Acrylic polymer and adhesive composition

Abstract

We disclose an acrylic polymer and pressure-sensitive adhesive composition prepared from (i) about 1 to about 10 weight percent of a carboxy-functional monomer component, (ii) about 50 to about 90 weight percent of a low Tg alkyl acrylate monomer component, (iii) about 1 to about 20 weight percent of a tertiary amine-functionalized alkyl acrylate monomer component, and (iv) optionally, up to 50 weight percent of a vinyl ester monomer component. The acrylic polymer and pressure-sensitive adhesive are ideally suited for skin-contact applications, particularly as diagnostic patches, transdermal drug delivery patches, and skin patches for the delivery of skin-active substances.

Description

Technical Field

[0001] (Field of the Invention) The present invention relates to acrylic polymers and pressure-sensitive adhesive compositions ideally suitable for skin contact applications including, but not limited to, adhesives for adhering medical devices to the skin, diagnostic patches, transdermal drug delivery patches, and skin patches for the delivery of skin actives, and their end-use applications.

Background Art

[0002] (Background of the Invention) Adhesive compositions are widely used in the medical field, for example, in various tapes, bandages, and drug delivery devices. These devices have an adhesive layer formed on at least one surface of a substrate and are adhered to a target skin surface through the adhesive layer. The adhesive is a pressure-sensitive adhesive that is permanently sticky at room temperature, holds the adherend to the skin with gentle pressure, and can be easily removed without causing pain or leaving adhesive residues. Depending on the purpose of the application, the device needs to ensure adhesion to the skin surface over a long period of time. These devices are usually in the form of ostomy bags, bandages, diagnostic vehicles, and transdermal patches.

[0003] Pressure-sensitive adhesives for application to the skin are known, but there is a continuing need and necessity in medical applications. The present invention addresses this need in the art.

Summary of the Invention

Means for Solving the Problems

[0004] (Brief Summary of the Invention) The present invention relates to acrylic polymers and adhesive compositions, and particularly to products containing acrylic polymers and adhesive compositions in medical skin contact devices.

[0005] One aspect of the present invention relates to an acrylic polymer prepared from (i) about 1 to about 10% by weight of a carboxy-functional monomer component, (ii) about 50 to about 90% by weight of a low Tg alkyl acrylate monomer component, (iii) about 1 to about 20% by weight of a tertiary amine-functionalized alkyl acrylate monomer component, and (iv) optionally, up to 50% by weight of a vinyl ester monomer component.

[0006] Another aspect of the present invention relates to a pressure-sensitive adhesive composition comprising an acrylic polymer prepared from (i) about 1 to about 10 carboxy- and / or hydroxy-functional monomers, (ii) about 50 to about 90% by weight of a low Tg alkyl acrylate monomer component, and (iii) about 1 to about 20% by weight of a tertiary amine-functionalized alkyl acrylate monomer.

[0007] Yet another aspect of the present invention relates to a medical skin contact device comprising an adhesive layer comprising the above pressure-sensitive adhesive composition and a backing layer. The pressure-sensitive adhesive composition of the medical skin contact device provides long-term adhesion and shear performance.

[0008] Yet another aspect of the present invention relates to a method of forming an acrylic polymer comprising the steps of (a) forming a monomer mixture in a container of (i) about 1 to about 10 carboxy- and / or hydroxy-functional monomers, (ii) about 50 to about 90 of a low Tg alkyl acrylate monomer component, and (iii) about 1 to about 20% by weight of a tertiary amine-functionalized alkyl acrylate monomer component, (b) adding a solvent and a crosslinking agent to the container, (c) heating the container, and (d) separating the acrylic polymer.

Mode for Carrying Out the Invention

[0009] (Detailed Description of the Invention) As used herein, the terms "pressure sensitive adhesive" or "PSA" refer to viscoelastic materials that adhere instantaneously to most substrates upon the application of slight pressure and maintain adhesiveness permanently. A polymer is a pressure sensitive adhesive within the meaning of the terms used herein if it has the properties of a pressure sensitive adhesive by itself or functions as a pressure sensitive adhesive by mixing with other components. The pressure sensitive adhesives of the present invention can be used for any number of applications, for example, labels, tapes, and medical skin contact device tapes for diagnostic and transdermal purposes.

