One of our clients from the Central Asian region approached us with a request to provide technological and technical assistance in the implementation of a one project.
Due to the annual increase in logistics costs, the company was no longer able to purchase high-quality foil and metallized BOPP film from the European Union. Since the company was very focused on the production of polyethylene (EPE) and polypropylene (EPP) foam insulation with metallized BOPP film sheet lamination, it was imperative to find alternative materials and the only one supply option was China. The main problem was that the thickness of the cast polymer layer of BOPP film and aluminum foil was 2.5 times thinner than before. Chinese suppliers simply did not want to produce material exclusively for our customer's needs, since the volumes were not enough.
Challenges
In this regard, our client asked us for support in developing new technological processes associated with the production of laminated thermal insulation from polyethylene and polypropylene foam in order to minimize the risks of foil and metallized film peeling off polymer foam after lamination.
We understood that simply changing lamination technological parameters would not help in this situation, since the problem lies solely in the quality and characteristics of the foil and metallized film used.
Analysis
It was decided to work on increasing the adhesion of foam to foil and metallized film, as well as slightly change the recipe of the raw materials of the extrusion process in order to increase the gas permeability of the foam polymer and reduce the amount of residual gas in the cells of the foam polymer during the lamination process.
Firstly, we conducted an audit of technological processes, the raw materials and additives used.
The actual degassing period of the material was determined by observing changes in weight, density, and expansion of the material over several weeks at various temperatures and other conditions.
It has also been established that the quality department does not pay attention to the actual time of degassing of finished products and semifinished products and that EPE and EPP foam are often used before the actual time of replacement of gas with air, which also affects the formation of defects during lamination, since there is a large amount of residual gas during the heating process, expands between layers and prevents adhesion between films and foam.
Another feature of this project was revealed, that the customer could not afford to increase the current degassing period of foam materials due to limited storage space.
Solutions & Actions
We drew up a plan for modifying the recipe with calculations of costs. It was planned to replace the standard GMS lubricant with another sliding additive in order to increase gas permeability and reduce the degassing time to no more than 10 days. It was also decided to introduce a polar copolymer of ethylene and butyl acrylate into the formulation of foamed polymers to increase the adhesion of foam materials when heated during the lamination process.
FAP teams completely took over the process of searching for suppliers of raw materials, carried out a regulated process of testing and introducing new types of raw materials into the recipe. Training materials were also prepared in the form of presentations for operators, technicians and the quality department managers, which contained detailed theoretical material on the foaming process and the influence of existing and new types of raw materials on the process. A meeting and training of all personnel was organized for 1 working day with production stopped.
Results
By introducing new raw materials into the recipe, it was possible to bring the degassing period of foam closer to 11 days, which satisfied the customer.
In addition, the introduction of a polar copolymer increased the adhesion of foam during lamination, since the initial melting temperature of the copolymer is 12 degrees lower than the melting temperature of low-density polyethylene.
Incorporating a small percentage of this material into the formulation created a more sticky layer on the surface of the foam when heated, but the production cost of the foam polymer increased slightly. Because the film's polymer coating layer was thinner, the current cost of purchasing metallized BOPP film and aluminum foil was significantly lower than before, about 40%, making the final product more economical despite the formulation changes.