Gel Coat Application:

Catalyst

Organic Peroxides
Organic peroxides are usually highly flammable and under certain conditions may decompose with explosive violence. Catalysts have been tested by their manufacturer for heat sensitivity, shock sensitivity, burning rate, flash point, storage stability and reaction to blasting caps to determine their relative hazards.

The material is a strong irritant and corrosive to the eyes. Proper protective equipment must be worn when handling. Obtain manufacturer's material safety data sheets and safe handling and disposal before using.

Mixing
The catalyst must never be added directly to undiluted accelerators or promoters. A violent explosion may result. The best procedure is to first thoroughly mix the accelerator into the resin and then add the catalyst.

Very small quantities of peroxide initiator make drastic changes in the physical properties of polyester resins. It is imperative that all precautions be taken in handling the commercial forms of these products to assure high performance of the initiator and to avoid violent decomposition.

Keep all work areas, tools and containers clean. Avoid mixing peroxides with any substances other than those recommended by the catalyst supplier. Weigh and mix in a special room or area separate from other plant operations. The mix area should be well ventilated and be equipped with sprinklers.

Employees should know the location of the nearest emergency shower and eye wash in the mix area.

Contamination
Contamination is always a potential problem in the handling and use of peroxide catalysts. The most common causes of contamination are exposure to heat and contact with metals. Never expose organic peroxides to heat regardless of the source. This means open flames or sparks, radiators, steam pipes, or direct sunlight. Any of these exposures may cause the peroxides to decompose explosively and they will burn violently once ignited. Consult manufacturer's recommendations and never exceed recommended storage temperatures.

If a ketone peroxide is heated above a certain temperature, its rate of decomposition increases in an uncontrolled manner. This reaction can become violent, releasing large volumes of hot flammable gases. The temperature at which this occurs depends on the volume, the container and the length of time which the ketone peroxide remains at the temperature. The self-accelerating decomposition temperature (SADT) has been determined to be about 145º F. for methyl ethyl ketone peroxide. Never allow organic peroxides to come in contact with easily oxidized metals or rubbers. Such metals include copper, brass and mild or galvanized steel. Contact with natural and synthetic rubbers is hazardous. When replacement parts are required for equipment designed to handle organic peroxides, follow materials specifications of the equipment manufacturer.

Never mix peroxides in metal containers. Brass, copper, zinc, galvanized finishers and some steels and aluminum alloys are corroded by peroxides and the resulting corrosion can trigger a peroxide fire or explosion.

Equipment designed for contact with ketone peroxides should be limited to 316 stainless steel (304 is an alternate), low and high density polyethylene, glass, and other inert plastic materials like Teflon, Kynar, Nylon and Kel-F. These installations should be adequately grounded, bonded and of approved explosion-proof electrical construction.

Resin or resin over-spray can contaminate equipment used to handle peroxides and create hazardous conditions. If, for example, the funnel used to charge a catalyst pressure pot is contaminated, the amount of promoter present in the funnel could decompose the peroxide. Grinding dust is also a source of promoters that can decompose peroxides.

Extinguishing Agents
Ketone peroxides burn vigorously and are difficult to extinguish. The usual precautions for flammable liquids should be observed. If a small fire occurs, Class B extinguishers (dry chemical, foam, or carbon dioxide) can be used. In case of fire involving large quantities of ketone peroxides, the area should be evacuated and the fire fought with water.

FireExtinguishing Agent
Styrene monomer and/or polyesterDry chemical, water fog, foam or carbon
monomer and/or polyesterdioxide

CAUTION: Solvent and/or monomer fire can float on water and therefore can be spread when hit by a direct high pressure stream of water. Never use water or foam to extinguish a fire where electrical equipment is present.

SPRAYING WITH ORGANIC PEROXIDES

Safety Precautions
Keep all equipment clean, with covers in place. Be sure equipment is checked and maintained regularly.

Avoid contaminating the organic peroxide when filling the dispensing containers. Sanding dust and resin over-spray are hazardous sources of contamination. Dispensing containers must be kept away from any sources of fire or heat.

Make sure pressure pot vents are free of all over-spray. Vents clogged with over-spray or vents that are too small will not clean the air adequately. Never test spray into the atmosphere. Always spray into water.

Always duplicate the original construction material when replacement parts become necessary. Replacing screens and other parts with copper or other metals that are corroded by peroxide can result in fires and explosions.

NEVER SMOKE IN THE SPRAY AREAS. Wear eye protection at all times. Be sure ventilation system is in operation and/or wear a respirator to avoid breathing over-spray. Never point the spray gun at yourself or anyone else.

Storage and Shelf Life
Always store organic peroxides in the manufacturer's original shipping containers. Properly stored ketone peroxides have a limited shelf life. All containers should be dated upon receipt and either used or disposed of within the prescribed time. Store at proper temperature. When measuring or transferring quantities of peroxide, always use clean glass, teflon, polypropylene, polyethylene or stainless steel containers, funnels, stirrers, etc.

Before disposal, containers must be completely emptied and cleaned. DO NOT REUSE CONTAINERS. Destroy empty containers following container label instructions.

Keep only the quantity of material that will be used during the operating shift at the work station. Keep all containers labeled and tightly closed to avoid contamination. Organic peroxides must be stored apart from all other materials used in the plant.

DISPOSAL OF ORGANIC PEROXIDES

Organic peroxides must be destroyed. If they are discarded or dumped into sewers they can catch fire or explode.

Spills
Spilled liquid or paste peroxides must be absorbed with sand, clay, perlite, or vermiculite and then wetted down with water. After wetting down, sweep up with non-sparking tools. Sweep solid peroxides with extreme caution. Wet waste should be placed in double polyethylene bags and disposed of as follows:

Disposal of Wet Wastes
Safe destruction of peroxides can be accomplished by slowly adding them to a 5% caustic (lye) solution. Follow your plant's recommended procedures for disposal of diluted solution. When cleaning up use only clean, white rags. Dyes used in colored rags may react with peroxides. Contaminated rags and single-use containers and tools may be disposed of by burning in a property designated incinerator which has been permitted by local environmental authorities, or by soaking them in water. Follow your plant's recommended procedures.

Dusts
Dusts from flashing removal, finishing operations, sanding joints or repairing defects can irritate the skin, nose, throat and lungs. The plant's finishing areas should be equipped with exhaust booths or equipment with vacuum dust collection devices. Depending on the effectiveness of this equipment, dust respirators may still be necessary. Dust respirators must be worn where there are no dust collection devices available. Long sleeved shirts will reduce exposure to skin.

CAUTION: A source of many explosions in the past has been dust from cutting, grinding, etc. which sifts into catalyst pots through the vent and during filling. This dust contains cobalt compounds from the promoter system which causes decomposition of peroxides. The best way to eliminate this problem is to eliminate the catalyst pot altogether and use positive displacement catalyst injection equipment.