Adhesive components

Abstract

To provide an adhesive composition that exhibits excellent adhesion in high-temperature environments and excellent retention in high-temperature, high-humidity environments. [Solution] The adhesive composition comprises a (meth)acrylic resin and a tackifier. The tackifier is a polymer containing structural units derived from isopropenyltoluene. In the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12 area% or less, and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35 area% or more, relative to 100 area% of the peak area of ​​the polymer. The content ratio of the tackifier to the adhesive composition is 0.5% by mass or more and less than 10% by mass.

Description

TECHNICAL FIELD

[0001] The present invention relates to an adhesive composition. BACKGROUND ART

[0002] Conventionally, it has been known that a tackifier is blended into an adhesive composition from the viewpoint of improving adhesive strength.

[0003] For example, in Patent Document 1 below, an adhesive composition is produced by blending a (meth)acrylic resin, a tackifier, and a crosslinking agent. Further, the tackifier is a polymer containing a structural unit derived from isopropenyltoluene. And the polymer contains a high molecular weight component having a molecular weight of 2000 or more. PRIOR ART DOCUMENT PATENT DOCUMENT

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2024-141123 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0005] However, although the adhesive composition of Patent Document 1 described above is excellent in adhesive strength under high-temperature conditions, it has insufficient holding power under high-temperature and high-humidity conditions.

[0006] The present invention provides an adhesive composition that is excellent not only in adhesive strength under high-temperature conditions but also in holding power under high-temperature and high-humidity conditions. MEANS FOR SOLVING THE PROBLEM

[0007] The present invention [1] provides an adhesive composition comprising a (meth)acrylic resin and a tackifier, wherein the tackifier is a polymer containing structural units derived from isopropenyltoluene, and in the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12 area% or less, and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35 area% or more, and the content ratio of the tackifier to the adhesive composition is 0.5% by mass or more and less than 10% by mass.

[0008] The present invention [2] includes the adhesive composition described in [1] above, wherein the proportion of low molecular weight components of the polymer with a polystyrene equivalent molecular weight of 500 or less is 8 area% or more.

[0009] The present invention [3] includes the adhesive composition described in [1] above, wherein the proportion of low molecular weight components of the polymer with a polystyrene-based molecular weight of 500 or less is less than 8 area%.

[0010] The present invention [4] includes an adhesive composition according to any one of the above [1] to [3], wherein, in the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of high molecular weight components with a polystyrene molecular weight of 3000 or more relative to 100 area% of the peak area of ​​the polymer is 10 area% or more.

[0011] The present invention [5] includes an adhesive composition according to any one of the above [1] to [4], wherein the content ratio of the tackifier to the adhesive composition is 3% by mass or more and 7% by mass or less.

[0012] The present invention [6] comprises the adhesive composition described in any one of the above [1] to [5], wherein the polymer includes structural units derived from a C5 fraction.

[0013] The present invention [7] includes the adhesive composition described in [6] above, wherein the copolymer contains 90 mol% or more and 99 mol% or less of structural units derived from the isopropenyltoluene, and 1 mol% or more and 10 mol% or less of structural units derived from the C5 fraction.

[0014] The present invention [8] includes a laminate comprising an adhesive layer containing the adhesive composition described in any one of the above [1] to [7]. [Effects of the Invention]

[0015] In the adhesive composition of the present invention, the tackifier is a polymer containing structural units derived from isopropenyltoluene. Furthermore, in the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12 area% or less, and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35 area% or more, relative to 100 area% of the peak area of ​​the polymer. The content ratio of the tackifier to the adhesive composition is 0.5% by mass or more and less than 10% by mass.

[0016] Therefore, the adhesive composition of the present invention exhibits excellent adhesive strength in high-temperature environments as well as excellent holding power in high-temperature and high-humidity environments. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic diagram showing one embodiment of the laminate of the present invention. [Figure 2] Figure 2 is a gel permeation chromatogram illustrating the proportions of low-molecular-weight and high-molecular-weight components. [Modes for carrying out the invention]

[0018] The adhesive composition comprises (meth)acrylic resin and a tackifier.

[0019] <(meth)acrylic resin> A (meth)acrylic resin is the main component of an adhesive composition, and can be obtained, for example, as a polymer of a first polymerization component containing an alkyl (meth)acrylate. Note that (meth)acrylic refers to acrylic and / or methacrylic.

[0020] Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having an alkyl moiety with 1 to 12 carbon atoms. Examples of the alkyl (meth)acrylate having an alkyl moiety with 1 to 12 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate.

[0021] Preferred examples of the alkyl (meth)acrylate include methyl (meth)acrylate and alkyl acrylates having an alkyl moiety with 2 to 8 carbon atoms.

[0022] The alkyl (meth)acrylate is adjusted such that the glass transition temperature of the (meth)acrylic resin reaches a set value.

[0023] The blending ratio of the alkyl (meth)acrylate is, for example, 60 parts by mass or more, preferably 70 parts by mass or more, more preferably 80 parts by mass or more, still more preferably 90 parts by mass or more, particularly preferably 95 parts by mass or more, and most preferably 99 parts by mass or more, relative to 100 parts by mass of the first polymerization component; and is, for example, 100 parts by mass or less, preferably 99.9 parts by mass or less.

[0024] Further, the first polymerization component may contain a copolymerizable monomer copolymerizable with the alkyl (meth)acrylate.

[0025] Examples of copolymerizable monomers include functional group-containing vinyl monomers, vinyl esters, aromatic vinyl monomers, N-substituted unsaturated carboxylic acid amides, heterocyclic vinyl compounds, vinylidene halides, α-olefins, and dienes.

[0026] Examples of functional group-containing vinyl monomers include carboxyl group-containing vinyl monomers, hydroxyl group-containing vinyl monomers, amino group-containing vinyl monomers, glycidyl group-containing vinyl monomers, cyano group-containing vinyl monomers, sulfonic acid group-containing vinyl monomers and their salts, acetoacetoxy group-containing vinyl monomers, phosphate group-containing compounds, and amide group-containing vinyl monomers.

[0027] Examples of carboxyl group-containing vinyl monomers include (meth)acrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, and crotonic acid. Preferably, acrylic acid is used as the carboxyl group-containing vinyl monomer.

[0028] Examples of hydroxyl group-containing vinyl monomers include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

[0029] Examples of amino group-containing vinyl monomers include 2-aminoethyl (meth)acrylate, 2-(N-methylamino)ethyl (meth)acrylate, and 2-(N,N-dimethylamino)ethyl (meth)acrylate.

[0030] Examples of vinyl monomers containing a glycidyl group include glycidyl (meth)acrylate.

[0031] Examples of cyano group-containing vinyl monomers include (meth)acrylonitrile.

