Gary Shawhan and Dave Sikora, Chemark Consulting02.16.22
This is Part 3 of a 3-part article on sustainability and the challenges facing many markets, including CASE, in finding commercial sources of supply for bio-based polymer raw materials. In Part 3, we will focus on the chemical options for manufacturing the remainder of the resin/polymer categories from bio-based sources. These are listed in Table 1.
We will also examine the potential chemical routes to commercial production of new bio-based polymer types. This includes an assessment of the current global efforts to bring new commercial products to market in each of the above polymer families from both the existing and new emerging sources of supply.
Finally, some observations and general conclusions are offered on the present situation and future prospects for new sources of bio-based chemicals. Comments are also included on the drivers that are present in industry that will continue to push markets toward greater use of bio-based polymers. In this regard, we comment on the expected impact of cost for bio-based chemical alternatives based on the event of the last two years.
Aromatic Polyester Polymers
Aromatic polyesters (in this discussion) refer to those polyesters that are derived from petrochemically-based terephthalic acid/dimethyl ester (PTA/DMT) or those manufactured from the bio-based furan dicarboxylic acid/dimethyl ester (FDCA/FDME). Due to the pervasive use of plastic beverage bottles, polyethylene terephthalate (PET) is the leading aromatic polyester. Following PET in market demand is the engineering thermoplastic, polybutylene terephthalate (PBT).
Due to PBT’s key mechanical, thermal, and electrical properties, it is ideally suited for use in automobiles, electrical equipment, and electronic devices. As car manufacturers seek to make lighter weight vehicles to improve fuel economy or accommodate the growth in electric vehicles, PBT has been continually sought to replace heavier weight materials.
Due to PBT’s electrical properties, growth in its use is also anticipated in electric vehicles. Applications include various parts not found in internal combustion engine but required for battery powered vehicles. Thus, volume production of bio-1,4-butanediol (BDO) for PBT would be favored by automakers as they seek to reach sustainability targets in new, future vehicles.
New to the polyester family is the DuPont-developed and commercialized polytrimethylene terephthalate (PTT), Sorona®. While PET is purely petrochemically-based, PBT and PTT are bio-petro hybrids due to the availability of bio-BDO and bio-1,3-propanediol (PDO). Amongst petrochemically-based terephthalic acid/dimethyl ester (PTA/DMT) manufacturers and the users of such esters, there is an intense effort being put forth to develop bio-based para-xylene, the precursor to PTA/DMT. Consortia have been formed to expedite this development. Sorona is mainly used in fiber form for apparel and carpets.
DuPont and Archer Daniels Midland, in their joint efforts to build a platform for producing 100% bio-based polymers, have collaborated to manufacture furan dicarboxylic methyl ester (FDME). This is a derivative of fructose-derived furan dicarboxylic acid (FDCA). These furan-based materials might be thought of as “pseudo surrogates” for petrochemical-based DMT and PTA, respectively.
In combination with the bio-diols 1,3-PDO, BDO, 1,5-PDO, and corn-based diol isosorbide, a dramatic number of bio-based polyester possibilities can be imagined. Individually, these polymers can be engineered to address various physical and performance property profiles needed to satisfy specific application requirements.
The furan moiety of these polymers imparts superior gas barrier properties relative to terephthalate. As its first endeavor (for this platform), DuPont and Archer Daniels Midland are developing polytrimethylene furan dicarboxylate (PTF) for use in packaging and beverage bottles and as a potential substitute for PET. Due to polymerization of furan dicarboxylic methyl ester (FDME) with bio-1,3-propanediol, it is made totally from renewable resources.
As a substitute for PET, the Dutch company Avantium has developed a polyester based on fructose-derived furan dicarboxylic acid (FDCA) and monoethylene glycol (MEG), polyethylene furanoate (PEF). Again, due to the furan moiety contributing to excellent gas barrier properties, PEF is aimed at the beverage bottle market.
While MEG is petro-derived, Avantium, Haldor-Topsoe, and Braskem are aggressively exploring sugar-based MEG where the fermentation product, ethanol, is dehydrated to ethylene, and subsequently oxidized to MEG.
