Adhesive composition, adhesive layer, decorative film, and decorative molded body

Abstract

The present invention provides an adhesive composition having good storage stability, having good adhesive strength when not being stretched, and capable of maintaining good adhesive strength even after being stretched. Specifically, the present invention provides an adhesive composition that contains an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C), and that satisfies (1) to (4). (1) The melting point of the acid-modified polyolefin (A) is 50-120°C. (2) The content of the tackifier resin (C) is 100-600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (3) The content of the thermoplastic elastomer (B) is 100-600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (4) The thermoplastic elastomer (B) contains a styrene-based elastomer.

Description

Adhesive composition, adhesive layer, decorative film and decorated molded body

[0001] The present invention relates to an adhesive composition, an adhesive layer, a decorative film, and a decorated molded article.

[0002] BACKGROUND ART Polyolefins such as polypropylene and polyethylene have been used in the fields of automobile parts and the like as substrates for sheets, films, molded articles, etc., because they are inexpensive and have excellent properties such as moldability, chemical resistance, water resistance, and electrical properties.

[0003] Polyolefin substrates are often coated on their surfaces for purposes such as design and protection. When coating, an adhesive is usually used to improve adhesion between the topcoat and the polyolefin substrate. However, unlike polar substrates such as polyurethane resins, polyamide resins, acrylic resins, and polyester resins, polyolefin substrates are non-polar and crystalline, making it difficult to coat, bond, or otherwise apply them to them. Therefore, polyolefin adhesives based on polyolefin resins, which have the same main chain structure and therefore good adhesive properties, have been used as adhesives.

[0004] In recent years, with the trend toward lighter automobiles, polyolefin substrates have been increasingly used in automobile exteriors such as bumpers, automobile outer panels, fenders, radiator grilles, etc. In addition, substrates other than polyolefin substrates, such as polycarbonate, ABS resin, polyvinyl chloride, acrylic resin, urethane resin, and metal, are used for parts such as gasoline tanks, door handles, engine covers, and side mirrors.

[0005] The surfaces of these various substrates are coated with paint, and therefore, from the viewpoint of improving the efficiency of the coating process, there is a growing demand for a single adhesive that has adhesion to both polyolefin substrates and substrates of types other than polyolefin substrates, and that has sufficient storage stability so that it does not thicken or gel during processing or storage.

[0006] Also, VOC and CO ２From the viewpoint of cost reduction, the replacement of conventional spray painting with film decoration has been considered. In particular, the method of obtaining a decorated molded body by laminating a decorative film on the outermost surface of a molded body has the advantage of being able to decorate even molded body surfaces with three-dimensional irregularities, offering greater design freedom and superior productivity compared to conventional spray painting. Furthermore, as one means of film decoration, a film decoration method called vacuum pressure forming, in which adhesive materials are used to bond the film to three-dimensional parts, has attracted attention.

[0007] For example, Patent Document 1 describes "a decorative film having a decorative layer and an adhesive layer, the adhesive layer containing a block copolymer including a block composed of an isopentane-derived structure, a terpene resin, and a color pigment, the decorative film being for decorative molding under vacuum heating conditions or reduced pressure heating conditions." Furthermore, Patent Document 1 describes that "the manufacturing method for the decorative film preferably includes a step of forming an adhesive layer by applying an adhesive composition onto the decorative layer and drying or curing the composition."

[0008] Japanese Patent Application Publication No. 2022-39431

[0009] In order to prepare a decorative film using the adhesive composition described in Patent Document 1 and laminate the decorative film onto a molded body to produce a decorated molded body, it was necessary to bond the decorative film and the molded body together at a high temperature of 140°C.

[0010] However, when the adhesive composition is heated at a high temperature of 140° C. or higher, drawdown may occur, resulting in a problem of poor adhesive strength.

[0011] The present invention has been made in view of the above, and an object of the present invention is to provide an adhesive composition that has good storage stability, good adhesive strength when unstretched, and can maintain good adhesive strength even after stretching.

[0012] As a result of extensive research aimed at achieving the above object, the present inventors have found that the above object can be achieved by an adhesive composition containing an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C) in specific proportions. Based on this finding, the present inventors have conducted further research and have completed the present invention.

[0013] The present invention encompasses, for example, the subject matter described in the following items. Item 1. An adhesive composition containing an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C), and satisfying all of the following (1) to (4): (1) The melting point of the acid-modified polyolefin (A) is 50 to 120°C. (2) The content of the tackifier resin (C) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (3) The content of the thermoplastic elastomer (B) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (4) The thermoplastic elastomer (B) contains a styrene-based elastomer.

[0014] The adhesive composition of the present invention has good storage stability, has good adhesive strength when not stretched, and can maintain good adhesive strength even after stretching.

[0015] Preferred embodiments of the present invention will be described in detail below. The following description of the components may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0016] In this specification, the expressions "contain" and "comprise" include the concepts of "contain," "include," "consist essentially of," and "consist only of."

[0017] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "to" means a numerical range that includes the numbers before and after "to" as the upper and lower limits.

[0018] In this specification, "A and / or B" means "one of A and B" or "both A and B," and specifically means "A," "B," or "A and B."

[0019] In this specification, room temperature means a temperature within the range of 20°C to 25°C.

[0020] In this specification, "under a wide range of temperature conditions from low to high" generally means a temperature range of 40°C or higher and 120°C or lower, preferably a temperature range of 50°C or higher and 100°C or lower.

[0021] 1. Adhesive Composition The adhesive composition of this embodiment has the following components (I) to (V): (I) Contains an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C). (II) The melting point of the acid-modified polyolefin (A) is 50 to 120°C. (III) The content of the tackifier resin (C) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (IV) The content of the thermoplastic elastomer (B) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (V) The thermoplastic elastomer (B) contains a styrene-based elastomer.

[0022] The adhesive composition of the present embodiment has the above-described components (I) to (V), and therefore has high adhesive strength before stretching, sufficient adhesive strength even after stretching, and excellent storage stability.

[0023] <Acid-Modified Polyolefin (A)> The adhesive composition of the present invention contains an acid-modified polyolefin (A) as an essential component. In one embodiment, the acid-modified polyolefin (A) is preferably a polymer obtained by graft polymerizing at least one α,β-unsaturated carboxylic acid or an acid anhydride thereof onto a polyolefin. In other words, in one embodiment, the acid-modified polyolefin (A) is preferably a graft polymer having a structure in which at least one selected from an α,β-unsaturated carboxylic acid and an acid anhydride thereof is grafted onto a polyolefin.

[0024] The polyolefin is preferably a propylene-based resin containing propylene as a constituent component, more preferably a homopolypropylene (a homopolymer of propylene) and / or a propylene-α-olefin copolymer, and even more preferably a propylene-α-olefin copolymer.

[0025] In one embodiment, the acid-modified polyolefin (A) is more preferably a graft polymer having a structure in which an α,β-unsaturated carboxylic acid or an acid anhydride thereof is grafted onto a homopolypropylene or a propylene-α-olefin copolymer.

[0026] In one embodiment, the acid-modified polyolefin (A) is more preferably a graft polymer having a structure in which an α,β-unsaturated carboxylic acid or an acid anhydride thereof is grafted onto a propylene-α-olefin copolymer.

[0027] Propylene-α-olefin copolymers are copolymers of propylene as the main component with an α-olefin. Examples of α-olefins include ethylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and vinyl acetate. These α-olefins can be used alone or in combination of two or more. In one embodiment, of these α-olefins, ethylene and 1-butene are preferred, and 1-butene is more preferred.

[0028] In one embodiment, the content of the propylene component in the propylene-α-olefin copolymer is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and particularly preferably 70 mol% or more. When the content of the propylene component in the propylene-α-olefin copolymer is 50 mol% or more, the adhesive strength of the adhesive composition to polyolefin substrates (particularly polypropylene substrates) is further improved.

[0029] Examples of the α,β-unsaturated carboxylic acid or acid anhydride thereof to be graft polymerized onto the polyolefin include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, aconitic acid, aconitic anhydride, etc. Among these, acid anhydrides of α,β-unsaturated carboxylic acids are preferred, and maleic anhydride is more preferred.

[0030] In one embodiment, the acid-modified polyolefin (A) is preferably at least one selected from the group consisting of maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, and maleic anhydride-modified propylene-1-butene copolymer. In one embodiment, the acid-modified polyolefin (A) is more preferably maleic anhydride-modified propylene-ethylene copolymer and / or maleic anhydride-modified propylene-1-butene copolymer. In one embodiment, the acid-modified polyolefin (A) is even more preferably maleic anhydride-modified propylene-1-butene copolymer.

[0031] A wide variety of known methods can be used to graft polymerize an α,β-unsaturated carboxylic acid or its acid anhydride onto a polyolefin, including, for example, a radical graft reaction (a reaction in which radical species are generated on a polyolefin main chain in the presence of a radical generator, and an α,β-unsaturated carboxylic acid or its acid anhydride is graft polymerized using the radical species as a polymerization initiation point).

[0032] As the radical generator, it is preferable to use an organic peroxide, such as di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy-2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, or lauroyl peroxide.

