to 0.3; (vii) polymer component (A) is selected from hydroxy-terminated polyethers and hydroxy-terminated polyesters having a weight average molecular weight in the range of 1,000 to 20,000 daltons; (viii) at least one compound (ii) is selected from hydroxy-substituted -(C2-C6) alkyl methacrylate esters; and (ix) At least one compound (iii) is a branched C3-C 12 selected from fatty alcohols; Adhesive polyurethane composition.

[0110] Any preferred / optional feature disclosed herein with respect to a first aspect of the invention that falls within the scope of aspects 1-1 to 1-18 above will be understood to be a preferred / optional feature of aspects 1-1 to 1-18. Similarly, any features of dependent claims that fall within the scope of aspects 1-1 to 1-18 above will be interpreted as if those claims also recited aspects 1-1 to 1-18.

[0111] Method for preparing an adhesive polyurethane composition According to a second aspect of the present invention, there is provided a method for preparing an adhesive polyurethane composition, the method comprising: (a) To form the cross-linking component (B), (i) a polyisocyanate component having an average of at least Y isocyanate functional groups per molecule, where Y represents a number ranging from 1.8 to 6; (ii) at least one compound containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom; and, optionally, (ii) at least one compound containing a nucleophilic functional group having an active hydrogen atom and no functional group curable by free radical polymerization; wherein the total degree of substitution of polyisocyanate component (i) with compounds (ii) and (iii) is at least 0.2 and not more than the smaller of 0.3Y and 0.8; (b) a second step of combining the product of step (a) with a polymer component having a weight average molecular weight in the range of 500 to 100,000 daltons and having an average of X nucleophilic functional groups with active hydrogen atoms per molecule, where X represents a number greater than 2; Includes:

[0112] The method of the second aspect of the invention can be used to produce the adhesive polyurethane composition of the first aspect of the invention. Accordingly, any feature described as optional or preferred in connection with the first aspect of the invention should be understood to also constitute an optional or preferred feature with respect to the identities, amounts, and proportions of the corresponding components used in the method of the second aspect of the invention. For example, the method of the second aspect of the invention can be used to produce the adhesive polyurethane composition of any of aspects 1-1 to 1-18 above.

[0113] Step (a) and / or step (b) of the method for preparing the pressure-sensitive adhesive polyurethane composition may be carried out in the presence of a catalyst. Suitable catalysts include dibutyltin dilaurate, zirconium(IV) acetylacetonate, dibutyltin 2-ethylhexanoate, and tertiary amines.

[0114] 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.

[0115] Preferably, a photoinitiator is combined with the product of step (a) or with the polymeric components prior to step (b). Most preferably, a photoinitiator is combined with the polymeric components prior to step (b).

[0116] Adhesive Medical Products According to a third aspect of the present invention there is provided an adhesive medical product comprising a layer of the switchable adhesive polyurethane composition as defined herein disposed between a first carrier film and a release liner.

[0117] The adhesive medical product may include a product selected from the group including adhesive dressings including absorbent wound pads, surgical incise drapes, bacterial barriers for covering wounds, and skin closure devices for closing wound edges together. Suitably, the first carrier film of the medical product may be translucent to UV and / or visible light. Optionally, a removable light occlusive layer is laminated to the first carrier film on the surface opposite the adhesive composition.

[0118] Exemplary materials for the carrier film to carry the switchable adhesive composition layer include polyethylene, polypropylene, polyurethane, ethylene / propylene copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, silicone elastomer, polydimethylsiloxane, neoprene rubber, polyisobutylene, polyacrylate, chlorinated polyethylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, crosslinked polymethacrylate polymer (hydrogel), polyvinylidene chloride, poly(ethylene terephthalate), butyl rubber, epichlorohydrin rubber, ethylene vinyl alcohol copolymer, ethylene vinyl acetate ... Examples of suitable polymeric materials include polyethylene-vinyloxyethanol copolymers; silicone copolymers such as polysiloxane-polycarbonate copolymers, polysiloxane-polyethylene oxide copolymers, polysiloxane-polymethacrylate copolymers, polysiloxane-alkylene copolymers (e.g., polysiloxane-ethylene copolymers), and polysiloxane-alkylenesilane copolymers (e.g., polysiloxane-ethylenesilane copolymers); cellulose polymers such as methyl or ethyl cellulose, hydroxypropyl methylcellulose, and cellulose esters; polycarbonates; and polytetrafluoroethylene. More preferred are medical polyether or polyester polyurethanes, thermoplastic polyester elastomers, perforated polyethylene, polypropylene, and PET films, as well as medical woven or nonwoven fabric materials.

