MXPA99008885A - Molecular level cleaning of contaminates from parts utilizing an environmentally safe solvent - Google Patents

Abstract

The invention provides a solvent mixture comprising n-propyl bromide, a mixture of low boiling solvents and, preferably, a defluxing and/or ionics removing additive and/or at least one saturated terpene. The invention also provides a method of cleaning an article (e.g., an electrical, plastic, or metal part) in a vapor degreaser using the solvent mixture. The solvent mixture of the invention is non-flammable, non-corrosive, and non-hazardous. In addition, it has a high solvency and a very low ozone depletion potential. Thus, using the solvent mixture of the invention, oil, grease, rosin flux, and other organic material can be readily removed from the article of interest in an environmentally safe manner.

Description

MOLECULAR CLEANING OF PARAMETERS CONTAMINANTS USING AN ENVIRONMENTALLY SAFE SOLVENT CROSS REFERENCE TO RELATED REQUEST This is a continuation of part of the co-pending US patent application serial number 08 / 580,840 filed on December 29, 1995, now US patent No. 5,616,549 issued on April 1, 1997. FIELD OF THE INVENTION The invention relates, in general terms, to the cleaning at the molecular level of parts by means of degreasing with steam. More particularly, the invention relates to a mixture of solvents comprising n-propyl bromide, a mixture of low boiling point solvents and, preferably, a flux removal agent and / or removal of ionic species and / or at least one saturated terpene, as well as a method of cleaning an article in a steam degreaser using the solvent mixture. The solvent mixture of the present invention is non-combustible, non-corrosive, non-hazardous, and has a low potential for destruction of the ozone layer. BACKGROUND OF THE INVENTION Cleaning at the molecular level by means of degreasing in steam has been widely accepted in the industry. In fact, cleaning at the molecular level by degreasing steam it is a preferred method for cleaning precision parts, for example, electronic parts, machined metal parts, etc., since steam cleaning virtually leaves no residue on the parts. Generally, a degreasing of steam includes the heating of a solvent to its boiling point in order to generate a vapor layer in which the object to be cleaned is placed. The steam condenses on the object and subject the surface to a cleaning action with solvent as it flows down. The cleaning action with solvent dissolves the hydrocarbon contaminants and removes them from the object, cleaning it in this way. The drops of liquid are then collected in a tank and vaporized again, typically by the use of steam heating coils. Thus, the surface of the object is continuously rinsed with fresh solvents. There are four general types of degreasers in the vapor phase. The simplest form of a vapor degreaser is the direct steam cycle degreaser that uses only steam for cleaning. As the parts are introduced into the hot steam, the steam condenses on the cold parts and dissolves the oils and fats from the surface. The oily condensate falls into the liquid solvent at the base of the tank. The solvent is continuously evaporated to form a vapor layer. Since the oils are not vaporized, they remain in the background of the tank in the form of a sediment. The action of extracting impurities from the condensing steam continues until the temperature of the part reaches the temperature of the vapor when the condensation is suspended, the part has a dry appearance, and is removed from the degreaser. The time required to reach this point depends on the particular solvent used, the temperature of the steam, the weight of the part, its specific heat and the type of contamination material to be removed. This particular vapor phase degreaser has an excellent performance in that it dries the parts after an aqueous cleaning and before coating application, and, therefore, is frequently used for this purpose in jewelery. Unfortunately, however, it is not as effective in the case of small, low-weight parts, because such parts frequently reach the temperature of the vapor before the condensation action has completely cleaned the parts. A second type of steam degreaser, that is, the vapor-spray cycle degreaser, is frequently used to solve the problems associated with the direct steam cycle degreaser. In this steam-spray cycle degreaser, the part to be sprayed is placed first in the vapor zone as in the case of the direct steam cycle degreaser. A portion of the steam is condensed by the action of coils of Cool and fill a liquid solvent tank. This hot liquid solvent is pumped up to a spray nozzle that can be used to direct the solvent over the part, removing the surface oils and cooling the part, thus cleaning by steam condensation. The third type of vapor degreaser is a liquid-vapor cycle degreaser that has one compartment with a hot solvent and another compartment with a vapor zone. This degreaser is especially useful in the case of very dirty parts either to clean a basket or small parts that are nested together. The fourth type of vapor degreaser is the ultrasonic degreaser. Such degreasers are useful for cleaning critical parts. An ultrasonic degreaser has a transducer mounted on the base of the tank that operates within a range of 20 kHz to 40 kHz. The transducer