Articles containing adhesive compositions that exhibit on-demand peeling 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 generally relates to an article containing two or more components joined to each other by a pressure-sensitive adhesive exhibiting on-demand debonding behavior, and more particularly relates to an article that can be separated into two or more components by applying an electric potential across the pressure-sensitive adhesive. Background Art

[0002] Adhesives, including pressure-sensitive adhesives (PSA), are commonly used to bond components into assembled articles in various industries including the electronics, automotive, aerospace, abrasive, medical device, and packaging industries. The bond strength of PSA between components in an article is important to achieve desired performance characteristics for a particular application. In many applications, PSA must exhibit high peel strength to prevent separation or debonding of components during use. For example, PSA can be used in the automotive industry to bond trim to the side of an automobile or truck. In other applications, PSA must be reworkable or repositionable. Typically, such PSA adheres more strongly to one component than to another, thus allowing repositioning or replacement of the component to which the adhesive adheres more strongly. For example, PSA can be used to bond a protective cover to an electronic device such as a mobile phone, personal computer, or computer tablet. Due to the high cost of the article and the relatively low cost of the protective cover, it may be desirable to remove (peel off) the cover for repair of the article, modification of the article, repositioning of the backing on the article, or recycling of the bonded article. Summary of the Invention

[0003] Articles containing adhesive compositions capable of controlling the timing of delamination and influencing the surface from which the adhesive delaminates are needed. This disclosure provides articles comprising two or more components bonded together by a pressure-sensitive adhesive composition exhibiting on-demand delamination behavior upon application of a direct current (DC) potential, and methods for separating the components. The surface from which the adhesive composition delaminates may be influenced by the direction of the potential across the adhesive composition. Articles and methods described herein can be used, for example, in advanced manufacturing (e.g., to grasp parts, transport parts to another location, and release parts on demand), device maintenance (e.g., to delaminate adhesively fixed 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 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, wherein the adhesive composition bonds the first component to the second component, and the effort required to separate the first component from the second component, as measured by the bonding work per unit surface area, is reduced by applying a DC potential across the adhesive composition.

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

[0006] As used herein, the term “zwitterionic polymer” or similar terms means a polymer having at least one anionic moiety and at least one cationic moiety covalently bonded within a single polymer chain. The anionic and cationic moieties are appropriately positioned within the polymer backbone, pendanted to the polymer backbone, or are mixtures thereof. In some embodiments, the anionic and cationic moieties are randomly distributed within the polymer chain, while in other embodiments, they exist within the polymer chain in alternating patterns, block patterns, or other regular or semi-regular patterns. In some embodiments, the anionic and cationic moieties exist within the polymer chain in a 1:1 molar ratio. In other embodiments, the anionic moiety is present in a molar excess relative to the cationic moiety within the polymer chain. In yet another embodiment, the cationic moiety is present in a molar excess relative to the anionic moiety within the polymer chain. In some embodiments, a single covalently bonded anionic functional monomer is present in the zwitterionic polymer, while in other embodiments, one or more covalently bonded anionic functional monomers are present in the zwitterionic polymer. In some embodiments, a single cationic functional monomer is covalently bonded to the zwitterionic polymer, while in other embodiments, one or more cationic functional monomers are covalently bonded to the zwitterionic polymer. In some embodiments, one or more nonionic moieties are covalently bonded to the zwitterionic polymer.

[0007] As used herein, the term “adhesive composition” means a PSA or PSA-containing composite (e.g., single-sided or double-sided tape) comprising a zwitterionic polymer and one or more optional additional components blended together, which exhibit on-demand peel behavior when exposed to a DC potential. The term “on-demand peel” means the ability to freely reduce the strength of the adhesive bond for the purpose of facilitating the separation (i.e., peeling) of the adhesively bonded components.

[0008] As used herein, “pressure-sensitive adhesive” is defined as having the following properties: (1) strong and permanent tackiness, (2) adhesion under less than finger pressure, (3) sufficient ability to be retained on a substrate, and (4) sufficient cohesive strength to be cleanly removed from the substrate. Materials found to function well as PSAs include polymers designed and formulated to exhibit the necessary viscoelastic properties, resulting in a desired balance of tackiness, peel adhesion, and shear retention. PSAs are typically characterized by being tacky at room temperature. A PSA is an adhesive that meets the Dahlquist criteria for tackiness, which is typically a shear storage modulus of 3 × 10 when measured at 25°C and 1 Hz (6.28 radians / sec). 5 This means the pressure is below Pa (300 kPa). PSA typically exhibits adhesiveness, cohesiveness, conformability, and elasticity at room temperature.

[0009] In this specification, the terms "conductive" and "electrically conductive" are used interchangeably.

[0010] In this specification, 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” applies to compounds, also called “monomers,” that are polymerizable and / or crosslinkable as a result of initiation by thermal decomposition, oxidation-reduction reactions, or photodecomposition. Such compounds have at least one α,β-unsaturated moiety. In some embodiments, monomers having one or more α,β-unsaturated moieties are referred to as “crosslinkers,” but it will be understood that the term “monomer” appropriately includes compounds having one or more such moieties as appropriate in the context.

[0012] As used herein, the terms “substantial” or “substantially” mean relatively small variations or aberrations from the specified properties, values, ranges of values, content, formulas, etc., and do not preclude the presence of additional materials, broader ranges of values, etc., that do not substantially affect the desired properties of a given composition, article, product, or method.

