A kind of copolyamide hot melt adhesive and preparation method thereof

Abstract

The present invention belongs to the field of polymer material bonding performance, and in particular to a copolyamide hot melt adhesive and a preparation method thereof. Polyamide resin is prepared using dimer acid, propionic acid, hexamethylenediamine and 1,3-diamino-2-propanol as raw materials, and then modified using modified organosilicon and carboxylated nano-silicon dioxide to obtain a copolyamide hot melt adhesive; polyamide resin is modified by adding organosilicon to the polyamide resin, and the introduction of flexible Si-O bonds can make the polymer chain segments rotate easily, which can eliminate part of the internal stress, absorb the fracture energy to the maximum extent, and effectively improve the fracture performance of the resin; in addition, the introduction of inorganic nanoparticles can combine the rigidity and stability of nanoparticles with the toughness and adhesion of grafted polymers, so that the grafted polymers have the excellent properties of both inorganic nanoparticles and organic polymers.

Description

Technical Field

[0001] The invention belongs to the field of polymer material bonding performance, and specifically relates to a copolyamide hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive is a solvent-free thermoplastic material that is solid at room temperature and melts into a viscous liquid after being heated to a certain temperature. It has a wide range of bonding and can be bonded to metals, non-polar materials and polar materials. It has high bonding strength and a very short cooling time during the bonding process. The bonding between objects is completed within seconds. It is non-toxic, harmless, green and environmentally friendly, easy to transport and store, and easy to process. It is widely used in paper lamination, automobiles, electronic devices, carton sealing, textiles, binding, furniture, footwear and packaging. With the development of society, the demand for hot melt adhesives in various industries has increased, and the requirements for the performance of hot melt adhesives have also become higher and higher.

[0003] Polyamide hot melt adhesives are divided into nylon hot melt adhesives and dimer acid hot melt adhesives. Dimer acid polyamide hot melt adhesives are dimer acid amide resins formed by the condensation of dimer acid and diamine or polyamine. They have the characteristics of narrow melting range, narrow softening point range, non-toxicity, good oil and chemical resistance, low temperature resistance, and good bonding strength to polar materials. Compared with other hot melt adhesives, polyamide hot melt adhesives have the characteristics of high bonding strength, good flexibility, good heat resistance and good medium resistance.

[0004] The Chinese patent with the announcement number CN115651599B discloses a polyamide hot melt adhesive and its preparation method and application, including either obtaining a polyamide hot melt adhesive by melt block copolymerization of a carboxyl-terminated nylon prepolymer and a hydroxyl-terminated polyether polyol, or obtaining a structural polyamide hot melt adhesive by directly melt random copolymerization of different types of nylon segment monomers; since the prepared polyamide hot melt adhesive has a high amide bond density, more hydrogen bonds can be formed between molecular chains, and the introduction of dipolyether polyol or polyether amine makes it have higher segment flexibility, thereby improving the bonding strength and bonding toughness of the polyamide hot melt adhesive. The raw material source is environmentally friendly and extensive, the preparation process is simple and easy to operate, and it is conducive to expanding production; the announcement number is CN118 Chinese patent No. 421257B discloses a high-strength, wear-resistant, low-pressure injection hot melt adhesive and its preparation method. The method comprises the following steps: dimer acid, modified monomer and ethylenediamine are polycondensed to form a chain polyamide structure, and then boron trifluoride ethylamine and modified filler are added. The carboxyl groups on the surface of the modified filler can be cross-linked with the active hydrogen on the nitrogen atom on the amide group in the chain polyamide molecular chain by acylation and dehydration to obtain a hot melt adhesive; boron trifluoride ethylamine can promote the cationic ring-opening polymerization reaction of the spiro ring structure in the hot melt adhesive molecule, causing the hot melt adhesive to expand slightly, thereby reducing the shrinkage rate of the hot melt adhesive; the modified filler forms a core-shell structure with the polyamide fiber, and contains a polysilsesquioxane structure, which can enhance the wear resistance of the hot melt adhesive with the silicone segment in the polyamide molecular chain. However, in the above preparation process, the raw materials are directly mixed, and the materials are easily unevenly distributed and agglomerated, thereby affecting the performance. How to further improve the adhesion of polyamide hot melt adhesive has become a focus of attention. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a copolyamide hot melt adhesive and a preparation method thereof. Polyamide resin is prepared using dimer acid, propionic acid, hexamethylenediamine and 1,3-diamino-2-propanol as raw materials, and then modified using modified silicone and carboxylated nano-silica. The prepared copolyamide hot melt adhesive has good bonding performance and low temperature resistance.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for preparing a copolyamide hot melt adhesive comprises the following steps:

