Resin composition, adhesive composition, and laminate

Abstract

Provided is a resin composition with which it is possible to produce laminates having various kinds of laminate structures that exhibit excellent adhesion and tear-openability without using an aromatic isocyanate, and which does not substantially contain a solvent component and is used as a main agent of a two-liquid curing type adhesive composition capable of being applied in a thin film state. This resin composition is used as a main agent (A) of a two-liquid curing type adhesive composition including the main agent (A) and a curing agent (B) and does not substantially contain a solvent content. The resin composition includes a polyester (a) having hydroxyl groups at molecular terminals at a hydroxy group concentration of 1.0-6.0 mol / kg. The polyester (a) has structural units derived from a dicarboxylic acid (α) and structural units derived from a diol (β). In the structural units derived from the dicarboxylic acid (α), the contained amount of a structural unit derived from an aromatic dicarboxylic acid (α1) is greater than 40 mol%. The melt viscosity of the resin composition at 80°C is 10,000 mPa･s or less.

Description

Resin composition, adhesive composition, and laminate

[0001] The present invention relates to a resin composition, an adhesive composition, and a laminate.

[0002] Film- or sheet-like laminates obtained by laminating plastic films, sheets, and the like are widely used as various containers and packaging materials for foods, miscellaneous goods, etc. For example, by laminating films with different properties, such as using a heat-sealable film as an inner layer and a non-heat-sealable film as an outer layer, containers and packaging materials can be produced with good productivity by a heat-sealing method or the like.

[0003] In many cases, decorative printing is applied to the laminated surface of the film or sheet. The printed surface is protected by the film or sheet, which prevents contamination of the contents with printing ink, etc. Furthermore, many of these containers and packaging materials are provided that can be easily torn open by hand without using scissors or the like.

[0004] However, it is important that the laminated film or sheet is torn as a unit when opening. If the tearing point of the laminated film or sheet varies, not only will the appearance be marred, but the protected printed surface may be exposed, which is undesirable from a hygienic standpoint. In particular, in the case of laminates using non-oriented linear low-density polyethylene films or polypropylene films as heat-sealable films, the adhesive strength is so high that they cannot be easily torn, and the printed surface is likely to be exposed, which is a problem.

[0005] In order to produce film- or sheet-like laminates with excellent tear-opening properties (hand tearability), two-component (two-liquid) mixed curing adhesive compositions have been used, which combine a high-molecular-weight base agent, such as polyester polyol, polyester polyurethane polyol, or polyether polyurethane polyol, with a curing agent, such as polyisocyanate. These adhesive compositions have high viscosity due to the high molecular weight of the base agent. Therefore, in order to apply a thin film by a coating method such as gravure coating or reverse roll coating, it has been necessary to dilute the adhesive composition with a large amount of solvent.

[0006] After application of the adhesive composition, the solvent component is removed by, for example, evaporation and drying. Vaporizing and drying the solvent component requires a large amount of energy, which is costly and places a heavy burden on the environment. For this reason, there has been a demand for a so-called solvent-free adhesive composition that uses as little solvent component as possible, ideally one that can be applied to form a thin film even if it does not substantially contain a solvent component.

[0007] Solventless adhesive compositions that can be applied as thin films to film- or sheet-like substrates have been known. For example, solventless adhesive compositions containing a polyol component and an isocyanate component have been proposed (Patent Documents 1 and 2). Another adhesive composition has been proposed in which a base component primarily composed of isocyanate-terminated polyether polyurethane is melt-mixed with a polyol curing agent (Patent Document 3). Another adhesive composition has been proposed in which a base component primarily composed of polyester polyol is melt-mixed with a polyisocyanate curing agent (Patent Document 4).

[0008] JP 2003-321664 A JP 2006-057089 A JP 2008-274061 A JP 2023-071162 A

[0009] However, film- or sheet-like laminates produced using conventional adhesive compositions have not always exhibited good tear-open properties. Furthermore, depending on the type of resin constituting the substrate, the adhesive properties are not always good, leaving room for improvement. Furthermore, conventional adhesive compositions often contain aromatic isocyanates, which may violate regulations such as European Directives 2002 / 72 / EC and 2007 / 19 / EC. Therefore, there has been a demand for adhesive compositions that can exhibit good adhesive properties without using aromatic isocyanates.

[0010] The present invention has been made in view of the problems associated with the conventional techniques, and an object of the present invention is to provide a resin composition that is substantially free of solvent components and that can be used as a base component in a two-component curing adhesive composition that can be applied in the form of a thin film and that can be used to produce laminates of various laminate configurations that have excellent adhesive properties and tear-openability without using an aromatic isocyanate.

