The Monobloc chair is a lightweight stackable polypropylene chair, usually white in colour, often described as the world's most common plastic chair.
Based on original designs by the Canadian designer D.C. Simpson in 1946, variants of the one-piece plastic chair went into production with Allibert Group and Grosfillex Group in the 1970s. They were inspired by the Chair Universal 4867 design by Joe Colombo in 1965, but no patents were filed for a monobloc chair design. Since then, millions have been manufactured in countries including Russia, Taiwan, Australia, Mexico, the United States, Italy, France, Germany, Morocco, Turkey, Israel, India and China. The Monobloc chair is named because it is injection moulded from thermoplastic as one piece rather than being assembled from multiple pieces. Many variations and styles exist but all are designed to allow the chair to be made quickly and cheaply through injection molding. A common thermoplastic used is thermoplastic polypropylene, with the granules being heated to about 220 degrees Celsius, and the melt injected into a mold. The gate of the mould is usually located in the seat, ensuring smooth flow to all parts of the tool.
