Glossary | urethane intermediates

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Acid Number

Acid number expresses the amount of residual acidic material in a polyol. It is reported as the number of milligrams of potassium hydroxide required to neutralize the acid content in one gram of sample.


BDO (1,4-Butanediol) is a stable, hygroscopic, clear, colorless liquid with a freezing point of 19-20ºC and a boiling point of 230°C. It is used extensively as a chain extender (curative) in production of polyurethane elastomers by reaction with diisocyanates and in the manufacturing of polyester polyols by reaction with dibasic acids. Gantrade offers low moisture BDO grades (<100ppm) for polyurethane industry.

Castable Polyurethanes

Castable Polyurethanes are liquid, 100% solids, reactive polymer systems. Such systems are used for production of polyurethane parts through the process of casting into open molds.


A molding process where a liquid polyurethane reaction mixture is poured into a cavity of an open mold to form a solid part. The process of removing the newly formed, solid part from the mold is called demolding.

Chain Extender

A chain extender is generally low molecular weight diol or diamine that reacts with diisocyantes to produce rigid "hard block" urethane segments in a high molecular weight polyurethane.


Curatives are reactive hydroxyl and amine compounds with a functionality of two or more that react with isocyanate moieties and become part of the molecular structure of the polyurethane, most specifically the “hard block” segment.


DETDA is a liquid mixture of 3,5-diethytoluene-2,4-diamine and 3,5-diethytoluene-2,6-diamine used as a specialty curative and chain extender for diisocyanate pre-polymers, creating polyureas with excellent mechanical and dynamic properties. It is also a curing agent for epoxy resins. DETDA provides excellent mechanical properties with low heat build-up under high compression loads, good resiliency, abrasion, wear and tear resistance, and processing advantages. The primary applications are in coatings, adhesives, sealants and cast elastomers. Gantrade offers a low color DETDA in totes.


DMTDA (Dimethylthiotoluenediamine) is a specialty curative and chain extender for diisocyanate pre-polymers, affording polyureas with good mechanical and dynamic properties. It is a viscous liquid used in both hot and room-temperature cast systems. DMTDA can be blended with other liquid diamines to achieve systems with varying cure rates and mechanical properties. A wide range of applications include polyurethane wheels, tires, rollers and casters, etc. It is used in the automotive, construction, mining, textiles, paper, and printing industry.


Durometer is a quantitative measure of the hardness of a material. Durometer is an ASTM hardness test, which measures the depth of an indentation in the material created by a given force on a standardized probe. This depth is dependent on the hardness of the material, its viscoelastic properties, the shape of the probe, and the duration of the test.

Gel Time

The elapsed time from the moment the components (prepolymer and curative) are mixed to the point when the reacting mass becomes a viscous, non-flowing, semi-solid.


Hydroxyethyl Ether of Resorcinol is an aromatic diol chain extender. It has good compatibility with MDI systems, which offers excellent performance in CPU, MPU and TPU polymer applications. HER based polyurethane elastomers impart better tear strength, tensile strength, compression set, cut resistance and ease of handling. HER systems maintain maximum endurance, elasticity, plasticity and minimum shrinkage of PU elastomer. Besides those common advantages of aromatic chain extenders, HER avoids the rapid crystallization in HQEE. The melting point of HER is ~ 15°C lower than HQEE and HER exhibits super-cooling behavior.

High Performance Coatings

In coatings, polyurethanes are distinguished by toughness and elasticity, high strength, water and humidity resistant, and abrasion, scratch and corrosion resistance. They can be formulated to resist weathering, yellowing and exhibit excellent gloss retention. Polyurethanes can be applied through a number of coating techniques to substrates such as metals, wood, concrete & masonry and plastic surfaces. Polyurethane coatings are widely used in architectural coatings, automotive coatings, marine coatings, industrial maintenance coatings and many types of product finishes.


Hydroquinone bis (2-hydroxyethyl) Ether is a symmetrical aromatic diol chain extender for polyurethanes. The polyurethane cured by HQEE exhibits higher melting temperatures vs. BDO. Therefore, HQEE-based elastomers show greater elevated temperature performance vs. comparable BDO systems. HQEE can improve tensile, hardness and resilience properties in MDI-polyurethane elastomers. HQEE/MDI PUR elastomer series parallels MCDEA/TDI. End uses include: industrial and forklift tires; pipe linings and coatings; seals and gaskets; conveyor belts, rollers and roll covers; oil well and hydraulic cylinder seals; high performance skate wheels and many other polyurethane products.

