Gantrade’s Urethane Polyols Platform

Gantrade’s Urethane Polyols Platform

Gantrade offers the broadest portfolio of polyols to the polyurethane’s industry.  We are a global leader in the distribution of high-performance, general purpose and “green’ polyols for a wide variety of performance enhancements within multiple urethane industry applications.  Our broad polyols platform includes polyether polyols, polyester polyols, polycarbonate polyols, and bio-based polyols as delineated below.

Gantrade’s technical knowledge and expertise, along with our uncompromising standards for customer service, ensure the best polyurethane solutions for your applications. Our global supply chain means high-quality urethane intermediates where you need them, when you need them. 

Described below are the attributes of the individual categories in our polyol product lines.  Selecting the best polyol for specific formula can be the difference between making a high-quality product or a low performance one. The key for making a proper material choice is a good understanding of the inherent characteristics of each polyol chemistry. Our selection criteria includes economics and the performance attributes required in the polyurethane elastomer.  

Polyether Polyols

The two major families of polyether polyols are the polypropylene glycols (PPG) and the  polytetramethylene ether glycols (PTMEG). Both the PPG and PTMEG impart good low temperature properties and excellent hydrolytic stability to polyurethane elastomers.   Both polyether classes exhibit very low Tg’s in the soft segment of polyurethanes.  The Tg of PTMEG polyol (Tg  ~ 75°C) is lower than that of PPG polyols (~60°C).  PTMEG is the premier polyol used in high-performance polyurethane elastomers.  Polypropylene glycol polyether polyols (PPG polyols) have many of the attributes of PTMEG polyols in polyurethanes, however, when compared to PTMEG polyols, the PPG polyols have lower physical properties and are more prone to thermo-oxidative degradation.

The chart below segments the polyether polyol market by end-use applications.

PPG Polyols

The polypropylene glycol polyether polyols are core building blocks used in the production of polyurethanes for an endless range of applications.  This family of polyether polyols are the most widely used and versatile group of polyols in polyurethanes, accounting for over 70% of the consumption of all polyols in the polyurethane market.  

In polyurethanes, PPG type polyether polyols exhibit excellent hydrolytic stability, good low temperature flexibility, a broad range of hardness values, durability, good resistance to weak acids and bases, ease of handling (liquids at ambient temperatures and low viscosities) and the lowest relative costs. The impressive array of polyether polyol functionalities and molecular weights permits tailoring of polyurethane properties to specific requirements in multiple industries.

The many different application platforms for polyether polyols include the following:

• Flexible polyols for furniture, cushions, and bedding foam products 
• Flexible polyols for CASE markets
• Flexible polyols for packaging protective materials
• Flexible polyols for high performance footwear
• High resiliency polyols for automotive seating and panels
• Rigid polyols for construction and building systems 
• Rigid polyols for insulation foam materials
• Molded foam and microcellular foam

Unlike the PTMEG family of diols, the PPG based polyols are available with functionalities up to six and above, and with high molecular weights.  Functionality of the polyols control properties such as hardness and processing characteristics.  Higher functionalities afford greater crosslinking, which yields harder, more rigid polyurethanes with enhanced thermal and chemical resistance.  Polyols with a molecular weight between 500 and 6000 and functionalities of 2-3 are used in flexible foams and CASE elastomers.  High functionality polyether polyols afford highly crosslinked rigid polyurethanes and are used in rigid foam applications and high-performance coatings.

The chart below outlines the general application arenas associated with the various PPG polyol functionalities.

In a foam, polyol functionality also affects foam density, foam cell size, gel times, tack-free times, shrinkage, and foam properties such as thermal conductivity (insulation characteristics).  

For a listing of our PPG polyol grades, please see our associated blog:  https://www.gantrade.com/blog/ppg-polyether-polyols

PTMEG Polyols

PTMEG is the premier polyol used in high-performance polyurethane elastomers. PTMEG-based polyurethanes are known for superior resistance to hydrolytic cleavage, good mechanical properties retention at low temperature, high rebound and resiliency, good processing characteristics and excellent mechanical and dynamic properties.  PTMEG polymers comply with a number of FDA regulations covering adhesives and coatings used in indirect food applications.