[0010] The term "transdermal" refers to an application on or to the skin, whereby the skin is used as a portal for diagnostic procedures such as monitoring of blood chemistry or for administration of drugs by topical application.

[0011] The terms "skin", "dermis" and "epidermis" are used interchangeably unless otherwise specified.

[0012] The term "patient" is used herein to include both human and non-human animals, including companion animals such as dogs, cats and horses, as well as livestock such as cows and pigs. Agricultural and horticultural applications are also contemplated.

[0013] Weight percent, "wt%", indicates weight percent based on the total weight of the components in the polymer.

[0014] The pressure sensitive adhesive is formed from an acrylic polymer. The pressure sensitive adhesive may be a neat acrylic polymer or in combination with a tackifier, a plasticizer, or other additives to provide pressure sensitive properties.

[0015] An acrylic polymer prepared from (i) about 1 to about 10 weight % of a carboxy-functional monomer component, (ii) about 50 to about 90 weight % of a low Tg alkyl acrylate monomer component, (iii) about 1 to about 20 weight % of a tertiary amine-functionalized alkyl acrylate monomer component, and (iv) optionally, up to 50 weight % of a vinyl ester monomer component.

[0016] (i) The carboxy-functional monomer component contains from about 3 to about 12 carbon atoms and includes, inter alia, acrylic acid, methacrylic acid, itaconic acid, β-carboxyethyl acrylate, and mixtures thereof.

[0017] (ii) The low Tg alkyl acrylate monomer has a homopolymer with a Tg of less than about -30 °C. Preferred alkyl acrylates for the acrylic polymer have up to about 18 carbon atoms in the alkyl group, preferably from about 4 to about 12 carbon atoms in the alkyl group. Alkyl acrylates for preparing the acrylic polymer include methyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, decyl acrylate, dodecyl acrylate, their isomers, and combinations thereof. Particularly preferred are butyl acrylate, 2-ethylhexyl acrylate and / or isooctyl acrylate, most preferably 2-ethylhexyl acrylate.

[0018] (iii) The tertiary amine-functionalized alkyl acrylate monomer component is selected from 2-dimethylaminoethyl methacrylate, 2-N-morpholinoethyl acrylate, 2-N-morpholinoethyl methacrylate, 2-diisopropylaminoethyl methacrylate, N-[3-(N,N-dimethylamino)propyl]methacrylamide, N-[2-(N,N-dimethylamino)ethyl]methacrylamide, N-[3-(N,N-dimethylamino)propyl]acrylamide, min, 95%, 2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-diethylamino)ethyl methacrylate, 2-(N,N-dimethylamino)ethyl methacrylate, 2-acryloxyethyltrimethylammonium chloride, and mixtures thereof.

[0019] The acrylic polymer may optionally contain (iv) one or more vinyl ester monomers. Carboxy and / or hydroxy functional monomers are preferred. Useful vinyl esters include vinyl acetate, vinyl benzoate, vinyl tert-butylbenzoate, vinyl chloroformate, vinyl cinnamate, vinyl decanoate, vinyl neodecanoate, vinyl pivalate, vinyl propionate, vinyl stearate, vinyl trifluoroacetate, vinyl valerate, and mixtures thereof, with vinyl acetate being particularly preferred.

[0020] The acrylic polymer may also contain a hydroxy functional monomer component and its derivatives. The hydroxy functional monomer component is selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate, and mixtures thereof. Alternatively, the acrylic polymer further contains an anhydride functional monomer component and its derivatives. The anhydride functional monomer component is selected from the group consisting of maleic anhydride, nadic anhydride, methyl maleic anhydride, methyl nadic anhydride or similar compounds. Adding a hydroxy functional monomer or an anhydride functional monomer component to the acrylic polymer improves the shear performance of the adhesive. An increase in the ionic properties of the hydroxy functional monomer or anhydride functional monomer in the adhesive is thought to provide this improved shear performance.

