Multilayer Heat-Sealable Films with Improved Heat Sealing Performance, Improved Hot Tack Performance, and Reduced Delamination
Publication Date: 2011-Jun-28
The IP.com Prior Art Database
Richard Halle: AUTHOR [+4]
This invention describes film compositions that show enhanced heat sealing performance. Specifically, enhancement is provided by blending Vistamaxx™ propylene based elastomers (PBE) into mLLDPE to provide enhanced hot tack performance, enhanced heat seal performance, and reduced delamination.
Richard Halle, Hans Pip, M. Glenn Williams, David Weisinger
Abstract: This invention describes film compositions that show enhanced heat sealing performance. Specifically, enhancement is provided by blending Vistamaxx™ propylene based elastomers (PBE) into mLLDPE to provide enhanced hot tack performance, enhanced heat seal performance, and reduced delamination.
The invention relates to a film structure exhibiting improved heat sealing performance. In particular, the invention relates to a film structure comprised of a metallocene catalyzed co-polymer blend and to the method for manufacturing the film.
In most processes for packaging products, including foodstuffs, such as potato chips, nuts, candy, biscuits, and spices, etc. the package is formed and filled by (i) creating a seal between two opposing film webs, each having at least one skin layer capable of forming a seal under the application of heat and pressure, to form a pocket, and (ii) almost simultaneously sliding or dropping the product to be packaged into the pocket.
For example, a continuous flat web of packaging film may be fed around a hollow-form which shapes the film into a tube. The free edges of the tube are sealed together. A tube thus formed is then passed between a pair of hot sealing jaws positioned across, or transverse, to the tube. The jaws create a series of discrete packages by collapsing the film onto itself and forming a seal through the application of heat and pressure to seal layers in the film structure. The product is introduced into each package through the hollow form in the interval between the heat seals. In the overall process, packages made in the foregoing manner are subsequently cut, separated, and collected into appropriate assemblies.
At high operating speeds, the product is dropped into the package while the sealing jaws, which form the seal, are closed. Alternatively, the product may be dropped into the package at the point that the sealing jaws are opening. With both vertical and horizontal form-and-fill sealing applications, the heat-seal should be strong enough to support and retain the product after the sealing jaws re-open to release the film. In order to achieve maximum operating speeds, the sealing jaws must be released as quickly as possible after the seal is formed.
Hot tack is defined as the strength of a hot seal measured after completion of the sealing cycle, but prior to the temperature of the seal cooling any substantial extent, i.e., the measure of the cohesive strength during the cooling stage before solidification of the heat seal. Hot tack is measured in force per unit of seal width. Hot tack is important in form-fill-seal packaging applications, where the critical window of time is when the seal is in the package machine and must resist the stresses of the product b...