Hot-melt processable (meth)acrylate medical adhesive

Abstract

The adhesive article includes a substrate and a hot-melt processable pressure-sensitive adhesive on the substrate. The hot-melt processable pressure-sensitive adhesive is a (meth)acrylate-based copolymer that is the reaction product of a reaction mixture that does not include an acidic or basic monomer, and includes an alkyl (meth)acrylate, a hydroxyl-functional (meth)acrylate, and a photocrosslinker. The (meth)acrylate-based polymer is made in a thermoplastic package.

Description

[Technical Field]

[0001] The present disclosure relates to (meth)acrylate-based pressure-sensitive adhesives that can be used to form adhesive articles such as tapes and other medical articles useful in medical applications. [Background technology]

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

[0003] Many adhesive articles use pressure-sensitive adhesives. Pressure-sensitive adhesives are well known to those skilled in the art to have certain properties at room temperature, including (1) strong and persistent adhesion, (2) adhesion with finger pressure or less, (3) sufficient ability to hold onto the substrate, and (4) sufficient cohesion to allow clean removal from the substrate. Materials known to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelastic properties necessary to provide the desired balance of adhesion, peel adhesion, and shear strength. The polymers most commonly used to make pressure-sensitive adhesives are natural rubber, synthetic rubber (e.g., styrene / butadiene copolymer (SBR) and styrene / isoprene / styrene (SIS) block copolymers), various (meth)acrylate (e.g., acrylate and methacrylate) copolymers, and silicones.

[0004] One problem with using adhesive articles for medical applications is that removal of the adhesive article can result in trauma to the skin, which is particularly troublesome in patients with sensitive skin such as infants and the elderly, and can be exacerbated in chronic patients where adhesive articles are repeatedly applied and removed over long periods of time.

[0005] Various attempts have been made to alleviate this problem with adhesive articles. In particular, healthcare professionals utilize removal techniques to reduce skin trauma. One way to reduce trauma to the skin is to remove the adhesive article by peeling slowly at a high angle to avoid pulling on the skin. Another way to reduce trauma is to pull straight (at an angle as close to 0° as possible) if the adhesive article is stretchable, inducing a pull-off of the adhesive layer from the skin. Additionally, manufacturers of adhesive articles have developed articles that reduce skin trauma by reducing adhesion to the skin. So-called "skin-friendly adhesives" have been developed that do not significantly strip skin cells or cause significant pain when removed.

[0006] Various skin-friendly articles and dressings using skin-friendly adhesives have been described. Skin-friendly adhesives are described in U.S. Patent Application Publication No. 2011 / 0212325 (Determan et al.), which describes electron beam and gamma ray crosslinked silicone gel adhesives that may use either non-functional or functional polydiorganosiloxanes. U.S. Patent No. 4,838,253 (Brassington et al.) describes silicone gel-coated dressings. U.S. Patent No. 6,051,747 (Lindqvist et al.) describes foam absorbent dressings in which a foam dressing is coated with a layer of hydrophobic gel. Also, U.S. Pat. No. 5,891,076 (Fabo) describes a hypertrophic scar dressing including a silicone gel on the side of the dressing that contacts the user's skin and a flexible carrier sheet, the flexible carrier sheet incorporating the silicone gel so that the gel forms a continuous layer on both sides of the carrier, and U.S. Patent Application Publication No. 2010 / 0331785 (Fabo et al.) describes a dressing including a liquid-impermeable film layer coated with a skin-friendly adhesive on the side intended to adhere to the skin. Summary of the Invention

[0007] The present disclosure relates to adhesive articles having hot-melt processable (meth)acrylate-based pressure-sensitive adhesives, packaged hot-melt processable (meth)acrylate-based pressure-sensitive adhesives, and methods of making adhesive articles.

[0008] Adhesive articles are disclosed herein. In some embodiments, the article includes a substrate and a hot-melt processable pressure-sensitive adhesive disposed on at least a portion of the substrate. The hot-melt processable pressure-sensitive adhesive includes a (meth)acrylate-based copolymer that is the reaction product of a reaction mixture that is substantially free of acidic or basic monomers. The reaction mixture includes, as a polymerizable component, 70 to 96 parts by weight of a first (meth)acrylate monomer of general formula I: CH2=CR 1 -(CO)-OR 2 Formula I [In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group, and 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH2=CR 1 -(CO)-OR 3 Formula II [In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; and a copolymerizable photocrosslinker.

[0009] Also disclosed are hot-melt processable packaged adhesive compositions. In some embodiments, the packaged adhesive compositions include a hot-melt processable adhesive comprising a polymerized (meth)acrylate copolymer formed from a polymerizable pre-adhesive mixture, and packaging material. The polymerizable pre-adhesive mixture composition is substantially free of acidic or basic monomers and comprises 70 to 96 parts by weight of a first (meth)acrylate monomer of general formula I: CH2=CR1 -(CO)-OR 2 Formula I [In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group, and 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH2=CR 1 -(CO)-OR 3 Formula II [In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; a copolymerizable photocrosslinker; and at least one initiator.

[0010] Also disclosed is a method of making an adhesive article. In some embodiments, the method includes providing a substrate having a first major surface and a second major surface, providing a hot-melt processable packaged adhesive composition, hot-melt processing the packaged adhesive composition, disposing the hot-melt processed packaged adhesive composition on at least a portion of the second major surface of the substrate to form a pressure-sensitive adhesive layer, and photocrosslinking the pressure-sensitive adhesive layer. The hot-melt processable packaged adhesive composition is described above. DETAILED DESCRIPTION OF THE INVENTION

[0011] The use of adhesive products in the medical industry has been widespread and increasing for many years. However, while adhesives and adhesive articles have proven themselves to be very useful in medical applications, their use also presents challenges. Medical adhesive-related skin injury (MARSI) has a significant negative impact on patient safety. Skin injuries associated with the use of medical adhesives are a common yet often overlooked complication occurring in all care settings and across all age groups. Furthermore, treating skin injuries is costly in terms of service delivery, time, and additional treatments and supplies.

[0012] Skin damage occurs when the surface layer of the skin is removed along with the medical adhesive product, which not only affects the integrity of the skin but also causes pain and risk of infection, increases wound size and can delay healing, all of which reduce the patient's quality of life.

[0013] A medical adhesive tape can be simply defined as a pressure-sensitive adhesive and a backing that acts as a carrier for the adhesive. The U.S. Food and Drug Administration more specifically defines a medical adhesive tape or bandage as "a device intended for medical purposes consisting of a piece of fabric material or plastic coated on one side with an adhesive, which may include a surgical dressing pad that does not contain an antiseptic. The device is used to cover and protect wounds, to hold together the skin edges of a wound, to support an injured part of the body, or to fasten objects to the skin."

[0014] The pathophysiology of MARSI is only partially understood. Skin injury occurs when the adhesion of skin cells to adhesives is stronger than the adhesion of skin cells to skin cells. When adhesive strength exceeds the strength of skin cell to skin cell interactions, cohesive failure occurs within the skin cell layer.

[0015] The inherent properties of all components of the adhesive product must then be considered to address these factors that may lead to MARSI. Adhesive properties to consider include cohesion over time and corresponding bond strength, and tape / backing / dressing properties to consider include breathability, extensibility, conformability, flexibility, and strength.

[0016] 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 acrylate- and silicone-based pressure-sensitive adhesives, for skin adhesion is known in the art, and many examples are commercially available. However, some pressure-sensitive adhesives have problems that limit their use in skin adhesion. For example, skin damage may occur when removing a pressure-sensitive adhesive that exhibits strong interfacial adhesion between the adhesive and skin cells. Alternatively, if adhesion to skin is low, the pressure-sensitive adhesive may lack a useful level of holding power. In addition, some pressure-sensitive adhesives, particularly acrylate-based pressure-sensitive adhesives containing acidic or basic comonomers, may significantly lose skin adhesion when in contact with bodily fluids containing multivalent ions. Furthermore, some pressure-sensitive adhesives that are relatively stiff or incompatible with skin typically cause significant patient discomfort during use. Also, even adhesives that are measured to have low peel adhesion to skin may cause discomfort during removal, for example, if the adhesive is superficially attached around hair.

[0017] Thus, there remains a need for adhesives suitable for medical applications that have high adhesive and cohesive strength without causing skin damage upon removal. Medical adhesives also desirably maintain stable adhesive and adhesive retention (often referred to as shear strength or shear retention) during wear, even when the adhesive article comes into contact with heavy body fluids.