[0011] Another object of the present invention is to provide a two-component curing adhesive composition that uses the above-mentioned resin composition as a base component and that is substantially free of solvent components.A further object of the present invention is to provide a film- or sheet-like laminate produced using the above-mentioned adhesive composition.

[0012] That is, according to the present invention, there is provided the following resin composition. [1] A resin composition that is used as the main component (A) of a two-component curing adhesive composition containing a main component (A) and a curing agent (B), and that does not substantially contain a solvent component, comprising a polyester (a) having hydroxyl groups at the molecular terminals and a hydroxyl group concentration of 1.0 to 6.0 mol / kg, wherein the polyester (a) has structural units derived from a dicarboxylic acid (α) and structural units derived from a diol (β), and the structural units derived from the dicarboxylic acid (α) include structural units derived from an aromatic dicarboxylic acid (α1) and structural units derived from a non-aromatic dicarboxylic acid (α2), and the content of the structural units derived from the aromatic dicarboxylic acid (α1) exceeds 40 mol%, the structural units derived from the diol (β) include structural units derived from neopentyl glycol, and the content of the structural units derived from the diol (β) is less than 40 mol%, and the resin composition has a melt viscosity at 80°C of 10,000 mPa s or less. [2] The resin composition according to [1], wherein the content of structural units derived from the aromatic dicarboxylic acid (α1) among the structural units derived from the dicarboxylic acid (α) is 50 to 90 mol %. [3] The resin composition according to [1] or [2], wherein the content of structural units derived from the polyalkylene glycol (β1) among the structural units derived from the diol (β) is 30 mol % or less.

[0013] The present invention also provides the following adhesive compositions. [4] A two-component curing adhesive composition comprising a base agent (A) and a curing agent (B) and substantially free of solvent components, wherein the base agent (A) is the resin composition described in any one of [1] to [3] above. [5] The adhesive composition described in [4] above, wherein the curing agent (B) contains a non-aromatic isocyanate compound (b) having an isocyanate group content of 4 to 8 mol / kg, and the non-aromatic isocyanate compound (b) has in its molecular structure any bond selected from the group consisting of a biuret bond, an allophanate bond, and a cyanurate bond. [6] The adhesive composition described in [4] or [5] above, wherein the melt viscosity at 80°C is 5,000 mPa s or less. [7] The adhesive composition described in any one of [4] to [6] above, wherein the curing agent (B) is substantially free of aromatic isocyanate compounds. [8] The adhesive composition according to any one of [4] to [7], wherein the stoichiometric ratio (NCO / OH) of the isocyanate groups in the curing agent (B) to the hydroxyl groups in the main component (A) is 1.0 to 10.0.

[0014] Furthermore, according to the present invention, there is provided the following laminate: [9] A film- or sheet-like laminate comprising two types of substrates and an adhesive layer formed from the adhesive composition according to any one of [4] to [8] above, disposed between the substrates.

[0015] According to the present invention, it is possible to provide a resin composition that is substantially free of solvent components and that can be used as a base component in a two-component curing adhesive composition that can be applied in the form of a thin film and that can be used to produce laminates of various laminate configurations that have excellent adhesive properties and tear-openability without using an aromatic isocyanate.

[0016] The present invention also provides a two-component curing adhesive composition that uses the resin composition as a base and is substantially free of solvent components. Furthermore, the present invention also provides a film- or sheet-like laminate produced using the adhesive composition.

[0017] <Resin Composition> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the resin composition of the present invention is a resin composition that is used as the main component (A) of a two-component curing adhesive composition containing a main component (A) and a curing agent (B), and that contains substantially no solvent component. The resin composition of this embodiment includes a polyester (a) that has hydroxyl groups at its molecular terminals and has a hydroxyl group concentration of 1.0 to 6.0 mol / kg. The polyester (a) has structural units derived from a dicarboxylic acid (α) and structural units derived from a diol (β). The structural units derived from the dicarboxylic acid (α) include structural units derived from an aromatic dicarboxylic acid (α1) and structural units derived from a non-aromatic dicarboxylic acid (α2), and the content of structural units derived from aromatic dicarboxylic acid (α1) in the structural units derived from the dicarboxylic acid (α) is greater than 40 mol%. The structural units derived from the diol (β) include structural units derived from neopentyl glycol, and the content of structural units derived from the polyalkylene glycol (β1) in the structural units derived from the diol (β) is less than 40 mol%. The melt viscosity of the resin composition of this embodiment at 80°C is 10,000 mPa s or less. The resin composition of this embodiment will be described in detail below.

