Adhesive and reactive hot-melt adhesive

Abstract

The present invention pertains to an adhesive containing a polyester (A) that satisfies the following requirements (1)-(4): (1) the polyester (A) has a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2); (2) the polyester (A) has an ester bond concentration of not more than 10.00 millimoles / g; (3) the polyester (A) has a melting point of 30°C or higher; and (4) the polyester (A) has a mass average molecular weight of 25,000 or more.

Description

Adhesives and reactive hot melt adhesives

[0001] The present invention relates to adhesives and reactive hot melt adhesives.

[0002] Conventionally, polyester resins have been used in a wide range of applications, such as films, PET bottles, fibers, toners, electrical components, adhesives, and pressure-sensitive adhesives, due to their excellent heat resistance, chemical resistance, durability, and mechanical strength. Furthermore, polyester resins are highly polar due to their polymer structure, and are known to exhibit excellent adhesion to polar polymers such as polyester, polyvinyl chloride, polyimide, and epoxy resins, as well as metal materials such as copper and aluminum. In recent years, from the perspective of environmental friendliness, there has been a demand for hot melt adhesives that can be applied without solvents.

[0003] Hot melt adhesives are solid or semi-solid at room temperature and become fluid when heated. Reactive hot melt adhesives are primarily composed of urethane prepolymers with isocyanate groups at their terminals. Many of these are moisture-curing urethane adhesives, typically in the form of an isocyanate-containing urethane prepolymer formed by addition polymerization of a polyol component and an isocyanate component. These reactive hot melt adhesives are applied to a substrate in a heated, molten state. After cooling and solidifying, moisture curing occurs due to a chemical crosslinking reaction between the isocyanate groups and water, forming a tough, heat-resistant, and chemical-resistant coating, i.e., an adhesive layer.

[0004] For example, Patent Documents 1 and 2 describe reactive hot melt adhesives using polyester polyol, and Patent Document 3 describes a reactive hot melt adhesive to which an acrylic polymer is added as a high molecular weight component.

[0005] Japanese special table No. 2007-523240 Japanese special table No. 2018-512472 Publication Japanese special table No. 2008-500406

[0006] As noted in Patent Document 1, in recent years, not only is high adhesion and strength required after moisture curing, but high adhesion and strength are also required before moisture curing in order to improve productivity (hereinafter, the strength after moisture curing will also be referred to as "final strength," and the strength before moisture curing will also be referred to as "initial strength"). Therefore, in order to improve the initial strength, Patent Document 1 describes a method using a crystalline polyol that uses a linear aliphatic dicarboxylic acid having 13 to 22 methylene groups. Similarly, Patent Document 2 also describes a method using a crystalline polyester polyol as a method for improving the initial strength.

[0007] However, in systems consisting only of low-molecular-weight polyols and isocyanates, as described above, the absence of high-molecular-weight components before moisture curing can result in insufficient cohesive strength, making it difficult to achieve the high levels of early strength required in recent years. Conversely, if a design is made to easily achieve early strength by increasing the amount of crystalline polyol and using cohesive strength derived from crystallinity, the crystallinity can in turn result in poor adhesion to the adherend interface, resulting in poor final strength. For these reasons and other reasons, it has been difficult to achieve both high levels of early strength and final strength.

[0008] Furthermore, in Patent Document 3, by including an acrylic polymer as a high molecular weight component in the adhesive, it is possible to achieve both initial strength and final strength, but there are problems in that the acrylic polymer is prone to generating VOCs (Volatile Organic Compounds) and odors derived from residual monomers and chain transfer agents, and further it is difficult to implement a high biomass design, which has become important in recent years from the perspective of environmental friendliness.

[0009] Therefore, we investigated the design of a high molecular weight polyester suitable for reactive hot melt adhesives. Polyesters are considered to have advantages such as being easy to design for high biomass content and having fewer VOCs than acrylic polymers. However, as the molecular weight of polyester increases, it becomes less soluble in the liquid polyols commonly used in reactive hot melt adhesives. Even soluble resin compositions can be difficult to handle in solvent-free systems. For example, due to their nature, they cannot be handled in pellet or flake form. These problems made the application of high molecular weight polyesters to hot melt adhesives difficult.

[0010] The present invention provides an adhesive containing a polyester (A) that satisfies the following constituent requirements (1) to (4): (1) the polyester (A) has a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), (2) the ester bond concentration of the polyester (A) is 10.00 mmol / g or less, (3) the melting point of the polyester (A) is 30°C or higher, and (4) the weight average molecular weight of the polyester (A) is 25,000 or higher.

[0011] More specifically, the present invention is as follows.

[0012] A first aspect of the present invention is an adhesive containing a polyester (A) that satisfies the following constituent requirements (1) to (4): (1) the polyester (A) has a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), (2) the ester bond concentration of the polyester (A) is 10.00 mmol / g or less, (3) the melting point of the polyester (A) is 30°C or higher, and (4) the weight average molecular weight of the polyester (A) is 25,000 or higher.

[0013] Aspect 2 of the present invention is the adhesive of Aspect 1, wherein the polyester (A) further satisfies the following constituent requirement (5): (5) In the polyester (A), the structural moieties derived from the aliphatic polycarboxylic acid (a1-1) account for 50 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1).

[0014] A third aspect of the present invention is the adhesive of the first or second aspect, wherein the polyester (A) further satisfies the following constituent requirement (6): (6) The hydroxyl value of the polyester (A) is less than 12 mgKOH / g.

[0015] A fourth aspect of the present invention is the adhesive of any one of the first to third aspects, wherein the polyester (A) has a solubility parameter (SP value) of 10.50 (cal / cm ３ ) １／２ Below is the adhesive.

[0016] A fifth aspect of the present invention is the adhesive of any one of the first to fourth aspects, wherein the content of organic solvent in the adhesive is 5 mass % or less.

[0017] A sixth aspect of the present invention is the adhesive according to any one of the first to fifth aspects, wherein the structural moiety derived from a monomer having an aromatic ring accounts for 30 mass % or less of the total mass of the polyester (A).

[0018] A seventh aspect of the present invention is the adhesive of any one of the first to sixth aspects, wherein the glass transition temperature of the polyester (A) is 0° C. or lower.

[0019] Aspect 8 of the present invention is the adhesive according to any one of aspects 1 to 7, wherein the polyester (A) has a crystalline heat of fusion of 3 J / g or more.

[0020] A ninth aspect of the present invention is the adhesive of any one of aspects 1 to 8, wherein the polyester (A) has a mass average molecular weight of 30,000 or more.

[0021] A tenth aspect of the present invention is the adhesive of any one of aspects 1 to 9, wherein the polyester (A) has a mass average molecular weight of 40,000 or more.

[0022] An eleventh aspect of the present invention is a reactive hot melt adhesive containing a urethane prepolymer (X) having an isocyanate group, the reactive hot melt adhesive comprising the adhesive of any one of aspects 1 to 10.

[0023] A twelfth aspect of the present invention is the reactive hot melt adhesive of the eleventh aspect, wherein the urethane prepolymer (X) contains a structural moiety derived from the polyalkylene glycol (B).

[0024] A thirteenth aspect of the present invention is the reactive hot melt adhesive of the twelfth aspect, wherein the polyalkylene glycol (B) has an average molecular weight of 200 to 5,000.

[0025] A fourteenth aspect of the present invention is the reactive hot melt adhesive of any one of Aspects 11 to 13, wherein the urethane prepolymer (X) includes a structural moiety derived from a polyester polyol (C) different from the polyester (A).

[0026] A fifteenth aspect of the present invention is the reactive hot melt adhesive of the fourteenth aspect, wherein the polyester polyol (C) has an average molecular weight of 500 to 5,500.

[0027] The polyester used in the adhesive of the present invention is a resin with excellent handleability, for example, in pellet form, and is soluble in liquid polyols such as polypropylene glycol, which are commonly used in reactive hot melt adhesives. Therefore, the polyester can be used in applications such as hot melt adhesives and reactive hot melt adhesives. Furthermore, because the polyester used in the present invention has a low VOC content, an adhesive according to one embodiment of the present invention using such a polyester has excellent low odor characteristics and, when used as a reactive hot melt adhesive, can achieve both high initial and final adhesive strengths.

[0028] As a result of extensive research, the present inventors have discovered a high molecular weight polyester for use in adhesives that has excellent solubility in liquid polyols commonly used in reactive hot melt adhesives and that can be handled, for example, in pellet form, and have completed the present invention. Even more surprisingly, the high molecular weight polyester used in the adhesive of the present invention has a lower VOC content than low molecular weight polyester polyols.

[0029] In other words, the high molecular weight polyester used in the adhesive of the present invention can be suitably used as a raw material resin for hot melt adhesives and reactive hot melt adhesives, which not only achieves high levels of initial strength and final strength, but also makes it possible to design hot melt adhesives and reactive hot melt adhesives that are low in odor and VOC.

[0030] The following is a detailed description of the configuration of the present invention, which is merely an example of a preferred embodiment. In the present invention, "x and / or y (x and y are optional configurations or components)" means three combinations: x only, y only, and x and y.

[0031] 1. Adhesive The adhesive of this embodiment contains a polyester (A) that satisfies the following constituent requirements (1) to (4): (1) The polyester (A) has a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2); (2) The ester bond concentration of the polyester (A) is 10.00 mmol / g or less; (3) The melting point of the polyester (A) is 30°C or higher; and (4) The weight average molecular weight of the polyester (A) is 25,000 or higher.

[0032] The adhesive of the present embodiment can be used as an adhesive, a hot melt adhesive, or a reactive hot melt adhesive. In addition, by adjusting the polyester (A), a high biomass design is possible, and the adhesive of the present embodiment using the polyester (A) has excellent low odor characteristics and environmental friendliness, and further, when used as a hot melt adhesive or a reactive hot melt adhesive, it can achieve both initial adhesive strength and final adhesive strength.

