Medical adhesive articles having low effective elastic modulus

Abstract

The medical adhesive article comprises a layer of adhesive and a modified substrate layer, the layer having a plurality of discontinuities arranged in a pattern that can be random, or the pattern can be arranged along at least one axis. The discontinuities are gaps that are not visible to the naked eye when the adhesive article is in an unstressed state, and at least some of the discontinuities become gaps visible to the naked eye and form openings when the adhesive article is in a stressed state. The adhesive article can be used to adhere a medical device to the skin.

Description

[Technical Field]

[0001] SUMMARY The present disclosure relates to medical adhesive articles suitable for extended wear that have a low effective modulus of elasticity. [Background technology]

[0002] A wide range of adhesive articles are used in medical applications, including gels used to attach electrodes and other sensing devices to a patient's skin, a wide range of tapes for attaching medical devices to a patient, and adhesive dressings used to cover and protect wounds.

[0003] Many adhesive articles use pressure-sensitive adhesives. Pressure-sensitive adhesives are well known to those skilled in the art to have certain properties at room temperature, including (1) strong and persistent adhesion, (2) adhesion with finger pressure or less, (3) sufficient ability to hold onto the substrate, and (4) sufficient cohesion to remove cleanly from the substrate. Materials known to perform well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelastic properties necessary to provide the desired balance of adhesion, peel adhesion, and shear strength.

[0004] The polymers most commonly used in preparing pressure-sensitive adhesives are natural rubber, synthetic rubber (e.g., styrene / butadiene copolymer (SBR) and styrene / isoprene / styrene (SIS) block copolymers), various (meth)acrylate (e.g., acrylate and methacrylate) copolymers, and silicones. Summary of the Invention

[0005] The present disclosure relates to medical adhesive articles that have a low effective modulus of elasticity and are suitable for extended wear, as well as methods for preparing these medical adhesive articles. Medical structures prepared using the medical adhesive articles are also disclosed.

[0006] In some embodiments, a medical adhesive article comprises a continuous layer of adhesive having a first major surface and a second major surface, and a substrate layer having a first major surface and a second major surface, the first major surface of the substrate layer being in contact with the second major surface of the adhesive layer. The substrate layer comprises a plurality of cuts, the plurality of cuts being arranged in a pattern. The pattern may be random or may be arranged along at least one axis. The cuts are gaps, but when the adhesive article is in an unstressed state, the gaps are not visible to the naked eye, and when the adhesive article is in a stressed state, at least some of the cuts become gaps visible to the naked eye.

[0007] Also disclosed are methods for preparing these adhesive articles. In some embodiments, the method includes providing a substrate layer having a first major surface and a second major surface, modifying the substrate layer by making a plurality of cuts in the substrate layer without removing material from the substrate layer, such that in an unstressed state the cuts are gaps that are not visible to the naked eye, but in a stressed state at least some of the gaps become visible to the naked eye, providing an adhesive, and forming a continuous layer of adhesive on the first major surface of the substrate layer. In some embodiments, the adhesive layer is formed on the substrate layer before modifying the substrate layer.

[0008] Also disclosed is a medical structure. In some embodiments, the medical structure includes a surface comprising mammalian skin and an adhesive article attached to the mammalian skin-comprising surface, the adhesive article being as described above. The adhesive article may further include a medical device. [Brief explanation of the drawings]

[0009] The present application may be more fully understood from consideration of the following detailed description of various embodiments of the disclosure in conjunction with the accompanying drawings. [Figure 1A] 1 shows top-view photographs of an article according to an embodiment of the present disclosure in an unstressed state and in two stressed states, as described in Example 1. [Figure 1B] 1 shows top-view photographs of an article that is comparative to the present disclosure in an unstressed state and in two stressed states, as described in Comparative Example C1. [Figure 1C] 1 shows top-view photographs of an article that is comparative to the present disclosure in an unstressed state and in two stressed states, as described in Comparative Example C2. [Figure 2A] 1A shows histogram data for the article of FIG. 1A, as described in Example 1. [Figure 2B] 1B shows histogram data for the article of FIG. 1B as described in Comparative Example C1. [Figure 2C] 1C, as described in Comparative Example C2.

[0010] In the following description of exemplary embodiments, reference is made to the accompanying drawings, which show, by way of illustration, various embodiments in which the present disclosure may be practiced. It is to be understood that embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure. The drawings are not necessarily to scale. Like numbers used in the drawings indicate like components. However, it will be understood that the use of a number to indicate a component in a given figure is not intended to limit the component in another figure indicated by the same number. DETAILED DESCRIPTION OF THE INVENTION

[0011] The use of adhesive products in the medical industry has been widespread and increasing for many years. However, while adhesives and adhesive articles have proven themselves very useful in medical applications, their use also presents problems. While many medical adhesive articles are applied directly to the wound area, a wide range of medical articles, such as tapes and drapes, are not applied to the wound area itself, but rather serve as absorbent materials or support for treatments, such as holding medical devices in place on the skin. Examples of medical devices that are held in place using tape include tubes, catheters, ostomy appliances, and sensors.

[0012] Medical adhesives have a wide range of desirable properties, among which a typical adhesive must have sufficient peel adhesion and shear holding power, as well as flexibility to flex with the body, a high moisture vapor transmission rate (MVTR), and low medical adhesive-related skin injury (MARSI).

[0013] MVTR is a measure of the rate at which water vapor passes through a material or barrier. Because sweating occurs naturally on the skin, if a material or adhesive system has a low MVTR, this can lead to moisture accumulation between the skin and the adhesive, potentially causing the adhesive to "lift" or peel, or even promoting other adverse effects such as bacterial growth and skin irritation. Therefore, much effort has focused on developing adhesive systems with high MVTR.