[0018] (Polyester (a)) The resin composition (main component (A)) of this embodiment contains a polyester (a) having a hydroxyl group at the molecular end. The content of the polyester (a) in the main component (A) is usually 80% by mass or more, preferably 95% by mass or more, and may be 100% by mass. In other words, the polyester (a) itself can be used as the main component (A). If the content of the polyester (a) in the main component (A) is less than 80% by mass, the tear-openability (hand tearability) of a laminate produced using this main component (A) may be slightly reduced.

[0019] The hydroxyl group concentration of the polyester (a) is 1.0 to 6.0 mol / kg, preferably 1.5 to 4.0 mol / kg. If the hydroxyl group concentration of the polyester (a) is less than 1.0 mol / kg, the viscosity of the adhesive composition increases, making it difficult to apply the adhesive composition in a thin film without using a solvent component. On the other hand, if the hydroxyl group concentration of the polyester (a) exceeds 6.0 mol / kg, the adhesive strength decreases and the hand tearability decreases.

[0020] The polyester (a) is a resin having a structural unit derived from a dicarboxylic acid (α) and a structural unit derived from a diol (β). Examples of the dicarboxylic acid (α) (acid component) include aromatic dicarboxylic acids (α1) and dicarboxylic acids other than aromatic dicarboxylic acids (α1) (non-aromatic dicarboxylic acids (α2)). Among the structural units derived from dicarboxylic acids (α), the content of structural units derived from aromatic dicarboxylic acids (α1) is more than 40 mol%, preferably 50 mol% or more. Among the structural units derived from dicarboxylic acids (α), the content of structural units derived from aromatic dicarboxylic acids (α1) is preferably 90 mol% or less, more preferably 80 mol% or less, and particularly preferably 70 mol% or less. If the content of structural units derived from aromatic dicarboxylic acids (α1) in the structural units derived from dicarboxylic acids (α) is too low, hand-tearability tends to decrease. When the aromatic dicarboxylic acid (α1) and the non-aromatic dicarboxylic acid (α2) are used in combination, the molar ratio may be 5.0:5.0 to 7.0:3.0.

[0021] The aromatic dicarboxylic acid (α1) is a compound in which two carboxy groups are bonded to an aromatic ring. Examples of the aromatic ring include a benzene ring, a pyridine ring, an imidazole ring, a naphthalene ring, a quinoline ring, and an anthraquinone ring. Preferred examples of the aromatic dicarboxylic acid (α1) include terephthalic acid, isophthalic acid, and phthalic acid. Acid anhydrides, alkyl esters, and the like can also be used as the aromatic dicarboxylic acid (α1).

[0022] Examples of non-aromatic dicarboxylic acids (α2) include adipic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, glutaric acid, 1,4-cyclohexyldicarboxylic acid, dimer acid, and hydrogenated dimer acid. Preferred examples of non-aromatic dicarboxylic acids (α2) include adipic acid and sebacic acid. The polyester (a) preferably contains a structural unit derived from an aromatic dicarboxylic acid (α1) and a structural unit derived from a non-aromatic dicarboxylic acid (α2). The polyester (a) may further contain a structural unit derived from a polycarboxylic acid (α3) having three or more carboxy groups.

[0023] Neopentyl glycol is used as the diol (β) (glycol component). That is, the structural units derived from the diol (β) include structural units derived from neopentyl glycol. Use of neopentyl glycol can improve hand-tearability. The content of the structural units derived from neopentyl glycol among the structural units derived from the diol (β) is preferably 20 to 80 mol %, and more preferably 30 to 70 mol %. Use of neopentyl glycol can further improve hand-tearability. By setting the content of the structural units derived from neopentyl glycol within the above range, hand-tearability can be further improved.

[0024] The structural units derived from the diol (β) may further contain structural units derived from diols other than neopentyl glycol. Examples of the other diols (glycol components) include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerin ether, 2-monoglycerin ether, dimer diol, and hydrogenated dimer diol. As other diols, 1,6-hexanediol, ethylene glycol, etc. are preferred.

[0025] The polyester (a) has structural units derived from a glycol other than polyalkylene glycol. By using a polyester (a) having structural units derived from a glycol other than polyalkylene glycol, hand tearability can be further improved. As the glycol other than polyalkylene glycol, it is preferable to use neopentyl glycol, 1,6-hexanediol, or ethylene glycol. For example, the molar ratio of "neopentyl glycol" to "1,6-hexanediol + ethylene glycol" may be 3.0:7.0 to 5.0:5.0.

