POLYURETHANE-8 is an inorganic chemical compound, a segmented block copolymer derived from urethane and synthesised from isocyanates.
Significant substances used in the production method:
polyethylene-poly(tetramethylene)glycol, propanoic anhydride, isophorone diisocyanate, isophorone diamine.

Safety
Polyurethanes are rather complex, inert and biostable materials that are also used in biomedical applications. They are typically synthesised by the reaction of a glycol or polyol with polyisocyanate or diisocyanate. It is known that exposure to isocyanates can cause asthma, contact allergies, conjunctival and skin irritation. However, a study by the Cosmetic Ingredient Review Expert Panel in 2017 found that the rates of harmful residues are not significant for human health.
https://www.cir-safety.org/sites/default/files/Polyur092017FR.pdf

Urethane (also called ethyl carbamate) is a by-product of fermentation and is considered a genotoxic agent.

What it is used for and where
Cosmetics

Binder agent. Ingredient that is used in cosmetic, food and pharmaceutical products as an anti-caking agent with the function of making the product in which it is incorporated silky, compact and homogenous. The binder, either natural such as mucilage, gums and starches or chemical, may be in the form of a powder or liquid.

Film-forming agent. It produces a continuous ultra-thin film with an optimal balance of cohesion, adhesion and stickiness on the skin or hair to counteract or limit damage from external phenomena such as chemicals, UV rays and pollution.

Plasticiser. Ingredient added to the formulation with the purpose of retaining fragrance and colour, increasing flexibility, flowability, deformability, durability of various ingredients allowing better processing.
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