[0021] In one preferred embodiment, the acrylic polymer is prepared from (i) about 1 to about 10% by weight of acrylic acid, (ii) about 50 to about 90% by weight of 2-ethylhexyl methacrylate, (iii) about 1 to about 20% by weight of 2-dimethylaminoethyl methacrylate and (iv) up to about 50% by weight of vinyl acetate.

[0022] Although specific polymerization methods are described in the examples, the acrylic polymer can be prepared by conventional polymerization methods well known to those skilled in the art. These methods include, but are not limited to, solution polymerization, suspension polymerization, bulk polymerization and emulsion polymerization.

[0023] It may also be advantageous to reduce the residual monomer content or remove or reduce the solvent level and / or other volatiles after polymerization using known and conventional methods in the art.

[0024] One way to form an acrylic polymer is (a) forming a monomer mixture in a container of (i) 1 to about 10 carboxy and / or hydroxy functional monomers, (ii) about 50 to about 90 of a low Tg alkyl acrylate monomer component, (iii) about 1 to about 20 wt% of a tertiary amine functionalized alkyl acrylate monomer component, (b) adding a solvent and an initiator to the container, (c) heating the container, and (d) separating the acrylic polymer.

[0025] A variety of initiators and solvents can be used to assist the polymerization process.

[0026] Examples of initiators useful for polymerization include 2,2'-azodi-(2-methylbutyronitrile), 2,2'-azobis-isobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile) and 2,2'-azobis-(2,4-dimethylvaleronitrile), and peroxide-based polymerization initiators such as lauryl peroxide, benzoyl peroxide and di(tert-butyl) peroxide.

[0027] Solvents useful for polymerization include organic solvents such as ethyl acetate, acetone, hexane, cyclohexane, heptane, toluene, ethanol, and isopropyl alcohol, or combinations thereof.

[0028] The neat acrylic polymer is viscoelastic and adheres instantaneously to stainless steel and synthetic skin (Vitro-Skin®, Portland, ME) substrates.

[0029] In another embodiment, a pressure-sensitive adhesive composition is formed that includes a pressure-sensitive adhesive composition comprising an acrylic polymer prepared from (i) from about 1 to about 10 carboxy and / or hydroxy functional monomers, (ii) from about 50 to about 90 low Tg alkyl acrylate monomer components, and (iii) from about 1 to about 20 weight percent of a tertiary amine functionalized alkyl acrylate monomer.

[0030] The acrylic polymer, in combination with plasticizers, tackifiers, and other additives, can improve the adhesive properties of the pressure-sensitive adhesive.

[0031] Examples of plasticizers include fatty acid esters of monohydric alcohols such as cetyl octanoate, hexyl laurate, isopropyl myristate, isopropyl palmitate, butyl stearate, and myristyl lactate; dibasic acid esters such as dioctyl adipate, diethyl sebacate, dioctyl sebacate, and dioctyl succinate; fatty acid esters of polyhydric alcohols such as propylene glycol dicaprionate, glyceryl trioctanoate, glyceryl tri(octanoate / decanoate), and medium-chain fatty acid triglycerides. Among these, there are fatty acid esters such as isopropyl myristate and isopropyl palmitate.

[0032] Suitable tackifiers include (1) aliphatic hydrocarbons, (2) mixtures of aliphatic and aromatic hydrocarbons, (3) aromatic hydrocarbons, (4) substituted aromatic hydrocarbons, (5) cured esters, (6) polyterpenes, (7) wood resins or rosins and their cured forms. The tackifier used is preferably compatible with the polymer. The pressure-sensitive adhesive may further include rheology modifiers, diluents, emollients, anti-irritants, opacifiers, fillers such as clays and silicas, pigments, preservatives, antioxidants, or additives.

[0033] The pressure-sensitive adhesive is viscoelastic, instantaneously adheres to various substrates with slight pressure, and permanently maintains adhesiveness. The shear strength is improved with the polymers of the present invention, indicating the usefulness of the polymers for long-term wearable devices. The peel strength of the polymers further indicates usefulness remaining on the dermis and remains equivalent or improved.