[0026] The structural units derived from the diol (β) preferably include structural units derived from 1,6-hexanediol. The content of the structural units derived from 1,6-hexanediol among the structural units derived from the diol (β) is preferably 20 to 70 mol %, and more preferably 20 to 50 mol %. By setting the content of the structural units derived from 1,6-hexanediol among the structural units derived from the diol (β) within the above range, cutting ability can be imparted to a wide range of combinations of base materials.

[0027] Among the constituent units derived from the diol (β), the content of the constituent units derived from the polyalkylene glycol (β1) is less than 40 mol%, preferably 30 mol% or less, and more preferably 20 mol% or less. The lower limit of the content of the constituent units derived from the polyalkylene glycol (β1) among the constituent units derived from the diol (β) is not particularly limited, but may be 0 mol%. In other words, the constituent units derived from the diol (β) may not contain any constituent units derived from the polyalkylene glycol (β1).

[0028] Polyalkylene glycols are compounds (polyols) in which two or more alkylene chains are bonded via ether bonds. Examples of polyalkylene glycols include diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, dibutylene glycol, and polytetramethylene glycol.

[0029] The polyester (a) may further contain a structural unit derived from an alcohol (another alcohol (β2)) other than the diol (β). Examples of the other alcohol (β2) include known monoalcohols, polyalcohols, and hydroxy acids.

[0030] The polyester (a) may also be a glycol decomposition product of a high molecular weight polyester compound having a structural unit derived from a dicarboxylic acid (α), such as polyethylene terephthalate (PET). Examples of such glycol decomposition products include bis-2-hydroxyethyl terephthalate. Methods for utilizing the glycol decomposition products include blending and reactions with other components, such as transesterification.

[0031] It is also preferable to use a urethane-modified polyester having a urethane bond in its molecular structure as the polyester (a). The urethane-modified polyester is a resin obtained by urethane-modifying a polyester having hydroxyl groups at its molecular terminals by reacting a polyisocyanate with some of the hydroxyl groups. It is preferable that the urethane-modified polyester does not substantially contain structural units derived from aromatic isocyanates. In other words, it is preferable that the polyisocyanate reacted with some of the hydroxyl groups of the polyester is a non-aromatic isocyanate.

[0032] (Other components) The main component (A) may further comprise other components other than the above-mentioned polyester (a).The other components can include known hydroxyl group-containing compounds such as polyester polyols other than polyester (a) (including polyesters obtained by ring-opening reaction of cyclic esters), polyether polyols, polyester polyether polyols, polycarbonate polyols, polyurethane polyols, acrylic polyols, epoxy polyols, the above-mentioned diols (β), and other alcohols (β2).For example, by adding diols (β), the melt viscosity of the main component (A) can be reduced.

[0033] (Resin Composition (Main Component (A))) The resin composition (main component (A)) of this embodiment has a melt viscosity at 80°C of 10,000 mPa·s or less, preferably 5,000 mPa·s or less, and more preferably 3,000 mPa·s or less. If the viscosity of the main component (A) at 80°C exceeds 10,000 mPa·s, it becomes difficult to apply the composition in a thin film without using a solvent component. While it is possible to reduce the melt viscosity of the adhesive composition by increasing the temperature during application, applying the adhesive composition at a temperature above 80°C reduces the usable time of the adhesive composition, making it less practical.

[0034] The main component (A) is a resin composition that is substantially free of solvent components. If a main component (A) that substantially contains a solvent component is used, the solvent component remaining in the laminate may cause poor curing and reduce hand-tearability. Furthermore, if the solvent component is an organic solvent, it may cause odors and the like. "Substantially free of solvent components" means that the nonvolatile content is 98% by mass or more. There is a possibility that trace amounts of moisture, by-products and decomposition products during the reaction, etc. may be mixed in as volatile components.

[0035] <Adhesive Composition> One embodiment of the adhesive composition of the present invention is a two-component curing adhesive composition that contains a main component (A) and a curing agent (B) and is substantially free of solvent components. The main component (A) is the resin composition described above. The adhesive composition of this embodiment will be described in detail below.

