Method for preparing self-healing resin composition

Abstract

To provide a method for producing a new self-repairing resin composition having high self-repairing properties.SOLUTION: A method for producing a self-repairing resin composition includes a step of reacting diisothiocyanates, dithiols, and a crosslinking agent to obtain a resin composition, wherein at least one of the diisothiocyanates and the dithiols has an ether structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a self-repairing resin composition having self-repairing properties. [Background technology]

[0002] In recent years, efforts have been made to develop resin compositions (self-repairing materials) that can repair scratches or breaks by themselves, with the aim of making effective use of resources and reducing waste, etc. As such a resin composition, for example, a self-repairing resin composition made of a sulfur-containing polymer that can bond in water has been proposed (see, for example, Patent Document 1).

[0003] In addition, polydithiourethanes having aliphatic or alicyclic structures have been reported as resin compositions made of similar sulfur-containing polymers (see, for example, Non-Patent Documents 1 and 2), but their self-healing properties have not been reported in detail. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2017 / 047733 [Non-patent literature]

[0005] [Non-Patent Document 1] Y. Yoshida, K. Ohnaka, T. Endo, Macromolecules (ACS), Vol. 52, No. 16, pp. 6080-6087, (2019) [Non-patent document 2] Y. Yoshida, T. Endo, Journal of Polymer Science Part A: Polymer Chemistry (Wiley), Vol. 56, No. 19, pp. 2255-2262, (2018) Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for producing a novel self-repairing resin composition having high self-repairing properties. [Means for solving the problem]

[0007] As a result of research aimed at solving the above problems, the inventors discovered that a novel self-repairing resin composition can be obtained by reacting a diisothiocyanate and a dithiol, at least one of which has an ether structure, with a crosslinking agent, and thus completed the present invention.

[0008] That is, the present invention relates to a method for producing a resin composition having self-repairing properties by reacting diisothiocyanates, dithiols, and a crosslinking agent, in which at least one of the diisothiocyanates and the dithiols has an ether structure.

[0009] The present invention also relates to a self-repairing resin composition represented by any one of the following formulas (VI) to (VIII): (Formulas (VI) to (VIII) each represent a polymer having three structural units.)

[0010] [ka]

[0011] [ka]

[0012] [ka]

[0013] The present invention also relates to a self-repairing resin composition represented by any of the following formulas (X) to (XII): (wherein formulas (X) to (XII) each represent a polymer having four structural units.)

[0014] [ka]

[0015] [ka]

[0016] [ka] [Effects of the Invention]

[0017] According to the method for producing a self-repairing resin composition of the present invention, a novel self-repairing resin composition having high self-repairing properties can be provided. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a photograph of the sheet-shaped resin compositions of Examples 1 to 3. [Figure 2] FIG. 2 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition (resin film) of Example 1. [Figure 3] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing test of the sheet-shaped resin composition of Example 2. [Figure 4] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing test of the sheet-shaped resin composition of Example 3. [Figure 5] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 4. [Figure 6] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 5. [Figure 7]FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 6. [Figure 8] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 7. [Figure 9] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 8. [Figure 10] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing property test of the sheet-shaped resin composition of Example 9. [Figure 11] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing test of the sheet-shaped resin composition of Example 10. [Figure 12] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing test of the sheet-shaped resin composition of Example 11. [Figure 13] FIG. 10 is a diagram showing the results of a tensile test in a self-repairing test of the sheet-shaped resin composition of Example 12. [Figure 14] FIG. 2 is a diagram showing the results of a repeated durability test of the sheet-shaped resin composition of Example 1. [Figure 15] FIG. 10 is a diagram showing the results of a repeated durability test of the sheet-shaped resin composition of Example 2. [Figure 16] FIG. 1 is a diagram showing an outline of a load-bearing test. [Figure 17] FIG. 1 is a diagram showing an outline of a recycling test. [Figure 18] FIG. 1 is an explanatory diagram of a test piece for evaluating adhesive strength. [Figure 19] FIG. 1 shows photographs of test pieces prepared using each substrate for adhesive strength evaluation. (a) is a stainless steel test piece, (b) is an aluminum test piece, (c) is a copper test piece, and (d) is a glass test piece. [Figure 20] These are photographs showing the load-bearing test conditions in the adhesive strength evaluation, where (a) is a stainless steel test piece, (b) is an aluminum test piece, (c) is a copper test piece, and (d) is a glass test piece. [Figure 21] FIG. 1 is a diagram showing an outline of a disassembly and re-adhesion test using a glass test piece (S1214). [Figure 22]This figure shows the results of disassembly and re-adhesion tests using a glass test piece (S1214). (a) is the test piece after thermal disassembly, (b) is the test piece after thermal disassembly and THF washing, and (c) shows A: the components isolated by the purification procedure, and B: the components contained in the THF solution after washing. [Figure 23] FIG. 1 shows the results of a disassembly and re-adhesion test using a copper test piece (C1100). DETAILED DESCRIPTION OF THE INVENTION

[0019] The method for producing a self-repairing resin composition of the present invention is a method for producing a self-repairing resin composition, which comprises a step of reacting diisothiocyanates, dithiols, and a crosslinking agent to obtain a resin composition, and is characterized in that at least one of the diisothiocyanates and dithiols has an ether structure. That is, at least one of the diisothiocyanates and dithiols used in the production method of the present invention has an ether bond. The ether structure may be contained as part of an ester.

[0020] According to the production method of the present invention, it is possible to easily produce a self-repairing resin composition having a high self-repairing property not previously available. That is, the resin composition produced by the production method of the present invention is capable of self-repairing the damaged part when damaged, and is useful as, for example, a resin film such as an optical film, a liquid crystal protective film, a pressure-sensitive adhesive sheet, an adhesive, an eyeglass lens, a camera lens, a microlens, etc.