alternately compresses and expands the solvent to form small bubbles that, in turn, cavitate or collapse on the surface of the part. This phenomenon of cavitation upsets the adhering dirt, thus cleansing the part. Conventional solvents used with the aforementioned vapor phase degreasers include trichlorethylene, perchlorethylene, methyl chloroform, methylene chloride, CFC 113, dibromomethane, bromochloromethane, trichlorotrifluoroethane and various hydrochlorofluorocarbons, for example "Genesolve" (manufactured by Allied Chemical). Steam degreasing techniques employing the aforementioned solvents or equivalents thereof are presented in U.S. Patent No. 3,881,941 which was issued on May 6, 1995 to Carl Martin Brock. Unfortunately, however, such solvents are typically found in the Pure Air Act's list of chemicals that destroy the ozone layer and, as a result, their production is being progressively suspended and / or their use is prohibited in the United States. United of America. Thus, there is a need for a solvent that can be used in place of these chemicals that destroy the ozone layer forbidden in vapor phase degreasers. U.S. Patent No. 4,056,403, which was issued to Robert J. Cramer, et al, on November 1, 1977, describes a method in which various unregulated ozone-depleting chemicals, including bromide, are used. -propyl, to clean a polyurethane foam generating equipment. Cramer et al., Presents a method where a solvent composition described herein is used to clean a polyurethane foam generating apparatus or a segment thereof. The solvents presented can be periodically injected under pressure through the mixer portion of the forming apparatus of foam in order to purge it of unreacted waste or materials of partial foam formation. Unfortunately, the method described in this patent would be totally ineffective because its composition does not include the appropriate stabilizers necessary to prevent the n-propyl bromide from becoming acidic and consequently attacking the metal surfaces that may be caused in the vapor layer. The use of hot saturated vapors of a liquid halogenated hydrocarbon, including bromochloromethane, is presented in U.S. Patent No. 4,193,838 which was issued to Robert J. Kelly, et al, on March 18, 1990. More particularly, this patent teaches the generation of a set of hot saturated vapors of a halogenated acrylic hydrocarbon. Paper parts coated with the "hot melt" coatings, such as those used in consumer items and milk cartons, etc., are then placed in the steam assembly and subsequently agitated. Again, it is observed that this method would be ineffective for cleaning flux and other articles due to the acid nature of the unstabilized compound used there which would tend to destroy the object instead of just cleaning it. U.S. Patent No. 5,403,507, which was assigned to Richard G. Henry on April 4, 1995, presents a mixture of solvents for use in degreasing by steam cleaning. Dibromomethane is used as the main component. Dibromomethane is mixed with other solvents in order to stabilize the dibromomethane and prevent the solvent mixture from becoming acidic when the bromide is released into the atmosphere. Even though the solvent mixture presented herein is more stable than other solvent mixtures presented in U.S. Patent Nos. 4,056,403 and 4,193,838, there remain a large number of disadvantages associated with the use of dibromomethane which makes this agent unsuitable for its use as a solvent in degreasers in the vapor phase. In fact, the Clean Air Act now integrates dibromomethane into the list of chemical agents that destroy the ozone layer that are prohibited from being used in steam degreasers or through any other cleaning process that results in a release to the atmosphere. Taking into account the above, it is readily apparent that there continues to be a need in the art for a solvent mixture that is suitable for the molecular level cleaning of parts without the use of any chemical ozone destruction agent that are identified as class I or class II materials in the US Federal Register volume 58, number 236, Friday, December 10, 1993, regulations and bromochloromethane as potential ozone destructor and possible prohibition in the US Federal Register 40 CFR part 82, volume 60, number 145, pages 38729-38734, July 28, 1995. COMPENDIUM OF THE INVENTION It is an object of the present invention to overcome at least one of the problems described above. Accordingly, the invention offers a mixture of solvents that can be employed in vapor phase degreasers instead of more traditional solvents. More particularly, the invention offers a mixture of solvents for use in a steam degreasing system. The solvent mixture comprises effective amounts of n-propyl bromide and at least one low-boiling solvent or a mixture thereof and, preferably, a flux removal additive and / or removal of ionic species and / or at least a saturated terpene. In another aspect, the invention provides a method for cleaning an article in a steam degreaser, the method comprising: (a) providing a vapor degreaser system; (b) adding the solvent mixture of the present invention to the solvent tank of the steam degreaser system; (c) boiling the solvent mixture to form a vapor layer; (d) inserting an article to be cleaned in the vapor layer; and, (e) remove the article from the vapor layer.