Processors know PTMEG as a high-performance polyol capable of formulating polyurethane elastomers in several positive directions. PTMEG will enhance polyurethane elastomer performance with respect to flexibility, dynamic properties, resiliency/rebound, hydrolytic stability, and abrasion resistance.   The unique attributes of the PTMEG polyols in polyurethanes are delineated below.

PTMEG-based polyurethanes exhibit the following attributes:

Strain-induced crystallization of the PTMEG soft segments, exact difunctionality and low acid values are all contributing factors to the superior mechanical properties of the associated polyurethane elastomers. This makes PTMEG the material of choice for processors specializing in wheels, belts, tires, tubing, abrasion resistant surfaces, elastic fibers (Spandex) and many other products. The PTMEG polyols represent about 6% of the total polyurethanes market for polyols.

The table below compares the key characteristics and properties of PTMEG and PPG polyols:

For more information on our comprehensive PTMEG product line, please see: https://www.gantrade.com/blog/premier-polyether-polyol-polytetramethylene-ether-glycol-ptmeg

Aromatic Polyether Polyols

Bakelite Synthetics has commercialized a family of aromatic polyether polyols that provide substantial advantages in both polyurethane and polyisocyanurate (PIR) foam. These aromatic polyether polyols contain primary aliphatic hydroxyl functionality and have an aromatic content of 33 percent. Gantrade has joined with Bakelite Synthetics to translate the performance attributes of the Resonance™ Aromatic Polyether Polyols into the CASE marketplace.

Aromatic polyether polyols offer significant potential product improvements to formulators in the coatings, adhesives, sealants, and elastomers (CASE) arena. These polyols have many attributes, as they improve flammability resistance, thermal performance, hydrolytic stability, and mechanical properties of polyurethanes and polyureas.

Resonance Aromatic Polyether Polyol-based polyurethanes exhibit the following attributes. Relevant to performance and processing in the CASE market, these attributes include the following:

• Significantly higher aromaticity than traditional polyols—33% aromaticity
• Potential to improved flammability characteristics of PURs
• Good compatibility with other commonly used polyols
• Primary hydroxyl end functionality with good isocyanate reactivity
• Low acid values—Less than 0.15 mg KOH/g
• Low color
• Liquids at room temperatures
• Hydroxyl functionalities of 2.4-3.6

Polyester Polyols

Compared to polyether polyols in polyurethane elastomers, polyesters offer higher physical properties, cut, tear and wear resistance, better sliding abrasion and flex fatigue resistance.  They are tough and durable. Polyester polyols in a polyurethane also exhibit very good resistance to oil, grease, fuels and nonpolar solvents.  The polyester backbone displays good thermo-oxidative stability which makes them better suited for high-temperature application. Thus, polyester based urethane parts, are used for their strength properties and toughness, durability, performance at higher temperatures and retention of properties under adverse chemical and environmental exposures. Polycaprolactone polyols and polycarbonate diols represent the ultimate generation of performance polyester diols for polyurethane elastomers, albeit, higher in cost.

Polyester based urethane elastomers also show good adhesion to commonly used substrates.  Polyester polyols are preferred where vibration damping, and shock absorption properties are required.

The charts below show the major markets for aliphatic polyester polyols. In the elastomers space, footwear and shoe soles are the largest segments.  Polyester polyols represent about 20% of the total polyols use in polyurethanes.

Aliphatic Polyester Polyols

Aliphatic polyester polyols are engineered using a variety of dicarboxylic acids, mainly adipic acid, and diols, in a broad range of molecular weights, enabling formulators to customize to desired properties.  Diols range from neopentyl glycol (NPG) and 2-methyl-1,3-propane diol (MPO) for increased hydrolytic stability and amorphous characteristics, to ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), butanediol (BDO), hexanediol (HDO) and co-diol polyol EG/BDO copolyester.  Adipate glycol polyesters are FDA-compliant, which makes them a good option for urethane articles safe to use in food contact applications.

Aromatic Polyester Polyols

Aromatic polyester polyols are manufactured by using low-cost building blocks including phthalic anhydride as the “diacid” with terephthalic acid or crude recycled polyethylene terephthalate.  They are esterified with an excess of low cost standard diols such as EG, DEG and PEG, etc.  Aromatic polyester polyols exhibit good hardness values, abrasion resistance and hydrolytic stability.  Higher functionality is achieved by incorporating TMP or pentaerythritol (PENTA) to improve chemical resistance.  Aromatic polyester polyols are a critical component of polyurethane and polyisocyanurate foam systems.  The high aromatic contents of these diols allow for lower levels of flame retardant additives required in the building and construction foam market.