[0008] S100, after uniformly stirring dimer acid, propionic acid and toluene, raising the temperature to 105-115° C., and maintaining the constant temperature for 15-25 min to obtain a mixture A; wherein the amount ratio of dimer acid, propionic acid and toluene is 0.014-0.056 mol: 0.006-0.024 mol: 8-32 mL;

[0009] S200, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, raising the temperature to 105-110°C, adding them to mixture A and introducing nitrogen, and reacting by raising the temperature in stages after the addition is completed, maintaining the temperature unchanged, evacuating and compressing for 20-40 minutes, cooling to 140-160°C, discharging, and cooling to room temperature to obtain mixture B; wherein, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, dividing them into 3-6 equal parts, adding one part each time, and the time interval between each addition is 10-20 minutes; the staged temperature reaction is specifically as follows: first raising the temperature to 155-165°C, maintaining the constant temperature for 15-25 minutes, and then raising the temperature to 220-240°C, and maintaining the constant temperature for 1.5-2.5 hours; the amount ratio of hexamethylenediamine to 1,3-diamino-2-propanol is 0.016-0.064 mol: 0.0018-0.0072 mol;

[0010] Polyamide hot melt adhesive itself has no special smell, can be quickly cured during application, can adhere to a variety of metal and non-metal surfaces, maintain high creep resistance under load, and is suitable for bonding a variety of materials. Therefore, in steps S100 and S200, dimer acid, propionic acid, hexamethylenediamine and 1,3-diamino-2-propanol are used as raw materials to prepare polyamide resin. Since a large number of bubbles will be generated in the early stage of synthesizing polyamide resin, the reaction is relatively violent, and the stirring and dispersion of the materials are difficult to control. Therefore, in the preparation process, the amine is added slowly in batches, which can make the reaction proceed smoothly and effectively ensure and improve the quality of the prepared polyamide resin; in addition, the organic inert solvent toluene is added during the reaction process, which can destroy the foam structure generated in the system in the early stage of the reaction, further avoid the violent expansion of the volume during the reaction, and make the reaction proceed stably. In addition, the addition of organic solvents is conducive to the uniform dispersion of the reactants and prevents the occurrence of agglomeration in the system;

[0011] S300, adding allyl glycidyl ether to the reactor, raising the temperature to 105-115°C under stirring and introducing nitrogen, maintaining the constant temperature for 20-40 minutes, then lowering the temperature to 70-80°C, adding catalyst A and hydrogen-containing silicone oil, raising the temperature to 105-115°C after the addition is completed, reacting for 4-6 hours to obtain modified silicone; wherein the catalyst A is chloroplatinic acid PT-5000; the hydrogen-containing silicone oil is any one or a mixture of H-018-120, H-020-120, H-025-120, H-028-120 and H-030-120; the catalyst A is added in a one-time addition manner, and the hydrogen-containing silicone oil is added in a dropwise manner, and the dropwise addition time is 40-60 minutes; the dosage ratio of allyl glycidyl ether, hydrogen-containing silicone oil and catalyst A is 100-220g:200-400g:150-320ul;

[0012] S400, adding toluene and modified silicone to mixture B, stirring evenly, adding catalyst B, raising the temperature to 30-40°C for reaction for 1-3h, and then lowering the temperature to room temperature to obtain a grafted polymer; wherein catalyst B is aluminum chloride; and the amount ratio of toluene, modified silicone and catalyst B is 10-30ml: 3-13g: 0.002-0.008g;

[0013] Although polyamide hot melt adhesive is excellent in heat resistance and bonding strength, it is prone to brittle fracture or cracking at low temperatures and has poor elasticity. Silicone has excellent low-temperature flexibility, thermal stability and oxidation resistance, so in the present invention, silicone is added to polyamide resin to modify it. In order to avoid the phenomenon of uneven dispersion caused by direct addition, in step S300, allyl glycidyl ether and silicone are first subjected to a silylation reaction to modify the silicone and introduce epoxy-containing side chains. Furthermore, in step S400, the modified silicone is grafted onto the polyamide resin by a ring-opening reaction between the modified silicone and the hydroxyl groups on the side chains of the prepared polyamide resin. The introduction of flexible Si-O bonds can make the polymer chain segments rotate easily, eliminate some internal stress, and absorb the fracture energy to the maximum extent. Even at low temperatures, the flexible chain segments still have a certain degree of rotational freedom and are not completely frozen. Therefore, the introduction of flexible chain segments into polyamide molecular chains can significantly improve the activity of resin network molecules, thereby improving the fracture toughness of the resin. In addition, when the resin is subjected to external tension, the presence of flexible chain segments can produce a large deformation, thereby enhancing the plastic deformation ability of the resin. At the same time, the polarity of Si-O bonds is extremely strong, with a significant ionization tendency, which can effectively improve the oxidation resistance of the material.

