EVALENE® PHJ4501: Superior Material for Thin-Wall Injection Molding

Thin wall Injection Molding (TWIM) Technology

TWIM Process.  Thin wall injection molding (TWIM) is a recent development in plastics technology, which is a major success due to its being a highly cost-effective process . In TWIM , cycle times are shorter compared to those in conventional injection molding due to thinner parts and are further reduced by addition of performance enhancing additives such as nucleating agents , which raise the temperature at which molten plastic material solidifies. This advancement has prompted new considerations in mold, machinery, and plastic part design. Today, one of the sought-after capabilities for an injection molder is the ability to create smaller, lighter parts which in turn results in product miniaturization and material savings.

TWIM Product Definition.  The TWIM product definition is dynamic: it generally depends upon the application for which it is used. But the main criterion is wall thickness. For packaging containers, “thin wall” means wall thicknesses that are less than 0.025 in (0.62 mm) with a flow length to wall thickness ratio of greater than 200 (Source: Milliken). The definition is not exact as it is used in the industry though, where injection molders will utilize a TWIM material for any article regardless of the definition, as long as cycle time, product performance and desired properties are achieved.

TWIM Materials.  The success of TWIM technology is largely due to the development of molding materials that can be processed at much higher rates. Thus, low viscosity (high melt flow) resins are commonly used in making thin wall products. ABS (Acrylonitrile Butadiene Styrene), PC (Polycarbonate), and PP are examples of such materials. ABS and PC are engineered resins commonly used in portable electronic devices, such as in mobile phone housing. On the other hand, makers of food packaging containers such as “microwavables” use PP. PET (Polyethylene terephthalate) and PS (Polystyrene) are also popular in food packaging. PP is strongly favored in TWIM application due its strength, capability for higher hot-fill temperatures (vs. PET), lower density (lightweight), recyclability and cost efficiency.

EVALENE PHJ4501: PP TWIM Material

Applications.  Articles that can be made from EVALENEsPHJ4501 grade include food and deli containers and lids, microwavable containers, drink cups, party plates and document cases; lightweight houseware and containers, pen barrels, storage containers, and packaging (e.g. for dry goods, socks, handkerchiefs, underwear). Thicker-walled containers, such as easy-cook noodle cups designed for exposure to hot water, can also be made using this PP TWIM grade.

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