Since ExxonMobil Chemical Co. announced the discontinuation of its Exxate&#;1 fluids line, users of these solvents have been seeking suitable replacements. Although specified in a variety of applications, Exxate fluids have found frequent use in solventborne coatings. Coatings manufacturers who need to replace these products in their formulations can be faced with a multi-step process that is demanding in terms of time and effort, and often costly. Most will begin the process by developing a list of potential replacements. The very lucky ones will find a drop-in replacement that functions as a direct substitute, but even these formulations require lab testing and validation. In many cases, no direct replacement is found, and the product requires complete reformulation, with all of the time and testing it takes to achieve performance that is equal to or better than the original formulation.
TJCY industrial chemical contains other products and information you need, so please check it out.
In addition to matching performance characteristics, a new formulation must also meet regulatory requirements, such as HAPs and TSCA. Certainly no manufacturer wants to introduce a new product that contains more VOCs than the old one! Next, is the new product as durable as the old one? Can it pass storage and shelf-life testing? How about environmental conditions and application methods? If the new formulation has successfully cleared these hurdles, the next step is to win customers' acceptance. For OEM and military applications, this often means an additional level of even more stringent testing, frequently involving esoteric equipment or techniques before a new product can be qualified. And finally, there are the administrative issues associated with bringing any new product into inventory, which can include everything from purchasing to EH&S, to supply chain and logistics. While no supplier can wave a magic wand to completely eliminate all the steps in the replacement process, large suppliers who are dedicated to the industry can offer significant assistance that can shorten the timetable. This article summarizes some of the work done at The Dow Chemical Co. to identify and develop suitable replacements for Exxate 600, 700, 800, 900, , and in solventborne coatings.
The Exxate line of solvents includes those noted above. Each Exxate solvent is composed of a mixture of branched and linear alkyl acetates. They are commonly referred to as oxo-alkyl acetates. The number in the Exxate solvent name refers to the number of carbons on the alkyl chain of the ester. Exxate 600 is a mixture of six carbon alkyl acetate esters, Exxate 700 a mixture of primarily seven carbon alkyl acetate esters, and so on.
Important criteria for solvent selection in solventborne coatings include solvency, ability to reduce coating resin viscosity, evaporation rate, density, odor, regulatory status, cost and other factors, depending on application. Since Exxate solvents are mainly used as the slow or "tail" solvent in coatings, it is most critical to match the evaporation rate as closely as possible. The "tail" solvent slows the drying of the coating, allowing time for it to flow and level, thereby improving the film appearance.
When replacing a solvent in a solventborne coating, matching the relative evaporation rate (RER) is critical in maintaining product performance. For single solvent replacements, an assessment can easily be made by comparing the RER values to the Exxate fluid to be replaced. For those Exxate fluids whose RERs are more difficult to match with currently available commercial solvents, blends can be utilized. However, comparing RER values may not lead to a suitable choice. Evaporation profiles, also described as percent of solvent evaporated over time, may differ dramatically for a blend even if the "average RER" is identical. Evaporation profile and evaporation rates for blends can be predicted by a number of modeling programs. Predictions generated by CHEMCOMP2, a suite of solvent-prediction programs developed by The Dow Chemical Co., illustrates this point. This program is designed to model the solvent blend evaporation behavior that should be observed when using a Shell evaporometer for the ASTM standard evaporation test. For example, n-butyl acetate has the same RER as a blend of 78% (by weight) isopropyl acetate and 22% n-pentyl propionate. This would lead to an assumption that, based on evaporation rate, this blend would be a good replacement for n-butyl acetate. Examination of the predicted evaporation profile shows that this assumption may not be accurate. Figure 1 shows a comparison of the evaporation profile, modeled at 25 °C with a relative humidity of 50%, of n-butyl acetate versus the blend. In this case, the slower solvent of the blend (isopropyl acetate) evaporates much more quickly than the target. Once the isopropyl acetate has evaporated, n-pentyl propionate then evaporates at a much slower rate than the target.