[0014] Medical adhesive-related skin injury (MARSI) has a significant negative impact on patient safety. Skin injuries associated with the use of medical adhesives are a frequent but often overlooked complication that occurs in all care settings and across all age groups. Furthermore, treating skin injuries is costly in terms of service delivery, time, and additional treatments and supplies.

[0015] Skin damage occurs when the surface layer of the skin is removed along with the medical adhesive product, which not only affects the integrity of the skin but also causes pain and risk of infection, increases wound size and can delay healing, all of which reduce the patient's quality of life.

[0016] Medical adhesive tape can be simply defined as a pressure-sensitive adhesive and a backing that acts as a carrier for the adhesive. The U.S. Food and Drug Administration defines a medical adhesive tape or bandage as "a device intended for medical purposes consisting of a piece of fabric material or plastic coated on one side with an adhesive, which may include a surgical dressing pad that does not contain an antiseptic. The device is used to cover and protect a wound, to hold together the skin edges of a wound, to support an injured part of the body, or to fasten an object to the skin."

[0017] The pathophysiology of MARSI is only partially understood. Skin injury occurs when adhesive adhesion to the skin is stronger than skin cell adhesion. When adhesive strength exceeds the strength of skin cell to skin cell interactions, cohesive failure occurs within the skin cell layer.

[0018] Current medical adhesive systems have difficulty remaining on the skin for extended periods of time because they do not address the difference in mechanical properties between the skin and the adhesive, i.e., the difference in stress / strain that exists between the skin and the adhesive system. Skin typically has a low stress-strain relationship that can be approximated as 0.05 MPa for a strain of 1.0 or 0.02 MPa for a strain of 0.4. Skin is viscoelastic, and current adhesive systems are typically highly elastic. Due to the mechanical mismatch between the skin and current adhesive systems, when a current adhesive system is in place on the skin and the skin moves (stretching / tensioning and compressing / compressing forces), these adhesive systems do not move to the same extent as the skin, resulting in a stress / strain mismatch between the adhesive system material and the skin. This mismatch creates high shear forces at the interface between the adhesive layer and the skin to which it is adhered. As a result of these shear forces, current adhesive systems experience edge delamination and eventually peel away from the entire adhesive system.

[0019] Therefore, adhesive systems are desirably designed to (1) address the mechanical property mismatch that exists between the skin and the adhesive system, and (2) have a high MVTR. Conventional adhesive systems have attempted to address the problem of mechanical property mismatch and resulting edge delamination by using strong adhesives, i.e., adhesives with high adhesion to the skin. The strength of an adhesive is defined by its initial bond strength and its sustained adhesive strength. However, these strong adhesives do not address the key problems of strain mismatch and high shear forces that arise between the skin and the adhesive. Therefore, these attempts result in systems that do not stretch to the same extent as the skin, remain strongly attached to the skin, and result in very high shear forces that cause pain to the wearer, ultimately leading to edge delamination and peeling. Furthermore, the use of strong adhesives makes them very difficult and painful to remove from the skin when the wearer desires to remove the adhesive system. However, adhesives that are not sufficiently strong do not maintain adhesion to the skin as the skin stretches, resulting in edge delamination and peeling.

[0020] A recent attempt to solve the problem of incompatibility between the skin and the adhesive article is described in International Application PCT / WO 2018 / 125739. This publication describes an adhesive system having a first layer having a first layer material with a bottom portion having a top and bottom perimeter, and a first layer adhesive on the bottom portion for attachment to the skin, the first layer having an inherent elastic modulus. The adhesive system also includes a second adhesive along only the bottom perimeter, and the first layer includes multiple modifications that result in the first layer having an effective elastic modulus lower than the inherent elastic modulus of the first layer. The multiple modifications in the first layer are perforations.

[0021] The present disclosure describes an adhesive article that does not involve modifying the adhesive layer or using multiple adhesive layers, and does not involve perforating the backing layer of the adhesive article. Rather, the adhesive article of the present disclosure includes a continuous layer of adhesive having a first major surface and a second major surface, and a substrate layer having a first major surface and a second major surface, the first major surface of the substrate layer being in contact with the second major surface of the adhesive layer. The substrate layer includes a plurality of cuts, the plurality of cuts being arranged in a pattern. In some embodiments, the pattern may be random, while in other embodiments, the pattern may be arranged along at least one axis. The cuts are not perforations, since they are not formed by removing material from the substrate layer; however, the gaps are not visible to the naked eye when the adhesive article is in an unstressed state, but at least some of the gaps are visible to the naked eye when the adhesive article is in a stressed state.

[0022] The use of cuts rather than perforations has various advantages. Among other advantages, the cuts allow for a lower effective modulus without removing material from the substrate layer. The arrangement of cuts also provides improved MVTR. An advantage of using cuts instead of perforations is that the arrangement of cuts creates gaps that provide a visual indicator of the application of stress to the adhesive article. As described above, the cuts are gaps that are invisible to the naked eye when the adhesive article is in an unstressed state, but upon application of stress, at least some of the gaps become visible to the naked eye. In this way, the substrate itself can indicate when stress has been applied to the adhesive article. Thus, the cuts not only provide a way to reduce the effects of stress on the adhesive article, but also a way to visually detect when stress has been applied to the adhesive article. Methods for preparing these adhesive articles are also disclosed.

