Use of Incompatible Polymer Blends in Producing Recyclable Sleeve or Roll Fed Shrink Label Films or Facestocks
Publication Date: 2015-Nov-18
The IP.com Prior Art Database
Disclosed is a use and preparation of incompatible polymer blends having different and specific viscosities so as to produce recyclable shrink film The incompatible polymer blends includes styrene butadiene copolymer and polyethylene LDPE COC etc or those of PET g and polyethylene or other incompatible blends
Sleeve or Roll-Fed Shrink Label Films or Facestocks
Inventor: Farid Ghiam
Disclosed is a use and preparation of incompatible polymer blends, having different and specific viscosities so as to produce recyclable shrink film. The incompatible polymer blends includes styrene butadiene copolymer and polyethylene (LDPE, COC, etc.) or those of PET-g and polyethylene, or other incompatible blends.
Problem and Opportunity
Shrink label films made from polymers with densities greater than 1g/cm³, such as those made from PETG (polyethylene terephthalate glycol-modified) or styrene butadiene copolymer (known as OPS shrink films) are not recyclable, as they sink in water during recycling process and making it almost impossible to separate them from the container’s base material. The majority of containers, especially those used in dairy, juice, or beverage industries, are commonly made from PET (polyethylene terephthalate), PS (polystyrene), or PC (polycarbonate). All of these polymers have densities greater than 1 and in the recycling process (i.e., in the sink-float operation) they submerge in the water making separation from the container almost impossible. Accordingly there remains a need to provide a material and method of producing such material that can be used for producing recyclable sleeve or roll-fed shrink labels.
It is an object of the present subject matter to blend incompatible polymer having differing and specific viscosities such as styrene butadiene copolymer and polyethylene (LDPE, COC, etc.) or those of PET-g and polyethylene, or other incompatible blends, could be prepared by addition of a minor phase. It is another object of the present subject matter to produce an oriented shrink film from such blends through extrusion followed by any orientation process such as MDO or TDO or biaxial stretching. The addition of the minor phase, in this example polyethylene, is aimed to reduce product’s density to below 1 and makes the label film recyclable.
Description of the Invention
In view of the foregoing, it is provided that the incompatible polymers with specific rheological properties (i.e. viscosity ratios) can be blended, extruded and subsequently oriented to produce a recyclable shrink film (or label stock) with comparable (or better) shrink performance (shrink percentage) than that of the mono component film. For instance, oriented polystyrene shrink films with a density of close to 1 g/cm3 when blended with polyethylene with a density of lower than 1 g/cm3 would result in a product with overall density of lower than 1 g/cm3, rendering the product recyclable. Furthermore, if the blend component viscosity ratios and processing conditions are carefully chosen the dispersed phase could be made to form fibrils or cylindrical morphologies which in...