Hot-melt adhesive composition

Abstract

The present invention provides a hot-melt adhesive composition which has the excellent property of bonding polyolefin-based substrates to poly(ethylene terephthalate) (PET) and has excellent high-temperature creep resistance.　This hot-melt adhesive composition comprises an acid-modified polyolefin resin (A), a dimer-acid polyamide resin (B), a styrene-based elastomer (C), and a tackifier resin (D), wherein the content of the acid-modified polyolefin resin (A) is 20-50 parts by mass per 100 parts by mass of all the solid components of the composition. The hot-melt adhesive composition has a melt flow rate at 190°C of 100-1,000 g / 10 min.

Description

Hot melt adhesive composition

[0001] The present invention relates to a hot melt adhesive composition.

[0002] Polyolefin-based substrates such as polypropylene (PP) and propylene-α-olefin copolymers are inexpensive, lightweight, and have excellent strength, chemical resistance, and hydrolysis resistance, making them widely used in a variety of fields, including automobiles and home appliances. In particular, polyolefin-based substrates are becoming increasingly popular in automobile applications, as they are used to reduce the weight of vehicle bodies in order to save energy. Furthermore, in recent years, regulations on organic solvents have become stricter due to their impact on the environment and health, leading to the widespread use of organic solvent-free hot melt adhesives.

[0003] When applying a hot melt adhesive to a polyolefin substrate, it is effective to use a polyolefin resin-based hot melt adhesive in terms of adhesive performance. However, in recent years, there has been an ever-increasing demand for adhesiveness not only between polyolefin substrates but also between polyolefin substrates and polar plastic substrates such as nylon and polyester, and between polyolefin substrates and dissimilar materials such as metals and paper.

[0004] As a hot melt adhesive for bonding a polyolefin substrate to a different material, for example, Patent Document 1 discloses a hot melt adhesive composition suitable for bonding polyolefin resins to each other or between a polyolefin resin and a different material, and discloses that the hot melt adhesive composition comprises a saponified ethylene / vinyl acetate copolymer, a polyamide resin, a polycarboxylic anhydride, a copolymer of ethylene and an acrylic ester, and a tackifier.

[0005] JP 11-92733, JP 2016-511782

[0006] However, in Patent Document 1, the adhesive strength between the highly polar resin substrate and the polyolefin-based substrate is poor, and it is difficult to obtain good adhesiveness and heat creep resistance between a polyethylene terephthalate (PET) substrate, which has a particularly large SP value among highly polar resin substrates, and a non-polar polyolefin-based substrate, which has a small SP value.

[0007] For example, Patent Document 2 discloses a hot melt adhesive containing a reaction product of a modified polyolefin copolymer and a polyamide, which exhibits good adhesion to polyolefin substrates or other substrates (aluminum or steel).

[0008] However, the hot melt adhesive described in Patent Document 2 has low wettability to the substrate and low fluidity, and therefore has a problem of poor adhesion between polyolefin-based substrates and polyethylene terephthalate (PET).

[0009] The present invention was devised to solve the problems of the prior art, and aims to provide a hot melt adhesive composition that has excellent adhesion between polyolefin substrates and polyethylene terephthalate (PET) and also has excellent heat creep resistance.

[0010] That is, the present invention has the following configurations. Item 1. A hot melt adhesive composition comprising an acid-modified polyolefin resin (A), a dimer acid polyamide resin (B), a styrene-based elastomer (C), and a tackifier resin (D), wherein the content of the acid-modified polyolefin resin (A) is 20 to 50 parts by mass per 100 parts by mass of the total solids content in the composition, and wherein the melt flow rate at 190°C is 100 g / 10 min to 1000 g / 10 min. Item 2. The hot melt adhesive composition according to Item 1, wherein the content of the dimer acid polyamide resin (B) is 30 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the acid-modified polyolefin resin (A). Item 3. The hot melt adhesive composition according to Item 1 or 2, wherein the acid-modified polyolefin (A) has a melting point of 50°C to 130°C. Item 4. Item 5. The hot melt adhesive composition according to any one of Items 1 to 3, wherein the acid-modified polyolefin resin (A) has an acid value of 5 to 50 mgKOH / g. Item 6. The hot melt adhesive composition according to any one of Items 1 to 4, wherein the dimer acid polyamide resin (B) has an amine value of 0.1 to 10 mgKOH / g. Item 7. The hot melt adhesive composition according to any one of Items 1 to 5, wherein the dimer acid polyamide resin (B) has a softening point of 100°C to 200°C. Item 8. The hot melt adhesive composition according to any one of Items 1 to 6, wherein the styrene-based elastomer (C) has a Shore A hardness of 60 or less. Item 9. The hot melt adhesive composition according to any one of Items 1 to 7, wherein the styrene-based elastomer (C) is contained in an amount of 10 to 80 parts by mass per 100 parts by mass of the total amount of the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B). Item 10. Item 10. The hot melt adhesive composition according to any one of items 1 to 8, wherein the tackifier resin (D) is a terpene resin. Item 11. An adhesive body formed by bonding a polyolefin substrate and a polyethylene terephthalate (PET) substrate with an adhesive comprising the hot melt adhesive composition according to any one of items 1 to 9.

[0011] According to the present invention, it is possible to provide a hot melt adhesive composition that has excellent adhesion between polyolefin-based substrates and polyethylene terephthalate (PET) and also has excellent heat creep resistance.

[0012] FIG. 1 is a diagram showing a measurement method for a heat creep resistance test.

[0013] (Hot melt adhesive composition) The hot melt adhesive composition of the present invention contains, as essential components, an acid-modified polyolefin resin (A), a dimer acid polyamide resin (B), a styrene-based elastomer (C), and a tackifier resin (D). The content of the acid-modified polyolefin resin (A) is 20 to 50 parts by mass per 100 parts by mass of the total solids content in the composition, and the hot melt adhesive composition is characterized by having a melt flow rate at 190°C of 100 g / 10 min to 1,000 g / 10 min.

