Preparation method of high-temperature-resistant flame-retardant polyimide sealing compound with good heat dissipation performance

Abstract

The invention relates to a preparation method of a high-temperature-resistant flame-retardant heat-dissipation polyimide sealant, which comprises the following steps: 1) stirring a crown ether diamine monomer at normal temperature for 24 hours under the protection of nitrogen to obtain a polyamide acid solution; (2) adding a dehydrating agent and a catalyst for chemical imidization to obtain a polyimide solution; (3) pouring the solution into a constant-pressure funnel, so that the solution is slowly separated out in absolute ethyl alcohol to form polyimide powder, and drying the polyimide powder; 4) dissolving soluble polyimide powder in the DMAC solution to obtain a polyimide solution; and 5) carrying out vacuum defoaming on the polyimide solution, pouring into a mold, and heating and curing to obtain the sealing compound. The invention has the following advantages: the phenyl ether type polyimide has good thermal stability, the molecular structure is changed due to ether bond breakage at high temperature, so that the performance and stability of the material are influenced, and the selected diamine and dianhydride reduce the content of ether bonds and improve the thermal stability under the condition of ensuring good high temperature resistance and flame retardant property.

Description

Technical Field

[0001] The invention relates to the technical field of nanofiber sealing adhesive, in particular to a method for preparing a polyimide sealing adhesive with good high temperature resistance, flame retardancy and heat dissipation performance. Background Art

[0002] Sealant can be used to seal, fill gaps in structures, and prevent the entry or loss of liquids, gases, sounds, heat, etc. It is widely used in construction, electronic instruments and parts. Polyimide sealant has the characteristics of high temperature resistance and thermal stability. When the connection part or the entire object is damaged by high temperature, fire, etc., it is protected, extending the service life of the object and maintaining its performance. The performance advantages of polyimide sealant over other organic sealants are mainly reflected in: good thermal stability, high temperature resistance, flame retardant properties, etc. Therefore, the research and preparation of polyimide sealant with strong thermal stability has great practical significance. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for preparing a polyimide sealant with good high temperature resistance, flame retardancy and heat dissipation performance. Through large-scale instrument characterization, we found that it is not only resistant to high temperatures, but also has good thermal stability. Therefore, we hope that the prepared polyimide sealant will be used in the protection of electronic components and in construction. The present invention is expected to be widely used in the sealing of construction, transportation, electronic instruments and high temperature resistant circulation parts.

[0004] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance, comprising the following steps:

[0005] Adding a plurality of crown ether diamine monomers to the dianhydride monomer respectively, stirring at room temperature for 24 hours under nitrogen protection, to obtain a polyamic acid solution;

[0006] Then, a dehydrating agent and a catalyst are added to carry out chemical imidization to obtain a polyimide solution;

[0007] Pour the above solution into a constant pressure funnel, and allow the solution to slowly precipitate in anhydrous ethanol to form polyimide powder, which is then dried;

[0008] Dissolving soluble polyimide powder in one or more solutions of DMAC / DMF / DMSO / NMP to obtain a polyimide solution;

[0009] The polyimide solution is vacuum degassed and poured into a mold, and heated to cure; or the polyimide solution is poured onto a desired device and air-dried to obtain a polyimide sealing film;

[0010] Furthermore, the air drying here can be carried out at room temperature or by heating, and the performance of the film is mainly due to its high heat resistance, that is, high degree of thermal decomposition;

[0011] In addition, its glass transition temperature, that is, its melting point, is relatively low, and this characteristic can be used for sealing.

[0012] The generated polyimide sealing film was subjected to a thermogravimetric test using a comprehensive thermal analyzer to obtain a TGA thermogravimetric curve.

[0013] Preferably, the diamine monomer is one or more of the following compounds: 6FODA, 6FAPB, 6FAPE.

[0014] Preferably, the dianhydride monomer is ODPA;

[0015] The dehydrating agent is acetic anhydride;

[0016] The catalyst is pyridine.

[0017] Preferably, in the step of obtaining the polyamic acid solution, the mass ratio of the diamine monomer to the dianhydride monomer is 1:1 to 1:1.5.