[0036] (Curing Agent (B)) The adhesive composition of this embodiment contains a curing agent (B) reactive with the main component (A). For example, the curing agent (B) may be one primarily composed of a compound having an isocyanate group. As the compound having an isocyanate group, a non-aromatic isocyanate compound (b) without an aromatic ring in its molecular structure is preferred. The isocyanate group content of the curing agent (B) is preferably 4 to 8 mol / kg, more preferably 4.5 to 6.5 mol / kg. If the isocyanate group content of the curing agent (B) is too low, hand tearability may be reduced depending on the type of substrate. Furthermore, curing agents (B) with an isocyanate group content of 8 mol / kg or more have a small molecular weight and high vapor pressure, so they may require careful handling. Furthermore, the non-aromatic isocyanate compound (b) is preferably a compound having a bond selected from the group consisting of a biuret bond, an allophanate bond, and a cyanurate bond in its molecular structure.

[0037] Examples of the non-aromatic isocyanate compound (b) include compounds derived from isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexane diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, and lysine triisocyanate. Among these, it is preferable to use biuret, allophanate, and cyanurate forms of hexamethylene diisocyanate and tetramethylene diisocyanate.

[0038] The melt viscosity of the curing agent (B) at 80°C is preferably 2,000 mPa s or less, more preferably 1,000 mPa s or less, and particularly preferably 500 mPa s or less. If the viscosity of the curing agent (B) at 80°C exceeds 2,000 mPa s, the isocyanate group content tends to be low. This may result in poor hand-cuttability, a shortened pot life, and poor processability.

[0039] It is preferable that the curing agent (B) is substantially free of aromatic isocyanate compounds. Even when a curing agent (B) containing an aromatic isocyanate compound is used, an adhesive composition capable of producing laminates with excellent adhesion and tear-openability can be obtained. However, in consideration of conflicts with regulations such as European Directives 2002 / 72 / EC and 2007 / 19 / EC, it is preferable to minimize the content of aromatic isocyanate compounds, and it is preferable to use a curing agent (B) that is substantially free of aromatic isocyanate compounds. Furthermore, even when a curing agent (B) that does not contain an aromatic isocyanate compound is used, a two-component curing adhesive composition that can be applied in the form of a thin film can be obtained, which can produce laminates with various laminate configurations with excellent adhesion and tear-openability.

[0040] (Two-component curing adhesive composition) In the adhesive composition of this embodiment, the stoichiometric ratio (NCO / OH) of isocyanate groups in the curing agent (B) to hydroxyl groups in the base component (A) is preferably 1.0 to 10.0, and more preferably 1.2 to 6.0. If the stoichiometric ratio (NCO / OH) is less than 1.0, the hand tearability of the resulting laminate may be slightly reduced, and the curing of the adhesive composition may be somewhat insufficient. On the other hand, if the stoichiometric ratio (NCO / OH) is more than 10.0, the adhesive composition tends to foam easily when cured, and curing tends to take a long time.

[0041] The melt viscosity of the adhesive composition containing the base agent (A) and the curing agent (B) at 80°C is preferably 5,000 mPa s or less, more preferably 1,500 mPa s or less, and particularly preferably 1,000 mPa s or less. If the viscosity of the adhesive composition at 80°C exceeds 5,000 mPa s, it becomes difficult to coat the adhesive composition into a thin film without using a solvent component.

[0042] The main component (A) and curing agent (B) constituting the adhesive composition of this embodiment may each contain a component having structural units derived from a biologically-derived component, or may contain the biologically-derived component itself. For example, the polyester (a) used as the main component of the main component (A) has a higher hydroxyl group concentration and a lower degree of polymerization than components such as main components used in conventional solvent-diluted adhesives. This makes it less likely that problems such as viscosity abnormalities during synthesis due to impurities in the biologically-derived component, such as malic acid, will occur. Therefore, biologically-derived components containing impurities (e.g., malic acid) can be actively used.

[0043] The adhesive composition of the present embodiment may contain, as needed, colorants such as pigments and dyes, dispersants, surfactants, foam stabilizers, antifoaming agents, viscosity modifiers, leveling agents, stabilizers, UV absorbers, coupling agents, antiblocking agents, catalysts, pot life extenders, plasticizers, fillers, and the like.

[0044] <Laminate> One embodiment of the laminate of the present invention is a film- or sheet-like laminate comprising two types of substrates and an adhesive layer formed from the adhesive composition described above, disposed between these substrates.

[0045] The substrate may be, for example, a film- or sheet-shaped substrate made of resin. The substrate may be subjected to a conventionally known surface treatment, if necessary. Examples of resins constituting the substrate include polyolefin resins such as polyethylene resin and polypropylene resin, polystyrene resin, polyvinyl chloride resin, ABS resin, polycarbonate resin, acrylic resin, fluorine-based resin, polyvinyl alcohol resin, polyvinyl alcohol-ethylene copolymer resin, polyamide resins such as 6-nylon, and polyester resins such as polyethylene terephthalate. The substrate may also be a foam obtained by foaming these resins. The surface of the substrate may be provided with various polymer coatings such as polyvinylidene chloride, or an inorganic layer formed by metal vapor deposition, silica vapor deposition, alumina vapor deposition, or the like. Furthermore, the substrate may be laminated with metal materials such as aluminum foil or copper foil, woven fabric, nonwoven fabric, paper, or the like.

