This site gives a good summary:
Understanding REACH - ECHA
In particular:
"REACH impacts on a wide range of companies across many sectors, even those who may not think of themselves as being involved with chemicals.
In general, under REACH you may have one of these roles:
Manufacturer: If you make chemicals, either to use yourself or to supply to other people (even if it is for export), then you will probably have some important responsibilities under REACH.
Importer: If you buy anything from outside the EU/EEA, you are likely to have some responsibilities under REACH. It may be individual chemicals, mixtures for onwards sale or finished products, like clothes, furniture or plastic goods.
Downstream users: Most companies use chemicals, sometimes even without realising it, therefore you need to check your obligations if you handle any chemicals in your industrial or professional activity. You might have some responsibilities under REACH.
Companies established outside the EU: If you are a company established outside the EU, you are not bound by the obligations of REACH, even if you export their products into the customs territory of the European Union. The responsibility for fulfilling the requirements of REACH, such as pre-registration or registration lies with the importers established in the European Union, or with the only representative of a non-EU manufacturer established in the European Union."