Adhesive containing β-1,3-glucan derivative

Abstract

Provided is an adhesive having high sustainability and excellent adhesiveness.　Provided is an adhesive comprising a β-1,3-glucan derivative in which some or all of hydrogen atoms of hydroxy groups are substituted by a first acyl group and a second acyl group, wherein the first acyl group is an acyl group having 2-5 carbon atoms, and the second acyl group is an acyl group having 6-20 carbon atoms. Also provided is an adhesion method involving bringing the adhesive into contact with a material. Also provided is a method for producing an adhesive-bonded body, the method involving bringing the adhesive into contact with a material.

Description

Adhesives containing β-1,3-glucan substituted compounds

[0001] The present invention relates to an adhesive containing a β-1,3-glucan substituted compound.

[0002] Adhesives made from naturally derived biomass resources are attracting attention as adhesives that have a low environmental impact and are expected to contribute to a sustainable society. For example, adhesives made from derivatives of β-1,3-glucan (also called paramylon) produced by certain microalgae such as Euglena are considered highly useful because they have excellent adhesive properties, a low environmental impact, and high sustainability (Patent Document 1). On the other hand, adhesives made from such naturally derived biomass resources tend to have more difficulty in obtaining desired properties (for example, sufficient adhesive properties for manufacturing the target industrial product) compared to non-natural adhesives (for example, synthetic adhesives using various petroleum resins).

[0003] Japanese Patent Publication No. 2018-154723

[0004] This disclosure aims to provide an adhesive that is highly sustainable and has excellent adhesive properties.

[0005] The inventors have found that β-1,3-glucan substituted compounds, in which some or all of the hydroxyl groups are substituted by two acyl groups with different numbers of carbon atoms, have excellent adhesive properties, and have completed the present invention. That is, according to the present disclosure, for example, the following embodiments are provided: [1] An adhesive comprising a β-1,3-glucan substituted compound in which some or all of the hydrogen atoms of a hydroxyl group are substituted by a first acyl group and a second acyl group, wherein the first acyl group is an acyl group having 2 to 5 carbon atoms, and the second acyl group is an acyl group having 6 to 20 carbon atoms.

[0006] According to this disclosure, it is possible to provide an adhesive that is highly sustainable and has excellent adhesive properties.

[0007] One embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications as long as they do not impede the effects of the present invention. If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments. In this specification, the expression "X to Y" means "X or more and Y or less". Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments, but only by the claims. Each aspect disclosed herein can be combined with any other features disclosed herein.

[0008] <Adhesive containing a β-1,3-glucan-substituted compound> In one embodiment, an adhesive is disclosed which contains a β-1,3-glucan-substituted compound in which some or all of the hydrogen atoms of a hydroxyl group are substituted by a first acyl group and a second acyl group, wherein the first acyl group is an acyl group having 2 to 5 carbon atoms, and the second acyl group is an acyl group having 6 to 20 carbon atoms. This adhesive tends to be highly sustainable and have excellent adhesive properties.

[0009] [Adhesives] An "adhesive" is a substance used for bonding. "To bond" means to bring about adhesion, and "adhesion" is the state of things of the same or different kinds becoming one. Furthermore, "adhesion" refers to the properties that bring about adhesion.

[0010] The adhesive is preferably solid or liquid at room temperature, and more preferably solid. Room temperature is typically 5 to 35°C, and may be, for example, 20°C, 23°C, or 25°C. Room temperature may also be room temperature. If the adhesive is solid, it may take the form of a resin film, as described later.

[0011] The adhesive may be a hot-melt adhesive. A hot-melt adhesive is an adhesive that uses a thermoplastic polymer that is solid at room temperature and liquid at high temperatures, and utilizes a heating-melting-cooling-solidification cycle to bond various materials such as plastics, metals, wood-based materials, paper, and painted surfaces. Hot-melt adhesives are widely used industrially because they are highly safe as they do not contain volatile solvents, and they have excellent properties such as not shrinking due to drying.

[0012] Adhesives may also be called adhesives. An "adhesive" is a substance used for adhesion, and "adhesion" is the process of causing adhesion. Adhesion is a phenomenon commonly seen in high-viscosity liquids, where adhesion occurs with only slight pressure applied for a short time without causing a change in state.

[0013] The adhesive may be an easily disassembled adhesive. An easily disassembled adhesive is an adhesive designed so that the bonded area can be disassembled by chemical and / or physical means when needed. Easily disassembled adhesives facilitate the reuse and recycling of the adherends.

[0014] The application of the adhesive is not limited to the extent that the effects of the present invention can be obtained. The adhesive may be, for example, a structural adhesive. A structural adhesive is an adhesive that, when materials are bonded together, provides a bonding surface that has the same resistance to stress as the materials themselves. The structural adhesive may be a structural adhesive for transportation equipment. Non-limiting examples of transportation equipment include automobiles and ships. A structural adhesive for transportation equipment can be suitably used, for example, for bonding components of a prime mover in transportation equipment.

[0015] The materials to which the adhesive adheres may be of any material and shape, as long as the effects of the present invention are obtained. Non-limiting examples of materials to which the adhesive adheres include metal plates and resin plates, which will be described later.

[0016] [β-1,3-Glucan and β-1,3-Glucan Substitutes] "β-1,3-Glucan" is a polysaccharide in which glucose is polymerized by β-1,3 bonds. β-1,3-Glucan may be of biological origin or a synthetic product. From the viewpoint of reducing environmental impact, biological origin is preferred. The organism may be any organism within the range in which the effects of the present invention can be obtained. As for biologically derived β-1,3-glucan, β-1,3-glucan isolated from microalgae that synthesize β-1,3-glucan in their cells is preferred. As for microalgae, Euglena (Japanese name: Midorimushi) is preferred, and Euglena gracilis is more preferred. Euglena is easy to cultivate, has a fast growth cycle, and accumulates a large amount of β-1,3-glucan particles in its cells as a photosynthetic product. Furthermore, the isolation of β-1,3-glucan from microalgae can be easily performed using standard methods. Note that β-1,3-glucan produced by the Euglena genus is also known as paramylon.