[0033] The melting point (Tm) of the acid-modified polyolefin (A) is 50°C or higher and 120°C or lower. In one embodiment, the melting point of the acid-modified polyolefin (A) is preferably 55°C or higher, more preferably 60°C or higher, even more preferably 65°C or higher, and particularly preferably 70°C or higher. The melting point of the acid-modified polyolefin (A) is preferably 110°C or lower, more preferably 100°C or lower, even more preferably 90°C or lower, and particularly preferably 85°C or lower. When the melting point of the acid-modified polyolefin (A) is lower than 50°C, the cohesive force derived from the crystals of the acid-modified polyolefin (A) is weakened, and the adhesive strength of the adhesive composition when unstretched and after stretching is poor. Furthermore, when the melting point of the acid-modified polyolefin (A) is higher than 120°C, the storage stability of the adhesive composition is significantly reduced, and the adhesive strength of the adhesive composition when unstretched and after stretching is poor.

[0034] In one embodiment, the melting point (Tm) of the acid-modified polyolefin (A) is preferably 55°C or higher and 110°C or lower, more preferably 60°C or higher and 100°C or lower, even more preferably 65°C or higher and 90°C or lower, and particularly preferably 70°C or higher and 85°C or lower.

[0035] The melting point (Tm) of the acid-modified polyolefin (A) can be measured by a differential scanning calorimeter (DSC) in accordance with JIS K7121-2012. Specifically, using a DSC measurement device, about 5 mg of a sample is heated and held in a molten state at 150°C for 10 minutes, then cooled at a rate of 10°C / min, stabilized at -50°C, and further heated to 150°C at 10°C / min to measure the peak temperature when melted, and the melting peak temperature is evaluated as the melting point. Specific measurement methods are described in the Examples below.

[0036] In one embodiment, the acid value of the acid-modified polyolefin (A) is preferably 2 to 50 mgKOH / g, more preferably 3 to 40 mgKOH / g, even more preferably 4 to 30 mgKOH / g, even more preferably 5 to 25 mgKOH / g, and particularly preferably 6 to 16 mgKOH / g. When the acid value of the acid-modified polyolefin (A) is 2 mgKOH / g or more, the adhesive strength of the adhesive composition tends to be better. On the other hand, when the acid value is 50 mgKOH / g or less, the compatibility between the acid-modified polyolefin (A) and the thermoplastic elastomer (B) tends to be better.

[0037] The acid value of the acid-modified polyolefin (A) can be adjusted by the amounts of α,β-unsaturated carboxylic acid, acid anhydride of α,β-unsaturated carboxylic acid, and radical generator used. The acid value of the acid-modified polyolefin (A) can be measured, for example, in accordance with the test method of JIS K0070-1992. Specific measurement methods will be described in the examples below.

[0038] In one embodiment, the weight average molecular weight (Mw) of the acid-modified polyolefin (A) is preferably in the range of 10,000 to 200,000. It is more preferably in the range of 30,000 to 160,000, even more preferably in the range of 40,000 to 140,000, and most preferably in the range of 50,000 to 100,000. When the Mw of the acid-modified polyolefin (A) is 10,000 or more, the cohesive strength of the acid-modified polyolefin (A) is exhibited, and the adhesive properties of the adhesive composition tend to be better. Furthermore, when the Mw of the acid-modified polyolefin (A) is 200,000 or less, the storage stability and fluidity of the adhesive composition tend to be better, the adhesive properties of the adhesive composition tend to be better, and the adhesive strength after stretching tends to be excellent.

[0039] The Mw of the acid-modified polyolefin (A) can be measured by gel permeation chromatography (GPC) and converted from a polystyrene calibration curve. The GPC measurement is carried out by a conventionally known method using a commercially available device with THF or the like as a solvent. The specific measurement method will be described in the examples below.

[0040] In one embodiment, the melt viscosity of the acid-modified polyolefin (A) at 230°C is preferably 1000 mPa·s or more and 10000 mPa·s or less, more preferably 1200 mPa·s or more and 8500 mPa·s or less, even more preferably 1300 mPa·s or more and 7500 mPa·s or less, particularly preferably 1400 mPa·s or more and 6000 mPa·s or less, and most preferably 1500 mPa·s or more and 5000 mPa·s or less. When the melt viscosity of the acid-modified polyolefin (A) at 230°C is 1000 mPa·s or more and 10000 mPa·s or less, the storage stability of the adhesive composition tends to be further improved, the adhesive properties of the adhesive composition tend to be better, and the adhesive strength after stretching tends to be better.

[0041] In one embodiment, from the viewpoint of further improving the adhesion between the polyolefin substrate and the adhesive composition, the content of the acid-modified polyolefin (A) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 5% by mass or more and 30% by mass or less, more preferably 8% by mass or more and 25% by mass or less, even more preferably 9% by mass or more and 20% by mass or less, and even more preferably 9.5% by mass or more and 17.5% by mass or less.

[0042] <Thermoplastic elastomer (B)> The adhesive composition of the present invention contains a thermoplastic elastomer (B) as an essential component. The thermoplastic elastomer (B) contains a styrene-based elastomer. When the thermoplastic elastomer (B) contains a styrene-based elastomer, internal stress in the adhesive composition can be reduced, and the adhesion between the adhesive composition and a substrate film can be improved. Furthermore, when the thermoplastic elastomer (B) contains a styrene-based elastomer, the compatibility between the acid-modified polyolefin (A) and the thermoplastic elastomer (B) is improved, and the adhesive composition has good storage stability.

[0043] Examples of styrene-based elastomers include styrene homopolymers, styrene-butadiene block copolymers, styrene-butadiene-styrene block copolymers, styrene-ethylene-propylene block copolymers, styrene-isoprene-butadiene-styrene block copolymers, and styrene-isoprene-styrene block copolymers. The styrene-based elastomers may be hydrogenated. Examples of hydrogenated styrene-based elastomers include styrene-ethylene-butylene-styrene block copolymers and styrene-ethylene-propylene-styrene block copolymers. The styrene-based elastomers may also be acid-modified.

[0044] In one embodiment, the styrene-based elastomer is preferably at least one selected from the group consisting of a styrene homopolymer, a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-ethylene-propylene block copolymer, a styrene-isoprene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene-butylene-styrene block copolymer, and a styrene-ethylene-propylene-styrene block copolymer.

[0045] In one embodiment, the styrene-based elastomer is more preferably at least one selected from the group consisting of a styrene-butadiene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, and a styrene-isoprene-butadiene-styrene block copolymer.

[0046] In one embodiment, the styrene-based elastomer is particularly preferably a styrene-butadiene-styrene block copolymer and / or a styrene-ethylene-propylene-styrene block copolymer.

[0047] In one embodiment, the thermoplastic elastomer (B) may further contain, in addition to the styrene-based elastomer, at least one selected from the group consisting of an olefin-based elastomer, an alkene-based elastomer, a vinyl chloride-based elastomer, a urethane-based elastomer, and an amide-based elastomer, as long as the effects of the present application are not impaired.

[0048] In one embodiment, from the viewpoint of relaxing the stress of the thermoplastic elastomer (B), the content of the olefin-based elastomer relative to the total mass of the adhesive composition is preferably 10 mass % or less, more preferably 8 mass % or less, even more preferably 5 mass % or less, still more preferably 2.5 mass % or less, and particularly preferably 1 mass % or less.

[0049] Examples of olefin-based elastomers include ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-vinyl acetate copolymers, and ethylene-ethyl acrylate copolymers.

[0050] In one embodiment, the content of the ethylene-butene copolymer relative to the total mass of the adhesive composition is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, even more preferably 2.5% by mass or less, and particularly preferably 1% by mass or less.

[0051] In the present invention, the content of the thermoplastic elastomer (B) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). If the content of the thermoplastic elastomer (B) is less than 100 parts by mass per 100 parts by mass of the acid-modified polyolefin (A), the adhesive composition will have poor adhesive strength both before and after stretching. If the content of the thermoplastic elastomer (B) is more than 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A), the storage stability of the adhesive composition will be significantly reduced, and the adhesive strength of the adhesive composition will be poor both before and after stretching.

[0052] In one embodiment, the content of the thermoplastic elastomer (B) is preferably more than 100 parts by mass and less than 600 parts by mass, more preferably 150 parts by mass or more and 550 parts by mass or less, even more preferably 200 parts by mass or more and 500 parts by mass or less, still more preferably 250 parts by mass or more and 450 parts by mass or less, and most preferably 300 parts by mass or more and 430 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A).

[0053] In one embodiment, the styrene content in the thermoplastic elastomer (B) is preferably 5% by mass or more and 35% by mass or less, more preferably 7% by mass or more and 30% by mass or less, even more preferably 9% by mass or more and 25% by mass or less, and most preferably 11% by mass or more and 15% by mass or less. When the styrene content in the thermoplastic elastomer (B) is 5% by mass or more and 35% by mass or less, the compatibility between the thermoplastic elastomer (B) and the acid-modified polyolefin (A) is improved, the stress in the thermoplastic elastomer (B) is further relaxed, and the adhesive strength of the adhesive composition after stretching is improved. In addition, the adhesive composition has better adhesive properties under a wide range of temperature conditions from low to high, and the adhesive properties between polyolefin substrates and substrates of different types from the polyolefin substrate are further improved.

[0054] The styrene content in the thermoplastic elastomer (B) can be measured by H-NMR or C-NMR. Here, the "styrene content" refers to the content (mass %) of an aromatic vinyl polymer block, typically styrene, based on the mass of the thermoplastic elastomer (B).

