JPH03237199A - Azeotrope-like composition having stabilized 1,1-dichloro-2, 2, 2-trifluoroethane and 1, 1-dichloro-1-fluoroethane - Google Patents

Abstract

PURPOSE: To obtain the subject compsn. by adding nitromethane and diisopropylamine to a specific azeotropic compsn. in a stabilizing amt., and stable during use and during long-term preservation and exerting no adverse effect on the washing of an electronic circuit board.

CONSTITUTION: One or more kinds of compds. (B) among nitromethane, diisopropylamine, 1,2-butyleneoxide and 4-methoxyphenol are added to an azeotropic compsn. (A) consisting of about 80-20 wt.% (pref., about 65 wt.%) of 1,1-dichloro-2,2,2-trifluoroethane (i) and about 20-80 wt.% (pref., about 35 wt.%) of 1,1-dichloro-1-fluoroethane (ii) in a stabilizing amt. to obtain the objective compsn. having a b.p. of 31°C under about atmospheric pressure.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Pending U.S. Patent Application No. 07 filed February 15, 1989
No. 297.366, 1,1-dichloro- with methanol and ethanol as effective cleaning solvent compositions, particularly for cleaning electronic circuit boards.
2,2,2-)lifluoroethane (HCFC-123)
and 1,1-dichloro-1-fluoroethane (ICFC
-141b) is disclosed.

As disclosed in the above-referenced application, the current industrial process for brazing electronic components to circuit boards is to coat the entire circuit board with a flux composition and then apply the coated side of the board to the solder. It includes passing it over a bre-heater and then passing it through molten solder. The flux composition cleans the conductive metal parts and promotes solder adhesion. Commonly used fluxes consist mostly of resins used alone or with active additives, such as amine hydrochlorides or oxalic acid derivatives.

After brazing, which thermally degrades some of the resin, the flux and flux residue are often removed from the substrate with an organic solvent composition. Many current circuit board cleaning processes use vapor film flux technology because the requirements for removing contaminants from circuit boards are very demanding. In conventional operation of vapor defluxing, brazed circuit boards are passed through a bath of boiling organic solvent, which removes resin lumps (including thermally degraded resin), and then passed through a bath of fresh The organic vapor is passed through a bath containing distilled solvent and finally above a steam boiling bath where it condenses on the substrate and provides a final rinse with clean distilled solvent. Furthermore, the circuit board can also be sprayed with distilled solvent, if desired, prior to final rinsing.

Pending U.S. Patent Application No. 07 filed April 1989
As disclosed in No. 7335.940, constant boiling azeotropic compositions of 1,1-dichloro-2,2,2-trifluoroethane and 1,1-dichloro-1 fluoroethane are used for cleaning circuit boards. However, in certain industrial applications these solvent systems, like many solvent systems, must be stabilized against compositional changes during use and long-term storage. oxidation, polymerization,
Changes such as interaction of components can generate products that have an adverse effect on the circuit board being cleaned or the solvent composition itself.

Accordingly, it is an object of the present invention to: 1. be compositionally stable during use and long-term storage, and with little formation of undesirable reaction products that may adversely affect the cleaning of electronic circuit boards; l-dichloro-2,2,2-
An object of the present invention is to provide a constant boiling aceodorope composition of trifluoroethane and 1,1-dichloro-1-fluoroethane.

SUMMARY OF THE INVENTION The stabilized azeotropic compositions disclosed herein are composed of predetermined amounts of 1,1-dichloro-2,2,2-trifluoroethane and 1,1-dichloro-1-fluoroethane. an azeotropic composition having a boiling point of approximately 31° C. at atmospheric pressure and containing an effective stabilizing amount of nitromethane, diisopropylamine, 1
, 2-butylene oxide and/or 4-methoxyphenol. The stabilizing package also comprises effective stabilizing amounts of 1,2-propylene oxide and nitromethane with or without one or more of diisopropylamine, 1,2-butylene oxide and/or 4-methoxyphenol. becomes possible.

DETAILED DESCRIPTION OF THE INVENTION An effective amount is such an amount of 1,1-dichloro-2
,2,2-)lifluoroethane (HCFC-123) and 1゜1-dichloro-1-fluoroethane (HCFC-
141b) of the azeotropic compositions of the present invention, as disclosed in U.S. patent application Ser. It means that formation is brought about.

Effective stabilizing amount means at least some of one or more of nitromethane, diisopropylamine, 1,2-butylene oxide and/or 4-methoxyphenol. Effective stabilizing amounts also include diisopropylamine, 1,2-butylene oxide and/or 4
- means at least some of 1,2-propylene oxide and nitromethane, with or without one or more of methoxyphenols. When the effective stabilizing amount of the above compound is When combined with a composition, they enable the azeotropic composition to be commercially used and preserved;
That is, it provides a commercially acceptable appearance, resistance to corrosion and loss of integrity of the azeotropic composition.