[0017] A "β-1,3-glucan substituted compound" is a compound in which at least one hydrogen atom of a hydroxyl group in at least one glucose unit of β-1,3-glucan is substituted with a functional group such as an acyl group. β-1,3-glucan substituted compounds can be prepared according to standard methods. Specific examples of such methods will be described later.

[0018] [First Acyl Group] The first acyl group is an acyl group having 2 to 5 carbon atoms, preferably an acyl group having 2 to 4 carbon atoms, and more preferably an acyl group having 2 or 3 carbon atoms. The first acyl group may contain saturated or unsaturated, substituted or unsubstituted, aliphatic or aromatic hydrocarbon groups, preferably a saturated, unsubstituted aliphatic hydrocarbon group. The first acyl group may also contain linear, branched, or cyclic hydrocarbon groups, preferably a linear hydrocarbon group. Non-limiting examples of the first acyl group include acetyl group (2 carbon atoms), propionyl group (3 carbon atoms), isopropionyl group (3 carbon atoms), butyryl group (4 carbon atoms), isobutyryl group (4 carbon atoms), and pentanoyl group (5 carbon atoms).

[0019] [Second Acyl Group] The second acyl group is an acyl group having 6 to 20 carbon atoms, preferably an acyl group having 7 to 18 carbon atoms. The second acyl group may contain saturated or unsaturated, substituted or unsubstituted, aliphatic or aromatic hydrocarbon groups, preferably saturated or unsubstituted aliphatic hydrocarbon groups. The second acyl group may also contain linear, branched, or cyclic hydrocarbon groups, preferably linear hydrocarbon groups. Non-limiting examples of the second acyl group include the hexanoyl group (6 carbon atoms), heptanolyl group (7 carbon atoms), octanoyl group (8 carbon atoms), nonanoyl group (9 carbon atoms), decanoyl group (10 carbon atoms), undecanoyl group (11 carbon atoms), lauroyl group (12 carbon atoms), tridecanoyl group (13 carbon atoms), myristoyl group (14 carbon atoms), pentadecanoyl group (15 carbon atoms), palmitoyl group (16 carbon atoms), heptadecanoyl group (17 carbon atoms), stearoyl group (18 carbon atoms), oleoyl group (18 carbon atoms), linoleoyl group (18 carbon atoms), linolenoyl group (18 carbon atoms), nonadecanoyl group (19 carbon atoms), eicosanoyl group (20 carbon atoms), and eicosanoyl group (20 carbon atoms).

[0020] [Degree of substitution in β-1,3-glucan-substituted compounds] The degree of substitution in β-1,3-glucan-substituted compounds refers to the proportion of acyl groups attached to each glucose unit in the β-1,3-glucan-substituted compound. For example, a degree of substitution of 1.0 means that, on average, one acyl group is introduced per glucose unit. Theoretically, the upper limit of the degree of acyl group substitution is 3.0, and the lower limit is 0.

[0021] Unless otherwise specified, the degree of substitution is the ratio of all acyl groups attached to each glucose unit of the β-1,3-glucan-substituted product, and in this case, the degree of substitution is also called the total degree of substitution. The degree of substitution (total degree of substitution) of the β-1,3-glucan-substituted product is preferably 2.0 or more and 3.0 or less, more preferably 2.3 or more and 3.0 or less. When the degree of substitution (total degree of substitution) of the β-1,3-glucan-substituted product is within this range, the β-1,3-glucan-substituted product tends to have excellent adhesion.

[0022] Furthermore, when multiple types of acyl groups are bonded to the β-1,3-glucan-substituted product, the degree of substitution may be the degree of substitution by a specific acyl group among the multiple types of acyl groups. For example, the proportion of the first acyl group and the proportion of the second acyl group bonded to one glucose unit of the β-1,3-glucan-substituted product are referred to as the degree of substitution by the first acyl group and the degree of substitution by the second acyl group, respectively. When multiple types of acyl groups are bonded to the β-1,3-glucan-substituted product, the sum of the degrees of substitution by each acyl group becomes the total degree of substitution. The degree of substitution by the first acyl group of the β-1,3-glucan-substituted product is preferably 1.7 to 2.9, more preferably 1.8 to 2.8. The degree of substitution by the second acyl group of the β-1,3-glucan-substituted product is preferably 0.1 to 1.0, more preferably 0.2 to 0.9. When the degree of substitution by the first acyl group and / or the second acyl group of the β-1,3-glucan-substituted compound is within these ranges, the β-1,3-glucan-substituted compound tends to have excellent adhesive properties.

[0023] The degree of substitution in β-1,3-glucan-substituted compounds can be evaluated by standard methods. Such methods include, for example, nuclear magnetic resonance spectroscopy (NMR) and elemental analysis. When using nuclear magnetic resonance spectroscopy (NMR), typically, １ The degree of acyl group substitution is evaluated by 1H-NMR based on the integral value of hydrogen directly bonded to the carbon of the glucose unit (hydrogen of the methylene and methine groups) and hydrogen of the acyl group. The total degree of substitution of the β-1,3-glucan-substituted product, the degree of substitution by the first acyl group, and the degree of substitution by the second acyl group can be adjusted in the method for producing the β-1,3-glucan-substituted product described later by changing the charging ratio of the first acyling agent for introducing the first acyl group, the second acyling agent for introducing the second acyl group, and the glucose unit contained in the β-1,3-glucan.

