Moisture-cured polyamide hot melt adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of hot melt adhesives, and particularly relates to a moisture-cured polyamide hot melt adhesive and a preparation method thereof. The polyamide hot melt adhesive comprises the following components in parts by weight: 30-40 parts of dimer acid; 10 to 20 parts of aliphatic dicarboxylic acid; 30 to 35 parts of polyether amine; 5 to 10 parts of aliphatic diamine; 8 to 10 parts of a functionalized silane modifier; 0.08 to 0.1 part of a phosphoric acid catalyst; the functional silane modifier is added into the components of the polyamide hot melt adhesive, so that the polyamide hot melt adhesive is modified, and the provided polyamide hot melt adhesive is an amber transparent solid, has excellent adhesive property, mechanical property, high-temperature resistance and antibacterial property, also has good constructability, and is suitable for being used as a high-temperature-resistant and antibacterial polyamide hot melt adhesive. The polyamide hot melt adhesive has enough opening time for fitting and positioning, especially gives the moisture curing characteristic to the polyamide hot melt adhesive, and can be further subjected to moisture curing after being cooled and cured to form a high-strength bonding effect.

Description

Technical Field

[0001] This invention belongs to the field of hot melt adhesive technology, specifically relating to a moisture-curing polyamide hot melt adhesive and its preparation method. Background Technology

[0002] Polyamide hot melt adhesive (PA hot melt adhesive) is a high-performance hot melt adhesive based on polyamide resin. It is produced through the condensation reaction of diacids and diamines. It possesses excellent adhesion, temperature resistance, chemical resistance, and mechanical properties, and is widely used in textiles and apparel, footwear, electronics, industrial packaging, and other fields. However, traditional polyamide hot melt adhesives are essentially thermoplastic materials, and their adhesive strength depends on melt cooling and crystallization or glass transition. During use, thermoplasticity easily leads to poor heat creep resistance, making them prone to deformation under continuous stress or high temperatures. This leads to adhesive failure. To overcome the shortcomings of thermoplastic adhesives, reactive hot melt adhesives have emerged. Moisture-curing reactive polyurethane (PUR) hot melt adhesive technology is relatively mature. It introduces terminal isocyanate groups into the polyurethane prepolymer, which reacts with moisture in the air after application to form a thermosetting material with a network structure. This significantly improves the heat resistance, creep resistance and chemical stability of the final adhesive layer. Polyamide materials themselves have a higher melting point and heat resistance than polyurethane. If they can be given moisture-curing properties, it is hoped that the advantages of both can be combined to develop a new type of hot melt adhesive with even better performance.

[0003] Chinese patent application CN202211481364.7 discloses a polyamide hot melt adhesive and its preparation method and application. The raw materials for its preparation include the following components: 600-700 parts of diacid, 20-80 parts of diamine, 100-500 parts of polyetheramine, 10-50 parts of aminosulfonic acid, 10-50 parts of silicone oil, 20-200 parts of resin, 10-40 parts of antioxidant, 2-20 parts of catalyst, and 10-40 parts of colorant. This polyamide hot melt adhesive significantly improves the adhesion, hardness, and resilience of hot melt adhesives. Chinese patent application CN202410620085.7 discloses a... The main steps of the copolyamide hot melt adhesive and its preparation method are as follows: a condensation polymerization reaction is used to polycondense a diacid and a diamine to form a polyamide resin; amino acids, tackifying resins, and antioxidants are added to the polyamide resin; and the copolyamide hot melt adhesive is obtained after heating and stirring. The mechanical strength and adhesiveness of the copolyamide hot melt adhesive are improved by adding isocyanate. However, the adhesive properties of the hot melt adhesives provided by the above-mentioned patents are insufficient, and the moisture curing effect of polyamide hot melt adhesives is not involved. At present, there is little research on introducing the moisture curing mechanism into the polyamide system. Therefore, developing a moisture-curable hot melt adhesive based on a polyamide skeleton has important technological innovation value and market application prospects. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a moisture-curing polyamide hot melt adhesive and its preparation method. By adding a functionalized silane modifier to the polyamide hot melt adhesive components, the polyamide hot melt adhesive is modified. The provided polyamide hot melt adhesive is an amber-colored transparent solid with excellent adhesion, mechanical properties, high temperature resistance, and antibacterial properties. It also has good workability, sufficient open time for bonding and positioning, and, in particular, endows the polyamide hot melt adhesive with moisture-curing characteristics. After cooling and curing, it can be further moisture-cured to form a high-strength bonding effect.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows: A moisture-curing polyamide hot melt adhesive, the polyamide hot melt adhesive comprising the following components in parts by weight: 30-40 parts dimer acid; 10-20 parts aliphatic dicarboxylic acid; 30-35 parts polyetheramine; 5-10 parts aliphatic diamine; 8-10 parts functionalized silane modifier; and 0.08-0.1 parts phosphoric acid catalyst.

