Hot melt adhesive composition and laminate

Abstract

This hot melt adhesive composition contains an acid-modified polyolefin and a copolymerized polyester and satisfies the following (1)-(5). (1) The copolymerized polyester is composed of a dicarboxylic acid component and a glycol component and has a melting point (T1) of 80-150ºC, as obtained by a differential scanning calorimeter (DSC). (2) The melting point (T2) of the acid-modified polyolefin, as obtained by the DSC, is 60-150ºC. (3) |T1-T2|≤40ºC. (4) When the acid value of the acid-modified polyolefin is defined as AV (eq / ton) and the hydroxyl value of the copolymerized polyester is defined as OHV (eq / ton), 0.5≤AV / OHV≤4.5. (5) When the total amount of the acid-modified polyolefin and the copolymerized polyester is 100 mass%, the content of the acid-modified polyolefin is 5-40 mass% and the content of the copolymerized polyester is 60-95 mass%, and when the total amount of the whole hot melt adhesive composition is 100 mass%, the total amount of the acid-modified polyolefin and the copolymerized polyester is at least 70 mass%.

Description

Technical Field

[0001] The present invention relates to a hot-melt adhesive composition and a laminate bonded with the hot-melt adhesive composition.

Background Art

[0002] Olefin resins such as polypropylene (PP) and propylene-α-olefin copolymers are inexpensive, lightweight, and excellent in strength, chemical resistance, and hydrolysis resistance, and thus are widely used in various fields including automobiles and home electric appliances. Particularly in recent years, weight reduction has been strongly demanded to improve the fuel efficiency of automobiles, and the resins have been widely studied as a substitute for metals. However, since these olefin resins have no polarity, it has been difficult to obtain good adhesion to their molded articles and films. To improve this drawback, various methods have been attempted, such as oxidizing the surface of an olefin resin by chemical treatment with a chemical agent, corona discharge treatment, plasma treatment, flame treatment, or other methods. However, these methods not only require special equipment, but also cannot be said to have sufficient improvement effects on adhesion and paintability.

[0003] Chlorinated polyolefins and acid-modified polyolefins have been developed as a means for imparting good paintability and adhesion to olefin resins by a relatively simple method. Since polyolefins generally do not dissolve in solvents, contrivances have been made to lower crystallinity and impart solubility through chlorination or copolymerization with α-olefins. Since crystallinity is also reduced by acid modification, resins with relatively good solubility have been obtained through acid modification. However, these resins have low compatibility with polar resins, and thus have the problem that good adhesion to highly polar resins such as polyvinyl chloride (PVC) and polyethylene terephthalate (PET) cannot be obtained.

[0004] Therefore, epoxy adhesives and urethane adhesives are used to bond olefin resins and ester resins. These exhibit excellent mechanical properties because they form three-dimensional crosslinks through the reaction of the resin and the curing agent (for example, Patent Document 1). In addition, a resin composition consisting of polyester and modified polyolefin has been disclosed (for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-323292 [Patent Document 2] Japanese Patent Application Publication No. 5-86239 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the adhesive described in Patent Document 1 is generally a two-component type consisting of a resin and a hardener, and requires accurate weighing and mixing before use, which is problematic due to poor workability. Furthermore, because it gels quickly after mixing, the pot life is short, ranging from several tens of minutes to several hours, making it unsuitable for automated application using dispensers, etc., and requiring the disposal of excess. In addition, the curing time of several tens of minutes to several hours is also problematic due to low productivity. Moreover, the resin composition described in Patent Document 2 uses a polyester having amide bonds, and hydrogen bonding between the amide bonds of the polyester and between the amide bonds and the modified polyolefin causes a significant increase in melt viscosity and a decrease in adhesiveness.

[0007] The object of the present invention is to provide a hot melt adhesive composition that improves the aforementioned workability and productivity, has good adhesion to olefin substrates such as polypropylene, also has good adhesion to highly polar substrates such as PVC and PET, and further has excellent mechanical properties. [Means for solving the problem]

[0008] To achieve the above objective, the inventors have conducted diligent research and have come to propose the following invention. Specifically, the present invention relates to the hot melt adhesive composition shown below, and to a laminate using the hot melt adhesive composition.