[0021] Furthermore, the resin composition produced by the production method of the present invention can be chemically recycled, and can be regenerated when its performance deteriorates.

[0022] Specific examples of the method for producing the self-repairing resin composition of the present invention include the following embodiments (production embodiments a) to c). a) A mode using a diisothiocyanate having an ether structure, a dithiol having an ether structure, and a crosslinking agent b) A mode using a diisothiocyanate having no ether structure, a dithiol having an ether structure, and a crosslinking agent c) An embodiment using a diisothiocyanate having an ether structure, a dithiol not having an ether structure, and a crosslinking agent

[0023] <Method for producing the self-repairing resin composition of the first invention> The first method for producing a self-repairing resin composition of the present invention is a method in which a diisothiocyanate, a dithiol, and a crosslinking agent are reacted in an organic solvent.

[0024] [Diisothiocyanates with ether structure] The diisothiocyanates having an ether structure used in the production method of the first invention are compounds represented by the following formula (I).

[0025] [ka]

[0026] In formula (I), R 1 and R 2 are each independently -C k H 2k - (k represents an integer of 1 to 3), and m represents an integer of 1 to 5.

[0027] [Dithiols with Ether Structure] The dithiol having an ether structure used in the production method of the first aspect of the present invention is preferably a compound represented by the following formula (II).

[0028] [ka]

[0029] In formula (II), R 3 is a linking group represented by the following formula (a-1) or formula (a-2).

[0030] [ka]

[0031] [ka]

[0032] In formula (a-1), R 4 and R 5 are each independently -C k H 2k - (k represents an integer of 1 to 3), and i represents an integer of 1 to 5. In formula (a-2), j represents an integer of 1 to 5.

[0033] [Diisothiocyanates without ether structure] The diisothiocyanates having no ether structure used in the production method of the first invention are preferably compounds represented by the following formula (III).

[0034] [ka]

[0035] In formula (III), R 6 Ha-C k H 2k - (k represents an integer of 3 to 12), or a linking group represented by the following formulas (b-1) to (b-4), k H 2k - (k represents an integer of 3 to 12) is preferred, and -C k H 2k - (k represents an integer of 5 to 10) is preferred.

[0036] [ka]

[0037] [Dithiols without ether structure] The dithiol having no ether structure used in the production method of the first aspect of the present invention is preferably a compound represented by the following formula (IV).

[0038] [ka]

[0039] In formula (IV), R 7 Ha-C k H 2k - (k represents an integer of 3 to 10), or a linking group represented by the following formula (c):

[0040] [ka]

[0041] In formula (c), R 8 Ha-C k H 2k - (k represents an integer from 3 to 10).

[0042] [Crosslinking agent] The crosslinking agent used in the first production method of the present invention is preferably a polyfunctional thiol compound having three or more thiol groups in the molecule, more preferably a tetrafunctional thiol compound. The crosslinking agent may be a single type or two or more types.

[0043] Specifically, a preferred crosslinking agent (polyfunctional thiol compound) is, for example, a compound represented by the following formula (V).

[0044] [ka]

[0045] In formula (V), R 9 is a linking group represented by the following formulae (d-1) to (d-3), and is preferably a linking group represented by the following formula (d-1).

[0046] [ka]

[0047] R 9 The polyfunctional thiol compound (d-1) is 2,2-bis(mercaptomethyl)-1,3-propanedithiol (hereinafter sometimes referred to as PE). 9 The polyfunctional thiol compound (d-2) is 2,2-bis[[(3-mercaptopropionyl)oxy]methyl]trimethylenebis[3-mercaptopropionate] (hereinafter sometimes referred to as MP). 9 The polyfunctional thiol compound (d-3) is 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril (hereinafter, sometimes referred to as BU).

[0048] In the first production method of the present invention, the three types of diisothiocyanates, dithiols, and crosslinking agent may be mixed and reacted simultaneously, or two types may be mixed together and then the remaining one may be mixed.

[0049] The blending ratio of the dithiol to the diisothiocyanates is preferably 0.10 to 0.95 equivalents in molar ratio, more preferably 0.30 to 0.90 equivalents, and even more preferably 0.60 to 0.85 equivalents.

[0050] The mixing ratio of the crosslinking agent is preferably 0.04 to 0.18 equivalents, more preferably 0.06 to 0.15 equivalents, and even more preferably 0.08 to 0.12 equivalents, in molar ratio relative to the diisothiocyanates.

[0051] Examples of organic solvents that can be used include dichloromethane, methyl ethyl ketone (MEK), toluene, tetrahydrofuran (THF), acetone, dimethylformamide (DMF), and ethyl acetate. The reaction temperature is usually about 0°C to 100°C, preferably room temperature (20 to 25°C). The reaction time is, for example, about 1 to 48 hours, preferably about 12 to 36 hours.

[0052] In the first production method of the present invention, a polyaddition reaction is usually used. In the polyaddition reaction, it is preferable to add an organic base as a catalyst. Examples of organic bases include triethylamine, dimethylethylamine, tetramethylethylenediamine, triethylenediamine, hexamethylenetetramine, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene, pyridine, 4-dimethylaminopyridine, 1-methylimidazole, 1,2-dimethylimidazole, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0053] Next, the self-repairing resin composition of the first invention will be described. The self-repairing resin composition of the present invention can be produced using the production method of the first invention described above. The self-repairing resin composition of the present invention can be, for example, a resin composition represented by any one of formulas (VI) to (VIII) produced by the above-mentioned production modes a) to c). Formulas (VI) to (VIII) represent polymers having three structural units. The molecular weight is 1,000 to 100,000, preferably 5,000 to 20,000. In addition, R 1 ~R 9 is the same as that explained in the above manufacturing method, and therefore the explanation will be omitted. [ka] [ka] [ka]

[0054] Specifically, examples of the resin composition represented by formula (VI) produced in production mode a) include the compounds shown below.

