Medical pressure-sensitive adhesive articles that can be worn for extended periods

Abstract

The pressure-sensitive adhesive article comprises a substrate having a first major surface and a second major surface, and a pressure-sensitive adhesive layer disposed on at least a portion of the first major surface of the substrate. The pressure-sensitive adhesive layer is an E-beam cured composition of a (meth)acrylate-based polymer that does not contain acid or amide functionality, and at least one tackifier that is a hydrogenated hydrocarbon resin. The pressure-sensitive adhesive layer has a static shear to protein leather of at least 600 minutes.

Description

Summary of the Invention

[0001] Disclosed herein are pressure-sensitive adhesive articles and medical structures made using the pressure-sensitive adhesive articles. In some embodiments, the pressure-sensitive adhesive article comprises a substrate having a first major surface and a second major surface, and a pressure-sensitive adhesive layer disposed on at least a portion of the first major surface of the substrate. The pressure-sensitive adhesive layer comprises an E-beam curing composition comprising a (meth)acrylate-based polymer that does not contain acid or amide functional groups, and at least one tackifier that comprises a hydrogenated hydrocarbon resin. The pressure-sensitive adhesive layer has a static shear against protein leather of at least 600 minutes.

[0002] Also disclosed is a medical structure. In some embodiments, the medical structure comprises a surface comprising mammalian skin and an adhesive article adhesively affixed to the surface. The adhesive article is described above. The present application may be more fully understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which: [Brief description of the drawings]

[0003] [Figure 1] 1 is a graph of static shear on sebum coated protein leather for Examples E21, E22, E24, and E25. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] The use of adhesive products in the medical industry has been widespread for a long time and is increasing. However, while adhesives and adhesive articles have shown themselves to be very useful for medical applications, the use of adhesives and adhesive articles also presents problems. In particular, the properties desired for an adhesive are often contradictory. For example, it is desirable for an adhesive to have high adhesion to many surfaces, including human skin, but it is also desirable for the adhesive to be removable without damaging the skin. In addition, the period of wear of medical articles is becoming longer, and the medical article needs to remain adhered and be removable without damaging the skin or leaving any residue.

[0005] Medical adhesive-related skin injury (MARSI) has a significant negative impact on patient safety. Skin injuries related to the use of medical adhesives are a common, yet under-recognized, complication that occurs in all care settings and across all age groups. In addition, treating skin injuries is costly in terms of service provision, time, and additional treatments and consumables.

[0006] Skin injury occurs when the superficial layer of the skin is removed along with the medical adhesive product, which can not only affect the integrity of the skin but also cause pain and risk of infection, increase the size of the wound, and delay healing, all of which reduce the patient's quality of life.

[0007] The pathophysiology of MARSI is only partially understood. Skin injury occurs when the adhesive forces between the skin and the skin are stronger than the adhesive forces between the skin cells. When adhesive forces exceed the strength of the skin cell-skin cell interactions, cohesive failure occurs within the skin cell layer.

[0008] A typical medical adhesive article comprises an adhesive layer and a substrate layer, which may be, for example, a tape backing. Other medical adhesive articles may have other substrate layers and include multiple layers, devices, etc. In this case, the unique properties of all components of the adhesive article must be considered to address these factors that may cause MARSI. The adhesive properties to consider include cohesion over time and the corresponding adhesion. The tape / backing / dressing properties to consider include breathability, stretch, compatibility, flexibility, and strength.

[0009] The widespread use of adhesives in medical applications has led to the development of skin-friendly adhesives and adhesive articles. Some of these adhesives are pressure-sensitive adhesives. The application of pressure-sensitive adhesives, including (meth)acrylate-based and silicone-based pressure-sensitive adhesives, for skin adhesion is known in the art, and many examples are commercially available.

[0010] A class of adhesive materials that are widely used as pressure-sensitive adhesives are (meth)acrylate-based pressure-sensitive adhesives. These materials have many desirable characteristics, such as not requiring the use of added tackifying agents because they are often inherently tacky, are typically formed by free radical polymerization with high conversions (meaning that little or no unpolymerized monomers remain in the formed pressure-sensitive adhesive), and a wide range of monomers can be used to form (meth)acrylate-based copolymers to tailor the desired properties of the pressure-sensitive adhesive. In many cases, (meth)acrylate-based pressure-sensitive adhesives are prepared from reaction mixtures that contain monomers with polar groups, such as acidic and basic groups. Acidic and basic monomers are often classified as reinforcing monomers in the adhesives art, since they tend to increase the cohesive strength of (meth)acrylate-based pressure-sensitive adhesives. It is therefore a challenge to prepare (meth)acrylate-based pressure-sensitive adhesives that retain the necessary cohesive strength to be useful in medical applications without including either acidic or basic reinforcing monomers.

[0011] As used herein, the term "adhesive" refers to a polymeric composition that is useful for adhering two adherends together. An example of an adhesive is a pressure sensitive adhesive.

[0012] Pressure sensitive adhesive compositions are well known to those skilled in the art to have properties including: (1) strong and permanent tack, (2) adhesion with no more than finger pressure, (3) sufficient ability to be held on the substrate, and (4) sufficient cohesion to be removed cleanly from the substrate. Materials that have been found to perform well as pressure sensitive adhesives are polymers designed and formulated to exhibit the necessary viscoelastic properties, resulting in the desired balance of tack, peel adhesion, and shear retention. Obtaining the proper balance of properties is not an easy process.

[0013] The term "(meth)acrylate-based" refers to a polymer that contains at least (meth)acrylate monomers and may also contain additional copolymerizable monomers.

[0014] The term "(meth)acrylate" refers to monomeric acrylic or methacrylic acid esters of alcohols. Acrylate and methacrylate monomers or oligomers are collectively referred to herein as "(meth)acrylates."

[0015] The term "protein leather" is used herein according to its commonly understood meaning. Protein leather, also known as synthetic leather, is composed of protein powder and resins that form flexible sheets that resemble leather in appearance and durability.

[0016] The term "hydrocarbon-based" is used herein to describe tackifying resins and plasticizers and refers to materials that are hydrocarbons, meaning that they contain carbon and hydrogen atoms and are essentially free of functional groups.

[0017] The term "hydrogenated" is used herein to describe materials, such as tackifier resins, that are fully hydrogenated (meaning that the material or resin is substantially free of unsaturated groups) or partially hydrogenated (meaning that a significant amount of the unsaturated groups in the material or resin, typically 70% or more, are hydrogenated).

[0018] The terms "room temperature" and "ambient temperature" are used interchangeably to mean a temperature in the range of 20°C to 25°C.

[0019] The term "adjacent" as used herein when referring to two layers means that the two layers are close 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.

[0020] The terms "polymer" and "macromolecule" are used herein consistent with their 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.

[0021] The term "alkyl" refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. An alkyl can be straight chain, branched chain, cyclic, or a combination thereof and typically has 1 to 20 carbon atoms. In some embodiments, an alkyl group contains 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.

[0022] The term "aryl" refers to a monovalent group that is aromatic and carbocyclic. An aryl can have 1 to 5 rings attached or fused to an 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.

[0023] The term "heteroalkyl" refers to a monovalent radical of alkyl having one or more interstitial heteroatoms. The heteroatoms are -O- or -NR-, where R is an H atom or an alkyl group.

[0024] The terms "free radically polymerizable" and "ethylenically unsaturated" are used interchangeably and refer to a reactive group that contains a carbon-carbon double bond that can be polymerized via a free radical polymerization mechanism.

[0025] A pressure-sensitive adhesive article is disclosed herein. The adhesive article comprises a substrate having a pressure-sensitive adhesive layer disposed on at least a portion of the substrate surface. The substrate and the pressure-sensitive adhesive layer are described in detail below. The adhesive article of the present disclosure has a wide range of desirable properties. The desirable properties include the ability to be worn for extended periods of time without causing skin damage. One measure for modeling the desirable characteristics of such adhesive articles is the measurement of static shear. Static shear measurements, particularly on surfaces that mimic mammalian, and particularly human, skin, provide a simulated long-term wearability of the adhesive article. In the present disclosure, protein leather is used as a particularly suitable test surface. Protein leather refers to artificial leather (sometimes called synthetic leather) that is composed of protein powder and resins that form pliable sheets. These sheets resemble leather in appearance and durability. The use of protein leather in the testing of samples is described in detail in the Examples section. One particularly suitable protein leather is the protein leather PBZ13001 KAKI manufactured by Ideatex Japan Co., Ltd.

[0026] As mentioned above, it is desirable that the adhesive article is removable from the skin of a mammal without causing skin damage. In some embodiments, the adhesive article is removable after 5 days. In many embodiments, the adhesive article is removable after a longer period of time, such as 7 days, 14 days, 21 days, 30 days or longer. Typically, skin damage is determined by physical examination of the site where the adhesive article is applied.

[0027] In some embodiments, the pressure-sensitive adhesive article comprises a substrate having a first major surface and a second major surface, and a pressure-sensitive adhesive layer disposed on at least a portion of the first major surface of the substrate. The pressure-sensitive adhesive layer comprises an E-beam curing composition comprising a (meth)acrylate-based polymer that does not contain acidic or amide functional groups, and at least one tackifier comprising a hydrogenated hydrocarbon resin. In some embodiments, the pressure-sensitive adhesive article further comprises at least one hydrocarbon-based plasticizer. The static shear of the pressure-sensitive adhesive layer against protein leather is at least 600 minutes. In some embodiments, the static shear of the adhesive article is at least 1,000 minutes, at least 2,000 minutes, or even at least 2,880 minutes. The method used to measure the static shear against protein leather is described in the Examples section below.