For polyester coil coatings, a UK industrial-academic collaboration is exploring polyesters based on FDCA, succinic acid, isosorbide, 1,3-propanediol and 1,5-pentanediol. The fructose-derived furan dicarboxylic acid (FDCA) and the furan dicarboxylic methyl ester (FDME) provide industry with a starburst of possibilities for new polyamides, polyester polyols for PU, and plasticizers, used in combination with new polymers for markets beyond packaging.
Aliphatic Polyester Polymers
A whole myriad of aliphatic polyester polymers (higher MW than polyester polyols) can be tailor made to achieve desired physical and performance properties. This is accomplished by varying the diol and diacid type, the molar ratio thereof, the mode of addition, together with rigorous control of condensation polymerization temperature, pressure, and time.
A very notable aliphatic polyester is polybutylene succinate (PBS) due to its biodegradability. While originally produced from petro succinic acid and bio-1,4-butanediol (BDO), it is marketed for plastic tableware and other meal utensils, food packaging, agricultural film, and outdoor products. Polymerization of bio-succinic acid and bio-BDO would provide a biodegradable, bio-based PBS. Bio-PBS™ is produced by a JV of Mitsubishi and the Thailand-based PTT Global Chemical.
Lactic acid, a purely bio-based chemical derived from various carbohydrates, which contains both hydroxyl and carboxylic acid functionality, undergoes self-condensation polymerization or ring opening polymerization of its dimer, lactide, to form polylactic acid, (PLA). PLA is not only the most recognized aliphatic polyester (polylactic acid is actually a misnomer for polylactide), but also probably the most recognized bio-based polymeric material in use to date.
Developed and commercialized by both Corbion-Purac and NatureWorks (JV of Cargill and PTT Global Chemical) polylactic acid is probably the earliest success story in the bio-based chemical arena. PLA is used in resins, films, and fiber forms. It has a wide array of applications, particularly, in packaging, biodegradable medical devices, apparel, and agricultural products. Perhaps the most recent use of PLA is as a printable filament for 3D printings. PLA can be blended with various polymers to expand physical and performance properties. For example, blending with ABS can impact the engineering plastic characteristics to address application requirements.
Acrylic Acid and Derivatives
For many years, an effective biochemical route to acrylic acid remained elusive, particularly from 3-hydroxypropionic acid. Proctor & Gamble took a different approach. They developed and patented award-winning breakthrough technology which dehydrates lactic acid to acrylic. Cargill obtained an exclusive license from P&G and are now in partnership with the French companies, Axens and IFP Energies Nouvelles to further develop, scale-up, and commercialize the technology.
Bio-based acrylic acid has been the basis for not only the large array of acrylic/acrylate polymers, but also many bio-based acrylate diol monomers readily used in UV/EB curing of inks and coating. Fully bio-based polymer examples could include 1,5-pentanediol diacrylate, BDO diacrylate, isosorbide diacrylate, and soya oil polyol acrylates as made from soya oil polyols (as noted in the polyurethanes section).
Also, academic researchers have prepared oligolactide diacrylates and tested them in UV-curable printing inks. These are 100% bio-based polymers. Bio-vinyl ester resins and reactive vinyl monomers like diol diacrylates, have been formed via the esterification of bio acrylic acid with bio epoxy resins, (diglycidyl ether, see below).
Biochemical routes to date for methacrylic acid (MA) have proven to be challenging and difficult. Direct routes from sugar have been investigated. However, the optimal route(s) for success first involve the fermentation of sugar to various MA intermediates followed by subsequent chemical reactions for ultimate conversion to MA. A successful pathway to producing bio-methacrylic acid will enable much of the similar chemistry to the aforementioned derivatives for acrylic acid.
Epoxies and Derivatives
Epichlorohydrin (ECH) is industrially produced starting with propylene. However, bio ECH (Epicerol®) has been developed by Solvay and commercialized by the Solvay subsidiary, Advanced Biochemical Thailand Co (ABT) via glycerol derived from plant oil triglycerides. Their plant in Thailand was recently expanded to 120,000 tpa.
Due to the wide use of ECH as a raw material for manufacturing the epoxy scaffold, this commercial facility opens the way for enabling many bio-based diglycidyl ether monomers. This includes those derived from the bio diols, isosorbide, BDO, and 1,5-pentanediol. Isosorbide has been frequently mentioned as an effective substitute for BPA in epoxy resins. Furthermore, reaction of such bio-diglycidyl ethers with bio acrylic acid would potentially enable the manufacture of 100% bio-vinyl ester resins.