Commercially available HCFC-123 is available in small amounts of 1.2
-dichloro-1,1,2-trifluoroethane, for example about 20.0% by weight of 1,2-dichloro-1,1,2-
trifluoroethane (ICFC-123a), which mixture is coated with 1,1-dichloro-2,2,2-trifluoroethane (HCPC-123) and imparts azeotropic properties to the cleaning solvent composition. It is intended to contain small amounts of other substances that are not significantly modified.

The stabilized compositions of the present invention contain an effective amount of 1.1-
dichloro-2,2,2-trifluoroethane and 1°l
-dichloro-1-fluoroethane; 0.025 to 0.2% by weight diisopropylamine, and about 0.002 to 0.018% by weight 4
- forming an azeotropic composition that can contain one or more methoxyphenols, where the weight percentages of said stabilizer are based on the weight of the azeotropic composition.

The azeodorope composition of the present invention comprises a mixture of 1,1-dichloro-2,2,2-)lifluoroethane and 1,1-dichloro-1-fluoroethane, more specifically, The composition contains about 1-99% by weight of 1.1-
dichloro-2,2,2-)lifluoroethane and about 99
-1% by weight of a mixture of 1,1-dichloro-1-fluoroethane.

The azeotropic compositions of the present invention also have about 20-80
wt% 1,1-dichloro-2,2,2-)lifluoroethane and about 80-20 wt% 1,1-dichloro-l
- It is possible to provide a mixture of fluoroethane, which boils at approximately 31° C. at approximately atmospheric pressure.

A minimum of about 35% by weight of 1,1-dichloro-
It has been found that the azeotropic compositions of the present invention containing 2,2,2-trifluoroethane are non-flammable.

A preferred azeotropic composition of the present invention has a composition of about 65% by weight 1,1-dichloro-2,2,2-1-lifluoroethane and about 35% by weight 1,1-dichloro-1-fluoroethane. has. This azeotropic composition generally boils at about 31° C. at atmospheric pressure.

The azeotropic composition is an effective solvent for cleaning electronic circuit boards. The above solvent composition is
It is characterized by desirable properties such as relatively low boiling point, non-flammability, relatively low toxicity, and high solvent properties for fluxes and flux residues. The azeotropic nature and relatively low boiling point of the compositions allows them to be easily recovered and reused without losing their desirable properties.

Azeotropic compositions of 1,1-dichloro-2,2,2-trifluoroethane and 1,1-dichloro-1-fluoroethane perform well in the field of vapor defluxing and degreasing of printed circuit boards. It has been recognized that, in order to obtain the practical advantage of the unique properties of these solvent compositions, certain other desirable properties must be added to the compositions, particularly when solvent systems are used commercially. There is.

One of the desirable properties mentioned above is storage stability.

It is recognized that all materials used commercially must normally be kept in stock. The above storage may be for a short period of time, or for a long period of several months or years. Therefore, for solvent compositions to be useful, they must be stabilized against any significant deleterious changes that may result from oxidation, polymerization, or interaction of the components during storage or use. No. The above changes result in discoloration of the solvent, the formation of undesirable by-products such as chloride ions and acids, and/or the formation of insoluble polymeric materials. It has been found that the addition of one or more of the compounds listed above in the above-mentioned friability ranges exhibits effective storage stability.

Other commercially desirable properties imparted to the above solvent systems include:
Stability during use. For example, as discussed above, in a vapor deflux cleaning procedure, the circuit board being cleaned is first passed through a bath containing a boiling solvent to remove clumped resin, including thermally degraded resin. In this bath,
The organic solvent is exposed to a heat source for an extended period of time. After passing the first common law,
The circuit board is passed through a trough containing freshly distilled solvent and finally through the solvent vapors above the four baths, which provide a final rinse with cleaning solvent condensing on the circuit board. Thus, in use, organic solvents are constantly being used, either in the maintenance of boiling baths or in the evaporation of solvents to provide fresh distilled solvent, or the evaporation of vapors that condense on circuit boards for final rinsing. is heated. Therefore,
It is highly desirable to minimize any changes in the solvent system that could adversely affect the cleaning process or degrade the integrity of the solvent. As mentioned above, the changes are due to oxidation, polymerization, or interactions between components of the solvent system.

For example, one of the interactions that should be minimized is the interaction between hydrochloride fluorocarbons and metals at elevated temperatures, which can generate acidic by-products and chloride ions. Active metals such as zinc and aluminum and certain aluminum alloys, which are commonly used as materials for circuit board construction, are particularly susceptible to such interactions. The solvent system of the present invention contains nitromethane of about O
Incorporated at concentrations of 1 to 0.8% by weight, it effectively retards attacks of the above type and further prevents the formation of kelp.

diisopropylamine at a concentration of about 0.025 to 0.2% by weight, 96% by weight, methquinphenol at a concentration of about 0.05 to 0.4% by weight, A stabilizer package comprising .2-propylene oxide and nitromethane at a concentration of about 1 to 08% by weight enhances the stability of the solvent system.