[0024] [Glass Transition Temperature (Tg)] The glass transition temperature (Tg) of the adhesive is preferably 30°C or higher, more preferably 50°C or higher, even more preferably 80°C or higher, particularly preferably 100°C or higher, or preferably 50°C to 200°C, more preferably 80°C to 200°C, particularly preferably 100°C to 160°C. When the glass transition temperature (Tg) is within this range, the adhesive is more likely to maintain a stable bond between the bonded materials under normal usage conditions. Furthermore, when the glass transition temperature (Tg) is within this range, the adhesive can be suitably used, in particular, as a hot-melt adhesive.

[0025] In this disclosure, the glass transition temperature (Tg) is preferably defined as the temperature at which the tanδ obtained by dynamic viscoelasticity measurement reaches its maximum value. Dynamic viscoelasticity measurement can be performed by a standard method. For example, dynamic viscoelasticity measurement can be performed using a dynamic viscoelasticity measuring device (e.g., EPLEXOR 500N, GABO). In this case, a small piece of β-1,3-glucan-substituted material measuring 40 mm in length, 10 mm in width, and 2 mm in thickness is set in the dynamic viscoelasticity measuring device by clamping it with a gripping distance of 20 mm, and measured in tensile mode, frequency of 1 Hz, heating rate of 5 °C / min, and from -120 °C to 200 °C to determine the storage modulus E' and loss modulus E'' in the range of -120 °C to 200 °C, and tanδ is determined as the ratio of the loss modulus E'' to the storage modulus E', and the glass transition temperature (Tg) can be determined as the temperature at which tanδ reaches its maximum value in the range of -120 °C to 200 °C. The glass transition temperature (Tg) of the adhesive can be adjusted by changing the total degree of substitution of the β-1,3-glucan-substituted compound, the degree of substitution by the first acyl group, and / or the degree of substitution by the second acyl group.

[0026] [Storage Modulus] The storage modulus E' of an adhesive may be, for example, 10 MPa or more, 20 MPa or more, 30 MPa or more, 50 MPa or more, or 100 MPa or more, or 10 MPa to 9000 MPa, 20 MPa to 9000 MPa, 50 MPa to 9000 MPa, 50 MPa to 7000 MPa, 50 MPa to 2000 MPa, or 100 MPa to 1600 MPa. When the storage modulus E' is within these ranges, the adhesive has excellent hardness and is good at maintaining a stable bond between bonded materials. The storage modulus E' can be measured by a standard method. For example, as described above, the storage modulus E' can be measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR 500N, GABO or dynamic viscoelasticity measuring device ARES-G2, TA Instruments). The storage modulus E' of the adhesive can be adjusted by changing the total degree of substitution of the β-1,3-glucan-substituted compound, the degree of substitution by the first acyl group, and / or the degree of substitution by the second acyl group.

[0027] [Resin Film] The adhesive can take the form of a resin film. The adhesive can also be made into a resin film by known methods. A non-limiting example of a known method is a heat press. A heat press can be performed, for example, by placing an adhesive that is solid at room temperature on a Kapton film, covering it with another Kapton film, sandwiching the resulting mixture between two aluminum plates, and pressing it at a temperature of 180°C to 220°C for 5 minutes. The thickness of the resin film can be appropriately set depending on the application. For example, the thickness of the resin film may be 10 to 1000 μm, preferably 20 to 500 μm, and more preferably 50 to 200 μm. Furthermore, when the resin film is used for measuring the tensile shear adhesive strength described later, the thickness of the resin film is preferably about 70 μm.

[0028] [Tensile Shear Bonding Strength] The tensile shear bonding strength of the adhesive at 23°C with respect to a metal plate is preferably 7.0 MPa or higher, more preferably 7.4 MPa or higher, particularly preferably 9 MPa or higher, or preferably 7.0 MPa to 40 MPa, more preferably 7.4 MPa to 40 MPa, particularly preferably 9 MPa to 35 MPa. The tensile shear bonding strength of the adhesive at 23°C with respect to a resin plate is preferably 1 MPa or higher, more preferably 2 MPa or higher, or preferably 1 MPa to 30 MPa, more preferably 2 MPa to 25 MPa. When the tensile shear bonding strength of the β-1,3-glucan-substituted compound at 23°C falls within these ranges, the adhesive is likely to exhibit the desired adhesion.

[0029] A metal plate is a plate-shaped metal substrate, and its shape and properties are not limited as long as the effects of the present invention can be obtained. Non-limiting examples of metal plates include aluminum plates and steel plates. A resin plate is a plate-shaped resin substrate, and its shape and properties are not limited as long as the effects of the present invention can be obtained. Non-limiting examples of resin plates include polyamide plates, polyoxymethylene plates, polyphenylene ether plates, polypropylene plates, polyethylene plates, or polyethylene terephthalate plates.

[0030] Tensile shear adhesive strength can be evaluated by a standard method. A standard method is the one conforming to JIS K 6850:1999 (corresponding to ISO 4587). The method conforming to JIS K 6850:1999 can be suitably carried out by the following procedure. Two 100 mm × 25 mm × 3 mm aluminum alloy (A6061) pieces are used to sandwich the aforementioned resin film, which is cut to a size of 25 mm × 5 mm and has a thickness of approximately 70 μm, at room temperature (overlap area: 25 mm × 5 mm). This is heated at 180°C to 220°C for 30 minutes, and then cooled in a 23°C environment to obtain an adhesive test piece. The adhesive test piece is held in a universal testing machine (AGS-50NX, Shimadzu Corporation), and a tensile load with displacement control of 1 mm / min is applied to both ends at room temperature. The tensile shear adhesive strength is calculated by dividing the load at which the test piece breaks by the adhesive area.