[0013] In this specification, the terms “including” and their variations are not limited in meaning when they appear in the specification and claims. Such terms should be understood to suggest that they include one or more steps or elements specified, but not that any other one or more steps or elements, or any other group of steps or elements, is excluded. “Consisting of” means including and limiting to everything that precedes the phrase “consisting of.” Thus, the phrase “consisting of” indicates that the enumerated elements are necessary or essential, and that other elements cannot be present. “Essentially consisting of” means including all elements enumerated after the phrase, and any other elements that do not interfere with or contribute to the activity or action identified in this disclosure with respect to the enumerated elements. Thus, the phrase “essentially consisting of” indicates that the enumerated elements are necessary or essential, but the other elements are optional and may or may not be present, depending on whether they substantially affect the activity or action of the enumerated elements.

[0014] In this application, terms such as "a," "an," and "the" are not intended to refer only to singular entities, but include general classifications, and specific examples of such general classifications may be used for illustrative purposes. 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 an enumeration refer to any one item in the enumeration, and any combination of two or more items in the enumeration.

[0015] As used herein, the term "or" generally has the same meaning as "and / or" unless otherwise specified. The term "and / or" means one or all of the listed elements, or any combination of two or more of the listed elements.

[0016] Furthermore, in this specification, all numbers are considered to be modified by the term “about,” and in certain embodiments, by the term “exactly.” As used herein, in relation to a measured quantity, the term “about” refers to the variation of the measured quantity that can be predicted by a person skilled in the art who performs the measurement and exercises a level of care commensurate with the purpose of the measurement and the precision of the measuring instrument used. In this specification, the “maximum” number (e.g., maximum 50) includes that number (e.g., 50).

[0017] Furthermore, in this specification, the description of a numerical range by endpoints includes all numbers and their endpoints that are included within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0018] Throughout this specification, references to “several embodiments” mean that certain features, configurations, compositions, or properties described in relation to embodiments are included in at least one embodiment of this disclosure. Therefore, occurrences of such phrases in various places throughout this specification do not necessarily refer to the same embodiment of this disclosure. Furthermore, certain features, configurations, compositions, or properties may be combined in any preferred manner in one or more embodiments.

[0019] The terms “preferred” and “preferred” refer to embodiments of the disclosure that may provide a particular benefit under certain circumstances, but other embodiments may be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unhelpful, nor is it intended to exclude other embodiments from the scope of the disclosure.

[0020] The above summary of the present disclosure is not intended to describe each disclosed embodiment or all implementation forms of the present disclosure. The following description more specifically exemplifies exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Referring to the figures, like reference numerals (e.g., 12 and 112, or 30 and 130) after removing multiples of 100 indicate 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, the dimensions of various components are described only in illustrative terms, and the relationship between the dimensions of various components should not be inferred from the drawings unless otherwise indicated. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0023] In the following description of illustrative embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments. It should 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 article of the present disclosure generally includes a first component having a first electrically conductive surface, a second component having a second surface, and an adhesive composition disposed between the first electrically conductive surface and the second surface. The adhesive composition, described in more detail below, comprises a pressure-sensitive adhesive containing a zwitterionic polymer, and optionally one or more additional components blended therewith, and exhibits on-demand debonding behavior when exposed to a DC potential. For example, the effort required to separate the first component from the second component, 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 the present disclosure are not particularly limited. The article may be a finished product, or may be a component incorporated into 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 shape of a two-dimensional body or a three-dimensional body. Similarly, the shape and form of the components constituting the article are also not particularly limited. A component may be a single element or a combination of elements, and a component may be a two-dimensional body or a three-dimensional body. In some embodiments, two or more components are interconnected, or even two different portions of the same material are interconnected (e.g., one end of a composite strip of material may be folded over to adhere 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 before the components are separated. For example, the potential may be applied across two conductive components on either side of the adhesive composition such that the surface of one component acts as the negative electrode (or negative adhesive interface) and the other surface of the component acts as the positive electrode (or positive adhesive interface). Alternatively, the potential may be applied across one conductive component and a conductive adhesive carrier of the double-sided tape such that the surface of the conductive component or conductive adhesive carrier acts as the negative adhesive interface and the other surface of the conductive component or conductive adhesive carrier acts as the 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 delamination can be reversed simply by changing the polarity of the potential.

[0027] Figure 1 illustrates one embodiment of an article of the present disclosure comprising two conductive components joined together by an adhesive composition. Referring to Figure 1A, article 10 includes 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 from a conductive material. The properties of the conductive material are 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 compositions of the first and second conductive surfaces 14 and 24 are the same.

[0028] The adhesive composition 30 bonds the first and second components 12 and 22 to each other on 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 acts as the positive adhesive interface, and the second conductive surface 24 acts as the negative adhesive interface. Applying a DC potential 40 across the adhesive composition 30 results in weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, according to the adhesive work per unit surface area, and thus makes 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 can be reused, allowing the first component 12 to be rejoined to the second component 22, or to be bonded to a completely different component or article. If it is desirable for the adhesive to remain on the second component 22 after separation, the polarity of the DC potential can be reversed, thereby allowing the first conductive surface 14 to function as a negative adhesive interface.

[0029] The conductive components include components made entirely from a conductive material, as illustrated in Figure 1A, and components made from a non-conductive material coated with a conductive material, as illustrated in Figure 1B. Referring to Figure 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 may be made entirely from a conductive material, and the other components may be made from a non-conductive material coated with a conductive material. The conductive coating may partially coat the component, as illustrated in Figure 1B, or it may completely coat the outer surface of the component. For the purposes of this disclosure, it is only necessary that the surface of the component in direct contact with the adhesive composition when a DC potential is applied across the adhesive composition is sufficiently coated to weaken the adhesive bond at the negative adhesive interface. 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, conductive materials are not particularly limited and can be 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 in Figure 1B bonds the first and second components 12 and 22 to each other. The first conductive surface 14 acts as a positive adhesive interface, and the second conductive surface 24 acts as a negative adhesive interface. Applying a DC potential 40 across the adhesive composition 30 weakens the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, according to the adhesive work per unit surface area, thus making it easier to separate the second component 22 from the first component 12. If it is desirable that the adhesive composition remain mainly on the second component, the polarity of the DC potential can be reversed, thereby allowing the first conductive surface to act as a negative adhesive interface.