[0046] Conventional laminates made using non-oriented linear low-density polyethylene resin films or polypropylene resin films as substrates are difficult to tear due to the high viscosity of the resins. Therefore, to obtain laminates with good hand-tearability, it has been necessary to use adhesive compositions containing large amounts of solvent components. Furthermore, to produce laminates with good hand-tearability using solvent-free adhesive compositions, it has been necessary to use adhesive compositions containing aromatic isocyanates.

[0047] In contrast, when the adhesive composition of the present embodiment is used, a film- or sheet-like laminate with excellent tear-open properties can be produced when a non-oriented linear low-density polyethylene resin film or polypropylene resin film is used as the substrate, without using an aromatic isocyanate or solvent component.

[0048] Furthermore, the adhesive composition of the present embodiment can be easily applied in a thin film by a method such as a squeeze roll coating method that does not use a solvent component, even to substrates that are difficult to apply in a thin film without using a solvent component, such as polyvinyl chloride resin, ABS resin, polycarbonate resin, fluorine-based resin, and acrylic resin, and the adhesive composition exhibits excellent adhesive properties.

[0049] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0050] <Resin Production> (Example 1) 83.1 parts of isophthalic acid (iPA), 73.1 parts of adipic acid (AA), 61.5 parts of 1,6-hexanediol (16HD), 40.6 parts of neopentyl glycol (NPG), and 24.2 parts of ethylene glycol (EG) were placed in a flask. Under a nitrogen stream, the mixture was heated to 230°C and stirred for 5 hours, allowing an esterification reaction to occur while distilling off water. When the distillation of water stopped, 0.1 parts of tetra-n-butoxytitanium and 0.1 parts of triphenyl phosphite were added. The mixture was heated to 250°C and reduced pressure to 10 Torr to allow polycondensation, yielding Resin a1, a hydroxyl-terminated polyester polyol. The hydroxyl group concentration of the resulting Resin a1 was 1.80 mol / kg, and the melt viscosity at 80°C was 782 mPa·s. The hydroxyl group concentration of the resin was measured in accordance with JIS K0070. The melt viscosity of the resin at 80° C. was measured using a BM type rotational viscometer.

[0051] (Examples 2 to 9, Comparative Examples 1 to 8) Resins a2 to a9 and a101 to a108, which are hydroxyl-terminated polyester polyols, were obtained in the same manner as in Example 1 above, except that the formulations shown in Tables 1-1 and 1-2 were used. The hydroxyl group concentration and melt viscosity at 80°C of each of the obtained resins are shown in Tables 1-1 and 1-2. The abbreviations in Tables 1-1 to 1-3 have the following meanings: BHET: bis(2-hydroxyethyl) terephthalate DMT: dimethyl terephthalate tPA: terephthalic acid iPA: isophthalic acid PA: phthalic anhydride AA: adipic acid SA: sebacic acid (component derived from 100% biomass) 16HD: 1,6-hexanediol EG: ethylene glycol NPG: neopentyl glycol DEG: diethylene glycol

[0052]

[0053]

[0054] Example 10: 58.6 parts of resin a4 (polyester polyol, Mn: 586) obtained in Example 4, 11.1 parts of isophorone diisocyanate, and 0.6 parts of zinc octoate were placed in a flask. The mixture was heated to 80°C under a nitrogen stream and stirred for 7 hours to allow the mixture to react. This resulted in resin a110, a hydroxyl-terminated urethane-modified polyester. The hydroxyl group concentration of the resulting resin a110 was 1.4 mol / kg, and the melt viscosity at 80°C was 4,820 mPa·s.

[0055] Comparative Example 9: 1,000 parts of polypropylene glycol having a number average molecular weight of 1,000 and 125 parts of diphenylmethane-4,4'-diisocyanate were placed in a flask. The mixture was heated to 75°C under a nitrogen stream and stirred for 8 hours to carry out a polyaddition reaction, yielding Resin a111, a hydroxyl-terminated polyurethane. The hydroxyl group concentration of the resulting Resin a111 was 0.9 mol / kg, and the melt viscosity at 80°C was 330 mPa s.

