Adhesive films, adhesive systems, and related processes

Abstract

The adhesive film comprises a first (meth)acrylate copolymer, the first (meth)acrylate copolymer containing at least 55 weight percent (wt%) of linear or branched alkyl (meth)acrylate monomer units, 15-40 wt% of (meth)acrylic acid monomer units, and 0.1-5 wt% of a crosslinking monomer having two or more (meth)acrylate groups. When the first (meth)acrylate copolymer contains 15 wt% of (meth)acrylic acid monomer units, the first (meth)acrylate copolymer contains at least 5 wt% of a high T g The adhesive film comprises up to 5 wt. % of a further (meth)acrylate copolymer, the further (meth)acrylate copolymer comprising 0.1-15 wt. % of (meth)acrylic acid monomer units. The adhesive film can be a multi-layer adhesive assembly comprising a first layer of the first (meth)acrylate copolymer and a second adhesive layer adjacent to the first layer. Processes for the manufacture and a system comprising the adhesive film and the primer are also described.

Description

[Background technology]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Patent Application No. 63 / 290205, filed December 16, 2021, the disclosure of which is incorporated by reference in its entirety herein.

[0002] [Background technology] Adhesives are used for a variety of marking, holding, protecting, sealing, and shielding purposes. Adhesive tapes generally include a backing or substrate and an adhesive. One type of adhesive that is useful for many applications is a pressure-sensitive adhesive. It is well known to those skilled in the art that pressure-sensitive adhesives (PSAs) have certain properties, including: (1) strong and persistent tackiness, (2) adhesion with finger pressure or less, (3) sufficient ability to hold an adherend, and (4) sufficient cohesive strength.

[0003] Materials that have been found to perform well as pressure sensitive adhesives are polymers designed and formulated to exhibit the necessary viscoelastic properties to provide the desired balance of tack, peel adhesion, and shear strength. The polymers most commonly used in the preparation of pressure sensitive adhesives are various (meth)acrylate-based copolymers, natural rubber, synthetic rubber, and silicones.

[0004] Pressure-sensitive adhesive compositions comprising a combination of a first (meth)acrylate copolymer and a second (meth)acrylate copolymer have been reported in U.S. Patent Application Publication No. 2021 / 0102099 (Unverhau et al.) to exhibit high adhesive peel and shear strengths on various types of substrates. Multi-layer pressure-sensitive adhesive assemblies comprising a first pressure-sensitive adhesive layer laminated onto a second pressure-sensitive adhesive layer have been reported in U.S. Patent No. 9,845,414 (Wieneke et al.) to exhibit high adhesive peel and shear strengths on various types of substrates. Summary of the Invention

[0005] After application to a substrate surface, pressure sensitive adhesives (PSAs) typically flow to wet the surface and create adhesion. The Dahlquist criterion is commonly used to describe such behavior of PSAs. The Dahlquist criterion for PSAs suggests that the shear storage modulus G' should not exceed 0.3 megapascals (MPa) at 25°C with an applied oscillatory strain of 1 Hertz (Hz) within the linear viscoelastic region of the PSA. If the Dahlquist criterion is exceeded, the PSA will usually lose its tackiness and adhesion build-up will no longer occur properly. Thus, the Dahlquist criterion represents an upper limit on the storage modulus for PSA properties. However, such a storage modulus restriction will likewise limit the overall cohesive strength of the PSA, which generally does not exceed an overlap shear strength of 1 MPa.

[0006] The present disclosure provides an adhesive film that exceeds the Dahlquist rating criteria, but which when combined with a primer provides excellent wet adhesion to a substrate. The adhesive film in combination with a primer can provide overlap shear strength values ​​of 2.5 MPa to 3.5 MPa, as shown in the examples below. Thus, the adhesive film of the present disclosure has excellent cohesive strength and can provide overlap shear adhesion values ​​much higher than typical PSAs. The adhesive film of the present disclosure functions as a PSA in the presence of a primer according to the properties (1) to (4) above. Advantageously, due to its ability to function as a PSA, no heat or radiation and reactive chemicals are required in the primer or adhesive film to provide beneficial adhesive properties.

[0007] According to one embodiment, the present disclosure relates to an adhesive film comprising a first (meth)acrylate copolymer, the first (meth)acrylate copolymer containing at least 55% by weight, based on the weight of the (meth)acrylate copolymer, of linear or branched alkyl (meth)acrylate monomer units, 15% to 40% by weight, based on the weight of the (meth)acrylate copolymer, of (meth)acrylic acid monomer units, and 0.1% to 5% by weight, based on the weight of the (meth)acrylate copolymer, of a crosslinking monomer unit having two or more (meth)acrylate groups. When the first (meth)acrylate copolymer contains 15% by weight of (meth)acrylic acid monomer units, the first (meth)acrylate copolymer contains at least 5% by weight, based on the weight of the first (meth)acrylate copolymer, of a high T α- ... g The adhesive film comprises up to 5 weight percent of an additional (meth)acrylate copolymer, the additional (meth)acrylate copolymer having from 0.1 weight percent to 15 weight percent of (meth)acrylic acid monomer units, based on the weight of the additional (meth)acrylate copolymer.

[0008] The adhesive film of the present disclosure may be in the form of a foam and / or may form part of a multi-layer adhesive assembly, the adhesive film being in the form of a first adhesive layer, which may be a foam layer, and the multi-layer adhesive assembly further comprising a second adhesive layer adjacent to the first adhesive layer.

[0009] According to another embodiment, the adhesive film is a multi-layer adhesive assembly including a first layer of a first (meth)acrylate copolymer and a second adhesive layer adjacent to the first layer.

[0010] In some embodiments, the adhesive film further comprises a second (meth)acrylate copolymer, the second (meth)acrylate copolymer having more than 15% to 40% by weight of (meth)acrylic acid monomer units based on the weight of the second (meth)acrylate copolymer. In another aspect, the present disclosure provides a process for producing such an adhesive film. The process comprises incorporating the second (meth)acrylate copolymer into a curable precursor composition comprising a linear or branched alkyl (meth)acrylate monomer, a (meth)acrylic acid monomer, a crosslinking monomer, and a polymerization initiator, and polymerizing the linear or branched alkyl (meth)acrylate monomer, the (meth)acrylic acid monomer, and the crosslinking monomer to form a first (meth)acrylate copolymer in the presence of the second (meth)acrylate copolymer.

[0011] In yet another aspect, the present disclosure provides an adhesive system comprising a primer composition and an adhesive film as described above, wherein the adhesive film does not react with the primer composition to form a covalent bond.

[0012] In the context of this disclosure, the expression "low surface energy substrate" is meant to refer to a substrate having a surface energy of less than 34 dynes per centimeter. Among such materials are polypropylene (PP), polyethylene (e.g., high density polyethylene (HDPE)), and blends of polypropylene (e.g., PP / ethylene propylene diene monomer (EPDM), thermoplastic olefin (TPO)).

[0013] In the context of the present disclosure, the expression "medium surface energy substrate" is meant to refer to a substrate having a surface energy comprised between 34 and 70 dynes per centimeter, typically between 34 and 60 dynes per centimeter, more typically between 34 and 50 dynes per centimeter. Among such materials are polyamides (PA), such as polyamide 6 (PA6), acrylonitrile butadiene styrene (ABS), polycarbonate (PC) / ABS blends, PC, polyvinyl chloride (PVC), PUR, thermoplastic elastomers (TPE), polyoxymethylene (POM), polystyrene, poly(methyl methacrylate) (PMMA), clearcoat surfaces, in particular clearcoats for vehicles such as automobiles or coating surfaces for industrial applications, and composite materials such as fiber-reinforced plastics.

[0014] In the context of the present disclosure, the expression "high surface energy substrate" is meant to refer to substrates having a surface energy of more than 350 dynes per centimeter, typically more than 400 dynes per centimeter, more typically between 400 and 1100 dynes per centimeter. Among such materials are metal substrates (e.g., aluminum, stainless steel), and glass.

[0015] Surface energy is typically determined from contact angle measurements, such as those described in ASTM D7490-08.

[0016] The term superimposed, when used throughout this specification, means that two or more layers of polymeric liquid precursors or polymer layers of the multi-layer adhesive assembly are arranged one on top of the other. The superimposed liquid precursor layers or polymer layers may be arranged directly adjacent to each other, with the upper surface of the lower layer abutting the lower surface of the upper layer.

[0017] As used throughout this specification, the term adjacent refers to two superimposed layers in a precursor multi-layer adhesive assembly or a cured multi-layer adhesive assembly that are positioned directly adjacent to one another, i.e., abutting one another.

[0018] The terms "glass transition temperature" and "Tg" are used interchangeably and refer to the glass transition temperature of a (co)polymeric material or blend. Unless otherwise indicated, glass transition temperature values ​​are measured by dynamic mechanical analysis (DMA).

[0019] Exemplary "wet-in-wet" manufacturing processes for use herein are described in detail, for example, in WO 2011094385(A1) (Hitschmann et al.) or EP 0259094(A1) (Zimmerman et al.), the entire disclosures of which are incorporated herein by reference.

[0020] The term "acrylic" refers to both acrylic and methacrylic polymers, oligomers and monomers.

[0021] The term "(meth)acrylate" with respect to a monomer, oligomer, or polymer means a vinyl-functional alkyl ester formed as the reaction product of an alcohol with acrylic or methacrylic acid. "(Meth)acrylate" includes, individually and collectively, methacrylates and acrylates.

[0022] The term "polymer" refers to a molecule having a structure that actually or conceptually includes multiple repeats of units derived from one or more monomers. The term "monomer" refers to a molecule of low relative molecular weight that can be combined with others to form a polymer. The term "polymer" includes homopolymers and copolymers, as well as homopolymers or copolymers that can be formed in miscible blends, for example, by coextrusion or reaction. The term "polymer" includes random, block, graft, and star polymers. The term "copolymer" encompasses oligomers.

[0023] A "monomer unit" of a polymer or oligomer is a segment of the polymer or oligomer that is derived from a single monomer.

[0024] The term "crosslinked" generally refers to polymer chains linked together by covalent chemical bonds through crosslinking molecules or groups to form a network polymer. Crosslinked polymers are generally characterized as insoluble, but may be swellable in the presence of an appropriate solvent. The term "crosslinked" includes partially crosslinked.

[0025] The term "alkyl" refers to a monovalent group that is a saturated hydrocarbon. An alkyl can be straight chain, branched chain, cyclic, or a combination thereof and typically has 1 to 32 carbon atoms. In some embodiments, an alkyl group contains 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, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, 2-ethylhexyl, 2-octyl, and 2-propylheptyl.

[0026] As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly indicates otherwise.

[0027] As used herein, the terms "have," "having," "include," "including," "comprise," and "comprising" are used in an open-ended sense and generally mean "including, but not limited to." It is understood that the terms "consisting of" and "consisting essentially of" are encompassed by the term "comprising."

