Adhesive body and method for producing same

Abstract

Disclosed is an adhesive body. The adhesive body comprises a first substrate, a second substrate, and an adhesive layer that bonds the first substrate and the second substrate to each other. The haze of the first substrate and the second substrate is 5% or more. The adhesive layer contains a cured product of an adhesive composition containing: an organoborane complex; a compound having a radically polymerizable group; and a thermal acid generator.

Description

Adhesive body and its manufacturing method

[0001] The present disclosure relates to adhesive bodies and methods for making the same.

[0002] Two-component adhesive compositions containing organoborane complexes are known as adhesives for bonding plastic substrates such as polyethylene and polypropylene (see, for example, Patent Document 1). The organoborane complexes are decomplexed by mixing with a decomplexing agent to give organoboranes. The organoboranes act as initiators that generate radicals by reacting with oxygen. The borinic acid radicals generated here act to generate dormant species in atom transfer radical polymerization (ATRP), which sustains propagation reactions, including surface grafting, while suppressing chain transfer or termination reactions of compounds having radically polymerizable groups.

[0003] Special Publication No. 2005-514489

[0004]

[0005] Meanwhile, there is also a demand for one-component adhesive compositions containing organoborane complexes. However, in one-component adhesive compositions, after a first component (main component) and a second component (initiator) are combined into one component, a reaction gradually progresses during storage at room temperature (25°C) or at low temperatures, resulting in a decrease in adhesive strength, an increase in viscosity, and other problems in workability, such as the inability to apply the composition.

[0005] An object of the present disclosure is to provide an adhesive body using an adhesive composition that can ensure a sufficient pot life (usable time) at room temperature and that can exhibit sufficient adhesive strength after curing, and a method for producing the same.

[0006] The inventors of the present disclosure conducted research to solve the above problems and found that by adding a thermal acid generator to an adhesive composition, it is possible to obtain an adhesive composition that can ensure a sufficient pot life (usable time) at room temperature and that can exhibit sufficient adhesive strength after curing.The inventors then completed the invention of the present disclosure by applying such an adhesive composition to the production of an adhered body.

[0007] The present disclosure provides the following bonded structure [1] and a method for manufacturing a bonded structure [2]. [1] A bonded structure comprising: a first substrate; a second substrate; and an adhesive layer that bonds the first substrate and the second substrate to each other, wherein the haze of the first substrate and the second substrate is 5% or more, and the adhesive layer contains a cured product of an adhesive composition that includes an organoborane complex, a compound having a radical polymerizable group, and a thermal acid generator. [2] A method for manufacturing a bonded structure according to [1], comprising the steps of bonding the first substrate and the second substrate together via the adhesive composition to obtain a laminate, and heating the laminate to obtain a bonded structure.

[0008] According to the present disclosure, there are provided an adhesive body using an adhesive composition that can ensure a sufficient pot life (usable time) at room temperature and that can exhibit sufficient adhesive strength after curing, and a method for producing the same.

[0009] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0010] The same applies to the numerical values ​​and ranges in the present disclosure, and do not limit the present disclosure. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0011] In this specification, (meth)acrylate means acrylate or the corresponding methacrylate. (Meth)acrylamide means acrylamide or the corresponding methacrylamide. The same applies to other similar expressions such as (meth)acryloyl group and (meth)acrylic copolymer. Furthermore, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0012] [Bonded structure and manufacturing method thereof] In one embodiment, the bonded structure includes a first substrate, a second substrate, and an adhesive layer that bonds the first substrate and the second substrate together. The adhesive layer contains a cured product of an adhesive composition.

[0013] The first substrate and the second substrate are substrates with low transparency. The haze (cloudiness) of the first substrate and the second substrate is 5% or more, and may be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more. The haze of the first substrate and the second substrate may be, for example, 100% or less. In this specification, haze refers to a value measured in accordance with the method specified in JIS K7136:2000. Haze can be measured, for example, in an environment of 25°C using a commercially available device such as NDH-5000 (product name, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0014] The total light transmittance of the first substrate and the second substrate may be, for example, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, or 50% or less. In this specification, total light transmittance refers to a value measured in accordance with the method specified in JIS K7361-1:1997. The total light transmittance can be measured, for example, in an environment of 25°C using a commercially available device such as NDH-5000 (product name, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0015] Examples of the first substrate and the second substrate include plastic substrates such as polypropylene (PP), polyamide (PA), polyphenylene sulfide (PPS), acrylonitrile butadiene styrene (ABS), polyether ether ketone (PEEK), polyamide imide (PAI), polyphenylene ether (PPE), and ethylene vinyl acetate (EVA), and metal substrates such as aluminum, steel, copper, and stainless steel.

