My partner has an Indian passport with a permanent residence card in the UK.
Does he need a visa to travel to the Netherlands?
If you are not joining or accompanying your partner, then they have no access to the freedom of movement provisions.
A UK permanent residence visa (I assume you mean ILR) is not recognized as a valid instrument for Schengen because the UK does not provide reciprocity.
So yes, your partner will need a Schengen visa.