[0028] In this application, terms such as "a," "an," and "the" are not intended to refer to only a singular entity, but include general classes, specific examples of which may be used for illustration. The terms "a," "an," and "the" are used interchangeably with the term "at least one." The phrases "at least one of" and "comprises at least one of," followed by a list, refer to any one of the items in the list, and any combination of two or more items in the list. All numerical ranges include their endpoints and non-integer values ​​between the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5), unless otherwise stated.

[0029] The above summary of the present disclosure is not intended to describe each disclosed embodiment or all implementations of the present disclosure. The following description more particularly illustrates exemplary embodiments. Therefore, it should be understood that the following description is merely for illustrative purposes and should not be read to unduly limit the scope of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the adhesive film of the present disclosure, the first (meth)acrylate copolymer comprises at least 55 wt% of linear or branched alkyl (meth)acrylate monomer units based on the weight of the first (meth)acrylate copolymer. In some embodiments, the first (meth)acrylate copolymer comprises at least 60 weight percent (wt%), 65 wt%, or 70 wt% of linear or branched alkyl (meth)acrylate monomer units based on the weight of the first (meth)acrylate copolymer. In some embodiments, the first (meth)acrylate copolymer comprises less than 85 wt%, or up to 84 wt%, 83 wt%, 82 wt%, 81 wt%, or 80 wt% of linear or branched alkyl (meth)acrylate monomer units based on the weight of the first (meth)acrylate copolymer. In some embodiments, when present, the second (meth)acrylate copolymer comprises at least 55%, 60%, 65%, or 70% by weight of linear or branched alkyl (meth)acrylate monomer units based on the weight of the second (meth)acrylate copolymer. In some embodiments, the second (meth)acrylate copolymer comprises less than 85% by weight, or up to 84%, 83%, 82%, 81%, or 80% by weight of linear or branched alkyl (meth)acrylate monomer units based on the weight of the first (meth)acrylate copolymer. In some embodiments, the linear or branched alkyl (meth)acrylate monomer units are selected from the group consisting of C1-C 32 (Meth)acrylic acid ester monomer units, C1-C 24 (Meth)acrylic acid ester monomer unit, or C1-C 18 It is a (meth)acrylic acid ester monomer unit.

[0031] Examples of suitable alkyl (meth)acrylates include those represented by Formula I: CH2=C(R')COOR (I) [In the formula, R' is hydrogen or a methyl group, and R is an alkyl group having 1 to 30, 4 to 30, 6 to 30, 8 to 30, 6 to 24, 6 to 20, 6 to 18, 8 to 24, 8 to 20, or 8 to 20 carbon atoms, which may be linear or branched]. Examples of suitable monomers represented by formula I include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, iso Included are decyl acrylate, undecyl (meth)acrylate, n-dodecyl acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, 2-propylheptyl (meth)acrylate, stearyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, octadecyl (meth)acrylate, and behenyl (meth)acrylate. Suitable monomer units further include mixtures of at least two or at least three structural isomers of secondary alkyl (meth)acrylates of formula II: [ka] [In the formula, R 1 and R 2 are each independently C1 to C 30 R is a saturated linear alkyl group. 1 and R 2 The total number of carbon atoms in R is 7 to 31. 3 is H or CH3. 1 and R2 The total number of carbon atoms in may, in some embodiments, 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. Pat. No. 9,102,774 (Clapper et al.).

[0032] In some embodiments, the first (meth)acrylate copolymer and / or the optional second (meth)acrylate copolymer comprises at least one of 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, isooctyl (meth)acrylate, In some embodiments, the first (meth)acrylate copolymer and / or the second (meth)acrylate copolymer comprises 2-ethylhexyl (meth)acrylate.

[0033] In the adhesive film of the present disclosure, the first (meth)acrylate copolymer comprises 15% to 40% by weight of (meth)acrylic acid monomer units. In some embodiments, the first (meth)acrylate copolymer comprises at least 15% by weight, greater than 15% by weight, at least 16% by weight, or at least 17% by weight based on the weight of the first (meth)acrylate copolymer. In some embodiments, the second (meth)acrylate copolymer in the adhesive film, if present, comprises greater than 15% to 40% by weight of (meth)acrylic acid monomer units. In some embodiments, the second (meth)acrylate copolymer comprises at least 15% by weight, at least 16% by weight, or at least 17% by weight based on the weight of the second (meth)acrylate copolymer. In some embodiments, the first (meth)acrylate copolymer in the adhesive film comprises 15.5-40 wt%, 16-40 wt%, 16-35 wt%, 16-30 wt%, 16-25 wt%, 17-25 wt%, 17-23 wt%, or 17-20 wt% (meth)acrylic acid monomer units based on the weight of the first (meth)acrylate copolymer. In some embodiments, the optional second (meth)acrylate copolymer in the adhesive film comprises 15.5-40 wt%, 16-40 wt%, 16-35 wt%, 16-30 wt%, 16-25 wt%, 17-25 wt%, 17-23 wt%, or 17-20 wt% (meth)acrylic acid monomer units based on the weight of the second (meth)acrylate copolymer. Examples of (meth)acrylic acid monomer units include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, ethacrylic acid, crotonic acid, citraconic acid, cinnamic acid, β-carboxyethyl acrylate, and 2-methacrylolyloxyethyl succinate. In some embodiments, the (meth)acrylic acid monomer units are acrylic acid monomer units or methacrylic acid monomer units. The (meth)acrylic acid monomer units include salts of these acids, such as alkali metal salts and ammonium salts.

[0034] In some embodiments, the first (meth)acrylate copolymer, when polymerized, has a glass transition temperature (T g ) homopolymers with high T g " monomer (i.e., a homopolymer formed from the monomer has a T of at least 50°C, 60°C, or 70°C) g In embodiments where the first (meth)acrylate copolymer has 15 wt. % (meth)acrylic acid monomer units based on the weight of the first (meth)acrylate copolymer, the first (meth)acrylate copolymer has at least 5 wt. % (in some embodiments, at least 7.5 wt. %, 10 wt. %, 12.5 wt. %, or 15 wt. %) of "high T g " monomer units. g are measured by differential scanning calorimetry and many are reported in the polymer properties database found at polymerdatabase.com. Some suitable high T g Monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl (meth)acrylate, cyclohexyl methacrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, phenyl acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl (meth)acrylate, tert-butylcyclohexyl methacrylate, 2-phenoxyethyl methacrylate, N-octyl (meth)acrylamide, tetrahydrofurfiiryl methacrylate, and mixtures thereof. Other suitable high T gThe monomers have a single vinyl group that is not a (meth)acryloyl group, such as various vinyl ethers (e.g., vinyl methyl ether), vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrenes (e.g., a-methylstyrene), vinyl halides, and mixtures thereof. In some embodiments, the optional second (meth)acrylate copolymer is a high T copolymer including any of the above. g The monomer may further comprise monomer units of the monomer of formula (I) in any of the weight percentages given above.

[0035] In the adhesive film of the present disclosure, the first (meth)acrylate copolymer comprises 0.05% to 5% by weight of a crosslinking monomer unit having two or more (meth)acrylate groups, based on the weight of the (meth)acrylate copolymer. Suitable crosslinking monomers include diacrylate esters of diols, such as ethylene glycol diacrylate, diethylene glycol diacrylate, propanediol diacrylate, butanediol diacrylate, butane-1,3-diyl diacrylate, pentanediol diacrylate, hexanediol diacrylate (including 1,6-hexanediol diacrylate), heptanediol diacrylate, octanediol diacrylate, nonanediol diacrylate, decanediol diacrylate, and dimethacrylates of any of the aforementioned diacrylates. Further suitable multifunctional monomers include polyacrylate esters of polyols, such as glycerol triacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, neopentyl glycol diacrylate, dipentaerythritol pentaacrylate, methacrylates of the aforementioned acrylates, and combinations thereof. Further suitable multifunctional crosslinking monomers include divinylbenzene, allyl methacrylate, diallyl maleate, diallyl phthalate, and combinations thereof. Further suitable multifunctional crosslinking monomers include multifunctional acrylate oligomers containing two or more acrylate groups. The multifunctional acrylate oligomers may be urethane acrylate oligomers, epoxy acrylate oligomers, polyester acrylates, polyether acrylates, polyacrylic acrylates, methacrylates of any of the aforementioned acrylates, or combinations thereof. Any combination of these crosslinking monomers may be useful. In some embodiments, up to 4%, 3%, 2%, or 1% by weight of the monomer units in the first (meth)acrylate copolymer are derived from crosslinking monomers.In some embodiments, at least 0.1% by weight of the monomer units in the first (meth)acrylate copolymer are derived from crosslinking monomers. The second (meth)acrylate copolymer, if present, may be free of crosslinking monomer units.

[0036] For acrylic polymers, nuclear magnetic resonance spectroscopy ( 1 H or 13 The polymer can be analyzed by C NMR (C NMR) to identify the monomer units in the polymer. Solid-state or solution NMR can be useful depending on the level of crosslinking in the polymer. For solid-state NMR, the acrylic polymer can be swollen in an appropriate solvent for analysis.

[0037] In some embodiments, the first (meth)acrylate copolymer and the second (meth)acrylate copolymer, if present, each independently have a T in the range 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. g In some embodiments, the first (meth)acrylate copolymer and the second (meth)acrylate copolymer, if present, each independently have a T of 100° C. or less, 80° C. or less, 60° C. or less, 50° C. or less, 45° C. or less, or even 40° C. or less. g has.

[0038] In some embodiments, the adhesive film has a thickness of at least 0.3 millimeters. In some embodiments, the adhesive film has a thickness in the range of 300 micrometers to 6000 micrometers, 300 micrometers to 4000 micrometers, 300 micrometers to 2000 micrometers, 500 micrometers to 2000 micrometers, 800 micrometers to 1500 micrometers, or 600 micrometers to 1300 micrometers.

[0039] In some embodiments, the adhesive film of the present disclosure has a shear storage modulus of at least 0.5 megapascals (MPa) or more than 0.5 MPa, measured by a rheometer at 25 ° C. with an oscillatory strain of 1 Hertz (Hz) in the linear viscoelastic region of the adhesive film. In some embodiments, the adhesive film of the present disclosure has a storage modulus of at least 1 MPa or 1.5 MPa. In some embodiments, the adhesive film of the present disclosure has a storage modulus of up to 4 MPa, 3.5 MPa, 3 MPa, 2.5 MPa, or 2 MPa. The storage modulus of the bulk adhesive film can be conveniently measured as described in the examples below. In embodiments where the adhesive film is a multilayer film, the storage modulus can be determined by atomic force microscope (AFM)-based nanoindentation at frequencies (0.1 Hz to 100 Hz) and temperatures in theologically relevant regimes, as described in more detail below.