Hydrolytic Stability

Hydrolysis is the reaction of a polyurethane with water to degrade the polymer structure. Factors that affect the hydrolysis rate include temperature, pH and moisture absorption. Ester polyol based polyurethanes are the most susceptible to degradation and produce acid moieties that accelerate the hydrolysis process. Polyether based polyurethanes are the most hydrolytically stable.

Hydroxyl Values

Hydroxyl Number (OH Number) is determined by a wet analytical method for the hydroxyl content of a polyol, or by IR Spectrophotometry. It is expressed by the milligrams of potassium hydroxide in one gram of polyol or other hydroxyl compounds.


Hysteresis is a measure of the energy lost or absorbed by a material, such as a rubber or polyurethane elastomer, when subjected to deflection.


Methylene bis (ortho-ethylaniline) is a specialty liquid diamine curative and chain extender for isocyanate pre-polymers, affording polyureas with superior mechanical and dynamic properties. MBOEA provides excellent mechanical properties with low heat build-up under high compression loads, superior hydrolytic resistance at higher temperatures, good resiliency, abrasion, wear and tear resistance. The primary end applications are in the CASE markets – coatings, adhesives sealants and cast elastomers and fast set spray-on coatings. Gantrade offers MBOEA in drum packaging.


Methylene bis (ortho-diethyl-3- chloroaniline) is a solid, high performance, hindered aromatic diamine curative and chain extender for isocyanate and pre-polymers. It affords polyureas with superior mechanical and dynamic properties and extended gel times. MCDEA provides excellent mechanical properties with low hysteresis (heat build-up), excellent temperature resistance up to 150ºC (302ºF), good resiliency, abrasion, wear and tear resistance, and processing advantages. The primary end applications are in the CASE markets – coatings, adhesives sealants and cast elastomers, and wheels and tires. MCDEA is preferably used with TDI based urethane prepolymers. Gantrade offers high purity - low-color grades of MCDEA in 20kg. packaging.


MDI, Methylene diphenyl diisocyanate, is an aromatic diisocyanate used in the production of polyurethanes through reaction with polyols and diols. The 4,4'-isomer of MDI is the most widely used diisocyanate. Other forms include polymeric, PMDI, and mixed isomer of MDI. MDI is used in the production of polyurethanes in applications such as CASE (Coatings, Adhesive , Sealants & Elastomers). PMDI is used in applications such as rigid, flexible and semi-rigid foams.

MDI Systems

Diphenylmethane diisocyanate (MDI)-PTMEG (polyether) systems produce urethane elastomers with higher resilience, better impingement type abrasion resistance, good dynamic performance, improved hydrolysis resistance and excellent low temperature properties. MDI-Polyester systems are tough, abrasion resistant and tear resistant. Both can be formulated to produce dry and wet food FDA compliant polyurethane elastomers.


Methyl ethyl ketoxime (MEKO) is a reactive chemical blocking-agent for the isocyanates group in prepolymers. A primary use is in water-dispersible polyurethane dispersions (BPUD), where the blocked isocyanate remains unreactive until de-blocked by heating. Advantages of the blocking technology include storage-stability, one-component system formulations and compatibility with fast-curing chain extenders. Other applications are in coatings, binders and adhesives.


4,4’-Methylene-bis(ortho-chloroaniline) is a unique curative and chain extender for isocyanate pre-polymers, and epoxy resins, characterized by extended gel times at high temperatures. Polyurea semi-rigid foams and solid hot cast elastomers produced using MOCA exhibit durability, resiliency, excellent abrasion resistance, tensile, cut, tear, compressive strength properties, and impact strength, etc. Finished products are used in wheels, tires and casters, seals and gaskets, rollers, flexible couplings, liners and padding, and a myriad of other durable elastomeric parts. Gantrade has 3 grades of MOCA and offers different physical forms to choose from, giving customer options for their equipment capability.


2-Methyl-1,3-propanediol (MPO) is a versatile liquid, non-crystallizing, short-chain diol possessing two primary hydroxyl groups. It exhibits a high boiling point of 212ºC and a very low melting point of -54ºC; this contributes to ease in handling. MPO has the same molecular weight+ and equivalent weight as 1,4-butanediol. The branched methyl moiety on MPO imparts good hydrolytic stability in polyesters and polyurethanes, while maintaining good weatherability and product durability. MPO is much less hygroscopic than BDO. In addition to applications such as an intermediate for polyesters, polyester polyols and unsaturated polyesters , this unique short chain diol has been promoted as a chain extender for MDI based pre-polymers. When compared with BDO systems, MPO systems exhibit lower hardness values, increased flexibility, greater transparency, softer feel and increased compatibility with other materials. Gantrade offers MPO in drums and bulk ISO tanks.