[0119] Adhesive wound dressings typically consist of an absorbent pad for absorbing exudate from a covered wound, surrounded by an adhesive area for securing the wound pad in place on the wound. The adhesive area and wound pad are supported on a carrier film that is often flesh-colored or may have an attractive design on its visible surface. The switchable adhesive composition according to the present invention is an ideal candidate for use as the adhesive in the adhesive area around the wound pad of an adhesive wound dressing.

[0120] Adhesive wound dressings are often applied at home by general users, not necessarily by medical professionals. Because few homes have access to suitable UV irradiation equipment, home adhesive wound dressings preferably contain an adhesive that can be cured by visible light. In some cases, adhesive wound dressings preferably contain an adhesive that can be cured by UV light, so that the timing of dressing removal is controlled by medical professionals. If the adhesive is curable by UV light, a removable light-blocking layer may not be necessary.

[0121] Adhesive wound dressings intended for home use will preferably include a light-shielding layer to prevent premature switching of the switchable adhesive composition. A first light-shielding layer is placed on the carrier film on the side opposite the adhesive and remains in place until the user desires to remove the adhesive wound dressing. At this point, the first light-shielding layer is removed, and the underlying switchable adhesive composition is exposed to visible light, resulting in the adhesive composition switching from an adhesive state to a non-adhesive or low-adhesive state. Optionally, a second light-shielding layer may form part of a release liner placed on the adhesive side of the dressing. This second light-shielding layer is removed just before the adhesive wound dressing is applied to the wound. If the adhesive wound dressing is provided in a light-tight package, the second light-shielding layer may not be necessary.

[0122] If the adhesive wound dressing contains an adhesive that can be cured by UV light, no light-shielding layer is required. Instead, the carrier film of the adhesive wound dressing only needs to be translucent to UV light. When it is desired to remove the adhesive wound dressing, a trained medical professional shines the light of an appropriate UV light source on the adhesive wound dressing to initiate the curing reaction. Within a few seconds, the adhesive loses its stickiness, and the wound dressing can be easily removed.

[0123] The release liner may be selected from any coated material with low surface energy to allow it to be easily removed from the adhesive layer. Suitable release liners include paper and plastic films provided with a silicone coating on the surface that contacts the adhesive composition.

[0124] According to a fourth aspect of the present invention, there is provided a method of treating a wound using a switchable adhesive dressing described herein, the method comprising the steps of removing the release liner and applying the dressing to a wound site.

[0125] The invention will now be further described, by way of example only and not by way of limitation, with reference to the drawings in which: [Brief explanation of the drawings]

[0126] [Figure 1] 1 is a cross-sectional view through an adhesive dressing according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view showing an attempt to remove an adhesive dressing from a patient's forearm according to a first embodiment of the present invention, including an enlarged callout in partial cross section showing how removal of the adhesive dressing causes the adhesive composition to protrude. [Figure 3] 1 is a perspective view of an adhesive dressing according to a first embodiment of the present invention undergoing irradiation to effect adhesive switching. FIG. [Figure 4]FIG. 1 is a perspective view illustrating how an adhesive dressing according to a first embodiment of the present invention can be easily removed after switching adhesives. [Figure 5] FIG. 1 is a graph showing peel force measurements for Examples 7 to 11. DETAILED DESCRIPTION OF THE INVENTION

[0127] An adhesive medical product using the switchable adhesive composition of the present invention will now be described with reference to Figures 1 to 4. The adhesive medical product in this example is an adhesive medical dressing.

