Method of making polydiorganosiloxane adhesive with porous substrate and articles

Abstract

Adhesive (e.g. medical) articles are described comprising a layer of a crosslinked nonfunctionalized polydiorganosiloxane adhesive composition having a first major surface and second opposing major surface; and a porous substrate proximate the first major surface, proximate the second major surface, embedded within the polydiorganosiloxane adhesive layer, or a combination thereof. The porous substrate is a fibrous substrate or apertured organic polymer film. The apertures can be formed before or after application of the polydiorganosiloxane adhesive composition.

Description

[0001] METHOD OF MAKING POLYDIORGANOSILOXANE ADHESIVE WITH POROUS SUBSTRATE AND ARTICLES

[0002] Summary

[0003] Adhesive articles, such as medical articles, are described comprising a layer of a crosslinked nonfunctionalized polydiorganosiloxane adhesive composition having a first major surface and second opposing major surface; and a porous substrate proximate the first major surface, proximate the second major surface, embedded within the polydiorganosiloxane adhesive layer, or a combination thereof.

[0004] The porous substrate is a fibrous substrate or apertured organic polymer film. The apertures can be formed before or after application of the polydiorganosiloxane adhesive composition.

[0005] In some embodiments, the thickness of the polydiorganosiloxane adhesive composition is at least 250 microns. In some embodiments, the article comprises a plurality of apertures that extend through the porous substrate and layer of crosslinked nonfunctionalized polydiorganosiloxane adhesive composition.

[0006] Also described are methods of making adhesive (e.g. medical) articles.

[0007] Brief Description of the Drawings

[0008] FIGs. 1-3 are schematic side view of articles comprising a crosslinked silicone adhesive and a porous substrate.

[0009] Written Description

[0010] With reference to FIGs. 1-3, the adhesive article (100, 200, 300) generally comprises providing a layer of crosslinked polydiorganosiloxane composition on a support, such as a release liner (140, 240, 340). The layer of polydiorganosiloxane composition further comprises a porous substrate (180, 280, 380). The layer of polydiorganosiloxane composition has a first major surface (121, 221, 321) proximate the release liner support (140, 240, 340) and an opposing second major surface (123, 223, 323). The major surfaces are typically parallel to each other. The thickness of the layer(s) is the distance in the direction orthogonal to the major surfaces.

[0011] Polydioganosiloxane Composition

[0012] Silicone gel materials have been used for medical therapies for promoting scar tissue healing. Lightly crosslinked silicone gels are soft, tacky, elastic materials that have low to moderate adhesive strength compared to traditional, tackified silicone PSAs. Silicone gels are typically softer than silicone PSAs, resulting in less discomfort when adhered to and removed from skin. The combination of relatively low adhesive strength and moderate tack make silicone gels suitable for gentle to skin adhesive applications. Crosslinked siloxane networks described herein are formed from non-functional silicone materials. These gel adhesives have excellent wetting characteristics, due to the very low glass transition temperature (Tg) and modulus of the poly siloxane network.

[0013] The silicone materials are polydiorganosiloxanes, i.e., materials comprising a polysiloxane backbone. In some embodiments, the nonfunctionalized silicone materials can be a linear material described by the following formula illustrating a siloxane backbone with aliphatic and / or aromatic substituents: wherein Rl, R2, R3, and R4 are independently selected from the group consisting of an alkyl group and an aryl group, each R5 is an alkyl group and n and m are integers, and at least one of m or n is not zero. In some embodiments, one or more of the alkyl or aryl groups may contain a halogen substituent, e.g., fluorine. For example, in some embodiments, one or more of the alkyl groups may be -CH2CH2C4F9.

[0014] In some embodiments, R5 is a methyl group, i.e., the nonfunctionalized polydiorganosiloxane material is terminated by trimethylsiloxy groups. In some embodiments, Rl and R2 are alkyl groups and n is zero, i.e., the material is a poly (dialkylsiloxane). In some embodiments, the alkyl group is a methyl group, i.e., poly(dimethylsiloxane) (“PDMS”). In some embodiments, Rl is an alkyl group, R2 is an aryl group, and n is zero, i.e., the material is a poly (alkylarylsiloxane). In some embodiments, Rl is methyl group and R2 is a phenyl group, i.e., the material is poly(methylphenylsiloxane). In some embodiments, Rl and R2 are alkyl groups and R3 and R4 are aryl groups, i.e., the material is a poly(dialkyldiarylsiloxane). In some embodiments, Rl and R2 are methyl groups, and R3 and R4 are phenyl groups, i.e., the material is poly(dimethyldiphenylsiloxane).

[0015] In some embodiments, the nonfunctionalized polydiorganosiloxane materials may be branched. For example, one or more of the Rl, R2, R3, and / or R4 groups may be a linear or branched siloxane with alkyl or aryl (including halogenated alkyl or aryl) substituents and terminal R5 groups.

