CN-122012004-A - Preparation method of bio-based reversible cross-linked polyurethane hot melt adhesive

Abstract

The invention provides a preparation method of a bio-based reversible cross-linked polyurethane hot melt adhesive. The method comprises the steps of firstly, carrying out polymerization reaction on biological polyol PO3G (polytrimethylene ether glycol) and isophorone diisocyanate serving as raw materials to obtain an isocyanate-terminated biological prepolymer, then, carrying out chain extension reaction by taking diethyl toluenediamine and m-phthalhydrazide as a mixed chain extender, and drying to obtain the biological polyurethane hot melt adhesive. The bio-based hot melt adhesive prepared by the invention is suitable for hot melt type sealant in the field of electronic devices. The adhesive has good bonding performance on stainless steel base materials, has tensile shear strength of 0.45-0.5 MPa and excellent reversible disassembly characteristic, and can realize convenient separation of bonding interfaces after heating for 10 minutes at 100 ℃.

Inventors

• WANG WENPIN
• LI JIALIN
• LIU HAIZHU
• LI ZHONGCHENG

Assignees

• 青岛科技大学

Dates

Publication Date

20260512

Application Date

20260323

Claims (2)

1. 1. The preparation method of the bio-based reversible cross-linked polyurethane hot melt adhesive is characterized by comprising the following steps: ① Mixing 1-3 mmol bio-based polyol PO3G (polytrimethylene ether glycol), 2-6 mmol isophorone diisocyanate and 10-15 mg dibutyl tin dilaurate, reacting at 60-75 ℃ under the protection of N 2 for 1-2 h to obtain isocyanate-terminated bio-based prepolymer, dissolving 0.5-1.5 mmol chain extender monomer diethyl toluenediamine and 0.5-1.5 mmol hydrazide monomer m-phthalhydrazide in 5-15 mL N-N-dimethylacetamide by ②, dropwise adding into the bio-based prepolymer prepared by ① for continuous chain extension for 12-24 h, and drying to obtain the bio-based polyurethane hot melt adhesive, wherein the number average molecular weight of the bio-based polyol PO3G is 1000 or 2000G/mol, and the molar ratio of PO3G, isophorone diisocyanate, diethyl toluenediamine and m-phthalhydrazide is 2:4:1:1.
2. 2. Use of the biobased reversible cross-linked polyurethane hot melt adhesive obtained by the preparation method of claim 1 as a hot melt type sealant in the field of electronic devices, wherein the hot melt adhesive has a tensile shear strength of 0.45-0.5 MPa to a stainless steel substrate and can be heated at 100 ℃ for 10 minutes to separate an adhesive interface.

Description

Preparation method of bio-based reversible cross-linked polyurethane hot melt adhesive Technical Field The invention relates to a recyclable environment-friendly adhesive, in particular to a bio-based polyurethane hot melt adhesive for realizing thermal reversible crosslinking based on the actions of a bio-based polyol soft segment and a multi-level hydrogen bond and a preparation method thereof. Technical Field As a solvent-free and environment-friendly adhesive material, the hot melt adhesive is widely applied to the fields of packaging, spinning, electronics, automobiles and the like. Polyurethane hot melt adhesives are of great interest because of their excellent adhesive properties, good flexibility and weatherability. From the molecular structure, the polyurethane hot melt adhesive also has the block copolymerization characteristic formed by soft segments and hard segments, and the microscopic phase separation structure and adjustable molecular design of the polyurethane hot melt adhesive provide a basis for the performance optimization of the polyurethane hot melt adhesive. Under the trend of global environmental protection and sustainable development, the bio-based raw materials (such as bio-based polyol) are utilized to replace petroleum-based raw materials to synthesize the polyurethane hot melt adhesive, so that the polyurethane hot melt adhesive meets the development requirements of green low carbon and provides a new idea for expanding the application field of the polyurethane hot melt adhesive. However, the current bio-based polyurethane hot melt adhesives still face a key bottleneck in practical application. On one hand, the mechanical property and the bonding strength of the hot melt adhesive are generally lower than those of petroleum-based products, and the requirements of high-strength use scenes are difficult to meet, and on the other hand, the influence of the thermal reversibility and the structural stability of the hot melt adhesive on the bonding performance in the repeated melt processing process is not fully solved. It is worth noting how to achieve a synergistic increase in adhesive strength while maintaining good flowability and reversible adhesive properties has become an important research point in this field. Chinese patent No. 120310511B discloses a bio-based polyurethane hot melt adhesive and a preparation method thereof, and the hot melt adhesive is said to have the characteristics of high hydrolysis resistance, high initial adhesion and high bonding strength. Chinese patent CN115926722B discloses a method for preparing a recyclable bio-based thermosetting polyurethane hot melt adhesive, which is said to have the characteristics of low melt viscosity, high peel strength and recyclability. The invention aims to construct the bio-based polyurethane hot melt adhesive with the characteristics of thermal reversibility, high peel strength and recoverability by introducing the bio-based soft segment and cooperatively improving the effect of disordered hydrogen bonds in the hard segment. Disclosure of Invention The invention aims to provide a preparation method of a bio-based polyurethane hot melt adhesive, and the hot melt adhesive prepared by the method has excellent bonding strength, thermal reversibility and recyclability, so that the green sustainability of the whole life cycle of a product is realized. In order to achieve the above purpose, the invention provides a bio-based polyurethane hot melt adhesive. The adhesive takes bio-based polyol as a soft segment, and has excellent bonding strength and good heat recovery performance through multi-stage hydrogen bonding. The invention provides a preparation method of a bio-based reversible cross-linked polyurethane hot melt adhesive, which comprises the following steps: (1) Mixing 1-3 mmol bio-based polyol PO3G (polytrimethylene ether glycol), 2-6 mmol isophorone diisocyanate and 10-15 mg dibutyltin dilaurate, and reacting at 60-75 ℃ under the protection of N 2 for 1-2 h to obtain an isocyanate-terminated bio-based prepolymer; (2) Dissolving 0.5-1.5 mmol chain extender monomer diethyl toluenediamine and 0.5-1.5 mmol hydrazide monomer m-phthalhydrazide in 5-15 mL N-N-dimethylacetamide, dropwise adding the mixture into the bio-based prepolymer prepared in the step (1) for continuous chain extension reaction of 12-24 h, and drying to obtain the bio-based polyurethane hot melt adhesive, wherein the number average molecular weight of the bio-based polyol PO3G is 1000 or 2000G/mol, and the mol ratio of PO3G, isophorone diisocyanate, diethyl toluenediamine and m-phthalhydrazide is 2:4:1:1; (3) The application of the bio-based reversible cross-linked polyurethane hot melt adhesive prepared in the step (2) in the field of electronic devices is characterized in that the tensile shear strength of the hot melt adhesive on a stainless steel substrate is 0.45-0.5 MPa, and the adhesive interface can be separated by heating for 10 minutes at 100