[0023] A medical structure is also disclosed herein. The medical structure includes a surface comprising mammalian skin and an adhesive article attached to the mammalian skin-containing surface. The adhesive article is described above and includes a continuous layer of adhesive having a first major surface and a second major surface, and a substrate layer having a first major surface and a second major surface, the first major surface of the substrate layer being in contact with the second major surface of the adhesive layer. The substrate layer includes a plurality of cuts, the plurality of cuts being arranged in a pattern; in some embodiments, the pattern is random, and in other embodiments, the pattern is arranged along at least one axis. The adhesive article may also further include a sensor or other device adhered to the second major surface of the substrate layer.

[0024] Unless otherwise indicated, all numbers expressing feature dimensions, quantities, and physical properties used in the specification and claims are to be understood as modified in all instances by the term "about." Accordingly, unless specifically indicated to the contrary, the numerical parameters set forth in the above specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by those of ordinary skill in the art utilizing the teachings disclosed herein. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

[0025] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include embodiments having plural referents unless the content clearly dictates otherwise. For example, reference to a "layer" includes embodiments having one, two, or more layers. As used in this specification and the appended claims, the term "or" is used generally in its sense including "and / or" unless the content clearly dictates otherwise.

[0026] As used herein, the term "adhesive" refers to a polymeric composition useful for adhering two adherends together. Examples of adhesives are pressure sensitive adhesives and gel adhesives.

[0027] It is well known to those skilled in the art that pressure-sensitive adhesive compositions possess properties including: (1) aggressive and persistent tack, (2) adhesion with no more than finger pressure, (3) sufficient ability to hold down an adherend, and (4) sufficient cohesive strength to remove cleanly from the adherend. Materials known to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelastic properties necessary to provide the desired balance of tack, peel adhesion, and shear holding power. Achieving the right balance of properties is not a simple process.

[0028] As used herein, the term "gel adhesive" refers to a tacky, semi-solid, cross-linked matrix containing a liquid or fluid that can adhere to one or more substrates. Gel adhesives may have some properties in common with pressure-sensitive adhesives, but are not pressure-sensitive adhesives. A "hydrogel adhesive" is a gel adhesive that has water as the fluid contained within the cross-linked matrix.

[0029] As used herein, the term "cut" refers to a narrow opening made in a substrate by the penetration of a cutting tool, whereby no material is removed from the substrate by the cutting process. The terms "cut" and "slit" are used interchangeably.

[0030] The term "(meth)acrylate" refers to a monomeric acrylic or methacrylic ester of an alcohol. Acrylate and methacrylate monomers or oligomers are collectively referred to herein as "(meth)acrylates." Materials referred to as "(meth)acrylate-functional" are materials that contain one or more (meth)acrylate groups.

[0031] As used herein, the term "siloxane-based" refers to a polymer or polymeric unit containing siloxane units. The terms silicone or siloxane are used interchangeably to refer to units having dialkyl or diaryl siloxane (-SiRO-) repeating units.

[0032] The terms "room temperature" and "ambient temperature" are used interchangeably and refer to temperatures in the range of 20°C to 25°C.

[0033] The terms "Tg" and "glass transition temperature" are used interchangeably. When measured, Tg values ​​are measured by differential scanning calorimetry (DSC) at a scan rate of 10°C / min unless otherwise indicated. Typically, Tg values ​​of copolymers are not measured but are calculated using the well-known Fox equation using homopolymer Tg values ​​provided by the monomer supplier, as will be understood by those skilled in the art.

[0034] As used herein, the term "adjacent" when referring to two layers means that the two layers are in close proximity to each other with no intervening open space between them. They may be in direct contact with each other (e.g., laminated together) or there may be an intervening layer.

[0035] As used herein, the term "pattern" refers to a plurality of discontinuities that form an array, the pattern of which may be a "random pattern," meaning that there are no readily identifiable repeating units within the array, or the array may be aligned along at least one axis. In some embodiments, the array is aligned along one axis, and in other embodiments, the array is aligned along two or more axes.

[0036] The terms "polymer" and "macromolecule" are used herein consistent with common usage in chemistry. Polymers and macromolecules are composed of many repeating subunits. As used herein, the term "macromolecule" is used to describe a group attached to a monomer having multiple repeating units. The term "polymer" is used to describe the resulting material formed from a polymerization reaction.

[0037] The term "alkyl" refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. Alkyl can be straight-chained, branched, cyclic, or a combination thereof and typically has 1 to 20 carbon atoms. In some embodiments, alkyl groups contain 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0038] The term "aryl" refers to a monovalent group that is aromatic and carbocyclic. An aryl can have 1 to 5 rings connected to or fused to the aromatic ring. Other ring structures may be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0039] The term "alkylene" refers to a divalent group that is a radical of an alkane. Alkylene can be straight-chained, branched, cyclic, or a combination thereof. Alkylene often has 1 to 20 carbon atoms. In some embodiments, alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of an alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms.

[0040] The terms "free radically polymerizable" and "ethylenically unsaturated" are used interchangeably and refer to a reactive group containing a carbon-carbon double bond that can be polymerized via a free radical polymerization mechanism.

[0041] As used herein, the term "gap" refers to a void space within a substrate that runs through the entire thickness of the substrate. Gaps can be prepared by cutting, slitting, boring, etc. In this disclosure, gaps are described as not visible to the naked eye when the substrate is in an unstressed state, and gaps are described as visible to the naked eye and forming "openings" when the substrate is in a stressed state. As used herein, the term "opening" is used according to its typical definition, a space through which light passes. As used herein, the term "hole" refers to a void in the surface of a substrate that is visible to the naked eye in both an unstressed and stressed state, and is an opening in both an unstressed and stressed state.

