Easy-to-disassemble adhesive, laminate, method for manufacturing a laminate, and method for recycling a laminate

Abstract

To provide an easily dismantled adhesive that has sufficient bonding strength, exhibits easy dismantling properties, and has excellent adhesive component removal capabilities. [Solution] The easily disassembled adhesive contains a first anthracene derivative represented by formula (I) and a second anthracene derivative represented by formula (II). C(A-R1-O)4(I) AO-(CH2CH2O) n -A(II) (A is an anthracene-containing group, R1 is *-COR2O-** or *-(CH2CH2O)) m -**, where m is an integer from 1 to 50, R2 is a divalent hydrocarbon group with 5 to 20 carbon atoms, and n is an integer from 20 to 150.

Description

[Technical Field]

[0001] This disclosure relates to an easily disassembled adhesive, a laminate, a method for manufacturing a laminate, and a method for recycling a laminate. [Background technology]

[0002] From an environmental perspective, the recyclability of products is required in various fields. For example, in the automotive and electrical / electronic fields, easy disassembly of connecting components is necessary to facilitate recycling. To achieve easy disassembly of joined components, there is a need for easily disassemblable adhesive materials. An easily disassemblable adhesive material is one that possesses both sufficient adhesive strength for its intended use and the property of being able to reduce its adhesive strength at any desired time, allowing for easy peeling (disassembly).

[0003] For example, as an example of an easily disassembled adhesive material, Patent Document 1 discloses an adhesive composition containing a novel anthracene derivative. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-145148 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In order to recycle dismantled components, it is necessary to remove adhesive components adhering to the components. Although the adhesive composition described in Patent Document 1 exhibits high adhesion and ease of dismantling, it may have poor ability to remove adhesive components adhering to the components. This disclosure is made in view of the above-mentioned conventional circumstances and aims to provide an easily disassembled adhesive that has sufficient bonding strength, exhibits easy disassembly, and has excellent adhesive component removal properties, as well as a laminate using this easily disassembled adhesive, a method for manufacturing the laminate, and a method for recycling the laminate. [Means for solving the problem]

[0006] The specific means for achieving the aforementioned objectives are as follows: <1> An easily disassembled adhesive containing a first anthracene derivative represented by general formula (I) and a second anthracene derivative represented by general formula (II).

[0007] [ka]

[0008] (In general formula (I), R1 is *-COR2O-** or *-(CH2CH2O) m -** represents an integer between 1 and 50. R2 represents a divalent hydrocarbon group with 5 to 20 carbon atoms. In R1, * represents the side that bonds with the oxygen atom in general formula (I), and ** represents the side that bonds with A in general formula (I). ** in A indicates the site where it bonds with ** in R1. In general formula (II), n represents an integer between 20 and 150. <2> The transmittance of 405 nm light at an optical path length of 20 μm is 10% or more. <1> The easily dismantled adhesive described above. <3> In general formula (I), R1 represents *-COR2O-**, and R2 represents a divalent hydrocarbon group with 8 to 12 carbon atoms. <1> or <2> The easily dismantled adhesive described above. <4> In general formula (I), R1 is *-(CH2CH2O) m -** represents a value where m represents an integer between 2 and 20. <1> or <2> The easily dismantled adhesive described above. <5> In general formula (II), n represents an integer between 40 and 100. <1> ~ <4> An easy-to-disassemble adhesive as described in any one of the items. <6> When X is the number of anthracene residues derived from the first anthracene derivative contained in the easily disassembled adhesive, and Y is the number of anthracene residues derived from the second anthracene derivative contained in the easily disassembled adhesive, the value expressed as Y / (X+Y) is in the range of 0.01 to 0.7. <1> ~ <5> An easy-to-disassemble adhesive as described in any one of the items. <7> The content of the first anthracene derivative in relation to the total amount of the first and second anthracene derivatives is 10% to 95% by mass. <1> ~ <6> An easy-to-disassemble adhesive as described in any one of the items. <8> An easily disassembled adhesive containing at least one anthracene derivative having at least two anthracene residues in one molecule, and satisfying conditions (1)-(3). (1) When the easy-to-disassemble adhesive is placed between a pair of quartz plates and the easy-to-disassemble adhesive is cured by irradiating it with light of 350 nm to 450 nm to bond the pair of quartz plates, the shear peel strength between the quartz plates is 50 kPa or more. (2) After heating the bonded pair of quartz plates at 150°C for 10 minutes, the shear peel strength between the quartz plates is less than 10 kPa. (3) When the hardened material of the easily dismantled adhesive, which has been cured under the conditions of (1), is heated to reduce the shear peel strength between the quartz plates to less than 10 kPa, and the quartz plates with the residue of the hardened material attached are immersed in 60°C hot water for 10 minutes, the hot water peel rate of the easily dismantled adhesive before and after immersion is greater than 0%. <9> The first base material and <1> ~ <8> A laminate comprising, in this order, an adhesive layer containing a cured product of an easily disassembled adhesive as described in any one of the items, and a second substrate. <10> The light transmittance at 405 nm with an optical path length of 20 μm for at least one of the first substrate and the second substrate is 10% or more. <9> The laminate described above. <11> Between the first substrate and the second substrate <1> ~ <8> A step of applying an easy-to-disassemble adhesive as described in any one of the items, The process involves irradiating the applied easy-to-dismantle adhesive with light of 350 nm to 450 nm, Method for manufacturing a laminate having the same. <12> Heating the laminate according to <9> or <10> to reduce the shear peel strength of the adhesive layer; Separating the first substrate and the second substrate; Immersing at least one of the separated first substrate and the second substrate in warm water; Recycling method for a laminate having the same.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide an easily disassembling adhesive having sufficient bonding strength, exhibiting easy disassembly properties, and excellent in the removability of the adhesive component, as well as a laminate using this easily disassembling adhesive, a method for manufacturing the laminate, and a recycling method for the laminate.

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments according to the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present disclosure.

