Paper barrier properties

OPP producers have expanded the core, creating a foam stmcture with lower density, greater opacity, and a stiffer, more paper-Hke feel. Vacuum metallisation increases opacity and water-vapor barrier properties. 

Oil Repellent. Fluorochemicals are the only class of material that can provide oil repeUency without altering the porosity of the paper or paperboard. Physical barriers to oil penetration are used primarily for their moisture- or gas-barrier properties, with retarded oil penetration as a secondary benefit. The most common od-repeUent additives are long-chain perfluoroalkyl phosphate salts of ammonia or diethanol amine. Commercial sources include Scotchban (3M), Zonyl (DuPont), and Lodyne (Ciba Specialties). There are also a fluorochemical carboxylate salt, Lodyne (Ciba Specialties), and fluorochemical copolymers, eg, Scotchban (3M). The widest range of oily fluid holdout is provided by the fluorochemical copolymers. 

Layered Structures. Whenever a barrier polymer lacks the necessary mechanical properties for an appHcation or the barrier would be adequate with only a small amount of the more expensive barrier polymer, a multilayer stmcture via coextmsion or lamination is appropriate. Whenever the barrier polymer is difficult to melt process or a particular traditional substrate such as paper or cellophane [9005-81-6] is necessary, a coating either from latex or a solvent is appropriate. A layered stmcture uses the barrier polymer most efficiently since permeation must occur through the barrier polymer and not around the barrier polymer. No short cuts are allowed for a permeant. The barrier properties of these stmctures are described by the permeance which is described in equation 16 where and L are the permeabiUties and thicknesses of the layers. 

This paper describes the physical, chemical, and barrier properties of a new family of high molecular weight copolymers of acrylonitrile and styrene with acrylonitrile functionality in the range of 60-85 weight per-... 

H. Wu, L. T. Drzal, Graphene nanoplatelet paper as a light-weight composite with excellent electrical and thermal conductivity and good gas barrier properties., Carbon, vol. 50,... 

The packaging material is a laminate made from layers of paper, plastic (polyethylene) and aluminium foil. The particular composition for a given product is chosen according to its specific requirements. This affords the best protection to each product and keeps it in peak condition until consumed. Polyethylene is laminated to the board to make it impermeable, and an aluminium foil (of 10 p.m or less) is added to increase the barrier properties against external hazards such as sunlight and atmospheric oxygen, which would cause deterioration of product quality. 

In addition to these applications in the food industry which are first and foremost a result of the improved barrier properties, there are other applications in the consumer sector in which the aesthetic value of products is enhanced by use of metallized films. A typical example is the use of metallized paper for drinks bottles. Numerous brands of bottled beer are promoted by use of metallized paper labels. This design of the bottle primarily serves the purpose of producing an eye-catching effect to capture consumers attention the bottles on the shelf are designed to stand out from other beers and give the impression of a superior and more precious product. This is also the reason for using metallic elements on brochures and promotional materials. 

In packaging, thin PVDC films are used as barrier layers in laminates. PVDC dispersion coatings provide very good barrier properties on paper, regenerated cellulose, OPP and other plastic films. The coatings can also be manufactured so that they are heat sealable. Because of their heat sealability, fat and oil resistance and good flexibility, PVDC polymers are exceptional packaging materials. 

DuPont s Biomax is used in a number of specialty packaging applications, injection-moulded parts, coatings for paper, thermoformed cups and trays, and films because of its superior barrier properties. DuPont has targeted fast-food disposable packaging, as well as yard-waste bags, diaper backing, agricultural film, flowerpots, and bottles, for particular development. 

A common factor of metal foodstuff packaging is that it provides long term ambient stable storage with excellent abuse resistance and protection from environmental contamination ensuring food safety and quality retention with extended shelf life. Flexible packaging which is covered elsewhere in this book may also use thin layers of metal either as discrete foil layers or as metallised plastic or paper layers for improved barrier properties, but the main structural components are non-metallic and so are not covered here. 

Paper has no moisture-resistant properties (unless specially treated), hence no barrier properties against moisture, gases, etc. 

Microcrystalline waxes may be used for barrier properties or as a heat seal. They may be used as either a surface layer or as a total impregnation (paper). Known as wet and dry waxing respectively. 

This paper considers various methods to create a thin diffusion barrier at the surface of a plastic article such as a packaging film or container after it has been given its intended shape. Such an approach permits one to choose the optimum polymer type based on strength, processability, cost, etc. without being constrained by barrier properties. 

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