CN-122011994-A - High-shear strength biodegradable hot melt adhesive and preparation method and application thereof

Abstract

A biodegradable hot-melt adhesive with high shear strength is prepared from biodegradable high-molecular material and epoxy resin through chemical reaction to form covalent bond, and optional linking agent or catalyst for promoting reaction. Wherein the mass ratio of the biodegradable polymer material to the epoxy resin is 99.9:0.1-80:20, and the reaction is carried out for 5-30 minutes at 80-200 ℃. The method has simple process and is environment-friendly. The obtained hot melt adhesive has no release of volatile organic compounds, can be biodegraded, can obviously improve the bonding strength by adding a small amount of epoxy resin, and has the lap joint shearing strength of up to 34.37 megapascals. The product is suitable for structural or semi-structural bonding in the fields of packaging, electronic and electric appliances, wood industry manufacturing, building materials, automobiles, transportation, mechanical manufacturing, new energy, medical and health, aerospace and the like with high strength requirements.

Inventors

• HUANG JINRUI
• YANG CHONG
• JIN JING
• GAO YUNBAO
• TAN HAIYING
• JIANG ZONGLIN
• JIANG WEI

Assignees

• 武汉纺织大学

Dates

Publication Date

20260512

Application Date

20260204

Claims (10)

1. 1. The biodegradable hot melt adhesive with high shear strength is characterized by comprising a biodegradable polymer chain segment, an epoxy resin chain segment and an epoxy functional group, wherein the biodegradable polymer chain segment and the epoxy resin chain segment are connected through covalent bonds to form a linear, branched or crosslinked polymer network structure.
2. 2. The high shear strength biodegradable hot melt adhesive according to claim 1, characterized in that the structural unit content of the epoxy resin segments is 0.1 to 20wt.%, based on the total mass of the polymer network.
3. 3. The high shear strength biodegradable hot melt adhesive according to claim 1, wherein said polymer network further comprises a linker residue or catalyst, said linker residue or catalyst being present in an amount of 0.1 to 10% by mass based on the total mass of structural units of said biodegradable polymer segment and epoxy resin segment.
4. 4. The high shear strength biodegradable hot melt adhesive according to claim 1, wherein said biodegradable polymer segments are derived from at least one of polypropylene carbonate, chlorinated polypropylene carbonate, chlorosulfonated polypropylene carbonate, polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, poly (succinic acid-adipic acid-butylene succinate), poly (terephthalic acid-adipic acid-butylene succinate), poly (lactic acid-terephthalic acid-butylene terephthalate), polytrimethylene carbonate, poly (trimethylene carbonate-co-caprolactone), polyanhydride, plasticized or esterified modified starch, cellulose, chitin, chitosan, or copolymers formed from the above polymers.
5. 5. The high shear strength biodegradable hot melt adhesive according to claim 1, wherein said epoxy resin segments are derived from at least one of bisphenol a type epoxy resin, bisphenol F type epoxy resin, cycloaliphatic epoxy resin, hydrogenated bisphenol a type epoxy resin.
6. 6. The high shear strength biodegradable hot melt adhesive according to claim 3, wherein said linker residue is derived from a compound having two or more functional groups selected from at least one of polyacids, anhydrides, polyols, polyamines, polyisocyanates or silane coupling agents, and said catalyst is a compound capable of promoting ring-opening addition reaction of carboxyl groups or hydroxyl groups with epoxy groups selected from at least one of 1-dimethylaminopyridine, triphenylphosphine, 2-methylimidazole, 1-methylimidazole, 2-ethyl-4-methylimidazole, stannous octoate, dibutyltin dilaurate, zinc acetylacetonate, tetramethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium bromide, benzyltriethylammonium chloride, ethyltriphenylphosphine bromide, butyltriphenylphosphine bromide.
7. 7. The biodegradable hot melt adhesive according to any one of claims 1 to 6, characterized in that it has a lap shear strength at room temperature of not less than 5 MPa.
8. 8. A method of preparing the high shear strength biodegradable hot melt adhesive according to any one of claims 1 to 6, comprising mixing biodegradable polymeric material, epoxy resin, and optionally a linker and/or catalyst in a molten state and reacting at 80 ℃ to 200 ℃ for 5 minutes to 30 minutes to form covalent bonds between the biodegradable polymeric material and the epoxy resin, and between them and the optional linker.
9. 9. The preparation method according to claim 8, wherein the mass ratio of the biodegradable polymer material to the epoxy resin is 99.9:0.1 to 80:20.
10. 10. Use of the high shear strength biodegradable hot melt adhesive according to any of claims 1 to 6 for structural bonding or semi-structural bonding in packaging, electronics, wood manufacturing, building materials, automotive and transportation, mechanical manufacturing, new energy, medical hygiene or aerospace applications.