[0016] The thickness of the first substrate and the second substrate is not particularly limited, but may be, for example, 0.1 to 10,000 mm.

[0017] The adhesive composition contains an organoborane complex, a compound having a radical polymerizable group (hereinafter sometimes referred to as a "polymerizable compound"), and a thermal acid generator. The adhesive composition is a thermosetting composition.

[0018] (Organoborane Complex) The organoborane complex refers to an organoborane-Lewis base complex formed by coordinating a Lewis base to an organoborane to form a complex. The organoborane-Lewis base complex can be a compound that reacts with an acid or an electrophilic cation generated from a thermal acid generator described below to give an organoborane. The organoborane undergoes radical cleavage in the presence of oxygen to generate a borinic acid radical or the like, and can therefore act as an initiator for living radical polymerization. The organoborane can be, for example, alkylborane (BR ３ , R: alkyl group). The Lewis base may be, for example, an amine. The amine may be, for example, a compound having multiple amino groups, or a compound having at least an amino group constituting the amine and a group (e.g., an alkoxy group) containing an atom capable of coordinating with boron (e.g., an oxygen atom) other than the nitrogen atom of the amino group. These compounds act as multidentate ligands for organoborane, and therefore can be referred to as multidentate amines.

[0019] The organoborane complex may be an alkylborane-amine complex or an alkylborane-multidentate amine complex. Examples of organoborane complexes include triethylborane-1,3-diaminopropane complex, triethylborane-diethylenetriamine complex, tri-n-butylborane-3-methoxy-1-propylamine complex, tri-n-butylborane-1,3-diaminopropane complex, triisobutylborane-1,3-diaminopropane complex, triethylborane-1,6-diaminohexane complex, triisobutylborane-1,3-diaminopropane complex, and triisobutylborane-1,6-diaminohexane complex. These may be used alone or in combination of two or more. Among these, the organoborane complex may be triethylborane-1,3-diaminopropane complex or tri-n-butylborane-3-methoxy-1-propylamine complex. The organoborane complex may be a commercially available product or a synthesized product.

[0020] The content of the organoborane complex may be 0.01 mass% or more, 0.05 mass% or more, 0.1 mass% or more, or 0.2 mass% or more, based on the total amount of the adhesive composition, from the viewpoint of adhesive strength development. The content of the organoborane complex may be 10 mass% or less, 5 mass% or less, 3 mass% or less, or 1 mass% or less, based on the total amount of the adhesive composition, from the viewpoint of toughness of the adhesive layer.

[0021] The content of the organoborane complex may be 0.01 mol% or more, 0.05 mol% or more, 0.1 mol% or more, or 0.5 mol% or more, based on the total amount of the polymerizable compounds, from the viewpoint of adhesive strength development. The content of the organoborane complex may be 10 mol% or less, 5 mol% or less, 2 mol% or less, or 1 mol% or less, based on the total amount of the compounds having a radical polymerizable group, from the viewpoint of toughness of the adhesive layer.

[0022] (Compound Having a Radically Polymerizable Group (Polymerizable Compound)) The polymerizable compound is a compound having a polymerizable group that reacts with a radical. Examples of the radically polymerizable group include a (meth)acryloyl group, a vinyl group, an allyl group, a styryl group, an alkenyl group, an alkenylene group, and a maleimide group.

[0023] The polymerizable compound may contain, for example, a compound having a (meth)acryloyl group. Examples of the compound having a (meth)acryloyl group include monofunctional (meth)acrylates having one (meth)acryloyl group, polyfunctional (meth)acrylates having two or more (meth)acryloyl groups, and (meth)acrylamide derivatives. Among these, the compound having a (meth)acryloyl group may be a monofunctional (meth)acrylate having one (meth)acryloyl group.