[0014]

[0009] The inventors have independently discovered through research and development that the inclusion of the above-mentioned essential components enables the formation of a sea-island structure, thereby exhibiting good wettability of the adhesive to the substrate and good compatibility of the adhesive components. Furthermore, the inventors have discovered that by including a specific content of acid-modified polyolefin resin (A) in the adhesive components and configuring the adhesive components so that the melt flow rate at 190°C is within a specific range, good fluidity can be achieved, a phase structure can be formed that is good for bonding substrates with large differences in SP value, and good adhesion between polyolefin substrates and polyethylene terephthalate (PET) and heat creep resistance can be obtained.

[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, the term "solid content" refers to components contained in the hot melt adhesive composition that are solid at room temperature (23°C), and does not include solvents, diluents, etc. that are liquid at room temperature. Specific examples of the solid content in this specification include the acid-modified polyolefin resin (A), the dimer acid polyamide resin (B), the styrene-based elastomer (C), and the tackifier resin (D).

[0019] <Acid-Modified Polyolefin Resin (A)> The present invention contains an acid-modified polyolefin resin (A). The acid-modified polyolefin resin (A) is not particularly limited, and is preferably a polymer obtained by graft polymerizing an α,β-unsaturated carboxylic acid and / or its acid anhydride onto a polyolefin resin. In other words, the acid-modified polyolefin resin (A) is preferably a graft polymer having a structure in which an α,β-unsaturated carboxylic acid and / or its acid anhydride is grafted onto a polyolefin resin.

[0020] Polyolefin resins typically have structural units derived from α-olefins, such as α-olefins having 2 to 20 carbon atoms (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms), such as ethylene, propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0021] The polyolefin resin may be an olefin polymer containing one type of structural unit derived from an α-olefin, or may be a copolymer of an olefin polymer containing two or more types of structural units derived from an α-olefin.

[0022] In one embodiment, the polyolefin resin is typically a petroleum-derived polyolefin resin, which is a polyolefin-based resin synthesized from petroleum-derived olefins.

[0023] Petroleum-derived olefins are olefins produced by thermal cracking of petrochemical raw materials such as naphtha, ethane, LPG (Liquefied Petroleum Gas), NGL (Natural Gas Liquid), and gas oil.

[0024] In one embodiment, examples of the polyolefin resin constituting the acid-modified polyolefin resin (A) include homopolypropylene (propylene homopolymer), propylene-α-olefin copolymer, homopolyethylene (ethylene homopolymer), ethylene-α-olefin copolymer, homopoly-1-butene, 1-butene-α-olefin copolymer, etc. These polyolefin resins can be used alone or in combination of two or more. Among these polyolefin resins, homopolypropylene and / or propylene-α-olefin copolymer are preferred, and propylene-α-olefin copolymer is more preferred.

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

[0026] Propylene-α-olefin copolymers are copolymers of propylene and α-olefins. Examples of α-olefins include ethylene; α-olefins having 4 to 20 carbon atoms (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms), such as 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. These α-olefins can be used alone or in combination of two or more. Of these, 1-butene is preferred as the α-olefin.

[0027] The content of the propylene component in the propylene-α-olefin copolymer is preferably 50 mol% or more, more preferably 55 mol% or more, even more preferably 60 mol% or more, still 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 water resistance and adhesion to polyolefin substrates (particularly polypropylene substrates) of the modified polyolefin resin composition of this embodiment become even better.

[0028] In one embodiment, the polyolefin resin may be a bio-derived polyolefin resin instead of a petroleum-derived polyolefin resin. The bio-derived polyolefin resin refers to a polyolefin resin produced from a biological resource (biomass). Biomass refers to a polyolefin resin formed from a renewable biological organic resource excluding fossil resources.

[0029] When a bio-derived polyolefin resin is used, it is preferable that the polyolefin resin contains a propylene structural unit. When a bio-derived polyolefin resin is used, the biomass degree of the polyolefin resin is usually 25% or more, preferably 27% or more, and more preferably 30% or more. The upper limit of the biomass degree is not particularly limited as long as it is 100% or less. The biomass degree of the polyolefin resin can be calculated, for example, from the content of carbon isotope with mass number 14 measured in accordance with ASTM D6866.

[0030] Examples of the α,β-unsaturated carboxylic acid and / or its acid anhydride to be graft polymerized onto the polyolefin resin constituting the acid-modified polyolefin resin (A) include maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, mesaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, himic anhydride, etc. Among these α,β-unsaturated carboxylic acids or acid anhydrides thereof, maleic acid, maleic anhydride and itaconic anhydride are preferred, and maleic acid and maleic anhydride are more preferred.

[0031] The method for graft polymerizing an α,β-unsaturated carboxylic acid and / or its acid anhydride onto a polyolefin resin is not particularly limited, and examples thereof include a radical graft reaction (a reaction in which, in the presence of a radical generator, radical species are generated on a polyolefin that serves as a main chain, and the unsaturated carboxylic acid and the acid anhydride are 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 resin (A) is preferably 50°C to 130°C. It is more preferably 55°C or higher, even more preferably 60°C or higher, and particularly preferably 65°C or higher. It is also more preferably 110°C or lower, even more preferably 100°C or lower, and most preferably 95°C or lower. A melting point of 50°C to 130°C or higher results in stronger cohesive force derived from crystals and higher fluidity, resulting in better adhesion. In addition, the open time from heating to lamination can be extended, improving workability.

[0034] The melting point (Tm) of the acid-modified polyolefin resin (A) can be measured by a differential scanning calorimeter (DSC) in accordance with JIS K7121-2012. Specific measurement methods will be described in the examples below.

[0035] The acid value of the acid-modified polyolefin resin (A) is preferably in the range of 5 to 50 mgKOH / g, more preferably 5 to 40 mgKOH / g, even more preferably 5 to 30 mgKOH / g, and most preferably 5 to 16 mgKOH / g. When the acid value is 5 mgKOH / g or more, the acid-modified polyolefin resin (A) exhibits even greater adhesive strength to polyolefin substrates. Furthermore, the dimer acid polyamide resin (B) in the hot melt adhesive composition can be efficiently dispersed, resulting in the formation of a favorable sea-island structure. When the acid value is 50 mgKOH / g or less, the cohesive strength of the acid-modified polyolefin resin (A) is increased, resulting in even greater improvement in adhesive strength.

