Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C23/00—Tools; Devices not mentioned before for moulding
  • B22C23/02—Devices for coating moulds or cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
  • B29C33/60—Releasing, lubricating or separating agents
• • 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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process

Definitions

• the present invention relates to a release agent and methods of using a release agent.
• the present invention relates to a release agent comprising boron nitride and a fumed metal oxide, which may find use, for example, in metal processing applications.
• Aluminum has been used as a prominent material by many industries, including the automotive and construction industries. Traditional metal aluminum alloys are not able to meet the desired mechanical properties for all purposes, such as those required by new automotive standards. As a result, to achieve better mechanical properties (e.g., ductility, strength, etc.) new low-iron aluminum alloys have been developed. Manufacturing molded articles using these low-iron aluminum alloys is difficult, however, because these alloys damage metal processing equipment such as the steel die casting equipment that is most commonly used to manufacture such articles. The low-iron aluminum alloys tend to stick (solder) to the steel die casting equipment and requires a higher release force. To minimize the sticking of the low-iron aluminum alloy, a significant amount of lubricant must be applied to the die surface. The use of excessive lubricant may cause fatigue of the die surface, especially when the surface is subjected to repeated heating by molten alloys at high casting temperatures. This fatigue results in fine cracks that produce corresponding raised veins on die castings.
• Metal processing processes for ferrous and non-ferrous materials face similar challenges in their operations.
• the present invention provides a release agent.
• the release agent allows for a significant decrease in the pull force required to remove an article from a die compared to conventional lubricants.
• the present invention provides a release agent comprising (a) boron nitride; and (b) a fumed metal oxide.
• the present invention provides a substrate defining a surface, the substrate comprising a coating of the release agent disposed on at least a portion of the surface.
• the present invention provides a method for forming a shaped metal article comprising: providing an apparatus defining a mold cavity to form a shaped article, wherein a surface of the mold cavity comprises a coating of the release agent; supplying a metal to the mold cavity; forming a shaped article; and removing the article from the cavity.
• the present invention provides a use for the release agent in a metal processing operation.
• the words “example” and “exemplary” means an instance, or illustration.
• the words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment.
• the word “or” is intended to be inclusive rather than exclusive, unless context suggests otherwise.
• the phrase “A employs B or C,” includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C).
• the articles “a” and “an” are generally intended to mean “one or more” unless context suggest otherwise.
• the present invention provides a release agent comprising a mixture of boron nitride powder with a fumed metal oxide.
• the fumed metal oxide is chosen from fumed silica, fumed alumina, fumed titanic, fumed ceria, fumed neodymium, fumed titnia-silicon mixed oxide, or a combination of two of more thereof.
• the release agent may be applied to the metal processing equipment (e.g., die casting equipment) to provide a coating.
• Metal processing is the process of working with metals to create individual parts, assemblies, or large-scale structures and includes forging, extrusion, and casting.
• Boron nitride can be used in metal processing operations for both ferrous and non-ferrous metal alloys.
• the release agent comprises a mixture of boron nitride powder and fumed silica in a water-based solvent. In one embodiment, the release agent comprises a mixture of boron nitride powder and fumed alumina in a water-based solvent.
• the fumed metal oxide particles have a relatively high surface area.
• the particles have a surface area of about 10 m 2 /g to about 500 m 2 /g; 10 m 2 /g to about 400 m 2 /g; 10 m 2 /g to about 300 m 2 /g; about 10 m 2 /g to about 200 m 2 /g; about 10 m 2 /g to about 100 m 2 /g; about 20 m 2 /g to about 400 m 2 /g; about 20 m 2 /g to about 300 m 2 /g; about 20 m 2 /g to about 200 m 2 /g; about 20 m 2 /g to about 100 m 2 /g; about 50 m 2 /g to about 300 m 2 /g; about 50 m 2 /g to about 200 m 2 /g; or about 50 m 2 /g to about 100 m 2 /g.
