- What is PU Rubber for Concrete Molds
What is PU Rubber for Concrete Molds
What is PU Rubber for Concrete Molds?
Polyurethane (PU) rubber for concrete molds is a two-component, room-temperature curing liquid PU resin system. Developed by TPUCO, this PU resin series is specifically designed for making durable, elastic molds, which are suitable for statues, cement wall decorations, concrete columns, artificial stones, ornaments, and millwork production. The mixing ratio of the mold making PU resins are 1:1 by weight, and the low viscosity makes them user-friendly and ideal for creating detailed, elastic, elastomeric molds, with hardness options ranging from 25 to 94 Shore A.
Concrete Mold Making with PU Rubber
Follow these steps for using PU rubber to make concrete molds:
- Ensure both Part A and Part B of the PU rubber resins are at room temperature, and that all tools are prepared. Mixing tools and containers should be clean and made of plastic or metal.
- Although TPUCO PU rubber resins are formulated to minimize air bubbles in the cured rubber, vacuum degassing before mixing and pouring the resin will further reduce trapped air.
- Pre-mix Part B of the PU rubber resins before use. Dispense equal amounts of Part A and Part B into the mixing container, then mix thoroughly for at least three minutes.
- Hand mixing with a Poly Paddle is recommended to avoid incorporating air into the rubber.
- For large batches, use a mechanical mixer for three minutes. Then, pour the entire mixture into a new, clean container and mix again.
Comparing Silicone and PU Rubber for Mold Making
Traditional RTV silicone rubber is widely used to create molds for statues, cement wall decorations, concrete columns, artificial stones, ornaments, and millwork. This is due to its ease of use, soft hardness, and ability to cure at room temperature. However, the cost of silicone rubber has been steadily increasing. As a result, many mold makers have switched to polyurethane rubber, which offers a lower cost and greater durability.
Beyond cost considerations, PU rubber has superior physical properties compared to silicone rubber, such as higher tear strength and lower compression set. This makes PU rubber molds more durable and shape stable. TPUCO PU rubbers are solvent-free and eco-friendly. The low viscosity of the PU resins makes them ideal for creating delicate molds with intricate designs. Additionally, when TPUCO PU rubber resins are used for finished products instead of molds, the resulting PU products are white, allowing for easy painting and coloring.
Comparison Chart of Silicone and PU Mold Rubbers
| |
Silicone mold rubber |
TPUCO PU mold rubber |
| Price |
Higher |
Lower |
| Process method |
Solvent type
(Heating is required if necessary.)
|
Solvent-free
(Heating is required if necessary.)
|
| Release Agent |
Not required, but can be used if necessary |
Release agent is required |
| Tensile Strength |
Fair |
Excellent |
| Elongation |
Fair |
Excellent |
| Tear Strength |
Fair |
Excellent |
| Durability |
Fair |
Excellent |
| Compression Set |
High |
Low |
| Pot life & Demold time |
Bigger adjustment range |
Smaller adjustment range |
| Solvent Resistance |
Fair |
Excellent |
| Water Resistance |
Excellent |
Excellent |
| Low Temperature Resistance |
Good |
Good |
| High Temperature Resistance |
Excellent |
Good |
| Weather Resistance |
Excellent |
Good |
| Optical Transmittance |
Fair |
Excellent |
| Recyclability |
No |
Yes |
More information about:
Mold making PU rubber
Fast curing casting PU for concrete mold
https://www.taiwanpu.com/en/product/PU-mold-rubber