[0036] The acid value of the acid-modified polyolefin resin (A) can be measured, for example, in accordance with the test method of JIS K0070-1992. A specific measurement method will be described in the examples below.

[0037] In one embodiment, the weight-average molecular weight (Mw) of the acid-modified polyolefin resin (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 weight-average molecular weight is 10,000 or more, the cohesive strength of the acid-modified polyolefin resin (A) is exerted, resulting in better adhesive properties. Furthermore, when the weight-average molecular weight is 200,000 or less, the fluidity of the acid-modified polyolefin resin (A) is high, forming a good phase structure in the adhesive composition, resulting in better adhesive properties. Workability is also improved. Furthermore, the acid-modified polyolefin resin (A) has good wettability to substrates, resulting in improved adhesive strength.

[0038] The weight average molecular weight (Mw) of the acid-modified polyolefin resin (A) can be measured by gel permeation chromatography (GPC) and converted from a polystyrene calibration curve. GPC measurement is carried out by a conventionally known method using a commercially available device with THF or the like as a solvent. Specific measurement methods will be described in the examples below.

[0039] In one embodiment, the melt viscosity of the acid-modified polyolefin resin (A) at 190°C is preferably in the range of 1,000 mPa·s to 10,000 mPa·s. It is more preferably in the range of 1,500 mPa·s to 9,000 mPa·s, even more preferably 1,800 mPa·s to 8,000 mPa·s, and most preferably 2,200 mPa·s to 7,000 mPa·s. When the acid-modified polyolefin resin (A) has a melt viscosity at 190°C of 10,000 mPa·s or less, the wettability of the hot melt adhesive composition to the substrate is improved, and the adhesiveness is further improved. Furthermore, when the melt viscosity at 190°C is 1,000 mPa·s or more, the dimer acid polyamide resin (B) in the hot melt adhesive composition can be efficiently dispersed, forming a good sea-island structure and further improving the adhesiveness to the substrate. Specific methods for measuring the melt viscosity will be described in the examples below.

[0040] <Dimer Acid Polyamide Resin (B)> The present invention contains a dimer acid polyamide resin (B). The dimer acid polyamide resin (B) has an amide bond in the main chain and is obtained mainly by a dehydration condensation reaction using a dicarboxylic acid component and a diamine component. The dimer acid polyamide resin (B) uses a dimer acid as the dicarboxylic acid component. Here, the dimer acid is obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms, such as oleic acid or linoleic acid. For example, a dimer acid whose unsaturated double bond has been hydrogenated to reduce the degree of unsaturation may be used.

[0041] As the dimer acid, for example, commercially available Haridimer series (manufactured by Harima Chemicals Co., Ltd.), Pripol series (manufactured by Croda Japan Co., Ltd.), Tsunodim series (manufactured by Tsuno Foods Industries Co., Ltd.), etc. can be used.

[0042] Compared to widely used polyamide resins such as nylon 6, nylon 66, and nylon 12, the dimer acid polyamide resin (B) has a large hydrocarbon group and therefore excellent flexibility, resulting in good wettability to substrates and high adhesive properties. By including the dimer acid polyamide resin (B) in the adhesive composition of the present invention, the adhesive composition has good fluidity and a good phase structure. Furthermore, the adhesive composition can have excellent heat resistance and good heat creep resistance.

[0043] The content of dimer acid constituting the dimer acid polyamide resin (B) is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more, relative to 100 mol% of the dicarboxylic acid component. When the content of dimer acid is 50 mol% or more, the properties and effects of the dimer acid polyamide resin (B) can be more effectively exhibited.

[0044] As the dicarboxylic acid component other than the dimer acid, a C4 to C60 dicarboxylic acid can be used, such as adipic acid, azelaic acid, succinic acid, dodecanedioic acid, glutaric acid, maleic acid, sebacic acid, pimelic acid, suberic acid, nonanedicarboxylic acid, fumaric acid, undecanedioic acid, or a mixture thereof.

[0045] The content of the dicarboxylic acid component other than the dimer acid is preferably less than 50 mol%, more preferably 25 mol% or less, based on 100 mol% of the dicarboxylic acid component. This makes it easier to control the softening point and adhesiveness of the dimer acid polyamide resin (B). Note that monomer acid (having 18 carbon atoms), which is a monomer, trimer acid (having 54 carbon atoms), other polymerized fatty acids having 20 to 54 carbon atoms, etc. are not included in the dimer acid referred to in the present invention, but are included in the other dicarboxylic acid component.

[0046] Examples of the diamine component constituting the dimer acid polyamide resin (B) include ethylenediamine, hexamethylenediamine, tetramethylenediamine, pentamethylenediamine, m-xylenediamine, phenylenediamine, diethylenetriamine, and piperazine. Among these, ethylenediamine, hexamethylenediamine, diethylenetriamine, m-xylenediamine, piperazine, and mixtures thereof are particularly preferred.

[0047] The diamine component and the dimer acid or dicarboxylic acid component are subjected to thermal condensation, followed by an amidation process accompanied by dehydration, to produce a dimer acid polyamide. The polymerization method used for thermal condensation can be a conventionally known method, and is not particularly limited, but generally, the reaction temperature is about 100 to 300°C, and the reaction time is about 1 to 8 hours. When polymerizing the dimer acid polyamide resin (B), the degree of polymerization, acid value, amine value, etc. of the resin can be controlled by adjusting the charging ratio of the dicarboxylic acid component and the diamine component.

