Some customers would like to achieve 100% compostable packages for their amazing products, and sometimes, an aluminized layer is needed inside the package to keep the products in original freshness and fragrance as long as possible.
So, metallized paper comes to a top option.
Then follow the question most customers concern about -Is metallized paper fully compostable?
To answer this question, we will have to trace back to the formulation and structure for metallized paper, with graphic shown in the below picture.
structure-of-metallized-paper-graphicPaper, undoubtfully, is compostable, as it is made from fiber plant, which comes to earth, and back to earth.
Clay coating to the paper substrate, which is quite like the white clay applied to the walls, is compatible to earth soil, so it should be considered eco-friendly and compostable.
white-clay-onto-wallThe pre-metalization coating, which works as an adhesion assistant agent, is sometimes chemicals lacquer, with weight 1-2 g per square meter, very subtle to consider.
Aluminum metallized layer, is realized from aluminum wire with purity higher than 99.% and evaporated onto the surface, and it will react with the water moisture and oxygen in natural conditions.
Read here for more understanding.
The top print side primer, is mainly a clear lacquer varnish, which is usually water-type, with thickness about 1-2 gsm, that is quite alike the print inks in the compostable foil laminate.
So, up to now, we can not consider metallized paper as 100% compostable, however 98~99% of its components can be compostable, so usually in commercial use, people take metallized paper as compostable film materials.
Below pictures shows the test of metallized paper buried in nature solid conditions, and see how it degrade in home/garden environments. You may click the picture for more understanding.
To realize compostable foil laminate materials, metallized paper will have to be further laminated with other compostable film material, which would be introduced in future posts. For any questions regarding compostable materials, you are welcome to leave a comment or just reach us at
METALLIZED PAPER &#; TRANSFER METALLIZING A BETTER CHOICE
What is metallizing?
Metallized materials are produced by melting and vaporizing a metal (usually aluminium) in a vacuum while passing a web or paper or film around a chilled roller and over the point of vaporization. The vaporized molecules then collect on the cool web, so providing the paper or film with a metallic finish. It can be carried out by direct metallizing onto the material surface, or by transfer metallizing where the vaporized metal particles are attracted in the vacuum chamber to a very smooth plastic carrier web and then transferred to the chosen substrate under pressure.
Direct Metallizing[DM]
When direct metallizing paper, the paper is first primed to seal the paper surface and give an improved smoothness to the surface, vacuum metallized by the process, described above and then re-moisturised to replace the moisture lost in the vacuum processing and post-coated with a print receptive lacquer.
Transfer Metallizing[TM]
The process has four elements:
- Coating (of a carrier film with a release lacquer)
- Metallizing (onto the release lacquer on the carrier film)
- Laminating (the carrier film with paper)
- Splitting (the carrier film from the metallized paper) &#; with in-line Corona Discharge Treatment.
The lacquer which allowed the separation of the carrier film from the product remains totally on the transfer metallized product, protecting the metal and acting as a print receptive surface. The carrier film, after splitting, becomes available for re-use.
During the splitting process, the lacquer surface (The release lacquer) is Corona Discharge Treated to enhance print receptivity. This treated surface is stable for over 6 months when stored under appropriate conditions.
The process is very difficult to achieve in that one requires 100% adhesion of the lacquer to the carrier film during coating, metallizing and laminating and then 0% at splitting process. Thus the intimate relationship between the lacquer and the carrier film is of prime importance.
Essentially on each substrate is a conversion of about 3 g/m2 of lacquer and 3 g/m2 of adhesive, and the paper does not go into the metallizing chamber (as is the case with direct metallizing).
FORMULATIONS
RELEASE LACQUER
FORMULA - A
Saran Resin F-310 (DOW) = 80 parts
VMCH (DOW) = 20 parts
MEK = 300 parts
If you are looking for more details, kindly visit Herofu.
Coating Thickness ~ preferably 2.5 GSM
Drying Temperature ~ 70 degree centigrade
FORMULA - B
Neocryl B-811(DSM coating resins, Netharlands) = 70 parts
Vinnol H 40/55(Wacker Polymer) = 30 parts
MEK = 210 parts
Ethyl Acetate = 90 parts
Coating Thickness ~ preferably 2.5 GSM
Drying Temperature ~ 70 degree centigrade
LAMINATION
Use Lamination Adhesive, ADCOTE-340 OF DOW OR EPS-71 OF HERBERTS
Coating thickness ~ preferably 2.5 &#; 3.0 GSM
Drying temperature ~ refer manufacturer
SPLITTING
Splitting to be carried out after 72 hours of Aging.
TRANSFER METALLIZING offers several benefits to the end user.
- The process itself is almost self-monitoring as far as defects are concerned. If there is a coating defect during stage one such as a scratch mark etc., the metal will be deposited on the uncoated film at this spot and will not be separated from the carrier film, consequently the final product is defective, but of far more importance, the carrier film will be destroyed making it unusable for further processing. Likewise with the lamination stage, if again there is a defect - no adhesive spot - when the paper is separated from the complex it will not remove the lacquer and metal from this spot &#; again a defective product and an unusable carrier film is the result.
- TM products have the highest reflectivity in that the metallized layer reproduces the very smooth carrier film and not the relatively rough paper underneath, as is the case with DM, where the metal molecules are deposited directly on the rougher substrate.
- In TM, the lacquer which allowed the separation of the carrier film from the product remains totally on the TM product and protects the metal coating and acts as a print receptive surface.
- It is an extremely versatile process in that by only changing the substrate; completely different products can be produced &#; from 46 g/m2 to over 300 g/m2 and also transfer metallized non-paper substrates.
- Any finished product created using Transfer Metallizing, has 6 g/m2 of lacquer and adhesive, making the metallized paper considerably stronger than the original substrate and stronger than direct metallized products as they do not have the layer of adhesive and lacquer.
- Independent research carried out by TNO (NL) studying the recyclability of Transfer Metallized papers and Boards showed that &#;&#; 10% of Transfer Metallized Paper in domestic waste paper has no significant effect on the properties or appearance of the recycled paper products from it.&#; Likewise the PTS study concluded that &#;Transfer Metallized Papers and Boards used in applications such as gift-wrap, laminates and flexible packaging can be part of the normal household waste used paper stream and as such can be collected and recycled.&#;
HOPE THE ARTICLE IS INFORMATIVE!!
THANKS.
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