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 make use of them are Aluminum Brazing Foil and the packaging industry. Packaging industry happens to be 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 allow us to understand what is meant by metallized films in general. Metallized films refer to films which can be metallized on a single end sealable on the other. Metallized films may be made from many different metals like aluminium, chromium and a combination of nickel and chromium. Their main uses are packaging in food, pharmaceuticals as well as the beauty industry. It really is used to produce a various forms of wraps like foils, sheets and scarps. The 2 kinds 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, which makes it immune to gases, and less diffusive with regards to aroma and flavor. One other advantageous properties are that they can be shrunk with heat application, may be molded into different forms as per the necessity, are printable, sealable and capable of lamination and extrusion also.
All these properties of polyester metallized films get them to the perfect option for making aluminium foils employed for packaging food items as they should be immune to outer gases, but concurrently need to support the aroma and the flavor of the food.
The filler metal (FM) alloys that can be produced as amorphous brazing foils (ABF) are eutectic compositions formed by transition metals including nickel, iron, copper, etc., in conjunction with metalloids, such as silicon, boron and phosphorus. In conventional crystalline state, all these materials are inherently brittle and should not be produced in continuous forms like foil, wire, etc. Therefore, these people were available only as powders, pastes, or their derivates. On the other hand, the particular presence of Lamination Foil at or close to the eutectic concentration promotes the rapid solidification (RS) conversion of the alloys in to a ductile amorphous foil.
The creation of amorphous alloys demands a manufacturing technology that operates on the basis in the necessary cooling rates, which is called rapid solidification, or melt spinning technology. Amorphous structures are characterized by the lack of a crystal lattice or even a long range order. Using this random, spatially uniform arrangement from the gywlyo atoms, their structure is comparable to that of liquids. The type of the production process is why amorphous alloys are available 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 far more uniform despite crystallization, they melt over a narrow temperature range under transient heating. It is a results of the shorter distances over which atoms of numerous elements have to diffuse in order to form a uniform liquid phase. The resulting instant melting as well as their superior flow characteristic is only one in 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 reduced degree of gaseous impurities in ABFs, due to the specific characteristics of their production technology, is definitely an attractive feature for vacuum furnace brazing.
UABFs are available as strip having a width from .5 mm to 125 mm along with a thickness from 20 µm to 50 µm. Preforms can be simply produced by using punch and die, cutting/slitting, photochemical etching, and 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, that are required with powder/paste and tape forms, are not necessary. The ideal level of Color Painted Aluminum can be simply applied to the component and, in just one heating cycle, ABFs create uniform braze joints of outstanding quality.