[0048] In one embodiment, the dimer acid polyamide resin (B) preferably has an amine value of 0.1 to 10 mgKOH / g. It is more preferably 0.1 to 5 mgKOH / g, even more preferably 0.2 to 3 mgKOH / g, and most preferably 0.3 to 2 mgKOH / g. If the amine value exceeds 10 mgKOH / g, the dimer acid polyamide resin (B) and the acid-modified polyolefin resin (A) may react to form three-dimensional crosslinks, resulting in reduced wettability and reduced adhesive properties of the hot melt adhesive composition. By having the amine value of the dimer acid polyamide resin (B) be 0.1 to 10 mgKOH / g, the adhesion to polyethylene terephthalate (PET) and heat creep resistance are improved. The amine value is the equivalent amount of hydrochloric acid required to neutralize 1 g of sample, expressed in milligrams of potassium hydroxide, and is determined according to the method of ASTM-D-2074.

[0049] In one embodiment, the softening point of the dimer acid polyamide resin (B) is preferably 100°C to 200°C. More preferably, it is 110°C to 190°C, and even more preferably, it is 115°C to 180°C. When the softening point of the dimer acid polyamide resin (B) is 100°C to 200°C, the wettability and phase structure of the hot melt adhesive composition are improved, and the adhesiveness to polyethylene terephthalate (PET) in particular is improved. The heat creep resistance properties are also improved. The softening point can be measured by the standard ring and ball method in accordance with ASTM E28.

[0050] <Styrene-Based Elastomer (C)> The present invention contains a styrene-based elastomer (C). The inclusion of the styrene-based elastomer (C) reduces internal stress in the adhesive and improves the compatibility between the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B) and tackifier resin (D), thereby improving adhesion to substrates. Furthermore, it is possible to form a phase structure that is favorable for bonding substrates with large differences in SP value, thereby providing good adhesion between polyolefin substrates and polyethylene terephthalate (PET). Examples of the styrene-based elastomer (C) include styrene elastomer, styrene-butadiene resin, styrene-ethylene-propylene resin, styrene-isoprene-butadiene-styrene resin, and styrene-isoprene-styrene resin. The styrene-based elastomer may be hydrogenated. Preferred examples of hydrogenated styrene-based elastomers include styrene-ethylene-butylene-styrene resin and styrene-ethylene-propylene-styrene resin. The styrene-based elastomer may also be acid-modified.

[0051] In addition to the styrene-based elastomer (C) of the present invention, the composition may further contain, for example, an olefin-based elastomer, an alkene-based elastomer, a vinyl chloride-based elastomer, a urethane-based elastomer, an amide-based elastomer, and the like, as long as the effects of the present invention are not impaired. Each of these may be used alone or in combination of two or more.

[0052] The Shore A hardness of the styrene-based elastomer (C) used in the present invention is preferably 60 or less, more preferably 50 or less, even more preferably 45 or less, and particularly preferably 40 or less. A Shore A hardness of 60 or less further reduces internal stress in the adhesive, and improves compatibility with the acid-modified polyolefin resin (A), dimer acid polyamide resin (B), and tackifier resin (D), thereby further improving adhesion to substrates. Furthermore, a good phase structure can be formed by adhering substrates with large differences in SP value, resulting in better adhesion between polyolefin-based substrates and polyethylene terephthalate (PET). Shore A hardness can be measured according to JIS K7215.

[0053] The density of the styrene elastomer (C) is 0.88 to 0.99 g / cm ３ More preferably, it is in the range of 0.89 to 0.91 g / cm ３ Within this range, the difference in specific gravity from the acid-modified polyolefin resin (A) does not become too large, and the storage stability tends to be good.

[0054] <Tackifier Resin (D)> The adhesive composition of the present invention contains a tackifier resin (D). By including a tackifier resin, the tackiness of the surface after application of the adhesive can be maintained, and the adhesion to the substrate can be improved.

[0055] The softening point of the tackifier resin (D) used in the present invention is preferably 60°C or higher. More preferably, it is 65°C or higher, even more preferably, 70°C or higher, and most preferably, 75°C or higher. It is also preferably 200°C or lower, even more preferably, 180°C or lower, and most preferably, 150°C or lower. When the softening point is 60°C or higher, the tackifier resin (D) is less likely to bleed out onto the surface at room temperature, resulting in a smooth surface and better adhesive properties. When the softening point is 200°C or lower, the wettability to the substrate is improved and better adhesive properties are obtained.

[0056] Examples of the tackifying resin (D) used in the present invention include petroleum resins (aliphatic, alicyclic, aromatic, etc.), terpene resins (polymers of α-pinene, β-pinene, limonene, etc.), aromatic hydrocarbon-modified terpene resins, rosin-based resins (gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, maleated rosin, rosin ester, etc.), and terpene phenol resins, and these can be used either alone or in combination of two or more.

[0057] In the present invention, the tackifier resin (D) is preferably a terpene resin, from the viewpoints of excellent compatibility with the acid-modified polyolefin resin (A), better adhesion to polyolefin substrates and polyethylene terephthalate (PET), and better adhesive strength at high temperatures.

[0058] <Hot Melt Adhesive Composition> The 190°C melt flow rate (MFR) of the hot melt adhesive composition of the present invention is in the range of 100 g / 10 min to 1,000 g / 10 min. It is preferably 200 g / 10 min to 800 g / 10 min, more preferably 250 g / 10 min to 600 g / 10 min. It is even more preferably 300 g / 10 min to 550 g / 10 min. A 190°C melt flow rate (MFR) of 100 g / 10 min or more improves wettability to the substrate, resulting in good adhesion to the substrate. Furthermore, it is possible to form a phase structure that is good for bonding substrates with large differences in SP value, and the composition has good adhesion and heat creep resistance between polyolefin substrates and polyethylene terephthalate (PET). Good fluidity and a good phase structure are obtained, improving adhesive strength. A 190°C melt flow rate (MFR) in this range results in better adhesion and improved handling during coating. The 190°C melt flow rate (MFR) can be measured by the method specified in JIS K7210-2014. The measurement temperature is 190°C, and the load is 2.16 kg unless otherwise specified.

