Improving scratch resistance and reducing weight at similar stiffness with Gloxil SF 91 A in a PP copolymer

Composites have long become standard in industry. Also in the fillers sector, they are already present in some cases, but often only as highly customized products individually tailored for one single customer. HOFFMANN MINERAL is now launching its first hybrid filler with Gloxil SF 91 A. Applications for the mixture of fibre and Neuburg Siliceous Earth with amino functionality lie in the field of thermoplastics, e.g. in 3D printing. The Gloxil SF 91 A excels in particular in applications where it is required to achieve rigidity, toughness, scratch resistance and good processing of the compound.

The product at a glance

Gloxil SF 91 A is a functional hybrid filler based on Silfit Z 91, in which the surface has been modified with a special amino functional group. The process parameters have been selected in such a way that on the one hand, anchoring to the surface takes place and on the other hand, released by-products are removed as far as possible during production. Undesirable side effects, such as occur during mixing in situ (i.e. direct addition of the additive), are therefore significantly reduced. Gloxil SF 91 A is used wherever increased stiffness and heat resistance, high surface quality and scratch resistance are just as important as good melt flowability, relatively high elongation at break and impact strength. 

Technical study of Gloxil SF 91 A in PP copolymer compounds

In PP copolymer compounds, Gloxil SF 91 A achieves the best results when maleic anhydride grafted polypropylene PP-g-MAH (PP-MAH) is added as a reactant for the amino groups of Gloxil SF 91 A, resulting in improved tensile and flexural strength and, above all, optimum scratch resistance. The stronger increase in stiffness can be utilized for weight-reduced compounds due to a lower filler loading. Here, e.g., 11% Gloxil SF 91 A in PP copolymer provides stiffness similar to 20% talc and thus enable a weight reduction of up to 7%.

Results

By replacing the ultrafine premium talc (20%) with Gloxil SF 91 A (11%) and by adding PP-MAH (1%) for a better incorporation of the modified filler, the compound density could be reduced by 6.7%. Furthermore, the scratch resistance of the final product could be significantly improved for K09 (coarse) and K31 (fine) compared to the talc. Here, the results were observed triple as good with the Gloxil SF 91 A. Also the Charpy impact strength and the heat deflection temperature (HDT/A) could be improved by retaining similar stiffness.

Next to that, as illustrated in the diagram with overall results, also the yield stress could be improved. However, in comparison the talc performs slightly better in properties as notched impact strength and tensile modulus, which would be potential minor offsets by using Gloxil SF 91 A instead of talc. Nevertheless, with the Gloxil SF 91 A it is possible to boost the compound in specific flexibility properties at similar stiffness not provided by the talc.

General summary

Gloxil SF 91 A shows in comparison to unfilled polymer following advantages:

• lower warpage
• higher hardness
• higher scratch resistance
• higher stiffness (modulus)
• higher tensile and flex strength 
• improved heat deflection temperature 
• higher heat conductivity  

Gloxil SF 91 A shows in comparison with other mineral fillers following advantages:

• good wetting and dispersion properties
• high melt flow rates
• no crosslinking in PK-compounds
• relatively low warpage
• excellent surface finish
• optimum scratch resistance
• no graying of black-colored compounds
• increased stiffness (modulus)
• relatively high elongation at break
• relatively high impact strength, even at low temperature
• increased heat deflection temperature (HDT)
• matting (in films)

Want to know more about Gloxil SF 91 A in PP copolymer compounds?

• Overview page of Gloxil SF 91 A
• Technical datasheet of Gloxil SF 91 A

Stay tuned for future posts regarding the Tailored Filler Solutions to receive a better understanding of the products and where to use them! 

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