[0055] In one embodiment, the density of the thermoplastic elastomer (B) is preferably 0.88 to 0.99 g / cm ３ , more preferably 0.89 to 0.91 g / cm ３ The density of the thermoplastic elastomer (B) is 0.88 to 0.99 g / cm ３ In this case, the difference in specific gravity between the thermoplastic elastomer (B) and the acid-modified polyolefin (A) does not become too large, and the storage stability of the adhesive composition tends to be better.

[0056] In one embodiment, the content of the thermoplastic elastomer (B) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 20% by mass or more and 70% by mass or less, more preferably 25% by mass or more and 60% by mass or less, even more preferably 30% by mass or more and 50% by mass or less, and still more preferably 38% by mass or more and 48% by mass or less.

[0057] <Tackifier Resin (C)> The adhesive composition of the present invention contains a tackifier resin (C) as an essential component. By containing the tackifier resin (C), the adhesive composition can maintain the tackiness of the surface after forming a film from the adhesive composition, and can further improve the adhesion between the substrate film and the adhesive layer.

[0058] In the present invention, the content of the tackifier resin (C) is 100 to 600 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A). If the content of the tackifier resin (C) is less than 100 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A), the storage stability of the adhesive composition will be significantly reduced. If the content of the tackifier resin (C) is more than 600 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A), the storage stability of the adhesive composition will be significantly reduced, and the adhesive strength of the adhesive composition both before and after stretching will be significantly reduced.

[0059] In one embodiment, the content of the tackifier resin (C) is preferably 150 parts by mass or more and 580 parts by mass or less, more preferably 200 parts by mass or more and 550 parts by mass or less, particularly preferably 250 parts by mass or more and 540 parts by mass or less, and most preferably 300 parts by mass or more and 530 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A).

[0060] In one embodiment, the softening point of the tackifier resin (C) is preferably 60°C or higher, more preferably 65°C or higher, even more preferably 70°C or higher, and most preferably 75°C or higher. The softening point of the tackifier resin (C) is preferably 150°C or lower, more preferably 145°C or lower, even more preferably 140°C or lower, and most preferably 130°C or lower. When the softening point of the tackifier resin (C) is 60°C or higher, the tackifier resin (C) is less likely to bleed out onto the surface at room temperature, resulting in a smooth surface, and the adhesive composition has better adhesion to polyolefin substrates and substrates of types different from the polyolefin substrate. Furthermore, when the softening point of the tackifier resin (C) is 150°C or lower, the adhesive composition has better adhesion under a wide range of temperature conditions from low to high, and the adhesive strength of the adhesive composition after stretching is better.

[0061] In one embodiment, the softening point of the tackifier resin (C) is preferably 60°C or higher and 150°C or lower, more preferably 65°C or higher and 145°C or lower, even more preferably 70°C or higher and 140°C or lower, and most preferably 75°C or higher and 130°C or lower.

[0062] In one embodiment, the tackifier resin (C) is preferably at least one resin selected from the group consisting of rosin-based resins, terpene-based resins, and petroleum resins.

[0063] Examples of rosin-based resins include unmodified rosins such as gum rosin, tall oil rosin, and wood rosin; disproportionated rosin; polymerized rosin; hydrogenated rosin; maleic acid-modified rosin; and rosin esters. These rosin-based resins may be used either alone or in combination of two or more.

[0064] Examples of the terpene resin include terpene resins such as α-pinene polymers, β-pinene polymers, and limonene polymers; aromatic modified terpene resins; and terpene phenol resins. These terpene resins can be used alone or in combination of two or more.

[0065] Examples of petroleum resins include aliphatic petroleum resins, alicyclic petroleum resins, and aromatic petroleum resins. These petroleum resins can be used either alone or in combination of two or more.

[0066] In one embodiment, the tackifier resin (C) is preferably a rosin resin or a terpene resin, more preferably a terpene resin. When the tackifier resin (C) is a rosin resin or a terpene resin, the adhesive composition has better adhesive properties under a wide range of temperature conditions from low to high, the adhesive strength of the adhesive composition after stretching is better, and the adhesive properties between a polyolefin substrate and a substrate of a type different from the polyolefin substrate are further improved.

[0067] In one embodiment, the tackifier resin (C) is preferably at least one selected from the group consisting of unmodified rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, maleic acid-modified rosin, rosin ester, terpene resin, aromatic-modified terpene resin, and terpene phenol resin.

[0068] In one embodiment, the tackifier resin (C) is particularly preferably a rosin ester and / or an aromatic modified terpene resin, and most preferably an aromatic modified terpene resin.

[0069] In one embodiment, the content of the tackifier resin (C) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 20% by mass or more and 70% by mass or less, more preferably 25% by mass or more and 60% by mass or less, even more preferably 30% by mass or more and 55% by mass or less, still more preferably 35% by mass or more and 50% by mass or less, and particularly preferably 38% by mass or more and 48% by mass or less.

[0070] <Organic Solvent (D)> The adhesive composition of the present embodiment may contain an organic solvent (D). Examples of the organic solvent (D) include those that can dissolve or disperse the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C). When the adhesive composition of the present embodiment contains the organic solvent (D), the coatability is further improved.

[0071] Examples of the organic solvent (D) include aromatic hydrocarbon solvents such as benzene, toluene, and xylene; aliphatic hydrocarbon solvents such as hexane, heptane, octane, and decane; alicyclic hydrocarbon solvents such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane; halogenated hydrocarbon solvents such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform; alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone. ketone-based solvents such as methyl cellosolve and ethyl cellosolve; cellosolve-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate; and glycol ether-based solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether, and these may be used either alone or in combination of two or more.

[0072] In one embodiment, from the viewpoint of being able to further improve the solubility of the adhesive composition and of providing the adhesive composition with better storage stability, the organic solvent (D) preferably comprises solvent (D1) and solvent (D2), wherein the solvent (D1) is at least one solvent selected from the group consisting of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and halogenated hydrocarbon solvents, and the solvent (D2) is at least one solvent selected from the group consisting of alcohol solvents, ketone solvents, ester solvents, and glycol ether solvents.

[0073] In one embodiment, from the viewpoint of further improving the solubility of the adhesive composition and providing the adhesive composition with even better storage stability, the organic solvent (D) more preferably consists of solvent (D1) and solvent (D2), wherein solvent (D1) is an alicyclic hydrocarbon solvent, and solvent (D2) is a ketone solvent and / or an ester solvent.

[0074] In one embodiment, from the viewpoint of being able to significantly improve the solubility of the adhesive composition and of providing the adhesive composition with excellent storage stability, the organic solvent (D) is even more preferably composed of solvent (D1) and solvent (D2), wherein solvent (D1) is an alicyclic hydrocarbon solvent, and solvent (D2) is an ester solvent.

[0075] In one embodiment, when the organic solvent (D) consists of solvent (D1) and solvent (D2), the mass ratio of solvent (D1) to solvent (D2) (solvent (D1) / solvent (D2)) is, from the viewpoint of further improving the solubility of the resin and further improving the storage stability of the adhesive composition, preferably solvent (D1) / solvent (D2)=95 / 5 to 50 / 50, more preferably solvent (D1) / solvent (D2)=90 / 10 to 55 / 45, even more preferably solvent (D1) / solvent (D2)=85 / 15 to 60 / 40, and particularly preferably solvent (D1) / solvent (D2)=80 / 20 to 65 / 35.

[0076] In one embodiment, the content of the organic solvent (D) is preferably 100 parts by mass or more and 5000 parts by mass or less, more preferably 200 parts by mass or more and 4500 parts by mass or less, even more preferably 250 parts by mass or more and 4000 parts by mass or less, still more preferably 300 parts by mass or more and 3500 parts by mass or less, and most preferably 400 parts by mass or more and 3000 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A). When the content of the organic solvent (D) is 100 parts by mass or more and 5000 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A), the storage stability of the adhesive composition is further improved, which is advantageous in terms of economy (production costs and transportation costs).

[0077] <Adhesive Composition> The adhesive composition of the present embodiment may contain, in addition to the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C), various additives such as plasticizers, curing agents, curing accelerators, curing catalysts, flame retardants, pigments, antiblocking agents, surfactants, antifoaming agents, anti-sagging agents, wetting agents, and ultraviolet absorbers, as long as the effects of the present invention are not impaired. These may be used alone or in combination of two or more.

[0078] The adhesive composition of the present embodiment may contain an antioxidant in order to further improve the adhesion between a polyolefin substrate and a substrate of a type different from the polyolefin substrate, and to further improve the storage stability of the adhesive composition.

[0079] In one embodiment, the antioxidant is preferably a phenolic antioxidant and / or a phosphorus-based antioxidant.

[0080] A wide variety of known commercially available phenolic antioxidants can be used, including, for example, SONGNOX 1076 (manufactured by SONGWON), SONGNOX 1010 (manufactured by SONGWON), SONGNOX 1098 (manufactured by SONGWON), and SONGNOX 2450 (manufactured by SONGWON).

[0081] A wide variety of known commercially available phosphorus-based antioxidants can be used, such as SONGNOX 1680 (manufactured by SONGWON).

[0082] The adhesive composition of this embodiment exhibits sufficient adhesiveness under a wide range of temperature conditions, from low to high.