[0009] A hot melt adhesive composition containing an acid-modified polyolefin and a copolymerized polyester, satisfying the following conditions (1) to (5). (1) The copolymerized polyester consists of a dicarboxylic acid component and a glycol component, and its melting point (T1) obtained by differential scanning calorimeter (DSC) is in the range of 80 to 150°C. (2) The melting point (T2) of the acid-modified polyolefin obtained by differential scanning calorimeter (DSC) is in the range of 60 to 150°C. (3) |T1-T2| ≤ 40℃ (4) When the acid value of the acid-modified polyolefin is AV (eq / ton) and the hydroxyl value of the copolymerized polyester is OHV (eq / ton), then 0.5 ≤ AV / OHV ≤ 4.5. (5) When the total amount of acid-modified polyolefin and copolymer polyester is taken as 100% by mass, the composition contains 5 to 40% by mass of acid-modified polyolefin and 60 to 95% by mass of copolymer polyester, and when the total amount of the hot melt adhesive composition is taken as 100% by mass, the total amount of acid-modified polyolefin and copolymer polyester is 70% by mass or more. It is preferable that the acid-modified polyolefin resin is a maleic anhydride-modified polyolefin. Furthermore, it is preferable that the polycarboxylic acid component of the copolymerized polyester contains both aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and that the alkylene glycol component is a saturated aliphatic glycol. A laminate of a polyvinyl chloride substrate and a polyolefin substrate bonded together with the hot melt adhesive composition described above. [Effects of the Invention]

[0010] The hot-melt adhesive composition of the present invention, by using specific amounts of specific copolymerized polyester and acid-modified polyolefin, possesses both non-polar and polar components, and therefore exhibits good adhesion between dissimilar substrates, such as olefin substrates like polypropylene and polar substrates like PVC and PET. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The hot-melt adhesive composition of the present invention must contain an acid-modified polyolefin and a copolymerized polyester, and must satisfy the following (1) to (4).

[0012] <(1) Hot melt adhesive composition that satisfies (1)> (1) will be explained. The copolymer polyester used in the hot melt adhesive composition of the present invention consists of a dicarboxylic acid component and a glycol component, and its melting point (T1) obtained by differential scanning calorimeter (DSC) is in the range of 80 to 150°C. Preferably it is 90 to 120°C, and more preferably 95 to 115°C. When T1 is 80°C or higher, the heat resistance of the hot melt adhesive composition tends to be good. When T1 exceeds 150°C, a larger amount of heat is required to melt the hot melt adhesive composition, which has adverse effects both economically and environmentally.

[0013] <(2) Hot melt adhesive composition that satisfies (2)> (2) will now be explained. The melting point (T2) of the acid-modified polyolefin used in the present invention, as determined by differential scanning calorimeter (DSC), is in the range of 60 to 150°C. Preferably, it is 65 to 125°C, and more preferably 70 to 110°C. If T2 is 60°C or lower, the heat resistance of the hot melt adhesive composition decreases. If T2 is 150°C or higher, more heat must be added to melt the hot melt adhesive composition, which has adverse effects both economically and environmentally.

[0014] <(3) Hot melt adhesive composition that satisfies this condition> (3) will be explained. The hot melt adhesive composition used in the present invention has a |T1-T2| ≤ 40 (°C). Preferably, |T1-T2| ≤ 30 (°C), and more preferably, |T1-T2| ≤ 20 (°C). If |T1-T2| exceeds 40°C, when bonding is performed by heating, only the low melting point component may melt first, which may reduce the adhesive strength with the polar substrate.

[0015] <(4) Hot melt adhesive composition that satisfies this condition> (4) will be explained. When the acid value of the acid-modified polyolefin constituting the hot melt adhesive composition of the present invention is AV (eq / ton) and the hydroxyl value of the copolymerized polyester is OHV (eq / ton), then 0.5 ≤ AV / OHV ≤ 4.5. Preferably, 0.8 ≤ AV / OHV ≤ 3.5, and more preferably 1.0 ≤ AV / OHV ≤ 3.0. If 0.5 > AV / OHV, the ratio of hydroxyl groups in the polyester to the acid in the acid-modified polyolefin becomes smaller, weakening hydrogen bonding and lowering the melt viscosity. When the melt viscosity is low, shear force is not applied when the hot melt adhesive composition is prepared by melt kneading, the acid-modified polyolefin and polyester do not become well dispersed, and the adhesive strength to the substrate decreases. By having AV / OHV ≤ 4.5, the melt viscosity of the hot melt adhesive composition does not become too high, resulting in good wettability to the substrate, and in particular good adhesion to polyvinyl chloride (PVC).