[0028] The adhesive article of the present disclosure comprises a substrate. A wide variety of substrates are suitable for the article of the present disclosure. In many embodiments, the substrate comprises a substrate suitable for use in medical articles. Examples of suitable substrates include polymeric films, fabrics, nonwovens, foams, papers, meshes, adhesives, or release liners. In some embodiments, the substrate comprises a breathable and conformable backing, such as a highly moisture vapor permeable film backing. Examples of such backings, methods of making such films, and methods of testing their permeability are described, for example, in U.S. Pat. Nos. 3,645,835 and 4,595,001.

[0029] Generally, the substrate is conformable to the anatomical surface. Thus, when the article is applied to the anatomical surface, the article conforms to the surface even when the surface is moved. Generally, the substrate is also conformable to the anatomical joint of the animal. When the joint is flexed and then returned to its unflexed position, the substrate stretches to accommodate the flexion of the joint, but is sufficiently resilient to continue to conform to the joint when the joint is returned to its unflexed state.

[0030] Examples of particularly suitable film backings can be found in U.S. Patent Nos. 5,088,483 and 5,160,315 and include films made from elastomeric polyurethane, polyester, or polyether block amides, which have a desirable combination of properties including resilience, high water vapor permeability, and transparency.

[0031] The pressure-sensitive adhesive article of the present disclosure also comprises a pressure-sensitive adhesive layer disposed on a substrate. The pressure-sensitive adhesive layer mainly comprises a (meth)acrylate-based polymer. This means that the (meth)acrylate-based polymer content of the adhesive layer is greater than 50% by weight. In some embodiments, the amount of (meth)acrylate-based polymer present in the pressure-sensitive adhesive layer is at least 70% by weight.

[0032] The (meth)acrylate-based polymers are prepared from a polymerization reaction mixture that includes at least a first (meth)acrylate monomer, at least one copolymerizable polar monomer that does not include an acidic or amide functionality, and at least one free radical initiator.

[0033] In some embodiments, the reaction mixture comprises at least 75 parts by weight of a compound of general formula I: CH2=CR 1 -(CO)-OR 2 Formula I (In the formula, R 1 is hydrogen or a methyl group, R 2is an alkyl, heteroalkyl, or aryl group). A wide range of (meth)acrylate monomers are suitable. In some embodiments, the first (meth)acrylate monomer comprises an alkyl (meth)acrylate monomer having from 4 to 12 carbon atoms. Exemplary monomers include, but are not limited to, those selected from the group consisting of esters of acrylic acid or methacrylic acid with non-tertiary alkyl alcohols, such as 1-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 1-methyl-1-butanol, 1-methyl-1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol, 3,5,5-trimethyl-1-hexanol, 3-heptanol, 2-octanol, 1-decanol, 1-dodecanol, and the like, and mixtures thereof. Such acrylate or methacrylate monomers are known in the art and commercially available. Particularly suitable are alkyl (meth)acrylate monomers having 8 to 12 carbon atoms, such as 2-ethylhexyl acrylate and isooctyl acrylate.

[0034] The reaction mixture used to form the (meth)acrylate-based polymer further contains at least one copolymerizable polar monomer that does not contain acidic or amide functional groups.Typically, in order to increase the internal cohesion of the pressure-sensitive adhesive, a (meth)acrylate monomer having an acidic or amide functional group is copolymerized in the (meth)acrylate polymer used to form the pressure-sensitive adhesive.Pressure-sensitive adhesives prepared from polymers containing only alkyl (meth)acrylate monomers tend to have very weak cohesion.

[0035] The reaction mixture of the present invention does not contain (meth)acrylate monomers with acid or amide functionality, because the presence of these monomers in the pressure-sensitive adhesive polymer may cause skin damage problems when the adhesive article is worn for extended periods of time. Therefore, polar monomers that are neither acid nor amide functional are used.

[0036] Representative examples of suitable polar monomers include, but are not limited to, 2-hydroxyethyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate; N-vinylpyrrolidone (NVP); N-vinylcaprolactam (NVC); poly(alkoxyalkyl) (meth)acrylates including 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, 2-methoxyethyl methacrylate, and polyethylene glycol mono(meth)acrylate; alkyl vinyl ethers including vinyl methyl ether; and mixtures thereof. One particularly suitable polar monomer is NVP (N-vinylpyrrolidone).

[0037] The amount of polar monomer present in the reaction mixture can vary. Typically, the polar monomer is present in an amount of at least 1 wt. %, and typically not more than 30 wt. %. More typically, the polar monomer is present in an amount of 2-20 wt. %.

[0038] In addition to the monomers listed above, the reaction mixture may further include one or more additional copolymerizable monomers. A wide range of copolymerizable monomers are suitable. In some embodiments, the copolymerizable monomer includes a copolymerizable photocrosslinker. The copolymerizable photocrosslinker is a material that contains a free radically polymerizable group that copolymerizes with the above monomers. The copolymerizable photocrosslinker also contains a photosensitive group that, when exposed to the proper wavelength of light, typically high intensity ultra-violet (UV) radiation, forms a free radical that can form crosslinks in the polymer. When the (meth)acrylate-based polymer is formed by the use of a photoinitiator, the photocrosslinker is not activated by the same wavelength of light as the photoinitiator. In this way, the copolymerizable photocrosslinker is incorporated into the polymer and can be heat treated since the crosslinker is thermally stable and will remain intact until activated by the appropriate wavelength of light. This allows the copolymerizable photocrosslinker to be activated until the polymer is hot melt coated. The coated crosslinkable pressure-sensitive adhesive layer is exposed to a high intensity UV lamp to effect crosslinking. Examples of suitable UV lamps include medium pressure mercury lamps or UV black lights.

