Thermoform coextruded sheets

Also popular is the use of thermoforming coextruded sheets or films (Figs. 8-51 and 52). 

When thermoforming coextruded sheets, the thickness and the viscosity of the upper layer in relation to the pigment particle size and its thickness influence the surface appearance. Of course, the degree of elongation and tight bends are critical. 

Thermoformed chassis and body panels are featured on the car. The products were made initially in the USA for assembly in China. The car will weigh less than 2000 lb (900 kg). Automotive Design Composites, Inc of San Antonio, TX, designed the vehicle to have body panels and trunk formed from coextruded sheet of ABS with an ASA cap layer that will hang on a pultruded composite frame. Ceramic tooling is used to thermoform plastic products. 

Thermoformed (Coextruded Plug-Assisted Twin-Sheet) Fuel Tanks Show Promise, MP, Apr. 2000. 

Figure 11. Coextruded sheet and container formed via scrapless thermoforming process.

Figure 7-71. The bonding of two thermoformed parts from coextruded sheets here resulted in a fuel tank. The tank s inside has a nylon surface to resist gasoline the outside uses PP to provide a combination of low cost and the required support strength.

Figure 7-72. A coextruded sheet for the production of a three-color thermoformed container with an integrally hinged lid.

Figure 7-73. The addition of a single-plastic clamping strip at each side of a coextruded sheet permits scrap reclaim of the thermoformed trim waste.

Eilms (0.2 to 1 mm) and sheets (2 to 5 mm) are coextruded. Coextruded sheets consisting of multilayers are thermoformed and inserted into an injection mold. This process is also referred to as overmolding. It is well established for automotive interiors. There are a number of promising developments for exterior applications. It is applicable for simple geometry parts with large surface area. See Figures 2 (1) and 3 (7). 

It is briefly reported that PP foam sheet from Convenience Food Systems in thickness from 500 to 1800 micron is thermoformable into chilled food packaging trays. Trays made in TiroPak XPP, which is coextruded with an EVOH barrier layer, can be taken from the freezer and heated to 90C in a microwave oven without loss of shape or properties. 

Food packaging is a significant area of demand for SBC. Its ease of processability allows it to be used in barrier co-extruded structures. It can be coextruded using adhesive layers with EVOH or PVDC to produce a sheet structure that is readily thermoformed into containers for aseptic food packaging. The high barrier and excellent clarity make it ideal for showcasing packaged products [10]. 

Various types of multilayer dies, such as the TRD, have successfully produced coextruded LCP-thermoplastic film, sheet, and thermoformed articles. These products are expected to penetrate the high barrier plastics market valued at more than 700 million per year for a variety of food, beverage, medical, and industrial packaging applications. Because of their very low permeability to oxygen and water vapor combined with high temperature and chemical resistance, coextruded LCP films should find applications in this market. The process for coextruded LCP thermoplastic multilayers overcomes the key problems previously limiting LCP coextrusion ... 

Since PVC is a thermoplastic, it can be recycled using technology that is comparable to that of the other regularly recycled commodity materials. By far, more postindustrial PVC is recycled than postconsumer due to the durability of PVC applications. Depending on the application, recycled PVC can be used as a raw material in the same application, as a layer in a coextruded part, or as a raw material for an entirely different application. Thermoform scrap can be reused in new sheet wire scrap becomes garden hose window lineal cut-offs become pipe siding scrap becomes the base layer laminated with an appearance film. Pipe goes back into more pipe. 

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