Adhesive composition, adhesive tape, and article

Abstract

The present invention addresses the problem of providing: an adhesive composition which has excellent adhesive properties, in particular, 180 DEG peel adhesion, constant load retention, and shear retention, and also has high re-peelability; and an adhesive tape having an adhesive layer comprising the adhesive composition. More specifically, the present invention provides an adhesive composition having a storage modulus G '(70 DEG C) of 1.5 * 104 Pa or more and tan [delta] (120 DEG C) of 0.4 or more.

Description

Technical Field

[0001] The present invention relates to an adhesive composition (the Japanese original of "adhesive" is "adhesive"), and more specifically, the present invention relates to an adhesive tape having an adhesive layer containing the adhesive composition, wherein the storage modulus G' (70 °C) of the adhesive composition is 1.5 × 10 4 Pa or more, and tan d (120 °C) is 0.4 or more. Background Art

[0002] Adhesive tapes are widely used as joining means for fixing components of relatively large electronic devices such as thin TVs, home appliances, and office automation equipment, or relatively small electronic devices such as portable electronic terminals, cameras, and personal computers. More specifically, in various industrial fields such as office automation equipment, IT / home appliances, and automobiles, they are not only used for fixing between metal plates constituting large electronic devices or fixing exterior components to the housing, fixing rigid components such as exterior components or batteries to small electronic devices, etc., for component fixing purposes and for temporary fixing purposes of such components, but also for label purposes for displaying product information.

[0003] In recent years, in the above-mentioned various industrial fields, from the viewpoint of protecting the global environment, for the purpose of saving resources, etc., for reused or reusable components used in products, most of them are disassembled and reused or reused after use. At this time, in the case of using an adhesive tape, it is necessary to peel off the adhesive tape attached to the component, but the above-mentioned adhesive tape usually has a large adhesive force, and if they are peeled off, sometimes the adhesive adheres to the component and causes "residual glue". The operation of removing the adhesive from such a component is very labor-consuming, so there is a need for an adhesive tape with excellent re-peelability that the adhesive does not remain on the component and can be peeled off and removed during the above-mentioned reuse or reuse.

[0004] In addition, in an adhesive tape used for component fixing, it is important to be able to fix the component without peeling during use, so it is desirable that all of the excellent 180° peel adhesive force, constant load holding force, and shear holding force are good.

[0005] As such an adhesive tape, for example, a peelable adhesive tape (for example, Patent Document 1) having the property of reducing its adhesive force by heating and being easily peeled from the adherend, and a hot-melt adhesive (for example, Patent Document 2) have been studied.

[0006] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2016-196567 Patent Document 2: Japanese Patent Application Publication No. 2014-159526 Summary of the Invention

[0007] The technical problem that the invention aims to solve The easy-peel adhesive tape described in Patent Document 1 exhibits excellent constant load holding force at temperatures below approximately 60°C, and its adhesive strength decreases upon heating, allowing for easy peeling from the adhered material. However, it does not address the crucial adhesive characteristic of shear holding force, essential for component fixing applications. There is room for improvement in balancing peeling difficulty under shear force and other adhesive properties. Furthermore, the hot-melt adhesive using a styrene-based thermoplastic elastomer described in Patent Document 2 maintains good adhesion and re-peelability over a long period, but it does not focus on constant load holding force and shear holding force. In applications such as fixing metal plates to each other in large electronic devices or fixing external components to housings, its adhesive properties may be insufficient.

[0008] Therefore, the technical problem of the present invention is to provide an adhesive composition and an adhesive tape having an adhesive layer comprising the adhesive composition, wherein the adhesive composition exhibits excellent adhesive properties, particularly 180° peel strength, constant load holding force and shear holding force, and also has high re-peelability.

[0009] Technical solutions for solving technical problems The inventors conducted in-depth research to solve the problems of the prior art, and as a result, obtained the following insights, thus discovering the present invention. Specifically, in order to achieve suitable adhesive properties in an adhesive composition, it is important to adjust the dynamic viscoelasticity of the adhesive composition among various physical properties, and the following insights were obtained: the storage modulus G' has a strong correlation with the shear holding force performance, tan... d There is a strong correlation between the performance and the shear retention force under constant load. Specifically, it was found that in order to produce an adhesive layer with excellent shear retention force, the storage modulus G' at a certain temperature needs to be above a certain value; and in order to produce an adhesive layer with excellent shear retention force under constant load, the tan... d The invention was completed by setting the value above a certain threshold.

[0010] The present invention includes the following methods.

[0011] [1] An adhesive composition having a storage modulus G' (70°C) of 1.5 × 10⁻⁶. 4 Pa or above, and tan d (120℃) is above 0.4.

[0012] [2] The adhesive composition according to [1] above contains an acrylic adhesive or a rubber adhesive.

[0013] [3] The adhesive composition according to [2] above, wherein the acrylic adhesive comprises a random copolymer or a triblock copolymer.

[0014] [4] The adhesive composition according to [2] above, wherein the rubber-based adhesive comprises a styrene-based triblock copolymer.

[0015] [5] The adhesive composition according to any one of [1] to [4] above, wherein the storage modulus G' (180°C) is 2000 Pa or less.

[0016] [6] The adhesive composition according to any one of [2] to [5] above further contains a tackifying resin.

[0017] [7] The adhesive composition according to any one of [2] to [6] above further contains an antioxidant.

[0018] [8] The adhesive composition according to any one of [1] to [7] above, wherein the adhesive composition is a hot melt adhesive composition.

[0019] [9] An adhesive tape comprising an adhesive layer comprising any one of the adhesive compositions described in [1] to [8] above.

[0020]

[10] An article which uses the adhesive tape described above [9].

[0021] Invention Effects According to the present invention, an adhesive composition can be provided that has a 180° peel bond strength, a constant load holding force, good shear holding force, and does not leave adhesive residue on the adherend upon peeling, and can be peeled off without damaging the adherend, as well as an adhesive tape having an adhesive layer comprising the adhesive composition. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the method for measuring shear holding force.

[0023] Figure 2 This is a schematic diagram illustrating the method for measuring the holding force under constant load. Detailed Implementation

[0024] The adhesive composition of the present invention has a storage modulus G' (70°C) of 1.5 × 10⁻⁶. 4 Pa or above, and tan d An adhesive composition with a strength of 0.4 or higher at 120°C.

[0025] The adhesive composition of the present invention, by having the above-mentioned characteristics, becomes an adhesive layer with excellent 180° peel adhesion, constant load holding force and shear holding force, and also excellent re-peelability.

[0026] Specifically, it was found that by making the storage modulus G' (70°C) of the adhesive composition of the present invention 1.5 × 10⁻⁶, the results were achieved. 4 At Pa or higher, the cohesive strength of the adhesive layer containing the adhesive composition of the present invention becomes higher, and it exhibits excellent shear retention even at high temperature environments.

[0027] Furthermore, by making the adhesive composition of the present invention tan d When the cohesive strength (at 120°C) is 0.4 or higher, the adhesive layer containing the adhesive composition of the present invention achieves a good balance between cohesion and flexibility, resulting in excellent adhesive strength. Among these, the constant load holding power is found to be particularly excellent.

[0028] The adhesive composition of the present invention will now be described in more detail based on its constituent elements.

[0029] (Adhesive composition) The adhesive composition of the present invention has a storage modulus G' of 1.5 × 10⁻⁶ at 70°C. 4 Pa or higher, preferably 1.5 × 10 Pa 4 ~1.0×10 6 Pa, more preferably 2.0 × 10 Pa 4 ~5.0×10 5 Pa, more preferably 2.0 × 10 Pa. 4 ~3.0×10 5 Pa. If the storage modulus G' is set within the above range, it exhibits excellent shear retention even at high temperatures and excellent melt viscosity at high temperatures, thus enabling the production of adhesive layers with suitable mixing workability and hot melt coating adaptability. In addition, due to the high cohesive strength, it has excellent re-peelability, and can be peeled off from the adhered object without residue.