[0039] Suitable photocrosslinkers include monoethylenically unsaturated aromatic ketone comonomers that do not contain an ortho-aromatic hydroxyl group, such as those described in U.S. Pat. No. 4,737,559 (Kellen et al.). Specific examples include para-acryloxybenzophenone (ABP, also known as AEBP), para-acrylyoxyethoxybenzophenone, para-N-(methylacryloxyethyl)-carbamoylethoxybenzophenone, para-acryloxyacetophenone, ortho-acrylamidoacetophenone, acrylated anthraquinone, and the like. Particularly suitable is ABP para-acryloxybenzophenone, also known as 4-acryloxybenzophenone.

[0040] Typically, such photocrosslinkers are used in amounts of about 0.05 to 0.50 phr. The term phr means Parts per Hundred Rubber, a measure used in the rubber industry to indicate the amount of a particular component required, particularly prior to vulcanization. In this case, the term phr refers to parts by weight of photocrosslinker per 100 parts by weight of total monomers present in the reaction mixture. In some embodiments, the photocrosslinker is present in an amount of about 0.10 parts by weight of crosslinker per 100 parts by weight of total monomers present in the reaction mixture.

[0041] As described in more detail below, the use of a photocrosslinker is not necessary because the pressure-sensitive adhesive undergoes crosslinking via exposure to electron beam radiation, although such materials can aid in the formation of a crosslinked pressure-sensitive adhesive by providing additional crosslinks.

[0042] The reaction mixture also includes at least one free radical initiator. The initiator may be a thermal initiator or a photoinitiator. A thermal initiator is an initiator that is activated to form free radicals when exposed to high temperatures. A photoinitiator is an initiator that is activated by light, typically ultraviolet (UV) light. The choice of initiator depends on various factors, especially the composition of the reaction mixture. When a photocrosslinker is used, a photoinitiator is not desirable because exposure to light, such as UV light, can prematurely activate the photocrosslinker. In many embodiments, a thermal initiator is used.

[0043] Many possible thermal free radical initiators are known in the art of vinyl monomer polymerization and can be used.Typical thermal free radical polymerization initiators useful herein are organic peroxides, organic hydroperoxides, and azo-based initiators that generate free radicals.Useful organic peroxides include, but are not limited to, compounds such as benzoyl peroxide, di-t-amyl peroxide, t-butyl peroxybenzoate, and dicumyl peroxide.Useful organic hydroperoxides include, but are not limited to, compounds such as t-amyl hydroperoxide and t-butyl hydroperoxide. Useful azo initiators include, but are not limited to, VAZO compounds from DuPont, such as VAZO52 (2,2'-azobis(2,4-dimethylpentanenitrile), VAZO64 (2,2'-azobis(2-methylpropanenitrile), VAZO67 (2,2'-azobis(2-methylbutanenitrile), and VAZO88 (2,2'-azobis(cyclohexanecarbonitrile)). Additional commercially available thermal initiators include, for example, LUPERSOL130 (2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3), available from Elf Atochem, Philadelphia, PA, and LUPEROX101 (2,5-dimethyl-2,5-di-(tert-butylperoxoxy)hexane), available from Arkema Canada, Inc., Oakville. US Patent Application Publication No. 2011 / 0300296 describes the polymerization process in detail, and in some embodiments includes a mixture of initiators.

[0044] In some embodiments, the initiator is a photoinitiator. Examples of suitable free radical photoinitiators include DAROCURE 1173, DAROCURE 4265, IRGACURE 184, IRGACURE 651, IRGACURE 1173, IRGACURE 819, LUCIRIN TPO, LUCIRIN TPO-L, available from BASF, Charlotte, NC. Photoinitiator DAROCURE 1173 is particularly suitable.

[0045] Generally, the initiator is used in an amount of from 0.01 to 2 parts by weight, more typically from 0.1 to 0.5 parts by weight, based on 100 parts by weight of total reactive components.

[0046] The pressure-sensitive adhesive layer further comprises at least one tackifier comprising a hydrogenated hydrocarbon resin. The tackifier is a minor component in the pressure-sensitive adhesive layer, meaning that it constitutes less than 50% by weight of all components of the layer. Typically, the tackifier is present in an amount of 5 to 40% by weight, or 10 to 30% by weight, or 15 to 25% by weight.

