Epoxy resin binder for metal matrix as well as preparation method and application of epoxy resin binder

Abstract

The invention belongs to the field of polymer preparations, and particularly relates to an epoxy resin binder for a metal matrix as well as a preparation method and application of the epoxy resin binder. The epoxy resin adhesive for the metal matrix comprises the following components in parts by mass: 100 parts of epoxy resin, 5-10 parts of a diluent, 10-30 parts of a toughening agent, 1-10 parts of a diluent, 20-40 parts of filler, 1-3 parts of a silane coupling agent, 0.5-2 parts of a thixotropic agent, 30-60 parts of a curing agent and 1-3 parts of a silane coupling agent. According to the technical scheme, through the collaborative design of gradient curing of the thiol curing agent and the amine curing agent, the high strength of epoxy resin is kept, meanwhile, the bottlenecks that a traditional system is large in brittleness, prone to interface failure and free of self-repairing are broken through, and an innovative solution is provided for metal matrix bonding.

Description

Technical Field

[0001] This invention belongs to the field of polymer formulations, specifically relating to an epoxy resin adhesive for metal matrices, its preparation method, and its application. Background Technology

[0002] Epoxy resin adhesives are a class of thermosetting polymers with epoxy groups (-CH(O)CH-) as the reaction core. They possess excellent bonding strength, chemical stability, and heat resistance, and are widely used in structural bonding of metals, ceramics, and composite materials. Their curing process involves ring-opening polymerization of epoxy groups with amines, anhydrides, or thiols as curing agents, forming a three-dimensional cross-linked network that imparts high mechanical strength and durability to the material.

[0003] Despite the superior performance of epoxy resin adhesives, the following key issues still exist in practical applications:

[0004] 1. High brittleness and insufficient toughness: The crosslinking density of the cured epoxy resin is high, and the elongation at break is usually less than 5%, making it prone to brittle fracture under impact or vibration loads.

[0005] 2. Interfacial adhesion failure: The chemical bond between the oxide layer on the metal surface and the epoxy resin is weak, and interfacial peeling is prone to occur under long-term humid and hot conditions (accounting for more than 60% of failure cases). Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an epoxy resin adhesive for metal substrates, its preparation method, and its application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An epoxy resin adhesive for metal substrates comprises the following components in parts by weight: 100 parts epoxy resin, 5-10 parts diluent, 10-30 parts toughening agent, 1-10 parts diluent, 20-40 parts filler, 1-3 parts silane coupling agent, 0.5-2 parts thixotropic agent, 30-60 parts curing agent, and 1-3 parts silane coupling agent.

[0009] Preferably, the composition comprises the following components in parts by weight: 100 parts epoxy resin, 8 parts diluent, 18 parts toughening agent, 8 parts diluent, 26.6 parts filler, 2 parts silane coupling agent, 1.5 parts thixotropic agent, 40 parts curing agent, and 2 parts silane coupling agent.

[0010] The preferred composition is 100 parts epoxy resin, 18 parts toughening agent, 8 parts diluent, 26.6 parts filler, 1.5 parts thixotropic agent, 40 parts curing agent, and 2 parts silane coupling agent.

[0011] The curing agent is a combination of amine curing agents and thiol curing agents;

[0012] Preferably, the amine curing agent is one or a combination of at least two of polyamide, polyether amine, fatty amine, phenolic amine, aromatic amine, and alicyclic amine;

[0013] Preferably, the thiol curing agent is at least one of pentaerythritol tetra(3-mercaptopropionate) PETMP or trimethylolpropane tri(3-mercaptopropionate);

[0014] Preferably, the mass ratio of the amine curing agent to the thiol curing agent is (5-7):(3-5); more preferably, it is 6:4.

[0015] Preferably, the epoxy resin is one or a combination of at least two of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, and glycidyl ester type epoxy resin.

[0016] Preferably, the toughening agent is one or a combination of at least two of the following: CTBN modified epoxy resin, dimer acid modified epoxy resin, core-shell rubber modified epoxy resin, polyurethane, liquid butyl rubber, polyacrylate, and silicone resin.

[0017] Preferably, the diluent is one or a combination of at least two of diglycidyl ether, polyglycidyl ether, alkylglycidyl ether, benzylglycidyl ether, and allylglycidyl ether.

[0018] Preferably, the filler is one or more of the following: calcium carbonate, calcium oxide, wollastonite, mica powder, carbon black, kaolin, barite, quartz powder, talc powder, organobentonite, and glass microspheres.

[0019] Preferably, the silane coupling agent is one or more selected from vinylsilane, aminosilane, epoxysilane, mercaptosilane, and methacryloxysilane.

[0020] Preferably, the thixotropic agent is one or more of fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax.

[0021] This invention also includes a method for preparing the aforementioned epoxy resin adhesive for metal substrates, comprising the following steps:

[0022] Step 1: Premixing the matrix resin: Stir and mix the epoxy resin and diluent at 40-80℃; preferably 60℃; add the silane coupling agent, ultrasonically disperse until completely dissolved, then add the filler and toughening agent to obtain the matrix resin mixture;

[0023] Step 2: Construction of the curing system: Mix the thiol curing agent and the amine curing agent in a certain proportion, then add the thixotropic agent and stir at low speed; preferably at 500 rpm for 15 min.

