Shrink packing, wrapping

Siace a large part of the beer market is take-home beer, brewers must provide retailers with packs that are easily handled and stored. Clear shrink wrappiag has become a dominant feature because it permits the content of the pack to be seen. Other packagiag methods are Shrink Wrapped 2 dozea Tray Pack, Cardboard Sleeve, Hi Coae 3 Pack, Hi Coae 6 Pack ia Tray, and Top CHp Bottle Pack (see Packaging materials). 

Further, they can be used for medical purposes, such as press-through packages, disposable syringes, liquid medicine vials, and infusion bags. They are suitable for electric or electronic materials, such as wire coating. In addition, packaging films, such as wrapping films, stretch films, shrink films, and blister packs can be produced. 

Protecting the can from the effect of corrosion is very important in order to achieve the very long shelf life that metal cans offer. Discussion with the can manufacturer will ensure the use of the appropriate grades of lacquers on the internal surfaces to prevent primary corrosion. The external surfaces must also be considered in order to prevent secondary corrosion, which will result in leakage. Handling on the filling line must ensure the smooth flow of cans and eliminate any sharp objects that may scratch or pierce them. A lot of moisture is present on the line because of the use of conveyor lubricants or from the pasteuriser, and it is important that cans are dried before being packed, particularly if they are to be shrink-wrapped. Cold cans, below the dew point, must be wanned to ambient temperature or else they will become wet when packed. 

Metal, composite, or plastic containers received on unitized pallets are usually packed with a shrink or stretch wrap shroud to maintain integrity of the load. Manual or automated depalletizers are available that orient the cans onto single-lane conveyors. The cans are inverted for cleaning and enter the filler. Filling is accomplished by timed flow or piston-type, volumetric action fillers. The end or side of... 

Patient-ready packs are allowed for supply to state institutions (or to permit holders in the private sector) only. Patient-ready pack immediate containers should be at lecist of the same quality as the standmd origincil container or conform to the specification of the latest edition of the USP for tight containers in respect of light transmission and vapour permeability. The outer containers should be over wrapped or shrink wrapped in low density polyethylene film of at lecist 60 micrometers. Unless otherwise proven, a maximum shelf life of 15 months which must be within the shelf life, commencing from the date of packaging, is permitted (MCC Circulars 6/92, 3/93 and 13/93). 

However, fibreboard has been criticised because of loose fibres. Baler bags received favourable publicity a few years ago but found rather limited use against the more competitive shrink wrapping systems. Shrink wraps as sleeves or overwraps may be used around complete pallet loads or small unit quantities. In the case of wrapped pallet loads the bottles may be separated with layer pads. On smaller quantities, bottles may be trayed or left without additional support (i.e. direct shrink wrap). Again the pallet may have a full shrink wrap to give added security and protection, and this is now the preferred method of packing. 

Outer or transit packaging can occasionally contribute to changes in the primary pack or the product. External wrapping materials may contain various migratory constituents, e.g. when a shrink or stretch film is in intimate contact with a primary pack or plastic components of a device. Odorous board, adhesives, printing inks on external packaging have also been known to cause flavour and/or odour changes. 

Polyethylene, as LDPE, LLDPE or a mixture or blend involving combinations of LDPE, MDPE, HDPE, EVA, etc., finds a wide usage in bags, sacks, sachets, overwraps, shrink wraps, stretch wraps, etc. Most deep freeze packs, for example, use LDPE or an LDPE mixture which is produced from a reel on a form fill seal type machine. However, as many of these packs are up to 100% printed, even ink of 2-5 Pm could be considered as a separate layer which modifies some of the physical and chemical properties. As all polyolefins need a surface (oxidative) treatment to ensure a good print key, this or any other surface treatment process may further modify the film properties. 

This may involve the collation of packages of similar or variable shapes. The most popular form uses either a direct shrink wrap (e.g. multi-packs) or a shallow tray which is usually made from corrugated board or solid board. Thermoformed plastic trays with a formed base (and/or a lid/cover) are also widely employed (e.g. bottles and aerosols). These systems offer restriction to pilferage and due to the see-through nature of the film may avoid the need for external labels. (Internal labels may be necessary if stock is controlled via a bar code.) Although LDPE has the major use, PVC may occasionally be used for its higher clarity. Gauges of 25 to 100 m are usually employed. 

Sometimes a two-part cover is used where the inner section serves as an actuator and the outer section is rigid and performs the usual function of a cover in preventing accidental spraying by top pressure. The capped and labelled aerosols are then either packed into outers with or without divisions, or shrink wrapped. 

The whole stack should be shrink-wrapped in plastic as tightly as possible to minimize any movement during transit. When storing the packed batteries prior to transportation or shipment, the layers of pallets should not be stacked more than two high. As a further precaution, the guidelines recommend that ULAB be transported in a sealed, shock-resistant container that will not leak electrolyte. 

Monolithic columns are another approach to provide lower pressure drops and higher rates of mass transfer. These are continuous solid columns of porous silica stationary phase instead of packed particles. Like perfusion packings, they have a bimodal pore structure (Figure 21.7). Macropores, which act as flowthrough pores, are about 2 fim in diameter. The silica skeleton contains mesopores with diameters of about 13 nm (130 A). It can be surface modified with stationary phases like Cig. The rod is shrink-wrapped in a polyetheretherketone (PEEK) plastic holder to prevent waU effects of solution flowing along the walls. The surface area of the mesopores is about 300 mVg, and the total porosity is 80%, compared with 65% for packed particles. The colunm exhibits a van Deemter curve approximating... 

Pallets of bagged hydrate have been stored successfully out-of-doors. The pallet is covered by a plastic sheet, the bags placed on the sheet and the pack shrink-wrapped. Such pallets should be moved into a covered store before unloading. 

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The blowing agent is usually chemically stable, volatile, and so its introduction into the molten polymer reduces the foam product density, by forming a myriad of closed cells. The foam is then trimmed to desired shape. The Foam Boards are packed into shrink-wrapped bundles on the pallets. And then these pallets are stored for curing during a certain period, until shipment. ... 

Styrene-butadiene copolymers are used in toys, housewares, and medical applications.Thermoformed products include disposable food packaging such as cups, bowls, clam shells, deli containers, and lids. Bhster packs and other display packaging also use styrene-butadiene copolymers. Other packaging apphcations include shrink wrap and vegetable wrap. ... 

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Besides forming strong and conveniently storable and stackable unit loads, palletless shrink-wrapping has the advantage that the cement can be packed in ordinary two-ply paper sacks, whereas otherwise cement intended for shipment overseas usually has to be packed in five- or six-ply sacks. 

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