[0030] The storage modulus G' of the adhesive composition of the present invention at 70°C can be adjusted to the above-mentioned preferred range, for example, by adjusting the type, content and weight-average molecular weight of the adhesive resin contained in the adhesive composition, the type and amount of tackifying resin, the softening point and molecular weight, the type, content and molecular weight of the plasticizer, the kinematic viscosity, etc.

[0031] The adhesive composition of the present invention at 120°C tan d The value is 0.4 or higher, preferably 0.4 to 10.0, more preferably 0.6 to 5.0, and even more preferably 0.6 to 3.0. If tan... dWithin the aforementioned range, a good balance between cohesion and flexibility is achieved, which improves the adhesion to the adhered objects and effectively mitigates the stress applied to the adhesive layer. Therefore, it is not easily peeled off when stretched under a certain load, and an adhesive layer with constant load retention and excellent 180° peel adhesion can be produced. In addition, the adhesion becomes good, which improves the adhesion to the adhered objects.

[0032] The adhesive composition of the present invention at 120°C tan d For example, the adhesive composition can be adjusted to the above-mentioned preferred range by adjusting the type, content and weight-average molecular weight of the adhesive resin, the type, amount and formulation of the tackifying resin, the softening point and molecular weight, the type, content and molecular weight of the plasticizer, the kinematic viscosity, etc.

[0033] The storage modulus G' at 70°C was determined by measuring dynamic viscoelasticity based on temperature dispersion. Using a viscoelastic testing machine (manufactured by TA Instruments Japan, trade name: ARES G2), the adhesive composition was formed to a thickness of approximately 2 mm, and the test piece was clamped between parallel discs with a diameter of 8 mm, which served as the measuring part of the testing machine. The storage modulus (G') was measured from 30°C to 200°C at a frequency of 1 Hz and a heating rate of 2°C / min.

[0034] tan at 120℃ d The loss modulus (G”) is determined using the same method as the storage modulus (G’), and tan is calculated from the above G’ and G”. d .

[0035] (Adhesive resin) The adhesive composition of the present invention is not particularly limited as long as it possesses the above-mentioned characteristics. It can be appropriately selected from known materials, containing an adhesive resin, and may also contain a tackifying resin and / or other components as needed.

[0036] The adhesive resin of this invention, as its main component, preferably comprises an acrylic adhesive resin containing an acrylic random copolymer or a block copolymer, or an aromatic vinyl adhesive resin containing a styrene block copolymer. More preferably, it comprises an acrylic adhesive resin containing an acrylic block copolymer or an aromatic vinyl adhesive resin containing a styrene block copolymer. In this specification, "main component of the adhesive resin" refers to the main component of the resin composition contained in the adhesive resin (typically containing more than 30% by mass).

[0037] In addition, when the main component of the adhesive resin in this invention is an acrylic random copolymer, it is preferable that the acrylic random copolymer accounts for 30 to 100% by mass relative to the total adhesive composition, more preferably 40 to 95 parts by mass of the acrylic random copolymer, and even more preferably 50 to 90 parts by mass of the acrylic random copolymer.

[0038] In addition, when the main component of the adhesive resin in this invention is an acrylic block copolymer, it is preferable that the acrylic block copolymer accounts for 30 to 100% by mass relative to the total adhesive composition, more preferably 40 to 90 parts by mass, and even more preferably 40 to 85 parts by mass.

[0039] In addition, when the main component of the adhesive resin in the present invention is a styrene-based block copolymer, the styrene-based block copolymer is preferably 30 to 100 parts by mass relative to the total adhesive composition, more preferably 40 to 90 parts by mass, and even more preferably 40 to 85 parts by mass.

[0040] (Acrylic adhesive resin containing acrylic random copolymers) In the case where the adhesive resin in this invention contains an acrylic random copolymer, the adhesive composition preferably contains an acrylic random copolymer, a crosslinking agent, and a tackifying resin.

[0041] The acrylic random copolymer of the present invention is obtained by polymerizing a monomer component containing a (meth)acrylic acid monomer. Examples of (meth)acrylic acid monomers that can be used in the manufacture of acrylic random copolymers include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, and other (meth)acrylic acid esters having alkyl groups having 1 to 12 carbon atoms.

[0042] Among them, (meth)acrylate monomers having alkyl groups having 4 to 12 carbon atoms are preferred, and (meth)acrylate monomers having alkyl groups having 4 to 8 carbon atoms are even more preferred. In terms of excellent 180° peel adhesion, constant load holding force and shear holding force, and thus high re-peelability, either or both of n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred.

[0043] The alkyl (meth)acrylate having 1 to 12 carbon atoms is preferably used in the total amount of monomers used in the manufacture of acrylic random copolymers at a rate of 60% by mass or more, more preferably in the range of 80% to 98.5% by mass. It is even more preferably used in the range of 90% to 98.5% by mass in terms of excellent 180° peel adhesion, constant load holding force and shear holding force, and thus high re-peelability.

[0044] Furthermore, when manufacturing acrylic random copolymers, highly polar vinyl monomers can be used as monomers. As such highly polar vinyl monomers, one or more of the following can be used: vinyl monomers having hydroxyl groups, vinyl monomers having carboxyl groups, vinyl monomers having amide groups, etc., or a combination of two or more.

[0045] As monomers containing hydroxyl groups, for example, hydroxyl-containing (meth)acrylates such as (meth)acrylate-2-hydroxyethyl ester, (meth)acrylate-2-hydroxypropyl ester, (meth)acrylate-4-hydroxybutyl ester, and (meth)acrylate-6-hydroxyhexyl ester can be used.

[0046] As vinyl monomers with carboxyl groups, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth)acrylic acid dimer, crotonic acid, ethylene oxide modified succinic acid acrylate, etc., can be used, among which acrylic acid is preferred.

[0047] As monomers with amide groups, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N,N-dimethylacrylamide, etc., can be used.

[0048] In addition to the above, vinyl acetate, ethylene oxide-modified succinic acid acrylate, 2-acrylamide-2-methylpropanesulfonic acid, etc., can also be used as highly polar vinyl monomers.

[0049] Relative to the total amount of monomers used in the manufacture of acrylic random copolymers, the aforementioned highly polar vinyl monomers are preferably used in the range of 1.5% to 20% by mass, more preferably in the range of 1.5% to 10% by mass, and are further preferably used in the range of 2% to 8% by mass in terms of excellent 180° peel adhesion, constant load holding force and shear holding force, and thus also high re-peelability.

[0050] As for the acrylic random copolymer in this invention, in order to obtain a double-sided adhesive tape that maintains excellent adhesive properties and has re-peelability that allows for easy peeling upon disassembly, an acrylic random copolymer with a weight average molecular weight of 400,000 to 3,000,000 is preferred. Since the constant load holding force and re-peelability are better, an acrylic random copolymer with a weight average molecular weight of 700,000 to 2,500,000 is more preferred.

[0051] It should be noted that the weight-average molecular weight and number-average molecular weight in this invention refer to values ​​calculated by gel permeation chromatography (GPC) and conversion to standard polystyrene. Specifically, the measurements can be performed using a GPC apparatus (HLC-8320 GPC) manufactured by Tosoh Corporation under the following conditions.