[0083] The adhesive composition of the present embodiment has good adhesive strength when unstretched and can maintain good adhesive strength even after stretching. Furthermore, the adhesive composition of the present embodiment exhibits good adhesion to both polyolefin substrates and substrates of different types from the polyolefin substrate.

[0084] When the adhesive composition of this embodiment is molded to a thickness of 30 to 50 μm, the adhesive strength in the unstretched state is preferably 10 N / 25 mm or more, more preferably 15 N / 25 mm or more, and even more preferably 20 N / 25 mm or more.

[0085] When the adhesive composition of the present embodiment is molded to a thickness of 30 to 50 μm, the adhesive strength after stretching the adhesive composition to 1.25 times its original length and 1.25 times its original width is preferably 5 N / 25 mm or more, more preferably 10 N / 25 mm or more, and even more preferably 15 N / 25 mm or more.

[0086] Furthermore, when the adhesive composition of the present embodiment is molded to a thickness of 30 to 50 μm, the adhesive strength after stretching the adhesive composition 2.0 times in the vertical direction and 2.0 times in the horizontal direction is preferably 3 N / 25 mm or more, more preferably 5 N / 25 mm or more, and even more preferably 10 N / 25 mm or more.

[0087] In the present disclosure, the upper limit of the adhesive strength after stretching is not particularly limited, but 150 N / 25 mm is sufficient industrially. The adhesive strength can be measured in accordance with the peel test method of ASTM-D1876-61. Specific measurement methods will be described in the examples below.

[0088] In one embodiment, the total content of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) relative to the total mass of the adhesive composition is preferably such that the lower limit is 5% by mass or more, 10% by mass or more, 15% by mass or more, and 20% by mass or more, in that order; and is preferably such that the upper limit is 55% by mass or less, 50% by mass or less, 45% by mass or less, and 40% by mass or less, in that order; and these upper and lower limit values ​​can be combined in any desired manner.

[0089] In another embodiment, the adhesive composition may consist solely of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) (however, the inclusion of unavoidable impurities is permitted).

[0090] In one embodiment, when the adhesive composition contains an organic solvent (D), the total content of the acid-modified polyolefin (A), the thermoplastic elastomer (B), the tackifier resin (C), and the organic solvent (D) relative to the total mass of the adhesive composition is preferably 80 mass% or more, 85 mass% or more, 90 mass% or more, and 95 mass% or more, in that order.

[0091] In another embodiment, the adhesive composition may consist only of the acid-modified polyolefin (A), the thermoplastic elastomer (B), the tackifier resin (C), and the organic solvent (D) (however, the inclusion of unavoidable impurities is permitted).

[0092] The adhesive composition of the present embodiment has good adhesion between polyolefin substrates and substrates of different types from the polyolefin substrate, and therefore can be suitably used in a wide range of applications, such as sheets, films, and molded articles, in various fields, such as automobiles, home appliances, electronic materials, food, and medicine. The adhesive composition of the present embodiment can be particularly suitably used as an adhesive composition for decorative films.

[0093] The polyolefin substrate can be a wide variety of known polyolefins commonly used in this field. Examples of such polyolefins include polyethylene, polypropylene (PP), ethylene-propylene copolymers, propylene-1-butene copolymers, and ethylene-propylene-1-butene copolymers. The adhesive composition of this embodiment is particularly suitable for use with polypropylene substrates.

[0094] As the substrate different from the polyolefin substrate, substrates such as ABS resin, polycarbonate, polyvinyl chloride, acrylic resin, urethane resin, polyester resin, metal, etc. can be used.

[0095] A wide variety of known methods can be used to produce the adhesive composition of this embodiment, and examples include the following method. Step (1): An acid-modified polyolefin (A) having a melting point of 50 to 120°C, a thermoplastic elastomer (B) containing a styrene-based elastomer, and a tackifier resin (C) are charged into a mixer in any order and kneaded while heating so that the content of the tackifier resin (C) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A) and the content of the thermoplastic elastomer (B) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). Step (2): The mixture is then cooled to room temperature, thereby producing an adhesive composition.

[0096] In the above step (1), the organic solvent (D), the antioxidant, or the additive may be added to the mixer in any order, if necessary.

[0097] In the above step (1), the heating temperature during kneading is usually 50 to 200° C., preferably 60 to 150° C., and more preferably 70 to 120° C. The kneading time varies depending on the heating temperature and the like, but is usually 10 to 120 minutes, preferably 15 to 90 minutes, and more preferably 20 to 60 minutes.

[0098] <Decorative film> The decorative film of this embodiment has the adhesive layer of this embodiment and a decorative layer. The decorative film of this embodiment usually has the adhesive layer formed from the adhesive composition of this embodiment and a decorative layer. The adhesive composition of this embodiment can be suitably used when producing a decorative film.

[0099] The decorative film of the present embodiment preferably has, in this order: (1A) an adhesive layer formed from the adhesive composition of the present embodiment and a decorative layer; or (2A) a decorative layer and an adhesive layer formed from the adhesive composition of the present embodiment.

[0100] (Decorative Layer) The substrate of the decorative layer may be, for example, an ABS resin, polycarbonate, polyvinyl chloride, acrylic resin, urethane resin, polyester resin, etc. The thickness of the decorative layer is preferably 0.01 to 10 mm, more preferably 0.05 to 5 mm, and even more preferably 0.1 to 1 mm. The substrate of the decorative layer is usually the layer that determines the design of the decorative film.

[0101] (Adhesive Layer) The adhesive layer of this embodiment contains the adhesive composition of this embodiment. The adhesive layer of this embodiment is usually formed from the adhesive composition of this embodiment. When the adherend is a base film, the film thickness of the adhesive layer after drying is preferably 0.5 μm to 50 μm, more preferably 1 μm to 40 μm, and even more preferably 10 μm to 30 μm. By having the film thickness within the range of 0.5 μm to 50 μm, the decorative film exhibits better adhesion under a wide range of temperature conditions from low to high temperatures, and has even better adhesive strength after stretching.

[0102] When the adherend is a molded article, the thickness of the adhesive layer after drying is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm. By having the thickness within the range of 5 μm to 80 μm, the decorative film exhibits better adhesiveness under a wide range of temperature conditions from low to high, and has even better adhesive strength after stretching.

[0103] (Separator Layer) The decorative film of another embodiment preferably has, in this order: (1B) a separator layer, an adhesive layer formed from the adhesive composition of the present embodiment, and a decorative layer; or (2B) a decorative layer, an adhesive layer formed from the adhesive composition of the present embodiment, and a separator layer.

[0104] The separator layer is usually used to temporarily protect the adhesive layer, and may be, for example, a substrate film made of a synthetic resin or a substrate film made of a synthetic resin that has been subjected to a release treatment.

[0105] Examples of substrate films that can be used for the separator layer include polyolefin resins such as polyethylene and polypropylene; and polyester resins such as polyethylene terephthalate (PET).

[0106] The separator layer is usually removed from the decorative film by peeling it off during the manufacturing process or when it is used.

[0107] <Decorated Molded Body> The decorated molded body of this embodiment has an adherend and the decorative film of this embodiment. The decorated molded body of this embodiment is usually formed by laminating the decorative film of this embodiment to an adherend. The decorated molded body of this embodiment is usually formed from the adhesive composition of this embodiment. The decorated molded body of this embodiment has the property of having high adhesive strength when not stretched and sufficient adhesive strength even after stretching.

[0108] <Method for manufacturing decorative film> The decorative film of this embodiment can be manufactured by a wide variety of known methods. For example, the decorative film can be manufactured by applying the adhesive composition of this embodiment to the surface of a decorative layer using an applicator, a bar coater, or the like, and then heating and drying the applied adhesive composition to form an adhesive layer on the decorative layer.

[0109] When producing the decorative film, it is preferable to attach the separator layer onto the adhesive layer (the surface of the adhesive layer opposite to the decorative layer) using a hand roller or the like.

[0110] The decorative film of this embodiment has good adhesive strength and can maintain good adhesive strength even after stretching, so it is suitable for use in decorating an adherend by molding under vacuum or reduced pressure conditions (so-called vacuum molding or pressure molding).

[0111] Examples of the adherend include substrate films and molded articles. Examples of the substrate film include polyolefin resins such as polyethylene and polypropylene, and polyester resins such as polyethylene terephthalate (PET). Examples of the molded article include various home appliances such as household appliances, kitchen appliances, health appliances, and seasonal appliances; interior and exterior components of housing facilities such as toilets, bathrooms, doors, and walls; automobile interior and exterior components such as bumpers, dashboards, doors, roofs, and hoods; various miscellaneous goods such as household goods and daily necessities; electronic components; nursing care and medical supplies; and interior and exterior components of ships and aircraft.

[0112] The vacuum pressure forming method is a method of forming a decorated molded body by adsorbing a decorative film onto the molded body while applying pressure under vacuum conditions, and can be performed using, for example, a vacuum pressure forming device. An example of the vacuum pressure forming method is as follows.