[0031] The articles in Figures 1A-B can be further adapted to bond non-conductive objects or elements using an adhesive composition, and then peel them off, as illustrated in Figure 1C. The article in 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 to each other by an adhesive composition 30. The first and second components may be made from conductive materials, but it should also be understood that the first and / or second components may be made from non-conductive materials and coated with conductive materials, 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 to the adhesive composition 30, and a second outer adhesive 60 is added to the first side 29 of the second component 22 opposite to the adhesive composition 30. The outer adhesives 50 and 60 may be the same or different, and are not particularly limited insofar as they bond to a non-conductive object or element and function for their intended use. 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. To protect the outer adhesive during transport and storage of the article, an optional release liner (not shown) may be applied to the first outer adhesive 50, the second outer adhesive 60, or both. In some embodiments, the 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 transport purposes, and the other outer adhesive is in direct contact with the release agent of the release liner by the article being rolled up on itself. The adhesive composition can then be unrolled when ready for use. The release liner may 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 paper, polyolefin film, or polyester film coated with a silicone release agent.Examples of commercially available release liners include POLYSLIK® silicone release paper from Loparex (Cary, NC), Silicone 1750 coated film from Infiana (Forchheim, Germany), silicone-treated polyethylene terephthalate film from HPSmith Co. (Stoneham, MA), and 3M Scotchpak® 9741 release liner from 3M Company (St. Paul, MN).

[0032] In the embodiment illustrated in Figure 1C, the first and second components are two-dimensional bodies (e.g., sheets or multilayer films). However, this is not mandatory, and applications can be considered where one or both of the components are three-dimensional bodies (e.g., special mounting functions such as molded recesses for seating nonconductive objects). In practice, one of the optional release liners is removed from the first outer adhesive 50, and the first outer adhesive is bonded to the nonconductive object. Then, a second optional release liner is removed from the second outer adhesive 60, and the second outer adhesive 60 is bonded to a different nonconductive object, thus bonding the nonconductive objects. The nonconductive objects can be separated on demand by applying a potential across the adhesive composition, as illustrated in Figures 1A-B. In this case, the separation yields one nonconductive object to which the first component is bonded, and the other nonconductive object to which the second component is bonded.

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

[0034] Referring to Figure 2A, 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 may be made from a conductive material(s) as shown in Figure 2A, or one or both of the first and second components may be made from a non-conductive material(s) and coated at least partially with a conductive material(s). The adhesive composition 130 is placed 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 further comprising a carrier 170 having a first main surface 172 and a second main surface 174 opposite to the first main surface. The first adhesive composition 132, comprising the first zwitterionic polymer, is located on the first main surface 172 of the carrier 170. Similarly, the second adhesive composition 134, comprising the second zwitterionic polymer, is located on the second main 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. The surface 136 of the first adhesive composition 132, opposite to the carrier 170, is in contact with the first conductive surface 114 of the first component 112. The surface 138 of the second adhesive composition 134, opposite to 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. Examples of 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 non-porous 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 Figure 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 from a porous material, the 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 adhesive work per unit surface area, thus making it easier to separate the second component 122 from the first component 112. If it is desirable to separate the adhesive composition from the first component, the polarity of the DC potential can be reversed, thereby allowing the first conductive surface to function as a negative adhesive interface.

[0038] When the carrier is a non-porous conductive material as shown in Figure 2A, applying a DC potential 140 across the adhesive composition 130 can result in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 124) and the first main 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 Figure 2B, the first conductive surface 114 of the first component 112 is a positive adhesive interface, and the first principal surface 172 of the carrier 170 is a negative adhesive interface. The application of a DC potential 140 across the first adhesive composition 132 results in the separation of the first component 112 and the second component 122 at the first principal 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 additional embodiments, the conductive surface 124 of the second component 122 or the second main 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 main surface 174 of the carrier 170 can be a positive adhesive interface.

[0041] Referring to Figure 2B, it should be understood that if carrier 170 functions as a negative or positive adhesive interface and the first conductive surface 114 of the first component 112 functions as the other negative or positive adhesive interface, then only the first adhesive composition 132 to which the DC potential is applied needs to contain a zwitterionic polymer. The second adhesive composition 134 can actually be any type of adhesive. Similarly, if carrier 170 functions as a negative or positive adhesive interface and the second conductive surface 124 of the second component 122 functions as the other negative or positive adhesive interface, then only the second adhesive composition 134 to which the DC potential is applied needs to contain a zwitterionic polymer. The first adhesive composition 132 can actually be any type of adhesive. Thus, in such embodiments, double-sided tape can be used to produce an article containing a carrier with adhesive on both sides, where only one side of the adhesive contains a zwitterionic polymer. This structure is considered to be similar to that illustrated in Figure 1C, where the second component 22 is the carrier.

[0042] As shown above, double-sided tapes with conductive carriers allow users to more strategically adjust the peeling position within an article. This can be particularly advantageous when adhesive needs to be removed from a component before recycling, and / or when adhesive needs to be left on a component for repositioning or bonding to the same or a different article.

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

[0044] The embodiments described above illustrate exemplary configurations of the articles of this disclosure and methods for removing components within these articles. Hereinafter, adhesive compositions, in particular the PSA of adhesive compositions, will be described in more detail.

