OECD Definition of Polymer
- A “polymer” means a substance consisting of molecules characterized by the sequence of one or more types of monomer units and comprising a simple weight majority of molecules containing at least three monomer units which are covalently bound to at least one other monomer unit or other reactant and consists of less than a simple weight majority of molecules of the same molecular weight.
- Such molecules must be distributed over a range of molecular weights wherein differences in the molecular weight are primarily attributable to differences in the number of monomer units.
EU, China, Korea and Taiwan follow with OECD definition and go further that:
- Over 50% w/w must consist of polymer molecules with at least three monomer units;
- The amount of polymer molecules presenting the same molecular weight is less than 50% w/w of the substance.
Definition of PLC
Criterion used to identify PLC have not been harmonized. The following parameters are usually used to define a PLC:
- The number-average molecular weight (Mn); An Mn >= 1000 Da is a generally accepted Mn range for a PLC;
- The content of low molecular weight, oligomeric species (i.e.,<1000 Da and/or <500 Da species);
- Whether specific reactive functional groups are present or absent in polymers;
- Solubility, stability and polymer class, etc.
Polymer registration in EU
- Polymer is exempt from registration;
- Registration of monomer or reactant>2%w/w is required if the volume of monomer or reactant exceeds 1t/y（2% rule）;
- No PLC definition.
- Source: ECHA guide on polymer registration
Polymer registration in China
- A new polymer substance not listed in exiting substance list must be registered prior to its manufacture or import;
- Polymer itself shall be registered under MEE order No. 12;
- If new polymer meets the filing requirements of polymers and does not fall into the exclusion of polymer filing (5 rules), polymer record application can be conducted, which including:
- Polymers containing no more than 2% of monomers or reactants as new chemical substances;
- Low Concern Polymers.
For polymers that do not meet the record application requirements, the applicant shall submit the regular registration or simplified registration dossier to MEE according to the amount. However, if the polymer meets the following three conditions at the same time, it is exempted from submitting health toxicology, ecotoxicology data and environmental risk assessment report while going through regular registration or simplified registration.
- The structure does not contain other metals except sodium, magnesium, potassium and calcium;
- Insoluble in water, lipophilic solvents (n-octanol, n-heptane) and general solvents (tetrahydrofuran, dimethyl formamide);
- It is stable under acid-base conditions, that is, stability tests conducted at pH values of 4.0, 7.0, 9.0 and 1.2 (if physiologically important) show stability.
Polymer registration in Korea
- Unlike EU REACH, K-REACH requires the registration of polymer itself. A new polymer substance must be registered prior to its manufacture or import. Existing polymer substances >=1t/y must be pre-registered and registered within a given deadline;
- Polymers could be exempted from registration and applicable to exemption applications if they meet the following criterial as the polymer of low concern (PLC), normally GPC and monomer residual report shall be available to determine whether the polymer is PLC or not:
- Polymer with Mn over 10,000 Dolton which contains oligomers with molecular weight of less than 1,000 over 5%, or oligomer with molecular weight of less than 500 over 2%.
- Polymer with Mn between 1000-10,000 D which contains oligomers with molecular weight of less than 1,000 over 25%, or oligomers with molecular weight of less than 500 over 10%.
- None-Cationic polymer
- Polymer with Mn under 10,000, which contains residual monomer of hazardous chemical, or priority management chemical not exceeding 0.1%.
- Non-PLCs must be performed as polymer registrations with two tiers level reduced data requirements.
It is important to understand the polymer definitions in different regions/countries and specific requirements of registration polymers products under each regulation regimes.
- Polymers are exempt from registration;
- Registration of monomers or reactants>2%w/w is required if the volume of monomers or reactants exceed 1t/y.
China MEE Order 12th
- Only new polymers require registration;
- Polymers with new substances of monomers or reactants less than 2% or PLC (no tonnage limited): Polymer Record application；（check the exclusion situation before Record）
- Non-PLC: simplified registration (1-10t/y) or regular registration (>10t/y) with reduced data requirements.
- Existing polymers with annual volume more than 1 ton per year and new polymers require registration;
- PLC: Apply for exemption applications;
- Non-PLC: Standard registration with reduced data requirements.