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] Examples of the resin composition represented by formula (VII) produced in production mode b) include the compounds shown below.

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] Specific examples of the resin composition represented by formula (VIII) produced in production mode c) include the compounds shown below.

[0068] [ka]

[0069] <Method for producing the self-repairing resin composition of the second invention> The second method for producing a self-repairing resin composition of the present invention is a method using diisothiocyanates having a tertiary amine structure. As the second method for producing a self-repairing resin composition of the present invention, an embodiment in which the diisothiocyanates include diisothiocyanates (A) that do not have a tertiary amine structure and diisothiocyanates (B) that have a tertiary amine structure can be mentioned.

[0070] In the second method for producing a self-healing resin composition of the present invention, diisothiocyanates, dithiols, and a crosslinking agent can be reacted without using an organic solvent. Since no organic solvent is used, it is possible to reduce the environmental impact. Furthermore, by using diisothiocyanates having a tertiary amine structure, it is not necessary to use a low molecular weight amine as a catalyst in the polyaddition reaction, as used in the first invention, thereby further reducing the environmental impact. Furthermore, since the polyfunctional isothiocyanate having a tertiary amine structure is incorporated into the cured composition, it does not become liberated like a low molecular weight amine-based curing agent.

[0071] The self-repairing resin composition produced by the second production method of the present invention exhibits high adhesive strength to adherends such as glass and metals such as stainless steel, aluminum, and copper, and can therefore be suitably used as an adhesive. When used as an adhesive for a product, the high strength is maintained from the time of product production until use, and the product can be easily disassembled, for example, by heating, as needed. Specifically, the product can be easily disassembled by heating at, for example, about 150°C for 1 to 10 minutes. The heating temperature for disassembly is preferably 120°C or higher, more preferably 130°C or higher. There is no particular upper limit, but it is, for example, about 200°C.

[0072] Furthermore, the self-healing resin composition produced by the second production method of the present invention has self-healing properties, so it can be reused after dismantling, promoting the recycling of resources and contributing to reducing environmental impact. That is, when the fractured surfaces of the dismantled article are left in contact with each other, the original adhesive strength is restored, making it an adhesive that can be easily dismantled and reused. Furthermore, by washing the fractured surfaces of the dismantled article with an organic solvent, the composition (adhesive) of the present invention can be completely removed from the adherend, so the adherend from which the adhesive has been removed can be easily recovered.

[0073] [Diisothiocyanates] Diisothiocyanates generally include diisothiocyanates (A) that do not have a tertiary amine structure and diisothiocyanates (B) that have a tertiary amine structure. Examples of the diisothiocyanates (A) that do not have a tertiary amine structure include the diisothiocyanates with an ether structure and the diisothiocyanates without an ether structure used in the method for producing a self-repairing resin composition of the first aspect of the present invention.

[0074] Examples of the diisothiocyanates (B) having a tertiary amine structure include compounds represented by the following formula (IX).

[0075] [ka]

[0076] In formula (IX), R 10 is a linking group represented by the following formula (e-1) or formula (e-2).

[0077] [ka]

[0078] [ka]

[0079] In formula (e-1), R 11 and R 12 are each independently -C k H 2k - (k is an integer from 3 to 6), R 13 is a methyl group or -C k H 2k -CH3 (wherein k is an integer of 1 to 3). 14 and R 15 are each independently -C k H 2k - (k represents an integer from 3 to 6).

[0080] [Dithiols] As the dithiol used in the production method of the second invention, the same dithiol as that used in the production method of the self-repairing resin composition of the first invention can be used.

[0081] [Crosslinking agent] The crosslinking agent used in the production method of the second invention can be the same as the crosslinking agent used in the production method of the self-repairing resin composition of the first invention.

[0082] In the second production method of the present invention, four types of diisothiocyanates (A), diisothiocyanates (B), dithiols, and crosslinking agent may be mixed and reacted simultaneously, or three types may be mixed together and then the remaining type may be mixed. Alternatively, two types may be mixed together and then one more type may be mixed, and finally the remaining one may be mixed. Alternatively, two types may be mixed together. In the production method of the present invention, a mixture of diisothiocyanates (A) and diisothiocyanates (B) and a mixture of dithiols and crosslinking agent are preferably mixed and reacted.

[0083] An example of a mode in which a mixture of diisothiocyanates (A) and diisothiocyanates (B) and a mixture of dithiols and a crosslinking agent are mixed and reacted is to place the diisothiocyanates and dithiols in separate containers, and place the crosslinking agent in one of the containers or in a further separate container, and then mix and react the diisothiocyanates, dithiols, and crosslinking agent.

[0084] The blending ratio of the dithiol is preferably 0.10 to 0.95 equivalents, more preferably 0.30 to 0.90 equivalents, and even more preferably 0.60 to 0.85 equivalents, in molar ratio relative to the diisothiocyanates (A).

[0085] The mixing ratio of the crosslinking agent is preferably 0.04 to 0.18 equivalents, more preferably 0.06 to 0.15 equivalents, and even more preferably 0.08 to 0.12 equivalents, in molar ratio relative to the diisothiocyanates (A).

[0086] The reaction temperature is usually about 0 to 100° C., preferably room temperature (20 to 25° C.) The reaction time is, for example, about 1 to 48 hours, preferably about 12 to 36 hours.