Polycaprolactones Polyols 

Polycaprolactone polyols comprise a special class of aliphatic polyester polyols, used as the soft block segment of high-performance polyurethane elastomers.  We can produce polycaprolactone polyols with very low acid values (increasing hydrolytic stability and controlled reactivity); perfect end-group functionality (controlled reactivity and improved network formation); narrow molecular weight distributions (low viscosity including in the prepolymer form), and low Tg’s (flexibility at low temperatures). Polycaprolactone based polyurethanes incorporate many of the benefits assigned to PTMEG polyols, albeit at a higher cost.  Polycaprolactone polyol exhibit good hydrolytic stability in wet environments, low temperature flexibility, excellent toughness and abrasion resistance, excellent flex fatigue life, durability and good elastic memory. In addition, polycaprolactone based PURs are much tougher materials than polyether-based PURs and exhibit higher temperature properties.

Polycaprolactone-based polyurethanes exhibit the following attributes:

The chart below is a qualitative delineation of the relative performance of PTMEG and polycaprolactone polyols in polyurethane elastomers.   The designation of “Best-in-Class” refers to the highest performance within the general classifications of polyurethanes.

Structure-Property Profiles of Polyurethane Elastomers vs. PCL vs. PTMEG Diols

      B = Best-in-Class; E = Excellent; VG = Very Good; G = Good

Polycarbonate Polyols 

The polycarbonate diols, the subject of this article, represent the next generation of ultimate performance diols for polyurethane elastomers. Their combination of high resistance to heat, hydrolysis, weather, and abrasion, aging stability, consistent performance and extreme durability is unattainable by other polyols. While cost is a major consideration in the selection of the soft-block polyol in tailoring the property profiles of polyurethanes, performance often overrides cost concerns.  Polycarbonate diols are increasingly used in polyurethane coatings, adhesives, and cast elastomer applications requiring extreme durability, due to their performance-based properties.  Specific application arenas include waterborne polyurethane dispersions, oil field and mining polyurethane cast parts, pipe linings and exterior coatings, electrical/electronic encapsulation, artificial leather coatings, optical devices, medical devices, elastomeric rollers and thermoplastic polyurethanes (TPUs). 

From a market perspective, polycarbonate diols can be subdivided into crystalline-solid type polyols and liquid type co-polycarbonate diols, with the solid-type diols holding the higher market share at about 65 percent.

Attributes of Polycarbonate Diols in Polyurethanes:

• Excellent hydrolytic stability (except in base) & low water absorption
• Maximum temperature stability; low-temperature flexibility
• High chemical & oil resistance
• Weatherability & UV resistance
• Superior environmental stress crack resistance
• Low yellowing and high gloss retention
• Superior durability, impact, and abrasion resistance
• High mechanical properties
• Long-term retention of designed properties in aggressive environments

Polycarbonate diols exhibit significantly better hydrolytic stability than their adipate polyester polyol counterparts. The figure below compares the tensile strength retention of a 2000 MW crystalline polycarbonate diol against other polyols families at the same molecular weight in MDI based TPUs, 1,4-BDO chain extended.  Tensile properties were measured on TPU pieces soaked in water at 80 °C for three weeks and four weeks.  Particularly noteworthy is the high hydrolysis-resistance of the polycarbonate based polyurethane. Also shown in the figure is a polycaprolactone diol, PTMEG polyol and a 1.6-hexanediol adipate.  The tensile strength of the HDO-PC was relatively unchanged versus the comparable data for the other polyol families.

For additional information on our polycarbonate diols, please refer to:  https://www.gantrade.com/blog/ultimate-performance-polyurethanes-based-on-polycarbonate-diols

Bio-Based Polyols

As consumer demand for “green” sustainable products increases, Gantrade has developed a family of polyether and polyester polyols derived from 100% bio-renewable sourced raw materials for application in the performance segment of polyurethane elastomers. Our emphasis has been on utilizing bio-based raw materials that produce durable and high-strength polyurethane elastomers with superior performance attributes and good processing characteristics.  Gantrade’s poly(trimethylene ether) glycol PO3G and green polyester polyols meet these goals. 

