Preparation method of alcohol-soluble gel adhesive

Abstract

The invention discloses an alcohol-soluble gel adhesive and a preparation method thereof, and belongs to the field of adhesives. Two monomers including lipoic acid and zein are dissolved in absolute ethyl alcohol, polymerization reaction is carried out under the heating condition of 70 DEG C, and after the solvent is completely volatilized, the solvent-free bio-based alcohol-soluble gel adhesive is finally prepared. The adhesive prepared by the preparation method disclosed by the invention shows excellent adhesive capacity to various base materials (including wood, aluminum, copper, iron, polyvinyl chloride, polymethyl methacrylate and polytetrafluoroethylene) in air and underwater environments, the adhesive strength of the adhesive in the air can reach 1.35 MPa, and the adhesive strength of the adhesive in the underwater environment can reach 1.04 MPa. Depending on a dynamically reversible polymer system, the adhesive exhibits good recyclability and recyclability. The high-strength bonding method of the biomass adhesive provided by the invention can provide a new idea for the design of a new generation of solvent-free high-adhesion-strength bio-based adhesive.

Description

Technical Field

[0001] The present invention belongs to an alcohol-soluble gel adhesive and a preparation method thereof, and relates to the field of adhesives. Background Art

[0002] Adhesives have a wide range of applications in industry, biomedicine, and daily life, such as traditional wood products, wound dressings, wearable electronics, and battery systems. Most of the raw materials of traditional adhesives are derived from non-renewable petroleum resources, and their high performance and low cost make them dominant in industrial applications. However, the limitedness, non-sustainability of petroleum resources, and the problems of difficult biodegradation and white pollution are becoming increasingly prominent. These environmental problems pose a severe challenge to the ecological balance and the sustainable development of mankind. In addition, the demand for solvents in traditional adhesives is not conducive to the green synthesis and circular economy of adhesives. Therefore, the development of a solvent-free, formaldehyde-free, and recyclable adhesive based on bio-based monomers is of great significance for promoting the development of green and sustainable adhesives.

[0003] The effective development of bio-based adhesives reduces the dependence on petroleum resources in the field of adhesive materials. In addition, the biodegradability of biomass adhesives has less impact on the environment, which conforms to the concept of green chemistry and sustainable development. In the future, with the increasing demand for environmental protection, bio-based adhesives will become an important direction for the development of materials science and industry. For example, Patent CN202411423249 discloses a preparation method of a recyclable mussel-inspired bio-based epoxy resin adhesive, which obtains a high-performance bio-based epoxy resin adhesive with high adhesion strength and recyclability through the reaction of bio-based epoxy polyaldehyde, diamine, and mussel-inspired aldehyde-based compounds. However, since most natural polymers have polar groups, bio-based adhesives absorb moisture as a boundary layer, which weakens the interfacial adhesion and bonding strength, limiting their practical applications. In addition, most of the existing bio-based adhesives cannot achieve repeated adhesion and closed-loop recycling. Therefore, the development of a bio-based sustainable adhesive that can be recycled in a closed loop is of great significance.

[0004] Zein mainly exists in the corn endosperm and shows broad application potential in fields such as food packaging, drug delivery, biosensors, and tissue engineering. As a natural biomaterial, zein has the characteristics of rich resources, low cost, biocompatibility, biodegradability, and renewability, providing an important idea for the replacement of traditional adhesives. Its non-polar amino acid residues (such as proline, leucine, alanine, and glutamine, etc.) can form physical interactions such as hydrogen bonds with the polymer network and the substrate surface, endowing the material with good adhesion properties. In addition, the biocompatibility and degradability of zein make it have broad prospects in the biomedical field, such as being used as a carrier for biosensors or a drug delivery platform. Therefore, zein has great research significance and value in the construction of bio-based adhesives.

[0005] Thioctic acid (TA) is a hydrophobic molecule containing a dithiolane ring. The dithiolane ring in its structure will undergo ring-opening polymerization under heating conditions to form a viscous fluid polymer. The polymer main chain contains hydrophobic dynamic covalent disulfide bonds, which can effectively drive away the interfacial water molecules on the substrate surface, thus forming good physical contact with the substrate. In addition, the terminal carboxyl groups of the polymer can further enhance the adhesion performance of the material through non-covalent interactions such as hydrogen bonds. At the same time, the thioctic acid-based polymer also exhibits characteristics such as self-healing, recyclable, degradable, and reversible adhesion, making it show broad application potential in multiple fields. Summary of the Invention

[0006] Object of the Invention: In order to address the huge challenges of traditional adhesive materials to green synthesis and circular economy, the object of the present invention is to provide a solvent-free recyclable alcohol gel adhesive and its preparation method, providing a new idea for the development of solvent-free bio-based adhesives.