[0016] <(5) Hot melt adhesive composition that satisfies this condition> Description will be given of (5). When the total amount of the acid-modified polyolefin and the copolyester is 100% by mass, the hot-melt adhesive composition of the present invention contains 5 to 40% by mass of the acid-modified polyolefin and 60 to 95% by mass of the copolyester. Preferably, the composition contains 20 to 40% by mass of the acid-modified polyolefin and 60 to 80% by mass of the copolyester. More preferably, the composition contains 25 to 35% by mass of the acid-modified polyolefin and 65 to 75% by mass of the copolyester. If the composition falls outside the above range, the polarity balance will be unbalanced in adhesion to dissimilar substrates, so good adhesion to both substrates cannot be obtained. Furthermore, the composition of the acid-modified polyolefin and the copolyester satisfies the above range, and when the total amount of the entire hot-melt adhesive composition is 100% by mass, the total amount of the acid-modified polyolefin and the copolyester needs to be 70% by mass or more. It is preferably 80% by mass or more, more preferably 90% by mass or more.

[0017] <Acid-modified polyolefin> Examples of the acid-modifiable polyolefin that serves as a base of the acid-modified polyolefin used in the present invention include polyethylene, polypropylene, ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. Among these, at least one selected from the group consisting of polypropylene, ethylene-propylene copolymers, and ethylene-propylene-butene copolymers (hereinafter also referred to as propylene-based polymers) is preferable in terms of heat resistance and compatibility with copolyesters. The propylene component in the propylene-based polymer is preferably 50 mol% or more, more preferably 70 mol% or more. Further, as the acid-modifiable polyolefin, those obtained by copolymerizing unsaturated acids such as (meth)acrylic acid and (meth)acrylic acid ester, alkyl esters of unsaturated acids, vinyl acetate, ethylene, propylene, and α-olefins can be used.

[0018] The acid-modified polyolefin used in the present invention is preferably obtained by graft polymerization (hereinafter also referred to as acid modification) of at least one selected from the group consisting of unsaturated carboxylic acids having 3 to 10 carbon atoms, acid anhydrides thereof and esters thereof. The weight of graft chains relative to the entire acid-modified polyolefin (hereinafter also referred to as the amount of acid modification) is preferably 0.5 to 10% by mass. More preferably, it is 0.7 to 3% by mass. When the weight fraction of graft chains is outside the above range, adhesion to a polyolefin substrate may decrease.

[0019] Examples of the unsaturated carboxylic acids having 3 to 10 carbon atoms, acid anhydrides thereof and esters thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid; acid anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, and citraconic anhydride; and alkyl esters of unsaturated carboxylic acids such as methyl acrylate, methyl methacrylate, and dimethyl maleate. Among these, maleic acid, itaconic acid, and acid anhydrides thereof are preferred.

[0020] Graft polymerization for producing the acid-modified polyolefin in the present invention can be carried out by a known method, and the method is not particularly limited. For example, the reaction can be carried out by adding an organic peroxide to a molten mixture of the polyolefin and the unsaturated carboxylic acid component. Alternatively, the reaction can be carried out by adding an organic peroxide to a mixture solution obtained by dissolving the polyolefin and the unsaturated carboxylic acid component in a solvent such as toluene or xylene. When carrying out graft polymerization, it is preferable to avoid contamination of air and oxygen, and the reaction is preferably carried out under an inert gas atmosphere such as nitrogen gas. Examples of the organic peroxide include acetylcyclohexylsulfonyl peroxide, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, and lauroyl peroxide, and one or more of these can be used in combination.

[0021] The melt viscosity of acid-modified polyolefin at 190°C is preferably 1,000 to 20,000 mPa·s, more preferably 2,000 to 15,000 mPa·s, and even more preferably 3,000 to 13,000 mPa·s. If the melt viscosity is 1,000 mPa·s or less, the cohesive force decreases, reducing the adhesive strength to the substrate, and if it is 20,000 mPa·s or more, the adhesion to the substrate decreases. Furthermore, the melt viscosity of copolymerized polyester at 190°C is preferably 220,000 mPa·s or less, and more preferably 200,000 mPa·s or less. If it is 220,000 mPa·s or more, the adhesion to the substrate decreases.