[0052] • Sample concentration: 0.5% by mass (tetrahydrofuran solution) • Sample injection volume: 100 m l • Eluent: Tetrahydrofuran • Flow rate: 1.0 ml / min • Measurement temperature: 40℃ • Main columns: 1 TSKgel G5000HXL + 1 TSKgel G4000HXL + 1 TSKgel G3000HXL + 2 TSKgel G2500HXL • Protective pillar: TSKgel HXL-H • Detector: Differential refractometer • Weight average molecular weight of standard polystyrene: 5 million to 5 million (manufactured by Tosoh Corporation) In the case where the adhesive composition of the present invention contains an acrylic random copolymer and a crosslinking agent, and an adhesive composition containing the crosslinking agent described later is used, the acrylic random copolymer preferably has functional groups that react with the functional groups of the crosslinking agent. Examples of functional groups in an acrylic random copolymer include hydroxyl groups. Hydroxyl groups can be introduced into the acrylic random copolymer, for example, by using a vinyl monomer having hydroxyl groups as the monomer described above. The amount of the vinyl monomer having hydroxyl groups relative to the total amount of monomers used in the manufacture of the acrylic random copolymer is preferably in the range of 0.01% by mass to 1.0% by mass, more preferably in the range of 0.03% by mass to 0.3% by mass.

[0053] The acrylic random copolymer of the present invention can be manufactured by polymerizing the aforementioned monomers using methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. Solution polymerization is preferred for improving the production efficiency of the acrylic random copolymer. As an example of the solution polymerization method, a method in which the aforementioned monomers, a known polymerization initiator, and an organic solvent are mixed and stirred at a temperature preferably 40°C to 90°C to carry out free radical polymerization is exemplified. The acrylic random copolymer obtained by the above method, for example, when manufactured using solution polymerization, can be in a state of being dissolved or dispersed in an organic solvent.

[0054] (Cross-linking agent) To easily ensure excellent adhesion, the acrylic random copolymer of the present invention preferably uses a crosslinking agent. Examples of such crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents. Among these, it is preferable to use either or both of isocyanate-based and epoxy-based crosslinking agents that have high reactivity with acrylic random copolymers, and more preferably, isocyanate-based crosslinking agents.

[0055] As the aforementioned isocyanate-based crosslinking agent, toluene diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, phenylmethylene diisocyanate, trimethylolpropane-modified toluene diisocyanate, etc., can be used, with toluene diisocyanate and trimethylolpropane-modified toluene diisocyanate being preferred.

[0056] The crosslinking agent is preferably used in an amount where the gel fraction of the adhesive layer relative to toluene is 40% to 80%, more preferably in an amount where the gel fraction is 30% to 70% by mass, and even more preferably in an amount where the gel fraction is 35% to 65% by mass in order to obtain an adhesive tape with both excellent adhesion and re-peelability.

[0057] It should be noted that the gel fraction of the adhesive layer refers to the value obtained by measuring using the method shown below. First, on the release surface of the release liner, with a dried thickness of 50... mThe adhesive was applied in a m-like manner, and the resulting material was dried at 100°C for 3 minutes, followed by curing at 40°C for 2 days to form an adhesive layer. This adhesive layer was then cut into squares 50 mm long and 50 mm wide, which were used as test pieces. After measuring the mass (G1) of the test pieces, they were immersed in toluene at 23°C for 24 hours. The mixture of the immersed test pieces and toluene was filtered through a 300-mesh metal mesh to extract the insoluble components from the toluene. These insoluble components were then dried at 110°C for 1 hour, and the mass (G2) of the resulting material was measured. The gel fraction was calculated based on the masses (G1), (G2), and the following formula.

[0058] Gel fraction (mass%) = (G2 / G1) × 100 (Acrylic adhesive resins containing acrylic block copolymers) In the case where the adhesive resin in this invention contains an acrylic block copolymer, the adhesive composition preferably contains an acrylic block copolymer (X), an acrylic block copolymer (Y), and a tackifying resin.

[0059] (Acrylic block copolymer (X)) The acrylic block copolymer (X) is preferably a block copolymer having segment A and segment B. Here, "segment" as used in this invention refers to the structural unit that constitutes each block in the block copolymer. For example, in the case of an ABA-type triblock copolymer in which structural unit (polymer or oligomer) A containing monomer a, structural unit (polymer or oligomer) B containing monomer b, and structural unit (polymer or oligomer) A containing monomer a are sequentially bonded together, structural units A and B are segments A and B, respectively (the same applies to the acrylic block copolymer (Y) described later).

[0060] The acrylic block copolymer (X) can be a diblock copolymer containing one segment A and one segment B (sometimes referred to as an acrylic diblock copolymer), a triblock copolymer having two segments A and one segment B (sometimes referred to as an acrylic triblock copolymer), or a multiblock copolymer having a total of four or more segments A and B. Preferably, the acrylic block copolymer (X) is a block copolymer in which segment A is a polymer mainly composed of alkyl methacrylate monomer units and segment B is a polymer mainly composed of alkyl acrylate monomer units. Using an acrylic triblock copolymer (X) with ABA-type segment bonds is more preferable as it exhibits high cohesive strength. Furthermore, segment A is preferably present at the ends. This is because if segment A is present at the ends, it easily aggregates to form a domain, thereby forming a pseudo-crosslinked structure and improving the cohesiveness of the adhesive. Additionally, the acrylic block copolymer (X) can use only one type or two or more types.

[0061] (Segment A) Segment A of the acrylic block copolymer (X) is preferably composed mainly of methacrylate monomers. Examples of such methacrylates include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 1-methylcyclohexyl methacrylate, 2-methylcyclohexyl methacrylate, 3-methylcyclohexyl methacrylate, 4-methylcyclohexyl methacrylate, and methyl methacrylate. 2-Phenoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-(N,N-dimethylamino)ethyl methacrylate, trifluoromethyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, stearyl methacrylate, 2-methoxypentyl methacrylate, 2-(N,N-dimethylamino)pentyl methacrylate, perfluoropentyl methacrylate, 2-trimethoxysilylpentyl methacrylate, etc.

[0062] Among the aforementioned monomers, in particular to improve shear retention at high temperatures, the main monomers constituting segment A are preferably esters of methacrylic acid with aliphatic alcohols having 3 or fewer carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate, as well as cyclohexyl methacrylate and isobornyl methacrylate.

[0063] In order to be referred to as the "body" in this invention, it is preferable that it contains 50% by mass or more in terms of the composition ratio (mass ratio) of all monomers constituting segment A, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0064] Furthermore, as a monomer constituting segment A of the acrylic block copolymer (X), monomers other than the aforementioned methacrylates that can be used include, for example, methacrylamides such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-isopropylmethacrylamide, N,N-dimethylmethacrylamide, and N,N-diethylmethacrylamide; acrylamides such as acrylamide, N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide; vinyl monomers with carboxyl groups such as methacrylic acid, acrylic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid; and styrene. α Aromatic vinyl monomers such as -methylstyrene and p-methylstyrene; conjugated diene monomers such as butadiene and isoprene; olefins such as ethylene and propylene; e - Caprolactone, valproic acid lactone, and other lactones.

[0065] The glass transition temperature (Tg) of segment A is not particularly limited as long as the acrylic block copolymer (X) can exhibit the desired physical properties, preferably 50–150°C, more preferably 70–140°C, and even more preferably 90–130°C. If the glass transition temperature is within the above range, segment A functions as a physical pseudo-crosslinking point and as a hard segment at the normal operating temperature of the adhesive, exhibiting excellent holding power and re-peelability when used in adhesive compositions.

[0066] (Segment B) Segment B of the acrylic block copolymer (X) is preferably composed of acrylate monomers. Examples of such acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-methylbutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, decyl acrylate, dodecyl acrylate, tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, 2-(N,N-dimethylamino)ethyl acrylate, trifluoromethyl acrylate, trimethoxysilylpropyl acrylate, 4-methyl-2-pentyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate.

[0067] Among the aforementioned monomers, in particular for the purposes of achieving excellent adhesion and tack, and improving stable adhesion under a wide peel speed range, monomers such as esters of acrylic acid and aliphatic alcohols with 4 to 9 carbon atoms, such as n-butyl acrylate, n-heptyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate, are preferred as the main constituent monomers of segment B.

