The differences between types of adhesives and their applications on plywood

Adhesives play an important role in the plywood manufacturing process. This is the key factor determining the durability as well as the load-bearing capacity of the product. Glue not only binds the layers together but also prevents external factors such as humidity from affecting the plywood quality and appearance. With the diverse requirements for using plywood in furniture, construction projects, and outdoor furniture, there are three main types of adhesives used in the industrial plywood manufacturing industry: Urea Formaldehyde (UF), Melamine Formaldehyde (MF), and Phenol Formaldehyde. (PF). Each type of adhesive has distinct characteristics, providing unique features for the plywood products. The article below will clarify these types of adhesives and the notable differences between them.

1. Urea Formaldehyde (UF)

Introduction: A synthetic adhesive created from the reaction between urea and formalin at an appropriate temperature. There are many types of UF glue, such as E0, E1, and E2 types, based on the concentration of Formaldehyde emissions, among which E2 glue and mixed water glue are commonly used in Vietnam.
Application: UF is widely used for interior plywood products, such as plywood used in dry environments, not exposed to water or moisture. Due to its poor moisture resistance, UF glue is not suitable for products exposed to outdoor environments or high humidity, such as bathrooms or kitchen areas.
Pros and cons: UF glue has the advantage of being cost-effective, having high adhesive strength, suitable for mass production. However, this type of glue does not have water resistance, making the product prone to delamination and warping when exposed to moisture. The amount of Formaldehyde emissions, although within permissible limits, is believed to affect users’ health if exposed for a long period.

2. Melamine Urea Formaldehyde (MUF)

Introduction: A well-known adhesive in Vietnam. Basically, MUF glue is produced similarly to UF glue, undergoing a thermal reaction between Formalin and Urea under the catalysis/inhibition of Formic Acid and Sodium Hydroxide. The difference between MUF glue and UF glue is that in the reaction process of MUF glue, melamine is involved – an organic compound that is poorly soluble in water. MUF glue comes in various types from E0 to E2, serving both domestic production and export. Depending on the percentage of melamine in the adhesive, the properties of the adhesive also vary. The higher the percentage of melamine, the better the quality of the water-resistant plywood. The maximum water resistance level is 20 hours of boiling.
Application: MUF adhesive is suitable for interior plywood products that frequently come into contact with moisture, such as kitchen cabinets, bathroom furniture, and products placed near water sources. The moderate moisture resistance of MF glue makes it widely used in interior spaces that require higher durability compared to UF. In addition, MUF glue is also used to produce other types of plywood such as LVL, film-faced plywood, etc.
Pros and cons: MUF glue has better adhesion and water resistance compared to UF, helping to increase the product’s lifespan in moderately humid environments. Melamine glue plywood products also reduce the delamination of filler layers compared to UF glue. However, MUF glue is more expensive, and its production requires drying fillers as well as technical skills from workers.

3. Phenol-Formaldehyde (PF)

Introduction: A special thermal adhesive made from Phenol and Formaldehyde, used in the wood industry. Due to the special bonds between Phenol and Formaldehyde molecules in the basic environment of the thermal reaction, very tightly bonded and durable chains are formed.
Application: This is the ideal adhesive for outdoor products, construction projects, and furniture placed in high-humidity environments such as ports, factories, or construction projects requiring high durability. The water and heat resistance of PF helps the plywood products avoid delamination or deformation in harsh environments. The boiling water resistance of plywood using this type of adhesive can last up to 100 hours without delaminating.
Pros and cons: Plywood using PF glue has excellent strength, water resistance, and heat resistance, ensuring the product has a long lifespan even in the most extreme environments. The quick curing time helps save production costs. However, the raw materials for producing Phenol glue in Vietnam are not really common, so the production cost of PF glue is much higher compared to other types of glue. The phenol resin mixture is brown, so it sometimes affects the aesthetics of the plywood.

Conclusion

In the production of industrial plywood, the choice of adhesive not only affects the durability and stability of the product but also determines many important features such as water resistance, moisture resistance, and heat resistance.
Understanding the properties of each type of adhesive helps manufacturers choose the right bonding material to optimize the quality and lifespan of the product. At the same time, consumers also need to pay attention to this feature to ensure that the plywood products will best serve their environment and usage needs. With the right adhesive choice, plywood products can be durable over time and meet the stringent requirements of both outdoor and indoor projects, creating solid aesthetic and technical values for living and working spaces.

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