Adhesive systems including curable adhesive films and solid activator compositions, and related kits and methods

Abstract

An adhesive system includes a tape and a solid activator composition. The tape comprises a curable adhesive film, the curable adhesive film comprising: a film of a polymer; an unsaturated free radical polymerizable group, the unsaturated free radical polymerizable group being capable of bonding to the polymer, or in a substance different from the polymer; and a transition metal cation. The solid activator composition comprises an oxidizing agent and is not a self-supporting membrane. Also described is a kit comprising a tape and a solid activator composition in the form of a crayon or paste. A method of bonding a first substrate includes rubbing a solid activator composition on the first substrate or spreading the solid activator composition onto the first substrate, and then applying a tape. Also described is a crayon comprising an oxidizing agent and an acrylic polymer comprising crystalline monomer units having from 16 to 50 carbon atoms and at least one other monomer unit.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the benefit of U.S. Patent Application No. 63 / 522,680, filed June 22, 2023, the entire disclosure of which is incorporated herein by reference. Background Technology

[0003] U.S. Patent Applications No. 2020 / 0362204, No. 2021 / 0102095, and No. 2021 / 0102097, respectively, granted to Ranade et al., each describe an adhesive system comprising a curable adhesive self-supporting film, the curable adhesive self-supporting film comprising a blend of: a) a first film-forming polymer or oligomer; b) a first substance comprising a first unsaturated free radical polymerizable group, the first substance being a) or a substance different from a); and c) a first transition metal cation. The curable adhesive self-supporting film may be a pressure-sensitive adhesive. The curable adhesive self-supporting film may be used with a primer that is liquid at room temperature and pressure and contains an oxidant. The curable adhesive self-supporting film may further include d) a reducing agent without an oxidizing agent, and may be used in combination with a second curable adhesive self-supporting film comprising a blend of: e) a second film-forming polymer or oligomer; f) a second substance containing a second unsaturated free radical polymerizable group, which may be e) or may be a substance different from e); and g) an oxidizing agent. A method of bonding using such a curable adhesive self-supporting film is also described.

[0004] In unrelated art, U.S. Patent Nos. 5,604,268 (Randen et al.) and 11,267,997 (June et al.) disclose adhesive crayons and friction-activated adhesive formulations, as well as application devices. U.S. Patent No. 6,852,193 (Kneafsey et al.) discloses a composition in rod form comprising an anaerobic polymerizable compound. Summary of the Invention

[0005] In one aspect, this disclosure provides an adhesive system comprising a tape and a solid activator composition. The tape comprises a curable adhesive film comprising: a polymer film; unsaturated free radical polymerizable groups capable of bonding to the polymer, or in a substance different from the polymer; and transition metal cations. The solid activator composition contains an oxidant and is not a self-supporting film.

[0006] In another aspect, the present disclosure provides a kit comprising a tape and a solid activator composition. The tape comprises a curable adhesive film comprising: a film of a polymer; unsaturated free-radically polymerizable groups that are capable of bonding to the polymer or in a species different from the polymer; and a transition metal cation. The solid activator composition is in the form of a crayon or a paste and comprises an oxidizing agent.

[0007] In another aspect, the present disclosure provides a method of bonding a first substrate. The method comprises applying a solid activator composition to a surface of the first substrate and contacting the solid activator composition with a first surface of a tape. The solid activator composition comprises an oxidizing agent and is applied by at least one of rubbing or spreading. The tape comprises a curable adhesive film comprising: a film of a polymer; unsaturated free-radically polymerizable groups that are capable of bonding to the polymer or in a species different from the polymer; and a transition metal cation.

[0008] In another aspect, the present disclosure provides a crayon comprising an acrylic polymer and an oxidizing agent. The acrylic polymer comprises crystalline monomeric units having 16 to 50 carbon atoms and at least one other monomeric unit.

[0009] The term “polymer” refers to a molecule having a structure comprising a plurality of repeating units that are actually or conceptually derived from one or more monomers. The term “monomer” refers to a low relative molecular mass molecule that can combine with other molecules to form a polymer. The term “polymer” includes homopolymers and copolymers and homopolymers or copolymers that can be formed in miscible blends, for example, by co-extrusion or by reaction. The term “polymer” includes random polymers, block polymers, graft polymers, and star polymers. The term “polymer” includes oligomers.

[0010] A “monomeric unit” of a polymer or oligomer is a segment of the polymer or oligomer that is derived from a single monomer.

[0011] The terms “cured” and “curable” refer to the joining together of polymer chains by covalent chemical bonds, typically through crosslinking molecules or groups. Thus, in the present disclosure, the terms “cured” and “crosslinked” are used interchangeably. Cured or crosslinked polymers are typically characterized by insolubility, but can be swellable in the presence of an appropriate solvent. The term “crosslinking” includes partial crosslinking.

[0012] Oxygen permeable means having at least 4000 cubic centimeters (cm3) of oxygen per square meter per 24 hours at 23°C to 25°C without specifying the percentage of relative humidity. 3 ​micrometers (μm) / square meters (m²) 2 ) sky Atmospheric pressure (atm) (4000cm) 3 μm / m 2 sky Oxygen permeability (atm).

[0013] As used throughout this specification, the term "adjacent" refers to two stacked layers within a strip or a construction comprising a strip, an activator, and one or more substrates, arranged directly adjacent to each other, i.e., they are adjacent to each other and generally in direct contact with each other.

[0014] The term "film formation" refers to the ability to form a continuous and coherent film, which in some embodiments may be produced by one or more operations of solidification, curing, drying or solvent removal of a melt, solution or suspension.

[0015] The term "solid" refers to a material that is essentially self-supporting at room temperature (i.e., 20°C to 25°C), such that if left to stand, it will retain its shape without deforming or flowing.

[0016] The term "self-supporting membrane" refers to a membrane that is solid at room temperature and pressure and has mechanical integrity independent of contact with any supporting material (especially excluding liquid, dry or in-situ cured surface coatings such as paint or primer, and surface coatings that do not have independent mechanical integrity).

[0017] In the context of one of the polymer-containing layers or films described herein, the term "thermally meltable" means that the polymer-containing composition includes little or no conventional solvent (in various embodiments, this may be less than 5% by weight, less than 3% by weight, less than 1% by weight, less than 0.5% by weight, less than 0.1% by weight, or less than 0.01% by weight) that can be thermally meltable under conventional conditions, wherein the thermal melt process includes thermal melt blending and extrusion.

[0018] The term "(meth)acrylate" includes, individually and collectively, methacrylates and acrylates.

[0019] The terms “normal temperature and pressure” or “NTP” refer to a temperature of 20°C (293.15K, 68℉) and an absolute pressure of 1 atm (14.696psi, 101.325kPa).

[0020] In the context of functional groups in polymers or oligomers, the term "side chain" refers to a functional group that does not form part of the main chain of the polymer or oligomer and is not a terminal group of the polymer.

[0021] The term "structural adhesive" means an adhesive that bonds through irreversible curing.

[0022] "pressure sensitive adhesive" (PSA) is well known to those of ordinary skill in the art to possess properties including: (1) forceful and permanent tack, (2) adhesion with no more than finger pressure, (3) sufficient internal cohesion to hold the adherends fast, and usually (4) sufficient cohesive strength to be removed cleanly from the adherend. A PSA is tacky and has the ability to adhere without activation by any energy source such as light, heat, or chemical reaction. Materials that have been found to work well as PSAs are polymers designed and formulated to exhibit the desired balance of viscoelastic properties to achieve tack, peel adhesion, and shear holding power. One method that can be used to identify a pressure sensitive adhesive is the Dahlquist criterion. As described in "Handbook of Pressure Sensitive Adhesive Technology", edited by Donatas Satas, 2ndEdition, page 172, Van Nostrand Reinhold, New York (NY), 1989, the criterion defines a pressure sensitive adhesive as one having a creep compliance greater than 3 x 10 -6 cm 2 Alternatively, since the modulus is roughly the inverse of the creep compliance, a pressure sensitive adhesive can be defined as one having a storage modulus less than about 3 x 10 5 N / m 2 .

[0023] The term "glass transition temperature" or "Tg" refers to the temperature at which a material transitions from a glassy state to a rubbery state. In this context, the term "glassy" means that the material is hard and brittle (and thus relatively easy to break), while the term "rubbery" means that the material is elastic and flexible. For a polymeric material, the Tg is the critical temperature that separates its glassy state from its rubbery state. If a polymeric material is at a temperature below its Tg, then large-scale molecular motion is severely restricted because the material is essentially frozen. On the other hand, if a polymeric material is at a temperature above its Tg, then molecular motion occurs on the scale of its repeat units, allowing the material to be soft or rubbery. Any reference herein to the Tg of a monomer means the Tg of a homopolymer formed from the monomer. The glass transition temperature of a polymeric material is typically determined using methods such as dynamic mechanical analysis ("DMA") or differential scanning calorimetry (e.g., modulated differential scanning calorimetry). Alternatively, if the amount and Tg of each monomer used to form a polymeric material are known, then the glass transition of the polymeric material can be calculated using the Fox equation.

[0024] The term "alkyl" refers to a monovalent radical of a saturated hydrocarbon. Alkyl groups can be straight-chain, branched, cyclic, or a combination thereof, and typically have from 1 to 32 carbon atoms. Unless otherwise indicated, alkyl groups contain from 1 to 25, 1 to 20, 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, 2-ethylhexyl, 2-octyl, and 2-propylheptyl.

[0025] The term "aryl" refers to a monovalent radical that is aromatic and optionally carbocyclic. Aryl groups have at least one aromatic ring. Any additional rings can be unsaturated, partially saturated, saturated, or aromatic. Optionally, the aromatic ring(s) can have one or more additional carbocyclic rings fused to the aromatic ring(s). Unless otherwise indicated, aryl groups typically contain from 6 to 30 carbon atoms. In some embodiments, aryl groups contain from 6 to 20, 6 to 18, 6 to 16, 6 to 12, or 6 to 10 carbon atoms. Examples of aryl groups include phenyl, naphthyl, biphenyl, phenanthryl, and anthryl.

[0026] The term "aralkyl" refers to a monovalent radical that is an alkyl group substituted with an aryl group (e.g., as in a benzyl group). The term "alkaryl" refers to a monovalent radical that is an aryl group substituted with an alkyl group (e.g., as in a tolyl group). In some embodiments, for both groups, the alkyl portion has from 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms, and the aryl portion has from 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms.

[0027] The term "alkylene" refers to a divalent radical of an alkane and includes straight-chain groups, branched groups, cyclic groups, bicyclic groups, or a combination thereof. Unless otherwise indicated, alkylene groups typically have from 1 to 30 carbon atoms. In some embodiments, alkylene groups have from 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Examples of "alkylene" groups include methylene, ethylene, propylene, 1,4-butylene, 1,4-cyclohexylene, and 1,4-cyclohexyldimethylene.

[0028] The term "arylene" refers to a divalent group that is aromatic and optionally carbocyclic. Arylene groups have at least one aromatic ring. Optionally, the aromatic ring can have one or more additional carbocyclic rings fused to the aromatic ring. Any additional rings can be unsaturated, partially saturated, or saturated. In some embodiments, arylene groups have up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromatic ring. For example, an arylene group can be phenylene. Unless otherwise indicated, arylene groups have 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms.

[0029] The term "aralkylene" refers to a divalent group that is an alkylene group substituted with an aryl group or an alkylene group attached to an arylene group. The term "alkarylene" refers to a divalent group that is an arylene group substituted with an alkyl group or an arylene group attached to an alkylene group. In some embodiments, both groups have 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms in the alkyl or alkylene portion. In some embodiments, both groups have 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms in the aryl or arylene portion.

[0030] As used herein, the term "or" is generally used in its usual sense, to mean "and / or", unless the context clearly indicates otherwise. As used herein, the term "and / or" is used to indicate one or both of the described conditions can occur, for example A and / or B includes (A and B) and (A or B).

[0031] As used herein, the term "room temperature" refers to a temperature in the range of 20 °C to 25 °C.

[0032] In this document, the terms "comprise" and variations thereof, when used in the specification and in claims, do not have a limiting meaning. Such terms will be understood to imply the inclusion of literal and / or equivalent factual sentries for the recited step or element, but not to the exclusion of any other step or element. By "consisting of is meant inclusion of the recited item or group of items and nothing more. Thus, the phrase "consisting of indicates that the listed elements are required or mandatory, and that no other elements can be present. By "consisting essentially of is meant inclusion of the recited item or group of items and any other item or group of items that does not materially affect the activity or action specified in the disclosure for the listed item or group of items. Thus, the phrase "consisting essentially of indicates that the listed elements are required or mandatory, but that other elements are optional and can or can not be present depending upon whether or not they materially affect the activity or action specified in the disclosure for the listed item or group of items. Any element or combination of elements that is recited in open-ended language (e.g., comprising, comprising at least, comprising at least one of, comprising one of, and the like), is considered to be additionally disclosed in closed- ended language (e.g., consisting of, consisting essentially of, and the like) and in partial closed-ended language (e.g., the more restrictive "consisting essentially of).

[0033] In this application, terms such as "one," "a," and "the" are not intended to refer to single

[0034] Also herein, all numerical values are assumed to be modified by the term "about" and in certain embodiments by the term "exactly." As used herein, the term "about" with reference to a measured quantity, means a deviation of plus or minus ten percent (10%) of the measured quantity, or a deviation of plus or minus the exact amount that would be expected by a person of ordinary skill in the art acting with reasonable care to measure the quantity. Herein, "up to" a number (e.g., up to 50) includes the number (e.g., 50).

[0035] Also herein, numerical ranges are expressed in terms of "between," "up to," and "from... to..." and include the numbers that fall within the range, including the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.) and any sub-ranges (e.g., 1 to 5 includes 1 to 4, 1 to 3, 2 to 4, etc.).

[0036] The terms "in a range" or "within a range" (and like expressions) include the endpoints of the range.

[0037] Throughout this specification, the reference to "some embodiments" means that a specific feature, configuration, composition, or characteristic described in connection with an embodiment is included in at least one embodiment of this disclosure. Therefore, such phrases appearing throughout this specification do not necessarily refer to the same embodiment as in this disclosure. Furthermore, specific features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0038] The foregoing overview of this disclosure is not intended to describe every disclosed embodiment or every implementation of this disclosure. The following description illustrates exemplary embodiments in more specific terms. Guidance is provided at several points throughout this application by a list of examples, which can be used in various combinations. In each case, the cited list is used only as a representative group and should not be construed as an exclusive list. Therefore, the scope of this disclosure should not be limited to the specific exemplary structures described herein, but should extend at least to the structures described by the language of the claims and their equivalents. Any element positively referenced as an alternative in this specification may be expressly included in or excluded from the claims in any combination as desired. While various theories and possible mechanisms may have been discussed herein, such discussion should in no way be used to limit the subject matter protected by the claims. The drawings are not to scale. Attached Figure Description

[0039] Figure 1 It is a cross-section of one embodiment of the tape that can be used in the adhesive system disclosed herein.

[0040] Figure 2 This is a cross-section of another embodiment of the tape that can be used in the adhesive system disclosed herein.

[0041] Figure 3 Is using Figure 2 A cross-section of one embodiment of the construction of the type of strip, solid activator composition, and first and second substrates shown.

[0042] Figure 4 It is a cross-section of one embodiment of a double-sided tape having only one curable adhesive film layer, which can be used in the adhesive system disclosed herein.

[0043] Figure 5 It is a cross-section of one embodiment of a double-sided multilayer tape with a barrier membrane support layer, which can be used in the adhesive system disclosed herein.

[0044] Figure 6 Is using Figure 2 A cross-section of another embodiment of the construction of the type of strip, solid activator composition, and first and second substrates shown.

[0045] Figure 7 is a cross-section of an embodiment of the adhesive system of the present disclosure covered with an oxygen permeable liner.

[0046] Figure 8 is a cross-section of another embodiment of the adhesive system of the present disclosure covered with an oxygen permeable liner.

[0047] Figure 9 depicts an embodiment of a method for bonding two substrates using an embodiment of the adhesive system of the present disclosure.

[0048] Figure 10 depicts another embodiment of a method for bonding two substrates using an embodiment of the adhesive system of the present disclosure.

[0049] Figure 11 depicts yet another embodiment of a method for bonding two substrates using another embodiment of the adhesive system of the present disclosure.

[0050] Figure 12 is a side (partially cross-sectional) elevation view of a container for containing a solid activator composition.

[0051] Figure 13 is a top view of a carrier forming Figure 12 a portion of the container. DETAILED DESCRIPTION

[0052] The adhesive system of the present disclosure includes a tape. The tape includes a curable adhesive film comprising a film of a polymer, unsaturated free-radically polymerizable groups, and transition metal cations. The unsaturated free-radically polymerizable groups are capable of bonding to the polymer (i.e., the component of the polymer) or can be in a substance different from the polymer. In some embodiments, the curable adhesive film further comprises a redox promoter. The unsaturated free-radically polymerizable groups serve to crosslink the curable adhesive film.

[0053] In some embodiments, the curable adhesive film is a first layer of a multilayer curable adhesive film, wherein the multilayer curable adhesive film further comprises a support layer. In some embodiments, the support layer is a foam support layer, in some embodiments, the support layer is a curable foam support layer. In some embodiments, the multilayer curable adhesive film is a double-sided tape, wherein one curable adhesive film is adjacent to each major surface of the curable foam support layer (i.e., a second curable adhesive film is adjacent to the surface opposite the first curable adhesive film). Thus, in this embodiment, the first curable adhesive film is adjacent to a first major surface of the curable foam support layer and the second curable adhesive film is adjacent to a second major surface of the curable foam support layer.