[0024] Examples of monofunctional (meth)acrylates include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate (n-lauryl (meth)acrylate), alkyl (meth)acrylates having an alkyl group such as isomyristyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl acrylate; alkenyl (meth)acrylates having an alkenyl group such as 3-butenyl (meth)acrylate; (meth)acrylates having an aromatic group such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; methoxytetraethylene glycol (meth)acrylate, methoxyhexaethylene glycol (meth)acrylate, and methoxyoctaethylene glycol Alkoxypolyalkylene glycol (meth)acrylates such as methyl acrylate, methoxynonaethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxyheptapropylene glycol (meth)acrylate, ethoxytetraethylene glycol (meth)acrylate, butoxyethylene glycol (meth)acrylate, and butoxydiethylene glycol (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (Meth)acrylates having an alicyclic group such as (meth)acrylate; (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; (meth)acrylates having an amino group such as N,N-dimethylaminoethyl (meth)acrylate; (meth)acrylates having an isocyanate group such as 2-(2-methacryloyloxyethyloxy)ethyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate;Examples of the polyalkylene glycol mono(meth)acrylate include tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, octapropylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, tripropylene glycol mono(meth)acrylate, and octapropylene glycol mono(meth)acrylate; and (meth)acrylates having a siloxane skeleton.

[0025] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, Polyethylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decamethylpropanediol di(meth)acrylate Aliphatic (meth)acrylates such as 2-methyl-1,3-propanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate; ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, ethoxylated propoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, and propoxylated bisphenol F di(meth)acrylate. aromatic (meth)acrylates such as (meth)acrylate, ethoxylated propoxylated bisphenol F type di(meth)acrylate, ethoxylated fluorene type di(meth)acrylate, propoxylated fluorene type di(meth)acrylate, and ethoxylated propoxylated fluorene type di(meth)acrylate; and aromatic epoxy (meth)acrylates such as bisphenol type epoxy (meth)acrylate, phenol novolac type epoxy (meth)acrylate, and cresol novolac type epoxy (meth)acrylate.

[0026] Examples of the (meth)acrylamide derivatives include N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and 4-(meth)acryloylmorpholine.

[0027] The polymerizable compound may contain, in addition to a compound having a (meth)acryloyl group, a copolymerizable compound copolymerizable with the compound having a (meth)acryloyl group, such as styrene, 4-methylstyrene, vinylpyridine, vinylpyrrolidone, vinyl acetate, cyclohexylmaleimide, and phenylmaleimide, other than a (meth)acryloyl group.

[0028] The content of the polymerizable compound may be 40% by mass or more, 50% by mass or more, 60% by mass or more, or 65% by mass or more, based on the total amount of the adhesive composition, from the viewpoint of improving the toughness and adhesive strength of the adhesive layer. The content of the polymerizable compound may be 99% by mass or less, 98% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less, based on the total amount of the adhesive composition, from the viewpoint of suppressing sagging of the applied adhesive composition and suppressing a decrease in the toughness of the adhesive layer.

[0029] (Thermal Acid Generator) A thermal acid generator is a compound that generates an acid or electrophilic cations upon heating. By including a thermal acid generator in the adhesive composition, a sufficient pot life (working time) can be ensured at room temperature, and sufficient adhesive strength can be achieved after curing. The reason for this effect is not entirely clear, but the inventors believe it to be as follows: An organoborane complex (organoborane-Lewis base complex) reacts with an acid, an electrophilic cation, or the like, causing the Lewis base in the organoborane complex to dissociate and generate an organoborane. Although a thermal acid generator generates an acid or electrophilic cations upon heating, it is difficult to generate an acid or electrophilic cations near room temperature before heating. Therefore, it is believed that a sufficient pot life (working time) can be ensured near room temperature. On the other hand, after heating, the presence of an acid or electrophilic cation in the adhesive composition is presumed to generate an organoborane that can act as an initiator for living radical polymerization, allowing the curing reaction to proceed sufficiently and enabling sufficient adhesive strength to be achieved after curing.