[0016] As used herein, “nonfunctional groups” are either alkyl or aryl groups consisting of carbon, hydrogen, and in some embodiments, halogen (e.g., fluorine) atoms. As used herein, a “nonfunctionalized polydiorganosiloxane material” is one in which the Rl, R2, R3, R4, and R5 groups are nonfunctional groups.

[0017] Nonfunctionalized polydiorganosiloxane lack functional groups including hydride group, a hydroxy group, an alkoxy group, a vinyl group, an epoxy group, and an acrylate group.

[0018] The polydiorganosiloxanes (e.g. polydimethylsiloxanes PDMS) may be oils, fluids, gums, elastomers, or resins, e.g., friable solid resins. Lower molecular weight, lower viscosity materials are referred to as fluids or oils, while higher molecular weight, higher viscosity materials are referred to as gums; however, there is no sharp distinction between these terms. Silicone oils are commercially available (e.g. from Wacker) at viscosities from 0.65 to 1,000,000 mPa* sec at 25 °C. In typical embodiments, higher viscosity (e.g. non-functional) liquid polydiorganosiloxanes are preferred. In some embodiments, the liquid polydiorganosiloxane has a viscosity of at least 50,000; 100,000; 250,000; 500,000; 750,000, or 1,000,000 mPa*sec at 25 °C. When polydiorganosiloxane gum is utilized, the viscosity may be greater than 1,000,000 mPa*sec at 25 °C.

[0019] The gentle to skin adhesives are prepared by combining one or more polydiorganosiloxane materials (e.g., silicone oils or fluids), optionally with an appropriate tackifying resin, coating the resulting combination, and crosslinking using radiation, typically electron beam (E-beam) or gamma irradiation. Generally, any known additives useful in the formulation of adhesives may also be included.

[0020] In some embodiments, silicate tackifying resins may be used. In some exemplary adhesive compositions, a plurality of silicate tackifying resins can be used to achieve desired performance.

[0021] Suitable silicate tackifying resins include those resins composed of the following structural units M (i.e., monovalent RfySiO 1 / 2 units), D (i.e., divalent R'2SiO2 / 2 units), T (i.e., trivalent R'SiO3 / 2 units), and Q (i.e., quaternary SiOq / 2 units), and combinations thereof. Typical exemplary silicate resins include MQ silicate tackifying resins, MQD silicate tackifying resins, and MQT silicate tackifying resins. These silicate tackifying resins usually have a number average molecular weight in the range of 100 to 50,000- gm / mole, e.g., 500 to 15,000 gm / mole and generally R' groups are methyl groups.

[0022] MQ silicate tackifying resins are copolymeric resins where each M unit is bonded to a Q unit, and each Q unit is bonded to at least one other Q unit. Some of the Q units are bonded to only other Q units. However, some Q units are bonded to hydroxyl radicals resulting in HOSiO3 / 2 units (i.e., "TOH" units), thereby accounting for some silicon-bonded hydroxyl content of the silicate tackifying resin.

[0023] The amount of silicon bonded hydroxyl groups (i.e., silanol) on the MQ resin may be reduced to no greater than 1.5 weight percent, no greater than 1.2 weight percent, no greater than 1.0 weight percent, or no greater than 0.8 weight percent based on the weight of the silicate tackifying resin. This may be accomplished, for example, by reacting hexamethyldisilazane with the silicate tackifying resin. Such a reaction may be catalyzed, for example, with trifluoroacetic acid. Alternatively, trimethylchlorosilane or trimethylsilylacetamide may be reacted with the silicate tackifying resin, a catalyst not being necessary in this case.

[0024] MQD silicone tackifying resins are terpolymers having M, Q and D units. In some embodiments, some of the methyl R' groups of the D units can be replaced with vinyl (CH2=CH-) groups ("D^1" units). MQT silicate tackifying resins are terpolymers having M, Q and T units. Suitable silicate 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).

[0025] In some embodiments, the layer of polydiorganosiloxane composition comprises (e.g. silicate) tackifying resin in an amount of at least 5, 6, 7, 8, 9, or 10 wt.% of the total polydiorganosiloxane composition. In some embodiments, the amount of (e.g. silicate) tackifying resin is not greater than 20, 25 or 10 wt.%. In other embodiments, the amount of (e.g. silicate) tackifying is less than 5, 4, 3, 2, or 1 wt.% (e.g. zero).