In this method, the vapor layer condenses on the article, thus subjecting the surface of the article to a cleaning action with solvent as the solvent flows downward. The cleaning action with solvent dissolves the hydrocarbon contaminants and removes them from the object, cleaning it in this way. By using the method of the present invention, oil, grease, rosin flux and other organic material can be easily removed from the article of interest. Other features, objects and advantages of the present invention and their preferred embodiments will be apparent from a review of the following detailed description. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED MODALITIES The solvent mixture of the present invention is non-combustible, non-corrosive, and non-hazardous. In addition, it has a high dissolution capacity and a low ozone layer destruction potential typically between 0.001 and 0.04 and a global warming potential typically between 0.0001 and 0.0003. As such, the solvent mixture of the present invention can be effectively employed to remove oil, grease, rosin flux, and other organic contaminants from the surface of various articles, for example electrical, plastic and metal parts. Preferably, the invention offers a mixture of solvents for use in a vapor degreasing system, the solvent mixture comprises: (a) from about 85% by weight to less than about 96.5% by weight of n-propyl bromide; (b) from 0% to about 6.5% by weight of a saturated terpene or a mixture of saturated terpenes, the mixture of terpenes preferably comprises from about 35% by weight to about 50% by weight of cis-pinene and about 35% by weight to about 50% by weight of trans-pine; (c) an effective amount, preferably from about 3.5 wt% to about 5 wt% of a low boiling point solvent mixture, the low boiling point solvent mixture preferably comprises about 0.5 wt% to about 1% by weight of nitromethane, from about 0.5% by weight to about 1% by weight of 1,2-butylene oxide and from about 2.5% by weight to about 3% by weight of 1,3-dioxolane; and (d) from 0 wt% to about 5 wt% of at least one flux removal additive and / or ion removal selected from the group consisting of sec-butanol, ethanol, and methanol. In a currently preferred embodiment, the terpene mixture of cis-pinene and trans-pinene includes terpenes. Suitable terpenes include, but are not limited to, one or more of the following: endo-isocanfen, alpha-pinene, cis-para- mint and trans-for-menthane. In another preferred embodiment, the pentene mixture also includes endo-isocanfen, alpha-pinene, cis-para-menthane and trans-para-menthane. If present, these terpenes can individually represent up to 100% of the terpene content of the solvent mixture and, preferably, from about 0.01% by weight to about 6.5% by weight of the solvent mixture, and preferably even higher, from about 0.05% by weight to about 5% by weight of the solvent mixture. One of the functions of the low-boiling solvent or low-boiling solvent mixture is to neutralize any free acid that could result from the oxidation of the mixture in the presence of air, from the hydrolysis of the mixture in the presence of of water, and of the pyrolysis of the mixture under the influence of high temperatures. In addition, the low-boiling solvent or solvent mixture serves to prevent pitting or corrosion of metallic articles placed in the vapor layer. It has been found that the mixture of solvents of the present invention fulfills the desired characteristics for an appropriate cleaning of electrical parts, metals, plastics, elastomers, circuit boards, etc. More particularly, the solvent mixture of the present invention has the following characteristics: (1) it is stabilized appropriately against any free acid that could result from the oxidation of the mixture in the presence of