WO2025094156A1 - Method of making polydiorganosiloxane adhesive with film backing and articles - Google Patents

Abstract

A method of making a (e.g. medical) adhesive article is described comprising: a) providing a layer of a polydiorganosiloxane composition on a (e.g. release liner) substrate wherein the layer has a first major surface proximate the substrate and an opposing second major surface; and b) exposing the opposing second major surface of the layer of the polydiorganosiloxane composition to radiation thereby curing the layer of the polydiorganosiloxane composition such that first major surface is a pressure sensitive adhesive and the opposing second major surface is a film backing. Adhesive (e.g. medical) articles and methods of use are also described.

Description

METHOD OF MAKING POLYDIORGANOSILOXANE ADHESIVE WITH FILM BACKING

AND ARTICLES

Summary

In one embodiment, a method of making an adhesive article is described comprising: a) providing a layer of a polydiorganosiloxane composition on a substrate wherein the layer has a first major surface proximate the substrate and an opposing second major surface; andb) exposing the opposing second major surface of the layer of the polydiorganosiloxane composition to radiation thereby curing the layer of the polydiorganosiloxane composition such that first major surface is a pressure sensitive adhesive and the opposing second major surface is a film backing. In some embodiments, the substrate is a first release liner.

In another embodiment, an adhesive article is described comprising a layer of a polydiorganosiloxane composition having two major surfaces, a first major surface comprising a pressures sensitive adhesive and a second major surface comprising a film backing; wherein the pressure sensitive adhesive and film backing comprise the same polydioorganosiloxane composition and the film backing comprises greater crosslinking than the pressure sensitive adhesive.

In some embodiments, the adhesive article is suitable for use as a medical article. Illustrative articles include for example medical tapes, bandages, wound dressings, compression wraps.

In another embodiment, a method of use for an adhesive article is described comprising providing an article as described herein and contacting the pressure sensitive adhesive to skin.

Brief Description of the Drawings

FIG. 1 is a schematic side view of an embodiment of an article 10 with a cured silicone adhesive 16 disposed on release liner 12.

Written Description

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 skin. The combination of relatively low adhesive strength and moderate tack make silicone gels suitable for gentle to skin adhesive applications.

Crosslinked siloxane networks can be formed from either functional or 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. 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.

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).

In some embodiments, the nonfunctionalized poly diorganosiloxane 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.

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 poly diorganosiloxane material” is one in which the Rl, R2, R3, R4, and R5 groups are nonfunctional groups.

Generally, functional silicone systems include specific reactive groups attached to the polysiloxane backbone of the starting material (for example, hydrogen, hydroxyl, vinyl, allyl, or acrylic groups). As used herein, a “functionalized poly diorganosiloxane material” is one in which at least one of the R-groups of Formula 2 is a functional group.

In some embodiments, a functional poly diorganosiloxane material is one is which at least 2 of the R-groups are functional groups. Generally, the R-groups of Formula 2 may be independently selected. In some embodiments, at least one lunctional group is selected from the group consisting of a hydride group, a hydroxy group, an alkoxy group, a vinyl group, an epoxy group, and an acrylate group.

In addition to functional R-groups, the R-groups may be nonfunctional groups, e.g., alkyl or aryl groups, including halogenated (e.g., fluorinated) alky and aryl groups. In some embodiments, the functionalized poly diorganosiloxane materials may be branched. For example, one or more of the R groups may be a linear or branched siloxane with functional and/or non-functional substituents.

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) polydiorganosiloxanes are preferred. In some embodiments, the 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.

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 curing using radiation, typically electron beam (E-beam) or gamma irradiation. Generally, any known additives useful in the formulation of adhesives may also be included.

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.

Suitable silicate tackifying resins include those resins composed of the following structural units M (i.e., monovalent R^SiO j/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.

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 HOSiC>3/2 units (i.e., "TOH units), thereby accounting for some silicon-bonded hydroxyl content of the silicate tackifying resin.

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.