[0026] In some embodiments, the polydiorganosiloxane composition may include any of a variety of known fillers (e.g. siliceous fillers, such as fumed silica) and additives including, but not limited to, pigments, additives for improving adhesion, additives for improving moisture-vapor transmission rate, antimicrobial agents (e.g. silver materials), pharmaceutical agents, cosmetic agents, natural extracts, silicone waxes, silicone pofyethers, hydrophilic polymers and rheology modifiers. Hydrophilic additives used to improve adhesion, particularly to wet surfaces, include polymers such as poly (ethylene oxide) polymers, polypropylene oxide) polymers and copolymers of polyethylene oxide and propylene oxide), acrylic acid polymers, hydroxyethyl cellulose polymers, carboxyethyl cellulose, silicone pofyether copolymers, such as copolymers of polyethylene oxide) and polydiorganosiloxane and copolymers of polypropylene oxide) and polydiorganosiloxane, and blends thereof. The polydiorganosiloxane composition may comprise various combinations of additives.

[0027] In some embodiments, the polydiorganosiloxane composition comprises fillers and / or additives in amounts up to 10, 15, 20, 25, or 30 wt.% of the total polydiorganosiloxane composition. In other embodiments, the polydiorganosiloxane composition comprises less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 wt.% of fillers and / or additives.

[0028] The pofysiloxane material, the tackifying resin, if present, and any optional additives may be combined by any of a wide variety of known means prior to being coated and crosslinked. For example, in some embodiments, the various components may be pre-blended using common equipment such as mixers, blenders, mills, extmders, and the like.

[0029] In some embodiments, the materials may be dissolved in a solvent, coated, and dried prior to crosslinking. In some embodiments, solventless compounding and coating processes may be used. In some embodiments, solventless coating may occur at about room temperature. For example, in some embodiments, the materials may have kinematic viscosity of no greater than 100,000 centistokes (cSt), e.g., no greater than 50,000 cSt. However, in some embodiments, hot melt coating processes such as extrusion may be used, e.g., to reduce the viscosity of higher molecular weight materials to values more suitable for coating. The various components may be added together, in various combinations or individually, through one or more separate ports of an extruder, blended (e.g., melt mixed) within the extruder, and extruded to form the hot melt coated composition. Porous Sub state

[0030] A variety of porous substrate can be utilized in the articles described herein. Porous substrates can be made from a variety of (e.g. thermoplastic) organic polymer materials such as polyesters, polyurethanes, polyamides (e.g. nylon), polyimides, and polyolefins. In typical embodiments, the porous substrate is a fibrous web or an apertured film. When the film is an apertured film, the film may be apertured before or after crosslinking of the polydiorganosiloxane layer. Thus, although the article comprises a porous substrate, in some embodiments the method utilizes a non-porous organic polymer film substrate that is rendered porous during manufacturing.

[0031] Fibrous webs can be made from the same (e.g. thermoplastic) organic polymer materials as just described. Fibrous webs can also be made from various organic fibers such as cotton, wool, hemp, and flax. Although inorganic fibers (e.g., fiberglass, ceramic, and metal) would typically not be utilized in medical articles, porous substrates with inorganic fibers can be used in other adhesive articles. In some embodiments, the fibrous webs comprise nylon, polyolefin, or cellulose acetate. Fibrous webs come in many forms including, e.g., woven webs, non-woven webs, knits, scrims, and meshes.

[0032] In other embodiments, the porous substrate is an apertured organic polymer film. Apertures may be formed in the organic polymer film using as suitable technique such as die punching, as described for example in KR10-2251386. The apertures can be formed before or after applying a layer of a polydiorganosiloxane composition to the organic polymer film. The apertures can contribute to the moisture vapor permeability of the film.

[0033] In some embodiments, the organic polymer film comprises a film material that has high moisture vapor permeability (without the apertures). Suitable films include (e.g. thermoplastic) polyurethane films such as available under the trade designation PELLETHANE or ESTANE from Lubrizol, Brecksville, Ohio; elastomeric polyesters such as available under the trade designation HYTREL from El. duPont deNemours & Co., Wilmington, Del.; and polyether block amides such as available under the trade designation PEB AX from Elf Altochem North America, Philadelphia, Pa. Other useful films are those described in U.S. Pat. No. 4,499,896 (Heinecke); U.S. Pat. No. 4,598,004 (Heinecke); and U.S. Pat. No. 5,849,325 (Heinecke et al). Typically, the film has a higher tensile strength and lower elongation than the crosslinked layer of the polydiorganosiloxane composition and thus can provide reinforcement and improve web handling. In some embodiments, the film has a maximum tensile strength (ASTM D 412) of at least 20, 30 or 40 MPa and typically no greater than 60, 50 or 40 MPa. In some embodiments, the film has a maximum elongation (ASTM D 412) of at least 100, 200 or 300, 400, or 500% and typically no greater than 1000, 750, or 500%. In some embodiments, the thickness of the film is at least 25, 50, 75 microns. In some embodiments, the thickness of the film is no greater than 200, 150, or 100 microns. The apertured film may have a lower tensile strength and higher elongation as compared to the same film without apertures. The (e.g. fibrous) porous substrate may have a basis weight of at least 15, 20, 25, 30, 35, 40, 45 or 50 g / m2. The (e.g. fibrous) porous substrate typically has a basis weight of no greater than 200, 150, or 100 g / m2. In some embodiments, the open area (as can be determined by the basis weight and density of the material) is at least 10, 20, 30, 40, 50, 60, or 70%. The thickness of the (e.g. fibrous) porous substrate is typically at least 0.05 mm (50 microns), 0.10 mm (100 microns) or 0.15 mm (150 microns). In some embodiments, the thickness of the (e.g. fibrous) substrate is no greater than 0.5 mm (500 microns), 0.4 mm, 0.3 mm, or 0.2 mm. The strand count of the fibrous porous substrate is typically at least 5, 10, 15, 20, or 25 strands per inch (2.54 cm). In some embodiments, the strand count of the fibrous porous substrate is no greater than 150, 100, 75, or 50 strands per inch (2.54 cm). The fibrous porous substrate may become compressed during manufacturing resulting in a greater basis weight and lower thickness in the article.