[0040] The adhesive film of the present disclosure comprises 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1 wt% or less of an additional (meth)acrylate copolymer having 0.1 wt% to 15 wt% (in some embodiments, 0.1 wt% to 12 wt%, 0.1 wt% to 11 wt%, 0.1 wt% to 10 wt%, 0.2 wt% to 10 wt%, 0.2 wt% to 9 wt%, 0.2 wt% to 8 wt%, 0.3 wt% to 8 wt%, 0.5 wt% to 8 wt%, 0.5 wt% to 6 wt%, 1 wt% to 6 wt%, or even 1 wt% to 5 wt%) of (meth)acrylic acid monomer units based on the weight of the additional (meth)acrylate copolymer. Such additional (meth)acrylate copolymer in the adhesive film of the present disclosure contributes to the T of the adhesive film. gand / or storage modulus, and also tends to reduce the cohesive strength of the adhesive film. In some embodiments, the adhesive film of the present disclosure does not include an additional (meth)acrylate copolymer, provided that the additional (meth)acrylate copolymer has 0.1 wt.% to 15 wt.% (in some embodiments, 0.1 wt.% to 12 wt.%, 0.1 wt.% to 11 wt.%, 0.1 wt.% to 10 wt.%, 0.2 wt.% to 10 wt.%, 0.2 wt.% to 9 wt.%, 0.2 wt.% to 8 wt.%, 0.3 wt.% to 8 wt.%, 0.5 wt.% to 8 wt.%, 0.5 wt.% to 6 wt.%, 1 wt.% to 6 wt.%, or even 1 wt.% to 5 wt.%) (meth)acrylic acid monomer units based on the weight of the additional (meth)acrylate copolymer.

[0041] The first (meth)acrylate copolymer for use herein may be prepared by any conventional free radical polymerization method, including solution, radiation, bulk, dispersion, emulsion, solventless, and suspension processes. The resulting copolymer may be a random or block copolymer. In some embodiments, the first (meth)acrylate copolymer is prepared as either a solution or syrup copolymer composition.

[0042] A typical solution polymerization process is carried out by adding the monomers, a suitable solvent, and optional chain transfer agent to a reaction vessel, adding a free radical initiator, purging with nitrogen, and maintaining the reaction vessel at an elevated temperature, typically in the range of about 40° C. to 100° C., until the reaction is complete, typically for about 1 hour to 24 hours, depending on the batch size and temperature. Examples of solvents are methanol, tetrahydrofuran, ethanol, isopropanol, tert-butanol, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, toluene, xylene, and ethylene glycol alkyl ethers. These solvents can be used alone or as mixtures thereof.

[0043] The syrup polymer technique involves partially polymerizing monomers to produce a syrup polymer comprising a first (meth)acrylate copolymer and unpolymerized monomers. The syrup polymer composition can be polymerized to a useful coating viscosity, coated onto a substrate (such as a tape backing), and further polymerized.

[0044] In some embodiments, the polymerization is carried out in the absence of a solvent that is non-reactive with the functional groups of the components of the syrup polymer, such as ethyl acetate, toluene, or tetrahydrofuran.

[0045] In some embodiments, the coatable syrup polymer is prepared by photoinitiated free radical polymerization. Polymerization to achieve a coatable viscosity can be carried out to achieve a maximum of about 10% conversion of monomer to polymer. Polymerization can be terminated when the desired conversion and viscosity is achieved by removing the light source and bubbling air (oxygen) through the solution to stop the propagation of free radicals. Polymerization can be achieved by exposing the syrup polymer composition to energy in the presence of a photoinitiator. An energy-activated initiator may not be necessary, for example, when ionizing radiation is used to initiate polymerization.

[0046] In some embodiments, the free radical photoinitiator is a Type I (cleavage type) photoinitiator. Cleavage type photoinitiators include acetophenone, alpha-aminoalkylphenone, benzoin ether, benzoyl oxime, acyl (e.g., benzoyl) phosphine oxide, acyl (e.g., benzoyl) phosphinate, and mixtures thereof. Examples of useful benzoin ethers include benzoin methyl ether and benzoin butyl ether.

[0047] Examples of suitable acetophenone compounds include 4-diethylaminoacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2 dimethylamino-4'-morpholinobutyrophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxyacetophenone, and 2,2-dimethoxy-1,2-diphenylethan-1-one. Examples of suitable acylphosphine oxide, acylphosphinate, and acylphosphonate compounds include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethylphenyl(2,4,6-trimethylbenzoyl)phosphineate, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, dimethylpivaloylphosphonate, and poly(oxy-1,2-ethanediyl), α,α',α"-1,2,3-propanediyl. and triyltris[co-[[phenyl(2,4,6-trimethylbenzoyl)phosphinyl]oxy]. Further suitable photoinitiators include substituted a-ketols such as 2-methyl-2-hydroxypropiophenone, aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, and photoactive oximes such as 1-phenyl-1,2-propanedione-2-(O-ethoxy-carbonyl)oxime. Many photoinitiators are available, for example, under the trade name "IRGACURE" from BASF, Vandalia, III., and under the trade names "OMNIRAD" and "ESACURE" from IGM Resins, Waalwijk, Netherlands. Any two or more of these photoinitiators may be used together in any combination. Additional photoinitiators can be added to the mixture to be coated after the copolymer is formed (i.e., the photoinitiator can be added to the syrup polymer mixture).

[0048] The degree of conversion (of monomers to copolymer) can be monitored by measuring the refractive index of the polymerizing mixture during irradiation.

[0049] In some embodiments of the adhesive film of the present disclosure, the adhesive film comprises 65% to 99%, 70% to 95%, 75% to 95%, 75% to 90%, or even 75% to 85% by weight of the first (meth)acrylate copolymer, the weight percentages being based on the total weight of the adhesive film. In some embodiments, the adhesive film of the present disclosure comprises 1% to 35%, 1% to 30%, 2% to 25%, 3% to 25%, 3% to 20%, 4% to 20%, or even 4% to 15% by weight of the second (meth)acrylate copolymer, the weight percentages being based on the total weight of the adhesive film.

[0050] The second (meth)acrylate copolymers for use herein may be prepared by any conventional free radical polymerization method, including solution, radiation, bulk, dispersion, emulsion, and suspension processes. The resulting adhesive copolymers may be random or block copolymers.

[0051] The second (meth)acrylate copolymer for use herein can be polymerized by conventional techniques including, but not limited to, solvent polymerization, dispersion polymerization, and solventless bulk polymerization. The monomer mixture can include a type and amount of polymerization initiator effective to polymerize the comonomer, especially a thermal initiator or a photoinitiator.

[0052] A typical solution polymerization process is carried out by adding the monomers, a suitable solvent, and optional chain transfer agent to a reaction vessel, adding a free radical initiator, purging with nitrogen, and maintaining the reaction vessel at an elevated temperature, typically in the range of about 40° C. to 100° C., until the reaction is complete, typically for about 1 hour to 20 hours, depending on the batch size and temperature. Examples of solvents are methanol, tetrahydrofuran, ethanol, isopropanol, tert-butanol, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, toluene, xylene, and ethylene glycol alkyl ethers. These solvents can be used alone or as mixtures thereof.

[0053] The second (meth)acrylate copolymer can be formed by photopolymerization using any of the methods and photoinitiators described above.

[0054] In a typical thermal polymerization process, the monomer mixture may be subjected to thermal energy in the presence of a thermal polymerization initiator (i.e., a thermal initiator). An example of a suitable thermal initiator is available from DuPont under the trade name "VAZO".

[0055] Solvent-free polymerization methods, such as the continuous free radical polymerization methods described in U.S. Pat. Nos. 4,619,979 and 4,843,134 (Kotnour et al.); the essentially adiabatic polymerization method using a batch reactor described in U.S. Pat. No. 5,637,646 (Ellis); and the method described for polymerizing a packaged pre-adhesive composition described in U.S. Pat. No. 5,804,610 (Hamer et al.), may also be utilized to prepare the second (meth)acrylate copolymer.

[0056] In some embodiments, the second (meth)acrylate copolymer for use in the adhesive film of the present disclosure is prepared using essentially solvent-free free radical polymerization, particularly essentially solvent-free thermal free radical polymerization.In some embodiments, the second (meth)acrylate copolymer for use herein is prepared by essentially adiabatic polymerization.The degree of conversion (of monomer to copolymer) can be monitored during polymerization by measuring the refractive index of the polymerizing mixture.

[0057] In some embodiments, the second (meth)acrylate copolymer for use in the adhesive film of the present disclosure is obtained as a prepolymer composition having a polymer conversion of greater than 10%, greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, greater than 40%, or greater than 45%, and in some embodiments, from 10% to 60%, from 20% to 55%, from 30% to 50%, or even from 35% to 50%.

[0058] If desired, a chain transfer agent may be added to the monomer mixture of either the first or second (meth)acrylate copolymer to control the molecular weight of the copolymer. Examples of useful chain transfer agents include carbon tetrabromide, alcohols, mercaptans, and mixtures thereof. In some embodiments, the chain transfer agent comprises at least one of isooctylthioglycolate or carbon tetrabromide.

[0059] The adhesive film may contain, as an optional component, a tackifying resin, in particular a hydrogenated hydrocarbon tackifier. Examples of hydrogenated hydrocarbon tackifiers include C9 and C5 hydrogenated hydrocarbon tackifiers. Examples of C9 hydrogenated hydrocarbon tackifiers include those sold by Eastman Chemical Co., Middelburg, Netherlands under the trade names "REGALITE S-5100", "REGALITE R-7100", "REGALITE R-9100", "REGALITE R-1125", "REGALITE S-7125", "REGALITE S-1100", "REGALITE R-1090", "REGALREZ 6108", "REGALREZ 1085", "REGALREZ 1094", "REGALREZ 1126", "REGALREZ 1139", and "REGALREZ 3103"; Examples include those sold under the names "PICCOTAC" and "EASTOTAC" by Eastman Chemical Co.; "ARKON P-140", "ARKON P-125", "ARKON P-115", "ARKON P-100", "ARKON P-90", "ARKON M-135", "ARKON M-115", "ARKON M-100", and "ARKON M-90" by Arakawa Chemical Inc., Chicago, IL; and "ESCOREZ 5000 Series" sold by Exxon Mobil Corp., Irving, TX. In some embodiments, the tackifier is a partially hydrogenated C9 hydrogenated tackifier, a fully hydrogenated C9 hydrogenated tackifier, or a combination thereof.

[0060] In some embodiments, adhesive films according to the present disclosure are substantially free of tackifying resins, and in particular free of hydrocarbon tackifying resins.

[0061] If desired, other additives can be added to the adhesive film of the present disclosure.For example, they can include leveling agents, UV absorbers, hindered amine light stabilizers (HALS), oxygen inhibitors, wetting agents, rheology control agents, defoamers, biocides, flame retardants, and dyes.All of these additives and their uses are known to those skilled in the art, and can be used as long as they do not adversely affect adhesive properties.