[0042] Disclosed herein are adhesive articles suitable for a wide range of medical uses. In some embodiments, the adhesive article comprises a continuous layer of adhesive having a first major surface and a second major surface, and a substrate layer having a first major surface and a second major surface, the first major surface of the substrate layer being in contact with the second major surface of the adhesive layer. The substrate layer comprises a plurality of cuts, the plurality of cuts being arranged in a pattern. In some embodiments, the pattern may be random, while in other embodiments, the pattern may be arranged along at least one axis. The cuts are gaps that are not visible to the naked eye when the adhesive article is in an unstressed state, but at least some of the gaps become visible to the naked eye when the adhesive article is in a stressed state.

[0043] A wide range of adhesives are suitable for use in the adhesive layer of the adhesive article of the present disclosure. In some embodiments, the adhesive comprises a pressure-sensitive adhesive, and in other embodiments, the adhesive comprises a gel adhesive. Suitable pressure-sensitive adhesives include (meth)acrylate-based pressure-sensitive adhesives and siloxane-based pressure-sensitive adhesives.

[0044] One suitable class of (meth)acrylate-based pressure-sensitive adhesives includes copolymers derived from (A) at least one monoethylenically unsaturated alkyl (meth)acrylate monomer (i.e., alkyl acrylate and alkyl methacrylate monomers) and (B) at least one monoethylenically unsaturated, free-radically copolymerizable reinforcing monomer. The reinforcing monomer has a higher homopolymer glass transition temperature (Tg) than the alkyl (meth)acrylate monomer, improving the glass transition temperature and cohesive strength of the resulting copolymer. As used herein, "copolymer" refers to a polymer containing two or more different monomers, including terpolymers, tetrapolymers, etc.

[0045] Monomer A, a monoethylenically unsaturated alkyl acrylate or methacrylate (i.e., (meth)acrylic acid ester), contributes to the flexibility and tackiness of the copolymer. Generally, Monomer A has a homopolymer Tg of about 0°C or less. Typically, the alkyl group of the (meth)acrylate has an average of about 4 to about 20 carbon atoms, or an average of about 4 to about 14 carbon atoms. The alkyl group may optionally contain an oxygen atom in the chain, for example, to form an ether or alkoxy ether. Examples of Monomer A include, but are not limited to, 2-methylbutyl acrylate, isooctyl acrylate, lauryl acrylate, 4-methyl-2-pentyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate, and isononyl acrylate. Other examples include, but are not limited to, polyethoxylated or polypropoxylated methoxy(meth)acrylates such as CARBOWAX (commercially available from Union Carbide) and NK Ester AM90G (commercially available from Shin-Nakamura Chemical Co., Ltd.) acrylate. Suitable monoethylenically unsaturated (meth)acrylates that can be used as monomer A include isooctyl acrylate, 2-ethyl-hexyl acrylate, and n-butyl acrylate. Combinations of various monomers classified as A monomers can be used to prepare copolymers.

[0046] Monomer B, a monoethylenically unsaturated, free-radically copolymerizable reinforcing monomer, improves the glass transition temperature and cohesive strength of the copolymer. Generally, monomer B has a homopolymer Tg of at least about 10°C. Typically, monomer B is a reinforcing (meth)acrylic monomer, including acrylic acid, methacrylic acid, acrylamide, or a (meth)acrylate. Examples of monomer B include, but are not limited to, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-hydroxyethylacrylamide, diacetoneacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-ethyl-N-aminoethylacrylamide, N-ethyl-N-hydroxyethylacrylamide, N,N-dihydroxyethylacrylamide, t-butylacrylamide, N,N-dimethylaminoethylacrylamide, and acrylamides such as N-octylacrylamide. Other examples of monomer B include itaconic acid, crotonic acid, maleic acid, fumaric acid, 2,2-(diethoxy)ethyl acrylate, 2-hydroxyethyl acrylate or methacrylate, 3-hydroxypropyl acrylate or methacrylate, methyl methacrylate, isobornyl acrylate, 2-(phenoxy)ethyl acrylate or methacrylate, biphenylyl acrylate, t-butylphenyl acrylate, cyclohexyl acrylate, dimethyl adamantyl acrylate, 2-naphthyl acrylate, phenyl acrylate, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Particularly suitable reinforcing acrylic monomers that can be used as monomer B include acrylic acid and acrylamide. Combinations of various reinforcing monoethylenically unsaturated monomers classified as B monomers can be used to prepare copolymers.

[0047] Typically, the (meth)acrylate copolymers are formulated to result in a Tg of less than about 0° C., more typically less than about −10° C. Such (meth)acrylate copolymers generally contain from about 60 parts to about 98 parts of at least one monomer A and from about 2 parts to about 40 parts of at least one monomer B. In some embodiments, the (meth)acrylate copolymers have from about 85 parts to about 98 parts of at least one monomer A and from about 2 parts to about 15 parts of at least one monomer B.

[0048] Examples of suitable (meth)acrylate-based pressure-sensitive adhesives that can be applied to the skin are described in U.S. Patent No. RE24,906. In some embodiments, a 97:3 isooctyl acrylate:acrylamide copolymer adhesive or a 70:15:15 isooctyl acrylate:ethylene oxide acrylate:acrylic acid terpolymer can be used, as described in U.S. Patent No. 4,737,410. Other useful adhesives are described in U.S. Patent Nos. 3,389,827, 4,112,213, 4,310,509, and 4,323,557.