[0006] Furthermore, the aliphatic dicarboxylic acid is any one or a mixture of several of sebacic acid, azelaic acid, and adipic acid.

[0007] Furthermore, the aliphatic diamine is any one or a mixture of several of the following: decanediamine, hexamethylenediamine, and ethylenediamine.

[0008] Furthermore, the functionalized silane modifier is prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.5-8.6, place at room temperature, stir and react for 22-24 hours to obtain polydopamine-modified nano-alumina. S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 60-70℃, stir and react for 5-6 hours to obtain functionalized silane modifier.

[0009] Further, in step S1, the mass ratio of nano-alumina to Tris-HCl buffer is 1:10-12; and the concentration of dopamine hydrochloride in the Tris-HCl buffer is 3-4 mg / mL.

[0010] Further, in step S2, the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane, and triethylamine is 1:0.3-0.4:0.08-0.1.

[0011] Further, the modified trimethoxysilane described in step S2 is prepared by the following method: Step 1: Add 3-aminopropyltrimethoxysilane to anhydrous dichloromethane, stir well, place at 30-35℃, slowly add epichlorohydrin dropwise, and after the addition is complete, stir the reaction for 3-4 hours to obtain trimethoxysilane chloride. Step 2: Add trimethoxysilane chloride, triclosan and triethylamine to anhydrous N,N-dimethylformamide, stir evenly, place at 50-60℃, and continue stirring for 5-6 hours to obtain modified trimethoxysilane.

[0012] Furthermore, the molar ratio of 3-aminopropyltrimethoxysilane and epichlorohydrin in the first step is 1:1-1.1.

[0013] Furthermore, in the second step, the molar ratio of trimethoxysilane chloride, triclosan, and triethylamine is 1:1-1.1:1.1-1.2.

[0014] This invention also provides a method for preparing a moisture-curing polyamide hot melt adhesive, comprising the following steps: according to the weight ratio, under nitrogen protection, adding dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to a reaction vessel; adding aliphatic diamine at 140-150℃; heating to 180-200℃; reacting for 3-4 hours; adding functionalized silane modifier; heating to 220-240℃; and continuing the reaction for 2-3 hours to obtain polyamide hot melt adhesive.

[0015] The present invention has the following beneficial effects: This invention prepares a modified trimethoxysilane containing trimethoxysilane, triclosan, alcohol hydroxyl, and chloroalkyl structures by reacting 3-aminopropyltrimethoxysilane sequentially with epichlorohydrin and triclosan. Furthermore, this invention grafts the modified trimethoxysilane onto polydopamine-modified nano-alumina by reacting the chloroalkyl group in the modified trimethoxysilane with the amino group in polydopamine-modified nano-alumina, thus obtaining a functionalized silane modifier. The functionalized silane modifier obtained by this invention contains polydopamine-modified nano-alumina, trimethoxysilane, triclosan, and alcohol hydroxyl structures. The alcohol hydroxyl groups can react with the carboxyl groups at the ends of the polyamide molecular chains to form a network structure, allowing the functionalized silane modifier to be grafted onto the polyamide. At the molecular level, organically modified nano-alumina exhibits better dispersibility and compatibility in polyamides, significantly enhancing the tensile strength and improving the mechanical properties of polyamide hot melt adhesives. The polydopamine structure itself possesses excellent adhesion and antibacterial properties, significantly enhancing the shear strength and improving the bonding performance of polyamide hot melt adhesives. It can also work synergistically with the triclosan structure, which has antibacterial properties, greatly improving the antibacterial performance of polyamide hot melt adhesives. The trimethoxysilane structure can react with moisture after application, hydrolyzing to generate silanol groups, which condense to form a stable cross-linked network structure, endowing polyamide hot melt adhesives with moisture-curing properties. This allows them to retain moisture-curing properties even after cooling and curing, further enhancing the tensile and shear strength of polyamide hot melt adhesives.

