Polyurethane Curing Agents

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About polyurethane curing agents

Polyurethanes are made from two components, a polyol (also called a polyhydroxyl) and polyisocyanate (also referred to as iso). These are mixed in a one to one ratio. The polyol part is described in the section on polyurethane resins.

For simplicity, the polyisocyanate part of polyurethenes can be referred to as the curing agent. Polyurethanes can be supplied as two pack systems where the polyol is part A and the polyisocyanate is part B. When these two liquid parts are mixed they react completely, chemical bonds called crosslinks are formed between them and a cured solid forms. Polyurethanes can also be supplied as single pack systems, made up of a partially reacted polyurethane polymer. During fabrication, these systems further react with moisture to form a cured solid.

Polyurethanes in the composites industry are used in the form of a resin in a composite laminate. In a composite part, the resin binds the fibres together, allows loads to be transferred between the fibres and provides a barrier to weather, water or chemicals. Polyurethanes are also used as adhesives, which may be supplied as two pack or single pack systems. Some polyurethanes can be made into foams by the additions of foaming agents and with the appropriate manufacturing process.

If either of the two components of polyurethane resins come in contact with the eyes and skin they can cause irritation. Irritation will also occur if either chemical is inhaled or swallowed. The polyioscyanate part of polyurethanes is more hazardous than the polyol part. This is because the polyisocyanate can cause sensitisation of the respiratory tract. Once a person has become sensitised, any future exposure results in an allergic response, even with minimal exposure.

Special Protection Information

Respiratory Protection: Adequate ventilation must be provided. If above the NOHSC exposure standard, use SA approved respiratory protective equipment. If dust is generated during cutting or machining/grinding/sanding of cured product, wear disposable dust mask (Type P1). or better as determined by you risk assessment. When using resin system (including hardener) with fibres, use combination mask with vapour and dust particle filter.
Eye Protection: Use SA approved chemical splash goggles.
Protective Clothing: Wear chemical resistant gloves such as butyl rubber or neoprene rubber gloves. Apply full dermal protection to un-covered skin. Wear full length trousers and long sleeved shirts and safety boots.

Effects of Exposure

Eyes: May cause irritation and redness.
Inhalation: May cause irritation of the respiratory tract. Isocyanates are known to cause sensitisation of the respiratory tract.
Skin: Prolonged and/or frequent contact can result in irritation of the skin.
Swallowing: May cause some gastrointestinal irritation.

First Aid Procedures

Eyes: Flush with water for at least 15 minutes.
Inhalation: Remove to fresh air. If breathing is difficult, seek immediate medical assistance.
Skin: Remove contaminated clothing for laundering. Wash with soap and water. Do NOT use solvents.
Swallowing: Do NOT induce vomiting. If person is conscious, they should drink large quantities of water. Seek medical advice immediately.

Spill or Leak Procedures

Eliminate all sources of ignition and ventilate area. Wearing protective equipment, stop spill at source, dam area and if possible pump liquid into salvage tank. Alternatively, absorb residue with vermiculite or sand. Scoop up using non-sparking tools into labelled waste container. Flush area with water, but prevent it from entering waterways. Dispose of waste in accordance with local, state and federal regulations. Reporting of spills/leaks may be required under EPA and Dangerous Goods regulations.

Fire Extinguishing Procedures

Wear protective clothing and equipment including self-contained breathing equipment. In general, use foam or carbon dioxide to put out fires. (Refer to MSDS). Cool fire exposed containers with water spray.

Storage and Handling Procedures

DG Class 3 (Flammable liquid). Store in properly closed, labelled containers in a cool area, fitted with floor level and breathing zone ventilation to remove vapours which collect at these levels. Ensure all sources of ignition are eliminated. Keep away from strong oxidising agents. Do not transfer to unmarked containers. Do not transfer to unapproved plastic containers. Earth containers when pouring to prevent the discharge of static electricity.

KEY to abbreviations – CNS: Central Nervous System EPA: Environmental Protection Authority NOHSC:National Occupational Health & Safety Commission (Worksafe Australia) PVC: Polyvinyl chloride SA: Standards Australia

Disclaimer: Facts and information reported on this page are believed by Composites Australia to be accurate at the date of printing. No responsibility is accepted by Composites Australia for the use or misuse of information on this page. Composites Australia accepts no responsibility for damage or injury caused by information or omissions contained on this page.