air, from the hydrolysis of the mixture in the presence of water, and from the pyrolysis of the mixture under the influence of high temperatures; (2) is non-combustible and non-corrosive; (3) the various components of the solvent mixture are not regulated by the American Clean Air Act; and (4) none of the various components of the solvent mixture are agents known to cause cancer (ie, the various components do not belong to the lists developed by NTI, IARC and California Proposition 65, (California proposal 65), they are regulated by OSHA). Furthermore, the solvent mixture of the present invention has a high solution capacity with a caori-butanol value above 120 and, more preferably above 125. In addition, the solvent mixture of the present invention has a lower evaporation rate 0.96 where the one of 1,1,1-trichloroethane equals 1. Upon evaporation, the solvent mixture of the present invention leaves a non-volatile residue (NVR) of less than 2.5 mg (or less about 500 ppm) and, more preferably, said solvent mixture upon evaporation leaves no residue. In addition, the solvent mixture of the present invention has a latent vaporization temperature of about 58.8 cal / g which, in turn, facilitates the condensation of the solvent mixture on the side of a standard vapor degreaser system. In addition, the use of n-propyl bromide in the solvent mixture of the present invention has significant advantages compared to the use of dibromomethane and bromochloromethane. In contrast to n-propyl bromide, dibromomethane is on the list developed by the Clean Air Act as a chemical substance that destroys the ozone layer that is prohibited for use in degreasing in steam or in other processes. cleaning involving the release to the atmosphere and it is suspected that bromochloromethane has an ODP greater than 0.1 where the ODP of the 1, 1, 1-trichloroethane prohibited is equal to 0.1 and the bromochloroethane will not obtain SNAP approval and may be prohibited. In addition, in contrast to n-propyl bromide having an atmospheric life of about 7 to 14 days and an ODP of 0.001 to 0.04, dibromomethane has an atmospheric life of about 3 years and bromochloromethane of 3 to 4 months and a ODP from 0.08 to 1.2. Dibromomethane is more toxic than n-propyl bromide and, in contrast to n-propyl bromide, dibromomethane exhibits bioaccumulation (for example, in fish and aquatic life). In addition, while both dibromomethane and n-propyl bromide react with strong bases, strong oxidizing agents, aluminum, calcium, zinc, magnesium, alloys, etc., the compounds formed with dibromomethane are typically sensitive to shocks and, therefore, potentially explosive while compounds formed with n-propyl bromide are not. In addition, the chemical and physical properties of the solvent mixtures based on n-propyl bromide of the present invention make them more efficient from an energy perspective than the solvent mixture of bromochloromethane or dibromomethane of the prior art or the forbidden solvents. , 1-trichlorethylene, trichlorethylene, or methylene chloride. As a result of its boiling point, physical heats and latent heat of vaporization, the solvent mixtures based on n-propyl bromide of the present invention require approximately the same amount or less energy to cause the boiling of the mixture and create a denser steam zone for cleaning. The sec-butanol, ethanol, and / or methanol present in the solvent mixture functions as an auxiliary for flux removal and / or removal of ionic species in steam degreasing and cold batch cleaning operations. The presence of sec-butanol increases the removal of flux for R-type, RMA-type, RA-type and synthetic fluxes. The sec-butanol also increases the cleaning of polar and non-polar dirt including hand oils, welding oils, greases, silicones, and similar soils.

