Thermoplastic adhesive composition and method of making such thermoplastic adhesive composition

Abstract

The present invention relates to a thermoplastic adhesive composition comprising a linear oligomer and / or a linear polymer, which linear oligomer and / or linear polymer is obtained by a co-oligomerization and / or co-polymerization reaction of a mixture comprising at least one monomer containing two terminal glycidyl groups and at least one monomer containing two secondary amine groups, wherein the ratio between the number of terminal glycidyl groups and the number of secondary amine groups in the mixture is from 1 : 1.1 to 1 : 2.75. The present invention further relates to a liquid adhesive composition, a process for preparing the thermoplastic adhesive composition, and a process for applying and removing the thermoplastic adhesive composition and the liquid adhesive composition.

Description

Technical Field

[0001] This invention relates to thermoplastic adhesive compositions, particularly debonding-on-demand (DoD) adhesive compositions. The invention also relates to methods for preparing such thermoplastic adhesive compositions and methods for applying them to and removing them from substrates. Background Technology

[0002] Adhesives with on-demand release (DoD) functionality are receiving increasing attention because they enable controlled separation triggered by external stimuli such as heat, light, or chemicals. These adhesives typically contain thermoplastic components that enable reversible bonding, making them ideal for applications requiring easy disassembly and repair without damaging materials. Therefore, DoD adhesives can simplify and improve manufacturing processes, extend product lifecycles, and promote recycling.

[0003] One approach to obtaining DoD adhesives is through supramolecular polymers, which can be assembled (disassembled) by external stimuli such as chemicals, heat, light, magnetic fields, electric current, and ultrasound. Controlled assembly (disassembly) of supramolecular polymers allows switching their physical properties between an adhesive and a non-adhesive state. Examples include hydrogen-bonded adhesives, host-guest interactions such as cyclodextrin or cucurbituril inclusion complexes, metal-ligand complexes, and electrostatic interactions. However, the adhesive strength of supramolecular adhesives is typically limited to a few megapascals, which is lower than that of most commercial adhesives. Furthermore, their synthesis is often highly complex, which limits their technological applicability.

[0004] On the other hand, epoxy-based adhesives, which contain epoxy molecules, are widely recognized for their superior bond strength, durability, and resistance to environmental factors, making them highly attractive in industries such as watchmaking. However, they are thermosetting adhesives that form a three-dimensional cross-linked network upon curing. While this allows them to form strong bonds with a wide variety of materials, the resulting bond is not easily adjusted or detached once applied and cured, and the bond can be brittle, limiting the use of epoxy-based adhesives in applications requiring "flexibility." Furthermore, the curing process can be time-consuming and often requires precise conditions, such as controlled temperature and the use of a hardener, which complicates the application process. Precise mixing of the components (resin and hardener) to ensure optimal performance can be challenging and error-prone. Additionally, recycling these adhesives is difficult and expensive.

[0005] To allow for the readjustment of bonded components, such as when their relative positions are insufficient, epoxy-based adhesives with extended working times (until full curing) and UV-curing adhesives have been developed. However, these adhesives still present issues such as detachment of bonded components and problems with recycling.

[0006] Shellac is a natural resin produced by the lac insect and is another DoD adhesive used in watchmaking and other industries. Shellac can be used as a solution in alcohol, subsequently dried, or as a hot-melt adhesive, and can be debonded and rebonded, for example, by applying a solvent or heating. Shellac's adhesive strength exceeds that of many supramolecular polymers; for example, stainless steel lap joints formed with shellac exhibit typical strengths in the 7 MPa range. However, its physicochemical properties depend considerably on its source and the purification process employed, and the material is known to crosslink upon aging or heating. Therefore, adhesive properties, including the ability to debond and rebond, show significant variations. Summary of the Invention

[0007] The present invention aims to overcome one or more of the aforementioned deficiencies. One object of the present invention is to provide an adhesive composition that provides high adhesive strength and on-demand release (DoD) properties, allows for easy readjustment of bonded components and easy removal of the adhesive, and is easily recyclable and / or reusable. Therefore, the object of the present invention is to provide an adhesive composition that can be used for adjustable permanent bonding applications, as well as for temporary bonding applications, particularly in the watchmaking industry.

[0008] Another object of the present invention is to provide an adhesive composition that also has excellent resistance to moisture, sweat and chemicals, such as oil and detergents, particularly for use with detergents in the watchmaking industry.

[0009] Another objective is to provide a method for preparing the adhesive composition that is simpler and / or cheaper than methods for preparing prior art DoD adhesive compositions. Yet another objective is to provide a method with high reproducibility, i.e., yielding an adhesive composition with the same properties upon repeated application.

[0010] Another objective is to provide a method for applying these adhesives to the substrate that allows for precise bonding, demonstrates excellent caulking performance, and is universally applicable.

[0011] Another objective is to provide a method for removing these adhesives from a substrate to which adhesives have previously been applied, thereby facilitating the removal of these adhesives and optionally recycling and / or reusing them.

[0012] According to a first aspect of the invention, a thermoplastic adhesive composition as described in the appended claims is disclosed.

[0013] The thermoplastic adhesive composition comprises or is substantially composed of linear oligomers and / or linear polymers, said linear oligomers and / or linear polymers being obtained by co-oligomerization and / or copolymerization of a mixture comprising at least one monomer containing two terminal glycidyl groups and at least one monomer containing two secondary amine groups or one primary amine group.

[0014] For the purposes of this invention, the term "secondary amine group" refers to an amine group that can react with a single glycidyl group. In this disclosure, "monomer containing two secondary amine groups" and "diamine monomer" are used interchangeably and therefore have the same meaning, i.e., both amine groups are secondary amine groups.

[0015] The term "primary amine group" refers to an amine group that can react with two glycidyl groups. In this disclosure, "monomer containing a primary amine group" and "amine monomer" are used interchangeably and therefore have the same meaning, i.e., the amine group is a primary amine group.

[0016] In this disclosure, "at least one monomer containing two secondary amine groups or one primary amine group" means one or a combination of a monomer containing two secondary amine groups and a monomer containing one primary amine group. In this disclosure, this term may also be used interchangeably with the term "(di)amine monomer".

[0017] In this disclosure, "monomer containing two terminal glycidyl groups" and "diglycidyl monomer" are used interchangeably and therefore have the same meaning, that is, both glycidyl groups are terminal groups.

[0018] In this disclosure, the term "linear oligomer and / or linear polymer" refers to an adhesive composition comprising one or both of linear oligomers or linear polymers, or substantially composed of them.

[0019] During co-oligopolymerization and / or copolymerization, the mixture, particularly the monomers in the mixture, react. Advantageously, when the monomers in the mixture react, the terminal glycidyl groups react with the amine groups, thereby forming linear oligomers and / or linear polymers. As mentioned above, when the amine group is a secondary amine group, it will react with a single glycidyl group; while when the amine group is a primary amine group, it will react with two glycidyl groups.

