Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
  • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
  • B24D3/28—Resins or natural or synthetic macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1409—Abrasive particles per se

Definitions

• the following is directed to an abrasive tool, and particularly directed to a robust binder bonded grinding wheel.
• Abrasive wheels are typically used for cutting, abrading, and shaping of various materials, such as stone, metal, glass, plastics, among other materials.
• the abrasive wheels can have various phases of materials including abrasive grains, a bonding agent, and some porosity.
• the abrasive wheel can have various designs and configurations. For example, for applications directed to the finishing and cutting of metals, some abrasive wheels are fashioned such that they have a particularly thin profile for efficient cutting.
• the abrasive articles are subject to fatigue and failure.
• the wheels may have a limited time of use of less than a day depending upon the frequency of use. Accordingly, the industry continues to demand abrasive wheels capable of improved performance.
• FIG. 1 includes an illustration of an abrasive tool in accordance with an embodiment.
• FIG. 2 includes an illustration of diblock copolymer in accordance with an embodiment.
• FIG. 3 includes an illustration of triblock copolymer in accordance with an embodiment.
• FIG. 4 includes a micrograph illustrating the microstructure formed by a block copolymer and a resin in accordance with an embodiment.
• FIG. 5 includes a bar graph illustrating the burst speed of a standard abrasive article and a block copolymer abrasive article in accordance with an embodiment.
• the matrix material can include a binder and an amphiphilic block copolymer including a binder miscible block and a binder immiscible block.
• embodiments herein are directed to abrasive wheels that are particularly suited for cutting and/or shaping metal.
• FIG. 1 includes an illustration of an abrasive tool in accordance with an embodiment.
• the abrasive tool 100 includes a body 101 having a generally circular shape as viewed in two dimensions. It will be appreciated, that in three- dimensions the tool has a certain thickness such that the body 101 has a disk-like or a cylindrical shape.
• the body can have an average thickness of at least about 0.1 cm and not greater than about 3 cm. For example, the average thickness can be within a range between about 0.5 cm and about 2 cm.
• the body can have an outer diameter 103 extending through the center of the tool.
• the outer diameter 103 can be within a range of 15 cm to about 100 cm. In a particular embodiment, the outer diameter can be at least about 45 cm.
• the abrasive tool 100 can include a central opening 105 defined by an inner circular surface 102 about the center of the body 101.
• the central opening 105 can extend through the entire thickness of the body 101 such that the abrasive tool 100 can be mounted on a spindle or other machine for rotation of the abrasive tool 100 during operation.
• the body can include a tapered region extending circumferentially around a portion of a periphery of the body.
• the tapered region can extend through the entire circumference of the body. Additionally, the tapered region extends radially from a flat region of the body. In a particular embodiment, the tapered region of the body comprises an average thickness that is greater than an average thickness of the flat region of the body.
• the body of the abrasive tool can include an abrasive grain contained within a matrix material.
• the abrasive grain can include superabrasive material, such as diamond, cubic boron nitride, and a combination thereof.
• the abrasive grains comprise a material selected from the group of materials consisting of oxides, carbides, borides, nitrides, and a combination thereof.
• the abrasive grains can consist essentially of oxides.
• the oxide material can include alumina, zirconia, silica, or any combination thereof.
• the abrasive grains comprise a Vickers hardness of at least about 5 GPa. In an embodiment, the abrasive grain can be present in an amount from about 50 wt to about 80 wt of the abrasive tool.
• the matrix material can include a binder, such as a phenolic resin or an epoxy resin, and an amphiphilic block copolymer.
• a binder such as a phenolic resin or an epoxy resin
• an amphiphilic block copolymer such as a phenolic resin or an epoxy resin
• the matrix material can include from about 70 wt to about 95 wt binder and from about 5 wt to about 30 wt amphiphilic block copolymer.
• the amphiphilic block copolymer can include at least two blocks and can include blocks comprising poly(methyl methacrylate), polystyrene, polybutadiene, or any combination thereof.
• the amphiphilic block copolymer can be a diblock copolymer or a triblock copolymer.
• FIG. 2 includes an illustration of an exemplary diblock copolymer 200.
• the diblock copolymer 200 can include blocks 202 and 204. Additionally, the diblock copolymer can include repeating units consisting of blocks 202 and 204, such that block 204 is followed by block 202 and block 202 is followed by block 204.