[0022] The melting point T1 of the acid-modified polyolefin is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher. It is also preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. If the melting point of the acid-modified polyolefin is below 60°C, the adhesiveness may decrease significantly due to rising temperatures in the environment of use, and if it exceeds 150°C, the olefin substrate may melt during bonding. Furthermore, when the melting point of the copolymerized polyester is T2, it is preferable that |T1-T2| ≤ 40°C. If |T1-T2| exceeds 40°C, when bonding is performed by heating, only the low-melting-point component may melt first, which may reduce the adhesive strength with the polar substrate.

[0023] The weight-average molecular weight (Mw) of the acid-modified polyolefin is preferably 30,000 to 120,000, more preferably 40,000 to 110,000, and even more preferably 50,000 to 100,000. The number-average molecular weight (Mn) is preferably 10,000 to 70,000, more preferably 15,000 to 60,000, and even more preferably 20,000 to 55,000. Furthermore, the molecular weight distribution (Mw / Mn) is preferably 3 or less, and even more preferably 2.8 or less. By using an acid-modified polyolefin within the above range, compatibility with copolymerized polyester is improved, and the adhesive properties of the hot-melt adhesive composition can be improved.

[0024] The AV of the acid-modified polyolefin is preferably 50 to 500, more preferably 100 to 400, and still more preferably 150 to 300. When AV is less than 50, the adhesion of the acid-modified polyolefin to a polyolefin substrate is low, resulting in reduced adhesive strength. When AV is more than 500, the cohesive force of the acid-modified polyolefin decreases, leading to reduced adhesive strength.

[0025] <Copolymerized Polyester> The copolymerized polyester used in the present invention is obtained, for example, by dehydration condensation or dealcoholization condensation of a dicarboxylic acid component such as dicarboxylic acid, an anhydride thereof or an alkyl ester thereof with a glycol component.

[0026] Examples of the compound forming the dicarboxylic acid component include aromatic dibasic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,2-naphthalenedicarboxylic acid, and 1,6-naphthalenedicarboxylic acid; and aliphatic dicarboxylic acids and alicyclic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, hydrogenated dimer acid, dodecenyl succinic anhydride, fumaric acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, and citraconic acid.

[0027] When the total amount of dicarboxylic acid components is 100 mol%, the content of aromatic dicarboxylic acid is 40 mol% or more The content is preferably at least 45 mol%, more preferably at least 50 mol%, and even more preferably at least 50 mol%. The upper limit is not particularly limited, and it may be 100 mol%, but is preferably 95 mol% or less, more preferably 90 mol% or less. The total content of the aliphatic dicarboxylic acid and the alicyclic dicarboxylic acid is preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. Too little aromatic dicarboxylic acid or too much aliphatic dicarboxylic acid and alicyclic dicarboxylic acid may reduce the adhesiveness and heat resistance of the hot-melt adhesive composition.

[0028] The OHV of the copolyester is preferably 20 to 200. It is more preferably 30 to 170, and even more preferably 50 to 150. When OHV < 30, the interaction with the acid-modified polyolefin becomes small, leading to poor dispersion during melt kneading. When OHV > 150, the adhesiveness to the polyolefin base material decreases when the adhesive layers are bonded together.

[0029] Other glycol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl Tyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl-3-hydroxypropyl-2',2'-dimethyl-3'-hydroxypropaneate, 2-(n-butyl)-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol Examples include aliphatic diols such as dol, alicyclic glycols such as 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxyethyl)cyclohexane, 1,4-bis(hydroxypropyl)cyclohexane, 1,4-bis(hydroxymethoxy)cyclohexane, 1,4-bis(hydroxyethoxy)cyclohexane, 2,2-bis(4-hydroxymethoxycyclohexyl)propane, 2,2-bis(4-hydroxyethoxycyclohexyl)propane, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, and 3(4),8(9)-tricyclo[5.2.1.02,6]decandimethanol, or aromatic glycols such as ethylene oxide adducts and propylene oxide adducts of bisphenol A, or polyethylene glycol, polypropylene glycol, and polytrimethylene glycol. These can be used individually or in combination of two or more.

[0030] Furthermore, the copolymerized polyester used in the present invention can also be copolymerized by substituting a portion of the dicarboxylic acid component with a trifunctional or higher carboxylic acid, or by substituting a portion of the glycol component with a trifunctional or higher polyol. Examples of these trifunctional or higher compounds include polycarboxylic acids such as trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, ethylene glycol bis(anhydrotrimellitate), and glycerol tris(anhydrotrimellitate), as well as their anhydrides, and polyfunctional glycols such as trimethylolpropane, pentaerythritol, glycerin, and polyglycerin.