• the particles have a surface area of about 50 m 2 /g, about 75 m 2 /g, about 100 m 2 /g, about 150 m 2 /g, about 200 m 2 /g, about 300 m 2 /g; about 400 m 2 /g, even about 500 m 2 /g.
• numerical values can be combined to form new or non-disclosed ranges.
• the fumed metal oxide may be selected from alumina, silica, titania, ceria, neodymium oxide, and a combination of two or more thereof.
• the fumed metal oxide has a BET value of 10 m 2 /g to 300 m 2 /g and a particle size of less than 25 microns. Fumed metal oxides are produced using processes known in the art, in one example, the hydrolysis of suitable feed stock vapor (such as silicon tetrachloride for fumed silica) in a flame of hydrogen and oxygen.
• the surface area of the fumed metal oxides may be measured by the nitrogen adsorption method of S. Brunauer, P. H. Emmet, and I. Teller, J. Am. Chemical Society, Volume 60, Page 309 (1938) and is commonly referred to as BET.
• the fumed metal oxide has a BET of 20 m 2 /g to about 100 m 2 /g.
• the fumed metal oxide has a mean particle size of 15 ⁇ m or less.
• the fumed metal oxide has a mean particle size of less than 1.0 ⁇ m.
• the fumed metal oxide has a mean particle size of 0.1-0.5 ⁇ m with a BET value of 10 m 2 /g to 500 m 2 /g.
• the fumed metal oxide is present in an amount of about 20 wt. %, about 10 wt. %, about 5 wt. %, about 1 wt. %, about 0.5 wt. %, or about 0.01 wt. %.
• the composition comprises from about 0.01 wt. % to about 20 wt. %; 0.01 wt. % to about 15 wt. %; about 0.01 wt. % to about 10 wt. %; about 0.1 wt. % to about 20 wt. %; about 0.1 wt. % to about 15 wt. %, or about 0.1 wt. % to about 10 wt.
• the fumed metal oxide is present in amount of about 0.5 wt. % to about 20 wt. %; about 0.5 wt. % to about 15 wt. %, or about 0.5 wt. % to about 10 wt. %.
• the boron nitride employed in the release agent composition is not particularly limited and may be selected as desired. In particular, a variety of forms or morphologies of boron nitride can be used. In one embodiment, the boron nitride powder comprises hexagonal boron nitride, platelet boron nitride, an agglomerate of boron nitride, or a combination of two or more thereof.
• the boron nitride powder may comprise crystalline or partially crystalline boron nitride particles made by processes known in the art. These include, but are not limited to spherical boron nitride particles in the micron size range produced in a process utilizing a plasma gas as disclosed in U.S. Pat. No. 6,652,822; hBN powder comprising spherical boron nitride agglomerates is formed from irregular non-spherical boron nitride particles bound together by a binder and subsequently spray-dried, as disclosed in U.S. Patent Publication No. 2001/0021740; boron nitride powder produced from a pressing process as disclosed in U.S. Pat.
• the boron nitride powder is in the form of spherical agglomerates of hBN platelets.
• the agglomerates have an average agglomerate size distribution (ASD) or diameter from about 10 ⁇ m to about 500 ⁇ m.
• the boron nitride powder is in the form of spherical agglomerates having an ASD in the range of about 30 ⁇ m to about 125 ⁇ m.
• the ASD is about 74 to about 100 microns.
• the boron nitride powder is in the form of platelets having an average length along the b-axis of at least about 0.1 micron, and typically between about 0.1 ⁇ m and 100 ⁇ m, and a thickness of no more than about 5 microns. In another embodiment, the powder is in the form of platelets having an average aspect ratio of from about 5 to about 1000.
• the boron nitride particles comprise hBN platelets having an aspect ratio of from about 5 to about 1000. In another embodiment, the boron nitride particles have an oxygen content from 0.2 to 10 wt. %. In another embodiment, the hBN particles have a graphitization index of less than 25. In one embodiment, the boron nitride may be turbostratic boron nitride without a defined graphitization index.
