JPH055280B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides solvent cleaning of trichlorotrifluoroethane, acetone, nitromethane and hexane;
This invention relates to an azeotropic mixture for vapor degreasing. These mixtures are useful in various vapor degreasing or solvent cleaning applications including desolventization. Vapor degreasing and solvent cleaning with fluorocarbon-based solvents is widely used in industry for degreasing and other cleaning of solid surfaces, especially complex parts and difficult to remove soils. Degreasing or solvent cleaning in its simplest form involves exposing the room temperature object to be cleaned to boiling solvent vapor. The vapor that condenses on the object becomes a clean distilled solvent that washes away grease or other dirt. Finally, when the solvent is evaporated from the object, nothing is left behind, just as if the object were simply washed in a liquid solvent. Conventional solutions where high temperatures are required to further enhance the cleaning action of solvents, where dirt is difficult to remove, or when operating large assembly lines where metal parts and assemblies must be cleaned effectively and quickly. A vapor degreasing operation consists of submerging the part to be cleaned into a reservoir of boiling solvent that removes dirt clumps, then placing the part into a reservoir containing freshly distilled solvent at around room temperature, and finally This is done by exposing the part to solvent vapor on a boiling sump which condenses on the cleaning part. Additionally, the area may be sprayed with distilled solvent before the final rinse. Steam degreasers suitable for the above operations are well known in the art. For example, US Pat. No. 3,085,918 to Sherliker et al. shows such a suitable steam degreaser consisting of a boiling basin, wash basin, water separator and other auxiliary equipment. Fluorocarbon solvents, such as trichlorotrifluoroethane, have been widely used in recent years as effective, non-toxic, non-flammable agents useful in degreasing applications. In particular, trichlorotrifluoroethane has been found to have excellent dissolving power for greases, oils, waxes, and the like. Therefore, motors, compressors, heavy metal parts, delicate precision metal parts, printed circuit boards, gyroscopes,
It has been found to be widely used for cleaning guidance equipment, space and missile hardware, aluminum parts, etc. However, depending on the purpose of dissolution, trichlorotrifluoroethane alone may not have sufficient dissolving power. Since trichlorotrifluoroethane is non-polar, it does not remove polar soils well. Therefore, to overcome this juncture, trichlorotrifluoroethane has been mixed with polar components such as aliphatic alcohols or chlorocarbons such as methylene chloride. For example, in U.S. Patent No. 3,881,949, 1,
A mixture of 1,2-trichloro-1,2,2-trifluoroethane and ethanol is used as a solvent for the vapor degreaser. The art has specifically sought azeotropic compositions containing desirable fluorocarbon components, such as trichlorotrifluoroethane, that also contain desirable properties, such as polar functionality, components that impart enhanced solvency, and stabilizers. . The azeotropic composition is
It is preferred because it has the lowest boiling point and does not fractionate on boiling. This is preferred in the vapor degreasing equipment described above using these solvents, as redistilled material is created for the final rinse. This vapor degreaser thus acts as a distiller. If the solvent composition does not exhibit a constant boiling point, ie, is not an azeotrope or azeotrope, fractionation will occur, leading to undesirable solvent distribution and unsafe cleaning and handling. If the solvent mixture is not azeotropic or azeotropic, the more volatile components of the mixture will be selectively evaporated and less desirable properties, such as less soil-solvating power and metal, plastic or elastomeric components, will be selectively evaporated. This results in a mixture whose components are less inert and more flammable and toxic. Several azeotropic compositions based on trichlorotrifluoroethane have been tested and in some cases found to be useful as versatile vapor degreasing solvents. For example, U.S. Pat.
No. 2999815 contains 1,1,2-trichloro-1,2,
An azeotrope of 2-trifluoroethane and acetone is described; US Pat. No. 3,573,213 describes 1,1,
Azeotropes of 2-trichloro-1,2,2-trifluoroethane and nitromethane are shown; U.S. Pat. and US Pat. No. 4,279,664 shows an azeotropic composition of trichlorotrifluoroethane, acetone and hexane. The industry continues to seek other new fluorocarbon-based azeotropes or azeotropes for new specialized applications in vapor degreasing and for other cleaning applications. It is therefore an object of the present invention to provide a 1,1,2-trichloro-1,
The object of the present invention is to provide new azeotropic compositions based on 2,2-trifluoroethane. Another object of the invention is to provide a new constant boiling point or essentially constant boiling point solvent which is liquid at room temperature, does not fractionate under the conditions of use and also has the above-mentioned advantages. . Yet another object is to provide azeotropic compositions that are relatively non-toxic and non-flammable in both the liquid and vapor phases. The present invention consists of trichlorotrifluoroethane, acetone, nitromethane and hexane,
Trichlorotrifluoroethane is 1,1,
