Hot-melt injectable adhesive, method for preparing the same and use thereof

Abstract

The application discloses a hot-melt injectable adhesive and a preparation method and application thereof, and belongs to the technical field of adhesives. The hot-melt injectable adhesive comprises a co-hot-melt product of alpha-liponic acid, N-alkyl liponic amide and tris(2-carboxyethyl) phosphonium hydrochloride or citric acid, and is specifically prepared by mixing and hot-melting alpha-liponic acid, N-alkyl liponic amide and tris(2-carboxyethyl) phosphonium hydrochloride or citric acid and then cooling and shaping. The hot-melt injectable adhesive is a temperature-responsive crystallization curing mode, the curing process does not involve material exchange with a water phase, and the use of a solvent is omitted, so that the hot-melt injectable adhesive has the advantages of green environmental protection, simple preparation, good universality, strong adhesion and convenient use and operation, and is expected to have great application potential in daily life and industrial engineering fields.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adhesives, in particular to a hot-melt injectable adhesive and its preparation method and application. BACKGROUND

[0002] Underwater adhesives have a broad application prospect in daily life, biomedical and industrial engineering. However, achieving underwater adhesion not only needs to overcome the influence of the hydration layer on the surface of the material on the interfacial adhesion, but also requires the adhesive itself to have suitable cohesive force or the ability to cure underwater, making the development and design of underwater adhesives extremely challenging.

[0003] At present, many biomimetic underwater adhesives are designed inspired by marine organisms in the related art, such as the cross-linked copolymer (ATAC-co-PEA) hydrogel of 2-(acryloyloxy) ethyl trimethylammonium chloride and 2-phenoxyethyl acrylate designed by Gong Jianping et al., and the supramolecular cross-linked hydrogel of chitosan / tannic acid / fibroin protein designed by Yang Huanghao et al. These hydrogels generally effectively achieve underwater adhesion through rich weak interactions or covalent bonding.

[0004] However, the existing biomimetic underwater adhesives generally have problems such as complex preparation, weak adhesion strength, and poor universality, which limit the development and application of underwater adhesives. SUMMARY

[0005] The present application discloses a hot-melt injectable adhesive and its preparation method and application, aiming to solve the technical problems of complex preparation, weak adhesion strength, and poor universality of existing biomimetic underwater adhesives.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0007] The first aspect of the present application provides a hot-melt injectable adhesive, which comprises a co-hot-melt product of the following components:

[0008] (i) alpha-lipoic acid;

[0009] (ii) N-alkyl lipoamide;

[0010] (iii) tris(2-carboxyethyl) phosphonium hydrochloride or citric acid.

[0011] In a preferred embodiment, the hot-melt injectable adhesive comprises a co-hot-melt product of the following components:

[0012] (i) 42-49 mole parts of alpha-lipoic acid;

[0013] (ii) 1-8 mole parts of N-alkyl lipoamide;

[0014] (iii) tris (2-carboxyethyl) phosphine hydrochloride or citrate 1 mole.

[0015] In a preferred embodiment, the N-alkyl thioctic amide has the following chemical structure:

[0016]

[0017] wherein R is a C6-C18 alkyl group.

[0018] The second aspect of the present application provides a method for preparing the hot-melt injectable adhesive as described in the present application, which comprises the following steps:

[0019] According to the raw material components of the hot-melt injectable adhesive as described in the present application, the α-lipoic acid, N-alkyl thioctic amide, and tris (2-carboxyethyl) phosphine hydrochloride or citrate are mixed and hot-melted, and then cooled, to obtain the hot-melt injectable adhesive.

[0020] In a preferred embodiment, the temperature for the mixing and hot-melting is 120-150℃.

[0021] The third aspect of the present application provides the use of the hot-melt injectable adhesive as described in the present application for the adhesion treatment of the contact surface to be adhered.

[0022] In a preferred embodiment, the hot-melt injectable adhesive is heated to 50-100℃ for hot-melting, and then injected onto the contact surface to be adhered, and then cooled, for the adhesion treatment of the contact surface to be adhered.

[0023] In a preferred embodiment, the contact surface to be adhered is located in an aqueous system.

[0024] In a preferred embodiment, the aqueous system comprises a fresh water system, an acidic water system, and / or a high-salt water system.