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 Coming (e.g., DC 2-7066), Momentive Performance Materials (e.g., SR545 and SR1000), and Wacker Chemie AG (e.g., BELSIL TMS-803).

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 fO wt.%. in other embodiments, the amount of (e.g. silicate) tackifying is less than 5, 4, 3, 2, or 1 wt.% (e.g. zero).

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 polyethers, hydrophilic polymers and rheology modifiers. Hydrophilic additives used to improve adhesion, particularly to wet surfaces, include polymers such as polyethylene oxide) polymers, polypropylene oxide) polymers and copolymers of polyethylene oxide and propylene oxide), acrylic acid polymers, hydroxyethyl cellulose polymers, carboxy ethyl cellulose, silicone polyether copolymers, such as copolymers of poly(ethylene oxide) and polydiorganosiloxane and copolymers of polypropylene oxide) and polydiorganosiloxane, and blends thereof. The polydiorganosiloxane composition may comprise various combinations of additives.

In some embodiments, the polydiorgansiloxane 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 polydiorgansiloxane composition comprises less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 wt.% of fillers and/or additives. The poly siloxane 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 cured. For example, in some embodiments, the various components may be pre-blended using common equipment such as mixers, blenders, mills, extmders, and the like.

In some embodiments, the materials may be dissolved in a solvent, coated, and dried prior to curing. 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.

Method of Marking

The method of making an adhesive article generally comprises providing a layer of a polydiorganosiloxane composition on a substrate. The layer has a first major surface proximate the substrate and an opposing second major surface. The method comprises exposing the opposing second major surface of the layer of the polydiorganosioxane composition to radiation thereby curing the layer of the polydiorganosiloxane composition.

In some embodiments, the substrate is a support film, such as a polyester terephthalate support film. In typical embodiments, the substrate is a (e.g. first) release liner.

In some embodiments, the uncured polydiorganosioxane composition may be applied to one release liner, with no substrate on the opposite surface (“open face”). 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 cured, particularly when open-face curing. In some embodiments, the polydiorganosiloxane composition is cured while in contact with a first release liner. After curing, the pressure sensitive adhesive surface is contacted with a second release liner and the first release liner is removed. In some embodiments, the method further comprises winding the cured layer of the polydiorganosiloxane composition into a roll (e.g. tape).

Various release liners are known and commercially available. The release liners may comprise a polyester terephthalate support film and a release coating. 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.

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).

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.

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

The thickness and curing 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.

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.

When the polydiorganosiloxane composition consists of non-reactive silicone oil having a viscosity of about 1,000,000 mm²/s., the thickness of the layer is preferably less than 630, 600, or 575 microns. At thicknesses of 630 microns, the silicone oil does not sufficiently cure at an E-beam dosage of 10-15 MRad. However, it is surmised that higher thickness can be obtained by coating and curing more than one layer.

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

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 cure, or partially cure the gentle to skin adhesives of the present disclosure. In some embodiments, such curing may occur simultaneously with a sterilization process for a semi-finished or finished product, for example a tape or wound dressing.

In some embodiments, the polydiorganoxiloxane 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 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.

Physical Properties of the Cured Polydiorganosiloxane Composition

In some embodiments, the pressure sensitive adhesive of the first major surface has a tack of at least 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 film backing of the second major surface has a tack of less than 30, 25, 20, 15, or 10 grams force.

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

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.

Articles

With reference to FIG. 1, illustrative (e.g. medical) adhesive article comprises a cured layer of a polydiorganosiloxane composition 16 having two major surfaces, a first major surface 17 (proximate release liner 12 during manufacturing) comprising a pressures sensitive adhesive and a second major surface 15 comprising a film backing. 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. The pressure sensitive adhesive and film backing typically comprise the same poly dioorgano siloxane composition and the film backing comprises greater crosslinking than the pressure sensitive adhesive.

In some embodiments, a second release liner is in contact with film backing surface 15.

