Browse Publications Technical Papers 2000-01-1127

Flow Mark Reduction of Metallic Colored PP 2000-01-1127

Blending polypropylene (PP) with materials such as rubber or filler creates compound PP, which is widely used in auto parts because of its balanced physical properties, formability, and cost performance. Recently non-painting of parts, namely coloring the raw materials, is being investigated as a method of reducing the cost of exterior parts which have conventionally been painted to match body colors, which are mostly metallic now. However flow marks often form in long injection molded parts such as the side protection molding, causing remarkable decreases in exterior appearance quality. This research investigates the influence of metallic coloring of PP material (blending PP and metallic pigment) factors on flow marks, as well as countermeasures for those causes of flow marks. PP and metallic pigment characteristics were the factors investigated to evaluate flow mark level. As a result, flow marks are less likely to occur when PP has low melt viscosity and wide molecular weight distribution, and when the metallic pigment has small mean particle diameter and low concentration. Based on the results of this research, we were able to manufacture a non-painted metallic color side protection molding, thus lowering costs, improving environmental conservation (reducing volatile organic compounds (VOC) and recycling), and better protecting door surfaces from scratches.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 17% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Thermoplastic Elastomer Classification System


View Details


Test Procedure to Measure the Fuel Permeability of Materials by the Cup Weight Loss Method


View Details


Recycling Study of Post-Consumer Radiator End Caps


View Details