Introduction of BOPP adhesives

Plastic film can be produced from different combinations (with different amounts) and in different thicknesses. Adhesive liquid can also have different compositions and thicknesses. In this way, by changing the above factors, many different types of adhesive tapes are produced, which are used in various industries (from printing and stationery to construction, automotive, electricity and packaging).

In fact, adhesive tapes are initially produced in the form of large and wide rolls of film (JUMBO ROLL) and then covered with adhesive liquids. These rolls are then opened by special machines (slitters) and in different widths (10 to 20). Mm in stationery, 25 to 72 mm in packaging and wider widths in construction and insulation industries (cut and rewinded with desired lengths).

Polypropylene (PP) films are mostly used in the packaging industry. PP can be used because of its much higher hardness (three times that of mold films and eight times that of polyethylene PE) and also because it can be used in thermal adhesion. Current global consumption of PP is estimated at more than one million tons per year. Typical film thicknesses range from 15 to 50 microns.

The films used to produce the adhesive tape are usually of the BOPP (bi axially oriented poly propylene) type. In this method, the thickness is more uniform and also the film is not easily torn by stretching in width and length, but it is stretched in simple language, ie the breaking point can occur after 100 to even 180% stretching.
The most important advantages of these films are:

• High hardness
• High tensile strength
• Very good barrier against water
• High recycling ability
• Microbial contamination much less than other films
• Easy to print
• Ability to present in different colors

The type and quality of the adhesive that is applied to the film, as well as the quality of the coating, is the second factor in shaping the type of adhesive tape.

Release coat: Makes the adhesive tape easy to remove from the roll. This combination is usually almost the same in different factories.
Backing film: The same plastic film we described earlier.
Primer coat: causes better quality (durability) of the adhesive liquid on the film. This combination is the same in most factories.
Adhesive mass coating: Different types of adhesives with different compositions and thicknesses are used in the manufacture of adhesive tapes. The most common type in most adhesive tapes is acrylic polymer, which comes in two types

• Water-based acrylic emulsion
• Adhesive liquid with chemical solvent

is used. The composition of these adhesives and the times of their use are the secrets of the expertise of each manufacturer, which is achieved over time and takes great care of it. Of course, in this regard, there are national and international standards available.
The thickness of the film and the adhesive usually follow defined ratios. For example, the most common packaging tapes are presented in the following ratios: