Self-filling thermosetting structural adhesive film and preparation method thereof

Abstract

The invention discloses a self-filling thermosetting structure adhesive film which is characterized in that the self-filling thermosetting structure adhesive film is formed by compounding an adhesive material, low-temperature expansion microspheres, organic urea and a curing agent, the adhesive material is composed of epoxy resin and carboxylated nitrile rubber, and the specific preparation process comprises the steps that S1, the epoxy resin and the carboxylated nitrile rubber are kneaded into the uniform adhesive material at low temperature; s2, kneading a curing agent, low-temperature expansion microspheres, organic urea and the sizing material obtained in the S1 at low temperature until the materials are uniformly dispersed; and S3, returning the temperature of the rubber block in the S2 to room temperature, calendering the rubber block with the release paper to a thickness required by a customer through a roller type pressing machine, and rolling the rubber block. The self-filling structural adhesive film disclosed by the invention has the interlayer bonding capacity of an uneven surface, and has self-adaptive filling on uneven and non-uniform interlayer gaps.

Description

Technical Field

[0001] This invention relates to the field of structural adhesive film technology, and in particular to a self-filling thermosetting structural adhesive film and its preparation method. Background Technology

[0002] Adhesives are generally classified into structural adhesives and non-structural adhesives. The most significant characteristic of structural components made with structural adhesives is their lightweight and high strength. Furthermore, bonded structures possess special properties such as crack resistance, wave absorption, vibration damping, heat insulation, and sound insulation, thus enjoying widespread application. Currently, structural adhesives and bonding technologies are used in various structures and fields, and the usage of adhesives is increasing significantly. Structural adhesives have become an important material in industrial production.

[0003] Existing structural adhesive membrane products have poor flowability, making it difficult to spread evenly or fill gaps during construction. Multiple coats or pressure applications are required to achieve uniform thickness, increasing labor costs and leading to low efficiency. Furthermore, their ability to compensate for gaps is weak, requiring the sacrifice of adhesive layer thickness to fill interlayer gaps; or it is necessary to increase the membrane thickness and fill gaps through adhesive overflow. Summary of the Invention

[0004] To address the issues of poor flowability and weak breaking capacity in structural adhesive films, this invention provides a self-filled thermosetting structural adhesive film and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a self-filled thermosetting structural adhesive film composed of an adhesive compound, low-temperature expanding microspheres, organic urea and a curing agent, wherein the adhesive compound is composed of epoxy resin and carboxylated nitrile rubber.

[0006] In one embodiment, the raw material ratio is as follows: 120-200 parts epoxy resin, 20-60 parts carboxylated nitrile rubber, 2-30 parts low-temperature expansion microspheres, 1-10 parts organic urea, and 5-50 parts curing agent.

[0007] A second aspect of the present invention provides a method for preparing a self-filling thermosetting structural adhesive film, comprising the following steps: S1. Epoxy resin and carboxylated nitrile rubber are kneaded at low temperature to form a homogeneous rubber compound; S2. Knead the curing agent, low-temperature expanding microspheres and organic urea with the adhesive obtained in S1 at low temperature until they are evenly dispersed; S3. Warm the S2 adhesive block to room temperature, then use a roller press to calculate the release paper to the thickness required by the customer and rewind it.

[0008] In one embodiment, the carboxylated nitrile rubber is a copolymer of butadiene, acrylonitrile and organic acid, with an acrylonitrile content of 27% and a Mooney viscosity of 34 (ML1+4@100℃).

[0009] In one embodiment, the low-temperature kneading is performed by controlling the temperature below 50°C.

[0010] In one embodiment, the thickness of the adhesive film is 0.2~2mm.

[0011] The above technical solution has the following beneficial effects: This invention creates a self-filling structural adhesive film. This adhesive film product is suitable for flat surfaces, has interlayer bonding capability for non-flat surfaces, and has an adaptive filling effect for non-flat and non-uniform interlayer gaps. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the internal structure of the present invention. Detailed Implementation

[0013] To illustrate the technical content, structural features, objectives, and effects of the technical solution in detail, the following description is provided in conjunction with specific embodiments and accompanying drawings. Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased from conventional products on the market.

[0014] Example 1 A method for preparing a self-filling thermosetting structural adhesive film, comprising the following steps: S1. Mix 100 parts of E51 epoxy resin, 30 parts of E20 epoxy resin and 40 parts of carboxylated nitrile rubber 1072CG at low temperature to form a homogeneous rubber compound. S2. Mix 12 parts of curing agent dicyandiamide, 16 parts of low-temperature expanding microspheres and 4 parts of organic urea with S1 adhesive at low temperature (temperature controlled below 50℃) until evenly dispersed; S3. Warm the S2 adhesive block to room temperature, then use a roller press to calculate the release paper to a thickness of 0.2mm and roll it up.

[0015] As the temperature increases, the viscosity of the adhesive film decreases rapidly. The expanding particles in the adhesive film begin to expand at 80°C, propelling the adhesive to flow between gaps and automatically filling gaps and discontinuities. At temperatures of 60°C to 95°C, the adhesive slowly cures, and its viscosity increases slowly. At 100°C to 130°C, the adhesive enters a rapid curing phase, with its viscosity increasing rapidly and losing its fluidity, thus completing the bonding process. (Organic urea begins to decompose slowly at 60°C and reaches its fastest rate at 120°C, producing dimethylamine. Dimethylamine reacts with epoxy groups to form tertiary amines, which catalyze the curing of epoxy with dicyandiamide.)

