Articles containing adhesive compositions that exhibit on-demand peel behavior

Abstract

An article comprising a first component having a first conductive surface and a second component having a second surface. An adhesive composition comprising a zwitterionic polymer is disposed between the first conductive surface and the second surface to bond the first component to the second component. The effort required to separate the first component from the second component, as measured by work of adhesion per surface area, is reduced by applying a DC potential across the adhesive composition.

Description

[Technical field]

[0001] The present invention relates generally to articles containing two or more components joined together by a pressure-sensitive adhesive that exhibits on-demand peel behavior, and more particularly to articles that can be separated into two or more components by applying an electric potential across the pressure-sensitive adhesive. [Background technology]

[0002] Adhesives, including pressure sensitive adhesives (PSAs), are commonly used in a variety of industries, including electronics, automotive, aerospace, abrasives, medical device, and packaging, to bond parts into assembled articles. The bond strength of the PSA between components in the article is important to achieve the desired performance characteristics for a particular application. In many applications, the PSA must exhibit high peel strength to prevent separation or delamination of the components during use. For example, PSAs may be used in the automotive industry to bond trim to the sides of an automobile or truck. In other applications, the PSAs must be reworkable or repositionable. Typically, such PSAs adhere more strongly to one component than to another, thus allowing for repositioning or replacement of the component to which the adhesive adheres more strongly. For example, PSAs may be used to bond protective covers to electronic devices such as cell phones, personal computers, or computer tablets. Due to the high cost of the article and the relatively low cost of the protective cover, it may be desirable to remove (peel) the cover to repair the article, modify the article, reposition the backing on the article, or recycle the bonded article. Summary of the Invention

[0003] There is a need for articles containing adhesive compositions that allow for controlling the timing of release and for influencing the surface to which the adhesive releases. The present disclosure provides articles including two or more components bonded together by a pressure-sensitive adhesive composition that exhibits on-demand release behavior upon application of a direct current (DC) potential, and methods for separating the components. The surface to which the adhesive composition releases can be influenced by the direction of the potential across the adhesive composition. The articles and methods described herein can be used, for example, in advanced manufacturing (e.g., to grip a part, transport the part to another location, and release the part on demand), device maintenance (e.g., to peel adhesively secured access panels), and / or recycling for economic or environmental benefits (e.g., to separate components that require different recycling processes).

[0004] In one embodiment, the present disclosure provides an article comprising a first component having a first conductive surface, a second component having a second surface, and an adhesive composition comprising a zwitterionic polymer disposed between the first conductive surface and the second surface, where the adhesive composition bonds the first component to the second component, and where the effort required to separate the first component from the second component, as measured by work of adhesion per surface area, is reduced by applying a DC potential across the adhesive composition.

[0005] In another embodiment, the present disclosure provides a method of separating components in a composite article, the method comprising applying a DC potential across an adhesive composition to cause a first component to separate from a second component.

[0006] As used herein, the term "zwitterionic polymer" or similar terms refers to a polymer having at least one anionic moiety and at least one cationic moiety covalently attached within a single polymer chain. The anionic and cationic moieties are positioned within the polymer backbone, pendant to the polymer backbone, or a mixture thereof. In some embodiments, the anionic and cationic moieties are randomly distributed within the polymer chain, while in other embodiments, the anionic and cationic moieties are present in an alternating, block, or other regular or semi-regular pattern within the polymer chain. In some embodiments, the anionic and cationic moieties are present in a 1:1 molar ratio within the polymer chain. In other embodiments, the anionic moieties are present in a molar excess relative to the cationic moieties within the polymer chain. In still other embodiments, the cationic moieties are present in a molar excess relative to the anionic moieties within the polymer chain. In some embodiments, there is a single anionic functional monomer covalently attached in the zwitterionic polymer, while in other embodiments, there is one or more anionic functional monomers covalently attached in the zwitterionic polymer. In some embodiments, there is a single cationic functional monomer covalently attached to the zwitterionic polymer, while in other embodiments there is one or more cationic functional monomers covalently attached to the zwitterionic polymer, and in some embodiments there is one or more nonionic moieties covalently attached to the zwitterionic polymer.

[0007] As used herein, the term "adhesive composition" refers to a PSA or a composite containing a PSA (e.g., a single- or double-sided tape) that includes a zwitterionic polymer and optionally one or more additional components blended together, which exhibits on-demand peel behavior when exposed to a DC potential. The term "on-demand peel" refers to the ability to reduce the strength of the adhesive bond at will in order to facilitate separation (i.e., peeling) of adhesively bonded components.

[0008] As used herein, a "pressure sensitive adhesive" is defined as having the following properties: (1) strong and permanent tack, (2) adhesion with no more than finger pressure, (3) sufficient ability to be held on a substrate, and (4) sufficient cohesive strength to be cleanly removed from a substrate. Materials that have been found to perform well as PSAs include polymers designed and formulated to exhibit the necessary viscoelastic properties that provide the desired balance of tack, peel adhesion, and shear retention. PSAs are typically characterized as being tacky at room temperature. PSAs are adhesives that meet the Dahlquist criteria for tack, which is an adhesive that has a shear storage modulus of typically 3×10 when measured at 25° C. and 1 Hertz (6.28 radians / sec). 5 Pa (300 kPa) or less. PSAs typically exhibit adhesive, cohesive, compliant, and elastic properties at room temperature.

[0009] As used herein, the terms "conductive" and "electrically conductive" are used interchangeably.

[0010] As used herein, the terms "negative electrode" and "negative adhesive interface" are used interchangeably, and the terms "positive electrode" and "positive adhesive interface" are used interchangeably.

[0011] As used herein, the term "polymerizable" refers to compounds, also referred to as "monomers," that are polymerizable and / or crosslinkable as a result of thermal, redox, or photolytic initiation. Such compounds have at least one site of α,β-unsaturation. In some embodiments, monomers having one or more sites of α,β-unsaturation are referred to as "crosslinkers," although it will be understood that the term "monomer" includes compounds having one or more such sites, as appropriate for the context.

[0012] As used herein, the terms "substantial" or "substantially" refer to relatively minor variations or aberrations from a specified property, value, range of values, content, formula, etc., and do not exclude the presence of additional materials, broader ranges of values, etc. that do not materially affect the desired properties of a given composition, article, product, or method.

[0013] As used herein, the term "comprising" and variations thereof do not have a limiting meaning when these terms appear in the specification and claims. Such terms will be understood to imply the inclusion of the specified step or element or group of steps or elements, but not the exclusion of any other step or element or group of steps or elements. "Consisting of" means to include and be limited to everything before the phrase "consisting of". Thus, the phrase "consisting of" indicates that the recited elements are necessary or mandatory, and that no other elements may be present. "Consisting essentially of" means to include any elements listed after the phrase, and any elements limited to other elements that do not interfere with or contribute to the activity or action specified in this disclosure with respect to those recited elements. Thus, the phrase "consisting essentially of" indicates that the recited elements are necessary or mandatory, but that other elements are optional and may or may not be present depending on whether they substantially affect the activity or action of the recited elements.

[0014] In this application, terms such as "a," "an," and "the" are not intended to refer to only a singular entity, but include general classes, specific examples of which may be used for illustration. The terms "a," "an," and "the" are used interchangeably with the phrases "at least one" and "one or more." The phrases "at least one of" and "including at least one of" following a list refer to any one of the items in the list, as well as any combination of two or more items in the list.