Epoxidized soybean oil (ESBO), itself is not only capable of serving as a poly epoxide itself, but also, the epoxide moieties (in ESBO) can serve as reactive sites for bio-acrylic acid yielding 100% bio-vinyl ester resins.
Industrially Useful Chemicals that are Best Synthesized From Biomass
Perhaps with the exception of glycerol, soya oils, FDCA, lactic acid, and isosorbide, the vast majority of bio-based chemicals are seen as having petrochemical sources. While many pharmaceuticals and amino acids have been traditionally made from biomass, it is noteworthy that there are some industrial chemicals that are best made from biomass and would be difficult to synthesize from petrochemicals. Two illustrative, pertinent examples are 9-decenoic acid methyl ester (9-DAME) and farnesene commercialized by Elevance Renewable Sciences and Amyris, respectively.
Elevance has elegantly exploited Nobel award-winning olefin metathesis chemistry to make products that are difficult to make by traditional organic synthetic methods. Exemplary is the metathesis of the unsaturated fatty acid, oleic acid, with ethylene to 9-DAME, a dual functionality 10-carbon molecule which contains a double bond at one end and an ester group at the other end. This uniqueness enables, for example, reaction with olefin-, ester-, and amine-containing polymers with the potential to form a whole myriad of previously unknown products.
Additionally, bio-1-decene (alpha decene), an alpha olefin, is produced as a co-product of this metathesis technology. Such alpha olefins are capable of an enormous number of chemical reactions potentially leading to a whole host of bio-based products for synthetic lubricants, cleaning products, cosmetics, oil field chemicals, and plasticizers to name a few.
Farnesene, made from sugar fermentation, is a very unique 15 carbon molecule containing 3 carbon-carbon double bonds thereby used as a building block for surfactants, fragrances, coatings, adhesives, sealants, and crop protection chemicals.
Observations and Conclusions Sources for Bio-based Chemicals
The number of actual commercial sources for bio-based chemicals is still limited but growing. This three-part article identifies a number of commercial ventures either in production or in various stages of planning or commercial development that are intended to meet this emerging demand for bio-based chemicals.
One aspect of the efforts to commercialize production of bio-based raw materials and polymers is to consider the primary markets for which these efforts are intended. In many cases, these commercial ventures are focused on large, non-coating related markets such as plastics, packaging films, and textiles. Coatings may benefit from these ventures but not necessarily from their being the primary business objective. CASE market applications will have a “fit,” but the intent to commercialize production of new, bio-based chemicals is often not guided by the specific needs of the coatings market.
In the individual discussions on bio-based chemicals (in this article), a number of potential and undeveloped routes to producing bio-based chemicals are identified. As indicated in the article, there are many new pathways and approaches to producing bio-based alternatives which can be brought forth to manufacture commercial volumes of bio-based chemicals. As the demand continues to grow for bio-based chemicals in the CASE markets, more of these commercial ventures will be tailored to the specific needs of this market space.
Drivers of Sustainability Initiatives
Led by many major corporations in the chemical industry, including the major global coatings manufacturers, definitive sustainability initiatives are being implemented with the goal of meeting the net-zero carbon footprint target by 2050. Target dates are being announced for partial and eventual 100% compliance with the Paris accords.
OEMs are now setting timelines for coatings manufacturers to provide new products that deliver a certain percentage level of bio-based content in their coating formulation. These proclamations are tied to corporate sustainability initiatives and the necessity for the larger global industry players to demonstrate their leadership in supporting this effort. The same can be said for the large global coating manufacturers, resin manufacturers, and other raw material suppliers who are struggling to find ways to respond to the increasing demand for greater bio-based chemical content in their products.
Cost Impact For Bio-based Alternatives
Putting aside the availability or viable sources for bio-based polymers, their cost has long been considered as a key barrier to their acceptance in commercial markets. The events of the last two years as a result of the COVID pandemic have, however, created a paradigm shift in industry with respect to resin prices.
Partly driven by supply chain interruption and vacillations in crude oil prices, resin prices have escalated far beyond what they were two years ago. The consequence of this has been price escalations throughout the supply chain. In turn, these events have resulted in less resistance and more tolerance for incorporating bio-based chemical content into next generation coating formulations.
