Polyester films are made from the petroleum substances that are key constituents of polyesters. They find numerous uses across various industries owing to their innate properties and advantages. The industries that majorly utilize them are Brazing Material and the packaging industry. Packaging industry happens to be the major user of these films. Due to their multiple properties of, attractive appearance, strong oxygen barrier, brilliant printing and sealing capabilities and machinability, they are preferred films for food products packaging.
Before referring to metallized version let us know what is meant by metallized films generally. Metallized films make reference to films which are metallized on one end sealable on the other. Metallized films could be made of many different metals like aluminium, chromium and a mix of nickel and chromium. Their main uses are packaging in food, pharmaceuticals as well as the beauty industry. It is actually used to make a various forms of wraps like foils, sheets and scarps. The two types of metallized films are metallized polypropylene films and metallized polyester films.
Metallized polyester films are metallized under high vacuum condition in order to achieve certain desired properties like a metallic look, making it resistant against gases, and fewer diffusive with respect to aroma and flavor. One other advantageous properties are they can be shrunk with heat application, could be molded into different forms as per the need, are printable, sealable and capable of lamination and extrusion also.
Each one of these properties of polyester metallized films make sure they are the ideal option for making aluminium foils employed for packaging food items as they need to be resistant to outer gases, but simultaneously have to support the aroma and also the flavor of the food.
The filler metal (FM) alloys which can be produced as amorphous brazing foils (ABF) are eutectic compositions formed by transition metals like nickel, iron, copper, etc., in combination with metalloids, including silicon, boron and phosphorus. In conventional crystalline state, all these materials are inherently brittle and cannot be created in continuous forms such as foil, wire, etc. Therefore, they were available only as powders, pastes, or their derivates. On the other hand, the very presence of Pet Laminated Aluminium at or close to the eutectic concentration promotes the rapid solidification (RS) conversion of the alloys right into a ductile amorphous foil.
The production of amorphous alloys requires a manufacturing technology that operates on the basis from the necessary cooling rates, which is known as rapid solidification, or melt spinning technology. Amorphous structures are characterized by the absence of a crystal lattice or perhaps a long range order. With this particular random, spatially uniform arrangement in the gywlyo atoms, their structure is a lot like that of liquids. The character of this production process is why amorphous alloys are given only as thin, ductile metal foils. Subsequently, tapes, parts and preforms can be produced by e.g. slitting, cutting, stamping and etching.
Amorphous brazing foils are compositionally much more uniform even after crystallization, they melt spanning a narrow temperature range under transient heating. This is a consequence of the shorter distances over which atoms of numerous elements must diffuse to be able to form a uniform liquid phase. The resulting instant melting and their superior flow characteristic is just one from the important highlights of ABFs. The lack of the residual organic solvent bases evident in powder paste/tapes correspondingly eliminates soot formation and furnace fouling. The low amount of gaseous impurities in ABFs, as a result of specific characteristics of the production technology, is surely an attractive feature for vacuum furnace brazing.
UABFs are available as strip using a width from .5 mm to 125 mm along with a thickness from 20 µm to 50 µm. Preforms can be easily created by using punch and die, cutting/slitting, photochemical etching, and other methods. It is user friendly foils and preforms at automatic production and assembling steps. The usage of foils and preforms reduces waste and enhances manufacturing efficiency. Drying and evaporation operations, that are required with powder/paste and tape forms, usually are not necessary. The optimal level of Color Painted Aluminum can be simply placed on the component and, in only one heating cycle, ABFs create uniform braze joints of outstanding quality.