[0016] This invention modifies polyamide hot melt adhesive by adding functionalized silane modifiers to the polyamide hot melt adhesive components. The resulting polyamide hot melt adhesive is an amber-colored transparent solid with excellent adhesion, mechanical properties, high temperature resistance, and antibacterial properties. It also has good workability, sufficient open time for bonding and positioning, and, in particular, endows the polyamide hot melt adhesive with moisture-curing characteristics. After cooling and curing, it can be further moisture-cured to form a high-strength bonding effect. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the technical solution of this invention, all chemical reagents used are commercially available, including: dimer acid (CAS: 61788-89-4), polyetheramine (CAS: 9046-10-0), sebacic acid (CAS: 111-20-6), azelaic acid (CAS: 123-99-9), adipic acid (CAS: 124-04-9), decanediamine (CAS: 646-25-3), hexamethylenediamine (CAS: 124-09-4), ethylenediamine (CAS: 107-15-3), and hydrochloric acid. Dopamine CAS: 62-31-7, Sodium hydroxide CAS: 1310-73-2, 3-aminopropyltrimethoxysilane CAS: 13822-56-5, Epichlorohydrin CAS: 106-89-8, Triclosan CAS: 3380-34-5, Triethylamine CAS: 121-44-8, Dichloromethane CAS: 75-09-2, N,N-Dimethylformamide CAS: 68-12-2, Ethanol CAS: 64-17-5.

[0019] Example 1 This embodiment provides a method for preparing modified trimethoxysilane: ; Step 1: Add 15.0 g of 3-aminopropyltrimethoxysilane to 450 mL of anhydrous dichloromethane, stir well, place at 35 °C, and slowly add 8.1 g of epichlorohydrin dropwise. After the addition is complete, stir the reaction for 4 h. After the reaction is complete, remove the anhydrous dichloromethane to obtain 18.5 g of trimethoxysilane chloride; wherein the molar ratio of 3-aminopropyltrimethoxysilane to epichlorohydrin is 1:1.05. Trimethoxysilane chloride: ESI (m / z): 272.8 [M+H] + , 1 H-NMR (600MHz, DMSO-d6, δppm): 5.37 (s, 1H), 3.86-3.89 (m, 1H), 3.71 (s, 1H), 3.55 (s, 9H), 3. 63-3.65 (m, 1H), 2.96-3.00 (m, 2H), 2.52-2.56 (m, 3H), 1.37-1.40 (m, 2H), 0.56-0.59 (m, 2H); Step 2: Add 18.5g of trimethoxysilane chloride, 20.7g of triclosan, and 7.6g of triethylamine to 400mL of anhydrous N,N-dimethylformamide, stir well, and place at 60℃ for 5 hours. After the reaction is complete, remove the anhydrous N,N-dimethylformamide to obtain 28.8g of modified trimethoxysilane; wherein the molar ratio of trimethoxysilane chloride, triclosan, and triethylamine is 1:1.05:1.1. Modified trimethoxysilane: ESI (m / z): 525.9 [M+H]+ , 1 H-NMR (600MHz, DMSO-d6, δppm): 9.48 (s, 1H), 7.11 (s, 1H), 6.91-6.94 (m, 2H), 6.70-6.76 (m, 3H), 5.38 (s, 1H) , 3.85-3.88 (m, 1H), 3.56 (s, 9H), 3.60-3.63 (m, 2H), 3.33-3.38 (m, 4H), 1.48-1.50 (m, 2H), 0.55-0.59 (m, 2H).

[0020] Example 2 This embodiment provides a moisture-curing polyamide hot melt adhesive, comprising the following components by weight: 40 parts of dimer acid; 20 parts of aliphatic dicarboxylic acid; 35 parts of polyetheramine; 10 parts of aliphatic diamine; 10 parts of functionalized silane modifier; and 0.1 parts of phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is azelaic acid and the aliphatic diamine is decanediamine.