[0018] Among the classes of adhesive materials widely used as pressure-sensitive adhesives are (meth)acrylate-based pressure-sensitive adhesives. These materials have many desirable characteristics, including being inherently tacky and therefore not requiring the use of added tackifiers. They are typically formed by free-radical polymerization at high conversion rates, which means that little or no unpolymerized monomer remains 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. (Meth)acrylate-based pressure-sensitive adhesives are made from reaction mixtures containing acidic and basic monomers. Because these monomers tend to increase the cohesive strength of (meth)acrylate-based pressure-sensitive adhesives, acidic and basic monomers are often classified as reinforcing monomers in the adhesives field. However, acidic and basic monomers can be problematic in applications where the pressure-sensitive adhesive may come into contact with human skin, especially when the adhesive comes into contact with heavy body fluids containing multivalent ions. Therefore, it is a challenge to create (meth)acrylate-based pressure-sensitive adhesives that retain the necessary cohesive strength without including these acidic or basic reinforcing monomers.

[0019] In some applications, the necessary cohesive strength can be imparted to the pressure-sensitive adhesive by using monomers with relatively high Tg or monomers with crystalline groups. In many cases, the reaction of these monomers to form the pressure-sensitive adhesive polymer must be carried out in a solution or dispersion, and the formed adhesive polymer is delivered as a solution or dispersion. However, as noted below, the adhesive industry is moving away from the use of solvents, and there is a need for adhesives that can be made and delivered without the use of solvents.

[0020] To address the growing need for performance issues, many classes of pressure-sensitive adhesives have been created. These pressure-sensitive adhesives are often provided as solutions or solvent-containing mixtures, often containing large amounts of solvent. Upon coating or dispensing, the solvent must be removed to produce an adhesive layer. Often, the solvent is removed by using high-temperature processes, such as heating in an oven. This solvent removal process can add cost to the formed article because solvent removal requires additional steps. Not only are additional steps required, but these steps require special care, precautions, and equipment because the solvent is volatile and typically flammable. Additionally, transporting the adhesive solution can add additional costs due to the added weight of the solvent and require special pre-shipment precautions due to the presence of the solvent. Environmental concerns are also an issue with solvent-containing adhesive systems, as solvent release into the environment is likely, even with the use of solvent regeneration equipment.

[0021] Therefore, 100% solids adhesive systems have been developed. Methods used to create 100% solids adhesive layers include on-web cure systems and hot-melt processable adhesives. Each of these systems has drawbacks and advantages. In on-web cure systems, the level of residual monomer often makes them undesirable or unusable in medical applications. Difficulties also arise when solvent processing is replaced by hot-melt processing. In many cases, it is difficult to reproduce the properties of solvent-delivered adhesive layers with hot-melt delivery systems due to the strong chain orientation that can occur in adhesive layers formed by extrusion processes.

[0022] Thus, desirable, but often incompatible, characteristics desired in a medical adhesive include: high enough adhesion to adhere to skin without causing skin damage upon removal; lacking acidic or basic monomers that can cause skin damage and / or skin irritation, yet having high enough cohesive strength to be useful; high skin adhesion, but stable adhesion during wear, especially when the adhesive comes into contact with heavy body fluids; and being hot melt processable so that the use of solvents is not required.

[0023] Another challenge in using adhesive articles for medical applications is the ability of the medical adhesive to maintain sufficient adhesion to the skin during wear. Typically, skin adhesives are made with adhesives containing either acid or base comonomers (e.g., AA (acrylic acid) or ACM rubber) and a surfactant that is soluble in body fluids (e.g., Ca 2+ or CO3 2- ) significantly degrades when the adhesive is confronted with bodily fluids (e.g., sweat and / or saliva).

[0024] One attempt to provide an adhesive with stable skin adhesion upon aging involves the use of rubber-based adhesives that do not contain acid / base functional groups, as described in, for example, Japanese Patent No. 4849200. However, these rubber-based adhesives have a high rate of irritants, resulting in significantly increased skin allergies and / or skin sensitivity, and these rubber-based adhesives typically have lower moisture permeability. Another attempt to provide stable skin adhesion upon aging involves the use of non-polar acrylate adhesives, as described in U.S. Patent No. 5,886,122. However, such adhesives suffer from a lack of cohesion due to their lack of polarity, a drawback that is alleviated by higher levels of crosslinking. However, higher levels of crosslinking can cause other problems, such as reducing the adhesive strength of the adhesive.

[0025] Disclosed herein are adhesive articles, packaged adhesive compositions, and methods for making adhesive articles. The adhesive articles include hot-melt processable (meth)acrylate-based pressure-sensitive adhesives, which are made from reaction mixtures that do not contain acidic or basic monomers. The hot-melt processable pressure-sensitive adhesives are made as 100% solids compositions in packages surrounded by packaging materials, and these packages can be hot-melt processed and placed on a substrate to form the adhesive article.

[0026] Unless otherwise indicated, all numbers expressing structural dimensions, quantities, and physical properties used in the specification and claims are to be understood as modified in all instances by the term "about." Accordingly, unless specifically indicated to the contrary, the numerical parameters set forth in the above specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by those of ordinary skill in the art utilizing the teachings disclosed herein. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

[0027] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include embodiments having plural referents unless the content clearly dictates otherwise. For example, reference to a "layer" includes embodiments having one or more layers. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0028] As used herein, the term "adhesive" refers to a polymeric composition that is useful for bonding two adherends together. An example of an adhesive is a pressure-sensitive adhesive.

[0029] It is well known to those skilled in the art that pressure-sensitive adhesive compositions possess properties including: (1) aggressive and persistent tack, (2) adhesion with no more than finger pressure, (3) sufficient ability to hold down an adherend, and (4) sufficient cohesion to remove cleanly from the adherend. Materials known to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelastic properties necessary to provide the desired balance of tack, peel adhesion, and shear holding power. Achieving the right balance of properties is not a simple process.

[0030] The terms "Tg" and "glass transition temperature" are used interchangeably. If measured, Tg values ​​may be measured by differential scanning calorimetry (DSC) at a scan rate of 10°C / min unless otherwise indicated. Tg values ​​may also be measured using dynamic mechanical analysis (DMA), as described in the Examples section. Typically, Tg values ​​of copolymers are calculated using the well-known Fox equation using monomer Tg values ​​provided by the monomer supplier, as will be understood by those skilled in the art.

[0031] The term "room temperature" refers to ambient temperature, generally 20°C to 22°C, unless otherwise specified.

[0032] The term "(meth)acrylate" refers to a monomer that is an acrylic or methacrylic ester of an alcohol. Acrylate and methacrylate monomers or oligomers are collectively referred to herein as "(meth)acrylate." Polymers described as "(meth)acrylate-based" are polymers or copolymers made primarily (greater than 50% by weight) from (meth)acrylate monomers and may include additional ethylenically unsaturated monomers.

[0033] As used herein, the term "adjacent" when referring to two layers means that the two layers are in close proximity to each other with no intervening open space between them. They may be in direct contact with each other (e.g., laminated together) or there may be an intervening layer.

[0034] The terms "polymer" and "macromolecule" are used herein consistent with common usage in chemistry. Polymers and macromolecules are composed of many repeating subunits. As used herein, the term "macromolecule" is used to describe a group attached to a monomer having multiple repeating units. The term "polymer" is used to describe the resulting material formed from a polymerization reaction.

[0035] The term "alkyl" refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. An alkyl can be linear, branched, 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.

[0036] The term "aryl" refers to a monovalent group that is aromatic and carbocyclic. An aryl can have 1 to 5 rings connected to or fused to the aromatic ring. Other ring structures may be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0037] The term "alkylene" refers to a divalent group that is a radical of an alkane. Alkylene can be linear, branched, cyclic, or a combination thereof. Alkylene often has 1 to 20 carbon atoms. In some embodiments, alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of an alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms.

[0038] The term "arylene" refers to a divalent group that is carbocyclic and aromatic. The group has 1 to 5 rings that are connected, fused, or a combination thereof. The other rings may be aromatic, non-aromatic, or a combination thereof. In some embodiments, the arylene group has up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or 1 aromatic ring. For example, the arylene group may be phenylene.

[0039] The term "heteroalkylene" refers to a divalent group containing at least two alkylene groups connected by thio, oxy, or -NR-, where R is alkyl. Heteroalkylenes can be linear, branched, cyclic, substituted with alkyl groups, or combinations thereof. Some heteroalkylenes are polyoxyalkylenes in which the heteroatom is oxygen, e.g., -CH2CH2(OCH2CH2) n OCH2CH2-, etc.

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

[0041] Disclosed herein is an adhesive article suitable for use in medical applications. The article includes a substrate and a hot-melt-processable pressure-sensitive adhesive disposed on at least a portion of the substrate. The substrate has a first major surface and a second major surface. Typically, the hot-melt-processable pressure-sensitive adhesive is disposed on the first major surface of the substrate. As described below, the substrate may be a monolithic structure or a multilayer structure. In a multilayer structure, the substrate may have various coatings or layers adjacent to or present on the first or second surface of the substrate.