A blend of 80% n-propyl propionate and 20% n-butyl propionate has the same predicted RER as the blend above, but the evaporation profile match is superior (Figure 2).
The evaporation profiles of solvents with greater water solubility are more affected by humidity. For example, Figure 3 shows the evaporation profile for n-butanol (7.7 % soluble in water at 20 °C) at increasing levels of relative humidity. The sharp decrease in rate at 95% relative humidity indicates that n-butanol has completely evaporated, and the water absorbed then evaporates at a slower rate.
Therefore, water solubility of a solvent should be considered when choosing replacements for coatings that will be cured at various environmental conditions.
Recommendations for each Exxate fluid include at least one single solvent recommendation and, for some, a selection of blends. The single solvent recommendation is the closest match based on RER and Hansen solubility parameters. A selection of blends is listed to offer choices that cover various performance, regulatory and cost requirements. For some formulations, these recommendations may offer a direct substitute. However, depending on requirements, adjustment of the solvent blend may be required to achieve the proper solvent balance. Replacement recommendations are based on single solvents and solvent blends that best match evaporation profiles.
CHEMCOMP allows the evaporation profiles to be predicted with various temperature and relative humidity. Conditions in the figures are 25 °C and 50% relative humidity unless otherwise noted.
A commercially available replacement exists for Exxate 600 that is nearly identical in structure and properties. Comparison of the chemical structure shows that n-pentyl propionate is an isomer of the four components of Exxate (See Figure 4).
Table 1 shows the physical properties to be nearly identical. The small differences can be attributed to the fact that most of the Exxate 600 isomers contain branched alkyl groups while UCAR n-Pentyl Propionate contains only linear alkyls. In addition to flash point, evaporation rate and solubility parameters, the table also shows other useful characteristics such as:
In many cases, n-pentyl propionate can be used as a drop-in replacement for Exxate 600. Comparison of evaporation rates shows very similair profiles, although n-pentyl propionate may evaporate slightly faster (Figure 5).
The higher Exxate fluids, Exxate 700 and above, are unique in their physical properties compared to other commercially available solvents, and thus may be more challenging to replace. Tables 2 through 6 show physical properties of Exxate fluids compared to recommended solvents and solvent blends. Some formulations may require a blend to achieve desired performance. The comparative evaporation profiles are given for each set of replacement recommendations. The proper balance of solvent properties, i.e. evaporation rate, solubility parameters, water solubility, density, surface tension, resistivity, HAP status and cost can be evaluated for individual needs. Evaluation of the properties of each recommendation can assist in selection of the proper solvent for different application requirements.
EEP = ethyl 3-ethoxy propionate
UCAR4 Ester EEP, EASTMAN5 EEP Solvent
2-EHAc = 2-ethylhexyl acetate
PGDA = propylene glycol diacetate
DOWANOL6 PGDA,
EBA = ethylene glycol butyl glycol ether acetate
Butyl CELLOSOLVE7 acetate, EASTMAN EB acetate, glycol ether EB acetate
n-BuAc = n-butyl acetate
DPMA = dipropylene glycol methyl ether acetate
DOWANOL DPMA, ARCOSOLV8 DPMA
IBHK = isobutyl heptyl ketone
ECOSOFT9 Solvent IK
DBA = diethylene glycol butyl ether acetate
Butyl CARBITOL10 acetate, EASTMAN DB acetate, glycol
ether DB acetate
TPMB = 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate
UCAR Filmer IBT, TEXANOL11 Ester Alcohol
Exxate 700
Exxate 800
Exxate 900
Exxate
Exxate and
Note: Evaporation rate profile comparison for Exxate is currently unavailable in the CHEMCOMP database due to the unavailability of physical property data.
There are several options available to the coatings formulator for replacing Exxate solvents. Whether the solution is a direct replacement or requires adjusting the solvent balance, formulators have many options in order to maintain product performance and cost effectiveness.