All weights 96 are based on the exact amount of azeodorope composition of 1,1-dichloro-2,2,2-trifluoroethane and 1,1-cyclo-fluoroethane.

As shown in the examples, the above stabilizers enhance the stability of the solvent system when used in -K (4-methoxyphenol, 1°2-propylene oxide, diisopropylamine and nitromethane). do.

- The acceptable performance range of stabilizer concentrations when used together is the same as when used separately above. Concentrations of stabilizer higher than those mentioned above can also be used, but
However, it should be noted that under normal conditions, higher stabilizer concentrations generally do not provide additional suppression benefits.

Other acceptable inhibitor-stabilizer systems that provide storage and use stability to the azeodorope compositions are as follows.

Inhibitor Nitromethane Diisopropylamine 1.2-Butylene oxide 4-Methoxyphenol Nitromethane + 1.2-Propylene oxide Nitromethane + 1.2-Butylene oxide Nitromethane 10,2 1.2-Propylene oxide + Diisopropylamine Nitromethane + 0.2 1.2-Butylene oxide + diisopropylamine nitromethane 10,2 1.2-propylene oxide + 1.2-butylene oxide nitromethane + 0.2 1.2-propylene oxide + 4-methoxyphenol weight 06 0.2 05 0 .05 0.004 0.2 +0.05 0.2 +0.05 + 0.05+0.05 0.05+ 0.05 0.05+ 0.05 + 0.05+ 0.004 Desired stabilization of the present invention The low boiling azeotropic composition contains about 65% by weight of 1,1-dichloro-2,
2,2-trifluoroethane and about 35% by weight of 1.1
-dichloro-1-fluoroethane, and about 0.1 to 0.8% by weight nitromethane, about 0.05 to 0.4% by weight 1,2-propylene oxide, and about 0.025 to 0.2% by weight. of diisopropylamine, and about 0.00
Contains 2 to 0.016% by weight of 4-methoxyphenol.

More preferably, the stabilized azeodorope compositions of the present invention contain about 65% by weight of 1,1-dichloro-2,2,
2-trifluoroethane and about 35% by weight of 1,1-cyclol-fluoroethane, and about 0.2% by weight of nitromethane, about 0.05% by weight of 1,2-propylene oxide, about 0.05% by weight % diisopropylamine,
and about 0.004% by weight of 4-methoxyphenol.

Accordingly, the present invention provides a 1.1- Stabilized azeotropic compositions of dichloro-2,2,2-trifluoroethane and 1,1-dichloro-1-fluoroethane are provided.

Methods of combining inhibitors with the azeotropic compositions of the present invention are known in the art. These can be prepared by any known method including the step of mixing or combining the desired amounts of ingredients in a suitable container. A preferred method is to measure the desired amounts of ingredients and then combine them in a suitable container.

The stabilized azeotropic compositions described above have a low potential for ozone depletion and are expected to degrade almost completely before reaching the stratosphere.

The azeotropic nature of the stabilized azeotropic composition of the present invention allows for easy recovery and reuse of the solvent from the defluxing and degreasing operations. As illustrated, the azeotropic mixtures of the present invention are described in U.S. Pat. H1
,949 for cleaning processes.

Approximately 65% by weight of 1.1 with various inhibitor combinations
-dichloro-2,2,2-trifluoroethane and about 3
A comparative study of the 7-day stability of 5 wt% I, l-dichloro-1-fluoroethane solvent system combinations of
A series of 500 m using 90% water saturated solvent at 25 °C.
This was carried out by refluxing a 150i1 vapor solvent combination in a 1 Pyrex® flask. The flask was connected to a water-cooled condenser, the top of which was connected to a Dr.
Additionally, a sample of stainless steel (5S-304) was placed at the refluxing solvent vapor/air interface of the condenser, and a sample of stainless steel (SS-304)/aluminum alloy (AL-7) was placed at the reflux solvent vapor/air interface of the condenser.
A bonded sample of 075) was placed in a boiling liquid.

The 1,1-dichloro-1-fluoroethane used in these tests contained approximately 500 pp11 by weight of vinylidene chloride, an impurity commonly found in raw products; was not used. The solvent suppressed systems tested are shown in the table.

The following tests were performed on the individual test systems following the test exposures.

1. Chloride ion concentration was determined at the end of the test by extracting the solvent with an equal volume of deionized water and analyzing the water for chloride ion concentration. The original unsuppressed solvent contained less than 0.29p1 chloride ions. An increase in chloride ions usually represents a loss of stability of the solvent system components.

Loss of stability is usually accompanied by an increase in acidity.