Methanol is effective to increase the removal of type A and RMA type fluxes. Ethanol, when present, forms an azeotropic mixture with n-propyl bromide, and is especially useful for the removal of fluxes from welded metal parts. The agent for removing fluxes and / or ionic species or mixtures of agents is typically employed in an effective amount of up to about 5% by weight, preferably 3% by weight or less, and highly preferably, of about 1% in weight, based on the total composition of solvents. As a result of the aforementioned properties, the solvent mixture of the present invention can be usefully employed in vapor phase degreasers instead of traditional solvents including, for example, trichlorethylene, perchlorethylene, methyl chloroform, methylene chloride, trichlorotrifluoroethane, dibromomethane, CFC-113, etc. In addition, the solvent mixture of the invention can be effectively employed in the four main types of vapor phase degreasers, namely, the direct steam cycle degreaser, the steam-spray cycle degreaser, and the liquid-vapor degreaser and the ultrasonic degreaser. In addition, emissions from a vapor phase degreaser operated with the solvent mixture of the present invention are so low that they are not it requires a local exhaust ventilation system, even though, in some cases, such a system may be desirable. The solvent composition of the present invention is prepared in a simple manner by combining and mixing together the n-propyl bromide, the mixture of terpenes (if present), the low-boiling solvent mixture, and the Flux removal agent and / or removal of ionic species (if present) in the desired or specified proportions. The solvent mixture is then ready for use as the solvent in a vapor phase degreaser system. N-propyl bromide (C3H7Br, ie, CH3CH2CH2Br) is commercially available from Dead Sea Bromine LTD Israel. The terpenes used to make the terpene mixture are commercially available from SCM Glidco Jacksonville FL. Notrometane (CH3N02), 1/3-dioxolone, and 1,2-butylene oxide (also known as 1,2-epoxybutane) are commercially available from Aldrich Chemical Co. (Mil aukee, Wisconsin). Sec-butanol is also available from Aldrich Chemical Co. In addition to acquiring the above compounds from commercial sources, it will be apparent to those skilled in the art that such compounds can be easily synthesized using known synthetic methods. For example, n-propyl bromide can be prepared by, for example, when alcohols react either with inorganic acid halides or with hydrogen halides. (See, for example, Cari R. Noller, Textbook of Organic Chemistry, Ch 6:81 (1956), whose teachings are incorporated herein by reference). In another aspect, the invention provides a method for cleaning articles in a steam degreaser using the solvent mixture of the invention. In this method, the solvent mixture of the invention is added to a metal degreaser, such as for example Baron-Blakesles or Branson models. The thermostat in the steam degreaser is typically adjusted to a temperature of about 156 ° F to about 160 ° F. (Ultrasonic degreasers can operate effectively at temperatures from 70 ° F.) In this temperature range, the n-propyl bromide present in the solvent mixture will be boiling. When the solvent mixture reaches a temperature of about 156 ° F to about 160 ° F, a layer of vapor will appear on the solvent in the form of a mist. This vapor mist constitutes the main characteristic of steam cleaning. When the vapor mist appears, the object to be cleaned is placed in the vapor layer. The steam condenses on the object and subject the surface of the object to a cleaning action with solvent as it flows down. The cleaning action with solvent dissolves the hydrocarbon contaminants and removes them from the object, cleaning it from this shape. The liquid drops are then collected in a tank where they are vaporized again, typically through the use of steam heating coils. Thus, the surface of the object is continuously rinsed with fresh solvent. By using the method of the present invention, oil, grease, rosin flux and other organic material can easily be removed from the object of interest. In addition, vapors from the solvent will not contain any of the contaminants removed and, consequently, the Vapors can be used to clean additional objects. The invention will be described in more detail through specific examples. The following examples are offered by way of illustration, and are not intended to limit or define the invention in any way. EXAMPLE I A mixture of solvents according to the present invention was mixed and added together to a standard steam degreaser, the solvent mixture consisted of the following: (i) about 90.0% by weight of n-propyl bromide; (ii) about 6% by weight of a mixture of saturated terpenes, the terpene mixture comprised about 45% by weight of cis-pinene, about 45% of trans-pinene, about 2% by weight of endo-isocanfen, about 2% by weight. % by weight of alpha- pinene, about 2% by weight of cis-para-menthane and about 2% by weight of trans-para-menthane; and (iii) about 4% by weight of a low boiling solvent mixture, the low boiling solvent mixture comprised about 0.5% by weight of nitromethane, about 0.5% by weight of 1,2-oxide. butylene, and about 3% by weight of 1,3-dioxolane. The thermostat in the steam degreaser was adjusted to a temperature of approximately 160 ° F, and the system was allowed to equilibrate. After the mixture inside the solvent tank had reached a temperature of