[0032] Examples of sulfonic acid group-containing vinyl monomers include allyl sulfonic acid and methallyl sulfonic acid. Examples of salts thereof include alkali metal salts (e.g., sodium salts and potassium salts) of the above sulfonic acid group-containing vinyl monomers, such as ammonium salts. Specifically, examples include sodium allyl sulfonate, sodium methallyl sulfonate, and ammonium methallyl sulfonate.

[0033] Examples of vinyl monomers containing an acetoacetoxy group include acetoacetoxyethyl (meth)acrylate.

[0034] Examples of phosphate group-containing compounds include 2-methachlorooxyethyl acid phosphate.

[0035] Examples of amide group-containing vinyl monomers include (meth)acrylamide.

[0036] Preferred examples of functional group-containing vinyl monomers include vinyl monomers containing carboxyl groups and / or hydroxyl groups.

[0037] Examples of vinyl esters include vinyl acetate and vinyl propionate. Vinyl acetate is preferred as the vinyl ester.

[0038] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, and divinylbenzene.

[0039] An example of an N-substituted unsaturated carboxylic acid amide is N-methylol(meth)acrylamide.

[0040] Examples of heterocyclic vinyl compounds include vinylpyrrolidone.

[0041] Examples of vinylidene halogen compounds include vinylidene chloride and vinylidene fluoride.

[0042] Examples of α-olefins include ethylene and propylene.

[0043] Examples of dienes include butadiene.

[0044] Furthermore, crosslinkable vinyl monomers can be cited as copolymerizable monomers.

[0045] Examples of crosslinkable vinyl monomers include compounds containing two or more vinyl groups. Examples of compounds containing two or more vinyl groups include methylenebis(meth)acrylamide, divinylbenzene, and polyethylene glycol chain-containing di(meth)acrylates.

[0046] Preferably, copolymerizable monomers include functional group-containing vinyl monomers.

[0047] Copolymerizable monomers can be used individually or in combination of two or more types.

[0048] The proportion of copolymerizable monomer is, for example, 0 parts by mass or more, preferably 0.1 parts by mass or more, and also, for example, 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and most preferably 1 part by mass or less, per 100 parts by mass of the first polymer component.

[0049] The polymerization method for the first polymerization component is not particularly limited, and known polymerization methods can be used.

[0050] Preferably, the first polymerization component is polymerized by radical polymerization in a solvent (e.g., ethyl acetate). In this method, for example, the first polymerization component and a polymerization initiator are mixed in a solvent and polymerization is carried out in the solvent.

[0051] The polymerization initiator is not particularly limited. Examples of polymerization initiators include persulfates, organic peroxides, and azo compounds. Organic peroxides are preferred as polymerization initiators.

[0052] Furthermore, the proportion of polymerization initiators is set appropriately according to the purpose and application.

[0053] Polymerization initiators can be used alone or in combination of two or more types.

[0054] Furthermore, in the polymerization described above, molecular weight modifiers may be added as needed.

[0055] Examples of molecular weight modifiers include mercaptans, allyl compounds, and low molecular weight halogen compounds. Examples of mercaptans include t-dodecyl mercaptan and n-dodecyl mercaptan. Examples of allyl compounds include allyl sulfonic acid, metaallyl sulfonic acid, and their sodium salts.

[0056] Furthermore, the proportion of molecular weight modifiers used is set appropriately according to the purpose and application.

[0057] Molecular weight modifiers can be used alone or in combination of two or more types.

[0058] The polymerization conditions are as follows: under atmospheric pressure, the polymerization temperature is, for example, 30°C or higher, preferably 50°C or higher, and for example, 150°C or lower, preferably 120°C or lower. The polymerization time is, for example, 1 hour or more, preferably 2 hours or more, and for example, 30 hours or less, preferably 20 hours or less.

[0059] This yields (meth)acrylic resin (a solution of (meth)acrylic resin).

[0060] The glass transition temperature of (meth)acrylic resin is, for example, 20°C or lower, preferably 0°C or lower, and for example, -60°C or higher, preferably -50°C or higher.

[0061] The above glass transition temperature can be calculated, for example, by FOX's formula.

[0062] In a solution of (meth)acrylic resin, the solid content concentration is, for example, 5% by mass or more, preferably 10% by mass or more, and also, for example, 70% by mass or less, preferably 60% by mass or less.

[0063] (Meth)acrylic resin can be used alone or in combination of two or more types.

[0064] The content of (meth)acrylic resin is, for example, 90 parts by mass or more, preferably 91 parts by mass or more, more preferably 92 parts by mass or more, even more preferably 93 parts by mass or more, and particularly preferably 94 parts by mass or more, based on 100 parts by mass of the total amount of (meth)acrylic resin and tackifier, or for example, 99.5 parts by mass or less, preferably 99 parts by mass or less, more preferably 98 parts by mass or less, even more preferably 97 parts by mass or less, and particularly preferably 96 parts by mass or less.

[0065] Furthermore, the content of (meth)acrylic resin is, for example, 88% by mass or more, preferably 89% by mass or more, more preferably 90% by mass or more, even more preferably 91% by mass or more, even more preferably 92% by mass or more, and particularly preferably 93% by mass or more, relative to the adhesive composition, and also, for example, 99% by mass or less, preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less, and particularly preferably 95% by mass or less.

[0066] (Meth)acrylic resin can be a commercially available product. Examples of commercially available products include Arontac S-1511X, Arontac S-1511 Kai, Arontac S-3403, Arontac S-3452YKF, and Arontac S-1605 (all solvent-based acrylic adhesives, manufactured by Toagosei Co., Ltd.).

[0067] <Adhesion agent> The tackifier is a polymer containing structural units derived from isopropenyltoluene.

[0068] Such polymers are formed by polymerizing a second polymerization component.

[0069] The second polymerization component contains isopropenyltoluene as an essential component.

[0070] The second polymerization component may also contain other components (excluding isopropenyltoluene). Examples of other components include α-methylstyrene, indene, vinyltoluene, and unsaturated aliphatic hydrocarbons.

[0071] Unsaturated aliphatic hydrocarbons are copolymerizable components with isopropenyltoluene, α-methylstyrene, indene, and vinyltoluene, and examples include C4 and C5 fractions.

[0072] The C4 fraction is obtained by refining and / or cracking petroleum. The C4 fraction is a fraction with a boiling point range of typically -15°C to 45°C under normal pressure, and includes, for example, carbon-4 unsaturated aliphatic hydrocarbons that do not contain conjugated double bonds, and carbon-4 unsaturated aliphatic hydrocarbons that contain conjugated double bonds.

[0073] Examples of carbon-4 unsaturated aliphatic hydrocarbons that do not contain conjugated double bonds include 1-butene, isobutene, and 2-butene.

