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EP0127643A1 - Procede de nettoyage d'articles recourant a des gaz surcritiques - Google Patents

Procede de nettoyage d'articles recourant a des gaz surcritiques

Info

Publication number
EP0127643A1
EP0127643A1 EP83903757A EP83903757A EP0127643A1 EP 0127643 A1 EP0127643 A1 EP 0127643A1 EP 83903757 A EP83903757 A EP 83903757A EP 83903757 A EP83903757 A EP 83903757A EP 0127643 A1 EP0127643 A1 EP 0127643A1
Authority
EP
European Patent Office
Prior art keywords
gas
article
contaminants
super
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83903757A
Other languages
German (de)
English (en)
Inventor
William A. Mueller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Co
Original Assignee
Hughes Aircraft Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hughes Aircraft Co filed Critical Hughes Aircraft Co
Publication of EP0127643A1 publication Critical patent/EP0127643A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/0021—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by liquid gases or supercritical fluids

Definitions

  • This invention relates in general to a method of removing contaminants from articles and, in particular, to a simple, rapid and effective method of removing from the surface and interstices of a solid article a variety of contaminants with which the article may possibly have come in contact during its manufacture. More specifically, the present invention relates to a method of removing organic contaminants from such articles using gases in the super-critical state.
  • Components and materials used in the manufacture of instruments for aerospace applications must be free from contaminants.
  • the contamination of the component may consist of saponifiable- materials such as oils as well as non-saponifiable materials such as resins.
  • Components formed from metal or synthetic plastic materials may contain gaseous or vaporizable contaminant residues from the manufacture and processing of the metal such as uncured prepolymers, release agents and unreacted monomers used in the processing of these materials.
  • thermal vacuum cleaning To effect the required level of cleaning of the materials used in the manufacture of components which meet government standards for cleanliness, the art has developed cleaning processes for these materials utilizing high vacuum, e.g., lO""**-* torr (millimeters of mercury or mmHg) and elevated temperatures up to 250°C to remove absorbed and adsorbed organic contaminants from the materials.
  • This cleaning technique referred to in the art as "thermal vacuum cleaning" is not completely satisfactory in that the cleaning process must be carried out in an expensive and complex high vacuum system which normally requires about fifteen hours to obtain the desired contaminant free surface.
  • the rapid removal of organic-based contaminants from articles, both porous and non-porous, without damage or contamination to the article is effected by contacting the article bearing the contaminant in a pressure vessel with a gas under super-critical conditions of temperature and pressure, whereby the contaminant on the surface and/or in the interstices of the article is absorbed by the gas and, thereafter, purging the gas from the pressure vessel to obtain the article having the contaminant removed therefrom.
  • surfaces is meant not only exterior surfaces but also interior surfaces which communicate therewith.
  • the critical temperature As the gas is subjected to increasingly higher pressure, e.g., on the order of several thousand pounds per square inch (psi) (one psi equals 51.71493 mm of mercury), the density of the gas approaches that of a liquid and the gas acts as a solvent for a variety of different types of organic and organo-metallic materials, including aliphatic and aromatic hydrocarbon organo- metallics such as metal alkyIs and alcoholates, silicones and boroalkyls and organic esters or inorganic acids such as sulfuric and phosphoric acid.
  • the critical temperatures and pressures for a variety of gases at which they exist in the super-critical condition may be found in U.S. Patent No. 4,124,528, the teachings of which are hereby incorporated by reference.
  • the article of manufacture to be cleaned is placed in a suitable vessel such as a pressure chamber or autoclave and the gas which is to effect the cleaning of the article surface is admitted to the vessel in a super ⁇ critical condition.
  • Cleaning of the article is accomplished in the pressurized vessel under conditions which maintain the super-critical condition of the gas used for cleaning.
  • the cleaning is conducted at a temperature range of about 35°C to about 100°C at about 1200 psi (62,058 mmHg) to about 10,000 psi (517,149 mmHg) pressure and preferably about 40°C to about 50°C and about 3,000 psi (155,145 mmHg) to about 8,000 psi (413,719 mmHg) pressure.
  • Inert gases having a critical temperature below about 200°C are considered most advantageous in the practice of the present invention.
