VFI®-4278 78 D Polyurethane Casting Plastic

Features & Benefits

• High heat deflection temperature (HDT) of 180.9°F
• Extended working time to vacuum degas and hand pour for bubble-free castings
• Able to be post-processed with CNC or general milling equipment

Instructions for Use:  

Mold Preparation

All surfaces should be clean, dry, and free of dirt, dust, and debris. Release agents are recommended for all molding applications to extend the life of the mold. When working with prototyping urethane molds, release is required. VFI recommends using a silicone-based release agent. Be careful not to overspray the release, as this may result in a shiny/glossy surface or loss of detail transferred to the casting.

We do not recommend using a heated mold or any mold over 120°F with this material. Compatible molds include aluminum, platinum silicone, and prototyping urethane rubber.

Casting Process

The material should be between 65°F – 85°F before use for proper mixing and application. Premix the B side (Poly) material before each use. The A side (Iso) does not need to be premixed. Avoid introducing moisture or air into the mix by working in a temperature-controlled environment with low humidity.

The material should be vacuum degassed for bubble-free castings. Prepare a container that is an appropriate size for degassing with at least 2/3 of headspace. Pour 100 parts of the A component into 85 parts of the B component by volume, 100 parts A component to 74.57 parts B component by weight. Thoroughly mix by hand or power mixer while ensuring the material is uniform and homogeneous. Transfer to a new, clean container and mix again before use. Be sure to scrape the sides and bottom of the container for uniformity.

VFI recommends pouring the material at least 1/8^th inch thick at room temperature. Thinner pours may not develop the necessary film to cure and develop full physical properties.

After an initial cure of 3-4 hours at room temperature (77°F), the material must be post-cured in an oven at 180°F for 16 hours to achieve full physical properties. Do not exceed temperatures above 200°F. If you do not post-cure the material, physical properties will be delayed until after 5-7 days at room temperature.

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 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 may irritate the skin and is toxic if inhaled as particulate matter. Avoid prolonged breathing of vapors or repeated skin contact. Use only with adequate ventilation. It is not UV stable and does not have any long-term UV testing.

• Incompatible materials – A side: water, alcohols, amines, bases, and acids. B side: strong oxidizing agents, strong acids, strong bases, and bromine trifluoride
• 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 but is not limited to, oxides of carbon and antimony oxides

Potential Health Hazards  

• May cause respiratory tract irritation. A side material may also cause allergy and asthma symptoms or breathing difficulties. 
• May cause stomach distress, nausea, or vomiting if swallowed.  
• May cause skin irritation or sensitization: redness, edema, drying, defatting, or cracking of the skin. 
• Causes serious eye irritation: discomfort, pain, excess blinking and tear production, marked redness, and swelling of the conjunctiva.  

*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.