Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/50—Solvents
  • C11D7/5036—Azeotropic mixtures containing halogenated solvents
  • C11D7/5068—Mixtures of halogenated and non-halogenated solvents
  • C11D7/5077—Mixtures of only oxygen-containing solvents
  • C11D7/5081—Mixtures of only oxygen-containing solvents the oxygen-containing solvents being alcohols only
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/50—Solvents
  • C11D7/5036—Azeotropic mixtures containing halogenated solvents
  • C11D7/504—Azeotropic mixtures containing halogenated solvents all solvents being halogenated hydrocarbons
  • C11D7/5059—Mixtures containing (hydro)chlorocarbons
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
  • C23G5/02—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents
  • C23G5/028—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents containing halogenated hydrocarbons
  • C23G5/02809—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents containing halogenated hydrocarbons containing chlorine and fluorine
  • C23G5/02825—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents containing halogenated hydrocarbons containing chlorine and fluorine containing hydrogen
  • C23G5/02841—Propanes
  • C23G5/02851—C2HCl2F5

Definitions

• This invention relates to solvent cleaning applications in which contaminated articles such as, for example, metals, textiles, glass, plastics, electronic components and printed circuit boards are cleaned using a solvent and/or solvent vapour and more particularly to solvent mixtures useful in solvent cleaning applications and their use.
• Solvent cleaning applications wherein contaminated articles are immersed in or washed with halogenated hydrocarbon solvents and/or the vapours thereof are well known and are in common use. Applications involving several stages of immersion, rinsing and drying are common and it is well known to use the solvent at ambient temperature (often accompanied by ultrasonic agitation) or at an elevated temperature up to the boiling point of the solvent. Examples of solvents used in these cleaning processes are 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,1-trichloroethane, trichloroethylene, perchloroethylene and methylene chloride.
• solvents are used alone or in mixtures with cosolvents such as aliphatic alcohols or other low molecular weight, polar additives and depending to some extent upon the articles to be cleaned are often stabilised against degradation induced by light, heat and the presence of metals.
• the use of the common cleaning solvents has been regarded as an acceptable practice in that the solvents are stable, non-flammable materials of relatively low toxicity believed to be environmentally benign.
• some at least of the common solvents may have a long-term deleterious effect on the stratosphere, the so-called ozone layer, so that replacement solvents are seen to be desirable.
• a solvent cleaning composition comprising a mixture of at least one isomer of dichloropentafluoropropane and 1,1-dichloroethane.
• the dichloropentafluoropropane may be a mixture of isomers but preferably contains at least a major proportion of 1,1-dichloro-2,2,3,3,3-pentafluoropropane, which is known in the art as "225ca".
• 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,1-dichloroethane form an azeotrope or essentially azeotropic mixture and the azeotrope is a preferred cleaning composition according to the invention, particularly in boiling-solvent cleaning applications.
• the azeotrope consists of about 80.5% by weight 1,1-dichloro-2,2,3,3,3-pentafluoropropane and about 19.5% by weight 1,1-dichloroethane and has a boiling point of about 51.4°C.
• azeotrope Whilst an azeotrope may be preferred since it maintains an essentially constant composition in use, we have found that some non-azeotropic mixtures, for example that containing about 18% by weight of 1,1-dichloro-2,2,3,3,3-pentafluoropropane, do in fact exhibit acceptable compositional stability in use and may be attractive in affording the possibility of controlling the cleaning power of the cleaning composition.
• the amounts of dichloropentafluoropropane and 1,1-dichloroethane in the mixture may vary within wide limits but the mixture should contain sufficient dichloropentafluoropropane to render the mixture non-flammable so that it does not have a flash point.
• the mixture should contain at least 15% by weight of the dichloropentafluoropropane.
• Useful mixtures comprise from 15% to 90% by weight of dichloropentafluoropropane. It is often preferred that the mixture contains from 20% to 80% by weight of the dichloropentafluoropropane. However, we have found that at less than 20% w/w the dichloropentafluoropropane is an effective diluent for 1,1-dichloroethane.
• 1,1,2-trichloro-1,2,2-trifluoroethane there are two preferred mixtures for replacing the presently commonly used solvents 1,1,2-trichloro-1,2,2-trifluoroethane and 1,1,1-trichloroethane.
• One such mixture comprises about 50:50% by weight of the dichloropentafluoropropane and 1,1-dichloroethane; the other comprises about 18:80% by weight dichloropentafluoropropane: 1,1-dichloroethane.
• the cleaning composition may contain an aliphatic hydrocarbon and/or a polar compound, for example an aliphatic alcohol, preferably an alcohol containing from 2 to 6 carbon atoms.
• an aliphatic alcohol preferably an alcohol containing from 2 to 6 carbon atoms.
• the amount of the alcohol may be up to 50% by weight of the composition, although amounts below about 10% are preferred.
• a typical ternary mixture contains from about 2% to about 7% by weight of alcohol.
• 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,1-dichloroethane and some at least of the lower alkanols form azeotropes and such ternary azeotropes represent another preferred feature of the invention, particularly in boiling-solvent cleaning applications.