[0074] An example of a four-carbon unsaturated aliphatic hydrocarbon containing a conjugated double bond is 1,3-butadiene.

[0075] The C4 fraction preferably consists of a carbon-4 unsaturated aliphatic hydrocarbon containing a conjugated double bond.

[0076] The C5 fraction is obtained by refining and / or cracking petroleum. The C5 fraction is a fraction with a boiling point range of typically -15°C to 45°C under normal pressure, and includes, for example, unsaturated aliphatic hydrocarbons with 5 carbon atoms that do not contain conjugated double bonds, and unsaturated aliphatic hydrocarbons with 5 carbon atoms that contain conjugated double bonds.

[0077] Examples of unsaturated aliphatic hydrocarbons with 5 carbon atoms that do not contain conjugated double bonds include 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and 2-pentene.

[0078] Examples of unsaturated aliphatic hydrocarbons with 5 carbon atoms containing conjugated double bonds include isoprene, 1,3-pentadiene, and cyclopentadiene.

[0079] The C5 fraction preferably consists of a carbon-5 unsaturated aliphatic hydrocarbon containing a conjugated double bond.

[0080] Other components preferably include unsaturated aliphatic hydrocarbons. More preferably, other components include C5 fractions. Specifically, the polymer preferably includes copolymers of isopropenyltoluene and C5 fractions. In other words, the polymer preferably contains structural units derived from the C5 fraction.

[0081] Other ingredients can be used alone or in combination of two or more types.

[0082] Furthermore, the second polymerization component may include monomers derived from fossil fuels or monomers derived from biomass.

[0083] Fossil fuels include petroleum, coal, natural gas, shale gas, or combinations thereof. Biomass refers to all renewable natural raw materials and their residues, including plant-derived or animal-derived materials such as fungi, yeasts, algae, and bacteria.

[0084] The polymer is then obtained by polymerizing the second polymerization component in the presence of a Friedel-Crafts catalyst.

[0085] Examples of Friedel-Crafts catalysts include phenolic complexes (e.g., boron trifluoride phenolate complexes).

[0086] The proportion of the Friedel-Crafts catalyst is, for example, 0.01 parts by mass or more, and for example, 1 part by mass or less, per 100 parts by mass of the second polymerization component.

[0087] The polymerization conditions include a polymerization temperature of, for example, -50°C or higher, or, for example, 50°C or lower. The polymerization time is, for example, 10 minutes or more, or, for example, 10 hours or less.

[0088] Furthermore, the above reaction may be carried out in the presence or absence of a solvent. Preferably, the above reaction is carried out in the presence of a solvent.

[0089] Examples of solvents include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, and alkyl esters. Aromatic hydrocarbons are preferred as solvents. Examples of aromatic hydrocarbons include toluene and xylene. Toluene is preferred as an aromatic hydrocarbon.

[0090] Solvents can be used alone or in combination of two or more types.

[0091] This yields a polymer (a solution of the polymer).

[0092] In a polymer solution, the solid content concentration is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 70% by mass or less, preferably 60% by mass or less.

[0093] In such polymers, the constituent units derived from isopropenyltoluene are 90 mol% or more, preferably 91 mol% or more, more preferably 92 mol% or more, even more preferably 93 mol% or more, even more preferably 94 mol% or more, and particularly preferably 95 mol% or more, and also, for example, 99 mol% or less, preferably 98 mol% or less, and more preferably 97 mol% or less.

[0094] If the constituent units derived from isopropenyltoluene are within the above range, the adhesive strength under high temperature conditions and the holding strength under high temperature and high humidity conditions can be further improved.

[0095] Furthermore, in such polymers, the constituent units derived from other components (preferably C5 fraction) are 1% or more, preferably 2 mol% or more, more preferably 3 mol% or more, and for example, 10 mol% or less, preferably 9 mol% or less, more preferably 8 mol% or less, even more preferably 7 mol% or less, even more preferably 6 mol% or less, and particularly preferably 5 mol% or less.

[0096] If the constituent units derived from other components (preferably the C5 fraction) are within the above range, the adhesive strength in high-temperature regions and the holding strength in high-temperature and high-humidity regions can be further improved.

[0097] The proportions of the above constituent units are as follows: 13 It can be measured by 13C-NMR spectroscopy.

[0098] The softening point of the polymer is, for example, 85°C or higher, preferably 90°C or higher, more preferably 95°C or higher, even more preferably 110°C or higher, and particularly preferably 120°C or higher, and also, for example, 170°C or lower, preferably 160°C or lower, and more preferably 150°C or lower.

[0099] The above softening point can be measured by the ring-and-ball method (in accordance with JIS K2207).

[0100] The number-average molecular weight (Mn) of the polymer, from the viewpoint of achieving both adhesiveness and retention, is, for example, 500 or more, preferably 700 or more, more preferably 800 or more, even more preferably 900 or more, and particularly preferably 1000 or more, as measured by gel permeation chromatography on a standard polystyrene basis, and also, for example, 2000 or less, preferably 1800 or less, more preferably 1600 or less, even more preferably 1400 or less, and particularly preferably 1300 or less.

[0101] If the above number-average molecular weight (Mn) is within the above range, the adhesive strength in high-temperature regions and the holding strength in high-temperature and high-humidity regions can be further improved.

[0102] Furthermore, the above number-average molecular weight (Mn) is, for example, 500 or more, preferably 700 or more, more preferably 900 or more, even more preferably 1000 or more, particularly preferably 1200 or more, and also, for example, 2000 or less, preferably 1500 or less, and more preferably 1400 or less.

[0103] If the above number-average molecular weight (Mn) is within the above range, the adhesive strength at high temperatures can be further improved.

[0104] On the other hand, the number-average molecular weight (Mn) is, from the viewpoint of retention, for example, 500 or more, preferably 700 or more, more preferably 800 or more, even more preferably 900 or more, and particularly preferably 1000 or more, and also, for example, 2000 or less, preferably 1500 or less, more preferably 1300 or less, even more preferably 1200 or less, and particularly preferably 1100 or less.

[0105] If the above number-average molecular weight (Mn) is within the above range, the retention capacity under high temperature and high humidity conditions can be further improved.

[0106] The weight-average molecular weight (Mw) of the polymer, from the viewpoint of achieving both adhesiveness and holding power, is, for example, 1000 or more, preferably 1200 or more, more preferably 1500 or more, even more preferably 1700 or more, and particularly preferably 1900 or more, as measured by gel permeation chromatography on a standard polystyrene basis, and also, for example, 5000 or less, preferably 3000 or less, more preferably 2500 or less, and even more preferably 2200 or less.