[0025] The fourth aspect of the present application provides a glass adhesion method, which comprises the adhesion treatment of the glass contact surface using the hot-melt injectable adhesive as described in the present application.

[0026] Compared with the prior art, the advantages or beneficial effects of the present application at least include:

[0027] The hot-melt injectable adhesive provided by the application effectively generates a co-melt product containing a small molecule eutectic phase of alpha-lipoic acid and N-alkyl lipoamide in phase by setting the ternary co-melt of alpha-lipoic acid, N-alkyl lipoamide and tris(2-carboxyethyl)phosphonium hydrochloride or citric acid, which can impart high flowability to the co-melt product by the melting of the contained small molecule eutectic phase at elevated temperature, thereby making it have good injectability; on the other hand, the flowable co-melt product can drain and wet the substrate well underwater, and then form extensive weak interactions with different substrate surfaces through polar groups (-COOH, -NH-CO-), and can achieve the effect of underwater persistent and stable solidification bonding through the recrystallization of the contained small molecule eutectic phase during cooling, thereby imparting it the ability of persistent and stable adhesion in underwater environment. In addition, the injectable co-melt product prepared by the application is a temperature-responsive crystallization and solidification mode, the entire solidification process does not involve material exchange with water phase, and the solvent composition is omitted, which has the advantages of green environmental protection, simple preparation, good universality, strong adhesion and convenient use and operation, and is expected to have great application potential in daily life and industrial engineering fields. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0029] Figure 1 The temperature rising rheological curves of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 provided by the application;

[0030] Figure 2 The shear viscosity statistical diagram of the 55℃ melt of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 provided by the application;

[0031] Figure 3 The water contact angle statistical diagram of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 provided by the application;

[0032] Figure 4 The lap shear strength test results of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 provided by the application, and the lap shear strength test results of underwater adhesion to glass under different solidification time of PLAO8;

[0033] Figure 5Physical picture of PLAO8 underwater adhesive weight provided for the present application;

[0034] Figure 6 Test results of lap shear strength of PLAO8 adhering glass in acidic and high salt water environment provided for the present application;

[0035] Figure 7 Shear viscosity curve of 55℃ melt of hot melt injectable adhesive PLAO8-CA provided for the present application;

[0036] Figure 8 Test results of lap shear strength of PLAO8-CA adhering glass after 24h curing provided for the present application;

[0037] Figure 9 Shear viscosity change curve of 55℃ melt of experimental group and control group (TCEP+LA, LA+LA-C 18 , TCEP+LA-C 18 ) provided for the present application;

[0038] Figure 10 Test results of lap shear strength of experimental group and control group (TCEP+LA, LA+LA-C 18 , TCEP+LA-C 18 ) adhering glass after 24h curing provided for the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments described in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0040] In the following description of the specification, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the cases of A alone, B alone and A and B at the same time. Wherein, A, B can be singular or plural; the symbol " / " represents the meaning of "or".

[0041] In the following description of the specification, the term "at least one" means one or more, and the term "multiple" means two or more. "At least one of the following" or similar expressions means any combination of the listed terms, including a single term or any combination of the listed terms. For example, "at least one of A, B, or C", or "at least one of A, B, and C", can mean any one of A, B, C, A+B, A+C, B+C, or A+B+C, where A, B, and C can be single or multiple.

[0042] In the following description of the specification, the order of the serial numbers does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence. The execution order of each process should be determined according to its function and internal logic, and does not constitute any limitation on the execution process of the embodiment.

[0043] In the following description of the specification, the numerical range should be understood to also specifically disclose each intermediate value between the upper limit and the lower limit of the range. Each smaller range between any stated value or intermediate value in a stated range and any other stated value or intermediate value in the stated range is also included in the embodiment, and the upper limit and the lower limit of the smaller range can be independently included or excluded from the range.

[0044] Unless otherwise specified, the technical / scientific terms used in the specification have meanings commonly understood by those skilled in the art. Although only preferred materials and methods are described in the specification, any method and material similar or equivalent to those described in the specific examples or test examples can also be used. All documents mentioned in the specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of conflict with any incorporated document, the content of the specification shall prevail.