[0014] S500, blending the carboxylated nano-silica with the grafted polymer, adding a tackifier, paraffin, an antioxidant and a plasticizer, and mixing them evenly, raising the temperature to 180-210° C., reacting for 1-2 hours, and then cooling to room temperature to obtain the copolyamide hot melt adhesive.

[0015] Furthermore, step S500 specifically includes:

[0016] S510, dissolving nano-silicon dioxide in N,N-dimethylformamide solution, and dispersing by ultrasonication to obtain a suspension; wherein the amount ratio of nano-silicon dioxide to N,N-dimethylformamide solution is 0.5-1.2 g: 15-25 ml;

[0017] S520, dispersing silane coupling agent and succinic anhydride in N,N-dimethylformamide solution, raising the temperature to 30-45°C and stirring for 2-4 hours, then adding suspension and deionized water, continuing stirring for 4-8 hours, centrifuging and separating nano-silica, and washing with alcohol and centrifuging to obtain carboxylated nano-silica; wherein the amount ratio of silane coupling agent, succinic anhydride, N,N-dimethylformamide solution and deionized water is 0.2-0.8g: 0.4-1.2g: 12-20ml: 2-3ml;

[0018] S530, spraying the silane coupling agent diluted with deionized water on the surface of carboxylated nano-silica, ultrasonically treating it for 20-40 minutes and then drying it, adding it to the stirred and ultrasonically treated grafted polymer, mixing it evenly, and then adding a tackifier, paraffin, an antioxidant and a plasticizer, mixing evenly, raising the temperature to 180-210°C, reacting for 1-2 hours, and then cooling it to room temperature to obtain the copolyamide hot melt adhesive; wherein, the amount of silane coupling agent in deionized water is 0.002-0.005g / ml, and the mass ratio of silane coupling agent to carboxylated nano-silica is 0.02-0.05g:5-10g; wherein, by weight, 2-4 parts by weight of carboxylated nano-silica, 50-80 parts by weight of grafted copolymer, 8-15 parts by weight of tackifier, 2-5 parts by weight of paraffin, 1-3 parts by weight of antioxidant, and 2-6 parts by weight of plasticizer.

[0019] The tackifier is one or a mixture of rosin glycerol ester, hydrogenated rosin resin, C5 petroleum resin, C5 hydrogenated petroleum resin; the paraffin is microcrystalline wax or alkane paraffin; the antioxidant is antioxidant 264 or antioxidant 1010; the plasticizer is one or a mixture of dioctyl terephthalate, dioctyl sebacate, diisooctyl dodecanoate; and the silane coupling agent is KH550.

[0020] In order to further improve the wear resistance and toughness of grafted polymer, carboxylated nano silicon dioxide was further added in step S500, and the adding of inorganic nanoparticles can combine the rigidity, stability etc. of nanoparticles with the toughness, cohesiveness etc. of grafted polymer, so that grafted polymer has the excellent properties of inorganic nanoparticles and organic polymers simultaneously. The adding of inorganic nanoparticles is likely to become the crosslinking point of molecular chain in addition, plays the effect of environmental stress resistance. But inorganic nanoparticles are prone to reunion, so in the present invention, a layer of silane coupling agent is coated on the surface of inorganic nanoparticles, and a firm chemical bond is formed between the double bonds in the silane coupling agent and the active groups in the grafted polymer, thereby effectively improving the performance of grafted polymer. The carboxyl on the amide bond in the polyamide long chain and the inorganic nanoparticle surface can provide abundant hydrogen bond donors and acceptors in addition, and the hydroxyl on the substrate surface can be used as the binding site of hydrogen bond, has increased the bonding effect between grafted polymer and substrate, and will further improve the bonding properties of the prepared product.

[0021] A copolyamide hot melt adhesive is obtained by using the preparation method of any one of the above technical solutions.