[0107] If the above weight-average molecular weight (Mw) is within the above range, the adhesive strength in high-temperature regions and the holding strength in high-temperature and high-humidity regions can be further improved.

[0108] Furthermore, the weight-average molecular weight (Mw) is, from the viewpoint of adhesive strength, for example, 1000 or more, preferably 1500 or more, more preferably 1700 or more, even more preferably 2000 or more, and particularly preferably 2100 or more. Also, for example, 5000 or less, preferably 3000 or less, more preferably 2500 or less, and even more preferably 2200 or less.

[0109] If the weight-average molecular weight (Mw) is within the above range, the adhesive strength at high temperatures can be further improved.

[0110] On the other hand, the weight-average molecular weight (Mw) is, from the viewpoint of retention, for example, 1000 or more, preferably 1200 or more, more preferably 1500 or more, even more preferably 1700 or more, and particularly preferably 1900 or more. Also, for example, 5000 or less, preferably 3000 or less, more preferably 2500 or less, even more preferably 2200 or less, and particularly preferably 2000 or less.

[0111] If the above weight-average molecular weight (Mw) is within the above range, the retention capacity under high temperature and high humidity conditions can be further improved.

[0112] The z-average molecular weight (Mz) of the polymer is, from the viewpoint of achieving both adhesiveness and retention, for example, 2000 or more, preferably 2500 or more, more preferably 3000 or more, and even more preferably 3100 or more, based on standard polystyrene equivalent measured by gel permeation chromatography, and also for example, 5000 or less, preferably 4000 or less, more preferably 3500 or less, and even more preferably 3300 or less.

[0113] If the above average molecular weight (Mz) is within the above range, the adhesive strength in the high-temperature region and the holding strength in the high-temperature, high-humidity region can be further improved.

[0114] Furthermore, the average molecular weight (Mz) z is, from the viewpoint of adhesive strength, for example, 2000 or more, preferably 2500 or more, more preferably 3000 or more, even more preferably 3200 or more, and also, for example, 5000 or less, preferably 4000 or less, more preferably 3500 or less, even more preferably 3300 or less.

[0115] If the above-mentioned average molecular weight (Mz) is within the above range, the adhesive strength at high temperatures can be further improved.

[0116] On the other hand, the average molecular weight (Mz) z is, from the viewpoint of retention, for example, 2000 or more, preferably 2500 or more, more preferably 3000 or more, and even more preferably 3100 or more, and also, for example, 5000 or less, preferably 4000 or less, more preferably 3500 or less, and even more preferably 3200 or less.

[0117] If the above average molecular weight (Mz) is within the above range, the retention capacity under high temperature and high humidity conditions can be further improved.

[0118] In polymers, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is, from the viewpoint of achieving both adhesiveness and holding power, for example, 1.10 or more, preferably 1.30 or more, more preferably 1.40 or more, even more preferably 1.50 or more, and particularly preferably 1.60 or more, and also, for example, 2.00 or less, preferably 1.85 or less, and more preferably 1.80 or less.

[0119] If the above ratio is within the above range, the adhesive strength in high-temperature regions and the holding strength in high-temperature and high-humidity regions can be further improved.

[0120] Furthermore, from the viewpoint of adhesive strength, the above ratio is, for example, 1.10 or more, preferably 1.30 or more, more preferably 1.50 or more, even more preferably 1.60 or more, and also, for example, 2.00 or less, preferably 1.80 or less, and more preferably 1.70 or less.

[0121] If the above ratio is within the above range, the adhesive strength in the high-temperature range can be further improved.

[0122] On the other hand, from the viewpoint of holding power, the above ratio is, for example, 1.40 or more, preferably 1.50 or more, more preferably 1.60 or more, even more preferably 1.65 or more, even more preferably 1.70 or more, and particularly preferably 1.75 or more. Also, for example, 2.00 or less, preferably 1.90 or less, more preferably 1.85 or less, and even more preferably 1.80 or less.

[0123] If the above ratio is within the above range, the retention force in high temperature and high humidity conditions can be further improved.

[0124] In polymers, the ratio of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw) (Mz / Mw) is, from the viewpoint of achieving both adhesiveness and holding power, for example, 1.10 or more, preferably 1.30 or more, more preferably 1.40 or more, even more preferably 1.50 or more, and also, for example, 2.00 or less, preferably 1.80 or less. More preferably 1.70 or less, even more preferably 1.65 or less.

[0125] If the above ratio is within the above range, the adhesive strength in high-temperature regions and the holding strength in high-temperature and high-humidity regions can be further improved.

[0126] Furthermore, from the viewpoint of adhesive strength, the above ratio is, for example, 1.10 or more, preferably 1.30 or more, more preferably 1.40 or more, even more preferably 1.50 or more, and also, for example, 2.00 or less, preferably 1.80 or less, more preferably 1.70 or less, even more preferably 1.60 or less, and particularly preferably 1.55 or less.

[0127] If the above ratio is within the above range, the adhesive strength in the high-temperature range can be further improved.

[0128] On the other hand, from the viewpoint of holding power, the above ratio is, for example, 1.10 or more, preferably 1.40 or more, more preferably 1.50 or more, even more preferably 1.55 or more, and particularly preferably 1.60 or more. Also, for example, 2.00 or less, preferably 1.80 or less, more preferably 1.70 or less, and even more preferably 1.65 or less.

[0129] If the above ratio is within the above range, the retention force in high temperature and high humidity conditions can be further improved.

[0130] Furthermore, in the chromatogram obtained by gel permeation graph measurement of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12 area% or less, and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35 area% or more, relative to 100 area% of the polymer peak. If the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more fall outside the above range, it is not possible to achieve both adhesive strength under high temperature conditions and holding strength under high temperature and high humidity conditions.

[0131] More specifically, in the chromatogram obtained by gel permeation graph measurement of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less relative to 100 area % of the polymer peak is 12 area % or less, more preferably 11 area % or less, even more preferably 10.5 area % or less, and for example, 1 area % or more, preferably 2 area % or more, more preferably 3 area % or more, even more preferably 4 area % or more, and particularly preferably 5 area % or more.

[0132] If the proportion of low molecular weight components is below the above upper limit, the adhesive strength in high-temperature regions and the holding power in high-temperature and high-humidity regions can be improved.

[0133] Furthermore, from the viewpoint of adhesive strength, the above ratio is, for example, 8 area% or less, preferably 7 area% or less, more preferably 6 area% or less, and also, for example, 1 area% or more, preferably 2 area% or more, more preferably 3 area% or more, even more preferably 4 area% or more, and particularly preferably 5 area% or more.

[0134] If the proportion of low molecular weight components is below the above upper limit, the adhesive strength at high temperatures can be further improved.

