Preparation of lipoic acid modified epoxy resin-based sealant and circuit board sealing and unsealing process method of lipoic acid modified epoxy resin-based sealant

Abstract

The invention belongs to the technical field of electronic sealants, and relates to preparation of a lipoic acid modified epoxy resin-based sealant and a circuit board sealing and unsealing process method thereof. The preparation method comprises the following steps: mixing epoxidized soybean oil and a lipoic acid monomer, stirring and reacting at 50-90 DEG C for 20-40 minutes to prepare a precursor, pouring the precursor into a mold, and curing at 50 DEG C for 8 hours to obtain the sealant. And sealing the circuit board by using the precursor, keeping at 50 DEG C for 8 hours, and finally soaking the sealed circuit board in absolute ethyl alcohol at 50 DEG C for 72 hours to realize unsealing. The method adopts a solvent-free method, and is simple in process, low in cost and environment-friendly. The prepared sealant can adhere to various base materials, is stable in air and underwater and has excellent transparency, weather resistance and detachability, a new thought is provided for design and preparation of the bio-based electronic sealant, and meanwhile, the epoxidized soybean oil can be replaced to construct various functional sealants.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic sealants, and particularly to the preparation of a lipoic acid-modified epoxy resin-based sealant and its circuit board sealing and unsealing process methods. Background Art

[0002] Electronic sealants can achieve dust and water protection for electronic devices, extending the device performance and service life. Compared with traditional bonding materials, electronic sealants need to possess more stringent comprehensive properties. To achieve tough and stable waterproof bonding for long-term use, have transparency for convenient observation of the device working state, have strong mechanical strength to resist external impacts, and also need to be detachable under mild conditions to reduce electronic waste and energy consumption. Therefore, developing a long-term stable, transparent, waterproof, and detachable electronic sealant is particularly urgent and important for accelerating the popularization and promotion of electronic sealants.

[0003] Patent CN202211110141 discloses a transparent polyurethane electronic sealant and its preparation method, which is prepared by compounding various raw materials such as isocyanates and polyols through specific reaction conditions, ensuring the transparency, adhesiveness, stability, and weather resistance of the sealant, but its performance in aspects such as waterproofness and detachability obviously needs to be improved.

[0004] Lipoic acid (TA) is a natural small molecule, which is rich in microorganisms, protozoa, plants and animals, and contains two characteristic functional groups, carboxyl and dithiolane. The carboxyl group can not only condense with functional groups such as hydroxyl, amino, and epoxy groups to form chemical bonds, but also have physical interactions such as hydrogen bonding and metal complexation with corresponding molecules. The dithiolane can form polymers through ring-opening polymerization and depolymerize into monomers by ring-closing, and has hydrophobicity, which can improve the water resistance of substances. After investigation, the existing related work using lipoic acid has not achieved the sealing of electronic circuits.

[0005] Epoxidized soybean oil (ESO), as a highly regarded chemical material, its raw material soybean oil is one of the most widely sourced renewable organic substances, and it has currently been applied in the field of plasticizing polymers on a large scale and at low cost. Soybean oil is mainly composed of various fatty acid esters mainly triglycerides. The presence of a large number of carbon-carbon double bonds and ester groups in the molecule endows it with certain unsaturation and polarity, and also makes soybean oil have good fluidity and certain chemical activity. Epoxidized soybean oil is exactly the product of the epoxidation of the unsaturated double bonds of soybean oil. With outstanding characteristics such as being renewable, low-cost, safe, and environmentally friendly, it has increasingly attracted the attention of scientific researchers in the preparation of sealants and is expected to play a greater role in related fields. Therefore, epoxidized soybean oil has great potential in the field of high-strength sealing materials. Summary of the Invention

[0006] Objective of the Invention: To address the issue that existing electronic sealants are difficult to simultaneously meet the requirements of high strength, high transparency, water resistance stability, and detachable under mild conditions, which restricts the popularization and application of electronic sealants. The objective of the present invention is to provide a preparation method of lipoic acid-modified epoxy resin-based sealant and a circuit board sealing and unsealing process method, providing new ideas for the popularization of electronic sealants.

