High-performance sheet metal bonding foaming material

Abstract

The invention relates to the technical field of foaming materials, and discloses a high-performance sheet metal bonding foaming material which comprises the following components in percentage by weight: 60-70wt% of bisphenol A epoxy resin, 3-5wt% of a chemical foaming agent, 15-20wt% of a curing agent, 5-8wt% of a toughening agent and 10-15wt% of nano silicon dioxide filler. The epoxy value of the bisphenol A type epoxy resin is 0.25-0.45, and the decomposition temperature of the chemical foaming agent is 195-205 DEG C. The high-performance sheet metal bonding foaming material has the advantage of high bonding strength, the material is foamed and expanded in the curing process, the contact area with a sheet metal part is increased through a foam hole structure, and the bonding strength of the sheet metal part is improved. Meanwhile, a cross-linked structure formed by the matrix resin and the curing agent provides strong adhesive force, so that the bonding strength between the material and a sheet metal part is remarkably improved, and the shear strength of the material is improved by 12% compared with that of a common bonding material through tests.

Description

Technical Field

[0001] The invention relates to the technical field of foam materials, in particular to a high-performance sheet metal bonding foam material. Background Art

[0002] In modern industrial production, sheet metal connections are widely used in many fields such as automobile manufacturing, aerospace, and electronic equipment. Traditional sheet metal connection methods such as welding and riveting have certain limitations. Welding may cause thermal deformation that affects the precision and surface quality of sheet metal parts, while riveting increases weight and is not suitable for some occasions with high requirements for appearance. Adhesive technology has gradually become an important alternative because of its advantages such as good sealing, shock absorption, and the ability to connect different materials.

[0003] The sheet metal bonding materials currently on the market have many deficiencies in performance. For example, ordinary bonding materials lack the foaming and expansion properties after curing, making it difficult to fill gaps of complex shapes, resulting in weak bonding; although some foaming materials have the ability to expand, their bonding strength will drop significantly in harsh environments such as high temperature and high humidity, and they cannot meet the needs of long-term stable use. In addition, the curing time of some materials is too long or too short, which is not conducive to the process operation in actual production and affects production efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a high-performance sheet metal bonding foaming material to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a high-performance sheet metal bonding foaming material, comprising the following components by weight percentage: 60-70wt% of bisphenol A epoxy resin, 3-5wt% of chemical foaming agent, 15-20wt% of curing agent, 5-8wt% of toughening agent, and 10-15wt% of nano-silica filler; the epoxy value of the bisphenol A epoxy resin is 0.25-0.45, and the decomposition temperature of the chemical foaming agent is 195-205 degrees Celsius.

[0006] Optionally, the nanoscale filler is one of nano-silicon dioxide and nano-calcium carbonate, or a mixture of both.

[0007] Optionally, the toughening agent comprises the following components in parts by weight: 59.6-60.2 parts of polyolefin elastomer POE; 30-50 parts of thermoplastic polyurethane; and 9.2-10 parts of expanded polystyrene EPS.

[0008] Optionally, the composition of the curing agent is expressed in parts by weight as follows: 5-15 parts of alicyclic amine curing agent, 28-85 parts of polyether amine curing agent, 10-80 parts of curing accelerator, and 1-3.5 parts of adhesion accelerator.

[0009] The present invention provides a method for preparing a high-performance sheet metal bonding foaming material, comprising the following steps:

[0010] S1. Add the main resin, toughening agent and part of the fillers into a high-speed mixer, and stir for 20 - 55 min at a temperature of 25 - 100 °C and a stirring speed of 500 - 1800 r / min to obtain a premix;

[0011] S2. Mix the foaming agent and curing agent with the remaining fillers respectively in a low-speed mixer;

[0012] S3. Mix the premix with the fillers containing the foaming agent and curing agent in a vacuum kneader, keep the vacuum degree at -0.085 to -0.098 MPa, and the kneading time at 30 - 90 min to obtain a high-performance sheet metal bonding foaming material.

[0013] Optionally, the part of the fillers accounts for 50% of the total amount of the fillers.

[0014] Optionally, the vacuum degree of the vacuum kneader is -0.09 MPa, and the kneading time is 60 min.

[0015] An application of a high-performance sheet metal bonding foaming material in the field of sheet metal bonding.

[0016] The high-performance sheet metal bonding foaming material foams and expands during the curing process, fills the gaps between sheet metal parts, and forms a firm bond.

[0017] The high-performance sheet metal bonding foaming material maintains stable bonding performance in an environment with a temperature range of -40 °C to 80 °C and a humidity not higher than 90%.

[0018] Compared with the prior art, the present invention provides a high-performance sheet metal bonding foaming material, which has the following beneficial effects:

[0019] 1. The high-performance sheet metal bonding foaming material has the advantage of high bonding strength. During the curing process, the material foams and expands, and the cell structure increases the contact area with the sheet metal parts. At the same time, the cross-linked structure formed by the main resin and the curing agent provides strong adhesion, significantly improving the bonding strength between the material and the sheet metal parts. After testing, its shear strength is 12% higher than that of ordinary bonding materials.