[0011] In the present disclosure, the term "step" includes, in addition to steps independent of other steps, those steps that are not clearly distinguishable from other steps but whose purpose is achieved. In the numerical range indicated by "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another stepwise numerical range. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified. In this disclosure, the terms “layer” or “film” include cases where, when the region in which the layer or film exists is observed, it is formed not only over the entire region but also over only a portion of the region. In this disclosure, the term "lamination" refers to stacking layers, and two or more layers may be bonded together or detachable. In this disclosure, "(meth)acrylic" means at least one of acrylic and methacrylic. In this disclosure, "solids" means the components remaining after removing volatile components such as solvents from the easily dismantled adhesive.

[0012] <Easy-to-dismantle adhesive> The first easily dismantled adhesive of this disclosure contains a first anthracene derivative represented by general formula (I) and a second anthracene derivative represented by general formula (II).

[0013] [ka]

[0014] In general formula (I), R1 is *-COR2O-** or *-(CH2CH2O) m -** represents an integer between 1 and 50. R2 represents a divalent hydrocarbon group with 5 to 20 carbon atoms. In R1, * represents the side that bonds with the oxygen atom in general formula (I), and ** represents the side that bonds with A in general formula (I). ** in A indicates the site where it bonds with ** in R1. In general formula (II), n represents an integer between 20 and 150.

[0015] The first easily dismantled adhesive of this disclosure has sufficient bonding strength, exhibits easy dismantling properties, and has excellent adhesive component removal properties. The reason for this is not clear, but it is presumed to be as follows. Anthracene can form an anthracene dimer as a result of a [4+4] cyclization reaction induced by ultraviolet irradiation. On the other hand, it is possible to convert the anthracene dimer back into anthracene (anthracene monomer) by irradiating it with ultraviolet light at a wavelength of 300 nm or less, or by heating the anthracene dimer. The reversible reaction between the anthracene dimer and the anthracene monomer is utilized to realize its function as an easily disassembled adhesive. The first easily disassembled adhesive of this disclosure contains a first anthracene derivative containing four anthracene residues in one molecule, and is therefore presumed to be able to exhibit sufficient bonding strength. Furthermore, it is presumed that the easily disassembled properties are achieved through a conversion reaction from anthracene dimer to anthracene monomer. On the other hand, as a result of diligent research, the inventors have found that by using a second anthracene derivative in combination with the first anthracene derivative, the easily dismantled adhesive component, when immersed in hot water, can be easily removed from the adhered material. From the above, it is inferred that the first easily dismantled adhesive of this disclosure has sufficient bonding strength, exhibits easy dismantling properties, and has excellent adhesive component removal properties.

[0016] Furthermore, the second easily disassembled adhesive of this disclosure contains at least one anthracene derivative having at least two anthracene residues in one molecule, and satisfies conditions (1)-(3). (1) When the easy-to-disassemble adhesive is placed between a pair of quartz plates and the easy-to-disassemble adhesive is cured by irradiating it with light of 350 nm to 450 nm to bond the pair of quartz plates, the shear peel strength between the quartz plates is 50 kPa or more. (2) After heating the bonded pair of quartz plates at 150°C for 10 minutes, the shear peel strength between the quartz plates is less than 10 kPa. (3) When the hardened material of the easily dismantled adhesive, which has been cured under the conditions of (1), is heated to reduce the shear peel strength between the quartz plates to less than 10 kPa, and the quartz plates with the residue of the hardened material attached are immersed in 60°C hot water for 10 minutes, the hot water peel rate of the easily dismantled adhesive before and after immersion is greater than 0%. The components constituting the second easily disassembled adhesive of this disclosure are not particularly limited and may include the first anthracene derivative and the second anthracene derivative described below, and may also include other components described below. In the second easily disassembled adhesive of this disclosure, the shear peel strength between quartz plates and the hot water peel rate of the easily disassembled adhesive are values ​​measured by the method described in the examples below. The first and second easy-to-disassemble adhesives of this disclosure may together be referred to as the easy-to-disassemble adhesives of this disclosure.

[0017] The following describes in detail each component that makes up the easily disassembled adhesive of this disclosure. The first easily dismantled adhesive of this disclosure contains a first anthracene derivative and a second anthracene derivative, and may optionally contain other components described below, to the extent that they do not impair the effects of this disclosure.

[0018] (First anthracene derivative) The first anthracene derivative used in this disclosure is a compound represented by general formula (I). In general formula (I), R1 is *-COR2O-** or *-(CH2CH2O) m -** represents. Hereinafter, the first anthracene derivative in which R1 is *-COR2O-** will be referred to as the first embodiment of the first anthracene derivative, and R1 is *-(CH2CH2O) m -** The first anthracene derivative is sometimes referred to as the second embodiment of the first anthracene derivative.

[0019] If R1 in general formula (I) is *-COR2O-**, then R2 in the four *-COR2O-** in general formula (I) may be the same or different, but it is preferable that they be the same. In *-COR2O-**, R2 represents a divalent hydrocarbon group having 5 to 20 carbon atoms. The number of carbon atoms in the divalent hydrocarbon group represented by R2 is preferably 7 to 15, and more preferably 8 to 12. The divalent hydrocarbon group with 5 to 20 carbon atoms represented by R2 is not particularly limited. Examples of divalent hydrocarbon groups with 5 to 20 carbon atoms represented by R2 include linear alkylene groups such as pentamethylene, hexamethylene, decamethylene, dodecamethylene, and eicosamethylene, and among these, decamethylene is preferred.

[0020] The R1 in general formula (I) is *-(CH2CH2O) m -** If this is the case, then the four *-(CH2CH2O) included in general formula (I) m In -**, m may be the same or different, but it is preferable that it be the same. *-(CH2CH2O) m In -**, m represents an integer between 1 and 50, preferably between 2 and 20, more preferably between 2 and 10, even more preferably between 2 and 8, and particularly preferably between 2 and 5.