[0024] Step 3: Add the cured system obtained in Step 2 to the matrix resin mixture obtained in Step 1 to obtain an epoxy resin adhesive.

[0025] The present invention also includes the application of the aforementioned epoxy resin adhesive for metal substrates.

[0026] It is used for bonding metal substrates; preferably, the metal substrate is at least one of cold-rolled steel, galvanized sheet, stainless steel, sandblasted steel, and aluminum alloy.

[0027] The application specifically includes the following steps: uniformly coating the metal substrate with an epoxy resin adhesive on the surface of the metal substrate and then curing it.

[0028] The curing process is a staged curing process; preferably, the curing temperature is 35-55℃, held for 0.2-1 hours, then the temperature is raised to 75-90℃ and held for 1-3 hours, and then the temperature is raised to 100-150℃ and held for 1-3 hours.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] The technical solution of this application, through the synergistic design of gradient curing with the addition of thiol curing agents and amine curing agents, overcomes the bottlenecks of high brittleness and easy interface failure in traditional systems while maintaining the high strength of epoxy resin, and provides an innovative solution for metal matrix bonding.

[0031] Specifically, the thiol curing agent preferentially reacts with the epoxy group at 35-55℃ to achieve rapid initial curing and surface drying within 30 minutes, avoiding sagging; the amine curing agent deeply crosslinks at 100-120℃, constructing a high-density network, which increases the final strength by 20-30%; at the same time, the thiol group (-SH) forms a strong coordination bond with the metal surface oxide, improving the interfacial bonding strength, ensuring the bonding effect without grinding the metal substrate surface; the amine curing agent ensures the high degree of crosslinking of the bulk resin, maintaining the overall mechanical properties. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the preferred embodiments.

[0033] Example 1

[0034] 1. A composition of an epoxy resin adhesive for a metal matrix: comprising 100 parts of bisphenol A type epoxy resin, 18 parts of toughening agent CTBN modified epoxy resin, 8 parts of diluent benzyl glycidyl ether, 26.6 parts of filler (10 parts of calcium carbonate, 15 parts of calcium oxide, and 1.6 parts of organobentonite), 1.5 parts of thixotropic agent fumed silica, 40 parts of curing agent (12 parts of PETMP and 28 parts of polyetheramine D230), and 2 parts of silane coupling agent KH-560;

[0035] 2. A method for preparing epoxy resin adhesives for metal substrates, comprising the following steps:

[0036] Step 1: Premixed matrix resin: Epoxy resin and diluent are stirred and mixed at 60°C; silane coupling agent is added, ultrasonically dispersed until completely dissolved, and then filler and toughening agent are added to obtain matrix resin mixture;

[0037] Step 2: Construction of the curing system: Mix the thiol curing agent and the amine curing agent in proportion, then add the thixotropic agent and stir at low speed of 500 rpm for 15 minutes;

[0038] Step 3: Add the cured system obtained in Step 2 to the matrix resin mixture obtained in Step 1 to obtain an epoxy resin adhesive.

[0039] 3. Application of epoxy resin adhesives for metal substrates: The epoxy resin adhesive is applied to the bonding of metal substrates, specifically including the following steps: The epoxy resin adhesive is uniformly coated onto the surface of the metal substrate (stainless steel) and cured; the curing temperature is 40℃, and the temperature is maintained for 0.5 hours, then the temperature is increased to 80℃ and maintained for 2 hours, and then the temperature is further increased to 120℃ and maintained for 2 hours.

[0040] Example 2

[0041] The difference between Example 2 and Example 1 is that the ratio of PETMP to polyetheramine D230 in the curing agent is different: 16 parts of PETMP and 24 parts of polyetheramine D230.

[0042] Example 3

[0043] The difference between Example 3 and Example 1 is that the ratio of PETMP to polyetheramine D230 in the curing agent is different: 20 parts of PETMP and 20 parts of polyetheramine D230.

[0044] Comparative Example 1

[0045] The difference between Comparative Example 1 and Example 1 is that only the curing agent PETMP was added.

[0046] Comparative Example 2

[0047] The difference between Comparative Example 2 and Example 1 is that only the curing agent polyetheramine D230 was added.

[0048] Comparative Example 3

[0049] The difference between Comparative Example 3 and Example 1 is that the curing temperature is different. A one-step curing method is used, which specifically includes the following steps: the metal substrate is uniformly coated with an epoxy resin adhesive on the surface of the metal substrate and then cured; the curing temperature is 120°C and the curing time is 2 hours.