[0059] The present invention contains 20 to 50 parts by mass of acid-modified polyolefin resin (A) per 100 parts by mass of the total solids content of the hot melt adhesive composition. By containing the acid-modified polyolefin resin (A) in this range, a good sea-island structure is formed, resulting in excellent adhesion to polyolefin substrates and excellent heat creep resistance. Furthermore, it is possible to form a phase structure that is good for bonding substrates with large differences in SP value, and good adhesion between polyolefin substrates and polyethylene terephthalate (PET) is achieved. Preferably, the content of the acid-modified polyolefin resin (A) is 25 to 45 parts by mass, more preferably 28 to 42 parts by mass, per 100 parts by mass of the total solids content of the hot melt adhesive composition.

[0060] In one embodiment, the content of the acid-modified polyolefin resin (A) is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and even more preferably 28 to 42% by mass, based on 100% by mass of the hot melt adhesive composition. By including the acid-modified polyolefin resin (A) in this range, it becomes easier to form a good sea-island structure, resulting in better adhesion to polyolefin substrates and better heat creep resistance. Furthermore, it becomes more possible to form a phase structure that is good for bonding substrates with large differences in SP value, resulting in better adhesion between polyolefin substrates and polyethylene terephthalate (PET).

[0061] In one embodiment, the content of the acid-modified polyolefin resin (A) is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and even more preferably 28 to 42% by mass, based on 100% by mass of the total content of the acid-modified polyolefin resin (A), dimer acid polyamide resin (B), styrene-based elastomer (C), and tackifier resin (D). By including the acid-modified polyolefin resin (A) in this range, a favorable sea-island structure is more easily formed, resulting in superior adhesion to polyolefin substrates and superior heat creep resistance. Furthermore, a favorable phase structure can be more easily formed for bonding substrates with large differences in SP value, resulting in superior adhesion between polyolefin substrates and polyethylene terephthalate (PET).

[0062] In the present invention, the content of the dimer acid polyamide resin (B) is preferably 30 parts by mass or more relative to 100 parts by mass of the acid-modified polyolefin resin (A) from the viewpoint of improving compatibility with the acid-modified polyolefin resin (A), adhesion to polyolefin substrates and polyethylene terephthalate (PET), and heat creep resistance, and from the viewpoint of forming a phase structure that is good for adhesion to substrates with large differences in SP value. More preferably, the content of the dimer acid polyamide resin (B) is 40 parts by mass or more relative to 100 parts by mass of the acid-modified polyolefin resin (A), even more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more. Furthermore, the content of the dimer acid polyamide resin (B) is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less relative to 100 parts by mass of the acid-modified polyolefin resin (A). Even more preferably, it is 90 parts by mass or less.

[0063] In one embodiment, the content of the styrene-based elastomer (C) is preferably 10 to 80 parts by mass per 100 parts by mass of the total content of the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B), from the viewpoints of further improving the compatibility between the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B), alleviating stress at the adhesive interface, further improving adhesion to the substrate, and forming a phase structure favorable for adhesion to substrates with a large difference in SP value. More preferably, the content of the styrene-based elastomer (C) is 15 to 70 parts by mass, even more preferably 20 to 65 parts by mass, even more preferably 25 to 60 parts by mass, and particularly preferably 30 to 55 parts by mass per 100 parts by mass of the total content of the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B).

[0064] In one embodiment, the content of the tackifier resin (D) relative to the total content of the acid-modified polyolefin resin (A), the dimer acid polyamide resin (B), the styrene-based elastomer (C), and the tackifier resin (D) being 100% by mass, is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 15 to 30% by mass, from the viewpoint of improving wettability to the substrate and improving adhesive strength.

[0065] In one embodiment, the total content of the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B) is preferably 40 to 80% by mass, more preferably 45 to 70% by mass, and even more preferably 50 to 65% by mass, relative to 100% by mass of the total content of the acid-modified polyolefin resin (A), the dimer acid polyamide resin (B), the styrene-based elastomer (C), and the tackifier resin (D).

[0066] In one embodiment, the total content of the acid-modified polyolefin resin (A), the dimer acid polyamide resin (B), the styrene-based elastomer (C), and the tackifier resin (D) relative to the total mass of the hot melt adhesive composition is preferably 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more, in that order. It may also be 100% by mass.

[0067] In one embodiment, it is preferable to add an antioxidant to the hot melt adhesive composition. Examples of preferred antioxidants include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and amine-based antioxidants. These antioxidants can be used alone or in combination of two or more. A combination of a hindered phenol-based antioxidant with another antioxidant is particularly effective. It is also desirable to add stabilizers such as heat aging inhibitors, copper inhibitors, antistatic agents, light stabilizers, and ultraviolet absorbers. The use of phenol-based antioxidants containing a phosphorus atom in the molecule is particularly desirable because they allow for efficient radical capture. Furthermore, nucleating agents, flame retardants, and the like can also be added.

[0068] Examples of hindered phenolic antioxidants and stabilizers include 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,1,3-tri(4-hydroxy-2-methyl-5-t-butylphenyl)butane, 1,1-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-benzenepropanoic acid, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4 -hydroxyphenyl)propionate], 3-(1,1-dimethylethyl)-4-hydroxy-5-methyl-benzenepropanoic acid, 3,9-bis[1,1-dimethyl-2-[(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-trimethyl-2,4,6-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)benzene, thiodiethylenebis[3-(3, 5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexane-1,6diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 3,3',3",5,5'5"-hexa-tert-butyl-a,a',a"-(mesitylene-2,4,6triyl)tri-p-cresol, diethyl [[3,5-bis[1,1-dimethyl ethyl]-4-hydroxyphenyl]methyl]phosphate, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 2'3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro[5.5]undecane, and the like.

[0069] Examples of phosphorus-based antioxidants and stabilizers include 3,9-bis(p-nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tri(mononylphenyl)phosphite, triphenoxyphosphine, isodecyl phosphite, isodecylphenyl phosphite, diphenyl 2-ethylhexyl phosphite, dinonylphenyl bis(nonylphenyl) ester phosphorus acid, 1,1,3-tris(2-methyl-4-ditridecylphosphite-5-t-butylphenyl)butane, tris(2,4-di-tert-butylphenyl)phosphite, pentaerythritol bis(2,4-di- tert-butylphenyl phosphite), 2,2'-methylenebis(4,6-di-tert-butylphenyl)2-ethylhexyl phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis[2,4-bis[1,1-dimethylethyl]-6-methylphenyl]ethyl ester phosphorous acid, 6-[3-(3-tert-butyl-4-hydroxy-5-methyl)propoxy]-2,4,8,10-tetra-tert-butyldibenz[d,f][1,3,2]-dioxaphosphepine, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and the like.

