Phenolic resin adhesive is one of the early and widely used varieties among synthetic resin adhesives. It finds extensive applications in industries such as construction material processing, construction engineering, coatings, plastics, aviation, ships, automobiles, tractors, aerospace, and light industry. Phenolic resin adhesive is known for its high bonding strength, resistance to high temperatures, water, and oil, cost-effectiveness, ease of production, and modification.

To date, in the field of synthetic adhesives, phenolic resin adhesives remain one of the major categories in terms of quantity, especially modified phenolic resin adhesives hold a significant position. Due to the raw materials used in phenolic resin production, which include phenols and aldehydes, free phenols and aldehydes, especially free formaldehyde, are harmful to humans and the environment. Therefore, it is crucial to strictly control their content and produce phenolic resins with minimal or no free phenols and free aldehydes. Environmentally friendly modified phenolic resin products have been developed both domestically and internationally.

Phenolic resin adhesives come in various types, and their classification methods differ based on the raw materials, synthesis conditions, performance, and application requirements. They can be broadly categorized into two major types: phenolic resin adhesives and modified phenolic resin adhesives. Additionally, they can be classified based on curing temperatures into high-temperature curing, medium-temperature curing, and room-temperature curing phenolic resin adhesives. Here are details on the three subtypes:

1. High-temperature curing phenolic resin adhesive uses a strong alkali as a catalyst, with a reaction medium having a pH greater than 10, and it cures at 130~150°C. When a weak alkali is used as the catalyst, and the pH of the reaction medium is less than 9, the initial phenolic resin formed is dissolved in alcohol and cured at 130~150°C.

2. Medium-temperature curing phenolic resin adhesive uses alkali as a catalyst in a reaction medium with a pH greater than 12, and the resin cures at 105~115°C.

3. Room-temperature curing phenolic resin adhesive uses a strong alkali as a catalyst. Initially, the phenolic resin is dissolved in an organic solvent and cured at room temperature under acidic conditions.