[0020] 2. The high-performance sheet metal bonding foaming material has excellent weather resistance. By reasonably selecting the main resin, toughening agent and fillers, the material can maintain stable bonding performance at a high temperature of 250 °C and a low temperature of 5 °C, meeting the use requirements in different harsh environments.

[0021] 3. This high-performance sheet metal bonding and foaming material has good process adaptability. The curing time of the material can be controlled by adjusting the dosage and type of the curing agent. In industrial production, the complete curing time can be controlled between 3 and 12 hours according to the actual process requirements, which is convenient for operation and improves production efficiency. Detailed implementation mode

[0022] The technical solutions in 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 a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0023] Embodiment 1:

[0024] The present invention provides a technical solution: a high-performance sheet metal bonding and foaming material, and the material formula is as follows:

[0025] Main resin: Bisphenol A epoxy resin is selected, and its epoxy value is 0.25 - 0.45, accounting for 65wt% in the formula. This bisphenol A epoxy resin has good adhesion and mechanical properties, providing the basic bonding ability and strength support for the material.

[0026] Foaming agent: A chemical foaming agent is used, with a decomposition temperature of 195 - 205 degrees Celsius, accounting for 4wt%. This foaming agent decomposes to generate gas during the curing process of the material, promoting the formation of a uniform cell structure in the material.

[0027] Curing agent: The curing agent, with a dosage of 18wt% of the mass of bisphenol A epoxy resin. It matches well with bisphenol A epoxy resin to ensure that the material is completely cured within an appropriate time and forms a stable cross-linked structure.

[0028] Toughening agent: The toughening agent accounts for 6wt%, which can effectively improve the brittleness of the material, enhance the impact resistance of the material, and improve the reliability of the material in actual use.

[0029] Filler: Nano-silica is selected as the filler, accounting for 7wt%. The addition of nano-silica can improve the hardness, wear resistance and dimensional stability of the material, and at the same time reduce the material cost.

[0030] The preparation process is as follows:

[0031] S1. Premixing: Add the main resin, toughening agent, and 3.5 wt% of nano-silica into a high-speed mixer. Set the temperature at 80 °C and stir at a speed of 1500 r / min for 30 min. During this process, the shear force generated by high-speed stirring enables the toughening agent and nano-silica to be fully dispersed in bisphenol A epoxy resin, forming a uniform premix, which lays the foundation for subsequent reactions;

[0032] S2. Mixing of foaming agent and curing agent: Mix the foaming agent and curing agent separately with the remaining 3.5 wt% of nano-silica in a low-speed mixer. Low-speed stirring can avoid premature decomposition of the foaming agent and premature contact between the curing agent and bisphenol A epoxy resin, ensuring that the foaming agent and curing agent are evenly dispersed in the filler.

[0033] S3. Final mixing: Put the premix and the nano-silica containing the foaming agent and curing agent into a vacuum kneader for mixing, maintaining a vacuum degree of -0.09 MPa and a kneading time of 60 min. The vacuum environment can remove air and moisture in the material system, preventing the generation of bubbles and defects; during the kneading process, the strong shear force and pressure promote the full mixing and reaction of each component, enabling the material to form a uniform and stable structure.

[0034] Perform performance testing on the prepared material, and the steps are as follows:

[0035] Adhesive strength test: Conduct the test according to the ASTM D1002 standard, using the shear strength test method. Use this material to bond a standard sheet metal sample, and the test results show that its shear strength reaches 86 MPa, and the adhesive strength is significantly improved compared with ordinary adhesive materials.

[0036] Weather resistance test: Place the bonded sheet metal parts in an environment of 80 °C and 90% humidity for 1000 h, and in a low-temperature environment of -40 °C for 500 h respectively. After testing, after the high-temperature and high-humidity environment, the retention rate of the material's adhesive strength is 92%; after the low-temperature environment, the retention rate of the adhesive strength is 91%, showing excellent weather resistance.

[0037] Curing time test: Under standard process conditions, determine the curing time of the material to be 30 min by real-time monitoring of the curing state of the material, which meets the requirements of industrial production for efficiency.

[0038] Example 2

[0039] The present invention provides a technical solution: a high-performance sheet metal bonding foaming material, and the material formula is as follows:

[0040] Matrix resin: Bisphenol A epoxy resin accounts for 60 wt%, and its epoxy value is still within 0.25 - 0.40 to ensure basic properties; Blowing agent: Chemical blowing agent accounts for 3 wt%, and the amount of blowing agent is adjusted according to different requirements; Curing agent: The dosage of the curing agent is 15 wt% of the mass of the epoxy resin. By changing the proportion of the curing agent, the curing speed and properties of the material are adjusted; Toughness agent: The toughness agent accounts for 5 wt%; Filler: Nano-silica accounts for 10 wt%. The addition of nano-silica can optimize the processing performance and hardness of the material.

[0041] The preparation process is as follows:

[0042] S1. Premixing: Add the matrix resin, toughness agent, and 5 wt% nano-calcium carbonate to a high-speed mixer. Set the temperature to 75 °C and stir at a speed of 1200 r / min for 25 min.