[0113] For example, the adherend and the decorative film of this embodiment are placed in a molding chamber under atmospheric pressure, and then the molding chamber is evacuated. Subsequently, while maintaining the vacuum in the molding chamber, the chamber is heated to a desired temperature using a heater to soften the decorative film of this embodiment, and then stretched. After contacting the stretched decorative film with a molded article as the adherend, the vacuum in the molding chamber is released to create an atmospheric pressure state, and compressed air is introduced into the molding chamber from a compressed air tank, thereby pressing the stretched decorative film to the molded article along the shape of the molded article. The compressed air is then released, and the decorated molded article of this embodiment is removed. Note that, if the decorative film has a separator layer, it is preferable to set the adherend and the decorative film having the separator layer in the molding chamber under atmospheric pressure, and then peel off the separator layer.

[0114] The present invention provides the following aspects of the invention. Item 1. An adhesive composition containing an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C), and satisfying all of the following (1) to (4): (1) The melting point of the acid-modified polyolefin (A) is 50 to 120°C. (2) The content of the tackifier resin (C) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (3) The content of the thermoplastic elastomer (B) is 100 to 600 parts by mass per 100 parts by mass of the acid-modified polyolefin (A). (4) The thermoplastic elastomer (B) contains a styrene-based elastomer. Item 2. The adhesive composition according to Item 1, wherein the acid-modified polyolefin (A) has an acid value of 2 to 50 mgKOH / g. Item 3. Item 4. The adhesive composition according to any one of Items 1 to 3, wherein the acid-modified polyolefin (A) has a melt viscosity at 230°C of 1,000 to 10,000 mPa·s. Item 5. The adhesive composition according to any one of Items 1 to 4, wherein the acid-modified polyolefin (A) has a melting point (Tm) of preferably 55°C or higher and 110°C or lower, more preferably 60°C or higher and 100°C or lower, even more preferably 65°C or higher and 90°C or lower, and particularly preferably 70°C or higher and 85°C or lower. Item 6. Item 7. The adhesive composition according to any one of Items 1 to 5, wherein the acid-modified polyolefin (A) has an acid value of preferably 2 to 50 mgKOH / g, more preferably 3 to 40 mgKOH / g, even more preferably 4 to 30 mgKOH / g, even more preferably 5 to 25 mgKOH / g, and particularly preferably 6 to 16 mgKOH / g. Item 8. The adhesive composition according to any one of Items 1 to 6, wherein the acid-modified polyolefin (A) has a melt viscosity at 230°C of preferably 1,000 mPa·s or more and 10,000 mPa·s or less, more preferably 1,200 mPa·s or more and 8,500 mPa·s or less, even more preferably 1,300 mPa·s or more and 7,500 mPa·s or less, particularly preferably 1,400 mPa·s or more and 6,000 mPa·s or less, and most preferably 1,500 mPa·s or more and 5,000 mPa·s or less.Item 8. The adhesive composition according to any one of Items 1 to 7, wherein the acid-modified polyolefin (A) is a graft polymer having a structure in which at least one selected from an α,β-unsaturated carboxylic acid and an acid anhydride thereof is grafted onto a polyolefin. Item 9. The adhesive composition according to any one of Items 1 to 8, wherein the acid-modified polyolefin (A) is preferably a graft polymer having a structure in which an acid anhydride of an α,β-unsaturated carboxylic acid is grafted onto a homopolypropylene or a propylene-α-olefin copolymer, more preferably a graft polymer having a structure in which an acid anhydride of an α,β-unsaturated carboxylic acid is grafted onto a propylene-α-olefin copolymer. Item 10. The adhesive composition according to Item 9, wherein the propylene-α-olefin copolymer has a propylene component content of preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and particularly preferably 70 mol% or more. Item 11. Item 12. The adhesive composition according to any one of Items 1 to 11, wherein the acid-modified polyolefin (A) is preferably at least one selected from the group consisting of maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, and maleic anhydride-modified propylene-1-butene copolymer, more preferably maleic anhydride-modified propylene-ethylene copolymer and / or maleic anhydride-modified propylene-1-butene copolymer, even more preferably maleic anhydride-modified propylene-1-butene copolymer. Item 13. The adhesive composition according to any one of Items 1 to 11, wherein the acid-modified polyolefin (A) is preferably at least one selected from the group consisting of maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, and maleic anhydride-modified propylene-1-butene copolymer, more preferably maleic anhydride-modified propylene-ethylene copolymer and / or maleic anhydride-modified propylene-1-butene copolymer, even more preferably maleic anhydride-modified propylene-1-butene copolymer. Item 13. The adhesive composition according to any one of Items 1 to 12, wherein the content of the thermoplastic elastomer (B) is preferably more than 100 parts by mass and less than 600 parts by mass, more preferably 150 parts by mass or more and 550 parts by mass or less, even more preferably 200 parts by mass or more and 500 parts by mass or less, still more preferably 250 parts by mass or more and 450 parts by mass or less, and most preferably 300 parts by mass or more and 430 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A).Item 14. The adhesive composition according to any one of Items 1 to 13, wherein the styrene content in the thermoplastic elastomer (B) is preferably 5% by mass or more and 35% by mass or less, more preferably 7% by mass or more and 30% by mass or less, even more preferably 9% by mass or more and 25% by mass or less, and most preferably 11% by mass or more and 15% by mass or less. Item 15. The adhesive composition according to any one of Items 1 to 14, wherein the styrene-based elastomer is preferably at least one selected from the group consisting of a styrene homopolymer, a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-ethylene-propylene block copolymer, a styrene-isoprene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene-butylene-styrene block copolymer, and a styrene-ethylene-propylene-styrene block copolymer, more preferably at least one selected from the group consisting of a styrene-butadiene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, and a styrene-isoprene-butadiene-styrene block copolymer, and particularly preferably a styrene-butadiene-styrene block copolymer and / or a styrene-ethylene-propylene-styrene block copolymer. Item 16. The adhesive composition according to any one of Items 1 to 15, wherein the content of the tackifier resin (C) is preferably 150 parts by mass or more and 580 parts by mass or less, more preferably 200 parts by mass or more and 550 parts by mass or less, particularly preferably 250 parts by mass or more and 540 parts by mass or less, and most preferably 300 parts by mass or more and 530 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A). Item 17. The adhesive composition according to any one of Items 1 to 16, wherein the tackifier resin (C) is preferably a rosin-based resin or a terpene-based resin, more preferably a terpene-based resin.Item 18. The adhesive composition according to any one of Items 1 to 16, wherein the tackifier resin (C) is preferably at least one selected from the group consisting of unmodified rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, maleic acid-modified rosin, rosin ester, terpene resin, aromatic-modified terpene resin, and terpene phenol resin, particularly preferably a rosin ester and / or an aromatic-modified terpene resin, most preferably an aromatic-modified terpene resin. Item 19. The adhesive composition according to any one of Items 1 to 18, wherein the content of the olefin-based elastomer relative to the total mass of the adhesive composition is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, even more preferably 2.5% by mass or less, and particularly preferably 1% by mass or less. Item 20. The adhesive composition according to Item 19, wherein the olefin-based elastomer is an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-vinyl acetate copolymer, or an ethylene-ethyl acrylate copolymer. Item 21. Item 21. The adhesive composition according to any one of Items 1 to 20, wherein the content of the acid-modified polyolefin (A) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 5% by mass or more and 30% by mass or less, more preferably 8% by mass or more and 25% by mass or less, even more preferably 9% by mass or more and 20% by mass or less, and even more preferably 9.5% by mass or more and 17.5% by mass or less. Item 22. The adhesive composition according to any one of Items 1 to 21, wherein the content of the thermoplastic elastomer (B) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 20% by mass or more and 70% by mass or less, more preferably 25% by mass or more and 60% by mass or less, even more preferably 30% by mass or more and 50% by mass or less, and even more preferably 38% by mass or more and 48% by mass or less.Item 23. The adhesive composition according to any one of Items 1 to 22, wherein the content of the tackifier resin (C) relative to the total mass of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) is preferably 20% by mass or more and 70% by mass or less, more preferably 25% by mass or more and 60% by mass or less, even more preferably 30% by mass or more and 55% by mass or less, even more preferably 35% by mass or more and 50% by mass or less, and particularly preferably 38% by mass or more and 48% by mass or less. Item 24. The adhesive composition according to any one of Items 1 to 23, wherein the total content of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) relative to the total mass of the adhesive composition is preferably 5% by mass or more and 55% by mass or less, more preferably 10% by mass or more and 50% by mass or less, even more preferably 15% by mass or more and 45% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less. Item 25. Item 26. The adhesive composition according to any one of Items 1 to 24, further comprising an organic solvent (D). Item 26. The adhesive composition according to Item 25, wherein the content of the organic solvent (D) is preferably 100 parts by mass or more and 5000 parts by mass or less, more preferably 200 parts by mass or more and 4500 parts by mass or less, even more preferably 250 parts by mass or more and 4000 parts by mass or less, still more preferably 300 parts by mass or more and 3500 parts by mass or less, and most preferably 400 parts by mass or more and 3000 parts by mass or less, relative to 100 parts by mass of the acid-modified polyolefin (A). Item 27. Item 27. The adhesive composition according to Item 25 or 26, wherein the organic solvent (D) preferably consists of solvent (D1) and solvent (D2), wherein the solvent (D1) is at least one solvent selected from the group consisting of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and halogenated hydrocarbon solvents, and the solvent (D2) is at least one solvent selected from the group consisting of alcohol solvents, ketone solvents, ester solvents, and glycol ether solvents. Item 28. The adhesive composition according to any one of Items 25 to 27, wherein the organic solvent (D) more preferably consists of solvent (D1) and solvent (D2), wherein the solvent (D1) is an alicyclic hydrocarbon solvent, and the solvent (D2) is a ketone solvent and / or an ester solvent.Item 29. The adhesive composition according to any one of Items 25 to 28, wherein the organic solvent (D) more preferably consists of solvent (D1) and solvent (D2), wherein solvent (D1) is an alicyclic hydrocarbon solvent, and wherein solvent (D2) is an ester solvent. Item 30. The adhesive composition according to any one of Items 27 to 29, wherein the mass ratio of solvent (D1) to solvent (D2) [solvent (D1) / solvent (D2)] is preferably solvent (D1) / solvent (D2)=95 / 5 to 50 / 50, more preferably solvent (D1) / solvent (D2)=90 / 10 to 55 / 45, even more preferably solvent (D1) / solvent (D2)=85 / 15 to 60 / 40, and particularly preferably solvent (D1) / solvent (D2)=80 / 20 to 65 / 35. Item 31. The adhesive composition according to any one of Items 25 to 30, wherein the total content of the acid-modified polyolefin (A), the thermoplastic elastomer (B), the tackifier resin (C), and the organic solvent (D) relative to the total mass of the adhesive composition is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Item 32. The adhesive composition according to any one of Items 1 to 31, further comprising an antioxidant. Item 33. The adhesive composition according to Item 32, wherein the antioxidant is a phenolic antioxidant and / or a phosphorus-based antioxidant. Item 34. The adhesive composition according to any one of Items 1 to 33, wherein the adhesive composition is for use in a decorative film. Item 35. An adhesive layer comprising the adhesive composition according to any one of Items 1 to 34. Item 36. A decorative film having the adhesive layer according to Item 35 and a decorative layer. Item 37. A decorated molded body having the decorative film according to Item 36 and an adherend.