We will also examine the potential chemical routes to commercial production of new bio-based polymer types. This includes an assessment of the current global efforts to bring new commercial products to market in each of the above polymer families from both the existing and new emerging sources of supply.
Finally, some observations and general conclusions are offered on the present situation and future prospects for new sources of bio-based chemicals. Comments are also included on the drivers that are present in industry that will continue to push markets toward greater use of bio-based polymers. In this regard, we comment on the expected impact of cost for bio-based chemical alternatives based on the event of the last two years.
Aromatic Polyester Polymers
Aromatic polyesters (in this discussion) refer to those polyesters that are derived from petrochemically-based terephthalic acid/dimethyl ester (PTA/DMT) or those manufactured from the bio-based furan dicarboxylic acid/dimethyl ester (FDCA/FDME). Due to the pervasive use of plastic beverage bottles, polyethylene terephthalate (PET) is the leading aromatic polyester. Following PET in market demand is the engineering thermoplastic, polybutylene terephthalate (PBT).
Due to PBT’s key mechanical, thermal, and electrical properties, it is ideally suited for use in automobiles, electrical equipment, and electronic devices. As car manufacturers seek to make lighter weight vehicles to improve fuel economy or accommodate the growth in electric vehicles, PBT has been continually sought to replace heavier weight materials.
Due to PBT’s electrical properties, growth in its use is also anticipated in electric vehicles. Applications include various parts not found in internal combustion engine but required for battery powered vehicles. Thus, volume production of bio-1,4-butanediol (BDO) for PBT would be favored by automakers as they seek to reach sustainability targets in new, future vehicles.
New to the polyester family is the DuPont-developed and commercialized polytrimethylene terephthalate (PTT), Sorona®. While PET is purely petrochemically-based, PBT and PTT are bio-petro hybrids due to the availability of bio-BDO and bio-1,3-propanediol (PDO). Amongst petrochemically-based terephthalic acid/dimethyl ester (PTA/DMT) manufacturers and the users of such esters, there is an intense effort being put forth to develop bio-based para-xylene, the precursor to PTA/DMT. Consortia have been formed to expedite this development. Sorona is mainly used in fiber form for apparel and carpets.
DuPont and Archer Daniels Midland, in their joint efforts to build a platform for producing 100% bio-based polymers, have collaborated to manufacture furan dicarboxylic methyl ester (FDME). This is a derivative of fructose-derived furan dicarboxylic acid (FDCA). These furan-based materials might be thought of as “pseudo surrogates” for petrochemical-based DMT and PTA, respectively.
In combination with the bio-diols 1,3-PDO, BDO, 1,5-PDO, and corn-based diol isosorbide, a dramatic number of bio-based polyester possibilities can be imagined. Individually, these polymers can be engineered to address various physical and performance property profiles needed to satisfy specific application requirements.
The furan moiety of these polymers imparts superior gas barrier properties relative to terephthalate. As its first endeavor (for this platform), DuPont and Archer Daniels Midland are developing polytrimethylene furan dicarboxylate (PTF) for use in packaging and beverage bottles and as a potential substitute for PET. Due to polymerization of furan dicarboxylic methyl ester (FDME) with bio-1,3-propanediol, it is made totally from renewable resources.
As a substitute for PET, the Dutch company Avantium has developed a polyester based on fructose-derived furan dicarboxylic acid (FDCA) and monoethylene glycol (MEG), polyethylene furanoate (PEF). Again, due to the furan moiety contributing to excellent gas barrier properties, PEF is aimed at the beverage bottle market.
While MEG is petro-derived, Avantium, Haldor-Topsoe, and Braskem are aggressively exploring sugar-based MEG where the fermentation product, ethanol, is dehydrated to ethylene, and subsequently oxidized to MEG.
For polyester coil coatings, a UK industrial-academic collaboration is exploring polyesters based on FDCA, succinic acid, isosorbide, 1,3-propanediol and 1,5-pentanediol. The fructose-derived furan dicarboxylic acid (FDCA) and the furan dicarboxylic methyl ester (FDME) provide industry with a starburst of possibilities for new polyamides, polyester polyols for PU, and plasticizers, used in combination with new polymers for markets beyond packaging.