[0021] The anthracene residue represented by formula A in general formula (I) may or may not have substituents. Examples of substituents include alkyl groups, alkoxy groups, amino groups, and dialkylamino groups. From the viewpoint of bonding strength, the anthracene residue is preferably unsubstituted.

[0022] In the first aspect of the first anthracene derivative, R2 in *-COR2O-* represented by R1 is a linear alkylene group having 7 to 15 carbon atoms, and the anthracene residue represented by formula A is preferably unsubstituted. More preferably, R2 in *-COR2O-* represented by R1 is a linear alkylene group having 8 to 12 carbon atoms, and the anthracene residue represented by formula A is unsubstituted. In the second aspect of the first anthracene derivative, m in *-(CH2CH2O) m -* is an integer from 1 to 8, and the anthracene residue represented by formula A is preferably unsubstituted. More preferably, m in *-(CH2CH2O) m -* is an integer from 2 to 5, and the anthracene residue represented by formula A is unsubstituted.

[0023] The first anthracene derivative may be used alone or in combination of two or more.

[0024] (Second anthracene derivative) The second anthracene derivative used in the present disclosure is a compound represented by general formula (II). In general formula (II), n represents an integer from 20 to 150, and may be an integer from 40 to 100. Also, in general formula (II), n may be an integer from 20 to 30 in the first aspect, may be an integer greater than 30 and not exceeding 60 in the second aspect, may be an integer greater than 60 and not exceeding 100 in the third aspect, and may be greater than 100 and not exceeding 150 in the fourth aspect. Hereinafter, a second anthracene derivative in which n in general formula (II) is an integer between 20 and 30 will be referred to as the first embodiment of the second anthracene derivative, a second anthracene derivative in which n in general formula (II) is an integer greater than 30 and less than or equal to 60 will be referred to as the second embodiment of the second anthracene derivative, a second anthracene derivative in which n in general formula (II) is an integer greater than 60 and less than or equal to 100 will be referred to as the third embodiment of the second anthracene derivative, and a second anthracene derivative in which n in general formula (II) is an integer greater than 100 and less than or equal to 150 will be referred to as the fourth embodiment of the second anthracene derivative. When the second anthracene derivative is the first embodiment, n is preferably an integer between 20 and 25, and more preferably an integer between 21 and 24. When the second anthracene derivative is the second embodiment, n is preferably an integer between 35 and 55, and more preferably an integer between 40 and 50. When the second anthracene derivative is the third embodiment, n is preferably an integer between 65 and 90, and more preferably an integer between 70 and 80. When the second anthracene derivative is the fourth embodiment, n is preferably an integer between 110 and 145, and more preferably an integer between 120 and 140.

[0025] The anthracene residue represented by formula A in general formula (II) may or may not have substituents. Examples of substituents include alkyl groups, alkoxy groups, amino groups, and dialkylamino groups. From the viewpoint of bonding strength, the anthracene residue is preferably unsubstituted.

[0026] (Ratio of anthracene residues) When X is the number of anthracene residues derived from the first anthracene derivative contained in the first easily disassembled adhesive, and Y is the number of anthracene residues derived from the second anthracene derivative contained in the first easily disassembled adhesive, the value expressed as Y / (X+Y) (ratio of anthracene residues) may be appropriately set depending on the types of the first and second anthracene derivatives, for example, it may be in the range of 0.01 to 0.7, 0.1 to 0.5, or 0.2 to 0.4.

[0027] The preferred ratio of anthracene residues may be within the following range, depending on the combination of the first anthracene derivative and the second anthracene derivative. In the case of a combination of the first embodiment of the first anthracene derivative and the first embodiment of the second anthracene derivative, the ratio of anthracene residues is preferably 0.05 to 0.7, more preferably 0.08 to 0.4, and even more preferably 0.1 to 0.3. In the case of a combination of the first embodiment of the first anthracene derivative and the second embodiment of the second anthracene derivative, the ratio of anthracene residues is preferably 0.05 to 0.7, more preferably 0.08 to 0.5, and even more preferably 0.15 to 0.35. In the case of a combination of the first embodiment of the first anthracene derivative and the third embodiment of the second anthracene derivative, the ratio of anthracene residues is preferably 0.03 to 0.7, more preferably 0.08 to 0.6, and even more preferably 0.1 to 0.5. In the case of a combination of the first embodiment of the first anthracene derivative and the fourth embodiment of the second anthracene derivative, the ratio of anthracene residues is preferably 0.03 to 0.18, more preferably 0.08 to 0.15, and even more preferably 0.09 to 0.12. In the case of a combination of the second embodiment of the first anthracene derivative and the first embodiment of the second anthracene derivative, the ratio of anthracene residues is preferably 0.1 to 0.5, more preferably 0.2 to 0.4, and even more preferably 0.25 to 0.35. In the case of a combination of the second aspect of the first anthracene derivative and the second aspect of the second anthracene derivative, the ratio of anthracene residues is preferably 0.05 to 0.5, preferably 0.15 to 0.45, and more preferably 0.25 to 0.45. In the case of a combination of the second aspect of the first anthracene derivative and the third aspect of the second anthracene derivative, the ratio of anthracene residues is preferably 0.05 to 0.3, more preferably 0.08 to 0.4, and even more preferably 0.1 to 0.3.

[0028] (Transmittance of 405nm light) In the first easily disassembled adhesive, the transmittance of 405 nm light at a path length of 20 μm is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. A higher transmittance of 405 nm light is preferable, with an upper limit of 100%. The inventors have found that depending on the type and content ratio of the first and second anthracene derivatives contained in the first easily disassembled adhesive, turbidity may occur in the first easily disassembled adhesive, which may impair the photocurability of the easily disassembled adhesive upon light irradiation. In the easily disassembled adhesive, if the transmittance of 405 nm light at a path length of 20 μm is 10% or more, sufficient photocurability of the easily disassembled adhesive can be ensured.