[0042] A wide range of substrates are suitable, including release liners and medical substrates. A release liner is a sheet material having a low-adhesion coating on at least one surface. The hot-melt-processable pressure-sensitive adhesive of the present disclosure can be disposed on a release liner to produce an article comprising a layer of pressure-sensitive adhesive on the release liner. This adhesive / release liner article can be used to make other adhesive / substrate articles by laminating the adhesive layer to a different substrate and then removing the release liner. This allows for the placement of adhesive on substrates where it would be difficult to directly place a hot-melt-processable pressure-sensitive adhesive, such as heat-sensitive substrates. The adhesive / release liner article can also be used to apply a pressure-sensitive adhesive layer to articles such as electrodes, ostomy devices, and the like.

[0043] Exemplary medical substrates include polymeric materials, plastics, natural polymeric materials (e.g., collagen, wood, cork, silk, and leather), paper, fabrics, textiles, nonwovens, metals, glass, ceramics, composites, and combinations thereof. The medical substrate may be a tape backing. Examples of suitable tape backings include breathable conformable backings onto which an adhesive is disposed. A wide range of breathable conformable backings are suitable for use in the articles of the present disclosure. Typically, breathable conformable backings include woven or knitted fabrics, nonwovens, or plastics.

[0044] In some embodiments, the breathable conformable backing comprises a highly moisture vapor permeable film backing. Examples of such backings, methods for making such films, and methods for testing their permeability are described, for example, in U.S. Patent Nos. 3,645,835 and 4,595,001. Typically, such backings are porous materials.

[0045] Generally, the backing is conformable to the anatomical surface. Thus, when applied to an anatomical surface, the backing conforms to the surface even when the surface moves. Generally, the backing is also conformable to the anatomical joint of the animal. When the joint is flexed and then returned to its unflexed position, the backing stretches to accommodate the flexion of the joint, yet is sufficiently elastic to continue to conform to the joint when the joint returns to its unflexed state.

[0046] Examples of particularly suitable backings can be found in U.S. Patent Nos. 5,088,483 and 5,160,315 and include elastomeric polyurethane, polyester, or polyether block amide films, which have a desirable combination of properties including elasticity, high moisture vapor permeability, and transparency.

[0047] The article may include additional optional layers. In some embodiments, it may be desirable to have a primer layer between the substrate surface and the pressure-sensitive adhesive layer. Typically, the primer layer includes a material commonly referred to as a "primer" or "adhesion promoter." Primers and adhesion promoters are materials that are applied as thin coatings to a surface, adhere strongly to the surface, and modify the surface's surface chemistry. Examples of suitable coating materials include polyamides, poly(meth)acrylates, chlorinated polyolefins, rubbers, chlorinated rubbers, polyurethanes, siloxanes, silanes, polyesters, epoxies, polycarbodiimides, phenolic resins, and combinations thereof. Typically, the articles of the present disclosure do not require a primer layer because, once the hot-melt-processable pressure-sensitive adhesive is disposed on the substrate surface, it tends to form strong interactions with a wide range of substrate surfaces, making a primer unnecessary.

[0048] In some embodiments, it may be desirable for the second major surface of the substrate, i.e., the surface not coated with the adhesive structure, to have a low-adhesion coating. This is particularly true when the adhesive article is supplied in the form of a tape. Many tapes are supplied as rolls, and the adhesive layer contacts the non-adhesive "back" side of the backing when unwound. This non-adhesive surface of the backing often has a low-adhesion or release coating thereon, allowing the roll to be unwound. These low-adhesion coatings are often referred to as "low-adhesion backsize" or LAB. Whether an LAB coating is necessary or desirable is governed by many factors, including the nature of the adhesive, the composition and topography of the backing, and the desired use of the tape article.

[0049] The hot-melt processable pressure-sensitive adhesives of the present disclosure comprise (meth)acrylate-based copolymers that are the reaction product of a reaction mixture that is substantially free of acidic or basic monomers. The reaction mixture typically includes, as polymerizable components, a first (meth)acrylate monomer present in a major amount, a second (meth)acrylate monomer present in a minor amount, and a copolymerizable photocrosslinker. Each of these components is described in more detail below.

[0050] The reaction mixture includes a first (meth)acrylate monomer of general formula I: CH2=CR 1 -(CO)-OR 2 Formula I In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group. 2 Alkyl (meth)acrylate monomers, where is alkyl, are particularly suitable.

[0051] The first monomer is present in the reaction mixture in a major amount, meaning that more than half of the reactive components in the reaction mixture comprise the first monomer. While the first monomer is referred to as a single material, it should be understood that the first monomer may also be a mixture of materials of the general structure of Formula I. Typically, the reaction mixture contains 70 to 96 parts by weight of the first (meth)acrylate monomer of general Formula I. The term "parts by weight" is used to describe the amount by weight of reactive material present in the mixture. This term is similar to, but should not be confused with, "weight %" or "% by weight." Typically, components add up to 100 parts by weight, and thus parts by weight are the same as % by weight, but in many embodiments, the reactive components do not add up to exactly 100 parts by weight. In these embodiments, the term parts by weight is close to, but not exactly the same as, % by weight. For example, a reactive mixture containing 70 parts by weight of Monomer 1, 30 parts by weight of Monomer 2, and 0.1 parts by weight of Monomer 3 has about 70% by weight of Monomer 1, but since the parts by weight of the monomers total more than 100, it is not accurate to use that term.

[0052] As noted above, in some embodiments, the first (meth)acrylate monomer is present in an amount of 70 to 96 parts by weight, in other embodiments, the first (meth)acrylate monomer is present in an amount of 80 to 96 parts by weight, and in still other embodiments, the first (meth)acrylate monomer is present in an amount of 90 to 96 parts by weight.

[0053] Useful alkyl (meth)acrylate monomers include monomeric acrylic or methacrylic acid esters of non-tertiary alkyl alcohols, the alkyl group of which contains from about 1 to about 14 carbon atoms, and in some embodiments from about 7 to about 9 carbon atoms, and mixtures thereof.

[0054] Suitable alkyl (meth)acrylate monomers include, but are not limited to, those selected from the group consisting of acrylic or methacrylic acid esters 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 mixtures thereof. Such monomeric acrylic or methacrylic esters are known in the art and commercially available.

[0055] Generally, it is desirable for the first monomer to have a relatively low homopolymer Tg. For this reason, in many embodiments, the first monomer often includes an acrylate monomer instead of a methacrylate monomer, since acrylates tend to have lower homopolymer Tg values ​​than their corresponding methacrylates. The homopolymer Tg is a property that defines the value of a monomer and refers to the Tg of the homopolymer of that monomer. Suppliers of acrylate and methacrylate monomers provide the homopolymer Tg value of the monomer, which can be used by those skilled in the art to determine the Tg of a copolymer with that monomer by using the Fox equation. In some embodiments, the first monomer has a homopolymer Tg of -20°C or lower.

[0056] Examples of alkyl acrylate monomers that are particularly suitable for use as the first (meth)acrylate monomer are isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isobutyl acrylate, and mixtures thereof.

[0057] The reaction mixture includes a second (meth)acrylate monomer of general formula II, CH2=CR 1 -(CO)-OR 3 Formula II In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer.

[0058] Typically, the reaction mixture comprises 4 to 30 parts by weight of the second (meth)acrylate monomer of general formula II. In some embodiments, the second (meth)acrylate monomer is present in an amount of 4 to 20 parts by weight, and in still other embodiments, the second (meth)acrylate monomer is present in an amount of 4 to 10 parts by weight.

[0059] Examples of suitable second monomers include those in which R 3 In some embodiments, the alkylene oxide group is a group of the formula -(R 4 -O-)n- repeating units [wherein R 4 is an alkyl group containing 2 to 4 carbon atoms, and n is an integer from 3 to 100.

[0060] Examples of alkyl acrylate monomers that are particularly suitable for use as the second (meth)acrylate monomer are 2-hydroxyethyl acrylate, hydroxylpropyl acrylate, 4-hydroxybutyl acrylate, and poly(ethylene glycol) acrylate.

[0061] The reaction mixture forming the (meth)acrylate copolymer also contains a copolymerizable photocrosslinker. A copolymerizable photocrosslinker is a substance containing free-radically polymerizable groups that copolymerize with the above-mentioned monomers. The copolymerizable photocrosslinker also contains photosensitive groups, which, when exposed to the right wavelength of light, typically high-intensity ultraviolet (UV) radiation, form free radicals capable of forming crosslinks in the polymer. When the (meth)acrylate polymer is formed using a photoinitiator, the photocrosslinker is not activated by light of the same wavelength as the photoinitiator. In this way, the copolymerizable photocrosslinker is incorporated into the polymer and can be thermally processed because the crosslinker is thermally stable and remains intact until activated by the appropriate wavelength of light. This allows the copolymerizable photocrosslinker to be activated until the polymer is hot-melt coated. In some embodiments, these crosslinkers are activated by ultraviolet light generated from artificial sources such as medium-pressure mercury lamps or UV black lights.