[0062] In some advantageous aspects, the adhesive film of the present disclosure comprises a filler material, in particular a particulate filler material. In some embodiments, the optional filler material for use herein is selected from the group of polymeric microspheres, glass bubbles, and any combination thereof.

[0063] In some embodiments, the adhesive film of the composition of the present disclosure comprises 65% to 98% by weight, 70% to 95% by weight, 75% to 95% by weight, 75% to 90% by weight, or 75% to 85% by weight of a first (meth)acrylate copolymer; 0% to 35% by weight, 1% to 35% by weight, 1% to 30% by weight, 2% to 25% by weight, 3% to 25% by weight, 3% to 20% by weight, 4% to 20% by weight, or 4% to 15% by weight of a second (meth)acrylate copolymer; and optionally, 2% to 15%, 2% to 14%, or 2% to 12% by weight of a filler material comprising at least one of polymeric microspheres and glass bubbles, the weight percentages being based on the total weight of the adhesive film.

[0064] The adhesive films of the present disclosure can be prepared by simply blending the first and second (meth)acrylate copolymer components, optionally with optional ingredients such as filler materials and tackifying resins. The copolymers can be blended using a number of conventional methods, such as, for example, melt blending, solvent blending, or any suitable physical means.

[0065] Physical blending equipment that provides dispersive mixing, distributive mixing, or a combination of dispersive and distributive mixing is useful in preparing homogeneous blends. Of the physical blends, both batch and continuous methods can be used. Examples of batch methods include BRAB ENDER (using BRAB ENDER PREP CENTER available from CW Brabender Instruments, Inc.; South Hackensack, NJ) or BANBURY internal mixing and roll milling (using equipment available from FARREL COMPANY, Ansonia, CT). Examples of continuous methods include single screw extrusion, twin screw extrusion, disk extrusion, reciprocating single screw extrusion, and pin barrel single screw extrusion. Continuous processes can include utilizing both cavity moving elements (e.g., CTM available from RAPRA Technology, Ltd., Shrewsbury, England) and distributive elements such as pin mixing elements, static mixing elements, and dispersion elements (e.g., MADDOCK mixing elements or SAXTON mixing elements as described in "Mixing in Single-Screw Extruders", Mixing in Polymer Processing, edited by Chris Rauwendaal (Marcel Dekker Inc., New York (1991), pp. 129, 176-177 and 185-186)).

[0066] According to aspects of the present disclosure, the adhesive film can be prepared by incorporating the second (meth)acrylate copolymer into a curable precursor composition of the first (meth)acrylate copolymer, which comprises a linear or branched alkyl (meth)acrylate monomer, a (meth)acrylic acid monomer, a crosslinking monomer, optionally a polymerization initiator, and optionally a particulate filler material, thereby forming a curable precursor composition of the adhesive film. The first (meth)acrylate copolymer is then formed in situ in a second step by polymerizing the linear or branched alkyl (meth)acrylate monomer, the (meth)acrylic acid monomer, and the crosslinking monomer to form the first (meth)acrylate copolymer in the presence of the second (meth)acrylate copolymer. In some embodiments, the second (meth)acrylate copolymer is diluted into the curable precursor composition of the first (meth)acrylate copolymer and mixed by shaking. In some embodiments, the polymerization of the linear or branched alkyl (meth)acrylate monomer, the (meth)acrylic acid monomer, and the crosslinking monomer to form the first (meth)acrylate copolymer in the presence of the second (meth)acrylate copolymer is carried out using actinic radiation. In some embodiments of the process for producing a film adhesive of the present disclosure, the second (meth)acrylate copolymer is obtained by free radical polymerization, particularly by an essentially solvent-free polymerization method, more particularly by an essentially adiabatic polymerization reaction. In some embodiments, the second (meth)acrylate copolymer is obtained as a prepolymer composition with a polymer conversion of more than 10%, more than 15%, more than 20%, more than 25%, more than 30%, more than 35%, more than 40%, more than 45%, or in the range of 10% to 60%, 20% to 55%, 30% to 50%, or 35% to 50%.

[0067] In some embodiments, the adhesive film of the present disclosure is in the form of a foam. The foam contains voids, which may be open or closed cell. In some embodiments, the voids are present in the foam in an amount of at least 5% by volume, 10% to 55% by volume, 10% to 45% by volume, 15% to 45% by volume, or 20% to 45% by volume. Adhesive films in the form of a foam typically have a viscosity of 0.45 g / cm. 3 ~1.5g / cm 3 , 0.45g / cm 3 ~1.10g / cm 3 , 0.50g / cm 3 ~0.95g / cm 3 , 0.60g / cm 3 ~0.95g / cm 3 , or 0.70 g / cm 3 ~0.95g / cm 3 It has a density in the range of

[0068] In some embodiments, the adhesive film in the form of a foam has a thickness in the range of 100 micrometers to 6000 micrometers, 200 micrometers to 4000 micrometers, 500 micrometers to 2000 micrometers, or 800 micrometers to 1500 micrometers. In some embodiments, the adhesive film in the form of a foam has a thickness of at least 300 micrometers. As will be apparent to one skilled in the art in light of this description, the thickness of the foamed adhesive film will vary depending on the intended application.

[0069] The voids or bubbles in the foam can be created by any of the known methods described in the art, including the use of gas or blowing agents and / or the inclusion of hollow particles in the composition for the foam. For example, according to one method for making foam described in U.S. Pat. No. 4,415,615 (Esmay et al.), an acrylic foam can be obtained by frothing a composition containing an acrylate monomer and an optional comonomer, coating the foam onto a backing, and polymerizing the frothed composition. An unfoamed composition of an acrylate monomer and an optional comonomer can also be coated onto a backing, and then the composition is foamed and polymerized simultaneously. Frothing the composition may be accomplished by bubbling a gas into the polymerizable composition, optionally in the presence of a surfactant (e.g., a hydrocarbon or fluorochemical surfactant) or surface-modified nanoparticles to stabilize the foam. Inert gases such as nitrogen, argon, and carbon dioxide can be useful, especially when the polymerization is photoinitiated.

[0070] In some embodiments, the adhesive film in the form of a foam incorporates hollow fillers such as hollow polymer particles, hollow glass microspheres, and hollow ceramic microspheres. Hollow polymer microspheres include elastomeric particles, such as those available under the trade name "EXPANCEL" from Akzo Nobel, Amsterdam, The Netherlands. Examples of hollow ceramic microspheres include alumina / silica microspheres having a particle size in the range of 5 microns to 300 microns and a specific gravity of 0.7 ("FILLITE", Pluess-Stauffer International), aluminum silicate microspheres having a specific gravity of about 0.45 to about 0.7 ("Z-LIGHT"), calcium carbonate coated polyvinylidene copolymer microspheres having a specific gravity of 0.13 ("DUALITE 6001AE", Pierce & Stevens Corp.), and hollow ceramic microspheres sold by 3M Company, Saint Paul, Minnesota under the trade name "3M GLASS". "3M GLASS BUBBLES" include Glass Bubbles available in grades K1, K15, K20, K25, K37, K46, S15, S22, S32, S35, S38, S38HS, S38XHS, S42HS, S42XHS, S60, S60HS, iM30K, iM16K, XLD3000, XLD6000 and G-65, as well as any of the HGS series of "3M GLASS BUBBLES". Foams containing hollow microspheres are called syntactic foams. The foam adhesive may also include a hydrocarbon elastomer as described in U.S. Pat. No. 5,024,880 (Vesley et al.).

[0071] According to another aspect, the present disclosure is directed to a multi-layer adhesive assembly comprising an adhesive film as described above, the adhesive film as described above being in the form of a first adhesive film layer, and in some embodiments in the form of a first adhesive foam layer, the multi-layer adhesive assembly further comprising a second adhesive layer adjacent to the first adhesive film layer.

[0072] This type of multi-layer adhesive assembly, and in particular dual layer or skin-core-skin foam tape assemblies, is advantageous compared to single layer adhesives in that the adhesion (instant adhesion) can be tailored by the formulation of the second adhesive layer (also commonly referred to as the skin layer), while other properties / requirements of the overall assembly such as application issues, deformation issues, and energy distribution can be addressed by appropriate formulation of the first adhesive film layer (also commonly referred to as the core layer).

[0073] In some embodiments, the multi-layer adhesive assemblies described herein are in the form of a skin / core multi-layer adhesive assembly, where the first layer is an adhesive film of the present disclosure, in some embodiments in the form of a foam, which is the core layer of the multi-layer adhesive assembly, and the second adhesive layer is the skin layer of the multi-layer adhesive assembly.

[0074] In some embodiments, the multi-layer adhesive assembly described herein is in the form of a multi-layer adhesive assembly further comprising a third adhesive layer, thereby forming, for example, a three-layer multi-layer adhesive assembly. In some embodiments, the third adhesive layer is adjacent to the first adhesive layer on a side of the first adhesive layer that is opposite the side of the first adhesive layer that is adjacent to the second adhesive layer. In some embodiments, the first, second, and third adhesive layers are superimposed.

[0075] In some embodiments, the multi-layer adhesive assembly is in the form of a skin / core / skin multi-layer adhesive assembly, where the first adhesive layer is an adhesive film layer of the present disclosure in the form of a foam and is also the core layer of the multi-layer adhesive assembly, the second adhesive layer is the first skin layer of the multi-layer adhesive assembly, and the third adhesive layer is the second skin layer of the multi-layer adhesive assembly.

[0076] The second adhesive layer and / or the third adhesive layer may have any composition commonly known in the art. Thus, the compositions of these various layers for use in the multi-layer adhesive assemblies of the present disclosure are not particularly limited.

[0077] In some embodiments, the second adhesive layer and / or the third adhesive layer comprises a polymer matrix independently selected from the group consisting of polyacrylates, polyurethanes, polyolefins, polyamines, polyamides, polyesters, polyethers, polyisobutylenes, polystyrenes, polyvinyls, polyvinylpyrrolidones, natural rubbers, synthetic rubbers, and any combinations, copolymers, or mixtures thereof. In some embodiments, the second adhesive layer and / or the third adhesive layer comprises a polymer matrix independently selected from the group consisting of polyacrylates, polyurethanes, and any combinations, copolymers, or mixtures thereof. In some embodiments, the second adhesive layer and / or the third adhesive layer comprises a polymer matrix independently selected from the group consisting of polyacrylates, and any combinations, copolymers, or mixtures thereof.

[0078] In some embodiments, the second adhesive layer and the third adhesive layer independently comprise a polyacrylate polymer matrix whose major monomeric component comprises a linear or branched alkyl (meth)acrylate ester, and in some embodiments, a non-polar linear or branched alkyl (meth)acrylate ester having a linear or branched alkyl group containing from 1 to 32, 1 to 20, or even 1 to 15 carbon atoms.