  • CC1 2 F 2 , 2 0, noble gases such as argon, NH3 and N .
  • Gases such as CO2 are preferred in the practice of the present invention as the super-critical temperature of such gases is near ambient temperature; the gases are inexpensive, non-toxic, and relatively inert to most solid substrates.
  • C0 is especially preferred as this gas in the super-critical state has a very low viscosity, namely 0.05 centipoise, which is one-twentieth that of water. As a result, the gas in the super-critical state can penetrate very readily into the contaminant to effect its rapid removal from the article being cleaned.
  • the article to be cleaned be preheated prior to its place ⁇ ment in the pressure vessel to a temperature above ambient, e.g., about 30°C to about 100°C, and preferably about 40° to 50°C.
  • the absorptive capacity of the gases in the super ⁇ critical condition with respect to most contaminants, and particularly contaminants of basically organic origin, is raised with increased pressure.
  • a pressure which is substantially higher than the critical pressure of the gas and a temperature only slightly above the critical temperature is selected for maintaining the gas in the super-critical condition.
  • the temperature and pressure conditions under which the gas is caused to contact the article to be cleaned be sufficiently above the critical temperature and pressure in order to have a single physical phase, i.e., the gaseous phase, of the gas present in the pressurized vessel during the cleaning operation.
  • the gas when such gas is used as the cleaning medium, the gas is maintained at a temperature of about 35°C to about 100°C and a pressure of 2,000 psi (103,430 mmHg) to 10,000 psi (517,149 mmHg) in the pressure vessel.
  • the article when placed in the pressure vessel for cleaning, is contacted with the gas under super-critical conditions for a period of time ranging from about 0.25 hour to about four hours and preferably about 0.5 hour to about one hour to effect complete removal of contaminants.
  • the pressure in the vessel is released and the gas containing the absorbed contaminants are vented or purged from the vessel into the atmosphere.
  • the cleaned article is then removed from the vessel.
  • the gas in the super ⁇ critical condition is vented or purged from the pressurized vessel into a suitable collection vessel where the pressure is reduced or the temperature lowered at constant pressure, which conditions render the gas a non-solvent for the contaminant which then precipitates from the gas.
  • the gas, freed of contaminants, can then be recompressed and recycled for use in the cleaning of contaminated articles.
  • Example I A high pressure autoclave (10,000 psi or 517,149 mmHg maximum working pressure) of 300 milliliter (ml) capacity was equipped with a gas inlet, a gas outlet, pressure gauge, a thermocouple well, and heating means. Connected to the gas inlet was a CO2 supply bottle which delivered the C0 at 800 psi (41,372 mmHg) gauge. A gas booster pump operating on the 100 psi (5171 mmHg) shop air and having the capability to raise the bottle pressure to a maximum to 10,000 psi
  • Example I The procedure of Example I was repeated to clean a polyimide polymer containing contamination in the form of volatile solvents by exposure to CO2 for one hour under super-critical conditions of 8,000 psi (413,719 mmHg) pressure and a temperature of 45 ⁇ C.
  • OMPI under conditions of 125°C temperature and a vacuum of 10 ⁇ 5 torr (mmHg) or thermogravimetry mass spectrometry (TGA-MS) under conditions of one atmosphere and temperatures of 210°C or 820 ⁇ C.
  • TGA-MS thermogravimetry mass spectrometry
  • Example III The procedure of Example I was repeated with the exception that thin-sectioned parts of less than 0.25 inch thickness of a diverse selection of organic and inorganic materials were cleaned by exposure to C0 2 under super-critical conditions with only minor changes in the mechanical and physical properties of the materials being observed thereafter.
  • the laser casting alloy was subjected to a vacuum- pressure cycle in silicone oil (Dow-Corning DC-200) to saturate the metal with the silicone oil.
  • the oil- saturated metal part was then cleaned according to Military Interim Specification (MIS) 23542D, a cleaning specification for these parts.
  • MIS-23542D the material to be cleaned is subjected to an exhaustive extraction in a Soxhlet apparatus using toluene as the solvent followed by evaporation of the solvent and an infrared (IR) spectra examination of the residue.
  • the IR examination must indicate the absence of silicone or other residues to establish removal of all traces of silicone oil contaminant. To achieve this result required four days of treatment with the Soxhlet extraction apparatus, whereas by using the procedure of Example I, removal of all traces of silicon oil contaminants from a similar laser casting alloy similarly saturated with silicone oil was achieved in two hours.

