1. It uses water as the medium, is non-toxic, non-flammable, non-polluting, non-dangerous, has a small smell, does not pollute the environment and saves energy
, and is especially suitable for products that are easily contaminated by organic solvents. Bonding of corroded substrates.
2. The viscosity is low and can be adjusted with water-soluble thickener and water. It is easy to operate and the residual glue is easy to clean.
3. It can be mixed with a variety of water-based resins to improve performance and reduce costs, but attention should be paid to ionicity and acidity to prevent aggregation.
4. It contains carboxyl, hydroxyl and other groups, which can participate in the reaction under appropriate conditions to produce cross-linking
and improve the bonding performance.
Everything has two sides, and water-based polyurethane adhesive is no exception. In addition to the above advantages, it also has poor wettability to non-polar substrates, slow drying speed, low initial viscosity, and poor water resistance. Good and other defects, so when using it, you must carefully choose based on its advantages and disadvantages
Types of adhesives for bonding wood Source: China Adhesive Network
Phenolic resin for bonding wood There are two types of adhesives: water-soluble and alcohol-soluble.
Water-soluble phenolic resin adhesive is made by the condensation polymerization of phenol and formaldehyde in the presence of sodium hydroxide. The appearance is dark brown transparent viscous liquid with a solid content of 45% to 50%. It is mainly used to produce water-resistant plywood and fiberboard.
Alcohol-soluble phenolic resin adhesive is made by condensation polymerization of phenol and formaldehyde in the presence of ammonia water, dehydration under reduced pressure and then dissolving with an appropriate amount of alcohol. Appearance is a brown transparent liquid with a solid content of not less than 50%. It is thinner than water-soluble liquid. It can be further diluted with alcohol when used, but it is insoluble in water. It becomes turbid and stratified when exposed to water. It is mainly used for impregnation and production of paper. High-grade water-resistant plywood
. In order to meet the needs of certain situations where heat curing is not possible, phenolic tree iS adhesives cured at room temperature have also been developed and produced. This type of adhesive is obtained by polymerizing phenol and formaldehyde in the presence of sodium hydroxide or barium hydroxide, dehydrating under reduced pressure, and diluting with alcohol; its solid content is between 65% and 70%, and its viscosity is relatively high. This type of adhesive can be cured at room temperature by adding benzene sulfonic acid. It is a wood adhesive that is easy to use, has high bonding strength and excellent performance. It is widely used in the bonding production process of the construction, transportation and furniture sectors. Some of them have relatively low free phenol content, while others have as high as 20%, so care should be taken when using them. In addition, due to the use of sulfonic acid curing agents, wood is more susceptible to aging, so it is currently mainly used in special situations where heat bonding is not possible.