[0030] The thermal acid generator may be a salt compound composed of a cation and an anion. Examples of the thermal acid generator include BF ４ － , B.R. ａ ４ － (R ａ represents a phenyl group in which a hydrogen atom is substituted with two or more fluorine atoms or two or more trifluoromethyl groups.), PF ６ － , P.F. ｎ (R ｂ ) ６－ｎ － (R ｂ represents an alkyl group in which a hydrogen atom is substituted with two or more fluorine atoms, and n represents 1 to 5.), SbF ６ － , AsF ６ － Examples include onium salts having anions such as R ｂ The number of carbon atoms in the alkyl group represented by R may be, for example, 1 to 8, 1 to 4, or 1 to 2. ｂExamples of the alkyl group represented by the formula (I) include a trifluoromethyl group and a pentafluoroethyl group. n is 1 to 5, 2 to 4, or 2 to 3. PF ｎ (R ｂ ) ６－ｎ － For example, PF ３ (C ２ F ５ ) ３ － Examples of onium salts include sulfonium salts, phosphonium salts, ammonium salts (quaternary ammonium salts, anilinium salts), diazonium salts, iodonium salts, and pyridinium salts. The thermal acid generator may be, for example, a sulfonium salt or an ammonium salt.

[0031] Examples of the cation of the sulfonium salt include sulfonium salts having an aryl group, such as a 4-hydroxyphenyl-methyl-benzylsulfonium ion, a 4-hydroxyphenyl-methyl-(2-methylbenzyl)sulfonium ion, a 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium ion, and a p-methoxycarbonyloxyphenyl-benzyl-methylsulfonium ion.

[0032] Examples of cations of ammonium salts (quaternary ammonium salts, anilinium salts) include N-benzyl-N,N-dimethylanilinium ion, N-(4-nitrobenzyl)-N,N-dimethylanilinium ion, N-(4-methoxybenzyl)-N,N-dimethylanilinium ion, N-(α-phenylbenzyl)-N,N-dimethylanilinium ion, N-(α-methylbenzyl)-N,N-dimethylanilinium ion, N-(1-naphthylmethyl)-N,N-dimethylanilinium ion, and N-cinnamyl-N,N-dimethylanilinium ion.

[0033] In one embodiment, the thermal acid generator is, for example, SbF 2 from the viewpoint of improving adhesive strength. ６ －In one embodiment, from the viewpoints of environmental considerations and low-temperature curing properties, the thermal acid generator may be, for example, a salt compound having an anion containing boron as a constituent element, or a salt compound having an anion containing phosphorus as a constituent element.

[0034] The anion containing boron as a constituent element is BR ａ ４ － and more specifically, tetrakis(pentafluorophenyl)borate.

[0035] The anion containing phosphorus as a constituent element is PF ｎ (R ｂ ) ６－ｎ － More specifically, tris(pentafluoroethyl)trifluorophosphate (PF ３ (C ２ F ５ ) ３ － ) may be.

[0036] In one embodiment, the thermal acid generator is SbF ６ － In one embodiment, the thermal acid generator may be an ammonium salt having an anion containing boron as a constituent element, or a sulfonium salt having an anion containing phosphorus as a constituent element.

[0037] The content of the thermal acid generator may be 0.1 mass % or more, 0.3 mass % or more, 0.5 mass % or more, or 0.7 mass % or more, based on the total amount of the adhesive composition, from the viewpoint of adhesive strength development. The content of the thermal acid generator may be 10 mass % or less, 7 mass % or less, 5 mass % or less, or 3 mass % or less, based on the total amount of the adhesive composition, from the viewpoint of toughness of the adhesive layer.

[0038] The content of the thermal acid generator may be 0.01 mol % or more, 0.05 mol % or more, 0.1 mol % or more, or 0.5 mol % or more based on the total amount of the polymerizable compounds from the viewpoint of adhesive strength development, and may be 10 mol % or less, 5 mol % or less, 2 mol % or less, or 1 mol % or less based on the total amount of the polymerizable compounds from the viewpoint of toughness of the adhesive layer.

[0039] The molar ratio of the thermal acid generator to the organoborane complex (molar amount of thermal acid generator / molar amount of organoborane complex) may be, for example, 0.3 or more, 0.5 or more, or 0.8 or more. When the molar ratio is 1 or more, more sufficient adhesive strength tends to be obtained. The molar ratio of the thermal acid generator to the organoborane complex (molar amount of thermal acid generator / molar amount of organoborane complex) may be, for example, 50 or less, 30 or less, 10 or less, 7 or less, 5 or less, or 3 or less. The smaller the molar ratio, the more sufficient the working time from applying the adhesive composition to the substrates until bonding them tends to be secured.

[0040] (Polymerization Regulator) The adhesive composition may further contain at least one member selected from the group consisting of metal halide salts and compounds having a thiocarbonylthio structure, which can act as a polymerization regulator.