[0054] As Figure 1 An embodiment of tape 110 includes a curable adhesive film 140 (having two major surfaces 142 and 144) adjacent to a support layer 150 (having two major surfaces 152 and 154), as shown in FIG. 1. In some embodiments, support layer 150 is a foam. In some embodiments, support layer 150 is curable.

[0055] An embodiment of multilayer curable adhesive film 210 includes a first curable adhesive film 240 (having two major surfaces 242 and 244) and a second curable adhesive film 260 (having two major surfaces 262 and 264), each of which is adjacent to opposite surfaces of a support layer 250 (having two major surfaces 252 and 254), as shown in FIG. 2. More specifically, first major surfaces 242 and 262 form the outer adhesive surfaces of multilayer curable adhesive film 210; second major surface 244 of first adhesive film 240 is adjacent to first major surface 252 of support layer 250; and second major surface 264 of second adhesive film 260 is adjacent to second major surface 254 of support layer 250. In some embodiments, support layer 250 is a foam. In some embodiments, support layer 250 is curable. Figure 2

[0056] The second layer is a second curable adhesive film comprising: a second film of a second polymer; a second unsaturated free-radically polymerizable group, the unsaturated free-radically polymerizable group being bondable to the second polymer or in a second substance different from the second polymer; and a second transition metal cation. The components of the first curable adhesive film and the second curable adhesive film can be the same or different. In some embodiments, the second unsaturated free-radically polymerizable group is bonded to the second polymer. In some embodiments, the second unsaturated free-radically polymerizable group is in a second substance different from the second polymer, and the second polymer does not comprise an unsaturated free-radically polymerizable group.

[0057] In some embodiments of FIG. 1, first curable adhesive film 140 is carried on first major surface 152 of support layer 150, and second curable adhesive film 140 is carried on second major surface 154 of support layer 150. That is, the layers are typically fabricated in one step, such as in a coating or co-extrusion process. Figure 2 Figure 2 ​​In some embodiments of the present disclosure, the first curable adhesive film 240 is directly bonded to the first major surface 252 of the support layer 250, and the second curable adhesive film 260 is directly bonded to the second major surface 254 of the support layer 250. That is, the layers are typically fabricated in two or more steps, such as in a lamination process. Such procedures are well known in the tape preparation art. Regardless of how the multi-layer curable adhesive film is fabricated, the major surface 244 of the curable adhesive film 240 is adjacent to the major surface 252 of the curable foam support layer 250.

[0058] Examples of suitable film-forming polymers for the polymeric film that can be used in the curable adhesive film include (meth)acrylate polymers; aromatic or aliphatic polyurethanes (e.g., including those polyurethanes made from aliphatic or aromatic diols, polyamides, saturated and unsaturated polyesters, such as polybutylene terephthalate, polyethylene terephthalate, polyglycolic acid, polylactic acid, poly-2-hydroxybutyrate, polycaprolactone, and combinations containing maleic acid repeat units); polyethers (e.g., such as polyacetals and copolymers thereof, polyphenylene ethers, polyether ketones, polyether ether ketones); natural and synthetic rubbers (e.g., polyisoprene, polychloroprene, nitrile rubber, butadiene-based rubbers); alkyd resins; phenolic resins (e.g., novolac resins and resole resins); amino resins (e.g., urea-formaldehyde resins, melamine-formaldehyde resins, and melamine-urea copolymer resins); and epoxides (e.g., those made from bisphenol A or adducts using telechelic amino resins capped with oxirane functionality). In some embodiments, the film-forming polymer or oligomer is a (meth)acrylate functional polymer, such as those made by adding (meth)acrylate end groups to a polyester, polyurethane, polybutadiene, or polyether polymer. Various combinations of any of these film-forming polymers can be used in the curable adhesive film in the articles of the present disclosure.

[0059] In some embodiments, the film-forming polymer of the curable adhesive film is a (meth)acrylate polymer. In some embodiments, the curable adhesive film is a pressure sensitive adhesive prior to curing in contact with the solid activator described herein. Thus, prior to curing, they are also capable of holding substrates in place without clamps and other supports, for example, under shop or factory conditions. In some embodiments where the curable adhesive film is a (meth)acrylate polymer and / or a pressure sensitive adhesive, the (meth)acrylate polymer comprises linear or branched alkyl (meth)acrylate monomer units selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, 2-propylheptyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, nonyl (meth)acrylate, isophoryl (meth)acrylate, and any combination or mixture thereof. In some embodiments, the (meth)acrylate polymer includes monomer units of at least one of 2-methylbutyl acrylate, isooctyl acrylate, lauryl acrylate, 4-methyl-2-pentyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate, or isononyl acrylate.

[0060] Suitable monomer units also include mixtures of at least two or at least three structural isomers of a secondary alkyl (meth)acrylate of Formula I: where R 1 and R 2 each independently is a C1 to C 30 saturated linear alkyl group; the sum of the number of carbons in R 1 and R 2 is 7 to 31; and R 3 is H or CH3. In some embodiments, R 1 and R 2The sum of the number of carbons in the alkyl group and the number of carbons in the alkyl group of the (meth)acrylate monomer unit can be 7 to 27, 7 to 25, 7 to 21, 7 to 17, 7 to 11, 7, 11 to 27, 11 to 25, 11 to 21, 11 to 17, or 11. Methods for making and using such monomers and monomer mixtures are described in U.S. Patent No. 9,102,774 (Clapper et al.).

[0061] In some embodiments, the (meth)acrylic alkyl ester monomer units can be copolymerized with one or more monoethylenically unsaturated monomers having polar groups, such as acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, N-substituted acrylamides (e.g., N,N-dimethyl acrylamide), acrylonitrile, methacrylonitrile, hydroxyalkyl acrylate, cyanoethyl acrylate, N-vinyl pyrrolidone, N-vinyl caprolactam, and maleic anhydride. In some embodiments, these polar copolymerizable monomers are used in an amount of less than 20 wt% and / or at least 6 wt%, at least 8 wt%, or at least 10 wt%, based on the total weight of monomer units. In some embodiments, the (meth)acrylate polymer comprises at least 6 wt% of acrylic acid, at least 8 wt%, or at least 10 wt%, each based on the total weight of monomers in the (meth)acrylate polymer. In some embodiments, the (meth)acrylate polymer comprises 0.1 wt% to 12 wt% of (meth)acrylic monomer units, based on the weight of the (meth)acrylate polymer. The (meth)acrylate polymer can also include small amounts of other useful copolymerizable monoethylenically unsaturated monomers, such as alkyl vinyl ethers, vinylidene chloride, styrene, and vinyl toluene.

[0062] In some embodiments, the (meth)acrylic alkyl ester monomer units can be copolymerized with a crosslinking agent, such as 1,6-hexanediol diacrylate, or with a photoactive triazine crosslinking agent, such as taught in U.S. Patent No. 4,330,590 (Vesle) and U.S. Patent No. 4,329,384 (Vesley et al.). The film-forming polymer can also be crosslinked with a heat-activatable crosslinking agent, such as a C 1-4 lower alkoxylated aminoformaldehyde condensates, such as hexamethoxymethyl melamine or tetramethoxymethyl urea or tetrabutoxymethyl urea. Crosslinking of the film-forming polymer can also be achieved by irradiating the composition with electron beam (or "e-beam") radiation, gamma radiation, or X-ray radiation. This crosslinking occurs during the preparation of the polymer film, prior to the reaction of the unsaturated free-radically polymerizable groups in the curable adhesive film.

[0063] In some embodiments, the (meth)acrylate polymer has a Tg of no greater than 0 °C. In some embodiments, the (meth)acrylate polymer has a Tg of -70 °C to 0 °C, -70 °C to -10 °C, -60 °C to -10 °C, -60 °C to -20 °C, -60 °C to -30 °C, -55 °C to -35 °C, or -50 °C to -40 °C.

[0064] In some embodiments, the curable adhesive film is a pressure sensitive adhesive comprising a first (meth)acrylate copolymer comprising 0.1 to 12 weight percent of (meth)acrylic monomer units, based on the weight of the first (meth)acrylate copolymer; and a second (meth)acrylate copolymer comprising 15 to 40 weight percent of (meth)acrylic monomer units, based on the weight of the second (meth)acrylate copolymer. The first (meth)acrylate copolymer and / or the second (meth)acrylate copolymer can comprise any of those described above as the primary monomer units. In some embodiments, the first (meth)acrylate copolymer and / or the second (meth)acrylate copolymer comprises linear or branched (meth)acrylic alkyl ester monomer units selected from the group consisting of 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, isooctyl (meth)acrylate, and any combination or mixture thereof as the primary monomer units. In some embodiments, the first (meth)acrylate copolymer has a Tg of no greater than 0°C and the second (meth)acrylate copolymer has a Tg of greater than 0°C. In some embodiments, the second (meth)acrylate copolymer has a Tg of no greater than 100°C, no greater than 80°C, no greater than 60°C, no greater than 50°C, no greater than 45°C, or even no greater than 40°C. In some embodiments, the first (meth)acrylate copolymer has a Tg of -70°C to 0°C, -70°C to -10°C, -60°C to -10°C, -60°C to -20°C, -60°C to -30°C, -55°C to -35°C, or -50°C to -40°C. In some embodiments, the second (meth)acrylate copolymer has a Tg of 2°C to 100°C, 2°C to 80°C, 2°C to 60°C, 2°C to 50°C, 2°C to 45°C, 5°C to 45°C, 5°C to 40°C, 5°C to 35°C, or 10°C to 30°C. In some embodiments, the curable adhesive film comprises 65 to 99 weight percent, 70 to 95 weight percent, 75 to 95 weight percent, 75 to 90 weight percent, or 75 to 85 weight percent of the first (meth)acrylate copolymer, and wherein the weight percent is based on the total weight of the curable adhesive film composition. In some embodiments, the curable adhesive film in the articles of the present disclosure comprises 1 to 35 weight percent, 1 to 30 weight percent, 2 to 25 weight percent, 3 to 25 weight percent, 3 to 20 weight percent, 4 to 20 weight percent, or even 4 to 15 weight percent of the second (meth)acrylate copolymer, and wherein the weight percent is based on the total weight of the curable adhesive film composition.In some embodiments, these pressure sensitive adhesive compositions are described in U.S. Patent Application Publication No. 2021 / 0102099 (Unverhau et al.).

[0065] The polymer in the polymer film can be prepared by any suitable polymerization method. Suitable polymerization methods include, but are not limited to, photopolymerization, thermal polymerization, or ionizing radiation polymerization. These methods can be carried out in solution, emulsion, or bulk without solvent. Bulk polymerization methods are described in U.S. Patent No. 5,804,610 (Hamer et al.). Optionally, the photopolymerizable monomers can be partially polymerized to a viscosity of 1000 cps to 40,000 cps to facilitate coating. Alternatively, partial polymerization can be achieved by heating. If desired, the viscosity can also be adjusted by mixing the monomers with a thixotropic agent such as fumed silica.

[0066] Photopolymerization can be carried out in an inert atmosphere, such as under a nitrogen or argon blanket. Alternatively, an inert environment can be achieved by temporarily covering the photopolymerizable coating with a plastic film that is transparent to ultraviolet radiation and irradiating the coating through the film. If the polymerizable coating is not covered during photopolymerization, the permissible oxygen content of the inert atmosphere can be increased by mixing an oxidizable tin compound into the photopolymerizable composition, such as disclosed in U.S. Patent No. 4,303,485 (Levens), which can enable relatively thick coatings to be polymerized in air.

[0067] Curable adhesive films that can be used in the articles of the present disclosure include unsaturated free-radically polymerizable groups that are capable of bonding to a polymer (i.e., a reactive polymer that includes unsaturated free-radically polymerizable groups) or in a substance that is different from the polymer. Unsaturated free-radically polymerizable groups include ethylenically unsaturated groups (e.g., vinyl-containing groups such as (meth)acrylate groups). In some embodiments, the unsaturated free-radically polymerizable groups are part of a crosslinking agent (i.e., a crosslinkable substance) that is different from the polymer from which the polymer film is made. Such crosslinking agents include two or more unsaturated free-radically polymerizable groups or three or more unsaturated free-radically polymerizable groups. In some embodiments, the crosslinking agent is a crosslinking monomer. In some embodiments, the crosslinking agent is an oligomer.

[0068] Examples of suitable crosslinking agents include trimethylolpropane triacrylate (TMPTA), ethoxytrimethylolpropane triacrylate, propoxyglyceryl triacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, ethoxy pentaerythritol tetraacrylate, trimethylolpropane trimethacrylate, ethoxy pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, glyceryl diacrylate, glyceryl triacrylate, ethylene glycol dimethacrylate, 1,3-propanediol dimethacrylate, 1,2,4-butanetriol trimethacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, neopentyl glycol diacrylate, and combinations thereof. Other examples of crosslinking agents include other multifunctional polyol esters. For example, acrylates or methacrylates of a plurality of polyols in which at least two hydroxyl groups are esterified can be used as crosslinking agents.

[0069] The curable adhesive film that can be used in the articles of the present disclosure additionally includes a transition metal cation. Examples of suitable transition metal cations include molybdenum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, or zinc. In some embodiments, the transition metal cation is a copper cation, such as Cu(II), such as can be found in copper(II) acetate monohydrate and copper(II) naphthenate. In some embodiments, the transition metal cation is an iron cation, such as Fe(II) or Fe(III), such as can be found in Pigment Black 11 (Fe3O4or FeO . Fe2O3), Pigment Red 102 (Fe2O3), or Pigment Yellow 42 (Fe2O3·H2O).

[0070] Useful transition metal complexes are described in U.S. Patent No. 11,370,940 (Townsend et al.) and have the general formula: [ML p ] n+ A - where M represents a transition metal capable of participating in a redox cycle with an oxidizing agent and a reducing agent. Useful transition metals M can include catalytically active valence states of Cu, Fe, Ru, Cr, Mo, Pd, Ni, Pt, Mn, Rh, Re, Co, V, Au, Nb, and Ag. In some embodiments, the transition metal cation is a low valence transition metal including Cu(II), Fe(II), Ru(II), and Co(II). Other valence states of these metals can be used and can be generated in situ to an active low valence state.

[0071] In formula [ML p ] n+ A -In the complex, L represents a ligand. The ligand L can be used to solubilize the transition metal salt in a suitable solvent and to adjust the redox potential of the transition metal to achieve suitable reactivity and selectivity. The ligand can direct the transition metal complex to undergo the desired single electron transfer process rather than a two electron process, such as oxidative addition / reductive elimination. The ligand can also enhance the stability of the complex in the presence of different monomers and solvents or at different temperatures. Acidic monomers and monomers that are strongly complexing to the transition metal can still be polymerized effectively by appropriate selection of the ligand. Useful ligands include those having one or more nitrogen, oxygen, phosphorus, and / or sulfur atoms that can coordinate to the transition metal through a sigma bond; ligands containing two or more carbon atoms that can coordinate to the transition metal through a pi bond; and the like.

[0072] In some embodiments, such ligands can be monodentate or polydentate compounds containing up to about 20 carbon atoms and up to 10 heteroatoms selected from aluminum, boron, nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, antimony, and tellurium, wherein the polydentate compound can coordinate to the metal M n+ form a 4-, 5-, or 6-membered saturated or unsaturated ring. Examples of suitable monodentate ligands are carbon monoxide; alcohols such as ethanol, butanol, and phenol; pyridine, nitrosyl ion (i.e., NO + ); compounds of Group 15 elements such as ammonia, phosphine, trimethylamine, trimethylphosphine, tributylphosphine, triphenylamine, triphenylphosphine, triphenylarsine, or tributyl phosphite; nitriles such as acetonitrile or benzonitrile; isonitriles such as phenyl isonitrile or butyl isonitrile; carbene groups such as ethoxymethyl carbene or dithiomethoxycarbene; alkylidene groups such as methylene or ethylene.

[0073] Examples of suitable polydentate compounds include bipyridine, 1,2-bis(diphenyl- phosphino)ethane; 1,2-bis(diphenylarsino)ethane, bis(diphenylphosphino)methane, polyamines (e.g., ethylenediamine, propylenediamine, tetramethylethylenediamine, hexamethyltriethylenediamine, diethylenetriamine, 1,3-diisocyanatopropane, and hydridotripyrazolylborate), hydroxycarboxylic acids (e.g., glycolic acid, lactic acid, and salicylic acid), polyphenols such as catechol and 2,2'-dihydroxybiphenyl, hydroxyamines (e.g., ethanolamine, propanolamine, and 2-aminophenol); dithiocarbamates such as diethyldithiocarbamate and dibenzyl dithiocarbamate, xanthates such as ethyl xanthate and phenyl xanthate, dithiolenes such as bis(perfluoromethyl)-1,2-dithiolene, aminocarboxylic acids (e.g., alanine, glycine, and anthranilic acid); dialkyldiamines such as oxamide and biuret, diketones such as 2,4-pentanedione, hydroxyketones such as 2-hydroxyacetophenone, a-hydroxyoximes such as salicylaldoxime, ketoximes such as benzoinoxime, 1,10-phenanthroline, porphyrins, cryptands, and crown ethers such as 18-crown-6 ether, and glyoxime such as dimethylglyoxime.