[0033] The adhesive of this embodiment contains a polyester (A) containing a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2). First, the polyester (A) will be described.

[0034] <Polyester (A)> The polyester (A) used in the adhesive of the present embodiment contains a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2) in the molecule, and it is preferable that the structural moiety derived from an aliphatic polycarboxylic acid (a1-1) accounts for 50 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1).

[0035] When the structural moiety derived from the aliphatic polycarboxylic acid (a1-1) is 50 mol% or more relative to the total structural moieties derived from the polycarboxylic acid (a1), the adhesive tends to exhibit excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives. The structural moiety derived from the aliphatic polycarboxylic acid (a1-1) is preferably 65 mol% or more, more preferably 75 mol% or more, even more preferably 85 mol% or more, and particularly preferably 95 mol% or more relative to the total structural moieties derived from the polycarboxylic acid (a1).

[0036] [Polycarboxylic Acids (a1)] Examples of polycarboxylic acids constituting the structural moiety derived from the polycarboxylic acid (a1) include the aliphatic polycarboxylic acids (a1-1) described below, the aromatic polycarboxylic acids described below, and the alicyclic polycarboxylic acids described below. One or more types of polycarboxylic acids can be used.

[0037] Examples of the aliphatic polycarboxylic acids constituting the structural moiety derived from the aliphatic polycarboxylic acids (a1-1) include straight-chain aliphatic carboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, and branched aliphatic polycarboxylic acids such as dimer acids. Among these, in order to impart crystallinity to the resulting polyester (A) and improve handling and adhesive strength when used as an adhesive, it is preferable to contain straight-chain aliphatic carboxylic acids, and more preferably to contain those with an even number of carbon atoms. Furthermore, in order to improve solubility in liquid polyols such as polypropylene glycol, which are commonly used in reactive hot melt adhesives, the polyester (A) in the adhesive of this embodiment preferably contains an aliphatic polycarboxylic acid having 8 or more carbon atoms.

[0038] Examples of dimer acids include dimer acids (mainly having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc., and hydrogenated products thereof. Among these, hydrogenated products are preferred from the viewpoint of inhibiting gelation during the production of polyester resins.

[0039] The structural moiety derived from the aliphatic polycarboxylic acid (a1-1) is preferably 50 mol% or more, more preferably 65 mol% or more, even more preferably 75 mol% or more, particularly preferably 85 mol% or more, and particularly preferably 95 mol% or more, based on the total structural moieties derived from the polycarboxylic acid (a1). When the structural moiety derived from the aliphatic polycarboxylic acid (a1-1) is 50 mol% or more based on the total structural moieties derived from the polycarboxylic acid (a1), the adhesive tends to exhibit excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives. The content (mol%) of the structural moiety derived from the aliphatic polycarboxylic acid (a1-1) based on the total structural moieties derived from the polycarboxylic acid (a1) can be calculated using the following formula 1. [Formula 1] Content (mol%) of aliphatic polycarboxylic acid = (aliphatic polycarboxylic acid (mol) / polycarboxylic acid (mol)) × 100

[0040] Examples of aromatic polycarboxylic acids include monocyclic aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl isophthalate, and orthophthalic acid; polycyclic aromatic polycarboxylic acids such as biphenyldicarboxylic acid, naphthalenedicarboxylic acid, and dimethyl naphthalenedicarboxylate; and among polycyclic aromatic polycarboxylic acids, condensed polycyclic aromatic polycarboxylic acids such as naphthalenedicarboxylic acid and dimethyl naphthalenedicarboxylate and derivatives thereof (aromatic dicarboxylic acids). Other examples include aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Furthermore, trivalent or higher aromatic polycarboxylic acids introduced into polyester resins for the purpose of imparting a branched skeleton or acid value are also included in the above aromatic polycarboxylic acids. Examples of trivalent or higher aromatic polyvalent carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride.

[0041] The content of the structural moiety derived from aromatic polycarboxylic acids in the entire polycarboxylic acids (a1) is preferably 50 mol% or less, more preferably 30 mol% or less, even more preferably 15 mol% or less, and particularly preferably 10 mol% or less. When the content of aromatic polycarboxylic acids is 50 mol% or less, the adhesive tends to exhibit excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives.

[0042] The content (mol %) of aromatic polycarboxylic acids relative to the total polycarboxylic acids (a1) can be calculated from the following formula 2: [Formula 2] Content (mol %) of aromatic polycarboxylic acids = (aromatic polycarboxylic acids (mol) / polycarboxylic acids (mol)) x 100

[0043] The content of the structural moiety derived from aromatic polycarboxylic acids in the entire polyester (A) is preferably 30% by mass or less, and more preferably 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, and 2% by mass or less. When the content of the structural moiety derived from aromatic polycarboxylic acids in the entire polyester (A) is 30% by mass or less, the polyester (A) tends to have excellent solubility in liquid polyols such as polypropylene glycol that are generally used in reactive hot melt adhesives.

[0044] When imparting an acid value to the polyester (A), it is preferable that the structural moiety derived from the polycarboxylic acid (a1) contains a structural moiety derived from a trivalent or higher polycarboxylic acid. The valence of the carboxy group in the structural moiety derived from the trivalent or higher polycarboxylic acid is preferably 3 to 6, more preferably 3 to 4. Examples of such trivalent or higher polycarboxylic acids include the above-mentioned trivalent or higher aromatic polycarboxylic acids. Examples include trimellitic anhydride, trimellitic acids, and trimesic acids. Examples of trivalent or higher polycarboxylic acids other than those mentioned above include hydrogenated trimellitic acid and hydrogenated trimellitic anhydride. Among these, those having an acid anhydride group are preferred, and structural moieties derived from trimellitic anhydride and hydrogenated trimellitic anhydride are particularly preferred.

[0045] Examples of the alicyclic polycarboxylic acids constituting the structural moiety derived from the alicyclic polycarboxylic acids include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and acid anhydrides thereof.

[0046] The polyester (A) may contain a structural moiety derived from an aromatic dicarboxylic acid having a sulfonic acid group, such as a structural moiety derived from sulfoterephthalic acid, a structural moiety derived from 5-sulfoisophthalic acids, a structural moiety derived from 4-sulfophthalic acids, a structural moiety derived from 4-sulfonaphthalene-2,7-dicarboxylic acids, or a structural moiety derived from 5(4-sulfophenoxy)isophthalic acids, and a structural moiety derived from an aromatic dicarboxylic acid salt having a sulfonate group, such as a metal salt or ammonium salt thereof. In terms of the hygroscopicity of the polyester (A) and the solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives, the content of the structural moiety derived from the aromatic dicarboxylic acid relative to the total structural moieties derived from the polyvalent carboxylic acids (a1) is preferably 8 mol% or less, more preferably 5 mol% or less, particularly preferably 3 mol% or less, even more preferably 1 mol% or less, and most preferably 0 mol%.

[0047] In the adhesive of this embodiment, the structural moiety derived from the aromatic ring-containing monomer is preferably 30% by mass or less relative to the entire polyester (A). When the structural moiety derived from the aromatic ring-containing monomer is 30% by mass or less relative to the entire polyester (A), the polyester (A) tends to have excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives. The structural moiety derived from the aromatic ring-containing monomer is, in order of more preferred, 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, and 2% by mass or less relative to the entire polyester (A). Examples of the aromatic ring-containing monomer contained in the polyvalent carboxylic acid (a1) include the aromatic polyvalent carboxylic acids described above.

[0048] In the polyester (A), at least one of the structural moieties derived from the polycarboxylic acids (a1) and the structural moieties derived from the polyhydric alcohols (a2) preferably has a structural moiety derived from a monomer having a molecular weight of 320 or more. This makes it possible to reduce the ester bond concentration while maintaining the crystallinity of the polyester, making it easier to achieve both handleability and solubility in liquid polyols such as polypropylene glycol, which are commonly used in reactive hot melt adhesives. From the above perspective, at least one of the structural moieties derived from the polycarboxylic acids (a1) and the structural moieties derived from the polyhydric alcohols (a2) preferably has 0.1 mol% or more, more preferably 0.5 mol% or more, even more preferably 1 mol% or more, and particularly preferably 3 mol% or more, of structural moieties derived from a monomer having a molecular weight of 320 or more.

[0049] As a monomer having a molecular weight of 320 or more, those included in the polycarboxylic acids (a1) include aromatic polycarboxylic acids such as ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride, and aliphatic polycarboxylic acids such as dimer acids. Among these, from the viewpoint of solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives, aliphatic polycarboxylic acids are preferred, dimer acids are more preferred, and hydrogenated dimer acids are particularly preferred.

[0050] The monomer constituting the structural moiety derived from the polycarboxylic acid (a1) preferably includes a plant-derived monomer, such as succinic acid, glutaric acid, azelaic acid, sebacic acid, or a dimer acid.

[0051] [Polyhydric alcohols (a2)] Examples of the polyhydric alcohols (a2) include aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, aromatic polyhydric alcohols, and polyalkylene glycols. One or more types of polyhydric alcohols can be used.

[0052] Examples of the aliphatic polyhydric alcohol constituting the structural moiety derived from the aliphatic polyhydric alcohol include linear aliphatic alcohols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol, and branched aliphatic diols such as 1,2-propylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, and dimer diols. Among these, linear aliphatic polyhydric alcohols are preferred in order to impart crystallinity to the polyester and improve handling properties and adhesive strength when made into an adhesive, and among these, those having an even number of carbon atoms are more preferred. In addition, in order to achieve excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives, it is preferable that the polyester (A) in the adhesive of this embodiment contains an aliphatic polyhydric alcohol having 4 or more carbon atoms.

[0053] Examples of the dimer diols include dimer diols which are reduced products of dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc., and hydrogenated products thereof. Among these, hydrogenated products are preferred from the viewpoint of suppressing gelation during polyester production.

