EP0525122A1 - Procede ameliore pour enlever les revetements de substrats fragiles, et dispositif de sablage utile a cette fin - Google Patents

Procede ameliore pour enlever les revetements de substrats fragiles, et dispositif de sablage utile a cette fin

Info

Publication number
EP0525122A1
EP0525122A1 EP91911117A EP91911117A EP0525122A1 EP 0525122 A1 EP0525122 A1 EP 0525122A1 EP 91911117 A EP91911117 A EP 91911117A EP 91911117 A EP91911117 A EP 91911117A EP 0525122 A1 EP0525122 A1 EP 0525122A1
Authority
EP
European Patent Office
Prior art keywords
bicarbonate
blasting
hydrophobic silica
microns
average particle
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.)
Ceased
Application number
EP91911117A
Other languages
German (de)
English (en)
Other versions
EP0525122A4 (en
Inventor
Lawrence Kirschner
Michael Stephen Lajoie
William E. Spears, Jr.
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.)
Church and Dwight Co Inc
Original Assignee
Church and Dwight Co Inc
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 Church and Dwight Co Inc filed Critical Church and Dwight Co Inc
Publication of EP0525122A1 publication Critical patent/EP0525122A1/fr
Publication of EP0525122A4 publication Critical patent/EP0525122A4/en
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0084—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a mixture of liquid and gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/08—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for polishing surfaces, e.g. smoothing a surface by making use of liquid-borne abrasives
    • B24C1/086—Descaling; Removing coating films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C11/00—Selection of abrasive materials or additives for abrasive blasts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C11/00—Selection of abrasive materials or additives for abrasive blasts
    • B24C11/005—Selection of abrasive materials or additives for abrasive blasts of additives, e.g. anti-corrosive or disinfecting agents in solid, liquid or gaseous form
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0046—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier
    • B24C7/0053—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier with control of feed parameters, e.g. feed rate of abrasive material or carrier
    • B24C7/0061—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier with control of feed parameters, e.g. feed rate of abrasive material or carrier of feed pressure