approximately 160 ° F, the mixture began to boil. Upon inspection, a layer of steam several inches thick was observed inside the steam degreaser unit. Sufficient steam was created to condense and circulate from the cooled side of the steam degreaser to the boiling side of the steam degreaser. EXAMPLE II Fifteen gallons of the solvent mixture described in Example I were added to a vapor phase degreaser. The thermostat in the steam degreaser was adjusted to a temperature of approximately 160 ° F, and the system was allowed to equilibrate. After the mixture inside the solvent tank had reached a temperature of about 160 ° F, the mixture began to boil. A basket of steel parts covered with lithium-based grease was placed in the vapor layer. After a period of about 30 seconds, the basket of steel parts was removed from the vapor layer. All the lithium-based grease had been removed and the steel parts were completely clean. Using a procedure similar to the one just described, sheet metal parts containing light mineral oils, silicone oils, lithium fats, and other types of industrial fluids were placed in the vapor layer for cleaning. After a period of about 1 minute, the metal pieces in the mine were removed from the vapor layer. All contaminants, ie, light mineral oils, silicone oils, lithium fats, and other types of industrial fluids, had been removed. EXAMPLE III Fifteen gallons of the solvent mixture described in Example I were added to an ultrasonic degreaser that effectively operates with the solvent mixture of the present invention at temperatures in the range of 70 ° F to about 160 ° F. The ultrasonic degreaser had a transducer mounted on the base of the tank that operates within a range of 30 kHz to 40 kHz. The thermostat in the ultrasonic degreaser was adjusted to a temperature of approximately 160 ° F, and the system was allowed to I will balance The ultrasonic degreaser also uses water cooled coils to control solvent vapors and to eliminate the need for a local exhaust ventilation system. Several steel parts coated with lithium grease were immersed in the solvent for a period of about 1 minute. The transducer alternately compressed and expanded the solvent to form small bubbles, which in turn cavitated on the surface of the steel parts coated with lithium grease. The cavitation phenomenon affected the adhering dirt and cleaned the parts. Using a procedure similar to the one just described, sheet metal parts containing light mineral oils, silicone oils, lithium fats, and other types of industrial fluids were immersed in the ultrasonic degreaser. After a period of approximately 1 minute, the pieces of metal in the mine were removed from the vapor layer. All contaminants, ie, light mineral oils, silicone oils, lithium fats, and other types of industrial fluids have been removed. EXAMPLE IV Five gallons of the solvent mixture described in Example I were added to an emulsion immersion tank. A part of steel coated with lithium grease was immersed for one minute in an immersion tank in emulsion containing the solvent mixture at room temperature. While a certain cleaning was observed, the resulting cleaning was not at the molecular level. Similarly, five gallons of the solvent mixture described in Example I were added to a heated potent washing emulsion degreaser. The thermostat in this degreaser was set at a temperature of 156 ° F, just below the boiling point of n-propyl bromide, and the system was allowed to equilibrate. Then, the solvent mixture was sprayed on steel parts that were coated with lithium grease. When reviewing, it was observed that the resulting cleaning was at the molecular level. EXAMPLE V Standard corrosion tests, similar to those performed by the Dow Chemical Company, were performed using the solvent mixture of the invention, since oxidation is a potential problem with all solvent cleaners. In addition, a methodology similar to that used by the Dow Chemical Company was used to show the equivalences with the existing solvents prohibited by the Clean Air Act. When performing these tests, copper and steel strips one inch wide by 6 inches long and 20 mils thick were subjected to polishing on a belt sandpaper in order to remove any rust film. 15 milliliters of the solvent mixture described was placed in example I in a cylindrical Pyrex glass container and the strips were placed in such a way that 75% of the surface was immersed in the solvent. A sample container filled with tap water was used as control for the test in order to ensure that no alloys were present in the metal strips that could have prevented oxidation. The openings of the sample containers were sealed with cork stoppers in order to reduce evaporation. After an incubation period of 8 hours and an incubation period of 24 hours, the strips were removed and it was determined that the solvent mixture of the present invention was not corrosive. It is understood that the above description is intended to illustrate the present invention and not to limit it. Many modalities will be apparent to people with knowledge in the matter when reading the previous description. The scope of the present invention will therefore be determined not with reference to the foregoing description, but with reference to the appended claims, together with the full scope of equivalents of such claims. Disclosures of all articles and references including patent applications and patent publications are incorporated herein by reference.