[0031] Furthermore, copolymer polyesters used in the present invention can also be copolymerized or post-added with glycolic acid, lactones, lactides, or (poly)carbonates, or post-added with acid anhydrides, or copolymerized with glycolic acid.

[0032] The copolymer polyester used in the present invention preferably does not contain amide bonds in its main chain. The amount of amide bonds in the main chain of the copolymer polyester is 5 × 10 per 100 g of copolymer polyester. -4 It is preferable that the amount be less than a mole. More preferably 1 × 10⁻⁶. -4 The number of moles is 5 × 10⁻⁵ moles or less. -4 If present in amounts exceeding a certain mole, hydrogen bonding between amide bonds in the copolymerized polyester and hydrogen bonding between amide bonds and the acid-modified portion of the acid-modified polyolefin may significantly increase the melt viscosity and reduce adhesion. The melt viscosity of the copolymerized polyester at 190°C is preferably 220,000 mPa·s or less, and more preferably 200,000 mPa·s or less. A melt viscosity of 220,000 mPa·s or less provides good adhesion to the substrate.

[0033] The melting point T2 of the copolymerized polyester is preferably 80°C or higher, more preferably 85°C or higher, and even more preferably 90°C or higher. It is also preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. If T2 is below 80°C, the adhesiveness may decrease significantly due to rising temperatures in the environment of use, and if it exceeds 150°C, the olefin substrate may melt during bonding.

[0034] The copolymerized polyester may be either crystalline or amorphous, but crystalline copolymerized polyester is preferred. If crystalline copolymerized polyester is used, improved adhesive strength can be expected due to the increased strength of the resin resulting from crystallization.

[0035] Furthermore, it is preferable to add an antioxidant to the hot-melt adhesive composition of the present invention. Preferred antioxidants include hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and amine antioxidants, and one or more of these can be used in combination. In particular, the combination of a hindered phenol antioxidant and other antioxidants is effective. It is also desirable to add stabilizers such as heat aging inhibitors, copper damage inhibitors, antistatic agents, light stabilizers, and ultraviolet absorbers. In particular, it is desirable to use a phenol antioxidant containing a phosphorus atom in its molecule, as this allows for efficient radical capture. Furthermore, nucleating agents and flame retardants can also be added.

[0036] Examples of hindered phenol 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-hydroxybenzenepropanoic acid, and pentaerythritol tetrakis[3-(3,5-di-t-butyl-4 -Hydroxyphenyl)propionate], 3-(1,1-dimethylethyl)-4-hydroxy-5-methylbenzenepropanoic 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-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 3,3',3”,5,5'5”-hexa-tert-butyl-a,a',a”-(mesitylene-2,4,6-triyl)tri-p-cresol, diethyl[[3,5-bis[1,1-dimethicone] Examples include ethyl-4-hydroxyphenyl]methyl phosphate, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 2'3-bis[[3-[3,5-di-ter-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, and 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro[5·5]undecane.

[0037] 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, isodecylphosphite, isodecylphenylphosphite, diphenyl 2-ethylhexyl phosphite, dinonylphenyl bis(nonylphenyl) ester phospholucic 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- Examples include 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 phosphite, 6-[3-(3-tert-butyl-4-hydroxy-5-methyl)propoxy]-2,4,8,10-tetra-tert-butyldibenz[d,f][1,3,2]-dioxaphosfepine, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonate, and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

[0038] 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, and 4,6 Examples include -bis(octylthiomethyl)-o-cresol and 4,4-thiobis(3-methyl-6-tert-butylphenol).

[0039] Examples of amine-based 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].

[0040] The amount of antioxidant added is preferably 0.1% by mass or more and 5% by mass or less of the total hot melt adhesive composition. If it is less than 0.1% by mass, the thermal degradation prevention effect may be poor. If it exceeds 5% by mass, it may adversely affect the adhesive properties, etc.

[0041] The hot-melt adhesive composition of the present invention may also contain other resins such as epoxy resins, polyamide resins, polyolefin resins, polycarbonate resins, acrylic resins, ethylene vinyl acetate resins, and phenolic resins, to the extent that they do not impair the performance of the present invention, which may improve adhesion, flexibility, durability, etc. The amount of other resins added should preferably be less than 5% by mass of the total 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 dioxide, and flame retardants such as antimony trioxide and brominated polystyrene may also be added.

