N-propyl alcohol versus Isopropanol alcohol

[Lukew]

Have just been looking up the msds sheets for both n-propyl alcohol and Isopropanol alcohol . It seems that N-propyl alcohol would be a safer option with its lower vapour pressure and evaporation rate, Is there a reason that printers don't use it more frequently in fount solutions rather then Isopropanol ?
With the figures below, it would seem that you could run n-propyl at say 6% versus Isopropanol at 3% and you would effectivley be emmitiing similar VOC levels,
I have only come across one fount that has n-propyl already premixed in it, But if you were to dose it yourself the possibility to cut VOC levels even further would be great.

Anyone using this stuff?


N-propyl alcohol
% Volatiles by volume @ 21C (70F):
100
Boiling Point:
97C (207F)
Melting Point:
-127C (-197F)
Vapor Density (Air=1):
2.07
Vapor Pressure (mm Hg):
21 @ 25C (77F)
Evaporation Rate (BuAc=1):
1.3

Isopropanol
% Volatiles by volume @ 21C (70F):
100
Boiling Point:
82C (180F)
Melting Point:
-89C (-128F)
Vapor Density (Air=1):
2.1
Vapor Pressure (mm Hg):
44 @ 25C (77F)
Evaporation Rate (BuAc=1):
2.83

 

[jlind]

n-propanol versus isopropanol

n-propanol versus isopropanol

Luke:
I think it will work OK, but you are overlooking the point of using alcohol in the first place. You want the alcohol to increase the viscosity of the water so it follows the rollers at a thinner water film, and then evaporates as soon as possible. You don't want the alcohol to be too good of a solvent for the ink, or you get tinting in the non image area and slow drying.

With this said, one solvent that works even better than isopropyl alcohol is ethanol. Unfortunately, alcoholism among printers is already high enough, for good reason, all the aggravation of those pesky designers and customers. Also, ethanol is taxed and very expensive, at least in the US of A.

Isopropyl alcohol was a compromise. N-propanol will not work as well for a few reasons. It is slower to evaporate, and will act like the butyl cellosolves (not that slow) of the current alcohol substitutes. Also, I think it will be a better solvent for the ink vehicles and thus tend to cause emulsification issues. And finally, since it is slower than isopropyl alcohol to evaporate, it will stay in the printed ink film longer and lead to drying and blocking issues.

If you look at early studies of replacing isopropyl alcohol, done at the old GATF, you will surely find data for n-propyl alcohol. It was probably one of the first things they tried.

So, in conclusion, I'll bet vodka would work great. Kampei!

John Lind
Cranberry Township, PA
724-776-4718

 

[Lukew]

With the n-propyl having a slower evaporating rate then isopropanol, could this mabee be a benefit for polyester plates, which are notorious for not wanting to hold fount,, especially towards end of shift when there's a fair amount of heat in and around the machine.
If pressmen are having to run their IPA % higher to compensate for any evaporation before it reaches the plate, then could it not be possible that running with a lower % of n-proyl would give similar effects but with a substansial drop in VOC emmisions.

I'm sure I have read an article on the use of n-propyl alcohol in fount, but it was a long time ago, and at a time that I had little interest in the matter, If any one has any links to such articles it would be great. as I can't find any at the moment

Luke..

 

[Pressmanscooter]

FYI— IPA does not increase the viscosity (specific gravity) of water, it lowers it thus the reason hydrometers sink as IPA is added. Second IPA is the best choice for one reason, it reduces the surface tension of the water it is in. The short, short definition of surface tension is the force on a liquid that makes it bead up versus spread out. A drop of water with IPA will spread out and cover more area than a drop without. It does evaporate quickly too which is a nice benefit unless you are concerned about VOC. Other IPA alternatives all have the same problems, they do not lower surface tension as well as IPA, they do not evaporate as quickly and they all result in water speeds higher than what would be used if IPA was used.

 

[archetype]

I agree with scooter. IPA breaks down surface tension, essentially making your water wetter than it was before. Unfortunately alcohol also breaks down ink in the rollor train causing it to emulsify prematurely and eats away at pigments causing dryback and fading of the ink. Glycol and glycerin compounds in alcohol subs are still alcohol, just a different kind, more like what you would find in antifreeze and do not evaporate.