[0128] 1 is a cross-sectional view through an adhesive medical dressing 100 attached to a patient's skin 20. The adhesive medical dressing 100 is a multi-layer product having the following structure: The dressing 100 comprises a wound-facing absorbent layer 130 disposed beneath a protective backing layer 140. At both ends 150, the backing layer 140 is provided with a switchable adhesive composition 170 comprising curable molecules that can crosslink under the influence of UV and / or visible light.

[0129] The backing layer 140 is optionally provided with a light-blocking cover layer 180 that is releasably secured to the backing layer 140 by a weak adhesive 190. To facilitate removal, the light-blocking cover layer 180 overhangs the backing layer 140 at its ends 110. If the switchable adhesive composition 170 has a photoinitiator that is activated by UV radiation, the light-blocking cover layer 180 may be omitted.

[0130] 2 is a perspective view illustrating an attempt to remove adhesive dressing 100 from a patient's forearm 14 prior to switching the switchable adhesive composition. Prior to switching, adhesive composition 171 is very tacky, fairly firmly adhering adhesive dressing 100 to the patient's skin 20. Thus, when the patient attempts to remove dressing 100 from forearm 14, dressing 100 remains adhered to skin 20 unless dressing 100 is removed with some force.

[0131] 3 is a perspective view showing an adhesive dressing being irradiated, in this example from a lamp 60, to cause curing of the curable molecules in the adhesive composition 170. The light from the lamp 60 (UV light or visible light, preferably long wavelength UV) causes a photoinitiator in the adhesive composition 170 to generate free radicals, which initiate curing of the curable molecules in the adhesive composition. Curing converts (switches) the adhesive composition 170 from its tacky state to a non-tacky or low-tacky state.

[0132] FIG. 4 is a perspective view illustrating how the patient can easily remove the adhesive dressing 100 from the forearm 14 after switching adhesive compositions without requiring excessive force.

[0133] Example Examples 1-5 Crosslinking Component (B) The reaction was carried out at room temperature with stirring. The components shown below in Table 1, except for the catalyst, were added to a reagent bottle and mixed to form a homogeneous solution, after which the catalyst was added. The mixture was left overnight to complete the reaction.

[0134] After verifying by GPC that no unreacted hydroxypropyl methacrylate or 2-ethyl-1-hexanol remained, the isocyanate-functional acrylate oligomer was ready for use.

[0135] GPC was performed by diluting the sample with tetrahydrofuran in a ratio of 1:100 and injecting a volume of 20 μl into the injection valve of a Waters HPLC 1515 pump using tetrahydrofuran at a flow rate of 1 ml / min. The instrument was equipped with a Styragel HR1 column connected to a Waters 2414 refractive index detector.

[0136] The ingredients shown in Table 1 are as follows:

[0137] A Polyisocyanate Component (i) B Solvent C catalyst D. Stabilizer E Compound (ii) F Compound (iii)

[0138] [Table 1] Example 6 - Preparation of polymer component (A) Under protection from UV light sources, all ingredients in Table 2, except for Baymedix AR602, were placed in a sealable glass jar and mixed using a magnetic stirrer until all solid materials were dissolved. Baymedix AR602 was then added and the mixture was stirred until homogeneous.

[0139] The ingredients shown in Table 2 are as follows:

[0140] H Polyol I. Photopolymerization initiator B Solvent C catalyst D. Stabilizer to prevent premature conversion during storage J Surfactants

[0141] [Table 2] Examples 7 to 11 - Switchable Adhesive Compositions Examples 7 to 11 are examples of switchable adhesive compositions according to the present invention that were assembled to include a composition comprising crosslinking component (B) from Examples 1 to 5 and a composition comprising polymer component (A) from Example 6 in the amounts shown in Table 3.

[0142] Both components in Examples 7 to 11 were placed in a sealable glass jar and mixed to a uniform solution using a magnetic stirrer for approximately 10 minutes under protection from UV light. The resulting adhesive solution was then spread onto a flexible medical polyurethane film with a removable carrier film (Medical Film 48938) using a spreader with a 150 μm gauge. The adhesive coating was then cured in a fan-assisted oven at 130°C for 10 minutes. After this step, the adhesive coating had a thickness of approximately 60-80 μm.

