Multilayer adhesive film, method for manufacturing the same, and use

Abstract

The present invention provides multilayer adhesive films, methods for manufacturing them, and uses thereof. In particular, the disclosure herein relates to multilayer adhesive films that exhibit excellent impact resistance, good adhesive strength, and excellent reworkability when cured at low temperatures, for example, not exceeding 90°C.

Description

Technical Field

[0001] Technical Field The present invention relates to a multilayer adhesive film, a method for producing the same and use thereof. In particular, the disclosure herein relates to a multilayer adhesive film that exhibits excellent impact resistance, good adhesive strength and excellent reworkability when cured at a low temperature, for example, a low temperature not exceeding 90°C.

Background Art

[0002] Background of the Invention Thermally activatable adhesive films are widely used in assembling substrates in the manufacture of electronic devices. The term "thermally activated" (or "thermally activatable") refers to a composition having latent adhesive properties that are only activated after heating above a predetermined temperature. Such compositions have other advantages including that they are easy and quick to use and are self-supporting. During the manufacturing process, the thermally activatable adhesive film is placed between the surfaces of the substrates to be assembled and held in contact therewith. At the same time, the assembly is heated to activate the adhesive composition. The heating time varies depending on the thickness of the substrate, but it must not be too long to avoid thermal deformation of the substrate. In some cases, pre-bonding allows the adhesive film to be partially cured partially at a lower temperature, and final bonding cures the adhesive film to sufficiently bond the substrates. After cooling, an adhesive film having a specific adhesive strength is obtained and the substrates are assembled.

[0003] Current thermally activatable adhesive films disclosed in the prior art or available on the market are based on thermoplastic polymers, polyols and NCO-terminated isocyanates. When cured at low temperatures, for example, temperatures not exceeding 90°C, such adhesive films exhibit insufficient impact resistance, insufficient adhesive strength or insufficient reworkability, cause damage to substrates or leave residues, and cannot meet the requirements of electronic device manufacturing.

Summary of the Invention

Problem to be Solved by the Invention

[0004] Considering the above, a multilayer adhesive film is needed that exhibits excellent impact resistance, adhesive strength, and excellent reworkability when cured at low temperatures, for example, not exceeding 90°C. [Means for solving the problem]

[0005] Summary of the Invention According to a first aspect of the present invention, the disclosure herein is: A first layer having a first main surface and a second main surface opposite the first main surface, and The second layer is placed on the first main surface of the heat-activated adhesive film. We provide a multilayer adhesive film that includes the following: Here, the first layer is a heat-activated adhesive film obtained by drying a solvent-based heat-activated adhesive composition (A) until the solvent content is 5% by weight or less of the total weight of the solvent-based heat-activated adhesive composition, wherein the solvent-based heat-activated adhesive composition (A) comprises at least one thermoplastic polymer (A1), at least one polyol (A2), at least one polyisocyanate (A3) having at least two isocyanate groups and at least one uretdione group in one molecule, and an organic solvent (A4). Here, the second layer is derived from a dispersion composition (B) comprising at least one aqueous polyurethane dispersion (B1) and optionally a latent curing agent (B2).

[0006] A second aspect of the present invention is a method for producing a multilayer adhesive film according to the present invention.

[0007] A third aspect of the present invention is an article comprising a first substrate, a second substrate, and a multilayer adhesive film according to the present invention disposed between the first and second substrates.

[0008] A fourth aspect of the present invention is the use of a multilayer adhesive film according to the present invention, or the use of an article containing a multilayer adhesive film in the manufacture of automotive parts, truck bed covers (or tonneau covers), laminated textiles, assembled products, and electronic equipment.

[0009] Other features and aspects of the present invention will be described in detail below. [Modes for carrying out the invention]

[0010] Detailed description of the invention Those skilled in the art will understand that this description is merely illustrative of exemplary embodiments and is not intended to limit the broader aspects of the invention. Each aspect described herein may be combined with any other aspect unless explicitly stated otherwise. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0011] Unless otherwise specified, terms used in the context of this invention shall be interpreted in accordance with the following provisions.

[0012] Unless otherwise specified, the terms "a," "an," and "the" used herein shall include both singular and plural forms.

[0013] As used herein, the terms “comprising” and “comprises” are synonymous with “including,” “includes,” “containing,” or “contains,” and are comprehensive or non-restrictive, and do not preclude additional, undescribed components, elements, or method steps.

[0014] The terms “at least one” or “one or more” used herein to define a component (or element) refer to the types of components, not the absolute number of molecules. For example, “one or more polyols” means one type of polyol or a mixture of several different polyols.

[0015] The term "thermally active" is understood to mean that the adhesive film has latent adhesive properties such that the adhesive film is only activated after being heated above a predetermined temperature ("activation temperature"). The film exhibits its adhesive properties during this thermal activation step.

[0016] The term "adhesive film" means an adhesive in film form.

[0017] The term "self-supporting adhesive film" means an adhesive film that maintains its integrity even in the absence of any substrate.

[0018] In the context of the present invention, a "liner" or "releasable liner" is not regarded as a substrate.

[0019] The term "polyurethane" means polyurethanes and polyurethanes containing urea groups in the polyurethane backbone.

[0020] As used herein, the term "room temperature" refers to a temperature of from about 20°C to about 25°C, preferably about 25°C.

[0021] Unless otherwise stated, the recitation of numerical endpoints includes all values and fractions subsumed within the respective ranges, as well as the recited endpoints.

[0022] All references cited herein are hereby incorporated by reference in their entireties.

[0023] Unless otherwise stated, molecular weight refers to number average molecular weight (Mn). Unless otherwise stated, all molecular weight data refer to values obtained by gel permeation chromatography (GPC), for example according to DIN 55672.

[0024] The softening points described herein are determined by using the Ring and Ball method according to DIN ISO 4625.

[0025] Unless otherwise specified, all terms used in this invention, including technical and scientific terms, have the meanings generally understood by those skilled in the art.

[0026] According to a first aspect of the present invention, the disclosure herein is: A first layer having a first main surface and a second main surface opposite the first main surface, and The second layer is placed on the first main surface of the heat-activated adhesive film. We provide a multilayer adhesive film that includes the following: Here, the first layer is a heat-activated adhesive film obtained by drying a solvent-based heat-activated adhesive composition (A) until the solvent content is 5% by weight or less of the total weight of the solvent-based heat-activated adhesive composition, wherein the solvent-based heat-activated adhesive composition (A) comprises at least one thermoplastic polymer (A1), at least one polyol (A2), at least one polyisocyanate (A3) having at least two isocyanate groups and at least one uretdione group in one molecule, and an organic solvent (A4). Here, the second layer is derived from a dispersion composition (B) comprising at least one aqueous polyurethane dispersion (B1) and optionally a latent curing agent (B2).

[0027] (A) Solvent-based thermoactive adhesive composition According to the present invention, the solvent-based thermoactive adhesive composition (A) comprises at least one thermoplastic polymer (A1), at least one polyol (A2), at least one polyisocyanate (A3) having at least two isocyanate groups and at least one uretdione group in one molecule, and an organic solvent (A4).

[0028] (A1) Thermoplastic polymer The thermoplastic polymer (A1) provides the backbone for the thermoactive adhesive film. Without the thermoplastic polymer, the multilayer adhesive film cannot achieve a self-supporting adhesive film.

