Interesting question, although the definition of 'solventability' needs to be established.
It is common in the US for sheetfed alcohol substitutes to contain 50 to 100 percent EB or some other similar solvent (EB, EP, DPM, DB, PnB are all used by one vendor or another) while web formulas to produce similar work (high end catalogs, magazines etc) at much higher speeds usually contain less than 7% of these solvents. This is for presses with continuous dampening, brush and spray dampening formulations for high speed web often contain no solvent whatsoever in order to be VOC free.
The reasons sheetfed formulations require high solvent levels are complicated and few people in the fountain solution business would agree about the reasons for this. There are many low solvent products on the market for sheetfed printing but their success is limited, and may be determined by the equipment they are run on.
Dan the following white paper was sent to me. I asked for permission to post and it was granted.
In the past twenty-five years the chemical structure of the glycol ether solvents have undergone a marked chemical change. Previously glycol ethers were mainly derived from the ethers formed by the chemical reaction of ethylene oxide (a two carbon molecule) with various alcohols. This reaction gave rise to various products such as Dowanol EM (methyl Cellosolve, Dowanol EE (Ethyl Cellosolve) and Dowanol EB (Butyl Cellosolve).
These chemicals had one thing in common. All were based on the mono-ether with ethylene glycol (ethylene oxide reacted with water) this class of solvents found wide use in paints, varnishes, fountain solutions, etc. They were manufactured in large volumes by the major chemical companies.
About thirty-five years ago Government laboratories, which study the health effects of industrial chemicals found this type of glycol ether produced toxic effects when metabolized by the human body. The cause of the problem turned out to be based on the fact that these glycol ethers were formed by the two carbon ethylene oxide molecule. This two carbon building block is what caused these glycol ethers to break down into toxins in the body.
When this became known, a concerted effort was launched to reduce the usage of two carbon glycol ethers. This affects fountain solutions because Dowanol EB (butyl Cellosolve) is widely used.
To overcome the toxic drawback of the two carbon based glycol ethers and still retain the fine properties of this type of chemical solvent, the large chemical companies developed a new series of glycol ethers. These new glycol ethers are now based on a three carbon oxide (propylene oxide) as the building block to make this series of glycol ethers. The use of the same alcohols yield products that perform just like the previous two carbon glycol ethers.
The difference between the new glycol ethers is they are based on a three carbon building block as the base. This gets around the two carbon toxic effect when metabolized by the human body since the three carbon structure metabolizes by a different pathway.
The three carbon glycol ethers have generally the same physical properties, i.e. they are still good oxygenated solvents, they tend to have lower vapor pressures and higher boiling points. You will see these glycol ethers under names as Dowanol PM and DPM. The use threshold of these glycol ethers, due to the reduced toxic metabolic effects, are generally higher. However one must remember that all organic solvents, if handled indiscriminately can be a safety hazard.
The same would apply on polyglycol derivatives. The two carbon based glycols (ethylene glycol) and polyglycols (diethylene glycol, etc.) are more toxic if ingested than similar compounds based on three carbon building blocks (propylene glycol).
Since these propylene glycols have very low vapor pressures (very high boiling points) they do not generally contribute to health problems or environmental pollution.
This is a White Paper from Amerikal Products Corporation’s continued series “YOU NEED TO KNOW”, reproduction without the consent of Amerikal Products Corporation is prohibited.