Landscapes

  • Cleaning In General (AREA)
  • Detergent Compositions (AREA)

Abstract

Au cours de la fabrication de toute sorte d'articles, des substances contaminantes organiques se fixent aux surfaces de ces articles et doivent en être ultérieurement retirées. Le procédé décrit est efficace pour retirer des substances contaminantes organiques de toute sorte d'articles et pour permettre de retirer rapidement de telles substances contaminantes sans endommager l'article. Ce procédé est spécialement utile pour nettoyer les composants utilisés dans le domaine aérospatial. Dans le procédé décrit, un composant structural portant la substance contaminante est mis en contact dans un récipient à pression avec un gaz dans des conditions de température et de pression surcritiques, ce qui entraîne l'absorption de la substance contaminante par le gaz. Le gaz, ayant absorbé la substance contaminante, est ensuite évacué du récipient afin d'obtenir un composant nettoyé.
EP83903757A 1982-12-06 1983-10-31 Procede de nettoyage d'articles recourant a des gaz surcritiques Withdrawn EP0127643A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US44693982A 1982-12-06 1982-12-06
US446939 1982-12-06

Publications (1)

Publication Number Publication Date
EP0127643A1 true EP0127643A1 (fr) 1984-12-12

Family

ID=23774383

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83903757A Withdrawn EP0127643A1 (fr) 1982-12-06 1983-10-31 Procede de nettoyage d'articles recourant a des gaz surcritiques

Country Status (5)

Country Link
EP (1) EP0127643A1 (fr)
KR (1) KR840007367A (fr)
ES (1) ES527786A1 (fr)
IT (1) IT1175802B (fr)
WO (1) WO1984002291A1 (fr)

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5013366A (en) * 1988-12-07 1991-05-07 Hughes Aircraft Company Cleaning process using phase shifting of dense phase gases
US5068040A (en) * 1989-04-03 1991-11-26 Hughes Aircraft Company Dense phase gas photochemical process for substrate treatment
JPH03202102A (ja) * 1989-12-28 1991-09-03 Toray Dow Corning Silicone Co Ltd オルガノポリシロキサン成形物中のシロキサンオリゴマー量の減少方法
AT395951B (de) * 1991-02-19 1993-04-26 Union Ind Compr Gase Gmbh Reinigung von werkstuecken mit organischen rueckstaenden
US5482371A (en) * 1991-04-18 1996-01-09 Osaka Sanso Kogyo Ltd. Method and apparatus for measuring the dew point and/or frost point of a gas having low water content
JP2863663B2 (ja) * 1991-04-18 1999-03-03 大阪酸素工業株式会社 光学式露点計の反射鏡の洗浄方法及び洗浄装置付き光学式露点計
US5470154A (en) * 1991-04-18 1995-11-28 Osaka Sanso Kogyo Ltd. Method of cleaning the reflector mirror in an optical dew point meter and an optical dew point meter equipped with a cleaning device
DE4123288C2 (de) * 1991-07-13 1994-11-17 Reinhard Knof Verfahren zur Behandlung von kristallinem Siliziumdioxid-Granulat
FR2686351A1 (fr) * 1992-01-20 1993-07-23 Metalimphy Procede de nettoyage et degraissage de produits metalliques conditionnes sous forme de bobine ou de feuilles formant tas et installation pour sa mise en óoeuvre.
US5316591A (en) * 1992-08-10 1994-05-31 Hughes Aircraft Company Cleaning by cavitation in liquefied gas
DE4309734A1 (de) * 1993-03-25 1994-09-29 Akzo Nobel Nv Verfahren zum Reinigen von Hohlfasern
US5481058A (en) * 1994-01-07 1996-01-02 Minnesota Mining And Manufacturing Company Supercritical fluid extraction involving hydrofluoroalkanes
DE4423188C2 (de) * 1994-07-01 1999-03-11 Linde Ag Reinigung von Druckgasbehältern
US6248797B1 (en) * 1999-05-17 2001-06-19 Shelton A. Dias Supercritical carbon dioxide extraction of contaminants from ion exchange resins
US6589355B1 (en) * 1999-10-29 2003-07-08 Alliedsignal Inc. Cleaning processes using hydrofluorocarbon and/or hydrochlorofluorocarbon compounds
KR100447942B1 (ko) * 2001-07-04 2004-09-08 한국화학연구원 고압 전처리와 초임계 유체 세정에 의한 분리막 성능의 유지 및 복원방법
US7267727B2 (en) 2002-09-24 2007-09-11 Air Products And Chemicals, Inc. Processing of semiconductor components with dense processing fluids and ultrasonic energy
US7282099B2 (en) 2002-09-24 2007-10-16 Air Products And Chemicals, Inc. Dense phase processing fluids for microelectronic component manufacture
US6880560B2 (en) 2002-11-18 2005-04-19 Techsonic Substrate processing apparatus for processing substrates using dense phase gas and sonic waves
US20050029492A1 (en) 2003-08-05 2005-02-10 Hoshang Subawalla Processing of semiconductor substrates with dense fluids comprising acetylenic diols and/or alcohols
US7195676B2 (en) 2004-07-13 2007-03-27 Air Products And Chemicals, Inc. Method for removal of flux and other residue in dense fluid systems

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1493190C3 (de) * 1963-04-16 1980-10-16 Studiengesellschaft Kohle Mbh, 4330 Muelheim Verfahren zur Trennung von Stoffgemischen
US4124528A (en) * 1974-10-04 1978-11-07 Arthur D. Little, Inc. Process for regenerating adsorbents with supercritical fluids

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8402291A1 *

Also Published As

Publication number Publication date
WO1984002291A1 (fr) 1984-06-21
IT8349424A0 (it) 1983-12-02
KR840007367A (ko) 1984-12-07
IT1175802B (it) 1987-07-15
ES527786A1 (es) 1985-05-16

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19840711

AK Designated contracting states

Designated state(s): BE CH DE FR GB LI SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19851029

RIN1 Information on inventor provided before grant (corrected)

Inventor name: MUELLER, WILLIAM, A.