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HSP Application note #31

Mold Release Cleaning Solvents and Hansen Solubility Parameter (HSP)


HSPiP Team Senior Developer, Dr. Hiroshi Yamamoto


Hansen Solubility Parameters (HSP)

Hansen Solubility Parameters(HSP) were developed by Charles M. Hansen as a way of predicting if one material will dissolve in another and form a solution. They are based on the idea that "like dissolves like" where one molecule is defined as being 'like' another if it bonds to itself in a similar way.
Specifically, each molecule is given three Hansen parameters, each generally measured in MPa0.5:
dD:The energy from dispersion bonds between molecules
dP:The energy from dipolar intermolecular force between molecules
dH:The energy from hydrogen bonds between molecules.
These three parameters can be treated as Vector for a point in three dimensions also known as the Hansen space. The nearer two molecules HSP Vector are in this three dimensional space, the more likely they are to dissolve into each other.

What can perhaps be surprising is that one can assign HSP to so many different things. Gases like carbon dioxide, solids like carbon-60, sugar, and biological materials like human skin, depot fat, DNA, and even some proteins all have HSP. The list can be continued with drugs, polymers, plasticizers, and in fact any organic material and even many inorganic materials like salts. The only requirement for an experimental confirmation is that the material must behave differently in a sufficient number of test solvents upon contact.

Pirika JAVA Demo Applet calculate HSP. HSPLight is available here.
Please refer to e-Book of HSPiP if you want know more about HSP.
About the Power Tools that handle HSP more effectively.

I will explain how to use HSPiP with the theme of Mold Release (Anti-stick agent) cleaning solvents.

HSPiP(Hansen Solubility Parameters in Practice)

The first edition of HSPiP that appeared in November, 2008, greatly enhanced the usefulness of the Hansen solubility parameters (HSP).

The HSP values of over 1200++ chemicals and 500 polymers are provided in convenient electronic format and have been revised and updated using the latest data sources in the second edition (March, 2009).

A third edition of the HSPiP appeared in March, 2010. There are now 10,000 compounds in the HSP file which also includes data on density, melting point, boiling point, critical parameters, Antoine constants and much more. The user is able to carry out many different sorts of optimisations of solubility, evaporation, diffusion, adhesion, create their own datasets (automatically if required) and explore the huge range of applications for HSP in coatings, paints, nanoparticles, cosmetics, pharma, organic photovoltaics and much more.

The 3rd Edition v3.1 was released on 12 December 2010. Current users can upgrade free (now v3.1.09) by downloading the latest .msi installer from http://hansen-solubility.com

The 4th Edition v4.0.x was released on 2 Jan. 2013. The Current users can upgrade with free charge.

2013.1.28 The Visual How to manual of HSPiP. You can understand what HSPiP can do.
Please check the Functional Group List whether your targets are available with HSPiP.
How to purchase HSPiP
2013..1.2 The HSPiP ver. 4 include Power Tools for HSPiP power user.


Mold release agents are used when they make plastic products with injection molding. At that time they coat mold surface with some chemicals for easily remove after shot. They use fluoro-compounds or silicone compounds for this purpose. So sometime, these chemicals remain of the surface of plastic. The amount of chemicals are so small amount, but if that plastic is used for medical area, they need wash out those chemicals.

I search solubility of fluoro-compounds or silicone compounds, but in vain. (If you know where the data is, please let me know.) So I explain with Stearic Acid. If you want to search “something” cleaning solvents, the procedure is same, so please read Stearic Acid as “something” your specific target.
Actually, when they use Stearic Acid as Mold Release, they use Ca or Zn salt.
If you have that solubility data, use them. Here I explain with just Acid form.

I made Charge Calculation program for my students. Just draw molecule and push calc. button, you will get charge. This Program may help understanding of these salts.


The thing you have to do at first is compile solubility data. I found the Stearic Acid solubility data in Handbook. Then summarize like below.

Hcode name MW Density 30C(g/100g) 30C(g/100ml)
10 Acetonitrile 41.053 0.786 0.3 0.2358
7 Acetone 58.08 0.79 4.8 3.792
570 isopropyl alcohol 60.096 0.785 10 7.85
325 Ethanol 46.069 0.7905 3.42 2.70351
328 ethyl acetate 88.106 0.902 5.2 4.6904
102 butyl acetate 116.16 0.882 8.1 7.1442
122 carbon tetrachloride 153.823 1.584 10.7 16.9488
181 cyclohexane 84.161 0.779 10.5 8.1795
443 diisopropyl ether 102.177 0.724 10.5 7.602
306 1,4-dioxane 88.1 1.029 15.3 15.7437
156 chloroform 119.378 1.489 17.5 26.0575
637 toluene 92.141 0.867 10.45 9.06015
92 butanol 74.123 0.81 9 7.29
481 methyl ethyl ketone 72.107 0.805 8.34 6.7137
417 hexane 86.177 0.659 4.3 2.8337
52 benzene 78.114 0.879 12.4 10.8996
456 methyl alcohol 32.042 0.791 3 2.373

In this case, the ethanol is 95% purity so marked yellow for some error.
In the handbook, the solubility data is g/100g solvent. But HSP we deal solubility with g/100ml solvent. So I append that column.

Then I search HSP value of these solvent.

Please run HSPiP, and from menu bar “File” choose new. Then you will get blank table. Then check Molecular List. You will see 1200+ official compounds with HSP values. And if you double click on the solvent, that data are copy to your own table. You can search compounds with name or CAS number.
If you ready all your solvents, then you need to input score.
For the standard procedure, please put 1 for good solvent, put 0 for bad solvent.
In this case, I put 1 for solubility is more than 8g/100ml.

