Polyurethane-84 is an inorganic chemical compound, a segmented block copolymer derived from urethane and synthesised from isocyanates.

The name describes the structure of the molecule:

• "Polyurethane" is a term that describes a class of polymers widely used in various applications due to their versatility and desirable properties such as durability, flexibility and abrasion resistance and temperature variations.
• "-84" is a reference to the specific type or grade of polyurethane, which can be characterized by such factors as the types of isocyanates and polyols used, their relative amounts, and the presence of any additives. . This is a designation used to differentiate different molecular structures or variants of the polymer. In cosmetic chemistry, these numbers can help formulators identify specific characteristics or behaviors of a given ingredient, particularly when a chemical family has multiple derivatives or forms.

Significant substances used in the production method:

Hexanediol, Dimethyl Carbonate, Dimethylolpropionic Acid, Cyclohexane Dimethanol, Saturated Methylene Diphenyl Diisocyanate, Triethylamine, hydrazine, Diethylenetriamine.

Description of raw materials used in production and their functions.

• Hexanediol. This acts as a diolic component reacting with isocyanate groups to form urethane linkages.
• Dimethyl Carbonate. Can be used as a solvent or carboxylating agent in the process.
• Dimethylolpropionic Acid (DMPA). Provides hydroxyl and carboxylic groups enhancing the polyurethane's water solubility.
• Cyclohexane Dimethanol. Another diolic component contributing to the flexibility of the polyurethane.
• Saturated Methylene Diphenyl Diisocyanate. Provides the isocyanate groups necessary for the polyurethane formation reaction.
• Triethylamine. Serves as a pH adjuster and neutralizes DMPA acid, forming a salt.
• Diethylenetriamine. Used to chain extend and/or crosslink the polymer.

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

• Hexanediol, Cyclohexane Dimethanol, and DMPA are mixed and reacted with Saturated Methylene Diphenyl Diisocyanate to form a polyurethane prepolymer.
• Dimethyl Carbonate might be introduced to modulate carboxylation or solvent properties.
• Triethylamine salt of the DMPA acid is formed to make the polymer water-soluble.
• Diethylenetriamine is finally added to chain extend and/or crosslink the polyurethane, finalizing polymer formation.

What it is used for and where

Cosmetics

It is a restricted ingredient as II/201 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Substance or ingredient reported: Triethylamine 

Nail Conditioning agent. It is an agent that creates protection against harmful or chemical substances by strengthening the nail structure against external elements and can repair any chipping, cracking or brittle nails. It helps keep the nail's outer layer and keratin protein in good condition. It can also prevent cracking and peeling of the nail.

CAS: 1436463-63-6

It appears as a white powder or colorless liquid.

Safety

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

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.