[0054] The content of the aliphatic polyhydric alcohol is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and particularly preferably 80 mol% or more, based on the total structural moieties derived from the polyhydric alcohols (a2).

[0055] Furthermore, for the purpose of further imparting a branched skeleton or a hydroxyl value to the polyester, the polyester may contain an aliphatic polyhydric alcohol having a valence of three or more, such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol.

[0056] Examples of the alicyclic polyhydric alcohol constituting the structural moiety derived from the alicyclic polyhydric alcohol include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.

[0057] Examples of the aromatic polyhydric alcohol constituting the structural moiety derived from the aromatic polyhydric alcohol include paraxylene glycol, metaxylene glycol, orthoxylene glycol, 1,4-phenylene glycol, ethylene oxide adducts of 1,4-phenylene glycol, and bisphenol skeleton-containing alcohols.

[0058] Examples of the bisphenol skeleton-containing alcohols include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4′-dihydroxybenzophenone, bisphenolfluorene, and hydrogenated products thereof, as well as glycols such as ethylene oxide adducts and propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl group of a bisphenol.

[0059] Examples of the polyalkylene glycol constituting the polyalkylene glycol-derived structural moiety include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Among these, polypropylene glycol and polytetramethylene glycol are preferred from the viewpoint of solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives, and polytetramethylene glycol is most preferred from the viewpoint of reactivity.

[0060] The average molecular weight of the polyalkylene glycol is preferably 320 or more, more preferably 400 or more, and particularly preferably 500 or more, from the viewpoints that the ester bond concentration can be reduced while maintaining the crystallinity of the polyester and that it is easy to achieve both handleability and the above-mentioned solubility. The average molecular weight of the polyalkylene glycol is an average molecular weight calculated from the hydroxyl value.

[0061] The content of the polyalkylene glycol is preferably 5% by mass to 80% by mass relative to the total polyester (A). From the viewpoint of the solubility described above, the content of the polyalkylene glycol is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 20% by mass or more, relative to the total polyester (A). Furthermore, from the viewpoint of adhesive strength when used as an adhesive, the content of the polyalkylene glycol is preferably 80% by mass or less, more preferably 70% by mass or less, and particularly preferably 60% by mass or less, relative to the total polyester (A).

[0062] When the polyester (A) contains a structural moiety derived from an alicyclic polyhydric alcohol and / or a structural moiety derived from an aromatic polyhydric alcohol, the total content of the structural moieties derived from the alicyclic polyhydric alcohol and the structural moieties derived from the aromatic polyhydric alcohol in the structural moieties derived from the polyhydric alcohols (a2) is preferably 50 mol% or less, more preferably 40 mol% or less, and particularly preferably 30 mol% or less. If these contents are too high, the polyester becomes amorphous and has poor handleability, and the solubility of the polyester (A) in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives, tends to be poor.

[0063] In the adhesive of this embodiment, the structural moiety derived from the aromatic ring-containing monomer is preferably 30% by mass or less relative to the entire polyester (A). The structural moiety derived from the aromatic ring-containing monomer is, in the following order of preference, 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, and 2% by mass or less relative to the entire polyester (A). When the structural moiety derived from the aromatic ring-containing monomer is 30% by mass or less relative to the entire polyester (A), the adhesive tends to have excellent solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives. Examples of the aromatic ring-containing monomer contained in the polyhydric alcohol (a2) include the aromatic polyhydric alcohols described above.

[0064] In the polyester (A), at least one of the structural moieties derived from the polycarboxylic acids (a1) and the structural moieties derived from the polyhydric alcohols (a2) preferably has a structural moiety derived from a monomer having a molecular weight of at least 320. At least one of the structural moieties derived from the polycarboxylic acids (a1) and the structural moieties derived from the polyhydric alcohols (a2) preferably has 0.1 mol % or more, more preferably 0.5 mol % or more, even more preferably 1 mol % or more, and particularly preferably 3 mol % or more of the structural moieties derived from a monomer having a molecular weight of at least 320.

[0065] Examples of the monomer having a molecular weight of 320 or more that is included in the polyhydric alcohols (a2) include aliphatic polyhydric alcohols such as dimer diols, bisphenol skeleton-containing alcohols (excluding those with a molecular weight of less than 320), and polyalkylene glycols (excluding those with a molecular weight of less than 320). Among these, from the viewpoint of the solubility of the polyester (A) in liquid polyols such as polypropylene glycol that are generally used in reactive hot melt adhesives, aliphatic polyhydric alcohols and polyalkylene glycols are preferred, dimer diols are more preferred, and hydrogenated dimer diols are particularly preferred.

[0066] The monomer constituting the structural moiety derived from the polyhydric alcohols (a2) preferably includes a plant-derived monomer, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,10-decanediol, dimer diols, or glycerin.

[0067] [Components of Polyester (A)] In the adhesive of this embodiment, the structural moiety derived from a monomer having an aromatic ring is preferably 30% by mass or less, and more preferably 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, and 2% by mass or less, in order of more preferred. As the monomer having an aromatic ring, examples of monomers other than polyvalent carboxylic acids (a1) and polyhydric alcohols (a2) include hydroxycarboxylic acids having an aromatic ring.

[0068] The polyester (A) used in the adhesive of this embodiment may have at least one structural moiety selected from the group consisting of a structural moiety derived from a trivalent or higher polycarboxylic acid and a structural moiety derived from a trivalent or higher polyhydric alcohol for the purpose of introducing a branched skeleton. That is, the polyester (A) may contain at least one selected from the group consisting of the trivalent or higher polycarboxylic acid and the trivalent or higher polyhydric alcohol as a copolymerization component. In particular, in reactive hot melt adhesives, when a crosslinked structure is formed by moisture curing after reaction with an isocyanate (described below), the introduction of a branched skeleton increases the number of reactive sites in the resin, resulting in a high crosslink density and a high-strength adhesive layer. Among these, trimethylolpropane is preferred for its versatility. When a trivalent or higher polycarboxylic acid or a trivalent or higher polyhydric alcohol is used in the depolymerization reaction (described below), a trivalent or higher polycarboxylic acid or a polyhydric alcohol may be used separately from the polycarboxylic acid or polyhydric alcohol used in the depolymerization reaction.

[0069] When at least one selected from the group consisting of trivalent or higher polycarboxylic acids and trivalent or higher polyhydric alcohols is used for the purpose of introducing a branched skeleton into polyester (A), the content of the trivalent or higher polycarboxylic acids relative to the total polycarboxylic acids (a1) or the content of the trivalent or higher polyhydric alcohols relative to the total polyhydric alcohols (a2) (excluding the trivalent or higher polycarboxylic acids and trivalent or higher polyhydric alcohols used in the depolymerization reaction) is preferably 0.1 to 5 mol %, more preferably 0.3 to 3 mol %, and even more preferably 0.5 to 2 mol %. If the content of either or both is too high, the mechanical properties such as elongation at break of the coating film formed by application of the adhesive tend to decrease, resulting in a decrease in adhesive strength, and gelation also tends to occur during polymerization and preparation of the reactive hot melt adhesive.

[0070] Furthermore, the polyester (A) used in the adhesive of this embodiment may contain a structural moiety derived from a hydroxycarboxylic acid compound. The hydroxycarboxylic acid compound is a compound having a hydroxyl group and a carboxyl group in its molecular structure. Examples of hydroxycarboxylic acid compounds that constitute the structural moiety derived from the hydroxycarboxylic acid compound include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis(p-hydroxyphenyl)valeric acid. These may be used alone or in combination of two or more.

[0071] The adhesive of this embodiment preferably contains substantially no organic solvent. Specifically, the content of organic solvent in the adhesive is preferably 5% by mass or less, and particularly preferably 2% by mass or less.

[0072] [Glass transition temperature (Tg) of polyester (A)] The glass transition temperature (Tg) of the polyester (A) used in the adhesive of this embodiment is preferably 0° C. or lower, preferably −10° C. or lower, more preferably −20° C. or lower, particularly preferably −30° C. or lower, even more preferably −40° C. or lower, and particularly preferably −50° C. or lower. If the glass transition temperature (Tg) is too high, the solubility of the polyester (A) in liquid polyols such as polypropylene glycol that are generally used in reactive hot melt adhesives tends to be poor.

[0073] The glass transition temperature (Tg) can be determined by measurement using a differential scanning calorimeter under the following measurement conditions: a temperature range of −90 to 200° C., and a temperature rise rate of 10° C. / min.

[0074] [Acid value of polyester (A)] The acid value of the polyester (A) used in the present invention is preferably 3 mgKOH / g or less, more preferably 2 mgKOH / g or less, and particularly preferably 1 mgKOH / g or less. If the acid value is too high, hydrolysis of the polyester is promoted, and long-term durability under a humid and hot environment tends to decrease.

[0075] The acid value (mg KOH / g) can be determined by dissolving 1 g of polyester (A) in 30 g of a mixed solvent of toluene / methanol (for example, toluene / methanol=9 / 1 by volume) and subjecting the solution to neutralization titration in accordance with JIS K 0070. In the present invention, the acid value of polyester (A) is determined by the content of carboxy groups in the polyester.

[0076] [Hydroxyl value of polyester (A)] The hydroxyl value of the polyester (A) is preferably less than 20 mgKOH / g, and in descending order of preference, is less than 18 mgKOH / g, less than 16 mgKOH / g, less than 14 mgKOH / g, less than 12 mgKOH / g, less than 10 mgKOH / g, less than 8 mgKOH / g, and less than 6 mgKOH / g. If the hydroxyl value is too high, it tends to be difficult to achieve high levels of both initial strength and final strength when the adhesive of this embodiment is used as a reactive hot melt adhesive.

[0077] The hydroxyl value of the polyester (A) is determined by neutralization titration in accordance with JIS K 0070.