[0143] [Table 3] Peel force measurement The peel force before and after switching was determined for each of the adhesives in Examples 7 through 11. 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 high-adhesion PET tape. The PET film was secured to the medical film to negate the elastic effect of the medical film on the measured peel force.

[0144] Peel strength was determined after a 20-minute dwell time using an Instron 5943 test apparatus equipped with a 100 N load cell according to FINAT test method FTM1, except that a high-density polyethylene (HDPE) panel was used as the substrate surface, and a peel rate of 100 mm / min and a crosshead speed of 200 mm / s were used to collect all of the necessary data within the time frame of a single peel force measurement.

[0145] Adhesive switching was achieved by exposing the adhesive (bonded to an HDPE plate) through PET tape and a medical film backing to light at approximately 5 mW / cm² intensity from a XeLED-Ni3UV-R4-365-E27-SS lamp with a narrow spectrum around 365 nm. Switching times for different coatings were measured as the time from the start of irradiation to the occurrence of essentially instantaneous adhesion loss during a continuous peel strength test of approximately 1.5 minutes (i.e., the adhesive was peeled for a period of time while irradiated). Peel force measurements continued under irradiation until the peel force reached a plateau value, which typically occurred 5–10 seconds after the switching time. Peel strength and switching time were measured four times, and the average values ​​of switching time and peel strength (before and after switching) are reported in Table 4.

[0146] The peel force measurements are shown in Table 4 along with the meq curing group (i.e., the olefin portion of the methacrylate ester). The meq of curing group is easily calculated from the mmol of hydroxypropyl methacrylate added to the adhesive and the total dry weight of the adhesive (i.e., excluding solvent).

[0147] [Table 4] Table 4 shows that in all cases, a peel force reduction of 80% or more was achieved. As expected, the peel force after switching was highest for the adhesive of Example 11, which had the lowest content of curable methacrylate moieties. However, even at relatively low curable group contents, the peel force reduction was significant. When the methacrylate content of the adhesive exceeded about 0.05 meq / g, the peel force reduction easily exceeded 90%. Comparison of Examples 7 and 8 shows that when the curable group content exceeded about 0.1 meq / g, the switched peel force was substantial. This demonstrates that an excessive amount of curable groups is not essential for good switching performance. This offers the possibility of replacing some of the curable groups with non-curable groups from compound (iii) without impairing (or even improving) the adhesive's performance. In Examples 7 and 8, the peel force reduction approached 99%, demonstrating that the switched adhesive could be removed from the substrate essentially without damage to the substrate (and even without pain when removing the switched adhesive from skin). The results of the peel force measurements are shown graphically in FIG.

[0148] Examples 12 to 17 - Crosslinking components with different degrees of isocyanate substitution Compositions containing crosslinking component (B) with different degrees of substitution of polyisocyanate component (i) were prepared according to the procedure set forth in Example 1, using the amounts of the different components set forth in Table 5. Optional component (iii) is not used in Examples 12 to 17.

[0149] [Table 5] Examples 18 to 31 - Switchable Adhesive Compositions Examples 18 to 31 are examples of switchable adhesive compositions according to the present invention that were assembled to include a composition comprising crosslinking component (B) from Examples 12 to 17 and a composition comprising polymer component (A) from Example 6 in the amounts shown in Table 6. The adhesives were assembled according to the method of Example 7, except that a 200 μm gauge was used to spread the adhesive on the film, and the adhesive was applied at a rate of 90 to 100 g / m. 2 The resulting adhesive coating had a coat weight of 0.015. Peel forces were measured as above on four samples per adhesive and are reported in Table 6. The measured values ​​represent adhesive failure. No cohesive failure was observed in these tests. In other words, the maximum measured peel force represents the force required to separate the adhesive from the substrate, and does not represent internal failure of the adhesive structure (leaving a residue on the surface).

[0150] It will be appreciated that as the degree of substitution of the polyisocyanate component increases, the relative amount of crosslinking component (B) will need to increase to ensure that sufficient unreacted isocyanate groups are available to react with polymer component (A).