[0034] Illustrative fibrous porous substrate are commercially available from Industrial Netting (e.g. WN0100 and WN0200), Bedford Weaving Inc, ANCI, and Tessitura A. Ghiringhelli & C.S.p.A., Azzate, Italy. Physical properties of some illustrative fibrous webs are as follows:

[0035] Method of Making

[0036] The method of making an adhesive article generally comprises providing a layer of a (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition on a support, such as a release liner or organic polymer film. The layer of polydiorganosiloxane composition further comprises a porous substrate at the first major surface, at the opposing, major surface, or embedded within the layer of polydiorganosiloxane composition.

[0037] In some embodiments, a layer of (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition is applied to a porous substrate, such as fibrous web or apertured organic polymer film. This embodiment optionally comprises forming apertures through the porous substrate and the crosslinked layer(s) of nonfunctionalized polydiorganosiloxane composition.

[0038] Alternatively, a layer of (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition is applied to a non-porous substrate, such as an organic polymer film. This method further comprises forming apertures through the fibrous web or organic film substrate and the crosslinked layer(s) of nonfunctionalized polydiorganosiloxane composition.

[0039] In typical embodiments, the (e.g. porous) substrate is embedded within the polydiorganosiloxane composition, as depicted in FIG.1. This can be prepared by coating the release liner 140 with a first layer of (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition 120 A, applying the (e.g. porous) substrate 180 to first layer 120A, and coating a second layer of (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition 120B to the (e.g. porous) substrate 180 (and underlying layer 120A). It is also contemplated that the first layer of (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition 120A may be at least partially crosslinked prior to applying the second layer 120B. In FIG. 1, the (e.g. porous) substrate 180 is depicted as being disposed in the middle of the total thickness of polydiorganosiloxane composition (i.e. 120A together with 120B). In other words, about 50 wt.% of the polydiorganosiloxane composition is disposed on both major surfaces of the (e.g. porous) substrate 180. However, the weight ratio of polydiorganosiloxane composition of first layer 120A to second layer 120B can vary from 9: 1 to 1 :9. In some embodiments, it is favored for the first layer 120A to be thicker than the second layer 120B. In this embodiment, the weight ratio of polydiorganosiloxane composition of first layer 120A to second layer 120B may be greater than 1: 1 such at 1.5:1, 2: 1, 2.5: 1, 3 : 1, 3.5:1, 4: 1, or 5: l.

[0040] In another embodiment, the (e.g. porous) substrate 280 is disposed on the (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition 220 after applying the polydiorganosiloxane composition to the release liner support 240, such as illustrated in FIG. 2. In one embodiment, the porous substrate may have lower porosity such that the polydiorganosiloxane composition 220 does not significantly penetrate the porous substrate thereby providing low tack at first major surface 221. In this embodiment, the porous substrate may have less than 50, 40, 30, 20 or 10% open space.

[0041] In another embodiment, the (e.g. porous) substrate 380 is disposed on the release liner 380 prior to providing the (e.g. uncrosslinked or partially crosslinked) polydiorganosiloxane composition 320 on the release liner support, as depicted in FIG.3. In this embodiment, the porous substrate is sufficiently porous such that the polydiorganosiloxane composition penetrates the porous substrate thereby providing sufficient tack at first major surface 321. In one embodiment, the porous substrate typically has greater than 50, 60, 70% open space. However, for compression wrap articles, the porous substate may have a lower amount of open space. In some embodiments, the porous substrate may be first coated with a lower viscosity polydiorganosiloxane (e.g. less than 100,000 centistokes (cSt) and a higher viscosity (at least 500,000 or 1,000,000 centistokes) is applied to the coated porous substrate.