[0031] [Maintenance of tensile shear adhesive strength after dismantling and re-bonding] When adherends bonded with an adhesive are dismantled and then re-bonded, the maintenance rate of tensile shear adhesive strength may be 50% or more, preferably 60% or more, more preferably 75%, and particularly preferably 85% or more. The adherend may be any adherend within the range in which the effects of the present invention can be obtained, for example, the metal plate or resin plate mentioned above. The maintenance rate of tensile shear adhesive strength is the percentage of the tensile shear adhesive strength of the adhesive after re-bonding to the tensile shear adhesive strength of the adhesive before re-bonding. Adhesives having a tensile shear adhesive strength maintenance rate within the above range are suitable for repeated use and are advantageous in terms of cost reduction, simplification of work, reduction of environmental impact, and recycling.

[0032] The retention rate of tensile shear adhesive strength can be suitably determined by the following procedure: (1) As described above, the tensile shear adhesive strength is calculated on an adhesive test specimen (adhesive test specimen before disassembly and re-adhesion) obtained by bonding two 100 mm × 25 mm × 3 mm aluminum alloy plates (A6061) with an adhesive. (2) The adhesive test specimen from (1) is heated in an electric furnace at 180°C for 2 minutes, and immediately after removing the adhesive test specimen from the electric furnace, it is pulled apart by hand to disassemble the adhesive test specimen. Then, the two disassembled aluminum alloy plates are re-bonded by a simple overlap joint under the same temperature conditions as before disassembly and re-adhesion to obtain an adhesive test specimen after disassembly and re-adhesion. The tensile shear adhesive strength of the adhesive test specimen after disassembly and re-adhesion is measured in the same manner as in (1). The retention rate of tensile shear adhesive strength can be calculated as the percentage of the tensile shear adhesive strength in (2) to the tensile shear adhesive strength in (1). (3) Optionally, the operation in (2) may be repeated multiple times (for example, four times). In this case, the retention rate of the tensile shear adhesive strength may be calculated as the percentage of the tensile shear adhesive strength in the adhesive test specimen after repeating the operation in (2) multiple times (for example, four times) relative to the tensile shear adhesive strength in (1).

[0033] [Other properties] The degree of polymerization of the β-1,3-glucan derivative contained in the adhesive is not limited within the range where the scope of the present invention can be obtained, but is preferably from 60 to 3000, more preferably from 1000 to 2500, and even more preferably from 1500 to 2000. When the degree of polymerization is within these ranges, an adhesive having desired adhesiveness is easily obtained.

[0034] The weight average molecular weight Mw of the β-1,3-glucan derivative is preferably 200,000 or more and 800,000 or less, and more preferably 250,000 or more and 700,000 or less. The number average molecular weight Mn of the β-1,3-glucan derivative is preferably 150,000 or more and 600,000 or less, and more preferably 200,000 or more and 500,000. When the molecular weight of the β-1,3-glucan derivative is within these ranges, an adhesive having desired adhesiveness is easily obtained.

[0035] The dispersity Mw / Mn of the β-1,3-glucan derivative contained in the adhesive is preferably 1.0 or more and 1.6 or less, and more preferably 1.0 or more and 1.2 or less. Here, Mw is the weight average molecular weight and Mn is the number average molecular weight. Mw and Mn can be calculated in terms of polystyrene by, for example, GPC (gel permeation chromatography). When the dispersity Mw / Mn is within these ranges, an adhesive having desired adhesiveness is easily obtained.

[0036] [Method for producing the adhesive] The method for producing the adhesive preferably includes acylating part or all of the hydroxyl groups in the glucose constituting β-1,3-glucan with a first acylating agent for introducing a first acyl group and a second acylating agent for introducing a second acyl group. Specifically, the method for producing the adhesive may be (i) a method in which the dissolved β-1,3-glucan is reacted with the first acylating agent to form a monoester and then reacted with the second acylating agent to synthesize a mixed ester, or (ii) a method in which an acid anhydride is reacted with a carboxylic acid having an arbitrary carbon chain length to cause a transesterification reaction and then reacted with β-1,3-glucan to form a mixed ester.

[0037] (i) In a method of synthesizing a mixed ester by reacting dissolved β-1,3-glucan with a first acyling agent to produce a monoester, and then reacting it with a second acyling agent, the first acyl group and the second acyl group can be introduced to the β-1,3-glucan in a sequential process. The first acyling agent may be any compound as long as it is a compound that effectively introduces the first acyl group to some or all of the hydroxyl groups in the glucose constituting the β-1,3-glucan. Non-limiting examples of the first acyling agent include acetyl chloride (2 carbon atoms), propionyl chloride (3 carbon atoms), isopropionyl chloride (3 carbon atoms), butyryl chloride (4 carbon atoms), isobutyryl chloride (4 carbon atoms), and pentanoyl chloride (5 carbon atoms). Furthermore, the second acylating agent may be any compound, as long as it effectively introduces the second acyl group to some or all of the hydroxyl groups in the glucose constituting the β-1,3-glucan. Non-limiting examples of the first acylating agent include hexanoyl chloride (6 carbon atoms), heptanoyl chloride (7 carbon atoms), octanoyl chloride (8 carbon atoms), nonanoyl chloride (9 carbon atoms), decanoyl chloride (10 carbon atoms), lauroyl chloride (12 carbon atoms), myristoyl chloride (14 carbon atoms), palmitoyl chloride (16 carbon atoms), stearoyl chloride (18 carbon atoms), oleoyl chloride (18 carbon atoms), linoleoyl chloride (18 carbon atoms), and linolenoyl chloride (18 carbon atoms).

