Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D4/00—Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16
  • C09D4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00
• • 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
  • B24D3/001—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 supporting member
  • B24D3/002—Flexible supporting members, e.g. paper, woven, plastic materials
  • B24D3/004—Flexible supporting members, e.g. paper, woven, plastic materials with special coatings
• • 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
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D177/00—Coating compositions based on polyamides obtained by reactions forming a carboxylic amide link in the main chain; Coating compositions based on derivatives of such polymers

Definitions

• Coated abrasives may employ a make coat of resinous binder material in order to secure the abrasive grains to the backing, and a size coat of resinous binder material can be applied over the make coat and abrasive grains in order to more firmly bond the abrasive grains to the backing.
• the resinous material of the make and size coats may be the same material or may be different materials.
• a common resinous material used for both make and size coatings is generically referred to as phenolic resin.
• Phenolic resins are a class of materials made from the reaction of phenol with various aldehydes.
• Phenolic resins are commonly used in binders for coated abrasive articles because of their high adhesive strength to abrasive particles, durability, and high thermal stability. However, phenolic resins do not adhere well to some types of backing materials. Poor adhesion may cause the phenolic binder to peel away or "shell off' prematurely as the abrasive article is subjected to normal use. This lack of adhesion limits the types of backings that can be used in coated abrasive articles that use phenolic resin binders.
• this binder precursor Upon heating to elevated temperatures, this binder precursor is capable of flowing, increasing the tack of the hot melt adhesive, allowing the hot melt adhesive to penetrate and/or bond intimately with the backing substrate.
• the binder precursor may be liquid at room temperature.
• a "continuous filament yarn” is a yarn comprising indefinitely long fibers such as those found in silk, or those manufactured fibers which are extruded into filaments and then assembled into a yarn with or without a twist.
• the compositions of the invention combine the toughness, the improved adhesion to other phenolics, and the meit-processibilty of thermoplastic polyamides with the rapid curing, high temperature stability, and phenolic resin compatibility of the functionalized oligomeric material.
• the resulting solventless compositions are processed at moderate temperatures (200-280 °F (83-138 °C)) as compared with typical thermoplastic materials processed in excess of 204 °C, and thus allow the use of temperature sensitive backing materials in coated abrasives.
• compositions of the invention may also be used as laminating or transfer coating adhesives in composite backings that provide strength and durability similar to that of cloth at less cost.
• a preferred binder precursor of the invention contains from about 30 to about 70 weight percent of an acrylated oligomer and from about 70 to about 30 weight percent of thermoplastic polyamide, the weight percent being based on the total resin content of the composition.
• a more preferred binder precursor of the invention contains from about 30 to about 50 weight percent of an acrylated oligomer and from about 70 to about 50 weight percent of thermoplastic polyamide, the weight percent being based on the total resin content of the composition.
• a preferred acrylated oligomer is an acrylated epoxide.
• a preferred catalyst for the acrylated oligomer containing material is a free radical producing photoinitiator.
• compositions of the invention contain one or more acrylated oligomers.
• Useful acrylated oligomers are radiation curable and include acrylated epoxy resins and acrylated urethane resins.
• the term acrylate includes both acrylates and methacrylates.
• PHOTOMER 3038 epoxy acrylate tripropylene glycol diacrylate blend
• PHOTOMER 3071 modified bisphenol A acrylate, etc.
• Acrylated urethanes are multifunctional acrylate esters of hydroxyterminated isocyanate extended polyesters or polyethers.
• Examples of commercially available acrylated urethanes include those known by the trade designations PHOTOMER (for example, PHOTOMER 6010) available from Henkel Corp.; EBECRYL 220 (hexafunctional aromatic urethane acrylate of 1000 molecular weight), EBECRYL 284 (aliphatic urethane diacrylate of 1200 molecular weight diluted with 1 ,6-hexanediol diacrylate), EBECRYL 4827 (aromatic urethane diacrylate of 1600 molecular weight), EBECRYL 4830 (aliphatic urethane diacrylate of 1200 molecular weight diluted with tetra ethylene glycol diacrylate), EBECRYL 6602 (trifunctional aromatic urethane acrylate of 1300 molecular weight diluted with trimethylolpropane eth
• Preferred acrylated oligomers are di-and tri-functional acrylated oligomers. More preferred acrylated oligomers include Bisphenol A based di-functional acrylated epoxy resins. Preferred commercially available di-functional acrylated Bisphenol A based epoxy resins are EBECRYL 3700and 3720, available from UCB Chemicals.
• compositions of the invention contain at least one catalyst for curing the acrylated oligomer.
• the acrylated oligomer can be cured by radiation energy. Since the acrylated oligomer is cured by radiation, the amount of radiation depends upon the degree of cure desired of the crosslinkable components.
• radiation energy sources include ionizing radiation, ultraviolet radiation, and visible light radiation.
