Polyurethane-33 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.
• "-33" 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:

dimethylolpropionic acid, Adipic Acid, Hexylene Glycol, Neopentyl Glycol, methylene dicyclohexyldiisocyanate (SMDI), triethylamine, hydrazine.

Description of raw materials used in production with their functions.

Dimethylolpropionic Acid (DMPA). Provides hydroxyl and carboxylic groups for urethane and ionic bond formation.

• Adipic Acid. A dicarboxylic acid providing acid groups for ester and urethane bond formation.
• Hexylene Glycol. Dihydric alcohol providing hydroxyl groups for urethane and ester bond formation.
• Neopentyl Glycol. Dihydric alcohol used to enhance the thermal and chemical stability of polymers.
• Methylene Dicyclohexyldiisocyanate. Provides isocyanate groups for urethane bond formation.
• Triethylamine. Acts as a catalyst and neutralizer for DMPA's carboxylic groups.
• Hydrazine. Chain extender that reacts with remaining isocyanate groups.

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

• Mixing of dimethylolpropionic acid, Adipic Acid, Hexylene Glycol and Neopentyl Glycol.
• Addition of methylene dicyclohexyldiisocyanate to the mixture and allow to react.
• Once a prepolymer is formed, triethylamine is added to partially neutralize the acid groups of DMPA.
• Hydrazine is added to further extend the polymer chain.
• Once a certain degree of polymerization is reached,the reaction is stopped and the polymer is cooled to obtain Polyurethane-33.

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.

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.