[0042] The layer of polydiorganosiloxane composition has a first major surface proximate the release liner support and an opposing second major surface. The method comprises exposing the opposing second major surface of the layer of the polydiorganosiloxane composition to radiation thereby crosslinking the layer of the polydiorganosiloxane composition.

[0043] The uncured polydiorganosiloxane composition may be applied to one release liner or (e.g. porous) substrate, with no substrate on the opposite surface (“open face”). Alternatively, the uncured polydiorganosiloxane composition and (e.g. porous) substrate may be disposed between two release liners during curing. Generally, the chamber is inerted (e.g., the oxy gen-containing room air is replaced with an inert gas, e.g., nitrogen) while the samples are e-beam crosslinked, particularly when open-face crosslinking. In some embodiments, the polydiorganosiloxane composition is crosslinked while in contact with a first release liner. After crosslinking, the pressure sensitive adhesive surface may be contacted with a second release liner and the first release liner is removed. In some embodiments, the method further comprises winding the crosslinked layer of the polydiorganosiloxane composition into a roll (e.g. tape).

[0044] Various release liners are known and commercially available. The release liners may comprise a polyester terephthalate support film and a release coating. Other support films for release coatings include polyolefins (e.g. polyethylene, polypropylene), and paper. In some embodiments, the release coating may be a fluorosilicone material. Release coatings that are free of silicone materials and / or fluorinated materials have also been described for use with polydiorganosiloxane adhesive.

[0045] Release liners are often characterized as having light, medium, or heavy release based on the peel force required to remove the pressure sensitive adhesive of the adhesive article from the release liner. This can be measured according to EN ISO 29862, Annex B (Self-adhesive tapes - Measurement of peel adhesion from a surface at an angle of 90°) using a SP-2100 peel tester from IMass, Inc. equipped with a lOlbf load cell and a peel rate of 30 cm / min. When a heavy release is desired, the peel force required to remove the pressure sensitive adhesive of the adhesive article from the release liner may be at least 40 g / inch (2.54 nm) or greater. When a light release is desired, the peel force required to remove the pressure sensitive adhesive of the adhesive article from the release liner may be less than 10 or 5 g / inch (2.54 nm). When a medium release is desired, the peel force required to remove the pressure sensitive adhesive of the adhesive article from the release liner may be greater than 10 and less than 40 g / inch (2.54 nm).

[0046] Various release liners are commercially available including release liners from Siliconature Spa (Godega di Sant'Urbano, Italy), under the trade designation “SILFLU”; and from Toray as the trade designation Cerapeel™’, POLYSILK™ silicone release liners from Loparex International B.V. (Apeldoom, The Netherlands), 3M™ Scotchpak™ 9741 release liner from 3M Company (St Paul, MN), and perfluorinated release chemistries as disclosed in US 4,472,480.

[0047] In typical embodiments, a thicker layer of the same polydiorganosiloxane composition is crosslinked from one side providing a crosslink gradient wherein one surface is a pressure sensitive adhesive and the opposing surface is a film backing. When the opposing surface of the crosslinked polydiorganosiloxane composition is a film backing, the article may lack other fdm backing materials such as polyurethane film backings.

[0048] However, it is also contemplated that the polydiorganosiloxane layer may be formed by coating more than one layer of the same polydiorganosiloxane composition. Further, the polydiorganosiloxane composition may be exposed to more than one pass of radiation or (e.g. different intensities of) radiation from both sides. The thickness and crosslinking conditions are selected such that the first major surface (proximate the substrate) forms a pressure sensitive adhesive and the opposing second major surface (closer to the radiant energy source) forms a film backing.

[0049] The total thickness of the polydiorganosiloxane layer is typically at least 250 microns. The thickness of the polydiorganosiloxane layer is typically no greater than 1000, 900, 800, or 700 microns. In some embodiments, the thickness is no greater than 650, 600, 550, 500, 450, 400, 350, 300, or 250 microns.

[0050] In some embodiments, the polydiorganosiloxane composition may be crosslinked through exposure to E-beam irradiation. In some embodiments, the coating may be crosslinked through exposure to gamma irradiation. In some embodiments, a combination of electron beam crosslinking and gamma ray crosslinking may be used. For example, in some embodiments, the coating may be partially crosslinked by exposure to electron beam irradiation. Subsequently, the coating may be further crosslinked by gamma irradiation.

[0051] Commercially available electron beam generating equipment is available such as a Model CB- 300 electron beam generating apparatus (available from Energy Sciences, Inc. (Wilmington, MA), also described in US 8,541,481. Commercially available gamma irradiation equipment includes equipment often used for gamma irradiation sterilization of products for medical applications. In some embodiments, such equipment may be used to crosslink, or partially crosslink the gentle to skin adhesives of the present disclosure. In some embodiments, such crosslinking may occur simultaneously with a sterilization process for a semi-finished or finished product, for example a tape or wound dressing.