[0047] Conventional (meth)acrylate pressure sensitive adhesives use tackifier resins that include materials such as rosin esters and terpene phenolic resins that are not suitable for the adhesive article of the present invention. Rosin esters and terpene phenolic resins are frequently used tackifier resins because they are highly compatible with (meth)acrylate polymers. Rosin esters and terpene phenolic resins are not suitable tackifier resins for the adhesive article of the present invention because they can cause skin sensitization. This is especially true in articles of the present invention that are crosslinked by exposure to electron beams. The reason is that such exposure can cause the decomposition of rosin esters and terpene phenolic resins to form small molecules that irritate the skin. Therefore, hydrogenated hydrocarbon resins are used in the adhesive article of the present invention. The hydrogenated hydrocarbon resins can be fully hydrogenated or partially hydrogenated hydrocarbon resins. Partially hydrogenated hydrocarbon resins can be suitable as long as they are sufficiently compatible with the remaining components of the pressure sensitive adhesive. Fully hydrogenated hydrocarbon resins are preferred in many embodiments, but partially hydrogenated hydrocarbon resins can also be useful. Fully hydrogenated hydrocarbon tackifier resins are substantially free of unsaturated groups and free of polar groups. A wide range of hydrogenated hydrocarbon tackifier resins are suitable. Suitable resins include those available under the trade names ES300, ES320, ES340, ES380, ES600 and ES615 from Aquent Impex, as well as some resins available from Arakawa Chemical. Examples of suitable resins from Arakawa Chemical include those under the trade name ARKON, such as the ARKON M series (partially hydrogenated), such as ARKON M-100, ARKON M-115, ARKON M-135, and ARKON M-90, and the ARKON P series (fully hydrogenated), such as ARKON P-100, ARKON P-115, ARKON P-125, ARKON P-140, and ARKON P-90. One particularly suitable tackifier is ARKON P-100.

[0048] In some embodiments, the pressure-sensitive adhesive article of the present disclosure further comprises at least one hydrocarbon-based plasticizer. Plasticizers are common additives used in many polymer compositions, such as pressure-sensitive adhesives. Plasticizers are typically added to increase the flexibility or processability of polymer systems. Plasticizers typically affect the viscosity of the polymer composition, lower the glass transition temperature, and lower the modulus of elasticity. Typical classes of plasticizers include phthalates and terephthalates. Plasticizers, like tackifiers, are selected for their compatibility with the polymer composition. Typical plasticizers used with (meth)acrylate-based pressure-sensitive adhesives include phthalates, terephthalates, benzoates, and epoxidized oils, such as Epoxidized Soybean Oil (ESO).

[0049] The choice of suitable plasticizers in the pressure-sensitive adhesive layers of the present invention is limited in various ways. The chemical nature of the pressure-sensitive adhesive layers of the present invention limits which plasticizers are suitable, and the use of these pressure-sensitive adhesive layers in medical articles also limits the choice of suitable plasticizers. Because the pressure-sensitive adhesive layers of the present invention contain hydrogenated hydrocarbon resins, many conventional plasticizers are not suitable. Conventional plasticizers are not highly compatible with these hydrogenated hydrocarbon materials. Therefore, when plasticizers are used in the pressure-sensitive adhesive layers of the present invention, these plasticizers are typically hydrocarbon-based. This is because hydrocarbon-based plasticizers are highly compatible with hydrogenated hydrocarbon resins. In this way, the plasticizers help to compatibilize the (meth)acrylate-based polymers and hydrogenated hydrocarbon tackifier resins in the pressure-sensitive adhesive layers. In addition, as mentioned above, the plasticizer must be biocompatible. This means that the plasticizer does not cause adverse reactions when applied to the skin. Examples of suitable plasticizers include IOP (iso-octyl palmitate), polyester polyol PRIPLAST 3197 available from Croda, tea tree oil, and mineral oil.

[0050] As mentioned above, the pressure-sensitive adhesive layer is a cross-linked pressure-sensitive adhesive layer, and cross-linking is achieved by exposure to electron beam (E-beam) radiation. Cross-linking is used to increase the cohesive strength of the pressure-sensitive adhesive layer. E-beam curing is particularly desirable in the articles of the present invention because it does not require an initiator to achieve cross-linking and therefore does not leave initiator residues in the cross-linked pressure-sensitive adhesive layer.

[0051] Various procedures for E-beam curing are well known and depend on the particular equipment used, and those skilled in the art can define dose calibration models for particular equipment, geometries, and line speeds, as well as other well-understood process parameters.

[0052] Commercially available electron beam generating equipment is readily available. In the examples described herein, radiation treatment was performed with a Model CB-300 electron beam generator (available from Energy Sciences, Inc., Wilmington, Mass.). Typically, a support film (e.g., a polyester terephthalate support film) is passed through the chamber. In some embodiments, a sample of uncured material may be affixed to the support film, which may have liners (e.g., fluorosilicone release liners) on both sides ("closed side"), and transported at a fixed speed of about 6.1 meters / minute (20 feet / minute). In some embodiments, the sample of uncured material may be applied to one liner, and the opposite surface may be linerless ("open side"). Typically, the chamber is inerted (e.g., the oxygen-containing room air is replaced with an inert gas, e.g., nitrogen), and the sample is E-beam cured, especially for open-side curing.