[0020] The ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture is from 1:1.1 to 1:2.75, preferably from 1:1.1 to 1:2, more preferably from 1:1.1 to 1:1.5, and most preferably from 1:1.1 to 1:1.4. In this disclosure, "the number of amine groups" refers to the total number of amine groups, regardless of whether the amine groups are secondary or primary amine groups. In other words, "the number of amine groups" refers to the total number of secondary amine groups and, if present in the mixture, primary amine groups.

[0021] The inventors have discovered that when an excess of amine groups results in a ratio higher than 1:2.75, such as 1:3 and above, the resulting thermoplastic adhesive composition is brittle. This leads to poor adhesive properties, particularly when providing specific flexibility through adhesion or when the formed bond must withstand specific mechanical strain.

[0022] In other words, the mixture contains an excess of amine groups, i.e., more amine groups than terminal glycidyl groups, and the number of amine groups is at most 2.75 times that of terminal glycidyl groups. The inventors have found that this excess is necessary for obtaining thermoplastic adhesive compositions. More specifically, the excess of amine groups, at most 2.75 times that of terminal glycidyl groups, allows substantially all of the terminal glycidyl groups in the diglycidyl monomer to react with the amine groups, resulting in linear oligomers and / or linear polymers that are substantially free of crosslinkable groups (e.g., epoxy groups).

[0023] It was also found that when the mixture contains an excess of up to 2.75 times more amine groups than the terminal glycidyl groups, the degree of polymerization or oligomerization can be controlled and limited, thereby controlling and limiting the molecular weight of the resulting linear oligomers and / or linear polymers. In other words, as the ratio between the number of terminal glycidyl groups and the number of amine groups increases, the molecular weight of the resulting oligomers and / or polymers decreases.

[0024] The inventors have discovered that a combination of characteristics—the substantial absence of crosslinkable groups and the limitation of the molecular weight of the resulting linear oligomers and / or linear polymers—enables thermoplastic adhesive compositions. A second result of this combination of characteristics is the provision of thermoplastic adhesive compositions that are at least partially soluble in a wide range of solvents, preferably organic solvents.

[0025] Advantageously, the mixture further comprises a monofunctional secondary amine monomer, wherein "secondary amine" is as defined above. In this disclosure, the term "monofunctional monomer" refers to a monomer having a single functional group. In other words, a monofunctional secondary amine monomer is a monomer having a secondary amine group as its only functional group.

[0026] It is known in the art that the addition of a monofunctional secondary amine monomer to a mixture can contribute to limiting the molecular weight of the resulting oligomers and / or polymers, thereby contributing to the thermoplastic properties of the thermoplastic adhesive composition.

[0027] When the mixture contains a monofunctional secondary amine monomer, the monomer contributes to the number of amine groups in the mixture. It should be understood that when the mixture contains such a monomer, the ratio between the number of terminal glycidyl groups and the number of amine groups provided by monomers containing two secondary amine groups or one primary amine group (thus excluding amine groups provided by monofunctional secondary amine monomers) is lower than the ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture (thus including amine groups provided by monofunctional secondary amine monomers).

[0028] Advantageously, when the mixture contains a monofunctional secondary amine monomer, the number of terminal glycidyl groups in the mixture may be equal to or less than the number of amine groups provided by one or more monomers containing two secondary amine groups or one primary amine group, provided that the ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture (and thus including any amine groups provided by the monofunctional secondary amine monomer) is 1:1.1 to 1:2.75, preferably 1:1.1 to 1:2, more preferably 1:1.1 to 1:1.5, and most preferably 1:1.1 to 1:1.4.

[0029] Advantageously, when the mixture contains a monofunctional secondary amine monomer, the ratio between the number of terminal glycidyl groups and the number of amine groups provided by a monomer containing two secondary amine groups or one primary amine group (thus excluding any amine groups provided by the monofunctional secondary amine monomer) is equal to or greater than 1:1 and less than 1:2.75, preferably equal to or greater than 1:1 and less than 1:2, more preferably equal to or greater than 1:1 and less than 1:1.5, and most preferably equal to or greater than 1:1 and less than 1:1.4.

[0030] It should be understood that when the mixture does not contain monomers containing one primary amine group (i.e., monomers containing (all) amine groups are monomers containing two secondary amine groups), a 1:1 ratio means equal amounts or molar amounts of one or more monomers containing two terminal glycidyl groups and one or more monomers containing two secondary amine groups. In other words, in this case, the mixture is an equimolar mixture of one or more monomers containing two terminal glycidyl groups and one or more monomers containing two secondary amine groups.

[0031] Advantageously, the monomer containing two terminal amine groups is a piperazine. Alternatively, and more advantageously, the diamine is a compound represented by formula (I):

[0032] R 1 -NH-R 2 -NH-R3 (I),

[0033] in

[0034] R 1 and R 3 C is independent 1-20 Alkyl, preferably C 1-10 Alkyl, more preferably C 1-6 Alkyl group, C is the most preferred. 1-2 Alkyl, i.e., methyl or ethyl; and

[0035] R 2 It is C 1-20 Alkylene, preferably C 1-10 Alkylene, more preferably C 1-6 Alkylene, C is the most preferred. 1-2 Alkylenes, particularly methylene or ethylenes.

[0036] "Independently" refers to R 1 and R 3 They can be the same or different.

[0037] A specific example of a monomer containing two terminal amine groups as shown in formula (I) is N,N'-dimethylethylenediamine (R 1 and R 3 It is methyl, and R 2 It is ethylene) and N,N'-diethylethylenediamine (R 1 and R 3 It is ethyl, and R 2 It is ethylene).

[0038] Advantageously, the monomer containing two terminal glycidyl groups is bisphenol A diglycidyl ether (BADGE) as shown in formula (II):

[0039] (II),

[0040] Where n is 0 to 10, preferably 0 to 5, more preferably 1 to 4, for example 2 to 3.

[0041] Specific examples of linear oligomers and / or linear polymers are obtained by co-oligopolymerization and / or copolymerization of glycidyl monomers represented by formula (II) with piperazine, N,N'-dimethylethylenediamine or N,N'-diethylethylenediamine as diamine monomers, preferably wherein n is 0 to 3.

[0042] Advantageously, the number-average molecular weight M of the linear oligomers and / or linear polymers is... nThe molecular weight is 5000 to 30000 g / mol, preferably 6000 to 27500 g / mol, and more preferably 7500 to 25000 g / mol. In this disclosure, the number-average molecular weight is determined by size exclusion chromatography (SEC) using N,N-dimethylformamide as the eluent and calibrated based on polymethyl methacrylate standards.