[0074] Other suitable ligands that can coordinate to transition metals through sigma bonds are inorganic groups (e.g., F - , OH - , Cl - , Br - , I - , and hydrides) and organic groups (e.g., CN - , SCN - , acetyloxy, formyloxy, and benzoyloxy). The ligand can also be a unit of a polymer, for example, an amino group in poly(ethyleneimine), a phosphine group in poly(4-vinylphenyldiphenylphosphine), a carboxylic acid group in poly(acrylic acid), and an isonitrile group in poly(4-vinylphenylisonitrile).

[0075] Useful ligands that can coordinate to transition metals through a pi bond containing two or more carbon atoms are provided by any monomeric or polymeric compound having an accessible unsaturated group, such as an olefinic group, an acetylenic group, or an aromatic group having accessible pi electrons, regardless of the overall molecular weight of the compound. Examples of pi-bonded ligands include straight-chain and cyclic compounds olefinic and acetylenic compounds having less than 100 carbon atoms (when monomeric), in some embodiments, less than 60 carbon atoms and zero to 10 heteroatoms selected from nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, boron, aluminum, antimony, tellurium, silicon, germanium, and tin. Specific examples of such pi-bonded ligands include ethylene, acetylene, propylene, methylacetylene, alpha-butylene, 2-butene, diacetylene, butadiene, 1,2-dimethylacetylene, cyclobutene, pentene, cyclopentene, hexene, cyclohexene, 1,3-cyclohexadiene, cyclopentadiene, 1,4-cyclohexadiene, cycloheptene, 1-octene, 4-octene, 3,4-dimethyl-3-hexene, 1-decene; η 3 -allyl, η 3 -pentenyl, norbornadiene, η 5 -cyclohexadienyl, cycloheptatriene, and cyclooctatetraene. Other suitable pi-bonded ligands include substituted and unsubstituted carbocyclic and heterocyclic aromatic ligands having up to 25 rings and up to 100 carbon atoms and up to 10 heteroatoms selected from nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, boron, aluminum, antimony, tellurium, silicon, germanium, and tin. Specific examples of such pi-bonded ligands include η 5 -cyclopentadienyl, benzene, mesitylene, toluene, xylene, tetramethylbenzene, hexamethylbenzene, fluorene, naphthalene, anthracene, pyrene, η 7 -cycloheptatrienyl, triphenylmethane, paracyclophane, 1,4-diphenylbutane, η 5 -pyrrolyl, η 5 -thiophene, η 5- Furan, pyridine, γ-methylpyridine, quinalidine, benzopyran, thiamine fluorescent, benzoxazine, indole, acridine, carbazole, triphenylene, silazine, arsenicazine, antimonyazine, 2,4,6-triphenylphosphine, η 5 -Selenophene, dibenzostannepine, η 5 - Tellurium, phenathiazine, selenanthrene, phenoxaphosphine, phenarsazine, phenatellurazine, η 5 -Methylcyclopentadienyl, η 5 -Pentamethylcyclopentadienyl and 1-phenylborane.

[0076] In some embodiments, the ligands include unsubstituted and substituted pyridines and bipyridines, tertiary amines (including polydentate amines such as N,N,N',N'-tetramethylethylenediamine and tris(N,N-dimethylamino-ethyl)amine), acetonitrile, phosphites (e.g., (CH3O)3P), 1,10-phenanthroline, porphyrin, cryptoid ligands, and crown ethers (e.g., 18-crown-6 ether). In some embodiments, the ligand is a polydentate amine, bipyridine, or a phosphite. Ligands and ligand-metal complexes that may be used in the initiator systems of this disclosure are described in Matyjaszewski and Xia, Chemical Reviews (2001), vol. 101, pp. 2921-2990.

[0077] In formula [ML] p ] n+ A - In the complex, A - This represents anion. Available anion A - Examples include halide ions (e.g., chloride, bromide, fluoride), alkoxy groups having 1 to 6 carbon atoms (i.e., C1-C6 alkoxy groups), nitrate, sulfate, phosphate, hydrogen phosphate, hexafluorophosphate, trifluoromethanesulfonate, methanesulfonate, aromatic sulfonate, cyanide, alkane carboxylate (e.g., acetate), and aromatic carboxylate (e.g., benzo[a]carboxylate). In formula [ML] p ] n+ A - In the complex, n represents the formal charge on the transition metal with an integer value of 1 to 7, or 1 to 3 in some embodiments, and p is the number of ligands on the transition metal with a value of 1 to 9, or 1 or 2 in some embodiments.

[0078] In some embodiments, the curable adhesive film additionally includes a redox promoter, such as a quaternary ammonium salt, an amine hydrochloride salt, sodium chloride, or a phosphonium salt. Suitable quaternary ammonium salts can be represented by the formula (R 7 )4N+ X- wherein each R 7 independently is an alkyl group, an aryl group, or a combination thereof, where any of these groups can be substituted or unsubstituted, and X is CI, Br, F, SbF, BF, or PF. Examples of suitable quaternary ammonium salts include dimethylbenzylamine chloride (DMBAC) and benzyltriethylammonium chloride. Suitable phosphonium salts can be represented by the formula (R 8 )4P+ X- wherein each R 8 independently is an alkyl group, an aryl group, or a combination thereof, where any of these groups can be substituted or unsubstituted, and X is CI, Br, F, SbF, BF, or PF. In some embodiments, each R 8 independently is a phenyl group or a C1-C5 alkyl group. Examples of suitable phosphonium salts include allyl triphenylphosphonium bromide (ATPB), 2- (ethoxycarbonyl)ethyl-triphenylphosphonium bromide, 1-ethoxycarbonyl ethyl triphenylphosphonium bromide, 4-ethoxycarbonyl butyl triphenylphosphonium bromide, ethoxycarbonylmethyl triphenylphosphonium bromide, and methyl triphenylphosphonium bromide. If desired, various combinations of redox promoters can be used. In some embodiments, the redox promoter is used in an amount of at least 0.25 wt%, and typically up to 4 wt%, based on the total weight of the curable adhesive film.

[0079] While the present disclosure is not bound by any theory or proposed mechanism, it is believed that the oxidizing agent in the curable adhesive film oxidizes the transition metal cation (e.g., oxidizes Cu(I) to Cu(II)) to form a free radical that initiates crosslinking (typically catalyzes crosslinking) of the crosslinkable species, thereby forming a crosslinked network. It is believed that the redox promoter, when present, acts as a reducing agent that reduces the initially provided Cu(II) cation to Cu(I).

[0080] The curable adhesive film that can be used in the articles of the present disclosure is generally a room temperature solid and is also a self-supporting film as defined herein, regardless of any support layer that can be present. The curable adhesive film can be made using conventional techniques, such as solution coating on a web. In some embodiments, including the embodiments exemplified herein, the curable adhesive film is made from a hot-melt processable adhesive film and is made in a hot-melt process. Hot-melt processing, such as hot-melt blending or hot-melt extrusion, can be achieved by any suitable method, including those disclosed in U.S. Patent Application Publication No. 2013 / 0184394 (Satrijo et al.). In some embodiments, the hot-melt processable adhesive film comprises a blend of a reactive polymer comprising unsaturated free-radically polymerizable groups, which are typically pendant groups, and a transition metal cation. In some embodiments, the hot-melt processable adhesive film comprises a blend of a film-forming polymer or oligomer, a reactive species comprising unsaturated free-radically polymerizable groups, and a transition metal cation. In some of these embodiments, the adhesive film further comprises a redox promoter (e.g., a quaternary ammonium salt). The adhesive film made by hot-melt processing can then be applied directly to a substrate or release liner adjacent to an activator to provide the adhesive system of the present disclosure.

[0081] The curable or cured adhesive film in the articles of the present disclosure can have any suitable thickness. In some embodiments, the thickness is at least 20 micrometers, at least 25 micrometers, at least 50 micrometers, at least 100 micrometers, at least 200 micrometers, at least 250 micrometers, at least 300 micrometers, or at least 350 micrometers. In some embodiments, the thickness is no more than 2000 micrometers, no more than 1000 micrometers, or no more than 500 micrometers.

[0082] The curable adhesive film can be cured when in contact with the solid activator composition disclosed herein, which comprises an oxidizing agent. Generally, the oxidizing agent of the activator migrates into the curable adhesive film, thereby initiating the cure of the curable adhesive film(s) generally in the absence of oxygen.

[0083] In some embodiments, the curable adhesive film is a first layer of a multilayer curable adhesive film, where the multilayer curable adhesive film further comprises a support layer. In some embodiments, the support layer is a foam support layer, in some embodiments, the support layer is a curable foam support layer. In some embodiments, the curable support layer comprises a base polymer. The base polymer can be the same as or different from the film-forming polymer of the polymeric film that can be used in the curable adhesive film, and can be any of those described above for the curable adhesive film. The base polymer of the curable foam support layer can be the same as the polymer in the curable adhesive film, which can or can not comprise unsaturated free-radically polymerizable groups. The base polymer can also be made and processed by any of the processes described above for the curable adhesive film.

[0084] In some embodiments, the base polymer of the support layer, which can be a foam support layer or a curable foam support layer, is a silicone polymer. Acrylate and silicone foams are useful due to their UV stability, conformability, and ability to disperse stress. Suitable silicone polymers can include MQ resins containing a resin core and non-resin polyorganosiloxane groups terminated with silicon-bonded hydroxyl groups, treated MQ resins, and polydiorganosiloxanes terminated with groups that can condense. Such compositions can be used in structural glazing applications, as described in U.S. Patent No. 8,298,367 (Beger et al.).

[0085] In some embodiments, the support layer, which in some embodiments is a foam support layer or a curable foam support layer, comprises a crosslinking agent mixed therein. If the base polymer of the curable foam support layer does not comprise unsaturated free-radically polymerizable groups, in some embodiments such groups can be provided by a different species within the curable foam support layer, or they can be provided by a species that migrates into the curable foam support layer. Examples of suitable crosslinking agents include those described above for the curable adhesive film.

[0086] Thus, in some embodiments, the curable foam support layer comprises a base polymer that is receptive to a crosslinking agent that can migrate into the curable foam support layer. In some embodiments, the crosslinking agent migrates from the curable adhesive film into the curable foam support layer. Thus, in these embodiments, the crosslinking agent of the curable foam support layer is the same as the species comprising the unsaturated free-radically polymerizable groups of the curable adhesive film. The same crosslinking agent can also be loaded into the curable adhesive film and the curable foam support layer, respectively. In other embodiments, the crosslinking agent of the curable foam support layer can be different from the species comprising the unsaturated free-radically polymerizable groups of the curable adhesive film.

[0087] When the curable adhesive film contacts the solid activator composition, typically when oxygen is excluded from the curable adhesive film or multilayer curable adhesive film to begin the redox cycle, the crosslinking agent contained within and / or migrated into the curable foam support layer and contained within the curable adhesive film is activated, initiating crosslinking. This crosslinking of the crosslinking agent results in the cure of both the curable adhesive film and the curable foam support layer. It is believed that an interpenetrating crosslinked network is formed in the bulk of the adhesive layer, where the first network is formed from the crosslinking agent and the second network is formed from the film-forming polymer. This crosslinked network forms across the boundary between the layers of the multilayer curable adhesive film, for example, across the boundary between the cured adhesive film and the cured foam support layer, evidenced by cohesive failure, for example, the foam support layer cracking open.

[0088] In some embodiments, the curable foam support layer contains transition metal cations as described for the curable adhesive film. In some embodiments, the curable foam support layer further contains a redox promoter as described for the curable adhesive film.

[0089] The foam support layer, in some embodiments, the curable foam support layer of the multilayer curable adhesive film that can be used in some embodiments of the present disclosure, can be a closed cell foam, an open cell foam, a synthetic foam, a non-synthetic foam, or a combination thereof. Such foams can be made using, for example, chemical blowing agents, physical blowing agents, and mechanical foaming processes. In some embodiments, the curable foam support layer contains a blowing agent and the same components as the curable adhesive film. In some embodiments, the blowing agent includes at least one of expandable microspheres, hollow glass bubbles, or gas (e.g., nitrogen) bubbles, the blowing agent being optionally surfactant stabilized. For example, the foam can be made from a foam formed by physical agitation and stabilized with a surfactant such as a silicone or fluorine-containing compound known to be useful in foaming organic liquids having low surface tension (e.g., those described in U.S. Patent No. 4,415,615 (Esmay et al.).

[0090] In some embodiments, the foam is a syntactic foam containing hollow microspheres (e.g., hollow ceramic (e.g., glass) microspheres). Useful hollow glass microspheres include those having a density less than 0.4 grams per milliliter (g / mL) and a diameter of 5 micrometers to 200 micrometers. The microspheres can be transparent, coated, dyed, or a combination thereof. Useful hollow glass microspheres include those available under the trade designation "3M GLASS BUBBLES K37" from 3M Co., St Paul, MN. The microspheres typically comprise 5 to 65 volume percent of the foam composition. Examples of useful acrylic foams made in this manner are disclosed in U.S. Patent No. 4,415,615 (Esmay et al.) and U.S. Patent No. 6,103,152 (Gehlsen et al.).

[0091] In some embodiments, the foam is formed by blending expanded polymeric microspheres into a polymerizable composition. In some embodiments, the foam is formed by blending expandable polymeric microspheres into a composition and expanding the microspheres. Expandable polymeric microspheres include a polymeric shell and a core material in the form of a gas, a liquid, or a combination thereof. When heated to a temperature equal to or below the melting or flow temperature of the polymeric shell, the polymeric shell expands to form a microsphere. Suitable core materials include propane, butane, pentane, isobutane, neopentane, isopentane, and combinations thereof. The thermoplastic resin used for the polymeric microsphere shell can affect the mechanical properties of the foam, and the properties of the foam can be adjusted by the selection of the microspheres or by the use of a mixture of different types of microspheres. Examples of commercially available expandable microspheres include those available under the trade designation "EXPANCEL" (e.g., under the trade designation "EXPANCEL 551 DE") from Akzo Nobel Pulp, Duluth, GA, and Performance Chemicals AB, Sundsvall, Sweden. Methods of making foams containing expandable polymeric microspheres and details of these microspheres are described in U.S. Patent No. 6,103,152 (Gehlsen et al.).

[0092] The foam is prepared by forming air voids in the composition using various mechanisms including, for example, mechanical mechanisms, chemical mechanisms, and combinations thereof. Useful mechanical foaming mechanisms include, for example, agitation (e.g., shaking, stirring, or jarring the composition, and combinations thereof), injecting a gas into the composition (e.g., inserting a nozzle under the surface of the composition and blowing gas into the composition), and combinations thereof. Methods of making foams having voids formed via a blowing agent are described in U.S. Patent No. 6,586,483 (Kolb et al.).

[0093] In some embodiments, the curable support foam layer has a foam density of 320 kilograms per cubic meter (kg / m 3 ) to 1041 kg / m 3 , 400 kg / m 3 to 880 kg / m 3 , or 561 kg / m 3 to 800 kg / m 3 .

[0094] In some embodiments, the curable foam support layer further comprises a polymer modulus modifier to provide a desired modulus. In some embodiments, the polymer modulus modifier comprises a polymer having a Tg of no greater than 100°C, no greater than 90°C, no greater than 80°C, no greater than 70°C, no greater than 60°C, no greater than 50°C, or no greater than 40°C. In some embodiments, the polymer modulus modifier comprises a polyvinyl acetal resin, particularly polyvinyl butyral (PVB). In some embodiments, the polymer modulus modifier includes a high acid polymer. It is believed that the polymer modulus modifier increases the modulus of the foam and / or toughens the system against applied forces.

[0095] In some embodiments, the polyvinyl acetal resin includes polymeric units having the following formula:

[0096] wherein R1is hydrogen or an alkyl group having 1 to 7 carbon atoms (C1-C7). The polyvinyl acetal resin can be obtained, for example, by reacting polyvinyl alcohol with an aldehyde, as known in the art. The polyvinyl alcohol resin is not limited by the method of preparation. For example, those prepared by saponification of polyvinyl acetate, for example, with a base, an acid, or aqueous ammonia, can be used. The polyvinyl alcohol resin can be fully saponified or partially saponified. In some embodiments, the polyvinyl alcohol resin has a degree of saponification of 80 mole% or greater. The polyvinyl alcohol resin can be used alone or in combination of two or more.

[0097] Examples of suitable aldehydes used in the preparation of the polyvinyl acetal resin include formaldehyde (including paraformaldehyde), acetaldehyde (including triacetaldehyde), propionaldehyde, butyraldehyde, n-octylaldehyde, valeraldehyde, hexaldehyde, heptaldehyde, 2-ethylhexaldehyde, cyclohexaldehyde, furfuraldehyde, glyoxal, glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, and ß-phenylpropionaldehyde. These aldehydes can be used alone or in combination of two or more.

[0098] In some embodiments, the alkyl residue of the aldehyde comprises 1 to 7 carbon atoms. In other embodiments, the alkyl residue of the aldehyde comprises 3 to 7 carbon atoms, such as in the case of butyraldehyde, hexanal, n-octylaldehyde. Of these aldehydes, butyraldehyde, also known as butanal, is most commonly used. Polyvinyl butyral (“PVB”) resins are commercially available under the trade designation MOWITAL from Kuraray and under the trade designation BUTVAR from Solutia.