[0038] (ii) In the method of causing an ester exchange reaction by reacting an acid anhydride with a carboxylic acid having an arbitrary carbon chain length and then reacting with β-1,3-glucan to obtain a mixed ester, the first acyl group and the second acyl group can be introduced into β-1,3-glucan by the same process. The acid anhydride may be any acid anhydride within the range where the effects of the present invention can be obtained. Non-limiting examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, and octanoic anhydride. The carboxylic acid having an arbitrary carbon chain length may be any compound within the range where the effects of the present invention can be obtained. Non-limiting examples thereof include hexanoic acid (carbon number 6), heptanoic acid (carbon number 7), octanoic acid (carbon number 8), nonanoic acid (carbon number 9), decanoic acid (carbon number 10), undecanoic acid (carbon number 11), lauric acid (carbon number 12), tridecanoic acid (carbon number 13), myristic acid (carbon number 14), pentadecanoic acid (carbon number 15), palmitic acid (carbon number 16), heptadecanoic acid (carbon number 17), stearic acid (carbon number 18), oleic acid (carbon number 18), linoleic acid (carbon number 18), linolenic acid (carbon number 18), nonadecanoic acid (carbon number 19), icosanoic acid (carbon number 20), and eicosanoic acid (carbon number 20).

[0039] <Adhesion method> In one embodiment, an adhesion method is disclosed that includes bringing an adhesive into contact with a material. The adhesive and the material are as described above. The adhesion method preferably includes a step of heating and softening the adhesive before and / or after bringing the adhesive into contact with the material, and / or a step of air-cooling and curing the adhesive after bringing the adhesive into contact with the material.

[0040] <Method for producing an adhesive bonded body> In one embodiment, a method for producing an adhesive bonded body is disclosed that includes bringing an adhesive into contact with a material. More specifically, a method for producing an adhesive bonded body is disclosed that includes gripping an adhesive formed in the form of a resin film with two adherends, heating at a temperature above the melting point, and then air-cooling. The adhesive and the material are as described above. The adhesive bonded body is not particularly limited as long as it is an adhesive bonded body including a material bonded by an adhesive.

[0041] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below: [1] An adhesive comprising a β-1,3-glucan-substituted compound in which some or all of the hydrogen atoms of a hydroxyl group are substituted by a first acyl group and a second acyl group, wherein the first acyl group is an acyl group having 2 to 5 carbon atoms, and the second acyl group is an acyl group having 6 to 20 carbon atoms. [2] The adhesive according to [1], wherein the degree of substitution of the substituted β-1,3-glucan-substituted compound is 2.0 to 3.0. [3] The adhesive according to [1] or [2], wherein the glass transition temperature (Tg) is 30°C or higher. [4] The adhesive according to any one of [1] to [3], wherein the storage modulus E' at 23°C is 10 MPa or higher. [5] The adhesive according to any one of [1] to [4], wherein the tensile shear bond strength to a metal plate at 23°C is 7.0 MPa or higher. [6] The adhesive according to [5], wherein the metal plate is an aluminum plate or a steel plate. [7] The adhesive according to any one of [1] to [6], wherein the tensile shear adhesive strength to a resin plate at 23°C is 1 MPa or more. [8] The adhesive according to [7], wherein the resin plate is a polyamide plate, a polyoxymethylene plate, a polyphenylene ether plate, a polypropylene plate, a polyethylene plate, or a polyethylene terephthalate plate. [9] The adhesive according to any one of [1] to [8], which is a structural adhesive for transport equipment.

[10] The adhesive according to any one of [1] to [9], which is an easily disassembled adhesive.

[11] The adhesive according to any one of [1] to

[10] , which is a hot melt adhesive.

[12] The adhesive according to any one of [1] to

[11] , wherein the retention rate of the tensile shear adhesive strength when the adherends bonded with the adhesive are disassembled and then re-bonded is 50% or more.

[13] A bonding method comprising bringing the adhesive according to any one of [1] to

[11] into contact with a material. A method for manufacturing an adhesive bond, comprising bringing an adhesive described in any of [1] to

[11] into contact with a material. Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments.

[0042] The present invention will be described in more detail below with reference to examples, but the interpretation of the present invention is not limited by these examples.

[0043] [Synthesis of β-1,3-glucan substituted compounds] (Example 1) 5 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in 250 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.95 g of lithium chloride (0.0932 mol) was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.185 mol) and hexanoic acid (0.139 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.715 g of 4-dimethylaminopyridine (0.0059 mol) were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 4000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 400 mL of methanol, filtered again, and dissolved in 150 mL of chloroform. The solution was poured into 1600 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 8.4 g of product (95% yield). １ The degree of substitution was determined by H-NMR.

[0044] (Example 2) 10 g of β-1,3-glucan (0.0617 mol in glucose units) was suspended in 500 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 7.84 g (0.184 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.370 mol) and decanoic acid (0.222 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 1.43 g (0.0118 mol) of 4-dimethylaminopyridine were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 1200 mL of methanol, and the resulting solid was filtered off. The solid was washed with 500 mL of methanol, filtered again, and dissolved in 200 mL of chloroform. The solution was poured into 1600 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 17.2 g of product (yield 84%). １ The degree of substitution was determined by H-NMR.

[0045] (Example 3) 10 g of β-1,3-glucan (0.0617 mol in glucose units) was suspended in 500 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 7.84 g (0.184 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.370 mol) and lauric acid (0.222 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 1.43 g (0.0118 mol) of 4-dimethylaminopyridine were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 10,000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 500 mL of methanol, filtered again, and dissolved in 200 mL of chloroform. The solution was poured into 1,800 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 17.6 g of product (84% yield). １ The degree of substitution was determined by H-NMR.

[0046] (Example 4) 5 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in 300 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.95 g of lithium chloride (0.0932 mol) was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.185 mol) and myristic acid (0.139 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.715 g of 4-dimethylaminopyridine (0.0059 mol) were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 5000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 400 mL of methanol, filtered again, and dissolved in 150 mL of chloroform. The solution was poured into 1800 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 8.65 g of product (yield 86%). １ The degree of substitution was determined by H-NMR.