[0021] Functionalized silane modifiers are prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.6 with 30% sodium hydroxide solution, place at room temperature, stir and react for 24 h. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain polydopamine-modified nano-alumina; wherein the mass ratio of nano-alumina to Tris-HCl buffer is 1:10; the concentration of dopamine hydrochloride in Tris-HCl buffer is 4 mg / mL; S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 70℃, stir and react for 5 hours. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain functionalized silane modifier; wherein the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane and triethylamine is 1:0.4:0.1.

[0022] This embodiment also provides a method for preparing a moisture-curing polyamide hot melt adhesive, comprising the following steps: according to the weight ratio, under nitrogen protection, adding dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to a reaction vessel, adding aliphatic diamine at 150°C, raising the temperature to 200°C, reacting for 3 hours, adding functionalized silane modifier, raising the temperature to 240°C, and continuing the reaction for 2 hours to obtain polyamide hot melt adhesive.

[0023] Example 3 This embodiment provides a moisture-curing polyamide hot melt adhesive, comprising the following components by weight: 35 parts dimer acid; 10 parts aliphatic dicarboxylic acid; 32 parts polyetheramine; 5 parts aliphatic diamine; 9 parts functionalized silane modifier; and 0.09 parts phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is sebacic acid and the aliphatic diamine is hexamethylenediamine.

[0024] Functionalized silane modifiers are prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.6 with 30% sodium hydroxide solution, place at room temperature, stir and react for 22 h. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain polydopamine-modified nano-alumina; wherein the mass ratio of nano-alumina to Tris-HCl buffer is 1:11; the concentration of dopamine hydrochloride in Tris-HCl buffer is 3.5 mg / mL; S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 65℃, stir and react for 5.5 h. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain functionalized silane modifier; wherein the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane and triethylamine is 1:0.35:0.09.

[0025] This embodiment also provides a method for preparing a moisture-curing polyamide hot melt adhesive, comprising the following steps: according to the weight ratio, under nitrogen protection, adding dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to a reaction vessel, adding aliphatic diamine at 145°C, raising the temperature to 190°C, reacting for 3.5 h, adding functionalized silane modifier, raising the temperature to 230°C, and continuing the reaction for 2.5 h to obtain polyamide hot melt adhesive.

[0026] Example 4 This embodiment provides a moisture-curing polyamide hot melt adhesive, comprising the following components by weight: 30 parts dimer acid; 15 parts aliphatic dicarboxylic acid; 30 parts polyetheramine; 8 parts aliphatic diamine; 8 parts functionalized silane modifier; and 0.08 parts phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is adipic acid and the aliphatic diamine is ethylenediamine.

[0027] Functionalized silane modifiers are prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.5 with 30% sodium hydroxide solution, place at room temperature, stir and react for 23 hours. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain polydopamine-modified nano-alumina; wherein the mass ratio of nano-alumina to Tris-HCl buffer is 1:12; the concentration of dopamine hydrochloride in Tris-HCl buffer is 3 mg / mL; S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 60℃, stir for 6 hours. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain functionalized silane modifier; wherein the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane and triethylamine is 1:0.3:0.08.

[0028] This embodiment also provides a method for preparing a moisture-curing polyamide hot melt adhesive, comprising the following steps: according to the weight ratio, under nitrogen protection, adding dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to a reaction vessel, adding aliphatic diamine at 140°C, raising the temperature to 180°C, reacting for 4 hours, adding functionalized silane modifier, raising the temperature to 220°C, and continuing the reaction for 3 hours to obtain polyamide hot melt adhesive.

[0029] Example 5 This embodiment provides a moisture-curing polyamide hot melt adhesive, comprising the following components by weight: 40 parts dimer acid; 10 parts aliphatic dicarboxylic acid; 30 parts polyetheramine; 10 parts aliphatic diamine; 10 parts functionalized silane modifier; and 0.09 parts phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is adipic acid and the aliphatic diamine is decanediamine.