[0056] Comparative Examples A-1 and B-1 Resins A and B, which are hydroxyl-terminated polyester polyols, were obtained in the same manner as in Example 1, except that the formulations shown in Table 1-3 were used and the description in the Examples of JP-A No. 2003-96428 (paragraphs

[0029] and

[0030] ) was taken into consideration. The hydroxyl group concentrations of each of the obtained resins are shown in Table 1-3.

[0057]

[0058] <Production of Curing Agent> (Production Example 1) 325 parts of polytetramethylene glycol (number average molecular weight: 650), 500 parts of polypropylene glycol (number average molecular weight: 1,000), and 500 parts of diphenylmethane-4,4'-diisocyanate were placed in a flask. The mixture was heated to 75°C and stirred for 8 hours under a nitrogen stream to allow a polyaddition reaction. This resulted in the production of a terminal isocyanate polyurethane b109. The resulting polyurethane b109 had an isocyanate group content of 1.5 mol / kg and a melt viscosity at 80°C of 330 mPa s.

[0059] (Production Example 2) 1,000 parts of polypropylene glycol (number average molecular weight: 1,000) and 500 parts of diphenylmethane-4,4'-diisocyanate were placed in a flask. The mixture was heated to 75°C under a nitrogen stream and stirred for 8 hours to allow a polyaddition reaction. This resulted in the production of a terminal isocyanate polyurethane b110. The resulting polyurethane b110 had an isocyanate group content of 1.3 mol / kg and a melt viscosity at 80°C of 330 mPa s.

[0060] <Preparation of curing agents> The types of curing agents shown in Table 2 were prepared. In Table 2, "Coronate L" and "Desmodur RE" contain a solvent (ethyl acetate) and therefore cannot be heated to 80°C, and therefore their melt viscosity at 80°C was marked as "unmeasurable." Furthermore, "VESTANT T1890 / 100" is solid at 80°C, and therefore its melt viscosity at 80°C was marked as "unmeasurable." However, for any of the curing agents, the melt viscosity at 80°C can be measured by blending it with other curing agents, for example.

[0061]

[0062] <Preparation of adhesive compositions> (Examples 11 to 20, Comparative Examples 10 to 19) Adhesive compositions c1 to c10 and c101 to c110 were prepared by mixing the components to obtain the compositions shown in Tables 3-1 and 3-2. In Tables 3-1 and 3-2, "BPE" refers to a 1:1 (mass ratio) mixture of polyether polyols (trade names "Newpol BPE-20" and "Newpol BPE-40" (both manufactured by Sanyo Chemical Industries, Ltd.)) with a hydroxyl group concentration of 4.9 mol / kg and a melt viscosity at 80°C of 110 mPa·s. The "silane coupling agent" used was "Shin-Etsu Silicone KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). The catalysts used were "U-650" (trade name "Neostan U-650" manufactured by Nitto Kasei Co., Ltd.) and "SA102" (trade name "U-CAT-SA102" manufactured by San-Apro Co., Ltd.).

[0063]

[0064]

[0065] (Comparative Examples A-2 and B-2) Adhesive compositions A and B were prepared in the same manner as in Examples 11 to 20 and Comparative Examples 10 to 19, except that the components were mixed to obtain the compositions shown in Table 3-3.

[0066]

[0067] <Production of Laminate> The prepared adhesive composition was applied to each of the first substrates shown in Tables 4-1 to 4-3 and 5 to form a coating film with a thickness of 1.5 μm. A second substrate shown in Tables 4-1 to 4-3 and 5 was placed on the formed coating film and bonded to it, and then stored at 40° C. for 3 days to obtain a laminate. Details of the first substrate and second substrate in Tables 4-1 to 4-3 and 5 are shown below.・Ny:ink ... White ink coated biaxially oriented nylon resin film (thickness: 15 μm) ・LL ... Linear low-density polyethylene resin film (thickness: 50 μm) ・Barrier NY ... Barrier nylon resin film (thickness: 15 μm) ・Transparent vapor deposition NY ... Nylon resin film with a binary vapor deposition layer of alumina or silica (thickness: 15 μm) ・DOF ... Wood grain printed olefin resin decorative film for building materials (thickness: 65 μm) ・A-PET ... Amorphous PET resin sheet (thickness: 400 μm) ・Acrylic ... Wood grain printed thermoplastic acrylic resin decorative film (thickness: 125 μm) ・PVC ... Semi-rigid PVC resin sheet (thickness: 250 μm) ・PCTFE ... Polychlorotrifluoroethylene resin film (thickness: 50 μm)

