The PPG (polypropylene glycol) 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 polyols in the polyurethane market.
In polyurethanes, PPG polyether polyols exhibit excellent hydrolytic stability, good low temperature flexibility (Tg’s ~ -65°C), 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. PPG polyether types are offered in grades designed for rigid polyurethane foam, flexible polyurethane foam, elastomers and others (molded foam, microcellular foam, etc.) applications. The impressive array of PPG polyether 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:
- Rigid polyols for construction and building systems
- Rigid polyols for insulation foam materials
- High resiliency polyols for automotive seating and panels
- Flexible polyols for furniture, cushions, and bedding foam products
- Flexible polyols for packaging protective materials
- Flexible polyols for high performance footwear
- Flexible polyols for CASE markets
Other applications include sponges, heat and acoustic insulators, vibration dampening, automotive bumpers and floor covering.
The chart below segments the polyether polyol market by end-use applications.
Chemistry
PPG polyether polyols are produced by reacting propylene oxide (PO) monomer with an “initiator” (water, glycerin, sorbitol, sucrose, amines, etc.) under catalytic conditions. The multifunctional initiators allow the production of very high functionality polyols, a unique feature of the polyether polyols. Molecular weight of these polyether polyols varies from about 300 to as high as 6000.
Potassium hydroxide has been the traditional catalyst used to produce PPG polyols. DMC catalyst technology based on Double Metal Cyanides has been introduced to allow the production of high molecular weight PPG polyols with a much higher hydroxyl end functionality. Ethylene oxide is often used to end-cap or “tip” the PPG polyols to afford the more reactive primary hydroxyl end-group functionality.
The basic chemical structure and the synthetic routes to PPG polyether polyols are shown below. The structure below shows the secondary hydroxyl functionality of PPG polyols, which accounts for their lower reactivity with isocyanates.
Gantrade’s partner in PPG polyols, Pucore USA Inc, uses an environmentally clean and cost effective technology to produce the raw material propylene oxide, based on hydrogen peroxide.
Polyol Functionality and End-Use Applications
The hydroxyl functionality of the polyether polyols refers to the number of hydroxyl (-OH) moieties per molecule and can range from diols to six (sorbitol initiated) and eight (sucrose initiated) functional end-groups. Initiators such as amines (ethylenediamine or triethanol amine) afford triols and tetraols respectively that are self-catalyzing and react faster than the standard polyol initiated PPG polyols. Amine base polyols are used in rigid foam applications.
The 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 1.8-30 are used in flexible foams and CASE elastomers. High functionality PPG 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 polyol functionalities.
| Hydroxyl Functionality | Flexible Foam | Rigid Foam | CASE |
| 2 | ★★ | ★ | ★★ |
| 3 | ★★ | ★★ | ★ |
| 4 | ★★ | ★★ | - |
| 6 | ★ | ★★ | - |
| 8 | - | ★★ | - |
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).
PPG Polyether Polyol Grades - Gantrade
Gantrade’s grade slate of PPG based polyether polyol is provided below. This extensive product line is produced by Pucore in Korea. Competitive advantages offered by Gantrade’s partner, Pucore, include the following:
- Pucore is a leading company in polyurethanes, committed to sustainable technologies
- Backward integrated to propylene oxide (PO) monomer
- The PO monomer process is cost-effective and co-monomer free, using hydrogen peroxide (H2O2)
- Pucore’s plants are new, environmentally friendly, and highly reliable
- The grade slate is very broad
- Unique grades with molecular weights up to 5000, with 8000 MW grades available
Our product line includes PPG polyols designed for flexible slab foam, flexible molded foam, rigid foam and CASE (Coatings, Adhesives, Sealants and Elastomers) markets. PPG polyols for CASE applications are lower in moisture values with higher end-hydroxyl functionality.
Summary
The PPG (polypropylene glycol) family of polyether polyols are the most widely used and versatile group of polyols in polyurethane elastomers. In polyurethanes, PPG polyols exhibit excellent hydrolytic stability, good low temperature flexibility (Tg’s ~ -65°C), 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.
Gantrade’s extensive product line of PPG based polyether polyol is produced by Pucore. Competitive advantages include a very broad range of grades and molecular architectures, including molecular weights in the 5000-8000 range. The propylene oxide monomer technology, based on hydrogen peroxide, is environmentally friendly, cost effective and highly reliable.
PPG polyethers are offered in grades designed for rigid polyurethane foam, flexible polyurethane foam, molded foam and cast elastomers applications. The extensive array of PPG polyether functionalities and molecular weights allow tailoring of polyurethane properties to specific requirements in multiple industries.
To explore how our range of urethane intermediates can address your unique polyurethane elastomer applications, partner with Gantrade Corporation. Our expert teams, armed with a wealth of technical knowledge and experience, can guide you to the best solutions for your applications. Our global supply chain means high-quality chemical products where you need them when you need them.