[0068] In order to be referred to as the "body" in this invention, it is preferable that it contains 50% by mass or more in terms of the composition ratio (mass ratio) of all monomers constituting segment B, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0069] In addition to the acrylates mentioned above, other monomers that can be used as constituent monomers of segment B of the acrylic block copolymer (X) include, for example, alkyl methacrylates (e.g., methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, and other methacrylates that are constituent monomers of the above-mentioned segment A); methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-isopropyl methacrylamide, etc. Methacrylamides such as N,N-dimethylmethacrylamide and N,N-diethylmethacrylamide; acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide; vinyl monomers with carboxyl groups such as methacrylic acid, acrylic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid; aromatic vinyl monomers such as styrene, o-methylstyrene, and p-methylstyrene; conjugated diene monomers such as butadiene and isoprene; and olefins such as ethylene and propylene. e - Caprolactone, valproic acid lactone, and other lactones.

[0070] The glass transition temperature (Tg) of the aforementioned segment B is not particularly limited as long as the acrylic block copolymer (X) exhibits the desired physical properties, and is preferably -80 to 40°C, more preferably -70 to 10°C, and even more preferably -60 to 0°C. If the glass transition temperature is within this range, segment B functions as a soft segment with excellent flexibility, and can exhibit excellent low-temperature properties and impact resistance when used in adhesive compositions.

[0071] The glass transition temperatures of segments A and B constituting the acrylic block copolymer (X) are extrapolated onset temperatures of the transition regions of segments A and B, confirmed from curves obtained by analyzing the acrylic block copolymer (X) using differential scanning calorimetry (DSC). Multiple glass transition temperatures derived from segments A and B of the acrylic block copolymer (X) can be identified based on curves obtained by DSC determination. These glass transition temperatures can be attributed to segments A and B, respectively, based on the glass transition temperatures of polymers with the same chemical structure (monomer composition, stereoregularity, etc.) as the individual polymer blocks.

[0072] Provided that the effects of the present invention are not compromised, the acrylic block copolymer (X) can be modified as needed to have functional groups such as hydroxyl, carboxyl, anhydride, amino, and trimethoxysilyl groups in the molecular side chain or at the end of the molecular main chain.

[0073] The acrylic block copolymer (X) of the present invention preferably has a weight-average molecular weight of 50,000 or more and 400,000 or less, more preferably 110,000 or more and 300,000 or less, even more preferably 130,000 or more and 300,000 or less, and particularly preferably 150,000 or more and 300,000 or less. If the weight-average molecular weight of the acrylic block copolymer (X) is within the above range, the adhesive properties of the adhesive composition, such as adhesion strength, cohesion, and tackiness, become good.

[0074] The molecular weight distribution (weight average molecular weight / number average molecular weight) of the acrylic block copolymer (X) is preferably in the range of 1.0 to 2.0, more preferably in the range of 1.0 to 1.7, and even more preferably in the range of 1.0 to 1.5. By ensuring that the molecular weight distribution of the acrylic block copolymer (X) is within the above range, excellent holding power and re-peelability are achieved when it is mixed with the acrylic block copolymer (Y) described later within a specified range.

[0075] The content of segment A in the acrylic block copolymer (X) of the present invention is preferably 5 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 10 to 20% by mass or less, based on the total mass of the acrylic block copolymer (X). If the content of segment A in the acrylic block copolymer (X) is within the above range, it exhibits excellent high load-bearing capacity and re-peelability when mixed with the acrylic block copolymer (Y) within the specified range.

[0076] The content of segment B in the acrylic triblock copolymer (X) of the present invention is preferably 70-95% by mass, more preferably 75-95% by mass, and even more preferably 80-90% by mass or less, based on the total mass of the acrylic triblock copolymer (X). When the content of segment B in the acrylic triblock copolymer (X) is within the above range, it exhibits excellent high load-bearing capacity and re-peelability when mixed with the acrylic triblock copolymer (Y) within a specified range.

[0077] The acrylic block copolymer (X) of this invention can be synthesized by polymerizing raw material monomers, or commercially available products can be used. There are no particular limitations on the polymerization method; for example, anionic polymerization, atom transfer radical polymerization (ATRP), etc., can be used. Detailed descriptions of each polymerization method are omitted here. For example, known methods can be used, such as anionic polymerization using an organoalkali metal compound as a polymerization initiator in the presence of inorganic acid salts such as alkali metal or alkaline earth metal salts, anionic polymerization using an organoalkali metal compound as a polymerization initiator in the presence of organoaluminum compounds, and anionic polymerization using organorare earth metal complexes as polymerization initiators. For ATRP, known methods can be used, such as polymerization using organohalides or sulfonyl halides as initiators in the presence of transition metal compounds or nitrogen-containing compounds. Commercially available products include, for example, the "KURARITY (registered trademark) series" manufactured by Kuraray Co., Ltd.

[0078] The acrylic block copolymer (X) of the present invention is preferably solid at 23°C. By appropriately adjusting the types of monomers constituting segments A and B, the content ratio of segments A and B, and the weight-average molecular weight of segments A and B, the polymerization reaction can be adjusted so that the polymerized acrylic block copolymer (X) is solid at 23°C.

[0079] (Acrylic block copolymer (Y)) The acrylic block copolymer (Y) is the same as the acrylic block copolymer (X), being a block copolymer having segments A and B. Furthermore, the acrylic block copolymer (Y) is preferably liquid at 23°C.

[0080] The adhesive composition of the present invention, by combining an acrylic block copolymer (Y) which is liquid at 23°C with the above-mentioned acrylic block copolymer (X), can exhibit superior shear retention and superior re-peelability at high temperatures without reducing adhesive strength and constant load holding force.

[0081] The acrylic block copolymer (Y) can be a diblock copolymer containing one segment A and one segment B (sometimes referred to as an acrylic diblock copolymer), a triblock copolymer having two segments A and one segment B (sometimes referred to as an acrylic triblock copolymer), or a multiblock copolymer having a total of four or more segments A and B. Preferably, the acrylic block copolymer (Y) is a block copolymer in which segment A is a polymer mainly composed of alkyl methacrylate monomer units and segment B is a polymer mainly composed of alkyl acrylate monomer units. Using an acrylic triblock copolymer (Y) with ABA-type segment bonds is more preferable as it exhibits high cohesive strength and adaptability to hot-melt coating. Furthermore, the acrylic block copolymer (Y) can use only one type or two or more types.

[0082] (Segment A) Segment A of the acrylic block copolymer (Y) can use the same constituent monomers as segment A of the acrylic block copolymer (X) described above. It should be noted that in the adhesive composition of the present invention, the constituent monomers of segment A of the acrylic block copolymer (X) and segment A of the acrylic block copolymer (Y) can be the same or different. If they are the same, the acrylic block copolymer (X) and acrylic block copolymer (Y) have good compatibility, which is therefore preferred. Furthermore, in order to improve shear retention at high temperatures, monomers such as esters of methacrylic acid and aliphatic alcohols with 3 or fewer carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate, as the main constituent monomers of segment A, are preferably used.

[0083] (Segment B) The monomers constituting segment B of the acrylic block copolymer (Y) can be the same as those constituting segment B of the acrylic block copolymer (X) described above. It should be noted that in the adhesive composition of the present invention, the monomers constituting segment B of the acrylic block copolymer (X) and the acrylic block copolymer (Y) can be the same or different. If they are the same, the acrylic block copolymer (X) and the acrylic block copolymer (Y) have good compatibility, which is therefore preferred. Furthermore, from the viewpoint that excellent low-temperature properties and impact resistance can be obtained when used in the adhesive composition, the main component of segment B is preferably selected from esters of acrylic acid and aliphatic alcohols having 4 to 9 carbon atoms, such as n-butyl acrylate, n-heptyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate, as well as copolymers thereof.

[0084] The weight-average molecular weight of the acrylic block copolymer (Y) in this invention is preferably 20,000 or more and 100,000 or less, more preferably 40,000 or more and 80,000 or less. If the weight-average molecular weight of the acrylic block copolymer (Y) is within the above range, the exudation of the acrylic block copolymer (Y) from the adhesive layer containing the above adhesive composition can be suppressed.

