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Introduction
High technology is more and more complex and needs an increasingly large number of materials differing in nature and properties used in an almost infinite number of combinations. In order to achieve optimum operation, very clean surfaces are quite often needed. Industry, therefore, requires solvents which are very efficient in removing contaminations and are not aggressive
toward the parts to be cleaned; the solvents must allow the treatment of complete assemblies (electronic circuits, precision parts, optical parts...) by a convenient and fast procedure.
In former times, CFC-113 was used to obtain perfectly cleaned surfaces in a great number of such applications. However, like all fully halogenated chlorofluorocarbons, CFC-113 falls under the international regulations aimed at the protection of the stratospheric ozone layer and is therefore phased out.
Solkane® 141b is a product developed by Solvay, which is well suited for the substitution of CFC-11 as blowing agent for polyurethane foams and for the partial substitution of CFC-113 as solvent and drying agent.
Compared to CFC-113, Solkane® 141b is approximately ten times less harmful to stratospheric ozone and is recognized as an interim solution allowing the rapid phase-out of CFCs.
Especially in the field of solvents, Solkane® 141b enables the users to continue using and paying off their existing equipment without major changes, which is not the case with aqueous or semi-aqueous processes.
HCFC-141b is a solvent with its own characteristics. We offer guidance to our customers to help them minimize emissions and adapt their equipment, so as to use Solkane® 141b in the best possible way.
Solvay’s laboratories have already worked out several specialties based on Solkane® 141b for the major fields of application:
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cleaning of various parts such as plastics, metals, alloys, glass
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drying of various parts such as plastics, metals, alloys, glass
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defluxing of printed circuit boards.
Compatibility with plastics and elastomers
Being a mild and selective solvent, Solkane® 141b can be used to treat most synthetic materials. However, a few plastic and elastomeric substances are more sensitive to Solkane® 141b than to CFC-113. We advise users to perform compatibility tests before any usage in regular production processes.
The tables below summarize the behaviour of various types of plastics and elastomers after immersion in Solkane® 141b and CFC-113. The measurements were made according to the usual procedure (after 5 minutes, after 7 days immersion and finally after drying the pieces 3 days long at 50°C).
Our laboratories are at the disposal of the users for any additional testing.
Compatibility with plastic materials – Comparison with CFC-113
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Solkane® 141b
|
|
CFC-113
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| ABS |
-
|
|
+
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| Nylon (6 and 66) |
+
|
|
+
|
| Polyethylene |
-
|
|
+
|
| Polypropylene |
+
|
|
+
|
| Polycarbonate |
o
|
|
+
|
| Polystyrene |
-
|
|
o/+
|
| PVC |
+
|
|
+
|
| PVDF |
+
|
|
+
|
| Epoxy resins |
+
|
|
+
|
Compatibility with elastomers – Comparison with CFC-113
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Solkane® 141b
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|
CFC-113
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| Natural rubber |
-
|
|
-
|
| Buna N |
o/-
|
|
+
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| Neoprene |
-
|
|
-
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| Kalrez |
+
|
|
o
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| (perfluoroelastomer) |
|
|
|
| Silicone rubber |
-
|
|
-
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| Viton A |
o/+
|
|
o/+
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| PFTE |
+
|
|
+
|
| Copolymere Ethyl/Propyl |
-
|
|
o/-
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+ compatible
– non compatible
o compatibility to check case by case
Compatibility with metals
All specialties based on Solkane® 141b are compatible with the most commonly used metals and alloys. This is due to the very high stability of Solkane® 141b and to the fact that the contact time with the parts to be cleaned or dried is short.
We advise users to check the compatibility with Solkane® 141b in the case of special metals or alloys before any application on a large scale. Our laboratories are ready to assist users whenever there are doubts regarding compatibility with Solkane® 141b.
Retrofitting existing equipment for the use of Solkane® 141b
Solkane® 141b can be used in cleaning machines having one or more baths.