Description

High-shear strength biodegradable hot melt adhesive and preparation method and application thereof Technical Field The invention relates to the technical field of adhesives, in particular to a hot melt adhesive, and especially relates to a high-shear-strength biodegradable hot melt adhesive, and a preparation method and application thereof. Background The adhesive can be used for efficiently connecting various materials and has even stress distribution, and is widely applied to the fields of packaging, furniture, automobiles, electronics and the like. However, conventional solvent-based adhesives release volatile organic compounds during production and use, subject to increasingly stringent environmental regulations. Under this background, a solvent-free and convenient-to-use hot melt adhesive becomes an important environmentally friendly alternative, and the market scale continues to expand. At present, commercial hot melt adhesives are mainly based on petroleum-based polymers such as ethylene-vinyl acetate copolymer, polyolefin, polyamide or polyurethane, and the materials are difficult to degrade in natural environment and easily cause white pollution after being discarded. In addition, the traditional hot melt adhesive mainly relies on physical entanglement and Van der Waals force to realize bonding, and the lap shear strength is generally lower than 4 MPa, so that the bonding requirement of structures or semi-structures with high requirements on reliability, such as woodwork processing, composite material preparation and the like, is difficult to meet. In order to achieve both performance and sustainability, the development of high performance bio-based or biodegradable hot melt adhesives has become an important research direction. One common technical path is to physically blend biodegradable polymers such as polylactic acid, polycaprolactone, etc. with tackifying resins, waxes, etc. For example, the polylactic acid hot melt adhesives disclosed in the prior art are prepared by multi-component melt blending, and although the components synergistically enhance part of the properties, they are still physically mixed in nature, and fail to form strong chemical bonds, so that there is an inherent upper limit on the adhesive strength, and thus, the polylactic acid hot melt adhesives are difficult to apply to structural bearing occasions. Another idea is to chemically modify the biodegradable polymer, for example by introducing polar groups through chlorination or chlorosulfonation reactions, improving the adhesion of the material. The modification can improve the lap shear strength to about 3 MPa while maintaining biodegradability, but the cohesive strength of the adhesive layer is still insufficient because a firm three-dimensional crosslinked network is not formed, and creep is easy to occur under continuous stress, so that the adhesive is mainly suitable for the field of non-structural adhesion. Some recent leading edge researches introduce special acting force into the degradable framework through exquisite molecular design or utilize a novel polymerization method to realize remarkable improvement of bonding performance, and the lap shear strength of part of system steel plates can reach 20.6MPa. These works show great potential for chemical structural design, but their synthetic routes are often complex, involving expensive raw materials or precision catalytic systems, and are costly and a significant distance from large-scale industrial applications. In contrast, chain extension modification routes that form moderately branched or crosslinked structures by introducing multifunctional chain extenders to react with degradable polymer end groups are seen as more promising industrial directions. Research shows that the addition of isocyanate chain extender in specific blend system can raise the molecular weight and interface adhesion performance effectively to 10-25 MPa. The route achieves a good balance among performance, processability and cost. Epoxy resins are widely used in structural adhesives with their excellent mechanical properties, high bond strength and high reactivity, but their conventional curing systems are not biodegradable. If the segments of the epoxy resin and the biodegradable polymer can be combined in a covalent bond manner through chemical reaction, a new material with high bonding strength and degradability can be hopefully created. However, there are few reports in the prior art relating to the realization of deep fusion of the two by a simple process, thereby constructing a high-performance degradable hot melt adhesive system truly suitable for structural bonding. Therefore, developing a novel hot melt adhesive with easily available raw materials, simple process and capability of combining the enhancement effect of epoxy resin with biodegradability through chemical bonding becomes a technical problem to be solved in the field. Disclosure of Invention Aiming at the problems that