[0079] In some embodiments, the second adhesive layer and the third adhesive layer independently comprise a polymeric substrate and a major monomer component thereof is selected from the group consisting of polyacrylates comprising linear or branched alkyl (meth)acrylate esters, the linear or branched alkyl (meth)acrylate esters being selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, iso-pentyl (meth)acrylate, n-hexyl (meth)acrylate, iso-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl ... ) acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, 2-propylheptyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, nonyl (meth)acrylate, isofloryl (meth)acrylate, and any combination or mixture thereof. In some embodiments, the linear or branched alkyl (meth)acrylate ester comprises at least one of isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, butyl acrylate, or 2-octyl (meth)acrylate, and in some embodiments at least one of isooctyl acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or 2-propylheptyl (meth)acrylate.

[0080] In some embodiments of the multi-layer adhesive assembly of the present disclosure, the second adhesive layer and / or the third adhesive layer have the same or similar (co)polymer composition as described above for the adhesive film of the present disclosure.

[0081] In some embodiments of the multi-layer adhesive assembly of the present disclosure, the second adhesive layer and / or the third adhesive layer comprises a polyacrylate matrix further comprising a polar monomer unit. In some embodiments, the polar comonomer comprises at least one of acrylic acid, methacrylic acid, itaconic acid, hydroxyalkyl acrylates, nitrogen-containing acrylate monomers, particularly acrylamides and substituted acrylamides, acrylamines and substituted acrylamines, and any combination or mixture thereof.

[0082] In some embodiments of the multi-layer adhesive assembly of the present disclosure, the second adhesive layer and / or the third adhesive layer are g In some embodiments, the high T g The monomer units include at least one of isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, isofloryl (meth)acrylate, cyclohexyl (meth)acrylate, and in some embodiments, isobornyl (meth)acrylate.

[0083] According to some embodiments of the multi-layer adhesive assembly of the present disclosure, the second adhesive layer and / or the third adhesive layer further comprises a tackifier resin, in particular a hydrocarbon tackifier resin. The tackifier resin can be any of those described above. Advantageously, the tackifier resin is selected from the group consisting of C5-based hydrocarbon resins, C9-based hydrocarbon resins, C5 / C9-based hydrocarbon resins, and any combination or mixture thereof or hydrogenated versions.

[0084] In some embodiments of the multi-layer adhesive assembly of the present disclosure, the polymerizable material used to manufacture the second adhesive layer and / or the third adhesive layer comprises 50% to 99.5% by weight, or 60% to 95% by weight, of a linear or branched alkyl (meth)acrylate ester as a first / main monomer, the main monomer being preferably selected from the group consisting of isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, butyl acrylate, and optionally 1.0% to 50% by weight, 3.0% to 50 .... % to 40 wt%, 5.0 wt% to 35 wt%, or 10 wt% to 30 wt% of a second monomer having an ethylenically unsaturated group, which in some embodiments is a high Tg monomer, and optionally 0.1 wt% to 15 wt%, 0.5 wt% to 15 wt%, 1.0 wt% to 10 wt%, 2.0 wt% to 8.0 wt%, 2.5 wt% to 6.0 wt%, or 3.0 wt% to 6.0 wt% of a polar monomer, such as a polar (meth)acrylate, and optionally a tackifying resin, the weight percentages being based on the total weight of the polymerizable material used to make the second adhesive layer and / or the third adhesive layer.

[0085] According to an advantageous aspect of the multi-layer adhesive assembly of the present disclosure, the second adhesive layer and / or the third adhesive layer comprises a polymer matrix further comprising a chlorinated polyolefin (co)polymer. The incorporation of a chlorinated polyolefin (co)polymer into the curable precursor of the second adhesive layer and / or the third adhesive layer can improve the stability of the resulting adhesive layer upon thermal bond aging and thermal / humidity bond aging, especially on low surface energy (LSE) substrates.

[0086] Examples of chlorinated polyolefin (co)polymers suitable for use herein include those sold under the trade names: "CPO 343-1" sold by Eastman Chemical Co.; "13-LP", "15-LP", "16-LP" and "17-LP" sold by Toyo Kasei Kogyo Co.; "HYPALON CP 827B", "HYPALON CP 163" and "HYPALON CP 183" sold by DuPont Co.; and "TYRIN CPE 421 IP", "TYRIN CPE 6323A" and "TYRIN CPE 3615P" sold by Dow Chemical Co. Suitable chlorinated polyolefins include chlorinated polypropylene, chlorinated polyethylene, chlorinated ethylene / vinyl acetate copolymers, and any combination, mixture or copolymer thereof. In some embodiments, the chlorinated polyolefin (co)polymer is chlorinated polypropylene.

[0087] In some embodiments, the multi-layer adhesive assembly described above in any of its embodiments is obtained by a wet-on-wet coating process step. Exemplary "wet-in-wet" manufacturing processes for use herein are described, for example, in WO2011094385(A1) (Hitschmann et al.) or EP0259094(A1) (Zimmerman et al.). In some embodiments, the method for manufacturing the multi-layer adhesive assembly comprises a wet-on-wet coating process step.

[0088] According to another aspect, the present disclosure is a process for manufacturing a multi-layer adhesive assembly as described above in any of its embodiments, the process comprising superimposing a (liquid) precursor of a first adhesive polymer layer, a (liquid) precursor of a second adhesive layer, and optionally a (liquid) precursor of a third adhesive layer, thereby forming a curable precursor of the multi-layer adhesive assembly, and curing the curable precursor of the multi-layer adhesive assembly, in some embodiments by curing with actinic radiation.

[0089] In some embodiments of the process for manufacturing a multi-layer adhesive assembly, a (bottom) layer of curable (liquid) precursor of the second adhesive layer is covered by an adjacent (top) layer of curable liquid precursor of the first adhesive layer, respectively, essentially without exposing the (bottom) layer of curable (liquid) precursor of the second adhesive layer.

[0090] In some embodiments of the process for producing a multi-layer adhesive assembly, the process is a continuous and self-metering process for producing a multi-layer adhesive assembly. In some of these embodiments, the process comprises: providing two or more coating knives independently offset from one another from the substrate to form a gap perpendicular to a surface of the substrate; moving the substrate in a downstream direction relative to the coating knife; Providing a curable (liquid) precursor of the first adhesive layer, a curable (liquid) precursor of the second adhesive layer, and optionally a curable (liquid) precursor of the third adhesive layer upstream of the coating knife, thereby coating the two or more curable liquid precursors through their respective gaps as superimposed layers on the substrate. It is well within the capabilities of those skilled in the art to carry out a continuous and self-metering method for producing a multi-layer adhesive assembly as described above, in light of this disclosure together with the disclosure of WO2011094385(A1) (Hitschmann et al.). In particular, suitable settings and configurations of coating equipment, coating knives and coating stations for use in this particular embodiment of the method for producing a multi-layer adhesive assembly will be readily identified by those skilled in the art in light of this disclosure together with the disclosure of WO2011094385(A1) (Hitschmann et al.).

[0091] In some embodiments of the process for producing a multi-layer adhesive assembly, the first adhesive polymer layer, the second adhesive layer, and optionally the third adhesive layer are prepared separately and then laminated together. In other embodiments of the process for producing a multi-layer adhesive assembly, the process includes a (co)extrusion step. In other embodiments of the process for producing a multi-layer adhesive assembly, the process is as described in U.S. Pat. No. 4,818,610 (Zimmerman et al.). The adhesive tape of U.S. Pat. No. 4,818,610 (Zimmerman et al.) is prepared by sequentially coating liquid compositions, each of which includes at least one photopolymerizable monomer, onto a substrate. A liner can be attached to the top layer, and the multiple superimposed layers are cured by subjecting it to radiation to provide an adhesive tape.

[0092] The adhesive film can be conveniently coated on or between liners that may be treated with a release coating. Any suitable material for the liner and release coating can be used. In some embodiments, the adhesive film can be coated on a liner with different release properties on each surface, and can be optionally wound into a roll.

[0093] The adhesive films (in some embodiments, foams) and multilayer assemblies of the present disclosure can be applied to a variety of substrates. The substrates can be flexible or non-flexible and can be made of polymeric materials, glass or ceramic materials, metals, or combinations thereof. Suitable polymeric substrates include polymeric films such as those prepared from polypropylene, polyethylene, polyvinyl chloride, polyester (polyethylene terephthalate or polyethylene naphthalate), polycarbonate, polymethyl (meth)acrylate (PMMA), cellulose acetate, cellulose triacetate, and ethyl cellulose. Foam substrates may also be used. Examples of other substrates include metals such as stainless steel, polymeric materials coated with metals or metal oxides, and glass coated with metals or metal oxides.

[0094] As described above, in the presence of a primer, the adhesive film of the present disclosure functions as a PSA. The present disclosure provides an adhesive system comprising a primer composition and an adhesive film as described above in any of its embodiments. The adhesive film generally adheres to a primed substrate surface when applied without the use of heat or radiation. The adhesive film generally adheres to a primed substrate surface without forming a covalent bond. For example, the adhesive film generally does not react with the primer composition to form a covalent bond. The adhesive system may be useful, for example, for bonding substrates. A method of bonding substrates may include applying a primer composition to a substrate and then applying an adhesive film to the substrate. The primer composition may be left on the substrate for at least 5 minutes, 10 minutes, 15 minutes, 30 minutes, or 60 minutes before the adhesive film is applied.

[0095] In some embodiments of the adhesive system and related methods, the primer composition comprises at least one of a polyamide, a polyurethane, or a polyacrylate. Polyurethane primers can undergo moisture curing after they are applied to the substrate, but do not necessarily react with the adhesive film when it is applied to the primer. Other primer compositions are not reactive when applied and are not reactive with the adhesive film. Suitable polyamide primers include those available from 3M Company under the trade designation "3M PRIMER 4297". Suitable polyurethane primers include those available from 3M Company under the trade designation "3M PRIMER P591", from Henkel under the trade designations "TEROSON 8519" and "TEROSON 8517", and from Sika under the trade designation "SIKA 210". Suitable polyacrylate primers include those available from 3M under the trade designation "3M PRIMER 9348" and from Tesa under the trade designation "TESA 60153". In some embodiments, the surface DMT modulus is at least 0.5 GPa, 0.75 GPa, 0.8 GPa, 1 GPa, or at least 1.5 GPa, as determined by AFM using the techniques described above.

[0096] The adhesive films and multi-layer adhesive assemblies of the present disclosure may be used in any conventionally known article, such as labels, tapes, signs, covers, marking indicia, display components, and touch panels.