[0135] On the other hand, from the viewpoint of retention, the above ratio is 12 area% or less, preferably 11 area% or less, and also, for example, 8 area% or more, preferably 9 area% or more, and more preferably 10 area% or more.

[0136] If the proportion of low molecular weight components is within the above range, the retention capacity under high temperature and high humidity conditions can be further improved.

[0137] In the chromatogram obtained by gel permeation graph measurement of the polymer, the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more relative to 100 area of ​​the polymer peak is 35 area% or more, preferably 35.5 area% or more, more preferably 36 area% or more, and also, for example, 60 area% or less, preferably 50 area% or less, more preferably 48 area% or less, even more preferably 45 area% or less, and particularly preferably 43 area% or less.

[0138] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is above the lower limit mentioned above, the adhesive strength in high-temperature regions and the holding power in high-temperature and high-humidity regions can be improved.

[0139] Furthermore, from the viewpoint of adhesive strength, the above ratio is 35 area% or more, preferably 36 area% or more, more preferably 38 area% or more, even more preferably 40 area% or more, even more preferably 41 area% or more, particularly preferably 42 area% or more, and also, for example, 60 area% or less, preferably 50 area% or less, more preferably 48 area% or less, even more preferably 45 area% or less, particularly preferably 43 area% or less.

[0140] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is above the lower limit mentioned above, the adhesive strength at high temperatures can be further improved.

[0141] On the other hand, from the viewpoint of holding power, the above ratio is 35 area% or more, preferably 35.5 area% or more, more preferably 36 area% or more, and also, for example, 55 area% or less, preferably 45 area% or less, more preferably 40 area% or less, even more preferably 39 area% or less, even more preferably 38 area% or less, and particularly preferably 37 area% or less.

[0142] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is above the lower limit mentioned above, the retention capacity under high temperature and high humidity conditions can be further improved.

[0143] In the chromatogram obtained by gel permeation graph measurement of the polymer, the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 3000 or more relative to 100 area % of the polymer peak is, from the viewpoint of achieving both adhesiveness and holding power, for example, 10 area % or more, preferably 15 area % or more, more preferably 17 area % or more, even more preferably 18 area % or more, and also, for example, 35 area % or less, preferably 30 area % or less, more preferably 25 area % or less, and even more preferably 23 area % or less.

[0144] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 3000 or more is above the above lower limit, the adhesive strength in high-temperature regions and the holding power in high-temperature and high-humidity regions can be further improved.

[0145] Furthermore, from the viewpoint of adhesive strength, the above ratio is, for example, 10 area% or more, preferably 15 area% or more, more preferably 18 area% or more, even more preferably 20 area% or more, and also, for example, 35 area% or less, preferably 30 area% or less, more preferably 25 area% or less, and even more preferably 23 area% or less.

[0146] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 3000 or more is above the lower limit mentioned above, the adhesive strength at high temperatures can be further improved.

[0147] On the other hand, from the viewpoint of holding power, the above ratio is, for example, 10 area% or more, preferably 15 area% or more, more preferably 17 area% or more, even more preferably 18 area% or more, and also, for example, 30 area% or less, preferably 25 area% or less, more preferably 22 area% or less, even more preferably 20 area% or less.

[0148] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 3000 or more is above the lower limit mentioned above, the retention capacity under high temperature and high humidity conditions can be further improved.

[0149] In the chromatogram obtained by gel permeation graph measurement of the polymer, the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 5000 or more relative to 100 area of ​​the polymer peak is, from the viewpoint of adhesiveness and retention, for example, 1 area% or more, preferably 2 area% or more, more preferably 3 area% or more, even more preferably 4 area% or more, and also, for example, 15 area% or less, preferably 10 area% or less, and more preferably 7 area% or less.

[0150] If the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 5000 or more is above the lower limit mentioned above, the adhesive strength in high-temperature regions and the holding power in high-temperature and high-humidity regions can be further improved.

[0151] Adhesion agents can be used alone or in combination of two or more types.

[0152] The proportion of the tackifier is, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, particularly preferably 4 parts by mass or more, or, for example, 10 parts by mass or less, preferably 9 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 7 parts by mass or less, particularly preferably 6 parts by mass or less, based on 100 parts by mass of the total amount of (meth)acrylic resin and tackifier.

[0153] Furthermore, the content of the tackifier is 0.5% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 4% by mass or more, and less than 10% by mass, preferably 9% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, particularly preferably 6% by mass or less, relative to the adhesive composition.

[0154] If the tackifier content is within the above range, it exhibits excellent adhesive strength in high-temperature environments and superior holding power in high-temperature, high-humidity environments.

[0155] On the other hand, if the tackifier content is less than 0.5% by mass relative to the adhesive composition, it is not possible to achieve both adhesive strength in high-temperature regions and holding strength in high-temperature and high-humidity regions. Furthermore, if the tackifier content is 10% by mass or more relative to the adhesive composition, it is not possible to achieve both adhesive strength in high-temperature regions and holding strength in high-temperature and high-humidity regions. In particular, if the tackifier content exceeds 10% by mass, the holding strength in high-temperature and high-humidity regions decreases.

[0156] <Crosslinking agent> The adhesive composition preferably contains a crosslinking agent from the viewpoint of improving adhesive strength.

[0157] Examples of crosslinking agents include epoxy compounds, isocyanate compounds, aziridine compounds, and melamine compounds.

[0158] Examples of epoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, and resolcin diglycidyl ether.

[0159] Examples of isocyanate compounds include derivatives of hexamethylene diisocyanate (e.g., trimethylolpropane adducts, isocyanurate derivatives) and derivatives of tolylene diisocyanate (e.g., trimethylolpropane adducts, isocyanurate derivatives).

[0160] Examples of aziridine compounds include trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate.

[0161] Examples of melamine compounds include hexamethoxymethylolmelamine.

[0162] Preferably, isocyanate compounds are used as crosslinking agents.

[0163] Crosslinking agents can be used alone or in combination of two or more types.

[0164] Furthermore, the crosslinking agent content is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, relative to the adhesive composition, and also, for example, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1.5% by mass or less.

[0165] <Additives> The adhesive composition may contain additives in appropriate proportions as needed. Examples of additives include antioxidants, UV absorbers, antistatic agents, silane coupling agents, coating properties improvers, leveling agents, defoamers, plasticizers, surfactants, pigments, fillers, fungicides, processing aids, and anti-aging agents.

[0166] Additives can be used individually or in combination of two or more types.

[0167] <Preparation of adhesive compositions> The adhesive composition is obtained by blending (meth)acrylic resin, a tackifier, a crosslinking agent as needed, and additives as needed.