2-trichloro-1,2,2-trifluoroethane is preferred. A novel azeotropic composition for solvent cleaning and vapor degreasing has been discovered. In the present invention, the azeotropic composition comprises 72.7-87.8% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane;
10.0-16.6 wt% acetone, 0.005-1.5 wt%
of nitromethane and 0.2-10.6% by weight of hexane. In a preferred embodiment of the invention, the azeotropic composition comprises 77.9-87.6% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane, 10.0% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane,
Consisting of ~14.2% by weight acetone, 0.05-0.9% by weight nitromethane and 1.0-7.9% by weight hexane. Such compositions have a constant or essentially constant boiling point of about 44.0° C. at 760 mm Hg. Although the exact azeotropic composition was not measured, it was found to be within the above range. Regardless of the composition of the true azeotrope, all compositions within this indicated range, as well as certain compositions outside the indicated range, are azeotropic compositions, as defined in more detail below. These azeotropic compositions are stable and safe to use, and the preferred compositions of the invention are non-flammable (Tag Open Cup).
When tested using the ASTM D1 310-16 test method, it was found to exhibit very good dissolving power (no flash point). These compositions have been found to be particularly effective when used in conventional degreasing equipment for dissolving lubricating and machine cutting oils and cleaning such oils from solid surfaces. For purposes of this discussion, an azeotropic composition is a composition that behaves as a true azeotrope in that it has a constant boiling point property or does not tend to fractionate upon boiling or evaporation. I will take it to mean. Such compositions may or may not be true azeotropes. Thus, in such compositions, the composition of the vapor produced during boiling or evaporation is the same or substantially the same as the initial liquid composition. Therefore, even if the liquid composition changes during boiling or evaporation, the change is minimal or negligible. This is in contrast to non-azeotropic compositions where the liquid composition changes considerably during boiling or evaporation. As is well known in the art, another characteristic of azeotropic compositions is azeotropic composition ranges containing the same components in different proportions. All these compositions are here encompassed by the term azeotropic. For example, it is well known that at different pressures the composition of an azeotrope changes at least slightly, and that a change in distillation pressure also changes the distillation temperature at least slightly. Thus, the azeotrope of A and B exhibits a unique relationship, but the various compositions are determined by temperature and/or pressure. 1, 1, 2 of the novel solvent azeotropic composition of the present invention
-Trichloro-1,2,2-trifluoroethane, acetone, nitromethane and hexane components are all commercially available. Preferably, they should be of sufficiently high purity to avoid adversely affecting the solvency and constant boiling properties of the system. For example, 1,1,2-trichloro-1,2,
A suitable 2-trifluoroethane is that sold by Allied under the trade name "GENESOLV D". The word “hexane” is used here to refer to any
Also used to mean C ₆ paraffinic hydrocarbon (C ₆ H ₁₄ ) (Hackh's Chemical
Dictionary, 3rd edition, McGraw-Hill Books (1944), p. 408). Therefore, the term "hexane" includes n-hexane, 2-methylpentane, 3
-methylpentane, 2,2-dimethylbutane,
Included are 2,3-dimethylbutane and mixtures of any and all of these. In particular, from about 35 to about 100% by weight of 2 mixed with other hexane isomers.
- Includes commercially available "isohexane" containing primarily methylpentane. Each hexane isomer, separately and in combination with other hexane isomers, is used in accordance with the invention with 1,1,2-trichloro-1,2,2-
It has been found that it forms azeotropic compositions with trifluoroethane, acetone and nitromethane. It will be apparent to those skilled in the art that various additives such as lubricants, detergents, etc. can be incorporated into the novel azeotropic compositions of the present invention for special purposes. These additives are selected so as not to adversely affect the essential properties of the composition for the particular application. Example 1 About 84% by weight of 1, based on the total weight of the mixture.
1,2-trichloro-1,2,2-trifluoroethane, about 12% by weight acetone, about 2% by weight n
- About 5000 g of a solvent mixture containing hexane and about 1% by weight of nitromethane was produced. This mixture was transferred to a four-plate column, distillation head and ASTM
Distillation was carried out using a 5 3-necked flask with a graduated thermometer. The distillation step consisted of refluxing the solvent mixture for about 1 hour and collecting 8 fractions.
The first and last fractions of approximately 300 ml each were discarded, and the remaining fractions were redistilled for approximately 1 hour, and 6 fractions were collected. Again, the first and last fractions were discarded. The atmospheric pressure measured during distillation was approximately 754.2 mmHg. The distillation rate is approximately 10
ml/min. The average density is 25 (77〓) and is approximately 1.366
Four fractions of g/ml were collected at 44°C. The analysis of the four fractions by gas chromatography is shown in the following table:

[Table] Example 2 About 84% by weight of 1,1,2-trichloro-1,
The procedure of Example 1 was repeated with a solvent mixture containing 2,2-trifluoroethane, about 12% by weight acetone, about 2% by weight n-hexane, and about 1% by weight nitromethane. All weight percentages are based on the total weight of the mixture. The atmospheric pressure was approximately 744.4 mmHg.
The distillation rate was about 20 ml/min and the steam temperature was about 43.8°C. The specific gravity was approximately 1368 g/ml at 23°C (74〓). Four fractions were analyzed by gas chromatography.
The results are shown in the table below.

EXAMPLE 3 A series of experiments were conducted to determine the flash point of the novel azeotropic composition of the present invention. An analysis of the compositions used in these tests is shown in the following table. Surface Ingredients Weight % Trichlorotrifluoroethane 85.5 Acetone 12.4 Hexane 1.6 Nitromethane 0.5 The flash point of the above composition was determined according to ASTM method D1310 "Flash Point of Liquids by Tag Open-Cup Apparatus". The starting point for this test is 10℃ (50〓)
The solvent mixture was cooled so that This test was performed twice. The same results were obtained: this four-component mixture had no flash point and boiled at 46°C (114°C). Example 4 Representative embodiments of compositions of the invention were evaluated in stability tests. The analysis results of the compositions used in this test are shown in the following table. Surface Ingredients Weight % Trichlorotrifluoroethane 85.5 Acetone 12.4 Hexane 1.6 Nitromethane 0.5 The above composition was refluxed at autogenous pressure for 48 hours in the presence of zinc and aluminum metals. The compositions were then analyzed for the presence of chloride ions. The greater the amount of chloride ions, the more the solvent will decompose. For comparison, about 83 to about 85% by weight 1,1,2-trichloro-1,2,2-trifluoroethane, manufactured and sold by Allied under the trade name "GENESOLV 404", about
12.5 to about 13.5% by weight acetone and about 2.5 to about
Similar tests and analyzes were performed using an azeotropic composition containing 3.5% by weight n-hexane. The results of these tests are shown in the table below.

[Table] Example 5 The stability of another embodiment of the present invention was evaluated using the procedure of Example 4. Analysis of this composition is shown in the following table. Table Components Weight % Trichlorotrifluoroethane 85.8 Acetone 12.5 Hexane 1.6 Nitromethane 0.1 The results of this test are shown in the table below.

[Table] Example 6 The azeotropic composition of the present invention was prepared using a distillation process that resulted in a distillate that was more highly rectified than that found in most sought-after degreaser systems. Therefore, it can be limited. For this purpose, a five theoretical plate Oldershaw distillation column with cold water condensation, manual liquid separation head was used. Typically, about 350
cc of liquid was put into a distillation pot. This liquid is 1,
It was a mixture of various combinations of 1,2-trichloro-1,2,2-trifluoroethane, acetone, nitromethane and hexane. The mixture was heated at total reflux for approximately 1 hour to ensure equilibrium. In most cases,
The distillate was obtained at a boiling rate of 400-500 g/h and a reflux ratio of 2:1. Approximately 300 c.c. of product was distilled and 6
Two approximately equal amounts of overhead fractions were collected.
Vapor temperature (of the distillate), pot temperature and pressure were monitored. Fractions with a constant boiling point were collected, and the weight percentages of the components were determined by gas chromatography analysis. Next, a mixture consisting of the approximate composition of the fractions with a constant boiling point was prepared and redistilled under the same conditions. The composition of the distillate and residue was compared by chromatographic analysis to confirm that the mixture had a constant boiling point. A mixture of constant boiling point obtained by the above distillation method according to the present invention,
Shown in the table.

