Anodizing of aluminum parts for cosmetic package containers

Why does aluminum need to be oxidized?

The anodic oxidation of aluminum is an electrochemical method to generate oxide film (AL2O3) on the surface of the product, which changes the surface state and properties, such as surface coloring, enhancing wear resistance and hardness, and protecting the metal surface. The thin layer of oxide film has a large number of columnar honeycomb pore microporous, film microporous adsorption capacity can be colored into a variety of beautiful and bright colors.

Cosmetic aluminum oxidation process:

1, flow chart: aluminum substrates --> punching system --> degreasing and polishing --> anode --> water cleaning --> coloring --> sealing hole --> dryer --> anode products.

2、Related description

Punching: Using molds to make aluminum form into customized shapes.

Degreasing and polishing: remove oil impurities on the surface of processed products and scratches, metal burrs, other impurities on the surface of products, etc., to lay a good foundation for anodic oxidation coloring.

Chemical polishing: It is soaking the workpiece in phosphoric acid-based solution to eliminate mechanical defects on the surface of the workpiece, reduce the surface roughness and improve its surface gloss.

Anodic oxidation: The principle of aluminum anodic oxidation is essentially the principle of water electrolysis. When the current passes, on the cathode, hydrogen is released; on the anode, the oxygen precipitated is not only the molecular state of oxygen, but also includes atomic oxygen and ionic oxygen, which is usually expressed as molecular oxygen in the reaction. The aluminum as the anode is oxidized by the oxygen precipitated on it, forming an anhydrous aluminum oxide film. Not all of the oxygen generated acts with aluminum, and part of it is precipitated in the gaseous form.

After anodic oxidation, before coloring, the oxide film can be activated by acid treatment. All organic/inorganic acids and acid salts can be used as activators, and due to the chemical dissolution of aluminum trioxide by the acid solution, the pore wall of the oxide film pore is dissolved from the outside to the inside, so that the pore size is enlarged, and at the same time, the pore size of the alumina film with different pore size can be obtained by controlling the length of activation time, so as to expand the pore and increase the porosity, thus improve the effect of dye adsorption capacity.

Dyeing: The chemical coloring of aluminum anodic oxide films is based on the ability of the porous film layer to adsorb dyes like textile fibers.

Sealing: Closing the micro-pores of the anodized film and fixing the dye inside the micro-pores is an integral part of the dyeing process. The easiest way to seal the pores is to treat them in boiling water, which, if done properly, ensures that the dyed film exhibits the desired color solidity and also makes the workpiece resistant to grease marks, stains and grease. The anodized surface can only be sealed sufficiently to make it lose its ability to affect the contact material.

At present, our aluminum oxidation products include aluminum-plastic airless bottles, spray perfume tubes, perfume caps, drooper，mascara tubes, cream lids, aluminum-plastic cream bottles, various plastic products and other cosmetic outer packaging series.