• the azeotrope containing methanol boils at about 46.4°C and consists of about 76.3% by weight the dichloropentafluoropropane, about 17.7% by weight of 1,1-dichloroethane and about 6% by weight of methanol.
• the azeotrope containing ethanol boils at about 51°C and consists of about 79% by weight of the dichloropentafluoropropane, about 18% by weight of 1,1-dichloroethane and about 3% by weight of ethanol.
• a ternary azeotrope containing propanol does not appear to be produced.
• the cleaning composition may contain an aliphatic hydrocarbon, acyclic or cyclic saturated or ethylenically unsaturated hydrocarbons being examples of suitable components.
• Suitable hydrocarbons which should be liquids at room temperature, include those having a boiling point in the range 30°C to 75°C, preferably 40°C to 65°C.
• a particularly suitable hydrocarbon for use with 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,1,-dichloroethane is cyclopentane, b.p 50°C, although the compounds do not appear to form a ternary azeotrope.
• suitable hydrocarbons for incorporation in the solvent cleaning composition according to the present invention may be mentioned inter alia:
• the amount of the hydrocarbon in the solvent cleaning composition may vary within wide limits, for example from 20% to 80% by weight.
• hydrocarbons are generally readily flammable and the amount of the hydrocarbon should preferably be such that the composition remains non-flammable.
• the combined amount of hydrocarbon and 1,1-dichloroethane, which is also flammable should preferably be below that at which the composition is flammable and exhibits a flash point.
• any vapours emitted during use of the composition should preferably also be non-flammable.
• compositions of the invention may contain one or more stabilisers as are often used in known cleaning compositions, notably nitroalkanes and epoxides.
• the cleaning compositions of the invention may be used as replacements for the solvents used in any of the known cleaning applications and a process is provided according the invention for cleaning articles which comprises contacting the article(s) with the cleaning composition and/or the vapour thereof.
• the compositions may be used in cold cleaning applications but will usually be employed at an elevated temperature up to their boiling points.
• This Example illustrates the use of an azeotropic mixture according to the present invention for the removal of flux from a printed circuit board.
• 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,1-dichloroethane (80.5% halopropane/19.5% haloethane) was used to remove ionic solder flux residues from circuit boards by the following procedure.
• solder cream was applied to test boards (5 cm x 7 cm) cut from a copper-coated FR4 board and reflowed in a Micro VPS unit.
• the solder cream was a 62% tin/38% lead solder available as Multicore PRAB 3.
• the solvent was boiled in a beaker fitted with an upper cooling coil through which cold water was circulated to create a boiling liquid phase and a vapour phase.
• the contaminated test board was dipped into the boiling liquid for 60 seconds and then held in the vapour for 30 seconds.
• Residual ionic contamination of the test board expressed as mg sodium chloride per square centimetre, was determined using a Protonique Contaminometer. The ionic contamination of an unwashed test board was determined and the % removal of ionic contamination by the cleaning procedure was calculated. 72.4% of ionic contaminants were removed.
• Example 1 The test procedure described in Example 1 was repeated using the ternary azeotropes described in Table 1.
• This Example illustrates the compatibility of solvent cleaning compositions according to the present invention with plastics materials.
• Nitromethane (0.3% by weight) was added to the azeotropic mixtures described in Table 3 and the resulting solvents (50 ml) were charged to a reflux apparatus heated on an oil bath.
• test pieces of aluminium, zinc and mild steel were located in the reflux apparatus, partly immersed in the boiling solvent. After approximately 3 days the metal test pieces and the solvent were removed for analysis. The metal pieces were washed with a small amount of deionised water (which was retained and used later to extract ionic species from the used solvent), rinsed with more water and brushed free of any deposits. They were then rinsed with acetone, dried and re-weighed.
• the used solvent was extracted with the metal rinse water (see above) and the extract was analysed for chloride and fluoride ions.
• the mild steel test pieces were clean and bright and there was no visual evidence of a tidemark corresponding to the liquid/vapour interface.
• the aluminium test pieces and the zinc test pieces were also clean and bright although a very slight tidemark was observed on each test piece.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Detergent Compositions (AREA)
• Manufacturing Of Printed Wiring (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

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Publications (2)

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Cited By (3)

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Citations (2)

• 1990
  • 1990-04-04 GB GB909007578A patent/GB9007578D0/en active Pending
• 1991
  • 1991-03-27 EP EP19910302702 patent/EP0450856A3/en not_active Withdrawn
  • 1991-03-27 IE IE102691A patent/IE911026A1/en unknown
  • 1991-03-28 AU AU73914/91A patent/AU7391491A/en not_active Abandoned
  • 1991-04-04 JP JP3071817A patent/JPH05295394A/ja active Pending
  • 1991-04-04 CA CA002039829A patent/CA2039829A1/fr not_active Abandoned
  • 1991-04-04 KR KR1019910005445A patent/KR910018531A/ko not_active Application Discontinuation

Patent Citations (2)

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