[0062] Suitable photocrosslinkers include monoethylenically unsaturated aromatic ketone comonomers that do not contain ortho-aromatic hydroxyl groups, such as those described in U.S. Patent No. 4,737,559 (Kellen et al.). Specific examples include para-acryloxybenzophenone (ABP), para-acryloxyethoxybenzophenone, para-N-(methylacryloxyethyl)-carbamoylethoxybenzophenone, para-acryloxyacetophenone, ortho-acrylamidoacetophenone, acrylated anthraquinone, and the like. ABP para-acryloxybenzophenone, also known as 4-acryloxybenzophenone, is particularly suitable.

[0063] Typically, such photocrosslinkers are used in an amount of about 0.01 to 1.0 parts by weight 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 per 100 parts by weight of total monomers present in the reaction mixture.

[0064] The monomers are selected to impart desired properties to the formed (meth)acrylate-based polymer. Because (meth)acrylate-based copolymers are pressure-sensitive adhesives, they typically have a Tg corresponding to room temperature (generally 20°C) or lower. In some embodiments, the (meth)acrylate-based copolymer has a Tg of 0°C or lower. In yet other embodiments, the (meth)acrylate-based copolymer has a Tg of -20°C or lower. Typically, as will be understood by those skilled in the adhesives art, adhesives with lower Tg tend to have a lower modulus and therefore improved wetting of highly textured surfaces, such as skin.

[0065] (Meth)acrylate copolymers can have a wide range of molecular weights. Typically, (meth)acrylate copolymers have a weight average molecular weight of 500,000 grams / mole or more. This molecular weight is particularly suitable for hot melt processing. One method for increasing the molecular weight is to incorporate polymer branching by adding both a difunctional (meth)acrylate monomer (e.g., 1,6-hexanediol diacrylate, or HDDA) and a free radical chain transfer agent (e.g., isooctylthioglycolate, or IOTG).

[0066] As described above, the reaction mixture from which the (meth)acrylate copolymer is formed contains a photocrosslinker. Typically, after the (meth)acrylate copolymer is hot-melt coated onto a substrate, the (meth)acrylate copolymer is photocrosslinked. Typically, this photocrosslinking is performed by exposing the (meth)acrylate copolymer adhesive layer to UV radiation. Photocrosslinking is performed on the coated adhesive layer to enable hot-melt processing of the polymer; if the material were crosslinked before hot-melt processing, the polymer would be difficult or impossible to hot-melt process. As described above, the photocrosslinker is selected to be thermally stable to enable hot-melt processing, and also to not activate at the same wavelength as the photoinitiator, if one is used to form the (meth)acrylate copolymer.

[0067] The pressure-sensitive adhesive layer may be of any suitable thickness depending on the desired application. In some embodiments, the thickness will be at least 10 micrometers and up to 2 millimeters, and in some embodiments, the thickness will be at least 20 micrometers and up to 1 millimeter thick. A wide range of intermediate thicknesses, such as 25 micrometers to 500 micrometers, 200 micrometers to 400 micrometers, etc., are also suitable.

[0068] In addition to the (meth)acrylate copolymer, the pressure-sensitive adhesive layer may further include one or more additives. A wide variety of additives are suitable as long as the additive does not interfere with the usefulness of the pressure-sensitive adhesive layer in medical articles. Additives can be added to the reaction mixture as long as they do not interfere with the polymerization reaction. In addition, additives can be added to the (meth)acrylate copolymer during hot-melt processing.

[0069] As described in detail below, the (meth)acrylate copolymer is typically polymerized in a package that contains the (meth)acrylate copolymer, and optionally any additives, during polymerization. Generally, these packages are placed in a hot melt extruder and pulverized to form a pressure-sensitive adhesive that is coated onto a substrate to form an adhesive article.

[0070] One artifact of this process is that the hot-melt processing of the packaging adhesive generates particles of the packaging material within the pressure-sensitive adhesive layer. Thus, in many embodiments, the pressure-sensitive adhesive further comprises particles formed from the packaging material, which is a thermoplastic polymer. A wide variety of thermoplastic polymers are suitable. Examples of suitable thermoplastic polymers include polyethylene, ethylene vinyl acetate, ethylene methyl acrylate, ethylene acrylic acid, ethylene acrylic acid ionomer, polypropylene, acrylic polymer, polyphenylene ether, polyphenylene sulfide, acrylonitrile-butadiene-styrene copolymer, polyurethane, and mixtures and blends thereof.

[0071] Examples of other suitable optional additives that can be included in the pressure-sensitive adhesive layer include tackifying resins, plasticizers, antioxidants, fillers, leveling agents, ultraviolet absorbers, hindered amine light stabilizers (HALS), oxygen inhibitors, wetting agents, rheology modifiers, defoamers, biocides, dyes, pigments, etc. All of these additives and their uses are well known in the art. It should be understood that any of these compounds can be used as long as they do not adversely affect the adhesive properties.

[0072] In many embodiments of the present disclosure, the hot-melt processable adhesive comprises a hot-melt processable packaged adhesive composition. Methods for making hot-melt processable packaged adhesive compositions are described in U.S. Patent No. 5,804,610 (Hamer et al.). The hot-melt processable packaged adhesive compositions of the present disclosure comprise a hot-melt processable adhesive comprising a polymerized (meth)acrylate-based copolymer formed from a polymerizable pre-adhesive mixture, and a packaging material. These pre-adhesive mixtures are substantially free of acidic or basic monomers.

[0073] The pre-adhesive mixture typically includes a first (meth)acrylate monomer present in a major amount, a second (meth)acrylate monomer present in a minor amount, a copolymerizable photocrosslinker, and at least one initiator. In some embodiments, the pre-adhesive composition contains other ingredients, such as a chain transfer agent and / or a difunctional (meth)acrylate. Each of these ingredients is described in more detail below.

[0074] The pre-adhesive mixture comprises a first (meth)acrylate monomer of general formula I: CH2=CR 1 -(CO)-OR 2 Formula I In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group. 2 Alkyl (meth)acrylate monomers, where is alkyl, are particularly suitable.

[0075] The first monomer is present in the pre-adhesive mixture in a major amount, meaning that more than half of the reactive components in the pre-adhesive mixture comprise the first monomer. Although the first monomer is referred to as a single material, it should be understood that the first monomer may also be a mixture of materials of the general structure of Formula I. Typically, the pre-adhesive mixture includes 70 to 96 parts by weight of the first (meth)acrylate monomer of general Formula I.

[0076] As noted above, in some embodiments, the first (meth)acrylate monomer is present in an amount of 70 to 96 parts by weight, in other embodiments, the first (meth)acrylate monomer is present in an amount of 80 to 96 parts by weight, and in still other embodiments, the first (meth)acrylate monomer is present in an amount of 90 to 96 parts by weight.

[0077] Useful alkyl (meth)acrylate monomers include monomeric acrylic or methacrylic acid esters of non-tertiary alkyl alcohols, the alkyl group of which contains from about 1 to about 14 carbon atoms, and in some embodiments from about 7 to about 9 carbon atoms, and mixtures thereof.

[0078] Suitable alkyl (meth)acrylate monomers include, but are not limited to, those selected from the group consisting of acrylic or methacrylic acid esters 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 mixtures thereof. Such monomeric acrylic or methacrylic esters are known in the art and commercially available.

[0079] Generally, it is desirable for the first monomer to have a relatively low homopolymer Tg. For this reason, in many embodiments, the first monomer often includes an acrylate monomer instead of a methacrylate monomer, since acrylates tend to have lower homopolymer Tg values ​​than their corresponding methacrylates. In some embodiments, the first monomer has a homopolymer Tg of -20°C or lower.

[0080] Examples of alkyl acrylate monomers that are particularly suitable for use as the first (meth)acrylate monomer are isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isobutyl acrylate, and mixtures thereof.

[0081] The pre-adhesive mixture includes a second (meth)acrylate monomer of general formula II, CH2=CR 1 -(CO)-OR 3 Formula II In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer.

[0082] Typically, the pre-adhesive mixture comprises 4 to 30 parts by weight of the second (meth)acrylate monomer of general formula II. In some embodiments, the second (meth)acrylate monomer is present in an amount of 4 to 20 parts by weight, and in still other embodiments, the second (meth)acrylate monomer is present in an amount of 4 to 10 parts by weight.

[0083] Examples of suitable second monomers include those in which R 3 In some embodiments, the alkylene oxide group is a group of the formula -(R 4 -O-)n- repeating units [wherein R4 is an alkyl group containing 2 to 4 carbon atoms, and n is an integer from 3 to 100.

[0084] Examples of alkyl acrylate monomers that are particularly suitable for use as the second (meth)acrylate monomer are 2-hydroxyethyl acrylate, hydroxylpropyl acrylate, 4-hydroxybutyl acrylate, and poly(ethylene glycol) acrylate.