Definitions

  • TITLE IMPROVED PROCESS FOR REMOVING COATINGS FROM SENSITIVE SUBSTRATES, AND BLASTING MEDIA USEFUL THEREIN
  • This invention relates to a process for removing coatings from sensitive metal and composite surfaces or like substrates, and to blasting media useful therein.
  • Blasting media useful for such purposes should, preferably, meet the following criteria:
  • Sodium bicarbonate has also been proposed as a blasting medium for removing coatings from sensitive substrates such as aircraft parts.
  • Bicarbonate is an ideal choice for such a medium since it readily meets criteria 1, 2 and 4 above.
  • it is relatively non-aggressive (Mohs hardness of about 2.5), is available in a variety of particle sizes, and is both water soluble and commonly utilized to treat sewage treatment facilities for the control of alkalinity and pH.
  • the mild abrasive characteristics of sodium bicarbonate have previously been utilized, for example, in polishing media for teeth. See, for example, U.S. Patents Nos.
  • TCP tricalciu phosphate
  • Bicarbonate blasting media which may be so utilized are free flowing and have long storage lives under adverse commercial blasting conditions, and may be utilized as blasting media at high humidities and under a broad range of finely controlled, high flow rates and air pressures.
  • a process for removing coatings from sensitive substrates comprising blasting such surfaces with a high velocity fluid stream, desirably a substantially saturated compressed air stream under a pressure of about 10-150 psi, containing as a blasting medium crystalline water-soluble bicarbonate particles having average particle sizes within the range of about 100-500, preferably about 250-300, microns, desirably in admixture with at least about 0.2%, preferably about 0.2-3%, of a hydrophobic silica flow/anti-caking agent, by weight of the bicarbonate.
  • hydrophobic silica to the blasting medium imparts significantly better flow characteristics than comparable media which are either free of flow aids or which contain other conventional flow aids such as TCP or hydrophilic silica.
  • bicarbonate blasting media incorporating the hydrophobic silica flow aid have significantly longer, substantially indefinite shelf lives, and exhibit superior resistance to the high relative humidities of commercial compressed air streams.
  • crystalline sodium bicarbonate As the abrasive material in the blasting media of this invention. It is, however, intended that other crystalline water-soluble bicarbonates, e.g., alkali metal bicarbonates such as potassium bicarbonate, or ammonium bicarbonate may similarly be employed. Accordingly, while the following description principally refers to the preferred crystalline sodium bicarbonate-containing blasting media, it will be understood that the invention embraces blasting media incorporating other water-soluble crystalline bicarbonate abrasives as well.
  • Hydrophobic silica has previously been utilized in admixture with hydrophilic silica as a flow aid in polishing media for dental prophylaxis. Such media are applied under conditions which differ dramatically from commercial blasting media.
  • dental prophylaxis media contain bicarbonate particles having particle sizes of about 65-70 microns, and are applied at rates of about 3 grams per minute through 1/16-1/32 inch nozzles under the pressure of clean, laboratory compressed air supplies under pressures of about 50-100 psi. Most important, such air supplies are not substantially saturated with moisture, and present quite different flow and caking problems from those inherent in the application of commercial blasting media at high thruputs in saturated compressed air blast streams.
  • the blasting media of the invention consist essentially of the crystalline water-soluble bicarbonate, e.g., sodium bicarbonate, in admixture with hydrophobic silica particles.
  • Hydrophobic silica unlike known hydrophilic silicas, is substantially free of non-hydrogen bonded silanol groups and absorbed water.
  • Aerosil R 972 a product which is available from Degussa AG.
  • This material is a pure coagulated silicon dioxide aerosol, in which about 75% of the silanol groups on the surface thereof are chemically reacted with dimethyldichlorosilane, the resulting product having about 0.7 mmol of chemically combined methyl groups per 100m 2 of surface area and contai.ni.ng about 1% carbon. Its particles vary in diameter between about 10-40 nanometers and have a specific
  • the hydrophobic silica particles are admixed with the crystalline sodium bicarbonate blasting agent in the proportion of at least about 0.2%, and up to about 3% by weight thereof.
  • the crystalline bicarbonate particles may be of any desired average particle size, within the range of from about 100 to 500 microns.
  • Blasting media thus constituted are useful for cleaning or de-coating sensitive metals, e.g., aluminum or aluminum alloys, or composite substrates, such as utilized on exterior aircraft surfaces, without abrading or otherwise damaging the substrates.
  • Composites which can be treated with the blasting media hereof comprise matrices, e.g., epoxy resins, which may contain fibers such as glass strands, graphite or the like for reinforcement.
  • the blasting medium thus constituted is preferably applied in commercial compressed air streams, i.e., streams which are substantially saturated with moisture (90% or higher relative humidities) and contain oil contaminants from compressors.
  • a stream of water may be added to the media/air stream to cool the workpiece and control dust formation, although the addition of water may reduce the coating removal rate somewhat.
  • the bicarbonate/hydrophobic silica blasting medium may be applied at flow rates of about 1-10, desirably about three to four, pounds per minute and under air pressures of about 10-150 psi, from 1/4 inch or larger blasting nozzles.
  • blasting media so constituted and employed do not cake, have excellent shelf lives, and are free-flowing. They may thus be readily employed in commercial blasting operations for removing coatings from sensitive metal and composite surfaces.
  • Figure 1 is an electron scanning photomicrograph of a clad aluminum test panel which has visible corrosion at the surface, penetrating the cladding, prior to blasting;
  • Figure 2 is an electron scanning photomicrograph of a clad aluminum test panel which has been cleaned according to the process of the invention. It is apparent that the surface corrosion by-product materials have been removed without damaging the metal surface;
  • Figure 3 is a graph comparing production rates obtained employing bicarbonate blasting media having different average particle sizes, at varying feed rates.
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples illustrate the free-flowing characteristics of (Example 1), and the high production rates obtained by (Examples 2 and 3), the blasting media of the present invention. In the examples, all parts and percentages are given by weight and all temperatures in °F unless otherwise indicated.
  • EXAMPLE 1 Two crystalline sodium bicarbonate samples, each having an average particle size of about 250-300 microns, and one in admixture with 0.5% Aerosil R-972 hydrophobic silica, were used as media in a standard sand blasting apparatus.
  • the apparatus was a Schmidt Accustrip System, manufactured by Schmidt Manufacturing, Inc. of Houston, Texas, having a 0.5 inch nozzle diameter and a Thompson valve connected to a 6 cubic foot blast pot and an 800 cfm compressor. The blast pot was mounted on a scale so that media flow rates could be determined.
  • the crystalline sodium bicarbonate particles absent the hydrophobic silica flow aid flowed intermittently through the system, rapidly clogging the nozzle and preventing further flow. Sustained flow could not be maintained.
  • the crystalline bicarbonate-hydrophobic silica formulation flowed continuously through the system for more than 65 hours at controllable rates varying from 1 pound per minute to 5 pounds per minute. No flow problems were encountered therewith.
  • Test panels of aluminum, two feet by two feet by 0.032 inch thick were cleaned by treating with water, washing with phosphoric acid solution, rinsing with water, applying Alodyne corrosion inhibitor, and rinsing with a final water rinse.
  • An epoxide primer was applied and the panels were dried in air for eight hours.
  • a polyurethane paint was then applied and the panels were dried for seven days.
  • the panels were then aged for 96 hours in an air oven at 210°F.
  • the target thickness for the paint and primer was 2 mils.
  • the blasting media consisted of 99.5% sodium bicarbonate (in differing particle sizes) and 0.5% Aerosil E972 hydrophobic silica.
  • the nozzle pressure was set at 60 psi and -li ⁇
  • the media were placed under differential pressure sufficient to give the desired feed rate.
  • the water pressure was set at a pressure of 200 psi, yielding a flow of 0.5 gal/min.
  • the angle blast nozzle made with the workpiece was set at 60°.
  • the media feed rates were varied from two to four lbs/min.
  • the production rates and average particle sizes of the bicarbonates in the respective media were as follows:
  • Example 2 The blasting medium described in Example 1, incorporating a crystalline sodium bicarbonate having an average particle size of about 250-300 microns, in admixture with 0.5% Aerosil R-972 hydrophobic silica, was compared with a blasting medium incorporating a compacted bicarbonate, having particles in the range of -20 mesh to +40 mesh, in admixture with a like amount (0.5%) of the same hydrophobic silica flow aid.
  • the respective media were utilized to depaint aluminum test panels in the manner described in Example 2.
  • the maximum production rates obtained with the respective media were determined, and are tabulated below.
  • the tabulation shows the improved production rate achieved using the blasting medium incorporating the crystalline sodium bicarbonate rather than the medium incorporating the compacted sodium bicarbonate:
  • the present invention provides an improved process for cleaning or removing paint or other coatings from the surfaces of sensitive substrates, and to crystalline sodium bicarbonate-containing blasting media useful therein. It will be understood that various changes may be made in the blasting process and blasting media exemplified in the preferred embodiments described hereinabove without departing from the scope of the invention. Accordingly, the preceding description should be construed as illustrative and not in a limiting sense.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Paints Or Removers (AREA)
  • Detergent Compositions (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