[0047] (Example 5) 10 g of β-1,3-glucan (0.0617 mol in glucose units) was suspended in 500 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 7.84 g (0.184 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.370 mol) and myristic acid (0.278 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 1.43 g (0.0118 mol) of 4-dimethylaminopyridine were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 9000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 300 mL of methanol, filtered again, and dissolved in 200 mL of chloroform. The solution was poured into 1600 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 17.5 g of product (85% yield). １ The degree of substitution was determined by H-NMR.

[0048] (Example 6) 10 g of β-1,3-glucan (0.0617 mol in glucose units) was suspended in 500 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 7.84 g (0.184 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing acetic anhydride (0.370 mol) and palmitic acid (0.185 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 1.43 g (0.0118 mol) of 4-dimethylaminopyridine were added. The mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 6000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 500 mL of methanol, filtered again, and dissolved in 250 mL of chloroform. The solution was poured into 2400 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 19.6 g of product (90% yield). １ The degree of substitution was determined by H-NMR.

[0049] (Example 7) 10 g of β-1,3-glucan (0.0617 mol in terms of glucose units) was suspended in dehydrated N,N-dimethylacetamide (500 mL) under a nitrogen atmosphere, 7.84 g (0.184 mol) of lithium chloride was added, and the mixture was heated and stirred at 115 °C for 1 hour. To the resulting homogeneous solution, a solution obtained by mixing acetic anhydride (0.370 mol) and stearic acid (0.185 mol) and heating and stirring at 100 °C for 1 hour under a nitrogen atmosphere, and 1.43 g (0.0118 mol) of 4-dimethylaminopyridine were added, and the mixture was further heated and stirred at 100 °C for 3 hours. The mixed solution was poured into 7000 mL of methanol, and the resulting solid was collected by filtration. The solid was washed with 500 mL of methanol, collected by filtration again, and dissolved in 350 mL of chloroform. The solution was poured into 2700 mL of methanol, and the precipitated solid was collected by filtration. The obtained solid was dried in vacuo at 80 °C to obtain 21.8 g of the product (yield 92%). １ The degree of substitution was determined by the 1H-NMR method.

[0050] (Example 8) 5.0 g of β-1,3-glucan (0.0309 mol in terms of glucose units) was suspended in dehydrated N,N-dimethylacetamide (250 mL) under a nitrogen atmosphere, 3.95 g (0.0932 mol) of lithium chloride was added, and the mixture was heated and stirred at 115 °C for 1 hour. To the resulting homogeneous solution, a solution obtained by mixing propionic anhydride (0.185 mol) and decanoic acid (0.111 mol) and heating and stirring at 100 °C for 1 hour under a nitrogen atmosphere, and 0.715 g (0.0059 mol) of 4-dimethylaminopyridine were added, and the mixture was further heated and stirred at 100 °C for 3 hours. The mixed solution was poured into 9000 mL of methanol, and the resulting solid was collected by filtration. The solid was washed with 500 mL of methanol, collected by filtration again, and dissolved in 150 mL of chloroform. The solution was poured into 1600 mL of methanol, and the precipitated solid was collected by filtration. The obtained solid was dried in vacuo at 80 °C to obtain 6.01 g of the product (yield 49%). １ The degree of substitution was determined by the 1H-NMR method.

[0051] (Example 9) 5.0 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in 250 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.95 g (0.0932 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing propionic anhydride (0.185 mol) and myristic acid (0.0925 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.715 g (0.0059 mol) of 4-dimethylaminopyridine were added, and the mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 10,000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 800 mL of methanol, filtered again, and dissolved in 150 mL of chloroform. The solution was poured into 1,600 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to obtain 10.0 g of product (80% yield). １ The degree of substitution was determined by H-NMR.

[0052] (Example 10) 3.5 g of β-1,3-glucan (0.0216 mol in glucose units) was suspended in 200 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 2.76 g (0.0651 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution obtained by mixing butyric anhydride (0.129 mol) and myristic acid (0.0647 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.501 g (0.0041 mol) of 4-dimethylaminopyridine were added, and the mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 2500 mL of methanol, and the resulting solid was filtered off. The solid was washed with 900 mL of methanol, filtered again, and dissolved in 100 mL of chloroform. The solution was poured into 800 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 8.89 g of product (92% yield). １ The degree of substitution was determined by H-NMR.

[0053] (Example 11) 3.0 g of β-1,3-glucan (0.0185 mol in glucose units) was suspended in 150 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 2.37 g of lithium chloride (0.0559 mol) was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing valeric anhydride (0.111 mol) and myristic acid (0.0555 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.429 g of 4-dimethylaminopyridine (0.0035 mol) were added, and the mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 2000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 800 mL of methanol, filtered again, and dissolved in 100 mL of chloroform. The solution was poured into 800 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 8.45 g of product (98% yield). １ The degree of substitution was determined by H-NMR.

[0054] (Comparative Example 1) 5.0 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in 200 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.95 g of lithium chloride (0.0932 mol) was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution prepared by mixing hexanoic anhydride (0.185 mol) and myristic acid (0.0925 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.715 g of 4-dimethylaminopyridine (0.0059 mol) were added, and the mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 1500 mL of methanol, and the resulting solid was filtered off. The solid was washed with 800 mL of methanol, filtered again, and dissolved in 150 mL of chloroform. The solution was poured into 800 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to yield 14.9 g of product (97% yield). １ The degree of substitution was determined by H-NMR.

