Colloids

They launched their graphene enhanced masterbatch at the end of last year. It is still unknown who their supplier in case of graphene is. In a current article they say:

“When the customer has an interest, then we need to sit down with them and talk about bespoke formulations because, depending on their requirements and performance targets, we need to find the right formulation, either by using one type of graphene or a mixture of them, or the specific size of platelets. You have to strike a balance between over-designing or under-designing a product.

Colloids: masters of masterbatch - Graphene (manchester.ac.uk)

So far I am only aware of FGR providing different platelet sizes (5-50). Also Colloids have developed their products at the GEIC:

Colloids is the only masterbatch company that works closely and fully sponsors a PhD project at the National Graphene Institute and the Graphene Engineering Innovation Centre at the University of Manchester (in Manchester, UK). Colloids is also the first masterbatch producer who became a member of the Graphene Council (US).

Colloids has been working on its graphene R&D for over seven years, extensively collaborating with the world’s top graphene producers analyzing the different quality and grades. This work has enabled the formulation of novel polymer composites using this remarkable 2D material. As a result, Colloids is now able to offer bespoke solutions to its global customers.

Colloids Ltd set to Launch New Advanced Graphene 2D Polymer Composites - Colloids

So it looks like they obtain the graphene from at least one graphene producer active at the GEIC. In regards to the different platelets sizes, FGR might be involved? The only other one I see is Black Swan Graphene, but only because I don't know their product specs...