[0045] Adhesive composition The adhesive compositions of this disclosure comprise a zwitterionic polymer and optionally one or more additional components. These additional components include one or more adhesion promoters, tackifiers, surfactants, antifouling agents, heat stabilizers or oxidation stabilizers, colorants, auxiliaries, plasticizers, solvents, crosslinking agents, or mixtures thereof.

[0046] The zwitterionic polymers of this disclosure are copolymers comprising anionic monomers which are acrylic acid, methacrylic acid, carboxylate salts thereof, or blends thereof; cationic monomers which are acrylic acid or methacrylic acid esters having alkylammonium functional groups; and polymerization products of acrylic acid or methacrylic acid esters of alcohols having 2 to 18 carbon atoms. One or more additional monomers of any choice are included in the zwitterionic polymers of the present invention. 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, acrylic acid, methacrylic acid, or salts thereof are mixtures of two or more of these. In some embodiments, the acrylic acid ester 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, their carboxylates, or blends thereof are present in the zwitterionic polymer in amounts ranging from 0.2% to 16% by weight, 0.2% to 10% by weight, 1% to 8% by weight, or 2% to 6% by weight, based on the total weight of the zwitterionic polymer, or various intermediate levels, such as 2.3% by weight, 2.4% by weight, 2.6% by weight, 2.7% by weight, and all other such individual values ​​expressed in 0.1% by weight increments between 0.2% and 16.0% by weight, as well as ranges between any of these individual values ​​in 0.1% by weight increments, such as 0.2% to 9.5% by weight, 1.9% to 6.2% by weight, etc. These amounts also apply to the amount of unreacted acrylic acid, methacrylic acid, their carboxylates, or blends thereof in the prepolymer reaction mixture.

[0048] The cationic monomer is an acrylic acid ester 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 properties of the alkyl group are not particularly limited, but the number of useful embodiments may be limited by cost and practicality. In some embodiments, 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, in such embodiments, at least two of the three alkyl groups of 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 groups, 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 anions associated with the ammonium functionality of cationic monomers are not particularly limited, and many anions are useful in relation to various embodiments of the present invention. In some embodiments, the anion is a halide anion such as a chloride, bromide, fluoride, or iodide, and in some such embodiments, the anion is a chloride. In other embodiments, the anion is BF4, N(SO2CF3)2, O3SCF3, or O3SC4F9. In other embodiments, the anion is a methyl sulfate. In yet another embodiment, the anion is a 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 using 2-(dimethylamino)ethyl acrylate or 2-(dimethylamino)ethyl methacrylate, and the corresponding ammonium functionality is formed in situ by the reaction of the amino group 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 a zwitterionic polymer, and then the anions are exchanged to yield different anions. In such embodiments, ion exchange is carried out using any of the conventional processes known to those skilled in the art and commonly used by those skilled in the art.

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

[0051] In embodiments, the acrylic or methacrylic esters of alcohols having 2 to 18 carbon atoms include acrylic or methacrylic esters of linear, branched, or cyclic alcohols. Examples of alcohols useful for acrylic or methacrylic esters, but not limited to them, 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 esters of alcohols having 2 to 18 carbon atoms are mixtures of two or more such compounds.

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

[0053] In some embodiments, polymerization products of one or more additional monomers are included in the zwitterionic polymer of the present invention. Such additional monomers are not particularly limited by their structure but may be selected to impart various desired properties to the resulting zwitterionic polymer. Examples of additional monomers in some embodiments include 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] Polymerization products of one or more additional monomers are present in the zwitterionic polymer in amounts of 0% to 40% by weight, 0% to 30% by weight, 2% to 20% by weight, 3% to 15% by weight, or 5% to 10% by weight, based on the total weight of the zwitterionic polymer, or various intermediate levels, e.g., 1% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, and all other such values ​​expressed individually in 1% by weight increments between 0% to 40% by weight, as well as ranges between any of these individual values ​​in 1% by weight increments, e.g., about 2% to 4% by weight, about 11% to 28% by weight, about 7% to 17% by weight, etc. All such ranges preferably include 0%. These amounts also apply to the amount of unreacted additional monomers in the prepolymer reaction mixture.

[0055] In some embodiments, additional monomers have two or more polymerizable functionalities, and such monomers are referred to as crosslinking agents. Crosslinking agents useful in the formation of 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 its derivatives. In some embodiments, the crosslinking agent is a photoactive crosslinking agent. Examples of photoactive crosslinking agents include benzaldehyde, acetaldehyde, anthraquinone, substituted anthraquinone, various benzophenone-type compounds, and certain chromophore-substituted vinyl halomethyl-s-triazines such as 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine.

[0056] In some embodiments, the crosslinking agent 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 crosslinking agent is present in the zwitterionic polymer in an amount of about 0% to 10% by weight based on the total weight of the polymer, for example, about 0.01% to 5% by weight or about 0.1% to 2% by weight. These amounts also apply to the amount of unreacted crosslinking agent in the prepolymer reaction mixture.

[0057] In some embodiments, the zwitterionic polymers of the present disclosure are copolymers comprising polymerization products of methacrylic acid, 2-(dimethylamino)ethyl acrylate methyl chloride, and iso-octyl acrylate. In addition, some embodiments include vinyl acetate.