[0053] A wide range of E-beam dosages are suitable for crosslinking the pressure-sensitive adhesive layers of the articles of the present disclosure, hi some embodiments, the pressure-sensitive adhesive layers are crosslinked with an E-beam dosage of 0.5 to 4.0 megarads.

[0054] The crosslinked pressure sensitive adhesive layer can be of any suitable thickness depending on the desired application. In some embodiments, the thickness is at least 10 micrometers and up to 2 millimeters, and in some embodiments, the thickness is at least 20 micrometers and up to 1 millimeter thick. A wide range of intermediate thicknesses are also suitable, such as 25 to 500 micrometers, 200 to 400 micrometers, etc.

[0055] A wide variety of methods of making the adhesive articles of the present disclosure are suitable. Typically, the (meth)acrylate-based polymer is prepared by mixing the monomeric components with an initiator to form a reaction mixture. In some embodiments, the components are dispersed in a solvent or mixture of solvents. Suitable solvents include hydrocarbon solvents, such as hexane, heptane, and the like, aromatic solvents, such as benzene or toluene, or esters, such as ethyl acetate. The reaction mixture is polymerized by activating the initiator (typically by heating above the activation temperature of the initiator). The desired additives (tackifiers and plasticizers, if used) are then added to the polymerization mixture, and the resulting mixture is coated onto a surface (typically a release liner), dried by heating, and cured. Curing requires exposure to E-beam radiation as described above, and may also require exposure to UV light if a photocrosslinker is incorporated into the (meth)acrylate-based polymer. When crosslinked on the release liner, the resulting pressure-sensitive adhesive layer can then be laminated to the surface of the desired substrate. A wide variety of release liners are suitable. Release liners are commonly used and well understood in the adhesive art. Exemplary release liners include those made from paper (e.g., kraft paper) or polymeric materials (e.g., polyolefins such as polyethylene or polypropylene, ethylene vinyl acetate, polyurethane, polyesters such as polyethylene terephthalate, and the like, and combinations thereof). At least some release liners are coated with a layer of a release agent, such as a silicone-containing material or a fluorocarbon-containing material. Exemplary release liners include, but are not limited to, polyethylene terephthalate film with a silicone release coating, commercially available from CP Film (Martinsville, Va.) under the trade names "T-30" and "T-10".

[0056] Also disclosed herein is a medical structure. In some embodiments, the medical structure comprises a surface comprising mammalian skin and an adhesive article adhesively attached to the surface. The adhesive article comprises the article described above. In some embodiments, the adhesive article comprises a substrate having a first major surface and a second major surface, and a pressure-sensitive adhesive layer disposed on at least a portion of the first major surface of the substrate. The pressure-sensitive adhesive layer comprises an E-beam curing composition comprising a (meth)acrylate-based polymer having no acid or amide functional groups, at least one tackifier comprising a hydrogenated hydrocarbon resin, and optionally at least one hydrocarbon-based plasticizer. The pressure-sensitive adhesive layer has a static shear to protein leather of at least 600 minutes.

[0057] As mentioned above, it is desirable that the adhesive article is removable from the skin of a mammal without causing skin damage. In some embodiments, the adhesive article is removable after 5 days. In many embodiments, the adhesive article is removable after a longer period of time, such as 7 days, 14 days, 21 days, 30 days or longer. Typically, skin damage is determined by physical examination of the site where the adhesive article is applied.

[0058] Suitable components of the adhesive article, including the substrate and the pressure-sensitive adhesive layer, are described in detail above. EXAMPLES

[0059] All percentages are by weight unless otherwise noted.

[0060] [Table 1]

[0061] Study 1: Examples E1-E8 and Comparative Examples C1-C4 Monomers, initiator, and solvent were mixed in a glass jar according to the polymer formulation shown in Table 2. The solution was purged with nitrogen for 2 minutes (min) and then polymerization was carried out at 60° C. for 24 hours (hr) to obtain a viscous polymer solution.

[0062] The resulting polymer solution was mixed with additives P-100 and / or 3197 according to the formulation shown in Table 3, and then coated on the surface of the TSC using a knife coater. Additive P-100 acts as a tackifier, and 3197 acts as a plasticizer. The coated TSC was dried in an oven (70°C for 2 minutes, followed by 120°C for 2 minutes). As shown in Table 3, a pressure-sensitive adhesive (PSA) sheet with a thickness of 100 micrometers (μm) was obtained after curing using either ultraviolet (UV) radiation or electron beam (E-beam). Sontara was then laminated onto the PSA sheet by hot can lamination at 120°C after corona treatment (PSA surface was corona treated using corona generator AGF-B10 (Kasuga Electric Co., Ltd., 0.15 kW)). Hot can lamination is described in U.S. Pat. No. 6,703,108 (Bacon et al.).

[0063] [Table 2]

[0064] [Table 3]

[0065] The substrate was protein leather PBZ13001 KAKI protein leather available from Ideatex Japan Co., Ltd. (Tokyo, Japan). Protein leather is a synthetic material with a surface of polyurethane blended with protein powder. The surface and elastic properties of protein leather are such that the inventors find it to be a useful elastic substrate for simulating testing on human skin.