In another embodiment, an adhesive (e.g. tape) article may comprises the cured layer of a polydiorganosiloxane composition 16 in the absence of release liners. The adhesive (e.g. tape) article is wound upon itself in a roll such that backing surface 15 is in contact with pressure sensitive adhesive surface 17.

In some embodiments, the cured 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 cured layer of the polydiorganosiloxane composition may also be useful for other articles including dentures and hairpieces.

In some embodiments, the cured layer of the polydiorganosiloxane composition is suitable for contact to skin or other tissue (e.g. wound) of humans and/or animals.

Additional Components

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.

In some embodiments, the cured layer of the polydiorganosiloxane composition may further comprise a porous reinforcement layer such as a fibrous web, apertured fdm, or scrim. The fibrous web may be nonwoven, woven or knit. When present, such porous reinforcement layer is typically embedded within the cured layer of the polydiorganosiloxane composition. This is typically accomplished by applying a first layer of polydiorganosiloxane composition to a (e.g. release liner) substrate, applying the porous reinforcement layer to the first layer, and then applying a second layer of the polydiorganosiloxane composition to the reinforcement layer. 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.

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.

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.

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 polyurethane 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.

In some embodiments, a portion of the pressure sensitive adhesive surface of the (e.g. medical) article may comprise a facing layer. The facing layer is preferably soft, flexible, conformable, nonirritating and non-sensitizing. The facing layer may adhered directly to the wound site or be composed of a material that minimizes or prevents attachment to the wound site. The facing layer is preferably liquid permeable and can be made from a liquid permeable material and/or be applied discontinuously (e.g., pattern coated, perforated or slit) so that liquid or exudate from a wound can pass through the facing layer to the absorbent layer.

In one embodiment, the facing layer may be in the form of moisture vapor permeable films, perforated films, woven, non-woven or knit webs or scrims. It is typically preferred that the medical articles be transparent so that the wound site to which they are applied can be viewed through the wound dressing. Preferred films for use as facing layer that allow visual inspection of the wound site include polyurethane films such as those available under the trade designation ESTANE from B.F. Goodrich, Cleveland, Ohio; elastomeric polyesters such as those available under the trade designation HYTREL from El. duPont deNemours & Co., Wilmington, Del.; and, poly ether block amides such as those available under the trade designation PEBAX from Elf Altochem North America, Philadelphia, Pa. Other useful films are those describes 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).

Examples

A polydiorganosiloxane composition consisting of Wacker™ AK 1,000,000, a linear, non- reactive PMDS with a viscosity of about 1,000,000 mm²/s. available from Wacker Chemie AG) was coated at various thicknesses as described in Table 1 onto a 50 micron polyester terephthalate substrate comprising a release coating, as previously described.

The layer of polydiorganosiloxane composition had a first major surface proximate the release liner (Side B) and an opposing second major surface (Side A). The opposing second major surface was exposed to E-Beam (280keV, 70kGy). The opposing second major surface was exposure to the Ebeam dosage indicated in the following table. The first major surface of the polydiorganosiloxane composition, proximate the release liner, was expose to about 30-40% of the E-beam dosage.

After exposure, the cured polydiorganosiloxane composition was covered with a second release liner and wound into roll.

Samples of the cured polydiorganosiloxane composition were cut such that the length of the sample was in the machine direction. The cured polydiorganosiloxane composition was evaluated according to the following Test Methods:

Tack

Tack was measured using a TA-XT Plus Texture Analyzer equipped with a 5kg load cell and a 7 mm stainless steel cylinder probe. The test sample was slit to a width of 1 inch and laminated to a brass bar with 10 mm diameter holes through it to allow for the probe to reach the adhesive face of the tape. The probe head was cleaned with n-heptane after each measurement. Test parameters: Pretest speed: 1.0 mm/sec, test speed: 0.05 mm/sec, applied force: 5 grams, contact time: 5 seconds, trigger force: 60 gram, and withdraw distance: 12 mm. Data represents the average value of three measurements per example.