[0058] Zwitterionic polymers can be produced by an emulsion polymerization process. 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 may 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 aqueous phase by using one or more surfactants. In various embodiments, the surfactant is essentially cationic, anionic, zwitterionic, or nonionic, and its structure is not particularly 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 for forming oil-in-water emulsions of monomers used to form zwitterionic polymers include ammonium, sodium, lithium, or potassium salts of lauryl sulfonic acid, sodium dioctyl sulfosuccinate, ammonium, sodium, lithium, or potassium salts of perfluorobutanesulfonic acid, ammonium, sodium, lithium, or potassium salts of perfluorooctanesulfonic acid, ammonium, sodium, lithium, or potassium salts of perfluorooctanoic acid, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium laureth sulfate, sodium lauroyl sarcosinate, sodium myreth sulfate, sodium pareth sulfate, ammonium, sodium, lithium, or potassium salts of stearate, and one or more combinations thereof.

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

[0061] Non-limiting examples of cationic surfactants useful for forming oil-in-water emulsions of monomers used to form cationic or zwitterionic polymers include benzalkonium chloride, cetrimonium bromide, demethyldioctadecylammonium chloride, laurylmethylglucet-10 hydroxypropyldiammonium chloride, tetramethylammonium hydroxide, monoalkyltrimethylammonium chloride, monoalkyldimethylbenzylammonium chloride, dialkylethylmethylammonium ethosulfate, trialkylmethylammonium chloride, polyoxyethylene monoalkylmethylammonium chloride, and di-quaternary ammonium chloride, as well as ammonium functional surfactants sold by Akzo Nobel NV (Amsterdam, the Netherlands) under the trade names ETHOQUAD®, ARQUAD®, and DUOQUAD®, and mixtures thereof. In forming oil-in-water emulsions for the polymerization of the zwitterionic polymers of the present invention, particularly useful are ETHOQUAD® surfactants, such as ETHOQUAD® C / 12, C / 25, C / 12-75, etc. In some embodiments, ETHOQUAD® C / 25 is usefully used to produce high-solids emulsions in water of monomers used to produce the zwitterionic polymers of the present invention.

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

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

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

[0065] In some embodiments, ETHOQUAD® C / 25 is usefully used to produce 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, with total solids of about 15% and 60% by weight in water, or total solids of about 25% to 60% by weight in water, or solids of about 30% to 50% by weight in water, or various intermediate levels, e.g., 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 26% by weight, 27% by weight, and all other such values ​​expressed individually in 1% by weight increments between 15% and 60% by weight in water, as well as ranges between any of these individual values ​​in 1% by weight increments, e.g., 23% to 46% by weight, 45% to 57% by weight, etc.

[0066] Generally, the conditions of the emulsion polymerization and methodology used are the same as or similar to those used in conventional emulsion polymerization methods. In some embodiments, oil-in-water emulsion polymerization is carried out using a thermal initiation reaction. In such embodiments, one useful polymerization initiator is V-50 (available from Wako Pure Chemical Industries, Ltd. (Osaka, Japan)). In some such embodiments, the emulsion temperature is adjusted to about 30°C to 100°C before and during polymerization, for example, about 40°C to 80°C, or about 40°C to 60°C, or about 45°C to 55°C. Stirring of the emulsion at high 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 high 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 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. The completion of polymerization is achieved through careful adjustment of conditions, and it will be understood that standard analytical techniques, such as gas chromatography analysis of residual monomer content, will inform those skilled in the art of the completion of polymerization.

[0067] Coating process Adhesive compositions comprising a zwitterionic polymer and optionally one or more additional components can be coated as emulsions onto the surface of components (e.g., carriers, substrates, surface of articles, 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 polymerization will remain bound to the adhesive composition along with any residual unreacted monomers or initiators. The adhesive composition is coated and dried for a sufficient amount of time to remove substantial portions of the water, although in most embodiments, the surfactants used will remain in the dried coating, 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 some or substantial portions 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, and one or more components are coated with the modified emulsion and dried to remove substantial portions of the water and some or substantial portions of any other residual volatile components. After drying, the emulsion adhesive composition preferably contains unreacted monomers at a concentration of 1% by weight or less, for example, 0.5% to 5 ppm, or about 500 ppm to 10 ppm, or about 100 ppm to 1 ppm, based on the total weight of monomers added to the emulsion polymerization reaction vessel.

[0068] The cationically emulsified adhesive composition of the present invention 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 partially determined by the solid content of the emulsion and the molecular weight of the formed zwitterionic polymer. The emulsion is stable under shear stress such that the onset of shear instability occurs at least about 80 Pa or higher, for example, 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 a wide range of flexibility in the selection of a coating method for coating the adhesive composition onto one or more components. Useful coating processes for which cationically emulsified adhesive compositions are used include, but are not limited to, knife coating, slot coating, die coating, flood coating, rod coating, curtain coating, spray coating, brush coating, dip coating, kiss coating, gravure coating, and printing coating operations (such as flexographic, inkjet, or screen print coating). In some embodiments, the adhesive compositions are coated as a continuous coating, and in other embodiments, they are pattern coated as described in U.S. Patents No. 4,798,201 and No. 5,290,615, or using other techniques.

[0069] Following the coating of the emulsified adhesive composition, drying is carried out using an appropriate temperature and time for sufficient drying to remove substantial portions of water and any other volatile substances associated with the emulsion mixture.

[0070] In some embodiments, the thickness of the adhesive composition is at least 10 μm, at least 100 μm, at least 500 μm, or at least 1000 μm. In some embodiments, the thickness of the adhesive composition is up to 2 mm, up to 1000 μm, up to 500 μm, or up to 100 μm. In some embodiments, the thickness of the adhesive composition is 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 another embodiment, 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 this disclosure can offer many advantages. Components in the article may be separated (i.e., peeled) on demand. As described above, on-demand peeling in an 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., negative electrode), thus reducing the effort required to separate components in the article. 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 applied DC potentials of up to 800 V / mm, up to 250 V / mm, or up to 90 V / mm. In some embodiments, on-demand peeling occurs 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 the application of the applied DC potential.

