Polyester films are made of the petroleum substances that 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 use them are Brazing Material as well as the packaging industry. Packaging industry is the major user of these films. Because of 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 talking about metallized version we will understand what is meant by metallized films generally. Metallized films refer to films which can be metallized on one end sealable on the other. Metallized films may be made from 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 really is used to produce 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 experience certain desired properties just like a metallic look, rendering it immune to gases, and fewer diffusive regarding aroma and flavor. Another advantageous properties are that they may be shrunk with heat application, could be molded into variations depending on the requirement, are printable, sealable and able to lamination and extrusion also.
Each one of these properties of polyester metallized films make them an ideal choice for making aluminium foils utilized for packaging food items as they need to be resistant against outer gases, but at the same time need to keep the aroma as well as the flavor in the food.
The filler metal (FM) alloys which can be produced as amorphous brazing foils (ABF) are eutectic compositions formed by transition metals including nickel, iron, copper, etc., in combination with metalloids, such as silicon, boron and phosphorus. In conventional crystalline state, all these materials are inherently brittle and should not be created in continuous forms like foil, wire, etc. Therefore, these were available only as powders, pastes, or their derivates. On the contrary, the presence of Al Pet Laminated at or near the eutectic concentration promotes the rapid solidification (RS) conversion of such alloys into a ductile amorphous foil.
Producing amorphous alloys requires a manufacturing technology that operates on the basis of the necessary cooling rates, which is called rapid solidification, or melt spinning technology. Amorphous structures are described as the absence of a crystal lattice or even 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 nature of the production process is the reason why amorphous alloys are available only in the form 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 much more uniform even though crystallization, they melt spanning a narrow temperature range under transient heating. This is a results of the shorter distances over which atoms of numerous elements have to diffuse to be able to form a uniform liquid phase. The resulting instant melting and their superior flow characteristic is just one in the important attributes 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 an attractive feature for vacuum furnace brazing.
UABFs can be found as strip using a width from .5 mm to 125 mm and a thickness from 20 µm to 50 µm. Preforms can easily be created 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. Using foils and preforms reduces waste and enhances manufacturing efficiency. Drying and evaporation operations, which can be required with powder/paste and tape forms, are not necessary. The ideal amount of Color Painted Aluminum can be easily put on the component and, in only one heating cycle, ABFs create uniform braze joints of outstanding quality.