[0066] The substrate was prepared by applying a synthetic sebum coating. The synthetic sebum solution prepared according to Table 4 was coated onto protein leather using a D-bar coater (No. 30) and dried at 70°C to obtain a synthetic sebum-coated protein leather. The blank cut from the coated protein leather was approximately 30 mm x 125 mm.

[0067] [Table 4]

[0068] Static Shear Test Sample tapes measuring 25 mm x 75 mm were prepared, and a 25-micrometer-thick polyester (polyethylene terephthalate, PET) film was laminated to the top 50 mm area of ​​each sample tape to prevent the sample tape from peeling off due to stretching.

[0069] The PET film laminated sample tape was laminated to one end of the coated protein leather blank with a 25 mm overlap, then compressed with a 2 kilogram (kg) roller (reciprocating, 50 millimeters per second (mm / sec)) to obtain the prepared test specimen.

[0070] The additionally prepared test specimens were fixed in a 145-DP retention tester (Yasuda Seiki Seisakusho Co., Ltd., Tokyo, Japan). After the chamber conditions reached 40°C and 75% relative humidity (RH), the prepared test specimens were held at these conditions for 4 hours without load. After 4 hours, a load of 300 g was applied to each test specimen, and the retention time was measured.

[0071] Static peel test using protein leather A sample tape with dimensions of 12.5 mm x 125 mm was prepared and one end of the sample tape was folded to form a tab. The tape sample was laminated onto a synthetic sebum-coated protein leather and then compressed with a 2 kg roller (reciprocating, 50 mm / sec).

[0072] One end of the laminated protein leather was fixed in a jig, and then a clip was attached to the tab of the laminated tape sample. A 100g weight was attached to the clip, and the static T-peel test was started. The test time was 10 minutes, and the migration length of the delaminated tape was measured. If the tape completely delaminated within 10 minutes, the estimated migration time was calculated based on the drop time according to ((laminated length) / (drop time) x (10 minutes)).

[0073] Test results The results of the static shear test on synthetic sebum coated protein leather and the static peel test on synthetic sebum coated protein leather are shown in Table X. All trial samples showed good static shear performance at the appropriate cure level (EB: 2 megarad (MRad), UV: 20 millijoules (mJ)) compared to commercial 3M medical tape 4076 (Comparative Example C5). At higher cure levels, the PSA lost flexibility, showed reduced stress relaxation performance, and the PSA delaminated from the protein leather. There was no significant static shear performance difference in the trial formulations. It is believed that the most important factor for achieving good static shear performance is to have a suitable polymer network that can provide both good cohesion and stress relaxation.

[0074] [Table 5]

[0075] Static peel testing shows that PSAs formulated with P-100 tackifier had improved performance. The tackifier provided good initial tack and resistance to peel force. The addition of 3197 plasticizer can improve skin wetting, and at least in this trial, 5% plasticizer loading provided acceptable static peel performance.

[0076] Another factor is that chemically stable PSA formulations are preferred to minimize the risk of medical adhesive-related skin injury (MARSI). Residual monomers or photoinitiators may cause skin hypersensitivity. Although ABP can provide a good polymer network with suitable UV curing, there is a risk that residual benzophenone moieties may irritate the skin. PSAs containing residual monomers or photoinitiators may not be suitable for skin application, especially for long-term wear.

[0077] Study 2: Examples E9-E12 Monomers, initiator, and solvent were mixed in a glass jar according to the formulation shown in Table 6. The solution was purged with nitrogen for 2 minutes and then polymerized at 60° C. for 24 hours to prepare a viscous polymer solution.

[0078] The resulting polymer solution was mixed with the additives shown in Table 7 and coated onto the surface of TSC using a knife coater and then dried in an oven (70°C for 2 minutes, followed by 120°C for 2 minutes). After E-beam curing at 3MRad, a 100 μm thick PSA sheet was obtained. Sontara was then laminated onto the cured PSA sheet by hot can lamination at 120°C after corona treatment as described above. Details of the formulation and test conditions are shown in Tables 6 and 7.

[0079] [Table 6]

[0080] [Table 7]

[0081] Static shear tests using uncoated protein leather Specimens for static shear testing were prepared as described in Study 1, except that the protein leather was not coated with synthetic grease.

[0082] Static shear testing was performed as described in Study 1, except the chamber conditions were 30° C. and 75% RH. The maximum test time was 1440 minutes. The results are shown in Table 8. These results confirm the preferred level of NVP in the polymer for extended wear applications. NVP loadings greater than 5% may be required to obtain adequate cohesion.

[0083] [Table 8]

[0084] Study 3: Examples E13 to E20 Polymers 1 and 6 were synthesized by mixing the monomers, initiator, and solvent in a glass jar as shown in Table 9. The solution was purged with nitrogen for 2 minutes and then polymerized at 60° C. for 24 hours to prepare a viscous polymer solution.