[0073] The weakening of the adhesive bond can be measured, for example, by the change in the percentage of adhesive work per surface area of ​​two components bonded together by the adhesive composition. In some embodiments, the percentage change in adhesive work per surface area over 100 seconds at 0V and 50V 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, over 100 seconds at 0V and 50V, the percentage change in adhesive work per surface area of ​​components bonded to an article using the adhesive composition 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 applied DC potential is sufficient to completely decouple the components from the article without user intervention.

[0074] Another relevant advantage of the articles of this application is the ability to determine the location of delamination by the direction of the potential applied across the adhesive composition. The adhesive compositions of this application typically delaminate from the negative adhesive interface. Preferably, little to 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 delamination. In some preferred embodiments, no adhesive composition remains on the negative adhesive interface after delamination. This allows the user to cleanly separate the components at the optimal interface. In some structures, it may be possible to delaminate the adhesive composition at one interface during the lifespan of the article and at another interface at the end of the article's lifespan, as recycling and environmental regulations may require.

[0075] In addition, since 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, thus exhibiting properties often resulting from the lower peel strength of the PSA.

[0076] The articles of this application can provide various on-demand peeling 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 complete, the object can be removed by applying an electric potential across the adhesive composition. In some embodiments, the separation may be designed such that the adhesive composition remains on the mechanical arm to grip a new and different object.

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

[0078] In other applications, the goods can be used in the packaging and transportation industries. The adhesive composition can be used to bundle packages together. Upon arrival at the delivery destination, transportation workers 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 requiring periodic service or replacement. For example, a service panel may be bonded to a housing with 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, it may be repositioned using the same adhesive composition that was initially applied during manufacturing.

[0080] The article may also be a multi-component product that has reached the end of its product lifecycle, and at least some, if not all, of its components are recyclable. If the components are bonded together by an adhesive composition, the recyclable components can be cleanly separated by applying a DC potential across the adhesive composition.

[0081] The uses described above are not intended to be limiting. The articles and methods of this application may find use in any variety of applications that benefit from on-demand adhesive removal. [Examples]

[0082] The objects and advantages of the present invention are further illustrated by the following embodiments, but the specific materials and their quantities, as well as other conditions and details described in these embodiments, should not be construed as unduly limiting the invention. These embodiments are for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0083] Unless otherwise stated, all parts, percentages, ratios, etc., in the examples and elsewhere in this specification are based on weight. [Table 1]

[0084] Comparative Example C1: Preparation of an adhesive formulation containing a nonionic polymer. Deionized water (582.3 g), a nonionic surfactant (Igepal CA-897, 17.1 g), and NVP (8.05 g) were added to a stirred reactor along with HDDA (0.31 g) and IOA (391.7 g). The components in the reactor were stirred to form an emulsion. 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. When the reaction reached 60°C, potassium persulfate (0.51 g) was added to the reactor. The reaction was initiated by exothermic reaction and proceeded to a peak temperature of 90°C to 98°C. The reaction was then cooled to 70°C and held at that temperature for 2 hours. The mixture was then cooled and filtered to remove all solids. The filtered mixture had a solid content of approximately 40%.

[0085] Comparative Examples C2-C3 and Examples E1-E13: Preparation of Adhesive Formulations In each example, the components DMAEA-MCl, IOA, C12-acrylate, Vac, MAA, EQ-C25, IOTG, deionized water, and V-50 were sequentially added to a clean 32-ounce reaction bottle in 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 rotating device. The reaction bottle was heated to 50°C for 18 hours while rotating. The reaction bottle was removed and allowed to cool to room temperature. The reaction mixture was filtered through a screen. No coagulation was obtained. The reactants were then analyzed by gas chromatography (GC) to determine the solids content percentage. The analysis revealed a conversion rate of over 99%.

[0086] Preparation of single-layer transfer adhesive The adhesive formulations of Comparative Examples C1-C3 and Examples 1-12 were coated between silicone-treated PET release liners (RF02N / RF32N, available from SKC Haas (Seoul, SK)) to a wet coating weight of 0.30 mm. The structure was 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 a carrier layer The preparation of the double-sided coating adhesive on the tissue carrier layer was carried out in the same manner as the preparation of the single-layer transfer adhesive, with the following exceptions. The adhesive formulation of Example 13 was coated to a thickness of 0.1 mm onto a silicone-treated PET liner and dried in a solvent oven at 65°C for 10 minutes. The tissue material was then laminated onto the dried adhesive. A second layer of the same adhesive formulation was coated to a thickness of 0.1 mm onto the tissue side of the structure and then dried in a solvent oven at 65°C for 10 minutes. [Table 2]

[0088] Test Method 1: Bonding work per unit surface area with and without applied potential. The amount of bonding work per unit surface area required to separate two parallel bonded test surfaces was measured while separating the surfaces in the thickness direction of the bonding material at a specific removal rate.

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

[0090] The tests were performed using a strain-controlled rheometer (ARES G2, TA Instruments, New Castle, Delaware) equipped with an electroviscosity accessory. The test fixture was an 8mm diameter stainless steel parallel plate. For temperature control, the bottom plate was mounted on a water-cooled Advanced Peltier System (APS, TA Instruments, New Castle, Delaware). The temperature was adjusted to 25°C for all adhesion tests. For potential application, 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 then connected to the upper shape on the rheometer. The lower shape was grounded. This allowed for the application of a direct current (V DC) potential in the range of 0 to ±4000 volts across the test specimen between the rheometer plates.

