Millathane® Millable Polyurethane Rubber and Thanecure® Reactive Additives
TSE Industries, Inc. is the world’s largest manufacturer of millable urethane rubber, sold under the trade name of Millathane®. TSE has been working with millable urethanes since 1962 and producing Millathane millable urethanes since 1976. TSE Industries has two facilities in Clearwater, Florida (USA).
Introduction to Millathane® Millable Urethane
Millable polyurethane rubbers (sometimes known as millable gums) are solid polymers that can be processed on standard rubber processing equipment such as internal mixers (Banbury® mixers) and rubber mills. The properties of millable urethanes are generally comparable to castable (liquid) urethanes, which require different processing equipment and molding techniques. Millable urethane rubbers are used in many demanding applications, especially those that require excellent mechanical strength, oil resistance, ozone resistance and abrasion resistance.
Polyurethanes are made by reacting a diisocyanate with a polyol and usually a chain extender. Millable polyurethane rubbers are made from both polyester and polyether polyols. Diisocyanates like MDI, TDI, H
Like other synthetic rubbers, cure sites must be present to radically cure with peroxide or sulfur. Cure sites can be accomplished by the use of MDI as the isocyanate or by introducing carbon-carbon double bonds in the chain extender. Thus vulcanization can be accomplished with heat and pressure utilizing sulfur or peroxide cure systems. An important part of the sulfur cure system is the accelerator Thanecure® ZM, used along with MBTS, MBT and sulfur.
Millathane compounds can be made into dense, solid materials or sponge materials (foamed or blown). Dense compounds can have hardnesses from approximately 25 to 99 Shore A (60 Shore D), tensile strengths over 5000 psi (35 MPa) and DIN abrasion values as low as 30-40 mm³ loss. Sponge compounds can be produced with densities as low as 0.4 g/cc.
Millable urethane rubbers possess a combination of physical properties not found in natural or synthetic rubber such as:
- Outstanding abrasion resistance
- Excellent oil, oxygen and ozone resistance
- Excellent gas (e.g., nitrogen) permeability resistance, especially with polyester grades
- Low temperature flexibility
- Dynamic load bearing ability
- High resilience
- Excellent resistance to compression set
- Withstands temperatures up to 120° C
Millathane® millable polyurethane rubber is useful to rubber molders or fabricators who wish to make abrasion and oil resistant parts without employing techniques or equipment required for cast or thermoplastic polyurethanes. Applications for millable polyurethane include:
Rollers and Belting
Millathane millable urethanes are widely used in rubber covered rolls because of their excellent combination of abrasion resistance, oil resistance and resistance to glazing, so they retain their coefficient of friction as they age. This is important for rollers and belts in paper and currency handling applications. Several grades that are often used in rollers are Millathane E34, Millathane 5004 and Millathane 76.
The strength properties of urethanes, including tensile strength and abrasion resistance, make it useful for critical applications for (non-implantable) medical devices. Millathane grades that find use in this application area include Millathane 76, Millathane E34 and Millathane 26.
Military and Aeronautical Applications
Many rubber applications in military and aerospace, including parts on airplanes and helicopters, require the high abrasion resistance of Millathane millable urethanes along with very good low temperature properties. Millathane CM and Millathane E40 are two of the Millathane grades that are excellent for both abrasion resistance and low temperature properties and are used in these applications.
The wear resistance, excellent frictional characteristics and excellent ozone resistance make Millathane millable urethanes the polymer of choice for applications such as keypads, belts and rollers. Millathane grades used include Millathane 5004, Millathane 66 and Millathane 97.
The excellent abrasion resistance of urethanes like Millathane E34, Millathane CM and Millathane E40 make these polymers desirable for tough footwear applications, especially in the sporting shoe industry. The good wet and dry frictional properties of millable urethanes make it good for shoe soles. The transparency of Millathane 97 is the reason it has been used in transparent footwear applications for over 20 years. Download our Millathane Footwear Brochure from our Millathane Technical Information page.
Oil and Fuel Resistant Applications
Polyester grades of Millathane millable urethanes are widely used in o-rings, gaskets and seals, where the excellent resistance to petroleum based oils, fuels and hydraulic fluids is important. Millathane grades used for oil resistant applications include Millathane 5004, Millathane 66, Millathane 76 and Millathane HT.
The abrasion resistance of Millathane millable urethanes, coupled with their excellent oil resistance and frictional characteristics, make them the choice for specialty industrial tires that require these properties. Millathane grades that are used in this application include Millathane 76 and Millathane E34.
Millathane® Millable Polyurethane Grades
TSE produces Millathane millable urethanes in both polyester and polyether grades. Polyether grades have better water and hydrolysis resistance than polyester grades, while polyester grades have better heat, oil and compression set resistance than polyether grades. Most Millathane grades are available in a range of viscosities, and are available as dense bales or Premilled sheets.
|Polyether grades||Key Properties||Typical Applications|
|Millathane® 26||Compliance with FDA regulation 21CFR177.2600||Rollers, belting and molded parts, for food and non-food handling applications|
|Millathane® 97||Transparency and high abrasion resistance||Transparent shoe soles and shoe components, and brightly colored parts|
|Millathane® CM||Excellent strength, abrasion resistance and low temperature properties||Military and aerospace parts requiring excellent strength and abrasion and low temperature resistance|
|Millathane® E34||Abrasion and hydrolysis resistance||Rubber covered rollers for paper and printing industries, footwear|
|Millathane® E40||Outstanding low temperature properties||Military and aerospace parts requiring the optimum in low temperature properties|
|Polyester grades||Key Properties||Typical Applications|
|Millathane® 5004||Oil and solvent resistance||Suction cups, diaphragms, rollers for printing and paper handling|
|Millathane® 6010||High hardness compound with high strength||Clay tile die molds, industrial parts|
|Millathane® 66||Excellent heat, oil and compression set resistance||Seals, gaskets, belts, rollers needing the optimum in heat and compression set resistance|
|Millathane® 76||Excellent oil and abrasion resistance||O-rings, gaskets, suction cups, vibration isolators, wheels|
|Millathane® HT Premilled*||Excellent frictional characteristics and low temperature properties||Belts, rollers, gaskets requiring excellent frictional characteristics|
|Thanecure® T9 (TDI Dimer)||Thanecure T9 is dimerized TDI and is used as a vulcanization agent for isocyanate cured millable urethanes. It is also used as an adhesion promoter for rubber to textile bonding.|
|Thanecure® ZM||Thanecure ZM is a cure activator/accelerator for sulfur cured millable polyurethanes. It is typically used at a 1 phr level which give a good balance of cure speed and processing safety.|