[0052] In some embodiments, the polydiorganosiloxane material is exposed to E-beam radiation having a voltage of at least 200, 250, or 300 kV. The voltage of E-beam radiation is typically no greater than 500, 450, 400, 350, or 300 kV. The total dosage of (E-beam) radiation is typically at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 MRad. In some embodiments, the total dosage of (E-beam) radiation is typically no greater than 25 or 20 MRads. The intensity and total exposure is based on the electron beam generating apparatus and the time of exposure. It is appreciated that in the present invention, the first major surface and second opposing major surface of the polydiorganosiloxane layer receive different dosages of (E-beam) radiation.

[0053] Physical Properties of the Crosslinked Polydiorganosiloxane Composition

[0054] In some embodiments, the pressure sensitive adhesive of the first major surface has a tack of at least 5, 10, 15, 20, 25, 30, 35 40, 45, 50, 55, 60, 65, 70, 75, or 80 grams force. In some embodiments, the pressure sensitive adhesive of the first major surface has a tack no greater than 120, 110, or 100 grams force. In some embodiments, the pressure sensitive adhesive of the first major surface has a tack no greater than 75, 50, or 25 grams force. In some embodiments, the pressure sensitive adhesive of the first major surface has a tack no greater than 15, 10, or 5 grams force. In some embodiments, the film backing of the second major surface has a tack of less than 30, 25, 20, 15, 10, or 5 grams force.

[0055] In some embodiments, the pressure sensitive adhesive of the first major surface has a greater tack than the film backing of the second major surface. The difference in tack may be at least 25, 50, 75, 100, 150 grams force or greater. In other embodiments, the pressure sensitive adhesive of the first major surface has about the same tack than the film backing of the second major surface (i.e. within 10% of the average tack value).

[0056] In some embodiments, the crosslinked polydiorganosiloxane layer has tensile modulus of at least 0.10, 0.15, or 0.2 N / inch (2.54 cm). In some embodiments, the crosslinked polydiorganosiloxane layer has a tensile modulus of no greater than 0.4, 0.3, or 0.2 N / inch. In some embodiments, the crosslinked polydiorganosiloxane layer has a maximum tensile strength of at least 1, 1.5, 2, or 2.5 N / inch (2.54 cm). In some embodiments, the crosslinked polydiorganosiloxane layer has a maximum tensile strength of no greater than 4, 4.5, 3, 3.5, or 2 N / inch. In some embodiments, the crosslinked polydiorganosiloxane layer has a maximum elongation of at least 100, 150, 200, or 350%. In some embodiments, the crosslinked polydiorganosiloxane layer has a maximum elongation of no greater than 500, 400, or 300%.

[0057] The peel adhesion to biological substrates such as human skin is known to be highly variable. Skin type, location on the body, and other factors can affect results. Generally, average values of peel adhesion from skin are subject to large standard deviations. In some embodiments, the average peel adhesion for human skin may be less than 200 gm / 2.54 cm, and in some embodiments, less than 100 gm / 2.54 cm.

[0058] Articles

[0059] In many embodiments, an (e.g. medical) adhesive article comprises a crosslinked layer of a polydiorganosiloxane composition having two major surfaces - a first major surface (proximate to a release liner during manufacturing) comprising a pressure sensitive adhesive and a second major surface comprising a fdm backing. The pressure sensitive adhesive and film backing comprise the same polydiorganosiloxane composition and the film backing comprises greater crosslinking than the pressure sensitive adhesive.

[0060] In some embodiments, a second release liner is in contact with a film backing surface.

[0061] In another embodiment, an adhesive (e.g. tape) article may comprise the crosslinked layer of a polydiorganosiloxane composition in the absence of release liners. The adhesive (e.g. tape) article may be wound upon itself in a roll such that backing surface is in contact with pressure sensitive adhesive surface.

[0062] In some embodiments, the crosslinked layer of the polydiorganosiloxane composition is suitable for medical articles such as medical tapes, bandages, wound dressings, IV site dressings, compression wraps, surgical drapes, a prosthesis, an ostomy or stoma pouch, a buccal patch, or a transdermal patch. In some embodiments, the crosslinked layer of the polydiorganosiloxane composition may also be useful for other articles including dentures and hairpieces.

[0063] In some embodiments, the crosslinked layer of the polydiorganosiloxane composition is suitable for contact to skin or other tissue of humans and / or animals.

[0064] Additional Components

[0065] The (e.g. medical) adhesive article may comprise various additional components as known in the art. Such additional components are optional with respect to the broadest embodiments of the invention, yet may be preferred for some medical articles.

[0066] In some embodiments, when the adhesive article is a wound dressing, the article may further comprise an absorbent pad, such as described in US2019 / 0231604; incorporated herein by reference.

[0067] The absorbent pad is typically disposed at a central portion of the pressure sensitive adhesive surface, such that there is adhesive on opposing sides or the pressure sensitive adhesive surrounds the absorbent pad.