• Ionizing radiation preferably has an energy level of 0.1 to 10 megarad, more preferably 1 to 10 megarad.
• Ultraviolet radiation is non-particulate radiation having a wavelength of from about 200 to 700 nanometers, more preferably from 250 to 400 nanometers. Visible light radiation is non-particulate radiation having a wavelength of from about 400 to 760 nanometers.
• photoinitiators examples include organic peroxides, azo compounds, quinones, benzophenones, nitro compounds, acyl halides, hydrazones, mercapto compounds, pyrylium compounds, triacrylimidizoles, bisimidizoles, chloroalkyltriazines, benzoin ethers, benzil ketals, thioxanthones, and acetophenone derivatives.
• a photoinitiator is required to initiate free radical polymerization. Examples of useful visible light photoinitiators can be found in U.S. Patent No. 4,735,632.
• IRGACURE and have product numbers 369, 651, and 961, all available from Ciba Geigy Chemicals, Hawthorne, NY.
• any known and compatible additive useful in coatings used in the abrasives art may be used as long as the amount of the additive used does not adversely affect the performance characteristics of the end-use product or article.
• Common additives include optically transparent fillers such as feldspar and silica, and materials useful for dissipating static charges such as carbon black and graphite.
• Paper backings can also be barrier coated, backsized, untreated, or fiber-reinforced.
• the paper backings also can be provided as laminates with a different type of backing material.
• Nonwoven backings include spunbonded webs and laminates to different backing materials mentioned herein.
• Laminates may include those constructions having a network of filaments adhesively bonded or melt bonded to a nonwoven web.
• the nonwovens may be formed of cellulosic fibers, synthetic fibers, or blends thereof. Examples of commercially available nonwoven backing materials include TYPAR spunbonded polypropylene and REEMAY spunbonded polyester, available from Typar/Reemay, Old Hickory, TN; and STABILON scrims, available from Milliken.
• the binder precursor may be prepared by mixing the various ingredients in a suitable vessel at an elevated temperature sufficient to liquefy the materials so that they may be efficiently mixed with stirring but without thermally degrading them until the components are thoroughly melt blended.
• This temperature depends in part upon the particular chemistry. For example, this temperature may range from about 30 to 150 °C, typically 50 to 140 °C, and preferably ranges from 60 to 125 °C.
• the components may be added simultaneously or sequentially, although it is preferred to first blend the acrylated oligomer resin and the thermoplastic polyamide component. Then the catalysts are added, followed by any optional additives including fillers or grinding aids (for peripheral coating use).
• the binder precursor should be compatible in the uncured, melt phase.
• the viscosity ratio of the acrylated oligomer and the thermoplastic polyamide is approximately 0.1 at the processing temperature.
• the binder precursor may be immediately coated after melt blending or may be packaged in pails, drums, or other suitable containers, as a solid or a powder, preferably in the absence of light, until ready for use.
• the binder precursors so packaged may be delivered to a hot-melt applicator system with the use of pail unloaders, block melters equipped with rotating screws, and the like.
• the hot melt binder precursors of the invention may be delivered to conventional bulk hot melt applicator and dispenser systems in the form of sticks, pellets, slugs, blocks, pillows, or billets. It is also feasible to incorporate organic solvent into the binder precursor; although this may not always be preferred. It is also possible to provide the hot melt binder precursors of the invention as uncured, unsupported rolls of adhesive film. In this instance, the binder precursor is extruded, cast, or coated to form the film. Such films are useful in transfer coating the binder precursor to an abrasive article backing. It is desirable to roll up the film with a release liner (for example, silicone-coated Kraft paper), with subsequent packaging in a bag or other container that is not transparent to actinic radiation.
• a release liner for example, silicone-coated Kraft paper
• the hot melt binder precursors of the invention may be applied to the abrasive article backing by extrusion, gravure printing, coating, (for example, by using a coating die, a heated knife blade coater, a roll coater, a curtain coater, or a reverse roll coater), or transfer coating.
• coating for example, by using a coating die, a heated knife blade coater, a roll coater, a curtain coater, or a reverse roll coater
• transfer coating for example, by using a coating die, a heated knife blade coater, a roll coater, a curtain coater, or a reverse roll coater
• the binder precursor be applied at a temperature of about 50 to 140 °C, more preferably from about
• a liquid binder precursor can be applied to the backing by any conventional technique such as roll coating, spray coating, die coating, knife coating, and the like. After coating the resulting binder precursor, it may be exposed to an energy source to activate the catalyst before the abrasive grains are embedded into the binder precursor. Alternatively, the abrasive grains may be coated immediately after the binder precursor is coated before partial cure is effected.
• the coating weight of the hot melt binder precursor of the invention to a backing can vary depending on the grade of the abrasive particles to be used.
• the application rate of the binder precursor composition of this invention is between about 4 to 500 g/m ⁇ , preferably between about 20 to about 300 g/m ⁇ .
