- CUROX® M-303 is a colorless liquid consisting of a mixture of peroxides based on methyl ethyl ketone peroxide, primarily desensitized by phthalate plasticizers.This peroxide is used as an initiator (radical source) in the curing of unsaturated polyester resins.
- Main Applications: Room-temperature curing of gel coats, molded parts, castings, or glass-fiber-reinforced products, when used in combination with cobalt accelerators.
- Appearance: Colorless liquid
- Active oxygen: approx. 9.1% (mass percentage)
- Free hydrogen peroxide content: approx. 1.7% (mass percentage)
- Water content: approx. 1.5% (by weight)
- Desensitizer: Dimethyl phthalate
- Density (20°C): approx. 1.1 g/cm³
- Viscosity (20°C): approx. 20 mPa·s
- Miscible with alcohols and phthalates
- Critical temperature (SADT): Above 60°C
- Refrigerated stability: below -20°C
- Recommended storage temperature: 0°C to 30°C
- Activity remains stable for 6 months at 30°C from the date of delivery
- Suitable for curing all types of unsaturated polyester resins when combined with a cobalt accelerator at room temperature.
- Standard dosage: 1–3% of the supply volume, combined with 0.5–2% of a 1% cobalt solution.
- Also suitable for gelatin layers with improved penetration resistance and low porosity due to low moisture and hydrogen peroxide content.
- The “working time” (gel time of the resin + peroxide + catalyst mixture) is relatively short but can be extended by adding inhibitors such as tert-butyl hydroquinone.
- Moderate heat release, long mold release time, and moderate mold release factor.
- Temperatures below 20°C significantly prolong the curing time; alternatively, cobalt/amine accelerators may be used.
- Particularly suitable for hand lay-up, spray-up, centrifugal casting, fiber winding, resin casting, and surface coatings (fillers, fillers, gel coats, and topcoats).
- Spray Equipment: Use spray equipment in accordance with the manufacturer’s instructions. Ensure that all safety equipment is in proper working order. Do not spray MEKP into the air to clean the spray gun.
- This information and all further technical recommendations reflect our knowledge and experience regarding this product and its applications, based on internal testing, and are intended to provide information about our products and their applications. This information should not be construed as a warranty regarding the specific properties of the described product or its suitability for a particular application, nor does it constitute complete instructions for use.This information does not constitute a warranty regarding the product’s characteristics or shelf life, nor does it impose any legal or other liability on us, including liability related to existing third-party intellectual property rights, particularly patent rights.We reserve the right to make any changes based on technological advancements or further developments. The use and application of our products in accordance with our technical recommendations are beyond our control and are entirely the responsibility of the user. The user is obligated to conduct thorough incoming inspections and tests to verify suitability for the intended application.