[0068] The absorbent pad can be made of one or more layers, and each layer can be made of one or more absorbent materials. Preferred absorbent pads are relatively flexible. Flexibility allows for a medical article incorporating the absorbent pad to be easily applied to a bendable portion of a body, such as a joint, etc. The absorbent pad can be slit at one of more locations to provide additional flexibility. In some embodiments, the absorbent pad may be translucent or transparent, thus allowing for visual inspection of the wound without removal of the wound dressing.

[0069] The absorbent pad can be made of synthetic or natural materials and may include, but is not limited to, woven or nonwoven materials (e.g., woven or nonwoven cotton or rayon), hydrocolloids (e.g., pectin, gelatin, carboxymethylcellulose (CMC), cross-linked carboxymethylcellulose (X-link CMC), cross-linked polyacrylic acid (PAA) and the hydrocolloids described in U.S. Pat. Nos. 5,622,711 and 5,633,010), polymer gels (e.g., hydrogels), foams, collagens, hydrofibers, alginates, and combinations thereof. In some embodiments, the absorbent pad may include a polymeric fabric, a polymeric foam, and combinations thereof. For example, the polymeric fabric may be a nonwoven and the polymeric foam may be the foam used in the TEGADERM foam adhesive dressing available from 3M Company, St. Paul, Minn. In certain embodiments, the polymeric foam is a polymethane foam. The absorbent pad may optionally include other components, including one or more active agents, such as pharmacologically active agents, as further described in US2019 / 0231604. Examples

[0070] Materials Used in the Examples

[0071] 100% Silicone Oil A was used as the polydiorganosiloxane composition for all the examples except for Examples 7 and 16. The polydiorganosiloxane composition of Example 7 contained 94 wt.% Silicone Oil A and 6 wt.% Silicone Tackifying Resin. The polydiorganosiloxane composition of Example 16 contained 100% Silicone Oil B. The polydiorganosiloxane composition was coated onto a release liner (50 micron polyethylene terephthalate film comprising a release coating) using various method described below.

[0072] The following porous substrates were used in the examples:

[0073] WN0100 and WN0200 are nylon meshes available from Industrial Netting with open area of 38 and 44% respectively.

[0074] Cellulose acetate fabrics were obtained from Bedford and TAG, including both high and low density versions from TAG.

[0075] Oaf S8520FM is a cross laminated polyolefin open mesh from ANCI Inc with an open area of up to 70%, larger than any of the other porous substrates used. This large open area is conducive to formation of apertures extending through the entire article via method 4 below.

[0076] Fabrication of Examples of Table 1:

[0077] The polydiorganosiloxane composition was coated onto both sides of the porous substrate using one of the following methods:

[0078] Method 1 -applying a layer of the polydiorganosiloxane composition on a release liner, placing the porous substrate on top of the layer of the polydiorganosiloxane composition, applying a second layer of the polydiorganosiloxane composition on top of the porous substrate, placing a second release liner on top of the second polydiorganosiloxane layer, and pressing the assembled layers between the release liners using a Carver press with metal shim spacers around the edge of the press (Examples 1-2), Method 2 - applying a layer of the polydiorganosiloxane composition on a release liner, placing the porous substrate on top of the layer of the polydiorganosiloxane composition, applying a second layer of the polydiorganosiloxane composition on top of the porous substrate, placing a second release liner on top of the second polydiorganosiloxane layer, and pulling the assembled layers through a knife coater set to a 24 mil gap (Examples 3-7), or

[0079] Method 3 - coating a layer of the polydiorganosiloxane composition onto a release liner by pulling through a knife coater set to an 8 mil gap and manually laminating two such polydiorganosiloxane layers, one to each side of the porous substrate (Examples 8-15).

[0080] Method 4 - applying a layer of the polydiorganosiloxane composition on a release liner, placing the porous substrate on top of the layer of the polydiorganosiloxane composition, applying a second layer of the polydiorganosiloxane composition on top of the porous substrate, placing a second release liner on top of the second polydiorganosiloxane layer, and (e.g. manually) laminating the assembled layers with a hand roller. Then, both release liners were removed, and the porous substrate coated with polydiorganosiloxane was transferred to a fresh set of release liners, leaving openings in the polydiorganosiloxane layer corresponding to the openings in the porous substrate (Example 16)

[0081] All examples were passed through an e-beam chamber with the release liner facing up at a voltage of 300 kV with the doses listed in Table 1. Thus, the layer of the polydiorganosiloxane composition was cured through the release liner.

[0082] Examples 1-2 were perforated after e-beam curing using a die designed to cut a square pattern of holes with 2 mm diameter and 4.5 mm center-to-center distance.