[0099] In some embodiments, the polyvinyl acetal (e.g., butyral) resin has a Tg in the range of 60 °C to 80 °C or 60 °C to 75 °C. In some embodiments, the polyvinyl acetal (e.g., butyral) resin has a Tg of at least 65 °C, or at least 70 °C. When other aldehydes such as n-octylaldehyde are used in the preparation of the polyvinyl acetal resin, the Tg can be less than 65 °C, or even less than 60 °C. The Tg of the polyvinyl acetal resin is typically at least 35 °C, at least 40 °C, or at least 45 °C. When the polyvinyl acetal resin has a Tg below 60 °C, higher concentrations of high Tg monomers can be employed compared to those monomers used with polyvinyl butyral resins. When other aldehydes such as acetaldehyde are used in the preparation of the polyvinyl acetal resin, the Tg can be greater than 75 °C, or greater than 80 °C. When the polyvinyl acetal resin has a Tg greater than 70 °C, higher concentrations of low Tg monomers can be used compared to those monomers used with polyvinyl butyral resins.

[0100] The polyvinyl acetal (e.g., PVB) resins typically have a weight average molecular weight (Mw) of at least 10,000 g / mol, 15,000 g / mol, or 30,000 g / mol, and no greater than 100,000 g / mol, 80,000 g / mol, or 60,000 g / mol.

[0101] The polyacetal resins are typically random copolymers; however, block copolymers and tapered block copolymers can provide similar benefits as random copolymers. Examples of polyvinyl acetal resins are described in U.S. Patent Application Publication No. 2021 / 0102100 (Xia et al.).

[0102] In some embodiments, if used, the polyvinyl acetal resin is used in an amount of at least 5 wt%, at least 7 wt%, or at least 10 wt%, based on the total weight of the curable foam support layer composition. If used, the polyvinyl acetal resin is used in an amount of up to 25 wt%, up to 20 wt%, or up to 15 wt%, based on the total weight of the curable foam support layer composition.

[0103] In some embodiments, the polymer modulus modifier includes a high acid polymer. In this context, high acid means that the amount of acrylic acid in the acrylate polymer is higher than the amount of acrylic acid in a conventional pressure sensitive adhesive, such as 90:10 isooctyl acrylate:acrylic acid. This makes the polymer "harder" (i.e., has a higher modulus).

[0104] In some embodiments, the high acid polymer is a second (meth)acrylate copolymer including 15 wt% to 40 wt% of (meth)acrylic monomer units, based on the weight of the second (meth)acrylate copolymer for some embodiments of the curable adhesive film described above. In some embodiments, the high acid polymer has a Tg of 2°C to 100°C, 2°C to 80°C, 2°C to 60°C, 2°C to 50°C, 2°C to 45°C, 5°C to 45°C, 5°C to 40°C, 5°C to 35°C, or 10°C to 30°C. It is believed that the high acid polymer provides excellent mechanical properties, particularly due to the relatively high concentration of (meth)acrylic monomer units.

[0105] In some embodiments, if used, the high acid polymer is used in an amount of at least 1 wt%, at least 2 wt%, at least 3 wt%, or at least 4 wt%, based on the total weight of the curable foam support layer. If used, the high acid polymer is used in an amount of up to 35 wt%, up to 30 wt%, up to 25 wt%, up to 20 wt%, or up to 15 wt%, based on the total weight of the curable foam support layer.

[0106] The curable foam support layer and the curable adhesive film can contain one or more optional additives. Such additives can include fillers, antioxidants, viscosity regulators, pigments (inorganic or organic), tackifying resins, fibers, flame retardants, antistatic and slip agents, thermally conductive particles, electrically conductive particles, continuous microfibers, filaments, and mixtures thereof. The various additives can be used in amounts typically used for adhesive tapes.

[0107] In addition to the hollow microspheres described above, useful fillers include glass beads, metal oxide particles, silica particles (e.g., fumed silica), carbonates, metal oxides, silicates (e.g., talc, asbestos, clay, mica), sulfates (e.g., barium sulfate), metals in powder form (e.g., aluminum, zinc, and iron), silica, and aluminum trihydrate. In some embodiments, the solid or hollow filler particles comprise a polymer, glass, ceramic, or metal oxide material. If desired, a combination of two or more fillers can be used. In some embodiments, the filler includes fumed silica.

[0108] Examples of useful organic pigments include halogenated copper phthalocyanines, aniline black, anthraquinone black, benzimidazolone, azo condensates, arylamides, diarylides, disazo condensates, isoindolinone, isoindoline, quinophthalone, anthrapyrimidine, flavanthrone, pyrazolone orange, perinone oranges, beta-napthol, BON arylamides, quinacridone, perylene, anthraquinone compounds, dibromoanthracene, pyranthrones, diketopyrrolopyrrole pigments (DPP), dioxazine violet, copper and copper-free phthalocyanines, and indanthrone. Examples of useful inorganic pigments include titanium dioxide, zinc oxide, zinc sulfide, lithopone, antimony oxide, barium sulfate, carbon black, graphite, black iron oxide, black mica iron oxide, brown iron oxide, metal complex browns, lead chromate, cadmium yellow, yellow oxide, bismuth vanadate, lead chromate, lead molybdate, cadmium red, red iron oxide, Prussian blue, ultramarine, cobalt blue, chromium green (Brunswick green), chromium sesquioxide, hydrated chromium sesquioxide, organic metal complexes, and lake dye pigments.

[0109] The polymer used to make the curable foam support layer can be initially coated onto a flexible backing sheet (e.g., a release liner) having a low-adhesion surface from which the polymerized layer can be easily removed, and polymerized against. If the opposite side of the backing sheet also has a low-adhesion surface, the backing sheet with its polymerized layer can be wound into a roll form for storage prior to assembly into the finished adhesive article.

[0110] The curable or cured foam support layer in the articles of the present disclosure can have any suitable thickness. In some embodiments, the thickness is at least 20 microns, at least 25 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 250 microns, at least 300 microns, or at least 350 microns. In some embodiments, the thickness is no more than 2000 microns, no more than 1000 microns, or no more than 500 microns.

[0111] The multiple layers of curable adhesive films in the tape that can be used in the adhesive systems of the present disclosure can include two or more curable adhesive films having the same or different components (i.e., they are independently selected). The multiple layers of curable adhesive films can include two or more curable foam support layers having the same or different components (i.e., they are independently selected). In some embodiments, the multiple layers of curable adhesive films further include a second curable adhesive layer comprising: a second film of a second independently selected polymer; a second independently selected unsaturated free-radically polymerizable group capable of bonding to the second independently selected polymer or in a second species different from the second independently selected polymer; and a second independently selected transition metal cation. In some embodiments, the second curable adhesive layer is adjacent to a surface of the foam support layer opposite the first layer.

[0112] The adhesive systems of the present disclosure include a solid activator composition comprising an oxidizing agent. The solid activator composition is solid at normal temperature and pressure. The solid activator composition can be used as an activator for a tape. In some embodiments, the solid activator composition is not a self-supporting film. In other words, the film of the solid activator composition does not have mechanical integrity independent of contact with any support material (e.g., a release liner or a substrate to be bonded). When the solid activator composition is not a self-supporting film, the solid activator composition can retain its shape; however, the intact film of the solid activator composition cannot be removed from the support material on which it is deposited. The solid activator composition can be in the form of a crayon or a paste.

[0113] In the method of bonding a first substrate according to the present disclosure, the solid activator composition is applied to the substrate and then the solid activator composition is contacted with the curable adhesive film on the first surface of the tape as described above in any of its embodiments. Reference is made to Figure 3 (not drawn to scale), in one embodiment, the configuration 300 includes a tape 310 and substrates 320 and 330. As Figure 3As illustrated, a solid activator composition 370 is applied to the first substrate 320 and a solid activator composition 380 is applied to the second substrate 330. The solid activator compositions 370 and 380 can be the same or different. According to one embodiment of the disclosure, a double-sided tape 310 including the curable adhesive films 340 and 360 adjacent to the support layer 350 is applied to the solid activators 370 and 380 on the substrates 320 and 330 such that the curable adhesive films 340 and 360 are in contact with the solid activator compositions 370 and 380, respectively. In some embodiments, the assembly is held by an external force (e.g., a clamp) until the curable adhesive films become cured; however, in other embodiments, the tackiness of the tape alone holds the assembly until cured. The tape is cured to form a cured structural adhesive layer from the curable adhesive films 340 and 360 adjacent to the solid activator compositions 370 and 380. In some embodiments, the support layer 350 can also be cured. In some embodiments, the support layer 350 is a foam support layer.

[0114] Applying the solid activator compositions 370 and 380 to the one or more substrates 320 and 330 can be done by at least one of rubbing or spreading. For example, a wax pencil containing the solid activator composition can be rubbed on the substrates 320 and 330. In another example, the solid activator composition in the form of a paste can be spread on the substrates 320 and 330 using any suitable tool. The solid activator compositions 370 and 380 can be cured or uncured in the final construction, in Figure 3 In the illustrated embodiment, the final construction includes two substrates bonded together by a double-sided tape using a structural adhesive. In some embodiments, the solid activator composition does not include an unsaturated free-radically polymerizable group. In some embodiments, the solid activator composition is not curable at the time of application and is not cured in the final structural construction.

[0115] As described in any of the embodiments above and below, the first substrate and the second substrate in the methods of the disclosure can be composed of any suitable material. Suitable substrate materials include metals (e.g., aluminum, titanium, stainless steel, and steel), polymeric materials (e.g., polyolefins, polyethylenes, polypropylenes, polystyrenes, poly(meth)acrylates, polyurethanes, natural or synthetic rubbers, and polydienes), natural materials (e.g., wood and stone) or derivatives thereof (e.g., composite boards and concrete), glass materials, and ceramic materials. If two substrates are bonded together in the articles and processes of the disclosure, the two substrates are independently selected.

[0116] In some embodiments, at least one of the surface of the first substrate or the surface of the second substrate comprises at least one of a metal, a glass, a polymer, a paper, a painted surface, a nonwoven or woven fabric, a wood, a foam, or a composite material. The material of the surface of the first substrate and the second substrate can be found throughout the substrate, or the surface can comprise a different material than the bulk of the substrate. In some embodiments, the surface of the first substrate and / or the second substrate comprises at least one of a metal (e.g., steel, stainless steel, or aluminum), a glass (e.g., which can be coated with indium tin oxide), a polymer (e.g., a plastic, a rubber, a thermoplastic elastomer, or a thermoset), a paper, a painted surface, or a composite material. A composite material can be made from any two or more constituent materials having different physical or chemical properties. When the components are combined to make a composite material, a material having properties different from the individual components is often obtained. Some examples of useful composite materials include fiber-reinforced polymers (such as carbon fiber-reinforced epoxy and glass-reinforced plastic); metal matrix composites; and ceramic matrix composites. The surface of at least one of the first substrate or the second substrate can comprise a polymer such as a polyolefin (e.g., polypropylene, polyethylene, high-density polyethylene, polypropylene blend), polyamide 6 (PA6), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), PC / ABS blend, polyvinyl chloride (PVC), polyamide (PA), polyurethane (PUR), thermoplastic elastomer (TPE), polyoxymethylene (POM), polystyrene, polyester (e.g., polyethylene terephthalate), poly(meth) methacrylate (PMMA), and combinations thereof. The surface of at least one of the first substrate or the second substrate can also comprise a metal coating on such a polymer. In some embodiments, at least one of the first substrate or the second substrate comprises a transparent material such as a glass or a polymer (e.g., acrylic or polycarbonate).

[0117] In some embodiments, the tapes that can be used in the adhesive systems of the present disclosure further comprise: one or more barrier film support layers (having two major surfaces); one or more conventional adhesive layers (having two major surfaces) comprising an adhesive that is not curable upon contact with a solid activator; and / or a tape backing material or release liner typically used in multilayer tapes. For example, the double-sided tapes of the present disclosure can comprise only one curable adhesive film, and in some embodiments a curable foam support layer, and can comprise a secondary adhesive layer that is not curable upon contact with a solid activator composition.

[0118] As Figure 4(not drawn to scale) shown, the tape 410 includes a curable adhesive film 440 and a secondary adhesive layer 460, which can be any of a variety of conventional adhesives (e.g., pressure sensitive adhesives) that are not curable upon contact with a solid activator composition, each of the curable adhesive film and the secondary adhesive layer being adjacent opposite surfaces of a support layer 450. Examples of conventional adhesives include: pressure sensitive adhesives that are tacky and bond immediately upon the application of pressure; thermoplastic adhesives that bond with the application of heat and pressure and are reversible with heat; and thermoset adhesives that bond when subjected to heat and pressure for a predetermined period of time so as to cause some irreversible chemical reaction to occur. In some embodiments, the secondary adhesive layer 460 is a conventional pressure sensitive adhesive that achieves a lower bond strength than the curable adhesive film 440 of the activator applied to the substrate.

[0119] One or more barrier film support layers (i.e., barrier layers) can be used in the tape in the adhesive systems of the present disclosure to provide, for example, a barrier to migration of, for example, oxidizing agents and / or cross-linkable species. For example, Figure 1 The described types of tapes can also include a barrier film support layer adjacent a major surface of a support layer opposite a major surface of a curable adhesive film, such that a 3-layer tape including curable adhesive / support layer / barrier is formed. In another example, Figure 2 The described types of tapes can also include a barrier film support layer disposed between a support layer and one of the curable adhesive films. In this embodiment, a first curable adhesive film is adjacent a support layer, which is adjacent a barrier film support layer, which is adjacent a second curable adhesive film, such that a 4-layer tape including curable adhesive / support layer / barrier / curable adhesive is formed. In some embodiments, the support layer is a foam. In some embodiments, the support layer is curable. In some embodiments, the first curable adhesive film is adjacent a curable foam support layer, the barrier film support layer is adjacent a surface of the curable foam support layer opposite the first curable adhesive film, and the second curable adhesive film is adjacent a surface of the barrier film support layer opposite the curable foam support layer.

[0120] In another example, a multi-layer tape can be prepared from Figure 1 Two of the described types of tapes, with a barrier film support layer disposed between the support layers of the two tapes, such that a 5-layer tape including curable adhesive film / support layer / barrier / support layer / curable adhesive film is formed. In some embodiments, the support layers are foams. In some embodiments, the support layers are curable.

[0121] In yet another example, a multi-layer tape can be prepared from Figure 2The illustrated method involves the fabrication of two double-sided tapes, with a barrier film support layer disposed between the two tapes, forming a seven-layer tape comprising a curable adhesive film / support layer / curable adhesive film / barrier element / curable adhesive film / support layer / curable adhesive film. Specifically, in this embodiment, a first curable adhesive film, a first support layer, a second curable adhesive film, a barrier film support layer, a third curable adhesive film, a second support layer, and a fourth curable adhesive film are sequentially stacked. In some embodiments, the support layer is foam. In some embodiments, the support layer is curable.

[0122] More specifically, such as Figure 5 As shown (not drawn to scale), the tape 510 includes a first curable adhesive film 540 and a second curable adhesive film 560, each of which is adjacent to the opposite main surface of the first support layer 550. The tape 510 also includes a third curable adhesive film 540' and a fourth curable adhesive film 560', each of which is adjacent to the opposite main surface of the second support layer 550'. The curable adhesive film 560 has a surface 562 adjacent to the first surface 592 of the barrier film support layer 590, and the curable adhesive film 560' has a surface 562' adjacent to the second surface 594 of the barrier film support layer 590. The barrier film support layer 590 prevents crosslinkable substances and / or oxidants from migrating through it. Therefore, different curing mechanisms and curable components can be used on either side of the barrier layer (i.e., within layers 540 / 550 / 560 compared to layers 540' / 550' / 560'). In some embodiments of the method disclosed herein, when bonding the tape 510 to a first substrate (e.g., via a third curable adhesive film 540'), a tape 510 comprising a barrier layer 590 (a solid activator composition) is used. Layers 540' / 550' / 560' cure to form a cured structural adhesive layer, while the barrier layer 590 prevents the curing of layers 540 / 550 / 560. Another independently selected solid activator composition can be used to bond the tape 510 to a second substrate via a first curable adhesive film 540. Layers 540 / 550 / 560 can then be cured to form a structural adhesive layer. In this embodiment, the strip can be applied to the substrate at a first time or location and bonded to an activated second substrate at a later time or location, thereby providing flexibility when manufacturing bonded articles using the adhesive system of this disclosure.

[0123] In some embodiments of the method for preparing adhesive articles according to this disclosure (such as...) Figure 6In the illustrated embodiment, a double-coated tape 610 including curable adhesive films 640 and 660 adjacent to a single support layer 650 according to some embodiments of the present disclosure is applied to a second substrate 630 such that curable adhesive film 660 is in contact with the second substrate 630. In some embodiments, the support layer is a foam. In some embodiments, the support is curable. A solid activator composition 670 in an adhesive system of the present disclosure is applied to a first substrate 620. After the tape and the solid activator composition are applied to their respective substrates and allowed to sit for any independently selected length of time, the solid activator 670 and the curable adhesive film 640 of the double-coated tape 610 are brought into contact. Once the solid activator 670 and the curable adhesive film 640 are brought into contact, curing begins and continues through the foam support layer 650 and the curable adhesive film 660. The tape cures to form a cured structural adhesive layer from the curable adhesive films 640 and 660 and the cured foam support layer 650. In some embodiments, the assembly is held by an external force (e.g., a clamp) until the curable adhesive films become cured; however, in other embodiments, the tackiness of the tape alone holds the assembly until curing. The solid activator composition 670 can be cured or uncured in the final cured construct 600 including two substrates bonded together by a double-coated tape including a structural adhesive bond. The solid activator composition can be applied using any of the methods described above in connection with the embodiments of the present disclosure. Figure 3

[0124] In some embodiments of the adhesive systems and methods of the present disclosure, the tape can be attached to a substrate at a point of manufacture and bonded at a different time and / or location. In some embodiments, the tape can be attached to a first substrate at a point of manufacture and optionally covered with a conventional release liner for any period of time before the tape is bonded to an activated second substrate. The solid activator composition can be applied to a second substrate at a second point of manufacture and the first substrate with the tape thereon and the activated second substrate can be bonded at the second point of manufacture or even at a third time and / or location. Thus, the tape can be applied to a substrate at a first time or location and bonded to an activated second substrate at a later time or different location, providing flexibility in manufacturing bonded articles using the adhesive systems of the present disclosure.