[0007] Technical Solution: A preparation method of an alcohol gel adhesive, the steps and conditions are as follows: (1) Add 2 - 10 g of zein to 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, add 10 g of thioctic acid monomer and continue to stir for 30 minutes to obtain a precursor solution of the alcohol gel adhesive; the mass concentration of zein monomer in the solution is 40 g / L - 200 g / L, and the mass concentration of thioctic acid monomer is 200 g / L; (2) Place the above precursor solution of the alcohol gel adhesive in an oven at 70 °C and react for 72 hours. After the solvent has completely evaporated, a solvent-free alcohol gel adhesive is finally prepared. The mass ratio between the zein and the thioctic acid monomer used is 0.2 - 1:1.

[0008] Innovation point: The innovation of the present invention lies in combining a dynamic polythioctic acid polymer with a hydrophobic zein to construct a solvent-free bio-based adhesive. By relying on the synergistic effect of zein and the polythioctic acid polymer, the balance between the overall cohesion and interfacial adhesion of the adhesive is effectively adjusted. The hydrogen bond interaction between the amino acid residues of zein and the carboxyl groups in the polythioctic acid polymer chain endows the adhesive with high-strength adhesion performance. Due to the dynamic nature of polythioctic acid, the adhesive exhibits good functional characteristics such as reusability and recyclability, providing a new idea for the development of sustainable adhesives. Beneficial effects

[0009] The present invention prepares an alcohol-soluble gel adhesive, which requires monomers with low cost for preparation, has a safe and simple preparation process, and does not generate harmful substances such as formaldehyde. (2) The alcohol-soluble gel adhesive prepared by the present invention achieves strong underwater adhesion to a variety of substrates, including: wood, aluminum, copper, iron, polyvinyl chloride, polymethyl methacrylate, and polytetrafluoroethylene. (3) The alcohol-soluble gel adhesive prepared by the present invention exhibits good functional characteristics such as reusability and recyclability, and its design concept provides a new idea and method for green sustainable adhesives. Specific embodiments Example 1

[0010] (1) Add 2 g of zein to 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, and then add 10 g of thioctic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of the alcohol-soluble gel adhesive; the mass concentration of zein monomer in the solution is 40 g / L, and the mass concentration of thioctic acid monomer is 200 g / L. (2) Place the above precursor solution of the alcohol-soluble gel adhesive in an oven at 70 °C and polymerize for 72 hours. After the solvent has completely evaporated, a solvent-free alcohol-soluble gel adhesive is finally obtained. The mass ratio between the zein and thioctic acid monomer used is 0.2:1.

[0011] Testing method for the prepared alcohol-soluble gel adhesive: Take 1 mL of the prepared adhesive fluid and coat it on the surface of the substrate, with the coating area fixed at 2.5 cm × 2.0 cm. Use a Shimadzu universal testing machine (model: SHIMADZU AGS-X10KN) from Japan for shear testing, and the testing speed is 50 mm / min. Using the above testing method, the shear strength of the alcohol-soluble gel adhesive prepared in Example 1 is 0.08 MPa. Example 2

[0012] (1) Add 4 g of zein to 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of the alcohol-soluble gel adhesive; the mass concentration of zein monomer in the solution is 80 g / L, and the mass concentration of lipoic acid monomer is 200 g / L; (2) Place the above precursor solution of the alcohol-soluble gel adhesive in an oven at 70 °C and polymerize for 72 hours. After the solvent has completely evaporated, a solvent-free alcohol-soluble gel adhesive is finally obtained. The mass ratio between the zein and the lipoic acid monomer used is 0.4:1.

[0013] Using the test method of Example 1, the shear strength of the alcohol-soluble gel adhesive prepared in Example 2 is 0.51 MPa. Example 3

[0014] (1) Add 6 g of zein to 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of the alcohol-soluble gel adhesive; the mass concentration of zein monomer in the solution is 120 g / L, and the mass concentration of lipoic acid monomer is 200 g / L; (2) Place the above precursor solution of the alcohol-soluble gel adhesive in an oven at 70 °C and polymerize for 72 hours. After the solvent has completely evaporated, a solvent-free alcohol-soluble gel adhesive is finally obtained. The mass ratio between the zein and the lipoic acid monomer used is 0.6:1.

[0015] Using the test method of Example 1, the shear strength of the alcohol-soluble gel adhesive prepared in Example 3 is 1.05 MPa. Example 4

[0016] (1) Add 8 g of zein to 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of the alcohol-soluble gel adhesive; the mass concentration of zein monomer in the solution is 160 g / L, and the mass concentration of lipoic acid monomer is 200 g / L; (2) Place the above precursor solution of the alcohol-soluble gel adhesive in an oven at 70 °C and polymerize for 72 hours. After the solvent has completely evaporated, a solvent-free alcohol-soluble gel adhesive is finally obtained. The mass ratio between the zein and the lipoic acid monomer used is 0.8:1.