Aliphatic Polyester Polymers
A whole myriad of aliphatic polyester polymers (higher MW than polyester polyols) can be tailor made to achieve desired physical and performance properties. This is accomplished by varying the diol and diacid type, the molar ratio thereof, the mode of addition, together with rigorous control of condensation polymerization temperature, pressure, and time.
A very notable aliphatic polyester is polybutylene succinate (PBS) due to its biodegradability. While originally produced from petro succinic acid and bio-1,4-butanediol (BDO), it is marketed for plastic tableware and other meal utensils, food packaging, agricultural film, and outdoor products. Polymerization of bio-succinic acid and bio-BDO would provide a biodegradable, bio-based PBS. Bio-PBS™ is produced by a JV of Mitsubishi and the Thailand-based PTT Global Chemical.
Lactic acid, a purely bio-based chemical derived from various carbohydrates, which contains both hydroxyl and carboxylic acid functionality, undergoes self-condensation polymerization or ring opening polymerization of its dimer, lactide, to form polylactic acid, (PLA). PLA is not only the most recognized aliphatic polyester (polylactic acid is actually a misnomer for polylactide), but also probably the most recognized bio-based polymeric material in use to date.
Developed and commercialized by both Corbion-Purac and NatureWorks (JV of Cargill and PTT Global Chemical) polylactic acid is probably the earliest success story in the bio-based chemical arena. PLA is used in resins, films, and fiber forms. It has a wide array of applications, particularly, in packaging, biodegradable medical devices, apparel, and agricultural products. Perhaps the most recent use of PLA is as a printable filament for 3D printings. PLA can be blended with various polymers to expand physical and performance properties. For example, blending with ABS can impact the engineering plastic characteristics to address application requirements.
Acrylic Acid and Derivatives
For many years, an effective biochemical route to acrylic acid remained elusive, particularly from 3-hydroxypropionic acid. Proctor & Gamble took a different approach. They developed and patented award-winning breakthrough technology which dehydrates lactic acid to acrylic. Cargill obtained an exclusive license from P&G and are now in partnership with the French companies, Axens and IFP Energies Nouvelles to further develop, scale-up, and commercialize the technology.
Bio-based acrylic acid has been the basis for not only the large array of acrylic/acrylate polymers, but also many bio-based acrylate diol monomers readily used in UV/EB curing of inks and coating. Fully bio-based polymer examples could include 1,5-pentanediol diacrylate, BDO diacrylate, isosorbide diacrylate, and soya oil polyol acrylates as made from soya oil polyols (as noted in the polyurethanes section).
Also, academic researchers have prepared oligolactide diacrylates and tested them in UV-curable printing inks. These are 100% bio-based polymers. Bio-vinyl ester resins and reactive vinyl monomers like diol diacrylates, have been formed via the esterification of bio acrylic acid with bio epoxy resins, (diglycidyl ether, see below).
Biochemical routes to date for methacrylic acid (MA) have proven to be challenging and difficult. Direct routes from sugar have been investigated. However, the optimal route(s) for success first involve the fermentation of sugar to various MA intermediates followed by subsequent chemical reactions for ultimate conversion to MA. A successful pathway to producing bio-methacrylic acid will enable much of the similar chemistry to the aforementioned derivatives for acrylic acid.
Epoxies and Derivatives
Epichlorohydrin (ECH) is industrially produced starting with propylene. However, bio ECH (Epicerol®) has been developed by Solvay and commercialized by the Solvay subsidiary, Advanced Biochemical Thailand Co (ABT) via glycerol derived from plant oil triglycerides. Their plant in Thailand was recently expanded to 120,000 tpa.
Due to the wide use of ECH as a raw material for manufacturing the epoxy scaffold, this commercial facility opens the way for enabling many bio-based diglycidyl ether monomers. This includes those derived from the bio diols, isosorbide, BDO, and 1,5-pentanediol. Isosorbide has been frequently mentioned as an effective substitute for BPA in epoxy resins. Furthermore, reaction of such bio-diglycidyl ethers with bio acrylic acid would potentially enable the manufacture of 100% bio-vinyl ester resins.
Epoxidized soybean oil (ESBO), itself is not only capable of serving as a poly epoxide itself, but also, the epoxide moieties (in ESBO) can serve as reactive sites for bio-acrylic acid yielding 100% bio-vinyl ester resins.