[0030] Functionalized silane modifiers are prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.5 with 30% sodium hydroxide solution, place at room temperature, stir and react for 24 h. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain polydopamine-modified nano-alumina; wherein the mass ratio of nano-alumina to Tris-HCl buffer is 1:11; the concentration of dopamine hydrochloride in Tris-HCl buffer is 4 mg / mL; S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 65℃ and stir for 6 hours. After the reaction is complete, centrifuge, filter, wash the product with water and ethanol in sequence, and dry to obtain functionalized silane modifier; wherein the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane and triethylamine is 1:0.35:0.1.

[0031] This embodiment also provides a method for preparing a moisture-curing polyamide hot melt adhesive, comprising the following steps: according to the weight ratio, under nitrogen protection, adding dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to a reaction vessel, adding aliphatic diamine at 150°C, raising the temperature to 190°C, reacting for 4 hours, adding functionalized silane modifier, raising the temperature to 230°C, and continuing the reaction for 2 hours to obtain polyamide hot melt adhesive.

[0032] Comparative Example 1 This comparative example provides a moisture-curing polyamide hot melt adhesive, comprising the following components in parts by weight: 40 parts of dimer acid; 20 parts of aliphatic dicarboxylic acid; 35 parts of polyetheramine; 10 parts of aliphatic diamine; 10 parts of polydopamine-modified nano-alumina; and 0.1 parts of phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is azelaic acid and the aliphatic diamine is decanediamine.

[0033] The preparation method of polydopamine-modified nano-alumina is the same as step S1 in Example 2.

[0034] This example also provides a method for preparing a moisture-curing polyamide hot melt adhesive, which is the same as in Example 2.

[0035] Comparative Example 2 This comparative example provides a moisture-curing polyamide hot melt adhesive, comprising the following components in parts by weight: 40 parts of dimer acid; 20 parts of aliphatic dicarboxylic acid; 35 parts of polyetheramine; 10 parts of aliphatic diamine; 10 parts of modified trimethoxysilane; and 0.1 parts of phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is azelaic acid and the aliphatic diamine is decanediamine.

[0036] This example also provides a method for preparing a moisture-curing polyamide hot melt adhesive, which is the same as in Example 2.

[0037] Comparative Example 3 This embodiment provides a moisture-curing polyamide hot melt adhesive, comprising the following components by weight: 40 parts of dimer acid; 20 parts of aliphatic dicarboxylic acid; 35 parts of polyetheramine; 10 parts of aliphatic diamine; and 0.1 parts of phosphoric acid catalyst; wherein the aliphatic dicarboxylic acid is azelaic acid and the aliphatic diamine is decanediamine.

[0038] This example also provides a method for preparing a moisture-curing polyamide hot melt adhesive, which is the same as in Example 2.

[0039] Test case The appearance of the polyamide hot melt adhesives provided in Examples 2 to 4 and Comparative Examples 1 to 3 was observed. All were amber-colored transparent solids. The high-temperature viscosity test was performed according to GB / T 2794-1995 standard; the open time test according to HG / T 3716-2003 standard; the softening point test according to GB / T 15332-94 standard; and the tensile strength and shear strength (aluminum / aluminum) tests according to GB / T7124-2008 standard. The antibacterial activity of the polyamide hot melt adhesive was tested using the inhibition zone method. Samples were 5 mm in diameter and 1 mm thick, and 100 μL of activated bacterial solution (all concentrations were 10) was evenly coated onto the culture medium. 6 The samples were prepared by placing a suspension of Staphylococcus aureus and Escherichia coli (cfu / mL) in the center of the culture medium and incubating at a constant temperature (37℃) for 24 hours. The diameter of the inhibition zone was then measured. The results are shown in Table 1 below.