Dispositif de sablage utilisé pour enlever les revêtements de surfaces métalliques et composites fragiles, et procédé utile à cette fin. Le dispositif de sablage emploie des particules de bicarbonate de sodium cristallin soluble dans l'eau ayant des dimensions de particules moyennes de 100-500 microns, avec un flux de silice hydrophobe/agent anti-agglutinant.
EP19910911117 1990-04-06 1991-04-04 Improved process for removing coatings from sensitive substrates, and blasting media useful therein Ceased EP0525122A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US50644790A 1990-04-06 1990-04-06
US506447 1990-04-06

Publications (2)

Publication Number Publication Date
EP0525122A1 true EP0525122A1 (fr) 1993-02-03
EP0525122A4 EP0525122A4 (en) 1993-04-28

Family

ID=24014633

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910911117 Ceased EP0525122A4 (en) 1990-04-06 1991-04-04 Improved process for removing coatings from sensitive substrates, and blasting media useful therein

Country Status (12)

Country Link
EP (1) EP0525122A4 (fr)
JP (1) JPH0669668B2 (fr)
KR (1) KR960003113B1 (fr)
CN (1) CN1029599C (fr)
AU (1) AU643039B2 (fr)
CA (1) CA2079892C (fr)
MY (1) MY109653A (fr)
NO (1) NO176751C (fr)
NZ (1) NZ237596A (fr)
PL (1) PL165174B1 (fr)
TR (1) TR25589A (fr)
WO (1) WO1991015308A1 (fr)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5232514A (en) * 1991-10-10 1993-08-03 Church & Dwight Co., Inc. Corrosion-inhibiting cleaning systems for aluminum surfaces, particularly aluminum aircraft surfaces
CA2122361C (fr) * 1992-03-20 1998-06-16 Lawrence Kirschner Agent abrasif pour l'elimination des revetements et procede d'utilisation
US5593339A (en) * 1993-08-12 1997-01-14 Church & Dwight Co., Inc. Slurry cleaning process
NL1003398C2 (nl) * 1996-06-21 1997-12-23 Delwi Ontwikkelingen B V Werkwijze en materiaal voor het reinigen van binnenwanden van kanaalvormige ruimten.
US6010546A (en) * 1997-07-24 2000-01-04 Asahi Glass Company, Ltd. Blasting medium and blasting method employing such medium
NL1007501C2 (nl) * 1997-11-10 1999-05-11 Pieter Schurink Werkwijze en medium voor het reinigen van oppervlakken.
DE19842054A1 (de) 1998-09-15 2000-03-16 Bayer Ag Verwendung von wasserlöslichen polymeren Polycarboxylaten in Reinigerformulierungen mit abrasiver Wirkung
DE19842053A1 (de) 1998-09-15 2000-03-23 Bayer Ag Verwendung von Polyasparaginsäuren in Reinigerformulierungen mit abrasiver Wirkung
GB2565122A (en) * 2017-08-03 2019-02-06 Rolls Royce Plc Gas turbine engine
FR3102694B1 (fr) * 2019-10-30 2022-06-03 Safran Aircraft Engines Procede de compactage d’un revetement anti-corrosion
CN111673622A (zh) * 2020-06-01 2020-09-18 江苏佰健环保科技有限公司 食品器具不沾涂层环保清除工艺及其设备
CN113996602A (zh) * 2021-11-02 2022-02-01 东南大学 一种印制电路板的孔道钻污清洗方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963627A (en) * 1970-02-16 1976-06-15 Imperial Chemical Industries Limited Surface treatment of particulate solids
US4412402A (en) * 1978-07-28 1983-11-01 Cavitron Inc. Equipment and method for delivering an abrasive-laden gas stream
WO1990011163A2 (fr) * 1989-03-14 1990-10-04 Church & Dwight Co., Inc. Procede d'elimination de revêtements sur des substrats sensibles, et milieux de projection abrasifs utiles dans ledit procede