Claims (2)

1. CLAIMS 1. A mixture of solvents for use in a steam degreaser system, said solvent mixture comprising: (a) from about 85% by weight to less than about 96.5% by weight of n-propyl bromide; (b) of about 3.5% by weight unless about 15% by weight of a low boiling solvent mixture, said solvent mixture comprises from about 0.5% by weight to about 1% by weight of nitromethane, of about 0.5% by weight to about 1% by weight of 1,2-butylene oxide, and from about 2.5% by weight to about 3% by weight of 1,3-dioxolane; and (c) an effective amount of up to about 5% by weight of at least one additive selected from the group consisting of sec-butanol, ethanol, and methanol. . The solvent mixture of claim 1, further comprising an effective amount of at least one saturated terpene. . The solvent mixture of claim 2, which comprises up to about 6.5% by weight of a mixture of cis-pinene and trans-pinene terpenes. . The solvent mixture of claim 3, wherein said mixture of terpenes comprises about 35% in weight to about 50% by weight of cis-pinene and from about 35% by weight to about 50% by weight of trans-pinene. 5. The solvent mixture of claim 2, wherein said mixture of terpenes further comprises at least one terpene selected from the group consisting of endo-isocanfen, alpha-pinene, cis-para-menthane, and trans-paramethane. 6. The solvent mixture of claim 2, wherein said mixture of terpenes further comprises endo-isocanfen, alpha-pinene, cis-para-menthane, and trans-para-menthane. The solvent mixture of claim 1, wherein said additive consists essentially of up to about 3% by weight of sec-butanol. 8. The solvent mixture of claim 7, wherein said sec-butanol comprises about 1% by weight of said solvent mixture. 9. A method for cleaning an article in a steam degreaser, said method comprising: (a) providing a vapor degreaser system; (b) adding a mixture of solvents to the solvent tank of said vapor degreaser system, said solvent mixture comprising: i) from about 85% by weight to less than about 96.5% by weight of n-propyl bromide; ii) of about 3.5 wt% to less than about 15 wt% of a low boiling solvent mixture, said solvent mixture comprises from about 0.05 wt% to about 1 wt% nitromethane, of about 0.5 % by weight to about 1% by weight of 1,2-butylene oxide and from about 2.5% by weight to about 3% by weight of 1,3-dioxolone; and iii) an effective amount of up to about 5% by weight of at least one additive selected from the group consisting of sec-butanol, ethanol, and methanol; (c) boiling said mixture of solvents to form a vapor layer; (d) introducing into said steam layer said article to be cleaned, said vapor layer condenses in said article, thus subjecting the surface of said article to a cleaning action with solvent; and (e) removing said article from said vapor layer. The method of claim 9, further comprising an effective amount of at least one saturated terpene. The method of claim 10, which comprises up to about 6.5% by weight of a mixture of cis-pinene and trans-pinene terpenes.
2. 2. The method of claim 11, wherein said mixture of terpenes comprises from about 35% by weight to about 50% by weight of cis-pinene and from about 35% by weight to about 50% by weight of trans-pinene. The method of claim 10, wherein said mixture of terpenes further comprises a terpene selected from the group consisting of endo-isocanfen, alpha-pinene, cis-para-menthane and trans-para-menthane. The method of claim 10, wherein said mixture of terpenes further comprises endo-isocanfen, alpha-pinene, cis-para-menthane and trans-para-menthane. The method of claim 9, wherein said flux removal additive consists essentially of up to about 3% by weight of sec-butanol. The method of claim 15, wherein said sec-butanol comprises about 1% by weight of said solvent mixture.