[0029] In this disclosure, the transmittance of 405 nm light at an optical path length of 20 μm refers to the value measured by the following method. (Measurement device for 405 nm light transmittance at an optical path length of 20 μm) The 405 nm light transmittance at a path length of 20 μm is measured using a JASCO V-730 spectrophotometer, detecting the transmittance T% at a fixed wavelength of 405 nm. (Method for preparing a sample for measuring light transmittance at 405 nm with an optical path length of 20 μm) A sample for measurement is prepared by sandwiching two quartz plates, each measuring 76 mm in length, 26 mm in width, and 1 mm in thickness, between which an adhesive, pre-mixed in a predetermined ratio, is applied, ensuring no air bubbles are present. The thickness of the adhesive layer is then adjusted so that the optical path length is 20 μm. The thickness and transmittance of the two quartz plates alone are measured beforehand and used as blank values ​​for thickness and transmittance, respectively. (Method for calculating the thickness of the adhesive layer in a sample for measurement) Using only the thickness blank values ​​of the two quartz plates described in the method for preparing the sample for measurement, the thickness of the adhesive layer is calculated using the following formula (I). Adhesive layer thickness = Thickness of the sample for measurement - Blank value (thickness of only the two quartz plates) Equation (I) (Method for calculating light transmittance at 405nm) Since the two quartz plates themselves have 405 nm light absorption, the transmittance of the adhesive layer alone (i.e., the transmittance of 405 nm light at a path length of 20 μm) is calculated using the blank value of the 405 nm light transmittance mentioned above, and the following formula (II). Transmittance of the adhesive layer only (%) = Transmittance of the sample used for measurement + (100 (%) - Transmittance blank value) Equation (II) The optical path length L satisfies the relationship L = d / sinθ, where d is the thickness of the adhesive layer and θ is the angle of incidence of the light used for transmittance measurement. When measuring transmittance, the incident angle θ should be 90°.

[0030] (Anklene derivative content ratio) The content ratio of the first anthracene derivative and the second anthracene derivative contained in the first easily disassembled adhesive of this disclosure is preferably set such that the transmittance of 405 nm light at an optical path length of 20 μm of the easily disassembled adhesive is 10% or more. In the first easily disassembled adhesive of the present disclosure, the content of the first anthracene derivative in relation to the total amount of the first anthracene derivative and the second anthracene derivative may be 10% to 95% by mass, 20% to 80% by mass, or 30% to 70% by mass.

[0031] (Other ingredients) The easily dismantled adhesive of this disclosure may contain other components besides the first anthracene derivative and the second anthracene derivative. Other components include conventionally known additives such as antistatic agents, antioxidants, leveling agents, rheology control agents, colorants, fillers, anti-aging agents, UV absorbers, and functional dyes. If the easily dismantled adhesive of this disclosure contains other components, the content of the other components in the solid content of the easily dismantled adhesive is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0032] From the viewpoint of coating properties, the easily dismantled adhesive of this disclosure preferably has a viscosity of 1 mPa·s to 500,000 mPa·s at 25°C, and more preferably 2 mPa·s to 400,000 mPa·s.

[0033] The easily dismantled adhesive of this disclosure may contain a solvent from the viewpoint of coating properties. If the easily dismantled adhesive of this disclosure contains a solvent, the viscosity of the easily dismantled adhesive at 25°C in the solvent-containing state is preferably within the range described above. Examples of solvents include various organic solvents such as ketone solvents, alcohol solvents, and aromatic solvents. More specifically, examples include methyl ethyl ketone, cyclohexene, ethylene glycol, propylene glycol, methyl alcohol, isopropyl alcohol, butanol, benzene, toluene, xylene, ethyl acetate, and butyl acetate. One solvent may be used alone, or two or more solvents may be used in combination. If the easily dismantled adhesive of this disclosure contains a solvent, the solvent content is not particularly limited, and the solvent content may be adjusted so that the viscosity of the easily dismantled adhesive at 25°C falls within the range described above.

[0034] The easily dismantled adhesive of this disclosure can be obtained by stirring and mixing the above-mentioned components according to known methods.

[0035] <Laminate> The laminate of the present disclosure comprises, in this order, a first substrate, an adhesive layer containing a cured product of the easily disassembled adhesive of the present disclosure, and a second substrate. The laminate of this disclosure has sufficient bonding strength and exhibits easy disassembly because the first substrate and the second substrate are bonded together by the cured product of the easy-to-disassemble adhesive of this disclosure. The details of the substrates and other components constituting the laminate are described below. The laminate of this disclosure may have a first substrate, a second substrate, and other layers other than the adhesive layer. Examples of other layers include a primer layer, a surface modification layer, a conductive layer, and a fluorescent dye layer for detecting the residue of the adhesive layer.

[0036] (base material) The materials of the first and second substrates constituting the laminate of this disclosure are not particularly limited, and conventionally known materials can be used. Examples of materials for the first and second substrates include plastics, glass, metals, and the like. From the viewpoint of easily curing the easily disassembled adhesive applied between the first substrate and the second substrate by light irradiation, it is preferable that the light transmittance at 405 nm with a path length of 20 μm for at least one of the first substrate and the second substrate be 10% or more, and more preferably 20% or more. The light transmittance at an optical path length of 20 μm for the first and second substrates is determined by preparing measurement samples of the same material as the first and second substrates with a thickness of 20 μm, and detecting the transmittance T% of the obtained 20 μm thick measurement samples using the above-described measuring device. Examples of materials with a light transmittance of 10% or more at 405 nm in an optical path length of 20 μm include plastics and glass. Examples of plastics include polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyolefins such as polypropylene and polyethylene; polyamides; polycarbonates; and poly(meth)acrylic resins. Examples of glass include alkali glass, alkali-free glass, and quartz glass.

[0037] The shape of the substrate is not particularly limited and can include films, sheets, plates, and various three-dimensional shapes. The thickness of the substrate is not particularly limited and is set appropriately, taking into account the light transmittance of the substrate. Surface treatment may be applied to the surface of the substrate to improve adhesion and other properties. Examples of surface treatments include corona treatment and surface abrasion treatment. If a primer layer or surface modification layer is provided on the surface of the substrate, the above-mentioned surface treatment may be applied to the surface of these layers.