[0040] Table 1 As shown in Table 1, the high-temperature viscosity, open time, softening point, tensile strength, shear strength, and inhibition zone diameter of the polyamide hot melt adhesives prepared in Examples 2 to 4 of this invention are all higher than those in Comparative Examples 1 to 3. This indicates that the polyamide hot melt adhesives provided by this invention have excellent bonding performance, mechanical properties, high-temperature resistance, and antibacterial properties, as well as good workability. Compared with Comparative Examples 1 to 3, Example 2 of this invention's polyamide hot melt adhesive includes a functionalized silane modifier. The functionalized silane modifier contains polydopamine-modified nano-alumina, a trimethoxysilane structure, a triclosan structure, and an alcohol hydroxyl structure. The alcohol hydroxyl group can react with the carboxyl group at the end of the polyamide molecular chain to form a network structure, allowing the functionalized silane modifier to be grafted onto the polyamide. On the amine molecule; organically modified nano-alumina exhibits better dispersibility and compatibility in polyamides, significantly enhancing the tensile strength and improving the mechanical properties of polyamide hot melt adhesives. The polydopamine structure itself possesses excellent adhesion and antibacterial properties, significantly enhancing the shear strength and improving the bonding performance of polyamide hot melt adhesives. It can also work synergistically with the triclosan structure, which has antibacterial properties, greatly improving the antibacterial performance of polyamide hot melt adhesives. The trimethoxysilane structure can react with moisture after application, hydrolyzing to generate silanol groups, which condense to form a stable cross-linked network structure, endowing polyamide hot melt adhesives with moisture properties. This allows it to retain moisture-curing properties after cooling and solidification, further enhancing the tensile and shear strength of polyamide hot melt adhesives.

[0041] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A moisture-curing polyamide hot melt adhesive, characterized in that, The polyamide hot melt adhesive comprises the following components in parts by weight: 30-40 parts of dimer acid; 10-20 parts of aliphatic dicarboxylic acid; 30-35 parts of polyether amine; 5-10 parts of aliphatic diamine; 8-10 parts of functionalized silane modifier; and 0.08-0.1 parts of phosphoric acid catalyst. The functionalized silane modifier is prepared by the following method: S1. Add nano-alumina to Tris-HCl buffer, stir well, add dopamine hydrochloride, adjust the pH to 8.5-8.6, place at room temperature, stir and react for 22-24 hours to obtain polydopamine-modified nano-alumina. S2. Add polydopamine-modified nano-alumina to ethanol, stir until homogeneous, add modified trimethoxysilane and triethylamine, place at 60-70℃, stir and react for 5-6 hours to obtain functionalized silane modifier.

2. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, The mass ratio of nano-alumina and Tris-HCl buffer in step S1 is 1:10-12.

3. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, The concentration of dopamine hydrochloride in the Tris-HCl buffer solution described in step S1 is 3-4 mg / mL.

4. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, In step S2, the mass ratio of polydopamine-modified nano-alumina, modified trimethoxysilane, and triethylamine is 1:0.3-0.4:0.08-0.

1.

5. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, The modified trimethoxysilane described in step S2 is prepared by the following method: Step 1: Add 3-aminopropyltrimethoxysilane to anhydrous dichloromethane, stir well, place at 30-35℃, slowly add epichlorohydrin dropwise, and after the addition is complete, stir the reaction for 3-4 hours to obtain trimethoxysilane chloride. Step 2: Add trimethoxysilane chloride, triclosan and triethylamine to anhydrous N,N-dimethylformamide, stir evenly, place at 50-60℃, and continue stirring for 5-6 hours to obtain modified trimethoxysilane.

6. The moisture-curing polyamide hot melt adhesive according to claim 5, characterized in that, The molar ratio of 3-aminopropyltrimethoxysilane and epichlorohydrin in the first step is 1:1-1.

1.

7. The moisture-curing polyamide hot melt adhesive according to claim 5, characterized in that, The molar ratio of trimethoxysilane chloride, triclosan, and triethylamine in the second step is 1:1-1.1:1.1-1.

2.

8. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, The aliphatic dicarboxylic acid is any one or a mixture of several of sebacic acid, azelaic acid, and adipic acid.

9. The moisture-curing polyamide hot melt adhesive according to claim 1, characterized in that, The aliphatic diamine is any one or a mixture of several of the following: decanediamine, hexamethylenediamine, and ethylenediamine.

10. A method for preparing a moisture-curing polyamide hot melt adhesive as described in any one of claims 1-9, characterized in that, The process includes the following steps: According to the weight ratio, under nitrogen protection, add dimer acid, aliphatic dicarboxylic acid, polyetheramine and phosphoric acid catalyst to the reaction vessel. Add aliphatic diamine at 140-150℃, raise the temperature to 180-200℃, react for 3-4 hours, add functionalized silane modifier, raise the temperature to 220-240℃, and continue the reaction for 2-3 hours to obtain polyamide hot melt adhesive.

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