[0085] The pre-adhesive mixture forming the (meth)acrylate copolymer also contains a copolymerizable photocrosslinker, as described above. The copolymerizable photocrosslinker is a substance containing free-radically polymerizable groups that copolymerize with the monomers described above. The copolymerizable photocrosslinker also contains photosensitive groups, which, when exposed to the right wavelength of light, typically high-intensity ultraviolet (UV) light, form free radicals capable of forming crosslinks in the polymer. When the (meth)acrylate polymer is formed using a photoinitiator, the photocrosslinker is not activated by light of the same wavelength as the photoinitiator. In this way, the copolymerizable photocrosslinker is incorporated into the polymer and can be thermally processed because the crosslinker is thermally stable and remains intact until activated by the appropriate wavelength of light. This allows the copolymerizable photocrosslinker to be activated until the polymer is hot-melt coated. In some embodiments, these crosslinkers are activated by ultraviolet light generated from artificial sources such as medium-pressure mercury lamps or UV black lights.

[0086] Suitable photocrosslinkers include monoethylenically unsaturated aromatic ketone copolymers that do not contain ortho-aromatic hydroxyl groups, such as those described in U.S. Patent No. 4,737,559 (Kellen et al.). Specific examples include para-acryloxybenzophenone (ABP), para-acryloxyethoxybenzophenone, para-N-(methylacryloxyethyl)-carbamoylethoxybenzophenone, para-acryloxyacetophenone, ortho-acrylamidoacetophenone, acrylated anthraquinone, and the like. ABP para-acryloxybenzophenone, also known as 4-acryloxybenzophenone, is particularly suitable.

[0087] Typically, such photocrosslinkers are used in an amount of about 0.01 to 1.0 parts by weight 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 per 100 parts by weight of total monomers present in the reaction mixture.

[0088] The pre-adhesive mixture also includes at least one initiator. Typically, the initiator is a photoinitiator, meaning that the initiator is activated by light, typically ultraviolet (UV) light. Photoinitiators are well understood by those skilled in the art of (meth)acrylate polymerization. Examples of suitable free-radical photoinitiators include DAROCURE 1173, DAROCURE 4265, IRGACURE 184, IRGACURE 651, IRGACURE 1173, IRGACURE 819, LUCIRIN TPO, and LUCIRIN TPO-L, all commercially available from BASF, Charlotte, NC. Photoinitiator DAROCURE 1173 is particularly suitable.

[0089] Generally, the photoinitiator is used in an amount of 0.01 to 2 parts by weight, more typically 0.1 to 0.5 parts by weight, based on 100 parts by weight of all reactive components.

[0090] The pre-adhesive mixture may also contain various optional additives, so long as the additives do not adversely affect the polymerization reaction. One particularly suitable additive is a chain transfer agent. Examples of useful chain transfer agents include, but are not limited to, those selected from the group consisting of carbon tetrabromide, mercaptans, alcohols, and mixtures thereof. A particularly suitable chain transfer agent is IOTG (isooctylthioglycolate). Chain transfer agents and their use are well understood in the adhesives field.

[0091] The components of the pre-adhesive mixture are selected to impart desired properties to the resulting hot-melt processable (meth)acrylate-based polymer. Because hot-melt processable (meth)acrylate-based copolymers are pressure-sensitive adhesives, they typically have a Tg corresponding to room temperature (generally 20°C) or lower. In some embodiments, the (meth)acrylate-based copolymer has a Tg of 0°C or lower. In yet other embodiments, the (meth)acrylate-based copolymer has a Tg of -20°C or lower.

[0092] Hot-melt processable (meth)acrylate copolymers can have a wide range of molecular weights. Typically, (meth)acrylate copolymers have a weight average molecular weight of 500,000 grams / mole or greater. This molecular weight is particularly suitable for hot-melt processing.

[0093] The hot-melt processable packaged adhesive composition also includes a packaging material. The packaging material completely encloses the polymerized pre-adhesive mixture and any optional additives. The packaging material is a thermoplastic material that generally melts at or below the processing temperature of the polymerized pre-adhesive mixture (i.e., the temperature at which the polymerized pre-adhesive mixture flows). The packaging material generally has a melting point of 200°C or less, or 170°C or less. In some embodiments, the melting point is in the range of about 90°C to about 150°C. The packaging material may be a flexible thermoplastic polymer film. The flexible thermoplastic polymer film is made from a thermoplastic material. Suitable thermoplastic materials include polyethylene, ethylene copolymers such as ethylene / polyolefin copolymers and ethylene / vinyl copolymers such as ethylene vinyl acetate (EVA), ethylene methyl acrylate (EMA), ethylene acrylic acid (EAA), EAA ionomers, and polypropylene, as well as acrylics, polyphenylene ethers, polyphenylene sulfides, acrylonitrile-butadiene-styrene copolymers (ABS), polyurethanes, and other thermoplastic materials known to those skilled in the art. Blends of thermoplastic materials may also be used, with a particularly preferred thermoplastic material being polyethylene and EVA.

[0094] The thickness of the flexible thermoplastic film ranges from 0.01 mm to 0.25 mm, and from about 0.025 mm to about 0.127 mm to obtain a film that has good strength during processing, yet is thin enough to heat seal quickly and minimize the amount of film material used.

[0095] The packaging material may contain plasticizers, stabilizers, dyes, fragrances, fillers, slip agents, antiblocking agents, flame retardants, antistatic agents, microwave susceptors, thermally conductive particles, electrically conductive particles and / or other materials to increase flexibility, handleability, visibility or other useful film properties, so long as they do not adversely affect the desirable properties of the adhesive composition.

[0096] The amount of packaging material depends on the type of material and the desired final properties. The amount of packaging material typically ranges from 0.5% to 20% by weight, based on the total weight of the adhesive composition and packaging material. Typically, the packaging material is 2% to 15% by weight, more typically 3% to 5% by weight.

[0097] Also disclosed is a method of making an adhesive article. In some embodiments, the method includes providing a substrate having a first major surface and a second major surface, providing a hot-melt processable packaged adhesive composition, hot-melt processing the packaged adhesive composition, disposing the hot-melt processed packaged adhesive composition on at least a portion of the first major surface of the substrate to form a pressure-sensitive adhesive layer, and photocrosslinking the pressure-sensitive adhesive layer.

[0098] Suitable substrates are described above. A wide range of substrates are suitable, including release liners and medical substrates. A release liner is a sheet material having a low-adhesion coating on at least one surface. The hot-melt-processable pressure-sensitive adhesive of the present disclosure can be disposed on a release liner to produce an article comprising a layer of pressure-sensitive adhesive on the release liner. This adhesive / release liner article can be used to make other adhesive / substrate articles by laminating the adhesive layer to a different substrate and then removing the release liner. This allows for the placement of adhesive on substrates where it would be difficult to directly place a hot-melt-processable pressure-sensitive adhesive. The adhesive / release liner article can also be used to apply a pressure-sensitive adhesive layer to articles such as electrodes, ostomy appliances, and the like.

[0099] Exemplary medical substrates include polymeric materials, plastics, natural polymeric materials (e.g., collagen, wood, cork, silk, and leather), paper, fabrics, textiles, nonwovens, metals, glass, ceramics, composites, and combinations thereof. The medical substrate may be a tape backing. Examples of suitable tape backings include breathable conformable backings onto which an adhesive is disposed. A wide range of breathable conformable backings are suitable for use in the articles of the present disclosure. Typically, breathable conformable backings include woven or knitted fabrics, nonwovens, or plastics.

[0100] The hot-melt processable packaged adhesive composition is described in detail above and includes a hot-melt processable (meth)acrylate-based copolymer and a packaging material.

[0101] The hot-melt processable packaged adhesive composition is hot-melt processed and placed on the second major surface of the substrate. Methods for making the hot-melt processable packaged adhesive composition are described in detail below. These packaged adhesive compositions are hot-melt processed using hot-melt mixing equipment. In addition to the hot-melt processable packaged adhesive composition, optional additives can be added to the hot-melt mixture at this point, if desired. Typically, in embodiments of the present disclosure, optional additives are not added.

[0102] Various hot melt mixing techniques using various hot melt mixing equipment are suitable for producing the packaged adhesive composition. Both batch and continuous mixing equipment can be used. Examples of batch methods include those using a BRABENDER (e.g., the BRABENDER PREP CENTER, available from CW Brabender Instruments, Inc., South Hackensack, NJ) or a BANBURY internal mixing and roll milling device (e.g., equipment available from Farrel Co., Ansonia, CN). Examples of continuous methods include single-screw extrusion, twin-screw extrusion, disk extrusion, reciprocating single-screw extrusion, and pin-barrel single-screw extrusion. Continuous methods can utilize distributive elements, pin mixing elements, static mixing elements, and dispersive elements such as MADDOCK mixing elements and SAXTON mixing elements. A single hot melt mixing device or a combination of hot melt mixing devices can be used to process the packaged adhesive composition of the present disclosure.

