Coextrusion technology

Approximately 252 million dollars in counterfeit U.S. currency is recovered each year. While this is a small percentage of the 540 billion U.S. dollars that are assumed to circulate worldwide, there is clearly a need for more sophisticated security features. A possible solution is to use multilayer coextrusion technology to create an optical polymer substrate for U.S. currency. 

Multilayer coextrusion technology is used to create an optical polymer substrate for U.S. currency. The final product specifications of the optical currency are listed below ... 

Coextrusion Technology, November 27-30, 1995, Amsterdam Course Director C.R. Finch, C40. 

Another consideration for the scale of a process is batch versus continuous. Batch processes limit production to the size and number of batches that can be produced in a given amount of time. Continuous production allows for uninterrupted operation, with the production rate controlled by the throughput of the equipment. The atomization and coextrusion technologies are the most common continuous encapsulation processes. Spray-coating processes are available as both batch and continuous. The emulsion-based processes are limited to batch processing, which is the basis for their increased operating costs over most of the physical processes. 

Blow molded parts demonstrate that, from technical and cost standpoints, BM offers a promising alternative to other processes, particularly injection molding (IM) and thermoforming. The technical evolution of BM, plus accompanying improvements and new developments in plastics, has led to new BM parts. With the coextrusion technology now established and the hardware in place, the variety of achievable properties can readily be extended by the correct combination of different materials (see Chapter 3). The potential for BM products includes much more than the simple bottles that have been made for many decades. Now the expertise and economics of the method are such that many ideas once deemed futuristic are much closer to realization (2, 96, 186-212). 

Application. Typical application areas that exploit the properties of polyester film are illustrated in Table 6. It can be seen that usually a combination of properties are required and these are achieved by a combination of base film properties, fillers, coatings, and coextrusion technologies. 

A special application of the coextrusion technique is the production of polymeric foamed materials with a high strength-to-weight ratio and good acoustic and thermal insulation. Control of the foam cell size is very critical in obtaining these key performance properties. The control of cell size in the thin layers by the microlayer coextrusion technology makes the creation of microcellular foam possible [8]. 

Coextrusion. Coextrusion technology has been developed in conjunction with new polymers, providing continuously formed layered polymer structures such as the film structures required for flexible packaging. Coextrusion is perhaps the most economical method of combining polymers into functional multilayer products such as films, sheets, profiles, bottles, pipes, and wire coatings. 

Multilayered films can be formed by various processes to create a structure with specific mechanical and physical properties. Microlayers of foam/film were formed by microlayer coextrusion technology [176], resulting in unique mechanical properties studied by optical microscopy. Cohen et al. [177] studied... 

Layer multiplying coextrusion technology was used to produce multilayered ultrathin films of PP containing p-nucleating agents and PS by forced assembly.When these... 

The goal of this research is to create PP nanocomposite noatmals using multilayer coextrusion technology. These multilayers will then be sq arated into distinct, individual layers and material and thermal properties for each layer will be measured. These results, along with TEM micrographs, will allow us to assess the effectiveness of qjplying shear stress in a slit die to achieve dispersion in PP nanocomposites. 

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