[0068] <Evaluation> (Solventless Coatability) Coatability when a thin film of 1.5 μm thick was applied using a squeeze roll coater (coatability using a squeeze roll coating method) was evaluated according to the following evaluation criteria. The results are shown in Tables 4-1 and 4-2. ○: Appearance is good ×: Uncoatable

[0069] (Adhesion) The first substrate and second substrate of the produced laminate were peeled off at a temperature of 25°C, and the peel strength (N / 15 mm) was measured, and the adhesion was evaluated according to the following evaluation criteria. The results are shown in Tables 4-1, 4-2, and 5. ⊚: Peel strength was 5 N / 15 mm or more. ◯: Peel strength was 1 N / 15 mm or more and less than 5 N / 15 mm. ×: Peel strength was less than 1 N / 15 mm. ND: No data available (due to inability to coat, etc.).

[0070] (Tear-opening property) A cut was made with a cutter knife in the printed portion of the produced laminate. The laminate was torn along this cut, and the state was observed, and the tear-opening property was evaluated according to the following evaluation criteria. The results are shown in Tables 4-1 to 4-3. ○: The laminate surface was not exposed. ×: The film was stretched and the laminate surface was exposed. ND: No data available (due to inability to coat, etc.).

[0071]

[0072]

[0073]

[0074]

[0075] By using the adhesive composition of the present invention, it is possible to produce not only film-like and sheet-like laminates that have excellent adhesive properties and tear-openability, but also various laminates that have excellent adhesive properties and can be applied to molding processes that take advantage of thermoplasticity, while reducing the burden on the environment.

Claims

1. A resin composition substantially free of solvent components, used as the main component (A) of a two-component curing adhesive composition containing the main component (A) and the curing agent (B), comprising a polyester (a) having hydroxyl groups at molecular terminals and a hydroxyl group concentration of 1.0 to 6.0 mol / kg, the polyester (a) having structural units derived from a dicarboxylic acid (α) and structural units derived from a diol (β), the structural units derived from the dicarboxylic acid (α) including structural units derived from an aromatic dicarboxylic acid (α1) and structural units derived from a non-aromatic dicarboxylic acid (α2), and the content of the structural units derived from the aromatic dicarboxylic acid (α1) exceeds 40 mol%, the molar ratio of the structural units derived from the aromatic dicarboxylic acid (α1) to the structural units derived from the non-aromatic dicarboxylic acid (α2) being 5.0:5.0 to 7.0:3.0, a resin composition having a melt viscosity at 80°C of 10,000 mPa s or less, wherein the structural units derived from the diol (β) include structural units derived from neopentyl glycol, and the content of structural units derived from polyalkylene glycol (β1) in the structural units derived from the diol (β) is less than 40 mol%.

2. The resin composition according to claim 1, wherein the structural units derived from the diol (β) further include structural units derived from 1,6-hexanediol and structural units derived from ethylene glycol, and the molar ratio of the structural units derived from the neopentyl glycol to the sum of the structural units derived from the 1,6-hexanediol and the structural units derived from the ethylene glycol is 3.0:7.0 to 5.0:5.

0.

3. A resin composition according to claim 1 or 2, wherein the content of structural units derived from the aromatic dicarboxylic acid (α1) in the structural units derived from the dicarboxylic acid (α) is 50 to 70 mol %.

4. A resin composition according to any one of claims 1 to 3, wherein the content of structural units derived from polyalkylene glycol (β1) in the structural units derived from the diol (β) is 30 mol% or less.

5. A two-component curing adhesive composition that contains a main component (A) and a curing agent (B) and is substantially free of solvent components, wherein the main component (A) is the resin composition described in any one of claims 1 to 4.

6. The adhesive composition according to claim 5, wherein the curing agent (B) contains a non-aromatic isocyanate compound (b) having an isocyanate group content of 4 to 8 mol / kg, and the non-aromatic isocyanate compound (b) has in its molecular structure any bond selected from the group consisting of a biuret bond, an allophanate bond, and a cyanurate bond.

7. The adhesive composition according to claim 5 or 6, which has a melt viscosity at 80°C of 5,000 mPa·s or less.

8. The adhesive composition according to claim 6, wherein the curing agent (B) is substantially free of aromatic isocyanate compounds.

9. The adhesive composition according to any one of claims 5 to 8, wherein the stoichiometric ratio (NCO / OH) of isocyanate groups in the curing agent (B) to hydroxyl groups in the main component (A) is 1.0 to 10.

0.

10. A film- or sheet-like laminate comprising two types of substrates and an adhesive layer formed from the adhesive composition according to any one of claims 5 to 9, disposed between the substrates.

Images