[0043] S2. Mixing of blowing agent and curing agent: Mix the blowing agent and curing agent separately with the remaining 5 wt% nano-calcium carbonate in a low-speed mixer.

[0044] S3. Final mixing: Mix the premix with nano-silica containing the blowing agent and curing agent in a vacuum kneader. Maintain the vacuum degree at -0.086 MPa and the kneading time at 50 min.

[0045] The performance tests are as follows:

[0046] Adhesive strength test: The test is carried out according to the ASTM D1002 standard. Using the shear strength test method, apply this material to bond standard sheet metal part samples. The test results show that its shear strength reaches 83 MPa. Compared with ordinary adhesive materials, the adhesive strength is significantly improved.

[0047] Weather resistance test: Place the bonded sheet metal parts in an environment of 75 °C high temperature and 85% humidity for 800 h, and in an environment of -35 °C low temperature for 400 h. After the test, the retention rate of the adhesive strength in the high-temperature and high-humidity environment is 89%, and the retention rate in the low-temperature environment is 88%. It still has good weather resistance.

[0048] Curing time test: Under standard process conditions, the curing time of the material is 40 min. By adjusting the dosage of the curing agent, the effective control of the curing time is achieved, meeting the requirements of different production processes.

[0049] The present invention has the advantage of high bonding strength. During the curing process, the material foams and expands, and the foam structure increases the contact area with the sheet metal parts. At the same time, the cross-linked structure formed by the main resin and the curing agent provides strong adhesion, significantly improving the bonding strength between the material and the sheet metal parts. After testing, its shear strength is 12% higher than that of ordinary bonding materials. At the same time, it has excellent weather resistance. By reasonably selecting the main resin, toughening agent and filler, the material can maintain stable bonding performance at high temperatures of 250 degrees Celsius and low temperatures of 5 degrees Celsius, meeting the usage requirements in different harsh environments.

[0050] The above has generally described the present invention in detail. However, based on the present invention, some modifications or improvements can be made, which are obvious to those of ordinary skill in the technical field. Therefore, modifications or improvements made without departing from the spirit of the present invention are within the protection scope of the present invention.

Claims

1. A high-performance sheet metal bonding and foaming material, characterized in that, By weight percentage, it includes the following components: 60 - 70 wt% of bisphenol A epoxy resin, 3 - 5 wt% of chemical foaming agent, 15 - 20 wt% of curing agent, 5 - 8 wt% of toughening agent, 10 - 15 wt% of nano-silica filler; the epoxy value of the bisphenol A epoxy resin is 0.25 - 0.45, and the decomposition temperature of the chemical foaming agent is 195 - 205 °C.

2. The high-performance sheet metal bonding and foaming material according to claim 1, wherein The nano-level filler is one or a mixture of two of nano-silica and nano-calcium carbonate.

3. The high-performance sheet metal bonding and foaming material according to claim 1, wherein The composition of the toughening agent by weight parts is: 59.6 - 60.2 parts of polyolefin elastomer POE; 30 - 50 of thermoplastic polyurethane; 9.2 - 10 parts of expanded polystyrene EPS.

4. A high-performance sheet metal bonding and foaming material according to claim 1, characterized in that The composition of the curing agent by weight parts is: 5 - 15 parts of alicyclic amine curing agent, 28 - 85 parts of polyetheramine curing agent, 10 - 80 parts of curing accelerator, 1 - 3.5 parts of adhesion promoter.

5. A method for preparing a high-performance sheet metal bonding and foaming material according to any one of claims 1-4, characterized in that, It includes the following steps: S1. Add the main resin, toughening agent and part of the filler into a high-speed mixer, and stir at 25 - 100 °C and a stirring speed of 500 - 1800 r / min for 20 - 55 min to obtain a premix; S2. Mix the foaming agent and the curing agent with the remaining filler respectively in a low-speed mixer; S3. Mix the premix with the filler containing the foaming agent and the curing agent in a vacuum kneader, keep the vacuum degree at -0.085~-0.098 MPa, and the kneading time is 30 - 90 min to obtain a high-performance sheet metal bonding foaming material.

6. The preparation method of a high-performance sheet metal bonding and foaming material according to claim 5, characterized in that, The part of the filler accounts for 50% of the total amount of the filler.

7. A method for preparing a high-performance sheet metal bonding and foaming material according to claim 5, characterized in that, The vacuum degree of the vacuum kneader is -0.09 MPa, and the kneading time is 60 min.

8. Application of the high-performance sheet metal bonding foaming material according to any one of claims 1 - 4 in the field of sheet metal bonding.

9. The application according to claim 8, wherein The high-performance sheet metal bonding foaming material foams and expands during the curing process, fills the gap between sheet metal parts, and forms a firm bond.

10. The application according to claim 8, wherein The high-performance sheet metal bonding foaming material maintains stable bonding performance in an environment with a temperature range of -40 °C - 80 °C and a humidity not higher than 90%.