[0070] Examples of sulfur-based antioxidants and stabilizers include 4,4'-thiobis[2-tert-butyl-5-methylphenol]bis[3-(dodecylthio)propionate], thiobis[2-(1,1-dimethylethyl)-5-methyl-4,1-phenylene]bis[3-(tetradecylthio)propionate], pentaerythritol tetrakis(3-n-dodecylthiopropionate), bis(tridecyl)thiodipropionate, didodecyl-3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate, 4,6-bis(octylthiomethyl)-o-cresol, and 4,4-thiobis(3-methyl-6-tert-butylphenol).

[0071] Examples of amine antioxidants and stabilizers include 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, N,N'-di-2 naphthyl-p-phenylenediamine, N-phenyl-N'-4,4'-thiobis(2-t-butyl-5-methylphenol), and 2,2-bis[3-(dodecylthio)propanoyloxymethyl]-1,3-propanediol bis[3-(dodecylthio)propionate].

[0072] The amount of antioxidant added is preferably 0.1% by mass or more and 5% by mass or less based on the total amount of the hot melt adhesive composition, from the viewpoint of improving the effect of preventing thermal degradation. Addition of an antioxidant in an amount exceeding 5% by mass may adversely affect adhesion, etc.

[0073] In one embodiment, other resins such as epoxy resins, polyamide resins, polyolefin resins, polycarbonate resins, acrylic resins, ethylene vinyl acetate resins, and phenolic resins can be blended into the hot melt adhesive composition as long as the performance of the present invention is not impaired. In this case, adhesion, flexibility, durability, and the like may be improved. The amount of other resins blended is preferably less than 5% by mass of the entire hot melt adhesive composition. Furthermore, curing agents such as isocyanate compounds and melamine, fillers such as talc and mica, pigments such as carbon black and titanium oxide, and flame retardants such as antimony trioxide and brominated polystyrene may also be blended.

[0074] The adhesive composition of the present invention exhibits good adhesion between a polyolefin substrate and polyethylene terephthalate (PET). When the adhesive composition of the present invention is molded to a thickness of 20 μm, the adhesive strength is preferably 10 N / 25 mm or more, more preferably 15 N / 25 mm, and even more preferably 20 N / 25 mm. The adhesive strength can be measured in accordance with the peel test method of JIS K6854-2. Specific measurement methods will be described in the examples below.

[0075] The hot melt adhesive composition of the present invention has good adhesion and heat creep resistance when bonding a polyolefin substrate to polyethylene terephthalate (PET). Furthermore, since the hot melt adhesive composition of the present invention has good adhesion when bonding substrates having a large difference in SP value, it can also be favorably used for bonding highly polar resin substrates other than polyethylene terephthalate (PET), such as polyvinyl chloride (PVC) and polyurethane (PU), to polyolefin substrates, and between polyolefin substrates.

[0076] The adhesive article of the present invention can be obtained by bonding a polyolefin substrate to polyethylene terephthalate (PET) using an adhesive comprising the hot melt adhesive composition described above. Applications of the adhesive article include sheets, films, and molded articles in the fields of automobiles, home appliances, electronic materials, food, and medicine.

[0077] (Polyolefin-Based Substrate) The polyolefin-based substrate can be appropriately selected from conventionally known polyolefin-based substrates, such as polyethylene, polypropylene, and ethylene-propylene copolymers.

[0078] (Method for producing hot melt adhesive composition) The method for producing the hot melt adhesive composition of the present invention is not particularly limited, and includes, for example, a method of melt-kneading using an extruder such as a single-screw extruder or a twin-screw extruder, and a method of melt-kneading using a batch kneader. A method using a twin-screw extruder that can apply high shear stress is particularly preferred. When using a twin-screw extruder, it is preferable to melt-knead at a temperature higher than the melting point or softening point of each raw material used, specifically, melt-kneading at 150 to 300°C.

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0080] <Acid-Modified Polyolefin Resin (A)> (1) Measurement of Acid Value of Acid-Modified Polyolefin Resin (A) The acid value (mg KOH / g) of the acid-modified polyolefin resin (A) in the present invention is the amount of KOH required to neutralize 1 g of the acid-modified polyolefin resin (A), and was measured in accordance with the test method of JIS K0070 (1992). Specifically, 1 g of the acid-modified polyolefin resin was dissolved in 100 g of xylene adjusted to 100 ° C., and then titrated at the same temperature 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.] using phenolphthalein as an indicator. At this time, the amount of potassium hydroxide required for the titration was converted to mg to calculate the acid value (mg KOH / g).

[0081] (2) Measurement of Weight Average Molecular Weight (Mw) of Acid-Modified Polyolefin Resin (A) The weight average molecular weight (Mw) of the acid-modified polyolefin resin (A) was measured using a gel permeation chromatograph Alliance e2695 (hereinafter referred to as GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran, 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) manufactured by Nihon Waters K.K.

[0082] (3) Measurement of Melting Point of Acid-Modified Polyolefin Resin (A) The melting point (Tm) of the acid-modified polyolefin resin (A) was measured in accordance with JIS K7121-2012 using a differential scanning calorimeter (Q-2000, manufactured by T.A. Instruments Japan, hereinafter sometimes referred to as DSC) by holding about 5 mg of a sample at −50° C. for 5 minutes, then raising the temperature at a rate of 10° C. / min to melt the sample, and then maintaining the heated-molten state at 230° C. for 2 minutes. The temperature was then lowered at a rate of 10° C. / min, and the sample was stabilized at −50° C., and the temperature was again raised at a rate of 10° C. / min to measure the top temperature of the melting peak when melted, and the melting peak temperature was evaluated.