[0034] The pressure-sensitive adhesive is useful for the manufacture of labels such as industrial tapes, films, and masking tapes, surface protection films, bookmarks, sticky notes, price display labels, promotional graphic materials, etc. and medical skin contact devices such as wound dressings, EKG electrodes, sports tapes, ostomy bags, analgesics, and transdermal patches.

[0035] Active substances can be incorporated into the pressure-sensitive adhesive. The pressure-sensitive adhesive can be advantageously formulated for use in wound treatment, transdermal or topical drug, or pharmaceutical cosmetic delivery applications. The term transdermal refers to the use of the skin as a portal for drug administration by topical application. The topically applied drug passes into and / or through the skin.

[0036] Thus, "transdermal" is widely used to refer to local, i.e., topical administration of drugs that act on the surface or within the skin, such as a wound patch used to treat acne, for example, and topical administration of drugs that diffuse through the skin and act systemically by entering the bloodstream. The term "drug" should be interpreted in this specification in its broadest sense to mean any agent intended to produce some therapeutic benefit. An agent may or may not be pharmaceutically active, but it becomes "bioactive" in the sense that it affects the human body. An agent can be used to treat or modify a condition, whether pathological, i.e., diseased, or not. In this specification, the terms "active", "drug", "bioactive substance", "preparation", "pharmaceutical", "therapeutic agent", "physiological agent" and "medicine" are used interchangeably and include substances for use in the diagnosis, cure, mitigation, arrest, treatment or prevention of a condition or disease state, or for affecting the structure or function of the body. This term includes skin wellness agents that perform functions such as softening and moisturizing. The term "treatment" is widely used and includes the prevention, modification, cure and control of a condition.

[0037] Examples of drugs include general anesthetics, hypnotics / analgesics, antipyretics, analgesic-antipyretics, anti-inflammatory drugs, steroidal anti-inflammatory drugs, stimulants / analgesics, anti-motion sickness drugs, psychotropic drugs, local anesthetics, skeletal muscle relaxants, autonomic drugs, anti-convulsants, anti-Parkinson drugs, anti-histamines, cardiac stimulants, anti-arrhythmic drugs, diuretics, antihypertensive drugs, vasoconstrictors, vasodilators, anti-atherosclerotic drugs, respiratory stimulants, antitussive and expectorant drugs, peptic ulcer drugs, collagenase, hormonal agents, urokinase agents, anti-asthma drugs, parasitic skin disease drugs, emollients, vitamins, inorganic preparations, hemostatic agents, anticoagulants, liver disease drugs, drug poisoning agents, gout preventives, anti-diabetic drugs, anti-cancer agents, radiopharmaceuticals, traditional Chinese medicines, antibiotics, chemotherapeutic agents, vermifuges / anti-protozoal agents, narcotics, etc.

[0038] Examples of cosmetic ingredients include whitening ingredients such as ascorbyl palmitate, kojic acid, lucinol, tranexamic acid, and oil-soluble licorice extract; anti-wrinkle agents such as retinol, retinoic acid, retinol acetate, and retinol palmitate; circulation-improving ingredients such as vitamin E, tocopherol acetate, capsaicin, and nonivamide; antibacterial ingredients such as isopropylmethylphenol; photosensitive elements, zinc oxide, and vitamins such as vitamin D 2 and vitamin D 3 and vitamins such as vitamin K are included.

[0039] The content of the drug or cosmetic ingredient in the pressure-sensitive adhesive for skin can be appropriately determined according to the type and purpose of use. The drug and cosmetic ingredient can also be encapsulated together with an absorption promoter, or a retention layer can be provided for the medical or cosmetic ingredient.

[0040] The pressure-sensitive adhesive can be made in the form of a device such as a medical tape, a medical patch, a medical sheet, a medical bandage, a transdermal patch, an industrial tape, an industrial sheet, or other forms known to those skilled in the art, either alone or together with an active substance. Various shapes and sizes of the device are conceivable.