[0015] As used herein, the term "or" is generally used in its ordinary sense, including "and / or," unless the content clearly dictates otherwise. The term "and / or" refers to one or all of the listed elements or a combination of any two or more of the listed elements.

[0016] Also, all numbers herein are deemed to be modified by the term "about," and in certain embodiments, by the term "exactly." As used herein, in the context of a measured quantity, the term "about" refers to the variation in the measured quantity as would be expected by one of ordinary skill in the art making the measurement and exercising a level of care commensurate with the purpose of the measurement and the precision of the measuring device used. As used herein, a "up to" number (e.g., up to 50) is inclusive of that number (e.g., 50).

[0017] Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range, and the endpoints thereof (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0018] References throughout this specification to "several embodiments" mean that a particular feature, configuration, composition, or characteristic described with respect to an embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases in various places throughout this specification do not necessarily refer to the same embodiment of the present disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0019] The words "preferred" and "preferably" refer to embodiments of the present disclosure that may provide certain benefits, under particular circumstances, although other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[0020] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly illustrates exemplary embodiments. [Brief description of the drawings]

[0021] [Figure 1A] 1 is a schematic side view of one exemplary article of the present application. [Figure 1B] FIG. 1B is a schematic side view of a variation of the article of FIG. 1A. [Figure 1C] FIG. 1B is a schematic side view of another variation of the article of FIG. 1A. [Figure 2A] FIG. 2 is a schematic side view of another exemplary article of the present application. [Figure 2B] FIG. 2B is a schematic side view of a variation of the article of FIG. 2A. [Diagram 3] 1 is a plot of Example 1 tensile force (Newtons) (y-axis) versus distance (millimeters) (x-axis) between two 8 mm stainless steel plates separated at a rate of 0.01 mm / sec. [Figure 4] FIG. 1 is a contour surface plot of adhesion work per unit surface area (indicated by shading on scale) from the tensile adhesion tests of Example 1 as a function of applied DC voltage (x-axis) and the duration the voltage was applied before the plates were separated (y-axis).

[0022] When referring to the figures, like reference numbers when not multiples of 100 (e.g., 12 and 112 or 30 and 130) refer to like elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are selected for the purpose of illustrating different embodiments of the present invention. In particular, dimensions of the various components are described in illustrative terms only, and relationships between the dimensions of the various components should not be inferred from the drawings, unless otherwise indicated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In the following description of exemplary embodiments, reference is made to the accompanying drawings which form a part hereof, and in which specific embodiments are shown by way of illustration, It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0024] The articles of the present disclosure generally include a first component having a first conductive surface, a second component having a second surface, and an adhesive composition disposed between the first conductive surface and the second surface. The adhesive composition (described in more detail below) includes a pressure-sensitive adhesive comprising a zwitterionic polymer and, optionally, one or more additional components blended therewith, and exhibits on-demand peel behavior when exposed to a DC potential. For example, the effort required to separate the first component from the second component, as measured by the work of adhesion per surface area according to Test Method 1, is reduced by applying a DC potential across the adhesive composition.

[0025] The shape and form of the article in this disclosure is not particularly limited. The article may be a finished product or a part that is incorporated or attached to another object. The article is typically composed of at least two components that can be adhesively bonded to each other, and the article may be in the form of a two-dimensional or three-dimensional body. Similarly, the shape and form of the components that make up the article are not particularly limited. The components may be a single element or a combination of elements, and the components may be in the form of a two-dimensional or three-dimensional body. In some embodiments, two or more components are interconnected, or even two different parts of the same material are interconnected (e.g., one end of a composite strip of material may be folded over to be adhered to the opposite end of the strip).

[0026] To facilitate the separation of components bonded together by the adhesive composition, a DC potential is applied across the adhesive composition prior to separation of the components. For example, a potential may be applied across two conductive components on either side of the adhesive composition, such that one surface of the component acts as a negative electrode (or negative adhesive interface) and the other of the surfaces of the components acts as a positive electrode (or positive adhesive interface). Alternatively, a potential may be applied across one conductive component and a conductive adhesive carrier of a double-sided tape, such that the surface of the conductive component or the conductive adhesive carrier acts as a negative adhesive interface and the other of the conductive component or the conductive adhesive carrier acts as a positive adhesive interface. The application of a DC current typically weakens the adhesive bond at the negative adhesive interface, thus reducing the amount of effort required to separate the components in the article. The location of peeling can be reversed by simply changing the polarity of the potential.

[0027] FIG. 1 illustrates one embodiment of an article of the present disclosure, comprising two conductive components bonded together by an adhesive composition. Referring to FIG. 1A, the article 10 comprises a first component 12 having a first conductive surface 14 and a second component 22 having a second conductive surface 24. The first and second components 12 and 22 are each made of a conductive material. The nature of the conductive material is not particularly limited. In some embodiments, the first conductive surface 14 and the second conductive surface 24 are each selected from the group consisting of metals, mixed metals, alloys, metal oxides, composite metals, conductive plastics, conductive polymers, or combinations thereof. In some embodiments, the composition of the first conductive surface 14 is different from the composition of the second conductive surface 24. In other embodiments, the composition of the first and second conductive surfaces 14 and 24 is the same.

[0028] The adhesive composition 30 bonds the first and second components 12 and 22 to one another at the first conductive surface 14 and the second conductive surface 24. The adhesive composition exhibits on-demand peel behavior by applying a DC potential across the adhesive composition 30. In this particular embodiment, the first conductive surface 14 functions as a positive adhesive interface and the second conductive surface 24 functions as a negative adhesive interface. The application of a DC potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 22 from the first component 12. Preferably, little or no adhesive residue remains on the second conductive surface 24 after separation. In some embodiments, less than 10% (by weight), less than 5% (by weight), or less than 1% (by weight) of the adhesive composition remains on the second component 22 after separation. In some preferred embodiments, no adhesive composition remains on the second component 22 after separation. In some embodiments, the adhesive composition may be reusable, allowing the first component 12 to be rejoined to the second component 22, or to be adhered to an entirely different component or article. If it is desired that the adhesive remain on the second component 22 after separation, the polarity of the DC potential can be reversed, thereby causing the first conductive surface 14 to act as a negative adhesive interface.

[0029] Conductive components include components made entirely from conductive materials, as illustrated in FIG. 1A, and components made from non-conductive materials coated with conductive materials, as illustrated in FIG. 1B. Referring to FIG. 1B, the first component 12 includes a first non-conductive material 16 and a first conductive coating 18 to provide a first conductive surface 14. Similarly, the second component 22 includes a second non-conductive material 26 and a second conductive coating 28 to provide a second conductive surface 24. Alternatively (not shown), one of the components can be made entirely from a conductive material and the other can be made from a non-conductive material coated with a conductive material. The conductive coating may only partially coat the component, as illustrated in FIG. 1B, or may completely coat the exterior surface of the component. For the purposes of this disclosure, it is only necessary that the surface of the component that is in direct contact with the adhesive composition be coated sufficiently to weaken the adhesive bond at the negative adhesive interface when a DC potential is applied across the adhesive composition. In some embodiments, the coating is a solid layer. In other embodiments, the coating is pattern coated on the surface of the component. As mentioned above, the conductive material is not particularly limited and may include materials selected from the group consisting of metals, mixed metals, alloys, metal oxides, composite metals, conductive plastics, conductive polymers, or combinations thereof.