[0049] Another class of suitable pressure-sensitive adhesives is siloxane-based adhesives. Examples of siloxane-based pressure-sensitive adhesives include those described in U.S. Patent Nos. 5,527,578 and 5,858,545, and International Application PCT / WO 00 / 02966. Specific examples include polydiorganosiloxane polyurea copolymers and blends thereof, and polysiloxane-polyalkylene block copolymers, as described in U.S. Patent No. 6,007,914. Other examples of siloxane pressure-sensitive adhesives include those formed from silanols, silicone hydrides, siloxanes, epoxides, and (meth)acrylates. When siloxane pressure-sensitive adhesives are prepared from (meth)acrylate-functional siloxanes, the adhesives are sometimes referred to as siloxane (meth)acrylates.

[0050] The siloxane adhesive composition contains at least one siloxane elastomeric polymer and may contain other ingredients such as a tackifying resin. Examples of elastomeric polymers include urea-based siloxane copolymers, oxyamide-based siloxane copolymers, amide-based siloxane copolymers, urethane-based siloxane copolymers, and mixtures thereof.

[0051] Useful siloxane polyurea block copolymers are disclosed, for example, in U.S. Pat. Nos. 5,512,650, 5,214,119, 5,461,134, and 7,153,924, and International Application Nos. PCT / WO 96 / 35458, 98 / 17726, 96 / 34028, 96 / 34030, and 97 / 40103.

[0052] Another useful class of siloxane elastomeric polymers are oxamide-based polymers, such as polydiorganosiloxane polyoxamide block copolymers, examples of which are provided, for example, in U.S. Patent Application Publication No. 2007-0148475.

[0053] Another useful class of siloxane elastomeric polymers are the amide-based siloxane polymers, which are similar to urea-based polymers, containing amide linkages (-N(D)-C(O)-) instead of urea linkages (-N(D)-C(O)-N(D)-), where C(O) represents a carbonyl group and D is hydrogen or an alkyl group.

[0054] Another useful class of siloxane elastomeric polymers are urethane-based siloxane polymers, such as siloxane polyurea-urethane block copolymers. Siloxane polyurea-urethane block copolymers comprise the reaction product of a polydiorganosiloxane diamine (also called a siloxane diamine), a diisocyanate, and an organic polyol. Structurally, these materials are very similar to the structure of Formula I, except that the -N(D)-BN(D)- bond is replaced with an -OBO- bond. Examples of such polymers are provided, for example, in U.S. Pat. No. 5,214,119.

[0055] In some embodiments, the siloxane-based pressure-sensitive adhesive further comprises a siloxane tackifying resin. Siloxane tackifying resins were previously called "silicate" tackifying resins, but that terminology has been replaced by the term "siloxane tackifying resin." The siloxane tackifying resin is added in an amount sufficient to achieve the desired tack and adhesion level. In some embodiments, multiple siloxane tackifying resins can be used to achieve the desired performance.

[0056] Suitable siloxane tackifying resins are commercially available from sources such as Dow Corning (e.g., DC 2-7066), Momentive Performance Materials (e.g., SR545 and SR1000), and Wacker Chemie AG (e.g., BELSIL TMS-803).

[0057] Another class of adhesives used in medical applications are silicone gels. As used herein, the terms "siloxane" and "silicone" are used interchangeably. While the term siloxane replaces silicone in common usage, both terms are used in the art. Silicone gel (crosslinked polydimethylsiloxane (PDMS)) materials have been used in dielectric fillers, vibration dampers, and medical therapies to promote scar tissue healing. Lightly crosslinked silicone gels are soft, tacky, and elastic materials containing a relatively high concentration of fluid (liquid). Silicone gels are typically softer than silicone pressure-sensitive adhesives, resulting in less discomfort when applied to the skin. The combination of reasonable adhesive retention on the skin and reduced trauma to the skin upon removal makes silicone gels suitable for skin-friendly adhesive applications.

[0058] Silicone gel adhesives provide good adhesion to skin with gentle removal and the ability to reposition. Examples of commercially available silicone gel adhesive systems include products sold under the trade names Dow Corning MG 7-9850, WACKER 2130, BLUESTAR 4317 and 4320, and NUSIL 6345 and 6350. These skin-friendly adhesives are formed by an addition cure reaction between vinyl-terminated and hydrogen-terminated PDMS in the presence of a hydrosilylation catalyst (e.g., a platinum complex). Due to their specific chemical moieties, vinyl-terminated and hydrogen-terminated PDMS chains are referred to as "functionalized" silicones. Individually, such functional silicones are generally not reactive, but together they form a reactive silicone system. Furthermore, silicone resins (tackifiers, sometimes called "silicate resins") and PDMSs with multiple hydrogen functional groups (crosslinkers) can be blended to modify the adhesive properties of the gel.

[0059] The substrate layer is typically a thin film material. The film material is sufficiently rigid to provide support for the adhesive article. The substrate layer is modified by cutting and is flexible enough to conform to the anatomical surface. Thus, when the dressing is applied to a tissue surface, it can conform to the surface, expanding and contracting even as the surface moves. The modification process of the present disclosure allows for the use of a wide range of film materials that would otherwise not conform to the anatomical surface. Suitable material classes include thermoplastics, elastomers, and nonwovens. The substrate layer can be prepared from a wide range of materials, including polyolefins, polyurethanes, polyesters, polyether block amides, or natural fiber-based materials. One particularly suitable substrate is Sontara nonwoven material from Sontara America, which is a tightly interlocking nonwoven film without holes suitable for use in medical barrier and drape applications.

[0060] The substrate layer has a wide range of thicknesses. In some embodiments, the thickness is at least 10 micrometers and up to 254 micrometers (10 mils), and in some embodiments, the thickness is from 25 micrometers (1 mil) to up to 178 micrometers (7 mils). A wide range of intermediate thicknesses is also suitable.