[0041] Examples of metal halide salts include copper(II) bromide, copper(II) chloride, iron(III) bromide, vanadium(III) bromide, chromium(III) bromide, ruthenium(III) bromide, copper(I) bromide, iron(II) bromide, manganese(II) bromide, cobalt(II) bromide, nickel(II) bromide, and palladium(II) bromide. These may be used alone or in combination of two or more. The metal halide salt may be, for example, copper(II) bromide.

[0042] The compound having a thiocarbonylthio structure can be used without any particular limitation as long as it has a thiocarbonylthio structure. For example, a chain transfer agent (RAFT agent) used in the field of RAFT polymerization (Reversible Addition / Fragmentation Chain Transfer) can be suitably used.

[0043] The content of the polymerization inhibitor may be 0.01% by mass or more, 0.02% by mass or more, or 0.03% by mass or more, based on the total amount of the adhesive composition, from the viewpoint of ensuring the working time from applying the adhesive composition to the substrates until bonding them and improving the adhesive strength. The content of the polymerization inhibitor may be 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less, based on the total amount of the adhesive composition.

[0044] The content of the polymerization inhibitor may be 0.01 mol% or more, 0.02 mol% or more, or 0.03 mol% or more, based on the total amount of the polymerizable compounds, from the viewpoint of ensuring the working time from applying the adhesive composition to the substrates until bonding them and improving the adhesive strength. The content of the polymerization inhibitor may be 5 mol% or less, 3 mol% or less, 1 mol% or less, 0.7 mol% or less, 0.5 mol% or less, or 0.2 mol% or less, based on the total amount of the polymerizable compounds.

[0045] (Stabilizer) The adhesive composition may further contain a compound represented by formula (1) that can act as a stabilizer for the organoborane complex. Note that the compound represented by formula (1) has a radical polymerizable group, and therefore also acts as the compound having the above-mentioned radical polymerizable group ((meth)acrylamide derivative). In this specification, the compound represented by formula (1) that serves as a stabilizer for the organoborane complex is not included in the compound having the above-mentioned radical polymerizable group (polymerizable compound), and is therefore excluded from the content of the polymerizable compound.

[0046]

[0047] R １ represents a hydrogen atom or a methyl group. １ may be a hydrogen atom.

[0048] R ２ and R ３each independently represents an alkylene group. The alkylene group may have 1 to 20, 1 to 10, 1 to 6, or 1 to 3 carbon atoms. The alkylene group may be either a linear alkylene group or a branched alkylene group. The linear alkylene group usually has 1 to 20 carbon atoms, and may have 1 to 10, 1 to 6, or 1 to 3 carbon atoms. The branched alkylene group usually has 3 to 20 carbon atoms, and may have 3 to 10 or 3 to 6 carbon atoms.

[0049] Examples of linear alkylene groups include methylene, ethylene, propylene, butylene, pentylene, and hexylene groups. Examples of branched alkylene groups include isopropylene, isobutylene, and dimethylpropylene groups. Among these, the alkylene group may be an ethylene group.

[0050] Some of the hydrogen atoms of the alkylene group may be substituted with a substituent. When some of the hydrogen atoms of the alkylene group are substituted with a substituent, the number of carbon atoms mentioned above includes the number of carbon atoms of the substituent.

[0051] Nitrogen atom, oxygen atom, R ２ , and R ３ The ring (heterocycle) composed of the following may be, for example, a morpholine ring.

[0052] Specific examples of the compound represented by formula (1) include 4-(meth)acryloylmorpholine, etc. The compound represented by formula (1) may be 4-(meth)acryloylmorpholine or 4-acryloylmorpholine (ACMO).

[0053] The stabilizer content may be 0.01 mass % or more, 0.05 mass % or more, 0.1 mass % or more, or 0.5 mass % or more, based on the total amount of the adhesive composition, from the viewpoint of the adhesive strength development in a short time of the adhesive composition. The stabilizer content may be 10 mass % or less, 7 mass % or less, 5 mass % or less, or 3 mass % or less, based on the total amount of the adhesive composition, from the viewpoint of the toughness of the adhesive layer.

[0054] The content of the stabilizer may be 0.01 mol % or more, 0.05 mol % or more, 0.1 mol % or more, or 0.5 mol % or more, based on the total amount of the polymerizable compounds, from the viewpoint of the adhesive composition's adhesive strength development in a short period of time. The content of the stabilizer may be 10 mol % or less, 7 mol % or less, 5 mol % or less, or 3 mol % or less, based on the total amount of the polymerizable compounds, from the viewpoint of the toughness of the adhesive layer.