[0022] The present invention has the following beneficial effects:

[0023] In the present invention, polyamide resin is modified by adding organosilicon to the resin, and the modified organosilicon is used to undergo a ring-opening reaction with the hydroxyl groups on the side chains of the prepared polyamide resin, and the modified organosilicon is grafted onto the polyamide resin. The introduction of flexible Si-O bonds can make the polymer chain segments rotate easily, eliminate part of the internal stress, absorb the fracture energy to the maximum extent, and effectively improve the fracture performance of the resin. The introduction of inorganic nanoparticles can combine the rigidity and stability of the nanoparticles with the toughness and adhesion of the grafted polymer, so that the grafted polymer has the excellent properties of both inorganic nanoparticles and organic polymers. At the same time, the carboxyl groups on its surface can provide abundant hydrogen bond donors and acceptors, thereby enhancing the bonding between the grafted polymer and the substrate. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] The dimer acid (industrial grade) used in the present invention was purchased from Zhejiang Yongzai Chemical Co., Ltd., propionic acid (AR), toluene (AR), and hexamethylenediamine (AR) were purchased from Shanghai Reagent Factory No. 1, 1,3-diamino-2-propanol, silane coupling agent, aluminum chloride, and succinic anhydride were purchased from Sinopharm Chemical Reagent Co., Ltd., allyl glycidyl ether (AR) was purchased from Shanghai MacLean Chemical Co., Ltd., hydrogenated silicone oil (H-020-120, H%=0.190%) was purchased from Zhejiang Runhe New Materials Co., Ltd., chloroplatinic acid isopropanol solution (Pt: 5000ppm) was purchased from Guangdong Kejunchi Co., Ltd., and nano-silica (content>99.9%) was purchased from Zhoushan Mingri Nanomaterials Co., Ltd. All reagents are commercially available.

[0026] Embodiment 1

[0027] A method for preparing a copolyamide hot melt adhesive comprises the following steps:

[0028] S100, after uniformly stirring dimer acid, propionic acid and toluene, raising the temperature to 110°C and maintaining the constant temperature for 20 minutes, to obtain a mixture A; wherein the amount ratio of dimer acid, propionic acid and toluene is 0.021 mol: 0.009 mol: 12 mL;

[0029] S200, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, raise the temperature to 110°C, add them to mixture A and introduce nitrogen, and after the addition is completed, heat them up in stages for reaction, after the reaction is completed, maintain the temperature unchanged, evacuate and compress and polymerize for 30 minutes, cool to 150°C, discharge, and cool to room temperature to obtain mixture B; wherein, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, divide them into 5 equal parts, add one part each time, and the time interval between each addition is 15 minutes; the staged temperature reaction is specifically as follows: first raise the temperature to 160°C, keep the temperature constant for 20 minutes, then raise the temperature to 230°C, and keep the temperature constant for 2 hours; the molar ratio of hexamethylenediamine to 1,3-diamino-2-propanol is 0.024 mol:0.0027 mol;

[0030] S300, add allyl glycidyl ether to the reactor, raise the temperature to 110°C under stirring and introduce nitrogen, keep the constant temperature for 30 minutes, then lower the temperature to 70°C, add catalyst A and hydrogen-containing silicone oil, raise the temperature to 110°C after the addition is completed, and react for 5 hours to obtain modified silicone; wherein, the catalyst A is chloroplatinic acid PT-5000; the hydrogen-containing silicone oil is H-020-120; the catalyst A is added once, and the hydrogen-containing silicone oil is added dropwise, and the dropwise addition time is 60 minutes; the dosage ratio of allyl glycidyl ether, hydrogen-containing silicone oil and catalyst A is 120g:320g:235ul;

[0031] S400, adding toluene and modified silicone to mixture B, stirring evenly, adding catalyst B, raising the temperature to 35°C for reaction for 2 hours, and then lowering the temperature to room temperature to obtain a grafted polymer; wherein catalyst B is aluminum chloride; and the amount ratio of toluene, modified silicone and catalyst B is 12ml:10g:0.006g;

[0032] S510, dissolving nano-silicon dioxide in N,N-dimethylformamide solution, and dispersing by ultrasonication to obtain a suspension; wherein the amount ratio of nano-silicon dioxide to N,N-dimethylformamide solution is 0.8 g:18 ml;

[0033] S520, dispersing silane coupling agent and succinic anhydride in N,N-dimethylformamide solution, raising the temperature to 40°C and stirring for 3 hours, then adding suspension and deionized water, continuing stirring for 6 hours, centrifuging and separating nano-silica, and washing with alcohol and centrifuging to obtain carboxylated nano-silica; wherein the amount ratio of silane coupling agent, succinic anhydride, N,N-dimethylformamide solution and deionized water is 0.5g:0.8g:18ml:2.5ml, and the silane coupling agent is KH550;