[0087] Next, the self-repairing resin composition of the second invention will be described. The self-repairing resin composition of the second invention can be produced using the production method of the second invention. Examples of the self-repairing resin composition of the second invention include resin compositions represented by any of formulas (X) to (XII) produced by the above production modes a) to c). Formulas (X) to (XII) represent polymers having four structural units. The molecular weight is 1,000 to 100,000, preferably 5,000 to 20,000. Note that R in the formula 1 ~R 10 is the same as that explained in the above manufacturing method, and therefore the explanation will be omitted.

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] Specifically, examples of the resin composition represented by formula (X) produced in production mode a) include the compounds shown below.

[0092] [ka]

[0093] [ka]

[0094] Furthermore, examples of the resin composition represented by formula (XI) produced in production mode b) include the compounds shown below.

[0095] [ka]

[0096] [ka]

[0097] Examples of the resin composition represented by formula (XII) produced in production mode c) include the compounds shown below.

[0098] [ka]

[0099] [ka] [Example]

[0100] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0101] <Production of the self-repairing resin composition of the first invention> Example 1 The resin composition of Example 1 (NPDTU-1) was synthesized as follows. A tetrahydrofuran (2.00 mL) solution of diisothiocyanate (5.00 mmol) having a triethylene glycol structure and a tetrahydrofuran (2.00 mL) solution of dithiol (4.00 mmol) having a triethylene glycol structure, PE (0.5 mmol) as a crosslinking agent, and triethylamine (7.00 μL) were mixed in a glass Petri dish with an inner diameter of 70 mm, left to stand at room temperature for 24 hours, and then vacuum-dried overnight at 25°C to obtain a sheet-shaped resin composition (NPDTU-1) of Example 1.

[0102] [ka]

[0103] Example 2 A sheet-shaped resin composition (NPDTU-2) of Example 2 represented by the following chemical formula was obtained in the same manner as in Example 1-1, except that MP (0.5 mmol) was used instead of PE as the crosslinking agent.

[0104] [ka]

[0105] Example 3 A sheet-shaped resin composition (NPDTU-3) of Example 3 represented by the following chemical formula was obtained in the same manner as in Example 1-1, except that BU (0.5 mmol) was used as the crosslinking agent instead of PE.

[0106] [ka]

[0107] FIG. 1 shows photographs of the sheet-shaped resin compositions of Examples 1 to 3. As shown in FIG. 1, the resin compositions of Examples 1 to 3 gave transparent, flexible, self-supporting sheets.

[0108] Examples 4 to 12 Resin compositions (NPDTU-4 to NPDTU-12) of Examples 4 to 12 of the present invention, represented by the following chemical formulas, were obtained in the same manner as in Example 1, except that the corresponding diisothiocyanates, dithiols, and crosslinking agents were used instead.

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] <Evaluation of Resin Composition Properties> (Analysis of the chemical structure of the resin composition) The chemical structures of the resin compositions of the examples prepared above were measured by attenuated total reflectance (ATR) using a Fourier transform infrared (FTIR) spectrometer (Agilent, Cary 630). In each resin composition, peaks due to the thiocarbonyl group (C=S) and NH group of the dithiourethane bond were observed at 1500 cm. -1 near and 3200 cm -1 It is observed in the vicinity of 2100-2200 cm -1 Isothiocyanate groups (C=N=S) observed near 2560 cm -1 It was confirmed that the peak of the thiol group (SH) observed around this point had completely disappeared.

[0119] (Analysis of thermal properties of resin compositions) The glass transition temperatures of the resin compositions prepared in the examples were measured using a differential scanning calorimeter (Shimadzu, DSC-60Plus). A 5 mg sample was placed on an aluminum pan and heated twice from -50°C to 100°C at a rate of 10°C / min under a nitrogen stream. A baseline shift due to the glass transition was observed in each resin composition, confirming the glass transition temperature corresponding to the chemical structure of the resin composition.

[0120] (Analysis of mechanical properties of resin compositions) The breaking strain and breaking stress of the resin compositions of the examples prepared above were measured by tensile testing using a force tester (A&D, MCT-1150). Test pieces of 1.0 mm thick resin compositions were processed into No. 8 dumbbell shapes, and tensile tests were performed at a crosshead speed of 100 mm / min. Young's modulus was determined from the initial slope of the stress-strain curve obtained by the tensile test. Since no clear yield point was observed in any of the resin compositions, it was confirmed that they were soft and tenacious materials.

[0121] (Analysis of optical properties of resin compositions) The refractive index of the resin compositions of the examples prepared above was measured using a digital Abbe refractometer (Anton Paar, Abbemat MW) at 25° C. with the D line (589 nm) of a light source lamp. It was confirmed that most of the resin compositions exhibited a refractive index exceeding 1.60.

[0122] The analytical results of the above resin composition are shown in Table 1.

[0123] [Table 1]

[0124] Self-repair test A test was carried out to evaluate the self-repairing properties of the resin compositions of the examples produced above. The fracture surfaces of the test pieces fractured in the tensile test were brought into contact and left to stand at 25°C for 24 hours, resulting in a test piece with the fracture surfaces firmly bonded. The tensile test of the test piece after the repair operation was carried out using the same method as the tensile test used to measure the fracture strain and fracture stress described above, and the self-repair rate was evaluated as [fracture stress of the test piece after the repair operation] / [fracture stress of the test piece immediately after manufacture]. The results are shown in Table 2. The stress-strain curves obtained by the tensile tests are shown in FIGS.

[0125] [Table 2]

[0126] As shown in Table 2 and FIGS. 2 to 13, it was confirmed that the resin composition of the present invention has high self-repairing properties.

[0127] <Repeated durability test of self-repairing properties> The same procedure as in the self-repairing property test was repeated four times to evaluate the self-repairing property of the resin composition and its repeated durability. The repeated durability test was carried out using the resin composition of Example 1 (NPDTU-1) and the resin composition of Example 2 (NPDTU-2) as test pieces. The results are shown in Table 3.