[0018] Preferably, in the step of obtaining the polyimide solution, the mass ratio of the polyamic acid solution, the dehydrating agent, and the catalyst is 1:(5-11):(2.5-5).

[0019] Beneficial Effects

[0020] The invention provides a method for preparing a polyimide sealant with good high temperature resistance, flame retardancy and heat dissipation performance. The invention has the following beneficial effects: the method for preparing a polyimide sealant with good high temperature resistance, flame retardancy and heat dissipation performance, the phenylene ether type polyimide has good thermal stability, at high temperature, the rupture of the ether bond will cause the molecular structure to change, thereby affecting the performance and stability of the material, and the selected diamine and dianhydride reduce the content of the ether bond and improve the thermal stability under the condition of ensuring high temperature resistance and good flame retardancy. At the same time, the introduction of crown ether diamine molecules can copolymerize with other monomers to form a cross-linked structure, thereby enhancing the mechanical properties and heat resistance of the polyimide sealant. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the TGA data of polyimide film.

[0022] Figure 2 DMA data for polyimide film. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] All electrical components in this case are connected to their corresponding power supplies through wires by personnel in this field, and a suitable controller should be selected according to actual conditions to meet control requirements. The specific connection and control sequence should refer to the working sequence between the electrical components in the following working principle to complete the electrical connection. The detailed connection means are well-known technologies in this field. The following mainly introduces the working principle and process, and no longer explains the electrical control.

[0025] See also Figure 1-2 , the present invention provides a technical solution:

[0026] Example 1

[0027] A method for preparing a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance, the specific steps are as follows:

[0028] 1. Add 10 g of crown ether diamine monomer 6FODA to 12 g of dianhydride monomer ODPA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0029] 2. Add 8 grams of acetic anhydride and 3 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0030] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 500 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0031] 4. Dissolve the above polyimide powder in 200 ml of DMAC solution to obtain a polyimide solution.

[0032] 5. Pour the polyimide solution evenly on a pre-cleaned copper plate and heat-cure it at a temperature of 150°C for 2 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0033] Example 2

[0034] 1. Add 15 g of crown ether diamine monomer 6FODA to 20 g of dianhydride monomer BPADA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0035] 2. Add 10 grams of acetic anhydride and 4 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0036] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 700 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0037] 4. Dissolve the above polyimide powder in 300 ml of DMAC solution to obtain a polyimide solution.

[0038] 5. Pour the polyimide solution evenly on a pre-cleaned copper plate and heat-cure it at a curing temperature of 160°C for 3 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0039] Example 3

[0040] 1. Add 12 g of crown ether diamine monomer 6FAPB to 14 g of dianhydride monomer ODPA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0041] 2. Add 9 grams of acetic anhydride and 3.5 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0042] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 600 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0043] 4. Dissolve the above polyimide powder in 250 ml of DMAC solution to obtain a polyimide solution.

[0044] 5. Pour the polyimide solution evenly on a pre-cleaned copper plate and heat-cure it at a curing temperature of 155°C for 2.5 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0045] Example 4

[0046] 1. Add 18 g of crown ether diamine monomer 6FAPB to 22 g of dianhydride monomer BPADA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0047] 2. Add 11 grams of acetic anhydride and 4.5 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0048] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 800 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0049] 4. Dissolve the above polyimide powder in 350 ml of DMAC solution to obtain a polyimide solution.

[0050] 5. Pour the polyimide solution evenly onto a pre-cleaned copper plate and heat-cure it at a temperature of 165°C for 3.5 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0051] Example 5

[0052] 1. Add 10 g of crown ether diamine monomer 6FAPE to 12 g of dianhydride monomer ODPA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0053] 2. Add 8 grams of acetic anhydride and 3 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0054] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 500 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0055] 4. Dissolve the above polyimide powder in 200 ml of DMAC solution to obtain a polyimide solution.

[0056] 5. Pour the polyimide solution evenly on a pre-cleaned copper plate (or other material that needs to be filled with sealant), heat and cure it at a temperature of 150°C for 2 hours to obtain a polyimide sealant with good high temperature resistance, flame retardancy and heat dissipation performance.