[0151] [Table 6] As shown in Table 6, the degree to which the isocyanate functional groups of crosslinking component (B) are substituted with either curable groups (such as acrylates / methacrylates) or non-curable groups affects the adhesive properties of the adhesive composition. While it might be expected that crosslinking component (B) could be made simply by removing the non-curable moieties (from compound (iii)) with a sufficient amount of unsaturation, it has been found that when crosslinking component (B) has only a low degree of substitution, the resulting composition has poor adhesion. The distribution and density of crosslinks within the resulting polymer matrix, and therefore the adhesive properties, can be tailored for polyol-isocyanate oligomer pairs or mixtures thereof by replacing a portion of isocyanate component (i) with non-curable compound (iii). Therefore, the minimum degree of substitution of polyisocyanate component (i) is at least 0.2, and preferably at least 0.3, more preferably at least 0.4, and most preferably at least 0.45 or at least 0.5.

[0152] On the other hand, although a crosslinking component (B) having a very high level of isocyanate substitution can be used to form a strong adhesive, the amount of crosslinking component (B) required to form sufficient crosslinks with the polymer component (A) is so large that it is not cost-effective. For example, the degree of substitution of the maximum polyisocyanate component (i) is not more than the smaller of 0.3Y and 0.8, for example, not more than the smaller of 0.28Y and 0.75.

[0153] Example 32 - Pumping of a composition containing cross-linking component (B) The ratio of polymer component (A) to crosslinking component (B) determines the adhesive's tackiness, and at the same time, small variations in the ratio can have a significant impact on adhesive performance. Therefore, one of the best ways to maintain a stable ratio while coating the adhesive is to use a gear pump (gear metering pump). In the following examples, a 2K GMM e2 mixer from Scanrex Industriservice AB was equipped with a GM301D-30R-110Z 3.0 cc pump and a GM601D-30R-110Z 6.0 cc pump from Oerlikon Barmag for the crosslinking component and polymer component, respectively.

[0154] In a production run, 20 kg of a composition containing the crosslinking component (B) from Example 1 (approximately 65% ​​isocyanate substitution by curable groups) and 40 kg of a composition containing the polymer component (A) from Example 6 were prepared and placed in their respective containers. The mixer was set to the total flow rate indicated in Table 7 below. The mixing process was then initiated and continued under intermittent conditions until the 3.0 cc pump for the crosslinking component (B) stopped due to excessive torque. When the crosslinking component pump head was disassembled, a white, rubbery material was noticed on the gears as well as the surrounding pump house. It is believed that this was the cause of the pump clogging, as it is well known that high shear forces can initiate polymerization.

[0155] In a second trial, 5 kg of the composition containing the crosslinking component prepared according to Example 2 (approximately 19% substitution of isocyanate by curable groups) was charged into its corresponding vessel, where, after the recirculation device was in place, the crosslinking component pump (with the polymer component pump disconnected) was started at a flow rate of 2.5 ml / s. After pumping 970 liters through the system without any pump failure, no visible material could be detected in the pump head after decomposition, clearly demonstrating that polymerization in the pump head can be avoided by keeping the amount of curable moieties below a certain concentration while maintaining the total degree of substitution of polyisocyanate component (i) with compound (iii).

[0156] [Table 7] Example 33 - Adhesive containing a photoinitiator as compound (iii) A composition comprising a crosslinking component (B) containing a photoinitiator as compound (iii) was prepared by the method of Example 1 using the components listed in Table 8.

[0157] [Table 8] A composition containing polymer component (A) was prepared by the method of Example 6 using the ingredients set forth in Table 9.

[0158] [Table 9] Following the method of Example 7, an adhesive composition was prepared by combining 33.9 g of polymer component (A) and 9.94 g of crosslinking component (B). The NCO / OH ratio of this adhesive was 0.465. This adhesive provided an initial peel force of 1.45 N / 25 mm on HDPE, a post-switch peel force of 0.10 N / 25 mm, and a switching time of 9.6 seconds. A particular advantage of the adhesive of Example 33 is that the potentially hazardous photoinitiator becomes chemically bound to the adhesive polymer matrix so that it cannot be absorbed by the skin.