[0061] As described above, the substrate layer includes a plurality of cuts arranged in a pattern; in some embodiments, the pattern can be random; in other embodiments, the pattern is arranged along at least one axis. The two-dimensional surface of the substrate layer can be considered to have two major orthogonal axes, often referred to as the x-axis and the y-axis. Due to the method of making the film, the x-axis is often referred to as the "machine direction" or MD, and the orthogonal y-axis is referred to as the "cross direction" or CD. Typically, the plurality of cuts are arranged in a pattern along the machine direction. This means that the lengths of the plurality of cuts are aligned along the machine direction of the substrate layer.

[0062] The multiple cuts arranged in a pattern are gaps, but these gaps are essentially invisible to the naked eye when the substrate layer is in an unstressed state. When the adhesive article is in a stressed state, at least some of the gaps are visible to the naked eye. As used herein, the term "stressed state" includes stretching, bending, or a combination thereof. Because the cuts are very thin (i.e., essentially widthless) in an unstressed state, they are typically described by their length and depth. Generally, the cuts extend through the entire thickness of the substrate layer, so their depth is the same as the thickness of the substrate layer. One parameter that can describe the relationship of the length of a cut to its width is the aspect ratio. The term "aspect ratio" is typically used to describe particles, but as used herein, it is used to describe hole sizes or void areas where no material is present. In some embodiments, the aspect ratio (ratio of length to width) of the cuts is greater than 1000. When stress is applied, the aspect ratio of the cuts decreases. An example of a suitable cut is one that is 1 centimeter long and 5 micrometers wide.

[0063] The discontinuities can be more complex than the simple linear shapes described above. The discontinuities can have various two-dimensional shapes, such as crosses, asterisks, chevrons, letters, and numbers, as long as they are not visible to the naked eye in an unstressed state, and at least some of the discontinuities become gaps visible to the naked eye when the adhesive article is in a stressed state. Furthermore, when stress is applied to the article, not only do the gaps become visible to the naked eye, but the gaps also become openings through which light can pass. In this way, when stress is applied, the openings formed allow for viewing through the substrate layer.

[0064] In some embodiments, the cuts are arranged in a pattern along the machine direction of the substrate. Often, the cuts are formed by a process known as "skip slitting." In this process, a series of discontinuous slits are formed in a linear fashion within the substrate. If one follows the line of the slits along the substrate surface where they are encountered, the slit ends, there is an unslitted area, then a new slit is encountered, the slit ends, that slit encounters an unslitted area, and so on. This type of pattern is described in International Application PCT / WO 19 / 043621. In these patterns, the area between the end of one slit and the beginning of the next slit is called the bridge area. While wide patterns are preferred, in some embodiments, the patterns have a 50% offset. This means that if two linear arrays exist in the machine direction, when viewed in the cross direction, the bridge areas of the first array correspond to the slits of the second array, and vice versa.

[0065] In some embodiments, the plurality of cuts are arranged in a pattern along two or more axes, meaning that at least some of the cuts have lengths that are not aligned with the machine direction of the substrate layer but are offset from alignment by up to 90°. The lengths that are offset from alignment at 90° with the MD of the substrate layer are aligned in the cross direction.

[0066] The cuts can be made in several different ways, as long as the method does not involve removing material from the substrate layer, and the cuts form gaps that are essentially invisible to the naked eye in an unstressed state, at least some of the gaps becoming visible to the naked eye when the adhesive article is in a stressed state. Among these methods are those in which the cuts are introduced into the substrate layer when the layer is formed, for example, by extrusion, molding, machining, etc. Another method is to introduce the cuts into the substrate layer after it is formed, by cutting with a cutting tool such as a knife, linear blade, rotary die blade, water jet, or laser light, or by stamping with a stamping tool. In some embodiments, the cuts are made by feeding the substrate layer into a nip that includes a rotary die blade and an anvil, so that the die cuts through the substrate layer to form a cut pattern.

[0067] In some embodiments, the substrate layer is not modified until the adhesive layer is applied to it to form the article, and then a cut is formed in the substrate layer. As described below, in some embodiments, the cut is present only in the substrate layer. In other embodiments, the cut is present in the substrate layer and the adhesive layer.

[0068] The substrate layer of the article has an effective modulus of elasticity in at least one axis that is lower than that of an identical substrate layer without multiple cuts. In other words, modifying the substrate layer with multiple cuts reduces the effective modulus of elasticity. Elastic modulus (also called modulus of elasticity) is a quantity that measures the resistance of an object or substance to elastic (i.e., non-permanently) deformation when stress is applied. The modulus of elasticity of an object is defined as the slope of the stress-strain curve within the elastic deformation region. Effective modulus is defined in the art as the ratio of average stress to average strain, which results in a major portion when subjected to pure shear or pure compression on its outer boundary. In the present disclosure, effective modulus is the modulus of elasticity of the substrate layer or an adhesive article including the substrate layer after the substrate layer has been modified by the cuts.

[0069] Although perforating the substrate layer may seem like an equally suitable method for reducing the effective modulus, it has been found that the use of perforations does not provide the same reduction in modulus. In this context, the term "perforation" is used according to its commonly used definition and refers to a hole through the substrate prepared by a method for removing material from the substrate. Unlike the cuts of the present disclosure, perforations are easily visible to the naked eye, whether in an unstressed or stressed state.

[0070] The adhesive articles of the present disclosure have desirable optical properties. Among the desirable optical properties is that when the adhesive article is in a stressed state, the adhesive article has optical properties that are different from the optical properties of the adhesive article when it is in an unstressed state. The difference in optical properties relates to a property of an adhesive article in which a plurality of discontinuities arranged in a pattern are gaps that are invisible to the naked eye when the substrate layer is in an unstressed state, and at least some of the gaps become visible to the naked eye when the adhesive article is in a stressed state. For example, gaps that become visible in the substrate layer upon application of stress are evidenced by portions of the substrate layer changing from opaque to light-transmitting. In this way, the surface to which the stressed adhesive article is applied can become visible. If discontinuities are not present in the adhesive layer, applying stress to the adhesive article can make portions of the adhesive layer visible.