[0016] As shown in Table 1, the performance indicators of the self-filling thermosetting structural adhesive film of Example 1 are as follows: Example 2 A method for preparing a self-filling thermosetting structural adhesive film, comprising the following steps: S1. 75 parts of E51 epoxy resin, 50 parts of E20 epoxy resin and 30 parts of carboxylated nitrile rubber 1072CG are kneaded at low temperature to form a homogeneous rubber compound. S2. Mix 11 parts of dicyandiamide, 25 parts of low-temperature expanded microspheres and 2 parts of organic urea with S1 rubber compound at low temperature (temperature controlled below 50℃) until evenly dispersed; S3. Warm the S2 adhesive block to room temperature, then use a roller press to calculate the release paper to a thickness of 5mm and roll it up.

[0017] As shown in Table 2, the performance indicators of the self-filling thermosetting structural adhesive film of Example 2 are as follows: Example 3 A method for preparing a self-filling thermosetting structural adhesive film, comprising the following steps: S1. Mix 150 parts of E51 epoxy resin, 20 parts of E20 epoxy resin and 50 parts of carboxylated nitrile rubber 1072CG at low temperature to form a homogeneous rubber compound. S2. Mix 17 parts of dicyandiamide, 4 parts of low-temperature expanded microspheres and 8 parts of organic urea with S1 rubber compound at low temperature (temperature controlled below 50℃) until evenly dispersed; S3. Warm the S2 adhesive block to room temperature, then use a roller press to calculate the release paper to a thickness of 3mm and roll it up.

[0018] As shown in Table 3, the performance indicators of the self-filling thermosetting structural adhesive film of Example 3 are as follows: Comparative Example 1 The difference from Example 1 is that the organic urea is replaced with 2-ethyl-4-methylimidazole, while everything else remains the same.

[0019] Comparative Example 2 The difference from Example 1 is that the organic urea is replaced with dimethylimidazole, while everything else remains the same.

[0020] Test case The shear strength of the adhesive film under different curing temperatures was tested using the schemes of Example 1 and Comparative Example 1.2. The results are shown in Table 4. Curing conditions Example 1 Comparative Example 1 Comparative Example 2 130℃ for 30 minutes 27.5 MPa 23.92 MPa 21.15 MPa 115℃ for 30 minutes 25.11 MPa 22.98 MPa 20.95 MPa 110℃ for 30 minutes 24.1 MPa 22.6 MPa 20.32 MPa 100℃ for 30 minutes 20.1 MPa 21.6 MPa 20.5 MPa 90℃ for 30 minutes 1.76 MPa 12.32 MPa 8.82 MPa The storage properties of the films under different storage conditions were tested using the schemes of Example 1 and Comparative Example 1.2, and the results are shown in Table 5: If the film is stored at this temperature, the gelation rate will be greater than 50%, the film will have no surface adhesion, and it will lose its usability.

[0021] Storage conditions Organic urea regimen Option 2 (Liquid Imidazole) Option 3 (Solid Imidazole) -18℃ >180 days >180 days >180 days -5~5℃ >180 days <60 days <90 days 23℃ >90 days <7 days <15 days As shown in Table 4.5, the adhesive film obtained by this application has good room temperature storage properties, slow reaction at medium and low temperatures, and rapid reaction at high temperatures. Compared with ordinary epoxy products, which can only be cured quickly at low temperatures or require high temperature of 180°C and cannot be stored at room temperature and can only reduce activity at sub-zero temperatures, this application has obvious advantages.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of additional elements in the process, method, article, or terminal device that includes said element. Additionally, in this document, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number.

[0023] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A self-filling thermosetting structural adhesive film, characterized in that, It is composed of a compound of rubber, low-temperature expanding microspheres, organic urea and curing agent, wherein the rubber is composed of epoxy resin and carboxylated nitrile rubber.

2. The self-filling thermosetting structural adhesive film as described in claim 1, wherein the raw material ratio is: 120-200 parts epoxy resin, 20-60 parts carboxylated nitrile rubber, 2-30 parts low-temperature expansion microspheres, 1-10 parts organic urea, and 5-50 parts curing agent.

3. The method for preparing a self-filling thermosetting structural adhesive film as described in claim 1 or 2, characterized in that, The steps are as follows: S1. Epoxy resin and carboxylated nitrile rubber are kneaded at low temperature to form a homogeneous rubber compound; S2. Knead the curing agent, low-temperature expanding microspheres and organic urea with the adhesive obtained in S1 at low temperature until they are evenly dispersed; S3. Warm the S2 adhesive block to room temperature, then use a roller press to calculate the release paper to the thickness required by the customer and rewind it.

4. The preparation method according to claim 2, characterized in that, The carboxylated nitrile rubber is a copolymer of butadiene, acrylonitrile and organic acid, with an acrylonitrile content of 27% and a Mooney viscosity of 34 (ML1+4@100℃).

5. The preparation method according to claim 2, characterized in that, The low-temperature kneading process involves controlling the temperature below 50°C.

6. The preparation method according to claim 2, characterized in that, The thickness of the adhesive film is 0.2~2mm.

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