Polyester films are made from the petroleum substances which are key constituents of polyesters. They find a multitude of uses across various industries owing to their innate properties and advantages. The industries that majorly utilize them are Brazing Foil and the packaging industry. Packaging industry is actually 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 very well what is meant by metallized films generally. Metallized films reference films that are metallized using one end sealable on the other. Metallized films may be made of a number of metals like aluminium, chromium and a mixture of nickel and chromium. Their main uses are packaging in food, pharmaceuticals and the beauty industry. It is 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 to get certain desired properties just like a metallic look, making it resistant to gases, and fewer diffusive regarding aroma and flavor. The other advantageous properties are they can be shrunk with heat application, can be molded into variations according to the need, are printable, sealable and capable of lamination and extrusion also.
All these properties of polyester metallized films make sure they are an ideal option for making aluminium foils used for packaging food items as they must be resistant to outer gases, but simultaneously must retain the aroma and also the flavor from the food.
The filler metal (FM) alloys that may be produced as amorphous brazing foils (ABF) are eutectic compositions formed by transition metals such as nickel, iron, copper, etc., together with metalloids, including silicon, boron and phosphorus. In conventional crystalline state, all of these materials are inherently brittle and can not be created in continuous forms such as foil, wire, etc. Therefore, they were available only as powders, pastes, or their derivates. On the contrary, the very presence of Al Pet Laminated at or near the eutectic concentration promotes the rapid solidification (RS) conversion of such alloys right into a ductile amorphous foil.
The production of amorphous alloys requires a manufacturing technology that operates on the basis of 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 even a long range order. With this particular random, spatially uniform arrangement from the gywlyo atoms, their structure is similar to that relating to liquids. The type of the production process is why amorphous alloys are given only by means of thin, ductile metal foils. Subsequently, tapes, parts and preforms can be made by e.g. slitting, cutting, stamping and etching.
Amorphous brazing foils are compositionally far more uniform despite crystallization, they melt more than a narrow temperature range under transient heating. This can be a consequence of the shorter distances over which atoms of numerous elements need to diffuse to be able to form a uniform liquid phase. The resulting instant melting and their superior flow characteristic is only one from the important features of ABFs. The absence of the residual organic solvent bases evident in powder paste/tapes correspondingly eliminates soot formation and furnace fouling. The low degree of gaseous impurities in ABFs, due to the specific characteristics of its production technology, is surely an attractive feature for vacuum furnace brazing.
UABFs are available as strip with a width from .5 mm to 125 mm along with a thickness from 20 µm to 50 µm. Preforms can be easily made by using punch and die, cutting/slitting, photochemical etching, as well as other methods. It is actually user friendly foils and preforms at automatic production and assembling steps. The use of foils and preforms reduces waste and enhances manufacturing efficiency. Drying and evaporation operations, that are required with powder/paste and tape forms, are not necessary. The perfect quantity of Aluminum Solid Panel can be easily applied to the component and, in only one heating cycle, ABFs create uniform braze joints of outstanding quality.