[0029] Unlike thermosetting polymers, which crosslink or harden and solidify when heated, thermoplastic polymers are flexible at high temperatures and solidify when cooled.

[0030] In some embodiments, the thermoplastic polymer (A1) can have a weight-average molecular weight (Mw) of at least 10,000 g / mol, preferably 10,000 to 200,000 g / mol, preferably 10,000 to 150,000 g / mol, and more preferably 20,000 to 100,000 g / mol.

[0031] In some embodiments, the thermoplastic polymer (A1) exhibits an optimal activation temperature of 100°C or less, preferably less than 85°C, preferably between 30°C and less than 80°C, more preferably between 30°C and less than 70°C, and even more preferably between 30°C and less than 60°C. Within the preferred range, the thermoactive adhesive film derived from the thermoactive adhesive composition (A) can be self-supporting and exhibit a certain adhesive strength even when cured at low temperatures, for example, not exceeding 90°C.

[0032] As used herein, the term “optimal activation temperature” refers to the temperature range (or point) in a thermoplastic polymer where (physical) aggregation occurs and satisfactory strength is achieved with less than 10% non-aggregated portion. The optimal activation temperature of the thermoplastic polymers described herein is determined based on EN 12961:2001.

[0033] Generally, the thermoplastic polymer (A1) described herein is chemically nonreactive, undergoes aggregation upon heating, and becomes flexible with specific adhesive properties. In some embodiments, the thermoplastic polymer (A1) may contain hydroxyl groups that can react with component (A3).

[0034] In the present invention, a wide variety of thermoplastic polymers can be used. Suitable thermoplastic polymers for use in the present invention can be selected from the group consisting of thermoplastic polyurethane polymers, polyester polymers, acrylic polymers, ethylene-vinyl acetate copolymers, styrene block copolymers, polyvinyl acetol, styrene acrylonitrile, polyolefins, polyacrylonitrile, ethylene vinyl acetate ternary copolymers, functionalized ethylene vinyl acetate, ethylene acrylate copolymers, ethylene acrylate ternary copolymers, ethylene butadiene copolymers, and block copolymers, and are preferably selected from thermoplastic polyurethane polymers, polyester polymers, acrylic polymers, styrene block copolymers, and combinations thereof.

[0035] In some embodiments, thermoplastic polyurethane polymers can be used as component (A1) in the present invention. Suitable thermoplastic polyurethane polymers can be obtained from ring-opening polymerization reactions of lactones such as ε-caprolactone, or from reactions of polyester polyols and polyether polyols with diisocyanates, and may be further obtained from reactions of such components with chain extenders such as low molecular weight polyols, preferably diols, or with diamines to form urea bonds, as needed.

[0036] Useful polyester polyols for use in the preparation of thermoplastic polyurethane polymers as component (A1) include, for example, linear dicarboxylic acids, dicarboxylic acid derivatives (e.g., anhydrides, esters, and acid chlorides), aliphatic polyols, cyclic aliphatic polyols, linear polyols, branched polyols, and polyester polyols derived from combinations thereof. Useful dicarboxylic acids from which polyester polyols can be derived include adipic acid, succinic acid, sebacic acid, dodecanediic acid, phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, dimer acid, and combinations thereof. Useful aliphatic diols from which polyester polyols can be derived include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, methylpropanediol, 3-methyl-1,5-propanediol, and combinations thereof.

[0037] Examples of useful polyether polyols used in the preparation of thermoplastic polyurethane polymers to be used as component (A1) include the polymerization of cyclic oxides, e.g., ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran, or by adding one or more such oxides to a polyfunctional initiator having at least two active hydrogens, e.g., water, polyhydric alcohols (e.g., ethylene glycol, propylene glycol, diethylene glycol, cyclohexanedimethanol, glycerol, trimethylolpropane, pentaerythritol, and bisphenol A), ethylenediamine, propylenediamine, triethanolamine, and 1,2-propanedithiol.

[0038] Useful thermoplastic polyurethane polymers for use as thermoplastic polymer (A1) generally consist of a soft segment, such as a polyether or polyester polyol, and a hard segment, usually derived from the reaction of low molecular weight diols and diisocyanates. Commercially available thermoplastic polyurethane polymers for use as component (A1) include, but are not limited to, the Pearlstick series from Lubrizol, such as 5707, 5703, 5701, 5714, 5713, 5715, 45-40, 45-50, 45-60, 45-80, 45-90, 48-60, 40-70, and 46-10; the HF-4003LH, 3003EH series, HF-3H, and 6H series from Huafeng Chemicals; and the WHT-61, 63, 64, 65, and 67 series from Wanhua Chemicals.

[0039] Suitable polyester polymers to be used as component (A1) include ethylene glycol, diethylene glycol, trimethylene glycol, butanediol (1,4-butanediol, 1,2-butanediol, 1,3-butanediol), neopentyl glycol, 2-methyl-1,3-propanediol, hexanediol (hexamethylene glycol), propanediol (propane-1,2-diol, propane-1,3-diol, or propylene glycol), trimethylolpropane, cyclohexanedimethanol, or combinations thereof. It can be obtained by polycondensation of at least one polyester diol with at least one dicarboxylic acid or its ester or anhydride derivative, such as terephthalic acid, dimethyl terephthalate, isophthalic acid, adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, dodecanoic acid (1,10-decanedicarboxylic acid), succinic acid, dimer acid, phthalic anhydride, maleic anhydride, and a hydroxycarboxylic acid such as polycaprolactone or a diester obtained from ε-caprolactone and diethylene glycol, or a combination thereof. Commercial polyester polymers used as component (A1) include, but are not limited to, BX1001 manufactured by TOYOBO, CAPA® 6800, 6500, 6400 from Perstorp, PLACCEL H series manufactured by Daicel, and PCL65000, PCL68000 from Hunan Juren Chemical.

[0040] Suitable acrylic polymers for use as component (A1) can be obtained by polymerizing esters of acrylic acid and methacrylic acid monomers. Exemplary and useful monomers for use in the synthesis of component (A) include soft monomers such as ethyl acrylate, 2-ethylhexyl acrylate, and n-butyl acrylate, and hard monomers such as methyl methacrylate and isobutyl acrylate. Exemplary acrylic polymers for use as component (A1) include polymethyl methacrylate, n-butyl acrylate-based block copolymers, n-butyl acrylate / 2-ethylhexyl acrylate-based block copolymers, and combinations thereof. It is preferable to use acrylic block polymers derived from soft and hard monomers. Commercially available acrylic polymers for use as component (A1) include, but are not limited to, n-butyl acrylate-methacrylate copolymers under Kurarity® LA-2140 manufactured by SANYO.