[0030] The adhesive composition 30 of FIG. 1B bonds the first and second components 12 and 22 together. The first conductive surface 14 serves as the positive adhesive interface and the second conductive surface 24 serves as the negative adhesive interface. Application of a DC potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 22 from the first component 12. If it is desired that the adhesive composition remain primarily on the second component, the polarity of the DC potential can be reversed, thereby causing the first conductive surface to serve as the negative adhesive interface.

[0031] The article of Figures 1A-B may further be adapted to bond and subsequently release non-conductive objects or elements using the adhesive composition, as illustrated in Figure 1C. The article of Figure 1C includes a conductive first component 12 having a first conductive surface 14 and a conductive second component 22 having a second conductive surface 24. The first and second components 12 and 22 are bonded together by an adhesive composition 30. The first and second components may be made of conductive materials, but it should also be understood that the first and / or second components may be made of non-conductive materials and coated with a conductive material, as illustrated in Figure 1B. Figure 1C differs from Figures 1A-B in that a first outer adhesive 50 is added to the second side 19 of the first component 12 opposite the adhesive composition 30, and a second outer adhesive 60 is added to the first side 29 of the second component 22 opposite the adhesive composition 30. The outer adhesives 50 and 60 may be the same or different, without particular limitation, so long as the outer adhesives 50 and 60 bond to non-conductive objects or elements and function for the intended application. In some embodiments, the outer adhesive is a pressure sensitive adhesive. In some further embodiments, the outer adhesive is an adhesive composition as defined herein. An optional release liner (not shown) may be applied to the first outer adhesive 50, the second outer adhesive 60, or both to protect the outer adhesives during transportation and storage of the article. In some embodiments, a release liner is applied to each of the first and second outer adhesives. In other embodiments, a release liner is applied to one of the outer adhesives for storage and transportation purposes, and the article is rolled on itself, so that the other outer adhesive is in direct contact with the release agent of the release liner. The adhesive composition can then be unrolled when ready for use. The release liner can be made of, for example, kraft paper, polyethylene, polypropylene, polyester, or a composite of any of these materials. These liners are preferably coated with a release agent, such as a fluorochemical or silicone. In some preferred embodiments, the liner is a paper, polyolefin film, or polyester film coated with a silicone release material.Examples of commercially available release liners include POLYSLIK™ silicone release paper available from Loparex (Cary, NC), Silicone 1750 coated film from Infiana (Forchheim, Germany), silicone treated polyethylene terephthalate film available from HP Smith Co. (Stoneham, MA), and 3M Scotchpak™ 9741 release liner from 3M Company (St. Paul, MN).

[0032] In the embodiment illustrated in FIG. 1C, the first and second components are two-dimensional bodies (e.g., sheets or multi-layer films). However, that is not required, and applications can be envisaged where either one or both of the components are three-dimensional bodies (e.g., special attachment features such as molded recesses for seating non-conductive objects). In practice, one of the optional release liners is removed from the first outer adhesive 50, and the first outer adhesive is adhered to a non-conductive object. The second optional release liner is then removed from the second outer adhesive 60, and the second outer adhesive 60 is adhered to a different non-conductive object, thus adhesively bonding the non-conductive objects. The non-conductive objects can be separated on demand by applying an electric potential across the adhesive composition, as illustrated in FIGS. 1A-B. In this case, separation results in one non-conductive object to which the first component is adhesively bonded, and another non-conductive object to which the second component is adhesively bonded.

[0033] FIG. 2 shows another embodiment of an article 110 of the present application, which is a double-sided tape in which an adhesive composition bonds first and second components together.

[0034] 2A, the article 110 includes a first component 112 having a first conductive surface 114 and a second component 122 having a second conductive surface 124. The first and second components can be made from conductive material(s) as illustrated in FIG. 2A, or one or both of the first and second components can be made from non-conductive material(s) and at least partially coated with conductive material(s), as described above with respect to FIG. 1. An adhesive composition 130 is disposed between the first conductive surface 114 and the second conductive surface 124 to bond the first component 112 to the second component 122.

[0035] The adhesive composition 130 is a double-sided adhesive that further includes a carrier 170 having a first major surface 172 and a second major surface 174 opposite the first major surface. A first adhesive composition 132 including a first zwitterionic polymer is on the first major surface 172 of the carrier 170. Similarly, a second adhesive composition 134 including a second zwitterionic polymer is on the second major surface 174 of the carrier 170. In some embodiments, the composition of the first zwitterionic polymer is the same as the composition of the second zwitterionic polymer. In other embodiments, the composition of the first zwitterionic polymer is different from the composition of the second zwitterionic polymer. A surface 136 of the first adhesive composition 132 opposite the carrier 170 is in contact with the first conductive surface 114 of the first component 112. A surface 138 of the second adhesive composition 134 opposite the carrier 170 is in contact with the second conductive surface 124 of the second component 122.

[0036] In some embodiments, the carrier is a porous material that allows physical contact between the first adhesive composition and the second adhesive composition. Exemplary carriers include paper, woven or nonwoven fabrics, porous films, metal meshes, metal grids, or combinations thereof. In some embodiments, the carrier is conductive. Such conductive carriers may be porous or nonporous and may include metal meshes, metal grids, metal foils, metal plates, conductive polymers, conductive foams, conductive tissues, or combinations thereof.

[0037] In the embodiment illustrated in FIG. 2A, the first conductive surface 114 functions as a positive adhesive interface and the second conductive surface 124 functions as a negative adhesive interface. When the carrier is made of a porous material, application of a DC potential 140 across the adhesive composition 130 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 124), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 122 from the first component 112. When it is desired to separate the adhesive composition from the first component, the polarity of the DC potential can be reversed, thereby causing the first conductive surface to function as a negative adhesive interface.

[0038] When the carrier of FIG. 2A is a nonporous conductive material, application of a DC potential 140 across the adhesive composition 130 can result in a negative adhesive interface (i.e., the second conductive surface 124) and a weakening of the adhesive bond at the first major surface 172 of the carrier 170.

[0039] In another embodiment, the carrier 170 is a conductive material that functions as either a positive or negative adhesive interface during the peeling process. For example, referring to FIG. 2B, the first conductive surface 114 of the first component 112 is the positive adhesive interface and the first major surface 172 of the carrier 170 is the negative adhesive interface. Application of a DC potential 140 across the first adhesive composition 132 results in separation of the first component 112 and the second component 122 at the first major surface 172 of the carrier 170. Alternatively, the first component 112 can be removed from the first adhesive composition 132 by reversing the polarity of the DC potential.

[0040] In an additional embodiment, the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be a negative adhesive interface, and the other of the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be a positive adhesive interface.

[0041] With reference to FIG. 2B, it should be understood that if the carrier 170 serves as the negative or positive adhesive interface and the first conductive surface 114 of the first component 112 serves as the other of the negative or positive adhesive interfaces, then only the first adhesive composition 132 to which the DC potential is applied needs to include a zwitterionic polymer. The second adhesive composition 134 can actually be any type of adhesive. Similarly, if the carrier 170 serves as the negative or positive adhesive interface and the second conductive surface 124 of the second component 122 serves as the other of the negative or positive adhesive interfaces, then only the second adhesive composition 134 to which the DC potential is applied needs to include a zwitterionic polymer. The first adhesive composition 132 can actually be any type of adhesive. Thus, in such an embodiment, a double-sided tape can be used to create an article that includes a carrier with adhesive on both sides, where only one of the adhesives includes a zwitterionic polymer. This structure would be similar to that illustrated in FIG. 1C, where the second component 22 is a carrier.