[0038] (adhesive layer) The adhesive layer constituting the laminate of the present disclosure includes a cured product of the easily disassembled adhesive of the present disclosure. The thickness of the adhesive layer is not particularly limited as long as it is sufficient to ensure sufficient adhesive strength between the first substrate and the second substrate. The thickness of the adhesive layer is preferably 1 μm to 10 mm, more preferably 2 μm to 5 mm, and even more preferably 5 μm to 2 mm.

[0039] <Method for manufacturing laminates> A method for manufacturing a laminate according to the present disclosure comprises the steps of: applying the easily disassembled adhesive of the present disclosure between a first substrate and a second substrate (hereinafter sometimes referred to as the application step); and irradiating the applied easily disassembled adhesive with light of 350 nm to 450 nm (hereinafter sometimes referred to as the irradiation step). By irradiating the easily disassembled adhesive of this disclosure, applied between the first substrate and the second substrate, with light of 350 nm to 450 nm, a dimerization reaction occurs between the anthracene residues constituting the first anthracene derivative and the second anthracene derivative, causing the easily disassembled adhesive to harden. The hardening of the easily disassembled adhesive adheres the first substrate and the second substrate together, producing a laminate. The details of each step included in the method for manufacturing the laminate are described below. The method for manufacturing the laminate according to this disclosure may include other steps besides the impregnation step and the irradiation step.

[0040] (Granting process) In the application step, the easily disassembled adhesive of the present disclosure is applied between the first substrate and the second substrate. The application step may, for example, involve applying a liquid easily disassembled adhesive to at least one of the first substrate and the second substrate, removing the solvent contained in the easily disassembled adhesive by heating or other means as necessary, and bonding the first substrate and the second substrate together via the applied easily disassembled adhesive.

[0041] The method of applying the easy-to-disassemble adhesive is not particularly limited, and commonly used known methods can be used. Specifically, these include the roll coating method, bar coating method, dip coating method, spin coating method, casting method, die coating method, blade coating method, gravure coating method, curtain coating method, spray coating method, and doctor coating method.

[0042] If necessary, solvent removal methods can be used, such as drying at room temperature (e.g., 25°C), heating, or vacuum drying. For heating or vacuum drying, a hot plate, hot air dryer, hot air heating furnace, infrared dryer, infrared heating furnace, far-infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating device, steam heating furnace, etc. The temperature and time for drying can be adjusted as appropriate according to the type and amount of solvent used. For example, it is preferable to dry at 40°C to 180°C for 1 to 120 minutes.

[0043] One method for bonding the first substrate and the second substrate via an easily disassembled adhesive is to bond them by pressure. The method of pressure bonding the first substrate and the second substrate is not particularly limited; for example, a machine may be used, or the bonding may be done by hand.

[0044] (irradiation process) In the irradiation process, light in the 350nm to 450nm range is irradiated onto the easily disassembled adhesive applied between the first substrate and the second substrate. The light source used in the irradiation process is not particularly limited. For example, high-pressure mercury lamps, electrodeless lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, black lights, and LED lamps can be used.

[0045] The integrated light intensity during the irradiation process is not particularly limited. From the viewpoint of ensuring adhesive strength, the integrated light intensity should be 10 mJ / cm². 2 The above is preferable, and 100 mJ / cm² is preferred. 2 The above is more preferable, with 1,000 mJ / cm² being preferable. 2 The above is even more preferable. The integrated light intensity is 50,000 mJ / cm² from the viewpoint of the productivity of the laminate. 2 The following is preferable: 40,000 mJ / cm² 2 The following is more preferable: 35,000 mJ / cm² 2 The following is even more preferable: The integrated light intensity is 10 mJ / cm². 2 ~50,000 mJ / cm 2 That's fine.

[0046] <Recycling methods for laminated materials> The method for recycling a laminate according to the present disclosure comprises: a step of heating the laminate according to the present disclosure to reduce the shear peel strength of the adhesive layer (hereinafter sometimes referred to as the heating step); a step of separating the first substrate and the second substrate (hereinafter sometimes referred to as the separation step); and a step of immersing at least one of the separated first substrate and the second substrate in hot water (hereinafter sometimes referred to as the immersion step). When the laminate undergoes a heating process, the anthracene dimer is converted back into anthracene monomer. This conversion regenerates the first and second anthracene derivatives within the adhesive layer, reducing the shear peel strength of the adhesive layer. Therefore, it becomes easier to separate the first and second substrates during the separation process. Furthermore, the second anthracene derivative regenerated in the adhesive layer has a polyoxyethylene structure (-(CH2CH2O) mBecause it has the property of being soluble in hot water, it has excellent swelling or solubility. Therefore, the adhesive layer is easily removed from the first or second substrate by swelling or dissolution through the immersion process. Based on the above, it is presumed that the laminate recycling method described herein is excellent in removing adhesive components. The details of each step included in the laminate recycling method are described below. The method for manufacturing the laminate according to this disclosure may include other steps besides the heating step, separation step, and immersion step.

[0047] (Heating process) In the heating step, the laminate is heated. The heating temperature should be above the temperature at which the anthracene dimer is converted to anthracene monomer. Specifically, for example, 80°C or higher is preferred, more preferably 100°C or higher, even more preferably 120°C or higher, and particularly preferably 130°C or higher. To suppress thermal degradation of the first and second substrates, the heating temperature is preferably 150°C or lower. A heating temperature of 80°C to 150°C is particularly preferred. The heating time varies depending on the heating method and temperature, but is preferably 2 seconds or more, more preferably 2 seconds to 1 hour, even more preferably 3 seconds to 30 minutes, and particularly preferably 4 seconds to 10 minutes. If the heating time is within the above range, the shear peel strength of the adhesive layer can be sufficiently reduced.