References
1 Exxate is a trademark of ExxonMobil Chemical Co.
2 CHEMCOMP is a Service Mark of The Dow Chemical Co.
3 Carter, W.P.L. (). Atmospheric Ozone Impacts of Exxsol D95, Isopar M and the Exxate fluids. Final Report. ExxonMobil. RT3L.
4 UCAR is a trademark of The Dow Chemical Co.
For more sodium hexametaphosphateinformation, please contact us. We will provide professional answers.
5 EASTMAN is a trademark of The Eastman Chemical Co.
6 DOWANOL is a trademark of The Dow Chemical Co.
7 CELLOSOLVE is a trademark of The Dow Chemical Co.
8 ARCOSOLV is a trademark of Lyondell Chemical Co.
9 ECOSOFT is a trademark of The Dow Chemical Co.
10 CARBITOL is a trademark of The Dow Chemical Co.
11 TEXANOL is a trademark of Eastman Chemical Co.
Welcome back to the newsletter. We crossed a milestone recently and there are over people getting these emails. Thank you for subscribing and to those who have contributed monetarily just know that you are the reason I&#;ve been grinding it out for so long. If anyone is interested in sponsoring the next 8 issues of the newsletter feel free to respond to this .
This is the last issue sponsored by:
I&#;ve resisted putting in chemical structures long enough!Levulinic acid is having a moment right now with GF Biochemicals and NxtLevvel (JV with GF Biochemicals) attempting commercialization of levulinic acid derivatives. If you have no idea what levulinic acid is then you can perhaps go here for a brief explanation, but the reason why it&#;s so interesting is because it can be made from non-food biomass and it has enough functionality to be interesting for industrial and polymer chemists. My own doctoral thesis in biobased epoxy resins was based on a levulinic acid derivative&#;Diphenolic Acid.
When it comes to changing the origins of our economy there are really two options in moving away from oil dependence. The first option is to develop easy to use drop-in replacements to existing petrochemicals and this is something that Origin Materials is working on now with their chloroymethyl furfural (CMF) to terephthalic acid platform. The second option is to develop a whole new class and category of biobased chemicals and materials that can be substituted for existing petrochemicals.
It&#;s not like our existing petrochemicals are that great anyway. We are mostly stuck in a trap of performance versus cost and getting out of this trap requires competitive chemicals that perform similar or better than their current petrochemical counterparts at similar or lower prices. Levulinic acid has long been viewed as a viable molecule on which to build companies and its derivatives such as butyl levulinate (ester of levulinic acid and 1-butanol), a potential plasticizer.
The earliest production of levulinic acid that I remember during graduate school was a little company called Biofine Technologies LLC, which was co-founded by Steve Fitzpatrick, a chemical engineer. Biofine&#;s process is a dilute acid hydrolysis of mostly cellulose to produce levulinic acid. Fitzpatrick won the Presidential Green Chemistry Award in for his work. From the award:
Biofine developed a process to convert the waste cellulose in paper mill sludge, municipal solid waste, unrecyclable waste paper, waste wood, and agricultural residues into levulinic acid (LA). LA can be used as a building block for many other useful chemicals. LA made from waste cellulose reduces the use of fossil fuels and reduces the overall cost of LA from $4&#;6 per pound to as little as $0.32 per pound.
Biofine&#;s original demonstration plant is located at the University of Maine Orono in Old Town. I got a chance to meet Fitzpatrick and his co-founder when I was in graduate school (around ) and Biofine also built a demonstration plant in Caserta, Italy that as far as I was told never got finished due to a lack of funds.
It turns out that the demonstration plant in Caserta, Italy would eventually become GF Biochemicals, which is now led by Mathieu Flamini, a French football star who played for some of the best teams in the world including Arsenal and Milan as a midfielder, and he is also a major investor. I think Flamini&#;s passion for biobased chemicals, specifically levulinic acid, is exactly what the industry needs.
Mathieu, if you are reading this I&#;d love to chat about your company.
Also, Origin Materials also has a pathway to levulinic acid.