[0097] The adhesive film and multi-layer adhesive assembly of the present disclosure can be coated / applied on a substrate using any conventional coating technique, appropriately modified for a particular substrate.For example, the adhesive film can be applied / coated on various solid substrates by methods such as roller coating, flow coating, dip coating, spin coating, spray coating, knife coating, and die coating.These various coating methods allow the adhesive composition and the assembly to be placed on the substrate with different thicknesses, thereby allowing the assembly to be used in a wider range of applications.

[0098] The adhesive films and multi-layer adhesive assemblies according to the present disclosure can be useful for forming strong adhesive bonds to low surface energy (LSE) substrates. Among such materials are polypropylene, polyethylene (e.g. high density polyethylene or HDPE), blends of polypropylene (e.g. PP / EPDM, TPO), or even some clearcoat surfaces. Other substrates may also have low surface energy properties due to residues such as oily residues or films such as paints on the surface of the substrate.

[0099] The adhesive films and multilayer adhesive assemblies of the present disclosure may also be useful for bonding to medium surface energy (MSE) substrates such as, for example, polyamide 6 (PA6), acrylonitrile butadiene styrene (ABS), polycarbonate (PC) / ABS blends, PC, PVC, polyurethane (PUR), thermoplastic elastomers (TPE), polyoxymethylene (POM) polystyrene, poly(methyl methacrylate) (PMMA), some clearcoat surfaces, especially clearcoats of vehicles such as automobiles or coated surfaces for industrial applications, and composite materials such as fiber reinforced plastics.

[0100] The adhesive films and multi-layer adhesive assemblies of the present disclosure can also be useful for bonding high surface energy (HSE) substrates such as, for example, ceramic, glass, and metal.

[0101] Thus, the present disclosure is further directed to the use of the adhesive compositions and assemblies as described above for bonding to low surface energy substrates, medium surface energy substrates, and / or high surface energy substrates.

[0102] In some embodiments, the adhesive films and multilayer adhesive assemblies of the present disclosure have static shear strength values ​​greater than 2000 minutes, greater than 4000 minutes, greater than 6000 minutes, greater than 8000 minutes, or even greater than 10000 minutes, measured at 110 ° C. according to the static shear test method described in the experimental section.

[0103] The substrate to which the adhesive film and multi-layer adhesive assembly of the present disclosure can be applied is selected according to the specific application.For example, the multi-layer adhesive assembly can be applied to sheet products (e.g., decorative graphics and reflective products), label stock, and tape backings, especially by its second and / or third adhesive layer.In addition, the adhesive film and multi-layer adhesive assembly of the present disclosure can be applied directly onto other substrates, such as metal panels (e.g., automobile panels) or glass windows, so that further substrates or objects can be attached to the panel or window.

[0104] Thus, the adhesive films and multi-layer adhesive assemblies of the present disclosure may find particular use in the automotive manufacturing industry (eg, for attaching exterior trim or weather stripping), the construction industry, or the solar panel construction industry.

[0105] Thus, the present disclosure is further directed to the use of the above adhesive films and assemblies for industrial applications, particularly construction applications, automotive applications (including, for example, specialized vehicles such as trucks, trains, and buses), appliances, cladding, and displays.

[0106] As mentioned above, the adhesive film generally adheres to the primed substrate surface when applied without the use of heat or radiation. The adhesive film generally adheres to the primed substrate surface without forming a covalent bond. Advantageously, no crosslinking agents or reactive chemicals are required in the adhesive film to build up adhesive strength. Thus, the adhesive film generally does not include thermal crosslinking additives such as multifunctional aziridines, isocyanates, or epoxies, or chemical crosslinking agents such as peroxides. Also, the adhesive film generally does not include photochemical crosslinking additives that are activated after application to the substrate. In some embodiments, the adhesive film of the present disclosure does not include multifunctional aziridines, multifunctional isocyanates, multifunctional epoxides, benzophenones, triazines, multifunctional carboxylates, oxetanes, or oxazolines.

[0107] As shown in the examples below, the adhesive system of the present disclosure can provide an overlap shear adhesive strength on aluminum of at least 2 MPa or at least 2.5 MPa. In contrast, the comparative adhesive film includes, for example, an additional (meth)acrylate copolymer as the main component of the adhesive film, and the additional (meth)acrylate copolymer is present in an amount of 0.1% to 15% by weight (in some embodiments, 0.1 to 11% by weight, 0.1 to 10% by weight, 0.2 to 10% by weight, 0.3 to 10% by weight, 0.4 to 10% by weight, 0.5 to 10% by weight, 0.6 to 10% by weight, 0.7 to 10% by weight, 0.8 to 10% by weight, 0.9 ... When the composition has 0.2-9 wt%, 0.2-8 wt%, 0.3-8 wt%, 0.5-8 wt%, 0.5-6 wt%, 1-6 wt%, or even 1-5 wt% (meth)acrylic acid monomer units, the overlap shear adhesive strength on aluminum is generally 1.5 MPa or less.

[0108] Item 1 is an adhesive film comprising a first (meth)acrylate copolymer, the first (meth)acrylate copolymer is at least 55% by weight, based on the weight of the first (meth)acrylate copolymer, of linear or branched alkyl (meth)acrylate monomer units; 15% to 40% by weight of (meth)acrylic acid monomer units based on the weight of the first (meth)acrylate copolymer, where when the first (meth)acrylate copolymer contains 15% by weight of (meth)acrylic acid monomer units, at least 5% by weight based on the weight of the first (meth)acrylate copolymer of high T 1 -1 -1 -2 -1 -2 -1 -1 -2 -1 -1 -2 -1 -1 -2 -1 -2 g (Meth)acrylic acid monomer units, including monomer units of the monomer and 0.1% to 5% by weight, based on the weight of the first (meth)acrylate copolymer, of monomer units of a crosslinking monomer having two or more (meth)acrylate groups; The adhesive film comprises 5% by weight or less of an additional (meth)acrylate copolymer, the additional (meth)acrylate copolymer comprising 0.1% by weight to 15% by weight of (meth)acrylic acid monomer units, based on the weight of the additional (meth)acrylate copolymer.

[0109] Item 2 is the adhesive film according to item 1, wherein the first (meth)acrylate copolymer contains (meth)acrylic acid monomer units in an amount greater than 15 weight percent (wt%), at least 15.5 wt%, at least 16 wt%, or at least 17 wt%, based on the weight of the first (meth)acrylate copolymer.

[0110] Item 3 is the adhesive film according to item 1 or 2, in which the first (meth)acrylate copolymer contains 15.5% by weight to 40% by weight, 16% by weight to 40% by weight, from 16% by weight to 35% by weight, from 16% by weight to 30% by weight, from 16% by weight to 25% by weight, from 17% by weight to 25% by weight, from 17% by weight to 23% by weight, or from 17% by weight to 20% by weight of (meth)acrylic acid monomer units, based on the weight of the first (meth)acrylate copolymer.

[0111] Item 4 is a high T polymer that provides a homopolymer having a glass transition temperature of at least 50° C. when homopolymerized.g 4. The adhesive film according to item 2 or 3, further comprising a monomer unit of a monomer.

[0112] Item 5 is the adhesive film according to any one of items 1 to 4, in which the adhesive film has a storage modulus of at least 0.5 megapascals or greater than 0.5 megapascals as measured with a rheometer at 25° C. and 1 hertz.

[0113] Item 6 is a method for producing a first (meth)acrylate copolymer having a T in the range 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. g 6. The adhesive film according to any one of items 1 to 5,

[0114] Item 7 is the adhesive film according to any one of items 1 to 6, having a thickness of at least 0.3 millimeters, and optionally up to 6 millimeters, 4 millimeters, or 2 millimeters.

[0115] Item 8 is a linear or branched alkyl (meth)acrylate monomer unit, linear or branched C1-C 32 (Meth)acrylate monomer units, C1-C 24 (Meth)acrylate monomer units, or C1-C 18 8. The adhesive film according to any one of items 1 to 7, which contains a (meth)acrylate monomer unit.

[0116] Item 9 is the adhesive film according to any one of items 1 to 8, wherein the linear or branched alkyl (meth)acrylate monomer unit includes at least one of 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, or isooctyl (meth)acrylate.

[0117] Item 10 is the adhesive film according to any one of items 1 to 9, in which the adhesive film is a foam.

[0118] Item 11 is the adhesive film according to item 10, comprising at least one of polymer expandable microspheres or glass bubbles in an amount of 2% by weight to 30% by weight based on the total weight of the adhesive film.

[0119] Item 12 is the adhesive film according to any one of items 1 to 11, further comprising a second (meth)acrylate copolymer, the second (meth)acrylate copolymer comprising more than 15% by weight to 40% by weight of (meth)acrylic acid monomer units based on the weight of the second (meth)acrylate copolymer.

[0120] Item 13 is the adhesive film according to item 12, comprising 65% by weight to 99% by weight, 70% by weight to 95% by weight, 75% by weight to 95% by weight, 75% by weight to 90% by weight, or 75% by weight to 85% by weight of the first (meth)acrylate copolymer, and 1% by weight to 35% by weight, 1% by weight to 30% by weight, 2% by weight to 25% by weight, 3% by weight to 25% by weight, 3% by weight to 20% by weight, 4% by weight to 20% by weight, or 4% by weight to 15% by weight of the second (meth)acrylate copolymer, based on the total weight of the adhesive film.

[0121] Item 14 is a method for producing a methacrylic acid copolymer comprising the steps of: at least one of the first (meth)acrylate copolymer or the second (meth)acrylate copolymer, comprising 15.5% by weight to 40% by weight, 16% by weight to 40% by weight, 16% by weight to 35% by weight, 16% by weight to 30% by weight, 16% by weight to 25% by weight, 17% by weight to 25% by weight, 17% by weight to 23% by weight, or 17% by weight to 20% by weight of (meth)acrylic acid monomer units based on the weight of the first or second (meth)acrylate copolymer; and 60% by weight to 84.5% by weight, 65% by weight to 84% by weight, or 77% by weight to 83% by weight of linear or branched C1-C 32 (Meth)acrylate monomer units, C1-C 24 (Meth)acrylate monomer units, or C1-C 18 and (meth)acrylate monomer units.

[0122] Item 15 is 65% to 99%, 70% to 95%, 75% to 95%, 75% to 90%, or even 75% to 85% by weight of a first (meth)acrylate copolymer, based on the total weight of the adhesive film; 1% to 35%, 1% to 30%, 2% to 25%, 3% to 25%, 3% to 20%, 4% to 20%, or 4% to 15% by weight of a second (meth)acrylate copolymer; 15. The adhesive film according to any one of items 12 to 14, optionally comprising 2% to 30% by weight, 2% to 20% by weight, or 2% to 15% by weight of a filler material comprising at least one of expandable microspheres or glass bubbles.

[0123] Item 16 is the adhesive film according to any one of items 1 to 15, which is substantially free of a tackifying resin, in particular free of a hydrocarbon tackifying resin.