• the block 202 can comprise a different polymer from the block 204, and as such, the properties of block 202 can be different from the properties of block 204.
• FIG. 3 includes an illustration of an exemplary triblock copolymer 300.
• the triblock copolymer 300 can include blocks 302, 304, and 306. Additionally, the diblock copolymer can include repeating units consisting of blocks 302, 304, and 306, such that block 306 is followed by another block 302.
• Block 304 can comprise a different polymer from block 302 and from block 306.
• block 302 can comprise a different polymer from block 306, such that each of block 302, 304, and 306 comprises a different polymer form the other blocks.
• block 302 and 306 can comprise a substantially similar polymer.
• amphiphilic block copolymer can include a binder miscible block and a binder immiscible block.
• a binder miscible block can be a polymer block that is soluble in the resin such that the miscible block and the resin form a single phase of the matrix.
• a binder immiscible block can substantially insoluble in the resin and can form a separate phase within the matrix.
• a polystyrene block is miscible in phenolic resin but immiscible in epoxy.
• a binder miscible block can be a polymer block that is soluble in the resin such that the miscible block and the resin form a single phase of the matrix.
• a binder immiscible block can substantially insoluble in the resin and can form a separate phase within the matrix.
• a polystyrene block is miscible in phenolic resin but immiscible in epoxy.
• a binder immiscible block can be any suitable for polymer block
• poly(methyl methacrylate) block is immiscible in phenolic resin but miscible in epoxy.
• a copolymer consisting of a polystyrene block and a poly(methyl methacrylate) block can be an amphiphilic block copolymer for both phenolic resins and epoxy resins.
• the alternating properties of the amphiphilic block copolymer can result in the self-assembly of a particular nano-structure when combined with the resin.
• An example of the nano-structure is depicted in the micrograph of FIG. 4.
• the micrograph of FIG. 4 is a micrograph of a portion of a matrix material that can be used to form an abrasive tool, e.g., a grinding wheel.
• the matrix material can include a binder 402 and a block copolymer within the binder.
• the block copolymer can include at least a first portion and second portion, i.e., the block copolymer can include a diblock copolymer, a triblock copolymer, a tetrablock copolymer, or some other multi-block copolymer.
• the matrix material can include a plurality of toughening domains 404 dispersed within the matrix material. Each of the toughening domains can include the first portion of the block copolymer and can exist as a first phase within the matrix material. Further, an abrasive grain can be dispersed within the matrix material.
• the second portion of the block copolymer and the binder form a single phase different from the phase of the toughening domains.
• the second phase formed from the second portion of the block copolymer and the binder can at least partially surround the first phase formed included in the toughening domains.
• the first portion of the block copolymer includes a binder immiscible portion and the second portion of the block copolymer comprises a binder miscible portion.
• the immiscible/miscible quality of the block copolymer can lead to the formation of the first phase and the second phase within the matrix material. Further, the immiscible/miscible quality of the block copolymer can lead to different morphology of the toughening domain structures, e.g., spherical domain structures, vesicular domain structures, cylindrical domain structures, etc.
• each toughening domain can be generally ellipsoidal in cross-section. Further, each toughing domain can be generally circular in cross- section. In one aspect, the toughening domains include an average diameter of at least about 0.1 ⁇ . In another aspect, the toughening domains can include an average diameter of at least about 0.2 ⁇ , at least about 0.3 ⁇ , at least about 0.4 ⁇ , at least about 0.5 ⁇ , at least about 1.0 ⁇ , at least about 2.5 ⁇ , or at least about 5.0 ⁇ . Further, the toughening domains can include an average diameter that is not greater than about 25.0 ⁇ , not greater than about 20.0 ⁇ , not greater than about 15.0 ⁇ , or not greater than about 10.0 ⁇ . The average diameter can be within a range between and including any of the minimum and maximum average diameters described above.
• the toughening domains can include an average diameter between and including 0.1 ⁇ and 25.0 ⁇ .
• the toughening domains can include an average diameter between and including 0.1 ⁇ and 20.0 ⁇ , between and including 0.1 ⁇ and 15.0 ⁇ , between and including 0.1 ⁇ and 10.0 ⁇ , between and including 0.1 ⁇ and 5.0 ⁇ , between and including 0.1 ⁇ and 2.5 ⁇ , or between and including 0.1 ⁇ and 0.5 ⁇ .