[0042] The hot-melt adhesive composition of the present invention may contain tackifiers such as rosin or terpenes, which may improve adhesion. The amount of tackifiers added is preferably less than 5% by mass of the total hot-melt adhesive composition.

[0043] The method for producing the hot-melt adhesive composition of the present invention is not particularly limited. Examples include melt-kneading using an extruder such as a single-screw extruder or a twin-screw extruder, directly obtaining a molded product by melt-kneading pellet blends in a molding machine, adding acid-modified polyolefin during polymerization of copolymer polyester and mixing, or blending the two in a solution. However, a method using a twin-screw extruder capable of applying 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 of the acid-modified polyolefin or copolymer polyester used, specifically at 150 to 300°C.

[0044] <Base material> As the polar substrate used in the present invention, substrates such as polyethylene terephthalate (PET) and polyvinyl chloride (PVC) can be used. Furthermore, the polyolefin substrate is not particularly limited, and substrates such as polyethylene (PE) and polypropylene (PP) can be used. Among these, a combination of PVC and PP is preferred.

[0045] <Laminate> The laminate of the present invention is a three-layer laminate (polar substrate / hot melt adhesive composition layer / polyolefin substrate) in which a polar substrate and a polyolefin substrate are laminated with a hot melt adhesive composition. The laminate can be manufactured, for example, by laminating or coating a hot melt adhesive composition onto a polyester substrate (or polyolefin substrate), further sandwiching it with a polyolefin substrate (or polyester substrate), and heat-pressing it. The thickness of the hot melt adhesive composition layer in the laminate is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 15 to 50 μm. If the thickness is too thin, sufficient adhesive performance may not be obtained, and if it is too thick, productivity may decrease. [Examples]

[0046] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. In the examples and comparative examples, "parts" refers to parts by mass, and "%" refers to mass percent. Examples 6 and 9 are for reference only.

[0047] <<Evaluation Methods for Resins and Hot Melt Adhesive Compositions>>

[0048] <Composition ratio> The sample (copolymerized polyester or acid-modified polyolefin) was dissolved in chloroform-d and analyzed using a Varian Gemini-200 nuclear magnetic resonance (NMR) analyzer to obtain 1H-N The decision was made after performing an MR analysis.

[0049] <Acid value (AV) of acid-modified polyolefins> In this invention, the acid value (eq / ton) of the acid-modified polyolefin is determined using FT-IR (Shimadzu Corporation, FT-IR8200PC) based on the carbonyl (C=O) ratio of maleic anhydride. Absorbance (I) of the binding stretching peak (1780 cm⁻¹), isotactic characteristic peak. The absorbance (II) of (840 cm⁻¹) and the factor (f) obtained from a calibration curve prepared using a chloroform solution of maleic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) were used to calculate the equivalent weight (eq / ton) per ton of resin using the following formula. Acid value = [Absorbance (I) / Absorbance (II) × (f) / Molecular weight of maleic anhydride × 2 × 10⁴] Molecular weight of maleic anhydride: 98.06

[0050] <Hydroxyl value (OHV) of copolymerized polyesters> The hydroxyl value of the copolymerized polyester in this invention was determined as follows: 50 g of copolymerized polyester was dissolved in 120 g of hot chloroform, and 70 g of 4,4'-diphenylmethane diisocyanate was added. The mixture was reacted at 70°C for 2 hours. The concentration of residual isocyanate groups in the reaction solution was then quantified by titration, and the hydroxyl value (eq / ton) was determined.

[0051] <Melting viscosity> Using a Shimadzu flow tester (CFT-500C model), a resin sample (copolymerized polyester or acid-modified polyolefin) with a moisture content of 0.1% or less was filled into a cylinder in the center of a heating element set to 190°C. After 3 minutes of filling, pressure (4.9 MPa) was applied to the sample via a plunger, and the molten sample was extruded through a die (pore diameter: 0.5 mm, thickness: 20 mm) at the bottom of the cylinder. The descent distance and descent time of the plunger were recorded, and the melt viscosity (mPa·s) was calculated.

[0052] <Weight average molecular weight (Mw), number average molecular weight (Mn)> In this invention, Mw and Mn are obtained using GPC (Gel Permeation Chromatography) manufactured by Waters Ltd. Japan, Alliance e2695 (hereinafter also referred to as GPC). Standard substance: Polystyrene resin Lipid, mobile phase: tetrahydrofuran, column: Shodex KF-806 + KF-803, column temperature: 40℃, flow rate: 1.0 ml / min, detector: photodiode array detector (wavelength 254 nm = ultraviolet) This is a value measured by ).