[0159] Example 34 - Adhesive containing a photoinitiator as compound (iii) A composition comprising a crosslinking component (B) containing a photoinitiator as compound (iii) was prepared by the method of Example 1 using the components listed in Table 10.

[0160] [Table 10] A composition containing polymer component (A) was prepared by the method of Example 6 using the ingredients set out in Table 11.

[0161] [Table 11] Following the method of Example 7, an adhesive composition was prepared by combining 20.05 g of a composition containing polymer component (A) with 7.82 g of a composition containing crosslinking component (B). The NCO / OH ratio of this adhesive was 0.841. This adhesive provided an initial peel force of 2.9 N / 25 mm on HDPE, a post-switch peel force of 0.08 N / 25 mm, and a switching time of 5.5 seconds. A particular advantage of the adhesive of Example 34 is that, again, the potentially hazardous photoinitiator becomes chemically bound to the adhesive polymer matrix so that it cannot be absorbed by the skin.

[0162] Examples 35 to 38 - Cytotoxicity of Adhesives A composition containing cross-linking component (B) was prepared by the method of Example 1 using the components set out in Table 12 (Example 35).

[0163] [Table 12] A composition containing polymer component (A) was prepared by the method of Example 6 using the ingredients set out in Table 13 (Example 36).

[0164] [Table 13] Adhesives were assembled according to the method of Example 7 using compositions containing polymer component (A) and crosslinking component (B) in the ratios set forth in Table 14.

[0165] [Table 14] The cytotoxicity of Examples 37 and 38 (measured according to a cytotoxicity test in accordance with the method described in the ISO 10993-5 "Biological Evaluation of Medical Devices" guideline) is presented in Table 15. The adhesive composition extract was diluted to determine whether lower concentration examples would exhibit better cytotoxicity. In Table 15, the dilution factor indicates the extent to which the extract was diluted before conducting the cytotoxicity test. The extract:medium ratio is tabulated. It should be noted that a sample is considered to have passed the test only if the undiluted (1:0) sample exhibited a viability of greater than 70%.

[0166] [Table 15] As can be seen in Table 15, the sample from Example 38 passed the cytotoxicity test, while the sample from Example 37 failed the cytotoxicity test despite the absence of photoinitiator and nearly half the catalyst concentration, both of which would be expected to exert some toxicity to living cells. This demonstrates that reducing the concentration of curable moieties in the adhesive has a beneficial effect on the adhesive's cytotoxicity without compromising the adhesive's switching properties.

[0167] In situations where the medical skin covering will be in prolonged contact with the patient's skin, or where the medical skin covering will be replaced with a new medical skin covering several times over an extended period of time, it is particularly important that the switchable adhesive composition used in the medical skin covering be of low cytotoxicity.

[0168] Example 39 A composition containing cross-linking component (B) was prepared by the method of Example 1 using the components set out in Table 16.

[0169] [Table 16] Example 40 Adhesives were assembled according to the method of Example 7 using a composition including the polymer component (A) of Example 6 and a composition including the crosslinking component (B) of Example 39 in the proportions presented in Table 17.

[0170] [Table 17] This adhesive provided an initial peel force of 3.38 N / 25 mm on HDPE, a post-switch peel force of 0.03 N / 25 mm, and a switching time of 1.8 seconds. An advantage of the adhesive produced in combination with a crosslinking component (B) similar to that in Example 39 is that a significantly smaller amount of the isocyanate component is required. This is more cost-effective since the isocyanate component is expensive compared to the polymer component (A).

[0171] material In the above examples, the following materials were used:

[0172] [Table 18] TIFF0007810434000020.tif114146

Claims

1. (A) a polymer component having a weight average molecular weight in the range of 500 to 100,000 daltons and having an average of X nucleophilic functional groups having active hydrogen atoms per molecule, where X represents a number having a value of at least 2; (B) (i) a polyisocyanate component having an average of at least Y isocyanate functional groups per molecule, where Y represents a number in the range of 1.8 to 6; (ii) at least one compound containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom; and (iii) at least one compound containing a nucleophilic functional group having an active hydrogen atom and no functional group curable by free radical polymerization; wherein the total degree of substitution of the polyisocyanate component (i) with the compounds (ii) and (iii) is at least 0.2 and not more than the smaller value of 0.3Y or 0.8; 1. An adhesive polyurethane composition comprising the reaction product of:

2. 2. The adhesive polyurethane composition of claim 1, wherein the total degree of substitution of said polyisocyanate component (i) with said compounds (ii) and (iii) is not greater than the smaller of 0.28Y and 0.