[0045] In a first aspect, the embodiments of the present application provide a hot-melt injectable adhesive. The hot-melt injectable adhesive described in the present application comprises a co-hot-melt product of the following components:

[0046] (i) alpha-lipoic acid;

[0047] (ii) N-alkyl lipoamide;

[0048] (iii) tris(2-carboxyethyl)phosphonium hydrochloride or citric acid.

[0049] The co-hot-melt product is a solidified product obtained by co-hot-melting and cooling the alpha-lipoic acid, N-alkyl lipoamide, and tris(2-carboxyethyl)phosphonium hydrochloride or citric acid in the components.

[0050] In summary, the present application can generate a eutectic product containing small molecule eutectic phase of α-lipoic acid and N-alkyl lipoamide in phase by setting the ternary co-melt of α-lipoic acid, N-alkyl lipoamide and tris(2-carboxyethyl)phosphonium hydrochloride or citric acid, which can impart high flowability to the eutectic product at elevated temperature by melting of the contained small molecule eutectic phase, thereby making it have good injectability; on the other hand, the eutectic product with high flowability can fully drain and wet the substrate underwater, then form extensive weak interactions with different substrate surfaces through polar groups (-COOH, -NH-CO-), and can achieve underwater persistent and stable solidification bonding by recrystallization of the contained small molecule eutectic phase during cooling, thereby imparting it with persistent and stable adhesion in underwater environment. In addition, since the injectable eutectic product described in the present application is a temperature-responsive crystallization and solidification mode, the entire solidification process does not involve material exchange with water phase, and the solvent composition is omitted, which has the advantages of green environmental protection, simple preparation, good universality, strong adhesion and convenient use and operation, and is expected to have great application potential in daily life and industrial engineering fields.

[0051] The hot-melt injectable adhesive according to the present disclosure preferably comprises a co-melt product of the following components;

[0052] (i) 42-49 mole parts of α-lipoic acid;

[0053] (ii) 1-8 mole parts of N-alkyl lipoamide;

[0054] (iii) 1 mole part of tris(2-carboxyethyl)phosphonium hydrochloride or citric acid.

[0055] It should be noted that the mole parts described in the present application refer to the direct or indirect proportioning of the contained α-lipoic acid, N-alkyl lipoamide and tris(2-carboxyethyl)phosphonium hydrochloride or citric acid according to the mole parts, which can be a direct combination of 42-49 mole parts of α-lipoic acid, 1-8 mole parts of N-alkyl lipoamide and 1 mole part of tris(2-carboxyethyl)phosphonium hydrochloride or citric acid; or an indirect combination of 4.2-4.9 mole parts of α-lipoic acid, 0.1-0.8 mole parts of N-alkyl lipoamide and 0.1 mole part of tris(2-carboxyethyl)phosphonium hydrochloride or citric acid; or an indirect combination of 420-490 mole parts of α-lipoic acid, 10-80 mole parts of N-alkyl lipoamide and 10 mole parts of tris(2-carboxyethyl)phosphonium hydrochloride or citric acid, etc.

[0056] Wherein, the application can effectively adjust the mechanical properties and adaptability of the prepared hot-melt injectable adhesive by controlling the molar content of the contained α-lipoic acid, N-alkyl lipoamide and tris (2-carbonyl ethyl) phosphonium hydrochloride or citric acid.

[0057] According to the hot-melt injectable adhesive of the present disclosure, the N-alkyl lipoamide has the following chemical structure:

[0058]

[0059] In the formula, R is a C6-C18 alkyl group, specifically one of a straight-chain alkyl group and a branched-chain alkyl group containing 6-18 carbon atoms.

[0060] It should be noted that the application can effectively adjust the hydrophobic properties of the prepared flowable co-hot-melt product by controlling the number of carbon atoms of the substituent R shown in the chemical structure, so that the co-hot-melt product can fully drain and wet the substrate underwater, thereby achieving better and more stable adhesion effect in underwater environment. In specific examples, the N-alkyl lipoamide includes but is not limited to N-hexyl lipoamide, N-dodecyl lipoamide, N-octadecyl lipoamide, etc.