[0115] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Hereinafter, "room temperature" means a temperature within the range of 20°C to 25°C.

[0116] (1) Measurement of Acid Value of Acid-Modified Polyolefin (A) The acid value (mg KOH / g) of the acid-modified polyolefin (A) refers to the amount of potassium hydroxide (KOH) required to neutralize 1 g of the acid-modified polyolefin (A). The oxidation of the acid-modified polyolefin (A) was measured in accordance with the test method of JIS K0070 (1992). Specifically, 1 g of the acid-modified polyolefin (A) was dissolved in 100 g of xylene adjusted to 100 ° C., and then titrated with a 0.1 mol / L potassium hydroxide ethanol solution (trade name "0.1 mol / L ethanolic potassium hydroxide solution", manufactured by Wako Pure Chemical Industries, Ltd.) at 100 ° C. using phenolphthalein as an indicator. At this time, the amount of KOH required for the titration was converted to mg to calculate the acid value (mg KOH / g) of the acid-modified polyolefin (A).

[0117] (2) Measurement of Weight-Average Molecular Weight (Mw) of Acid-Modified Polyolefin (A) The weight-average molecular weight (Mw) of the acid-modified polyolefin (A) was measured using a gel permeation chromatograph Alliance e2695 manufactured by Nippon Waters Co., Ltd. The measurement conditions for gel permeation chromatography (GPC) were as follows: The calibration curve was obtained by dissolving each of the following standard polystyrenes, manufactured by GL Sciences: "Molecular weight standard (lipid-soluble polymer) MW 500: Model 2012-2," "Molecular weight standard (lipid-soluble polymer) MW 2,000: Model 2012-5," "Molecular weight standard (lipid-soluble polymer) MW 10,000: Model 2012-9," "Molecular weight standard (lipid-soluble polymer) MW 20,000: Model 2013-1," "Molecular weight standard (lipid-soluble polymer) MW 50,000: Model 2013-3," and "Molecular weight standard (lipid-soluble polymer) MW 200,000: Model 2013-7," at a concentration of 0.5% to prepare a tetrahydrofuran solution, filtering the solution, placing it in a vial, and measuring the solution. <GPC measurement conditions> Standard substance: polystyrene resin (weight average molecular weight 500, 2,000, 50,000, 200,000) Concentration of acid-modified polyolefin (A): 0.5 mass% Mobile phase: tetrahydrofuran (THF) Column: Shodex KF-806 + KF-803 Column temperature: 40°C Flow rate: 1.0 ml / min Detector: photodiode array detector (wavelength 254 nm = ultraviolet light)

[0118] (3) Measurement of the melting point (Tm) of the acid-modified polyolefin (A) In accordance with JIS K7121-2012, a differential scanning calorimeter (DSC) (manufactured by TA Instruments Japan, Q-2000) was used to measure 5.0 mg of acid-modified polyolefin (A) at -50 ° C. for 5 minutes, and then heated from -50 ° C. to 230 ° C. at a rate of 10 ° C. / min to melt the acid-modified polyolefin (A). Then, the temperature was held at 230 ° C. for 2 minutes, cooled from 230 ° C. to -50 ° C. at a rate of 10 ° C. / min, and then held at -50 ° C. for 2 minutes. The temperature (° C.) at which the apex of the melting peak appeared when melted was taken as the melting point (Tm) of the acid-modified polyolefin (A).

[0119] (4) Measurement of Melt Viscosity of Acid-Modified Polyolefin (A) at 230 ° C. Using a Brookfield viscometer (DV-1), 7.0 g of acid-modified polyolefin (A) was filled into a heated cylinder set at 230 ° C. Ten minutes after filling, a spindle SC4-21 attached to the Brookfield viscometer was inserted into the molten resin in the cylinder, and rotation was started at 3 rpm. Ten minutes after the start of rotation, the rotation speed was appropriately changed so that the torque value of the Brookfield viscometer was in the range of 60 to 80%. After changing the rotation speed, the melt viscosity (mPa s) was measured after a further 25 minutes, 30 minutes, 35 minutes, and 40 minutes, and the average value was taken as the melt viscosity (mPa s) of the acid-modified polyolefin (A) at 230 ° C.

[0120] <Production Examples of Acid-Modified Polyolefin (A)> Production Example 1 Into a 1 L autoclave equipped with a stirrer, 100 parts by mass of propylene-1-butene copolymer (Tm: 80 ° C., weight average molecular weight (Mw): 135,000, propylene component content: 75 mol%, 1-butene component content: 25 mol%), 150 parts by mass of toluene, 20 parts by mass of maleic anhydride, and 4 parts by mass of di-tert-butyl peroxide were added, and nitrogen substitution was performed for 5 minutes. After that, the temperature was raised to 140 ° C. with heating and stirring, and the reaction was carried out at 140 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to 128 ° C. and then poured into a container containing 250 parts by mass of methyl ethyl ketone. The mixture was kept warm in a hot water bath at 40 ° C. and stirred for 10 minutes to precipitate a resin. The slurry from which the resin had precipitated was then cooled in a cold water bath until the internal temperature reached 25 ° C. After cooling, the mixture was centrifuged and subjected to solid-liquid separation to obtain a wet resin. The obtained wet resin was further washed several times with methyl ethyl ketone to remove unreacted maleic anhydride. The obtained resin was dried under reduced pressure at 40°C for 6 hours to obtain a maleic anhydride-modified propylene-1-butene copolymer (A-1), which is an acid-modified polyolefin (A) (propylene component content: 75 mol%, 1-butene component content: 25 mol%, acid value: 22 mgKOH / g, weight-average molecular weight (Mw): 50,000, Tm: 80°C, melt viscosity at 230°C: 1500 mPa s).

[0121] Production Example 2 Into a 1 L autoclave equipped with a stirrer, 100 parts by mass of propylene-1-butene copolymer (Tm: 80 ° C., weight average molecular weight (Mw): 135,000, propylene component content: 75 mol%, 1-butene component content: 25 mol%), 170 parts by mass of toluene, 8.5 parts by mass of maleic anhydride, and 4 parts by mass of di-tert-butyl peroxide were added, and nitrogen substitution was performed for 5 minutes. After that, the temperature was raised to 140 ° C. with heating and stirring, and the reaction was carried out at 140 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to 128 ° C. and then poured into a container containing 250 parts by mass of methyl ethyl ketone. The mixture was kept warm in a hot water bath at 40 ° C. and stirred for 10 minutes to precipitate a resin. The slurry from which the resin had precipitated was then cooled in a cold water bath until the internal temperature reached 25 ° C. After cooling, the mixture was centrifuged and subjected to solid-liquid separation to obtain a wet resin. The obtained wet resin was dried under reduced pressure at 40°C for 6 hours to obtain a maleic anhydride-modified propylene-1-butene copolymer (A-2), which is an acid-modified polyolefin (A) (propylene component content: 75 mol%, 1-butene component content: 25 mol%, acid value: 13 mgKOH / g, weight average molecular weight (Mw): 60,000, Tm: 80°C, melt viscosity at 230°C: 3000 mPa s).

[0122] Production Example 3 A maleic anhydride-modified propylene / 1-butene copolymer (A-3), which is an acid-modified polyolefin (A) (propylene component content: 69 mol%, 1-butene component content: 31 mol%, acid value: 22 mgKOH / g, weight-average molecular weight (Mw): 70,000, Tm: 70°C, melt viscosity at 230°C: 1500 mPa s), was obtained in the same manner as in Production Example 1, except that the propylene / 1-butene copolymer used in Production Example 1 was changed to a propylene / 1-butene copolymer (Tm: 70°C, weight-average molecular weight (Mw): 135,000, propylene component content: 69 mol%, 1-butene component content: 31 mol%).