8.

3. 3. The adhesive polyurethane composition of claim 1, wherein the total degree of substitution of the polyisocyanate component (i) with the compounds (ii) and (iii) is at least 0.

3.

4. 4. The adhesive polyurethane composition of claim 1, wherein the degree of substitution of said polyisocyanate component (i) with said compound (ii) is 0.6 or less.

5. 5. The adhesive polyurethane composition of claim 1, wherein the degree of substitution of said polyisocyanate component (i) with said compound (ii) is at least 0.

05.

6. 6. The adhesive polyurethane composition of claim 1, wherein Y represents a number ranging from 2 to 4.

7. 7. The adhesive polyurethane composition of claim 1, wherein the polyisocyanate component (i) comprises one or more polyisocyanate compounds selected from the group of polyisocyanates having from 2 to 10 isocyanate functional groups per molecule.

8. 8. The adhesive polyurethane composition of claim 7, wherein said polyisocyanate component (i) comprises a mixture of a diisocyanate and at least one polyisocyanate having an average of at least 3 isocyanate functional groups per molecule.

9. The polyisocyanate component (i) has the formula D(R-NCO) ３ wherein D represents a ring structure selected from isocyanurates, iminooxadiazinedione, and mixtures thereof; and each R independently represents a linear, branched, or cyclic alkylene group having from 2 to 15 carbon atoms, or an aryl group having from 6 to 20 carbon atoms.

10. 10. The adhesive polyurethane composition of claim 1, wherein said at least one compound (ii) comprises an olefinic moiety as a functional group curable by free radical polymerization.

11. the at least one compound (ii) is selected from hydroxy-substituted acrylate esters, hydroxy-substituted methacrylate esters, and mixtures thereof; The at least one compound (ii) is hydroxy-(C ２ -C ２０ ) alkyl-substituted methacrylate esters, polyalkoxylated monomethacrylates having 2 to 10 ether functional groups, and mixtures thereof; or The adhesive polyurethane composition of claim 10, wherein said compound (ii) is selected from 2-hydroxypropyl methacrylate, hydroxyethyl methacrylate, and mixtures thereof.

12. The at least one compound (iii) is One or more C １ -C ３０ fatty alcohols; Linear, branched, or cyclic C １ -C １８ fatty alcohols; Linear, branched, or cyclic C １ -C １２ a fatty alcohol; or Branched C ３ -C １２ Aliphatic alcohol or branched C ６ -C １８ fatty alcohols; 12. The adhesive polyurethane composition of any one of claims 1 to 11, comprising or consisting of:

13. 13. The adhesive polyurethane composition of any one of claims 1 to 12, wherein said at least one compound (iii) comprises or consists of one or more hydroxy-substituted photoinitiators.

14. 14. The adhesive polyurethane composition of claim 1, wherein X represents a number of at least 2.

2.

15. 15. The adhesive polyurethane composition of claim 1, wherein the polymer component (A) is selected from hydroxy-terminated polyethers, hydroxy-terminated polyesters, amine-terminated polyethers, and amine-terminated polyesters.

16. 16. The adhesive polyurethane composition of claim 15, wherein said hydroxy-terminated polyether is selected from alkoxylated derivatives of compounds containing from 2 to 5 hydroxy groups, or mixtures thereof.

17. 17. The adhesive polyurethane composition of claim 16, wherein the hydroxy-terminated polyethers include alkoxylated derivatives of ethylene glycol, propylene glycol, butane-1,4-diol, glycerol, trimethylolpropane, erythritol, pentaerythritol, pentane-1,2,4,5-tetrol, dextrose, and sorbitol.

18. 18. The adhesive polyurethane composition of claim 17, wherein said hydroxy-terminated polyether is a propoxylated derivative of ethylene oxide-capped pentaerythritol.