[0061] It should be noted that the application does not have special limitations on the preparation method of the N-alkyl lipoamide, which can be prepared according to known synthesis methods. The application takes the synthesis of N-octadecyl lipoamide as an example to provide a preparation method of N-alkyl lipoamide, which specifically includes:

[0062] α-lipoic acid (9.9 g, 48 mmol) and N-hydroxysuccinimide (5.5 g, 48 mmol) powders were added to 100 mL of dichloromethane, stirred and dissolved at 0°C, and then a solution of dicyclohexyl carbodiimide (12.4 g, 60 mmol) in 72 mL of dichloromethane was added dropwise. The reaction was carried out at room temperature for 1 h, and then placed in a 4°C environment overnight. Subsequently, the reaction mixture was filtered, and the solvent in the filtrate was evaporated under reduced pressure. The filter residue was washed with ether twice and naturally dried at room temperature to obtain a light yellow powder, i.e. lipoic acid succinimide ester.

[0063] Lipoic acid succinimide ester (4.85 g, 16 mmol) and octadecylamine (7.0 g, 23.4 mmol) were dissolved in 200 mL of dichloromethane, and the reaction was carried out at room temperature under nitrogen protection for 36 h. After the reaction, the organic phase was washed with 0.05M hydrochloric acid (500 mL), saturated ammonium chloride solution (500 mL) and saturated sodium chloride solution (500 mL) in sequence. The washed organic phase was dried over anhydrous magnesium sulfate, and the solvent was evaporated under vacuum to obtain N-octadecyl lipoamide.

[0064] Wherein, replacing the above-mentioned octadecylamine with one of the C6-17 amines, the remaining N-alkyl thioctic amides can be prepared, for example, replacing octadecylamine with n-hexylamine to synthesize N-hexyl thioctic amide; replacing octadecylamine with dodecylamine to synthesize N-dodecyl thioctic amide, etc., which will not be described one by one herein.

[0065] In a second aspect, the embodiments of the present application further provide a preparation method of the hot-melt injectable adhesive described in the above application, preferably comprising:

[0066] According to the raw material components of the hot-melt injectable adhesive described in the present application, the contained α-lipoic acid, N-alkyl thioctic amide, and tris(2-carboxyethyl) phosphonium hydrochloride or citric acid are mixed and hot-melted, and then cooled to obtain the product.

[0067] In the preparation method of the embodiments of the present application, the components can fully interact with each other and form a hydrophobic co-hot-melt product containing a small molecular eutectic phase of α-lipoic acid and N-alkyl thioctic amide in the phase, so that the co-hot-melt product has good injectability and a long-lasting and stable adhesive effect in an underwater environment.

[0068] According to the preparation method of the present application, the temperature of the mixed hot-melting is 120-150°C, and specific examples are 120°C, 130°C, 140°C, 150°C, or any value within the range. In the embodiments of the present application, by controlling the hot-melting temperature, the α-lipoic acid, N-alkyl thioctic amide, and tris(2-carboxyethyl) phosphonium hydrochloride or citric acid can be fully mixed and melted, and physical combination and chemical reaction can occur.

[0069] In a third aspect, the embodiments of the present application further provide an application of the hot-melt injectable adhesive described in the above application, specifically using the hot-melt injectable adhesive described in the embodiments of the present application to perform adhesive treatment on the contact surfaces to be bonded. In view of the good injectability and long-lasting and stable adhesive effect of the hot-melt injectable adhesive described in the present application, after the hot-melt injectable adhesive described in the present application is used to perform adhesive treatment on the contact surfaces to be bonded, the bonded contact surfaces are firmly bonded, which can effectively reduce the separation of the contact surfaces.

[0070] According to the application of the present application, it is found that when the hot-melt injectable adhesive described in the present application is heated to 50-100°C, it can be melted and form a co-hot-melt product with high flowability. Therefore, when the hot-melt injectable adhesive described in the present application is used to perform adhesive treatment on the contact surfaces to be bonded, the hot-melt injectable adhesive can be heated to 50-100°C for hot-melting, then injected onto the contact surfaces to be bonded, and the contact surfaces to be bonded are tightly contacted, and then cooled to complete the adhesive treatment on the contact surfaces to be bonded.

[0071] According to the application, the hot-melt injectable adhesive has the underwater stable adhesion effect, so the contact surface to be bonded can be located in the water-containing system. The water-containing system specifically refers to the water-related environment, including but not limited to fresh water system, acidic water system and / or high-salt water system.