• the toughening domains can include a toughening domain hardness that is less than a binder hardness.
• the toughening domain hardness can be less than about 90% of the binder hardness as given by the equation [HTD/HB]X100%, wherein HTD is the toughening domain hardness and 3 ⁇ 4 is the binder hardness.
• the toughening domain hardness can be less than about 85% of the binder hardness, less than about 80% of the binder hardness, less than about 75% of the binder hardness, or less than about 70%.
• the toughening domain hardness can be greater than about 60% of the binder hardness.
• the toughening domain hardness can be within a range between and including any of the minimum and maximum percentage values described above.
• the toughening domains can be substantially uniformly dispersed throughout an entire volume of the matrix material. In other words, the majority of the toughening domains can be spaced apart from each other.
• At least about 70% of the toughening domains can be spaced apart from each other.
• at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% of the toughening domains can be spaced apart from each other.
• essentially all of the toughening domains can be spaced apart from each other.
• the matrix material can include a toughening domain concentration of at least about 1 toughening domains per 1 ⁇ 2 as viewed in cross- section at a magnification of about 25000x.
• the toughening domain concentration can be at least about 2 toughening domains per 1 ⁇ 2 , at least about 3 toughening domains per 1 ⁇ 2 , at least about 4 toughening domains per 1 ⁇ 2 , or at least about 5 toughening domains per 1 ⁇ 2 .
• the toughening domain concentration may not be greater than about 10 toughening domains per 1 ⁇ 2 .
• the toughening domain concentration can be within a range between and including any of the minimum and maximum concentration values described above.
• the matrix material can include a toughening domain concentration between and include 1 toughening domains per 1 ⁇ 2 and 10 toughening domains per 1 ⁇ 2 .
• the toughening domain concentration can be between and include 1 toughening domains per 1 ⁇ 2 and 5 toughening domains per 1 ⁇ 2 .
• the matrix material can include at least about 0.5 wt of block copolymer for a total weight of the matrix material. Moreover, the matrix material can include at least about 1 % of the block copolymer, about 2 wt of block copolymer, at least about 3 wt of block copolymer, at least about 4 wt of block copolymer, or at least about 5 wt of block copolymer for the total weight of the matrix material. Further, the matrix material can include not more than about 10 wt of block copolymer for the total weight of the matrix material. The amount of block copolymer can be within a range between and including any of the minimum and maximum wt amounts described above.
• the matrix material can include between and including about 0.5 wt block copolymer and about 10 wt block copolymer.
• the matrix material can include between and including about 0.5 wt block copolymer and about 8 wt block copolymer or between and including about 0.5 wt block copolymer and about 5 wt block copolymer.
• the block copolymer can include a polydispersity index less than about 1.4. Further, the polydispersity index can be less than about 1.3 or 1.2. However, the polydispersity index may be greater than about 1.1. In another aspect, the polydispersity index can be between and including about 1.1 and about 1.4. Also, polydispersity index can be between and including about 1.1 and about 1.3. As the polydispersity index approaches 1, a length of each chain within the block copolymer will be substantially the same. In another aspect, an abrasive tool constructed using the matrix material illustrated in FIG. 4 can include a burst speed of at least about 6800 RPM.
• such an abrasive tool can include a burst speed of at least about 6850 RPM, at least about 6900 RPM, at least about 6950 RPM, at least about 7000 RPM, or at least about 7050 RPM.
• the burst speed may not be greater than about 7100 RPM.
• the block copolymer can include a molar mass of at least about 3000 g/mol. Specifically, the molar mass can be at least about 3100 g/mol, at least about 3200 g/mol, at least about 3300 g/mol, at least about 3400 g/mol, or at least about 3500 g/mol.
• the molar mass can be at least about lOOOOg/mol, at least about 15000g/mol, at least about 20000g/mol, at least about 25000g/mol, at least about 30000g/mol, at least about 35000g/mol, at least about 40000g/mol, at least about 45000g/mol, or at least about 50000g/mol.
• the toughening domains can act as dampeners during use a grinding wheel in which the toughening domains are incorporated.
• the toughening domains can absorb energy during use of a grinding wheel in which the toughening domains are incorporated.