[0085] The content of segment A in the acrylic block copolymer (Y) of the present invention is preferably 1 to 20% by mass, more preferably 3 to 15% by mass or less, and even more preferably 5 to 13% by mass or less, based on the total mass of the acrylic block copolymer (Y). If the content of segment A in the acrylic block copolymer (Y) is within the above range, the adhesive composition containing the block copolymer exhibits superior cohesive strength, and the adhesive strength and constant load holding power are further improved. In addition, it exhibits superior shear holding power and superior re-peelability at high temperatures.

[0086] The content of segment B in the acrylic block copolymer (Y) of the present invention is preferably 80-99% by mass, more preferably 85-97% by mass or less, and even more preferably 87-95% by mass or less, based on the total mass of the acrylic block copolymer (Y). If the content of segment B in the acrylic block copolymer (Y) is within the above range, it can impart flexibility, stress relaxation properties, and improved adhesive properties. On the other hand, it can suppress exudation and achieve better shear retention and re-peelability at high temperatures.

[0087] The acrylic block copolymer (Y) in this invention can be synthesized by polymerizing raw material monomers, or commercially available products can be used. There are no particular limitations on the polymerization method; specific examples of the polymerization method are the same as those for the acrylic block copolymer (X). Examples of commercially available products include, for instance, the "KURARITY (registered trademark) series" manufactured by Kuraray Co., Ltd.

[0088] The acrylic block copolymer (Y) of this invention is preferably liquid at 23°C. By appropriately adjusting the types of monomers constituting segments A and B, the content ratio of segments A and B, and the weight-average molecular weight of segments A and B, the polymerization reaction can be adjusted so that the polymerized acrylic block copolymer (X) is liquid at 23°C.

[0089] The content of acrylic block copolymer (Y) relative to 100 parts by weight of acrylic block copolymer (X) in this invention is preferably 1 to 140 parts by weight, more preferably 15 to 120 parts by weight, and even more preferably 20 to 100 parts by weight. If the content of acrylic block copolymer (Y) relative to 100 parts by weight of acrylic block copolymer (X) is within the above range, an adhesive layer that combines high adhesion and excellent cohesion can be produced, exhibiting excellent constant load retention and re-peelability.

[0090] (Aromatic vinyl adhesive resins containing aromatic block copolymers) In the case where the adhesive resin in this invention contains an aromatic block copolymer, the adhesive composition preferably contains a block copolymer of an aromatic vinyl compound and a conjugated diene compound, as well as a tackifying resin.

[0091] Examples of compounds constituting the aromatic segments of the aromatic block copolymers of the present invention include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, etc. α 2,4-Dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyl dimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, diphenylethylene containing tert-amino groups, etc. These aromatic monomers can be used alone or in combination of two or more.

[0092] Specific examples of conjugated diene compounds include isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, and 2-chloro-1,3-butadiene. β - Farnese, etc. These conjugated diene monomers can be used alone or in combination of two or more.

[0093] Using styrene as the aromatic chain segment facilitates control of the adhesive properties described below, and is therefore preferred from an economic and supply perspective. Isoprene and farnese are preferred as conjugated diene chain segments because they readily offer a good balance of flexibility and heat resistance.

[0094] Such block copolymers can be used alone or in combination with two or more base polymers. Examples include styrene-isoprene copolymers, styrene-isoprene-styrene copolymers, styrene-isoprene-butadiene-styrene copolymers, styrene-butadiene-styrene copolymers, styrene-ethylene-butene copolymers, styrene-ethylene-propylene copolymers, styrene-farnesene copolymers, styrene-farnesene-styrene copolymers, and their hydrides, etc., and other styrene-based resins. They can be used alone or in combination with two or more. Among these, the use of styrene-isoprene copolymers, styrene-isoprene-styrene copolymers, styrene-farnesene copolymers, and styrene-farnesene-styrene copolymers is more preferred, and particularly preferred, because it provides excellent initial adhesion, heat durability, and re-peelability.

[0095] The weight-average molecular weight of the styrene-based block copolymer in this invention is preferably 50,000 to 250,000, more preferably 100,000 to 200,000, and most preferably 170,000 to 200,000. If the weight-average molecular weight is too small, the melt viscosity or cohesive force of the system may decrease, resulting in poor thermal durability. If the weight-average molecular weight is too large, the viscosity of the system may increase, leading to poor compatibility with other components.

[0096] The styrene-based block copolymers of this invention preferably use block copolymers having styrene-derived structural units in the range of 5 to 80% by mass relative to the total mass of the styrene-based block copolymer, more preferably using block copolymers having styrene-derived structural units in the range of 5 to 60% by mass, even more preferably using block copolymers having styrene-derived structural units in the range of 5 to 40% by mass, and particularly preferably using block copolymers having styrene-derived structural units in the range of 10 to 30% by mass. This results in excellent adhesion and heat resistance. If the number of styrene-derived structural units is less than the above range, the cohesive strength decreases, and the heat durability and re-peelability deteriorate. Conversely, if the number of styrene-derived structural units is high, the cohesive strength becomes excessively high, and the adhesion decreases drastically, making it unsuitable for use as an adhesive composition.

[0097] The styrene-based block copolymers of this invention can be in the form of diblocks, triblocks, radial copolymers, or mixtures thereof. In triblocks and radial copolymers, hard segments (e.g., styrene blocks) are preferably disposed at the ends of the polymer chains. This is because hard segments disposed at the ends of the polymer chains tend to aggregate to form structural domains, thereby forming a pseudo-crosslinked structure and increasing the cohesiveness of the adhesive.

[0098] The styrene-based block copolymers used in this invention can be synthesized by polymerizing raw material monomers, or commercially available products can be used. Examples of commercially available products include Kraton D1107, 1112, and 1117 (all manufactured by Kraton Polymers), Quintac 3270, 3280, 3421, 3433N, 3440, 3450, 3520, and 3620 (all manufactured by Zeon Corporation of Japan), and SIS5229 (manufactured by JSR Corporation).

[0099] (Tackifying resin) The adhesive composition of the present invention preferably contains a tackifying resin in addition to the adhesive resin described above. By containing the tackifying resin, the adhesive composition of the present invention improves the adhesive strength to a level sufficient for practical use, satisfying properties such as adhesive strength, shear retention force, constant load peel retention force, and re-peelability.

[0100] The tackifying resin in this invention preferably has compatibility, enabling it to form a blend polymer with the aforementioned adhesive resin. There are no particular limitations on such a compatible resin; it can be appropriately selected from various known tackifying resins such as petroleum resins, styrene-based resins, coumarone-indene resins, terpene resins, modified terpene resins, rosin-based resins, rosin derivative resins, and ketone resins.

[0101] Examples of petroleum resins include aliphatic (C5 series) petroleum resins, aromatic (C9 series) petroleum resins, aliphatic / aromatic copolymers (C5 / C9 series) petroleum resins, and their hydrides (e.g., alicyclic petroleum resins obtained by hydrogenating aromatic petroleum resins).

[0102] Examples of styrene-based resins include resins whose main component is a homopolymer of styrene, and resins whose main component is a homopolymer of styrene. α Resins primarily composed of methylstyrene homopolymers, resins primarily composed of vinyltoluene homopolymers, and resins containing styrene monomers... α Resins whose main components are copolymers of two or more of methylstyrene and vinyltoluene (e.g., resins with copolymers of two or more of methylstyrene and vinyltoluene). α The main component is methylstyrene / styrene copolymer. α (e.g., methylstyrene / styrene copolymer resin).

[0103] As a coumarone-indene resin, a resin comprising coumarone and indene as monomeric components constituting the resin backbone (main chain) can be used. Examples of monomeric components that can be included in the resin backbone other than coumarone and indene include styrene. α -Methylstyrene, methylindene, vinyltoluene, etc.