[0072] In a fourth aspect, the embodiments of the present application also provide a glass bonding method, which comprises bonding the glass contact surface by using the hot-melt injectable adhesive described above. Since the hot-melt injectable adhesive of the embodiments of the present application has good universality and stable solidification bonding effect, the bonded glass contact surface is firmly bonded and can maintain the stable bonding effect in the underwater environment.

[0073] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0074] Embodiment 1

[0075] The present embodiment provides a hot-melt injectable adhesive (PLAO2), the raw materials of which comprise:

[0076] 4.9 mmol (1.01 g) of α-lipoic acid powder;

[0077] 0.1 mmol (0.05 g) of N-octadecyl lipoamide powder;

[0078] 0.1 mmol (0.03 g) of tris (2-carboxyethyl) phosphonium chloride salt powder;

[0079] The above-mentioned raw materials in the molar amount are put into a glass bottle, heated to 150°C and stirred for 20 min, and then cooled and crystallized at room temperature to obtain the hot-melt injectable adhesive (PLAO2).

[0080] Embodiment 2

[0081] The present embodiment provides a hot-melt injectable adhesive (PLAO4), the raw materials of which comprise:

[0082] 4.8 mmol (0.99 g) of α-lipoic acid powder;

[0083] 0.2 mmol (0.09 g) of N-octadecyl lipoamide powder;

[0084] 0.1 mmol (0.03 g) of tris (2-carboxyethyl) phosphonium chloride salt powder;

[0085] The above-mentioned raw materials in the molar amount are put into a glass bottle, heated to 150°C and stirred for 20 min, and then cooled and crystallized at room temperature to obtain the hot-melt injectable adhesive (PLAO4).

[0086] Example 3

[0087] This example provides a hot-melt injectable adhesive (PLAO8) whose raw materials include:

[0088] 4.6 mmol (0.95 g) of α-lipoic acid powder;

[0089] 0.4 mmol (0.18 g) of N-octadecyl lipoamide powder;

[0090] 0.1 mmol (0.03 g) of tris(2-carboxyethyl)phosphonium hydrochloride powder;

[0091] The above-mentioned raw materials in the molar amounts are put into a glass bottle, heated to 150°C and stirred for 20 min, and then cooled to crystallize at room temperature to obtain the hot-melt injectable adhesive (PLAO8).

[0092] Example 4

[0093] This example provides a hot-melt injectable adhesive (PLAO16) whose raw materials include:

[0094] 4.2 mmol (0.87 g) of α-lipoic acid powder;

[0095] 0.8 mmol (0.37 g) of N-octadecyl lipoamide powder;

[0096] 0.1 mmol (0.03 g) of tris(2-carboxyethyl)phosphonium hydrochloride powder;

[0097] The above-mentioned raw materials in the molar amounts are put into a glass bottle, heated to 150°C and stirred for 20 min, and then cooled to crystallize at room temperature to obtain the hot-melt injectable adhesive (PLAO16).

[0098] Example 5

[0099] This example provides a hot-melt injectable adhesive (PLAO8-CA) whose raw materials include:

[0100] 4.6 mmol (0.95 g) of α-lipoic acid powder;

[0101] 0.4 mmol (0.18 g) of N-octadecyl lipoamide powder;

[0102] 0.1 mmol (0.03 g) of citric acid powder;

[0103] The above-mentioned raw materials in the molar amounts are put into a glass bottle, heated to 150°C and stirred for 20 min, and then cooled to crystallize at room temperature to obtain the hot-melt injectable adhesive (PLAO8-CA).

[0104] To verify the actual performance of the hot-melt injectable adhesives prepared in the present application, the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8, PLAO16 and PLAO8-CA prepared in Examples 1-5 were subjected to the following tests:

[0105] 1.1 Rheological characterization

[0106] After the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 were respectively made into sheets with a diameter of 8 mm and a thickness of 1 mm, a rotational rheometer equipped with a PP08 rotor and a temperature control platform was used to test them in a temperature range of 0-80℃, and the results are shown in FIG. 1. Among them, Figure 1 Figure 1 is the temperature-rising rheological curve of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16.