[0041] Suitable styrene block copolymers to be used as component (A1) include aromatic vinyl polymer blocks and saturated intermediate blocks, preferably hydrogenated conjugated diene polymer blocks or unsaturated intermediate blocks. The blocks may be arranged in various structures, e.g., linear, branched, radial, star-shaped, and combinations thereof. Aromatic vinyl polymer blocks can be derived from a variety of aromatic vinyl compounds, including, for example, styrene, α-methylstyrene, β-methylstyrene, o-,m-,p-methylstyrene, t-butylstyrene-2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, 1,3-vinylnaphthalene, vinylanthracene, indene, acenaphthylene, and combinations thereof. Hydrogenated diene polymer blocks can be derived from a variety of diene-containing compounds, including, for example, isoprene, butadiene, hexadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and combinations thereof. Useful styrene block copolymers having a saturated intermediate block for use as component (A1) include, for example, triblock, multi-arm, and radial copolymers, specifically including styrene-ethylene / butene-styrene (SEBS), styrene-ethylene / propylene-styrene (SEPS), styrene-ethylene-ethylene / propylene-styrene (SEEPS), styrene / isobutylene / styrene (SIBS), and combinations thereof. Useful styrene block copolymers having an unsaturated intermediate block for use as component (A1) include styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-butadiene-isobutylene-styrene (SBBS), styrene-isoprene-butadiene-styrene (SIBS), and combinations thereof. Commercially available styrene block copolymers for use as component (A1) include, but are not limited to, Kuraray's HYBRAR® 5125 and 7311.

[0042] A suitable ethylene-vinyl acetate copolymer to be used as component (A1) is derived from at least one ethylene monomer and at least one vinyl acetate monomer. From the viewpoint of the strength and flexibility of the heat-activated adhesive film, the ethylene-vinyl acetate copolymer to be used as component (A1) preferably has a vinyl acetate content of 18% by mass or more. Commercially available ethylene-vinyl acetate copolymers to be used as component (A1) include, but are not limited to, ARLANXEO's Levamelt™ 686 (68% by weight vinyl acetate), KBE-68 A and KBE-68 B manufactured by Kuraray.

[0043] Other useful thermoplastic polymers to be used as component (A) include, but are not limited to, polyvinyl acetol, styrene acrylonitrile, polyolefins, polyacrylonitrile, ethylene vinyl acetate terpolymer, functionalized ethylene vinyl acetate, ethylene acrylate copolymer, ethylene acrylate terpolymer, ethylene butadiene copolymer and block copolymer, and combinations thereof.

[0044] The thermoplastic polymers described above can be used individually or in combination of two or more types.

[0045] Particularly preferably, component (A1) may be present in an amount of 1% to 95% by weight, preferably 10% to 40% by weight, based on the total weight of the solvent-based thermally activated adhesive composition (A).

[0046] (A2) Polyol According to the present invention, the solvent-based thermally activated adhesive composition (A) comprises at least one polyol (A2) and reacts with the component (A3) described later to form an effective bond upon heating.

[0047] The useful polyols (A2) in the present invention include those having at least two hydroxyl groups, such as three or four hydroxyl groups in one molecule, and having an aromatic group in one molecule, preferably having a hydroxyl value of 10 mg KOH / g or more, preferably equal to or greater than 15 mg KOH / g, more preferably 20 to 90 KOH / g, and even more preferably 30 to 60 KOH / g.

[0048] Preferably, component (A2) is a polyester polyol having a weight-average molecular weight (Mw) of less than 10,000 g / mol.

[0049] The component (A2) used in the present invention is preferably solid at ambient temperature (20°C). In some embodiments, the component (A2) may be selected from the group consisting of amorphous polyester polyols, semicrystalline polyester polyols, crystalline polyester polyols, and combinations thereof, from the viewpoint of solubility in organic solvents, and is preferably amorphous polyester polyols, semicrystalline polyester polyols, and combinations thereof.

[0050] As used herein, the term "amorphous polyester polyol" means a polyester polyol that does not undergo a melting transition when measured using differential scanning calorimetry (DSC) and does not have a crystalline form. Preferably, it has a degree of crystallinity of less than 10% by weight, preferably less than 5% by weight, advantageously less than 2% by weight, and more advantageously less than 1% by weight.

[0051] The term "semicrystalline polyester polyol" refers to a polyester polyol that contains crystalline and amorphous regions within its structure. Preferably, it has a degree of crystallinity of at least 20% to less than 80% by weight, more preferably at least 30% to less than 80% by weight, and even more preferably at least 40% to less than 80% by weight.

[0052] As used herein, the term "crystalline polyester polyol" refers to a polyester polyol that exhibits a melting transition when measured using differential scanning calorimetry (DSC) and has a crystalline form. Preferably, it has a degree of crystallinity of at least 80% by weight, and more preferably at least 90% by weight.

[0053] Crystallinity, which indicates the proportion of a substance in a crystalline state, can be determined by X-ray diffraction analysis at different angles of incidence, calorimetry such as DSC (differential scanning calorimetry), or other methods that can estimate the crystalline phase ratio of semicrystalline polyester polyols.

[0054] A useful amorphous polyester polyol used as component (A2) in the present invention comprises a reaction product of a polyacid (e.g., polyacids, polyanhydrides, polyacid esters, and polyacid halides) and a stoichiometrically excess amount of polyol. At least one polyacid component and the polyol contain an aromatic group. Suitable polyacids include, for example, diacids (e.g., dicarboxylic acids), triacids (e.g., tricarboxylic acids), and higher acids, including, for example, aromatic dicarboxylic acids, their anhydrides and esters, and higher acids (e.g., terephthalic acid, isophthalic acid, dimethylterephthalic acid, diethylterephthalic acid, phthalic acid, phthalic anhydride, methyl-hexahydrophthalic acid, methyl-hexahydrophthalic anhydride, methyl-tetrahydrophthalic acid, methyl-tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, and tetrahydrophthalic acid). This includes aliphatic dicarboxylic acids and their anhydrides (e.g., maleic acid, maleic anhydride, succinic acid, succinic anhydride, glutaric acid, glutaric anhydride, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, chlorendic acid, 1,2,4-butane-tricarboxylic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, dimeric acid, dimerized fatty acids, trimerized fatty acids, and fumaric acid), and alicyclic dicarboxylic acids (1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid), and mixtures thereof.Examples of suitable polyols include, for example, ethylene glycol, propanediols (e.g., 1,2-propanediol and 1,3-propanediol), butanediols (e.g., 1,3-butanediol, 1,4-butanediol, 1,2-butanediol), 1,3-butenediol, 1,4-butenediol, 1,4-butynediol, pentanediol (e.g., 1,5-pentanediol), pentenediol, pentynediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and This includes ethylene glycol, propylene glycol, polypropylene glycol (e.g., dipropylene glycol and tripropylene glycol), 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, dimergol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, glycerol, tetramethylene glycol, polytetramethylene glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, trimethylolpropane, pentaerythritol, sorbitol, glucose, and combinations thereof.

[0055] Specific examples of useful amorphous polyester polyols include poly(hexanediol phthalate) polyol, poly(neopentyl glycol adipate) polyol, poly(neopentyl glycol phthalate) polyol, poly(neopentyl glycol hexanediol phthalate) polyol, poly(diethylene glycol phthalate) polyol, poly(ethylene glycol terephthalate adipate) polyol, polyethylene terephthalate polyol, random copolymer diols of ethylene glycol, hexanediol, neopentyl glycol, adipic acid, and terephthalic acid, and combinations thereof.

[0056] When using a solid amorphous polyester polyol, it is preferable to have a softening point of 130°C or lower, preferably 120°C or lower, preferably 105°C or lower, for example, 60°C, 80°C, or 100°C, from the viewpoint of achieving good adhesive strength when fully cured and easy dissolution in a solvent-based thermoactive adhesive composition (A).