[0071] The detection of the change in optical properties is typically detectable with the naked eye. As mentioned above, discontinuities in the substrate layer are not visible to the naked eye, but applying stress to the adhesive article makes the discontinuities visible to the naked eye. In the present disclosure, the "naked eye" includes an optical system or optical device that includes the naked eye. Examples of optical devices include optical sensing devices that are adapted to detect changes in optical properties. In some embodiments, the optical device may include a camera designed to take a series of photographs, whereby comparison of the photographs provides an indication of the change in the optical properties of the adhesive article.

[0072] The change in optical properties when stress is applied to the adhesive article is useful for a variety of reasons. For example, the application of stress to the adhesive article when applied to a patient may result from swelling due to injury or from exudate caused by a wound. In some embodiments, the visible indication of stress applied to the adhesive article may result from simple movement, bending, twisting, etc. by the patient wearing the adhesive article, thus indicating excessive movement, bending, twisting, etc.

[0073] Also disclosed herein is an adhesive article that not only includes an adhesive layer and a substrate layer, but also includes a device attached to the second major surface of the substrate layer. A wide range of devices, such as sensors or monitors, are suitable. An advantage of the adhesive article of the present disclosure is that its flexibility allows the adhesive article to be worn for extended periods of time without the problems described above. Thus, the adhesive article of the present disclosure can be worn for extended periods of time, for example, for days, weeks, or even longer. This can be particularly important for adhesive articles that include devices that are intended to be worn by patients for extended periods of time. A further advantage of adhesive articles that include the modified substrate of the present disclosure is that the reduced effective elastic modulus provides a flexible damping layer between the flexible skin and the generally rigid device. This flexible damping layer allows increased movement by the wearer of the device without causing stress on the device or on the connection between the device and the skin.

[0074] Also disclosed herein are medical structures. The medical structures include a surface comprising mammalian skin and an adhesive article, such as those described above, attached to the surface comprising mammalian skin. These adhesive articles include a continuous layer of adhesive having a first major surface and a second major surface, and a substrate layer having a first major surface and a second major surface, the first major surface of the substrate layer being in contact with the second major surface of the adhesive layer. The substrate layer includes a plurality of cuts, the plurality of cuts being arranged in a pattern, in some embodiments, the pattern being random, and in other embodiments, the pattern being arranged along at least one axis, the cuts being gaps that are invisible to the naked eye when the adhesive article is in an unstressed state, and at least some of the gaps being gaps that become visible to the naked eye when the adhesive article is in a stressed state. The first major surface of the adhesive layer is in contact with and adhesively bonded to the surface comprising mammalian skin. As described above, the adhesive article may further include a device attached to the second major surface of the substrate layer.

[0075] Also disclosed herein are methods for preparing adhesive articles. In some embodiments, the method includes providing a substrate layer having a first major surface and a second major surface, modifying the substrate layer by creating a plurality of cuts in the substrate layer without removing material from the substrate layer, such that under an unstressed state, the cuts are gaps that are invisible to the naked eye, and under a stressed state, at least some of the gaps become visible to the naked eye, providing an adhesive, and forming a continuous layer of the adhesive on the first major surface of the substrate layer.

[0076] In some embodiments, modifying the substrate layer includes cutting a plurality of cuts into the substrate layer with a knife, blade, water jet, or laser light. A wide variety of techniques are suitable for modifying the substrate layer. Examples of modifications include cutting using a cutting tool such as a knife, linear blade, rotary die blade, water jet, or laser light, or stamping using a stamping tool. In some embodiments, the cuts are made by feeding the substrate layer into a nip including a rotating die blade and anvil, such that the die cuts through the substrate layer to form a cut pattern.

[0077] In many embodiments, the substrate layer is modified before forming the continuous layer of adhesive on the first major surface of the substrate layer. In this way, the substrate layer can be modified at a different location or at a different time from the formation of the adhesive article. In some embodiments, the continuous layer of adhesive on the first major surface of the substrate layer is formed before modifying the substrate layer. Modifying the substrate layer can involve simply modifying the substrate layer, or modifying the substrate layer can involve modifying both the substrate layer and the adhesive layer. In these embodiments, the multiple discontinuities present in the substrate layer are also present in the adhesive layer.

[0078] As described above, the method of forming the adhesive article further includes attaching a device to the second major surface of the substrate layer. Suitable devices are described above.

[0079] The articles of the present disclosure can be more fully understood from the figures, which are more fully described in the Examples section below. FIG. 1A shows an article of the present disclosure, in which the gaps formed by the array of cuts are essentially invisible in an unstressed state; upon applying stress to the article by pulling on the underlying substrate to which the article is attached, the gaps become visible, and the underlying substrate can be clearly seen through the gaps. Furthermore, as the underlying substrate stretches, the article elongates, demonstrating the elastic modulus that allows the article to elongate. FIGS. 1B and 1C show a comparative substrate having perforations. As can be seen, the perforations are visible in both the stressed and unstressed states. Furthermore, application of stress to the underlying substrate to which the article is attached does not stretch the perforated substrate, indicating that the elastic modulus of the article does not allow the article to elongate. [Example]

[0080] These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. The following abbreviations are used: mm = millimeters, kHz = kilohertz.