[0053] <Melting point> Using a differential scanning calorimetry analyzer "DSC220" manufactured by Seiko Electronics Industries, Ltd., 5 mg of the sample (copolymerized polyester or acid-modified polyolefin) was placed in an aluminum pan, sealed by pressing down on the lid, and held at 250°C for 5 minutes to completely melt the sample. After rapid cooling with liquid nitrogen, the temperature was measured from -150°C to 250°C at a heating rate of 20°C / min. From the obtained thermogram curve, the maximum endothermic peak of the heat of fusion was defined as the melting point.

[0054] <Preparation of sheet-like samples of hot-melt adhesive compositions> Using a tabletop test press SA-302 manufactured by Tester Industries Co., Ltd., a sheet-like sample of a hot-melt adhesive composition with a thickness of 20 μm was formed at 160°C, a holding pressure of 20 MPa, and a holding time of 10 seconds.

[0055] <Evaluation of adhesive strength> A sheet-like sample was sandwiched between a PVC film (BONLEX BE, 50 μm thick) manufactured by Takiron CI Co., Ltd. and a polypropylene plate (2.5 mm thick) manufactured by Nippon Test Panel Co., Ltd. A heat seal tester IMC-0800 manufactured by Imoto Seisakusho Co., Ltd. was used to form a sample for adhesive strength measurement by holding pressure at 140°C and 0.1 MPa for 120 seconds. The adhesive strength measurement sample was cut into 10 mm wide strips, and the PVC film of the adhesive strength measurement sample was placed in the upper chuck and the polypropylene plate in the lower chuck of a tensile testing machine manufactured by Shimadzu Corporation. The 180° peel adhesive strength was measured by pulling the machine up and down at a tensile speed of 50 mm / min using an Autograph AGX-V under conditions of 23°C and 60% Rh. Evaluation was performed based on the measured values ​​and an overall evaluation. (Overall evaluation) ○: The hot melt adhesive composition undergoes cohesive failure and has a peel strength of 15 N / 10 mm or more. △: (1) The hot melt adhesive composition peels off at the interface of the polypropylene board or PVC film. (2) Hot melt adhesive composition The material undergoes cohesive failure, and its peel strength is in the range of 10 N / 10 mm or more and less than 15 N / 10 mm. ×: The peel strength is less than 10 N / 10 mm.

[0056] <<Manufacturing Examples and Implementation Examples>>

[0057] Production example of acid-modified polyolefin (a) 100 parts by mass of crystalline polypropylene (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, sealed, and subjected to nitrogen purging for 5 minutes. The reaction was then carried out at 140°C for 5 hours with heating and stirring. After the reaction was complete, the reaction solution was added to a large amount of methyl ethyl ketone to precipitate the resin. The precipitated resin was removed, washed several times with methyl ethyl ketone, and then dried to obtain acid-modified polyolefin (a). The composition and properties are shown in Table 1.

[0058] Production examples of acid-modified polyolefins (b) to (f) Acid-modified polyolefins (b) to (e) were obtained by changing the type of polyolefin resin to be modified, in the same manner as with acid-modified polyolefin (a) described above. The composition and properties of each acid-modified polyolefin are shown in Table 1.

[0059] [Table 1] Polyolefin resin 1: Propylene-butene (=70 / 30 (molar ratio)) copolymer (weight-average molecular weight 230,000) Polyolefin resin 2: Propylene-butene (=90 / 10 (molar ratio)) copolymer (weight-average molecular weight 180,000) Polyolefin resin 3: Propylene-ethylene-butene (=70 / 10 / 20 (molar ratio)) copolymer (weight-average molecular weight 170,000)

[0060] Example of production of copolymer polyester (A) In a reaction vessel equipped with a stirrer, thermometer, and distillation cooler, 30 parts by mass of terephthalic acid, 20 parts by mass of isophthalic acid, 50 parts by mass of adipic acid, 100 parts by mass of 1,4-butanediol, and 0.25 parts by mass of tetrabutyl titanate were added, and an esterification reaction was carried out at 170-220°C for 2 hours. After the esterification reaction was completed, 0.5 parts by mass of the hindered phenol antioxidant "Irganox® 1330" (manufactured by BASF Japan Ltd.) was added, and the temperature was raised to 255°C while the pressure in the system was slowly reduced, reaching 665 Pa at 255°C over 60 minutes. Then, a polycondensation reaction was carried out at 133 Pa or less for 30 minutes to obtain polyester resin (A). The melting point of this polyester resin (A) was 110°C, and the melt viscosity at 190°C was 180,000 mPa·s.