• the boron nitride particles comprise hexagonal boron nitride powders having an average primary particle (crystallite) size of about 0.1 ⁇ m to about 20.0 ⁇ m, about 0.1 ⁇ m to about 15 ⁇ m; about 0.1 ⁇ m to about 10 ⁇ m, about 0.5 ⁇ m to about 15 ⁇ m, about 0.5 ⁇ m to about 10 ⁇ m; about 1.0 ⁇ m to about 20.0 ⁇ m, about 1.0 ⁇ m to about 15 ⁇ m, about 1.0 ⁇ m to about 10 ⁇ m.
• crystallite average primary particle
• the boron nitride loading in the release agent is about 0.1 wt. % to about 50 wt. %, 5 wt. % to about 45 wt. %, 10 wt. % to about 40 wt. %, or 15 wt. % to about 35 wt. %. of the total weight of the release agent.
• the boron nitride loading is from about 0.1 to about 30 wt. %; 1 to 20 wt. %; even 5 to 15 wt. % of the total weight of the release agent.
• numerical values can be combined to form new and non-disclosed ranges.
• Silica and/or alumina particles having a relatively high surface area in the composition result in a better dispersion stability.
• the boron nitride loading can be significantly reduced with the use of the higher surface area fumed metal oxide particles.
• the fumed metal oxide particles have a surface area of from about 50 to about 400 m 2 /g, and the amount of boron nitride may be as low as about 10 wt. %, about 8 wt. %, about 6 wt. %, about 5 wt. %, even about 1 wt. %.
• the surface of the boron nitride powder may be treated.
• suitable materials for surface treatment of the boron nitride powder include, but are not limited to, silanes, siloxanes, organometallic compounds such as titanates and zirconates (e.g., Ken-react by Kenrich), aluminates, hyperdispersants (e.g., Solsperse by Lubrizol), maleated oligomers such as maleated polybutadiene resin or styrene maleic anhydride copolymer (Cray Valley), fatty acids or waxes and their derivatives such as ester and amides, and ionic or non-ionic surfactants.
• silanes include, but are not limited to, an alkacryloxy silane, a vinyl silane, a chloro silane, a mercapto silane, a blocked mercapto silane, or a combination of two or more thereof.
• siloxane fluids examples include Silsoft® 876 (Siloxane Polyalkyleneoxide Copolymer), Silsoft® 880 (a copolymer of polydimethylsiloxane and polyethyleneglycol), Silsoft® spreader MAX (non-ionic organomodified carbosilane copolymer), Silquest A-187® (gamma-glycidoxypropyltrimethoxysilane), Silquest® A-1871 (gamma-glycidoxy-propyltriethoxysilane), Silquest® Wetlink 78, Silquest® A1160 (gamma-Ureidopropyltrialkoxysilane (50% in methanol), Silquest® A1524 (gamma-Ureidopropyltrimethoxysilane), Silquest® A-Link 25 (gamma-Isocyanatopropyl-triethoxysilane), Silquest® A-Link 35 (gamma-Isocyan
• the release agent can comprise from about 1 to about 5 wt. % of a silane or siloxane fluid; from about 1.5 to about 4 wt. %; even from about 2.7 to about 3.7 wt. % of a silane or siloxane fluid.
• the boron nitride powder has an average particle size of about 0.05 ⁇ m to about 500 ⁇ m; from about 0.5 ⁇ m to about 250 ⁇ m; from about 1 ⁇ m to about 150 ⁇ m; from about 5 ⁇ m to about 100 ⁇ m; even from about 10 ⁇ m to about 30 ⁇ m. In one embodiment, the boron nitride powder has an average particle size of at least 50 ⁇ m. In one embodiment, the boron nitride powder comprises irregularly shaped agglomerates of hBN platelets, having an average particle size of above 10 ⁇ m.