[0104] Examples of terpene resins include: α -Pinene polymer, β -Pinene polymers, dipeptene polymers, etc. Examples of modified terpene resins include resins obtained by modifying the aforementioned terpene resins (phenol modification, catechol modification, styrene modification, hydrogenation modification, hydrocarbon modification, etc.). Specifically, examples include terpene phenol resins, styrene-modified terpene resins, hydrogenated terpene resins, and terpene catechol resins.

[0105] The term "terpene phenol resin" as used above refers to a polymer containing terpene residues and phenol residues. It encompasses both copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins) and resins obtained by modifying homopolymers or copolymers of terpenes (terpene resins, typically unmodified terpene resins) with phenol (phenol-modified terpene resins). Preferred examples of terpenes constituting the aforementioned terpene phenol resin include... α -pinene, β - Monoterpenes such as pinene and limonene (including d-form, l-form and d / l-form (dipentene)).

[0106] Specific examples of rosin-based resins include unmodified rosin (gum rosin, wood rosin, tall oil rosin, etc., also known as raw rosin) and modified rosin (rosin obtained by modifying unmodified rosin through hydrogenation, disproportionation, polymerization, other chemical modifications, etc.). In addition, examples of rosin derivative resins include esters of unmodified rosin and esters of modified rosin; unmodified rosin and modified rosin modified with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing the carboxyl groups in unmodified rosin, modified rosin, unsaturated fatty acid modified rosin, or unsaturated fatty acid modified rosin esters; metal salts of rosin (especially rosin esters), such as unmodified rosin, modified rosin, and various rosin derivatives; and rosin phenolic resins obtained by thermal polymerization of rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) by adding phenols to rosin using an acid catalyst.

[0107] From the viewpoint of good compatibility with the above-mentioned resins and improved adhesion, petroleum resins and rosin-based resins are preferred.

[0108] From the viewpoint of high-temperature retention, the tackifying resin in this invention preferably contains at least one tackifying resin with a softening point of 0°C or higher. By incorporating such a tackifying resin with a high softening point, in addition to adhesion and retention, constant load peeling and re-peeling properties can be significantly improved. From the viewpoint of further improving this property, the softening point of the tackifying resin is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 85°C or higher, and most preferably 90°C or higher.

[0109] Furthermore, the softening point of the tackifying resin is preferably below 200°C, more preferably below 170°C, even more preferably below 165°C, and most preferably below 160°C. If the softening point of the tackifying resin is within the above range, it is possible to prevent the resin from becoming too hard, thus obtaining a suitable tack as an adhesive. Furthermore, it is possible to improve shear retention force, constant load retention force, and re-peelability under high-temperature conditions. It should be noted that one type of tackifying resin may be used, or two or more types may be used. When two or more types are used, the tackifying resin having the above-mentioned preferred softening point is preferably 50% by mass or more, more preferably 60% by mass or more, based on the total mass of all tackifying resins.

[0110] When the adhesive resin is set to 100 parts by weight, the amount of tackifying resin in this invention is preferably 10 parts by weight or more and 200 parts by weight or less, more preferably 20 parts by weight or more and 150 parts by weight or less, further preferably 25 parts by weight or more and 120 parts by weight or less, and most preferably 50 parts by weight or more and 100 parts by weight or less. If the amount of tackifying resin is within the above range, the adhesive force and holding force can be significantly improved. In particular, it can improve the shear holding force and constant load holding force under high temperature environments.

[0111] (Anti-aging agent) The adhesive composition of the present invention may contain an anti-aging agent as needed. By using the anti-aging agent, thermal degradation of the adhesive is prevented, thus improving its quality stability. The anti-aging agent may be used alone or in combination of two or more. Examples of anti-aging agents include phosphorus-based antioxidants, phenolic antioxidants (such as hindered phenolic antioxidants), hindered amine antioxidants, aromatic amine antioxidants, and sulfur-based antioxidants.

[0112] (Any ingredient) The adhesive composition of the present invention may, as needed, contain one or more rubber-like polymers other than acrylic block copolymers and aromatic block copolymers, without significantly impairing the effects of the present invention. The rubber-like polymers are various polymers known in the adhesive field, such as rubber-based, acrylic-based, polyester-based, urethane-based, polyether-based, silicone-based, polyamide-based, and fluorine-based polymers.

[0113] The adhesive composition of the present invention, without significantly impairing the effects of the present invention, may contain, as needed, various additives commonly used in the adhesive field, such as leveling agents, crosslinking agents, crosslinking aids, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antistatic agents, ultraviolet absorbers, and light stabilizers. Regarding the aforementioned additives, conventionally known additives can be used by conventional methods.

[0114] <Morphology of Adhesive Compositions> The composition of the adhesive composition of the present invention has been described in detail above. The adhesive composition can also be made into a hot melt adhesive composition by melting and mixing the above-mentioned adhesive resin, the required tackifying resin, and any component (other adhesive raw materials), or into a solution adhesive composition dissolved in a specified organic solvent (toluene, ethyl acetate, etc.).

[0115] When preparing a hot-melt adhesive composition, the storage modulus G' of the adhesive composition at 180°C is preferably 2000 Pa or less, more preferably 1 to 1500 Pa, further preferably 1 to 1000 Pa, and most preferably 1 to 800 Pa. If the storage modulus G' is set within the above range, it exhibits excellent holding power even at high temperatures and excellent melt viscosity at high temperatures, thus enabling the preparation of an adhesive layer with suitable mixing workability and hot-melt coating adaptability.

[0116] The storage modulus G' at 180°C was determined by measuring dynamic viscoelasticity based on temperature dispersion. Using a viscoelastic testing machine (manufactured by TA Instruments Japan, trade name: ARES G2), a hot melt adhesive composition was formed to a thickness of approximately 2 mm. The test piece was sandwiched between parallel discs with a diameter of 8 mm, which served as the measuring section of the testing machine. The storage modulus (G') was measured from 30°C to 200°C at a frequency of 1 Hz and a heating rate of 2°C / min.

[0117] <Uses of Adhesive Compositions> The adhesive composition of the present invention is suitable for adhesive articles in the form of adhesive layers containing the adhesive composition, laminates containing the adhesive layers (e.g., adhesive tapes), etc. Hereinafter, as an example of the use of the adhesive composition of the present invention, a double-sided adhesive tape formed by coating the above-described adhesive composition on both sides of a substrate will be described. It should be noted that in the case of a single-sided adhesive tape, it is the same as a double-sided adhesive tape, except that the adhesive is coated on only one side of the substrate.

[0118] The double-sided adhesive tape obtained by applying the adhesive composition of the present invention has the above-described adhesive composition coated on both sides of the substrate, and then, as needed, a release liner is attached to the surface of the adhesive composition.

[0119] As a substrate, there are no particular limitations on the shape, such as film or sheet, that can be coated with the adhesive composition. For example, depending on the application of the adhesive tape, the following can be appropriately selected: plastic films such as polypropylene film, ethylene-propylene copolymer film, polyester film, polyvinyl chloride film, cellophane, polyimide, polycarbonate (PC), and polystyrene (PS); foamed sheets containing polyurethane foam, polyethylene foam, polypropylene foam, ethylene-vinyl acetate copolymer foam, butyl rubber foam, and polyacrylate foam; woven and nonwoven fabrics formed from various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, and metal fibers such as stainless steel); papers such as kraft paper, Japanese paper, and crepe paper; and metal foils such as aluminum foil and copper foil. As for the above-mentioned plastic films, non-stretch films, uniaxial stretch films, and biaxial stretch films can all be used. In addition, the surface of the substrate where the adhesive layer is located can be treated with a primer, corona discharge treatment, or other easy-to-adhere treatments.

[0120] The thickness of the substrate can be appropriately selected according to the purpose, and is usually preferably 1. m More than m and less than 2 mm.