[0055] (Comparative Example 2) 4.0 g of β-1,3-glucan (0.0247 mol in glucose units) was suspended in 200 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.16 g (0.0745 mol) of lithium chloride was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, a solution obtained by mixing n-octanoic anhydride (0.148 mol) and myristic acid (0.0740 mol) and heating and stirring at 100°C for 1 hour under a nitrogen atmosphere, and 0.572 g (0.00468 mol) of 4-dimethylaminopyridine were added, and the mixture was further heated and stirred at 100°C for 3 hours. The mixed solution was poured into 800 mL of methanol, and the resulting solid was filtered off. The solid was washed with 800 mL of methanol, filtered again, and dissolved in 130 mL of chloroform. The solution was poured into 700 mL of methanol, and the precipitated solid was filtered off. The obtained solid was vacuum-dried at 80°C to obtain 13.3 g of product (100% yield). １ The degree of substitution was determined by H-NMR.

[0056] (Comparative Example 3) 5.0 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in 250 mL of dehydrated N,N-dimethylacetamide under a nitrogen atmosphere, and 3.95 g of lithium chloride (0.0932 mol) was added. The mixture was heated and stirred at 115°C for 1 hour. To the resulting homogeneous solution, 0.185 mol of acetic anhydride and 0.715 g of 4-dimethylaminopyridine (0.0059 mol) were added, and the mixture was heated and stirred at 100°C for 3 hours. The mixed solution was poured into 4000 mL of methanol, and the resulting solid was filtered off. The solid was washed with 800 mL of methanol, filtered again, and dissolved in 200 mL of dichloromethane. The solution was poured into 1600 mL of methanol, and the precipitated solid was filtered off. The resulting solid was vacuum-dried at 80°C to obtain 8.83 g of product (yield 99%). １ The degree of substitution was determined by H-NMR.

[0057] (Comparative Example 4) 7.0 g of β-1,3-glucan (0.0432 mol in glucose units) was suspended in anhydrous pyridine (500 mL) under a nitrogen atmosphere, and pentanoyl chloride (0.130 mol) was added dropwise. The mixture was heated and stirred at 65°C for 3 hours. The resulting homogeneous solution was poured into 1800 mL of water, and the resulting solid was filtered off. The solid was washed twice with 500 mL of methanol, filtered off, and dissolved in 150 mL of chloroform. The solution was poured into 3600 mL of methanol, and the precipitated solid was filtered off. The resulting solid was vacuum-dried at 80°C to obtain 6.86 g of product (yield 54%). １ The degree of substitution was determined by H-NMR.

[0058] (Comparative Example 5) 7.0 g of β-1,3-glucan (0.0432 mol in glucose units) was suspended in anhydrous pyridine (500 mL) under a nitrogen atmosphere, and hexanoyl chloride (0.130 mol) was added dropwise. The mixture was heated and stirred at 65°C for 3 hours. The resulting homogeneous solution was poured into 2000 mL of water, and the resulting solid was filtered off. The solid was washed twice with 500 mL of methanol, filtered off, and dissolved in 150 mL of chloroform. The solution was poured into 900 mL of methanol, and the precipitated solid was filtered off. The same reprecipitation procedure was repeated one more time, and the solid was recovered. The obtained solid was vacuum-dried at 80°C to obtain 12.07 g of product (yield 71%). １ The degree of substitution was determined by H-NMR.

[0059] (Comparative Example 6) 2.0 g of β-1,3-glucanparamylon (0.0123 mol in glucose units) was suspended in anhydrous pyridine (160 mL) under a nitrogen atmosphere, and octanoyl chloride (0.0370 mol) was added dropwise. The mixture was heated and stirred at 65°C for 3 hours. The resulting homogeneous solution was poured into 1000 mL of water, and the resulting solid was filtered off. The solid was washed twice with 500 mL of methanol, filtered off, and dissolved in 40 mL of chloroform. The solution was poured into 300 mL of methanol, and the precipitated solid was filtered off. The same reprecipitation procedure was repeated one more time, and the solid was recovered. The obtained solid was vacuum-dried at 80°C to obtain 3.29 g of product (80% yield). １ The degree of substitution was determined by H-NMR.

[0060] (Comparative Example 7) 5.0 g of β-1,3-glucan (0.0309 mol in glucose units) was suspended in anhydrous pyridine (500 mL) under a nitrogen atmosphere, and decanoyl chloride (0.0925 mol) was added dropwise. The mixture was heated and stirred at 65°C for 3 hours. The resulting homogeneous solution was poured into 2500 mL of water, and the resulting solid was filtered off. The solid was washed twice with 500 mL of methanol, filtered off, and dissolved in 150 mL of chloroform. The solution was poured into 1500 mL of methanol, and the precipitated solid was filtered off. The same reprecipitation procedure was repeated one more time, and after washing with 600 mL of methanol, the solid was recovered. The obtained solid was vacuum-dried at 80°C to obtain 11.7 g of product (yield 86%). １ The degree of substitution was determined by H-NMR.

[0061] [Glass Transition Temperature (Tg)] The glass transition temperature (Tg) was measured as the temperature at which tanδ, obtained by dynamic viscoelasticity measurement, reaches its maximum value. Specifically, using a dynamic viscoelasticity analyzer (EPLEXOR 500N, GABO), a small piece of β-1,3-glucan-substituted material measuring 40 mm in length, 10 mm in width, and 2 mm in thickness was set up with a gripping distance of 20 mm, and measured in tensile mode, frequency 1 Hz, heating rate 5 °C / min, from -120 °C to 200 °C. The storage modulus E' and loss modulus E'' in the range of -120 °C to 200 °C were determined, tanδ was calculated as the ratio of the loss modulus E'' to the storage modulus E', and the glass transition temperature (Tg) was determined as the temperature at which tanδ reaches its maximum value in the range of -120 °C to 200 °C.

[0062] [Storage Modulus] The storage modulus E' was measured in the dynamic viscoelasticity measurement described above.