[0078] [Ester bond concentration of polyester (A)] The ester bond concentration of the polyester (A) is 10.00 mmol / g or less, preferably 4.00 to 9.00 mmol / g, more preferably 5.00 to 8.50 mmol / g, and even more preferably 6.00 to 8.00 mmol / g. If the ester bond concentration is too low, the polarity and elastic modulus of the polyester (A) decrease, and the adhesiveness tends to be poor. If the ester bond concentration is too high, the solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives, tends to be poor.

[0079] The ester bond concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of polyester (A), and can be calculated, for example, from the amounts charged. The calculation method is to divide the number of moles of the polycarboxylic acids (a1) and the polyhydric alcohols (a2), whichever is charged less, by the total mass of the final product, and an example of the calculation formula is shown below. When the amounts of the polycarboxylic acids (a1) and the polyhydric alcohols (a2) charged are equal in molar amount, either of the following calculation formulas may be used. When a monomer having both a carboxylic acid and a hydroxyl group is used, or when a polyester is prepared from caprolactone or the like, the calculation method will be changed appropriately.

[0080] <When the amount of polycarboxylic acids (a1) is small> Ester bond concentration (mmol / g) = [(A1 / α1 × m1 + A2 / α2 × m2 + A3 / α3 × m3 ...) / Z] × 1000 A: amount of polycarboxylic acids (a1) charged (g) α: molecular weight of polycarboxylic acids (a1) m: number of carboxy groups per molecule of polycarboxylic acids (a1) Z: final mass (g)

[0081] <When the amount of polyhydric alcohols (a2) is small> Ester bond concentration (mmol / g) = [(B1 / β1×n1 + B2 / β2×n2 + B3 / β3×n3 ...) / Z] × 1000 B: amount of polyhydric alcohols (a2) charged (g) β: molecular weight of polyhydric alcohols (a2) n: number of hydroxyl groups per molecule of polyhydric alcohols (a2) Z: final mass (g)

[0082] The ester bond concentration can also be measured by a known method using NMR, etc. For example, the ester group concentration, composition, and composition ratio of the polyester (A) can be determined by H-NMR measurement (proton-type nuclear magnetic resonance spectroscopy) or C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy) at a resonance frequency of 400 MHz.

[0083] In addition, the concentration of other polar groups other than the ester bond and reactive functional group contained in the polyester (A) is preferably low from the viewpoints of low moisture absorption and long-term durability in a humid and hot environment, and / or solubility in a liquid polyol such as polypropylene glycol generally used in reactive hot melt adhesives described below. Examples of other polar groups include amide groups, imide groups, urethane groups, urea groups, ether groups, and carbonate groups.

[0084] In terms of solubility in liquid polyols such as polypropylene glycol that are generally used in reactive hot melt adhesives, the total concentration of amide groups, imide groups, urethane groups, and urea groups in the polyester (A) is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1 mmol / g or less, even more preferably 0.5 mmol / g or less, and most preferably 0.2 mmol / g or less.

[0085] Examples of the ether group include alkyl ether groups and phenyl ether groups, and it is particularly preferable to reduce the concentration of alkyl ether groups from the viewpoint of low moisture absorption and long-term durability in a humid and hot environment, or to reduce the concentration of phenyl ether groups from the viewpoint of solubility in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives.

[0086] From the viewpoint of solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives, the alkyl ether group concentration of polyester (A) is preferably 4 mmol / g or less, with the following preferred concentrations being 3 mmol / g or less, 2 mmol / g or less, 1.5 mmol / g or less, 1 mmol / g or less, and 0.5 mmol / g or less. Also, from the viewpoint of solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives, the phenyl ether group concentration of polyester (A) is preferably 5 mmol / g or less, with the following preferred concentrations being 4 mmol / g or less, 3 mmol / g or less, 2.5 mmol / g or less, 2 mmol / g or less, 1.5 mmol / g or less, 1 mmol / g or less, and 0.5 mmol / g or less.

[0087] The carbonate group concentration of the polyester (A) is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1 mmol / g or less, even more preferably 0.5 mmol / g or less, and most preferably 0.2 mmol / g or less.

[0088] [Solubility parameter (SP value) of polyester (A)] The solubility parameter (SP value) of the polyester (A) used in the adhesive of one embodiment of the present invention is preferably 10.50 (cal / cm ３ ) １／２ The preferred range is 8.50 to 10.40 (cal / cm ３ ) １／２ , 8.60 to 10.30 (cal / cm ３ ) １／２ , 8.70 to 10.25 (cal / cm ３ ) １／２ , 8.80-10.15 (cal / cm ３ ) １／２ , 9.00-10.05 (cal / cm ３ ) １／２If the solubility parameter (SP value) is too high or too low, the solubility of the polyester (A) in liquid polyols such as polypropylene glycol, which are generally used in reactive hot melt adhesives, tends to be poor.

[0089] The solubility parameter (SP value) can be determined by the known Fedors method. This method is described in R. F. Fedors, Polym. Eng. Sci., 14(2), 147 (1974), and is determined by the following formula from the vaporization energy and molar volume data of atoms and atomic groups in the structural formula of the desired compound: Solubility parameter = (ΣΔei / ΣΔvi) １／２ (In the formula, Δei and Δvi represent the evaporation energy and molar volume of an atom or atomic group, respectively.) The solubility parameter (SP value) can be calculated from each atomic group described in the above literature. However, if the structure contains atoms or atomic groups not described in the above literature, these structural parts should be ignored in the calculation.

[0090] [Mass average molecular weight (Mw) of polyester (A)] The mass average molecular weight (Mw) of the polyester (A) used in the adhesive of this embodiment is 25,000 or more, preferably 30,000 or more, more preferably 35,000 or more, even more preferably 40,000 or more, especially preferably 45,000 or more, particularly preferably 50,000 or more, and preferably 300,000 or less, more preferably 200,000 or less, even more preferably 150,000 or less, especially preferably 120,000 or less, particularly preferably 100,000 or less. The mass average molecular weight (Mw) of the polyester (A) is preferably 25,000 or more and 300,000 or less. If the mass average molecular weight (Mw) is too low, it tends to be difficult to achieve both high levels of initial strength and final strength when used as a reactive hot melt adhesive. On the other hand, if the mass average molecular weight (Mw) is too high, the solution viscosity tends to be too high, making it difficult to use as a hot melt adhesive.

[0091] The peak top molecular weight (Mp) of the polyester (A) used in the adhesive of this embodiment is preferably 30,000 or more, more preferably 35,000 or more, even more preferably 40,000 or more, especially preferably 45,000 or more, particularly preferably 50,000 or more, and preferably 300,000 or less, more preferably 200,000 or less, even more preferably 150,000 or less, especially preferably 120,000 or less, particularly preferably 100,000 or less. The peak top molecular weight (Mp) of the polyester (A) is preferably 35,000 or more and 300,000 or less. If the peak top molecular weight (Mp) is too low, it tends to be difficult to achieve both high levels of initial strength and final strength when used as a reactive hot melt adhesive. Furthermore, if the peak top molecular weight (Mp) is too high, the solution viscosity tends to be too high, making it difficult to use as a hot melt adhesive.

[0092] The mass average molecular weight (Mw) and peak top molecular weight (Mp) are measured by the following method: The mass average molecular weight (Mw) and peak top molecular weight (Mp) can be measured using a high performance liquid chromatograph (manufactured by Waters, "ACQUITY APC System") with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45, and can be calculated in terms of standard polystyrene molecular weight.

[0093] [Crystallization of Polyester (A)] In the adhesive of this embodiment, the polyester (A) has crystallinity. Crystallinity here can be confirmed by a differential scanning calorimeter, and refers to the observation of an endothermic peak due to crystalline melting when measured, for example, at a temperature range of −90 to 200° C. and a temperature rise rate of 10° C. / min. The measurement temperature range can be changed as appropriate depending on the sample.

[0094] The heat of crystalline fusion of the polyester (A) is preferably 3 J / g or more. This is to provide good handleability to the polyester resin. Furthermore, from the viewpoint of the initial strength and final strength when used as a reactive hot melt adhesive, the heat of crystalline fusion is more preferably 15 J / g or more, even more preferably 30 J / g or more, particularly preferably 40 J / g or more, particularly preferably 50 J / g or more, and most preferably 60 to 100 J / g.

[0095] The heat of crystalline fusion can be confirmed by a differential scanning calorimeter, and can be calculated from the area of ​​the endothermic peak due to crystalline melting observed when measuring, for example, in a measurement temperature range of −90 to 200° C. at a temperature rise rate of 10° C. / min.

[0096] [Melting Point of Polyester (A)] The melting point of the polyester (A) used in the adhesive of this embodiment is 30° C. or higher, preferably 35° C. or higher, more preferably 40 to 120° C., even more preferably 45 to 100° C., particularly preferably 50 to 90° C., and especially preferably 55 to 80° C. If the melting point is too low, the handling properties of the polyester and the initial strength when used as a reactive hot melt adhesive tend to be poor, while if the melting point is too high, the solubility in liquid polyols such as polypropylene glycol generally used in reactive hot melt adhesives tends to be poor, or the adhesion to the adherend tends to deteriorate, resulting in insufficient final strength when used as a reactive hot melt adhesive.

[0097] The melting point can be measured using a differential scanning calorimeter as follows: the measurement temperature range is −90 to 200° C., and the temperature rise rate is 10° C. / min.

[0098] <Production of Polyester (A)> The polyester (A) of the present invention can be produced by polycondensation reaction of the above-mentioned polycarboxylic acids (a1) and the above-mentioned polyhydric alcohols (a2) in the presence of a catalyst using a known method. That is, since the polyester (A) is obtained by polycondensation reaction of the polycarboxylic acids (a1) and the polyhydric alcohols (a2), it has a structural portion derived from the polycarboxylic acids (a1) and a structural portion derived from the polyhydric alcohols (a2). In the polycondensation reaction, an esterification reaction or a transesterification reaction is first carried out, and then the polycondensation reaction is carried out. Note that when a high molecular weight is not required, it may be produced by only an esterification reaction or a transesterification reaction.