[0168] Furthermore, the adhesive composition may be diluted with a known solvent. Also, in the polymerization of the (meth)acrylic and / or polymer described above, if polymerization is carried out in the presence of a solvent, that solvent may be used as is.

[0169] When the adhesive composition is diluted, its solid content concentration is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 70% by mass or less, preferably 60% by mass or less.

[0170] Such adhesive compositions exhibit excellent adhesion and holding power in high-temperature ranges. A high-temperature range is, for example, a range between 70°C and 150°C.

[0171] Furthermore, the adhesive composition exhibits excellent adhesive strength and holding power to the adherend, from the viewpoint that the tackifier suppresses the mobility of the acrylic adhesive ((meth)acrylic resin) and makes it less prone to shear slippage.

[0172] Examples of adherends include wood veneers, wood plywood, particleboard, MDF (medium-density fiberboard) and other wood fiberboards, metal materials such as iron and aluminum, ceramics such as glass and porcelain, non-cement ceramic materials such as gypsum, non-ceramic ceramic materials such as ALC (autoclaved lightweight concrete) boards, and resin materials. Resin materials are preferred as adherends. Examples of resin materials include (meth)acrylic resin, polyester resin, polystyrene resin, polyolefin resin, ABS resin, polycarbonate resin, phenolic resin, vinyl chloride resin, cellulose resin, and rubber. Low-polarity materials such as polyolefin resins are preferred as resin materials. Examples of polyolefin resins include polyethylene and polypropylene. The surface of the adherend may also be treated with paint or other coatings.

[0173] <Laminate> Referring to Figure 1, one embodiment of the laminate will be described in detail.

[0174] In Figure 1, the vertical direction of the paper is the vertical direction (thickness direction), with the top of the paper being the top (one side in the thickness direction) and the bottom of the paper being the bottom (the other side in the thickness direction). The horizontal and depth directions of the paper are plane directions perpendicular to the vertical direction. Specifically, these correspond to the directional arrows in each figure.

[0175] As shown in Figure 1, the laminate 1 has a film shape (including a sheet shape) with a predetermined thickness. The laminate 1 extends in a planar direction perpendicular to the thickness direction. The laminate 1 has a flat top surface and a flat bottom surface.

[0176] The laminate 1 comprises a base material 2 and an adhesive layer 3 arranged sequentially on one side in the thickness direction. Specifically, the laminate 1 comprises a base material 2 and an adhesive layer 3 that is directly disposed on the upper surface (one side in the thickness direction) of the base material 2.

[0177] <Base material> The base material 2 has a film shape. The base material 2 is a support layer (support material) that ensures the mechanical strength of the laminate 1. The base material 2 is placed over the entire lower surface of the adhesive layer 3 so as to be in contact with the lower surface of the adhesive layer 3.

[0178] The base material 2 is not particularly limited, but examples include paper, cloth, leather, wood, resin sheets, rubber sheets, and metal sheets. A resin sheet is preferably used as the base material. The resin sheet is made of a flexible plastic material. Examples of such plastic materials include polyester resin, (meth)acrylic resin, polyolefin resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, polystyrene resin, and norbornene resin. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. An example of a (meth)acrylic resin is polymethacrylate. Examples of polyolefin resins include polyethylene, polypropylene, and cycloolefin polymer (COP).

[0179] The substrate 2 may be surface-treated as needed. Examples of surface treatments include corona discharge treatment and primer treatment.

[0180] The thickness of the substrate 2 is not particularly limited and is set appropriately according to the purpose and application. The thickness of the substrate 2 is, for example, 5 μm or more, and for example, 50 μm or less.

[0181] <Adhesive layer> The adhesive layer 3 has a film shape.

[0182] The adhesive layer 3 is formed from the above-mentioned adhesive composition. In other words, the adhesive layer 3 contains the above-mentioned adhesive composition.

[0183] The adhesive layer 3 is obtained by applying an adhesive composition to one side of the substrate 2 in the thickness direction.

[0184] The thickness of the adhesive layer 3 is, for example, 5 μm or more, and for example, 50 μm or less.

[0185] If the thickness of the adhesive layer 3 is above the lower limit and below the upper limit, it offers excellent handling properties.

[0186] <Method for manufacturing laminates> The laminate 1 is manufactured by applying an adhesive composition (a solution of the adhesive composition) to one side in the thickness direction of the substrate 2, and then drying it as necessary.

[0187] As for the drying conditions, the drying temperature is, for example, 40°C or higher, or for example, 120°C or lower. The drying time is, for example, 1 minute or more, or for example, 120 minutes or less. In the laminate 1, the total light transmittance of the adhesive layer 3, measured in accordance with JIS K7361, is, for example, 87% or higher.

[0188] In the laminate 1, the adhesive strength of the adhesive layer 3, as measured by the adhesive strength measurement described later, is, for example, 7.0 N / 25 mm or more, preferably 7.5 N / 25 mm or more.

[0189] In the laminate 1, the holding force of the adhesive layer 3, as measured by the holding force measurement described later, is, for example, 1.5 mm or less, preferably 1.0 mm or less, and more preferably 0 mm.

[0190] The laminate 1 comprises an adhesive layer 3 made of an adhesive composition. Therefore, the laminate 1 has excellent adhesive strength in high-temperature regions and also excellent holding power in high-temperature and high-humidity regions.

[0191] In the above description, the laminate 1 is provided with an adhesive layer 3 on one side of the base material 2 in the thickness direction, but the laminate 1 can also be provided with adhesive layers 3 on both sides of the base material 2 (one side in the thickness direction and the other side in the thickness direction).

[0192] <Effects and Effects> In the above-described adhesive composition, the tackifier is a polymer containing structural units derived from isopropenyltoluene. Furthermore, in the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12 area% or less, and the proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35 area% or more, relative to 100 area% of the polymer's peak area. The content ratio of the tackifier to the adhesive composition is 0.5% by mass or more and less than 10% by mass. Therefore, the adhesive composition of the present invention exhibits excellent adhesive strength in high-temperature regions as well as excellent retention strength in high-temperature and high-humidity regions.

[0193] It is known that the higher the proportion of tackifier in an adhesive composition, the better the adhesive strength and retention force. However, in this embodiment, the adhesive composition exhibits excellent adhesive strength in high-temperature regions and excellent retention force in high-temperature and high-humidity regions, despite having a low proportion of tackifier.

[0194] <Modified form of laminate> The laminate 1 may be a decorative sheet. Specifically, the laminate 1 may be a multilayer structure further comprising a decorative layer on another surface in the thickness direction of the base material 2. Alternatively, the laminate 1 may comprise a decorative layer instead of the base material 2.

[0195] A decorative layer is a decorative layer provided to give an object to be decorated an aesthetic appearance.