[0043] Advantageously, linear oligomers and / or linear polymers have glass transition temperatures (T0) of 50 to 150 °C. g The glass transition temperature is preferably 60 to 130°C, more preferably 70 to 120°C. In this disclosure, the glass transition temperature is determined by differential scanning calorimetry (DSC) using two heating / cooling cycles at a heating / cooling rate of 10°C / min, wherein for the second heating cycle, T is reported. g value.

[0044] According to a second aspect of the invention, a liquid adhesive composition as defined in the appended claims is disclosed. This liquid adhesive composition comprises a thermoplastic adhesive composition according to the first aspect and contains an organic solvent. Advantageously, the linear oligomers and / or linear polymers in the thermoplastic adhesive composition are at least partially dissolved in the organic solvent, preferably substantially completely dissolved in the organic solvent. In this disclosure, "at least partially dissolved" means that at least 50%, preferably at least 75%, more preferably at least 85% of the linear oligomers and / or linear polymers are dissolved in the organic solvent. This adhesive composition can be used as a liquid adhesive, thus being easy to apply and easy to seal.

[0045] Advantageously, the organic solvent is selected from the group consisting of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), chloroform (CHCl3), and butylethylene glycol (BG). Particularly preferred examples of organic solvents include DMF and BG.

[0046] The advantages of the liquid adhesive composition of the present invention include, but are not limited to: ease of application, excellent caulking properties due to its excellent flowability, and the ability to be applied in low thickness while allowing for readjustment and on-demand release (DoD).

[0047] One advantage of the thermoplastic adhesive compositions of the present invention is that they soften, even to the point of being considered flowable, when heated to temperatures above their glass transition temperature. This allows them to be used as hot-melt adhesives. In other words, the thermoplastic adhesive compositions of the present invention can be used not only in the aforementioned liquid adhesive compositions but also as hot-melt adhesive compositions.

[0048] The thermoplastic properties of the thermoplastic adhesive composition of the present invention allow for easy readjustment of any substrate or component provided, which is achieved simply by heating the adhesive composition to a temperature above its glass transition temperature. This provides very precise adhesion and can be used as an adjustable permanent adhesive, meaning that the adhesive can permanently bond two substrates and can be easily readjusted when such adhesion does not meet specifications.

[0049] Furthermore, the thermoplastic properties of the adhesive composition allow for easy removal from the substrate or component to which the combination is applied, and the detachment of the adhesive composition from the article to which it is bonded (adheded together) can be achieved by heating the bonded components to a temperature higher than the glass transition temperature of the thermoplastic adhesive composition. The adhesive composition softens and can then be removed from the substrate or component. This allows for easy recycling of the adhesive composition and its reuse in other applications.

[0050] Alternatively or additionally, the adhesive composition can be removed from the substrate or component to which it has been applied, and the glued articles can be detached or removed by contacting the adhesive composition or the bonded joint with an organic solvent, wherein the linear oligomers and / or linear polymers in the adhesive are at least partially dissolved in the organic solvent.

[0051] It should be understood that removal and disassembly (de-adhesion) can also be achieved by combining the above methods (softening and dissolving).

[0052] The inventors have discovered that softening and dissolution of the adhesive composition in organic solvents do not alter the molecular structure of linear oligomers and / or linear polymers. In other words, the adhesive compositions of this invention can also be used as temporary adhesives in a wide range of applications.

[0053] Furthermore, any broken adhesive bond can be reformed by heating and softening the adhesive composition, then readjusting the parts and cooling. The inventors have discovered that this reforming results in a bond as strong as the initial bond, i.e., without loss of adhesive strength.

[0054] The inventors have discovered that, in addition to this thermoplastic property that allows for readjustment of adhesion and on-demand detachment, the adhesive composition of the present invention can achieve very strong adhesion, exceeding the adhesive strength achieved by prior art DoD adhesives, such as shellac and supermolecular adhesives.

[0055] According to a third aspect of the invention, a method for preparing a thermoplastic adhesive composition as described in the appended claims is disclosed. Specifically, the third aspect of the invention relates to a method for preparing a thermoplastic adhesive composition comprising linear oligomers and / or linear polymers. Advantageously, the thermoplastic adhesive composition is the thermoplastic adhesive composition according to the first aspect of the invention.

[0056] The method comprises or substantially consists of the following steps: reacting a mixture containing at least one monomer having two terminal glycidyl groups and at least one monomer having two secondary amine groups or one primary amine group.

[0057] The mixture is as described above. In other words, the monomer is as described above. Furthermore, the ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture is as described above. Advantageously, the mixture also comprises a monofunctional secondary amine monomer as described above.

[0058] Advantageously, the reaction is carried out in an inert atmosphere. The inert atmosphere advantageously contains helium, argon, nitrogen, or a combination of two or more of these gases, or is substantially composed of said gases, preferably nitrogen.

[0059] Advantageously, the reaction is carried out in the presence of a solvent. Advantageously, the solvent is N,N-dimethylformamide or butylethylene glycol. Advantageously, the method includes dissolving the diglycidyl monomer at least partially in the solvent. Advantageously, the method includes dissolving the (di)amine monomer at least partially in the solvent.

[0060] Advantageously, the reaction is carried out at a temperature of 50°C to 120°C, preferably 60°C to 100°C, more preferably 70°C to 90°C, for example 80°C.

[0061] Another aspect of the present invention discloses a method for applying the thermoplastic adhesive composition of the first aspect of the present invention or the liquid adhesive composition of the second aspect of the present invention to a substrate, as described in the appended claims.

[0062] According to a first embodiment, starting with the thermoplastic adhesive composition of the first aspect, the method includes dissolving at least partially a linear oligomer and / or linear polymer in the thermoplastic adhesive composition in an organic solvent to obtain the liquid adhesive composition of the second aspect; applying the liquid adhesive composition to a substrate; and removing the organic solvent. The removal of the organic solvent causes the liquid adhesive composition to cure. The solvent can be removed by means known in the art, such as evaporation.

[0063] According to a second embodiment, starting with the liquid adhesive composition described in the second aspect, the method includes applying the liquid adhesive composition to a substrate and removing an organic solvent. The removal of the organic solvent causes the liquid adhesive composition to cure. The solvent can be removed by means known in the art, such as evaporation.

[0064] The solvent is selected from the group consisting of N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, chloroform and butylethylene glycol.

[0065] Another aspect of the present invention discloses a method for removing the thermoplastic adhesive composition of the first aspect of the present invention or the liquid adhesive composition of the second aspect of the present invention from a substrate, as described in the appended claims.