[0091] In each test, parallel plate fixtures with a diameter of 8 mm were attached to the rheometer, and the gap between the plates was made zero. An 8 mm diameter disc was cut from either a single-layer transfer adhesive (C1-C3 and E1-E12) or a double-sided coating adhesive (E13), one of the release layers was peeled off the coating adhesive, and applied to the clean surface of the lower shape of the rheometer (an 8 mm diameter stainless steel plate). A second release liner was peeled off the coating adhesive. The temperature was equilibrated at 25°C for 1 minute. The upper 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 either 0 V DC (control test) or -50 V DC during the last 100 seconds of compression loading. At the end of the compression loading, the plates were separated at a speed of 0.001 cm / s, and the tensile force required to separate the plates was measured as a function of the plate separation distance. Three tests were conducted for each condition in each example, and the average values ​​for adhesive work per surface area, summarized in Table 3, were obtained.

[0092] The percentage reduction in adhesive work per surface area was calculated by subtracting the respective average value at a -50V DC applied potential from the corresponding average value without applied voltage, and then dividing the difference by the value without applied voltage. A positive percentage reduction indicates a decrease in adhesive work per surface area after the application of a -50V DC potential. These percentage reduction values ​​for each example are also recorded in Table 3.

[0093] In the tested examples, a negative DC potential resulted in preferential delamination from the upper plate, while a positive DC potential resulted in preferential delamination from the lower (ground) plate.

[0094] The tensile bonding profile of Example 1 is illustrated in Figure 3. The test was performed at DC potentials of 0V and -50V applied during the last 100 seconds of the compression process. The tensile force (Newtons) is plotted on the y-axis, and the distance between 8 mm diameter parallel stainless steel plates separated at a speed of 0.01 mm / sec is plotted on the x-axis. The application of potential reduces the bonding strength of the adhesive, as indicated by the decrease in bonding work (explained by the area under the curve). [Table 3]

[0095] Figure 4 shows a contour surface plot of the bonding work per unit surface area (shown by grayscale) from the tensile bonding test of Example 1 as a function of the applied DC voltage (x axis) and the duration of voltage application before separating the plates (y axis).

[0096] Accordingly, this disclosure provides, in particular, articles containing adhesive compositions exhibiting on-demand peel behavior. Various features and advantages of this disclosure are described in the following claims. The present invention encompasses the following embodiments. (1) A first component having a first conductive surface, 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, Articles containing, The adhesive composition bonds the first component to the second component, An article in which the effort required to separate the first component from the second component, as measured by the amount of adhesive work per unit surface area, is reduced by applying a DC potential across the adhesive composition. (2) The zwitterionic polymer is a. Anionic monomers comprising acrylic acid, methacrylic acid, their carboxylates, or mixtures of two or more thereof, in an amount of 0.2% to 16% by weight based on the total weight of the polymer (where the amount of carboxylate is based on the weight of the corresponding free acid), b. Based on the total weight of the polymer, 2% to 25% by weight of one or more cationic monomers containing alkylammonium functional groups, acrylic acid or methacrylic acid esters, c. Based on the total weight of the polymer, 50% to 95% by weight of one or more nonionic monomers, including acrylic acid or methacrylic acid esters, of alcohols having 2 to 18 carbon atoms, and d. One or more additional monomers in an amount of 0% to 40% by weight based on the total weight of the polymer, Articles as described in item 1, which are essentially derived from polymerization products of the same. (3) The article according to item 2, wherein at least one of the one or more additional monomers comprises a crosslinking agent in an amount of up to 10% by weight based on the total weight of the polymer. (4) The article according to item 2 or 3, wherein the acrylic acid or methacrylic acid ester of the alcohol having 2 to 18 carbon atoms is isooctyl acrylate. (5) The article according to any one of items 2 to 4, wherein the acrylic acid or methacrylic acid ester containing the alkylammonium functional group is a reaction product of 2-(dimethylamino)ethyl acrylate or 2-(dimethylamino)ethyl methacrylate with an alkyl bromide or alkyl chloride having 1 to 24 carbon atoms. (6) The article according to any one of items 1 to 5, wherein the first component comprises a first nonconductive material and a first conductive coating for providing the first conductive surface. (7) The article according to any one of items 1 to 6, wherein the second surface of the second component is a second conductive surface. (8) The article according to item 7, wherein the second component comprises a second nonconductive material and a second conductive coating for providing the second conductive surface. (9) The article according to item 7 or 8, wherein the first conductive surface and the second conductive surface are each selected from the group consisting of metals, mixed metals, alloys, metal oxides, composite metals, conductive plastics, conductive polymers, or combinations thereof. (10) An article according to any one of items 7 to 9, wherein the composition of the first conductive surface is different from the composition of the second conductive surface. (11) An article according to any one of items 7 to 9, wherein the composition of the first conductive surface is the same as the composition of the second conductive surface. (12) The adhesive composition A carrier having a first main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The article according to any one of items 7 to 11, wherein the surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component. (13) The article described in item 12, wherein the carrier is made of a porous material. (14) The article described in item 13, wherein the carrier is selected from the group consisting of paper, woven or nonwoven fabric, porous film, metal mesh, metal grid, or a combination thereof. (15) The article described in item 12, wherein the carrier is made of a conductive material. (16) The article according to item 15, wherein the carrier is selected from the group consisting of a metal mesh, a metal grid, a metal foil, a metal plate, a conductive polymer, a conductive foam, a conductive tissue, or a combination thereof. (17) An article according to any one of items 12 to 16, wherein the composition of the first zwitterionic polymer is the same as the composition of the second zwitterionic polymer. (18) The article according to any one of items 12 to 16, wherein the composition of the first zwitterionic polymer is different from the composition of the second zwitterionic polymer. (19) The second surface of the second component is a non-conductive surface, and the adhesive composition is A carrier having a first main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component. The article described in item 1, wherein the carrier is conductive. (20) The article described in item 19, wherein the carrier is made of a porous material. (21) The article according to item 19, wherein the carrier is selected from the group consisting of a metal mesh, a metal grid, a metal foil, a metal plate, a conductive polymer, a conductive foam, a conductive tissue, or a combination thereof. (22) The article according to any one of items 19 to 21, wherein the composition of the first zwitterionic polymer is the same as the composition of the second zwitterionic polymer. (23) The article according to any one of items 19 to 21, wherein the composition of the first zwitterionic polymer is different from the composition of the second zwitterionic polymer. (24) An article according to any one of items 1 to 23, further comprising a first outer adhesive on the first component opposite to the adhesive composition, a second outer adhesive on the second component opposite to the adhesive composition, or a combination thereof. (25) The article according to item 24, wherein at least one of the first outer adhesive and the second outer adhesive comprises a pressure-sensitive adhesive. (26) The article according to item 25, further comprising a release liner on the first outer adhesive opposite to the first component, on the second outer adhesive opposite to the second component, or a combination thereof. (27) An article according to any one of items 1 to 26, wherein at least one of the first and second components is a three-dimensional body. (28) An article according to any one of items 1 to 27, wherein at least one of the first and second components is a two-dimensional body. (29) An article according to any one of items 1 to 28, wherein at least one of the first component and the second component is a recyclable component. (30) The article according to any one of items 1 to 29, wherein the effort required to separate the first component from the second component is at least 15%, when measured by the percentage change in the amount of adhesive work per unit surface area over 100 seconds at 0V and 50V. (31) A method for separating components in a composite product as described in item 1, wherein the method includes applying a DC potential across the adhesive composition to separate the first component from the second component. (32) The method according to item 31, 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, and the method further comprises applying a DC potential to detach the adhesive composition from the negative electrode, thereby causing the first component to separate from the second component. (33) The adhesive composition A carrier having a first main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component. The carrier is conductive, The first conductive surface or carrier functions as a negative electrode, and the other of the first conductive surface or carrier functions as a positive electrode. The method according to item 31, further comprising applying a DC potential to detach the adhesive composition from the negative electrode and causing the first component to separate from the second component. (34) The method according to any one of items 31 to 33, wherein the thickness of the adhesive composition is in the range of 10 μm to 2 mm. (35) The method according to any one of items 31 to 34, wherein the applied potential is a maximum of 800 V / mm.

