Bisphenol is a synthetic organic compund containing 2 phenol groups (two hydroxyl phenyl groups) and it is used mainly for making plastics and resins.
Types of Bisphenol
Bisphenol A (BPA)
Bisphenol AF (BPAF)
Bisphenol B (BPB)
Bisphenol F (BPF)
Bisphenol S (BPS)
Aromatic Syntans
Receives much attention due to their advantages of filling property, dispersibility, and bleachability.
Well suited for all color shades and result in leathers with a better lightfastness, compared to leathers retanned with vegetable tannins.
Generally prepared through condensation, sulfonation, and other reactions by using phenol or naphthalane, formaldehyde, and concentrated sulfuric acid as raw materials.
Common compounds in aromatic syntans
Phenolic monomers such as phenol.
Phenol sulfonic acid
bisphenol S (dihydroxy diphenyl sulphone)
bisphenol F
These compounds are used as either starting materials or intermediate molecules formed during the manufacturing process.
Application of Bisphenols in leather Processing
In general, aromatic syntans are condensates of phenolsulfonic acid and/or phenol and/or dihydroxydiphenylsulfone (DHDPS or Bisphenol S) with formaldehyde where urea is optionally used.
Bisphenol S (dihydroxyl diphenyl sulphone) is used as raw materials for the manufacturing of sulphone syntans.
Depending upon the efficiency of the consideration process, a certain amount of phenolic monomers are left unreacted during the manufacturing process. This unreacted phenol may react with formaldehyde, resulting in the formation of bispenol F.
In the leather industry, these phenol/sulphone syntans are primarily used for pre-tanning, tanning, retanning and dyeing.
These unreacted phenolic monomers such as phenol, phenolsulfonic acid and bisphenol S/F that are present in the syntans, will be transferred to the leather during the (re)-tanning processes.
Minimizing the bisphenol content of leather with GG Organics synthetic tanning agents
GG Organics has developed phenol-based retanning agents with desired limits of bisphenol content by using an innovative process, technology and monomer chemistry.
BPA, BPB and BPAF are not present in any of our retanning agents
The real challenge is matching the properties of conventional syntans. We did this with our new range.
GG Organics' cutting-edge laboratory has been upgraded with advanced LC-MS testing equipment for identifying the concentration of bisphenol in retanning agents and leather. This would ensure an efficient delivery mechanism in the frontier areas of the leather industry.
All of our low bisphenol products are evaluated with LC-MS technology, and the results were below the limit proposed by BAuA and the major customers.
Why there is a demand for chemicals and leather with low bisphenol content?
Bisphenol and its derivatives are known endocrine disruptors that are harmful to both human health and the environment, as well as causing reproductive toxicity. Because of the adverse effects caused by Bisphenols, European Chemicals Agency (ECHA) and the EU Member States have started screening data on a large group of Bisphenols in 2020.
ECHA and the EU Member States assessed a group of 148 bisphenols and recommended the more than 30 bisphenols including BPA, BPB, BPS, BPF and BPAF need to be restricted due to their potential hormonal or reprotoxic effects.
The Call for Evidence of BAUA (Federal Institute for Occupational Safety and Health) for BPA and bisphenols of similar concern (Bosc) limitation recommended a new limit (10ppm) for leather and textile auxiliaries including articles.
Though the limitation of bisphenols in leather is expected to be implemented between 2024 and 2026, manufacturers and brands have started asking for leather with less bisphenol without compromising product quality.
Due to that, there is an increasing demand for Bisphenol-free or low-bisphenol leather and chemicals in the global leather market.
Aromatic Syntans:
Receives much attention due to their advantages of filling property, dispersibility, and bleachability.
Well suited for all color shades and result in leathers with a better lightfastness, compared to leathers retanned with vegetable tannins.
Generally prepared through condensation, sulfonation, and other reactions by using phenol or naphthalene, formaldehyde, and concentrated sulfuric acid as raw materials.
Common compounds in aromatic syntans:
Phenolic monomers such as phenol Phenol sulfonic acid
Phenol sulfonic acid
bisphenol S (dihydroxy diphenyl sulphone)
bisphenol F
These compounds are used as either starting materials or intermediate molecules formed during the manufacturing process.
Application of Bisphenols in Leather Processing:
In general, aromatic syntans are condensates of phenolsulfonic acid and/or
phenol and/or dihydroxydiphenylsulfone (DHDPS or Bisphenol S) with
formaldehyde where urea is optionally used.
Bisphenol S (dihydroxy diphenyl sulphone) is used as raw materials for the manufacturing of sulphone syntans.
Depending upon the efficiency of the condensation process, a certain amount of phenolic monomers are left unreacted during the manufacturing process. This unreacted phenol may react with formaldehyde, resulting in the formation of bisphenol F.
In the leather industry, these phenol/sulphone syntans are primarily used for pre-tanning, tanning, retanning, and dyeing.
These unreacted phenolic monomers such as phenol, phenolsulfonic acid and bisphenol S/F that are present in the syntons, will be transferred to the leather during the (re)-tanning processes.