[0048] The heating method for the laminate is not particularly limited, and can be a hot plate, hot air heater, infrared heater, far infrared heater, microwave heater, laser heater, electromagnetic heater, heater heater, steam heater, etc., and can be selected as appropriate in light of the heating temperature and heating time.

[0049] (separation process) In the separation process, the laminate that has undergone the heating process is separated into a first substrate and a second substrate. Because the shear peel strength of the adhesive layer is reduced after the heating process, the first and second substrates can be easily separated. In addition, by separating the first and second substrates, the adhesive layers remaining on the first and second substrates are more easily exposed to hot water in the subsequent immersion process. The method for separating the first substrate and the second substrate is not particularly limited; they may be separated mechanically or manually.

[0050] (Soaking process) In the immersion process, the separated first and second substrates are immersed in hot water. The temperature of the hot water is not particularly limited, but is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher. The temperature of the hot water may be 60°C or lower from the viewpoint of the heat distortion temperature of the recovered substrate or the suppression of hydrolysis. The temperature of the hot water is preferably between 40°C and 60°C. The immersion time is not particularly limited, but is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more. From the viewpoint of preventing contamination of the recovered substrate, the immersion time may be 10 minutes or less. The immersion time is preferably 1 to 10 minutes.

[0051] The hot water may or may not contain additives such as surfactants and inorganic salts to promote the peeling of the adhesive layer.

[0052] During the immersion process, the hot water may be in flow. Methods for imparting fluidity to the hot water include stirring the hot water with an agitator or the like, continuously flowing hot water supplied from a water heater, and creating a hot water flow in the bathtub using a circulation pump or the like.

[0053] The first and second substrates, after undergoing the immersion process, can be recycled as recycled materials by undergoing drying processes or other necessary steps as needed. [Examples]

[0054] The following examples will provide a more detailed description of the easily disassembled adhesive, laminate, method for manufacturing the laminate, and method for recycling the laminate according to this disclosure. The materials, amounts used, proportions, processing procedures, etc., shown in the following examples can be modified as appropriate, as long as they do not deviate from the spirit of this disclosure. Therefore, the scope of the easily disassembled adhesive, laminate, method for manufacturing the laminate, and method for recycling the laminate according to this disclosure should not be interpreted as being limited by the following specific examples.

[0055] <Synthesis of Anthracene Derivative A> (Synthesis of anthracene derivative A precursor) 38.7 g of 11-bromoundecanoic acid manufactured by Tokyo Chemical Industry Co., Ltd., 3.8 g of pentaerythritol manufactured by Tokyo Chemical Industry Co., Ltd., and 1.5 g of p-toluenesulfonic acid monohydrate manufactured by Fujifilm Wako Co., Ltd. were placed in a reaction vessel and heated and stirred at 60°C for 10 minutes, then at 120°C for 6 hours. After the reaction, the reaction vessel was cooled to 25°C and the product became a white solid. 100 ml of methanol manufactured by Fujifilm Wako Co., Ltd. was added and the mixture was stirred and washed. After methanol washing, the resulting white solid suspension was filtered and then dried in a vacuum dryer at 25°C for 12 hours to obtain 30.2 g of anthracene derivative A precursor.

[0056] (Synthesis of anthracene derivative A) To 28.0 g of the anthracene derivative A precursor obtained as described above, 28.2 g of anthracene-9-carboxylic acid from Tokyo Chemical Industry Co., Ltd., 17.2 g of potassium carbonate from Fujifilm Wako Co., Ltd., 4.2 g of sodium iodide from Fujifilm Wako Co., Ltd. as a catalyst, and 500 ml of acetone from Fujifilm Wako Co., Ltd. as a solvent were placed in a reaction vessel equipped with a reflux condenser and stirred at 25°C for 10 minutes. The reaction was then continued for 24 hours with heating under reflux at 60°C. After the reaction, the potassium salt was filtered and the acetone was removed by distillation to obtain 6.9 g of the target product, anthracene derivative A.

[0057] <Synthesis of Anthracene Derivative B> (Synthesis of anthracene derivative B precursor) In a reaction vessel equipped with a reflux condenser and a gas exhaust pipe, 10.0 g of Aldrich pentaerythritol tetraethoxylate (15 / 4 EO / OH), 200 ml of Fujifilm Wako chloroform, and 1 ml of Fujifilm Wako pyridine were added and dissolved at 25°C while a small amount of dry nitrogen was flowed through. Next, 12 ml of thionyl chloride was gradually added over 30 minutes. After the addition of thionyl chloride, the reaction solution was heated to 70°C and the reaction was continued for 5 hours. After the reaction, 50 ml of saturated sodium bicarbonate aqueous solution was added to the reaction solution to neutralize it, and the separated aqueous layer was removed. Chloroform was removed from the remaining organic layer by distillation to obtain 10.9 g of anthracene derivative B precursor.

[0058] (Synthesis of anthracene derivative B) As described above, 10 g of anthracene derivative B precursor, 10 g of anthracene-9-carboxylic acid from Tokyo Chemical Industry Co., Ltd., 6.4 g of potassium carbonate from Fujifilm Wako Co., Ltd., 0.8 g of sodium iodide from Fujifilm Wako Co., Ltd., and 300 ml of acetone from Fujifilm Wako Co., Ltd. were placed in a reaction vessel and heated and stirred at 25°C for 30 minutes, then at 60°C for 24 hours. After the reaction, the potassium salt was filtered off and the acetone was removed by distillation to obtain 13.5 g of the target product, anthracene derivative B.

[0059] <Synthesis of Anthracene Derivatives 2-5> (Synthesis of Anthracene Derivative 2-5 Precursors) Four different molecular weight anthracene derivative precursors, 2-5, were synthesized by reacting polyethylene glycol of the brands shown in Table 1 with each reagent.