[Table] Examples 7-9 Using the distillation apparatus and procedure described in Example 6 above, a mixture of 1,1,2-trichloro-1,2,2-trifluoroethane, acetone, nitromethane and hexane was prepared. , we investigated the composition range where the boiling point is constant. In the distillation pot, 1,1,2-
A mixture of trichloro-1,2,2-trifluoroethane (FC-113), acetone, nitromethane and hexane was charged. These examples show that each hexane isomer is 1,
1,2-Trichloro-1,2,2-trifluoroethane exhibiting its own unique compositional identity in an azeotrope with acetone and nitromethane, and each hexane isomer and mixtures thereof. But with such components, about
This shows that an azeotropic mixture with a constant boiling point is formed at 44.0±0.2°C. This is quite surprising considering the considerable differences in boiling points between the various hexane isomers. The hexane isomers and their boiling points are shown in the table below. Table Standard boiling points of hexane isomers (°C) 2,2-dimethylbutane 49.75 (2,2-DMB) 2,3-dimethylbutane 58.1 (2,3-DMB) 2-methylpentane 60.13 (isohexane) (2-MP) 3-Methylpentane 64 (3-MP) n-hexane 68.74 (n-hex) Distillation was performed several times with various compositions of the starting mixture, and the resulting fractions with a constant boiling point were collected and analyzed by gas chromatography. was analyzed and the vapor temperature and pressure were recorded. To standardize the boiling points observed on different days for a mercury pressure of 760 mmHg,
The approximate normal boiling point of a mixture rich in 1,1,2-trichloro-1,2,2-trifluoroethane was estimated by applying a barometric correction factor of about 26 mm Hg/°C to the observed value. However, it should be noted that this corrected boiling point is generally accurate to ±0.4°C and is only useful for cursory comparisons of boiling points measured on different days. By the above method, a mixture with a constant boiling point boiling at about 44.0 ± 0.2°C at 760 mmHg can be obtained with a concentration of 77.9 to 81.3% by weight.
of 1,1,2-trichloro-1,2,2-trifluoroethane, 12.9-14.2% by weight of acetone,
0.05-0.2 wt% nitrilomethane and 5.6-7.9
% by weight of hexane. Confirmatory distillation data for the investigated mixtures are shown in the table.

【table】

【table】

[Table] From the foregoing, it is clear that other mixtures of the same components with constant or essentially constant boiling points can be readily identified by those skilled in the art using the methods described above. 1,1,2-trichloro-
The true azeotrope of the system consisting of 1,2,2-trifluoroethane, acetone, nitromethane and hexane, as well as the limits outside the compositional range where boiling points are constant or essentially constant, have not been well characterized or defined. I didn't add anything. As mentioned above, those skilled in the art will appreciate that "constant boiling point" or "essentially constant boiling point" for purposes of the present invention means that in the environment of a vapor degreaser system as used in the art, Keeping in mind that constant or essentially constant boiling point is meant, other mixtures with constant or essentially constant boiling point can be readily identified. All such mixtures according to the invention which have a constant or essentially constant boiling point are referred to herein as "azeotropic mixtures". Example 10 To illustrate the azeotropic properties of the mixture of the present invention under practical conditions in a vapor phase degreasing operation, about 81.3% by weight of 1,1,2-trichloro-1, 2,2-trifluoroethane (FC-
113), a preferred azeotrope of the present invention consisting of about 13.1% by weight acetone, about 5.4% by weight commercially available isohexane, and about 0.2% by weight nitromethane. The mixture was evaluated for boiling point constancy or non-separability. The solvent was Baron Blakeslee's cooled three-bore VPD.
(Series 5000-Model No. MLR-216). The charged solvent was refluxed and the composition of the individual reservoirs was determined on a Hurits Packard 5890 gas chromatograph. Reflux was continued for 21 hours, during which time the composition of the reservoir was monitored. A mixture was considered constant boiling or non-separable if the maximum concentration difference between the reservoirs was below 0.3% for any mixture component. If the mixture is not azeotropic, the high boiling components will rapidly condense in the boiling reservoir and the rinse reservoir will empty. As the data in the table shows, this did not occur. These results indicate that the compositions of the present invention do not condense in commercial vapor degreasers, thereby avoiding potential safety, performance and handling problems. Preferred compositions tested also meet ASTM D-56 (Tag Closed Cup) and ASTM D-
1310 (tag open cup), it was also found that it does not have a flash point.