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA532346A (fr) * 1956-10-30 D. Smith Rowland Methode a nettoyer des outils a travailler le verre
US2710286A (en) * 1953-02-25 1955-06-07 Rca Corp Method of removing and salvaging adherent materials
US4020857A (en) * 1976-04-13 1977-05-03 Louis Frank Rendemonti Apparatus and method for pressure cleaning and waxing automobiles and the like
GB1603085A (en) * 1977-06-03 1981-11-18 Ciba Geigy Uk Ltd Fire protection means
US4174531A (en) * 1977-11-14 1979-11-13 Rca Corporation Printed circuit board with increased arc track resistance
US4174571A (en) * 1978-07-28 1979-11-20 Dentron, Inc. Method for cleaning teeth
SE455265B (sv) * 1984-03-27 1988-07-04 Arne Alvemarker Blesterkroppar av kompositmaterial for att rengora diskgods
US4588444A (en) * 1984-04-04 1986-05-13 Anderson Ronald L Method for cleaning polymeric contact lenses
US4731125A (en) * 1984-04-19 1988-03-15 Carr Lawrence S Media blast paint removal system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963627A (en) * 1970-02-16 1976-06-15 Imperial Chemical Industries Limited Surface treatment of particulate solids
US4412402A (en) * 1978-07-28 1983-11-01 Cavitron Inc. Equipment and method for delivering an abrasive-laden gas stream
WO1990011163A2 (fr) * 1989-03-14 1990-10-04 Church & Dwight Co., Inc. Procede d'elimination de revêtements sur des substrats sensibles, et milieux de projection abrasifs utiles dans ledit procede

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9115308A1 *

Also Published As

Publication number Publication date
PL165174B1 (pl) 1994-11-30
JPH0669668B2 (ja) 1994-09-07
NZ237596A (en) 1993-03-26
EP0525122A4 (en) 1993-04-28
TR25589A (tr) 1993-07-01
MY109653A (en) 1997-03-31
NO923823L (no) 1992-11-30
CA2079892C (fr) 1996-01-23
NO176751C (no) 1995-05-24
WO1991015308A1 (fr) 1991-10-17
NO176751B (no) 1995-02-13
CN1029599C (zh) 1995-08-30
CN1056077A (zh) 1991-11-13
AU643039B2 (en) 1993-11-04
AU7982891A (en) 1991-10-30
NO923823D0 (no) 1992-10-01
KR960003113B1 (ko) 1996-03-05
JPH05504919A (ja) 1993-07-29
CA2079892A1 (fr) 1991-10-07

Similar Documents

Publication Publication Date Title
US5160547A (en) Process for removing coatings from sensitive substrates, and blasting media useful therein
US5509971A (en) Process for removing coatings from hard surfaces
AU643039B2 (en) Improved process for removing coatings from sensitive substrates, and blasting media useful therein
US5308404A (en) Less aggressive blast media formed from compacted particles
US5112406A (en) Process for removing coatings from sensitive substrates, and sodium sulfate-containing blasting media useful therein
EP0463121B1 (fr) Procede d'elimination de revetements sur des substrats sensibles, et milieux de projection abrasifs utiles dans ledit procede
US5669945A (en) Abrasive blast media containing corrosion inhibitor
IL97705A (en) Process for removing coatings from sensitive surfaces and sodium bicarbonate preparations for its use
US6007639A (en) Blasting process for removing contaminants from substrates and potassium magnesium sulfate-containing blast media

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: 19921005

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

A4 Supplementary search report drawn up and despatched
AK Designated contracting states

Kind code of ref document: A4

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

17Q First examination report despatched

Effective date: 19930820

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

Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED

18R Application refused

Effective date: 19940611