[0057] Example 6

[0058] 1. Add 15 g of crown ether diamine monomer 6FAPE to 20 g of dianhydride monomer BPADA, and stir at room temperature for 24 hours under nitrogen protection to obtain a polyamic acid solution.

[0059] 2. Add 10 grams of acetic anhydride and 4 grams of pyridine to the above solution to carry out chemical imidization reaction to obtain a polyimide solution.

[0060] 3. Pour the above solution into a constant pressure funnel and allow the solution to slowly precipitate in 700 ml of anhydrous ethanol to form polyimide powder which is then dried.

[0061] 4. Dissolve the above polyimide powder in 300 ml of DMAC solution to obtain a polyimide solution.

[0062] 5. Pour the polyimide solution evenly on a pre-cleaned copper plate and heat-cure it at a curing temperature of 160°C for 3 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0063] As shown in Table 1, TD5% is the temperature at which the weight loss is 5% during the heating process, and TD10% is the temperature at which the heat loss is 10%;

[0064] RW800, the ratio of the weight of the residue after heating to 840 degrees to the weight before heating can be found in the table below. Figure 1 TGA curve of .

[0065] Table 1 TGA data of polyimide film

[0066]

[0067] Table 2 DMA data of polyimide film

[0068]

[0069] Example 7

[0070] On the basis of the above example, silane (PDMS) is added to introduce siloxane segments into the PI film. The flexible and small siloxane segments are easily enriched on the surface of the PI film, which significantly increases the contact area between the PI film and other substrates. The siloxane segments are more likely to penetrate into other substrates to form mechanical interlocking, thereby improving the bonding strength between the PI film and the substrate. The ratio is as follows:

[0071] Table 3 Experimental formula of polyimide

[0072]

[0073]

[0074] a The molar ratio of PDMS to the total diamine content in the PI film;

[0075] Pour the PDMS-polyimide solution evenly on a pre-cleaned copper plate (or other material that needs to be filled with sealant), heat and cure it at a temperature of 160°C for 3 hours to obtain a polyimide sealant with high temperature resistance, flame retardancy and good heat dissipation performance.

[0076] 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. In the absence of further restrictions. The sentence "includes an element defined by ... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0077] Although embodiments of the present invention 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 invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance, characterized in that: The following steps are involved: Adding a plurality of crown ether diamine monomers to the dianhydride monomer respectively, stirring at room temperature for 24 hours under nitrogen protection, to obtain a polyamic acid solution; Then, a dehydrating agent and a catalyst are added to carry out chemical imidization to obtain a polyimide solution; Pour the above solution into a constant pressure funnel, and allow the solution to slowly precipitate in anhydrous ethanol to form polyimide powder, which is then dried; dissolving soluble polyimide powder in DMAC solution to obtain a polyimide solution; After vacuum degassing, the polyimide solution is poured into a mold and heated to solidify; or the polyimide solution is poured onto the desired device; or TPI powder is directly used, and its low glass transition temperature and high thermal stability are utilized, and it is directly heated into a fluid form and filled in the desired position; Air-drying to obtain a polyimide sealing film; The generated polyimide sealing film was subjected to a thermogravimetric test using a comprehensive thermal analyzer to obtain a TGA thermogravimetric curve.

2. The method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance according to claim 1, characterized in that , the diamine monomer is one or more of the following compounds:

3. The method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance according to claim 1, characterized in that , the dianhydride monomer is one or more of the following compounds: The dehydrating agent is acetic anhydride; The catalyst is pyridine.

4. The method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance according to claim 1, characterized in that In the step of obtaining the polyamic acid solution, the mass ratio of the diamine monomer to the dianhydride monomer is 1:1 to 1:1.

5.

5. The method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance according to claim 1, characterized in that In the step of obtaining the polyimide solution, the mass ratio of the polyamic acid solution, the dehydrating agent, and the catalyst is 1:(5-11):(2.5-5).

6. The method for preparing a polyimide sealant having high temperature resistance, flame retardancy and good heat dissipation performance according to claim 1, characterized in that In the step of obtaining the polyimide solution, one or more of ceramic particles, metal oxide particles and silane-based inert fillers are added or not added; The addition ratio is 1% to 10% of the diamine monomer.

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