[0107] According to the above, Figure 1 it can be seen that the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 prepared above all have relatively high storage modulus (G’) and loss modulus (G”) in the low temperature range, and decrease significantly during heating, specifically, the modulus remains at a low level at a temperature of 55℃ and above, indicating that the hot-melt injectable adhesives prepared in the examples of the present application have good hot-melt behavior.

[0108] 1.2 Shear viscosity test

[0109] After the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 were respectively heated to 55℃ to melt, a rotational rheometer equipped with a PP08 rotor and a temperature control platform was used to test their shear viscosity at a shear rate of 1 s -1 Figure 2 The results are shown in FIG. 2. Among them, Figure 2

[0110] According to the above, Figure 2 it can be seen that the melt viscosity of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 prepared above gradually decreases with the increase of the amount of N-octadecyl thioctic amide, specifically, the melt viscosity of PLAO8 and PLAO16 is lower than 100 Pa·s, meeting the injection requirements.

[0111] 1.3 Hydrophilic and hydrophobic performance test

[0112] ​​​The hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 were respectively made into flat sheets with a thickness of 1 mm, and then the water contact angles of the flat sheets were measured by the pendant drop method using an optical contact angle measuring instrument, and the results are shown in Table 1. Figure 3 Figure 3 Table 1 is a statistical diagram of the water contact angles of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16.

[0113] According to Table 1, Figure 3 it can be known that the water contact angles of the hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 prepared above are all equal to or greater than 90°, and increase with the increase of the amount of N-octadecyl thioctic amide, which indicates that the hot-melt injectable adhesives prepared in the present application have hydrophobicity, and the addition of N-octadecyl thioctic amide can significantly enhance the hydrophobicity of the prepared hot-melt injectable adhesives.

[0114] 1.4 Lap shear strength test

[0115] The glass pieces were soaked in water at room temperature for standby as a substrate;

[0116] The hot-melt injectable adhesives PLAO2, PLAO4, PLAO8 and PLAO16 were loaded into a syringe and placed in a 55°C oven to melt, and then the hot-melt injectable adhesive PLAO2, PLAO4, PLAO8 and PLAO16 melt was respectively injected onto each glass substrate under water to form an adhered area, and then another glass piece was used to cover the adhered area, and after soaking for different times under water, the PLAO adhered glass samples were obtained. The PLAO adhered glass samples were placed on a mechanical tester for tensile testing, and the results are shown in Table 2. Figure 4 Figure 4 A in Table 2 is the lap shear strength test result of the PLAO adhered glass after 24h curing; Figure 4 B in Table 2 is the lap shear strength test result of the PLAO8 adhered glass after different curing times.

[0117] According to A in Table 2, Figure 4 it can be known that the adhesion strength of the PLAO adhered glass gradually increases with the addition of N-octadecyl thioctic amide, but the adhesion effect is poor due to the sharp reduction in the number of polar groups in the structure of PLAO16 which provides adhesion, which indicates that the addition of N-octadecyl thioctic amide can improve the wettability and hydrophobicity of the hot-melt injectable adhesive, thereby improving the underwater adhesion strength; according to B in Table 2, Figure 4 it can be known that the adhesion strength of the PLAO8 adhered glass gradually increases with the extension of the curing time, and reaches a stable state after 7d, which indicates that the curing process of PLAO8 is controlled by time.

[0118] 1.5 Underwater rapid adhesion test​​

[0119] A 4 kg stainless steel weight was placed in water, hot-melt injectable adhesive PLAO8 was loaded into a syringe and put into a 55 °C oven to melt, the PLAO8 melt was injected onto the weight under water, and a stainless steel block with a cross-sectional area of 2.5 cm 2 was pressed onto the adhesive area, and the result is shown in Figure 5 , wherein Figure 5 is a photograph of the PLAO8 underwater adhesive weight. Figure 5

[0120] According to Figure 5 , the hot-melt injectable adhesive PLAO8 prepared above firmly bonds the stainless steel block and the weight after 5 min of curing and can withstand the weight of a 4 kg weight, indicating that the hot-melt injectable adhesive PLAO8 has the performance of underwater rapid adhesion.