[0103] The extrudate of the hot melt mixture is coated onto a substrate to form an adhesive layer. When a batch device is used, the resulting hot melt blend can be removed from the device and placed into a hot melt applicator or extruder to coat the substrate. When an extruder is used to prepare the hot melt blend, the blend can be extruded directly onto a substrate by a continuous molding method to form an adhesive layer. In the continuous molding method, the adhesive can be drawn out of a film die and subsequently contacted with the substrate surface.

[0104] To crosslink the pressure-sensitive adhesive layer, the adhesive layer is subjected to a photocrosslinking process. In this process, a photosensitive crosslinking agent is activated by exposure to a high-intensity UV lamp to cause crosslinking. Examples of suitable UV lamps include medium-pressure mercury lamps.

[0105] Hot-melt processable packaged adhesive compositions can be made, for example, using the method described in U.S. Pat. No. 6,294,249 (Hamer et al.). In this method, a polymerizable pre-adhesive composition is made. The polymerizable pre-adhesive mixture includes a first (meth)acrylate monomer of general formula I, a second (meth)acrylate monomer of general formula II, a photocrosslinker, a polymerization initiator, and optional additives such as a chain transfer agent. This mixture can be made and mixed in any suitable mixing equipment. Each of these components is described in detail above.

[0106] In some embodiments, two lengths of thermoplastic film are heat sealed together across the bottom and each of the side edges on a liquid form-fill-seal machine to form an open-ended pouch. The pre-adhesive composition is pumped through a hose to fill the pouch, and the pouch is then heat sealed across the top to completely enclose the adhesive composition.

[0107] Form-fill-and-seal machines typically include an impulse sealer that traverses the pouch to form the top and bottom seals. Such sealers have one or two sets of jaws that clamp the pouch closed before scaling. A sealing wire is then heated to effect the seal, and the seal is allowed to cool before the jaws are released. The sealing temperature is generally above the softening point and below the melting point of the film used to form the pouch.

[0108] During the sealing process, it is desirable to remove most of the air from the pouch before sealing. A small amount of air is acceptable as long as the amount of oxygen is not sufficient to substantially interfere with the polymerization process. For ease of handling, it is desirable to seal the pouch as soon as it is filled with the composition, but immediate sealing is not necessary in all cases. In some cases, the pre-adhesive composition may alter the packaging material, and it is desirable to cross-seal the pouch within about 1 minute of filling, more typically within 30 seconds, and most typically within 15 seconds. If the pre-adhesive composition reduces the strength of the packaging material, it is preferable to polymerize the composition as soon as possible after the pre-adhesive composition is surrounded by the packaging material.

[0109] Alternatively, a single length of film can be folded lengthwise, one edge sealed, filled with the pre-adhesive composition, and sealed. In another embodiment, a single length of film can be stretched through a forming collar, sealed to form a tube, filled with the composition, and sealed. Another embodiment can be performed with a commercially available liquid form-fill-seal machine. A source for such machines is Eagle's Packaging Machinery Division. It is contemplated that sealing can be performed in any of a number of different configurations to form multiple pouches across and down the length of the film. For example, in addition to sealing the side edges, a seal can also be formed down the center of the length of the film, such that a cross seal forms two filled pouches. The pouches can remain attached to each other with a cross seal and / or a vertical seal, or can be cut into individual pouches or bundles of pouches. The pouches can each contain the same or different compositions.

[0110] Typically, the pre-adhesive composition is polymerized by activating a photoinitiator with radiation of an appropriate wavelength, typically UV radiation. In many embodiments, the packaged pre-adhesive composition is immersed in a heat exchange medium to generate excess heat during polymerization. In many embodiments, the heat exchange medium is water maintained at room temperature.

[0111] Once polymerization is complete, a packaged adhesive composition is produced. This packaged adhesive composition can be used immediately, stored for later use, or shipped to a different location for hot melt processing. Because the viscoelastic adhesive composition is contained within a package, handling and storage are greatly simplified. Suitable packaging materials are thermoplastic polymers, as described in detail above.

[0112] The present disclosure includes the following embodiments.

[0113] The present disclosure includes adhesive articles, packaged adhesive compositions, and methods for making adhesive articles.

[0114] Among other embodiments are adhesive articles. Embodiment 1 is an article comprising a substrate and a hot-melt processable pressure-sensitive adhesive disposed on at least a portion of the substrate, the hot-melt processable pressure-sensitive adhesive comprising a (meth)acrylate-based copolymer that is the reaction product of a reaction mixture that is substantially free of acidic or basic monomers and that includes, as a polymerizable component, 70 parts by weight to 96 parts by weight of a first (meth)acrylate monomer of general formula I: CH2=CR 1 -(CO)-OR 2 Formula I [In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group, and 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH2=CR 1 -(CO)-OR 3 Formula II [In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; and a copolymerizable photocrosslinker.

[0115] Embodiment 2 is the article of embodiment 1, wherein the pressure-sensitive adhesive further comprises particles of a thermoplastic polymer, the thermoplastic polymer comprising polyethylene, ethylene vinyl acetate, ethylene methyl acrylate, ethylene acrylic acid, ethylene acrylic acid ionomer, polypropylene, acrylic polymer, polyphenylene ether, polyphenylene sulfide, acrylonitrile-butadiene-styrene copolymer, polyurethane, and mixtures and blends thereof.

[0116] Embodiment 3 is the article of embodiment 1 or 2, wherein the substrate comprises a polymeric film, fabric, nonwoven, foam, paper, mesh, adhesive, or release liner.

[0117] Embodiment 4 is the article of any one of embodiments 1-3, wherein the reaction mixture includes 80 to 96 parts by weight of the first monomer and 4 to 20 parts by weight of the second monomer.

[0118] Embodiment 5 is the article of any one of embodiments 1-4, wherein the reaction mixture includes 90 to 96 parts by weight of the first monomer and 4 to 10 parts by weight of the second monomer.

[0119] Embodiment 6 is the article of any one of embodiments 1-5, wherein the (meth)acrylate copolymer has a Tg of -20°C or less.

[0120] Embodiment 7 is the article of any one of embodiments 1-6, wherein the (meth)acrylate-based copolymer has a weight average molecular weight Mw greater than or equal to 500,000 grams / mole.

[0121] Embodiment 8 is the article of any one of embodiments 1-7, wherein the first monomer has a homopolymer Tg of -20°C or less.

[0122] Embodiment 9 is directed to a method for preparing a first monomer R 2is an alkyl group having 1 to 14 carbon atoms.

[0123] Embodiment 10 relates to a method for preparing a compound having an R group of a first monomer. 2 is an alkyl group having 7 to 9 carbon atoms.

[0124] Embodiment 11 is the article of any one of embodiments 1-10, wherein the first monomer is selected from the group including isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isobutyl acrylate, and mixtures thereof.

[0125] Embodiment 12 is directed to a method for preparing a compound having an R group of a second monomer. 3 comprises a hydroxyl-substituted alkyl group containing 2 to 6 carbon atoms or a polymeric group containing a hydroxyl-terminated alkylene oxide group, the alkylene oxide group being of the formula -(R 4 -O-)n- repeating units [wherein R 4 is an alkyl group containing 2 to 4 carbon atoms; and n is an integer from 3 to 100.

[0126] Embodiment 13 is the article of any one of embodiments 1-12, wherein the second monomer is 2-hydroxyethyl acrylate, hydroxylpropyl acrylate, or 4-hydroxybutyl acrylate.

[0127] Embodiment 14 is the article of any one of embodiments 1-13, wherein the pressure-sensitive adhesive layer further comprises at least one additive.

[0128] Embodiment 15 is the article of embodiment 14, wherein the additive comprises an antioxidant.

[0129] Embodiment 16 is the article of any one of embodiments 1-15, wherein the pressure-sensitive adhesive layer is photocrosslinked.

[0130] Also disclosed is a packaged adhesive composition. Embodiment 17 is a packaged adhesive composition for a hot-melt processable adhesive comprising a polymerized (meth)acrylate copolymer formed from a polymerizable pre-adhesive mixture, wherein the polymerizable pre-adhesive mixture composition is substantially free of acidic or basic monomers and comprises from 70 parts by weight to 96 parts by weight of a first (meth)acrylate monomer of general formula I CH2=CR 1 -(CO)-OR 2 Formula I [In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group, and 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH2=CR 1 -(CO)-OR 3 Formula II [In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer], a copolymerizable photocrosslinker, and at least one initiator; and a packaging material.

[0131] Embodiment 18 is the packaged adhesive composition of embodiment 17, wherein the polymerizable pre-adhesive mixture composition further comprises a chain transfer agent.