[0057] Suitable crystalline polyester polyols as component (A2) in the present invention can be obtained from ring-opening polymerization reactions of lactones such as ε-caprolactone, or can be derived from diols and diacids. Exemplary diols in the preparation of preferred polyester polyols include ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and combinations thereof. Examples of diacids in the preparation of preferred polyester polyols include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and 1,12-dodecanediol, dimer acids, and combinations thereof. The range of diacids includes various derivatives of diacids such as carboxylic acid esters (especially methyl and ethyl esters), acid halides (such as acid chlorides), acid anhydrides, and combinations thereof.

[0058] Suitable crystalline polyester polyols include poly(hexanediol adipate) polyol, poly(butanediol adipate) polyol, poly-ε-caprolactone polyol, poly(dodecanediol hexanediol) polyol, poly(hexanediol terephthalate adipate) polyol, and combinations thereof.

[0059] The polyols described above can be used individually or in combination of two or more types.

[0060] Suitable commercially available polyols (A2) include FZPE-A03130 from GUANGZHOU FTRT CHEMICAL CO., DYNACOLL 7110, 7130, 7140 and 7150 from Evonik Industries AG, and FLP PA-1000N from Xuchuan Chemical (Suzhou) Co., Ltd.

[0061] Particularly preferably, component (A2) may be present in an amount of 0.01% to 80% by weight, preferably 5% to 40% by weight, based on the total weight of the solvent-based thermally activated adhesive composition (A).

[0062] (A3) Polyisocyanate According to the present invention, the solvent-based thermally activated adhesive composition (A) comprises at least one polyisocyanate (A3) having at least two isocyanate groups and at least one uretdione group in one molecule.

[0063] A useful polyisocyanate (A3) usable under the present invention corresponds to the following formula (I): [ka] (In the formula, -R is a divalent group containing 6 to 13 carbon atoms, and -n is an integer in the range of 0 to 10. Preferably, R is obtained from a divalent aromatic or polycyclic aromatic group, more preferably from an aromatic isocyanate such as toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI).

[0064] An example of a polyisocyanate (A3) usable under the present invention corresponds to one of the following formulas (I-1) or (I-2): [ka]

[0065] Preferably, the polyisocyanate (A3) usable under the present invention has an NCO content in the range of 15% to 40% by weight, more preferably 20% to 35% by weight, relative to the weight of the polyisocyanate.

[0066] Preferably, the solvent-based thermally activated adhesive composition (A) has a molar ratio of NCO / OH of 0.1 to 8:1. The isocyanate groups are derived from component (A3) present in the solvent-based thermally activated adhesive composition (A) according to the present invention, and the hydroxyl groups are derived from component (A2) according to the invention and, if present, from small amounts of hydroxyl groups in component (A1). The weight percentages of the polyol (A2) and polyisocyanate (A3) are not particularly limited, provided that the above molar ratios are met.

[0067] Suitable commercially available polyisocyanates (A3) include Grilbond® A2bond (MDI uretdione) sold by EMS-Griltech and Addolink® TT (TDI uretdione) sold by Rhein Chemie.

[0068] Particularly preferably, component (A3) may be present in an amount of 0.05% to 20% by weight, preferably 0.5% to 5% by weight, based on the total weight of the solvent-based thermally activated adhesive composition (A).

[0069] (A4) Organic solvents According to the present invention, the solvent-based thermally activated adhesive composition (A) comprises at least one organic solvent (A4).

[0070] The organic solvent (A4) that can be used according to the present invention is preferably one in which components (A1) and (A2), as well as other components or additives used as needed, are soluble in the organic solvent (A4), forming a mixture in which component (A3) can be uniformly dispersed, and which allows the solvent-based thermally activated adhesive composition (A) to be easily used on a substrate.

[0071] Preferably, the organic solvent (A4) has a solubility parameter δ (also known as Hildebrand solubility parameter or HSP) of 6.9 to 10.0 (cal / cm³). 3 The range is 1 / 2, and the hydrogen bonding index (HBI) γ is in the range of 5.0 to 7.7. These parameters are defined in a manner widely known in the literature, for example, in paragraphs 38 and 39 of patent application US 2004 / 0204524: -The solubility parameter δ is defined in Rompp Lexikon Lacke and Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, “Solubility parameters,” pp. 361-365; - The hydrogen bonding index represents the ability of solvent molecules to form hydrogen bonds. Donor solvents have a negative hydrogen bonding index, and acceptor solvents have a positive hydrogen bonding index. The hydrogen bonding index is determined based on the deviation of the infrared band relative to the RO-H stretching band (RCNelson, RWIrmwall and GDEdwards, Journal of Paint Technology, “Treatment of hydrogen bonding in predicting miscibility,” Vol.42, No.550, 1970, pp.636-643). Preferably, the organic solvent (A4) is selected from the group consisting of ketones, preferably aliphatic ketones, more preferably acetone, methyl ethyl ketone (MEK), 2-pentanone, 3-pentane, methyl isobutyl ketone, ethyl acetate, and combinations thereof.

[0072] Preferably, the organic solvent (A4) has a boiling point lower than the optimal activation temperature of the thermoplastic polymer (A1), ensuring that the thermoplastic polymer is not activated when the organic solvent is evaporated to form a thermosetting adhesive film, and the boiling point is, for example, less than 100°C, more preferably less than 80°C.

[0073] The above ingredient (A4) can be used alone or in combination of two or more.

[0074] In certain embodiments, the organic solvent (A4) is present in an amount of more than 36% to 95% by weight, preferably 50% to 85% by weight, based on the total weight of the solvent-based thermally activated adhesive composition (A). After drying, the thermally activated adhesive film contains less than 2.0% by weight, preferably less than 0.5% by weight, and more preferably less than 0.1% by weight, of at least one organic solvent, based on the total weight of the thermally activated adhesive film.

[0075] According to the present invention, the solvent-based thermally activated adhesive composition (A) may optionally contain or omit at least one component selected from pigments such as silane and carbon black, defoamers, smoothing agents (or leveling agents), stabilizers (antioxidants, UV stabilizers, heat stabilizers), catalysts, dyes, and mixtures thereof, provided that the advantageous properties of the solvent-based thermally activated adhesive composition (A) according to the present invention are not altered.

[0076] According to the present invention, the solvent-based thermally activated adhesive composition (A) may further contain 1 to 10% by weight of at least one of the optional additives specified above.

[0077] In a particularly preferred embodiment, the total weight of the heat-activated adhesive film is based on the total weight of the heat-activated adhesive film; (A1) At least one thermoplastic polymer having a weight-average molecular weight (Mw) of less than 10,000 g / mol, in an amount of 1% to 95% by weight, preferably 10% to 40% by weight; (A2) At least one polyol having a weight-average molecular weight (Mw) of less than 10,000 g / mol, in an amount of 0.01% to 80% by weight, preferably 5% to 40% by weight. (A3) At least one polyisocyanate having at least two isocyanate groups and at least one uretdione group in one molecule, in an amount of 0.05% to 20% by weight, preferably 0.5% to 5% by weight, and (A4) At least one organic solvent in an amount of less than 2.0% by weight, preferably less than 0.5% by weight, and more preferably less than 0.1% by weight. Includes.