19. 19. The adhesive polyurethane composition of any one of claims 1 to 18, wherein the polymer component has a weight average molecular weight in the range of 1,000 to 50,000 Daltons.

20. 20. The adhesive polyurethane composition of any one of claims 1 to 19, wherein the polymer component has an equivalent weight per nucleophilic functional group of from 200 to 5,000.

21. 21. The adhesive polyurethane composition of claim 1, wherein the polymer component has a monol content of 2 mol% or less.

22. 22. The adhesive polyurethane composition of any one of claims 1 to 21, wherein the sum of X and Y is at least 4.

5.

23. 23. The adhesive polyurethane composition of any one of claims 1 to 22, wherein the molar ratio of unsubstituted isocyanate functional groups in said crosslinking component (B) to nucleophilic groups in said polymer component (A) is from 0.3 to 0.

8.

24. 24. The adhesive polyurethane composition of claim 1, wherein the ratio of unsubstituted isocyanate functional groups in said crosslinking component (B) to nucleophilic groups in said polymer component (A) is at least 0.8n and not more than the smaller of 1.2n and 0.8, where n represents the total degree of substitution of said polyisocyanate component (i).

25. 25. The adhesive polyurethane composition of any one of claims 1 to 24, comprising 0.05 to 1 meq / g of functional groups curable by free radical polymerization.

26. 26. The adhesive polyurethane composition of any one of claims 1 to 25, further comprising 0.05 to 5 wt% of a photoinitiator.

27. 27. The adhesive polyurethane composition of claim 26, wherein said photoinitiator is reactive to UV light.

28. 28. The adhesive polyurethane composition of claim 27, wherein the photoinitiator is selected from the group comprising 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, 2-hydroxy-2-methylpropiophenone, and ethyl 4-(dimethylamino)benzoate.

29. 29. The adhesive polyurethane composition of any one of claims 1 to 28, further comprising a solvent.

30. 30. The adhesive polyurethane composition of any one of claims 1 to 29, further comprising a stabilizer.

31. 31. An adhesive polyurethane composition according to any one of claims 1 to 30, wherein the peel force reduction of the adhesive after switching is between 30 and 99%, and switching changes the adhesive polyurethane composition from a tacky state to a non-tacky state by initiating curing of the curable portions.

32. (a) To form the cross-linking component (B), (i) a polyisocyanate component having an average of at least Y isocyanate functional groups per molecule, where Y represents a number in the range of 1.8 to 6; (ii) at least one compound containing a functional group curable by free radical polymerization and further containing a nucleophilic functional group having an active hydrogen atom; (iii) at least one compound containing a nucleophilic functional group having an active hydrogen atom and no functional group curable by free radical polymerization; wherein the total degree of substitution of the polyisocyanate with the compounds (ii) and (iii) is at least 0.2 and not more than the smaller of 0.3Y and 0.8; (b) a second step of combining the product of step (i) with a polymer component (A) having a weight average molecular weight in the range of 500 to 100,000 Daltons and having an average of X nucleophilic functional groups with active hydrogen atoms per molecule, where X represents a number greater than 2; 1. A method for preparing an adhesive polyurethane composition, comprising:

33. 33. The method of claim 32, wherein step (a) and / or step (b) is carried out in the presence of a catalyst.

34. 34. The method of claim 32 or claim 33, wherein step (a) and / or step (b) is carried out in the presence of a solvent.

35. 35. The method of any one of claims 32 to 34, wherein the adhesive polyurethane composition is an adhesive polyurethane composition according to any one of claims 1 to 31.

36. 32. An adhesive medical product comprising the switchable adhesive polyurethane composition of any one of claims 1 to 31 disposed between a first carrier film and a release liner, wherein switching changes the adhesive polyurethane composition from a tacky state to a non-tacky state by initiating curing of a curable portion.

37. 37. The adhesive medical product of claim 36, wherein the first carrier film is UV translucent and optionally has a removable UV blocking layer laminated to the first carrier film on the surface opposite the adhesive polyurethane composition.

38. 38. A method of treating a wound using the adhesive dressing of claim 37, comprising removing the release liner and applying the adhesive dressing to the site of the wound.

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