[0132] Embodiment 19 is the packaged adhesive composition of embodiment 17 or 18, wherein the polymerizable pre-adhesive mixture composition comprises 80 to 96 parts by weight of the first monomer and 4 to 20 parts by weight of the second monomer.

[0133] Embodiment 20 is the packaged adhesive composition of any one of embodiments 17-19, wherein the polymerizable pre-adhesive mixture composition comprises 90 to 96 parts by weight of the first monomer and 4 to 10 parts by weight of the second monomer.

[0134] Embodiment 21 is the packaged adhesive composition of any one of embodiments 17-20, wherein the polymerized (meth)acrylate copolymer has a Tg of -20°C or less.

[0135] Embodiment 22 is the packaged adhesive composition of any one of embodiments 17-21, wherein the polymerized (meth)acrylate copolymer has a weight average molecular weight, Mw, greater than or equal to 500,000 grams / mole.

[0136] Embodiment 23 is the packaged adhesive composition of any one of embodiments 17-22, wherein the first monomer has a homopolymer Tg of -20°C or less.

[0137] Embodiment 24 is directed to a method for preparing a compound comprising: 2 24. The packaged adhesive composition of any one of embodiments 17-23, wherein is an alkyl group having 1 to 14 carbon atoms.

[0138] Embodiment 25 is directed to a method for preparing a compound having an R group of a first monomer. 2 25. The packaged adhesive composition of any one of embodiments 17-24, wherein is an alkyl group having 7 to 9 carbon atoms.

[0139] Embodiment 26 is the packaged adhesive composition of any one of embodiments 17-25, wherein the first monomer is selected from the group consisting of isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, isobutyl acrylate, and mixtures thereof.

[0140] Embodiment 27 is directed to a method for preparing a compound having an R group of a second monomer. 3comprises a hydroxyl-substituted alkyl group containing 2 to 6 carbon atoms or a polymeric group containing a hydroxyl-terminated alkylene oxide group, the alkylene oxide group being of the formula -(R 4 -O-)n- repeating units [wherein R 4 is an alkyl group containing 2 to 4 carbon atoms; and n is an integer from 3 to 100.

[0141] Embodiment 28 is the packaged adhesive composition of any one of embodiments 17-27, wherein the second monomer is 2-hydroxyethyl acrylate, hydroxylpropyl acrylate, or 4-hydroxybutyl acrylate.

[0142] Embodiment 29 is the packaged adhesive composition of any one of embodiments 17-28, wherein the pressure-sensitive adhesive further comprises at least one additive.

[0143] Embodiment 30 is the packaged adhesive composition of any one of embodiments 17-29, wherein the packaging material comprises a thermoplastic polymer, the thermoplastic polymer comprising polyethylene, ethylene vinyl acetate, ethylene methyl acrylate, ethylene acrylic acid, ethylene acrylic acid ionomer, polypropylene, acrylic polymer, polyphenylene ether, polyphenylene sulfide, acrylonitrile-butadiene-styrene copolymer, polyurethane, and mixtures and blends thereof.

[0144] Also disclosed is a method of making an adhesive article. Embodiment 31 is a method of making an adhesive article, comprising providing a substrate having a first major surface and a second major surface, and providing a hot-melt processable packaged adhesive composition, the hot-melt processable packaged adhesive composition being a hot-melt processable adhesive comprising a polymerized (meth)acrylate copolymer formed from a polymerizable pre-adhesive mixture, the polymerizable pre-adhesive mixture composition being substantially free of acidic or basic monomers and comprising 70 to 96 parts by weight of a first (meth)acrylate monomer of general formula I CH2=CR 1 -(CO)-OR 2 Formula I [In the formula, R 1 is hydrogen or a methyl group, and R 2 is an alkyl, heteroalkyl, alkenyl, or aryl group, and 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH2=CR 1 -(CO)-OR 3 Formula II [In the formula, R 1 is hydrogen or a methyl group, and R 3 is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer], a copolymerizable photocrosslinker, and at least one initiator; and a packaging material; hot-melt processing the packaged adhesive composition; disposing the hot-melt processed packaged adhesive composition on at least a portion of a second major surface of a substrate to form a pressure-sensitive adhesive layer; and photocrosslinking the pressure-sensitive adhesive layer.

[0145] Embodiment 32 is the method of embodiment 31, wherein the packaging material comprises polyethylene, ethylene vinyl acetate, ethylene methyl acrylate, ethylene acrylic acid, ethylene acrylic acid ionomer, polypropylene, acrylic polymer, polyphenylene ether, polyphenylene sulfide, acrylonitrile-butadiene-styrene copolymer, polyurethane, and mixtures and blends thereof.

[0146] Embodiment 33 is the method of embodiment 31 or 32, wherein the polymerizable pre-adhesive mixture further comprises a chain transfer agent.

[0147] Embodiment 34 is the method of any one of embodiments 31-33, wherein the polymerized (meth)acrylate copolymer comprises polymerizing the polymerizable pre-adhesive mixture by activation of an initiator.

[0148] Embodiment 35 is the method of any one of embodiments 31 to 34, wherein the initiator comprises a photoinitiator.

[0149] Embodiment 36 is the method of any one of embodiments 31-35, wherein the crosslinking comprises photochemical initiation of a copolymerizable photocrosslinker.

[0150] Embodiment 37 is the method of any one of embodiments 31-36, wherein the pressure-sensitive adhesive layer further comprises at least one additive. [Example]

[0151] These examples are for illustrative purposes only and are not meant to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and elsewhere herein are by weight unless otherwise indicated. Solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company (Milwaukee, Wisconsin) unless otherwise specified. The following abbreviations are used: mm = millimeter, cm = centimeter, in = inch, mL = milliliter, μg = microgram, kg = kilogram, lb = pound, Pa = pascal, min = minute, ppm = parts per million.

[0152] [Table 1]

[0153] Test Method Gel Permeation Chromatography (GPC) Number average molecular weight (M n The molecular weight (Mw) and weight-average molecular weight (Mw) were obtained by conventional gel permeation chromatography with a light scattering detector using tetrahydrofuran as the solvent and mobile phase. The instrument consisted of an Agilent 1100 system (pump, degasser, autosampler, column oven, differential refractometer) [Agilent Technologies, Santa Clara, CA, USA] and was operated at 40 °C and a flow rate of 1.0 mL / min. The stationary phase consisted of a Jordi Gel DVB mixed column [250 mm × 10 mm ID (Jordi Labs, Mansfield, MA, USA)]. A Polymer Labs (now Agilent Technologies, Santa Clara, CA, USA) Cirrus GPC was used for molecular weight calculations.

[0154] Dynamic Mechanical Analysis (DMA) DMA was used to measure the storage modulus, viscosity, and glass transition temperature of the pre-adhesive composition. A small sample of the pre-adhesive composition was placed on the lower plate of a rheometer (ARES G2 Rheometer, available from TA Instruments, New Castle, Del.). The rheometer had parallel upper and lower plates, each 8 mm in diameter. The upper plate of the rheometer was moved over the pre-adhesive composition sample until the parallel plates were spaced 1 mm apart. The sample was subjected to an oscillatory shear force (strain amplitude = 1%, frequency = 1 Hz) while the sample temperature was continuously increased from -65°C to 175°C at a rate of 5°C / min. During this time, the shear modulus, viscosity, and tan(δ) were evaluated using a temperature sweep test. The storage modulus (G') was recorded in Pa. Tan(δ) was calculated as the ratio of G" / G' (loss modulus / storage modulus). The temperature at which tan(δ) had a local peak was reported as the glass transition temperature ("Tg").

[0155] Gel concentration Gel concentration (gel content) was determined in a manner generally similar to that described in ASTM D3616-95 (specified in 2009), with the following modification: 63 / 64 inch diameter test specimens were placed in a 1.5 inch x 1.5 inch mesh basket. The basket containing the test specimens was weighed to approximately 0.1 mg and placed in a lidded jar containing sufficient EtOAc to cover the specimens. After 24 hours, the basket (containing the test specimens) was removed, the EtOAc was drained, and the basket was placed in a 120°C oven for 30 minutes. Gel concentration was determined by assigning the weight of the remaining unextracted portion of the adhesive sample to the weight of the adhesive sample before extraction (a disk of uncoated backing material of the same size as the test specimen was die-cut and weighed, to correct for the weight of the tape backing). The equation used to calculate gel concentration is:

number

[0156] Residual Monomer Analysis The residual monomer content of the final pressure-sensitive adhesive composition was determined by gas chromatography according to the following procedure: A predetermined amount of sample was weighed into a drum vial, and methanol was added. The vial was capped and shaken for 2 minutes. A portion of the sample was transferred to an autosampler vial and analyzed using an HP 6890 GCFID instrument. The column type was a J&W DB-5 MS 30 m x 0.25 mm x 0.1 μm, and the gas phase was He 2.0 ml / min. A known amount of standard was weighed into each sample and then analyzed to establish a calibration range of approximately 0.05 μg / mL to 1,000 μg / mL.