[0078] Dispersion composition (B) According to the present invention, a multilayer adhesive film includes a second layer disposed on the first main surface of the first layer. The second layer is derived from a dispersion composition (B) comprising at least one aqueous polyurethane dispersion (B1) and optionally a latent curing agent (B2). When peeled from a substrate, a single-layer adhesive film derived from a solvent-based thermoactive adhesive composition (A) typically breaks multiple times, resulting in inefficient reworkability. The second layer derived from the dispersion composition (B) is highly durable and provides a reliable support for the first layer, thus the multilayer adhesive film not only achieves excellent reworkability but also improves the impact resistance of the multilayer adhesive film when cured at low temperatures (not exceeding 90°C).

[0079] In some embodiments, the second layer derived from the dispersion composition (B) is composed of at least one aqueous polyurethane dispersion (B1), thereby making component (B) a non-reactive polyurethane dispersion adhesive.

[0080] In some embodiments, the aqueous polyurethane dispersion (B1) used in the present invention has a solid content of less than 50%, preferably 40% or less.

[0081] In some embodiments, the aqueous polyurethane dispersion (B1) used in the present invention has a polyurethane polymer with a weight-average molecular weight (Mw) of 50,000 g / mol to 80,000 g / mol.

[0082] Commercially available aqueous polyurethane dispersions (B1) include Adwel 1665A, Adwel 1676, Adwel 1663, Adwel 1630C from Wanhua Chemistry, ESACOTE PU 6419 and ESACOTEPU A32D from Lamberti, NH-102U from Sam Myung Bio Chem Co., Ltd, ESACOTEPU A32D from DSM, and DISPERCOLL U XP 2682, DISPERCOLL U XP 2612, DISPERCOLL U XP 2643, DISPERCOLL U XP 2849, DISPERCOLL U 53, and DISPERCOLL U 56 from COVESTRO.

[0083] The above-mentioned component (B2) can be used alone, but preferably in combination of two or more.

[0084] In other embodiments, the second layer is derived from a dispersion composition (B) comprising at least one aqueous polyurethane dispersion (B1) and a latent curing agent (B2), where component (B) becomes a latently reactive polyurethane dispersion adhesive upon heating.

[0085] Suitable latent curing agents (B2) include latently reactive solid isocyanates. Examples include aliphatic, cyclic aliphatic, heterocyclic, and aromatic polyisocyanates (e.g., methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and isophorone diisocyanate (IPDI)), preferably TDI.

[0086] The latent curing agent (B2) preferably includes groups selected from ethylenediamine, 1,3-propylenediamine, diethylenetriamine, triethylenetetramine, 2,5-dimethylpiperazine, 3,3'-dimethyl-4,4'-diaminodicyclohexyl, methane, methylnonane-diamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, diamino and triaminopolypropylene ethers, polyamidoamines, and combinations thereof.

[0087] The use of a suspension of latently reactive solid isocyanate is preferred. A preferred aqueous suspension of latently reactive solid isocyanate has a solid content of less than 50%. A desired aqueous suspension of latently reactive solid isocyanate has an NCO content of 5-15% based on test method M105-ISO 11909.

[0088] Useful aqueous suspensions of latently reactive solid isocyanates can be activated at 60°C to 80°C.

[0089] Commercially available latent hardening agents (B2) include CARMOT BL-1045, available from OSIC, and Thanecure® T9 SuperFine, available from TSE.

[0090] In a particularly preferred embodiment, the second layer is derived from a dispersion composition (B) comprising 80% to 100% by weight of an aqueous polyurethane dispersion (B1) and 0% to 20% by weight of a latent curing agent (B2).

[0091] Multilayer adhesive film According to the present invention, the multilayer adhesive film includes a first layer having a first main surface and a second main surface facing the first main surface, and a second layer disposed on the first main surface of the heat-activated adhesive film.

[0092] In some embodiments, at least one peelable liner is placed on the second main surface of the first layer, and at least one peelable liner is placed on the exposed surface of the second layer.

[0093] In some embodiments, the multilayer adhesive film further comprises a third layer of a heat-activated adhesive film in direct contact with a second main surface, the third layer being the same as or different from the second layer, and comprising at least one aqueous polyurethane dispersion and optionally a latent curing agent. Optionally, at least one peelable liner is provided on the exposed surface of the third layer and at least one peelable liner is provided on the exposed surface of the second layer.

[0094] The multilayer adhesive film has a total thickness in the range of 150 μm to 400 μm, preferably 200 μm to 300 μm.

[0095] According to the present invention, the multilayer adhesive film is characterized by being a self-supporting adhesive film. It can be cured at low temperatures, for example, not exceeding 90°C, preferably below 80°C, and exhibits excellent extrusion (or push-out) strength of at least 5 MPa, and excellent impact resistance of at least 0.5 J, preferably at least 0.8 J, based on the measurement methods described herein.

[0096] Manufacturing method According to a second aspect of the present invention, the present invention relates to a method for producing a multilayer adhesive film, comprising the following steps: (1) Applying (or coating) a solvent-based thermal adhesive composition (A) according to the present invention to a peelable liner, heating to a temperature of 40°C to 100°C until the solvent content is 5% by weight or less of the total weight of the solvent-based thermal adhesive composition, and then cooling to room temperature, thereby forming the first layer of a multilayer adhesive film; and, (2) Applying the dispersion composition (B) according to the present invention to the first main surface of a heat-activated adhesive film, heating to a temperature of 40°C to 100°C to dry the dispersion composition, and cooling to room temperature to form the second layer of the multilayer adhesive film.

[0097] In some embodiments, a multilayer adhesive film based on the above method further includes the following steps: (3) Remove the peelable liner from the second main surface of the heat-activated adhesive film, apply the dispersion composition (B) according to the present invention, heat to a temperature of 40°C to 100°C to dry the dispersion composition, and cool to room temperature to form the third layer of the multilayer adhesive film; and, (4) A step of applying a peelable liner to the exposed surfaces of the second and third layers as necessary.

[0098] During step (1), the solvent-based thermoactive adhesive composition (A) can be obtained by rapidly stirring a thermoplastic polymer (A1), polyol (A2), and optional components or additives that are soluble in an organic solvent (A4) under heating conditions, for example, at a temperature of 75°C or lower, preferably 65°C or lower, and then adding polyisocyanate (A3). In this case, polyisocyanate (A3) may be added at room temperature to obtain a homogeneous solvent-based thermoactive adhesive composition (A).

[0099] In step (2), the drying temperature is generally 40°C to 100°C, preferably 40°C to 60°C or lower. If the drying temperature is too high, it may affect the film formation of the dispersion composition (B); however, even if the drying temperature is as high as 100°C, the dispersion composition (B) contains sufficient moisture, and evaporation removes heat, so the actual temperature of the film does not become high enough to affect film formation. The drying time depends on the film thickness, the length of the drying tunnel, and the manufacturing capacity. In some embodiments, the second layer was dried at 80°C for 10 minutes and further showed an acceptable film formation state for use.

[0100] In step (3), the dispersion composition (B) may be the same as or different from the second layer and comprises at least one aqueous polyurethane dispersion and optionally a latent curing agent according to the present invention. In some embodiments, the peelable liner used in the above steps has a non-adhesive surface to which the composition is applied. For example, the solvent-based thermoactive adhesive composition (A) is applied as a uniform layer to a non-adhesive surface of the peelable liner, such as a silicone-treated surface. Application can be done using a film applicator or a bar coater. A two-layer adhesive film is favorably obtained after steps (1) and (2). A three-layer adhesive film is favorably obtained after steps (1) to (4).