[0123] Production Example 4 A maleic anhydride-modified propylene-ethylene-1-butene copolymer (A-4), which is an acid-modified polyolefin (A) (propylene component content: 94 mol%, ethylene component content: 3 mol%, 1-butene component content: 3 mol%, acid value: 19 mgKOH / g, weight-average molecular weight (Mw): 70,000, Tm: 130°C, melt viscosity at 230°C: 3000 mPa s), was obtained in the same manner as in Production Example 1, except that the propylene-1-butene copolymer used in Production Example 1 was changed to a propylene-ethylene-1-butene copolymer (Tm: 130°C, weight-average molecular weight (Mw): 70,000, propylene component content: 94 mol%, ethylene component content: 3 mol%, 1-butene component content: 3 mol%).

[0124] Production Example 5 A maleic anhydride-modified propylene-ethylene copolymer (A-5) (propylene component content: 85 mol%, ethylene component content: 15 mol%, acid value: 22 mgKOH / g, weight average molecular weight (Mw): 90,000, Tm: 63°C, melt viscosity at 230°C: 8000 mPa s), which is an acid-modified polyolefin (A), was obtained in the same manner as in Production Example 1, except that the propylene-1-butene copolymer used in Production Example 1 was changed to a propylene-ethylene copolymer (Tm: 63°C, weight average molecular weight (Mw): 135,000, propylene component content: 85 mol%, ethylene component content: 15 mol%).

[0125] Production Example 6 A maleic anhydride-modified propylene-ethylene copolymer (A-6) (propylene component content: 95 mol%, ethylene component content: 5 mol%, acid value: 22 mgKOH / g, weight average molecular weight (Mw): 60,000, Tm: 115°C, melt viscosity at 230°C: 3300 mPa s), which is an acid-modified polyolefin (A), was obtained in the same manner as in Production Example 1, except that the propylene-1-butene copolymer used in Production Example 1 was changed to a propylene-ethylene copolymer (Tm: 122°C, weight average molecular weight (Mw): 135,000, propylene component content: 95 mol%, ethylene component content: 5 mol%).

[0126] The thermoplastic elastomers (B) used in the examples and comparative examples were as follows: Thermoplastic elastomer (B-1): Septon (registered trademark) 2063 (styrene-ethylene-propylene-styrene elastomer, styrene content 13% by mass) manufactured by Kuraray Co., Ltd. Thermoplastic elastomer (B-2): Septon (registered trademark) 2006 (styrene-ethylene-propylene-styrene elastomer, styrene content 34% by mass) manufactured by Kuraray Co., Ltd. Thermoplastic elastomer (B-3): Tufprene (registered trademark) A (styrene-butadiene-styrene elastomer, styrene content 40% by mass) manufactured by Asahi Kasei Corporation Thermoplastic elastomer (B-4): Vistamaxx (registered trademark) 3000 (ethylene / propylene elastomer, styrene content 0% by mass) manufactured by ExxonMobil Corporation

[0127] The tackifying resins (C) used in the examples and comparative examples are as follows: Tackifying resin (C-1): YS Resin (registered trademark) TO-85 (aromatic modified terpene resin, softening point 85°C) manufactured by Yasuhara Chemical Co., Ltd. Tackifying resin (C-2): Pine Crystal (registered trademark) KE-100 (rosin ester resin, softening point 100°C) manufactured by Arakawa Chemical Co., Ltd. Tackifying resin (C-3): YS Resin (registered trademark) TO-125 (aromatic modified terpene resin, softening point 125°C) manufactured by Yasuhara Chemical Co., Ltd.

[0128] The antioxidants used in the examples and comparative examples are as follows: Antioxidant 1: SONGNOX 1010 (phenolic antioxidant) manufactured by SONGWON Co., Ltd. Antioxidant 2: SONGNOX 1680 (phosphorus-based antioxidant) manufactured by SONGWON Co., Ltd.

[0129] Examples 1 to 14, 16, and 17 and Comparative Examples 1 to 10 (Production of Adhesive Composition 1) A 500 mL four-neck flask equipped with a water-cooled reflux condenser and a stirrer was charged with 100 parts by mass of the maleic anhydride-modified propylene-1-butene copolymer A-1 obtained in Production Example 1, 400 parts by mass of thermoplastic elastomer (B-1), 500 parts by mass of tackifier resin (C-1), and 2,400 parts by mass of cyclohexane (D1) and 600 parts by mass of butyl acetate (D2) as organic solvents (D), and the mixture was heated to 70°C with stirring and stirred at 70°C for 1 hour. The mixture was then cooled to room temperature to produce Adhesive Composition 1.

[0130] (Preparation of Adhesive Compositions 2 to 14 and 16 to 27) Adhesive compositions 2 to 11, 14, and 16 to 27 were produced in the same manner as in Example 1, except that the types and amounts of the acid-modified polyolefin (A), thermoplastic elastomer (B), and tackifier resin (C) were changed as shown in Table 1. Furthermore, adhesive compositions 12 and 13 were produced in the same manner as in Example 1, except that the types and amounts of the acid-modified polyolefin (A), thermoplastic elastomer (B), tackifier resin (C), and antioxidant were changed as shown in Table 1. When producing adhesive compositions 2 to 14 and 16 to 27, 2400 parts by mass of cyclohexane (D1) and 600 parts by mass of butyl acetate (D2) were used as the organic solvent (D), as in Example 1.

[0131] (Preparation of Decorative Molded Body) A urethane resin film (Hygress (registered trademark) DUS-202, 100 mm thick, manufactured by Seedom) was used as the substrate for the decorative layer. The adhesive compositions 1 to 14 and 16 to 27 were applied to the urethane resin film using an applicator so that the film thickness after drying was 40 μm. The resulting film was dried for 15 minutes in an 80°C atmosphere using a hot air dryer, resulting in a decorative film (adhesive layer / urethane resin film) in which an adhesive layer (40 μm thick) was formed on the urethane resin film. A polypropylene (PP) test plate (manufactured by Nippon Test Panel Co., Ltd., 2 mm thick) was placed on the adhesive layer of the resulting decorative film (the surface of the adhesive layer opposite the urethane resin film) as an adherend, and the two were bonded together using a heat seal tester manufactured by Tester Sangyo Co., Ltd. (TP-701-B, manufactured by Tester Sangyo Co., Ltd.) at 100°C and 0.2 MPa for 30 seconds. After lamination, the laminate was left to cure at room temperature for one day to produce a decorated molded article (PP test plate / decorative film). The prepared decorated molded article (unstretched decorated molded article) was used as a sample for measuring adhesive strength when unstretched.

[0132] (Preparation of Decorative Molded Body by Vacuum and Compressed Air Forming) A urethane resin film (Hygress® DUS-202, manufactured by Seedom, thickness 100 mm) was used as the substrate for the decorative layer. The adhesive compositions 1-14 and 16-27 were applied to the urethane resin film using an applicator to a dry thickness of 40 μm. The resulting adhesive compositions were dried for 15 minutes at 80°C in a hot air dryer, resulting in a decorative film (adhesive layer / urethane resin film) with an adhesive layer (40 μm thick) formed on the urethane resin film. The resulting decorative film (adhesive layer / urethane resin film) was placed in a stretching mold, and a polypropylene (PP) test plate (manufactured by Nippon Test Panel Co., Ltd., thickness 2 mm) was used as the adherend. The mold and PP test plate were each set in a TOM molding machine "NGF-T-0203" (manufactured by Fuse Vacuum Co., Ltd.). The decorative film (adhesive layer / urethane resin film) in the mold was heated to 100 ° C., and the decorative film was stretched to 1.25 times vertically and 1.25 times horizontally (stretching ratio of 1.25 times in both vertical and horizontal directions), and 2.0 times vertically and 2.0 times horizontally (stretching ratio of 2.0 times in both vertical and horizontal directions). The stretched decorative film was then attached to the PP test plate as the adherend by maintaining it at 50 ° C. for 35 seconds. Then, a stretched decorative molded body (PP test plate / stretched decorative film) was produced by aging it at room temperature for 1 day (24 hours). The two types of stretched decorative molded bodies produced (PP test plate / decorative film stretched vertically and horizontally 1.25 times, and PP test plate / decorative film stretched vertically and horizontally 2.0 times) were used as samples for measuring adhesive strength after stretching.

[0133] Example 15 (Production of Adhesive Composition 15) Adhesive composition 15 was produced in the same manner as in Example 1, except that the types and amounts of the acid-modified polyolefin (A), the thermoplastic elastomer (B), and the tackifier resin (C) were changed as shown in Table 1.