[0099] The blending ratio of the polyvalent carboxylic acids (a1) to the polyhydric alcohols (a2) is preferably 1 to 3 equivalents, particularly preferably 1.1 to 2.2 equivalents, and even more preferably 1.2 to 1.7 equivalents of the polyhydric alcohols (a2) per equivalent of the polyvalent carboxylic acids (a1). If the blending ratio of the polyhydric alcohols (a2) is too low, the acid value tends to increase, making it difficult to obtain a high molecular weight, while if it is too high, the yield tends to decrease.

[0100] [Esterification reaction or transesterification reaction] In the esterification reaction or transesterification reaction, a catalyst is usually used, and specific examples include catalysts such as titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the standpoint of the balance between high catalytic activity and the hue of the resulting reaction product.

[0101] The amount of the catalyst to be added is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and further preferably 20 to 3,000 ppm, based on the total amount of copolymerization components (mass basis). If the amount is too small, the polymerization reaction tends to proceed poorly, whereas if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0102] The reaction temperature during the esterification reaction or transesterification reaction is preferably 200 to 300°C, particularly preferably 210 to 280°C, and even more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, while if it is too high, side reactions such as decomposition tend to occur easily. Furthermore, although the pressure during the reaction is usually normal pressure, it is also preferable to carry out the reaction under pressure to increase the reaction temperature and efficiently proceed with the reaction.

[0103] As reaction conditions for the polycondensation reaction carried out after the above-mentioned esterification reaction or transesterification reaction, the same amount of catalyst as that used in the above-mentioned esterification reaction or transesterification reaction is further blended, the reaction temperature is preferably 220 to 280 ° C., particularly preferably 230 to 270 ° C., and the reaction system is gradually reduced in pressure until the reaction is finally carried out at 5 hPa or less. If the reaction temperature is too low, the reaction tends to proceed poorly, and if it is too high, side reactions such as decomposition tend to occur easily.

[0104] In addition, when obtaining a polyester having a carboxy group in a side chain, a method of reacting a hydroxyl group-containing prepolymer obtained by copolymerizing a polycarboxylic acid (a1) other than a polycarboxylic acid anhydride with a polyhydric alcohol (a2) is preferred from the viewpoint of productivity.

[0105] The temperature for the esterification reaction between the polycarboxylic acids (a1) and the polyhydric alcohols (a2) is usually 180 to 280° C., and the reaction time is usually 60 minutes to 8 hours.

[0106] The temperature in the polycondensation is usually 200 to 280° C., and the reaction time is usually 20 minutes to 4 hours. The polycondensation is preferably carried out under reduced pressure.

[0107] The polyester (A) can also be produced by a well-known method other than the above, for example, by subjecting a polycarboxylic acid (a1) and a polyhydric alcohol (a2) to an esterification reaction, optionally in the presence of a catalyst, to obtain a prepolymer, followed by polycondensation and further depolymerization.

[0108] For the depolymerization, it is preferable to use a trivalent or higher polycarboxylic acid from the viewpoint of adhesive strength. As the trivalent or higher polycarboxylic acid, those described above in relation to the polycarboxylic acid (a1) can be used. Among them, trivalent or higher polycarboxylic acids having one acid anhydride group are preferred from the viewpoint of suppressing a decrease in molecular weight, and trimellitic anhydride and hydrogenated trimellitic anhydride are more preferred. The temperature for the depolymerization is usually 200 to 260°C, and the reaction time is usually 10 minutes to 5 hours.

[0109] In the depolymerization, when the total amount of the polycarboxylic acids (a1) is taken as 100 mol %, if the polycarboxylic acids having a valence of 3 or more are used in an amount exceeding 20 mol %, the molecular weight of the polyester (A) may be significantly reduced. Therefore, when the total amount of the polycarboxylic acids (a1) is taken as 100 mol %, the depolymerization is preferably carried out using 20 mol % or less of the polycarboxylic acids having a valence of 3 or more, more preferably 1 to 15 mol %, particularly preferably 2 to 10 mol %, and even more preferably 3 to 8 mol %.

[0110] Thus, the polyester (A) used in the adhesive of this embodiment can be obtained. The polyester (A) used in the adhesive of this embodiment is a resin that is solid at room temperature and has excellent handleability, for example, in pellet form, and is soluble in liquid polyols such as polypropylene glycol, which are commonly used in reactive hot melt adhesives. Therefore, it can be used in applications such as hot melt adhesives and reactive hot melt adhesives. Furthermore, because the VOC content is low and a high biomass design is possible, the adhesive of this embodiment using this polyester has low odor characteristics and is environmentally friendly. Furthermore, when made into a hot melt adhesive or reactive hot melt adhesive, it can achieve both initial and final adhesive strengths, making it extremely useful as a raw material for hot melt adhesives or reactive hot melt adhesives.

[0111] The adhesive of this embodiment can also be used as a hot melt adhesive, particularly as a reactive hot melt adhesive.

[0112] 2. Hot melt adhesive, reactive hot melt adhesive (hot melt adhesive) The adhesives described above can be included in the hot melt adhesive of this embodiment. A hot melt adhesive is solid or semi-solid at room temperature, melts when heated, and becomes fluid. It can be used as an adhesive placed between components to be joined to bond the components together. In other words, the hot melt adhesive can be used as a hot melt adhesive. It is preferable that the hot melt adhesive is substantially free of organic solvents, and it is preferable that the organic solvent content of the entire hot melt adhesive is 5 wt % or less.

[0113] The hot melt adhesive includes an adhesive containing at least a polyester (A). The hot melt adhesive may also contain at least one selected from the group consisting of a polyalkylene glycol (B), a polyester polyol (C) different from the polyester (A) (hereinafter also simply referred to as "polyester polyol (C)"), and an isocyanate.

[0114] (Method for Producing Hot Melt Adhesive) The hot melt adhesive can be produced, for example, by adding a resin other than the polyester (A), a polyol component, and additives to the polyester (A) as needed, and adjusting the mixture to have a desired melt viscosity.

[0115] (Reactive Hot Melt Adhesive) The above-mentioned adhesives and hot melt adhesives can also be used as reactive hot melt adhesives. The reactive hot melt adhesive includes an adhesive containing the above-mentioned polyester (A). The reactive hot melt adhesive preferably contains substantially no organic solvent, and the organic solvent content of the entire reactive hot melt adhesive is preferably 5% by mass or less, particularly 2% by mass or less. By adjusting the polyester (A), such a reactive hot melt adhesive can be made into a high-biomass reactive hot melt adhesive that not only achieves high levels of initial strength and final strength, but also has low odor and VOC emissions and is environmentally friendly.

[0116] The reactive hot melt adhesive contains a reactive group, such as an isocyanate group. The reactive hot melt adhesive preferably contains a urethane prepolymer (X) having an isocyanate group, and the urethane prepolymer (X) preferably contains a structural moiety derived from a polyalkylene glycol (B). The urethane prepolymer (X) preferably contains a structural moiety derived from a polyester polyol (C) different from the polyester (A). The urethane prepolymer (X) may also contain a component derived from the polyester (A). In other words, the reactive hot melt adhesive contains an adhesive containing the above-mentioned polyester (A), and the urethane prepolymer (X) may or may not contain the adhesive.

[0117] (Method for producing reactive hot melt adhesive) A reactive hot melt adhesive containing a urethane prepolymer (X) having an isocyanate group, which is an example of a reactive hot melt adhesive, can be produced, for example, by dissolving a polyester (A) in a polyalkylene glycol (B) or other liquid polyol, then adding an isocyanate and mixing under heat to obtain a urethane prepolymer. The polyester polyol (C) may be added to the polyalkylene glycol or other liquid polyol together with the polyester (A), and then dissolved by heating and mixing. Alternatively, the polyester (A) may be dissolved in the polyalkylene glycol (B) or other liquid polyol, and then the polyester polyol (C) and the isocyanate may be added simultaneously, and then mixed under heat.

[0118] The reactive hot melt adhesive may contain other additives to the extent that they do not adversely affect the reaction between the polyester (A), polyalkylene glycol (B), polyester polyol (C) and isocyanate that form the urethane prepolymer (X). The timing of addition is not particularly limited; for example, the additives may be added together with the polyester (A), polyalkylene glycol (B), polyester polyol (C), and isocyanate when synthesizing the urethane prepolymer (X). Alternatively, the polyester (A), polyalkylene glycol (B), polyester polyol (C) may be reacted with the isocyanate to synthesize the urethane prepolymer (X), and then the additives may be added. The additives may be the same as those described below as other additives for hot melt adhesives. The heating temperature is preferably within the range of 80 to 160°C, more preferably 100 to 140°C. Within this heating temperature range, the components dissolve well, the viscosity is reduced, and handling is improved. Furthermore, the reaction between the isocyanate and the polyester (A), the polyalkylene glycol (B), and the polyester polyol (C) proceeds sufficiently.

[0119] (Polyalkylene glycol (B)) Specific examples of the polyalkylene glycol (B) component include polymethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyalkylene glycols having two or more types of glycol units such as a copolymer of ethylene oxide and propylene oxide, and branched polyalkylene glycols using polyfunctional alcohols such as glycerin. Among these, polypropylene glycol is preferred as the polyalkylene glycol (B) component because it is liquid at room temperature and has excellent solubility for the polyester (A). Furthermore, these may be used alone or in combination of two or more.

[0120] The average molecular weight of the polyalkylene glycol (B) is preferably 200 to 5000, more preferably 700 to 3000. When the average molecular weight is 200 or more, the adhesive strength of the hot melt adhesive after curing is good, and when it is 5000 or less, the viscosity of the hot melt adhesive or reactive hot melt adhesive is low and the coatability is good. The average molecular weight of the polyalkylene glycol is the average molecular weight calculated from the hydroxyl value.