[0042] As indicated above, double-sided tapes with conductive carriers allow users to more strategically control the release location within an article, which can be particularly advantageous when the adhesive needs to be removed from a component prior to recycling and / or when the adhesive needs to remain on the component for repositioning or attachment to the same or a different article.

[0043] Furthermore, by using a double-sided tape with a conductive carrier, at least one of the components does not need to be conductive in order to separate a first component from a second component. The carrier can function as one of the electrodes, thus increasing the types of materials that can be included in an article (i.e., bonding two conductive components together, or bonding a conductive component to a non-conductive component).

[0044] The above embodiments illustrate exemplary configurations of the articles of the present disclosure, and methods of releasing components within these articles. The adhesive compositions, and in particular PSAs of the adhesive compositions, will now be described in more detail.

[0045] Adhesive Composition The adhesive compositions of the present disclosure include a zwitterionic polymer and, optionally, one or more additional components, including one or more of an adhesion promoter, a tackifier, a surfactant, a stain repellent, a thermal or oxidative stabilizer, a colorant, an adjuvant, a plasticizer, a solvent, a crosslinker, or mixtures thereof.

[0046] The zwitterionic polymers of the present disclosure are copolymers comprising an anionic monomer that is acrylic acid, methacrylic acid, a carboxylate thereof, or a blend thereof; a cationic monomer that is an acrylic or methacrylic acid ester having an alkyl ammonium functional group; and a polymerization product of an acrylic or methacrylic acid ester of an alcohol having 2 to 18 carbons. Optionally, one or more additional monomers are included in the zwitterionic polymers of the present disclosure. In some embodiments, the anionic monomer is acrylic acid or methacrylic acid, which is converted to the corresponding carboxylate by neutralization, either before or after polymerization. In some embodiments, the acrylic acid, methacrylic acid, or salts thereof are a mixture of two or more of these. In some embodiments, the acrylic or methacrylic acid ester is a mixture of two or more such esters, and in some embodiments, the cationic monomer is a mixture of two or more such cationic monomers.

[0047] In some embodiments, acrylic acid, methacrylic acid, carboxylates thereof, or blends thereof are present in the zwitterionic polymer in an amount of 0.2 wt % to 16 wt %, 0.2 wt % to 10 wt %, 1 wt % to 8 wt %, or 2 wt % to 6 wt %, based on the total weight of the zwitterionic polymer, or various intermediate levels, such as 2.3 wt %, 2.4 wt %, 2.6 wt %, 2.7 wt %, and all other such individual values ​​expressed in 0.1 wt % increments between 0.2 and 16.0 wt %, as well as ranges between any of these individual values ​​in 0.1 wt % increments, such as 0.2 wt % to 9.5 wt %, 1.9 wt % to 6.2 wt %, etc. These amounts also apply to the amount of unreacted acrylic acid, methacrylic acid, carboxylates thereof, or blends thereof in the prepolymer reaction mixture.

[0048] The cationic monomer is an acrylic or methacrylic acid ester containing alkylammonium functionality. In some embodiments, the cationic monomer is 2-(trialkylammonium)ethyl acrylate or 2-(trialkylammonium)ethyl methacrylate. In such embodiments, the nature of the alkyl group is not particularly limited, although cost and practicality may limit the number of useful embodiments. In some embodiments, the 2-(trialkylammonium)ethyl acrylate or 2-(trialkylammonium)ethyl methacrylate is formed from the reaction of 2-(dimethylamino)ethyl acrylate or 2-(dimethylamino)ethyl methacrylate with an alkyl halide, and in such embodiments, at least two of the three alkyl groups of the 2-(trialkylammonium)ethyl acrylate or 2-(trialkylammonium)ethyl methacrylate are methyl. In some embodiments, all three alkyl groups are methyl groups. In other embodiments, two of the three alkyl groups are methyl and the third is a linear, branched, cyclic, or alicyclic group having 2 to 24 carbon atoms, or 6 to 20 carbon atoms, or 8 to 18 carbon atoms, or 10 and 16 carbon atoms. In some embodiments, the cationic monomer is a mixture of two or more of these compounds.

[0049] The anion associated with the ammonium functionality of the cationic monomer is not particularly limited, and many anions are useful in connection with various embodiments of the present invention. In some embodiments, the anion is a halide anion, such as chloride, bromide, fluoride, iodide, and in some such embodiments, the anion is chloride. In other embodiments, the anion is BF4, N(SO2CF3)2, OSCF3, or OSCF9. In other embodiments, the anion is methyl sulfate. In yet other embodiments, the anion is hydroxide. In some embodiments, one or more cationic monomers comprise a mixture of two or more of these anions. In some embodiments, polymerization is carried out with 2-(dimethylamino)ethyl acrylate or 2-(dimethylamino)ethyl methacrylate, and the corresponding ammonium functionality is formed in situ by reacting the amino groups present in the polymer with a suitable alkyl halide to form the corresponding ammonium halide functionality. In other embodiments, the ammonium functional monomer is incorporated into the zwitterionic polymer, and then the anion is exchanged to provide a different anion. In such embodiments, ion exchange is carried out using any of the conventional processes known and commonly used by those of skill in the art.

[0050] In embodiments, the cationic monomer is present in the zwitterionic polymer in an amount of 2% to 25%, 2% to 20%, 4% to 16%, 8% to 16%, or 12% to 16% by weight based on the total weight of the zwitterionic polymer, or various intermediate levels, such as 3%, 5%, 6%, 8%, and all other such individual values ​​expressed in 1% by weight increments between 2 and 25%, as well as ranges between any of these individual values ​​in 1% by weight increments, such as 2% to 4%, 7% to 22%, 10% to 16%, etc. These amounts also apply to the amount of unreacted cationic monomer in the prepolymer reaction mixture.

[0051] In embodiments, the acrylic or methacrylic acid esters of alcohols having 2 to 18 carbons include acrylic or methacrylic acid esters of linear, branched, or cyclic alcohols. Non-limiting examples of alcohols useful for the acrylic or methacrylic acid esters include ethyl, propyl, n-butyl, sec-butyl, isobutyl, tert-butyl, hexyl, ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, undecyl, and dodecyl alcohols. In embodiments, the alcohol is isooctyl alcohol. In some embodiments, the acrylic or methacrylic acid esters of alcohols having 2 to 18 carbons are a mixture of two or more such compounds.

[0052] In embodiments, the acrylic or methacrylic acid ester of an alcohol having 2 to 18 carbons is present in the zwitterionic polymer in an amount of 50% to 95%, 60% to 90%, or 75% to 85% by weight based on the total weight of the zwitterionic polymer, or various intermediate levels, e.g., 51%, 52%, 53%, 54%, and all other such values ​​expressed individually in 1% weight increments between 50% and 95%, as well as ranges between any of these individual values ​​in 1% weight increments, e.g., about 54% to 81%, about 66% to 82%, about 77% to 79%, etc. These amounts also apply to the amount of unreacted acrylic or methacrylic acid ester of an alcohol having 8 to 12 carbons in the prepolymer reaction mixture.

[0053] In embodiments, the zwitterionic polymer of the present invention includes the polymerization product of one or more additional monomers. Such additional monomers are not particularly limited by structure, but may be selected to impart various desired properties to the resulting zwitterionic polymer. The additional monomers may include, in some embodiments, anionic functional monomers. Non-limiting examples of additional monomers are isobutyl acrylate, isobutyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, vinyl acetate, N-vinylpyrrolidone, hydroxyethyl acrylate, or hydroxyethyl methacrylate. In some embodiments, the additional monomer is a mixture of two or more of these monomers. In some such embodiments, the additional monomer is vinyl acetate.