[0083] (4) Measurement of Melt Viscosity of Acid-Modified Polyolefin Resin (A) The melt viscosity of the acid-modified polyolefin resin (A) was measured using a Shimadzu flow tester (CFT-500C type) by filling a cylinder at the center of a heater set at 190°C with an acid-modified polyolefin resin sample dried to a moisture content of 0.1% or less. After 3 minutes of filling, pressure (4.9 MPa) was applied to the sample via a plunger, and the molten sample was extruded from a die (hole diameter: 0.5 mm, thickness: 20 mm) at the bottom of the cylinder. The plunger's descent distance and descent time were recorded, and the melt viscosity (mPa s) was calculated.

[0084] (Production Example 1) 100 parts by mass of polyolefin resin 1, 8 parts by mass of maleic anhydride, 2 parts by mass of dicumyl peroxide, and 150 parts by mass of toluene were placed in an autoclave equipped with a stirrer, and after sealing, the autoclave was purged with nitrogen for 5 minutes. Thereafter, the reaction was carried out for 5 hours at 140°C while heating and stirring. After completion of the reaction, the reaction solution was poured into a large amount of methyl ethyl ketone to precipitate a resin. The precipitated resin was removed, washed several times with methyl ethyl ketone, and then dried to obtain an acid-modified polyolefin resin (A-1). The composition and properties are shown in Table 1.

[0085] (Production Examples 2 and 3) Acid-modified polyolefin resins (A-2) and (A-3) were obtained in the same manner as in the production example for the acid-modified polyolefin resin (A-1), except that the type of polyolefin resin was changed as shown in Table 1. The composition and resin properties of each acid-modified polyolefin resin (A) are shown in Table 1.

[0086]

[0087] <Polyolefin resins> Polyolefin resin 1: propylene-butene (=70 / 30 (molar ratio)) copolymer (weight average molecular weight (Mw) 230,000) Polyolefin resin 2: propylene-butene (=90 / 10 (molar ratio)) copolymer (weight average molecular weight (Mw) 180,000) Polyolefin resin 3: propylene-ethylene-butene (=94 / 3 / 3 (molar ratio)) copolymer (weight average molecular weight (Mw) 170,000)

[0088] <Dimer Acid Polyamide (B)> (B-1) Dimer Acid Polyamide: Vegichem Green (registered trademark) TPA-2125 (softening point 125°C, amine value 1.0 mgKOH / g) manufactured by Tsuno Oleochemicals Co., Ltd. (B-2) Dimer Acid Polyamide: Vegichem Green (registered trademark) TPA-2176 (softening point 175°C, amine value 0.5 mgKOH / g) manufactured by Tsuno Oleochemicals Co., Ltd. (B-3) Nylon 6: UBE Nylon (registered trademark) 1013B (softening point 175°C, amine value 1.9 mgKOH / g) manufactured by UBE Co., Ltd. <Styrene-based Elastomer (C)> (C-1) Styrene-based Elastomer: Septon (registered trademark) 2063 (styrene-ethylene-propylene-styrene-based elastomer, Shore A hardness 36) manufactured by Kuraray Co., Ltd. (C-2) Styrene-based elastomer: Kuraray Co., Ltd., Septon (registered trademark) 2004 (styrene-ethylene-propylene-styrene-based elastomer, Shore A hardness 67) (C-3) Thermoplastic elastomer: ExxonMobil Corporation, Vistamaxx (registered trademark) 3000 (ethylene / propylene-based elastomer, Shore D hardness 27) <Tackifier resin (D)> (D-1) Tackifier resin: Yasuhara Chemical Co., Ltd., YS Resin (registered trademark) TO-125 (aromatic modified terpene resin, softening point 125°C) (D-2) Tackifier resin (D): Arakawa Chemical Co., Ltd., Pine Crystal (registered trademark) KE-100 (rosin ester, softening point 100°C) (D-3) Tackifier resin (D): Yasuhara Chemical Co., Ltd., YS Resin (registered trademark) TO-85 (aromatic modified terpene resin) Softening point 85℃)

[0089] Example 1 30 parts by mass of acid-modified polyolefin resin (A-1), 20 parts by mass of dimer acid polyamide (B-1), 25 parts by mass of styrene-based elastomer (C-1), and 25 parts by mass of tackifier resin (D-1) were added, and the mixture was melt-kneaded at 190°C using a twin-screw extruder to obtain hot melt adhesive composition 1.

[0090] (Examples 2 to 15, Comparative Examples 1 to 12) Hot melt adhesive compositions 2 to 27 were obtained in the same manner as in Example 1, except that the acid-modified polyolefin resin (A), the dimer acid polyamide (B), the styrene-based elastomer (C), and the tackifier resin (D) were changed as shown in Tables 2 and 3.

[0091] In Tables 2 and 3, the blending ratios are shown in parts by mass, but in each Example and Comparative Example, the total content of the acid-modified polyolefin resin (A), dimer acid polyamide (B), styrene-based elastomer (C), and tackifier resin (D) is 100 parts by mass. Therefore, the blending ratios are the same as when expressed in % by mass, where the total content of the acid-modified polyolefin resin (A), dimer acid polyamide (B), styrene-based elastomer (C), and tackifier resin (D) (hot melt adhesive composition) is taken as 100% by mass.

[0092] (Preparation of sheet sample of hot melt adhesive composition) The hot melt adhesive composition 1 obtained above was pressed using a tabletop test press SA-302 manufactured by Tester Sangyo Co., Ltd. at 160°C, a holding pressure of 20 MPa, and a holding time of 10 seconds to prepare a sheet sample of the hot melt adhesive composition having a thickness of 20 μm.