[0121] As the release liner, conventional release paper or the like can be used, without particular limitation. For example, release liners with a release treatment layer on the surface of substrates such as plastic film and paper, or release liners containing low-adhesion materials such as fluoropolymers (polytetrafluoroethylene, etc.) and polyolefin resins (polyethylene, polypropylene, etc.) can be used. The release treatment layer mentioned above is, for example, formed by surface treatment of the substrate using release agents such as silicone-based, long-chain alkyl-based, or fluorine-based release agents.

[0122] Furthermore, there are no particular limitations on the method of coating the adhesive composition onto the substrate. Known methods such as dissolving the adhesive raw material in an organic solvent for coating (solvent coating), forming a sheet using multiple hot rollers for coating (calendering), and thermally melting the adhesive raw material for coating (thermal melting) can be used.

[0123] The adhesive composition of the present invention can be used for a variety of applications. Furthermore, the adhesive layer containing this adhesive composition can be used alone as an adhesive tape, and the laminate containing this adhesive layer can also be applied to a variety of applications. Examples include adhesives and adhesive tapes for fixing electronic components, fixing automotive components, surface protection, shielding, labeling, bonding, cutting tapes, sealing, corrosion and water resistance, electrical insulation, semiconductor manufacturing, optical display films, adhesive-type optical films, electromagnetic wave shielding, or as sealing materials for electrical and electronic components.

[0124] Example Next, embodiments will be given to further illustrate the present invention in detail, but the present invention is not limited to these embodiments.

[0125] (Example 1) A hot-melt adhesive composition was prepared by thoroughly mixing 100 parts by weight of styrene-butadiene block copolymer (Quintac 3280), 28.6 parts by weight of Pensil D-160 (polymeric rosin, Mw5100, softening point 160℃, manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifying resin, 36.3 parts by weight of Quintone G115 (aliphatic petroleum resin, Mw1800, softening point 115℃, manufactured by Zeon Corporation of Japan), and 0.88 parts by weight of antioxidant (Irganox 1010, manufactured by BASF Corporation) using a kneader set to 180℃. The adhesive composition was then remelted at 160℃ and coated onto a 100mm thick layer. m On the peel treatment surface of the release liner, an adhesive layer with a thickness of 50 is formed. m m adhesive tape.

[0126] (Examples 2-5) The composition of the adhesive composition was changed as shown in Table 3, except that the adhesive tape was made by the same procedure as in Example 1.

[0127] (Example 6) A hot-melt adhesive composition was prepared by thoroughly mixing 100 parts by weight of acrylic block copolymer (X) (Kurarity LA#3710, Mw=195000, Mw / Mn=1.1, manufactured by Kurarity Co., Ltd.), 20 parts by weight of acrylic block copolymer (Y) (Kurarity LA#2114, Mw=64000, Mw / Mn=1.1, manufactured by Kurarity Co., Ltd.), 80 parts by weight of tackifying resin (Neopolymer E-130, C9 petroleum resin, softening point 125℃, hydroxyl value ≥40mgKOH / g, manufactured by ENEOS Co., Ltd.), and 0.88 parts by weight of antioxidant (Irganox 1010, manufactured by BASF) using a kneader set to 180℃. The adhesive composition was then remelted at 160℃ and coated onto a 100mm thick layer. m On the peel treatment surface of the release liner, an adhesive layer with a thickness of 50 is formed. m m adhesive tape.

[0128] (Examples 7-8, Comparative Examples 1-2) The composition of the adhesive composition was changed as shown in Tables 4-5, and the adhesive tape was made by the same procedure as in Example 6.

[0129] (Example 9) A styrene-butadiene block copolymer (Quintac 3620), 40 parts of Quintone G115 (aliphatic petroleum resin, Mw1800, softening point 115℃, manufactured by ZEON Corporation, Japan) as a tackifying resin, and 40 parts of Pensel D-125 (polymeric rosin, Mw4100, softening point 125℃, manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifying resin were dissolved in toluene to obtain an adhesive composition. The adhesive composition was then applied using a coater to a dry thickness of 50 mm. m The coating is applied in a manner with a thickness of 100 mm. m On the peel-treated surface of the release liner, the adhesive layer is dried at 85°C for 5 minutes to create an adhesive layer with a thickness of 50 mm. m m adhesive tape.

[0130] (Example 10) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet, thermometer, and dropping funnel, 94 parts by mass of n-butyl acrylate, 4 parts by mass of acrylic acid, 0.06 parts by mass of 4-hydroxybutyl acrylate, and 200 parts by mass of ethyl acetate were added. The mixture was stirred while nitrogen was blown in and the temperature was raised to 65°C to obtain mixture (1). Next, 4 parts by mass of a 2,2'-azobisisobutyronitrile solution (2.5% by mass of solids) pre-dissolved in ethyl acetate was added to mixture (1). The mixture was stirred and kept at 65°C for 10 hours to obtain mixture (2). Then, mixture (2) was diluted with 98 parts by mass of ethyl acetate and filtered through a 200-mesh metal mesh to obtain a solution of acrylic random copolymer (1) with a weight average molecular weight of 1.6 million (converted from polystyrene).

[0131] Next, relative to 100 parts by weight of the solids component of the above-mentioned acrylic random copolymer (1) solution, 12 parts by weight of Pensel D-125 (polymerized rosin, Mw4100, softening point 125°C, manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifying resin and 15 parts by weight of Super Ester A-100 (rosin ester, Mw1100, softening point 100°C, manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifying resin were mixed and stirred, and then ethyl acetate was added to obtain an adhesive composition (1) with a solids component of 45% by weight. Relative to 100 parts by weight of the solids component of the adhesive composition (1), 3.1 parts by weight of CH-Y-1872 (trimethylolpropane adduct of toluene diisocyanate, isocyanate group content 7% by weight, non-volatile component 40% by weight, manufactured by DIC Corporation) as a crosslinking agent were added, and the mixture was stirred until homogeneous to obtain an adhesive composition (2). The adhesive composition (2) was applied using a coater to a thickness of 50 mm after drying. m The coating is applied in a manner with a thickness of 100 mm. mOn the peel-treated surface of the release liner, the adhesive layer is dried at 80°C for 3 minutes to create an adhesive layer with a thickness of 50 mm. m m adhesive tape.

[0132] <Instructions for Raw Materials> The raw materials used are as follows.

[0133] [Acrylic block copolymer] [Table 1]

[0134] [Aromatic Block Copolymer] [Table 2]

[0135] [Tackifying Resin] P-90: Arkon P-90 (petroleum resin, Mw1500, softening point 90℃, manufactured by Arakawa Chemical Industry) 90HS: Petrotac 90HS (C5 / 9 series petroleum resin, Mw2800, softening point 87℃, manufactured by Tosoh) D-125: Pensel D-125 (polymer rosin, Mw4100, softening point 125℃, manufactured by Arakawa Chemical Industry) D-160: Pensel D-160 (polymer rosin, Mw5100, softening point 160℃, manufactured by Arakawa Chemical Industry) A-100: Super Ester A-100 (Rosin ester, Mw1100, softening point 100℃, manufactured by Arakawa Chemical Industry) G115: Quintone G115 (aliphatic petroleum resin, Mw1800, softening point 115℃, manufactured by ZEON, Japan) E-100: Neopolymer E-100 (C9 series petroleum resin, Mw800, softening point 95℃, manufactured by ENEOS) E-130: Neopolymer E-130 (C9 series petroleum resin, Mw1300, softening point 125℃, manufactured by ENEOS) 160: Neopolymer 160 (C9 series petroleum resin, Mw2900, softening point 160℃, manufactured by ENEOS) PCJ: Haritack PCJ (Polymeric Rosin Ester, Mw4200, Softening Point 124°C, Manufactured by Harima Chemicals) [Antioxidants] Irg.1010: Irganox 1010 (manufactured by BASF) <Evaluation Methods> For adhesive tapes having an adhesive layer comprising an adhesive composition prepared as described above, measurements were performed according to the method described below. The results are shown in Tables 3 to 5.

