VFI®-4690 90 A MDI Casting Elastomer

Features & Benefits

• Superior physical properties for making parts and molds
• Moderate viscosity for casting intricate parts or large parts quickly
• Easy processing at room temperature
• Does not need to be freeze-protected for shipments
• Neutral color capable of being pigmented and colored as needed

Instructions for Use:

Mold Preparation

The mold must be clean, dry, and free of dirt, oils, and debris. The elastomer is compatible with most molds as long as the mold is sprayed with a proper release agent to prevent adhesion. We recommend Chem-Trend MR-515 Aerosol or a similar release agent. Spray several layers over the entire mold, waiting for the surface to dry before adding more. The release will help protect and extend the life of the mold and allow the part to release easily. However, spraying too much release on the mold can produce a shiny/glossy surface on the cured elastomer.

Mixing

The material should be at least 65°F before use for proper mixing and application. Mixing times may vary depending on volume and mixing method. Vacuum degassing can further reduce air entrapment to achieve bubble-free parts, but it is not required.

Thoroughly mix the POLY “B” component before mixing with the ISO “A” component. Usually, this takes a minimum of 3 minutes per “B” container with proper mixing equipment. Power mixing or meter mixing equipment is recommended for quantities over 1 gallon. Once the “B” component is thoroughly mixed, properly pour 1 part of the “A” component into 2 parts of the “B” component by volume, 56.1 parts “A” component into 100 parts “B” component by weight. Thoroughly mix for at least 30 seconds while scraping the sides and bottom of the container, ensuring the mix is uniform and homogeneous. Transfer to a separate, clean mixing container and mix again before use.

Molding Process

Cast the liquid elastomer in one spot at the lowest point of the mold until it is filled. If you are casting thin parts, use a higher durometer elastomer, such as VFI-4690 90 A MDI Casting Elastomer.

Allow the cast part to sit in the mold at room temperature for a minimum of 4 hours before demolding. It will develop full physical properties after 7 days at room temperature. It is required that the part sit for 3 days at room temperature before use or shipping.

Safety

*Always read the safety data sheet before working with chemicals

Use chemicals only as directed and for their intended purpose. Do not dispose of chemicals down the drain. Most chemicals must be disposed of as hazardous waste.

PPE to avoid all unnecessary exposure:

• Eye protection – wear approved safety glasses and any additional eye protection as necessary
• Hand protection – wear chemically resistant protective gloves (nitrile, butyl, or neoprene)
• Skin and body protection – wear suitable protective clothing
• Respiratory protection – in case of insufficient ventilation, wear suitable respiratory equipment. Respirator selection must be based on known or anticipated exposure levels, the hazards of the product, and the safe working limits of the selected respirator

Product Limitations

This product contains isocyanate, which can irritate the skin and is toxic if inhaled as particulate matter. Avoid prolonged breathing of vapors and repeated skin contact. It is not UV color stable and has no long-term UV testing. Urethane is moisture-sensitive and may foam when exposed to too much moisture, so use VFI-4690 in a controlled, high-production environment to limit moisture interaction.

• Incompatible materials – A side: water, alcohols, amines, bases, and acids. B side: oxidizers
• Conditions to avoid – heat and incompatible materials
• Chemical stability – stable under normal storage conditions
• Reactivity & hazardous reactions – no dangerous reaction known under normal use
• Hazardous decomposition products – A side: carbon monoxide, carbon dioxide, nitrogen oxides, hydrocarbons, and HCN. B side: may include, and are not limited to, oxides of carbon

Potential Health Hazards

• May cause respiratory tract irritation. A side material may also cause allergy and asthma symptoms or breathing difficulties if inhaled.
• Causes skin irritation and sensitization: redness, edema, drying, defatting, and cracking of the skin. Repeated exposure to B side material can result in absorption through the skin, causing a significant health hazard.
• Causes serious eye irritation: discomfort, pain, excess blinking and tear production, marked redness, and swelling of the conjunctiva.
• May cause stomach distress, nausea, or vomiting if swallowed.

*If you are experiencing any of these symptoms, seek medical advice or attention. Call a poison control center or doctor if swallowed.

Click here for more information on the full technical data sheet.