There are dozens of different types of plastic bags on rolls. They vary in size, thickness, type of material, bag construction, customization and manner in which they are mounted on the plastic bags on rolls.
Available Sizes and Thicknesses
Plastic bags come in a vast range of sizes and thicknesses, as varied as the types that are available. They can be as small as 1” x 2” nut and bolt bags and as large as 55- gallon drum liners or larger. They can range in thickness from.75 mils up to 8 mils. A mil, as a unit of measure, is defined as a thousandth of an inch.
Types of Material
There are a number of different materials available for the manufacture of plastic bags on rolls. The application determines the type of material chosen. Materials offered include:
• High-density polyethylene (HDPE) – thermoplastic made from petroleum. The density can range from .93 to .97 g/cm3. HDPE has little branching, giving it a higher tensile and specific strength than LDPE. It is also harder, more opaque and more temperature resistant.
• Low-density polyethylene (LDPE) – thermoplastic made from ethylene. The density range for LDPE is .91 to .94 g/cm3. LDPE has more branching, giving it lower tensile strength and higher resilience. It can withstand temperatures between 80 and 95 degrees Celsius for limited amounts of time.
• Linear low-density polyethylene (LLDPE) – thermoplastic made from ethylene. The density is .95 g/cm3. It is produced at lower temperatures than LDPE and therefore has a linear structure. This creates a higher tensile strength and higher impact and puncture resistance.
• Medium-density polyethylene (MDPE). The density range is .926 to .94 g/cm3. MDPE has good drop and stress cracking resistance.
Depending on the purpose of the bag, there are different methods of construction.
• Side Gussets – Pleats along the sides of the bags allow for expansion to an outlined shape.
• Side Weld – Seal along the sides, rather than the top or bottom, to be used in light-weight applications.
• Bottom Seal – Seal along the bottom, to be used in heavier weight applications that put a lot of stress on the seal or sides.
Bags can be customized in several different ways. They can be produced to different size, shape, construction, color and printing options as needed for each individual application, whether it’s for retail or wholesale situations.
Depending on the type of bag, there are a couple of ways that the bags can be mounted on rolls. There are coreless bags, where the bottom seal is wound on itself, creating the roll. Rolls can also be wound onto either a plastic or cardboard core.