[0125] ​In some embodiments of the methods of the present disclosure, the method comprises: applying the tape as described above in any of its embodiments to a first substrate; applying the solid activator composition as described above in any of its embodiments to a second substrate; and contacting the tape on the first substrate and the activator on the second substrate to bond the first substrate and the second substrate. In some embodiments, the tape is applied for at least 1 day, 3 days, or 5 days or at least 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, or 6 weeks before contacting the tape on the first substrate and the activator on the second substrate. In some embodiments, the tape is covered with a release liner for any of the times described above, and in some embodiments, the release liner is removed before contacting the tape on the first substrate and the activator on the second substrate.

[0126] In some embodiments of the adhesive systems and methods of the present disclosure, Figure 7 The illustrated article 700 can be useful. The article 700 includes a curable adhesive film 740 and an oxygen-permeable liner 725 on at least one side of the curable adhesive film. The curable adhesive film 740 includes: a film of a polymer; unsaturated free-radically polymerizable groups that are capable of bonding to the polymer or in a substance other than the polymer; transition metal cations; and an oxidizing agent. Figure 7 The illustrated embodiment also includes a first substrate 720. The illustrated embodiment can be made by a process that includes: applying a solid activator composition 730 to the substrate 720, where the activator includes an oxidizing agent; applying an adhesive film directly on the substrate 720 adjacent to the solid activator composition 730; and joining the adhesive film with an oxygen-permeable liner. The adhesive film includes a film of a polymer, unsaturated free-radically polymerizable groups, and transition metal cations. Typically, the oxidizing agent of the solid activator composition 730 migrates into the adhesive film. However, oxygen inhibits the curing of the curable adhesive film. Thus, when the oxygen-permeable liner is in place, the curable adhesive film does not cure for a period of days or weeks. In some embodiments, the process of making the illustrated embodiment includes forming the adhesive film on the oxygen-permeable liner and applying the adhesive film adjacent to the activator while the adhesive film is in contact with the oxygen-permeable liner.

[0127] In some embodiments of the adhesive systems and methods of the present disclosure, Figure 8 The illustrated article 800 can be useful. The article 800 includes a curable adhesive film 840 and an oxygen-permeable liner 825 on at least one side of the curable adhesive film. The curable adhesive film 840 includes: a film of a polymer; unsaturated free-radically polymerizable groups that are capable of bonding to the polymer or in a substance other than the polymer; transition metal cations; and an oxidizing agent. In Figure 8In the illustrated embodiment, the oxygen-permeable liner 825 includes ridges 827 on at least one surface 826. The ridges can have a height in the range of 4 micrometers (pm) to 200 pm, 8 pm to 100 pm, or 10 pm to 30 pm. In these embodiments, the ridges can be considered microstructures. The ridges can have a regular pattern or can present random spacing and can have a variety of cross-sectional shapes. The curable adhesive film 840 includes channels 843 corresponding to the ridges 827 in the surface 846. Such channels can aid in air escape during application of the film behind the surface 846. The channels and methods of their production can be as taught in U.S. Patent No. 6,655,281 (Jordan et al.).

[0128] Figure 8 The illustrated embodiment also includes a release liner 815. The illustrated embodiment can be made by applying a solid activator composition 830 to the release liner 815, where the solid activator composition includes an oxidizing agent. Then, an adhesive film including a polymer, unsaturated free-radically polymerizable groups, and transition metal cations (conveniently formed on an oxygen-permeable liner including ridges) can be applied directly to the release liner adjacent to the activator 830. Typically, the oxidizing agent of the activator 230 migrates into the adhesive film; however, oxygen inhibits the cure of the curable adhesive film. Thus, when the oxygen-permeable liner is in place, the curable adhesive film does not cure over a period of days or weeks. While in Figure 8 Not shown in the illustrated embodiment, but also air release channels 843 can be formed in the opposite surface of the adhesive film, which can aid in improved contact when the adhesive film is applied to the solid activator composition.

[0129] Figure 9 Another embodiment of a method of bonding a first substrate according to the present disclosure is illustrated. The method includes using an article 900 (such as Figure 7 the illustrated article 700) to bond a first substrate and a second substrate. Figure 9 The illustrated process includes removing the oxygen-permeable liner 925 to expose the curable adhesive film 940. While in Figure 9 the illustrated embodiment, the curable adhesive film 940 can also be a first layer of a multilayer curable adhesive film 110, 210 as Figure 1 or Figure 2 illustrated. After removing the oxygen-permeable liner 925, the process includes bonding a second substrate 980 to the curable adhesive film 940. In some embodiments, the bonded article is held by an external force (e.g., a clamp) until the curable adhesive film cures; however, in other embodiments, the tackiness of the curable adhesive film alone holds the assembly until the curable adhesive film cures. Once cured, the curable adhesive film 940 provides a structural adhesive layer.

[0130] In some embodiments of the process for making a bonded article 905, the process further comprises applying an optional solid activator composition 935 to the second substrate 980 prior to bonding the second substrate 980 to the curable adhesive film 940. The optional solid activator composition 935 comprises a second oxidizing agent, wherein the second oxidizing agent is the same as or different from the oxidizing agent in the first solid activator 930. Typically, the oxidizing agent of the activator composition 935 migrates into the curable adhesive film 940 to participate in the cure of the curable adhesive film 940, thereby forming a structural adhesive layer. After curing, the bonded article 905 comprises the first substrate 920 and the second substrate 980 bonded together with a structural adhesive made from the first solid activator composition 930, the curable adhesive film 940, and the optional solid activator 935.

[0131] Figure 10 Another embodiment of a method of bonding a first substrate according to the present disclosure is illustrated. The method comprises using two independently selected articles 1000, 1000a (such as Figure 7 the article 700 shown) to bond a first substrate and a second substrate. Figure 10 The process illustrated comprises removing the oxygen-permeable liner 1025 from the two articles 1000 and 1000a to expose the curable adhesive films 1040 on the two articles 1000 and 1000a. The two articles 1000, 1000a can be the same as or different from each other, the article comprising a first substrate 1020 and a second substrate 1080 that can be the same as or different from each other, a curable adhesive film 1040 that can be the same as or different from each other, and an oxygen-permeable liner 1025 that can be the same as or different from each other. While not illustrated in Figure 10 , one or more of the curable adhesive films 1040 can also be a multilayer curable adhesive film 110, 210 as shown in Figure 1 and Figure 2 . As shown in Figure 10 , the curable adhesive films 1040 are positioned in contact with each other once the oxygen-permeable films are removed, and then bonded together. In some embodiments, the bonded article is held by an external force (e.g., a clamp) until the curable adhesive films cure; however, in other embodiments, the tackiness of the curable adhesive films alone holds the assembly together until the curable adhesive films cure. Once cured, the curable adhesive films 1040 provide a structural adhesive layer.

[0132] Figure 11 Another embodiment of a method of bonding a first substrate according to the present disclosure is illustrated. The method comprises using an embodiment of an article similar to Figure 8 the article shown in Figure 11The ridge 827 or the channel 843 are not shown in Figure 11 The curable adhesive film 840, not exemplified in Figure 1 and Figure 2 the first layer of the multi-layer curable adhesive film 110, 210 as shown. Figure 11 The exemplified process includes removing the release liner 1115 to provide the first adhesive surface 1148; removing the oxygen-permeable liner 1125 to provide the second adhesive surface 1146; bonding the first adhesive surface 1148 to the first substrate 1120; and bonding the second adhesive surface 1146 to the second substrate 1180. The removal of the oxygen-permeable liner 1125 and the release liner 1115 can be performed simultaneously or sequentially in any order. Likewise, the bonding of the first adhesive surface 1148 to the first substrate 1120 and the bonding of the second adhesive surface 1146 to the second substrate 1180 can be performed simultaneously or sequentially in any order. The bonding of the first adhesive surface 1148 to the first substrate 1120 can be performed prior to the removal of the oxygen-permeable liner 1125, or the bonding of the second adhesive surface 1146 to the second substrate 1180 can be performed prior to the removal of the release liner 1115. In some embodiments, the bonded article is held by an external force (e.g., a clamp) until the curable adhesive film is cured; however, in other embodiments, the tackiness of the curable adhesive film alone holds the assembly until the curable adhesive film is cured. Once cured, the curable adhesive film 1140 provides a structural adhesive layer.

[0133] In some embodiments of the process for making the bonded article 1105, the method further includes applying a solid activator composition 1135 to at least one of the first substrate 1120 or the second substrate 1180 prior to bonding the first adhesive surface 1148 and the second adhesive surface 1146 to the first substrate 1120 and the second substrate 1180, respectively. In some embodiments, the solid activator composition 1135 is applied to only one of the first substrate 1120 or the second substrate 1180. In some embodiments, the solid activator composition 1135 is applied to both the first substrate 1120 and the second substrate 1180. The optional solid activator composition 1135 includes a second oxidizing agent, where the second oxidizing agent is the same as or different from the oxidizing agent in the first solid activator composition 1130. The solid activator composition 1135 and their components applied to the first substrate 1120 and the second substrate 1180 can be the same or different. Typically, the oxidizing agent of the solid activator 1135 migrates into the curable adhesive film 1140 to participate in the cure of the curable adhesive film 1140 to form a structural adhesive layer.

[0134] Figure 11The illustrated embodiments do not include ridges on the oxygen-permeable liner 1125 or release liner 1115. In other embodiments, one or both of the oxygen-permeable liner 1125 or release liner 1115 has ridges on the surface that contacts the curable adhesive film 1140 to provide channels in the curable adhesive film. Returning to Figure 8 When the curable adhesive film has channels 843 in one surface 846 but not in the other surface, the surface without channels can be placed on the first substrate 820 and then the second substrate 880 can be contacted with the surface 846 that includes channels. This approach can be useful, for example, where two rigid substrates are to be joined, as it allows for outgassing and accommodation of uneven surfaces, despite the substrates being non-flexible.

[0135] Any oxygen-permeable liner that allows sufficient oxygen to pass through to inhibit curing of the unsaturated free-radically polymerizable groups can be used in the articles and processes of the present disclosure. Suitable materials for the liner include paper, polyvinyl chloride (PVC), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polystyrene (PS), and polyolefins (e.g., polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), biaxially oriented polypropylene (BOPP)). In some embodiments, the oxygen-permeable liner includes at least one of paper or a polyolefin. The oxygen-permeable liner can have a low adhesion surface provided, for example, by silicone, fluoropolymer, urethane, acrylic, urethane, or polyolefin. In some embodiments, examples of useful release agents that can be coated on the oxygen-permeable liner include silicone copolymers (e.g., silicone acrylate, silicone urethane, and silicone polyurea), fluoro-silicone, perfluoropolyether, polyethylene, polypropylene, low density polyethylene, and combinations thereof. In some embodiments, the oxygen-permeable liner is a poly-coated kraft paper (i.e., paper coated with polyethylene), which can or can not be silicone-coated.

[0136] In some embodiments, the curable adhesive film is stable at room temperature for at least two weeks. In some embodiments, the curable adhesive film applied over the oxygen-permeable liner is at least 1 day, 3 days, or 5 days or at least 1 week, 2 weeks, 3 weeks, or 4 weeks old before the oxygen-permeable liner is removed and the curable adhesive film is bonded to a second substrate. Thus, the curable adhesive film can be applied to a substrate at a first time or first location and bonded to a second substrate at a later time or different location, providing flexibility in manufacturing bonded articles using the articles and processes of the present disclosure.

[0137] While it is possible to attach the curable adhesive film without oxidizer to the first substrate at a point of manufacture, and to apply the activator containing oxidizer to the second substrate at a second point of manufacture, and to bond the first substrate and activated second substrate at the second point of manufacture or even at a third time and / or place, it is Figure 7 to Figure 11 The exemplified method provides even greater flexibility, as it is possible that the second substrate does not even need to be activated to achieve sufficient bonding. Moreover, allowing the oxidizer to migrate throughout the curable adhesive film for a longer period of time while the curable adhesive film is covered with the oxygen permeable liner can provide a stronger structural adhesive bond more quickly once the oxygen permeable liner is removed and the curable adhesive film is bonded to the second substrate.

[0138] While U.S. Patent Application No. 2020 / 0362204, U.S. Patent Application No. 2021 / 0102095, and U.S. Patent Application No. 2021 / 0102097, each to Ranade et al., describe adhesive systems as described above in a construction including a release liner, the purpose of the release liner is to exclude oxygen. The release liner is considered to preferably remain in place until curing is complete. The ability of the oxygen permeable liner in the articles of the present disclosure to provide stability to the curable adhesive film including unsaturated free-radically polymerizable groups, transition metal cations, and oxidizer for two weeks or more is quite unexpected. In this context, when referring to the curable adhesive film being stable at room temperature for at least two weeks, it is meant that the dynamic shear adhesion to aluminum does not decrease to less than 90% of the initial adhesion value measured on the day the curable adhesive film is applied to the activator as measured in the Examples below.

[0139] As described above in connection with Figure 8 and Figure 11 The release liner can be an oxygen permeable liner as described in any of the embodiments above. However, the release liner need not be oxygen permeable and can include other materials such as ethylene vinyl acetate, polyurethane, cellulose acetate, polyvinylidene fluoride, and polyesters such as polyethylene terephthalate. The release liner can be coated with a layer of release agent such as silicone, fluoropolymer, urethane, acrylic, or polyolefin, including any of those described above in connection with the oxygen permeable liner. The coating can be present on both sides of the release liner and the liners can be the same or different. Suitable release liners include commercially available liners having a silicone release coating on a polyethylene terephthalate film. The release liner can have ridges on its surface as described above in connection with any of the embodiments of the oxygen permeable liner.

[0140] In some embodiments of the methods disclosed herein, including the methods described above in any of its embodiments, rubbing a solid activator composition onto or spreading a solid activator composition onto at least one of the surfaces of a first substrate or a second substrate comprises: rubbing the solid activator composition onto discontinuous portions of the first or second substrate or spreading the solid activator composition onto discontinuous portions of the first or second substrate without applying the solid activator composition to other portions of the first or second substrate. In embodiments where the solid activator composition is a crayon, the solid activator composition can be easily applied in any desired pattern. Upon contact with the solid activator composition, the curable adhesive film begins to cure, thereby forming a structural adhesive domain; however, the inventors have found that this curing exhibits limited propagation within the plane of the adhesive film. Therefore, cured structural adhesive domains are formed adjacent to the solid activator composition, while uncured pressure-sensitive adhesive domains may remain on the portions of the first substrate to which the solid activator composition was not applied. The structural adhesive domains may constitute 1% to 99%, 1% to 75%, 1% to 50%, 1% to 25%, 75% to 99%, 50% to 99%, 25% to 99%, or any desired portion of the adhesive film, wherein the remainder of the adhesive film is a pressure-sensitive adhesive domain. Any suitable structural adhesive domain pattern may be used, such as straight lines, curves, diagonal lines, or dashed lines; squares, rectangles, triangles, hexagons, or other polygonal grids; or it may be random or ordered dots of circular, elliptical, polygonal, or other shapes. Pattern features may have any desired width and / or spacing dimensions. In various embodiments, the structural adhesive domains may be continuous or discontinuous, and the pressure-sensitive adhesive domains may be continuous or discontinuous. In some embodiments, the structural adhesive domains are discontinuous and surrounded by continuous pressure-sensitive adhesive domains, for example, different columns of the structural domains are arranged separately by continuous pressure-sensitive adhesive domains. In some embodiments, discontinuous pressure-sensitive adhesive domains are surrounded by continuous structural adhesive domains.

[0141] Solid activator compositions that can be used in the adhesive systems and methods of this disclosure include an oxidizing agent. The solid activator is solid at room temperature and pressure. In some embodiments, the solid activator is not a self-supporting membrane. The solid activator may be in the form of a crayon or paste. Any suitable oxidizing agent may be used in the adhesive systems, methods, or crayons of this disclosure. Suitable oxidizing agents include organic peroxides and hydroperoxides, inorganic peroxides, and persulfates.

[0142] Suitable organic peroxides include hydroperoxides, dimeroxides, ketone peroxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxy esters, and peroxydicarbonates. Suitable organic hydroperoxides include those represented by the formula ROOH, where R is a straight-chain alkyl group (e.g., C1-C1). 20 Straight-chain alkyl), branched-chain alkyl (e.g., C3-C) 20 Branched alkyl groups), cycloalkyl groups (e.g., C6-C) 12 cycloalkyl), alkylaryl (e.g., C7-C) 20 alkylaryl), aralkyl (e.g., C7-C) 20 Aryl groups and aryl groups (e.g., C6-C) 12 Aryl). Examples of suitable organic hydroperoxides include tert-butyl hydroperoxide, tert-amyl hydroperoxide, p-diisopropylbenzene hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, p-methane hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide. Suitable organic peroxides include those of formula R. 1 -OOR 2 -OOR 3 The diperoxide represents R, where R is a peroxide. 1 and R 3 Independently selected from H, straight-chain alkyl (e.g., C1-C6 straight-chain alkyl), branched alkyl (e.g., C1-C6 branched alkyl), cycloalkyl (e.g., C5-C6 branched alkyl), and cycloalkyl (e.g., C5-C6 branched alkyl). 10 cycloalkyl), alkylaryl (e.g., C7-C) 12 alkylaryl), aralkyl (e.g., C7-C) 20 Aryl groups or aryl groups (e.g., C6-C) 10 Aryl), and R 2Suitable ketone peroxides include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methyl cyclohexanone peroxide, and cyclohexanone peroxide. Suitable peroxy esters include a-cumyl peroxyneodecanoate, t-butyl peroxy pivalate, t-butyl peroxyneodecanoate, 2,2,4-trimethylpentyl peroxy-2- ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butyl peroxy- m- phthalate, di-t-butyl peroxyhexahydro-p- phthalate, t-butyl peroxy-3,3,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxy-maleate. Suitable peroxydicarbonates include di-3-methoxy peroxydicarbonate, di-2- ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl-1- peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, and diallyl peroxydicarbonate. Suitable diacyl peroxides include acetyl peroxide, benzoyl peroxide, decanoyl peroxide, 3,3,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide. Suitable dialkyl peroxides include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexane. Suitable peroxyketones include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, and n-butyl 4,4-bis(t-butylperoxy)valerate. Suitable organic peroxides can additionally include t-butyl peroxyethylhexyl carbonate, t-butyl trimethylhexyl peroxide, t-butyl ethylhexyl peroxide, t-amyl ethylhexyl peroxide, t-octyl ethylhexyl peroxide, t-amyl peroxyethylhexyl carbonate, t-butyl isopropyl peroxide, t-butyl peroxyneodecanoate, and t-butyl isobutyl peroxide.

[0143] Solid activator compositions that can be used in the adhesive systems and methods of the present disclosure can include a variety of polymeric compositions. For example, the solid composition can contain a starch derivative, a condensation product of an aldehyde and / or ketone with a polyol (e.g., a reaction product of sorbitol and benzaldehyde), or a plasticized rubber (e.g., a natural or synthetic rubber).

[0144] In some embodiments, the solid activator composition that can be used in the adhesive system, method, or crayon of the present disclosure comprises an acrylic polymer comprising crystalline monomer units having a side chain alkyl chain containing 16 to 50 carbon atoms and at least one other monomer unit. Useful crystalline monomer units include those from monomers where their homopolymer has a melting temperature in the range of 45 °C to 68 °C. The crystalline monomer units can be made from vinyl, acrylate, or methacrylate monomers. In some embodiments, the side chain alkyl chain has 16 to 40, 16 to 30, 16 to 22, or 18 to 22 carbon atoms. Typically, these are straight chain alkyl groups to promote crystallinity. Useful acrylate monomers for producing the crystalline monomer units include octadecyl acrylate, docosyl acrylate, triacontyl acrylate, tetracontyl acrylate, and pentacontyl acrylate, which have side chain alkyl chains having 18, 18 to 22, 26 to 34, 36 to 44, and 46 to 54 carbon atoms, respectively.

[0145] In some embodiments, the at least one other monomer unit in the acrylic polymer of the solid activator composition is a waxy monomer unit having a side chain alkyl chain containing 14 to 50 carbon atoms. Useful crystalline monomer units include those from monomers where their homopolymer has a melting temperature in the range of 25 °C to 44 °C. The crystalline monomer units can be made from vinyl, acrylate, or methacrylate monomers. In some embodiments, the side chain alkyl chain has 14 to 40, 14 to 30, 14 to 22, or 16 to 22 carbon atoms. Useful monomers can have some branching, and can be methacrylate, which can be used to disrupt crystallinity. Useful methacrylate monomers for producing the waxy monomer units include octadecyl methacrylate (i.e., stearyl methacrylate), docosyl methacrylate.

[0146] In some embodiments, at least one other monomer unit in the acrylic polymer of the solid activator composition is a monomer unit from a monomer that when homopolymerized provides a non-crystalline polymer. In some embodiments, the monomer unit results from a high Tg monomer. As used herein, the term "high Tg monomer" refers to a monomer that when homopolymerized has a Tg greater than 30 °C, greater than 40 °C, or greater than 50 °C (i.e., the homopolymer formed from the monomer has a Tg greater than 30 °C, greater than 40 °C, or greater than 50 °C). Some suitable high Tg monomers have a single (meth)acryloyl group, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl (meth)acrylate, cyclohexyl methacrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, phenyl acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl (meth)acrylate, 2-phenoxyethyl methacrylate, N-octyl (meth)acrylamide, and mixtures thereof. Other suitable high Tg monomers have a single vinyl group that is not a (meth)acryloyl group, such as, for example, various vinyl ethers (e.g., vinyl methyl ether), vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrenes (e.g., a-methyl styrene), vinyl halides, and mixtures thereof.

[0147] In some embodiments, at least one other monomer unit in the acrylic polymer of the solid activator composition is a non-crystallizable low Tg monomer. As used herein, the term "low Tg monomer" refers to a monomer that has a Tg of no greater than 20 °C when homopolymerized (i.e., a homopolymer formed from the low Tg monomer has a Tg of no greater than 20 °C). Suitable low Tg monomers are often selected from (meth)alkyl acrylates, (meth)heteroalkyl acrylates, aryl-substituted alkyl acrylates, and aryloxy-substituted alkyl acrylates. Examples of low Tg (meth)alkyl acrylate monomers are typically non-tertiary alkyl acrylates, but can be alkyl methacrylates having a linear alkyl group of at least 4 carbon atoms. Examples of (meth)alkyl acrylates include n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, sec-butyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, isoamyl acrylate, n-decyl acrylate, isodecyl acrylate, n-decyl methacrylate, lauryl acrylate, isotridecyl acrylate, n-stearyl acrylate, isostearyl acrylate, and n-dodecyl acrylate. Isomers of these monomers and mixtures of isomers can be used. Examples of low Tg (meth)heteroalkyl acrylate monomers typically have at least 3 carbon atoms, at least 4 carbon atoms, or at least 6 carbon atoms, and can have up to 30 or more carbon atoms, up to 20 carbon atoms, up to 18 carbon atoms, up to 16 carbon atoms, up to 12 carbon atoms, or up to 10 carbon atoms. Specific examples of (meth)heteroalkyl acrylates include 2- ethoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-methoxyethyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate. Examples of low Tg aryl-substituted alkyl acrylates or aryloxy-substituted alkyl acrylates include 2-biphenylhexyl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, and 2-phenylethyl acrylate.

[0148] In some embodiments, at least one other monomer unit in the acrylic polymer of the solid activator composition is derived from at least one of isooctyl acrylate, 2- ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, n-butyl acrylate, sec-butyl acrylate, ethyl acrylate, diethylene glycol methyl ether acrylate, triethylene glycol methyl ether acrylate, allyl glycidyl ether, ethyl vinyl ether, 2-ethylhexyl vinyl ether, hydroxyethyl acrylate, dodecyl methacrylate, dodecyl vinyl ether, polydimethylsiloxy, and amorphous polyether (meth)acrylate.

[0149] In some embodiments, at least one other monomeric unit in the acrylic polymer of the solid activator composition is an acrylic monomeric unit comprising a carboxylic acid group. Examples of suitable acrylic monomers comprising a carboxylic acid group to provide these monomeric units include methacrylic acid, acrylic acid, itaconic acid, maleic acid, fumaric acid, ethylacrylic acid, butenolic acid, citraconic acid, cinnamic acid, beta-carboxyethyl acrylate, and hydrogen-methacryloyloxyethyl succinate. In some embodiments, the acrylic monomeric unit comprising a carboxylic acid group is an acrylic acid monomeric unit or a methacrylic acid monomeric unit, in some embodiments an acrylic acid monomeric unit.

[0150] In some embodiments, at least one other monomeric unit in the acrylic polymer of the solid activator composition is a macromonomer monomeric unit. Suitable macromonomers are prepared from corresponding prepolymers of mixtures of, for example, octadecyl acrylate (ODA), behenyl acrylate (BeA), and tetradecyl acrylate (TDA), tetradecyl methacrylate (TDMA), hexadecyl acrylate (HDA), hexadecyl methacrylate (HDMA), ODA, methacrylate octadecyl (ODMA), eicosyl acrylate (ECA), eicosyl methacrylate (ECMA), and behenyl methacrylate (BeMA). In some embodiments, the final macromonomer melt temperature (T m ) is in the range of about 35°C to about 120°C, about 35°C to about 70°C, or about 45°C to about 60°C. The macromonomer is incorporated into the semi-crystalline polymer by standard polymerization techniques of the adhesive stick pencil polymers described herein. The preparation of the macromonomer can be carried out by polymerizing any of the monomers mentioned above in the presence of a functional chain transfer agent (e.g., 2-mercaptoethanol). The hydroxyl-terminated telechelic polymer can then be functionalized by reaction with acryloyl chloride, methacryloyl chloride, 2'-isocyanatoethyl methacrylate, 3-isopropenyl-alpha- or alpha-dimethylbenzyl isocyanate (IPDMBI), for example, as described in U.S. Patent No. 5,604,268 (Randen et al.).

[0151] In some embodiments, the acrylic polymer that may be used in the solid activator composition comprises, per 100 parts by weight, at least 5 to 96 parts by weight, or about 5 to 60 parts by weight, of at least one crystalline monomer having an alkyl carbon length of at least 16, typically not exceeding 50 carbon atoms; per 100 parts by weight, at least 4 to 70 parts by weight, or about 12 to 59 parts by weight, of the acrylic polymer having a homopolymer Tg below about 80°C; per 100 parts by weight, of acrylic polymer... The following are provided: 0 parts by weight to about 70 parts by weight of an acrylic polymer having at least 14 side chain alkyl carbons with an average length of at least 14 carbon atoms, typically not exceeding 50 carbon atoms; 0 parts by weight to about 10 parts by weight, or about 0.5 parts by weight to about 3 parts by weight of an acrylic polymer having acid or base functionality; and 0 parts by weight to about 40 parts by weight, or 0 parts by weight to about 30 parts by weight of an acrylic polymer having a melting temperature of about 35°C to about 120°C.

[0152] The crystalline monomer component and the non-crystalline monomer component can be selected such that, when combined, the non-crystalline component disrupts the crystallinity of the resulting adhesive polymer composition to the extent that the resulting composition will exhibit a melt temperature (Tm) not exceeding 60°C, 50°C, or 40°C, as measured by differential scanning calorimetry using the method described in U.S. Patent No. 11,267,997 (June et al.). In some embodiments, the composition will exhibit a primary Tm in the range of about 25°C to about 35°C.

[0153] In some embodiments, the acrylic polymers that can be used in the solid activator composition include octadecyl acrylate, octadecyl methacrylate, the macromonomer octadecyl acrylate, acrylic acid, and isooctyl acrylate (homopolymer, T). g (approximately -54°C), butyl methacrylate (homopolymer, T) g (approximately 20°C) or benzyl methacrylate (homopolymer, T) g The monomer unit is at least one of the following (approximately 54°C). Acrylic polymers can be readily produced by any of the methods described above for producing acrylic polymers.

[0154] In some embodiments, tackifiers can be present in solid activator compositions that can be used in the adhesive systems, methods, or crayons of the present disclosure. In some embodiments, the tackifier resin comprises at least one of a polyterpene (e.g., those based on a-pinene, b-pinene, or limonene), a terpene phenolic tackifier, a rosin acid, a rosin ester, an aliphatic hydrocarbon resin (e.g., those based on cis- or trans-piperylene, isoprene, 2-methyl-but-2-ene, cyclopentadiene, dicyclopentadiene, or combinations thereof), an aromatic resin (e.g., those based on styrene, a-methylstyrene, methylindene, indene, coumarone, or combinations thereof), or a mixed aliphatic-aromatic hydrocarbon resin. The aromatic hydrocarbon resin can be a C9-type petroleum resin obtained by copolymerizing a C9 fraction resulting from thermal decomposition of petroleum naphtha, and the aliphatic hydrocarbon resin can be a C5-type petroleum resin obtained by copolymerizing a C5 fraction resulting from thermal decomposition of petroleum naphtha. The mixed aliphatic / aromatic resin can be a C5 / C9-type petroleum resin obtained by polymerizing a combination of C5 and C9 fractions resulting from thermal decomposition of petroleum naphtha. Any of these tackifier resins can be hydrogenated (e.g., partially or completely). The term rosin, as used herein, includes refined or unrefined natural rosin (refined rosin will typically contain about 90 wt% rosin acids and about 10 wt% inert materials), such as wood creosote rosin, natural gum rosin, and tall oil rosin; refined or unrefined modified rosins, such as disproportionated rosin, hydrogenated rosin, polymerized rosin; and pure or substantially pure acids comprising rosin, alone or in mixtures. In some embodiments, the rosin includes at least one of abietic acid, neoabietic acid, palustric acid, levopimaric acid, pimaric acid, or isopimaric acid. In some embodiments, the rosin includes dehydrogenated or hydrogenated rosin acids, such as dehydroabietic acid, dihydroabietic acid, and tetrahydroabietic acid. The tackifier resin can also include metal salts of rosin acids (sometimes referred to in the art as metal resinate salts). The metal salt of rosin acid can be a metal salt (e.g., zinc, calcium, or magnesium) of any of the rosins described above. In some embodiments, the solid activator composition comprises 100 parts by weight of the solid activator composition from 0 parts by weight to about 50 parts by weight, or from about 5 parts by weight to about 40 parts by weight, of at least one tackifier. 19 H 29 COOH, in some embodiments, at least one of abietic acid, neoabietic acid, palustric acid, levopimaric acid, pimaric acid, or isopimaric acid. In some embodiments, the rosin includes dehydrogenated or hydrogenated rosin acids, such as dehydroabietic acid, dihydroabietic acid, and tetrahydroabietic acid. The tackifier resin can also include metal salts of rosin acids (sometimes referred to in the art as metal resinate salts). The metal salt of rosin acid can be a metal salt (e.g., zinc, calcium, or magnesium) of any of the rosins described above. In some embodiments, the solid activator composition comprises 100 parts by weight of the solid activator composition from 0 parts by weight to about 50 parts by weight, or from about 5 parts by weight to about 40 parts by weight, of at least one tackifier.

[0155] Crystalline additives with different functionalities such as acids, diacids, alcohols, diols, and linear hydrocarbon-based waxes can be added to the solid activator compositions that can be used in the adhesive systems, methods, or crayons of the present disclosure. The crystalline additives can be selected such that they are melt miscible with the acrylic polymers described above (i.e., will form a transparent single phase system when melted). Upon cooling, such additives can partially or fully crystallize and form a finely dispersed phase in the polymer. The crystalline additives can provide improved storage stability (i.e., resistance to creep and resistance to flow) to the polymer up to the melting point of the crystalline additive. In some embodiments, about 3 wt% to about 50 wt% can be included in the solid activator composition. The additives have normal alkyl chain lengths of at least 20 carbons and can have melting points of at least about 50 °C or at least about 70 °C. Examples of suitable crystalline additives include stearic acid, zinc stearate, calcium stearate, stearyl alcohol, docosanol, docosanoic acid, C-30 alcohol, or C-50 alcohol. In some embodiments, the solid activator composition comprises 100 parts by weight of the solid activator composition from 0 parts by weight to about 50 parts by weight, 3 parts by weight to 50 parts by weight, or 0 parts by weight to about 30 parts by weight of at least one crystalline additive.

[0156] In some embodiments, the solid activator composition comprises 100 parts by weight of the solid activator composition from 0 parts by weight to about 30, or from about 1 parts by weight to about 10 parts by weight of an oil. Examples of useful oils include olive oil, glycerol, mineral oil, low molecular weight polyethylene oxide, and low molecular weight polypropylene oxide.

[0157] In some embodiments, the solid activator composition comprises 100 parts by weight of the solid activator composition from 0 parts by weight to about 50, or from about 10 parts by weight to about 40 parts by weight of a surfactant. Examples of useful surfactants include anionic surfactants, non-ionic surfactants, and cationic surfactants such as block copolymers of stearic acid, ethylene oxide, propylene oxide, and blends thereof; C12-C50 alcohol ethoxylates, alkyl phenol ethoxylates, ethoxylated fatty acid esters, fatty acids, and ethoxylated fatty acids. Examples of commercially available surfactants suitable for practicing the present disclosure include those available under the trade names “UNITHOX” 420, 450, 480, 490, 550, 720, and 750 (from Baker Hughes), “TERGITOL” 15-S-3 and 15-S-20 (from Dow Chemical), “PLURONIC” F38, F87, F68, F98, F127, and P85 (from BASF), and “TETRONIC” 904, 908, 1107, 1304 (from BASF).

[0158] Fillers such as calcium carbonate, silica, bentonite clay, glass spheres and bubbles, and wood flour can be included in the solid activator composition. Dyes, pigments, and antioxidants can also be included. In some embodiments, the solid activator composition that can be used in the adhesive systems, methods, and crayons of the present disclosure comprises 0 to about 50 parts by weight of at least one filler per 100 parts by weight of the solid activator composition.