Claims

1. A first component having a first conductive surface, 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, Articles containing, The aforementioned zwitterionic polymer, a. Anionic monomers comprising acrylic acid, methacrylic acid, their carboxylate salts, or mixtures thereof, b. Cationic monomers having alkylammonium functional groups, containing acrylic acid or methacrylic acid esters, c. Nonionic monomers containing acrylic acid or methacrylic acid esters of alcohols having 2 to 18 carbon atoms, and d. Optional components include one or more additional monomers, It contains polymerization products of The adhesive composition bonds the first component to the second component. An article in which the effort required to separate the first component from the second component, as measured by the adhesive work per unit surface area, is at least 15% when a DC potential is applied across the adhesive composition and measured by the percentage change in adhesive work per unit surface area over 100 seconds at 0V and 50V.

2. The aforementioned zwitterionic polymer, a. Anionic monomers comprising 0.2% to 16% by weight of acrylic acid, methacrylic acid, their carboxylates, or mixtures of two or more thereof, based on the total weight of the polymer (where the amount of carboxylate is based on the weight of the corresponding free acid), b. One or more cationic monomers containing acrylic acid or methacrylic acid ester having alkylammonium functional groups, in an amount of 2% to 25% by weight based on the total weight of the polymer. c. Based on the total weight of the polymer, 50% to 95% by weight of one or more nonionic monomers containing acrylic acid or methacrylic acid esters of alcohols having 2 to 18 carbon atoms, and d. One or more additional monomers in an amount of 0% to 40% by weight based on the total weight of the polymer, The article according to claim 1, which is essentially composed of polymerization products of the

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

4. The article according to claim 1, wherein the first component comprises a first nonconductive material and a first conductive coating for providing the first conductive surface.

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

6. The adhesive composition A carrier having a first main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The article according to claim 5, wherein the surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component.

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

8. The article according to 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 main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component. The article according to claim 1, wherein the carrier is conductive.

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

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

12. A method for separating components in a composite product according to claim 1, the method comprising applying a DC potential across the adhesive composition to separate the first component from the second component.

13. The method according to claim 12, 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, and the method further comprises applying a DC potential to detach the adhesive composition from the negative electrode, thereby causing the first component to separate from the second component.

14. The adhesive composition A carrier having a first main surface and a second main surface opposite to the first main surface, A first adhesive composition comprising a first zwitterionic polymer is located on the first main surface of the carrier, A second adhesive composition comprising a second zwitterionic polymer is located on the second main surface of the carrier, It is a double-sided adhesive that includes The surface of the first adhesive composition opposite to the carrier is in contact with the first conductive surface of the first component. The surface of the second adhesive composition opposite to the carrier is in contact with the second surface of the second component. The carrier is conductive, The first conductive surface or carrier functions as a negative electrode, and the other of the first conductive surface or carrier functions as a positive electrode. The method according to claim 12, further comprising applying a DC potential to detach the adhesive composition from the negative electrode and causing the first component to separate from the second component.

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