[0121] 1.6 Lap shear strength test of adhesion in acidic and high-salt water environments

[0122] Glass pieces were soaked in acidic and high-salt water environments at room temperature for use as substrates;

[0123] Hot-melt injectable adhesive PLAO8 was loaded into a syringe and put into a 55 °C oven to melt, then the PLAO8 melt was injected onto the glass substrate in acidic and high-salt water environments to form an adhesive area, respectively, and another glass piece was used to cover the adhesive area, and after 7 d of underwater immersion, the PLAO8 adhesive glass sample was obtained. The PLAO8 adhesive glass sample was placed on a mechanical tester for tensile testing, and the result is shown in Figure 6 , wherein Figure 6 A in Figure 6 is the lap shear strength test result of PLAO8 adhesion to glass in acidic water environments after 7 d of curing; B in

[0124] is the lap shear strength test result of PLAO8 adhesion to glass in high-salt water environments after 7 d of curing. Figure 6 Figure 6 According to A in , there is no significant difference in the glass adhesion strength of PLAO8 in different pH acidic and neutral water environments, indicating that the acidic environment has no significant effect on the adhesion performance of PLAO8; according to B in

[0125] , there is no significant difference in the glass adhesion strength of PLAO8 in different salt concentration water environments. It indicates that different concentrations of salt ion environment have no significant effect on the adhesion performance of PLAO8.

[0126] After the hot-melt injectable adhesive PLAO8-CA was heated to 55 °C to melt, a rotational rheometer equipped with a PP08 rotor and a temperature control platform was used to test the shear viscosity at 1 s -1Shear viscosity curves of the 55℃ melt of hot-melt injectable adhesive PLAO8-CA. Figure 7 Shear viscosity curves of the 55℃ melt of hot-melt injectable adhesive PLAO8-CA. Figure 7 Shear viscosity curves of the 55℃ melt of hot-melt injectable adhesive PLAO8-CA.

[0127] According to Figure 7 It can be seen from the above that the hot-melt injectable adhesive PLAO8-CA prepared has a melt viscosity of less than 100 Pa·s at a shear rate of 1 s -1 -1, which meets the injection requirements.

[0128] 1.8 Lap shear strength test of PLAO8-CA

[0129] Glass pieces were soaked in water at room temperature for use as substrates;

[0130] The hot-melt injectable adhesive PLAO8-CA was loaded into a syringe and placed in a 55℃ oven to melt, and then the hot-melt injectable adhesive PLAO8-CA melt was injected onto each glass substrate under water to form an adhesive area, and then another glass piece was used to cover the adhesive area, and after soaking under water for different times, the PLAO8-CA adhered glass samples were obtained. The PLAO8-CA adhered glass samples were placed on a mechanical tester for tensile testing, and the results are shown in Figure 8 Shear strength test results of PLAO8-CA adhered glass after 24h curing. Figure 8 Shear strength test results of PLAO8-CA adhered glass after 24h curing.

[0131] According to Figure 8 It can be seen from the above that the hot-melt injectable adhesive PLAO8-CA prepared has a melt viscosity of less than 100 Pa·s at a shear rate of 1 s

[0132] To further illustrate the combination effect of the components contained in the hot-melt injectable adhesive described in the present application, the performance of hot-melt bodies with different component combinations was tested in this paper as evaluation criteria of shear viscosity and lap shear strength. Specifically, the component ratio and preparation process of Example 3 were used as the experimental group (PLAO8), and Comparative Examples 1-3 were provided as control groups.

[0133] Comparative Example 1

[0134] This comparative example provides a binary co-hot-melt product of tris(2-carboxyethyl)phosphonium hydrochloride and alpha-lipoic acid (TCEP+LA), i.e., the component N-octadecyl lipoamide (LA-C 18 ) is omitted.

[0135] Comparative Example 2

[0136] This comparative example provides a binary co-hot-melt product of alpha-lipoic acid and N-octadecyl lipoamide (LA+LA-C18 ), that is, tris(2-carbonylethyl)phosphine hydrochloride (TCEP) is omitted from the composition.

[0137] Comparative Example 3

[0138] This comparative example provides a binary co-melting product of tris(2-carbonylethyl)phosphine hydrochloride and N-octadecyl lipoamide (TCEP+LA-C 18 ), i.e. α-lipoic acid (LA) is omitted from the composition.