[0159] In some embodiments, the solid activator composition includes a plasticizer. In some embodiments, the plasticizer has the following formula: wherein each R can be hydrogen, C1-C 14 alkyl, aryl, alkylaryl, or arylalkyl, each optionally interrupted by oxygen, nitrogen, carbonyl, carboxyl, or carbamide; each X can be oxygen, nitrogen, carbonyl, carboxyl, or carbamide; Z can be hydrogen, C1-C 14 alkyl, aryl, alkylaryl, arylalkyl, C1-C 14 alkylene, arylene, alkylarylene, arylalkylene, each optionally interrupted by oxygen, nitrogen, carbonyl, carboxyl, or carbamide; and n is an integer from 1 to 5. In some embodiments, n is an integer from 1 to 4. In some embodiments, the plasticizer comprises at least one of a benzoate ester, a myristate ester, a citrate ester, an acetate ester, a succinate ester, a glutarate ester, an adipate ester, or a sebacate ester. In some embodiments, the plasticizer comprises at least one of a benzoate ester, a myristate ester, or a citrate ester. The citrate ester can have one, two, three, or four R groups.

[0160] In some embodiments, the solid activator composition further comprises a film- forming polymer. The film-forming polymer can be any of those described herein for the curable adhesive film. In some embodiments, the film-forming polymer is a reactive polymer comprising unsaturated free-radically polymerizable groups, as described herein for the curable adhesive film. In some embodiments, the film-forming polymer does not comprise unsaturated free-radically polymerizable groups, as described herein for the curable adhesive film.

[0161] In some embodiments, the film-forming polymer can include a rubber and / or a (meth)acrylic resin. In some embodiments, the (meth)acrylic resin is a (meth)acrylic polymer made from any of the monomers described above for the curable adhesive film and the curable foam support layer. In some embodiments, the (meth)acrylic polymer is any of those described above for the curable adhesive film and the curable foam support layer.

[0162] In some embodiments, the rubber that can be used in the solid activator composition comprises a block copolymer of styrene and an olefin. In some embodiments, the rubber comprises a styrene-ethylene / butylene-styrene triblock copolymer. In some embodiments, the rubber comprises a styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride. In some embodiments, the rubber comprises at least one of a styrene-isoprene-styrene copolymer, a styrene-butadiene-styrene copolymer, a styrene-ethylene-butylene-styrene copolymer. Linear and star block copolymers, and combinations thereof, can be useful. Plasticizers, including any of those described above, can be used to formulate the rubber into a paste.

[0163] In some embodiments, the oxidizing agent is present in the solid activator composition in an amount of at least 0.5 wt%, at least 1 wt%, at least 2 wt%, or at least 4 wt%, based on the total weight of the solid activator composition. In some embodiments, the oxidizing agent is present in the activator in an amount of at most 20 wt%, at most 15 wt%, at most 10 wt%, or at most 5 wt%, based on the total weight of the solid activator composition.

[0164] In some embodiments, the activator further includes a transition metal cation, which can be one or more of any of those described herein for the curable adhesive film. In some embodiments, the activator further includes a silane (e.g., an epoxy silane).

[0165] In some embodiments, the solid activator composition can be in the form of a self-supporting film. The self-supporting film can include any of the rubbers described above, any of the plasticizers or additives described above, and any of the oxidizing agents described above. In some embodiments, the self-supporting film further includes an amine-functional (meth)acrylic resin that is a polymerization reaction product of an amine-functional (meth)acryloyl compound (e.g., amine-functional (meth)acrylates and amides) and a non-amine-vinyl monomer. In some embodiments, the amine-functional (meth)acrylic resin has a calculated glass transition temperature (Tg) greater than or equal to 12°C. In some embodiments, the amine-functional (meth)acrylic resin has a calculated Tg greater than or equal to 20°C. In some embodiments, the amine-functional (meth)acryloyl compound (e.g., amine-functional (meth)acrylates and amides) includes 2-(N,N-dimethylaminoethyl) (meth)acrylate, 2-(N,N-diethylaminoethyl) (meth)acrylate, 2-(tert-butylaminoethyl) (meth)acrylate, 2-(N,N-dimethylaminoethyl) (meth)acrylamide, 2-(N,N-diethylaminoethyl) (meth)acrylamide, 2-(tert-butylaminoethyl) (meth)acrylamide, and N-(meth)acryloylpiperidine. In some embodiments, the non-amine-vinyl monomer is selected from (meth)acrylic acid, (meth)acrylates, (meth)acrylamides, vinyl esters, styrene, (meth)acrylonitrile, and mixtures thereof. In some embodiments, the non-amine-vinyl monomer is a (meth)acrylate of a Ci to Ci8alcohol.

[0166] The solid activator composition can be applied in any suitable thickness. In some embodiments, the thickness is at least 1 micrometer, at least 2 micrometers, at least 3 micrometers, at least 4 micrometers, or at least 5 micrometers. In some embodiments, the thickness is no more than 20 micrometers, no more than 15 micrometers, or no more than 10 micrometers. In some embodiments, the solid activator composition is applied in an amount of no more than 3 milligrams per square centimeter. If the layer of solid activator composition is greater than 3 milligrams per square centimeter, as shown in the examples below, the low cohesive strength of the solid activator layer can reduce the bond strength between the tape and the substrate.

[0167] In some embodiments, it is advantageous that the solid activator composition need not include an organic solvent. In some embodiments, the solid activator composition includes less than 5 weight percent, less than 3 weight percent, less than 1 weight percent, less than 0.5 weight percent, less than 0.1 weight percent, or less than 0.01 weight percent of an organic solvent.

[0168] The present disclosure provides a kit comprising: a tape comprising a curable adhesive film comprising: a film-forming polymer; a substance comprising an unsaturated free-radically polymerizable group, which substance can be the film-forming polymer or a substance other than the film-forming polymer; and a transition metal cation; and a solid activator composition comprising an oxidizing agent, wherein the solid activator composition is in the form of a crayon or a paste. The tape, the curable adhesive film, and the solid activator composition can be any of those described above in any of the embodiments thereof.

[0169] In some embodiments, the solid activator composition is in the form of a crayon. The crayon can have any suitable shape, such as a cylinder or a prism having any desired cross-sectional shape, such as a rectangle, a triangle, or a square. The shape of the end of the crayon can be adjusted, for example, for ease of writing, but this is not essential. The kit of the present disclosure can comprise a tape and a crayon. The crayon can be usable with or without a container. In a container, the crayon can also be referred to as a stick. The kit can comprise a tape and a stick. Figure 12 Embodiments of a container that can be used to house a solid activator composition that can be used in the adhesive systems, methods, and crayons of the present disclosure are shown. The cross-section of the container 1 is cylindrical, with a cylindrical sidewall 2. At the bottom of the container is a knurled wheel 3 that forms part of a generally cylindrical push mechanism for the solid activator composition 4. The container also includes a cap 5 that can be snap-fitted to engage over the top end 6 of the container 1. The top end 6 can be of a smaller diameter than the sidewall 2, and has a rim 7 that engages in a corresponding recess on the underside of the cap 5 to secure the cap 5 in place.

[0170] The knurled wheel 3 is attached to an elongated drive or winding shaft 8 that is centrally located within the housing formed by the sidewall of the container. A movable carrier 9 is located on the winding shaft 8. The carrier 9 is generally cylindrical (as seen from its end view - see, for example, Figure 13 ), and has a short, circumferential upstanding wall 10 formed on its base 11. The solid activator composition can be formed with the carrier 9, optional shaft 8, and optional wheel 3 in place. As Figure 13As best shown, the carrier 9 has a central threaded hole 13 in which the threads 16 of the shaft 8 engage. Both the knurled wheel 3 and the shaft 8 are mounted for rotation relative to the container body. When the wheel 3 is turned, it causes the carrier to move up or down the shaft 8, thereby controlling the relative positioning of the mass and the container. In the position shown, the carrier has been moved up the shaft portion to move the solid activator composition 4 to its position protruding from the container. The solid activator composition can then be applied by rubbing the mass against the substrate with manual force. The mass is sheared sufficiently to rub off onto the substrate. To prevent the carrier 9 from rotating with the shaft, elongated ribs 14 are provided on opposite sides of the inner wall of the container. The ribs 14 extend from the base of the container to a position near the mouth of the container. The ribs 14 each engage one of the corresponding grooves 15 in the carrier 9, thereby preventing relative rotation of the container and the carrier and ensuring that the carrier moves up or down when the shaft 8 is turned.

[0171] The adhesive systems and methods of the present disclosure do not require mixing of liquid components; rather, a solid activator composition is applied to a substrate or release liner, and the activator-coated substrate or release liner is brought into contact with a curable adhesive film 140, 210, or 240, and the oxidizing agent migrates from the activator into the curable adhesive film. An oxygen-permeable liner can be held in place on the curable adhesive film until the curable adhesive film is ready to be bonded. When the connection of the substrates to be bonded thereby excludes oxygen, the curable adhesive film begins to cure, thereby creating a structural adhesive bond. In some embodiments of the adhesive systems and methods of the present disclosure, curing can be achieved at normal temperature and pressure without the need for heating and autoclaving. Likewise, in some embodiments of the adhesive systems and methods of the present disclosure, curing can be achieved without ultraviolet radiation treatment and other radiation treatment, and the curing spreads well into areas where radiation curing is difficult to reach. In some embodiments of the adhesive systems and methods of the present disclosure, the curable adhesive film and the solid activator composition do not require refrigeration or storage in the dark.

[0172] Some embodiments of the present disclosure

[0173] In a first embodiment, the present disclosure provides an adhesive system comprising: a curable adhesive film comprising: a film-forming polymer; unsaturated free-radically polymerizable groups capable of bonding to the film-forming polymer or in a species different from the polymer; and a transition metal cation; and a solid activator composition comprising an oxidizing agent, wherein the solid activator composition is not a self-supporting film. In a second embodiment, the present disclosure provides the adhesive system of the first embodiment, wherein the solid activator composition is in the form of a crayon or a paste. In a third embodiment, the present disclosure provides the adhesive system of the first or second embodiment, wherein the solid activator composition is present on a substrate in an amount of no more than 3 milligrams per square centimeter. In a fourth embodiment, the present disclosure provides a kit comprising: a curable adhesive film comprising: a film-forming polymer; unsaturated free-radically polymerizable groups capable of bonding to the film-forming polymer or in a species different from the polymer; and a transition metal cation; and a solid activator composition comprising an oxidizing agent, wherein the solid activator composition is in the form of a crayon or a paste.

[0174] In a fifth embodiment, the present disclosure provides a method for bonding a first article, the method comprising: applying a solid activator composition to a surface of the first substrate, the solid activator composition comprising an oxidizing agent, wherein applying comprises at least one of rubbing or spreading; and contacting the solid activator composition with a first surface of a tape, the tape comprising: a curable adhesive film, the curable adhesive film comprising: a film-forming polymer; unsaturated free-radically polymerizable groups, the unsaturated free-radically polymerizable groups being capable of bonding to the film-forming polymer or in a species different from the polymer; and a transition metal cation. In a sixth embodiment, the present disclosure provides the method according to the fifth embodiment, the method further comprising bonding a second surface of the tape to a second substrate. In a seventh embodiment, the present disclosure provides the method according to the fifth or sixth embodiment, the method further comprising at least one of: rubbing the solid activator composition on a surface of a second substrate or spreading the solid activator composition onto the surface of the second substrate; and contacting the solid activator composition on the second substrate with a second surface of the tape. In an eighth embodiment, the present disclosure provides the method according to the fifth embodiment, the method further comprising bonding a second surface of the tape to an oxygen-permeable liner. In a ninth embodiment, the present disclosure provides the method according to the eighth embodiment, wherein contacting the solid activator composition with a first surface of a tape is performed while the adhesive film is attached to the oxygen-permeable liner. In a tenth embodiment, the present disclosure provides the method according to the eighth or ninth embodiment, the method comprising removing the oxygen-permeable liner from the second surface of the tape; and bonding a second surface of the tape to a second substrate. In an eleventh embodiment, the present disclosure provides the method according to the tenth embodiment, the method further comprising at least one of: rubbing the solid activator composition on a surface of a second substrate or spreading the solid activator composition onto the surface of the second substrate; and contacting the solid activator composition on the second substrate with a second surface of the tape. In a twelfth embodiment, the present disclosure provides the method according to any one of the first through eleventh embodiments, wherein the first substrate is a release liner. In a thirteenth embodiment, the present disclosure provides the method according to the twelfth embodiment, the method comprising removing the release liner to provide a first adhesive surface, and bonding the first adhesive surface to a surface of a substrate. In a fourteenth embodiment, the present disclosure provides the method according to the thirteenth embodiment, the method further comprising applying a solid activator composition to the surface of the substrate, wherein the second solid activator composition comprises a second oxidizing agent, wherein the second solid activator composition is independently selected from the solid activator composition.In a fifteenth implementation, the present disclosure provides the method of any one of the fifth through fourteenth implementations, wherein the solid activator composition is applied to the surface of the first substrate and / or the surface of the second substrate in an amount of no more than 3 milligrams per square centimeter. In a sixteenth implementation, the present disclosure provides the method of any one of the fifth through fifteenth implementations, wherein at least one of rubbing the solid activator composition on or spreading the solid activator composition onto at least one of the surface of the first substrate or the surface of the second substrate comprises at least one of rubbing the solid activator composition on or spreading the solid activator composition onto an intermittent portion of the first substrate or the second substrate without applying the solid activator composition to other portions of the first substrate or the second substrate.

[0175] In a seventeenth implementation, the present disclosure provides the adhesive system, kit, or method of any of the first through sixteenth implementations, wherein the curable adhesive film is a first layer of a multilayer curable adhesive film, wherein the multilayer curable adhesive film further comprises a foam support layer. In an eighteenth implementation, the present disclosure provides the adhesive system, kit, or method of the seventeenth implementation, wherein the foam support layer is curable. In a nineteenth implementation, the present disclosure provides the adhesive system, kit, or method of the seventeenth or eighteenth implementation, wherein the foam support layer comprises at least one of a closed cell foam or a syntactic foam. In a twentieth implementation, the present disclosure provides the adhesive system, kit, or method of any of the seventeenth through nineteenth implementations, wherein the foam support layer comprises the same base polymer as the film-forming polymer in the curable adhesive film. In a twenty-first implementation, the present disclosure provides the adhesive system, kit, or method of any of the seventeenth through twentieth implementations, wherein the foam support layer comprises a crosslinking agent within the foam support layer. In a twenty-second implementation, the present disclosure provides the adhesive system, kit, or method of the twenty-first implementation, wherein the crosslinking agent is different from the material comprising an unsaturated free-radically polymerizable group in the curable adhesive film. In a twenty-third implementation, the present disclosure provides the adhesive system, kit, or method of the twenty-first implementation, wherein the crosslinking agent is the material comprising an unsaturated free-radically polymerizable group in the curable adhesive film that has migrated and / or has migrated (i.e., has migrated) into the curable support layer. In a twenty-fourth implementation, the present disclosure provides the adhesive system, kit, or method of any of the seventeenth through twenty-first or twenty-third implementations, wherein the foam support layer comprises a blowing agent and the same components as the curable adhesive film. In a twenty-fifth implementation, the present disclosure provides the adhesive system, kit, or method of the twenty-fourth implementation, wherein the blowing agent comprises at least one of expandable microspheres, hollow glass bubbles, or gas bubbles, the blowing agent being optionally surfactant stabilized. In a twenty-sixth implementation, the present disclosure provides the adhesive system, kit, or method of any of the seventeenth through twenty-fifth implementations, wherein the curable foam support layer further comprises a polymer modulus modifier. In a twenty-seventh implementation, the present disclosure provides the adhesive system, kit, or method of the twenty-sixth implementation, wherein the polymer modulus modifier comprises a polymer having a Tg of no greater than 100 °C, no greater than 90 °C, no greater than 80 °C, no greater than 70 °C, no greater than 60 °C, no greater than 50 °C, or no greater than 40 °C.In a twenty-eighth embodiment, the present disclosure provides the adhesive system, kit, or method of the twenty-sixth or twenty-seventh embodiment, wherein the polymeric modulus modifier comprises a polyvinyl acetal resin (e.g., polyvinyl butyral). In a twenty-ninth embodiment, the present disclosure provides the adhesive system, kit, or method of the twenty-sixth or twenty-seventh embodiment, wherein the polymeric modulus modifier comprises a high-acid polymer. In a thirtieth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the seventeenth through twenty-ninth embodiments, wherein the curable foam support layer further comprises a transition metal cation and a quaternary ammonium salt. In a thirty-first embodiment, the present disclosure provides the article of any one of the seventeenth through thirtieth embodiments, wherein the curable foam support layer is hot-melt processable. In a thirty-second embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the seventeenth through thirty-first embodiments, wherein the curable adhesive film is carried on a first major surface of the foam support layer. In a thirty-third embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the seventeenth through twenty-first embodiments, wherein the curable adhesive film is directly bonded to (e.g., laminated to) a first major surface of the foam support layer.