[0054] The polymerization product of one or more additional monomers is present in the zwitterionic polymer in an amount of 0% to 40%, 0% to 30%, 2% to 20%, 3% to 15%, or 5% to 10% by weight based on the total weight of the zwitterionic polymer, or various intermediate levels, such as 1%, 3%, 4%, 5%, 6%, 7%, and all other such values ​​expressed individually in 1% increments between 0% and 40% by weight, as well as ranges between any of these individual values ​​in 1% increments, such as about 2% to 4%, about 11% to 28%, about 7% to 17%, etc. All such ranges preferably include 0%. These amounts also apply to the amount of unreacted additional monomer in the prepolymer reaction mixture.

[0055] In some embodiments, the additional monomer has two or more polymerizable functionalities, and such monomers are referred to as crosslinkers. Crosslinkers useful in forming zwitterionic polymers include, but are not limited to, diacrylates such as ethylene glycol diacrylate, hexanediol diacrylate, and tripropylene glycol diacrylate, triacrylates such as glycerol triacrylate and trimethylolpropane triacrylate, tetraacrylates such as erythritol tetraacrylate and pentaerythritol tetraacrylate, divinylbenzene, and derivatives thereof. In some embodiments, the crosslinker is a photoactive crosslinker. Photoactive crosslinkers include, for example, benzaldehyde, acetaldehyde, anthraquinone, substituted anthraquinones, various benzophenone-type compounds, and certain chromophore-substituted vinylhalomethyl-s-triazines such as 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine.

[0056] In some embodiments, the crosslinker is present as an additional monomer in an amount of up to 10% by weight based on the total weight of the zwitterionic polymer, and in other embodiments, the polymerization product of the crosslinker is present in the zwitterionic polymer at about 0% to 10% by weight, e.g., about 0.01% to 5% by weight, or about 0.1% to 2% by weight based on the total weight of the polymer. These amounts also apply to the amount of unreacted crosslinker in the prepolymer reaction mixture.

[0057] In some embodiments, the zwitterionic polymer of the present disclosure is a copolymer comprising the polymerization product of methacrylic acid, 2-(dimethylamino)ethyl acrylate, methyl chloride, and iso-octyl acrylate. Additionally, some embodiments include vinyl acetate.

[0058] Zwitterionic polymers can be made by the process of emulsion polymerization. An emulsion of monomers is formed and polymerization is carried out using UV or thermal initiation of the polymerization reaction. In some embodiments, air is partially excluded or restricted during polymerization. The emulsion can be a water-in-oil or oil-in-water emulsion. In some such embodiments, the emulsion is an oil-in-water emulsion and one or more monomers are stabilized in the bulk water phase by using one or more surfactants. In various embodiments, the surfactant is cationic, anionic, zwitterionic, or nonionic in nature, and the structure is not otherwise specifically limited. In some embodiments, the surfactant is also a monomer and becomes incorporated into the zwitterionic polymer. In other embodiments, the surfactant is present in the polymerization reaction vessel but is not incorporated into the cationic or zwitterionic polymer as a result of the polymerization reaction.

[0059] Non-limiting examples of anionic surfactants useful in forming oil-in-water emulsions of the monomers used to form the zwitterionic polymer include ammonium, sodium, lithium, or potassium lauryl sulfonate, dioctyl sodium sulfosuccinate, ammonium, sodium, lithium, or potassium perfluorobutanesulfonate, ammonium, sodium, lithium, or potassium perfluorooctane sulfonate, ammonium, sodium, lithium, or potassium perfluorooctanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium laureth sulfate, sodium lauroyl sarcosinate, sodium myreth sulfate, sodium pareth sulfate, ammonium, sodium, lithium, or potassium stearate, and combinations of one or more of the foregoing.

[0060] Non-limiting examples of nonionic surfactants useful in forming oil-in-water emulsions of the monomers used to form the zwitterionic polymers include block copolymers of ethylene oxide and propylene oxide, such as those sold under the tradenames PLURONIC®, KOLLIPHOR®, or TETRONIC® by BASF Corporation (Charlotte, NC); ethoxylates formed by the reaction of ethylene oxide with fatty alcohols, nonylphenol, dodecyl alcohol, and the like, including those sold under the tradename TRITON® by Dow Chemical Company (Midland, MI); oleyl alcohol; sorbitan esters; alkyl polyglycosides such as decyl glucoside; sorbitan tristearate, and combinations of one or more thereof.

[0061] Non-limiting examples of cationic surfactants useful in forming oil-in-water emulsions of the monomers used to form the cationic or zwitterionic polymers include benzalkonium chloride, cetrimonium bromide, demethyldioctadecyl ammonium chloride, lauryl methyl gluceto-10 hydroxypropyl diammonium chloride, tetramethyl ammonium hydroxide, monoalkyl trimethyl ammonium chloride, monoalkyl dimethyl benzyl ammonium chloride, dialkyl ethyl methyl ammonium ethosulfate, trialkyl methyl ammonium chloride, polyoxyethylene monoalkyl methyl ammonium chloride, and di-quaternary ammonium chlorides, ammonium functional surfactants sold under the trade names ETHOQUAD®, ARQUAD®, and DUOQUAD® by Akzo Nobel NV (Amsterdam, the Netherlands), and mixtures thereof. Of particular use in forming oil-in-water emulsions for the polymerization of the zwitterionic polymers of the invention are ETHOQUAD® surfactants, such as ETHOQUAD® C / 12, C / 25, C / 12-75, etc. In some embodiments, ETHOQUAD® C / 25 is usefully used to prepare high solids emulsions in water of the monomers used to make the zwitterionic polymers of the invention.

[0062] When a cationic surfactant is used in an oil-in-water emulsion polymerization reaction, it is used in an amount of about 1.0% to 6.0% by weight based on the total weight of monomer, or in an amount of about 2.0% to 4.0% by weight of monomer, or at various intermediate levels, such as 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.1%, 2.2%, and all other such values ​​expressed individually in 0.1% increments between 1.0 and 6.0%, as well as ranges between any of these individual values ​​in 0.1% increments, such as 2.3% to 4.6%, 4.5% to 4.7%, etc.

[0063] Non-limiting examples of zwitterionic surfactants useful for forming oil-in-water emulsions of the monomers used to form the zwitterionic polymer include betaines and sultaines such as cocamidopropyl betaine, hydroxysultaine, and cocamidopropyl hydroxysultaine; others include lecithin, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and sodium 2-[1-(2-hydroxyethyl)-2-undecyl-4,5-dihydroimidazol-1-ium-1-yl]acetate (sodium lauroamphoacetate). When a zwitterionic surfactant is used in an oil-in-water emulsion polymerization reaction, it is used in an amount of about 1.0% to 10.0% by weight based on the total weight of monomer, or in an amount of about 2.0% to 6.0% by weight of monomer, or at various intermediate levels, such as 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.1%, 2.2%, and all other such values ​​expressed individually in 0.1% increments between 1.0 and 10.0% by weight, as well as ranges between any of these individual values ​​in 0.1% increments, such as 2.3% to 4.6%, 4.5% to 4.7%, etc.