[0034] S530, spraying the silane coupling agent diluted with deionized water on the surface of carboxylated nano-silica, ultrasonically treating for 30 minutes and then drying, adding it to the grafted polymer that was stirred and ultrasonically treated, mixing evenly, and then adding tackifier, paraffin, antioxidant and plasticizer, mixing evenly, raising the temperature to 200°C, reacting for 2 hours and then cooling to room temperature to obtain a copolyamide hot melt adhesive; wherein the amount of silane coupling agent in deionized water is 0.003g / ml, and the amount of silane coupling agent in deionized water is 0.003g / ml. The mass ratio of the silane coupling agent to the carboxylated nano-silica is 0.03g:10g; wherein, by weight, the carboxylated nano-silica is 3 parts by weight, the graft copolymer is 72 parts by weight, the tackifier is 10 parts by weight, the paraffin is 3 parts by weight, the antioxidant is 2 parts by weight, and the plasticizer is 3 parts by weight; wherein the tackifier is hydrogenated rosin resin, the paraffin is microcrystalline wax, the antioxidant is antioxidant 264, the plasticizer is dioctyl terephthalate, and the silane coupling agent is KH550.

[0035] Embodiment 2

[0036] Compared with the first embodiment, this embodiment has the following differences, specifically:

[0037] In step S100, dimer acid, propionic acid and toluene are stirred evenly, and then the temperature is raised to 105°C and kept constant for 15 minutes, wherein the amount ratio of dimer acid, propionic acid and toluene is 0.014 mol: 0.006 mol: 8 mL;

[0038] In step S200, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, the temperature is raised to 105°C. After the reaction is completed, the temperature is maintained unchanged and vacuum decompression and compression polymerization is performed for 20 minutes. The mixture is cooled to 140°C. After mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, the mixture is divided into three equal parts, and one part is added each time, with a time interval of 20 minutes between each addition. The staged temperature increase reaction is specifically as follows: firstly, the temperature is raised to 155°C, and the temperature is kept constant for 15 minutes, and then the temperature is raised to 220°C, and the temperature is kept constant for 1.5 hours. The dosage ratio of hexamethylenediamine to 1,3-diamino-2-propanol is 0.016 mol: 0.0018 mol.

[0039] In step S300, allyl glycidyl ether is added to the reactor, the temperature is raised to 105°C under stirring and nitrogen is introduced, the temperature is kept constant for 20 minutes, then the temperature is lowered to 70°C, catalyst A and hydrogen-containing silicone oil are added, and after the addition is completed, the temperature is raised to 105°C and reacted for 4 hours. The hydrogen-containing silicone oil is added dropwise for 40 minutes; the dosage ratio of allyl glycidyl ether, hydrogen-containing silicone oil and catalyst A is 100g:200g:150ul;

[0040] In step S400, toluene and modified silicone are added to mixture B, stirred evenly, and then catalyst B is added, the temperature is raised to 30° C. and reacted for 1 hour, and the usage ratio of toluene, modified silicone and catalyst B is 10 ml: 3 g: 0.0028 g;

[0041] In step S510, the dosage ratio of nano-silicon dioxide and N,N-dimethylformamide solution is 0.5 g:15 ml;

[0042] In step S520, the silane coupling agent and succinic anhydride are dispersed in the N,N-dimethylformamide solution, the temperature is raised to 30°C and stirred for 2 hours, then the suspension and deionized water are added, and the stirring is continued for 4 hours. The amount ratio of the silane coupling agent, succinic anhydride, N,N-dimethylformamide solution and deionized water is 0.2g:0.4g:12ml:2ml;

[0043] In step S530, the silane coupling agent diluted with deionized water is sprayed on the surface of the carboxylated nano-silica, ultrasonically treated for 20 minutes and then dried, and then added to the stirred and ultrasonically treated grafted polymer and mixed evenly, and then the tackifier, paraffin, antioxidant and plasticizer are added, and after mixing evenly, the temperature is raised to 180°C and reacted for 1 hour; the amount of silane coupling agent in deionized water is 0.002g / ml, and the mass ratio of silane coupling agent to carboxylated nano-silica is 0.02g:5g; wherein, by weight, 2 parts by weight of carboxylated nano-silica, 50 parts by weight of grafted copolymer, 8 parts by weight of tackifier, 2 parts by weight of paraffin, 1 part by weight of antioxidant, and 2 parts by weight of plasticizer.

[0044] The rest is as per Example 1.