[0085] The resulting polymer solutions were formulated as shown in Table 10 and coated onto the TSC surface using a knife coater and then dried in an oven (70° C. for 2 minutes, followed by 120° C. for 2 minutes). After E-beam curing at each of the conditions shown in Table 8, PSA sheets with a thickness of 100 micrometers were obtained. After corona treatment, Sontara was laminated to the PSA sheets by hot can lamination at 120° C.

[0086] [Table 9]

[0087] [Table 10]

[0088] Static shear tests using uncoated protein leather Static shear specimens were prepared as above using uncoated protein leather, using chamber conditions of 30°C and 75% RH. The results are shown in Figure 5. In this study, we confirmed the effect of the molecular weight of the acrylic polymer. Polymer 1 had a higher molecular weight than polymer 6 and showed better static shear performance. For low molecular weight polymers, a higher crosslinking level was required to achieve adequate cohesion. However, the polymer loses stress relaxation performance at high crosslinking levels. Therefore, it is not easy to find a suitable crosslinking level for low molecular weight polymers. For long-term wear applications, the use of higher molecular weight polymers should be preferred.

[0089] [Table 11]

[0090] Study 4: Examples E21 to E50 Coatable PSA solutions were prepared according to the formulations shown in Table 12, coated onto paper liners using a knife coater, and dried in an oven. After E-beam curing at each condition, PSA sheets of 100 micrometer thickness were obtained. For static shear testing, Sontara was laminated to each PSA sheet by hot can lamination at 120°C after corona treatment. For tack testing, PET was laminated to the PSA sheet using a hand roller.

[0091] [Table 12]

[0092] The synthetic sebum-coated protein leather was used to fabricate static shear specimens as described above. The synthetic sebum solution was prepared according to Table 13, and coated on the protein leather using a D-bar coater (No. 30), followed by drying at 70°C to obtain synthetic sebum-coated protein leather. The static shear test results at various levels of e-beam dose for Examples E21, E22, E24 and E25 were obtained and shown in Figure 1. Figure 1 shows the effect of e-beam dose on PSA crosslink density. The results show that PSA may have optimal properties at intermediate levels of crosslinking. Low levels of crosslinking resulted in cohesive failure, and high levels showed poor peel properties.

[0093] [Table 13]

[0094] Finger tack test PSA tack stability was evaluated in the PSA open face state. PET laminate samples were fixed on cardboard with the adhesive surface exposed to air. The fixed samples were kept at ambient laboratory conditions for 3 months. The finger tack test was then used to check the adhesion of the PSA according to the criteria in Table 14.

[0095] [Table 14]

[0096] The open surface stability of the PSA tack is an important performance characteristic for long term applications. When a PSA is used to attach a medical device to the skin, the device / PSA combination can be stored without a liner in the applicator exposed to air. If there is a compatibility issue between the tackifier and the acrylic polymer, the tackifier will migrate to the PSA surface and the PSA will lose its adhesive properties. Based on the results shown in Table 15, the combination of PSA-1 and P-100 was the only solution in the trial.

[0097] [Table 15]

Claims

1. A substrate having a first main surface and a second main surface, A pressure-sensitive adhesive layer disposed on at least a portion of the first main surface of the substrate, A (meth)acrylate polymer that does not contain acidic or amide functional groups, and which is present in the pressure-sensitive adhesive layer in an amount of at least 70% by weight, The E-beam curing composition comprises at least one tackifier containing a hydrogenated hydrocarbon resin, A pressure-sensitive adhesive article comprising a pressure-sensitive adhesive layer having a static shear of at least 600 minutes to a protein leather, as measured according to this specification.

2. The pressure-sensitive adhesive article according to claim 1, further comprising at least one hydrocarbon-based plasticizer.

3. The (meth)acrylate polymer is prepared from the polymerization reaction mixture, At least 75 parts by weight, formula: CH ２ =CR １ -(CO)-OR2 (In the formula, R １ is a hydrogen or methyl group, R ２ The first (meth)acrylate monomer is an alkyl, heteroalkyl, or aryl group, A copolymerizable polar monomer that does not contain acidic or amide functional groups, A pressure-sensitive adhesive article according to claim 1, comprising at least one free radical initiator.

4. The pressure-sensitive adhesive article according to claim 3, wherein the first (meth)acrylate monomer comprises an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms.

5. The pressure-sensitive adhesive article according to claim 3, wherein the copolymerizable polar monomer comprises NVP (N-vinylpyrrolidone).

6. The pressure-sensitive adhesive article according to claim 3, wherein the reaction mixture further comprises at least one copolymerizable monomer.

7. The pressure-sensitive adhesive article according to claim 1, wherein the pressure-sensitive adhesive layer is crosslinked with an E-beam dose of 0.5 to 4.0 megarads.

8. A pressure-sensitive adhesive article according to claim 1, which is removable after being bonded for at least five days.

9. The pressure-sensitive adhesive article according to claim 1, wherein the substrate comprises at least one material selected from the group consisting of polymer film, cloth, nonwoven fabric, foam, paper, mesh, and release liner.

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