Classifications

• • 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
  • B24C11/00—Selection of abrasive materials or additives for abrasive blasts

Definitions

• the invention relates to shot blasting medium particularly such a medium which is used to shot blast to clean and to protect a surface which is In wet or damp conditions, such as a steel or concrete underwater structure, for example a pile,
• Protective coating systems have been formulated for application to surfaces under wet or damp conditions.
• the substrate or surface to be treated requires special preparation prior to the application of the particular formulation being used.
• Blasting the surface with grit is a known procedure. This cleans the surface, but the surface immediately begins to corrode and the permissible time between the shot blasting with grit and the application of the system can be as low as a few seconds depending on the temperature and the biological activity of the water.
• a shot blasting medium comprising a plurality of discrete particles which in use is able to clean a surface at which it is directed, characterised in that substantially all of the particles have a coating comprising means for protecting the surface.
• the coating may also comprise a biocide. This helps to inhibit the inception of marine growth on the cleaned surface.
• the carrier may comprise an organic resin and otke coating may comprise corrosion inhibitor or prevention agent.
• A' suitable corrosion prevention agent may be zinc dust.
• the carrier may alternatively comprise an organo-titanate compound.
• the particles may each comprise a grit of a mineral slag material, for example a copper slag material. This is hard yet light enough to be projected in a stream against a surface to be cleaned.
• a standard grit of a copper slag base or core was coated with resin such as an epoxy resin, preferably solid, or rosin, and its derivatives, prior to the addition of the coating of zinc dust or other corrosion inhibiting agents and a biocide.
• resin such as an epoxy resin, preferably solid, or rosin, and its derivatives, prior to the addition of the coating of zinc dust or other corrosion inhibiting agents and a biocide.
• a target surface was subjected to shot blasting using this medium, both above and below the water-line. It was found that the surface was cleaned by the grit and the coating inhibited corrosion, and particularly the settlement of marine growth, for up to eight minutes (during which time the protective system could be applied). It will be understood that when the particles impinge on the target surface, the copper slag base cleans that surface and the zinc dust and resin are transferred to the cleaned surface.
• the resin both acts as a carrier to adhere the zinc dust to the particles and, subsequently, to adhere the zinc dust to the cleaned surface, which is protected prior to subsequent treatment as by painting.
• the biocide was the agent inhibiting the marine growth formation.
• the grit can be coated with a resin as follows:-
• the resin preferably a solid epoxy resin
• solvent preferably a 50% solids content by weight.
• the grit (particles) to be coated is put in a rotatable drum.
• the solution is added to the drum which is then rotated until each particle of grit is evenly coated with resin solution.
• a calculated quantity of zinc dust is thenadded to the drum which is again rotated until the particles are evenly coated with zinc dust.
• the coated grit is then allowed to dry, for example by blowing heated air through the drum. Any additional materials such as biocides for the coating are added to the resin solution prior to coating the particles.
• the zinc dust is very fine, the particle size being such that 99.9% passes a B. S. 240 mesh sieve.
• the average particle size of such a dust varies between 2.25 and 3 microns.
• Grit used in shot-blasting may be directed at the surface to be treated from a nozzle to which there Is secured a shroud or skirt.
• the shroud or skirt is then between the surface to be treated and the nozzle which is interiorly of the shroud or skirt and set back from the opening thereof.
• the nozzle may be inclined at an angle to the surface to be cleaned.
• guide means such as wheels or rollers mounted on the shroud, t.o control the angle of the shroud and its distance from the surface.
• the guide means may be adjustable to alter the angle and distance as required.
• the shot blasting medium comprises a plurality of sand particles which are coated with a coating comprising, preferably an epoxy resin.
• a coating comprising, preferably an epoxy resin.
• a clear epoxy. resin is preferred.
• coated particles of sand which is suitably silica-free, is used to clean the facades of buildings of dirt. The dirt is removed and the epoxy resin coating is transferred from the particles to the target surface. The surface is thus coated with a clear coat which protects it from atmospheric corrosion the coat being waterprrof.
• the particles are coated with resin solution as in the previous example, in other words the clear epoxy resin is dissolved in a solvent and the solution is added to the sand in a rotatable drum. The drum is rotated until each particle is evenly coated with the solution, and the coated particles are allowed to dry. The shot blasting medium can then be used. It will be understood that a grit other than sand can be used.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10511909

Family Applications (1)

Country Status (8)

Cited By (3)

Citations (6)

• 1981
  • 1981-02-27 JP JP56500708A patent/JPS57500372A/ja active Pending
  • 1981-02-27 WO PCT/GB1981/000030 patent/WO1981002539A1/en active Application Filing
  • 1981-03-02 FR FR8104088A patent/FR2477456A1/fr active Pending
  • 1981-03-04 IT IT20110/81A patent/IT1136907B/it active
  • 1981-03-04 CA CA000372260A patent/CA1174059A/en not_active Expired
  • 1981-03-05 ZA ZA00811470A patent/ZA811470B/xx unknown
  • 1981-03-05 GR GR64316A patent/GR78083B/el unknown
  • 1981-11-03 NO NO813718A patent/NO813718L/no unknown

Patent Citations (6)

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