[Table] Composition Example 11 This example describes the use of a preferred azeotropic composition of the present invention for cleaning metal parts. Cleaning was performed on a Branson B-400 double steam degreaser. The first reservoir is used as a working reservoir and is approximately
81.3% by weight of 1,1,2-trichloro-1,2,
2-trifluoroethane, about 13.2% by weight acetone, about 54% by weight commercially available isohexane and about
The solvent, consisting of 0.1% by weight nitromethane, was kept boiling. The second reservoir was used as a rinse reservoir. The cooled cooling coils are lined up on the upper inner wall of the device and kept covered with a blanket of steam. The stain was applied to two types of 1.9 cm x 7.6 cm (3/4" x 3") metal coupons. These were 316 stainless steel and 1010 cold rolled steel. The stain was selected from two types of metalworking fluids:

[Front] The metal coupon was polished to give it a new, clean surface. The coupons were rinsed with deionized water, followed by methanol, and air-dried for 10 minutes. Four identical coupons were then dipped into each metal working fluid. Cleaning tests were performed on these two coupons immediately after being immersed in metal working fluid. The other two coupons were tested after being left for 24 hours. The parts were placed on a shelf in a stainless steel wire mesh basket for cleaning. In the first step, the assembly is soaked in the working sump for 2 minutes and then in the rinse sump for 2 minutes.
Transfer for 2 minutes followed by solvent spray in the steam zone for 2 minutes. The final step is to remain in this vapor zone for 1 minute. The processed coupons were visually inspected for any remaining soil. A drain test was also conducted in which the coupons were immersed in water and drained for 10 seconds. During the 10 second drain period, the surface of the coupon was examined to see if the water film had broken. The coupon was considered to be generally clean if no remaining dirt or breaks in the water film were visible on the coupon surface during the drain test. "316" stainless steel coupons were stained with Trimsol metal working fluid and "1010" cold rolled steel coupons were stained with Hocut 711 metal working fluid in the manner described above.
All of these soiled coupons were cleaned with the preferred azeotropic composition of the present invention and evaluated for cleanliness as described above. All coupons were determined to be completely clean.

Claims (1)

[Claims] 1. Trichlorotrifluoroethane, acetone,
Solvent cleaning consisting of nitromethane and hexane,
Azeotrope-like composition for vapor degreasing. 2 The above trichlorotrifluoroethane is 1,
The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 1, which is 1,2-trichloro-1,2,2-trifluoroethane. 3. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is n-hexane. 4. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is 2-methylpentane. 5. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is 3-methylpentane. 6. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is 2,2-dimethylbutane. 7. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is 2,3-dimethylbutane. 8. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, wherein the hexane is isohexane. 9 Consisting of 72.7 to 87.8% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane, 10.0 to 16.6% by weight of acetone, 0.005 to 1.5% by weight of nitromethane and 0.2 to 10.6% by weight of hexane. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2. 10 77.9 to 87.6% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane, 10.0
3. The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, which comprises 1 to 14.2% by weight of acetone, 0.05 to 0.9% by weight of nitromethane, and 1.0 to 7.9% by weight of hexane. 11 85.0 to 86.5% by weight of 1,1,2-trichloro-1,2,2-trifluoroethane, 12.0
from 1.0 to 13.0% by weight acetone, from 0.03 to 0.5% by weight nitromethane and from 1.0 to 2.0% by weight n
- The azeotrope-like composition for solvent cleaning and vapor degreasing according to claim 2, which comprises hexane.