[0093] (1) Peel Strength Evaluation The sheet-like sample prepared above was sandwiched between a biaxially oriented polyester film (E5101, 50 μm thick) manufactured by Toyobo Co., Ltd. and a polypropylene plate (2.5 mm thick) manufactured by Nippon Test Panel Co., Ltd., and a heat seal tester IMC-0800 manufactured by Imoto Manufacturing Co., Ltd. was used. A peel strength measurement sample was prepared by holding the film at 150 ° C. and a pressure of 0.1 MPa for 120 seconds. The peel strength measurement sample was cut to a width of 10 mm, and the polyester film of the adhesive strength measurement sample was sandwiched between the upper chuck of a tensile tester manufactured by Shimadzu Corporation, and a polypropylene plate was sandwiched between the lower chuck. The 180 ° peel strength (N / 10 mm) was measured by pulling up and down at a pulling rate of 50 mm / min using an autograph AGX-V under an environment of 23 ° C. and 60% Rh. The results are shown in Tables 2 and 3.

[0094] (2) Evaluation of Heat Creep Resistance The sheet-like sample prepared above was sandwiched between a biaxially oriented polyester film (E5101, 50 μm thick) manufactured by Toyobo Co., Ltd. and a polypropylene plate (2.5 mm thick) manufactured by Nippon Testpanel Co., Ltd., and a test piece as shown in Figure 1 was prepared under the same sealing conditions as the adhesive strength evaluation sample. A 100 g weight was attached to the polyester film, and the polyester film was placed in a thermostatic chamber so that the load from the weight was applied vertically. After leaving the polyester film at 80°C for 240 hours, the vertical displacement (mm) of the polyester film was measured. The results are shown in Tables 2 and 3.

[0095]

[0096]

[0097] [Discussion of the results in Tables 2 and 3] As shown in Table 2, the hot melt adhesive compositions 1 to 15 obtained in Examples 1 to 15 exhibited good 180° peel strength and good heat creep resistance when bonding polypropylene test plates to polyester films. On the other hand, the hot melt adhesive compositions obtained in Comparative Examples 1 and 12 had a low content of acid-modified polyolefin resin, resulting in reduced adhesion to the polypropylene plate and a significant decrease in peel strength. The hot melt adhesive compositions obtained in Comparative Examples 2 and 11 had a high content of acid-modified polyolefin resin, resulting in reduced adhesion to the polyester film and a significant decrease in peel strength and heat creep resistance. The hot melt adhesive composition obtained in Comparative Example 3 used polyamide instead of dimer acid polyamide, resulting in poor compatibility and wettability and relatively low fluidity, resulting in reduced heat resistance and a significant decrease in heat creep resistance. The hot melt adhesive composition obtained in Comparative Example 4 used a thermoplastic elastomer instead of a styrene-based elastomer, which resulted in a weak ability to relieve stress at the adhesive interface and reduced compatibility, resulting in a significant decrease in adhesive strength. The hot melt adhesive composition obtained in Comparative Example 5 did not use a dimer acid polyamide, which resulted in reduced heat resistance and significantly reduced heat creep resistance. The hot melt adhesive composition obtained in Comparative Example 6 did not contain an acid-modified polyolefin resin, which resulted in reduced adhesion to the polypropylene plate and a significantly reduced peel strength. The hot melt adhesive composition obtained in Comparative Example 7 did not use a styrene-based elastomer, which resulted in an inability to relieve stress at the adhesive interface and reduced compatibility, resulting in a significantly reduced adhesive strength. The hot melt adhesive composition obtained in Comparative Example 8 did not contain a tackifier, which resulted in reduced wettability to the substrate and a significantly reduced adhesive strength. The hot melt adhesive compositions obtained in Comparative Examples 9 and 10 had a 190° C. melt flow rate of 100 g / 10 min or less, resulting in a significant decrease in heat creep resistance.

[0098] The hot melt adhesive composition of the present invention exhibits excellent adhesion between polyolefin substrates and polyethylene terephthalate (PET), as well as excellent adhesion to other dissimilar substrates such as highly polar resin substrates and metals. Because no solvents are used during bonding, the adhesive composition is environmentally friendly and can be widely used as an adhesive for bonding various substrates in a variety of applications in industries where multi-materialization is progressing. Furthermore, because the adhesive composition of the present invention does not use a curing agent, it can be easily peeled from the substrate by heat treatment even after bonding.

[0099] (a) polypropylene plate; (b) polyester film; (c) hot melt adhesive composition; and (d) 100 g weight.

Claims

The composition comprises an acid-modified polyolefin resin (A), a dimer acid polyamide resin (B), a styrene-based elastomer (C), and a tackifier resin (D), the content of the acid-modified polyolefin resin (A) is 20 to 50 parts by mass per 100 parts by mass of the total solid content in the composition, A hot melt adhesive composition having a melt flow rate at 190°C of 100 g / 10 min to 1000 g / 10 min.

2. The hot melt adhesive composition according to claim 1, wherein the content of the dimer acid polyamide resin (B) is 30 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the acid-modified polyolefin resin (A). 　 The hot melt adhesive composition according to claim 1, wherein the melting point of the acid-modified polyolefin resin (A) is 50°C to 130°C. 　 The hot melt adhesive composition according to claim 1, wherein the acid-modified polyolefin resin (A) has an acid value of 5 to 50 mg KOH / g.

2. The hot melt adhesive composition according to claim 1, wherein the dimer acid polyamide resin (B) has an amine value of 0.1 to 10 mgKOH / g.

2. The hot melt adhesive composition according to claim 1, wherein the dimer acid polyamide resin (B) has a softening point of 100°C to 200°C.

2. The hot melt adhesive composition according to claim 1, wherein the styrene-based elastomer (C) has a Shore A hardness of 60 or less.

2. The hot melt adhesive composition according to claim 1, wherein the content of the styrene-based elastomer (C) is 10 to 80 parts by mass per 100 parts by mass of the total content of the acid-modified polyolefin resin (A) and the dimer acid polyamide resin (B).

2. The hot melt adhesive composition of claim 1, wherein the tackifier resin (D) is a terpene-based resin. 　 An adhesive body in which a polyolefin-based substrate and polyethylene terephthalate (PET) are bonded together with an adhesive comprising the hot melt adhesive composition according to any one of claims 1 to 9.

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