[0081] Preparation and measurement of test specimens A strip of Sonata nonwoven material (Sonata America, Inc., Candler, NC) was coated with a medical-grade adhesive. A pattern was laser cut (laser settings: 13% power, 75 kHz, 1000 mm / sec, 2 passes) into the coated Sontara material, including a slit (Example 1) and two diameter round holes (Comparative Examples C1 and C2). The patterned, coated Sontara was then laminated to the spandex mold fabric with a hand roller, leaving unlaminated spandex fabric exposed on the top and bottom of the sample. Test specimens were cut with a 2-inch x 5-inch (approximately 51 x 127 mm) piece of Sontara material centered in the center of the specimen, and approximately 12 mm of spandex mold fabric exposed at each end. The specimen was secured to a measurement grid by the exposed spandex on the top, and the exposed spandex mold fabric on the bottom was gripped to allow the specimen to stretch. The specimen shape and cut pattern can be seen in Figure 1A (Example 1), Figure 1B (Comparative Example C1), and Figure 1C (Comparative Example C2).

[0082] The specimens were imaged using an attached iPhone X camera, and histograms were calculated. Each specimen was then stretched approximately 12 mm, images were recorded, and histograms were calculated. Finally, the specimens were stretched to their maximum extent, and the imaging and histogram calculations were repeated. Images are shown in Figures 1A-C. Histograms were calculated using ImageJ (an image processing program available at imagej.net) and are shown in Figures 2A-C.

[0083] Discussion of results The Sonata fabric resists stretching and deformation. The skip-slit processing allowed for greater maximum stretch of the specimens, and the resulting histograms were altered by exposure of the underlying spandex material through an open slit in the dark. This is due to the skip-slit pattern's ability to allow deformation, as shown in Figure 1A. Figure 2A provides histograms of the skip-slit specimens in the relaxed (unstretched) state, stretched approximately 12 mm, and fully stretched from left to right, respectively.

[0084] The specimens with round perforations did not promote elongation but deformed into an oval shape. This deformation did not expose significantly more spandex material, and the histograms showed no significant changes. The specimens with 12 mm perforations (Figure 2B, left, center, and right) allowed slightly greater elongation, but this did not result in significant differences between the histograms. The specimens with 2 mm perforations also did not deform significantly into an oval shape (Figure 2C, left and center).

[0085] The visible changes are due to the Sonata and spandex fabric layers having different optical responses. Optical performance is captured by histogram comparison of the perforated / slit areas when in the relaxed and stretched states. The stretched slit samples showed significant changes in the mean, mode, and standard deviation of the grayscale values ​​compared to the perforated ones. The sign of the value change is related to the selection of top and bottom contrast. The magnitude of the change is related to the ability of the pattern to expose the underlying material and the magnitude of the stretch.

Claims

1. An adhesive article comprising: a continuous layer of adhesive having a first major surface and a second major surface; and a substrate layer having a first major surface and a second major surface, wherein the first major surface of the substrate layer is in contact with the second major surface of the adhesive layer; the substrate layer includes a plurality of cuts; the plurality of cuts are arranged in a pattern, and the cuts are gaps, wherein the gaps are not visible to the naked eye when the adhesive article is in a stress-free state; an adhesive article, wherein at least some of the cuts become gaps visible to the naked eye when the adhesive article is in a stressed state.

2. The adhesive article according to claim 1, wherein when the adhesive article is in a stressed state, at least a portion of the gaps visible to the naked eye provides an opening that can be seen through the adhesive article.

3. The adhesive article according to claim 1, wherein the plurality of cuts are arranged in a pattern along one axis or along two or more axes.

4. The adhesive article according to claim 1, wherein the adhesive comprises a gel adhesive or a pressure-sensitive adhesive.

5. The adhesive article according to claim 1, wherein the substrate layer comprises a thermoplastic film of polyolefin, polyurethane, polyester, or polyether block amide.

6. The adhesive article according to claim 1, wherein the stressed state includes elongation, bending, or a combination thereof.

7. The adhesive article according to claim 1, wherein when the adhesive article is in a stressed state, the adhesive article has optical properties different from the optical properties of the adhesive article when the adhesive article is in a stress-free state.

8. The adhesive article according to claim 1, wherein the substrate layer has an effective elastic modulus in at least one axis that is lower than that of the same substrate layer without the plurality of cuts.

9. The adhesive article according to claim 1, further comprising a device attached to the second major surface of the substrate layer.

10. A medical structure comprising: a surface including mammalian skin; and an adhesive article attached to the surface including mammalian skin, the adhesive article comprising: a continuous layer of adhesive having a first major surface and a second major surface; and a substrate layer having a first major surface and a second major surface. The first major surface of the base material layer is in contact with the second major surface of the adhesive layer. The base material layer includes a plurality of cuts, and the plurality of cuts are arranged in a pattern. The cuts are gaps, but at least a part of the gaps are invisible to the naked eye when the adhesive article is in a first state. At least a part of the gaps that are invisible to the naked eye when in the first state become visible gaps to the naked eye when the adhesive article is in a second state. The second state is a state of being subjected to higher stress, bending, stretching, or a combination thereof. The first major surface of the adhesive layer is in contact with a surface including the skin of a mammal. Medical structure. Claim 11 A method for preparing an adhesive article, comprising: providing a base material layer having a first major surface and a second major surface; modifying the base material layer by making a plurality of cuts in the base material layer without removing material from the base material layer, wherein the cuts are gaps in a stress-free state and the gaps are invisible to the naked eye, but at least a part of the gaps becomes visible to the naked eye in a stressed state; providing an adhesive; forming a continuous layer of the adhesive on the first major surface of the base material layer.

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