[0041] Yet another aspect of the present invention relates to a device comprising a pressure-sensitive adhesive layer and a backing layer. In one embodiment, the device further comprises a release liner. In a preferred embodiment, the device is formed of a pressure-sensitive adhesive layer, a distal backing layer, and a proximal release liner.

[0042] The portion of the device not in contact with the skin is covered by a backing. The distal backing layer during use defines the side of the device that faces the surroundings, i.e., is distal to the skin. The backing serves to protect the device containing additional active contents from the environment by providing a non-permeable layer that prevents the adhesive and active substances (if present) from being lost to the surroundings. Thus, the material selected must be substantially impermeable to the active substance and the adhesive. Advantageously, the backing material can be made opaque to protect the contents from degradation due to exposure to light. Both non-porous films and porous films can be used as the backing substrate. This may be desirable as it reduces the moisture accumulating on the skin under the device and correspondingly reduces the amount of maceration of the skin that occurs, since a relatively high vapor transmission rate of the backing is desired. Conversely, an occlusive backing can be selected to enhance the active flux. Additionally, the backing layer must be able to bond to and support the other layers of the device, but since a hard backing can cause mechanical irritation, it must be flexible to accommodate the movement of the person using the device.

[0043] During long-term wear (e.g., for a period exceeding one day), it is also desirable for the backing to have a relatively high permeability to oxygen to maintain the health of the covered skin. Since the backing is in contact with the adhesive and possible active substances, it is important for the backing to be stable to such components in order to maintain its structural integrity and conformity. Also, it is desirable for the backing to be heat sealable at a relatively low temperature to other various polymer substrates.

[0044] The backing constituting the skin adhesive of the present invention is not subject to specific restrictions as long as it can support the adhesive layer. It has been found to be useful in drug delivery devices, and the backing that can be used in the practice of the present invention includes, with or without modification, metal foils, metallized poly foils, composite foils, or films containing materials of the polytetrafluoroethylene (TEFLON®) type or their equivalents, polyether block amide copolymers, polyurethanes, polyvinylidene chloride, nylon, silicone elastomers, rubber-based polyisobutylene styrene, styrene butadiene and styrene isoprene copolymers, polyethylene, polyester, and other such materials used in the field of transdermal drug delivery. Particularly preferred are thermoplastic polymers such as polyolefins, for example, polyethylene and polypropylene, and polyesters such as polyethylene terephthalate. To enhance the adhesiveness to the pressure-sensitive adhesive layer, the backing can be subjected to surface treatments such as corona treatment or plasma discharge treatment, or anchor coating treatment with an anchor agent.

[0045] The above-mentioned backing has a thickness of 10 to 100 μm, preferably 20 to 40 μm, so as not to cause discomfort at the site where the device is adhered to the skin.

[0046] Also, the above-mentioned backing is adjusted to have a tensile strength of 100 to 900 kg / cm 2 and a 100% elastic modulus of 10 to 100 kg / cm 2 to provide fine skin followability of the device for application to the skin.

[0047] The proximal release liner or the peelable film covers the side of the device facing the skin or the proximal side until the device is used. For such applications, a silicone-coated film is usually used. Immediately before using the device, the proximal release liner is removed to expose the pressure-sensitive adhesive layer for contact and adhesion to the skin surface. Therefore, the proximal release liner is adapted to be removed from the device, and it is necessary to peel the adhesive surface with a minimum force.

[0048] In one embodiment, the release liner of the first patch also functions as the backing layer of the second patch. With this design, the patches can be manufactured in a stacked form and administered to the patient in this way. The first patch is removed, applied to the skin, and no extra waste is generated for disposal.

[0049] The pressure-sensitive adhesive can be applied to the backing from an organic solution, an aqueous dispersion, or a melt. The matrix patch is a particularly preferred embodiment because it is easier to manufacture than the liquid reservoir patch and is more comfortable and easier to wear. The matrix patch device is a unit dosage form of the active substance in the pressure-sensitive adhesive. Generally, the device is in the form of a patch sized to deliver a preselected amount of the active substance through the skin. Surface areas in the range of 1 to 200 cm 2 are contemplated, and preferred sizes are 5, 10, 15, 20, 25, and 30 cm 2 . The thickness can vary over a wide range and is typically about 1 to about 5 mils, preferably 3 to 4 mils thick.