[0045] Embodiment 3

[0046] Compared with the first embodiment, this embodiment has the following differences, specifically:

[0047] In step S100, dimer acid, propionic acid and toluene are stirred evenly, and then the temperature is raised to 115° C. and the constant temperature is maintained for 25 minutes, wherein the amount ratio of dimer acid, propionic acid and toluene is 0.056 mol: 0.024 mol: 32 mL;

[0048] In step S200, after mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, the temperature is raised to 110°C. After the reaction is completed, the temperature is maintained unchanged and vacuum decompression and compression polymerization is performed for 40 minutes, and then cooled to 160°C. After mixing hexamethylenediamine and 1,3-diamino-2-propanol evenly, they are divided into 6 equal parts, and one part is added each time, and the time interval between each addition is 10 minutes; the staged temperature increase reaction is specifically as follows: firstly, the temperature is raised to 165°C, and the temperature is kept constant for 25 minutes, and then the temperature is raised to 240°C, and the temperature is kept constant for 2.5 hours; the dosage ratio of hexamethylenediamine and 1,3-diamino-2-propanol is 0.064 mol: 0.0072 mol;

[0049] In step S300, allyl glycidyl ether is added to the reactor, the temperature is raised to 115°C under stirring and nitrogen is introduced, the temperature is kept constant for 40 minutes, then the temperature is lowered to 80°C, catalyst A and hydrogen-containing silicone oil are added, and after the addition is completed, the temperature is raised to 115°C and reacted for 6 hours. The hydrogen-containing silicone oil is added dropwise for 60 minutes; the dosage ratio of allyl glycidyl ether, hydrogen-containing silicone oil and catalyst A is 220g:400g:320ul;

[0050] In step S400, toluene and modified silicone are added to mixture B, stirred evenly, and then catalyst B is added, the temperature is raised to 40° C. and reacted for 3 hours. The usage ratio of toluene, modified silicone and catalyst B is 30 ml: 13 g: 0.008 g;

[0051] In step S510, the dosage ratio of nano-silicon dioxide and N,N-dimethylformamide solution is 1.2 g: 25 ml;

[0052] In step S520, the silane coupling agent and succinic anhydride are dispersed in the N,N-dimethylformamide solution, the temperature is raised to 45°C and stirred for 4 hours, then the suspension and deionized water are added, and the stirring is continued for 8 hours. The amount ratio of the silane coupling agent, succinic anhydride, N,N-dimethylformamide solution and deionized water is 0.8g:1.2g:20ml:3ml;

[0053] In step S530, the silane coupling agent diluted with deionized water is sprayed on the surface of the carboxylated nano-silica, ultrasonically treated for 40 minutes and then dried, and then added to the stirred and ultrasonically treated grafted polymer and mixed evenly, and then the tackifier, paraffin, antioxidant and plasticizer are added, and after mixing evenly, the temperature is raised to 210°C and reacted for 2 hours; the amount of silane coupling agent in deionized water is 0.005g / ml, and the mass ratio of silane coupling agent to carboxylated nano-silica is 0.05g:10g; wherein, by weight, 4 parts by weight of carboxylated nano-silica, 80 parts by weight of grafted copolymer, 15 parts by weight of tackifier, 5 parts by weight of paraffin, 3 parts by weight of antioxidant, and 6 parts by weight of plasticizer.

[0054] The rest is as per Example 1.

[0055] Comparative Example 1

[0056] Compared with Example 1, this comparative example does not modify the organosilicon, and the rest is referred to Example 1, as follows:

[0057] Step S100, refer to step S100 of embodiment 1;

[0058] Step S200, refer to step S200 of embodiment 1;

[0059] Step S300, adding 10 g of hydrogen-containing silicone oil into mixture B and stirring evenly to obtain a graft copolymer;

[0060] Step S400, refer to step S510, step S520 and step S530 of the first embodiment.

[0061] Comparative Example 2

[0062] Compared with Example 1, this comparative example directly adds carboxylated nano-silica during the preparation of the hot melt adhesive, and the rest is as follows, referring to Example 1:

[0063] Step S100, refer to step S100 of embodiment 1;

[0064] Step S200, refer to step S200 of embodiment 1;

[0065] Step S300, refer to step S300 of embodiment 1;

[0066] Step S400, refer to step S400 of embodiment 1;

[0067] Step S500, adding carboxylated nano-silica to the stirred and ultrasonically treated grafted polymer, mixing evenly, then adding tackifier, paraffin, antioxidant and plasticizer, mixing evenly, raising the temperature to 200°C, reacting for 2 hours and then cooling to room temperature to obtain a copolyamide hot melt adhesive; wherein, the preparation of carboxylated nano-silica refers to step S510 and step S520 of Example 1; wherein, by weight, 3 parts by weight of carboxylated nano-silica, 72 parts by weight of grafted copolymer, 10 parts by weight of tackifier, 3 parts by weight of paraffin, 2 parts by weight of antioxidant and 3 parts by weight of plasticizer.