• the dampening or energy absorption can be attributed to the differences in hardness between the toughening domains and the binder.
• the binder powder can include a solid phenolic resin or a solid epoxy resin.
• the amphiphilic block copolymer powder can include a solid amphiphilic block copolymer.
• the solid amphiphilic block copolymer can include a binder miscible block and a binder immiscible block.
• the blended powder can include from about 15 wt to about 50 wt binder, from about 1 wt to about 15 wt amphiphilic block copolymer, and from about 50 wt to about 80 wt abrasive grain.
• the blended powder can be shaped into the form of a bonded abrasive.
• a mold cavity can be filled with the blended powder, and the blended powder can be compressed within the mold.
• the blended powder can be compressed by cold pressing, or heat can be added to the powder during pressing, such as by hot pressing.
• the matrix material shaped powder can be cured to form an abrasive tool.
• the matrix material can be cured by heating the blended powder to a curing temperature, such as at least about 200°C.
• the matrix material can be substantially cured while remaining within the mold cavity.
• the matrix material can be partially cured to a point sufficient to maintain the shape of the abrasive tool when removed from the cavity.
• the abrasive tool can be subjected to additional curing to substantially cure the matrix material after being removed from the mold cavity.
• the abrasive tools described herein can have certain features that make the abrasive tool suitable for improved grinding and/or cutting applications.
• the fracture toughness of the bonded abrasive tool is improved.
• the fracture toughness can be determined by measuring the force required to cause a crack to form in the abrasive tool, designated as the GiC, or by measuring the specific work off force (SpWOF) which corresponds to the force required to break a piece off the bonded abrasive tool.
• the abrasive articles of embodiments herein demonstrate an improved percent increase G ⁇ C and percent increase SpWOF as compared to conventional abrasive articles.
• the conventional abrasive articles included abrasives of the same design having the matrix material comprising resin without the addition of the amphiphilic block copolymer.
• the abrasive tool can have a percent increase GiC of at least about 20% over a similar abrasive tool without the amphiphilic block copolymer.
• the percent increase is based on the equation ((GN-GC)/GC X 100%) wherein G represents the GiC of an abrasive tool including the amphiphilic block copolymer and Gc represents the GiC of the abrasive tool without the amphiphilic block copolymer.
• the percent increase GiC can be at least about 30%, such as at least about 40%, such as at least about 50%, even at least about 60%.
• the percent increase GiC can be not greater than about 500%.
• the abrasive tool can have a percent increase SpWOF of at least about 10% over a similar abrasive tool without the amphiphilic block copolymer. Further, the percent increase SpWOF can be at least about 15%, such as at least about 20%. The percent increase is based on the equation ((SN-SC)/SC X 100%) wherein S represents the SpWOF of an abrasive tool having the amphiphilic block copolymer and Sc represents the SpWOF of the abrasive tool without the amphiphilic block copolymer. In other embodiments, the percent increase SpWOF can be not greater than about 500%.
• Liquid amphiphilic block copolymers such as described in US Publication 2009/0082486 Al, have been used to toughen epoxy resins used in applications such as laminating. These applications have relied upon a amphiphilic block copolymer comprising poly (ethylene oxide) (PEO) and poly(butylene oxide) (PBO).
• PEO poly (ethylene oxide)
• PBO poly(butylene oxide)
• the use of a liquid resin system can cause problems with the production of bonded abrasives articles, such as the partial settling of the abrasive grains within the liquid. This may lead to a non-uniform distribution of abrasive grains and uneven grinding performance.
• the use of a solid amphiphilic block copolymer powder provides a particular advantage for the formation of bonded abrasive articles.
• the amount of block copolymer that can be used to increase the strength, or toughness, of a binder used in a grinding wheel application can be such a small amount when compared to the binder material that it would be extremely difficult to get substantially uniform dispersal when mixing a liquid form of such a copolymer with a binder powder.
• mixing a powdered form of such a block copolymer can allow for the uniform dispersal of the block copolymer within the binder powder prior to formation of an abrasive article from the block copolymer/binder powder mixture.
• GIC critical energy release rate
• SpWOF specific work-off force
• Comparative Sample 1 is a phenolic resin based formulation prepared by pressing a phenolic resin powder into a mold and heating it to a temperature of 200°C for 1 hour.