[0124] Item 17 is the adhesive film according to any one of items 1 to 16, wherein the adhesive film is a multilayer adhesive assembly including a first layer including a first (meth)acrylate copolymer and a second adhesive layer adjacent to the first layer.

[0125] Item 18 is the adhesive film according to item 17, in the form of a skin / core multi-layer adhesive assembly, the first layer comprising the first (meth)acrylate copolymer being the core layer of the multi-layer adhesive assembly, and the second adhesive layer being the skin layer of the multi-layer adhesive assembly.

[0126] Item 19 is the adhesive film according to item 17 or 18 in the form of a multi-layer adhesive assembly, further comprising a third adhesive layer adjacent to the first adhesive layer on a side of the first adhesive layer opposite to the side of the first adhesive layer adjacent to the second adhesive layer.

[0127] Item 20 is the adhesive film according to item 19, in the form of a skin / core / skin multi-layer adhesive assembly, the first adhesive layer being the core layer of the multi-layer adhesive assembly, the second adhesive layer being the first skin layer of the multi-layer adhesive assembly, and the third adhesive layer being the second skin layer of the multi-layer adhesive assembly.

[0128] Item 21 is the adhesive film according to any one of items 17 to 20, wherein the second adhesive layer and / or the third adhesive layer comprises a polymer matrix selected from the group consisting of polyacrylate, polyurethane, polyolefin, polyamine, polyamide, polyester, polyether, polyisobutylene, polystyrene, polyvinyl, polyvinylpyrrolidone, natural rubber, synthetic rubber, and any combination, copolymer, or mixture thereof.

[0129] Item 22 is the adhesive film according to any one of items 17 to 21, wherein the second adhesive layer and / or the third adhesive layer comprises a polyacrylate polymer comprising linear or branched alkyl (meth)acrylate units having a linear or branched alkyl group having 1 to 32, 1 to 20, or 1 to 15 carbon atoms.

[0130] Item 23 is the adhesive film according to item 22, wherein the linear or branched alkyl (meth)acrylate units include at least one of isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, 2-octyl (meth)acrylate, or butyl acrylate units.

[0131] Item 24 is the adhesive film according to item 22 or 23, wherein the polyacrylate polymer further comprises polar monomer units, including at least one monomer unit of acrylic acid, methacrylic acid, itaconic acid, hydroxyalkyl acrylate, nitrogen-containing acrylate monomers, in particular acrylamide and substituted acrylamide and acrylamine and substituted acrylamine, and any combination or mixture thereof.

[0132] Item 25 is the adhesive film according to any one of Items 22 to 24, wherein the polyacrylate polymer further contains at least one monomer unit of isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, isophoryl (meth)acrylate, or cyclohexyl (meth)acrylate.

[0133] Item 26 is the adhesive film according to any one of Items 17 to 25, in which the second adhesive layer and / or the third adhesive layer contains a tackifier resin, in particular a hydrocarbon tackifier resin.

[0134] Item 27 is the adhesive film according to item 26, wherein the tackifier resin comprises at least one of a C5-based hydrocarbon resin, a C9-based hydrocarbon resin, or a C5 / C9-based hydrocarbon resin.

[0135] Item 28 is the adhesive film according to any one of items 17 to 27, wherein the second adhesive layer and / or the third adhesive layer further comprises a chlorinated polyolefin (co)polymer comprising at least one of chlorinated polypropylene, chlorinated polyethylene, or chlorinated ethylene / vinyl acetate copolymer.

[0136] Item 29 is the adhesive film according to any one of items 17 to 28, in which the second adhesive layer and / or the third adhesive layer are independently the adhesive film according to any one of items 1 to 16.

[0137] Item 30 is an adhesive film according to any one of items 17 to 29, obtained by a wet-on-wet coating process.

[0138] Item 31 is a process for producing the adhesive film according to any one of items 12 to 16, incorporating a second (meth)acrylate copolymer into a curable precursor composition comprising a linear or branched alkyl (meth)acrylate monomer, a (meth)acrylic acid monomer, a crosslinking monomer, and a polymerization initiator; and polymerizing a linear or branched alkyl (meth)acrylate monomer, a (meth)acrylic acid monomer, and a crosslinking monomer in the presence of a second (meth)acrylate copolymer to form a (meth)acrylate copolymer.

[0139] Item 32 is the process according to item 31, in which the second (meth)acrylate copolymer is obtained by free-radical polymerization, in particular by an essentially solvent-free polymerization process, in particular by an essentially adiabatic polymerization reaction.

[0140] Item 33 is the process according to items 31 or 32, wherein the second (meth)acrylate copolymer is obtained as a prepolymer composition having a polymer conversion in the range of at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, 10% to 60%, 20% to 55%, 30% to 50%, or up to 50%.

[0141] Item 34 is a process for producing the adhesive film according to any one of items 17 to 30, - superimposing a (liquid) precursor of the first adhesive layer, a (liquid) precursor of the second adhesive layer and optionally a (liquid) precursor of the third adhesive layer, thereby forming a curable precursor of a multi-layer adhesive assembly; and curing the curable precursor of the multi-layer adhesive assembly.

[0142] Item 35 is the process according to item 34, wherein curing of the curable precursor is carried out using actinic radiation.

[0143] Item 36 is the process of items 34 or 35, wherein a (bottom) layer of a curable (liquid) precursor of the second adhesive layer is covered by an adjacent (top) layer of a curable liquid precursor of the first adhesive polymer layer, respectively, essentially without exposing the (bottom) layer of the curable (liquid) precursor of the second adhesive layer.

[0144] Item 37 is the process according to item 36, comprising a (co)extrusion step.

[0145] Item 38 is the process of item 37, wherein the first adhesive layer, the second adhesive layer, and optionally the third adhesive layer are prepared separately and then laminated together.

[0146] Item 39 is the adhesive film according to any one of items 1 to 30, wherein the adhesive film adheres to a primer-treated substrate surface when applied without the use of heat or radiation.

[0147] Item 40 is the adhesive film according to any one of items 1 to 30 or 39, in which the adhesive film adheres to a primer-treated substrate surface without forming a covalent bond.

[0148] Item 41 is an adhesive system comprising a primer composition and the adhesive film according to any one of items 1 to 30, 39, and 40, wherein the adhesive film does not react with the primer composition to form a covalent bond.

[0149] Item 42 is the adhesive system according to item 41, wherein the primer composition comprises at least one of a polyamide, a polyurethane, or a polyacrylate.

[0150] Item 43 is the use or method of using the adhesive system according to items 41 or 42 for bonding substrates.

[0151] Item 44 is the use or method according to item 43, wherein the substrate is a low surface energy substrate, a medium surface energy substrate, and / or a high surface energy substrate.

[0152] Item 45 is the use or method according to items 43 or 44, wherein the substrate is useful in the construction industry or the automotive industry.

[0153] The present disclosure is further illustrated by the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the appended claims. EXAMPLES

[0154] [Table 1]

[0155] Test Method: Test substrates used for the test: Stainless steel (SS) plates ("Edelstahl 1.4301 IIID", 150 mm x 50 mm x 2 mm) were obtained from Rocholl GmbH, Eschenbronn, Germany.

[0156] Aluminum (Al) substrates (1 inch x 2 inch x 0.064 inch (2.5 cm x 5 cm x 1.1 mm)) were obtained from Rocholl GmbH, Eschenbronn, Germany.

[0157] Prior to testing, the substrates were cleaned as follows: the Al and SS plates were first cleaned with MEK and n-heptane and dried with a tissue, then cleaned with MEK and dried with a tissue.

[0158] 90° peel test at 300 mm / min (according to test method Finat No. 2) An adhesive film according to the present disclosure having a width of 10 mm and a length of >175 mm was cut lengthwise from the sample material.

[0159] For preparation of the test samples, the liner was first removed from one adhesive side and placed on an aluminum strip with the following dimensions: 22 x 1.6 cm. The adhesive coated side of each PSA strip was then placed, after the liner was removed, with its adhesive side facing down on a primed stainless steel test panel (primed with "3M PRIMER 4297") using light finger pressure. The test sample was then rolled twice in each direction with a standard FINAT test roller (weight 6.8 kg) at a speed of approximately 10 mm per second to ensure intimate contact between the adhesive mass and the surface. After the strips of adhesive composition and assembly were applied to the test panel, the test sample was left at ambient room temperature (23°C + / - 2°C, relative humidity 50% + / - 5%°C) for 24 or 72 hours prior to testing.

[0160] For the peel test, in a first step, the test sample was clamped in the lower movable jaw of a Zwick tensile tester (Model Z020, available from Zwick / Roell GmbH, Ulm, Germany). The pressure-sensitive adhesive film strip was folded back at a 90° angle and its free end was gripped in the upper jaw of the tensile tester in a configuration commonly used for 90° peel measurements. The tensile tester was set at a jaw separation speed of 300 mm per minute. Test results were expressed in Newtons per 10 mm (N / 10 mm). The reported peel value was the average of two 90° peel measurements.

[0161] Static shear test at 1000g and 110°C (FINAT Test Method No. 8. 8th Edition 2009) Static shear was a measure of the cohesiveness or internal strength of an adhesive. Static shear was measured in minutes as the time it took to pull a reference area of ​​the adhesive film from a test panel under the stress of a constant standard load.

[0162] Strips measuring 25 mm wide and 12.7 mm long were cut lengthwise from the adhesive film. One release liner was removed from the strip and the PSA sample was attached through its exposed adhesive surface onto an anodized aluminum backing. The second release liner was then removed and the PSA sample was attached to a test substrate coated with "3M PRIMER 4297" providing an adhesive area of ​​25 mm x 12.7 mm, using light finger pressure. A standard FINAT test roller (6.8 kg) was rolled once in each direction at a speed of approximately 10 mm per second to ensure intimate contact between the adhesive mass and the substrate surface. After the PSA strip was applied to the test plate, the test plate was left at room temperature for 24 hours before testing. A loop was made at the end of the test strip to hold the specified weight. The test panel was placed in a shear holding device. After a rest time of 15 minutes at a test temperature of 110°C, a load of 1000 g was attached to the loop. A timer was started. The results were recorded in minutes. Results are the average of three shear measurements. A recorded time of "10000+" indicated that the adhesive was not damaged after 10000 minutes.