[0063] [Preparation of resin film for measuring tensile shear adhesive strength] The products obtained in Examples 1 to 11 and Comparative Examples 1 to 7 were placed on a Kapton film, and another Kapton film was placed on top of that. This was then sandwiched between two aluminum plates and heated and pressed at 180°C to 220°C for 5 minutes to produce a resin film with a thickness of approximately 70 μm.

[0064] [Tensile Shear Bonding Strength] The tensile shear bonding strength was measured in accordance with JIS K 6850:1999 (corresponding to ISO 4587) as follows. Two 100 mm x 25 mm x 3 mm aluminum alloy (A6061) pieces were used to sandwich the above resin film, cut to a size of 25 mm x 5 mm (overlap area: 25 mm x 5 mm). This was heated at 180°C to 220°C for 30 minutes, and then cooled in a 23°C environment to obtain a bonding test specimen. The bonding test specimen was held in a universal testing machine (AGS-50NX, Shimadzu Corporation), and a tensile load with displacement control of 1 mm / min was applied to both ends at room temperature. The tensile shear bonding strength was calculated by dividing the load at which the specimen broke by the bonding area.

[0065] [Tensile shear adhesive strength and retention rate after disassembly and re-bonding] The tensile shear adhesive strength and retention rate after disassembly and re-bonding were measured as follows: (1) As described above, the tensile shear adhesive strength of the adhesive test specimen (adhesive test specimen before disassembly and re-bonding) was measured. (2) The adhesive test specimen from (1) was heated in an electric furnace at 180°C for 2 minutes, and immediately after removing the adhesive test specimen from the electric furnace, it was pulled by hand to disassemble the adhesive test specimen. Then, the two disassembled aluminum alloy plates were re-bonded using a simple overlap joint under the same temperature conditions as before disassembly and re-bonding to obtain an adhesive test specimen after disassembly and re-bonding. The tensile shear adhesive strength of the adhesive test specimen after disassembly and re-bonding was measured in the same manner as in (1). (3) The operation in (2) was repeated a total of four times. The retention rate of the tensile shear adhesive strength for each step was calculated as the percentage of the tensile shear adhesive strength after repeating the operation in (2) 0 to 4 times (tensile shear adhesive strength for the 1st to 5th steps) relative to the tensile shear adhesive strength in (1) (tensile shear adhesive strength for the first step). Table 1 shows the retention rates of the tensile shear adhesive strength (tensile shear adhesive strength for the 1st to 5th steps) when the decomposition and re-adhesion were repeated 0 to 4 times in the adhesive test specimens bonded using the β-1,3-glucan substitute of Example 5.

[0066]

[0067] For the adhesives in Examples 1-3, 5-11, and Comparative Examples 1-7, the retention rate of tensile shear adhesive strength after four repeated disassembly and re-adhesion cycles was evaluated as follows: ◎ for 85% or more, ○ for 75% or more but less than 85%, △ for 50% or more but less than 75%, and × for less than 50%.

[0068] The results are shown in Table 2.

[0069]

[0070] As shown in Table 1, adhesives containing β-1,3-glucan-substituted compounds, in which some or all of the hydrogen atoms of the hydroxyl group are substituted using an acyl group having 2 to 5 carbon atoms as substituent 1 and a second acyl group having 6 to 18 carbon atoms as substituent 2, exhibited excellent storage modulus. Furthermore, these adhesives showed a favorable glass transition temperature. In addition, these adhesives exhibited excellent tensile shear bond strength. Furthermore, these adhesives showed excellent retention of tensile shear bond strength.

[0071] Furthermore, the disclosures of patents, patent applications, and publications cited in this disclosure are incorporated herein by reference in their entirety.

[0072] The adhesives of this disclosure can be suitably used for bonding various materials used in the final or intermediate products of industrial goods. Therefore, the present invention has industrial applicability.

Claims

1. An adhesive comprising a β-1,3-glucan-substituted compound in which some or all of the hydrogen atoms of a hydroxyl group are substituted by a first acyl group and a second acyl group, wherein the first acyl group is an acyl group having 2 to 5 carbon atoms, and the second acyl group is an acyl group having 6 to 20 carbon atoms.

2. The adhesive according to claim 1, wherein the degree of substitution of the substituted β-1,3-glucan derivative is 2.0 or more and 3.0 or less.

3. The adhesive according to claim 1 or 2, wherein the glass transition temperature (Tg) is 30°C or higher.

4. The adhesive according to claim 1 or 2, wherein the storage modulus E' at 23°C is 10 MPa or more.

5. The adhesive according to claim 1 or 2, wherein the tensile shear adhesive strength to a metal plate at 23°C is 7.0 MPa or more.

6. The adhesive according to claim 5, wherein the metal plate is an aluminum plate or a steel plate.

7. The adhesive according to claim 1 or 2, wherein the tensile shear adhesive strength to a resin plate at 23°C is 1 MPa or more.

8. The adhesive according to claim 7, wherein the resin plate is a polyamide plate, a polyoxymethylene plate, a polyphenylene ether plate, a polypropylene plate, a polyethylene plate, or a polyethylene terephthalate plate.

9. The adhesive according to claim 1 or 2, which is a structural adhesive for transportation equipment.

10. The adhesive according to claim 1 or 2, which is an easily dismantled adhesive.

11. The adhesive according to claim 1 or 2, which is a hot melt adhesive.

12. The adhesive according to claim 1 or 2, wherein the retention rate of tensile shear adhesive strength when adherends bonded with the adhesive are re-bonded after disassembly is 50% or more.

13. A bonding method comprising bringing the adhesive according to claim 1 or 2 into contact with a material.

14. A method for manufacturing an adhesive bond, comprising bringing the adhesive described in claim 1 or 2 into contact with a material.

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