[0007] Technical Solution: A preparation method of lipoic acid-modified epoxy resin-based sealant and a circuit board sealing and unsealing process method, characterized in that the steps and conditions are as follows: (1) Mix two monomers of epoxidized soybean oil and lipoic acid, and carry out the reaction under stirring conditions. The reaction temperature is 50 - 90 °C, and the reaction time is 20 - 40 minutes to obtain a lipoic acid-modified epoxy resin-based sealant precursor. In this precursor, the mass concentration of epoxidized soybean oil monomer is 20 - 60 g / L, and the mass concentration of lipoic acid monomer is 50 - 90 g / L; (2) Pour the above lipoic acid-modified epoxy resin-based sealant precursor into a mold, seal the reaction mold, and place it in an oven at 50 °C for curing for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board, and place it in an oven at 50 °C for 8 hours to obtain a well-sealed circuit board. Immerse the sealed circuit board in absolute ethanol and place it in an oven at 50 °C for 72 hours to obtain a circuit board after unsealing.

[0008] Innovation Point: Through the formation of ester bonds by the carboxyl group of lipoic acid and the epoxy ring opening of epoxidized soybean oil, as well as the disulfide bonds formed by lipoic acid itself, the sealant has excellent weather resistance. At the same time, the sealant can be broken in absolute ethanol at a certain temperature, endowing the sealant with detachable performance. The dense covalent cross-linked network of the polymer and the hydroxyl groups on the main chain endow this adhesive with high interfacial adhesion strength and excellent water resistance stability. At the same time, the materials we used are bio-based raw materials, providing new insights for promoting the development and application of sustainable and recyclable electronic sealant materials. Beneficial Effects

[0009] The present invention prepares a lipoic acid-modified epoxy resin-based sealant. This preparation method adopts a solvent-free method, which has the characteristics of simple process, convenient operation, low cost, and environmental friendliness; The lipoic acid-modified epoxy resin-based sealant prepared by the present invention and the circuit board sealing and unsealing process method achieve adhesion with a variety of substrates, including: metals, plastics, glasses, woods, etc.; being stable in air and underwater for a long time; having excellent transparency, freeze-thaw cycle resistance, damp-heat cycle resistance, high and low temperature resistance. Compared with traditional electronic sealants, it can be disassembled under mild conditions; The preparation method of a lipoic acid modified epoxy resin based sealant and the circuit board sealing and unsealing process prepared by the present invention provide a new idea and method for the design and preparation of bio-based electronic sealants. The epoxy soybean oil therein can be replaced with other epoxy raw materials to realize the construction of sealants with various functions. This method for preparing sealants can also be extended to other material design systems. Brief Description of the Drawings

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art; Figure 1 XRD patterns of epoxy soybean oil (ESO), lipoic acid (TA), and the lipoic acid modified epoxy resin based sealant PTAE prepared in accordance with Claim 1; Figure 2 FT-IR spectra of epoxy soybean oil (ESO), lipoic acid (TA), and the lipoic acid modified epoxy resin based sealant PTAE prepared in accordance with Claim 1; Figure 3 Illustration of the underwater sealing application of the sealed circuit board (underwater sealing operation for 144 hours); Figure 4 Illustration of the circuit board before and after sealing and unsealing.

Claims

1. A preparation method of lipoic acid modified epoxy resin based sealant and circuit board sealing and desealing process, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxy soybean oil and thioctic acid, and reacting them under stirring conditions at a temperature of 50 to 90° C. for 20 to 40 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxy soybean oil monomer is 20 to 60 g / L, and the mass concentration of the thioctic acid monomer is 50 to 90 g / L; (2) pouring the above-mentioned lipoic acid modified epoxy resin-based sealant precursor into a mold containing a circuit board, sealing the reaction mold and curing it in an oven at 50 to 80° C. for 6 to 8 hours, and finally obtaining a circuit board with good sealing of the lipoic acid modified epoxy resin-based sealant; (3) Soak the sealed circuit board in anhydrous ethanol and place it in an oven at 40-60 °C for 72 hours to obtain a debonded circuit board.

