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Cast Polyurethane

Cast polyurethane is an elastomer produced through casting with using raw materials such as diisocyanates, polyols, and curing agents. It can be manufactured in a wide range of hardness and offers advantages including wear resistance, elasticity, tear strength, oil resistance, solvent resistance, and ozone resistance.
Due to issues related to storage, handling, and toxicity, diisocyanates are supplied as prepolymers, which are formed by reacting diisocyanates with polyols. Cast polyurethane systems are typically classified into two-component systems (prepolymer and chain extender/curing agent) and three-component systems (prepolymer, polyol, and curing agent).

Supplier

Covestro Elastomers

Covestro Elastomers, the successor of Bayer, the original developer of polyurethane, offers a wide range of high-performance raw materials and specialized customer support based on its innovative raw material systems. As the only global company that also manufactures Baulé® molding machines, which best implement these systems, Covestro Elastomers provides a "One Single Source" service.

Choyang Chemical, as the distributor of Covestro Cast PU, supplies products from various factories in France, Spain, China, and other locations. Through its Tech Center, equipped with molding machines for demonstrations, and a logistics center with reliable inventory, offers the best services to its customers.

SYSTEM

Two-Component System

This system is designed to produce PU with a single hardness using pre-synthesized prepolymers,
which are made from diisocyanates and polyols, and curing agents.

Diisocyanate TDI, MDI, or others

Polyol (long chain) Ether, Ester, or others

Prepolymer

Chain Extender (short chain) Moca, BDO, or others

Polyurethane

Three-Component System (Quasi-prepolymer)

The Quasi-prepolymer is a prepolymer based on MDI, with more than 12% unreacted NCO content remaining.
This system allows for the production of PU with varying hardness levels by adjusting the proportions of polyol (long chain) and curing agent (short chain) during the casting process.

Diisocyanate MDI

Polyol (long chain) Ether, Ester, or others

Quasi-Prepolymer MDI-Ether
or
MDI-Ester

Polyol Ether
or
Ester

Chain Extender BDO

Polyurethane

Characteristics

The properties of cast polyurethane (PU) are determined by the type of diisocyanate (TDI or MDI) and polyol (Ether or Ester) used in the prepolymer.

Regarding the diisocyanate

TDI
Advantages	Drawbacks
Low moisture sensitivity Easy mixing Easy process Easy to reach high hardness Linear reaction kinetics	Difficulty to reach low hardness Toxicity

MDI
Advantages	Drawbacks
Adjustable pot-life Low toxicity Hydrolysis resistance Large range of hardness	Sensitive mixing and process Exponential reaction kinetics

Regarding the long chain polyol

Ether Polyol
Advantages	Drawbacks
Hydrolysis resistance Microorganism resistance Low temperature behavior Resilience	Solvent resistance Tear resistance

Ester Polyol
Advantages	Drawbacks
Solvent resistance Hydrocarbon resistance High temperature behavior Tear resistance Abrasion resistance	Sensitive to hydrolysis Sensitive to microorganism Low resilience

Application

Renewable energy
Automotive
Material handling
Mining and Quarries
Oil & Gas
Pulp & Papaer
Printing
Industrial
Sports & Leisure

Types

TDI prepolymer

System with free TDI content under 0.5% enabling excellent mechanical properties, safety with low toxicity, and cost-effective as non-dangerous goods
Low unreacted TDI prepolymer

Free TDI content under 0.1% enabling low toxicity, low viscosity, and excellent mechanical properties
MDI prepolymer

Moca free, Low toxicity, Wide range hardness, Good hydrolysis resistance, Easy pot life control
Quasi-MDI prepolymer

Conveniently produce various hardnesses with single system
NDI prepolymer

Low abrasion loss and compression set, High tensile strength, tear resistance, and rebound resilience. Excellent dynamic performance with minimal compression set under prolonged high load and high-speed usage
Rotational Casting System

Coating roller without molds using the rotational casting technique. No additional processing steps
Cold Casting System

No need to pre-heat molds or post-cure. Low shrinkage and high elongation. Appropriate for prototypes and concrete molds.
Customized Systems

A variety of systems developed to meet specific customer requirements.