[0157] Peel Adhesion Test Peel adhesion was measured at a 180° angle using a Zwick tester (available from Zwick, GA) at a peel rate of 12 inches per minute. Stainless steel test panels were prepared by wiping the substrate panel three times with a lab wipe moistened with 50% n-heptane / 50% isopropanol, applying hand pressure. Adhesive tape samples were cut into 1 / 2 inch x 8 inch strips, and the strips were rolled onto the cleaned panel using a mechanical roller machine (preferred) or a hand-operated 4.5 lb roller (no additional force required), at a speed of approximately 2 inches (50 mm) per second in each direction, or one roll with a mechanical roller machine set at 120 inches per minute. Prepared samples were stored at 25°C and 50% relative humidity for the desired "dwell" time before testing. The experiment was repeated three to five times, and the average value was recorded as the peel strength.

[0158] The PVC panels were washed three times with heptane and then the same procedure was followed as for the stainless steel panels.

[0159] Immersion Test Samples Testing was performed using the peel adhesion test described above, except that the tape samples were immersed in a 3 mM aqueous CaCl solution (333 mg CaCl in 1 liter of deionized water) for the specified time (20 minutes or 60 minutes) before application onto the SS test panels.

[0160] Preparation of pre-adhesive composition and (meth)acrylate polymer A pre-adhesive formulation was made and cured to form a (meth)acrylate-based polymer according to the method described in U.S. Patent No. 5,804,610. The water bath temperature was 60°F and the UV intensity was 4.55 mW / cm. 2 The composition of each formulation is listed in Table 1.

[0161] [Table 2]

[0162] The properties of the (meth)acrylate polymer were measured according to the test methods described above, and the test results are summarized in Table 2.

[0163] [Table 3]

[0164] UV radiation crosslinking The (meth)acrylate polymer was fed into a twin-screw extruder (Haake) with the barrel temperature set at 275°F. The pressure-sensitive adhesive was extruded to a thickness of 0.0254 mm onto a paper web that had been treated on both sides with a silicone release coating. The coated adhesive was then exposed to a medium pressure mercury vapor lamp with an output of approximately 80 watts / cm and a spectral output ranging from 180 nm to 430 nm, resulting in an intensity of 50 mJ / cm. 2 The pressure-sensitive adhesives PRE1-PRE21 and PRE27 were then laminated to ESTANE 58237 thermoplastic polyurethane film, available from Lubrizol Corporation, and tested according to the test procedure for peel adhesion described above. The test results are shown in Table 3.

[0165] Pressure-sensitive adhesives PRE-22-PRE-25 and PRE27-PRE30 were extruded onto a cellulose acetate backing to a thickness of 0.072 mm, the opposite side of which was treated with a low-adhesion coating. Test results are shown in Table 4. Additionally, Example 13 had a gel fraction of 81% as measured using the gel concentration method described herein.

[0166] [Table 4]

[0167] [Table 5]

[0168] The residual monomer analysis of each pressure-sensitive adhesive composition is summarized in Table 5. Residual monomer concentrations of 500 ppm or less suggest that Examples 1-9 and CE1 are suitable for skin adhesive applications.

[0169] [Table 6]

Claims

1. An article, A substrate; a hot-melt processable pressure-sensitive adhesive disposed on at least a portion of the substrate; the hot-melt processable pressure-sensitive adhesive comprises a (meth)acrylate-based copolymer and optional additives that are the reaction product of a reaction mixture, the reaction mixture being free of acidic or basic monomers and containing, as a polymerizable component: 70 parts by weight to 96 parts by weight of a first (meth)acrylate monomer of general formula I CH ２ =CR １ -(CO)-OR ２ Formula I [In the formula, R １ is hydrogen or a methyl group, and R ２ is an alkyl, heteroalkyl, alkenyl, or aryl group; 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH ２ =CR １ -(CO)-OR ３ Formula II [In the formula, R １ is hydrogen or a methyl group, and R ３ is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; a copolymerizable photocrosslinker; wherein the additives are selected from a tackifying resin, a plasticizer, an antioxidant, a filler, a leveling agent, an ultraviolet absorber, a hindered amine light stabilizer (HALS), an oxygen inhibitor, a wetting agent, a rheology modifier, a defoamer, a biocide, a dye, or a pigment, and the pressure-sensitive adhesive further comprises particles of a thermoplastic polymer, the thermoplastic polymer comprising polyethylene, polyethylene vinyl acetate, polyethylene methyl acrylate, polyethylene acrylic acid, ethylene acrylic acid ionomer, polypropylene, an acrylic polymer, polyphenylene ether, polyphenylene sulfide, acrylonitrile-butadiene-styrene copolymer, polyurethane, and mixtures and blends thereof.

2. The article of claim 1 , wherein the substrate comprises a polymeric film, a fabric, a nonwoven, a foam, a paper, a mesh, an adhesive, or a release liner.

3. 10. The article of claim 1, wherein the reaction mixture comprises 80 to 96 parts by weight of the first monomer and 4 to 20 parts by weight of the second monomer.

4. The article of claim 1, wherein the (meth)acrylate-based copolymer has a Tg of -20°C or less.

5. 10. The article of claim 1, wherein the (meth)acrylate-based copolymer has a weight average molecular weight Mw of 500,000 grams / mole or greater.

6. The R of the second monomer ３ but, a hydroxyl-substituted alkyl group containing 2 to 6 carbon atoms, or a polymeric group comprising a hydroxyl-terminated alkylene oxide group; The alkylene oxide group is represented by the formula -(R ４ -O-)n- repeating unit [In the formula, R ４ is an alkyl group containing 2 to 4 carbon atoms, and n is an integer from 3 to 100.

7. 1. A packaged adhesive composition comprising: A hot-melt processable adhesive comprising a (meth)acrylate copolymer and optional additives formed from a polymerizable pre-adhesive mixture composition, wherein the polymerizable pre-adhesive mixture composition does not contain acidic or basic monomers; 70 parts by weight to 96 parts by weight of a first (meth)acrylate monomer of general formula I CH ２ =CR １ -(CO)-OR ２ Formula I [In the formula, R １ is hydrogen or a methyl group, and R ２ is an alkyl, heteroalkyl, alkenyl, or aryl group; 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH ２ =CR １ -(CO)-OR ３ Formula II [In the formula, R １ is hydrogen or a methyl group, and R ３ is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; a copolymerizable photocrosslinker; at least one initiator; a hot melt processable adhesive comprising: a packaging material that is a thermoplastic polymer; wherein the additive is selected from a tackifying resin, a plasticizer, an antioxidant, a filler, a leveling agent, an ultraviolet absorber, a hindered amine light stabilizer (HALS), an oxygen inhibitor, a wetting agent, a rheology modifier, a defoamer, a biocide, a dye, or a pigment.

8. 8. The packaged adhesive composition of claim 7, wherein the polymerizable pre-adhesive mixture composition further comprises a chain transfer agent.

9. 8. The packaged adhesive composition of claim 7, wherein the polymerizable pre-adhesive mixture composition comprises 80 to 96 parts by weight of the first monomer and 4 to 20 parts by weight of the second monomer.

10. 1. A method of making an adhesive article, comprising: providing a substrate having a first major surface and a second major surface; 1. A hot-melt processable packaged adhesive composition comprising:

1. A hot-melt processable adhesive comprising a (meth)acrylate copolymer and optional additives formed from a polymerizable pre-adhesive mixture composition, the polymerizable pre-adhesive mixture composition does not contain acidic or basic monomers; and 70 parts by weight to 96 parts by weight of a first (meth)acrylate monomer of general formula I CH ２ =CR １ -(CO)-OR ２ Formula I [In the formula, R １ is hydrogen or a methyl group, and R ２ is an alkyl, heteroalkyl, alkenyl, or aryl group; 4 parts by weight to 30 parts by weight of a second (meth)acrylate monomer of general formula II CH ２ =CR １ -(CO)-OR ３ Formula II [In the formula, R １ is hydrogen or a methyl group, and R ３ is a hydroxyl-substituted alkyl group, a hydroxyl-substituted heterocyclic group, a hydroxyl-substituted aryl group, or a hydroxyl-substituted polymer; a copolymerizable photocrosslinker; at least one initiator; and a packaging material that is a thermoplastic polymer; and hot melt processing the packaged adhesive composition; disposing the hot-melt processed packaged adhesive composition on at least a portion of the second major surface of the substrate to form a pressure-sensitive adhesive layer; and photocrosslinking the pressure-sensitive adhesive layer, wherein the additive is selected from a tackifying resin, a plasticizer, an antioxidant, a filler, a leveling agent, an ultraviolet absorber, a hindered amine light stabilizer (HALS), an oxygen inhibitor, a wetting agent, a rheology modifier, a defoamer, a biocide, a dye, or a pigment.

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