[0064] In some embodiments, the emulsion polymerization of the monomers used to make the zwitterionic polymers of the present invention is carried out by blending the monomers, surfactant, and UV initiator in water, followed by exposure to UV radiation of a wavelength corresponding to the preferred decomposition wavelength of the selected initiator for a period of time. In other embodiments, the emulsion polymerization of the monomers used to make the zwitterionic polymers of the present invention is carried out by blending the monomers, surfactant, and thermal initiator in water, followed by heating the emulsion to a temperature that induces decomposition of the thermal initiator at an appropriate rate. In some embodiments where methacrylic acid or acrylic acid is used in the monomer mixture, sodium, lithium, ammonium, or potassium hydroxide is added to the monomer mixture to neutralize the acid functionality to form the corresponding salt. In other embodiments, such neutralization is carried out after completion of the polymerization reaction. In embodiments, neutralization refers to adjusting the pH of the aqueous phase from about 2-3 to about 4-7, for example, about 5-6.

[0065] In some embodiments, ETHOQUAD® C / 25 is usefully used to make high solids emulsions of monomers. In this context, "solids" is defined as all components of the emulsion other than water. High solids emulsions are formed, for example, at about 15% and 60% total solids by weight in water, or about 25% to 60% total solids by weight in water, or about 30% to 50% solids by weight in water, or various intermediate levels, such as 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 26%, 27%, and all other such values ​​expressed individually in 1% increments between 15% to 60% by weight in water, as well as ranges between any of these individual values ​​in 1% increments, such as 23% to 46%, 45% to 57%, etc.

[0066] Generally, the emulsion polymerization and methodology conditions used are the same or similar to those used in conventional emulsion polymerization processes. In some embodiments, the oil-in-water emulsion polymerization is carried out using thermal initiation. In such embodiments, one useful polymerization initiator is V-50 (obtained from Wako Pure Chemical Industries, Ltd., Osaka, Japan). In some such embodiments, the temperature of the emulsion is adjusted to about 30° C. to 100° C., for example, about 40° C. to 80° C., or about 40° C. to 60° C., or about 45° C. to 55° C., before and during polymerization. Agitation of the emulsion at elevated temperature is carried out for a suitable time to decompose substantially all of the thermal initiator and react substantially all of the monomers added to the emulsion to form a polymerized emulsion. In some embodiments, the elevated temperature is maintained for about 2 hours to 24 hours, or about 4 hours to 18 hours, or about 8 hours to 16 hours. During the polymerization, in some embodiments, it is necessary to add additional thermal initiator to complete the reaction of substantially all of the monomer content added to the reaction vessel. It will be appreciated that completion of the polymerization is achieved by careful adjustment of the conditions, and standard analytical techniques, such as gas chromatographic analysis of residual monomer content, will inform one skilled in the art of the completion of the polymerization.

[0067] Coating Process The adhesive composition comprising the zwitterionic polymer and, optionally, one or more additional components, can be coated as an emulsion onto the surface of a component (e.g., a carrier, a substrate, a surface of an article, etc.). In some embodiments, the emulsified zwitterionic polymer is used as an adhesive composition at the end of the emulsion polymerization process and coated "as is" onto one or more components. In such embodiments, the water and one or more surfactants used in the polymerization will remain associated with the adhesive composition, along with any remaining unreacted monomers or initiators. The adhesive composition is coated and dried for a sufficient time to remove a substantial portion of the water, although in most embodiments, the surfactants used will remain in the dried coating, regardless of whether such surfactants react with the polymer and become part of the polymer. In some embodiments, drying of the emulsion also results in the removal of a portion or a substantial portion of any unreacted volatile monomers. In some embodiments, one or more additional components are added to the emulsion containing the zwitterionic polymer to form an adhesive composition, the modified emulsion is used to coat one or more components, and dried to remove a substantial portion of the water and a portion or a substantial portion of any other remaining volatile components. After drying, the emulsion adhesive composition desirably contains unreacted monomer in an amount of 1% by weight or less, for example, 0.5% by weight to 5 ppm, or about 500 ppm to 10 ppm, or about 100 ppm to 1 ppm, based on the total weight of monomer added to the emulsion polymerization reaction vessel.

[0068] The cationically emulsified adhesive composition of the present disclosure is characterized by excellent coating viscosity and high shear stability. In embodiments, the viscosity of the cationically stabilized adhesive composition of the present disclosure is about 20 cP to 2500 cP, or about 100 cP to 1500 cP, or about 400 cP to 1000 cP. The emulsion viscosity is determined in part by the solids content of the emulsion and the molecular weight of the zwitterionic polymer formed. The emulsion is stable under shear stress such that the onset of shear instability occurs at least about 80 Pa or more, such as about 90 Pa to 300 Pa or about 100 Pa to 200 Pa. The viscosity and shear stability of the cationically emulsified adhesive composition of the present disclosure provide wide flexibility in the selection of a coating method for coating the adhesive composition onto one or more components. Non-limiting examples of useful coating processes for use with the cationically emulsified adhesive compositions include knife coating, slot coating, die coating, flood coating, rod coating, curtain coating, spray coating, brush coating, dip coating, kiss coating, gravure coating, print coating operations (such as flexographic, inkjet, or screen print coating), etc. In some embodiments, the adhesive compositions are coated as a continuous coating, in other embodiments they are pattern coated as described in U.S. Pat. Nos. 4,798,201 and 5,290,615, or using another technique.

[0069] Coating of the emulsified adhesive composition is followed by drying using a suitable temperature and time for sufficient drying to remove a substantial portion of the water and any other volatile materials associated with the emulsion mixture.

[0070] In some embodiments, the adhesive composition has a thickness of at least 10 μm, at least 100 μm, at least 500 μm, or at least 1000 μm. In some embodiments, the adhesive composition has a thickness of up to 2 mm, up to 1000 μm, up to 500 μm, or up to 100 μm. In some embodiments, the adhesive composition has a thickness in the range of 10 μm to 2 mm.

[0071] In some embodiments, the adhesive composition comprises a zwitterionic polymer and, optionally, one or more additional components. In other embodiments, the adhesive composition is a single-sided tape comprising a carrier and a zwitterionic polymer and, optionally, one or more additional components applied to one side of the carrier. In yet other embodiments, the adhesive composition is a double-sided tape comprising a carrier and a first zwitterionic polymer and, optionally, one or more additional components applied to one side of the carrier and a second zwitterionic polymer and, optionally, one or more additional components applied to the opposite side of the carrier. The first and second zwitterionic polymers may be the same or different. Suitable carrier materials are described above.

[0072] Purpose The articles of the present disclosure can provide many advantages. Components in the article may be separated (i.e., peeled) on demand. As described above, on-demand peeling in the article occurs by applying a DC potential across the adhesive composition to cause weakening of the adhesive bond at the negative adhesive interface (i.e., the negative electrode), thus reducing the effort required to separate the components in the article. The weakening of the adhesive bond increases with increasing DC potential (voltage), increasing the duration of the applied DC potential, or a combination thereof. Thus, the user can tailor the conditions for on-demand peeling to the application or need. For example, the user can increase the duration of the applied DC potential if the application requires a lower voltage. In some embodiments, on-demand peeling occurs at an applied DC potential of up to 800V / mm, up to 250V / mm, or up to 90V / mm. In some embodiments, on-demand peeling occurs in less than 20 seconds, less than 15 seconds, less than 10 seconds, less than 5 seconds, less than 3 seconds, or less than 1.5 seconds after application of the applied DC potential.