[0128] [Table 3]

[0129] The stress-strain curves obtained from the repeated durability tests are shown in FIGS.

[0130] As shown in FIGS. 14 and 15, it was confirmed that the resin compositions of Examples 1 and 2 of the present invention had high repeated durability.

[0131] <Load-bearing test> A load-bearing test was carried out on a resin composition produced in the same manner as in Example 1. Fig. 16 is a diagram for explaining an outline of the load-bearing test. The outline of the test is as follows. As shown in Figure 16, a resin composition was produced using a glass Petri dish with an inner diameter of 40 mm in the same manner as in Example 1. The resulting resin composition was cut into two pieces with a cutter knife, and the two fracture surfaces were brought into contact and allowed to stand at 25°C for a certain period of time to confirm that the fracture surfaces had joined. The joined resin composition was cut into a plate measuring 10 mm wide x 30 mm long, and a 1 kg weight was hung from it. The time until the repaired resin composition broke again was measured up to a maximum of 360 minutes.

[0132] In NPDTU-1, the repair time was 20 hours and the fracture occurred after 40 minutes, 24 hours and the fracture occurred after 120 minutes, and 48 hours and the fracture did not occur within 360 minutes.

[0133] <Recycling test> A recycling test was carried out on the resin composition of Example 4. Fig. 17 is a diagram for explaining the outline of the recycling test. The outline of the test is as follows. The sheet used for the tensile test and all remaining sheets from the initial cutout were shredded and placed in a recovery flask with DMF (2 mL) and heated with stirring at 150°C. After a homogeneous solution was formed in about 10 minutes, the mixture was transferred to a petri dish, and a DMF (0.5 mL) solution of EtN (3.48 μL, 0.025 mmol) was added. The mixture was allowed to react at 25°C for 24 hours, and then vacuum dried overnight at 25°C to obtain a regenerated sheet.

[0134] As shown in FIG. 17, it was confirmed that the resin composition of the present invention is chemically recyclable.

[0135] <Production of the self-repairing resin composition of the second invention> Diisothiocyanates (B) having a tertiary amine structure were synthesized as follows.

[0136] (Piperazine-type diisothiocyanate) 1,4-Bis(3-aminopropyl)piperazine (10 mmol) and triethylamine (20 mmol) were dissolved in 20 mL of chloroform in a two-necked recovery flask. The atmosphere inside the vessel was replaced with argon and cooled to 0 °C using an ice bath. Carbon disulfide (20 mmol) was slowly added dropwise at 0 °C, followed by stirring at room temperature for 2 hours. Ethyl chloroformate (20 mmol) was then slowly added dropwise again at 0 °C, followed by stirring for 30 minutes and then at room temperature for 24 hours. The mixture was washed using a separatory funnel with 20 mL of purified water three times and 20 mL of saturated saline twice, and then dehydrated and dried over magnesium sulfate. The desiccant was removed by filtration, and the filtrate was concentrated using a rotary evaporator. The target product was purified by column chromatography to obtain the piperazine-type diisothiocyanate as a pale yellow powder solid. The structure of the obtained compound was confirmed by NMR spectrum and FT-IR spectrum.

[0137] [ka]

[0138] (NMe type diisothiocyanate) NMe-type diisothiocyanate was obtained in the same manner as the piperazine-type diisothiocyanate, except that 3,3'-diaminodipropylamine (10 mmol) was used instead of 1,4-bis(3-aminopropyl)piperazine as the diamine having a tertiary amine structure. The structure of the obtained compound was confirmed by NMR spectrum and FT-IR spectrum.

[0139] [ka]

[0140] Example 13 The resin composition of Example 13 was synthesized as follows. Ether-type diisothiocyanate and piperazine-type diisothiocyanate (1 mol%) were mixed to prepare solution A. Furthermore, ether-type dithiol and pentaerythritol tetra(3-mercaptopropionate) (5 mol%) as a crosslinker were mixed to prepare solution B.

[0141] [ka]

[0142] The prepared solutions A and B were mixed so that the functional group equivalents of the isothiocyanate group and the thiol group were equal, thereby producing the adhesive composition of Example 13 represented by the following chemical formula.

[0143] [ka]

[0144] Example 14 Solution A, shown in the following chemical formula, was prepared by mixing ether-type diisothiocyanate as the main agent and NMe-type diisothiocyanate (1 mol%) as the curing agent. Solution B, shown in the following chemical formula, was prepared by mixing ether-type dithiol as the main agent and pentaerythritol tetra(3-mercaptopropionate) (5 mol%) as the crosslinking agent.

[0145] [ka]

[0146] The prepared solutions A and B were mixed so that the functional group equivalents of the isothiocyanate group and the thiol group were equal, thereby producing the adhesive composition of Example 14 represented by the following chemical formula.

[0147] [ka]

[0148] (Reference Example 1: Composition according to the first invention) Solution A was prepared by diluting ether-type diisothiocyanate with THF. Solution B was prepared by mixing ether-type dithiol as the main agent, pentaerythritol tetra(3-mercaptopropionate) (5 mol%) as the crosslinker, and triethylamine (1 mol%), and then diluting the mixture with THF.

[0149] [ka]

[0150] The prepared solutions A and B were mixed so that the functional group equivalents of the isothiocyanate group and the thiol group were equal, thereby producing the adhesive composition of Reference Example 1 represented by the following chemical formula.

[0151] [ka]

[0152] <Adhesion strength evaluation> The adhesive strength was evaluated using the resin compositions of Examples 13 and 14. Specifically, the adhesive strength was evaluated by a tensile shear test and a load-bearing test. The method for preparing the test pieces and the outline of the test are as follows.