Liner Release Force

Liner release force was 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. Test samples were cut to a size of linch x 10mm. The nonliner side was adhered to the surface of the test machine using a double-coated tape, and a tab of the release liner was clamped into the jaw prior to running the 90° peel test. Test parameters: Initial delay time: Isec, averaging time: 5 sec, test speed: 30cm/min. Liner release force was recorded as the average force. Data represents the average value of three measurements per example.

Tensile Force & Elongation

Tensile and elongation was measured according to EN ISO 527-3 using a ZwickRoell Z010 machine equipped with a 500N loadcell. Samples were cut to a size of 80mm x linch, and tabs of linch length on each side were placed in the jaws for running the test. Samples were measured in the direction of coating. Machine settings: Jaw separation: 50mm, test speed: lOOmm/min, preload: 0.1N. Tensile strength is reported as the maximum force, elongation is reported as the elongation value at the maximum tensile force. Data represents the average value of three measurements per example.

The test results are as follows:

Table 1

Table 2

The first major surface (that was furthest from the E-beam source) formed a pressure sensitive adhesive. The opposing second major surface (closest to the E-beam source) formed a fdm backing. Thus, the adhesive article comprised the same polydioorganosiloxane material wherein the film backing surface had greater crosslinking than the pressure sensitive adhesive surface.

Claims

What is claimed is:

1. A method of making an adhesive article comprising: a) providing a layer of a polydiorganosiloxane composition on a substrate wherein the layer has a first major surface proximate the substrate and an opposing second major surface; b) exposing the opposing second major surface of the layer of the polydiorganosiloxane composition to radiation thereby curing the layer of the polydiorganosiloxane composition such that first major surface is a pressure sensitive adhesive and the opposing second major surface is a film backing.

2. The method of claim 1 wherein the substrate is a first release liner.

3. The method of claims 1-2 wherein the method further comprises applying a second release liner to the pressure sensitive adhesive of the first major surface.

4. The method of claims 1-3 wherein the method further comprises removing the first release liner after curing the layer of the polydiorganosiloxane composition.

5. The method of claims 1-4 further comprising winding the cured layer of the polydiorganosiloxane composition into a roll (e.g. tape).

6. The method of claims 1-5 wherein the layer of the polydiorganosiloxane composition comprises a single layer or multiple layers of the same composition.

7. The method of claims 1-5 wherein the pressure sensitive adhesive of the first major surface has a tack of at least 40, 45, 50, 55, 60, 65, 70, 75, or 80 grams force.

8. The method of claims 1-6 wherein the film backing of the second major surface has a tack of less than 30, 25, 20, 15, or 10 grams force.

9. The method of claims 1-8 wherein the polydiorganosiloxane composition comprises a non-functional polydiorganosiloxane optionally further comprising tackifying resin.

10. The method of claims 1-9 wherein the polydiorganosiloxane composition has a viscosity of at least 500,000; 750,000; or 1,000,000 mm²/sec before curing.

11. The method of claims 1-10 wherein the thickness of the layer of polydiorganosiloxane composition is at least 250, 300, 350, 400, 450, or 500 microns.

12. The method of claims 1-10 wherein the opposing second major surface is exposed to at least 8 MRad of e-beam radiation and the first major (e.g. adhesive) surface is exposed to less radiation than the opposing second major surface.

13. An adhesive article comprising: a layer of a polydiorganosiloxane composition having two major surfaces, a first major surface comprising a pressures sensitive adhesive and a second major surface comprising a film backing; wherein the pressure sensitive adhesive and fdm backing comprise the same polydioorganosiloxane composition and the film backing comprises greater crosslinking than the pressure sensitive adhesive.

14. The adhesive article claim 13 wherein the layer of polydiorganosiloxane composition or major surfaces thereof are further characterized according to claims 6-11.

15. The adhesive article of claims 13-14 further comprising a release liner in contact with the first major surface comprising the pressure sensitive adhesive.

16. The adhesive article for use as a medical article.

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

18. A method of use for an adhesive article comprising providing the adhesive article of claims 13-17 and contacting the pressure sensitive adhesive to skin or a wound.