Non-Mercury Urethane Cure Catalysts - Zn/Bi

The non-toxic Bismuth and Zinc neodecanoate compounds are excellent urethane cure catalysts for polyurethane coatings, adhesives, sealants and cast elastomers, and foams. They are effectively used in combination with tertiary amine catalysts to replace the toxic, mercury and lead catalysts based on affording a delayed cure followed by a rapid snap cure profile, and a low catalytic effect on the reaction of an isocyanate with water.


1,3-Propanediol is a liquid primary diol used as a high reactivity chain extender for polyurethanes or an intermediate for polyester polyols. PDO is a bio-based intermediate.

Polycaprolactone Polyols

Polycaprolactone polyols are a special, high performance class of polyester polyols. The method by which polycaprolactone polyols are produced compared to standard glycol adipates determines their enhanced physical properties. Polycaprolactone polyols are formed by a ring opening of a cyclic ester - caprolactone monomer via a glycol initiator. The nature of this reaction results in a low polydispersity and narrow molecular weight distribution. The lack of the high molecular weight tail found in standard polyester polyols results in the lower viscosities in polycaprolactone polyols and better low and high temperature performance. Additionally, polycaprolactone polyols exhibit enhanced hydrolytic stability compared to standard glycol adipates because they are made under mild conditions and without acid catalysis. Additionally, since polycaprolactones are polyester polyols, they also produce polyurethane adhesives with enhanced UV resistance, excellent resistance to oils and fuels, and better abrasion resistance and tensile and tear strength compared to polyether-based polyurethane adhesives. Application areas include coatings, adhesives, sealants, cast elastomers and thermoplastic elastomers. Gantrade markets a broad line of caprolactone polyols for polyurethane elastomers.

Polyester Polyols

Polyester polyols are hydroxyl terminated polymers containing ester groups. Glycol adipate based polyurethanes exhibit excellent UV resistance, good resistance to oils and fuels, and better abrasion resistance, tensile and tear strengths compared to polyether-based polyurethane elastomers. However, polyester-based polyurethanes are more susceptible to hydrolysis and provide poor resistance to weak acids and bases compared to polyether based polyurethane elastomers. Glycol adipate polyols are formed by the condensation reaction of a glycol (diol) with a dicarboxylic acid like adipic acid. The nature of the condensation reaction results in a broad molecular weight distribution and resulting higher viscosities. Aromatic polyester polyols use phthalate diacids and afford more rigid polyurethane elastomers. Gantrade's CA6oXX line of polyester polyols provide room temperature liquidity and high hydrolytic stability.

Polyether Polyols

Polyether polyols are higher molecular weight diols and triols, etc. that contain reactive hydroxyl functionality connected by ether linkages. Polyether-based polyols react with diisocyantes to afford polyurethanes with excellent resistance to hydrolysis, acids and bases compared to polyester-based polyurethanes. Polyether-based polyurethanes are more susceptible to UV degradation and have lower resistance to oils and fuels when compared to polyester-based polyurethanes. Examples of polyether polyols are the propylene oxide based polyol (PPG) and the PTMEG high performance polyols. The PTMEG polyols exhibit excellent mechanical properties because they are exactly difunctional, unlike most other polyol classifications. Gantrade has a full line of PTMEG grades consisting of different molecular weights.


Polyureas are polymers formed by reacting a di- or polyisocyanate or isocyanate prepolymer with a diamine or a polyamine. Polyureas general afford excellent abrasion, corrosion, and environmental resistance. Fast spray coatings based on polyureas afford the highest level of surface protection, for example in lined storage tanks, pipelines and general coatings. Gantrade develops and produces commercial quantity hybrid blends that afford custom properties for your unique applications.

Polyurea Polyurethane Hybrid

Hybrid formulations can be defined as the result of a chemical reaction between an isocyanate and a mixture of polyol (or diol) and amine curatives. These formulations provide hybrid polyurethane/polyurea polymers that displays many of the same properties of a polyurea.

Polyurethane (Urethane)

Polyurethanes are polymers formed by reacting a di- or polyisocyanate or isocyanate pre-polymer with a diol and a polyol. They can be rigid or flexible materials of choice for a broad range of applications requiring resiliency, flexibility and durability. Polyurethanes exhibit excellent tensile, hardness and resiliency properties, tear strength, cut and abrasion resistance, fatigue resistance, and low-temperature performance. Polyurethane property sets are important in demanding applications like conveyor belts and conveyor components, truck-bed liners and silo liners, tubing and cable jacketing, sports equipment, wheels, off-road tires, fork-lift truck tires, marine products, and resilient coatings, etc.