[0153] The adherends used were stainless steel (SUS304), aluminum (A1050), copper (C1100), and glass (S1214). The dimensions of the adherends were stainless steel and aluminum (thickness × width × length = 2.0 × 25 × 100 mm), copper (1.5 × 25 × 100 mm), and glass (1.5 × 26 × 76 mm). The length was defined as d / 2, which is half the width d of the adherend, and the adhesive area was defined as the width × d / 2 (Figure 18). 10 μL of the adhesive composition composed of the prepared mixture of liquids A and B was applied to one adherend, which was then overlapped with another adherend without the adhesive composition. The adhesive area was then secured with two double clips and left to stand in an oven set at room temperature of 25°C for 24 hours to prepare a test specimen.

[0154] The test piece with stainless steel (SUS304) as the adherend was designated as test piece a, the test piece with aluminum (A1050) as the adherend was designated as test piece b, the test piece with copper (C1100) as the adherend was designated as test piece c, and the test piece with glass (S1214) as the adherend was designated as test piece d. Figure 19 shows photographs of the test pieces a to d that were prepared.

[0155] In addition, after mixing the A and B liquids of Example 14, test piece e was prepared using glass (S1214) as the adherend, and after mixing the A and B liquids of Reference Example 1, test piece f was prepared using glass (S1214) as the adherend.

[0156] (Tensile shear test) Both ends of the test piece were fixed in a universal testing machine, and the machine was moved at a head speed of 5 mm / min to measure the load at which the adhesive broke. Six test pieces were prepared, and of the values ​​obtained from six measurements, two values ​​that deviated significantly from the average value were excluded, and the average value was evaluated as the adhesive strength. The results are shown in Table 4. The test method conforms to JIS K 6850.

[0157] [Table 4]

[0158] (Load-bearing test) A 1 kg weight was hung from the test piece, and the adhesive strength was evaluated by observing the degree of displacement of the adhesive surface after 24 hours. No change was observed in any of the test pieces prepared within 24 hours (Figure 20).

[0159] The composition of the present invention exhibited sufficient adhesive strength with a wide range of adherends. In particular, test piece c exhibited high adhesive strength due to its strong affinity with copper, which is attributable to its high sulfur content. Furthermore, the adhesive using diisothiocyanates with a tertiary amine structure (test piece e) exhibited superior adhesive strength to the adhesive without this (test piece f).

[0160] <Disassembly test> A disassembly test was carried out using a glass test piece prepared in the same manner as test piece d. Specifically, the test was carried out as follows.

[0161] A glass test piece prepared in the same way as test piece d was placed in an oven at 150°C for 1 minute, and the bonded area was confirmed to have broken without applying any load (release of the bond). The broken bonded areas were reconnected, fixed with two double clips, and left to stand in an oven set at room temperature (25°C) for 24 hours, allowing the glass test piece to be re-bonded (Figure 21).

[0162] A glass test piece prepared in the same manner as test piece d was placed in a 150°C oven for 20 minutes, and the adherend, with the adhesive fractured, was removed from the oven (Figure 22(a)). Immediately afterwards, it was immersed in THF for washing. It was confirmed that no adhesive remained on the adherend when it was removed from the solvent (Figure 22(b)). The THF solution after washing was purified by silica gel column chromatography using a solvent made of a 1:1 volumetric mixture of ethyl acetate and hexane, and the ether-type diisothiocyanate was isolated and recovered. Thin layer chromatography (TLC) confirmed that the diisothiocyanate had been isolated from the components contained in the THF solution after washing (Figure 22(c)).

[0163] It was confirmed that the composition of the present invention allows test specimens to be disassembled (released from adhesion) by heat. It was also confirmed that the adhesive can be completely removed from the adherend after disassembly by using an appropriate solvent, and that the adherend from which the adhesive composition has been removed can be reused as a material. It was also confirmed that the raw materials of the composition of the present invention can be separated and recovered.

[0164] <Re-adhesion test> A re-adhesion test was carried out using a glass test piece prepared in the same manner as test piece c. Specifically, the test was carried out as follows.

[0165] Both ends of a copper test piece, prepared in the same way as test piece c, were fixed to a universal testing machine, and the machine was moved at a head speed of 100 mm / min, causing the adhesive to quickly break at the bonded portion. It was confirmed that adhesive remained on both sides of the broken test piece. The broken adhesive portions were reconnected, and the bonded portions were fixed with two double clips. The copper test piece was then re-bonded by leaving it in an oven set at room temperature of 25°C for 24 hours (Figure 23). The adhesive strength of the re-bonded test piece was evaluated using a load-bearing test, and it did not break within 24 hours either before or after disassembly.

[0166] It has been confirmed that the composition of the present invention can be used as an adhesive that can re-adhere even after disassembly, taking advantage of its self-repairing properties. [Industrial Applicability]

[0167] The resin composition of the present invention can be used as a novel resin material having self-repairing properties and is therefore industrially useful.

Claims

1. A method for producing a resin composition having self-repairing properties by reacting a diisothiocyanate, a dithiol, and a crosslinking agent, comprising: A method for producing a self-repairing resin composition, wherein at least one of the diisothiocyanates and the dithiols has an ether structure.

2. 2. The method for producing a self-repairing resin composition according to claim 1, wherein a diisothiocyanate, a dithiol, and a crosslinking agent are reacted in an organic solvent.

3. The method for producing a self-repairing resin composition according to claim 1, characterized in that the diisothiocyanates include diisothiocyanates that do not have a tertiary amine structure and diisothiocyanates that have a tertiary amine structure.

4. 4. The method for producing a self-repairing resin composition according to claim 3, wherein the diisothiocyanates, the dithiols, and the crosslinking agent are reacted without using an organic solvent.

