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COATINGS FROM POLYOLEFIN DISPERSIONS (PODs) FOR METAL PACKAGING

IP.com Disclosure Number: IPCOM000241159D
Publication Date: 2015-Mar-31

Publishing Venue

The IP.com Prior Art Database

Related People

Mason, Jonathan: AUTHOR [+5]

Abstract

Polyolefin dispersions (PODs) used in food and beverage metal packaging formulations are composed of polyolefin resin (or blends of polyolefins) dispersed in water and are commercially available as CANVERA™ Polyolefin Dispersions. In addition to the polyolefin resin, dispersants, compatibilizers, and, additives are also part of the POD composition. The additives, such as antioxidants, slip agents, crosslinkers, defoamers, etc. can be blended with other components of the POD prior to dispersion, during the dispersion process, or post added once the dispersion has been formed. Acid functional POD components are typically neutralized with base. Any base will work but volatile bases, such as dimethylethanol amine (DMEA, CAS 108-01-0), are preferred for use in coatings for metal packaging. Across the different metal packaging applications, particle size ranges from 0.2 to 2 µm show the best performance. Typically, solid content of the PODs range from 30% to 55%, with viscosity ranging from 100 cP to 5000 cP (measured via Brookfield LV 2, 100 rpm, 21°C). Crosslinkers are often used to crosslink the functional components and/or introduce crosslinking in polyolefin resins. Particularly good crosslinking chemistries for POD formulations include hydroxy alkyl amides (e.g Primid QM-1260, CAS 57843-53-5 or XL-552, CAS 6334-25-4 from EMS Griltech), phenolics (e.g. SFC 112-65 or FB 110 XB-50 from Si Group), and/or peroxides.

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Coatings from Polyolefin Dispersions (PODs) for Metal Packaging

Polyolefin dispersions (POD)

PODs used in metal packaging formulations are composed of polyolefin resin (or blends of polyolefins) dispersed in water. PODs for metal packaging are commercially available as CANVERA™ Polyolefin Dispersions and non-commercial grades are available under an EXP experimental designation. In addition to the polyolefin resin, dispersants, compatibilizers, and, commonly, additives are also part of the POD composition. The additives, such as antioxidants, slip agents, crosslinkers, defoamers, etc. can be blended with other components of the POD prior to dispersion, during the dispersion process, or post added once the dispersion has been formed. Colloidal stability of the POD and its robustness in subsequent formulating, application, and curing are impacted by the choice of additives and the way in which they are incorporated into the POD. Additives which are not easily added or unstable in waterborne formulations can instead be added to the POD during manufacture to avoid these issues. For example, post adding antioxidant to POD is effective at stabilizing coatings made from POD during baking, but over time, as the POD formulation is stored, the stabilization effect can be diminished for some antioxidants. However, incorporation of the antioxidant into the POD during its production step results in longer lasting efficacy due to a homogeneous distribution throughout the composition. As another example, post addition of some slip agents to POD formulations causes issues with colloidal stability and grit formation. However, incorporating the slip agent of the same composition during the POD production eliminates the problem.

Acid functional POD components are typically neutralized with base. Any base will work but volatile bases, such as dimethylethanol amine (DMEA, CAS 108-01-0), are preferred for use in coatings for metal packaging. The amount of base can vary from substoichometric to stoichiometric to suprastoichiometric relative to the amount of acid functionality in the POD. The particle size and composition of the PODs are tailored for the specific metal packaging application. Across the different metal packaging applications, particle size ranges from 0.2 to 2 µm show the best performance. Typically, solid content of the PODs range from 30% to 55%, with viscosity ranging from 100 cP to 5000 cP (measured via Brookfield LV 2, 100 rpm, 21°C).

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Appendix A shows a representative technical datasheet with corresponding properties for a POD for food applications. Appendix B shows a representative technical datasheet for a POD for a beverage application.

POD Coating Formulations for Metal Packaging

POD coating formulations are typically comprised of the POD (or blends with other PODs and/or other binders), co-solvents, additives...