Polyurethane-35 is an inorganic chemical compound, a segmented block copolymer derived from urethane and synthesised from isocyanates, a complex urethane polymer that is made by reacting a polyester pre-polymer consisting of adipic acid, neopentyl glycol and  hexanediol with dicyclohexylmethane diisocyanate.

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.

Description of raw materials used in production and their functions.

• Adipic Acid. A dicarboxylic acid used to provide urethane bonds within the polymer.
• Dicyclohexylmethane diisocyanate. An isocyanate molecule utilized to react with alcohols forming urethane bonds.
• Ethylenediamine. A chain extender with two amine groups to react with isocyanate groups.
• Hexandiol. A diol used to react with isocyanates during prepolymer formation.
• Neopentyl Glycol. Another type of alcohol used in the prepolymer.
• Sodium N-(2-aminoethyl)-3-aminoethanesulfonate. A sulfonate monomer which can introduce sulfonate functional groups into the polymer.

Step-by-step summary of industrial chemical synthesis process.

• Preparation of Monomers. The raw materials are purified and, if needed, converted into the appropriate reactive forms.
• Polymerization. Dicyclohexylmethane diisocyanate is reacted with Hexandiol and Neopentyl Glycol to form an isocyanate-terminated prepolymer.
• Chain Extension. The prepolymer is then chain extended using ethylenediamine and sodium N-(2-aminoethyl)-3-aminoethanesulfonate, serving as a chain extender.
• Formation of Polyurethane. Adipic Acid is subsequently introduced into the reactive mixture to form urethane bonds, which are pivotal in the formation of polyurethane.
• Purification. The polymerization may produce impurities or unreacted monomers that need to be removed through purification.
• Drying and Solidifying. The resulting polymer is then dried and solidified into the desired form, such as films, fibers, or foams.

It appears as a white powder or colorless liquid.

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.

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