Industrially Useful Chemicals that are Best Synthesized From Biomass
Perhaps with the exception of glycerol, soya oils, FDCA, lactic acid, and isosorbide, the vast majority of bio-based chemicals are seen as having petrochemical sources. While many pharmaceuticals and amino acids have been traditionally made from biomass, it is noteworthy that there are some industrial chemicals that are best made from biomass and would be difficult to synthesize from petrochemicals. Two illustrative, pertinent examples are 9-decenoic acid methyl ester (9-DAME) and farnesene commercialized by Elevance Renewable Sciences and Amyris, respectively.
Elevance has elegantly exploited Nobel award-winning olefin metathesis chemistry to make products that are difficult to make by traditional organic synthetic methods. Exemplary is the metathesis of the unsaturated fatty acid, oleic acid, with ethylene to 9-DAME, a dual functionality 10-carbon molecule which contains a double bond at one end and an ester group at the other end. This uniqueness enables, for example, reaction with olefin-, ester-, and amine-containing polymers with the potential to form a whole myriad of previously unknown products.
Additionally, bio-1-decene (alpha decene), an alpha olefin, is produced as a co-product of this metathesis technology. Such alpha olefins are capable of an enormous number of chemical reactions potentially leading to a whole host of bio-based products for synthetic lubricants, cleaning products, cosmetics, oil field chemicals, and plasticizers to name a few.
Farnesene, made from sugar fermentation, is a very unique 15 carbon molecule containing 3 carbon-carbon double bonds thereby used as a building block for surfactants, fragrances, coatings, adhesives, sealants, and crop protection chemicals.
Observations and Conclusions Sources for Bio-based Chemicals
The number of actual commercial sources for bio-based chemicals is still limited but growing. This three-part article identifies a number of commercial ventures either in production or in various stages of planning or commercial development that are intended to meet this emerging demand for bio-based chemicals.
One aspect of the efforts to commercialize production of bio-based raw materials and polymers is to consider the primary markets for which these efforts are intended. In many cases, these commercial ventures are focused on large, non-coating related markets such as plastics, packaging films, and textiles. Coatings may benefit from these ventures but not necessarily from their being the primary business objective. CASE market applications will have a “fit,” but the intent to commercialize production of new, bio-based chemicals is often not guided by the specific needs of the coatings market.
In the individual discussions on bio-based chemicals (in this article), a number of potential and undeveloped routes to producing bio-based chemicals are identified. As indicated in the article, there are many new pathways and approaches to producing bio-based alternatives which can be brought forth to manufacture commercial volumes of bio-based chemicals. As the demand continues to grow for bio-based chemicals in the CASE markets, more of these commercial ventures will be tailored to the specific needs of this market space.
Drivers of Sustainability Initiatives
Led by many major corporations in the chemical industry, including the major global coatings manufacturers, definitive sustainability initiatives are being implemented with the goal of meeting the net-zero carbon footprint target by 2050. Target dates are being announced for partial and eventual 100% compliance with the Paris accords.
OEMs are now setting timelines for coatings manufacturers to provide new products that deliver a certain percentage level of bio-based content in their coating formulation. These proclamations are tied to corporate sustainability initiatives and the necessity for the larger global industry players to demonstrate their leadership in supporting this effort. The same can be said for the large global coating manufacturers, resin manufacturers, and other raw material suppliers who are struggling to find ways to respond to the increasing demand for greater bio-based chemical content in their products.
Cost Impact For Bio-based Alternatives
Putting aside the availability or viable sources for bio-based polymers, their cost has long been considered as a key barrier to their acceptance in commercial markets. The events of the last two years as a result of the COVID pandemic have, however, created a paradigm shift in industry with respect to resin prices.
Partly driven by supply chain interruption and vacillations in crude oil prices, resin prices have escalated far beyond what they were two years ago. The consequence of this has been price escalations throughout the supply chain. In turn, these events have resulted in less resistance and more tolerance for incorporating bio-based chemical content into next generation coating formulations.
Table 1: Polymer Families Covered |
|
---|---|
Resin | Article |
Aromatic Polyesters | Part 3 |
Aliphatic Polyesters | Part 3 |
Acrylic Acid Derivatives |
Part 3 |
Epoxies and Epoxy Derivatives | Part 3 |