[0061] Manufacturing examples of copolymer polyesters (B) to (D) Copolymerized polyester resins (B) to (D) were obtained by changing the dicarboxylic acid and glycol components in the same manner as copolymerized polyester (A). The properties of each resin are shown in Table 2.

[0062] [Table 2] TPA: Terephthalic acid IPA: Isophthalic Acid AA: Adipic acid EG: Ethylene glycol BD:1,4-butanediol PTMG1000: Polytetramethylene glycol (number average molecular weight 1000)

[0063] Example 1 Hot melt adhesive composition (1) A hot-melt adhesive composition (1) was obtained by adding 30 parts by mass of the above acid-modified polyolefin (a) as an acid-modified polyolefin and 70 parts by mass of the above copolymer polyester (A) as a copolymer polyester, and melt-kneading at 190°C using a twin-screw extruder. The adhesive strength measured by the above method was 20 N / cm. The composition and properties are shown in Table 3.

[0064] Examples 2-9, Comparative Examples 1-8 Examples of Hot Melt Adhesive Compositions 2-17 Hot melt adhesive compositions 2 to 17 were obtained in the same manner as in Production Example 1, according to the combinations in Tables 3 and 4. The adhesive strength was measured using the method described above. The compositions and properties are shown in Tables 3 and 4.

[0065] [Table 3]

[0066] [Table 4] Unmodified polyolefin: J-700GP (homopolypropylene manufactured by Prime Polymer Co., Ltd.)

[0067] Examples 1-9 satisfy the claims and exhibit good adhesive strength. Comparative Example 1 contains more than 95% by mass of copolymerized polyester, thus falling outside the scope of the present invention, resulting in low adhesion to PP film. Comparative Example 2 contains more than 50% by mass of acid-modified polyolefin, thus falling outside the scope of the present invention, resulting in low adhesion to PVC film. Comparative Example 3 has an AV / OHV of 4.5 or higher, falling outside the scope of the present invention, resulting in low adhesion to both PP and PVC film. Comparative Example 4 has |T1-T2|>40, leading to uneven dispersion of the adhesive layer and resulting in low adhesion. Comparative Example 5 does not contain acid-modified polyolefin, resulting in low adhesion to PP. Comparative Example 6 does not contain copolymerized polyester, resulting in low adhesion to PVC. Comparative Example 7 uses unmodified polyolefin adhesive instead of acid-modified polyolefin, resulting in low adhesion to PP substrate. Comparative Example 8 has low adhesion because, when the total amount of the hot melt adhesive composition is taken as 100% by mass, the total amount of acid-modified polyolefin and copolymerized polyester is less than 70% by mass.

Claims

1. A hot melt adhesive composition containing an acid-modified polyolefin and a copolymerized polyester, satisfying the following conditions (1) to (5). (1) The copolymerized polyester consists of a dicarboxylic acid component and a glycol component, and its melting point (T1), obtained by differential scanning calorimeter (DSC), is in the range of 80 to 150°C. (2) The melting point (T2) of the acid-modified polyolefin obtained by differential scanning calorimeter (DSC) is in the range of 60 to 150°C. (3) |T1 - T2| ≤ 40°C (4) When the acid value of the acid-modified polyolefin is AV (eq / ton) and the hydroxyl value of the copolymerized polyester is OHV (eq / ton), then 0.8 ≤ AV / OHV ≤ 3.

5. (5) When the total amount of acid-modified polyolefin and copolymer polyester is taken as 100% by mass, the composition contains 5 to 40% by mass of acid-modified polyolefin, and when the total amount of the hot melt adhesive composition is taken as 100% by mass, the total amount of acid-modified polyolefin and copolymer polyester is 70% by mass or more.

2. The hot melt adhesive composition according to claim 1, wherein the acid-modified polyolefin resin is a maleic anhydride-modified polyolefin.

3. The hot melt adhesive composition according to claim 1 or 2, wherein the dicarboxylic acid component of the copolymerized polyester comprises both aromatic dicarboxylic acid and aliphatic dicarboxylic acid, and the alkylene glycol component is a saturated aliphatic glycol.

4. A laminate of a polyvinyl chloride substrate and a polyolefin substrate bonded together with the hot melt adhesive composition according to any one of claims 1 to 3.

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