There is equipment specially designed for this solvent. But one of the greatest advantages of Solkane® 141b is that it can be utilized in most cases in equipment initially designed for CFC-113 and thus substitute CFC-113 without costly capital expenditure.
The physical characteristics of both solvents are not identical: slight modifications are required to ensure an optimal utilization of Solkane® 141b and minimize losses. Modifications must be made in accordance with the recommendations given by the equipment manufacturer.
Due to the boiling point of 32 °C of Solkane® 141b, it is necessary to adjust the heating elements. Tight controls of the machine are recommended to keep vapour from escaping. Close the lid whenever the machine is not in use.
Temperature of fluid in cooling coils (condensation of vapours)
Solkane® 141b is more volatile than CFC-113, therefore it is necessary to lower the temperature of the cooling fluid to approx. 0 °C (inlet temperature in the cooling coils), with an added cooling unit, if necessary.
Freeboard
Whenever enough space is available, we recommend a freeboard ratio greater than 1. Freeboard ratio is defined as the distance from the vapor line to the lip of the machine divided by the narrowest wall-to-wall dimension of the machine.
Additional freeboard may be added with a second cooling circuit also operated with an inlet temperature around 0 °C, the purpose of which is to condense the humidity of the surrounding air; the condensed water can be drained into a water separator.
Water separators
The density of Solkane® 141b is lower than the density of CFC-113. Thus, it is necessary to adjust the outlet (distance from the bottom) in the water separator. It is also recommended to cool down the water separator to approx. 0 °C to improve the phase separation.
If molecular sieves must be used, we recommend checking their compatibility with Solkane® 141b, because certain types of molecular sieves are known to exert a detrimental effect on the stability of Solkane® 141b.
Gaskets, elastomers and plastics
PTFE is the best choice for the gaskets; VITON® is also suitable, as well as Polyethylene, Polypropylene and PVC.
Productinformation
Solkane® CN for surface treatment
Solkane® CN is a blend that has been developed for the cleaning and degreasing of metal parts, plastics or combinations.
Treatment can be effected in cleaning equipment having one or more baths, also in the presence of ultrasonic agitation.
Thanks to its specific properties, Solkane® CN can be used for cleaning miscellaneous parts or complete assemblies for which a high degree of cleanliness is required.
The utilization of Solkane® CN is especially useful:
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when the parts are made of synthetic materials. In this case, we recommend pretesting whenever there is any doubt about the compatibility of the materials with Solkane® 141b. Our laboratories will give technical assistance on request.
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when the surface of the parts to be degreased must be extremely clean, because of their shape (mechanical parts) or because of their nature (optical parts).
 Composition
Solkane® 141b
+ stabilizer 200 ppm
Solkane® MA speciality for electronics
Solkane MA is an azeotropic composition containing Solkane® 141b and methanol. It has been specially developed for defluxing printed circuit boards.
This speciality can also be used for cleaning and degreasing various metallic or plastic parts.
Flux residues on printed circuit boards have to be removed so that the whole system works perfectly. Due to its selective solvent power, Solkane® MA removes these residues while respecting the components. The results obtained allow the circuit to pass the most severe tests of cleanliness (low ionic residue measured with an ionograph for example).
Defluxing printed circuit boards is usually made in a two or three-sump cleaning equipment completely filled with Solkane® MA; after immersion in the first sump submitted to ultrasonic agitation, the printed circuit board is eventually rinsed in liquid phase in the second sump before final vapour rinsing in the last chamber.
Degreasing of various parts with Solkane® MA is made in equipments with one, two or three sumps, with or without ultrasonic agitation. The exact cleaning procedure has to be defined case by case. As for defluxing, the total cleaning time usually does not exceed a few minutes.
Our laboratory is at the disposal of the users for all technical assistance they would need.
 Composition
Solkane® 141b
+ 3,8 % Methanol
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Metal surface treatment
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