[0121] (Polyester Polyol (C)) Crystalline polyester polyols and amorphous polyester polyols are known as polyester polyols (C), and crystalline polyester polyols are preferred from the viewpoint of early strength. Specific examples thereof include aliphatic polyester polyols and aromatic polyester polyols. Crystalline polyester polyols and amorphous polyester polyols can also be easily distinguished by differential scanning calorimetry (DSC). The melting point of crystalline polyester polyols is observed as an endothermic peak during temperature rise and as an exothermic peak during temperature fall in DSC measurement. The melting point of amorphous polyester polyols is not clearly observed when measured by DSC, and therefore it is possible to distinguish them from crystalline polyester polyols.

[0122] Aliphatic polyester polyols can be obtained by reacting aliphatic dicarboxylic acids with diols. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and decamethylenedicarboxylic acid. These may be used alone or in combination of two or more. Examples of diols include low-molecular-weight diols having 2 to 12 carbon atoms, such as ethylene glycol, 1-ethylethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, cyclohexanedimethanol, and 2,4-diethyl-1,5-pentanediol. The diol is preferably at least one selected from ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol. These diols may be used alone or in combination. Examples of the aliphatic polyester polyol include polyhexamethylene adipate, polyhexamethylene sebacate, polyhexamethylene dodecanate, and polybutylene adipate.

[0123] The aromatic polyester polyol is preferably one obtained by reacting an aromatic poly(or di)carboxylic acid with the above-mentioned diol. Examples of aromatic poly(or di)carboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. These may be used alone or in combination of two or more. Examples of aromatic polyester polyols include polyalkylene phthalate, polyalkylene isophthalate, and polyalkylene terephthalate.

[0124] As the polyol component, polyether polyol has low viscosity and good handleability, and is suitable for dissolving the polyester. In addition, polyester polyol has high heat resistance, solvent resistance, and strength, so it is preferable to use a polyalkylene glycol and a polyester polyol in combination.

[0125] The average molecular weight of the polyester polyol (C) is preferably 500 to 5500, more preferably 1500 to 4500. When the average molecular weight of the polyester polyol (C) is 500 or more, the adhesive strength of the hot melt adhesive after curing is good, and when it is 5500 or less, the viscosity of the hot melt adhesive or reactive hot melt adhesive is low and the coatability is good. The average molecular weight of the polyester polyol is an average molecular weight calculated from the hydroxyl value.

[0126] (Isocyanate) Examples of isocyanates include ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, xylylene diisocyanate, 1,4-naphthyl diisocyanate, 1,5-naphthylene diisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, dichlorohexamethylene diisocyanate, furfuridene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4"-triisocyanate-triphenylmethane, 1,3,5-triisocyanate-benzene, 2,4,6-triisocyanate-toluene, and 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate.

[0127] As the isocyanate, one containing an average of 1 to 3 isocyanate groups per molecule is preferred, and bifunctional isocyanates, or so-called diisocyanates, are particularly preferred. One type of isocyanate may be used alone, or two or more types may be used in combination. Among these, 4,4'-diphenylmethane diisocyanate is preferred due to its high adhesive strength after moisture curing. While monools, monoisocyanates, trifunctional polyols, and trifunctional isocyanates can also be used, bifunctional polyols (diols) and bifunctional isocyanates (diisocyanates) are preferred from the viewpoint of the viscosity of the hot melt adhesive or reactive hot melt adhesive. Using two moles of bifunctional isocyanate per mole of bifunctional polyol is preferred because it allows for the relatively easy production of the desired urethane prepolymer.

[0128] (Content of each component in the hot melt adhesive) From the viewpoint of the viscosity and adhesive strength of the hot melt adhesive, the content of the polyester (A) in the hot melt adhesive is preferably 2 to 50 mass%, more preferably 5 to 40 mass%, and even more preferably 7 to 30 mass% of the entire hot melt adhesive. From the viewpoint of the viscosity and adhesive strength of the hot melt adhesive, the content of the polyalkylene glycol (B) is preferably 10 to 75 mass%, more preferably 20 to 60 mass%, and even more preferably 30 to 50 mass% of the entire hot melt adhesive. From the viewpoint of the viscosity and adhesive strength of the hot melt adhesive, the content of the polyester polyol (C) is preferably 0 to 50 mass%, more preferably 10 to 40 mass%, and even more preferably 15 to 35 mass% of the entire hot melt adhesive. From the viewpoint of the viscosity and adhesive strength of the hot melt adhesive, the content of the isocyanate is preferably 0.1 to 5 mass%, more preferably 0.5 to 4 mass%, and even more preferably 1 to 3 mass% of the entire hot melt adhesive. Other additives include plasticizers, antioxidants, pigments, light stabilizers, flame retardants, catalysts, waxes, wetting agents, thickeners, defoamers, rheology modifiers, and the like.

[0129] (Amount of each component in the reactive hot melt adhesive) From the viewpoint of the viscosity, initial strength, and final strength of the reactive hot melt adhesive, the amount of polyester (A) used in the production of the reactive hot melt adhesive is preferably 2 to 50 mass%, more preferably 5 to 40 mass%, and even more preferably 7 to 30 mass%, based on the reactive hot melt adhesive produced. From the viewpoint of the viscosity, initial strength, and final strength of the reactive hot melt adhesive, the amount of polyalkylene glycol (B) used in the production of the reactive hot melt adhesive is preferably 10 to 75 mass%, more preferably 20 to 60 mass%, and even more preferably 30 to 50 mass%, based on the reactive hot melt adhesive produced. From the viewpoint of the viscosity, initial strength, and final strength of the reactive hot melt adhesive, the amount of polyester polyol (C) used in the production of the reactive hot melt adhesive is preferably 0 to 50 mass%, more preferably 10 to 40 mass%, and even more preferably 15 to 35 mass%, based on the reactive hot melt adhesive produced. From the viewpoint of the viscosity, initial strength, and final strength of the reactive hot melt adhesive, the amount of isocyanate used in producing the reactive hot melt adhesive is preferably 3 to 30 mass%, more preferably 5 to 25 mass%, and even more preferably 8 to 20 mass%, based on the reactive hot melt adhesive to be produced.

[0130] (Other Additives) Other additives that may be contained in the hot melt adhesive and the reactive hot melt adhesive include, for example, plasticizers such as dioctyl phthalate, dibutyl phthalate, and dioctyl adipate; antioxidants such as phenol-based antioxidants, phosphite-based antioxidants, thioether-based antioxidants, and amine-based antioxidants; pigments such as titanium oxide and carbon black; light stabilizers such as benzotriazole, hindered amines, benzoates, and benzotriazole; flame retardants such as halogen-based flame retardants, phosphorus-based flame retardants, antimony-based flame retardants, and metal hydroxide-based flame retardants; metal-based catalysts, for example, tin-based catalysts (trimethyltin laurate), , trimethyltin hydroxide, dibutyltin dilaurate, dibutyltin maleate, etc.), lead-based catalysts (lead oleate, lead naphthenate, lead octenate, etc.), other metal-based catalysts (metal salts of naphthenate such as cobalt naphthenate, etc.), amine-based catalysts such as curing catalysts such as triethylenediamine, tetramethylethylenediamine, tetramethylhexylenediamine, diazabicycloalkenes, dialkylaminoalkylamines, bis(2-dimethylaminoethyl)ether, dimorpholinodiethyl ether, etc.; and waxes such as paraffin wax and microcrystalline wax. Furthermore, wetting agents, thickeners, antifoaming agents, rheology modifiers, etc. may also be added as needed.

[0131] The adhesives and hot melt adhesives described above can be used as hot melt adhesives or reactive hot melt adhesives, or as materials for these. They can be used in fields where hot melt adhesives have traditionally been used, such as the architectural interior (or construction) field, the electronic materials field, and the automotive interior field.

[0132] The above-mentioned hot melt adhesives and reactive hot melt adhesives are suitable for use in adhering automobile interior components and adhering decorative materials to building interior components, but are not particularly limited thereto, and they can also be used for woodworking, paper processing, fiber processing, general purposes, etc.

[0133] The above-mentioned hot melt adhesives and reactive hot melt adhesives can be used in the same manner as conventional hot melt adhesives and reactive hot melt adhesives, and the method of use is not particularly limited. Furthermore, for example, when attaching an adherend to a substrate, the hot melt adhesive or reactive hot melt adhesive may be applied to the substrate side and / or the adherend side.

[0134] The adherend and substrate may be any commonly used material, such as a molding material, a film sheet, or a fibrous material made by weaving synthetic or natural fibers in a spinning machine into a sheet.

[0135] The molding material, film, and sheet are not particularly limited, but are preferably thermoplastic resins, such as polyolefin resins, polyester resins, acetate resins, polystyrene resins, ABS resins, vinyl chloride resins, and polycarbonate resins. Examples of polyolefin resins include polyethylene and polypropylene, and examples of polyester resins include polyethylene terephthalate and polybutylene terephthalate.

[0136] Laminates obtained by bonding an adherend and a substrate with the hot melt adhesive or reactive hot melt adhesive can be used in a variety of applications, specifically in the fields of construction, electronic materials, and automobiles. No special equipment is required to produce laminates; they can be produced using commonly known manufacturing equipment including a conveyor, coater, press, heater, and cutter. For example, laminates can be produced as follows: While the substrate and adherend are conveyed by a conveyor, the hot melt adhesive or reactive hot melt adhesive is applied to the substrate or adherend using a coater. The temperature during application is controlled to a predetermined temperature using a heater. The adherend is lightly pressed against the substrate using a press, and the adherend and substrate are bonded together via the hot melt adhesive or reactive hot melt adhesive. The bonded adherend and substrate are then allowed to cool and then conveyed by a conveyor to solidify the hot melt adhesive or reactive hot melt adhesive. The substrate with the adherend attached is then cut to an appropriate size using a cutter.

