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The invisible car cover of the car is mainly divided into three parts: coating, substrate and adhesive layer.
Summary
What types of pressure sensitive adhesives are there?
Which aspect of water-based pressure-sensitive adhesive cannot meet the requirements of car coating film?
What conditions need to be met as a qualified car coating glue?
1.
Pressure-sensitive adhesives are divided into water-based and oil-based pressure-sensitive adhesives according to different types of solvents.
What is water-based pressure-sensitive adhesive: Water-based polyurethane pressure-sensitive adhesive is a type of adhesive that is sensitive to pressure
The water-based pressure-sensitive adhesive contains surfactant.
2.
If the car cover has requirements for peeling force, the peeling force, initial tack force and cohesion force are very high.
Compared with many other pressure-sensitive tapes, the car coating film has a big difference in the application scene.
(1) Peel force: Peel strength refers to the force required to peel off the adhesive layer from a standard substrate at a constant rate and angle
.
How much N is required for the peel strength of the car cover, as shown in the following figure:
(2) Initial tack: The initial tack is the bond strength formed by the rapid "wetting" of the pressure-sensitive adhesive to the substrate under relatively small pressure, which is mainly determined by the mobility of the segment.
It has strong mobility, can form good wetting with the rough substrate surface, and can reach the molecular level contact with the substrate molecules, so that sufficient bonding strength can be generated by the intermolecular interaction force
.
Decide whether the construction personnel can repeat the construction and present the perfect construction effect
.
(3) Cohesion: refers to the internal strength of the colloid.
The cohesion of the colloid as a protective film must be very high, otherwise when the film is torn, the internal cracking of the colloid will cause residual glue
.
(4) The test standards for aging properties are xenon lamp aging resistance, heat aging resistance, and moisture aging resistance
.
(5) Adhesion of the substrate: the bonding force between the colloid and the substrate
.
Reasons for no glue residue: Adhesion and cohesion are the determining factors for whether glue will remain on the surface of the car paint or take away the vapor paint when the film is peeled off
.
Once the adhesion is less than the adhesion, glue will remain on the surface of the paint; and if the adhesion is greater than the cohesion, the tearing of the film will also cause the bonds between the glue molecules to break, which will eventually lead to glue retention
.
Under normal circumstances, if you want cohesion and adhesion to be greater than adhesion, there are requirements for the texture of the glue
.
At present, pressure-sensitive adhesives can meet this situation on the market.
Generally, the adhesion of pressure-sensitive adhesives < cohesion < adhesion.
The use of pressure-sensitive adhesives to make invisible car covers can greatly reduce the phenomenon of car paint sticking
.
Among the pressure-sensitive adhesives, oil-based pressure-sensitive adhesives are the most suitable for car coating film, so most of the oil-based acrylic glues are used in the market now
.