How to Choose Different Layer?

The meeting of mechanical requirements is the first step in ensuring that a package successfully contains a product. Thus, the material must attain adequate strength to hold the load. Power is determined by four properties: tensile strength – the resistance to breaking when pulled slowly; the impact of power that offers resistance to breakage under the immediate effect; the opposition to piercing by sharp materials; and the resistance to tear from a point of puncture.
Consequently, the mechanical property of a packaging material must resist both chemical and physical attack from both the product within and the external conditions. Thus, the effects occur from the contents of the package. Chemical attacks from products within the package are typically oils, fats, acids, grease, and caustic fluids. Depending on their resistance to these agents plastics change in their properties whilst others remain inert. The sharp edges of products in a packages is also a challenge affecting the choice of hardware substances for some edible products.

Dispensing is the need to access the contents of a package after initially opening it. Plastic films easily satisfy this approach provided the consumer has a pair of scissors or a knife although current trends are moving to attain a more accessible mode of opening the packages without the tools. Consumers also wish to re-close the packaging as a way of conserving the unconsumed product.
Plastics are often ineffective in performing these stated functions. Package seals are required to resist the penetration of water vapor and oxygen and still must concur with the ease of the package opening. Plastic films also fail to ensure the closing of a package after being opened as heat was required to recreate the original seal. Some plastic bags contain zipper-like systems for closure/sealing the package however the zippers are not airtight. Therefore, the product must endure the package or add an additional airtight seal that implies a lot of cost. In most cases, rigid containers with screw caps are better suited than plastic films.

Dirt and Dust
Plastics easily meet this technique/criteria of protecting products from dirt and dust. However, some plastics that conduct electricity poorly contain minor electric charges that attract dust. Improving these films by offering treatment or selecting alternative plastic films that are highly conductive can answer/solve this issue.
Atmospheric Gases
The choice of permeability depends on the nature of the product and the desires of the manufacturer. High permeability facilitates additional advantages like gaining desirable properties at lower costs. The use of multi-layer films is most evident amongst manufacturers. One film offers gas penetrability and the others heat scalability, strength, and opacity. P?V?D?C/(PVDC) materials provide both protection from the atmosphere and scalability of heat. Layers made of metal provide beautification and act as barriers against gases. Thecomplexity that arises in designing multi-layer packages is associated with the different needs of packagers. The protection against gas can almost always be attained by using the best plastic resin. “Almost always” is applicable because high barrier film packages made of plastic have not been considered an option for certain foods. Examples include soups and vegetables, commonly known as “shelf-stables.” The edibles require processing and canning and can stay on the shelf for many years without refrigeration.
Oxygen barriers used in this case are composed of plastic lined aluminum or PVDC, developed years previously. The barrier film required in Modified Atmosphere Packaging should prevent the re-entry of oxygen. As a result, materials like nylon, coated film, and PVDC are used. To meet this requirement, obstruction polymers such as EVOH and PVDC become incorporated. Selective permeability to gases reaches consideration by the use of Controlled Atmosphere Packaging.
Respiration is accessible to fresh produce, increasing their shelf-life. Therefore, with the appropriate combination of plastic films, the requirement is achieved. In the future, the popularity of multi-layer plastic films becoming engineered will increase motivated by the reduction of product spoilage and natural product convenience.

Odor/ Flavor Loss or Gain
Preventing the loss of desirable characteristics or the acquisition of undesirable flavours from the surrounding is attained by the use of multi-layer plastic films to protect against oxygen and water vapor. Seldom is the designer of the package tasked with incorporating a singular plastic to perform the role.
Light
Pigmentation and metallization of plastic films occur to enhance their opacity. One advantage is that metalized coatings provide Ultraviolet screening as well as any level of opacity required by the product by contrast with naturally opaque materials which are unable to be adjusted. Partial opacity can offer some products with adequate light protection together with attractive aesthetic effects.
Extremes of Temperature
Plastic packaging films remain effective when subjected to temperatures in the refrigerator and therefore do not require consideration by package designers.
However the upper temperature for packaging food is at 400℉, where PET and nylon remain stable and able to withstand the temperature, maintaining their mechanical assets without releasing chemicals into the packaged contents.

When providing the fundamental purposes for packaging products, plastic films should meet various requirements that depend on the marketing strategy of the packager. Some policies include the consideration of how printing inks are accepted by the film and their treatment to prevent the ink from being rubbed off. Multilayer films avoid abrasion by allowing the converter??? to print one of the inner surfaces. Dyes and pigments should not damage plastic resins although surface printing can be applied instead of pigmentation. Concealment and display can be created using opaque materials. Other important applicable properties include haze, gloss, and the percentage of light transmission. Mist is applied through the scattering of light to improve the visibility of the printing.
Gloss allows mirror-like reflection leading to a sparkling appearance. Seemingly, percent light rationalizes transmission and interposition between receptors when the film lacks. Optical and visual characteristics influence the appearance of a product on the shelf while the resistance and stiffness impose on the appearance of the product after handling by the customer. Requirements vary among-st packages.

Some plastics rarely resist oil and while others are attacked by chemicals. The use of the right film improves the workability of the vinyl, necessary for packaging. The extraction of non-food and non-drug packages only occurs if the products are liquid. In the case of food, the safety of the consumer is a major consideration.
Therefore, specifications are required following the use of resins so that the bits of polymerization or catalyst products are prevented from entering into the edibles. Products are kept at low temperatures to prevent taste alteration and harm to the consumers. The original tastes/flavors of certain food products can become altered through changes in their trace components. For example, the flavor of orange juice changes after the removal of the “fresh notes.” Polyolefin removes the juice components which lead to the use of expensive polymers to maintain a fresh taste. The polymers act as the contact layer in plastic juice containers.