Question 1

What MFI should I specify for PP granules for general injection moulding?

Accepted Answer

For general-purpose injection moulding of consumer products (containers, caps, housewares), an MFI of 8–20 g/10 min (230°C/2.16kg) is suitable for most standard wall thicknesses (2–3mm). For thin-wall packaging (wall thickness below 1.5mm), specify 25–60 g/10 min. For thick-wall structural parts (wall thickness above 4mm), specify 3–8 g/10 min for better control and reduced sink marks. Always confirm the MFI range appropriate for your specific tool and machine with your toolmaker or machine supplier.

Question 2

Can PP granules for injection moulding be used for food-contact products?

Accepted Answer

Yes — polypropylene is widely approved for food contact applications. For food-contact moulded products, specify a food-contact grade PP and request the supplier's Declaration of Compliance confirming compliance with EU Regulation 10/2011 (for EU markets) or FDA 21 CFR 177.1520 (for US markets). The declaration should confirm that the resin contains no restricted additives or colorants in excess of permitted migration limits. Verify that any masterbatch colorants used in moulding also have food-contact approval.

Question 3

What is the typical lead time for a container order of PP granules from China?

Accepted Answer

For standard grades held in stock by a trading company or regional warehouse, lead time from order confirmation to vessel loading is typically 5–15 days. For manufacturer direct orders requiring production scheduling, lead time may extend to 3–6 weeks. Ocean freight from Chinese ports to Europe is typically 25–35 days; to West Africa 20–30 days; to the US East Coast 28–40 days. Confirm current schedules with your freight forwarder at the time of order.

Question 4

What is the difference between natural, black, and coloured PP granules?

Accepted Answer

Natural (or white) PP granules contain no colourant and are the base grade used for dyeing or where the natural milky-white colour is acceptable. Black PP granules contain carbon black masterbatch pre-compounded into the resin — used for parts requiring UV resistance (outdoor applications) or where colour consistency is critical. Coloured PP granules contain pre-compounded pigment — typically used for high-volume production where colour consistency across batches is required. For small-volume colour production, buying natural granules and adding colour masterbatch at the moulding machine is more flexible. Confirm that colorants comply with applicable regulations for your end application.

PP-Granulat für Spritzguss

PP homopolymer vs copolymer — which grade for injection moulding?

Certifications and documentation to request