[0139] 2.1 Shear viscosity test

[0140] The experimental group and the control group were heated to 55 °C, and a rotational rheometer equipped with a PP08 rotor and a temperature control platform was used to measure the flow rate in the range of 0.1-100 s. -1 The shear viscosity test was carried out at a shear rate of Figure 9 As shown. Among them, Figure 9 The experimental group and the control group (TCEP+LA, LA+LA-C 18 TCEP+LA-C 18 )'s shear viscosity change curve of the 55°C melt.

[0141] according to Figure 9 It can be seen that the experimental group and the control group LA+LA-C 18 TCEP+LA-C 18 At a shear rate greater than 1s -1 The viscosity of the control group TCEP+LA was less than 100 Pa·s, which met the injection requirements; while the viscosity of the control group TCEP+LA was larger and difficult to inject.

[0142] 2.2 Lap shear strength test

[0143] Soak a glass slide in water at room temperature to prepare it as a substrate;

[0144] The experimental group and the control group were heated to a fully fluid state, and then injected into the glass substrate underwater to form an adhesion area. The adhesion area was then covered with another glass sheet. After being immersed in water for 24 hours, the adhered glass samples were placed on a mechanical tester for tensile testing. The results were as follows: Figure 10 As shown. Among them, Figure 10 These are the lap shear strength test results of the adhered glass in the experimental group and the control group after 24 hours of curing.

[0145] according to Figure 10 As shown in the figure, the experimental group has higher underwater bonding strength to glass; the control group TCEP+LA has poor adhesion; the control group LA+LA-C 18 Compared with the control group TCEP+LA-C 18 No sticking effect.

[0146] In summary, the ternary eutectic melt containing α-lipoic acid, N-alkyl lipoamide and tris(2-carboxyethyl)phosphonium hydrochloride can generate a co-melt product containing small molecule eutectic phase of α-lipoic acid and N-alkyl lipoamide in the phase. On the one hand, the high flowability of the co-melt product can be imparted by the small molecule eutectic phase contained therein melting at elevated temperature, thereby making it have good injectability; on the other hand, the flowable co-melt product can fully drain and wet the substrate underwater, then form extensive weak interactions with different substrate surfaces through polar groups (-COOH, -NH-CO-), and can achieve underwater persistent and stable solidification bonding by recrystallization of the contained small molecule eutectic phase during cooling process, imparting it with persistent and stable adhesion in underwater environment. In addition, since the injectable co-melt product described in the present application is a temperature-responsive crystallization and solidification mode, the entire solidification process does not involve material exchange with water phase, and the solvent composition is omitted, which has the advantages of green environmental protection, simple preparation, good universality, strong adhesion and convenient use and operation, and is expected to show great application potential in daily life and industrial engineering fields.

[0147] The various embodiments in the specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments.

[0148] The above examples are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A hot melt injectable adhesive, characterized in that: A co-melt product comprising the following components; (i) 42-49 molar parts of α-lipoic acid; (ii) 1 to 8 molar parts of N-alkyl lipoamide; (iii) 1 mol part of tris(2-carbonylethyl)phosphine hydrochloride or citric acid.

2. The hot melt injectable adhesive according to claim 1, characterized in that The N-alkyl lipoamide has the following chemical structure: Wherein, R is a C6-C18 alkyl group.

3. A method for preparing a hot melt injectable adhesive, characterized in that: The steps include: The raw material components of the hot-melt injectable adhesive according to claim 1 or 2 are prepared by mixing and hot-melting α-lipoic acid, N-alkyl lipoamide, and tris(2-carbonylethyl)phosphine hydrochloride or citric acid, and then cooling.

4. The preparation method according to claim 3, characterized in that The temperature of the mixed hot melt is 120-150°C.

5. Use of the hot-melt injectable adhesive according to claim 1 or 2 for bonding contact surfaces to be bonded.

6. The use according to claim 5, characterized in that When the bonding process is performed on the contact surface to be bonded, the hot-melt injectable adhesive is heated to 50-100° C. to melt, injected onto the contact surface to be bonded, and cooled.

7. The use according to claim 6, characterized in that The contact surfaces to be bonded are located in an aqueous system.

8. The use according to claim 7, characterized in that The aqueous system includes a fresh water system, an acidic water system and / or a high saline water system.

9. A glass bonding method, characterized by comprising bonding the glass contact surfaces using the hot-melt injectable adhesive according to any one of claims 1 to 3.

Images