[0060] [Table 1]

[0061] (Synthesis procedure) 10 g of each polyethylene glycol, 1 ml of pyridine, and 200 ml of chloroform were placed in a reaction vessel equipped with a reflux condenser and exhaust pipes for the generated hydrogen chloride and sulfur dioxide, and dissolved at 25°C while a small amount of dry nitrogen was circulated. 3.8 g of thionyl chloride manufactured by Fujifilm Wako was added, and the mixture was heated to 70°C under reflux for 8 hours. 50 ml of saturated sodium bicarbonate aqueous solution was added to stop the reaction, and the separated aqueous layer was removed. Chloroform was removed from the remaining organic layer by distillation to obtain the crude product of the anthracene derivative 2-5 precursor, which is a chlorinated compound at both ends of polyethylene glycol. A white solid was obtained by washing this crude product with 100 ml of diethyl ether. The solid was recovered by filtration and dried under reduced pressure at 25°C for 12 hours to obtain the anthracene derivative 2-5 precursor. Furthermore, diethylene glycol bis(2-chloroethyl) ether manufactured by Tokyo Chemical Industries was used as the anthracene derivative 1 precursor.

[0062] (Synthesis of anthracene derivatives 1-5) The anthracene derivative 1-5 precursors prepared as described above were reacted with the reagents listed in Table 2 below to synthesize five different anthracene derivatives 1-5 with varying molecular weights.

[0063] [Table 2]

[0064] (Synthesis procedure) The amounts of anthracene derivative 1-5 precursor, anthracene-9-carboxylic acid manufactured by Tokyo Chemical Industry Co., Ltd., potassium carbonate manufactured by Fujifilm Wako Co., Ltd., potassium iodide manufactured by Fujifilm Wako Co., Ltd., and N,N-dimethylformamide (DMF) manufactured by Fujifilm Wako Co., Ltd. were placed in a reaction vessel and heated and stirred at 25°C for 10 minutes, followed by heating at 100°C for 24 hours. After the reaction, the potassium salt was filtered and the DMF was removed by distillation to obtain the target product, anthracene derivative 1-5.

[0065] <Preparation of easily dismantled adhesive> The anthracene derivatives A and B and anthracene derivatives 1-5 obtained as described above were weighed so that the combination of anthracene derivative A and anthracene derivative 1-5 was in the amount shown in Table 3, and the combination of anthracene derivative B and anthracene derivative 2-4 was in the amount shown in Table 4. These were then mixed using a spatula in a 20 ml glass vial placed on a hot plate set to 60°C to prepare an easily disassembled adhesive. The units for the amounts of anthracene derivatives A and B, and anthracene derivatives 1-5 in Table 3-4 are mg.

[0066] [Table 3]

[0067] [Table 4]

[0068] [evaluation] The following evaluations were performed using the easily disassembled adhesive obtained.

[0069] <Transmittance of 405nm light at a path length of 20μm> The permeability of the easily dismantled adhesive was measured using the following method. (Measurement device for 405 nm light transmittance at an optical path length of 20 μm) The transmittance at 405 nm with an optical path length of 20 μm was measured using a JASCO V-730 spectrophotometer, detecting the transmittance T% at a fixed wavelength of 405 nm. (Method for preparing a sample for measuring light transmittance at 405 nm with an optical path length of 20 μm) An adhesive containing either or both of the first anthracene derivative represented by general formula (I) and the second anthracene derivative represented by general formula (II) was applied to a Misumi quartz slide glass (26 mm wide x 76 mm long x 1 mm thick), ensuring no air bubbles were present. The adhesive layer thickness was adjusted to achieve an optical path length of 20 μm to prepare the sample for measurement. The thickness and transmittance of the two quartz slide glass slides alone were measured beforehand and used as blank values ​​for thickness and transmittance, respectively. (Method for calculating the thickness of the adhesive layer in a sample for measurement) Using only the thickness blank values ​​of the two quartz glass slides described in the sample preparation method for measurement, the thickness of the adhesive layer was calculated using the following formula (I). Adhesive layer thickness = Thickness of the sample for measurement - Blank value (thickness of only two quartz glass slides) Equation (I) (Method for calculating light transmittance at 405nm) Since light absorption at 405 nm exists in both quartz glass slides, the transmittance of the adhesive layer alone (i.e., the transmittance of 405 nm light at a path length of 20 μm) was calculated using the blank value for 405 nm light transmittance described in the sample preparation method, and the following formula (II). Transmittance of the adhesive layer only (%) = Transmittance of the sample used for measurement + (100 (%) - Transmittance blank value) Equation (II) The transmittance (%) of the adhesive layer alone was defined as the transmittance at 405 nm.

[0070] <Shear peeling evaluation> A quartz microscope slide (26mm wide x 76mm long x 1mm thick) manufactured by Misumi was coated with 20mg of adhesive at the 10mm tip of one side, and a quartz plate of the same size was bonded to it to create a test specimen. The specimen was irradiated with a Contac LED lamp (wavelength 405nm) at a distance of 10mm for 5 minutes to perform photocuring bonding. This specimen was gripped by the air chuck of an Orientec Tensilon model RTE-1210 tensile testing machine equipped with a 50N load cell, and a tensile test was performed at a pulling speed of 5mm per minute. The maximum point load (unit = N) in the stress-elongation curve obtained from the test was determined, and the bonded area was 260mm². 2 The result of dividing by (N / mm 2The adhesive strength (shear peel strength) was calculated by multiplying the pressure (MPa) by 1,000 and converting it to kPa.