[0066] The method involves contacting a substrate with an organic solvent to at least partially dissolve the linear oligomers and / or linear polymers in the thermoplastic adhesive composition, resulting in the liquid adhesive composition described in the second aspect of the invention. The substrate may be contacted with the organic solvent by methods known in the art, such as cleaning the substrate with the solvent or immersing the substrate in the solvent.

[0067] The method may further include removing the organic solvent from the liquid adhesive composition of the second aspect of the invention to obtain the thermoplastic adhesive composition of the first aspect of the invention. The solvent can be removed by means known in the art, such as evaporation.

[0068] The solvent is selected from the group consisting of N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, chloroform and butylethylene glycol.

[0069] Then, the liquid adhesive composition and the thermoplastic adhesive composition can be applied to the substrate according to the method described above.

[0070] The present invention also relates to the use of the adhesive composition described in the first aspect of the invention or the liquid adhesive composition described in the second aspect of the invention as an adjustable permanent adhesive or as a temporary adhesive, preferably for watch parts. Attached Figure Description

[0071] The invention is now described in more detail with reference to the accompanying drawings, wherein like reference numerals in the drawings denote like features, and wherein:

[0072] - Figure 1 The curves showing the shear stress versus strain of stainless steel lap joints bonded using four adhesive compositions of the present invention as hot melts are displayed (adhesion test).

[0073] - Figure 2The curves showing the shear stress versus strain of stainless steel lap joints bonded using four adhesive compositions of the present invention as liquid adhesives are displayed (adhesion test).

[0074] - Figure 3 The curves showing the shear stress versus strain of stainless steel lap joints rebonded using four adhesive compositions of the present invention as hot melts are displayed (adhesion test).

[0075] - Figure 4 The curves showing the shear stress versus strain of stainless steel lap joints rebonded using four adhesive compositions of the present invention as liquid adhesives are displayed (adhesion test).

[0076] - Figure 5 The stress-strain curves (tensile test) of three adhesive compositions of the present invention as a film with a thickness of 200 µm are shown.

[0077] - Figure 6 The results of dynamic mechanical analysis (DMA) are shown for four adhesives of the present invention;

[0078] - Figure 7 Showing the shear storage energy and loss modulus of the first adhesive of the present invention (rheological test);

[0079] - Figure 8 The shear storage energy and loss modulus of the second type of adhesive of the present invention are shown (rheological test).

[0080] - Figure 9 The shear storage energy and loss modulus of the third type of adhesive of the present invention are shown (rheological test). Detailed Implementation

[0081] The thermoplastic adhesive composition of the present invention comprises linear oligomers and / or linear polymers obtained by copolymerization and / or copolymerization of a mixture comprising at least one monomer containing two terminal glycidyl groups (“diglycidyl monomers”) and at least one monomer containing two secondary amine groups (“diamine monomers”) or one primary amine group (“amine monomers”) (hereinafter referred to as “(di)amine monomers”).

[0082] Advantageously, the diamine monomer is a straight-chain molecule as shown in formula (I):

[0083] R 1 -NH-R 2 -NH-R 3 (I).

[0084] Advantageously, R 2 It is C 1-20 Alkylene, i.e. -Cx H 2x - where x is from 1 to 20. R 2 It can be linear or branched. R is preferred. 2 It is C 1-10 Alkylene, more preferably C 1-6 Alkylene, C is the most preferred. 1-4 Alkylene. R 2 Non-restrictive examples include -(CH2)2-, -CH(CH3)CH2-, -(CH2)3-, -(CH2)4-, and -CH(CH3)CH(CH3)-. 2 A particularly preferred example is ethylene.

[0085] Advantageously, R 1 It is C 1-20 Alkyl, i.e. -C y H 2y+1 , where y is from 1 to 20. R 1 It can be linear or branched. R is preferred. 1 It is C 1-10 Alkyl, more preferably C 1-6 Alkyl group, C is the most preferred. 1-4 Alkyl groups, particularly methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl, more preferably methyl or ethyl.

[0086] Advantageously, R 3 It is C 1-20 Alkyl, i.e. -C z H 2z+1 , where z is from 1 to 20. R 3 It can be linear or branched. R is preferred. 3 It is C 1-10 Alkyl, more preferably C 1-6 Alkyl group, C is the most preferred. 1-4 Alkyl groups, particularly methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl, more preferably methyl or ethyl.

[0087] Non-limiting examples of diamine monomers represented by formula (I) include: N,N'-dimethyl-1,2-diaminoethane (CAS110-70-3), N,N'-diethyl-1,2-diaminoethane (CAS 111-74-0), N,N'-diisopropyl-1,2-diaminoethane (CAS 2213-43-6), N,N'-diisobutyl-1,2-diaminoethane (CAS 13987-78-3), N,N'-dimethyl-1,3-diaminopropane (CAS 3855-32-1), N,N'-diethyl-1,3-diaminopropane (CAS 6624-19-9), and N,N'-di-n-propyl-1,2-diaminoethane (CAS 7219-50-5).

[0088] Alternatively, and more advantageously, the diamine monomer is a cyclic molecule. Non-limiting examples of cyclic diamines include: cyclohexanes containing two secondary amine groups, such as piperazine (also known as 1,3-diazacyclohexane, CAS 110-85-0); cyclopentanes containing two secondary amine groups, such as 1,3-diazacyclopentane (also known as imidazoline, CAS 462-88-4); and cyclooctanes containing two secondary amine groups, such as triethylenediamine (also known as 1,4-diazabicyclo[2.2.2]octane, CAS 280-57-9). A particularly preferred cyclic diamine monomer is piperazine.

[0089] Advantageously, when an amine monomer is present, the amine monomer is a compound represented by formula (III), (IV) or (V), or benzylamine or aniline:

[0090] R 4 -NH2(III),

[0091] R 5 -O-(CH2) x -NH2(IV),

[0092] (HOR 6 )3-C-(CH2) y -NH2(V).

[0093] In equation (III), R 4 C is advantageous 3-8 Alkyl, preferably C 3-6 Alkyl groups, particularly n-propyl, isopropyl, n-butyl, or isobutyl. R 4 It can be linear or branched.

[0094] Non-limiting examples of amine monomers represented by formula (III) include n-propylamine, isopropylamine, n-butylamine, and isobutylamine.

[0095] In equation (IV), R 5 C is advantageous 1-8 Alkyl, preferably C 1-6 Alkyl, more preferably C 1-4 Alkyl groups, especially methyl or ethyl. R 5 It can be linear or branched.

[0096] In formula (IV), x is advantageously 1 to 8, preferably 1 to 6, more preferably 1 to 4, and especially 1 or 2.

[0097] Non-limiting examples of amine monomers represented by formula (IV) include 2-methoxyethylamine, 2-ethoxyethylamine, 2-methoxymethylamine and 2-ethoxymethylamine.