[0196] The decorative layer may be a single layer or a multilayer structure consisting of two or more layers.

[0197] The decorative layer has a film shape. The decorative layer is positioned so as to be in contact with the lower surface of the substrate 2, or so as to be in contact with the lower surface of the adhesive layer 3, and so as to be positioned on the entire lower surface of the adhesive layer 3.

[0198] The material of the decorative layer is not particularly limited, and known materials can be used.

[0199] The method for manufacturing the decorative sheet is not particularly limited, and known methods can be used. The decorative sheet may be manufactured, for example, by applying an adhesive composition (a solution of the adhesive composition) to one side in the thickness direction of the substrate or decorative layer, and then drying it as necessary.

[0200] The decorative sheet may have a protective layer on another surface (the bottom surface) in the thickness direction of the decorative layer. This can improve the weather resistance, chemical resistance, stain resistance, abrasion resistance, and electrical insulation properties of the decorative sheet.

[0201] The decorative sheet may have a release layer on one side (one side in the thickness direction of the adhesive layer 2 or the other side in the thickness direction of the decorative layer) or on both sides (one side in the thickness direction of the adhesive layer 2 and the other side in the thickness direction of the decorative layer). The release layer prevents unintended adhesion of the decorative sheet and is peeled off when the decorative sheet is bonded to the molded body (the object to be decorated).

[0202] The laminate 1 may be a colored film. Specifically, the laminate 1 may comprise the above-mentioned decorative layer, a substrate 2 containing a pigment or dye, and an adhesive layer 3 in order toward one side in the thickness direction.

[0203] <Applications of laminates> The laminates of the present invention can be applied to various industrial products. Specific applications include tapes, labels, sheets, films, double-sided tapes, and decorative films.

[0204] The substrate to which the decorative film is adhered is not particularly limited, as long as it is an article to which the decorative film can be adhered, but examples include molded articles having a three-dimensional shape. Examples of molded articles include automotive interior parts, automotive exterior parts such as bumpers, electrical appliances, and general merchandise.

[0205] The material of the substrate to which the decorative film is deposited is not particularly limited, but examples include the resin materials mentioned above as the substrate, and preferably low-polarity materials. Examples of low-polarity materials include polyolefin resins, and preferably polypropylene. If the material of the substrate to which the decorative film is deposited is a low-polarity material (particularly polypropylene), the laminate of the present invention exhibits even greater adhesive strength in high-temperature regions and holding strength in high-temperature and high-humidity regions. In other words, the laminate of the present invention exhibits particularly excellent adhesive strength in high-temperature regions and holding strength in high-temperature and high-humidity regions for low-polarity materials. [Examples]

[0206] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" are based on mass. Furthermore, specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0207] <Details of ingredients> Details of the abbreviations used in each example and comparative example are described below. IPT: Isopropenyltoluene C5:C5 fraction D-125: Polymerized rosin ester, trade name "Pensel D-125", manufactured by Arakawa Chemical Industries, Ltd. D-135: Polymerized rosin ester, trade name "Pensel D-135", manufactured by Arakawa Chemical Industries, Ltd. D-160: Polymerized rosin ester, trade name "Pensel D-160", manufactured by Arakawa Chemical Industries, Ltd. KE-100: Hydrogenated rosin, product name "Pine Crystal KE-100", manufactured by Arakawa Chemical Industries, Ltd.

[0208] <(meth)acrylic resin> We used Arontack S-1511X (solvent-based acrylic adhesive) manufactured by Toagosei Co., Ltd.

[0209] <Crosslinking agent> As a crosslinking agent, we use Takenate D-101E (registered trademark) (isocyanate compound (TDI·TMP adduct)) manufactured by Mitsui Chemicals, Inc.

[0210] <Manufacturing of tackifiers (polymers)> Manufacturing Example 1 In the first stage of a 1270 ml autoclave equipped with stirring blades, a mixture of the second polymerization component (isopropenyltoluene and the C5 fraction obtained by the thermal decomposition of petroleum naphtha) and dehydrated purified toluene (second polymerization component / toluene = 1 / 1 (volume ratio)) and a Friedel-Crafts catalyst (boron trifluoride phenolate complex diluted 10-fold with dehydrated purified toluene (1.7 times the equivalent of phenol)) were continuously supplied, and the polymerization reaction was carried out at 5°C. The mass ratio of isopropenyltoluene to the C5 fraction (isopropenyltoluene / C5 fraction) was set to 90 / 10, the supply rate of the mixture of the second polymerization component and toluene was 1.0 liter / hour, and the supply rate of the Friedel-Crafts catalyst was 56 milliliters / hour. This obtained the reaction mixture.

[0211] Next, the reaction mixture was transferred to a second autoclave, and the polymerization reaction was continued at 5°C. When the total residence time in the first and second autoclaves reached 2 hours, the reaction mixture was continuously discharged from the autoclaves. When the residence time reached three times the total residence time, 1 liter of the reaction mixture was collected to terminate the polymerization reaction. After polymerization was complete, a 1 N aqueous NaOH solution was added to the collected reaction mixture to demineralize the catalyst residue. Furthermore, the reaction mixture was washed five times with a large amount of water, and then the solvent and unreacted second polymerization components were removed under reduced pressure using an evaporator to obtain a polymer (tackifier) ​​which is a copolymer of isopropenyltoluene and the C5 fraction.

[0212] Manufacturing Example 2 100 g of the reaction product obtained in Production Example 1 was dissolved in 400 g of acetone, a good solvent, and then added to 800 g of methanol while stirring to precipitate the reaction product. Next, the reaction product was filtered off by suction filtration, washed with a mixed solvent (acetone / methanol = 1 / 2 (by weight)), and then dried under reduced pressure at 100°C for 10 hours. This yielded a tackifier, which is a copolymer of isopropenyltoluene and the C5 fraction.

[0213] Manufacturing Example 3 A polymer (tackifier) ​​was obtained, which is a copolymer of isopropenyltoluene and a C5 fraction, following the same procedure as in Production Example 1. However, the supply rate of the Friedel-Crafts catalyst was changed to 105 ml / hour.

[0214] <Evaluation of polymers> [Constituent units of each component] The constituent units of each component (second polymerization component) in the polymer of each manufacturing example are determined based on the following conditions: 13 The results were obtained by analyzing the 1C-NMR spectrum. The results are shown in Table 1. {conditions} Equipment: Bruker BioSpin AVANCE III cryo-500 nuclear magnetic resonance spectrometer Measured nucleus: 13C (125MHz) Measurement mode: Single-pulse proton broadband decoupling Pulse width: 45° (5.00 μsec) Points: 64k Measurement range: 250 ppm (-55 to 195 ppm) Repeat time: 5.5 seconds Total number of times: 128 Measurement solvent: Orthodichlorobenzene / benzene-d6 (4 / 1 (volume ratio)) Sample concentration: 60 mg / 0.6 mL Measurement temperature: 120℃ Window function: exponential (BF: 1.0Hz) Chemical shift criterion: δδ signal 29.73 ppm

[0215] [Softening point] The polymers from each production example, D-125, D-135, D-160, and KE-100, were measured using the ring-sphere method in accordance with JIS K2207. The results are shown in Table 1.