[0101] If necessary, a multilayer adhesive film according to the present invention can be manufactured by the following steps: (1) Applying a solvent-based thermal adhesive composition (A) according to the present invention to a peelable liner, heating it to a temperature of 40°C to 100°C until the solvent content is 5% by weight or less of the total weight of the solvent-based thermal adhesive composition, and then cooling it to room temperature, thereby forming the first layer of a multilayer adhesive film; (2) Applying the dispersion composition (B) according to the present invention to a peelable liner, heating to a temperature of 40°C to 100°C to dry the dispersion composition, and cooling to room temperature to form the second layer of the multilayer adhesive film; and, (3) A step of bonding the second layer of multilayer adhesive film onto the first layer of multilayer adhesive film at a temperature of 40°C to 80°C and under a pressure of 1 to 5 bar.

[0102] Furthermore, the above manufacturing method may include the following steps: (4) Remove the peelable liner of the first layer of the multilayer adhesive film, apply the dispersion composition (B) according to the present invention, heat to a temperature of 40°C to 100°C, and cool to room temperature, thereby forming the third layer of the multilayer adhesive film; and, (5) Step of applying a peelable liner to the exposed surface of the third layer.

[0103] The equipment used for mixing, stirring, and dispersion is not particularly limited during the process. Automatic mortars equipped with stirrers and heaters, Henschel mixers, three-roll mills, ball mills, planetary mixers, bead mills, etc., can be used. Alternatively, a suitable combination of these devices may be used. The method for preparing composition (A) or (B) is not particularly limited, as long as the above components are uniformly mixed.

[0104] During this process, composition (A) or (B) can be applied using any suitable coating method, including, for example, automatic fine-line dispensing, jet dispensing, slot die coating, roll coating, gravure coating, transfer coating, pattern coating, screen printing, spray coating, filament coating, extrusion, air knife, trailing blade, brushing, dipping, doctor blade, offset gravure coating, rotary gravure coating, and combinations thereof. Composition (A) or (B) can be applied as a single layer or multiple layers, as a continuous or discontinuous coating, or in combinations thereof.

[0105] Articles and Use According to a third aspect, the present invention provides: first base material, Second substrate, and A multilayer adhesive film according to the present invention, placed between the first substrate and the second substrate. It is an article that possesses the following properties.

[0106] In another embodiment, the article comprises a first substrate, a second substrate, and a multilayer adhesive film of the present invention located between the two substrates and in direct contact with the two substrates.

[0107] The first and second substrates may consist of a single material and a single layer, or multiple (or more) layers of the same or different materials. The layers may be continuous or discontinuous.

[0108] The base materials of the articles described herein can have a variety of properties, including rigidity (e.g., rigid base materials, i.e., base materials that cannot be bent even with both hands, or that break when attempted to bend with both hands), flexibility (e.g., flexible base materials, i.e., base materials that can be bent with a force not exceeding the force of both hands), porosity, conductivity, non-conductivity, and combinations thereof.

[0109] The base material of the article may take a variety of forms, including, for example, fibers, threads, yarns, fabrics, nonwovens, films (e.g., polymer films, metallized polymer films, continuous films, discontinuous films, and combinations thereof), foils (e.g., metallic foils), sheets (e.g., metallic sheets, polymer sheets, continuous sheets, discontinuous sheets, and combinations thereof), and combinations thereof.

[0110] In a preferred embodiment, at least one substrate can be selected from anodized aluminum, metal calcined paste, conductive metal oxides such as tin, molybdenum, silver, indium tin oxide (ITO), fluorine-doped tin oxide, and aluminum-doped zinc oxide, glass such as ink-coated glass and plain glass, and resins such as polycarbonate, polybutylene, terephthalate, and polyamide. Furthermore, suitable metals include copper, gold, palladium, platinum, aluminum, indium, silver-plated copper, silver-plated aluminum, tin, and tin-plated copper. Preferably, both substrates are also selected from any of the above materials.

[0111] According to another embodiment of this preferred embodiment, an article can be made multilayered by laminating more substrates using a multilayer adhesive film according to the present invention.

[0112] In one embodiment, an article having a first substrate and a second substrate is manufactured by contacting the first substrate with the first main surface of either of the multilayer adhesive films, after removing the peelable liner if present, and contacting the second substrate with the second main surface of the film, after removing the peelable liner if present, so that the second main surface of the film is in direct contact with the second substrate, and curing the film by heating it to a temperature of less than 90°C, preferably 60°C to 80°C, and optionally at a pressure of 0.5 to 6 bar, so that the two substrates adhere to each other.

[0113] In another embodiment, an article having a first substrate and a second substrate is prepared by contacting the first substrate with the first principal surface of either of the multilayer adhesive films and heating to a temperature of 40°C to 60°C before or after applying the adhesive film to the first substrate to form a pre-bonding so that it can be stored and transported to another location. During pre-bonding, the solvent-based thermoactive adhesive composition (A) has not yet begun to cure or crosslink, but partial aggregation may occur. Once prepared, the pre-bonding is used in the manufacture of the final article, by contacting the second substrate with the second principal surface of the film so that the second principal surface of the film is in direct contact with the second substrate to form the article, and heating the article to a temperature of less than 90°C, preferably 60°C to 80°C, and applying pressure as necessary (e.g., film or bladder press, heated platen) to fully cure the multilayer adhesive film so that the two substrates adhere to each other via the adhesive film.

[0114] As will be understood, the time and temperature curing profiles for multilayer adhesive films according to the present invention may vary, and various multilayer adhesive films can be designed to provide curing profiles suitable for specific industrial manufacturing processes.

[0115] use A fourth aspect of the invention is the use of multilayer adhesive films or articles based on the present invention in the manufacture of automotive parts, truck bed covers, laminated textiles, assembled products, and electronic devices.

[0116] Multilayer adhesive films are useful in a variety of applications, such as temporary bonding of at least one substrate, permanent bonding of at least one or two substrates, protection of substrates, suppression or prevention of movement of a first substrate relative to a second substrate, and combinations thereof. Multilayer adhesive films are also useful in a variety of processes, including manufacturing processes (e.g., bonding two parts of an article, or holding two parts together by a relationship in which one part is fixed to the other during the manufacturing process), shipping processes, stacking technologies, and any combination thereof.

[0117] Multilayer adhesive films can be used in the manufacture of a wide variety of items, including automotive parts, truck bed covers, laminated textiles, various assembled products, and electronic equipment.

[0118] The aforementioned appropriate electronic devices include, but are not limited to, wearable electronic devices (e.g., watches and glasses), portable electronic devices (e.g., telephones (e.g., mobile phones and smartphones), cameras, tablets, e-readers, monitors (e.g., monitors used in hospitals and by medical professionals, athletes and individuals), clocks, calculators, mice, touchpads, and joysticks), computers (e.g., desktop and laptop computers), computer monitors, televisions, media players, or other electronic devices. [Examples]

[0119] The following examples are intended to help those skilled in the art to better understand and implement the present invention. The scope of the present invention is not limited by the examples but is defined in the appended claims. Unless otherwise specified, all parts and percentages are based on weight.

[0120] raw materials: WH6190A is a thermoplastic polyurethane polymer with a weight-average molecular weight (Mw) of 50,000 g / mol and an optimal activation temperature of 55°C, and is available from Wanhua Chemical.