[0098] In equation (V), R 6 C is advantageous 1-8 Alkyl, preferably C 1-6 Alkyl, more preferably C 1-4 Alkyl groups, especially methyl or ethyl. R 6 It can be linear or branched.

[0099] In formula (V), y is advantageously 0 to 6, preferably 0 to 4, more preferably 0 to 2, and especially 0 or 1.

[0100] Non-limiting examples of amine monomers represented by formula (V) include tris(hydroxymethyl)aminomethane and tris(hydroxymethyl)aminoethane.

[0101] The diglycidyl monomer is advantageously bisphenol A diglycidyl ether (BADGE). Advantageously, the BADGE monomer has a number average molecular weight of 200 to 2000 g / mol, preferably 250 to 1500 g / mol, more preferably 300 to 1200 g / mol.

[0102] The mixture may further contain additional compounds for providing glycidyl groups to the mixture. Alternatively, the mixture may further contain additional compounds for providing amine groups to the mixture. Preferably, the additional compounds for providing amine groups to the mixture are monofunctional secondary amine monomers, i.e., monomers containing a secondary amine as a single functional group.

[0103] It is known in the art that the addition of monofunctional secondary amine monomers can act as chain terminators. In other words, it is known that monofunctional secondary amine monomers can control and limit the polymerization of difunctional monomers (i.e., monomers containing two functional groups) by introducing chain ends without reactive groups into the formed coolids and / or copolymers. Therefore, the addition of monofunctional secondary amine monomers can have similar effects to the use of excess (di)amine monomers and contribute to the formation of linear oligomers and / or linear polymers with shorter chain lengths and thus lower molecular weights.

[0104] The thermoplastic adhesive composition of the present invention is obtained by reacting amine groups in a mixture with terminal glycidyl groups in the mixture. During the reaction of the glycidyl groups with the amine groups, co-oligopolymerization and / or copolymerization reactions occur. Advantageously, the co-oligopolymerization and / or copolymerization reactions are carried out at a temperature of 50°C to 120°C in an inert atmosphere, preferably nitrogen.

[0105] Advantageously, the (di)amine monomer and the diglycidyl monomer are at least partially dissolved in an organic solvent before the amine group contacts the glycidyl group. According to a first embodiment, the diglycidyl monomer and the (di)amine monomer are at least partially dissolved separately, and then these at least partially dissolved monomers are contacted to react the glycidyl group with the amine group. This embodiment provides control over the dissolution and the co-oligopolymerization and / or copolymerization reaction. According to another embodiment, the diglycidyl monomer and the (di)amine monomer are at least partially dissolved together.

[0106] When one or both monomers are at least partially dissolved in an organic solvent, the method advantageously includes the step of precipitating the resulting linear oligomers and / or linear polymers. Precipitation of the linear oligomers and / or linear polymers can be carried out by methods known in the art, such as contact with a solvent that cannot dissolve the linear oligomers and / or linear polymers (i.e., a non-solvent for the linear oligomers and / or linear polymers). Methanol is particularly suitable as a non-solvent for the linear oligomers and / or linear polymers.

[0107] When the precipitation step is performed, the method advantageously further includes the step of separating the precipitated linear oligomers and / or linear polymers from the non-solvent. This separation step can be carried out by methods known in the art, such as, but not limited to, filtration and centrifugation.

[0108] Optionally, the separated linear oligomers and / or linear polymers may also be washed with a non-solvent to remove any residual solvent. Washing can be performed by methods known in the art. Optionally, the separated linear oligomers and / or linear polymers may be dried, advantageously by methods known in the art, such as at high temperatures and / or reduced pressure. Drying is advantageously performed to prevent softening of the linear oligomers and / or linear polymers, i.e., at temperatures lower than their glass transition temperature.

[0109] Advantageously, when the diglycidyl monomer is BADGE as shown in formula (II) and the (di)amine monomer is a diamine monomer (i.e., the reaction mixture is substantially free of monomers containing a primary amine group), the resulting linear oligomers and / or linear polymers have repeating units as shown in formula (VI):

[0110] (VI)

[0111] in

[0112] As mentioned above; and

[0113] X is -N(R) 1 )-R 2 -N(R 3 )- or , where R1 R 2 and R 3 As mentioned above.

[0114] For example, when the diamine monomer is piperazine, the repeating units of the linear oligomers and / or linear polymers are advantageously as shown in formula (VII):

[0115] (VII), where n is as described above.

[0116] For example, when the diamine monomer is N,N'-dimethyl-1,2-diaminoethane (i.e., R... 1 and R 3 It is methyl, and R 2 When the product is ethylene, the repeating units of the linear oligomer and / or linear polymer are advantageously represented as shown in formula (VIII):

[0117] (VIII), where n is as described above.

[0118] For example, when the diamine monomer is N,N'-diethyl-1,2-diaminoethane (i.e., R... 1 and R 3 It is ethyl, and R 2 When the product is ethylene, the repeating units of the linear oligomer and / or linear polymer are advantageously represented as shown in formula (IX):

[0119] (IX), where n is as described above.

[0120] It should be understood that the molecular weight of the resulting linear oligomers and / or linear polymers can be varied by changing the ratio between the number of terminal glycidyl groups and the number of amine groups, and by altering the molecular weight of the diglycidyl monomer. It is known that molecular weight affects the physical properties of oligomers and polymers, such as the glass transition temperature (T0). g Solubility, melt viscosity, solution viscosity, and adhesive strength. The applicant has found that employing these principles for molecular weight control can provide thermoplastic adhesive compositions that are at least partially soluble in a wide range of solvents, provide high adhesive strength and on-demand release (DoD) properties, and allow for easy refitting of bonded parts and easy removal of the adhesive, as well as easy recycling and / or reuse.

[0121] Example

[0122] Three reference thermoplastic adhesive compositions and six thermoplastic adhesive compositions of the present invention were prepared using the monomers and molar ratios shown in Table 1, wherein BADGE represents glycidyl-terminated poly(bisphenol A-copoly-epiochlorohydrin), which is a monomer having two terminal glycidyl groups; DMEDA represents N,N′-dimethylethylenediamine; and DEEDA represents N,N′-diethylethylenediamine.

[0123] Table 1: Monomer and Molar Ratio of Adhesive Compositions

[0124]

[0125] The reference adhesive composition PGE2-PP was prepared as follows: 1.00 g PGE (6.7 mmol) and 0.287 g piperazine (3.33 mmol) were added to 3 mL of N,N-dimethylformamide (DMF) as a solvent. The mixture was stirred at 80 °C under N2 for 24 hours, and then precipitated while hot in 10 times the excess of methanol. A white precipitate was obtained, filtered, washed three times with methanol, and dried under vacuum at 90 °C for 48 hours.