[0017] Using the test method of Example 1, the shear strength of the alcohol-soluble gel adhesive prepared in Example 4 is 1.35 MPa. Example 5

[0018] (1) Add 10 g of zein into 50 ml of absolute ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of the zein gel adhesive; the mass concentration of zein monomer in the solution is 200 g / L, and the mass concentration of lipoic acid monomer is 200 g / L. (2) Place the above precursor solution of the zein gel adhesive in an oven at 70 °C for polymerization for 72 hours. After the solvent has completely evaporated, a solvent-free zein gel adhesive is finally obtained. The mass ratio between the zein and the lipoic acid monomer used is 1:1.

[0019] Using the test method of Example 1, the shear strength of the zein gel adhesive prepared in Example 5 is 0.75 MPa.

Claims

1. A method for preparing an alcohol sol gel adhesive, characterized in that: The steps and conditions are as follows: (1) Add 2-10 g of zein to 50 ml of anhydrous ethanol, stir at 50°C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of an alcohol-sol gel adhesive; the mass concentration of the zein monomer in the solution is 40 g / L-200 g / L, and the mass concentration of the lipoic acid monomer is 200 g / L; (2) The precursor solution of the alcohol sol gel adhesive is placed in an oven at 70°C for reaction for 72 hours, and after the solvent is completely evaporated, a solvent-free alcohol sol gel adhesive is finally prepared. The mass ratio of the zein to the lipoic acid monomer used is 0.2 to 1:

1.

2. The method for preparing an alcohol sol gel adhesive according to claim 1, characterized in that: The steps and conditions are as follows: (1) Add 2 g of zein to 50 ml of anhydrous ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of alcohol sol gel adhesive; the mass concentration of zein monomer in the solution is 40 g / L, and the mass concentration of lipoic acid monomer is 200 g / L; (2) The precursor solution of the alcohol sol gel adhesive is placed in an oven at 70°C for polymerization for 72 hours, and after the solvent is completely evaporated, a solvent-free alcohol sol gel adhesive is finally prepared. The mass ratio of the zein to the lipoic acid monomer used is 0.2:

1.

3. The method for preparing an alcohol sol gel adhesive according to claim 1, characterized in that: The steps and conditions are as follows: (1) 4 g of zein was added to 50 ml of anhydrous ethanol, and the mixture was stirred at 50 °C until completely dissolved. 10 g of lipoic acid monomer was added and the mixture was stirred for 30 minutes to obtain a precursor solution of an alcohol-sol gel adhesive. The mass concentration of the zein monomer in the solution was 80 g / L, and the mass concentration of the lipoic acid monomer was 200 g / L. (2) The precursor solution of the alcohol sol gel adhesive was placed in an oven at 70°C for polymerization for 72 hours, and after the solvent was completely evaporated, a solvent-free alcohol sol gel adhesive was finally prepared. The mass ratio of the zein to the lipoic acid monomer was 0.4:

1.

4. The method for preparing an alcohol sol gel adhesive according to claim 1, characterized in that: The steps and conditions are as follows: (1) Add 6 g of zein to 50 ml of anhydrous ethanol, stir at 50 °C until completely dissolved, add 10 g of lipoic acid monomer and continue stirring for 30 minutes to obtain a precursor solution of alcohol sol gel adhesive; the mass concentration of zein monomer in the solution is 120 g / L, and the mass concentration of lipoic acid monomer is 200 g / L; (2) The precursor solution of the alcohol sol gel adhesive was placed in an oven at 70°C for polymerization for 72 hours, and after the solvent was completely evaporated, a solvent-free alcohol sol gel adhesive was finally prepared. The mass ratio of the zein to the lipoic acid monomer was 0.6:

1.

5. The method for preparing an alcohol sol gel adhesive according to claim 1, characterized in that: The steps and conditions are as follows: (1) 8 g of zein was added to 50 ml of anhydrous ethanol, and the mixture was stirred at 50 °C until completely dissolved. 10 g of lipoic acid monomer was added and the mixture was stirred for 30 minutes to obtain a precursor solution of an alcohol-sol gel adhesive. The mass concentration of the zein monomer in the solution was 160 g / L, and the mass concentration of the lipoic acid monomer was 200 g / L. (2) The precursor solution of the alcohol sol gel adhesive is placed in an oven at 70°C for polymerization for 72 hours, and after the solvent is completely evaporated, a solvent-free alcohol sol gel adhesive is finally prepared. The mass ratio of the zein to the lipoic acid monomer used is 0.8:

1.

6. The method for preparing an alcohol sol gel adhesive according to claim 1, characterized in that: The steps and conditions are as follows: (1) 10 g of zein was added to 50 ml of anhydrous ethanol, and the mixture was stirred at 50 °C until completely dissolved. 10 g of lipoic acid monomer was added and the mixture was stirred for 30 minutes to obtain a precursor solution of an alcohol-sol gel adhesive. The mass concentration of the zein monomer in the solution was 200 g / L, and the mass concentration of the lipoic acid monomer was 200 g / L. (2) The precursor solution of the alcohol sol gel adhesive is placed in an oven at 70°C for polymerization for 72 hours, and after the solvent is completely evaporated, a solvent-free alcohol sol gel adhesive is finally prepared. The mass ratio of the zein to the lipoic acid monomer used is 1:1.