[0136] (180° peel adhesion) In an environment of 23°C and 50% RH, the adhesive tapes produced in the examples and comparative examples were used on one side with a thickness of 25 mm. m After lining with a polyethylene terephthalate (PET) film, the adhesive tape was cut to a length of 120 mm and a width of 20 mm. Next, the other adhesive side was attached to a stainless steel plate (obtained by brushing a SUS304 stainless steel sheet with #360 sandpaper). A 2 kg roller was then applied to the upper surface of the adhesive tape once, and the plates were left to stand for 1 hour at 23°C and 50% RH to create a test piece formed by bonding the adhesive tape to the stainless steel plate. Then, using a Tensilon tensile testing machine, with the stainless steel plate constituting the test piece fixed, the strength of the adhesive tape when peeled at a tensile speed of 300 mm / min in a 180° direction was measured.

[0137] (Shear holding force) Under conditions of 23°C and 50% RH, the adhesive tapes produced in the examples and comparative examples have a single-sided utilization thickness of 50 mm. m After reinforcing the aluminum foil with a thickness of m, cut it to a length of 100mm and a width of 20mm. Next, the adhesive side of the cut adhesive tape 2 is arranged to form a bonding area of ​​20mm × 20mm (4cm). 2 The adhesive tape 2 is attached to a stainless steel plate 3 (obtained by using #360 sandpaper to perform a hairline finish on SUS304) in a certain manner. A 2kg roller is then applied to the upper surface of the adhesive tape 2 once and pressure is applied to form a test piece 1. The test piece 1, which is formed by pressing the adhesive tape 2 and the stainless steel plate 3 together, is then produced by letting it stand for 1 hour at a temperature of 23°C and a relative humidity of 50%RH.

[0138] Next, the portion of the adhesive tape 2 of test piece 1 that is not attached to the stainless steel plate 3 is folded. The stainless steel plate 3 side of test piece 1 is then fixed to a holding force gauge at a measurement temperature of 70°C. A 500g weight 3 is then installed on the folded portion of the adhesive tape 2. With the weight 3 installed, the piece is placed at 70°C, and the time until the adhesive tape 2 peels off (falls off) is measured (a schematic diagram of the measurement method is shown below). Figure 1 It should be noted that if the experiment is maintained for 1440 minutes, it ends here and is recorded as "1440 <".

[0139] (Constant load holding force) Under conditions of 23°C and 50% RH, the adhesive tapes produced in the examples and comparative examples had a single-sided utilization thickness of 25 mm. m After lining with a polyethylene terephthalate film of m, it is cut into pieces 100 mm long and 10 mm wide. Next, the adhesive side of the cut adhesive tape 6 is attached to a stainless steel plate 7 (obtained by brushing SUS304 with #360 sandpaper) with an attachment length of 50 mm. The upper surface of the adhesive tape 6 is pressed once with a 2 kg roller, and then left to stand at 40°C for 1 hour to produce a test piece 5 formed by pressing the adhesive tape 6 and the stainless steel plate 7 together.

[0140] Next, the stainless steel plate 7 side of test piece 5 was fixed to the constant load holding force gauge with the adhesive tape facing down. A 100g weight 8 was then installed on the portion of the adhesive tape 6 not attached to the stainless steel plate 7. With the weight 8 installed, the test piece was placed in an environment of 23°C and 50% RH, and the time until the adhesive tape 6 peeled off (fell) was measured (a schematic diagram of the measurement method is shown below). Figure 2 It should be noted that if the experiment is maintained for 180 minutes, it ends here and is recorded as "180 <".

[0141] (Re-peelability) Under conditions of 23°C and 50% RH, the adhesive tapes produced in the examples and comparative examples had a single-sided utilization thickness of 25 mm. m After lining with a polyethylene terephthalate film of m, it is cut to a length of 120 mm and a width of 20 mm. Next, another adhesive side is attached to a stainless steel plate (obtained by BA finishing of SUS304), and a 2 kg roller is pressed and rubbed once on the upper surface of the adhesive tape. Then, they are left to stand for 72 hours at a temperature of 23°C and a relative humidity of 50%RH to produce a test piece made by pressing the adhesive tape and the stainless steel plate together.

[0142] Next, with the stainless steel plate of the above test piece fixed, the above adhesive tape was peeled off at a stretching speed of 20 m / min in a 135° direction, as shown below, and the presence of residual adhesive or contamination of the adhesive on the stainless steel plate was evaluated.

[0143] ◎: The adhesive layer peels off from the stainless steel plate interface without leaving any residue or contamination.

[0144] 〇: Slight traces of glue remain on the surface of the stainless steel sheet, but the adhesive layer has peeled off at the interface between the adhesive layer and the stainless steel sheet.

[0145] ×: Damage within the adhesive layer causes peeling between the polyethylene terephthalate film and the adhesive layer, resulting in residual adhesive and contamination.

[0146] (Energy storage modulus G') After the adhesive layers prepared in the examples and comparative examples were cured at 40°C for 2 days, they were overlapped to a thickness of approximately 2 mm and then stamped into a diameter of 8 mm to form test pieces. The test pieces were clamped in a viscoelasticity testing machine (ARESG2, manufactured by TA Instruments Japan) with a parallel plate of 8 mm diameter installed. The temperature was measured from 30°C to 200°C at a frequency of 1 Hz and a heating rate of 2°C / min. The storage modulus G' at 70°C and 180°C was determined.

[0147] (tan) d ) tan at 120℃ d The loss modulus (G”) was determined using the same method as the storage modulus (G’), and tan ... d .

[0148] (Weight-average molecular weight (GPC) of adhesive resin) The weight-average molecular weight specified in this specification refers to the value determined by gel permeation chromatography (GPC) and converted to standard polystyrene. Specifically, the weight-average molecular weight was determined using a GPC apparatus (HLC-8320GPC) manufactured by Tosoh Corporation under the following conditions.

[0149] • Sample concentration: 0.5% by mass (tetrahydrofuran solution) • Sample injection volume: 100 m l • Eluent: Tetrahydrofuran • Flow rate: 1.0 ml / min • Measurement temperature: 40℃ • Main columns: 1 TSKgel G5000HXL + 1 TSKgel G4000HXL + 1 TSKgel G3000HXL + 2 TSKgel G2500HXL • Protective pillar: TSKgel HXL-H • Detector: Differential refractometer • Weight average molecular weight of standard polystyrene: 5 million to 5 million (manufactured by Tosoh Corporation) [Table 3]

[0150] [Table 4]

[0151] [Table 5]

[0152] As shown in Tables 3-5, the adhesive composition of the present invention exhibits excellent 180° peel strength, constant load holding force and shear holding force, as well as excellent re-peelability.

Claims

1. An adhesive composition, characterized in that, The energy storage modulus G' at 70℃ is 1.5×10⁻⁶. 4 Pa or higher, and tan at 120℃ δ It is above 0.

4.

2. The adhesive composition according to claim 1, wherein, The adhesive composition contains an acrylic adhesive or a rubber adhesive.

3. The adhesive composition according to claim 2, wherein, The acrylic adhesive comprises random copolymers or triblock copolymers.

4. The adhesive composition according to claim 2, wherein, The rubber-based adhesive comprises an aromatic triblock copolymer.

5. The adhesive composition according to claim 1, wherein, The energy storage modulus G' at 180℃ is below 2000Pa.

6. The adhesive composition according to claim 2, wherein, The adhesive composition also contains a tackifying resin.

7. The adhesive composition according to claim 2, wherein, The adhesive composition also contains antioxidants.

8. The adhesive composition according to any one of claims 1 to 7, wherein, The adhesive composition is a hot melt adhesive composition.

9. An adhesive tape, characterized in that, An adhesive layer comprising the adhesive composition according to any one of claims 1 to 7.

10. An article characterized in that, The adhesive tape of claim 9 was used.

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