[0126] The preparation of BADGE is described below. x PP y The reference adhesive composition and the adhesive composition of the present invention were used. A first solution was prepared by completely dissolving the corresponding amounts of BADGE shown in Table 2 in DMF under N2 at room temperature with stirring. A second solution was prepared by dissolving the corresponding amounts of piperazine (PP) shown in Table 2 in DMF. The second solution was then added to the first solution, and the mixture was reacted at 80°C under N2 with continuous stirring for 24 hours. The reaction mixture was then precipitated hot into a 10-fold excess of methanol. A white precipitate was obtained, which was filtered, washed three times with methanol, and dried under vacuum at 90°C for 48 hours.

[0127] Table 2: Corresponding amounts of monomers used in adhesive compositions

[0128]

[0129] BADGE is also prepared in butyl ethylene glycol (BG) as a solvent. 1075 PP 1.2 and BADGE 1075 PP 1.3 The preparation of BADGE is described below. 1075 PP 1.2A first solution was prepared by completely dissolving 20.00 g (18.60 mmol) of BADGE in 40 mL of BG under N2 with stirring at 120 °C, followed by cooling the mixture to 80 °C. A second solution was prepared by dissolving 1.92 g (22.3 mmol) of piperazine (PP) in 20 mL of BG. The second solution was then added to the first solution, and the mixture was reacted at 80 °C under N2 with continuous stirring for 24 hours. The reaction mixture was then precipitated hot in 10 times the excess of methanol. A white precipitate was obtained, which was filtered, washed three times with methanol, and dried under vacuum at 90 °C for 48 hours. BADGE was prepared in the same manner. 1075 PP 1.3 However, 30.00g (27.90 mmol) of BADGE was dissolved in 60mL of BG, and 3.13g (36.30mmol) of PP was dissolved in 30mL of BG.

[0130] The preparation of BADGE is described below. 1075 DMEDA 1.3 and BADGE 1075 DEEDA 1.3 1.00 g (0.93 mmol) of BADGE was added to 3 mL of DMF as a solvent, and the mixture was stirred at room temperature under N2 until the BADGE was completely dissolved. Then, 0.107 g (1.21 mmol) of DMEDA or 0.141 g (1.21 mmol) of DEEDA was added to the solution, followed by heating at 80 °C for 30 hours under N2 and continuous stirring. The reaction mixture was then precipitated while hot into 10 times the excess of methanol. A white precipitate was obtained, filtered, washed three times with methanol, and dried under vacuum at 90 °C for 48 hours.

[0131] Table 3 shows the number average molecular weight (M) of the obtained adhesive compositions. n Polydispersity index (Đ) and glass transition temperature (T) g ).

[0132] M was determined by size exclusion chromatography (SEC) and based on calibration using polymethyl methacrylate (PMMA) standards. n And polydispersity index (Đ) value. SEC detection was performed using an Agilent Technologies 1200 Series HPLC system equipped with one Agilent Plgel hybrid guard column (particle size = 5 μm) and two Agilent Plgel hybrid-D columns (ID = 7.5 mm, L = 300 mm, particle size = 5 μm). DMF was used as the eluent, and the flow rate was 1.0 mL / min. –1Furthermore, UV (Agilent 1200 series, λ = 346 nm) and refractive index (Wyatt Technology Corp., Optilab REX interferometric refractometer) detectors were used to monitor the signal. Data was processed using Astra software (Wyatt Technology Corp.).

[0133] T was determined by differential scanning calorimetry (DSC). g DSC analysis was performed on a Mettler-Toledo STAR instrument in a temperature range of -20 to 200 °C. Starting at -20 °C, samples were analyzed at 10 °C min... -1 The heating / cooling rate was adjusted to two heating / cooling cycles. Tests were performed in a standard aluminum pan, using approximately 5 mg of sample per test; unless otherwise specified, the reported data are from the second heating cycle.

[0134] Table 3: M of the adhesive composition n Multidispersion index and T g

[0135]

[0136] A reference adhesive composition BADGE was found to be prepared using equimolar amounts of BADGE and PP. 1075 PP 1.0 It is insoluble in DMF, making SEC testing impossible to determine its M. n And (Đ). It should be noted that when using DMF or BG as a solvent, similar M values ​​are obtained. n Adhesive compositions using DMEDA and DEEDA as diamine monomers. T g The temperatures were significantly lower than those of adhesive compositions prepared using piperazine (71°C and 74°C vs. 91°C, respectively). This can be explained by the fact that acyclic diamines DMEDA and DEEDA have higher flexibility than cyclic piperazines. This demonstrates that the properties of the adhesive can be easily tuned by changing the diamine monomers.

[0137] It was found that all adhesive compositions prepared using excess diamine monomers (PP, DMEDA, and DEEDA) were soluble in DMF, DMSO, THF, CHCl3, and butyl ethylene glycol (BG), and could be dissolved in amounts of 33% by weight and even up to 56% by weight.

[0138] In fact, a well-defined glass transition temperature can be obtained, confirming the thermoplastic characteristics of the adhesive. Despite the thermoplastic properties of the adhesive, surprisingly high bond strength was detected.

[0139] To test the feasibility of using the adhesive composition as a hot-melt adhesive, a 100 µm thick film was prepared from the adhesive composition as described below. 100 mg of the adhesive composition was dissolved in 2 mL of CHCl3. These solutions were then cast into 6 cm diameter polytetrafluoroethylene (PTFE) Petri dishes and allowed to stand overnight in a well-ventilated fume hood. The Petri dishes were then placed in a vacuum oven at 50 °C for 24 hours. The samples were removed from the mold and processed in Carver. ® The PTFE sheets are compressed and molded between two PTFE sheets at 110°C and 4 tons of pressure for 10 minutes in a press.

[0140] The 100 µm thick film was then cut into 1 cm² pieces, and lap joints with a 1 cm² overlap were prepared for the adhesion test using stainless steel substrates (width: 10.0 mm, length: 80.0 mm, thickness: 1.0 mm). The 1 cm² film pieces were placed at the end of one of the two stainless steel substrates, and the two substrates were placed separately on a hot plate heated to 120°C. When the adhesive had formed a viscous liquid, the two substrates were stacked to clamp the adhesive, and the resulting joint was placed back on the hot plate. Mild pressure was applied by placing a 100 g weight on top of the bonded lap joint. After 10 minutes, the joint was mechanically secured with a clamp and cooled to room temperature, after which the clamp was removed. It should be noted that the reference adhesive composition BADGE was used. 1075 The film obtained from PP3 is very brittle. It cannot be properly bonded using the reference adhesive composition. 1075 PP 1.0 The membrane was treated and tensile tests were performed using an overlap joint formed from the adhesive solids thus synthesized. (Using BADGE) 1075 PP 3.0 The resulting membrane was too brittle to be detected.