See how you can accelerate the commercialization of your new materials
A new product launch is always a risky bet, and ends badly in most cases.
What are the best applications to enter? What are the market needs? How to reach the right contacts within the right companies?
These are typical challenges that a large American supplier faced after having developed an innovative copolymer.
Download their case study to learn how they accelerated their product commercialization thanks to SpecialChem Insight Solutions.
Back in GF Biochemicals would acquire Segetis, which included 250 patents which spanned across end markets such as fragrances, plasticizers, cleaners, personal care products, and more. Karen Laird reported on the story for Plastics Today back in about GF Biochemicals and the issue around price:
Hence, when GFBiochemicals not only developed a one-step process to bring levulinic acid to market, but also implemented its proprietary technology at its commercial-scale plant in Caserta, Italy, in partnership with the University of Pisa and the Polytechnic University of Milan&#;retrofitting the plant with new conversion, recovery and purification technology&#;the world sat up and took notice.
I suspect GF Biochemicals is using the same Biofine process since their plant is also in Caserta, Italy and the add-on of being able to recover spent chemicals to restart the process is likely the reason the costs have gone down significantly. It&#;s not clear if Biofine Technologies is still operational, but I&#;ve reached out to Steve Fitzpatrick to get more details.
Here in the US, it appears as if a joint venture between GF Biochemicals and Towell Engineering Group has taken the name NxtLevvel in an effort to bring levulinic esters and ketals to the US market based on the GF Biochemicals and Segetis platform. If you are a chemist or formulator working in coatings and you want a biobased replacement for Texanol, then consider reaching out to Steve Block at NxtLevvel.
Some of the places that Levulinic acid and its derivatives could gain traction via BioRefineries Blog:
Fuel additives. Levulinate esters are additives for gasoline and diesel transportation fuels. For instance, they can replace current cetane improvers and cold-flow performers for diesel. They may also replace lubricity improvers. Methyltetrahydrofuran (MeTHF), a levulinic acid derivative, can also be blended up to 50% with gasoline to increase vehicle performance and reduce air emissions.
Solvents. Levulinic acid esters, gammavalerolactone (GVL) and MeTHF are suitable solvents for a number of applications. GVL can replace ethyl acetate and MeTHF can be used as a substitute of tetrahydrofuran (THF) in the fine chemical and pharmaceutical industry.
Polymers and plasticizers. Levulinic acid-derived ketal esters can replace major phthalate-based plasticizers. Methyl butanediol (MeBDO) has potential as a monomer for polyurethanes. GVL can be a monomer for polyester-polymers and starting materials for pyrrolidinone-isomers.
Resins and coatings. Levulinic acid can be used in polyester resins and polyester polyols to increase scratch resistance for interior and exterior coatings. Its derivative Diphenolic Acid (DPA) is used in protective and decorative finishes.
Agro-chemicals. Its derivative delta-amino levulinic acid (DALA) is used as an herbicide on lawns and certain grain crops.
Pharmaceuticals. Levulinic acid is used in anti-inflammatory medication, anti-allergy agents, mineral supplements and transdermal patches. DALA is used for diagnosis and treatment of cancer.
Personal care. Levulinic acid and its derivatives are used in organic and natural cosmetic compositions for antimicrobial, perfuming, skin conditioning and pH-regulating purposes.
Flavors and fragrances. Levulinic acid esters are often used as niche fruity flavor and fragrance ingredients.
The last time I spoke to Steve and his co-founder they had been going after the fuel additive angle and it was really difficult for them to gain traction. Perhaps in there might be more appetite for lower cost fuel additives. Here is an old white paper from Biofine about the market size for ethyl levulinate as a replacement for ethanol in gasoline. They estimated the market to be about $2.2 billion in the United States with a price of $1.88 per gallon, essentially an attempt to displace ethanol, which has it&#;s own issues.
There might be a deal there somewhere if Biofine Technologies is still kicking around as a company. You can reach out to Steve Fitzpatrick and his co-founder Mike Cassata if you are interested in investing.