Brasil Pack Trends 2020

BrasilPackTrends2020 161 qual ity and new technologies Barrier materials The polymeric materials are permeable to gas and water vapor, differently from metallic and glass packages, and that limit the application for various products categories. However, the barrier properties can be improved by using nanocomposites and oxide coatings. Nanomaterials (clays, nanofibers, nanoparticles, etc.) work as small physical barriers to the permeation of gases and vapor through the polymers, making a tortuous path of the permeant through the polymer, slowing down its permeation. When they are present in a sufficient number, they slow down the mass transfer. The effective increase of the package barrier depends on the nanoparticles dispersion on the polymeric matrix. That dispersion is associated with the polymer, nanomaterial and compatibility agents, used to disperse the nanomaterial on the polymer (ROBINSON; MORRISON, 2010). It also depends on the concentration of the nanomaterial and the degree of exfoliation. If there is no layers separation (exfoliation and intercalation), which means that the polymer chain does not penetrate the nanomaterial layers, a conventional composite is obtained, with separate phases, immiscibles, in which the improvement of the mechanical properties can be verified, but not the increase of gas and water vapor barriers, just like the nanocomposites (Picture 6.28). The greater the degree of exfoliation, the bigger the gas and water vapor barrier. Although the incorporation of nanomaterials, especially clays, can be done in various polymers, the polyamide-based nanocomposites are the most commercial successful in barrier resins for packaging (examples: Imperm® by Nanocor® Inc MXD6 polyamide-based and HFX by Honeywell). The company InMat sells nanocomposite water base barrier coating - Nanolook, for films. The material combines polymer with nanoclay dispersed in water. The coating does not interfere in the biopolymers recyclability and compostability. It aims at the dry and oxygen sensitive food markets, such as coffee, nuts and snacks. FIGURE 6.28 Structure of nanocomposites (PAIVA; MORALES, 2006) The coating of films with silicon oxide SiO x through a physicial vapor deposition process with a good uniformity and adherence provides high humidity and gas barrier, keeping the package transparency. It is actually a polymer coating with manometric particles, usually applied in PET film, or bio-oriented polyamide. An example of that technology is the film family called Ceramis, by Amcor. In the field of PET bottles, Toyo Seikan Kaisha sells the SiBARD technology, which is a double internal package coating. Initially an organic silicone film is formed and it provides flexibility and adhesivity to other internal coating of the silicon oxide, with good gas barrier properties. The coating is very thin, does not compromise the recyclability and has high transparency. Mitsubishi Shoji Plastics uses the coating technology called Plasma Nano Shield (plasma enhanced chemical vapor deposition) of amorphous carbon for high barrier PET bottles. To increase the light barrier of polymeric packages, zinc nano-oxide and titanium nanodioxide are incorporated in polymers as anti-UV agents. DuPont is selling a titanium dioxide nanoparticle (Light Stabilizer 210) as a barrier to the UV light.