[0163] Single lap shear test according to ASTM D 1002 / DIN EN 1465 (overlap shear test) Overlap shear (OLS) was used to measure the cohesiveness or internal strength of the adhesive film. The aluminum substrates described above were cleaned with MEK, then grit sandblasted, cleaned with MEK, followed by air drying for 10 minutes. The substrates were then primed with "3M PRIMER 4297" primer. Primer was applied with a wool dubber supplied by 3M Company so that approximately 2 inches were coated. The primed substrates were allowed to air dry for a minimum of 10 minutes before applying the adhesive. Test specimens were made by cutting 1 inch (2 cm) strips of adhesive. One liner was removed and the adhesive was placed across the primed portion of the substrate. A 2 inch (5.1 cm) stiff rubber roller was used to ensure complete adhesive contact. The top release liner was removed to expose the adhesive, which was then introduced to a second primed substrate to form a bond. A pressure of approximately 150N was then applied to the closed bond for 30 seconds, and the bonded test assemblies were allowed to sit at room temperature (23°C + / - 2°C, 50% relative humidity + / - 5%°C) for 3 days before testing. Dynamic overlap shear tests were performed at 23°C using a Zwick tensile tester (Model Z020, available from Zwick / Roell GmbH, Ulm, Germany). The specimens were loaded into the grips and the crosshead was run at 1 inch (2.5 mm) per minute, loading the specimens to failure. The breaking stress was recorded in MPa using the test method disclosed in ASTM D1002. The results are reported in Tables 4 and 5 below. The failure mode for each example and comparative example was cohesive failure.

[0164] Shear Storage Modulus A strain-controlled rheometer in oscillatory shear mode at a constant frequency of 1 Hz with parallel plate geometry (8 mm) was used (Model ARES G2 available from TA Instruments, 159 Lukens Drive, New Castle, DE 19720, USA). Circular die-cut samples with a diameter of 8 mm and a thickness of 0.6 mm were exposed to a temperature gradient from -50°C to +150°C applying a heating rate of 5°C / min. Oscillatory strain and normal force control were adjusted to maintain adequate contact between the sample and the measurement geometry and a deformation level within the linear viscoelastic region of the sample material over the entire temperature range. The glass transition was determined as the peak temperature of the loss tangent. The complex modulus, storage modulus and loss tangent were monitored over the entire temperature range and specifically determined at 25°C. For comparison of tape formulations, the complex modulus was evaluated. The complex modulus was determined by the storage modulus, which reflects the Dahlquist criteria, and the respective loss tangent tan5, which is the ratio of the loss modulus to the storage modulus.

[0165] Preparation of the second acrylate copolymer: A second (meth)acrylate copolymer (hereafter referred to as Copolymer 2) was prepared as follows. The polymerization was carried out using a Buchi Poly cave stainless steel reactor (available from Buchi Labortechnik GmbH, City, The Netherlands). In the first step of the polymerization, the Buchi reactor was charged with 250 grams of a mixture of EHA (80 wt%), AA (20 wt%), IOTG (0.04 wt%) and 3 ppm of "VAZO 52" initiator. The reactor was sealed and purged of oxygen, and then maintained with approximately 1 bar of nitrogen pressure. The reaction mixture was heated to 60°C and the reaction proceeded adiabatically. The reaction peak temperature was 110°C. When the reaction was complete, the mixture was cooled to below 50°C. The polymerization conversion was around approximately 35%.

[0166] Precursors to Examples 1-6: The precursor compositions of Examples 1-6 were first prepared by diluting the copolymer 2 described above in a polymerized precursor composition containing C8 acrylate (EHA) and acrylic acid (15 wt%-20 wt%) as well as other high Tg monomers as shown in Table 2 below. Always, the resulting composition was mixed by shaking (150 U / min) with a rolling bench (Model LD 209 available from Labortechnik Frobel, Germany) propeller agitator for about 24 hours and mixing was stopped when a clear homogenous mixture was obtained. Then, the photoinitiator OMNIRAD 651, HDDA crosslinker, and fumed silica particles were added and mixed again by shaking for about 24 hours. In the third step, glass bubbles were added and the mixture was stirred with a propeller agitator (300 U / min) for 5 minutes to disperse. The exact formulations of the polymerized precursor compositions of Examples 1-6 are listed in Table 2 below. The corresponding first (meth)acrylate copolymer was formed in-situ in the presence of the second (meth)acrylate copolymer.

[0167] Example 7, Illustrative Example 8, Example FL-9, and Precursors of Skin Layers 1-6: The precursors of Examples 7 and FL-9, Illustrative Example 8, and Skin Layers 1-6 were prepared by combining a monomer composition including C8 acrylate (2-EHA), acrylic acid, and IBOA with 0.04 pph of photoinitiator in a glass container. The mixture was flushed with nitrogen for 10 minutes before UV exposure was started. Nitrogen was also bubbled through the mixture at all times until the polymerization process was stopped by adding air to the syrup. The mixture was stirred at all times with a propeller stirrer (300 revolutions per minute (U / min)) and the reaction was stopped when it reached a viscosity of 2800 mPas to 4000 mPas, as measured by a Brookfield Viscosimeter (Model DV1 Digital Viscosimeter, Hadamar-Steinbach, Germany) at T=25° C., spindle 4.12 rpm. The photoinitiator OMNIRAD 651, HDDA crosslinker, DCPA, and fumed silica particles were then added and mixed again. In the third step, glass bubbles were added and the mixture was stirred with a propeller stirrer (300 U / min) for 5 minutes to dissolve / disperse them. The exact formulation of the polymeric precursor composition is listed in Tables 2 and 3 below.

[0168] [Table 2]

[0169] [Table 3]

[0170] Preparation of Examples 1 to 7 and Illustrative Example 8 (Ex1 to Ex7 and IE8) The liquid precursors of Examples 1-7 and Illustrative Example 8 were coated on a laboratory coater with a gap of 600 micrometers calculated from the substrate surface, according to the method described in U.S. Pat. No. 4,818,610 (Zimmerman et al.). The adhesive film was cured between two polyester film liners ("HOSTAPHAN 2SLK", Mitsubishi Polyester Film GmbH, Wiesbaden, Germany). Curing was achieved from both the top and bottom in a UV curing station with a length of 300 cm, with the line speed set at 0.70 m / min. The total irradiation intensity cumulatively irradiated from the top to the bottom was approximately 3 mW / cm. 2 It was.

[0171] Preparation of Multi-Layer Pressure-Sensitive Adhesive Assemblies of Examples 9 to 14 (Ex9 to Ex14) The pressure sensitive adhesive skin layers SL-1 to SL-6 and the foam precursor of Example 9 were layered on top of each other in a laboratory coater according to the method described in U.S. Patent No. 4,818,610 (Zimmerman et al.). This allowed the liquid precursor of the pressure sensitive adhesive skin layer (e.g., SL-1) to be coated onto the bottom of the foam core layer EX-9. The knife height settings were 120 pm for the first knife (for pressure sensitive adhesive skin layers SL-1 to SL-6) and 620 to 640 pm for the second knife (for polymer foam core layer EX-9), both levels calculated from the substrate surface. The curing between the two liners described above for Examples 1 to 7 was achieved from both the top and bottom in a UV curing station with a length of 300 cm, with the line speed set at 1.00 m / min. The total irradiation intensity cumulatively irradiated from top to bottom was approximately 3 mW / cm. 2 It was.

[0172] result:

[0173] [Table 4]

[0174] [Table 5]

[0175] This disclosure is not limited to the above-described embodiments, but should be limited only by the limitations set forth in the following claims and any equivalents thereof.

Claims

1. An adhesive film comprising a first (meth)acrylate copolymer, The first (meth)acrylate copolymer comprises: at least 55 wt. % of linear or branched alkyl (meth)acrylate monomer units, based on the weight of the first (meth)acrylate copolymer; 15% to 40% by weight, based on the weight of the first (meth)acrylate copolymer, of (meth)acrylic acid monomer units, wherein when the first (meth)acrylate copolymer comprises 15% by weight of (meth)acrylic acid monomer units, at least 5% by weight, based on the weight of the first (meth)acrylate copolymer, of a high T acrylic acid monomer unit provides a homopolymer having a glass transition temperature of at least 50°C when homopolymerized. ｇ (meth)acrylic acid monomer units, including monomer units of the monomer 0.1% to 5% by weight, based on the weight of the first (meth)acrylate copolymer, of monomer units of a crosslinking monomer having two or more (meth)acrylate groups; The adhesive film comprises 5% by weight or less of an additional (meth)acrylate copolymer, the additional (meth)acrylate copolymer comprising 0.1% by weight to 15% by weight of (meth)acrylic acid monomer units, based on the weight of the additional (meth)acrylate copolymer.

2. 2. The adhesive film of claim 1, wherein the first (meth)acrylate copolymer comprises (meth)acrylic acid monomer units in an amount greater than 15% by weight based on the weight of the first (meth)acrylate copolymer.

3. When homopolymerized, it provides a homopolymer having a glass transition temperature of at least 50°C. ｇ The adhesive film of claim 2 further comprising a monomer unit of a monomer.

4. 10. The adhesive film of claim 1, wherein the adhesive film has a storage modulus greater than 0.5 megapascals as measured with a rheometer at 25°C and 1 hertz.

5. 10. The adhesive film of claim 1 having a thickness of at least 0.3 millimeters.

6. The adhesive film of claim 1 , wherein the adhesive film is a foam.

7. 7. The adhesive film of claim 6, comprising 2% to 12% by weight, based on the total weight of the adhesive film, of at least one of polymeric microspheres or glass bubbles.

8. The adhesive film according to claim 1, further comprising a second (meth)acrylate copolymer, wherein the second (meth)acrylate copolymer comprises from 15% by weight to 40% by weight of (meth)acrylic acid monomer units, based on the weight of the second (meth)acrylate copolymer.

9. The adhesive film of claim 8, wherein the first (meth)acrylate copolymer is present in an amount ranging from 65% to 99% by weight and the second (meth)acrylate copolymer is present in an amount ranging from 1% to 35% by weight, based on the total weight of the adhesive film.

10. The adhesive film of claim 1, wherein the adhesive film is a multi-layer adhesive assembly comprising a first layer of the first (meth)acrylate copolymer and a second adhesive layer adjacent to the first layer.

11. 11. The adhesive film of claim 10, wherein the first layer of the first (meth)acrylate copolymer is the core of a skin-core-skin multilayer adhesive.

12. A process for producing an adhesive film according to claim 8 or 9, comprising: incorporating the second (meth)acrylate copolymer into a curable precursor composition comprising the linear or branched alkyl (meth)acrylate monomer, the (meth)acrylic acid monomer, the crosslinking monomer, and a polymerization initiator; polymerizing the linear or branched alkyl (meth)acrylate monomer, the (meth)acrylic acid monomer, and the crosslinking monomer in the presence of the second (meth)acrylate copolymer to form the first (meth)acrylate copolymer; The process includes:

13. The adhesive film of any one of claims 1 to 11, wherein the adhesive film adheres to a primed substrate surface when applied without the use of heat or radiation.

14. An adhesive system comprising a primer composition and the adhesive film according to any one of claims 1 to 11, wherein the adhesive film does not react with the primer composition to form a covalent bond.

15. 15. The adhesive system of claim 14, wherein the primer composition comprises at least one of a polyamide, a polyurethane, or a polyacrylate.