An isocyanate terminated chemical compound formed by reaction of diisocyanate monomer (TDI, MDI, PPDI, etc.) and polyester, polyether or polycarbonate diol. Compared with the original diisocyanate, the prepolymer has a much higher molecular weight, a higher viscosity, a lower isocyanate content by weight, referred to as % NCO, and a lower vapor pressure. Advantages of prepolymers include a reduced exposure to diisocyanate monomer and more controlled reactivity with curatives in advancing to a higher molecular weight polymer elastomer.


Polytetramethylene Ether Glycols (PTMEG) are a high-performance polyether diol offering excellent resilience and dynamic properties of the polyurethane and superior abrasion resistance compared to PPG based polyether polyurethane. The PTMEGs contribute to the soft segment of high performance polyurethanes, hybrid polyureas, copolyesters (COPEs) and copolyamide (COPA) elastomers and Spandex fibers. PTMEG systems exhibit excellent hydrolytic stability, low-temperature properties, good resiliency and good dynamic properties. PTMEG plays a significant role in demanding applications like belts and conveyors, truck-bed liners, pipe liners and silo liners, tubing and castable jacketing, sports equipment, wheels and truck tires, and marine products, etc. Gantrade’s manufacture partner is one of the global largest PTMEG producers and we have production, warehousing facilities over Asia, North America and Europe, providing customers with top line equality, undisrupted supply and service. Gantrade markets a complete line of PTMEG molecular weight grades in drum and bulk packaging.

Spandex Fibers

Spandex fibers are a synthetic fiber known for their exceptional elasticity, significant strength and ability to return to the original shape after repeatedly stretching. They dry faster than ordinary fabrics. For these reasons, spandex is mixed with cotton or polyester fibers and used in garments and apparel. Spandex is a segmented block copolymer containing soft and hard segment networks. The soft segment is most often based on PTMEG polyols. Gantrade provides the special grade of PTMEG used to produce Spandex.


TDI-80 is an 80-20 mixture of 2,4- and 2,6- isomers and is considered the general purpose TDI.


TDI-100, is a specialty grade of TDI that contains greater than 98% of the 2,4 diisocyanate isomer. It is mainly used in the preparation of cast urethanes and in paints and coatings. One advantage of the T-100 is in the preparation of lower viscosity pre-polymers.


TDI, 2,4- and 2,6-toluene diisocyanate, is a water-white to pale yellow liquid diisocyante widely used in production of polyurethane foams and elastomers.

TDI Systems

Toluene Diisocyante TDI-Polyether systems produce polyurethane and polyurea elastomers that exhibit excellent low temperature and dynamic properties, microbial resistance and long term water resistance. TDI-Polyesters systems produce urethanes which are tough, abrasion resistant, and with excellent oil and aliphatic solvent resistance. TDI systems are usually cured with diamine and polyamine curatives. Gantrade has a wide range of curatives available for TDI systems plus custom blends for unique applications.

Thermoplastic Polyester-ethers (TPEEs/COPEs & COPA)

Polyether-ester block copolymers and polyamide-ether block copolymer formed thermoplastic elastomers are high performance engineering materials that bridge the gap between cross-linked elastomers and rigid thermoplastics. COPE & COPA are often produced with PBT resin or Nylon 11 or 12 resins modified with PTMEG polyols. They exhibit exceptional toughness, impact resistance, load bearing capacity, and low & high temperature flexibility. Applications include fuel resistant automotive parts and tubing, medical, food and pharmaceutical tubing & packaging, and flexible bags. COPEs and COPAs are processed on standard injection molding and extrusion equipment.

Thermoplastic Polyurethanes (TPUs)

Thermoplastic polyurethanes (TPU )are a unique category of polyurethane usually produced from the reaction of a diisocyanate or prepolymer and a diol(s). TPUs are melt processable when heated and hard when cooled. They are capable of being reprocessed multiple times without losing structural integrity. TPUs exhibit excellent physical properties of hot cast polyurethanes in high elongation and tensile strength, and resist solvents, chemicals and oils. They are abrasion resistant, flexible, durable elastomers typically used in footwear, wire & cable coatings, hot-melt adhesives, tubing, film and sheet, plus solvent based coatings—for example coated fabrics.

Urethane Intermediates

Urethane Intermediates are reactive components that are key building blocks in the manufacture of polyurethane elastomers. Intermediates include polyols, diol and triols, aliphatic and aromatic diamine curatives, diisocyantes, pre-polymers, etc.

Working Life

The "working life" is the amount of time a urethane or epoxy formulation remains low enough in viscosity that it can still be easily applied to a substrate or poured or into a mold in a particular application. See also Gel Time.



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