[0050] The device can be prepared using conventional methods. For example, the matrix device prepares a coating formulation by mixing a solution of the pressure-sensitive adhesive in a solvent with the active substance to form a uniform solution or suspension, and using well-known knife or bar or extrusion die coating methods, apply the adhesive to a substrate (backing or release liner), dry the coated substrate to remove the solvent, and laminate the exposed surface to a release liner or backing. Depending on the intended use of the device, the matrix may further contain the active substance.

[0051] The device of the present invention is arranged on the skin and can stay for a sufficient time to achieve or maintain the intended purpose. The time constituting the sufficient time can be selected by those skilled in the art in consideration of the flow rate of the device of the present invention and the state to be treated, for example, providing a diagnostic procedure or a therapeutic effect. Depending on the design of the patch and the state to be treated, the patch can remain on the skin for up to 1 hour or up to about 1 week. In one embodiment, the patch is designed to remain on the skin of the application site for at least 24 hours and up to 7 days. In another embodiment, the patch is designed to remain on the skin for up to 2 weeks or up to 1 month.

[0052] Generally, the device needs to adhere firmly to the skin for at least 24 hours after being attached to the skin, and in some cases, it needs to exceed 2 days, 3 days, 7 days, 14 days, 21 days, and even 30 days. Also, it is necessary to adhere without peeling off during sweating or bathing. In addition, when removing, it is necessary to be able to peel it off with a force that does not cause pain. If the adhesive force is too strong, it may cause hair loss, peeling of the cutin, or mechanical skin irritation by pulling the skin. As a result, this may cause erythema that can continue for several days after peeling, so it is necessary to minimize this inconvenience. Furthermore, it is important that no pressure-sensitive adhesive remains on the skin surface after the pressure-sensitive adhesive sheet is removed from the skin.

[0053] As will be apparent to those skilled in the art, many modifications and variations of the present invention can be made without departing from its spirit and scope. The specific embodiments described herein are provided by way of example only, and the present invention should be limited only by the terms of the appended claims and the full scope of equivalents to which such claims are entitled.

Examples

[0054] Example 1: Control Acrylic Polymer An initial charge containing 434 g of 2-ethylhexyl acrylate and 13 g of acrylic acid was prepared and slowly charged into a flask equipped with a stainless steel stirrer, thermometer, condenser, water bath, and additional funnel, containing 70 g of 2-ethylhexyl acrylate, 3 g of acrylic acid, 123 g of vinyl acetate, 84 g of heptane, and 90 g of ethyl acetate. The initial charge was heated to reflux with stirring for about 3 hours while adding AIBN slowly simultaneously. Heptane was added over several hours and refluxed for an additional 1 hour. Aluminum acetylacetonate, 2,4-pentanedione, toluene, and isopropanol were added. Finally, the contents were cooled, rinsed with isopropyl alcohol, and the cross-linked solids in the solution were examined.

[0055] Example 2: Acrylic Polymer Acrylic polymer samples A, B, C, and D were prepared in the same manner as the Example 1 control, but the amounts of 2-dimethylaminoethyl methacrylate (2-DMAEMA) and hydroxyethyl acrylate (HEMA), and maleic anhydride (MA) were varied. The weight percentages of the monomers directly replace the percentage of 2-ethylhexyl acrylate in the control sample.

[0056] [Table 1]

[0057] Example 3: Shear and Peel Adhesion Shear adhesion strength was measured according to PSTC No.107 using a mass of 1,000 grams (g) at room temperature. The bond area was 1 inch × 0.5 inch. The results are reported as the time required for the bond to fail.

[0058] The adhesive was applied to the substrate and changed as follows according to Test Method PSTC (Pressure Sensitive Tape Council, Northbrook, IL) 101, section 1.1.1. After wetting for 20 minutes or 24 hours, the peel adhesion at 180° between the backing and the substrate was measured. All tests were conducted at 22 °C and 50% relative humidity. The results reported in Table 2 are the average of three measurements.