[0055] (Filler) The adhesive composition may further contain a filler. The filler may be, for example, either an inorganic filler or an organic filler. Examples of inorganic fillers include inorganic fine particles such as silica, alumina, silica-alumina, titania, zirconia, magnesia, kaolin, talc, calcium carbonate, bentonite, mica, sericite, glass flakes, glass fiber, graphite, magnesium hydroxide, aluminum hydroxide, antimony trioxide, barium sulfate, zinc borate, wollastonite, xonotlite, and whiskers. When an inorganic filler is used as the filler, the inorganic filler may contain a silica filler.

[0056] Examples of organic fillers include organic fine particles such as silicone, acrylic silicone, acrylic rubber, MBS (methacrylate butadiene styrene), polyamide, and polyimide. These fillers (fine particles) may have a uniform structure or a core-shell structure. When an organic filler is used as the filler, the organic filler may contain acrylic core-shell particles.

[0057] The organic filler may contain an antioxidant in the organic filler. The content of the antioxidant in the organic filler may be, for example, 15,000 ppm by mass or less, 10,000 ppm by mass or less, 5,000 ppm by mass or less, or 3,000 ppm by mass or less.

[0058] The filler content may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 40% by mass or less, 30% by mass or less, or 30% by mass or less, based on the total amount of the adhesive composition.

[0059] (Plasticizer) The adhesive composition may further contain a plasticizer. Examples of the plasticizer include phthalate ester compounds, alkylsulfonate ester compounds, and adipic acid ester compounds.

[0060] The content of the plasticizer may be 0.1% by mass or more, 0.3% by mass or more, or 1.0% by mass or more, and may be 30% by mass or less, 20% by mass or less, or 10% by mass or less, based on the total amount of the adhesive composition.

[0061] In addition to the above components, the adhesive composition may further contain other components such as a crosslinking agent, an ultraviolet absorber, a dehydrating agent, a pigment, a dye, an antioxidant, an antioxidant, an antistatic agent, a flame retardant, an adhesion promoter, a dispersant, and a solvent.

[0062] The adhesive composition can be prepared by mixing the above components, such as the organoborane complex, the polymerizable compound, and the thermal acid generator. The temperature when mixing the above components may be, for example, 0 to 35°C or 10 to 25°C. The pot life (usable time) after mixing the above components may be, for example, more than 10 minutes, or may be 30 minutes or more, 60 minutes or more, 90 minutes or more, 120 minutes or more, 150 minutes or more, or 180 minutes or more.

[0063] The adhesive composition can also be prepared by preparing a composition set including a first liquid (main component) and a second liquid (initiator) and mixing the first liquid and the second liquid. In the composition set including the first liquid (main component) and the second liquid (initiator), the first liquid may contain a polymerizable compound and a thermal acid generator. The second liquid may contain an organoborane complex and may further contain a stabilizer. At least one of the first liquid and the second liquid may contain a polymerization inhibitor, a filler, a plasticizer, other components, etc. The temperature when mixing the first liquid and the second liquid and the pot life (usable time) may be the same as those described above.

[0064] The method for mixing each component, or the first and second liquids, is not particularly limited as long as the components are mixed. Examples of methods for mixing each component include manual mixing, manual mixing using a conventional caulking gun, and mixing using a mechanical rotary mixer, static mixer, or the like, in combination with a metering pump (e.g., a gear pump, a plunger pump, or the like) and a throttle valve for feeding the raw materials. When mixing the first and second liquids, the first and second liquids may be placed separately, fed from each to a nozzle, or the like, mixed inside the nozzle, and then discharged from the tip of the nozzle. This may be done using a dispenser, hand gun, or the like, which has a mechanism for continuously mixing the first and second liquids and applying the adhesive composition described below.

[0065] The prepared adhesive composition can be applied to a predetermined location to form an adhesive layer. The formed adhesive layer functions as an adhesive layer that bonds substrates together because the polymerizable compound gradually increases in molecular weight and hardens. The application to a predetermined location can be performed by a conventionally known method, such as a method using a dispenser.