2. The method for preparing a lipoic acid modified epoxy resin-based sealant and sealing and desealing a circuit board as claimed in claim 1, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxidized soybean oil and thioctic acid, and reacting them under stirring conditions at a temperature of 50°C for a reaction time of 40 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxidized soybean oil monomer is 20 g / L and the mass concentration of the thioctic acid monomer is 50 g / L; (2) pouring the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor into a mold, sealing the reaction mold, and curing it in an oven at 50° C. for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board and place it in an oven at 50°C for 8 hours to obtain a well-sealed circuit board, soak the sealed circuit board in anhydrous ethanol, place it in an oven at 50°C for 72 hours to obtain a debonded circuit board.

3. The preparation method of a lipoic acid modified epoxy resin-based sealant and a circuit board sealing and desealing process as claimed in claim 1, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxidized soybean oil and thioctic acid, and reacting them under stirring at a temperature of 60°C for 35 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxidized soybean oil monomer is 30 g / L and the mass concentration of the thioctic acid monomer is 60 g / L; (2) pouring the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor into a mold, sealing the reaction mold, and curing it in an oven at 50° C. for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board and place it in an oven at 50°C for 8 hours to obtain a well-sealed circuit board, soak the sealed circuit board in anhydrous ethanol, place it in an oven at 50°C for 72 hours to obtain a debonded circuit board.

4. The method for preparing a lipoic acid modified epoxy resin-based sealant and sealing and desealing a circuit board as claimed in claim 1, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxidized soybean oil and thioctic acid, and reacting them under stirring conditions at a temperature of 70°C for 30 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxidized soybean oil monomer is 40 g / L and the mass concentration of the thioctic acid monomer is 70 g / L; (2) pouring the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor into a mold, sealing the reaction mold, and curing it in an oven at 50° C. for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board and place it in an oven at 50°C for 8 hours to obtain a well-sealed circuit board, soak the sealed circuit board in anhydrous ethanol, place it in an oven at 50°C for 72 hours to obtain a debonded circuit board.

5. The method for preparing a lipoic acid modified epoxy resin-based sealant and sealing and desealing a circuit board as claimed in claim 1, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxidized soybean oil and thioctic acid, and reacting them under stirring conditions at a temperature of 80°C for a reaction time of 25 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxidized soybean oil monomer is 50 g / L and the mass concentration of the thioctic acid monomer is 80 g / L; (2) pouring the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor into a mold, sealing the reaction mold, and curing it in an oven at 50° C. for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board and place it in an oven at 50°C for 8 hours to obtain a well-sealed circuit board, soak the sealed circuit board in anhydrous ethanol, place it in an oven at 50°C for 72 hours to obtain a debonded circuit board.

6. The method for preparing a lipoic acid modified epoxy resin-based sealant and sealing and desealing a circuit board as claimed in claim 1, characterized in that: The steps and conditions are as follows: (1) Mixing two monomers, epoxidized soybean oil and thioctic acid, and reacting them under stirring conditions at a temperature of 90°C for a reaction time of 20 minutes to obtain a thioctic acid-modified epoxy resin-based sealant precursor, wherein the mass concentration of the epoxidized soybean oil monomer is 60 g / L and the mass concentration of the thioctic acid monomer is 90 g / L; (2) pouring the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor into a mold, sealing the reaction mold, and curing it in an oven at 50° C. for 8 hours to finally obtain a lipoic acid-modified epoxy resin-based sealant; (3) Pour the above-mentioned lipoic acid-modified epoxy resin-based sealant precursor onto a circuit board, seal the circuit board and place it in an oven at 50°C for 8 hours to obtain a well-sealed circuit board, soak the sealed circuit board in anhydrous ethanol, place it in an oven at 50°C for 72 hours to obtain a debonded circuit board.

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