• Sample 1 is prepared as Comparative Sample 1 with the addition of an amphiphilic block copolymer powder.
• the phenolic resin and the amphiphilic block copolymer are blended at a ratio of 90 wt resin to 10 wt copolymer to form a substantially homogeneous powder blend.
• the powder blend is pressed into a mold and heated to a temperature of 200°C for 1 hour. Table 1 shows the results of the GIC and SpWOF tests.
• Comparative Sample 2 is a phenolic resin based formulation prepared by pressing a phenolic resin powder into a mold and heating it to a temperature of 200°C for 1 hour.
• Sample 2 is prepared as Comparative Sample 2 with the addition of an amphiphilic block copolymer powder.
• the phenolic resin and the amphiphilic block copolymer are blended at a ratio of 90 wt% resin to 10 wt% copolymer to form a substantially homogeneous powder blend.
• the powder blend is pressed into a mold and heated to a temperature of 200°C for 1 hour. Table 2 shows the results of the GiC and SpWOF tests.
• Comparative Sample 3 is a phenolic resin based formulation prepared by pressing a phenolic resin powder into a mold and heating it to a temperature of 200°C for 1 hour.
• Sample 3 is prepared as Comparative Sample 2 with the addition of an amphiphilic block copolymer powder.
• the phenolic resin and the amphiphilic block copolymer are blended at a ratio of 90 wt% resin to 10 wt% copolymer to form a substantially homogeneous powder blend.
• the powder blend is pressed into a mold and heated to a temperature of 200°C for 1 hour.
• Table 3 shows the results of the G]C and SpWOF tests. Table 3
• a standard abrasive article is prepared using the formulation detailed in Table 4, below.
• Table 5 lists the ingredients for the standard bond referred to in Table 4.
• a block copolymer (BCP) abrasive article is also prepared using the same formulation as detailed in Table 4.
• the BCP abrasive article includes the addition of a block copolymer, as described herein, to the standard bond material.
• the block copolymer includes a binder immiscible block and a binder miscible block.
• the block copolymer includes a PMMA block copolymer.
• the block copolymer includes polystyrene -b-polybutadiene- b-syndio tactic poly methyl methacrylate.
• the block copolymer is blended with the standard bond at a ratio of 1:99 (block copolymer to standard bond). Moreover, the block copolymer is in a solid, powder form to facilitate thorough mixing and substantially uniform dispersion, as described herein. Dispersion is determined by taking various micrographs of the completed BCP abrasive article and determining the associated dispersion of the toughening domains formed by the immiscible portion of the block copolymer. Table
• each abrasive article is placed in a burst testing apparatus. Each abrasive article is freely spun, or rotated, until each wheel fails catastrophically, i.e., until it bursts. The speed at which the abrasive article fails is recorded as the burst speed.
• FIG. 5 shows the results of the burst testing as a simple bar graph.
• the standard abrasive article provides a burst speed of approximately 6800 RPM.
• the BCP abrasive article constructed using the block copolymer as described herein provides a burst speed of approximately 7100 RPM.
• the BCP abrasive article constructed using the block copolymer provides a burst speed that is approximately 4.4% higher than the burst speed of the standard abrasive articles as given by the formula: [BS B C P -BSS T ]/BSS T X 100%, wherein BS B C P is the burst speed of the BCP abrasive article and BS ST is the burst speed of the standard abrasive article.

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• Engineering & Computer Science (AREA)
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• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Polishing Bodies And Polishing Tools (AREA)

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• 2011
  • 2011-12-28 EP EP11853314.0A patent/EP2658682A2/de not_active Withdrawn
  • 2011-12-28 US US13/339,162 patent/US20120174493A1/en not_active Abandoned
  • 2011-12-28 WO PCT/US2011/067628 patent/WO2012092388A2/en not_active Ceased
  • 2011-12-28 TW TW100149307A patent/TWI449602B/zh not_active IP Right Cessation
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  • 2011-12-28 AU AU2011352122A patent/AU2011352122A1/en not_active Abandoned
  • 2011-12-28 CN CN2011800616200A patent/CN103313824A/zh active Pending
  • 2011-12-28 RU RU2013135448/02A patent/RU2013135448A/ru not_active Application Discontinuation
• 2013
  • 2013-07-18 CO CO13170804A patent/CO6741204A2/es unknown

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