[0176] In a thirty-fourth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the seventeenth through thirty-third embodiments, wherein the multilayer curable adhesive film further comprises a second curable adhesive layer comprising: a second film of a second independently selected polymer; a second independently selected unsaturated free-radically polymerizable group capable of bonding with the second independently selected polymer or in a second species different from the second independently selected polymer; and a second independently selected transition metal cation. In a thirty-fifth embodiment, the present disclosure provides the adhesive system, kit, or method of the thirty-fourth embodiment, wherein the second curable adhesive layer is adjacent to a surface of the foam support layer opposite the first layer. In a thirty-sixth embodiment, the present disclosure provides the adhesive system, kit, or method of the thirty-fifth embodiment, wherein the first layer is carried on a first major surface of the foam support layer and the second curable adhesive layer is carried on a second major surface of the foam support layer. In a thirty-seventh embodiment, the present disclosure provides the adhesive system, kit, or method of the thirty-fifth embodiment, wherein the first layer is directly bonded to a first major surface of the foam support layer and the second curable adhesive layer is directly bonded to a second major surface of the foam support layer.

[0177] In a thirty-eighth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through thirty-seventh embodiments, wherein the curable adhesive film comprises a hot-melt processable adhesive. In a thirty-ninth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through thirty-eighth embodiments, wherein the unsaturated free-radically polymerizable group is in a different species than the polymer, and wherein the polymer does not comprise an unsaturated free-radically polymerizable group.

[0178] In a fortieth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the eighth through thirty-ninth embodiments, wherein the oxygen permeable liner comprises at least one of paper or polyolefin. In a forty-first embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the eighth through fortieth embodiments, wherein the oxygen permeable liner comprises ridges on at least one surface. In a forty-second embodiment, the present disclosure provides the adhesive system, kit, or method of the forty-first embodiment, wherein the curable adhesive film comprises an outer surface bearing channels corresponding to the ridges, wherein the channels are capable of aiding air escape during application of the outer surface to a substrate.

[0179] In a forty-second embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-first embodiments, wherein the solid activator composition does not include an unsaturated free-radically polymerizable group. In a forty-third embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-second embodiments, wherein the oxidizing agent is an organic peroxide, an organic hydroperoxide, an inorganic peroxide, or a persulfate salt. In a forty-fourth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-third embodiments, wherein the solid activator composition includes an acrylic polymer including crystalline monomer units having 16 to 50 carbon atoms. In a forty-fifth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-fourth embodiments, wherein the solid activator composition includes at least one of a tackifier or an inorganic filler. In a forty-sixth embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-fourth embodiments, wherein the solid activator composition includes at least one of a fatty acid, a fatty acid salt, or a fatty acid ester. In a forty-seventh embodiment, the present disclosure provides the adhesive system, kit, or method of any one of the first through forty-sixth embodiments, wherein the solid activator composition includes less than 5 wt%, less than 3 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt% of an organic solvent.

[0180] In a forty-eighth implementation, the present disclosure provides a wax pencil comprising: an acrylic polymer comprising crystalline monomer units having from 16 to 50 carbon atoms and at least one other monomer unit; and an oxidizing agent. In a forty-ninth implementation, the present disclosure provides the wax pencil of the forty-eighth implementation, wherein the wax pencil does not comprise an unsaturated free-radically polymerizable group. In a fiftieth implementation, the present disclosure provides the wax pencil of the forty-eighth implementation or the forty-ninth implementation, wherein the oxidizing agent is an organic peroxide, an organic hydroperoxide, an inorganic peroxide, or a persulfate salt. In a fifty-first implementation, the present disclosure provides the wax pencil of any one of the forty-eighth implementation through the fiftieth implementation, further comprising at least one of a tackifier or an inorganic filler. In a fifty-second implementation, the present disclosure provides the wax pencil of any one of the forty-eighth implementation through the fifty-first implementation, further comprising at least one of a fatty acid, a fatty acid salt, or a fatty acid ester. In a fifty-third implementation, the present disclosure provides the adhesive system, kit, or method of any one of the forty-eighth implementation through the fifty-second implementation, wherein the solid activator composition comprises less than 5 wt%, less than 3 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt% of an organic solvent. In a fifty-fourth implementation, the present disclosure provides the adhesive system, kit, or method of any one of the first implementation through the fifty-third implementation, wherein the solid activator composition is in the form of a wax pencil having a shape of a cylinder, a triangular prism, a rectangular prism, or a square prism.

[0181] In a fifty-fifth implementation, the present disclosure provides the adhesive system of any one of the first implementation through the fifty-fourth implementation, further comprising a release liner to which the tape and the solid activator composition are releasably attached. In a fifty-sixth implementation, the present disclosure provides the adhesive system of any one of the first implementation through the fifty-fourth implementation, further comprising a substrate to which the tape and the solid activator composition are attached.

[0182] Examples

[0183] The objects and advantages of the present disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof cited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0184]

[0185] Preparation

[0186] Curable adhesive film 1 Preparation

[0187] Curable adhesive film 1 was prepared as described for hot melt compounding of PSA adhesive tape in U.S. Patent Application Publication No. 2023 / 0088278 (Kugel et al.).

[0188] Curable adhesive film 2- Curable foam support layer - Curable adhesive film 2 Preparation of multilayer tapes

[0189] Curable adhesive film 2 was made by combining a polymer and a liquid blend. The polymer was prepared as described in Synthetic Example S1 of U.S. Patent Publication No. 2013 / 0184394 Al (Satrijo et al.) except the pre-adhesive composition was as follows: 89.480 wt% Ml, 9.942 wt% AA, 0.149 wt% photoinitiator-1, 0.030 wt% CuOAc, 0.398 wt% antioxidant-1, and 0.001 wt% HDDA. The liquid blend was prepared by adding 132.8 pounds (lb) (60.2 kilograms (kg)) of DTMPTA into a HM-2.5 basket (Hockmeyer Equipment Corporation, Elizabeth City, NC, USA) that had been pre-loaded with clean Zirmil 1.5 millimeter (mm) bead media and equipped with a 0.5 mm tungsten coated screen and a 9-spindle hub with a HM-2.5 turbine propeller using a diaphragm pump (Wilden Pump and Engineering, Grand Terrace, CA, USA). When the addition of DTMPTA was complete, 17.2 lb (7.8 kg) of BTEAC was added to the basket using a paddle mixer for incorporation. The mixture was milled at 800 revolutions per minute (rpm) with a cooling jacket set to 70 °F (21 °C) for 3 hours. The mill material was further diluted by adding 254.1 lb (115.3 kg) of DTMPTA per 45.9 lb (20.8 kg) of mill material. This diluted material (liquid blend) was combined with 70.74 wt% of the polymer described above and 0.76 wt% of PB1 at 28.5 wt% and compounded as described for hot melt compounding of PSA adhesive tape in U.S. Patent Application Publication No. 2023 / 0088278 (Kugel et al.) to produce curable adhesive film 2.

[0190] A three layer co-extruded tape was prepared by co-extruding two layers of curable adhesive film 2 onto opposite sides of a curable foam support layer. The curable foam support layer was identical to the curable adhesive film 2 except that it was modified with 2 wt% of a density modifier (balance from the polymer content). The total thickness of the tape from the three layer manifold film die was 12 mils (0.30 mm). The three layer co-extruded tape was cast between a silicone coated casting roll and a silicone coated paper liner entrained by a second cooling roll. The cooling roll was cooled with water at a temperature of about 13 °C. Once cooled, the co-extruded tape exited the silicone coated release roll, thereby adhering to the silicone coated paper liner, which was then wound up in a winding station.

[0191] Polymer blend 1 Preparation

[0192] The ODA macromer was prepared by polymerizing octadecyl acrylate using the method described in the “Method” according to U.S. Patent No. 7,968,661 (Ellis et al.). The resulting polymer had a weight average molecular weight of 69,000 g / mole with a polydispersity index of 1.7 as measured using the test methods described below. Polymer blend 1 was prepared as described in Example 22 of U.S. Patent No. 11,267,997 (June et al.) except that the formulation ratio of ODA / ODMA / IOA / AA / ODA macromer was as follows: 16 / 47 / 22 / 0.5 / 14.5. The polymer was prepared following the method described in the “Method” according to U.S. Patent No. 7,968,661 (Ellis et al.) and the ratio of 18.7 / 54.7 / 26 / 0.6 ODA / ODMA / IOA / AA polymer had a weight average molecular weight of 74,000 g / mole with a polydispersity index of 2.5 as measured using the test methods described below.

[0193] General preparation of solid activator compositions

[0194] The semi-solid activators were prepared by mixing polymer blend 1 and the other materials shown in Table 2 (except for TBEC) in a 15 mL glass vial on a hot plate with occasional stirring at approximately 5 minute intervals. The hot plate temperature to prepare a uniform melt varied from 65 °C (for most of the polymers / additives used) to 90 °C (for mixtures containing rubber). The TBEC addition was completed once a uniform melt was observed and the melt temperature was checked to be below 60 °C. After brief mixing, activators 1-4 were poured into 0.4 cm (inscribed circle radius) x 7.0 cm equilateral triangle plastic molds and activators 5-9 were left in the vials until they cooled to room temperature. The solid activator compositions are shown in Table 2 below.

[0195]

[0196] Test methods

[0197] Dynamic shear adhesion test

[0198] Dynamic lap shear tests were performed at 71℉ (22°C) using an Insight 30EL load testing machine (MTS, EdenPrairie, MN). Test specimens for dynamic shear bonding were prepared on an aluminum substrate (Joseph T. Ryerson & Son, Inc., Coon Rapids, MN) (1 inch × 4 inch × 0.064 inch (2.5 cm × 10 cm × 1.6 mm)) washed with MEK, then with a 50 / 50 water / IPA solution, and then washed three times with acetone, followed by air drying for at least 2 minutes. After preparing the test specimens according to the following examples, the specimens were loaded into the clamps and operated with the crosshead at 0.1 inch (0.25 cm) per minute until failure. The fracture stress was recorded in pounds per square inch (psi) using the test method disclosed in ASTM D1002. Six samples were tested in each embodiment, and the results were averaged and reported.

[0199] Coating weight measurement

[0200] Coating weight measurement is used to measure the thickness of the delivered solid activator composition. The weight of the bare, clean substrate is recorded in milligrams as W0. A 1-inch × 2-inch area is masked using a tape. After applying the activator, the tape is removed, and the weight of the activated substrate is recorded in milligrams as W1. The coating weight is defined as (W1 - W0) / 2, and the unit is mg / inch. 2 Each embodiment tested twelve samples, and the results were averaged and reported.

[0201] Gel permeation chromatography (GPC) analysis GPC ) analysis

[0202] Approximately 50 mg of polymer solids were placed in 10 mL of THF (stabilized with 250 ppm BHT). The sample was mixed on a mechanical shaker (purchased under the trade designation E6010.00 from Eberbach Corporation, Belleville, MI) at low speed for approximately three hours to obtain a polymer solution. All polymer solutions were run through a 0.45 micron syringe filter and analyzed by gel permeation chromatography (“GPC”). The GPC consisted of a pump, a chromatographic column, and a detector. The chromatographic column and detector are described below. The pump was purchased under the trade designation “AGILENT 1100 HPLC” from Agilent Technologies, Santa Clara, CA.

[0203] GPC equipment and conditions: Sample: 50 L at 5 mg / mL injection, stabilized with tetrahydrofuran Samples were filtered through a 0.45 micron membrane Mobile phase: Stabilized tetrahydrofuran-UV grade (purchased under the trade designation “EMD OMNISOLV” from MilliporeSigma Co., Burlington, MA); or equivalent grade Flow rate: 1.0 mL / min Detector: Refractive index detector (purchased under the trade designation “1200 SERIES G1362” from Agilent Technologies, Santa Clara, CA) Chromatographic column: Two chromatographic columns with a nominal MW range of 500 daltons to 10 7 thousand daltons (purchased under the trade designation “PLGEL 10 MICRON MIXED-B” from Agilent Technologies, Santa Clara, CA) and one chromatographic column with a nominal MW range of 200 daltons to 400,000 daltons (purchased under the trade designation “PLGEL 5 MICRON MIXED-D” from Agilent Technologies). All chromatographic columns were 7.8 mm x 300 mm. The chromatographic columns were maintained at 40 °C.

[0204] Standard: Polystyrene, narrow dispersity; range 6.035 x 10 6to 580 Mp; (third order polynomial fit) available from Agilent, Santa Clara, CA under the trade designation "EASICAL PS-1"

[0205] Syringe filter type: 0.45 micron PTFE

[0206] Examples (Ex.) 1 to 11 and Illustrative Examples (I.E.) 1 and 2

[0207] Two different activation methods were used to activate aluminum substrates for dynamic shear adhesion testing. Examples 1-3 and Comparative Example 1 were activated by holding the activator like a crayon and simply writing / rubbing across the top of a single clean substrate (1 inch x 2 inch coated). Examples 4-11 and Comparative Example 2 were activated by the following process. A small amount of activator (about 10 mg) was applied and then spread evenly across the clean substrate (1 inch x 1.5 inch area) using a Kimwipe. The average coating weight by this method was 2 mg / inch 2 to 7 mg / inch 2 After the substrate activation was complete, adhesion coupons were prepared by cutting 1 inch (2.5 cm) wide strips of the previously described curable adhesive films 1 and 2. One release liner was removed and the curable adhesive film was laid on the activated portion of the substrate. A 2 inch (5.1 cm) hard rubber roller (MARSHALLTOWN, Marshalltown, IA) was rolled onto the construction by firm hand pressure to ensure complete contact of the curable adhesive film and the activated substrate. The uncured coupon was then stored at room temperature (71 °F / 22 °C) for the time shown in Table 2 (uncured storage time) before the bond was closed with a second substrate. The bond was formed by removing the top release liner to expose the curable adhesive film and introducing it to a second activated substrate (activated using the same method as the first substrate). The closed bond was then subjected to an applied pressure of about 18 psi for 5 seconds in a pneumatically driven hydraulic press (Fred S. Carver, Inc. Hydraulic Equipment, Menomonee Falls, WI) or a 15 pound force was rolled onto the overlapped bond area at a speed of 12 in / min. The bonded article was allowed to dwell at room temperature (71 °F / 22 °C) as indicated in Table 3 before testing using the dynamic shear adhesion test. The adhesive systems and results are shown in Table 3 below.

[0208]

[0209] The foregoing description of the present disclosure should not be construed to limit the scope of the present disclosure as claimed, the scope of the present disclosure being limited only by the claims and their all equivalents.

Claims

1. An adhesive system comprising: a tape comprising: a curable adhesive film comprising: a film of a polymer; unsaturated free-radically polymerizable groups capable of bonding to the polymer or in a species other than the polymer; and a transition metal cation; and a solid activator composition comprising an oxidizing agent, wherein the solid activator composition is not a self-supporting film.

2. A kit comprising: a tape comprising: a curable adhesive film comprising: a film of a polymer; unsaturated free-radically polymerizable groups capable of bonding to the polymer or in a species other than the polymer; and a transition metal cation; and a solid activator composition comprising an oxidizing agent, wherein the solid activator composition is in the form of a crayon or a paste.

3. A method of bonding a first substrate, the method comprising: applying a solid activator composition to a surface of the first substrate, the solid activator composition comprising an oxidizing agent, wherein applying comprises at least one of rubbing or spreading; and contacting the solid activator composition with a first surface of a tape comprising: a curable adhesive film comprising: a film of a polymer; unsaturated free-radically polymerizable groups capable of bonding to the polymer or in a species other than the polymer; and a transition metal cation.

4. The method of claim 3, wherein the solid activator composition is applied to the surface of the first substrate in an amount of no more than 3 milligrams per square centimeter.

5. The method of claim 3 or 4, further comprising bonding a second surface of the tape to a second substrate.

6. The method of claim 3 or 4, further comprising covering the second surface of the tape with an oxygen-permeable liner.

7. The adhesive system, kit, or method of any one of claims 1 to 6, wherein the solid activator composition does not comprise unsaturated free-radically polymerizable groups.

8. The adhesive system, kit, or method of any one of claims 1 to 7, wherein the solid activator composition comprises an acrylic polymer comprising crystalline monomeric units having 16 to 50 carbon atoms.

9. The adhesive system, kit, or method of any one of claims 1 to 8, wherein the solid activator composition comprises at least one of a tackifier, an inorganic filler, a fatty acid, a fatty acid salt, or a fatty acid ester.

10. The adhesive system, kit, or method of any one of claims 1 to 9, wherein the tape further comprises a support layer adjacent to the curable adhesive film.

11. The adhesive system, kit, or method of claim 10, wherein the support layer comprises a foam. ​ 12. The adhesive system, kit, or method of claim 11, wherein the foam comprises a crosslinker comprising an unsaturated free-radically polymerizable group.

13. The adhesive system, kit, or method of any one of claims 10 to 12, wherein the curable adhesive film is a first curable adhesive film, wherein the tape further comprises a second curable adhesive film, wherein the second curable adhesive film comprises, independently of the first curable adhesive film: a film of a polymer; an unsaturated free-radically polymerizable group, which is capable of bonding to the polymer or in a substance different from the polymer; and a transition metal cation; and wherein the second curable adhesive film is adjacent to a surface of the support layer opposite the first curable adhesive film.

14. The adhesive system, kit, or method of any one of claims 1 to 13, wherein the curable adhesive film comprises a hot-melt processable adhesive.

15. A wax pencil comprising: an acrylic polymer comprising crystalline monomer units having from 16 to 50 carbon atoms and at least one other monomer unit; and an oxidizing agent.

Images