About basics of adhesion
There are many types of adhesives.
There are many types of adhesives for different purposes.
Various adhesives are used to meet customer's production processes or applications.
Adhesives are categorized in different ways as follows:
Categories by main components
In this category, there is cement and other materials that endure a high temperature of 1000℃ or higher, however this category is minor now.
· Silicone-based (water glass and silicate)
· Calcium-based (cement and plaster)
Most adhesives are organic.
· Thermoplastic resins
· Heat-curing resins
· Rubber and elastomer
Categories by forms
They are water-based adhesives that are made by emulsifying the resin and dispersing it to water.
· Epoxy resin-based
· Polyvinyl acetate-based
· Nitrile rubber-based
They are adhesives that are made by dissolving a resin into a solvent, like volatile-solvent type adhesives
· Phenol resin
· Polyvinyl acetate
· Chloroprene rubber-based
They are adhesives that cure by the chemical reaction including the silicone-based and the epoxy-based.
· Epoxy resin-based
· acrylic resin
· Silicone rubber-based
They are solid type adhesives in the forms of such as lumps, powders, and films.
· Epoxy resin-based
· Styrene-butadiene Rubber-based
Categories by curing methods
They cure by vaporizing organic solvents.
ex.) Rubber pastes and adhesives for plastic models
· Polyvinyl acetate
· Nitrile rubber-based
It cures reacting with moisture in the air.
ex.) Instant adhesives and silicone based liquid gaskets
· Cyanoacrylate-based
· Silicone rubber-based
The hardener in the resin is activated and cured by heating
ex.) One-part epoxy resins
· Epoxy resin-based
· acrylic resin
Curing occurs, when the base agent is mixed with a hardener.
ex.) Two-part epoxy resins
· Epoxy resin-based
· Silicone rubber-based
It cures when air is repelled at the metal part. It is used for screws, joints, and pipes.
· Acrylate based (acrylic resin)
It cures in a short time by irradiating ultraviolet rays. It is used as bonding sealants, and adhesives for glasses and transparent plastics.
· acrylic resin
· Epoxy-based
It is coated in molten state, and it cures and bonds when getting cold. It is used for wrapping and bookbinding.
· Styrene-butadiene rubber-based
It bonds by applying pressure at room temperature. It is used for adhesive tapes and seals.
· acrylic resin
This adhesive can glue stamps and other items after wetting their dry adhesive surface with water, etc. to recover its adhesion.
· Chloroprene rubber-based
· Starch-based
To begin with, what is adhesion?
I will briefly explain the concept of adhesion. Let us think of factors that decide the strength of adhesion. Strength of adhesion will be one of the key points in your design requirements.
Factors to decide strength of adhesion
It is necessary that the adhesive soaks on the adherend. Adhesive strength differs depending on soaking of adhesives and the contact angle of two adherends.
There are various theories about bounding mechanism. Adhesive strength differs depending on each bonding process.
The adhesion strength varies depending on the type and material of each adhesive.
There are various theories about bounding mechanism. Adhesive strength differs depending on each bonding process.
Soaking and contact angle
It is ideal that the adhesive completely soaks on the adherend.
Mechanism of bonding
There are several theories on the mechanism that joins one substance to another, as shown below.
The adhesive causes a chemical reaction between the adhesive and the adherend. As this chemical reaction joins moleculars together, the adhesion becomes strong.
The adhesive causes bonding of hydrogen atoms in the adhesive and the adherend. This produces the pulling force of atoms each other. This pulling force makes the adhesion, however the adhesive force is rather weak.
The adhesive penetrates into pits on the surface of the adherend and bonds to the adherend. The adhesive force depends on how strong the anchoring effect is.
The bonding force is generated by the effect of static electricity. The bonding force is rather weak.
Bonding takes place between two adherends the surfaces of which are dissolved by the adhesive.
Because both adherends have dissolved surfaces, the bonding force is strong.
How the adherend receives peeling force
Several different peeling forces are applied on the adherend.
Select an adhesive or application method considering the following forces:
When you choose adhesive, you need to consider the following.
Decide your design requirements comprehensively considering the above factors, then select the most suitable adhesive.
We are ready to listen to your design requirements.
We, ThreeBond are making efforts to offer products that would best suit your design requirements.
Other series of Seminars on Adhesives
No.7
About epoxy resins
No.8
About liquid gaskets