 

[Alois Senefelder]

The Benefits of IPA

The Benefits of IPA

Hello, both Archetype and Scooter are wrong, they need to know more about the "Chemistry of Lithography" 1 IPA reduces the surface tension of the Dampening Solution. The practical Advantages: the film of dampening solution is even, and the Ink/Water balance stabilizes immediately. 2 Evaporative Cooling, IPA evaporates quickly, thus cooling the plate and the Inking System. As a result, the Rheological properties of the Ink remain constant during the Print Run. AND #3 IPA DOES INCREASE "VISCOSITY"
Adding IPA to dampening solution increases its viscosity. This in turn stabilizes the dampening film on the plate and facilitates the transport and the metering of the solution.

Regards, Alois

 

[Pressmanscooter]

IPA is the best way

IPA is the best way

Alois,

1) The cooling of which you speak is almost completely the result of the refrigeration of the fountain solution and very little from the evaporation of the IPA. Anyone that has had a chiller go out on them quickly realizes the IPA was not what was cooling the plate.

2) The 5-7% IPA added to fountain solution has zero effect on its viscosity. Viscosity, or rheology if you prefer, are not even relevant to the discussion we are having. Surface tension is the issue, not viscosity.

 

[Lukew]

Pressmanscooter,, Have a read of the document bellow, you will soon see IPA does increase the viscosity of the fount soloution,

Also pour some IPA onto your hand,, as it evaporates it will feel cold,, not very technical I know, but it does indeed, help cool the plate,,

Also having your fount chilled it keeps the IPA in suspension,, and slows it's evaporation rate,,
for example,,and only an example,, If you could run your chiller at 2 deg you could run a much higher % IPA before you notice the foul smell of IPA , then compared to running the chiller at say 10-15 deg with a lower IPA % basically the lower the temp the higher the % you can get before a saturation point is achieved in which case the IPA would then readily evaporate, at a high rate, bascally becoming useless,,


http://www.pneac.org/sheets/litho/alcoholfreeprinting.pdf


If the PDF doesn't work try this HTML document,, it just won't have the little diagrames..
Alcohol-Free Printing

 

[Alois Senefelder]

Re - IPA

Re - IPA

Hello, and thank you Lukew, hopefully "Scooter" will read the Gatf Technical Report !!! and he will see How wrong he is !!!

Regards, Alois

 

[qaos]

Hi there,

We use N-Propyl and Toyo HyUnity inks. Recently appear some troubles in drying and inks try to keep in blanket when print job used Magenta cover areas. Anyone can help me to solve this? I am using Agfa RC661 2/3%, N-Propyl 8-10%, Vulcan Reflection blankets on a Komori Lithrone. Thanks for help.

 

[Alois Senefelder]

Hi Carosp, you should be using -- Isopropanol -IPA (Ispropyl Alcohol) NOT N-Propyl which is a different member of the Alcohol Family. The rest of your message is not making sense !!!!!! Please PLAIN English.

Regards,
Alois

 

[Lukew]

Carosp,
What fount solution are you using with the n-propyl ? is it the 2 in 1 fount thats already premixed?

Alois
It would seem that the use of n-propyl alcohol is very popular in some area's of the world. south africa / some area's of europe..specificly the 2in1
N-propyl is only 20% lower in voc then IPA so in the end if you have to run 8%-10% of n-propyl it's hardly worth the change, as running IPA at 6% would yeild great results anyway though if you where to use the 2in1 you no longer have neat IPA on the premisise.

 

[Alois Senefelder]

re - the Merits of IPA against N-propyl

re - the Merits of IPA against N-propyl

Lukew, read the answer give by J.Lind earlier in the Discussion, I repeat IPA has more beneficial properties for Lithographic Printing than using N- propyl, bear in mind that the use of IPA is the "de facto " alcohol used in fountain solutions since its introduction in the late 1940s. Anyway the we should be trying to eliminate " Alcohol" from the Pressroom, speaking from my own experience ie Web-Offset, the firm I worked at until I retired !! - we went "Alcohol Free" in the 1980s BUT even running alcohol free was not with out its problems.