[0071] <Thermal demolition treatment and hot water peeling test> A quartz microscope slide (26mm wide x 76mm long x 1mm thick) manufactured by Misumi was coated with adhesive to the 10mm tip, with a target of 20mg. A quartz plate of the same size was then bonded to it to create a test specimen. The amount of adhesive applied (4) was determined with an accuracy of 0.1mg from the difference between the empty mass (1) of the two quartz plates and the mass of the test specimen after adhesive application (2). The test specimens shown were irradiated with a Contac LED lamp (wavelength 405nm) at a distance of 10mm for 5 minutes to perform photocuring adhesion. Afterward, the specimens were subjected to thermal decomposition for 1 minute in a hot air dryer preheated to 150°C to confirm whether the quartz plate peeled off (disintegrated). The results showed that the quartz plate could be easily peeled off from all specimens. The peeled specimens were separated to prevent re-adhesion. Furthermore, when thermal decomposition was performed separately at 150°C for 10 minutes and the adhesive strength (shear peel strength) was determined as described above, it was less than 10 kPa in all cases. Next, the separated test specimens were immersed in 60°C hot water to prevent overlapping of the adhesive surfaces where cured residues adhered, and left to stand for 10 minutes. After 10 minutes, excess moisture was removed without touching the adhesive layer, and the specimens were further dried in a vacuum dryer at 40°C and 1 kPa for 1 hour. Finally, the mass of the test specimens (3) after the hot water peel test was measured with an accuracy of 0.1 mg, and the hot water peel rate was calculated using the following formula.

[0072] Mass of the test specimen after adhesive application (2) - empty mass of two quartz plates (1) = mass of adhesive applied (4) Mass of test specimen after adhesive application (2) - Mass of test specimen after hot water peel test (3) = Peel mass (5) Hot water peel rate = (Peeling mass (5) / Adhesive application mass (4)) × 100 (%)

[0073] The evaluation results for each example and comparative example are summarized in Table 5. In Table 5, the "Ratio" and "Actual" in the "Category" column indicate that each experimental example corresponds to the "Comparative Example" and "Example," respectively.

[0074] [Table 5]

[0075] An easily disintegrating adhesive was prepared by mixing 67 mg of anthracene derivative A and 726 mg of anthracene derivative 5, and the transmittance of 405 nm light was measured using the method described above, and it was found to be 53.2%.

[0076] From Table 5, the following can be seen. The easily dismantled adhesive in the example demonstrates sufficient bonding strength, easy dismantling properties, and excellent removeability of adhesive components. On the other hand, adhesives containing only the first anthracene derivative represented by general formula (I) exhibited poor hot water peelability and poor removal of adhesive components. Furthermore, adhesives containing only the second anthracene derivative represented by general formula (II) exhibited inferior bonding strength. Furthermore, adhesives containing anthracene derivative 1, which is an anthracene derivative in general formula (II) where n is less than 20, and a first anthracene derivative A represented by general formula (I), exhibited poor hot water peelability and poor adhesive component removal.

Claims

1. An easily disassembled adhesive containing a first anthracene derivative represented by general formula (I) and a second anthracene derivative represented by general formula (II). 【Chemistry 1】 (In general formula (I), R １ *-COR ２ O-** or *-(CH ２ CH ２ O) ｍ - Represents **. m represents an integer from 1 to 50. R ２ R represents a divalent hydrocarbon group with 5 to 20 carbon atoms. １ In this, * represents the side that bonds with the oxygen atom in general formula (I), and ** represents the side that bonds with A in general formula (I). ** in A is R １ This indicates the part that connects with **. In general formula (II), n represents an integer between 20 and 150.

2. The easily disassembled adhesive according to claim 1, wherein the transmittance of 405 nm light at an optical path length of 20 μm is 10% or more.

3. In the general formula (I), R １ represents *-COR ２ O-**, and R ２ represents a divalent hydrocarbon group having 8 to 12 carbon atoms. The easily disassembled adhesive according to claim 1 or claim 2.

4. In general formula (I), R １ However, *-(CH ２ CH ２ O) ｍ An easy-to-disassemble adhesive according to claim 1 or claim 2, wherein -** represents an integer between 2 and 20.

5. The easy-to-disassemble adhesive according to claim 1 or claim 2, wherein in general formula (II), n represents an integer from 40 to 100.

6. The easy-to-disassemble adhesive according to claim 1 or claim 2, wherein when X is the number of anthracene residues derived from the first anthracene derivative contained in the easy-to-disassemble adhesive, and Y is the number of anthracene residues derived from the second anthracene derivative contained in the easy-to-disassemble adhesive, the value expressed as Y / (X+Y) is in the range of 0.01 to 0.

7.

7. The easily dismantled adhesive according to claim 1 or claim 2, wherein the content of the first anthracene derivative in relation to the total amount of the first anthracene derivative and the second anthracene derivative is 10% by mass to 95% by mass.

8. An easily disassembled adhesive containing at least one anthracene derivative having at least two anthracene residues in one molecule, and satisfying conditions (1)-(3). (1) When the easy-to-disassemble adhesive is placed between a pair of quartz plates and the easy-to-disassemble adhesive is cured by irradiating it with light of 350 nm to 450 nm to bond the pair of quartz plates, the shear peel strength between the quartz plates is 50 kPa or more. (2) The shear peel strength between the bonded pair of quartz plates after heating at 150°C for 10 minutes is less than 10 kPa. (3) When the quartz plates, with the residue of the hardened adhesive that has hardened under the conditions of (1) heated to reduce the shear peel strength between the quartz plates to less than 10 kPa, are immersed in 60°C hot water for 10 minutes, the hot water peel rate of the easy-to-dismantle adhesive before and after immersion is greater than 0%.

9. A laminate comprising, in this order, a first substrate, an adhesive layer containing a cured product of the easily disassembled adhesive described in claim 1 or claim 8, and a second substrate.

10. The laminate according to claim 9, wherein the light transmittance at 405 nm with an optical path length of 20 μm for at least one of the first substrate and the second substrate is 10% or more.

11. A step of applying the easily dismantled adhesive described in claim 1 or claim 8 between the first substrate and the second substrate, The process involves irradiating the applied easy-to-dismantle adhesive with light of 350 nm to 450 nm, A method for manufacturing a laminate having the following characteristics.

12. A step of heating the laminate according to claim 9 to reduce the shear peel strength of the adhesive layer, A step of separating the first substrate and the second substrate, A step of immersing at least one of the separated first substrate and the second substrate in hot water, A method for recycling laminates having the following characteristics.

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