[0059] Each polymer was separated and applied to a PET backing layer, and the shear performance and peel force of a stainless steel or VitroSkin® substrate were tested. The results are shown in Table 2.

[0060]

Table 2

[0061] The shear adhesion values of the B1, C1, and D1 samples in Table 2 are significantly higher than those of the control sample for both the stainless steel and Vitro-Skin® substrates. Adding HEMA and / or MA results in an improvement of about 4 to about 10 times that of the control. Also, for both the stainless steel and Vitro-Skin® substrates of Samples A, B, C, and D, the peel adhesion performance is equal to or better than that of the control sample. Peel adhesion depends on the wetting time of the substrate, the type of substrate, and the amounts of 2-DMAEMA, HEMA, and / or MA in the polymer.

[0062] Similarly, the polymer was applied to a Sontara® (Jacob-Holm) backing, and the shear force and peel force were tested with a stainless steel substrate. The results are shown in Table 3.

[0063]

Table 3

[0064] The shear and peel adhesion performance of Samples A, B, C, and D is also improved with Sontara® backing compared to the control.

Claims

1. An acrylic polymer prepared using (i) 1 to 10% by weight of a carboxy-functional monomer component, (ii) 50 to 90% by weight of a low Tg alkyl acrylate monomer component, (iii) 1 to 20% by weight of a tertiary amine-functionalized alkyl acrylate monomer component, (iv) up to 50% by weight of a vinyl ester monomer component, and (v) a hydroxy-functional monomer component, wherein (i) the carboxy-functional monomer component is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, β-carboxyethyl acrylate, and mixtures thereof; (ii) the low Tg alkyl acrylate monomer component is selected from the group consisting of methyl acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, decyl acrylate, dodecyl acrylate, and isomers and mixtures thereof; (iii) the tertiary amine-functionalized alkyl acrylate monomer component is 2-dimethylaminoethyl methacrylate; (iv) the vinyl ester monomer component is selected from the group consisting of vinyl acetate, vinyl benzoate, vinyl tert-butylbenzoate, vinyl chloroformate, vinyl cinnamate, vinyl decanoate, vinyl neodecanoate, vinyl pivalate, vinyl propionate, vinyl stearate, vinyl trifluoroacetate, vinyl valerate, and mixtures thereof; (v) the hydroxy-functional monomer component is an acrylic polymer selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and mixtures thereof.

2. The acrylic polymer according to claim 1, comprising (i) 1 to 10% by weight of acrylic acid, (ii) 50 to 90% by weight of 2-ethylhexyl methacrylate, (iii) 1 to 20% by weight of 2-dimethylaminoethyl methacrylate, and (iv) up to 50% by weight of vinyl acetate.

3. A pressure-sensitive adhesive composition comprising the acrylic polymer according to claim 1 or 2 and an additive selected from the group consisting of tackifiers, plasticizers, pigments, fillers, fluorescent agents, flow agents, wetting agents, surfactants, defoamers, rheology modifiers, penetration promoters, stabilizers, antioxidants, and mixtures thereof.

4. The pressure-sensitive adhesive composition according to claim 3, further comprising a pharmaceutical and / or nutraceutical active substance.

5. A product comprising the pressure-sensitive adhesive composition according to claim 3 or 4.

6. The product according to claim 5, which is a tape, a plaster, or a bandage.

7. a) forming a monomer mixture in a container using (i) a carboxy-functional monomer component in an amount of 1 to 10% by weight, (ii) a low Tg alkyl acrylate monomer component in an amount of 50 to 90% by weight, (iii) a tertiary amine-functionalized alkyl acrylate monomer component in an amount of 1 to 20% by weight, (iv) a vinyl ester monomer component in an amount of up to 50% by weight, and (v) a hydroxy-functional monomer component; b) adding a solvent and an initiator to the container; c) heating the container; d) separating the acrylic polymer, a method for forming the acrylic polymer according to claim 1 or 2.

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