[0073] The weakening of the adhesive bond can be measured, for example, by the % change in the work of adhesion per surface area of ​​two components bonded together with the adhesive composition. In some embodiments, the % change in the work of adhesion per surface area at 0V and 50V for 100 seconds is at least 10%, at least 15%, at least 20%, at least 30%, at least 40%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%. In some embodiments, the % change in the work of adhesion per surface area of ​​the components adhesively bonded to the article with the adhesive composition at 0V and 50V for 100 seconds is in the range of 10% to 100%, 10% to 99%, 40% to 99%, 60% to 99%, 70% to 99%, or 80% to 99%. In some embodiments, the DC applied potential is sufficient to completely detach the components from the article without user intervention.

[0074] Another related advantage of the article of the present application is the ability to determine the location of peeling by the direction of the potential applied across the adhesive composition. The adhesive composition of the present application typically peels from the negative adhesive interface. Preferably, little or no adhesive residue remains on the negative adhesive interface after separation. In some embodiments, less than 10% (by weight), less than 5% (by weight), or less than 1% (by weight) of the adhesive composition remains on the negative adhesive interface after peeling. In some preferred embodiments, no adhesive composition remains on the negative adhesive interface after peeling. This allows the user to cleanly separate the components at the optimal interface. In some constructions, it may be possible to peel the adhesive composition at one interface during the life of the article and at another interface at the end of the life of the article, as recycling and environmental regulations may require.

[0075] In addition, because the adhesive composition is a PSA as opposed to a curable adhesive, the peeled adhesive composition typically retains its tackiness and may be reused or repositioned as needed, and thus exhibits properties often attributed to PSAs having lower peel strength.

[0076] The articles of the present application can provide a variety of on-demand release solutions. In robotics, the articles may include a mechanical arm coated at one end with an adhesive composition for use in gripping an object (e.g., a component) used to perform various tasks. For example, the object may be a screwdriver or a soldering device. Once the task is completed, the object can be removed by applying an electrical potential across the adhesive composition. In some embodiments, the separation can be designed such that the adhesive composition remains on the mechanical arm to grip a new, different object.

[0077] The articles of the present application can be used, for example, in animal tracking collars, where researchers typically must sedate the animal during both application and removal of the collar. Using the articles of the present application, it is possible to create a collar designed to fall off at the end of its life cycle. For example, the collar can be secured around the animal's neck using an adhesive composition. A small battery used to collect tracking information can also be used near the end of the collection cycle to apply a potential across the adhesive composition, which would then detach the adhesive and allow the collar to fall to the ground. The collar can then be picked up by the researcher using a tracking device.

[0078] In another application, the article can be used in the packaging and shipping industry. The adhesive composition can be used to bind packages together. Upon arrival at the delivery destination, a shipping company employee can apply an electric current to separate the packages for delivery.

[0079] The article may also be part of a device or consumer product that includes one or more components that require periodic service or replacement. For example, a service panel may be adhesively bonded to a housing by an adhesive composition, and the panel may be removed by applying a DC applied potential across the adhesive composition. The panel may then be replaced after service, and in some embodiments, repositioned using the same adhesive composition that was originally applied during manufacture.

[0080] The article may also be a multi-component product that has reached the end of its product life cycle and at least some, if not all, of the components are recyclable. If the components are joined by an adhesive composition, it is possible to cleanly separate the recyclable components by applying a DC potential across the adhesive composition.

[0081] The above applications are not intended to be limiting, as the articles and methods of the present application may find use in any of a variety of applications that would benefit from on-demand adhesive release. EXAMPLES

[0082] The objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. These examples are merely for illustrative purposes and are not intended to limit the scope of the appended claims.

[0083] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and elsewhere in the specification are by weight. [Table 1]

[0084] Comparative Example C1 Preparation of Adhesive Formulation Containing Nonionic Polymer To a stirred reactor, deionized water (582.3 g), nonionic surfactant (Igepal CA-897, 17.1 g), and NVP (8.05 g) were added along with HDDA (0.31 g) and IOA (391.7 g). The ingredients in the reactor were stirred to produce an emulsion in the reactor. The resulting emulsion was passed twice through a Manton-Gaulin homogenizer. The homogenized emulsion was returned to the stirred reactor, deoxygenated, and heated to 60°C. Once the reaction reached 60°C, potassium persulfate (0.51 g) was added to the reactor. The start of the reaction was signaled by an exotherm and was allowed to proceed to a peak temperature of 90°C-98°C. The reaction was then allowed to cool to 70°C and held at that temperature for 2 hours. The mixture was then cooled and filtered to remove any coagulum. The filtered mixture had a solids content of approximately 40%.

[0085] Comparative Examples C2-C3 and Examples E1-E13 Preparation of Adhesive Formulations For each example, the ingredients DMAEA-MCl, IOA, C12-Acrylate, Vac, MAA, EQ-C25, IOTG, deionized water, and V-50 were charged sequentially to a clean 32 oz. reaction bottle using the amounts shown in Table 2. The mixture was purged with nitrogen for 2 minutes. The bottle was sealed and placed in a constant temperature water bath equipped with a rotator. The reaction bottle was heated to 50° C. for 18 hours with rotation. The reaction bottle was removed and cooled to room temperature. The reaction mixture was filtered through a screen. No coagulum was obtained. The reaction was then analyzed by gas chromatography (GC) to determine the % solids. The analysis revealed a conversion of over 99%.

[0086] Preparation of single layer transfer adhesive The adhesive formulations of Comparative Examples C1-C3 and Examples 1-12 were coated at a wet coating weight of 0.30 millimeters (mm) between silicone-treated PET release liners (RF02N / RF32N available from SKC Haas, Seoul, SK). The constructions were then dried in a solvent oven (Model LAC2-12-8, Despatch Thermal Processing Technology, Minneapolis, MN) at 65° C. for 10 minutes.

[0087] Preparation of double-sided coating adhesive with carrier layer The preparation of the double-sided coated adhesive on the tissue carrier layer was carried out in a similar manner to the preparation of the single layer transfer adhesive, with the following exceptions: The adhesive formulation of Example 13 was coated onto a siliconized PET liner at a thickness of 0.1 mm and dried in a solvent oven at 65°C for 10 minutes. The tissue material was then laminated to the dried adhesive. A second layer of the same adhesive formulation was coated onto the tissue side of the construction at a thickness of 0.1 mm and then dried in a solvent oven at 65°C for 10 minutes. [Table 2]

[0088] Test method 1: Work of adhesion per surface area with and without applied potential The work of adhesion per surface area required to separate two parallel bonded test surfaces was measured by separating the surfaces through the thickness of the bonded material at a specified removal rate.

[0089] The work of adhesion per surface area is expressed as Newtons per square centimeter of bonding surface multiplied by the distance traveled between the plates in centimeters (units: N / cm). It is calculated by integrating the area under the curve of tensile force (in Newtons (N)) plotted against the change in gap (in centimeters (cm)) between the bonding surfaces, and then multiplying that value by the contact area (in square centimeters (cm)) of the bonding test surfaces. 2 )) was analyzed.