[0141] Alternatively, an adhesive composition as a liquid adhesive composition (i.e., as a solution) was used to prepare the lap joint. Two stainless steel substrates (width: 10.0 mm, length: 80.0 mm, thickness: 1.0 mm) were placed on a hot plate heated to 120°C for 5 minutes. The adhesive composition was dissolved in BG to obtain a solution containing 33% by weight of the adhesive composition. Two drops of the adhesive-BG solution were placed on one of the two stainless steel substrates, and then the two stainless steel substrates were stacked to clamp the adhesive. The resulting joint was placed back on the hot plate, and gentle pressure was applied by placing a 100g weight on top of the bonded lap joint. After 10 minutes, the joint was mechanically secured with a clamp and placed in an oven set to 120°C to completely evaporate the solvent. After 60 minutes, the sample was removed from the oven and cooled to room temperature, after which the clamp was removed.

[0142] A reference adhesive composition BADGE was found to be prepared using equimolar amounts of BADGE and PP. 1075 PP 1.0 It is insoluble in BG, which limits its application as a liquid adhesive. For this adhesive, liquid adhesive lap joints cannot be obtained, so adhesion tests cannot be performed. Reference adhesive composition BADGE 1075 PP3 can dissolve in BG, but the resulting joint is very brittle.

[0143] The lap joints were subjected to adhesion tests at ambient temperature on a Zwick / Roell Z010 tensile testing machine equipped with mechanical clamps and a 10 kN load chamber, with a strain rate of 1 mm / min. -1 Table 4 shows the shear strength (in MPa) measured for hot melt adhesives and liquid adhesives. Figure 1 and Figure 2 The present invention's adhesive composition BADGE is shown when using DMF as a solvent. 1075 PP 1.1 BADGE 1075 PP 1.2 BADGE obtained when using DMF as a solvent 1075 PP 1.3 and BADGE 1075 PP 1.4 The curves showing the shear stress versus strain of stainless steel lap joints bonded using hot melt adhesive and liquid adhesive, respectively.

[0144] Table 4: Shear strength of adhesive compositions as hot melt and as liquid

[0145]

[0146] As can be clearly seen from Table 4, all adhesive compositions of the present invention used as hot melts and as liquid adhesives have a strength of at least 5.2 MPa (BADGE). 1075 PP 1.4 (hot melt) and even 16.0 MPa (using BADGE) 1075 PP 1.2 Excellent adhesive strength of liquid adhesives prepared in DMF. Regarding BADGE prepared in DMF. 1075 PP y Series, adhesive strength (bonding strength) with hot melt adhesives and liquid adhesives M n The adhesive strength increases with the increase of [the specific component / temperature]. The adhesive strength obtained using the adhesive of this invention as a hot melt is comparable to the adhesive strength reported in the literature for shellac (approximately 6.9 MPa).

[0147] Adhesives prepared using BG as a solvent yielded similar adhesive strength values ​​to those prepared using DMF (with the same molar ratio). Furthermore, replacing the piperazine as a diamine monomer with DMEDA or DEEDA resulted in similar or slightly higher adhesive strengths. This is believed to be related to the flexibility of DMEDA and DEEDA monomers compared to cyclic piperazines.

[0148] Liquid adhesives exhibit significantly higher bond strength than the same adhesive compositions used as hot melts. In some cases, this value can even reach twice that of liquid adhesives (e.g., for BADGE). 1075 PP 1.2 This can be explained by the fact that liquid adhesives have better wettability on stainless steel substrates.

[0149] After the adhesion test failed, the lap joint was reheated and bonded by placing the two stainless steel substrates back onto a hot plate at 120°C without applying additional adhesive or adhesive solution (for liquid adhesive compositions). Once the adhesive had formed a viscous liquid, the two substrates were joined as described above, and a second shear test was performed. Figure 3 and Figure 4 show Figure 1 and Figure 2 The curves showing the shear stress versus strain for the four adhesives of this invention are shown, but this was used for a second test (so after re-bonding). Very similar values ​​were detected, indicating that re-bonding can be easily performed without loss of adhesive strength.

[0150] Rapid heating and on-demand debonding are also demonstrated by mounting up to 40 kg of weight on stainless steel lap joints, which are achieved by using BADGE 1075 PP 1.2 (Prepared with DMF) Dissolved in BG as a liquid binder. The joint is then heated to above 90°C, i.e., above its T... g At a certain temperature, debonding is achieved within seconds.

[0151] A 200 µm thick membrane was prepared in the same manner as described for a 100 µm thick membrane, but 200 mg of the adhesive composition was dissolved in 2 mL of CHCl3, and the BADGE-PP adhesive composition of the present invention was used.

[0152] According to ASTM D882, these films were subjected to tensile tests under ambient conditions (25°C) on a static material testing apparatus from Zwick / Roell, equipped with a 200 N Xforce HP load chamber. The tensile tests were conducted at 150% min... −1Strain rate tests were performed on rectangular samples (width: 5.2 mm). The reported data are the average of 5 to 8 independent tests, and all errors are standard deviations. Figure 5 The obtained stress-strain curves show that the tensile strength (σ) and failure strain (ε) largely depend on M. n BADGE 1075 PP 1.4 It is very brittle and fails at σ = 0.5 ± 0.01 MPa and ε < 0.1%; while among machinable materials, it has the highest M n BADGE 1075 PP 1.1 It is a strong and tough material, exhibiting σ = 48 ± 3 MPa and ε = 7.4 ± 0.2%. 1075 PP 1.2 The values ​​(σ = 23 ± 1 MPa, ε = 2.8 ± 0.1%) and BADGE 1075 PP 1.3 value (σ = 13 ± 1 MPa, ε = 2.7 ± 0.1%) lies between these limits, and with M n change.

[0153] A 200 µm thick film was also analyzed using dynamic mechanical analysis (DMA) on a TA Instruments DMA Q800 instrument, with a heating rate of 3 °C / min. -1 The frequency was 1 Hz and the amplitude was 15 µm, with a temperature range of 25°C to 200°C. A tensile clamp and rectangular samples (width: 5.2 mm, length: 10.0 mm) were used. The reported data are the average of 5 to 8 independent measurements, and all errors are standard deviations.

[0154] Figure 6 The presence of DMA traces confirms the thermoplastic features observed during DSC, and Figure 5 The stress-strain data from the tensile tests are shown. All adhesive compositions show extension into the glassy region at approximately 90–110 °C, where the storage modulus E' is relatively constant. At 25 °C, BADGE... 1075 PP 1.1 It showed a significantly higher E' (3.5 ± 0.2 GPa), which is consistent with the high M of this material. n Related. BADGE 1075 PP 1.2 BADGE 1075 PP 1.3 and BADGE 1075 PP1.4 This indicates low stiffness, with E' values ​​ranging from 0.9 ± 0.2 to 1.2 ± 0.2 GPa. In the range above 90°C to 110°C, E' begins to decrease rapidly, indicating that T... g (100℃ - 120℃) at the beginning. With lower M n BADGE 1075 PP 1.4 In T g It will expire at any time.