• numerical values can be combined to form new and non-disclosed ranges.
• the release agent is formed by mixing boron nitride powders with the fumed metal oxide (e.g., fumed silica, fumed alumina, or a combination thereof) and dispersing the mixture in water.
• the mixture may be mixed using any suitable mixing method.
• the mixture is mixed using an electronic mixer such as the Speedmixer (FlackTek, Inc.)
• the release agent further comprises a filler.
• a suitable filler includes, but is not limited to, talc, graphite, alumina (Al 2 O 3 ), water-soluble phosphate, colloidal silica, colloidal alumina, water-soluble phosphate salt (e.g., water-soluble magnesium phosphate), a silicate (e.g. potassium silicate, magnesium aluminum silicate) and/or molybdenum disulfide, SiO 2 , ZnO, ZrO 2 , CeO, TiO 2 , mica, or a combination of two or more thereof.
• the release agent further comprises a wetting agent/rheology modifier in an amount of about 0.1 wt. % to about 30.0 wt. %, about 0.5 wt. % to about 20.0 wt. %, or about 1.0 wt. % to about 10.0 wt. %.
• the wetting agent/rheology modifier is present in an amount of less than about 30.0 wt. %.; less than about 20.0 wt. %; less than about 10.0 wt. %, less than about 9.0 wt. %, less than about 8.0 wt. %, less than about 7.0 wt. %, less than about 6.0 wt. %, less than about 5.0 wt. %, or even less than about 2.0 wt. %
• the wetting agent/rheology modifier may be a clay-based sedimentation preventing agent obtained by purifying a natural montmorillonite based clay mineral and reacting the purified clay mineral with an organic compound.
• the wetting agent/rheology modifier may be selected from sodium silicate, magnesium silicate, calcium silicate, or bentonite.
• the wetting agent is a silane-based wetting agent.
• a silane-based wetting agent may be present in an amount of about 0.1 wt. % to about 5 wt. %, about 0.5 wt. % to about 4.5 wt. %, or about 1.0 wt. % to about 4.0 wt. %.
• the silane-based wetting agent may be present in an amount of about 5 wt. %, 4 wt. %, 3 wt. %, 2 wt. %, or even 1 wt. %.
• siloxane fluids examples include Silsoft® 876 (Siloxane Polyalkyleneoxide Copolymer), Silsoft® 880 (a copolymer of polydimethylsiloxane and polyethyleneglycol), Silsoft® spreader MAX (non-ionic organomodified carbosilane copolymer), Silquest A-187® (gamma-glycidoxypropyltrimethoxysilane), Silquest® A-1871 (gamma-glycidoxy-propyltriethoxysilane), Silquest® Wetlink 78, Silquest® A1160 (gamma-Ureidopropyltrialkoxysilane (50% in methanol), Silquest® A1524 (gamma-Ureidopropyltrimethoxysilane), Silquest® A-Link 25 (gamma-Isocyanatopropyl-triethoxysilane), Silquest® A-Link 35 (gamma-Isocyan
• the release agent can comprise from about 1 to about 5 wt. % of a silane or siloxane fluid; from about 1.5 to about 4 wt. %; even from about 2.7 to about 3.7 wt. % of a silane or siloxane fluid.
• the release agent may optionally include a pigment to impart color to the release agent.
• the pigment may be chosen as desired to impart a desired color to the release agent.
• the release agent is chosen from an inorganic pigment chosen from a rutile, spinel, hematite, or phosphate pigment.
• the pigment is substantially free of chromium compounds including, for example, trivalent chromium, hexavalent chromium or combinations thereof.