[0216] [Number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), Mw / Mn, Mz / Mw, percentage of low molecular weight components (500 or less), percentage of high molecular weight components (2000 or more), percentage of high molecular weight components (3000 or more), percentage of high molecular weight components (5000 or more)] For each polymer from the production example, D-125, D-135, D-160, and KE-100, the number-average molecular weight (Mn), weight-average molecular weight (Mw), and z-average molecular weight (Mz) in standard polystyrene equivalents were measured by gel permeation chromatography based on the following measurement conditions, and Mw / Mn and Mz / Mw were calculated. In the obtained chromatograms, the area of ​​the region with a molecular weight of 500 or less was defined as the proportion of low molecular weight components, and the area of ​​the region with a molecular weight of 2000 or more was defined as the proportion of high molecular weight components, and the proportions of low molecular weight components and high molecular weight components in the polymer were calculated. Furthermore, the proportions of high molecular weight components with a molecular weight of 3000 or more and high molecular weight components with a molecular weight of 5000 or more were calculated. The results are shown in Table 1. In addition, the chromatograms obtained for Production Example 1 and Production Example 2 are shown in Figure 2. {Measurement conditions} Equipment: GPC HLC-8320 (manufactured by Tosoh Corporation) Solvent: Tetrahydrofuran Columns: TSKgel G7000 x 1, TSKgel G4000 x 2, TSKgel G2000 x 1 (all manufactured by Tosoh Corporation) Flow rate: 1.0ml / min Sample: 20 mg / mL tetrahydrofuran solution Column temperature: 40℃ Detector: Differential refractive index detector Injection volume: 50μl

[0217] <Preparation of adhesive compositions> Examples 1, 2, and Comparative Examples 1-13 Based on the information in Table 2, (meth)acrylic resin, a tackifier, and a crosslinking agent (isocyanate compound) were blended to prepare an adhesive composition.

[0218] <Evaluation of adhesive compositions> [Fabrication of laminates with an adhesive layer] An ethyl acetate / toluene solution of the adhesive composition for each example and comparative example was applied to the release surface of the release paper using an applicator so that the film thickness after drying was 25-30 μm, and then heated and dried at 80°C for 10 minutes. Next, a 25 μm PET film was pressed onto the dried coated surface using a roller. The laminated adhesive composition was then left to stand at 40°C for 2 days to allow sufficient crosslinking. This resulted in a laminate having an adhesive layer with a thickness of 25-30 μm.

[0219] [Measuring Adhesion] The laminates of each example and comparative example described above were cut to a width of 25 mm and a length of 150 mm to prepare test specimens. Next, the release paper was peeled off each test specimen to expose the adhesive layer, and the exposed adhesive layer was brought into contact with a polypropylene (PP) board measuring 2 mm thick × 50 mm wide × 100 mm long in an atmosphere of 23°C. Then, a 2 kg rubber roll was passed back and forth once over the adhesive layer to press the test specimen to the PP board. After standing for 30 minutes, the 180° peel strength at 80°C was measured at a speed of 300 mm / min. Based on the obtained adhesive strength, the adhesive strength was evaluated according to the following criteria. The results are shown in Table 2. A: Adhesive force ≧7.0N / 25mm B: Adhesive force<7.0N / 25mm

[0220] [Measurement of holding power] The laminates of each example and comparative example described above were cut to a width of 20 mm and a length of 100 mm to prepare test specimens. Next, the release paper was peeled off each test specimen to expose the adhesive layer, and the exposed adhesive layer was brought into contact with a PP board measuring 2 mm thick × 25 mm wide × 50 mm long in an atmosphere of 23°C, so that the adhesive area was 20 mm × 20 mm. Then, a 2 kg rubber roll was passed back and forth twice to press the test specimen to the PP board. Each test specimen was left to stand at 23°C for 60 minutes, and then left to stand in an atmosphere of 85°C / 85% RH for 10 minutes. After that, each test specimen was suspended vertically in the same environment, a 500 g weight was placed on the lower end of the test specimen, and it was left to stand. The displacement width after 1 hour was measured. If the adhesive layer peeled off and the weight fell, it was indicated as ">20". Based on the obtained displacement width, the holding force was evaluated according to the following criteria. The results are shown in Table 2. A: Holding force (slippage) ≤ 1.5 mm B: Holding force (slippage range) > 1.5 mm

[0221] [Table 1]

[0222] [Table 2]

Claims

1. An adhesive composition comprising (meth)acrylic resin and a tackifier, The tackifier is a polymer containing structural units derived from isopropenyltoluene, In the chromatogram obtained by gel permeation chromatography of the polymer, relative to 100 area of ​​the peak area of ​​the polymer, The proportion of low molecular weight components with a polystyrene equivalent molecular weight of 500 or less is 12% by area or less. The proportion of high molecular weight components with a polystyrene equivalent molecular weight of 2000 or more is 35% or more by area. An adhesive composition in which the content ratio of the tackifier to the adhesive composition is 0.5% by mass or more and less than 10% by mass.

2. The adhesive composition according to claim 1, wherein the proportion of low molecular weight components of the polymer with a polystyrene-equivalent molecular weight of 500 or less is 8 area% or more.

3. The adhesive composition according to claim 1, wherein the proportion of low molecular weight components of the polymer having a polystyrene-based molecular weight of 500 or less is less than 8 area percent.

4. The adhesive composition according to claim 1, wherein, in the chromatogram obtained by gel permeation chromatography of the polymer, the proportion of high molecular weight components with a polystyrene-equivalent molecular weight of 3000 or more is 10 area% or more relative to 100 area% of the peak area of ​​the polymer.

5. The adhesive composition according to claim 1, wherein the content ratio of the tackifier to the adhesive composition is 3% by mass or more and 7% by mass or less.

6. The adhesive composition according to claim 1, wherein the polymer contains structural units derived from the C5 fraction.

7. In the aforementioned polymer, The structural units derived from isopropenyltoluene are 90 mol% or more and 99 mol% or less. The adhesive composition according to claim 6, wherein the structural units derived from the C5 fraction are 1 mol% or more and 10 mol% or less.

8. A laminate comprising an adhesive layer containing the adhesive composition according to any one of claims 1 to 7.

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