[0121] FZPE-A03130 is an amorphous polyester polyol with a weight-average molecular weight (Mw) of 3000 g / mol and is available from GUANGZHOU FTRT CHEMICAL CO., LTD.

[0122] Silquest A-189 is a silane and is available from Momentive.

[0123] Carbon black is a pigment and is available from Cabot.

[0124] BYK-141 is an antifoaming agent and is available from BYK.

[0125] BYK-3550 is a smoothing agent (or leveling agent) and is available from BYK.

[0126] Addolink™ TT is a toluene diisocyanate dimer and is available from Rhein Chemie.

[0127] MEK is a methyl ethyl ketone with a boiling point of 70-80°C and is available from Sinopharm.

[0128] Adwel 1665A is an aqueous polyurethane dispersion having a solid content of 50% and a polyurethane polymer with a weight-average molecular weight (Mw) of 50,000 g / mol to 80,000 g / mol, and is available from Wanhua Chemical.

[0129] Adwel 1676 is an aqueous polyurethane dispersion having a solid content of 50% and a polyurethane polymer with a weight-average molecular weight (Mw) of 50,000 g / mol to 80,000 g / mol, and is available from Wanhua Chemical.

[0130] CARMOT BL-1045 is a dispersion containing a 40% TDI dimer with an NCO content of 7% to 8%, and is available from OSIC.

[0131] METOLAT 348 is a smoothing agent (or leveling agent) and is available from MUNZING.

[0132] Carboset® 527 is a thermoplastic acrylic resin available from Lubrizol.

[0133] AT501 is a thermoplastic epoxidized elastomer and is available from Daicel Corporation.

[0134] Preparation of solvent-based thermally activated adhesive composition (A) and production of the first layer of a multilayer adhesive film The solvent-based thermally activated adhesive composition (A) according to the present invention was prepared by the following steps: (1) Add 25g of WH6190A (A1), 5g of FZPE-A03130 (A2), 1g of Silkest A-189, 1g of carbon black, 1.5g of BYK-141, and 1.5g of BYK-3550 to 85g of MEK (A4), and stir slowly for about 10 hours at a temperature below 65°C until the polymer dissolves; and, (2) If dissolved, the solution is cooled to room temperature. Next, 1.2 g of Addolink® TT (A3) is added, then the mixture is transferred to a suitable container and placed under rapid stirring conditions using a high-speed mixer at 2000 revolutions per minute for 1 minute twice to obtain the solvent-based adhesive composition (A) ("F11").

[0135] The F11 solvent-based adhesive composition was applied onto a peelable liner using a 500 μm film applicator and dried at 40°C for 20 minutes to evaporate MEK(A4) until the MEK content was 5% or less, thereby obtaining the first layer of a multilayer adhesive film according to the present invention.

[0136] Preparation of dispersion composition (B) and production of the second / third layer of the multilayer adhesive film Based on the present invention, two dispersion compositions (B), F21 and F22 were prepared by mixing the components shown in Table 1 at room temperature for about 2 hours while slowly stirring at a speed of 400 to 800 rpm.

[0137] The information shown in Table 1 is expressed in grams (g).

[0138] [Table 1]

[0139] The dispersed compositions, F21 and F22, were applied to a peelable liner or to the first main surface of the heat-activated adhesive film obtained above, respectively. The dispersed compositions were dried by heating in an oven at 45°C for 10 minutes, and then cooled to room temperature to form the second / third layers of the multilayer adhesive film.

[0140] Comparative Examples 1-3 Comparative Example 1 was a single layer of F11 heat-activated adhesive film.

[0141] Comparative Examples 2 and 3 are two-layer adhesive films containing a heat-activated adhesive film of F11 as the first layer, while the second layer was obtained from compositions of CF1 and CF2 manufactured as described below.

[0142] A thermoplastic polymer and additives different from those of the present invention are added to MEK as shown in Table 2, and the mixture is slowly stirred for about 10 hours under a temperature of less than 65°C until the polymer dissolves to obtain dispersion compositions of "CF1" and "CF2".

[0143] The information shown in Table 2 is expressed in grams (g).

[0144] [Table 2]

[0145] In Comparative Examples 2 and 3, the CF1 and CF2 compositions were applied to the first main surface of the F11 heat-activated adhesive film, the dispersions of CF1 and CF2 were dried by heating at a temperature of 40 to 100°C, and then cooled to room temperature to form the two-layer adhesive films of the comparative examples.

[0146] Examples 1-3 of the present invention Each multilayer adhesive film in the embodiment of the present invention was manufactured by applying a dispersion of F21 / F22 to the first layer surface of a heat-activated adhesive film F11 at room temperature, and placing the coated film in an oven at 45°C for 10 minutes to evaporate the moisture and form a second layer. After drying, the two-layer adhesive film was kept at room temperature. The exposed surface of the second layer of the two-layer adhesive film was covered with a peelable liner.

[0147] In Example 3 of the present invention, the peelable liner attached to the exposed surface of the second layer was removed, the F22 dispersion composition was applied thereto, and the film was placed in an oven at 45°C for 10 minutes to evaporate the moisture. After drying, the formed three-layer adhesive film was kept at room temperature for 2 days. The exposed surface of the third layer of the three-layer adhesive film was covered with a peelable liner.

[0148] The composition of each layer, the thickness ratio, and the total thickness of the adhesive film for the examples and comparative examples are shown in Table 3.

[0149] Test method Push-out strength Sample pre-lamination: The multilayer adhesive films of the present invention and comparative examples were each cut into 25 × 25 mm test specimens and then pre-bonded on a heated platform using a test coupon. The test coupon consisted of an anodized aluminum block and a separating window element made of another anodized aluminum block. The adhesive film was uniformly applied to the surface of the aforementioned ink-coated glass block on the platform under a temperature of 50°C. The adhesive film was pressed down with a 500 g weight for 30 seconds. The liner was then removed from the adhesive film. 225 mm 2 An ink-coated glass block was pressed onto a window-shaped component with a bonding area of ​​60°C and a pressure of 2 kg for an additional 30 seconds. This preliminary bonding step helps activate the aggregation of the thermoplastic polymer and form initial adhesion.

[0150] Final bonding / thermosetting treatment: The specimens obtained as described above were moved to a thermocompressor for final bonding / thermocuring treatment at 80°C. The thermocompressor had flat metal thermoblocks on the top and bottom (both metal blocks were pre-set to 80°C). Final bonding was performed by heating at 80°C for 10 minutes under a pressure of approximately 2 bar (typically 3 to 6 specimens were heat-compressed simultaneously at one time), during which time the adhesive film was crosslinked and cured. The specimens were then moved from the thermocompressor to room temperature and subsequently compressed with a weight of 2 kg for 6 minutes.

[0151] Sample testing Extrusion (or push-out) strength measurements were performed using a universal testing machine with a punch at 23±2°C and 50±5% relative humidity. The punch applied compressive force to the metal block of the test coupon at an extrusion (or push-out) speed of 10 mm / min until the assembly could no longer support the load. The maximum load was recorded in Table 3, and the extrusion (or push-out) strength was calculated as total load / bonding area.

[0152] Adhesive films exhibiting an extrusion (or push-out) strength of at least 5 MPa are acceptable.

[0153] Impact resistance The impact resistance of the samples was evaluated using DuPont impact energy with a lap shear assembly.