[0050] Table 1 shows the test parameters for different embodiments and comparative examples. Table 2 shows the test results for different embodiments and comparative examples;

[0051] Table 1

[0052] Test Standards parameter Shear strength ASTMD1002 Stainless steel substrate, tested at 25℃ Tg ISO 11357 (DSC Method) Heating rate 10℃ / min Elongation at break ISO527 Dumbbell-shaped specimen, tensile rate 5 mm / min Moist heat aging GB / T15905 85℃ / 85%RH, 1000 hours Salt spray corrosion ASTMB117 5% NaCl solution, 35℃, 500 hours

[0053] Table 2

[0054]

[0055]

[0056] As can be seen from the results in the table, with the technical solution of this application, the addition of composite curing agents, of which thiol curing agents can improve flexibility and amine curing agents can ensure rigidity and strength, but a single curing agent, such as PETMP used only in Comparative Example 1, has a Tg of only 98 degrees Celsius, which is prone to high-temperature softening failure. A single amine curing agent is prone to brittle fracture, with an elongation of only 5.1% (Comparative Example 2). At the same time, if a one-step curing method is used, the metal interface is prone to insufficient wetting before curing. In addition, the shrinkage stress of the body is relatively concentrated, making it irreparable and prone to forming local agglomeration into micro-regions.

[0057] In summary, the technical solution of this application, through the synergistic design of gradient curing with the addition of thiol curing agents and amine curing agents, overcomes the bottlenecks of traditional systems such as high brittleness, easy interface failure, and lack of self-healing while maintaining the high strength of epoxy resin, providing an innovative solution for metal matrix bonding.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An epoxy resin adhesive for metal substrates, characterized in that, It comprises the following components by weight: 100 parts epoxy resin, 5-10 parts diluent, 10-30 parts toughening agent, 1-10 parts diluent, 20-40 parts filler, 1-3 parts silane coupling agent, 0.5-2 parts thixotropic agent, and 30-60 parts curing agent.

2. The epoxy resin adhesive for metal substrates according to claim 1, characterized in that, It comprises the following components by weight: 100 parts epoxy resin, 8 parts diluent, 18 parts toughening agent, 8 parts diluent, 26.6 parts filler, 2 parts silane coupling agent, 1.5 parts thixotropic agent, and 40 parts curing agent; The preferred composition is 100 parts epoxy resin, 18 parts toughening agent, 8 parts diluent, 26.6 parts filler, 1.5 parts thixotropic agent, 2 parts silane coupling agent, and 40 parts curing agent.

3. The epoxy resin adhesive for metal substrates according to claim 1, characterized in that, The curing agent is a combination of amine curing agents and thiol curing agents; Preferably, the amine curing agent is one or a combination of at least two of polyamide, polyether amine, fatty amine, phenolic amine, aromatic amine, and alicyclic amine; Preferably, the thiol curing agent is at least one of pentaerythritol tetra(3-mercaptopropionate) PETMP or trimethylolpropane tri(3-mercaptopropionate); Preferably, the mass ratio of the amine curing agent to the thiol curing agent is (5-7):(3-5); more preferably, it is 7:

3.

4. The epoxy resin adhesive for metal substrates according to claim 1, characterized in that, The epoxy resin is one or a combination of at least two of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, and glycidyl ester type epoxy resin. The toughening agent is one or a combination of at least two of the following: CTBN modified epoxy resin, dimer acid modified epoxy resin, core-shell rubber modified epoxy resin, polyurethane, liquid butyl rubber, polyacrylate, and silicone resin. Preferably, the diluent is one or a combination of at least two of diglycidyl ether, polyglycidyl ether, alkylglycidyl ether, benzylglycidyl ether, and allylglycidyl ether. Preferably, the filler is one or more of the following: calcium carbonate, calcium oxide, wollastonite, mica powder, carbon black, kaolin, barite, quartz powder, talc powder, organobentonite, and glass microspheres. Preferably, the coupling agent is one or more selected from vinylsilane, aminosilane, epoxysilane, mercaptosilane, and methacryloxysilane. Preferably, the thixotropic agent is one or more of fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax.

5. A method for preparing an epoxy resin adhesive for a metal matrix according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Premixing the matrix resin: Stir and mix the epoxy resin and diluent at 40-80℃; preferably 60℃; add the silane coupling agent, ultrasonically disperse until completely dissolved, then add the filler and toughening agent to obtain the matrix resin mixture; Step 2: Construction of the curing system: Mix the thiol curing agent and the amine curing agent in a certain proportion, then add the thixotropic agent and stir at low speed; preferably at 500 rpm for 15 min. Step 3: Add the cured system obtained in Step 2 to the matrix resin mixture obtained in Step 1 to obtain an epoxy resin adhesive.

6. The application of an epoxy resin adhesive for a metal matrix as described in any one of claims 1-4.

7. The application according to claim 6, characterized in that, It is used for bonding metal substrates; preferably, the metal substrate is at least one of cold-rolled steel, galvanized sheet, stainless steel, sandblasted steel, and aluminum alloy.

8. The application according to claim 6, characterized in that, Specifically, the steps include: uniformly coating the metal substrate with an epoxy resin adhesive on the surface of the metal substrate and then curing it.

9. The application according to claim 8, characterized in that, The curing process is a staged curing process; preferably, the curing temperature is 35-55℃, held for 0.2-1 hours, then the temperature is raised to 75-90℃ and held for 1-3 hours, and then the temperature is raised to 100-150℃ and held for 1-3 hours.

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