[0134] (Preparation of Decorative Molded Body) A urethane resin film (Hygress (registered trademark) DUS-202, 100 mm thick, manufactured by Seedam) was used as the substrate for the decorative layer. The adhesive composition 15 thus prepared was applied to the urethane resin film using an applicator so that the film thickness after drying was 40 μm. The resulting film was dried for 15 minutes in an 80°C atmosphere using a hot air dryer, yielding a decorative film (adhesive layer / urethane resin film) in which an adhesive layer (40 μm thick) was formed on the urethane resin film. A polypropylene (PP) test plate (manufactured by Nippon Test Panel Co., Ltd., 2 mm thick) was placed on the adhesive layer of the resulting decorative film (the surface of the adhesive layer opposite the urethane resin film) as an adherend, and the two were bonded for 30 seconds at 100°C and 0.2 MPa using a heat seal tester manufactured by Tester Sangyo Co., Ltd. (TP-701-B, manufactured by Tester Sangyo Co., Ltd.). After bonding, the resulting film was aged at room temperature for 1 day to produce a decorative molded body (PP test plate / decorative film). The prepared decorated molded article (unstretched decorated molded article) was used as a sample for measuring adhesive strength when unstretched.

[0135] (Preparation of Decorative Molded Body by Vacuum and Compressed Air Forming) A urethane resin film (Hygress® DUS-202, manufactured by Seedom, thickness 100 mm) was used as the substrate for the decorative layer. The adhesive compositions 1-14 and 16-27 were applied to the urethane resin film using an applicator to a dry thickness of 40 μm. The resulting adhesive compositions were dried for 15 minutes at 80°C in a hot air dryer, resulting in a decorative film (adhesive layer / urethane resin film) with an adhesive layer (40 μm thick) formed on the urethane resin film. The resulting decorative film (adhesive layer / urethane resin film) was placed in a stretching mold, and a polypropylene (PP) test plate (manufactured by Nippon Test Panel Co., Ltd., thickness 2 mm) was used as the adherend. The mold and PP test plate were each set in a TOM molding machine "NGF-T-0203" (manufactured by Fuse Vacuum Co., Ltd.). The decorative film (adhesive layer / urethane resin film) in the mold was heated to 120 ° C., and the decorative film was stretched to 1.25 times vertically and 1.25 times horizontally (stretching ratio of 1.25 times in both vertical and horizontal directions), and 2.0 times vertically and 2.0 times horizontally (stretching ratio of 2.0 times in both vertical and horizontal directions). The stretched decorative film was then attached to the PP test plate as the adherend by maintaining it at 50 ° C. for 35 seconds. Then, a stretched decorative molded body (PP test plate / stretched decorative film) was produced by aging it at room temperature for 1 day (24 hours). The two types of stretched decorative molded bodies produced (PP test plate / decorative film stretched vertically and horizontally 1.25 times, and PP test plate / decorative film stretched vertically and horizontally 2.0 times) were used as samples for measuring adhesive strength after stretching.

[0136] (1) Measurement of adhesive strength The three types of decorative molded bodies (unstretched decorative molded bodies and two types of stretched decorative molded bodies) prepared in Examples 1 to 17 and Comparative Examples 1 to 10 were each cut into 25 mm strips to prepare three types of test pieces of the decorative molded bodies. For the test pieces of the three types of decorative molded bodies prepared, a 180 ° peel test was performed to measure the adhesive strength of the unstretched decorative molded body (adhesive strength when unstretched) (N / 25 mm), the adhesive strength of the stretched decorative molded body (PP test plate / vertical 1.25 times, horizontal 1.25 times stretched decorative film) (adhesive strength after vertical 1.25 times, horizontal 1.25 times stretched) (N / 25 mm), and the adhesive strength of the stretched decorative molded body (PP test plate / vertical 2.0 times, horizontal 2.0 times stretched decorative film) (adhesive strength after vertical 2.0 times, horizontal 2.0 times stretched) (N / 25 mm). The 180° peel test was conducted in accordance with the test method of ASTM-D1876-61, and adhesive strength (N / 25 mm) was measured using a tensile tester (Tensilon RTM-100 manufactured by Orientec Corporation) by pulling vertically at a chuck distance of 40 mm and a pulling rate of 50 mm / min in an environment of 25° C. The measurement was conducted twice, and the average value was used as the adhesive strength (N / 25 mm) of the test pieces of the three types of decorative molded bodies.

[0137] (2) Evaluation of storage stability The viscosity of adhesive compositions 1 to 27 immediately after production was measured using a Brookfield viscometer (TVB-10M manufactured by Toki Sangyo Co., Ltd.). After measurement, adhesive compositions 1 to 27 were each placed in a different glass bottle, sealed, and left to stand at 25°C for one week (168 hours after production). The appearance of adhesive compositions 1 to 27 after standing for one week was visually observed. In addition, the viscosity of adhesive compositions 1 to 27 after standing for one week was measured using a Brookfield viscometer (TVB-10M manufactured by Toki Sangyo Co., Ltd.). The results of visual observation and the viscosity increase (%) represented by the following formula (1) were evaluated according to the following evaluation criteria. An evaluation of "◎" or "◯" indicates that there is no problem in actual use. Viscosity increase (%) = (viscosity of adhesive composition after standing for one week (V Ｉ ) - Viscosity of the adhesive composition immediately after production (V ＩＩ )) / Viscosity of adhesive composition immediately after production (V ＩＩ) × 100 Formula (1) <Evaluation criteria> ⊚: No lumps or gelation occurred, and the viscosity increase was less than 5%. ◯: No lumps or gelation occurred, and the viscosity increase was 5% or more but less than 30%. ×: Lumps or gelation occurred, or the viscosity increase was 30% or more.

[0138]

[0139] [Discussion of the results in Table 1] As shown in Table 1, it was confirmed that the decorative molded articles formed from adhesive compositions 1 to 17 all had good adhesive strength when unstretched. In addition, the decorative molded articles formed from adhesive compositions 1 to 17 were able to maintain good adhesive strength even after being stretched 1.25 times longitudinally and 1.25 times transversely and even after being stretched 2.0 times longitudinally and 2.0 times transversely. Furthermore, it was confirmed that adhesive compositions 4 to 6, 9 to 11, and 14 to 17 exhibited good storage stability, and adhesive compositions 1 to 3, 7, 8, 12, and 13 exhibited excellent storage stability.

[0140] On the other hand, adhesive composition 18 obtained in Comparative Example 1 did not contain a thermoplastic elastomer, resulting in significantly inferior adhesive strength. Adhesive composition 19 obtained in Comparative Example 2 did not contain a tackifier resin, resulting in significantly inferior adhesive strength and storage stability. Adhesive composition 20 obtained in Comparative Example 3 contained less than 100 parts by mass of tackifier resin per 100 parts by mass of acid-modified polyolefin, resulting in significantly inferior storage stability. Adhesive composition 21 obtained in Comparative Example 4 had extremely poor adhesive strength because the melting point (130°C) of the acid-modified polyolefin exceeded 120°C. Adhesive composition 22 obtained in Comparative Example 5 did not contain a styrene-based elastomer, resulting in significantly poor adhesive strength and storage stability. Adhesive compositions 23 and 26 obtained in Comparative Examples 6 and 9 had extremely poor adhesive strength because the tackifier resin content exceeded 600 parts by mass per 100 parts by mass of acid-modified polyolefin. Adhesive composition 24 obtained in Comparative Example 7 had a thermoplastic elastomer content of less than 100 parts by mass relative to 100 parts by mass of acid-modified polyolefin, and therefore showed extremely poor adhesive strength after stretching 2.0 times longitudinally and 2.0 times transversely. Adhesive compositions 25 and 27 obtained in Comparative Examples 8 and 10 had a thermoplastic elastomer content of more than 600 parts by mass relative to 100 parts by mass of acid-modified polyolefin, and therefore showed significantly poor adhesive strength after stretching 1.25 times longitudinally and 1.25 times transversely and after stretching 2.0 times longitudinally and 2.0 times transversely.

[0141] The adhesive composition of this embodiment not only exhibits excellent adhesion to non-polar substrates such as polyolefin substrates, but also to polar substrates, metals, and other substrates different from polyolefin substrates. Furthermore, the resin composition of this embodiment has good storage stability, exhibits good adhesive strength when unstretched, and can maintain good adhesive strength even after stretching. Therefore, decorative films formed from the adhesive composition of this embodiment are suitable for use in vacuum and pressure molding. Furthermore, the adhesive composition of this embodiment can be widely used as an adhesive for bonding various substrates together.

Claims

1. An adhesive composition containing an acid-modified polyolefin (A), a thermoplastic elastomer (B), and a tackifier resin (C), and satisfying all of the following (1) to (4): (1) The melting point of the acid-modified polyolefin (A) is 50 to 120 °C. (2) The content of the tackifier resin (C) is 100 to 600 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin (A). (3) The content of the thermoplastic elastomer (B) is 100 to 600 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin (A). (4) The thermoplastic elastomer (B) contains a styrene-based elastomer.

2. The adhesive composition according to claim 1, wherein the acid value of the acid-modified polyolefin (A) is 2 to 50 mgKOH / g.

3. The adhesive composition according to claim 1, wherein the melt viscosity of the acid-modified polyolefin (A) at 230 °C is 1000 to 10000 mPa·s.

4. The adhesive composition according to claim 1, wherein the tackifier resin (C) is a rosin-based resin or a terpene-based resin.

5. The adhesive composition according to any one of claims 1 to 4, which is for a decorative film.

6. An adhesive layer containing the adhesive composition according to any one of claims 1 to 4.

7. A decorative film having the adhesive layer according to claim 6 and a decorative layer.

8. A decorated molded article having the decorative film according to claim 7 and an adherend.

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