2. The pi (change (fi end-group) of the solvent is determined by extracting the acidity from the solvent with an equal volume of pH-neutral (pH=7) deionized water and checking the pH of the water. It was done.

3. Corrosion testing involves rubbing the metal surface with ink and pencil eraser, brushing the surface, and then subjecting the sample to 1.
1.2-Trichlorotrifluoroethane, rinsed with deionized water and acetone, dried on Drierite® drying for 24 hours, and 0.0001gra
It was determined by measuring the sample to m. The weight loss of a metal sample is expressed as 1Iils/year. 4
wits/year aluminum (AI-707
5) Corrosion rate is acceptable.

4. The appearance of the solvent and aluminum (AI-7075) was determined visually using the rate criteria below.

gel.

^1-7075-1 - Very slight corrosion on about 1% of the surface.

53-304 -1 - Very slight corrosion on about 1% of the surface.

The abbreviations used in the table are as follows:

1.2-BO-1,2-butylene oxide 1.2~
PO-1,2-Propylene Oquinde -Nitromethane 4-MP -4-Methoxyphenol DIP^ -Diisopropylamine DIP^ DIP^ 0.05 IPA -HP IPA 1.2-PO

Claims (17)

[Claims] 1. about 80 to 20% by weight of 1,1-dichloro-2,2
, 2-trifluoroethane and about 20 to 80% by weight of 1,1-dichloro-1-fluoroethane. and the azeotropic composition comprises nitromethane, diisopropylamine, 1,2-butylene oxide and 4-
A stabilized azeotropic composition is admixed with an effective stabilizing amount of one or more methoxyphenols. 2. The stabilized azeotropic composition of claim 1, wherein about 65% by weight 1,1-dichloro-2,2,2-trifluoroethane and about 35% by weight 1,1-dichloro-1-fluoroethane are present. thing. 3. Based on the weight of the azeotropic composition, about 0
．． A stabilized azeotropic composition according to claim 1, wherein 2% by weight of nitromethane is present. 4. Based on the weight of the azeotropic composition, about 0
．． 2. The stabilized azeotropic composition of claim 1, wherein 0.5% by weight of diisopropylamine is present. 5. Based on the weight of the azeotropic composition, about 0
．． 2. The stabilized azeotropic composition of claim 1, wherein 0.5% by weight of 1,2-butylene oxide is present. 6. Based on the weight of the azeotropic composition, about 0
．． 2. The stabilized azeotropic composition of claim 1, wherein 0.04% by weight of 4-methoxyphenol is present. 7. about 80 to 20% by weight of 1,1-dichloro-2,2
, 2-trifluoroethane and about 20 to 80% by weight of 1,1-dichloro-1-fluoroethane. 1,2- with or without one or more of diisopropylamine, 1,2-butylene oxide and 4-methoxyphenol.
A stabilized azeotropic composition is admixed with effective stabilizing amounts of propylene oxide and nitromethane. 8. Based on the weight of the azeotropic composition, about 0
．． 0.05 to 0.8% by weight nitromethane, about 0.05 to 0.4% by weight 1,2-propylene oxide, about 0.05 to 0.8% by weight 1,2-propylene oxide.
8. The stabilized azeotropic composition of claim 7, wherein about 0.025 to 0.2% by weight of diisopropylamine and/or about 0.002 to 0.016% by weight of 4-methoxyphenol are present. 9. about 0.2% nitromethane, about 0.05% by weight
1,2-propylene oxide, about 0.05% by weight diisopropylamine, and about 0.004% by weight 4-methoxyphenol. 10. Based on the weight of the azeotropic composition, about 0.2% by weight nitromethane and about 0.05% by weight 1
, 2-propylene oxide is present. 11. Based on the weight of the azeotropic composition, about 0.2% nitromethane, about 0.05% 1,
8. The stabilized azeotropic composition of claim 7, wherein 2-propylene oxide and about 0.05% by weight diisopropylamine are present. 12. Based on the weight of the azeotropic composition, about 0.2% nitromethane, about 0.05% 1,
2-propylamine oxide and about 0.05% by weight of 1
, 2-butylene oxide is present. 13. Based on the weight of the azeotropic composition, about 0.2% nitromethane, about 0.05% 1.
2-propylamine oxide, and about 0.004% by weight
8. The stabilized azeotropic composition of claim 7, wherein 4-methoxyphenol is present. 14. A method of cleaning solid surfaces comprising the use of a stabilized azeotropic composition according to claim 1. 15. A method for cleaning solid surfaces comprising the use of a stabilized azeotropic composition according to claim 7. 16. A method for expanding a polymeric foam comprising the use of a stabilized azeotropic composition according to claim 1 as a blowing agent. 17. A method for expanding a polymeric foam comprising the use of a stabilized azeotropic composition according to claim 7 as a blowing agent.