• release agent to the substrate of interest can be accomplished by any suitable method including, but not limited to, dipping, spraying, brushing, or rolling the release agent onto metal processing equipment including, but not limited to, mold surfaces, shot sleeves, transition plates, thimbles, ladles, launder joints, side wall dams, dummy blocks, billets, ingots, die bearings, shear blades, piercing mandrels, die surfaces, nozzles, degassing tubes and equipment, and thermocouple protection coatings.
• the release agent is applied to die casting equipment. Spraying with standard compressed air sprayers and airless systems is particularly suitable for applying the coating.
• the coating thickness of the release agent can be selected as desired.
• the present release agent allows for the use of relatively thin coatings, while still providing excellent release properties (e.g., low pull force).
• the desired thickness may depend on the particular metal processing application in which the release agent will be used.
• the coating has a thickness of about 2 mil to about 20 mil (about 50 microns to about 500 microns). In one embodiment, the coating has a thickness of about 2 mil to about 8 mil (about 50 to about 200 microns).
• the release agent can be used full strength (undiluted) or diluted with water to a maximum of two parts water to one part coating. If diluting, the use of distilled or purified water is preferable.
• the first coating layer comprises a primer or initial coating.
• This coating layer may be relatively thin (e.g., from about 0.01 mil to about 1 mil) and is applied evenly. After this first coating layer dries completely (typically 6 to 8 hours if air drying or 20 minutes hot air drying at 80° C.), one or more additional coating layers may be applied to provide a coating of a desired thickness. Before applying the release agent, it is recommended that the parts of the device to be coated should be clean and free of rust, oil, and other contaminants.
• the coating may be diluted as needed.
• At least one additional coating layer may be applied if the coating is damaged by repeated use. Additional coating layers may be applied as needed based on the condition of the coating.
• the release agent may be used in many metal processing applications.
• the release agent may be useful for processes involving casting, extrusion, forging and forming, and metallurgy.
• the release agent may be used as a coating or part of a coating for metal processing equipment including, but not limited to molds, shot sleeves, transition plates, thimbles, ladles, launder joints, side wall arms, dummy blocks, billets, die bearings, shear blades, piercing mandrels, die surfaces, work piece coatings, nozzles, degassing tubes and equipment, thermocouple protection coatings, and slip agents.
• a release agent coating comprising 10 wt. % hexagonal BN, 1 wt. % fumed silica, and water was prepared and the pull force measured.
• Steel pins (rods) were coated with either a known die lubricant composed of a water and oil-based formulation containing about 1-40% graphite or the release agent coating described above. The coatings were applied using the dipping and spraying method.
• a crucible was held in a fixture, inside a tensile tester.
• the rod was positioned at the desired level inside the crucible.
• the rod was initially lowered with the upper ram into the crucible and the end positioned 0.1 inch from the bottom of the crucible.
• Molten low-iron A356.1 alloy at 1350° F.+/ ⁇ 5° F. was then poured into the crucible and allowed to cool down to 750° F. as measured by a thermocouple, at which time the tensile tester was turned on and the rod was pulled out from the solidified aluminum while recording the load.
• the tensile strength tester was capable of measuring a pull for of up to 500 lbs.
• the pull force required to pull the rod coated with the known lubricant out from the solidified aluminum was more than 500 lbs. Because the tensile strength tester does not measure a pull force greater than 500 lbs, the exact pull force could not be determined.
• the pull force required to pull the rod coated with the new release agent was about 2 lbs. See Table 1 below.

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• 2016
  • 2016-12-29 JP JP2018534165A patent/JP2019500221A/ja active Pending
  • 2016-12-29 CA CA3010193A patent/CA3010193A1/en not_active Abandoned
  • 2016-12-29 CN CN201680082397.0A patent/CN108699705A/zh active Pending
  • 2016-12-29 WO PCT/US2016/069071 patent/WO2017117324A1/en active Application Filing
  • 2016-12-29 US US16/066,083 patent/US20200261969A1/en not_active Abandoned
  • 2016-12-29 EP EP16834157.6A patent/EP3397792B1/en active Active

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