[0137] These laminates have high initial adhesive strength due to the hot melt adhesive and reactive hot melt adhesive, and excellent heat resistance after moisture curing, so that the substrate and the adherend are unlikely to peel off, even in summer. It is also possible to produce laminates by manually applying the adhesive without using a coater.

[0138] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Various measurement and evaluation methods are as follows.

[0139] Test Example 1: Adhesives Adhesives of Examples 1 to 9 and Comparative Examples 1 to 7 described below were prepared and evaluated for the items described below.

[0140] Example 1 Production of Polyester (A-1) A reactor equipped with a thermometer, a stirrer, a rectification column, and a nitrogen inlet tube was charged with 180.7 parts by mass (1.53 mol) of succinic acid as polycarboxylic acids (a1), 217.9 parts by mass (0.38 mol) of Pripol 1009 (a hydrogenated dimer acid having 36 carbon atoms), 241.4 parts by mass (2.68 mol) of 1,4-butanediol as polyhydric alcohols (a2), and 0.06 parts by mass of tetrabutyl titanate as a catalyst. The temperature was raised over 2.5 hours until the internal temperature reached 265 ° C., and an esterification reaction was carried out at 265 ° C. for 1.5 hours. Next, 0.06 parts by mass of tetrabutyl titanate was added as a catalyst, the pressure in the system was reduced to 2.5 hPa, and a polymerization reaction was carried out over 1 hour to obtain polyester (A-1).

[0141] Examples 2 to 9 and Comparative Examples 1 to 4 [Production of Polyesters (A-2) to (A-9) and (A'-1) to (A'-4)] Polyesters (A-2) to (A-9) and (A'-1) to (A'-4) were obtained in the same manner as for polyester (A-1), except that the amounts of each raw material charged were changed so that the final compositions would be as shown in Table 1.

[0142] The compositions shown in Table 1 below are the composition ratios (resin composition ratios) of the finished product, and are the relative ratios (molar ratios and mass ratios) of the contents of structural moieties derived from each constituent monomer of the obtained polyester. The abbreviations in Table 1 are as follows: (Polycarboxylic acids) "SuA": succinic acid (plant-derived monomer) "SebA": sebacic acid (plant-derived monomer) "P1009": hydrogenated dimer acid having 36 carbon atoms (Pripol (registered trademark) 1009 manufactured by Equus Japan) (molecular weight: approximately 570) (plant-derived monomer) (Polyhydric alcohols) "EG": ethylene glycol "1,4BG": 1,4-butanediol "1,6HG": 1,6-hexanediol "3MPG": 3-methyl-1,5-pentanediol "NPG": neopentyl glycol "BEPG": 2-butyl-2-ethyl-1,3-propanediol

[0143]

[0144] <Comparative Examples 5 to 7> As Comparative Examples 5 to 7, polyester polyols shown in Table 3 were prepared. In Table 3, the abbreviations are as follows: "HS2H-351A": adipic acid / 1,6-hexanediol (average molecular weight 3500, manufactured by Toyokuni Oil Mills Co., Ltd.) "P-3010": adipic acid / 3-methyl-1,5-pentanediol (average molecular weight 3000, manufactured by Kuraray Co., Ltd.) "P-2050": sebacic acid / 3-methyl-1,5-pentanediol (average molecular weight 2000, manufactured by Kuraray Co., Ltd.)

[0145] <Evaluation Items> For Examples 1 to 9 and Comparative Examples 1 to 7, the ester bond concentration (hereinafter also referred to as "ES concentration"), solubility parameter (SP value), biomass content, melting point (Tm), heat of crystalline fusion (ΔH), glass transition temperature (Tg), mass average molecular weight (Mw), acid value, and hydroxyl value were calculated according to the following procedure. In addition, handleability, solubility, and VOC amount were evaluated. The results are shown in Table 3.

[0146] [ES concentration] The ES concentration was calculated from the charged amounts. The calculation method is to divide the number of moles of the polycarboxylic acid (a1) or the polyhydric alcohol (a2), whichever is charged less, by the total mass of the finished product, and an example of the calculation formula is shown below. Note that when the charged amounts of the polycarboxylic acid (a1) and the polyhydric alcohol (a2) are equal in molar amount, either of the following calculation formulas may be used.

[0147] <When the amount of polycarboxylic acids (a1) is small> Ester bond concentration (mmol / g) = [(A1 / α1 × m1 + A2 / α2 × m2 + A3 / α3 × m3 ...) / Z] × 1000 A: amount of polycarboxylic acids (a1) charged (g) α: molecular weight of polycarboxylic acids (a1) m: number of carboxy groups per molecule of polycarboxylic acids (a1) Z: final mass (g)

[0148] <When the amount of polyhydric alcohols (a2) is small> Ester bond concentration (mmol / g) = [(B1 / β1×n1 + B2 / β2×n2 + B3 / β3×n3 ...) / Z] × 1000 B: amount of polyhydric alcohols (a2) charged (g) β: molecular weight of polyhydric alcohols (a2) n: number of hydroxyl groups per molecule of polyhydric alcohols (a2) Z: final mass (g)

[0149] [Solubility parameter (SP value)] The solubility parameter (SP value) was determined by the known Fedors method. This method is described in R. F. Fedors, Polym. Eng. Sci., 14(2), 147 (1974), and was determined by the following formula from the data on the evaporation energy and molar volume of atoms and atomic groups in the structural formula of the desired polyester (A). Solubility parameter = (ΣΔei / ΣΔvi) １／２ (In the formula, Δei and Δvi represent the vaporization energy and molar volume of an atom or atomic group, respectively.)

[0150] [Biomass Degree] [Method of Calculating Biomass Degree] <In the Case of Polycondensation Reaction: Examples 1 to 9 and Comparative Examples 1 to 4> Biomass Degree (%) = [(Number of moles of carbon of plant-derived monomer calculated from the molar ratio of polycarboxylic acids (a1) and polyhydric alcohols (a2) in polyester (A)) / (Number of moles of carbon of all constituent monomers in polyester (A))] × 100 <In the Case of No Polycondensation Reaction: Comparative Examples 5 to 7> Biomass Degree (%) = [(Number of moles of carbon of plant-derived monomer in polyester (A)) / (Number of moles of carbon of all constituent monomers in polyester (A))] × 100

[0151] [Melting Point] The melting point (Tm) was determined by measuring using a differential scanning calorimeter under the following measurement conditions: a temperature range of −90 to 200° C., and a temperature rise rate of 10° C. / min.

[0152] [Heat of crystalline fusion] The heat of crystalline fusion (ΔH) can be confirmed by a differential scanning calorimeter, and was calculated from the area of ​​the endothermic peak due to crystalline melting observed when measuring at a temperature range of −90 to 200° C. and a temperature rise rate of 10° C. / min.

[0153] [Glass Transition Temperature] The glass transition temperature (Tg) was measured using a differential scanning calorimeter under the following measurement conditions: a temperature range of −90 to 200° C., and a temperature rise rate of 10° C. / min.

[0154] [Weight-average molecular weight] The weight-average molecular weight (Mw) was measured using a high-performance liquid chromatograph (manufactured by Waters, "ACQUITY APC System") equipped with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45, and was calculated in terms of the molecular weight of standard polystyrene.

[0155] [Acid Value] The acid value (mgKOH / g) was determined by dissolving 1 g of polyester (A) in 30 g of a mixed solvent of toluene / methanol (for example, toluene / methanol=9 / 1 by volume) and subjecting the solution to neutralization titration according to JIS K 0070.

[0156] [Hydroxyl Value] The hydroxyl value was determined by neutralization titration in accordance with JIS K 0070.

[0157] [Handling Ease] The handling ease was evaluated according to the following criteria shown in Table 2.

[0158]

[0159] In the above evaluation criteria for handling, A and D represent the most favorable results, B and E represent somewhat favorable results, and C and F represent unfavorable results.

[0160] [Solubility] Solubility was evaluated under the following conditions. A reactor equipped with a thermometer, a stirrer, a reflux tower, and a nitrogen inlet tube was charged with 20 parts by mass of polyester and 80 parts by mass of polypropylene glycol (PPG-1000) having an average molecular weight of approximately 1000, and the internal temperature was raised to 120°C over 0.5 hours. After heating and stirring at 120°C for 1 hour, the contents were visually inspected. ◯: Polyester dissolved ×: Polyester did not dissolve Note that "-" in the table indicates that the evaluation was not performed.

[0161] [Amount of VOCs] The amount of VOCs was measured using a headspace gas chromatograph mass spectrometer and calculated according to the following formula: Sum of peak areas of all observed volatile components × 100 / Peak area of ​​blank (Air) Note that "-" in the table indicates that the measurement was not performed.

[0162] The equipment and conditions used are as follows:

[0163] <Headspace section> Equipment used: Agilent Technologies Headspace Sampler G1888 Oven temperature: 130°C Loop temperature: 140°C Tr. Line temperature: 150°C GC cycle time: 40 min Vial equilibration time: 30 min Vial pressurization time: 1 min Vial capacity: 20 mL Vial pressurization: 15 psi Loop injection time: 0.04 min (injection volume 1 mL) Loop equilibration time: 0.2 min Sample injection time: 1 min Sample shaker: OFF

[0164] <Gas chromatograph section> Equipment used: 6890N Network GC system manufactured by Agilent Technologies Column: DB-17MS (Crosslinked Methyl Siloxane) capillary column Column temperature conditions: After holding at 40°C for 5 minutes, increase the temperature to 200°C at 10°C / min, and then hold at 200°C for 5 minutes Injection port: 180°C Carrier gas: Helium Column flow rate: 1.0 mL / min Split ratio: 30:1 Transfer line: 220°C

[0165] <Mass spectrometer section> Equipment used: Agilent Technologies 5973inert MassSelectiveDetector Mass range: 10 to 600 Ion source temperature: 230°C Number of samples: 2 Quadrupole temperature: 150°C Number of scans: 2.52 / sec Start time: 0 min EM voltage: relative

[0166] Sample amount (vial filling amount): 300 mg

[0167]

[0168] Test Example 2: Reactive Hot Melt Adhesives The reactive hot melt adhesives of Examples 10 to 13 and Comparative Examples 8 and 9 described below were prepared and evaluated for the items described below.