[0068] Comparative Example 3

[0069] Compared with Example 1, this comparative example directly adds nano silicon dioxide during the preparation of the hot melt adhesive, and the rest is as follows, referring to Example 1:

[0070] Step S100, refer to step S100 of embodiment 1;

[0071] Step S200, refer to step S200 of embodiment 1;

[0072] Step S300, refer to step S300 of embodiment 1;

[0073] Step S400, refer to step S400 of embodiment 1;

[0074] Step S500, adding nano-silicon dioxide to the stirred and ultrasonically treated grafted polymer, mixing evenly, then adding tackifier, paraffin, antioxidant and plasticizer, mixing evenly, raising the temperature to 200°C, reacting for 2 hours, and then cooling to room temperature to obtain a copolyamide hot melt adhesive; wherein, by weight, 3 parts by weight of nano-silicon dioxide, 72 parts by weight of graft copolymer, 10 parts by weight of tackifier, 3 parts by weight of paraffin, 2 parts by weight of antioxidant, and 3 parts by weight of plasticizer.

[0075] Comparative Example 4

[0076] Compared with Example 1, this comparative example does not add nano silicon dioxide during the preparation of the hot melt adhesive, and the rest is referred to Example 1, as follows:

[0077] Step S100, refer to step S100 of embodiment 1;

[0078] Step S200, refer to step S200 of embodiment 1;

[0079] Step S300, refer to step S300 of embodiment 1;

[0080] Step S400, refer to step S400 of embodiment 1;

[0081] Step S500, mixing the grafted polymer prepared in step S400 evenly, then adding a tackifier, paraffin, an antioxidant and a plasticizer, mixing evenly, raising the temperature to 200°C, reacting for 2 hours and then cooling to room temperature to obtain a copolyamide hot melt adhesive; wherein, by weight, the grafted copolymer comprises 72 parts by weight, the tackifier 10 parts by weight, the paraffin 3 parts by weight, the antioxidant 2 parts by weight and the plasticizer 3 parts by weight.

[0082] Comparative Example 5

[0083] Compared with Example 1, this comparative example does not add silicone during the preparation of the hot melt adhesive, and the rest is referred to Example 1, as follows:

[0084] Step S100, refer to step S100 of embodiment 1;

[0085] Step S200, refer to step S200 of embodiment 1;

[0086] Step S300, spraying the silane coupling agent diluted with deionized water on the surface of the carboxylated nano-silica, ultrasonically treating it for 30 minutes and then drying it, adding it to the mixture B prepared by stirring and ultrasonically treating step S200, mixing it evenly, and then adding a tackifier, paraffin, an antioxidant and a plasticizer, mixing evenly, raising the temperature to 200°C, reacting for 2 hours, and then cooling to room temperature to obtain a copolyamide hot melt adhesive; wherein, the amount of the silane coupling agent in deionized water is 0.003g / ml, and the mass ratio of the silane coupling agent to the carboxylated nano-silica is 0.03g:10g; wherein, by weight, 3 parts by weight of carboxylated nano-silica, 72 parts by weight of mixture B, 10 parts by weight of tackifier, 3 parts by weight of paraffin, 2 parts by weight of antioxidant, and 3 parts by weight of plasticizer.

[0087] Comparative Example 6

[0088] Compared with Example 1, this comparative example does not add organosilicon and nano-silicon dioxide during the preparation process, and the rest is referred to Example 1, as follows:

[0089] Step S100, refer to step S100 of embodiment 1;

[0090] Step S200, refer to step S200 of embodiment 1;

[0091] Step S300, uniformly mix the mixture B, tackifier, paraffin, antioxidant and plasticizer prepared in step S200, raise the temperature to 200°C, react for 2 hours, and then cool to room temperature to obtain a copolyamide hot melt adhesive; wherein, by weight, the mixture B comprises 72 parts by weight, the tackifier 10 parts by weight, the paraffin 3 parts by weight, the antioxidant 2 parts by weight, and the plasticizer 3 parts by weight.

[0092] Related tests

[0093] The products prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were tested as follows:

[0094] Molding shrinkage performance: refer to GB / T 15585-1995 standard test;

[0095] Wear resistance: Tested according to ISO 4649-2017 standard;

[0096] The test data is shown in Table 1.

[0097] Table 1 Shrinkage and wear resistance test results

[0098]

[0099] It can be seen from the test data in the above table that the polyamide hot melt adhesives prepared in Examples 1 to 3 have better anti-shrinkage ability and wear resistance than those prepared in Comparative Examples 1 to 6.