[0154] The sample preparation, pre-bonding, and final curing conditions are the same as those for the extrusion (or push-out) strength test described above.

[0155] Sample testing: As an initial condition, a 50g weight was dropped onto the sample from a height of 1m at a speed of 4.43m / s. If the substrate did not detach from the polycarbonate substrate three times, the weight was dropped again from a height 2cm higher than the previous drop. The DuPont impact energy was calculated using the following formula: E = m * g * h * 0.01

[0156] Here, E is the impact energy (J), m is the weight when the substrates separate from each other (g), h is the height from which the weights were dropped when the substrates separate from each other (m), and g is 9.8 m / s². 2 The measurement results are shown in Table 3. A DuPont impact energy value of at least 0.5 J, preferably at least 0.8 J, indicates acceptable impact resistance.

[0157] Reworkability test The reworkability of the samples was evaluated using the following method.

[0158] Sample manufacturing An assembled structure having a first substrate of anodized aluminum and a second substrate of ink glass was manufactured by, after removing the liner if present, bringing the second main surface of the first layer or the exposed surface of the third layer of the multilayer adhesive film in the embodiment of the present invention, or the second main surface of the first layer or the exposed surface of the third layer of the single-layer or multilayer adhesive film in the comparative example, into contact with the first substrate, and, after removing the liner if present, bringing the exposed surface of the second layer of the multilayer adhesive film into contact with the second substrate, so that the second layer of the film is in direct contact with the second substrate, thereby forming the assembled structure, and curing the adhesive film by applying heat at a temperature of 80°C and a pressure of 2 bar so that the two substrates are bonded to each other.

[0159] Sample testing At room temperature, the first substrate was first peeled from the assembled structure, then the adhesive film was peeled from the second substrate using a palette knife, and the film was continued to be peeled by hand from the surface of the second substrate at a controlled angle of 30-45°. The condition of the adhesive film and the reworkability level were evaluated and are shown in Table 3. A reworkability level of 5 indicates excellent reworkability.

[0160] [Table 3] [Table 4]

[0161] While several preferred embodiments have been described, many modifications and variations are possible in light of the teachings above. Therefore, it should be understood that the present invention can be implemented in ways different from those specifically described without departing from the scope of the appended claims.

Claims

1. A first layer having a first main surface and a second main surface opposite the first main surface, and The second layer is placed on the first main surface of the heat-activated adhesive film. A multilayer adhesive film including, Here, the first layer is a heat-activated adhesive film obtained by drying a solvent-based heat-activated adhesive composition (A) until the solvent content is 5% by weight or less of the total weight of the solvent-based heat-activated adhesive composition, wherein the solvent-based heat-activated adhesive composition (A) comprises at least one thermoplastic polymer (A1), at least one polyol (A2), at least one polyisocyanate (A3) having at least two isocyanate groups and at least one uretdione group in one molecule, and an organic solvent (A4). The second layer is derived from a dispersion composition (B) comprising at least one aqueous polyurethane dispersion (B1) and optionally a latent curing agent (B2). Multilayer adhesive film.

2. The multilayer adhesive film according to claim 1, wherein the thermoplastic polymer (A1) has an optimal activation temperature of 100°C or less, preferably less than 85°C, preferably between 30°C and less than 80°C, more preferably between 30°C and less than 70°C, and even more preferably between 30°C and less than 60°C.

3. The multilayer adhesive film according to claim 1 or 2, wherein the thermoplastic polymer (A1) has a weight-average molecular weight (Mw) of 10,000 g / mol or more, preferably 10,000 to 200,000 g / mol, preferably 10,000 to 150,000 g / mol, and more preferably 20,000 to 100,000 g / mol.

4. The multilayer adhesive film according to any one of claims 1 to 3, wherein the polyol (A2) is a polyester polyol having a weight-average molecular weight (Mw) of less than 10,000 g / mol.

5. The heat-activated adhesive composition (A) is a multilayer adhesive film according to any one of claims 1 to 4, wherein the molar ratio of NCO / OH is 0.1 to 8:

1.

6. The water-based polyurethane dispersion (B1) has a solid content of at least 40% to 70%, preferably 45% to 60%, according to any one of claims 1 to 5.

7. The water-based polyurethane dispersion (B1) has a weight-average molecular weight (Mw) of 50,000 g / mol to 80,000 g / mol, as described in claim 8, for the multilayer adhesive film.

8. The multilayer adhesive film according to any one of claims 1 to 7, wherein the latent curing agent (B2) is an aqueous suspension of a potentially reactive solid isocyanate.

9. The multilayer adhesive film according to any one of claims 1 to 8, further comprising a third layer in direct contact with the second main surface of a heat-activated adhesive film, wherein the third layer is identical or different from the second layer and comprises at least one aqueous polyurethane dispersion and optionally a latent curing agent. If necessary, at least one peelable liner positioned on the exposed surface of the third layer, and at least one peelable liner positioned on the exposed surface of the second layer.

10. The multilayer adhesive film according to any one of claims 1 to 9, wherein the multilayer adhesive film has a total thickness in the range of 150 μm to 400 μm, preferably 200 μm to 300 μm.

11. (1) Applying a solvent-based thermal adhesive composition (A) according to any one of claims 1 to 10 to a peelable liner, heating to a temperature of 40°C to 100°C until the solvent content is 5% by weight or less of the total weight of the solvent-based thermal adhesive composition, and then cooling to room temperature, thereby forming the first layer of a multilayer adhesive film; and, (2) The step of applying the dispersion composition (B) according to any one of claims 1 to 10 to the first main surface of a heat-activated adhesive film, heating to a temperature of 40°C to 100°C to dry the dispersion composition, and cooling to room temperature to form the second layer of the multilayer adhesive film. A method for manufacturing a multilayer adhesive film, including [the specified element].

12. (3) Remove the peelable liner from the second main surface of the heat-activated adhesive film, apply the dispersion composition (B) according to any one of claims 1 to 10, heat to a temperature of 40°C to 100°C to dry the dispersion composition, and cool to room temperature to form the third layer of the multilayer adhesive film; and, (4) Step of applying a peelable liner to the exposed surfaces of the second and third layers as necessary. A method for producing a multilayer adhesive film according to claim 12, further comprising:

13. (1) Applying a solvent-based thermal adhesive composition (A) according to any one of claims 1 to 10 to a peelable liner, heating to a temperature of 40°C to 100°C until the solvent content is 5% by weight or less of the total weight of the solvent-based thermal adhesive composition, and then cooling to room temperature, thereby forming the first layer of a multilayer adhesive film; (2) Applying the dispersion composition (B) according to any one of claims 1 to 10 to a peelable liner, heating to a temperature of 40°C to 100°C to dry the dispersion composition, and cooling to room temperature to form a second layer of a multilayer adhesive film; and (3) Laminating a second layer of multilayer adhesive film onto the first layer of multilayer adhesive film at a temperature of 40°C to 80°C and a pressure of 1 to 5 bar. A method for manufacturing a multilayer adhesive film, including [the specified element].

14. first base material, Second substrate, and A multilayer adhesive film according to any one of claims 1 to 10, disposed between a first substrate and a second substrate. A bound article.

15. Use of the multilayer adhesive film according to any one of claims 1 to 10, or the article according to claim 14, in the manufacture of automotive parts, truck bed covers, laminated textiles, assembled products, and electronic equipment.

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