[0066] The conditions for heating and curing the adhesive composition (adhesive layer) (heating temperature and maintenance time for maintaining the heating temperature) can be adjusted as desired, particularly by selecting the type of thermal acid generator. The heating temperature may be 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, or 60°C or higher. The heating temperature may be, for example, 180°C or lower, 150°C or lower, or 120°C or lower. The maintenance time may be 10 minutes or higher, 20 minutes or higher, or 30 minutes or higher. The maintenance time may be, for example, 300 minutes or lower, 150 minutes or lower, or 120 minutes or lower.

[0067] Examples of adhesive bodies include plastic laminate substrates, metal laminate substrates, electronic parts, semiconductor parts, display parts, and automobile parts.

[0068] A method for producing an adhesive structure according to one embodiment includes the steps of bonding a first substrate and a second substrate together via the adhesive composition to obtain a laminate, and heating the laminate to obtain an adhesive structure. The conditions for preparing the adhesive composition may be the same as those described above. The conditions for heating the laminate may be the same as those for heating and curing the adhesive composition (adhesive layer).

[0069] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0070] <Reference Examples 1 to 5> [Measurement of Haze and Total Light Transmittance] (Preparation of Substrates) Polypropylene (PP) substrate A (thickness: 2 mm) Polypropylene (PP) substrate B (thickness: 3 mm) Polyphenylene sulfide (PPS) substrate (thickness: 2 mm) Polyamide (PA) substrate (thickness: 2 mm) Polycarbonate (PC) substrate (thickness: 2 mm)

[0071] (Haze Measurement) Haze was measured using an NDH-5000 (product name, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the method specified in JIS K7136:2000. Specifically, each substrate was irradiated with light from a light source in an environment of 25°C, and the haze was determined. The results are shown in Table 1.

[0072] (Measurement of Total Light Transmittance) The total light transmittance was measured using an NDH-5000 (product name, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the method specified in JIS K7361-1:1997. Specifically, light from a light source was irradiated onto each substrate in an environment of 25°C, and the total light transmittance of light transmitted through the test piece was measured. The results are shown in Table 1.

[0073]

[0074] Preparation Examples 1 to 3 Preparation of Composition Set (Preparation of Raw Materials) Organoborane Complex TEB-DAP: triethylborane-1,3-diaminopropane complex (molecular weight: 172.1, Kishida Chemical Co., Ltd.) Compound having a radical polymerizable group (polymerizable compound) FA-513AS: dicyclopentanyl acrylate (molecular weight: 206.3, Resonaq Inc.) FA-310A: phenoxyethyl acrylate (molecular weight: 192.2, Resonaq Inc.) DMAA: N,N-dimethylacrylamide (molecular weight: 99.1, Fujifilm Wako Pure Chemical Industries, Ltd.) Thermal Acid Generator Thermal Acid Generator A: 4-hydroxyphenyl-methyl-(2-methylbenzyl)sulfonium hexafluoroantimonate (molecular weight: 481.1, Tokyo Chemical Industry Co., Ltd.) Thermal Acid Generator B: 4-hydroxyphenyl-methyl-benzylsulfonium Hexafluoroantimonate (molecular weight: 467.1, Tokyo Chemical Industry Co., Ltd.) Thermal acid generator C: 4-hydroxyphenyl-methyl-benzylsulfonium tris(pentafluoroethyl)trifluorophosphate (trade name: TA-100, molecular weight: 676.3, San-Apro Co., Ltd.) Polymerization inhibitor copper(II) bromide (molecular weight: 223.4, Fujifilm Wako Pure Chemical Industries, Ltd.) Stabilizer ACMO: 4-acryloylmorpholine (N,N-disubstituted acrylamide, molecular weight: 141.2, KJ Chemicals Co., Ltd.) Filler RY200S: fumed silica (hydrophobic fumed silica surface-treated with silicone oil, Nippon Aerosil Co., Ltd.) M210: acrylic core-shell particles (Kaneka Corporation, antioxidant not detected) Plasticizer PN-5090: adipic acid polyester (ADEKA Corporation)

[0075] (Preparation of First Liquid) The polymerizable compound, thermal acid generator, polymerization inhibitor, and filler were weighed into a plastic bottle in the types and proportions (unit: parts by mass) shown in Table 2, and mixed for 3 minutes at 2000 rpm using a planetary mixer (Thinky Corporation, Awatori Rentaro), and further degassed for 1 minute at 2000 rpm to prepare first liquids for Preparation Examples 1 to 3.