Hansen divided heat of vaporization energy into 3 parts.
δD: Dispersion energy
δP: Polarity energy
δH: Hydrogen bonding energy
And use this 3 parameter as Vectors, [dD, dP, dH].
Put HSP to X, Y,Z- axis, it called Hansen Space.
The solvents that dissolve “something” very well, all that solvents HSP are very similar, and if plot those HSP on Hansen Space, they make sphere. The Sphere program search this sphere.

Hansen Sphere

To determine if the parameters of two molecules (usually a solvent and a polymer) are within range a value called interaction radius (R0) is given to the substance being dissolved. This value determines the radius of the sphere in Hansen space and its center is the three Hansen parameters.

From version 3.1.X, Double Spheres function is available.

Pirika provide JAVA 3D Demo Applet to browse the Sphere(s).
The HTML5 Sphere Viewer examples are available here.
Now we have Power Tool "Sphere Viewer", GUI HTML5 software on HSPiP ver. 4.

Push calculate button.
The Sphere program search the sphere.
Every solvents scored 1 goes to inside the sphere.
And every solvents scored 0 goes to outside the sphere.
And the sphere radius is smallest.
Sometime, there is exceptions, but this case Sphere program search perfect sphere.
And the center of sphere become [17.59, 0.24, 4.6] and radius of sphere is 4.7.
Stearic Acid HSP is determined to [17.59, 0.24, 4.6] with solubility experimental data.

Once we got HSP, we can predict solubility of Stearic Acid with other solvents. We need just calculate HSP distance.

HSP Distance

To calculate the distance (Ra) between Hansen parameters in Hansen space the following formula is used:

HSP distance(Ra)={4*(dD1-dD2)2 + (dP1-dP2)2 +(dH1-dH2)2 }0.5

Please remind, there is a factor of 4 before dD term.
If the HSP distance is shorter than sphere radius(4.7), then that solvent have high probability of dissolving stearic acid.
Actually, we have Stearic Acid in official HSP database. That value is [16.3, 3.3, 5.5]. Please try to run the Sphere program with different score values.

Once you have HSP values, you can search solvents that will dissolve Stearic Acid from HSPiP database.

From Menue bar, FindMols, window will open.
You can search molecules with range of dD, dP, dH (or Boiling point).
I set Stearic Acid like HSP and push calculate button, then 28 molecules are matched.
You can choose from this list or can design mixture solvents.

Then what we can do when there is not in database, nor there is not experimental data?HSPiP have the function to estimate HSP from molecule’s chemical structure.
if you push δ button, DIY window apear.
And you just put Smiles structure and push calculate button, program automatically break molecule into functional groups, and estimate HSP and other properties.

Smiles(Simplified Molecular Input Line Entry Syntax)

SMILES is a string obtained by printing the symbol nodes encountered in a depth-first tree traversal of a chemical graph.
"Organic subset" of B, C, N, O, P, S, F, Cl, Br, and I, brackets can be omitted.
Branches are described with parentheses, as in CCC(=O)O for propionic acid
Double and triple bonds are represented by the symbols '=' and '#'
Ring closure labels are used to indicate connectivity between non-adjacent atoms in the SMILES

Pirika JAVA Demo Applet getting Smiles. Draw2Smiles is available here.
Now we have Power Tool "Draw 2 Smiles", GUI HTML5 software on HSPiP ver. 4.


Y-MB Properties Estimation

Y-MB break Smiles into correspponding Functional Groups and Estimate various Properties. These estimation schemes are come from Pirika technologies.

Pirika JAVA Demo Applet calculate Properties. PirikaLight is available here.
Now we have Power Tool "Y-Predict", GUI HTML5 software on HSPiP ver. 4.

The estimation values are [16.3, 3.0, 4.9] so it is very good agreement with experimental values.
From the functional groups information, program sugest us this compound is Hcode(Hansen Code) 603 Stearic acid.
If we have official values, then use them instead of estimated values.

If you want to search solvent by experiment, start from estimated values and feedback the results.
It will reduce your total trial.

As I wrote,
There is HSP in database,
There is experimental solubility data,
There is estimated HSP.
You can search solvent if you use HSPiP.

But please remember that this time we want to wash out Stearic Acid from polymer.
If that solvent dissolve not only Stearic acid but also the Polymer, that become meaningless.
Suppose, the polymer is ABS polymer.

If you push P button, All the list of polymer appear.
Search ABS polymer.
Suppose No. 390 ABS polymer is your target polymer.
HSP is [17.6, 8.6, 6.4] and radius is 10.9.

We can calculate HSP distance from ABS to Stearic Acid with this scheme.


And the HSP distance become 8.6.
So Stearic Acid is inside the Sphere.

Not dissolve polymer -> Outside of red circle.
Dissolve Stearic Acid -> Inside of blue circle.
And the candidate locate very narrow area.
(But attached mold release amount is very trivial and need not dissolve 8g/100ml, if you think like that, the blue circle radius become large and increase candidate.


Drag=Rotate, Drag+Shift=Larger/Smaller, Drag+Alt or Command(Window key)=Translate.

If you are using HTML5 enable browser such as Chrome, Safari or FireFox (IE9 is out of support), you will see the Canvas. If you pick solvent, solvent name will appear.

Blue Large Sphere is ABS.
Green small Sphere is Stearic Acid.

But remember that, if the mold release are easily dissolve to polymer, then it will not show anti-stick power.

Please try HSPiP!