5. The diisothiocyanates and the dithiols are contained in separate containers, and the crosslinking agent is contained in one of the containers or in a further container. The method for producing a self-repairing resin composition according to claim 3, characterized in that the diisothiocyanates, the dithiols, and the crosslinking agent are mixed and reacted.

6. A method using diisothiocyanates having an ether structure, The diisothiocyanates having an ether structure are The following formula (I) 【Chemistry 1】 [In formula (I), R １ and R ２ are each independently -C ｋ H ２ｋ - (k represents an integer of 1 to 3), and m represents an integer of 1 to 5.

4. The method for producing a self-repairing resin composition according to claim 2, wherein the compound is a compound represented by the formula:

7. A method using dithiols having an ether structure, The dithiol having an ether structure is The following formula (II) 【Chemistry 2】 [In formula (II), R ３ teeth, The following formula (a-1) 【Transformation 3】 (In formula (a-1), R ４ and R ５ are each independently -C ｋ H ２ｋ - (k represents an integer of 1 to 3), and i represents an integer of 1 to 5. , or The following formula (a-2) 【Chemistry 4】 (In formula (a-2), j represents an integer of 1 to 5.) represents a linking group represented by the following formula:

7. The method for producing a self-repairing resin composition according to claim 6, wherein the compound is a compound represented by the formula:

8. A method using dithiols having an ether structure, The dithiol having an ether structure is The following formula (II) 【Transformation 5】 [In formula (II), R ３ teeth, The following formula (a-1) 【Transformation 6】 (In formula (a-1), R ４ and R ５ are each independently -C ｋ H ２ｋ - (k represents an integer of 1 to 3), and i represents an integer of 1 to 5. , or The following formula (a-2) 【Transformation 7】 (In formula (a-2), j represents an integer of 1 to 5.) represents a linking group represented by the following formula:

4. The method for producing a self-repairing resin composition according to claim 2, wherein the compound is a compound represented by the formula:

9. 4. The method for producing a self-repairing resin composition according to claim 2, wherein the crosslinking agent is a polyfunctional thiol having three or more thiol groups in the molecule.

10. The crosslinking agent is represented by the following formula (V): 【Transformation 8】 [In formula (V), R ９ teeth, The following formulas (d-1) to (d-3) 【Chemistry 9】 represents any one of the linking groups represented by the following formula:

8. The method for producing a self-repairing resin composition according to claim 7, wherein the compound is a compound represented by the formula:

11. The crosslinking agent is represented by the following formula (V): 【Chemistry 10】 [In formula (V), R ９ teeth, The following formulas (d-1) to (d-3) 【Chemistry 11】 represents any one of the linking groups represented by the following formula:

9. The method for producing a self-repairing resin composition according to claim 8, wherein the compound is a compound represented by the formula:

12. The crosslinking agent is represented by the following formula (V): 【Chemistry 12】 [In formula (V), R ９ teeth, The following formulas (d-1) to (d-3) 【Chemistry 13】 represents any one of the linking groups represented by the following formula:

7. The method for producing a self-repairing resin composition according to claim 6, wherein the compound is a compound represented by the formula:

13. The method for producing a self-repairing resin composition according to claim 2 or 3, characterized in that 0.10 to 0.95 equivalents of the dithiols and 0.05 to 0.15 equivalents of the crosslinking agent are reacted in a molar ratio with respect to the diisothiocyanates.

14. A method using a diisothiocyanate having an ether structure and a dithiol having an ether structure, The following formula (VI) 【Chemistry 14】 [Formula (VI) represents a polymer having three constitutional units.] 11. The method for producing a self-repairing resin composition according to claim 10, wherein the resin composition is represented by the formula:

15. A method using a diisothiocyanate having no ether structure and a dithiol having an ether structure, The following formula (VII) 【Chemistry 15】 [Formula (VII) represents a polymer having three constitutional units, In the formula, R ６ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 12) , or The following formulas (b-1) to (b-4) 【Chemistry 16】 represents any one of the linking groups represented by the following formula:

12. The method for producing a self-repairing resin composition according to claim 11, wherein the resin composition is represented by the formula:

16. A method using a diisothiocyanate having an ether structure and a dithiol not having an ether structure, The following formula (VIII) 【Chemistry 17】 [Formula (VIII) represents a polymer having three constitutional units, In the formula, R ７ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 10) , or The following formula (c) [Chemistry 18] (In formula (c), R ８ is -C ｋ H ２ｋ - (k represents an integer of 3 to 10). represents a linking group represented by the following formula:

13. The method for producing a self-repairing resin composition according to claim 12, wherein the resin composition is represented by the formula:

17. The diisothiocyanates having a tertiary amine structure are The following formula (IX) 【Chemistry 19】 [In formula (IX), R １０ teeth, The following formula (e-1) 【Chemistry 20】 (In formula (e-1), R １１ and R １２ are each independently -C ｋ H ２ｋ - (k is an integer of 3 to 6), R １３ is a methyl group or -C ｋ H ２ｋ -CH ３ (k represents an integer of 1 to 3). , or The following formula (e-2) 【Chemistry 21】 (In formula (e-2), R １４ and R １５ are each independently -C ｋ H ２ｋ - (k represents an integer of 3 to 6). represents a linking group represented by the following formula:

4. The method for producing a self-repairing resin composition according to claim 3, wherein the compound is a compound represented by the formula:

18. A method using a diisothiocyanate having an ether structure, a dithiol having an ether structure, and a diisothiocyanate having a tertiary amine structure, The following formula (X) 【Chemistry 22】 [Formula (X) represents a polymer having four constitutional units, R １０ teeth, The following formula (e-1) 【Chemistry 23】 (In formula (e-1), R １１ and R １２ are each independently -C ｋ H ２ｋ - (k is an integer of 3 to 6), R １３ is a methyl group or -C ｋ H ２ｋ -CH ３ (k represents an integer of 1 to 3). , or The following formula (e-2) 【Chemistry 24】 (In formula (e-2), R １４ and R １５ are each independently -C ｋ H ２ｋ - (k represents an integer of 3 to 6). represents a linking group represented by the following formula:

11. The method for producing a self-repairing resin composition according to claim 10, wherein the resin composition is represented by the formula:

19. A method using a diisothiocyanate having no ether structure, a dithiol having an ether structure, and a diisothiocyanate having a tertiary amine structure, The following formula (XI) 【Chemistry 25】 [Formula (XI) represents a polymer having four constitutional units, In the formula, R ６ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 12) , or The following formulas (b-1) to (b-4) 【Chemistry 26】 represents any one of the linking groups represented by R １０ teeth, The following formula (e-1) 【Chemistry 27】 (In formula (e-1), R １１ and R １２ are each independently -C ｋ H ２ｋ - (k is an integer of 3 to 6), R １３ is a methyl group or -C ｋ H ２ｋ -CH ３ (k represents an integer of 1 to 3). , or The following formula (e-2) 【Chemistry 28】 (In formula (e-2), R １４ and R １５ are each independently -C ｋ H ２ｋ - (k represents an integer of 3 to 6). represents a linking group represented by the following formula:

12. The method for producing a self-repairing resin composition according to claim 11, wherein the resin composition is represented by the formula:

20. A method using a diisothiocyanate having an ether structure and a dithiol not having an ether structure, and using a diisothiocyanate having a tertiary amine structure, The following formula (VIII) 【Chemistry 29】 [Formula (VIII) represents a polymer having three constitutional units, In the formula, R ７ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 10) , or The following formula (c) 【Transformation 30】 (In formula (c), R ８ is -C ｋ H ２ｋ - (k represents an integer of 3 to 10). represents a linking group represented by R １０ teeth, The following formula (e-1) 【Chemistry 31】 (In formula (e-1), R １１ and R １２ are each independently -C ｋ H ２ｋ - (k is an integer of 3 to 6), R １３ is a methyl group or -C ｋ H ２ｋ -CH ３ (k represents an integer of 1 to 3). , or The following formula (e-2) 【Chemistry 32】 (In formula (e-2), R １４ and R １５ are each independently -C ｋ H ２ｋ - (k represents an integer of 3 to 6). represents a linking group represented by the following formula:

13. The method for producing a self-repairing resin composition according to claim 12, wherein the resin composition is represented by the formula:

21. A self-repairing resin composition represented by any one of the following formulas (VI) to (VIII): 【Transformation 33】 【Transformation 34】 【Chemistry 35】 [Each of formulas (VI) to (VIII) represents a polymer having three structural units, In each formula, R １ and R ２ teeth, Each independently -C ｋ H ２ｋ - (k is an integer of 1 to 3), and m is an integer of 1 to 5; R ３ teeth, The following formula (a-1) 【Transformation 36】 (In formula (a-1), R ４ and R ５ are each independently -C ｋ H ２ｋ - (k represents an integer of 1 to 3), and i represents an integer of 1 to 5. , or The following formula (a-2) 【Chemistry 37】 (In formula (a-2), j represents an integer of 1 to 5.) represents a linking group represented by R ９ teeth, The following formulas (d-1) to (d-3) 【Transformation 38】 represents any one of the linking groups represented by R ６ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 12) , or The following formulas (b-1) to (b-4) 【Chemistry 39】 represents any one of the linking groups represented by R ７ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 10) , or The following formula (c) 【Chemistry 40】 (In formula (c), R ８ Ha-C ｋ H ２ｋ - (k represents an integer of 3 to 10). represents a linking group represented by the following formula:

22. A self-repairing resin composition represented by any one of the following formulas (X) to (XII): 【Chemistry 41】 【Chemistry 42】 【Chemistry 43】 [Each of formulas (X) to (XII) represents a polymer having four structural units, In each formula, R １ and R ２ teeth, Each independently -C ｋ H ２ｋ - (where k is an integer of 1 to 3), and m is an integer of 1 to 5; R ３ teeth, The following formula (a-1) 【Chemistry 44】 (In formula (a-1), R ４ and R ５ are each independently -C ｋ H ２ｋ - (k represents an integer of 1 to 3), and i represents an integer of 1 to 5. , or The following formula (a-2) 【Chemistry 45】 (In formula (a-2), j represents an integer of 1 to 5.) represents a linking group represented by R ９ teeth, The following formulas (d-1) to (d-3) 【Chemistry 46】 represents any one of the linking groups represented by R ６ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 12) , or The following formulas (b-1) to (b-4) 【Chemistry 47】 represents any one of the linking groups represented by R ７ teeth, -C ｋ H ２ｋ - (k represents an integer of 3 to 10) , or The following formula (c) 【Chemistry 48】 (In formula (c), R ８ Ha-C ｋ H ２ｋ - (k represents an integer of 3 to 10). represents a linking group represented by R １０ teeth, The following formula (e-1) 【Chemistry 49】 (In formula (e-1), R １１ and R １２ are each independently -C ｋ H ２ｋ - (k is an integer of 3 to 6), R １３ is a methyl group or -C ｋ H ２ｋ -CH ３ (k represents an integer of 1 to 3). , or The following formula (e-2) [Transformation 50] (In formula (e-2), R １４ and R １５ are each independently -C ｋ H ２ｋ - (k represents an integer of 3 to 6). represents a linking group represented by the following formula:

23. 23. The self-repairing resin composition according to claim 22, which is an adhesive.

24. The self-repairing resin composition according to claim 23, characterized in that the adhesion is released by heating.

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