Lukew -- explain 2 in 1 fount please ??? IS it American English for something I should Know !!!!!!!!

Regards,

Alois

 

[Lukew]

Alois, Yes I know Ipa is the recognised and prefered alcohol to run in fount solutions..
2in1 is made in Aouth Africa basically you put the alcohol dosing hose into the drum of 2in1 which as the name sugests is premixed with n-propyl and fount solution.. you can then run it so you get an accurate feed of say 2% fount and 8% n-propyl


My main interest of N-propyl is if I could have got drums neat of it to use, as that 8% is going against what we are aiming for.
We run poly plates, and although we are running IPA at 3.5% its not as easy as it should be, and some jobs I have had to bump IPA back up to 7% just to get the job through.As I'm sure your aware of, the last thing a printer needs is to be using something that makes his life dificult. + our water %feed is high and come summer time it will get worse..

 

[Alois Senefelder]

IPA + Fountain Solution

IPA + Fountain Solution

Hi Lukew, Now I understand your problem ! are you using 2in 1 Fountain Sol. from the South African Company - BM Management SA ??????

I have no experience of printing from Polyester Plates !!! BUT


Regards, Alois

 

[Lukew]

No no, not using that fount,, just using a normal fount and dosing in IPA, was just curious of the posibility to doseing in NPA instead of IPA..

Have you heard of that particular fount, or run it before?

 

[Tom_print]

We have recently started using that 2 in 1 fount, and we are simply blown away by how well it works, expecialy on polyester plates. Its set to dose so we get 8%NPA and 2%fount which emissions wise roughly equates to running IPA at 5 -6 %
We had trialed numerous founts ranging from your IPA repacement to normal founts with a dose from 2.5% up to 10% IPA, and this product simply outperforemed all of the other founts.
Its ability to keep the plate wet, keep fine 95% - 97 % 175 line screens open with minimal water is amazing. And thats with polyester plates..

Our back cylinders are staying clean and we get no more anoying picture framing on the cylinders which is normaly just a hassel to cleanand more downtime

It prints a much sharper dot compared to the other founts we had trialed
Drying time has been slashed, and there's simply less water needed and less ink needed to achive density, As you know you generaly need less ink to achieve density when going from say a fount with 10%ipa down to below 5% IPA well with this fount your ink keys are closed even further..and your running lower water settings even when compared to 10% ipa

We have always had a problem getting band free solids due to press design(water roller diamaters too small,) In which case if you run metal plates you get very little because of such a low water setting needed to obtain a scum free image, but with this fount, on poly plates the banding is nearly totaly disapeared a huge improvement from what we had.

As I said we have only recently begain running this so I will give a heads up down the track, but so far its simply briliant..

So for those that say it can't work, simply haven't run the 2 in 1 product or have a hidden agenda.
Also its fogra approved and contains none of thr nasties that some of the IPA free founts contain.

I just wish I had come accros the product sooner,

Tom

 

[jlind]

Hey pardner, no hidden agenda. Just recounting a number of years of reading and printing. I'll follow your next report of progress. I think it would wet a polyester plate better than isopropyl alcohol. That's not how the coversation started out. Good luck.
John Lind
Cranberry Township, PA
724-776-4718

 

[Tom_print]

John, I understand the original poster is more focused on the enviromental side of things, but below is his post just after your first reply.

With the n-propyl having a slower evaporating rate then isopropanol, could this mabee be a benefit for polyester plates, which are notorious for not wanting to hold fount,, especially towards end of shift when there's a fair amount of heat in and around the machine.
If pressmen are having to run their IPA % higher to compensate for any evaporation before it reaches the plate, then could it not be possible that running with a lower % of n-proyl would give similar effects but with a substansial drop in VOC emmisions.
Luke..

Also this 2 in 1 fount has a vapour pressure of 10mmhg @ 20c which is on the low side.
I believe that the bonus of using this stuff on poly plates is because its evaporaton rate is lower then that of IPA, there for it's getting its job done better before evaporating
One interesting note is N-propyl is water misceble, where as IPA is water soluble, I'm wondering if this is whats giving it better effects as well.

Tom

 

[Green Printer]

2 in 1 fount is 80% Propyl Alcohol cas #71-23-8