[0100] Adhesion performance: The test was carried out according to ASTM D1002-10 test standard using a CMT 4104 tensile material testing machine (Shenzhen Xinsansi Material Testing Co., Ltd.), with a rate of 5 mm / min. The bonding strength was calculated by dividing the maximum bonding force by the bonding area. The test results are shown in Table 2.

[0101] Table 2 Adhesion performance

[0102]

[0103] It can be seen from the test data in the above table that the polyamide hot melt adhesives prepared in Examples 1 to 3 have greater bonding strength than those prepared in Comparative Examples 1 to 6.

[0104] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0105] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a copolyamide hot melt adhesive, characterized in that: The steps include: S100, after uniformly stirring dimer acid, propionic acid and toluene, raising the temperature to 105-115° C., and maintaining the constant temperature for 15-25 minutes to obtain a mixture A; S200, mixing hexamethylenediamine and 1,3-diamino-2-propanol uniformly, raising the temperature to 105-110° C., adding them to mixture A and introducing nitrogen, raising the temperature in stages after the addition is completed, and after the reaction is completed, maintaining the temperature unchanged, vacuumizing and reducing pressure to polymerize for 20-40 minutes, cooling to 140-160° C., discharging, and cooling to room temperature to obtain mixture B; S300, add allyl glycidyl ether to the reactor, raise the temperature to 105-115° C. under stirring and introduce nitrogen, maintain the constant temperature for 20-40 minutes, then lower the temperature to 70-80° C., add catalyst A and hydrogen-containing silicone oil, raise the temperature to 105-115° C. after the addition is complete, react for 4-6 hours, and obtain modified silicone; S400, adding toluene and modified silicone to mixture B, stirring evenly, adding catalyst B, raising the temperature to 30-40° C. for reaction for 1-3 hours, and then lowering the temperature to room temperature to obtain a grafted polymer; S500, blending carboxylated nano-silica with the grafted polymer, adding a tackifier, paraffin, an antioxidant and a plasticizer, mixing evenly, raising the temperature to 180-210° C., reacting for 1-2 hours and then cooling to room temperature to obtain the copolyamide hot melt adhesive; In step S200, hexamethylenediamine and 1,3-diamino-2-propanol are mixed evenly and then divided into 3-6 equal portions, and one portion is added each time, with a time interval of 10-20 minutes between each addition; Step S500 specifically includes: S510, dissolving nano-silicon dioxide in N,N-dimethylformamide solution, and ultrasonically dispersing to obtain a suspension; S520, dispersing a silane coupling agent and succinic anhydride in an N,N-dimethylformamide solution, raising the temperature to 30-45° C. and stirring for 2-4 hours, then adding the suspension and deionized water, continuing stirring for 4-8 hours, centrifuging and separating the nano-silica, and washing with alcohol and centrifuging to obtain carboxylated nano-silica; S530, spraying the silane coupling agent diluted with deionized water on the surface of the carboxylated nano-silica, ultrasonically treating for 20-40 minutes and then drying, adding it to the stirred and ultrasonically treated grafted polymer and mixing evenly, then adding tackifier, paraffin, antioxidant and plasticizer, mixing evenly, raising the temperature to 180-210° C., reacting for 1-2 hours and then cooling to room temperature to obtain the copolyamide hot melt adhesive.

2. The method for preparing the copolyamide hot melt adhesive according to claim 1, characterized in that: In step S200, the temperature is raised in stages as follows: first, the temperature is raised to 155-165°C, and the temperature is maintained for 15-25 minutes; then, the temperature is raised to 220-240°C, and the temperature is maintained for 1.5-2.5 hours.

3. The method for preparing the copolyamide hot melt adhesive according to claim 1, characterized in that: In step S300, the catalyst A is chloroplatinic acid PT-5000; the hydrogen-containing silicone oil is any one of H-018-120, H-020-120, H-025-120, H-028-120 and H-030-120, or a mixture of several thereof.

4. The method for preparing the copolyamide hot melt adhesive according to claim 1, characterized in that: In step S300, the catalyst A is added in one addition, and the hydrogenated silicone oil is added dropwise, and the duration of the dropwise addition is 40-60 minutes.

5. The method for preparing the copolyamide hot melt adhesive according to claim 1, characterized in that: In step S400, catalyst B is aluminum chloride.

6. A copolyamide hot melt adhesive, characterized in that: The copolyamide hot melt adhesive is obtained by the preparation method according to any one of claims 1 to 5.

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