[0155] BADGE 1075 PP 1.2 BADGE 1075 PP 1.3 and BADGE 1075 PP 1.4 Isothermal rheological tests were also conducted on 200 µm thick membranes using an Anton Paar MCR 702 rheometer equipped with a CTD600 convection temperature unit. A plate-to-plate geometry with an 8 mm diameter was used. The membranes were loaded into the instrument, and the test temperature was set to 120 °C. Once this temperature was reached, the gap was set to 0.1 mm, and the test was initiated while maintaining a constant temperature for 60 minutes. Changes in storage modulus and loss modulus (G' and G”, respectively) over time were monitored.

[0156] Figure 7 , Figure 8 and Figure 9 Display BADGE respectively 1075 PP 1.2 BADGE 1075 PP 1.3 and BADGE 1075 PP 1.4 The storage modulus and loss modulus. As expected, these data show that the melt viscosity increases with M. n The values ​​increase and decrease with temperature. More importantly, when the material is heated, G' and G” show only small changes, indicating that the viscoelastic properties remain constant under the experimental conditions. In particular, no crossover points between G' and G” were observed in any material, suggesting the absence of a crosslinking reaction.

Claims

1. A thermoplastic adhesive composition comprising linear oligomers and / or linear polymers, said linear oligomers and / or linear polymers being obtained by co-oligopolymerization and / or copolymerization of a mixture comprising at least one monomer containing two terminal glycidyl groups and at least one monomer containing two secondary amine groups or one primary amine group, characterized in that... The ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture is 1:1.1 to 1:2.75, preferably 1:1.1 to 1:2, more preferably 1:1.1 to 1:1.5, and most preferably 1:1.1 to 1:1.

4.

2. The thermoplastic adhesive composition according to claim 1, wherein the mixture further comprises a monofunctional secondary amine compound.

3. The thermoplastic adhesive composition according to any one of the preceding claims, wherein the mixture comprises a monomer containing two secondary amine groups, and wherein the monomer containing two secondary amine groups is a piperazine or a compound of formula (I): R 1 -NH-R 2 -NH-R 3 (I), in R 1 and R 3 C is independent 1-20 Alkyl, preferably C 1-10 Alkyl, more preferably C 1-2 Alkyl; and R 2 It is C 1-20 Alkylene, preferably C 1-10 Alkylene, more preferably C 1-2 Alkylene, xylene, or halogenated xylene.

4. The thermoplastic adhesive composition according to any one of the preceding claims, wherein the monomer containing two terminal glycidyl groups is bisphenol A diglycidyl ether (BADGE) of formula (II): (II), Where n is 0 to 10, preferably 0 to 5, and more preferably 2 to 3.

5. The thermoplastic adhesive composition according to any one of the preceding claims, wherein the number average molecular weight M of the linear oligomer and / or linear polymer is... n The number average molecular weight is 5,000 to 30,000 g / mol, preferably 7,500 to 25,000 g / mol, and is determined by size exclusion chromatography (SEC) using N,N-dimethylformamide as the eluent and calibrated based on polymethyl methacrylate standards.

6. The thermoplastic adhesive composition according to any one of the preceding claims, wherein the linear oligomer and / or linear polymer has a glass transition temperature (T0) of 50 to 150°C, preferably 70 to 120°C. g The glass transition temperature was determined by differential scanning calorimetry (DSC) using two heating / cooling cycles at a heating / cooling rate of 10 °C / min, wherein T is reported for the second heating cycle. g value.

7. A liquid adhesive composition comprising an organic solvent and a thermoplastic adhesive composition according to any one of the preceding claims, wherein the linear oligomers and / or linear polymers in the thermoplastic adhesive composition are at least partially dissolved in the organic solvent, preferably the solvent being selected from the group consisting of N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, chloroform, and butylethylene glycol.

8. A method for preparing a thermoplastic adhesive composition comprising linear oligomers and / or linear polymers, the method comprising reacting a mixture comprising at least one monomer containing two terminal glycidyl groups and at least one monomer containing two secondary amine groups or one primary amine group, characterized in that... The ratio between the number of terminal glycidyl groups and the number of amine groups in the mixture is 1:1.1 to 1:2.75, preferably 1:1.1 to 1:2, and most preferably 1:1.1 to 1:1.

4.

9. The method according to claim 8, wherein the mixture is reacted in the presence of a solvent at a temperature of 50°C to 120°C, preferably 70°C to 90°C, in an inert atmosphere.

10. The method according to claim 8 or claim 9, wherein the mixture further comprises a monofunctional secondary amine compound.

11. The method according to any one of claims 8-10, wherein the mixture comprises a monomer containing two secondary amine groups, and wherein the monomer containing two secondary amine groups is a piperazine or a compound of formula (I).

12. The method according to any one of claims 8-10, wherein the monomer containing two terminal glycidyl groups is bisphenol A diglycidyl ether (BADGE) of formula (II).

13. The method according to any one of claims 8-12, wherein the solvent is N,N-dimethylformamide or butyl ethylene glycol.

14. A method of applying a thermoplastic adhesive composition according to any one of claims 1-6 or a liquid adhesive composition according to claim 7 to a substrate, the method comprising: - For any thermoplastic adhesive composition according to any one of claims 1-6, the thermoplastic adhesive composition is at least partially dissolved in an organic solvent, preferably the solvent being selected from the group consisting of N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, chloroform and butylethylene glycol, thereby obtaining the liquid adhesive composition according to claim 7; - Apply the liquid adhesive composition to the substrate; and - Remove the organic solvent, thereby curing the liquid adhesive composition.

15. A method for removing an adhesive from a substrate, said adhesive comprising a thermoplastic adhesive composition according to any one of claims 1-6 or a liquid adhesive composition according to claim 7, the method comprising: - Contacting the substrate with an organic solvent to at least partially dissolve the adhesive and obtain the liquid adhesive composition according to claim 7, preferably the organic solvent being selected from the group consisting of N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, chloroform, and butylethylene glycol; and - For the thermoplastic adhesive composition according to any one of claims 1-6, the organic solvent is removed from the liquid adhesive composition according to claim 7.

16. Use of the thermoplastic adhesive composition according to any one of claims 1-6 or the liquid adhesive composition according to claim 7 as an adjustable permanent adhesive or as a temporary adhesive, preferably for watch parts.

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