[0090] Testing was performed using a strain-controlled rheometer (ARES G2, TA Instruments, New Castle, Delaware) equipped with an electrorheological accessory. The test fixture was a stainless steel parallel plate with a diameter of 8 mm. For temperature control, the bottom plate was mounted on a water-cooled Advanced Peltier System (APS, TA Instruments, New Castle, Delaware). For all adhesion tests, the temperature was regulated at 25 °C. For application of the potential, an arbitrary waveform generator (33210A, Keysight Technologies, Santa Rosa, California) was connected to a high voltage amplifier (Trek Model 609E-6, Trek Inc., Lockport, New York), which was connected to the upper geometry on the rheometer. The lower geometry was grounded. This allowed for the application of a potential ranging from 0 to ±4000 volts direct current (V DC) across the specimen between the rheometer plates.

[0091] For each test, an 8 mm diameter parallel plate fixture was attached to the rheometer with zero gap between the plates. 8 mm diameter disks were cut from the single layer transfer adhesive (C1-C3 and E1-E12) or double-sided coated adhesive (E13) and one of the release layers was peeled from the coated adhesive and applied to the clean surface of the lower geometry (8 mm diameter stainless steel plate) of the rheometer. The second release liner was peeled off from the coated adhesive. The temperature was equilibrated at 25°C for 1 minute. The top plate was then lowered and compressed in contact with the adhesive for 500 seconds with a compressive load of 5 N. During the compression process, a DC potential was applied at a voltage of either 0 V DC (control test) or -50 V DC during the final 100 seconds of compressive load. At the end of the compressive load, the plates were separated at a rate of 0.001 cm / s and the tensile force required to separate the plates was measured as a function of plate separation distance. Three tests were performed for each condition of each example and averaged to obtain the values ​​of adhesion work per surface area summarized in Table 3.

[0092] The percent (%) reduction in adhesion work per surface area was calculated by subtracting each average value at -50V DC applied potential from the corresponding average value with no voltage applied and then dividing the difference by the value with no voltage applied. A positive value for % reduction indicates a reduction in adhesion work per surface area after application of a -50V DC potential. These % reduction values ​​for each example are also recorded in Table 3.

[0093] In the examples tested, a negative DC potential resulted in preferential detachment from the top plate, while a positive DC potential resulted in preferential detachment from the bottom (ground) plate.

[0094] The tensile adhesion profile of Example 1 is illustrated in Figure 3. Tests were performed with DC potentials of 0V and -50V applied during the last 100 seconds of the compression step. The tensile force (Newtons) is plotted on the y-axis and the distance between 8 mm diameter stainless steel parallel plates separated at a rate of 0.01 mm / sec is plotted on the x-axis. The application of a potential reduces the adhesive bond strength as shown by a decrease in the work of adhesion (described by the area under the curve). [Table 3]

[0095] FIG. 4 shows a contour surface plot of the work of adhesion per unit surface area (indicated by the gray scale) from the tensile adhesion tests of Example 1 as a function of applied DC voltage (x-axis) and the duration that the voltage was applied before the plates were separated (y-axis).

[0096] Thus, the present disclosure provides, among other things, articles containing adhesive compositions that exhibit on-demand peel behavior. Various features and advantages of the present disclosure are set forth in the following claims.

Claims

1. a first component having a first conductive surface; a second component having a second surface; and an adhesive composition disposed between the first conductive surface and the second surface, the adhesive composition comprising a zwitterionic polymer; An article comprising: the adhesive composition bonds the first component to the second component; An article, wherein the effort required to separate the first component from the second component, as measured by work of adhesion per surface area, is reduced by applying a DC potential across the adhesive composition.

2. The zwitterionic polymer a. 0.2% to 16% by weight, based on the total weight of the polymer, of an anionic monomer comprising acrylic acid, methacrylic acid, a carboxylate salt thereof, or a mixture of two or more thereof, wherein the amount of carboxylate salt is based on the weight of the corresponding free acid; b. 2% to 25% by weight, based on the total weight of the polymer, of one or more cationic monomers, including acrylic or methacrylic acid esters, having alkylammonium functionality; c. 50% to 95% by weight, based on the total weight of the polymer, of one or more non-ionic monomers including acrylic or methacrylic acid esters of alcohols having 2 to 18 carbons; and d. 0% to 40% by weight, based on the total weight of the polymer, of one or more additional monomers; 10. The article of claim 1 consisting essentially of the polymerization product of

3. 3. The article of claim 2, wherein the acrylic or methacrylic acid ester containing an alkylammonium functional group is the reaction product of 2-(dimethylamino)ethyl acrylate or 2-(dimethylamino)ethyl methacrylate with an alkyl bromide or chloride having from 1 to 24 carbon atoms.

4. The article of claim 1 , wherein the first component comprises a first non-conductive material and a first conductive coating to provide the first conductive surface.

5. The article of claim 1 , wherein the second surface of the second component is a second conductive surface.

6. The adhesive composition comprises: a carrier having a first major surface and a second major surface opposite the first major surface; a first adhesive composition on a first major surface of the carrier, the first adhesive composition comprising a first zwitterionic polymer; a second adhesive composition on a second major surface of the carrier, the second adhesive composition comprising a second zwitterionic polymer; A double-sided adhesive comprising: a surface of the first adhesive composition opposite the carrier in contact with a first conductive surface of the first component; The article of claim 5 , wherein a surface of the second adhesive composition opposite the carrier is in contact with a second surface of the second component.

7. The article of claim 6 , wherein the carrier is a porous material.

8. The article of claim 6 , wherein the carrier is a conductive material.

9. the second surface of the second component is a non-conductive surface, and the adhesive composition is a carrier having a first major surface and a second major surface opposite the first major surface; a first adhesive composition on a first major surface of the carrier, the first adhesive composition comprising a first zwitterionic polymer; a second adhesive composition on a second major surface of the carrier, the second adhesive composition comprising a second zwitterionic polymer; A double-sided adhesive comprising: a surface of the first adhesive composition opposite the carrier in contact with a first conductive surface of the first component; a surface of the second adhesive composition opposite the carrier in contact with a second surface of the second component; The article of claim 1 , wherein the carrier is electrically conductive.

10. The article of claim 9 , wherein the carrier is a porous material.

11. 10. The article of claim 1, further comprising a first outer adhesive on the first component opposite the adhesive composition, a second outer adhesive on the second component opposite the adhesive composition, or a combination thereof.

12. 12. The article of any one of claims 1-11, wherein the effort required to separate the first component from the second component is at least 15% as measured by % change in work of adhesion per surface area in 100 seconds at 0V and 50V.

13. 10. The method for separating components in a composite article of claim 1, the method comprising applying a DC potential across the adhesive composition to cause the first component to separate from the second component.

14. 14. The method of claim 13, wherein the second surface of the second component is a second conductive surface, the first conductive surface or the second conductive surface functions as a negative electrode and the other of the first conductive surface or the second conductive surface functions as a positive electrode, the method further comprising applying a DC potential to peel the adhesive composition from the negative electrode and cause separation of the first component from the second component.

15. The adhesive composition comprises: a carrier having a first major surface and a second major surface opposite the first major surface; a first adhesive composition on a first major surface of the carrier, the first adhesive composition comprising a first zwitterionic polymer; a second adhesive composition on a second major surface of the carrier, the second adhesive composition comprising a second zwitterionic polymer; A double-sided adhesive comprising: a surface of the first adhesive composition opposite the carrier in contact with a first conductive surface of the first component; a surface of the second adhesive composition opposite the carrier in contact with a second surface of the second component; The carrier is conductive; The first conductive surface or the carrier functions as a negative electrode, and the other of the first conductive surface or the carrier functions as a positive electrode; 14. The method of claim 13, further comprising applying a DC potential to cause the adhesive composition to peel from the negative electrode and separation of the first component from the second component.

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