Polyether Polyols 

Reference: Fei Ping, ct. al., Polymer, 239 (2022)

The following performance attributes are exhibited by PO3G polyols in MDI-based, TDI-based, and aliphatic isocyanate-based elastomers: 

Attributes of Poly(trimethylene ether) glycol in Polyurethanes:

• Superior resistance to hydrolytic cleavage
• Exceptional flexibility and property retention at low temperatures
• High resiliency and rebound properties
• Excellent mechanical and dynamic properties, and low hysteresis
• High abrasion and wear resistance
• Good cut, chip, and tear resistance
• Durability in performance applications
  
  

Examples of end-use markets include the following.

• High-load wheels and rollers such as skate and amusement park wheels
• Mining and oil field equipment
• Coatings for synthetic leather and textiles used in automotive and furniture
• Performance Coatings, including waterborne polyurethane dispersions (PUDs)
• Adhesives, sealants, and binders
• Ink-jet formulations
• Sport shoes and waterproof, breathable textiles
• Synthetic leather goods
• Elastic fibers

The PO3G-based polyurethanes are very well suited to the most demanding applications found in the high-performance segments of the elastomers industry. 

Polyester Polyols 

Our range of bio-based polyester polyols are produced from combinations of bio-based sebacic acid and bio-based succinic acid as the aliphatic diacids, and bio-based 1,3-propanediol, neopentyl glycol and 1,4-butanediol as the diols.  These polyols have 100% renewable content.  Sebacic acid is a natural C10 linear fatty acid, derived from castor oil.  Bio-PDO, bio-BDO and bio-succinic acid are all produced by fermentation of renewable feedstocks.

The matrix below shows the polyester polyol composition alternatives offered.  The product nomenclature and physical properties are shown for 2000 MW polyols.  Available molecular weight grades range from 1000 to 4000 g/mol.  The combinations below allow the tailoring of a broad range of urethane elastomer property sets.

To meet the need for bio-content polyols which are liquids at room temperature, CA-D620SZX was produced from bio-sebacic acid and bio-based 1,3-propane diol, and 2-methyl-1,3-propanediol.  This 2000 MW linear polyester polyol remains a liquid at room temperature, exhibits a Tg at -51°C.  The total bio-content is about 83%.

Sebacate polyol elastomers display increased hydrophobic characteristics due to the long C10 chains in the sebacic acid.  Sebacic acid polyol/MDI systems, chain extended with BDO, exhibit better hydrolysis, acid and alkali resistance, tear and abrasion resistance, thermal performance, and metal adhesion vs. adipate polyols.  Hydrolytic stability in a major advantage of the sebacate polyols based polyurethane elastomers.  In TPUs, the PDO sebacate-2000 required a lower processing temperature vs. adipates and shorter demold times, which leads to processing improvements. The performance characteristics of sebacate polyols in polyurethane elastomers can be comparable to that of polycarbonate diol polyurethane elastomers.

All sebacic acid polyesters exhibit all excellent hydrolytic stability.  The chart below compares the hydrolytic stability of various adipate polyester polyols against a 2000 MW PDO sebacate polyol (PDO/SA).  The NPG sebacate exhibits the same excellent hydrolytic stability.  In the accelerated hot water degradation method, the polyol is mixed with 10 wt. % water and subjected to heating at 90°C for a twelve-hour period.  Relative hydrolytic resistance is determined by titration of acidic moieties generated through hydrolysis.  The comparative rates of acid generation demonstrate the greater resistance to hydrolysis of sebacic acid-based polyols.

Applications for our bio-based polyester polyols include protective coatings and pipe linings, hot melt adhesives, sealants, printing inks, textile and leather coatings, footwear and apparel, waterproof breathable films, performance textiles, cast polyurethane elastomers, thermoplastic polyurethanes (TPU), polyurethane dispersions (PUDs) and polyurethane foams.

For a listing of our bio-based polyester polyols product lines, please see our associated blog https://www.gantrade.com/blog/bio-based-polyester-polyols-for-performance-polyurethane-elastomers

To explore which polyols are best suited for your unique needs, partner with Gantrade. Our team’s wealth of technical knowledge and expertise ensure that you will receive the best polyurethane solutions for your applications. Gantrade’s urethane platform provides a broad range of possibilities to achieve your high-performance polyurethane requirements. Contact Gantrade today or request an associated brochure on the product lines represented above.