[0169] <Example 10> [Dissolution step] A four-neck flask equipped with a thermometer, a stirrer, and a condenser was charged with 41.08 parts by mass of polypropylene glycol (PPG-2000) having an average molecular weight of about 2000, 2.99 parts by mass of polypropylene glycol (PPG-400) having an average molecular weight of about 400, 24.45 parts by mass of polyester polyol "HS 2H-351A" (manufactured by Toyokuni Oil Mills Co., Ltd., polyester polyol of hexanediol and adipic acid, average molecular weight 3500, melting point 55 ° C., OHV = 32 mg KOH / g), 0.33 parts by mass of "Modaflow 2100" (manufactured by Allnex) as an antifoaming agent, and 23.7 parts by mass of polyester (A-6). The temperature was raised to 130 ° C. in 30 minutes, and the mixture was heated and stirred at 130 ° C. for 1 hour to obtain a uniform solution-like resin composition.

[0170] [Decompression Dehydration Step] The resin composition was heated and stirred at 15 kPa and 130° C. for 1 hour, and then dehydrated under reduced pressure.

[0171] [Urethane prepolymer formation step] After cooling the system to 100°C, 14.0 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI) as an isocyanate and 0.1 parts by mass of 2,2'-dimorpholinodiethyl ether (DMDEE) (manufactured by Mitsui Fine Chemicals, Inc.) as a curing catalyst were added, and the mixture was stirred at 15 kPa and 100°C for 1 hour. After that, the mixture was cooled to obtain a reactive hot melt adhesive.

[0172] <Examples 11 to 13 and Comparative Examples 8 and 9> Reactive hot melt adhesives of Examples 11 to 13 and Comparative Examples 8 and 9 were obtained in the same manner as in Example 10, except that the types and contents of each component were as shown in Table 4.

[0173] <Evaluation Items> The initial strength and final strength were evaluated according to the following procedures for Examples 10 to 13 and Comparative Examples 8 and 9. The results are shown in Table 5.

[0174] [Initial adhesive strength] Two flat bars (wooden, width 1.7 cm, length 7.5 cm, thickness 1.5 mm) were prepared, and one of the flat bars was coated with a heated and melted hot melt adhesive to a thickness of 0.36 mm over an area of ​​1.5 cm x 1.7 cm. The other flat bar was placed on top of the other flat bar, clamped with a double clip, and left to stand for 5 minutes to allow the hot melt adhesive to cool and solidify. After standing, the double clip was removed, and a tensile shear test was performed under the following measurement conditions using a precision universal testing machine (product name: AG-X, manufactured by Shimadzu Corporation) as the tensile tester, to measure the initial adhesive strength. <Measurement conditions> Tensile speed: 5.0 mm / min Measurement temperature: 23°C

[0175] [Final adhesive strength] Two adherends were prepared, and one of them was coated with a 1.5 cm x 2.5 cm (1.5 cm x 1.7 cm if the adherend was wood) hot melt adhesive at a thickness of 0.36 mm over an area of ​​1.5 cm x 2.5 cm. The other adherend was placed on top of the other adherend, clamped with double clips, and left to stand for three days to allow the hot melt adhesive to moisture cure. After standing, the double clips were removed, and a tensile shear test was performed under the following measurement conditions using a precision universal testing machine (product name: AG-X, manufactured by Shimadzu Corporation) as the tensile tester, to measure the final adhesive strength. Note that "-" in the table indicates that the result was not evaluated. <Measurement conditions> Tensile speed: 5.0 mm / min Measurement temperature: 23°C

[0176] The adherends used were as follows: SUS plate (width 2.5 cm, length 10 cm, thickness 1.5 mm) GFRP plate (width 2.5 cm, length 10 cm, thickness 2 mm) PC plate (width 2.5 cm, length 10 cm, thickness 2 mm) Flat bar (wood) (width 1.7 cm, length 7.5 cm, thickness 1.5 mm)

[0177]

[0178]

[0179] In Comparative Example 8, which did not use Polyester A, cohesive failure of the adhesive occurred mainly when measuring the initial strength and final strength. That is, adhesive strength was not achieved due to insufficient cohesive strength of the adhesive. On the other hand, in Comparative Example 9, in which polyester polyol (HS-2H-351A) was used in place of Polyester A in an increased amount, interfacial peeling occurred mainly between the adhesive and the adherend when measuring the final strength. That is, although the cohesive strength was sufficient, adhesive strength was not achieved due to insufficient adhesion of the adhesive to the adherend.

[0180] The polyesters of Examples 1 to 9 were excellent in handleability, solubility in liquid polyols, and low VOC properties, making them suitable for use as reactive hot melt adhesives. On the other hand, polyester A'-1 of Comparative Example 1, in which the polyester had a melting point of less than 30°C, was poor in handleability, and polyesters A'-2 to A'-4 of Comparative Examples 2 to 4, in which the polyester ester bond concentration exceeded 10.00 mmol / g, were poor in solubility in liquid polyols and difficult to use as reactive hot melt adhesives.

[0181] Furthermore, the polyester polyols of Comparative Examples 5 to 7, in which the weight average molecular weight of the polyester was less than 25,000, had a large amount of VOC.

[0182] Furthermore, the reactive hot melt adhesives of Examples 10 to 13 prepared using the polyesters A-6 to A-9 of Examples 6 to 9 were able to achieve both high levels of initial strength and final strength, whereas the reactive hot melt adhesive of Comparative Example 8, which did not use polyester (A), lacked cohesive strength and was poor in initial strength and final strength. Also, the reactive hot melt adhesive of Comparative Example 9, which did not use polyester (A) but instead increased the amount of the polyester polyol "HS2H-351A" of Comparative Example 5, in which the polyester had a mass average molecular weight of less than 25,000, had cohesive strength and excellent initial strength, but lacked interfacial adhesion and was poor in final strength.

[0183] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on May 16, 2023 (Patent Application No. 2023-081086), May 16, 2023 (Patent Application No. 2023-081088), and July 21, 2023 (Patent Application No. 2023-119125), the contents of which are incorporated herein by reference.

[0184] The polyester used in the adhesive, hot melt adhesive, and reactive hot melt adhesive of this embodiment is a resin that is solid at room temperature and has excellent handleability, for example, in pellet form, and is soluble in liquid polyols such as polypropylene glycol, which are commonly used in reactive hot melt adhesives, so it can be used in applications such as hot melt adhesives and reactive hot melt adhesives. Furthermore, because it has a low VOC content and can be designed for high biomass, the adhesive of this embodiment using this polyester can be suitably used as an adhesive, hot melt adhesive, or reactive hot melt adhesive that has low odor characteristics and is environmentally friendly.

Claims

1. An adhesive containing a polyester (A) that satisfies the following constituent requirements (1) to (4): (1) The polyester (A) has a structural portion derived from a polycarboxylic acid (a1) and a structural portion derived from a polyhydric alcohol (a2). (2) The ester bond concentration of the polyester (A) is 10.00 mmol / g or less. (3) The melting point of the polyester (A) is 30°C or higher. (4) The weight average molecular weight of the polyester (A) is 25,000 or more.

2. The adhesive according to claim 1 , wherein the polyester (A) further satisfies the following constituent requirement (5): (5) In the polyester (A), the structural moiety derived from the aliphatic polycarboxylic acid (a1-1) accounts for 50 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1).

3. The adhesive according to claim 1 or 2, wherein the polyester (A) further satisfies the following constituent requirement (6): (6) The hydroxyl value of the polyester (A) is less than 12 mgKOH / g.

4. The solubility parameter (SP value) of the polyester (A) is 10.50 (cal / cm ３ ) １／２ 3. The adhesive of claim 1 or 2, wherein:

5. The adhesive according to claim 1 or 2, wherein the content of the organic solvent in the adhesive is 5% by mass or less.

6. The adhesive according to claim 1 or 2, wherein a structural moiety derived from a monomer having an aromatic ring accounts for 30 mass % or less of the entire polyester (A).

7. The adhesive according to claim 1 or 2, wherein the polyester (A) has a glass transition temperature of 0°C or lower.

8. The adhesive according to claim 1 or 2, wherein the polyester (A) has a crystalline heat of fusion of 3 J / g or more.

9. The adhesive according to claim 1 or 2, wherein the polyester (A) has a mass average molecular weight of 30,000 or more.

10. The adhesive according to claim 1 or 2, wherein the polyester (A) has a mass average molecular weight of 40,000 or more.

11. The adhesive according to claim 1 or 2, which contains a urethane prepolymer (X) having an isocyanate group.

12. The adhesive according to claim 11 , wherein the urethane prepolymer (X) contains a structural moiety derived from a polyalkylene glycol (B).

13. The adhesive according to claim 12, wherein the polyalkylene glycol (B) has an average molecular weight of 200 to 5,000.

14. The adhesive according to claim 11 , wherein the urethane prepolymer (X) contains a structural moiety derived from a polyester polyol (C) different from the polyester (A).

15. The adhesive according to claim 14, wherein the polyester polyol (C) has an average molecular weight of 500 to 5,500.

16. A reactive hot melt adhesive comprising the adhesive of claim 1 or 2.

17. A polyester (A) for adhesives that satisfies the following constituent requirements (1) to (4). (1) The polyester (A) has a structural portion derived from a polycarboxylic acid (a1) and a structural portion derived from a polyhydric alcohol (a2). (2) The ester bond concentration of the polyester (A) is 10.00 mmol / g or less. (3) The melting point of the polyester (A) is 30°C or higher. (4) The weight average molecular weight of the polyester (A) is 25,000 or more.