The main factors influencing the barrier property aluminized film quality

Barrier property aluminum plating film quality index, thin film, is the most important barrier property. Many factors influencing the barrier property of aluminum plating film, one of the most main is aluminized layer of density, the thickness of the aluminized layer and the combination of aluminized layer and plastic film between the fastness, etc. , the influence factors can be summarized as two aspects of quality equipment and basement membrane. Main equipment factors affecting the quality of plastic film aluminum plating is the vacuum evaporation chamber. A high level of equipment is the foundation, to obtain high separation aluminized film without a high level of coating equipment, is impossible to produce high quality aluminum plating type barrier films. In general, the higher the degree of vacuum, aluminum plating film evaporation effect better, coating layer density increased, barrier property is improved significantly, so in choosing a forging membrane equipment, shall be of aluminium coated vacuum degree of vacuum chamber to special attention. The barrier property in the production of aluminum plating film, often encounter the most evaporation film on the quality of the evaporated film, so in a lot of literature on this aspect of the content are discussed. High quality aluminum plating film, aluminum plating layer on the membrane surface, must be securely attached, so to improve the effect of thin film of aluminum plating, requires enhanced aluminized layer and film surface adhesion between the fastness. Here attached mechanism, BOPET film surface structure performance and influencing factors of such aspects as were introduced briefly. Adhesion mechanism: plastic film has good chemical stability, generally lack of surface active group, so usually difficult to react with aluminum layer, to generate chemical bond, aluminized layer and combination between the plastic film, usually through intermolecular interactions, so on the discussion of aluminized layer between the basal membrane and the combination of fastness, need to start with understanding the role of the intermolecular. It is well known that the intermolecular forces, such as van der Waals force and hydrogen bond. Van der Waals force including orientation, induction force and the dispersion forces, the orientation force is permanent dipole moment polar molecules produced by electrostatic interaction of appeal, and its effect to the highest, 1. 2X104〜2. 1X104J/md; Induction force is polar molecules in other polar and nonpolar molecules interact and produce force, its action for 0. 6 x104 ~ 1。 2X104J/mol； Dispersion force is the 'instantaneous dipole moment' molecules interact to produce force, common lies between non-polar molecules, polar molecules and between polar and non-polar molecules, but the dispersion force is weak, small molecules dispersion effect can generally is 0. 8 x103 - 8. 4X103J/mol; Hydrogen bonding is the hydrogen molecules (AH) and molecules of the adjacent atom B formed by the intermolecular weak chemical bond, the key for 2. IX104- 4. 2 x104j/mol, hydrogen bond than chemical bond energy is smaller, but much bigger than the ordinary van der Waals force. To improve the plastic film and the combination of the aluminized layer between the fastness, should as far as possible increases the surface of the plastic film and the polarity of the aluminized layer, increase the proportion of their orientation in the interaction force. Although the aluminized layer is, however, has the very high surface energy of the polar material, but the surface of the plastic film is generally polarity ( Or low polarity) , even if has certain polarity ( Such as BOPET, BOPA plastic film) , its polarity is low, the plastic film ( Wrong polarity of plastic film) And aluminum layer between the combination of a lack of role can force strong orientation, and rely mainly on weaker induction force and the dispersion force, so they are adhesion between the fastness is quite low. Simple narrative, it is not hard to see from the above, to enhance the adhesion of molecules, select the appropriate plastic film, or through the surface treatment of plastic film, make its surface molecules with strong polarity and hydrogen containing functional groups, make the surface of the plastic film and aluminum plating layer may through larger orientation between force and hydrogen bonding, will greatly improve the combine fastness of aluminum layer plating. In addition to the role of the intermolecular, aluminized layer and plastic mechanical action between the surface ( Mechanical anchor meet) Is aluminized layer and plastic film between the combination of an important factor. The smooth surface of the plastic film and aluminum plating layer adhesion fastness is not good, because the contact area between them is relatively small, and lack the necessary mechanical anchoring effect. If proper handling of the thin film surface, has a certain roughness, on the one hand can increase and effective joint surface film on the surface of the aluminum layer; At the same time can also make the vacuum aluminum plating condensation aluminium, local into the plastic film is rough on the surface of the sag and the micropore, evaporation aluminum mechanical embedded in the pore, form tiny mechanical join points, will be firmly 'anchor' aluminum layer on the membrane surface, thus significantly enhanced aluminized layer and the combination of the plastic film between the fastness, plastic surface roughness, of course, need to keep within a moderate range, if mishandled, plastic film surface is too rough, often lead to aluminum plating can't completely fill the disadvantages of microporous, prompting adhesion defect, make aluminized layer on the surface of the plastic film, adhesion is reduced.