[0076] (Preparation of Second Liquid) The organoborane complex, stabilizer, filler, and plasticizer were weighed into a plastic bottle in the types and proportions (unit: parts by mass) shown in Table 2, and mixed for 15 minutes at 2000 rpm using a planetary mixer (Thinky Corporation, Awatori Rentaro), followed by degassing for 5 minutes at 2000 rpm to prepare second liquids for Preparation Examples 1 to 3.

[0077]

[0078] Examples 1 to 3 Preparation of adhesive composition and fabrication of laminate Two polypropylene substrates (PP substrate A, size: 100 mm × 25 mm, thickness: 2 mm, haze: 95.1%, total light transmittance: 80.3%) were prepared. A 0.5 mm thick spacer was placed on one of the polypropylene substrates so that the adhesive composition application area was 0.5 mm thick, 12.5 mm in the longitudinal direction of the polypropylene substrate, and 25 mm in the lateral direction of the polypropylene substrate. The adhesive compositions of Examples 1 to 3 were prepared by filling each of the first and second liquids into a manual dispenser and mixing the first and second liquids. The prepared adhesive composition was applied using the manual dispenser to the adhesive application area of ​​the polypropylene substrate where the spacer was placed, and the other polypropylene substrate was then attached to obtain multiple laminates of Production Examples 1 to 3.

[0079] [Measurement of adhesive strength by heating temperature] A plurality of laminates of each of Production Examples 1 to 3 were prepared. Each laminate was heated for 30 minutes at temperatures ranging from 40 to 110°C in 10°C increments, and the shear strength of the laminate after heating was measured. Shear strength was measured at room temperature (25°C) using an autograph (Shimadzu Corporation, model number: AGS X Plus, load cell: 50 kN) with a chuck distance of 100 mm and a tensile speed of 5 mm / min. The strength at break was measured, and the shear adhesive strength (MPa) was calculated from the measured value and the adhesive area. The results are shown in Table 3.

[0080]

[0081] As shown in Table 3, it was found that the adhesive compositions of Examples 1 to 3 exhibited sufficient adhesive strength when heated to a temperature of 60° C. or higher.

[0082] [Evaluation of pot life (usable time)] In the same manner as in [Preparation of adhesive composition and production of laminate] above, the first liquid and the second liquid were mixed to prepare the adhesive compositions of Examples 1 to 3. The prepared compositions were allowed to stand at room temperature (25°C) for an adhesive time of one hour from immediately after preparation until three hours, and then the adhesive compositions immediately after preparation or after standing were used to obtain laminates of Production Examples 1-0 to 1-3, Production Examples 2-0 to 2-3, and Production Examples 3-0 to 3-3 in the same manner as in [Preparation of adhesive composition and production of laminate] above. The laminates of Production Examples 1-0 to 1-3 were heated at 70°C, at which the adhesive composition of Example 1 showed the highest shear strength, the laminates of Production Examples 2-0 to 2-3 were heated at 80°C, at which the adhesive composition of Example 2 showed the highest shear strength, and the laminates of Production Examples 3-0 to 3-3 were heated at 60°C, at which the adhesive composition of Example 3 showed the highest shear strength, and the shear strength of the laminates after heating was measured in the same manner as in [Measurement of adhesive strength by heating temperature] above. The results are shown in Table 4.

[0083]

[0084] As shown in Table 4, the adhesive compositions of Examples 1 to 3 were found to have a pot life (usable time) of at least 3 hours at room temperature.

[0085] From the above, it has been confirmed that the adhesive composition of the present disclosure can ensure a sufficient pot life (usable time) at room temperature and can exhibit sufficient adhesive strength after curing. According to the present disclosure, an adherend using such an adhesive composition and a method for producing the same are provided.

Claims

1. An adhesive comprising: a first substrate; a second substrate; and an adhesive layer that bonds the first substrate and the second substrate to each other, wherein the haze of the first substrate and the second substrate is 5% or more, and the adhesive layer contains a cured product of an adhesive composition that includes an organoborane complex, a compound having a radically polymerizable group, and a thermal acid generator.

2. A method for producing an adhesive body according to claim 1, comprising the steps of: bonding the first substrate and the second substrate together via the adhesive composition to obtain a laminate; and heating the laminate to obtain an adhesive body.

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