[0083] Probe tack test:

[0084] A Texture Analyzer (Stable Micro Systems) was used to perform the probe tack test. A hemispherical stainless steel probe with a radius of 6 mm was pushed into the sample at a speed of 1 mm / s until a force of 50 g was reached. The probe was removed from the sample at a speed of 0.1 mm / s and the tack was recorded as the maximum force during removal in grams. Measurements were performed on both major surfaces (i.e. the first major surface proximate the release liner and the second opposing surface that was closest to the e-beam source during crosslinking.

[0085] Table 1. Silicone (e.g. wound contact layer) examples.

Claims

What is claimed is:

1. An adhesive article comprising: a layer of a crosslinked nonfunctionalized polydiorganosiloxane adhesive composition having a first major surface, second opposing major surface, and a thickness of at least 250 microns; and a porous substrate proximate the first major surface, proximate the second major surface, embedded within the layer, or a combination thereof.

2. The adhesive article of claim 1 wherein the nonfunctionalized polydiorganosiloxane has the formulawherein Rl, R2, R3, and R4 are independently selected from the group consisting of an alkyl group and an aryl group, each R5 is an alkyl group.

3. The adhesive article of claim 2 wherein R5 is methyl.

4. The adhesive article of claims 2-3 wherein Rl, R2, R3, and R4 are methyl.

5. The adhesive article of claims 1-4 wherein the polydiorganosiloxane adhesive composition is free of platinum group metal catalysts.

6. The adhesive article of claims 1-5 wherein the polydiorganosiloxane composition has a viscosity of at least 50,000; 100,000; 250,000; 500,000; 750,000; or 1,000,000 mm2 / sec before curing.

7. The adhesive article of claims 1-6 wherein the layer of a crosslinked nonfunctionalized polydiorganosiloxane adhesive composition further comprises a tackifier.

8. The adhesive article of claims 1-7 wherein the layer of crosslinked nonfunctionalized polydiorganosiloxane composition comprises a single layer or multiple layers of the same or different composition.

9. The adhesive article of claims 1-8 wherein the first major surface is disposed on a release liner.

10. The adhesive article of claim 9 wherein the pressure sensitive adhesive of the first major surface has a tack of at least 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 grams force.

11. The adhesive article of claims 1-10 wherein the second major opposing surface is a film backing.

12. The adhesive article of claim 11 wherein the film backing of the second major surface has a tack of less than 30, 25, 20, 15, 10, or 5 grams force.

13. The adhesive article of claims 1-12 wherein the porous substrate is a fibrous web or apertured film.

14. The adhesive article of claims 1-13 wherein the article comprises a plurality of apertures that extend through the porous substrate and layer of crosslinked nonfunctionalized polydiorganosiloxane adhesive composition.

15. An adhesive article comprising: a layer of a crosslinked nonfunctionalized polydiorganosiloxane adhesive composition having a first major surface, second opposing major surface; and an organic polymeric film or fibrous web proximate the first major surface, proximate the second major surface, embedded within the layer, or a combination thereof; wherein the article comprises a plurality of apertures that extend through the organic polymeric film or fibrous web and layer of crosslinked nonfunctionalized polydiorganosiloxane adhesive composition.

16. The adhesive article of claim 15 wherein the medical article is a medical tape, bandage, dressing, compression wrap.

17. A method of use for an adhesive article comprising providing the adhesive article of claims 15-16 and contacting the pressure sensitive adhesive to skin or a wound.

18. A method of making an adhesive article comprising: a) applying a layer of nonfunctionalized polydiorganosiloxane adhesive composition to a release liner support; b) providing a porous substrate on the release liner support before or after applying the layer of nonfunctionalized polydiorganosiloxane adhesive composition to the release liner support; c) optionally applying a second layer of nonfunctionalized polydiorganosiloxane adhesive to the porous substrate, wherein the total thickness of the nonfunctionalized polydiorganosiloxane adhesive is at least 250 microns;d) exposing the layer(s) of nonfunctionalized polydiorganosiloxane composition to radiation thereby crosslinking the layer(s) of the polydiorganosiloxane composition.

19. The method of claim 18 further comprising forming apertures through the porous substrate and the crosslinked layer(s) of nonfunctionalized polydiorganosiloxane composition.

20. A method of making an adhesive article comprising: a) applying a layer of nonfunctionalized polydiorganosiloxane adhesive composition between a release liner support and an organic polymer fdm or fibrous web; c) optionally applying a second layer of nonfunctionalized polydiorganosiloxane adhesive to the organic polymer film; d) exposing the layer(s) of nonfunctionalized polydiorganosiloxane composition to radiation thereby crosslinking the layer(s) of the polydiorganosiloxane composition; and forming apertures through the fibrous web or organic film substrate and the crosslinked layer(s) of nonfunctionalized polydiorganosiloxane composition.

21. The method of claims 18-20 further characterized by claims 2-16.

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