• Curing of the hot melt binder precursor begins upon exposure of the binder precursor to an appropriate energy source and continues for a period of time thereafter.
• the energy source is selected for the desired processing conditions and to appropriately activate the chosen photoactive catalyst system.
• the energy may be actinic (for example, radiation having a wavelength in the ultraviolet or visible region of the spectrum), accelerated particles (for example, electron beam radiation), or thermal (for example, heat or infrared radiation).
• the energy is actinic radiation (that is, radiation having a wavelength in the ultraviolet or visible spectral regions).
• Suitable sources of actinic radiation include mercury, xenon, carbon arc, tungsten filament lamps, sunlight, and so forth.
• Ultraviolet radiation especially from a medium pressure mercury arc lamp, is most preferred. Exposure times may be from less than about 1 second to 10 minutes or more (to preferably provide a total energy exposure from about 0.1 to about 10 Joule/square centimeter (J/cm ⁇ )) depending upon both the amount and the type of reactants involved, the energy source, web speed, the distance from the energy source, and the thickness of the binder precursor to be cured.
• the binder precursors may also be cured by exposure to electron beam radiation.
• the dosage necessary is generally from less than 1 megarad to 100 megarads or more.
• the rate of curing may tend to increase with increasing amounts of photocatalyst and/or photoinitiator at a given energy exposure. Curing of the mixture can also be effected by use of electron beam energy with no photoinitiator. The rate of curing also tends to increase with increased energy intensity.
• AF7 an antifoam, available from The Dow Chemical Co., Midland, MI, under the trade designation DOW 7
• DS1227 a high molecular weight polyester, available from Creanova Inc., under the trade designation DYNAPOL SI 227
• EP1 a bisphenol A epoxy resin, available from Shell Chemical, Houston TX, under the trade designation EPON 828 and having an epoxy equivalent weight of 185-192 g/eq
• EP2 a bisphenol A epoxy resin, available from Shell Chemical, under the trade designation of EPON 100 IF and having an epoxy equivalent weight of
• HDDA hexanediol diacrylate available from Sartomer, under the trade designation
• UV-893 acrylated urethane oligomer available from Morton, under the trade designation UVITHANE 893
• V-732 polyamide thermoplastic pellet having a melting point of 105 °C by differential scanning calorimetry (DSC), available from Creanova, Inc., under the trade designation VESTAMELT 732
• PE polyester drills cloth (240 g/n -), available from Johnston
• thermoplastic polyamide Seventy grams of thermoplastic polyamide and 30 grams of acrylated oligomer were weighed into a glass container. The mixture was heated at 140 °C for about one hour, with occasional mixing by hand with a tongue depressor. After one hour the blend was easily mixed to form a viscous, homogeneous solution. One gram of photoinitiator was dissolved into the hot solution, and the material was immediately knife coated directly onto a backing; the knife and bed were both previously heated to 138 °C, and the knife gap was set at approximately 75 micrometers. After the coating had cooled to room temperature and solidified, the acrylated oligomer was crosslinked by exposure to ultraviolet light (2 passes under a 236 W/cm Fusion Systems "D" bulb at 14 m min).
• a presized backing was prepared using the above method.
• the abrasive slurry compositions used are described below in Table 2.
• a production tool was made by casting polypropylene material on a metal master tool having a casting surface comprised of a collection of adjacent truncated pyramids.
• the production tool contained cavities that were in the shape of truncated pyramids.
• the pyramidal pattern was such that their adjacent bases were spaced apart from one another no more than about 510 micrometers.
• the height of each truncated pyramid was about 80 micrometers, the base was about 178 micrometers per side and the top was about 51 micrometers per side. There were about 50 lines per centimeter delineating the array of composites.
• the backing associated with the presize coating was secured to a metal carrier plate using a masking type pressure sensitive adhesive tape.
• the abrasive slurry was coated into the cavities of the tool using a rubber squeegee such that the abrasive slurry completely filled the cavities.
• the abrasive slurry contained in the cavities of the production tool was brought into contact with the backing that had previously been secured to the metal carrier plate.
• the production tool and backing were passed through rubber squeeze rolls to ensure that the abrasive slurry wetted the surface of the presize coating on the backing and to remove any undesired air bubbles.
• the article was cured by passing the tool together with the backing and binder precursor, at a speed of about 20 feet per minute (6.1 m/min), under two ultraviolet light medium pressure mercury bulbs, available from American Ultraviolet Company, Murray Hill, NJ. Each bulb operated at 400 watts/inch (158 watts/cm) and the radiation passed through the production tool. Upon exposure to the ultraviolet light, the curable abrasive composite layer was essentially converted into a cured abrasive composite layer. The abrasive composite layer, now adhered to the presized backing, was then removed from the cavities of the production tool.
• Coated abrasive articles were also prepared according to the following procedure:
• a presized backing was prepared as described above.
• a coatable mixture for producing a make coating for the backing was prepared by mixing 64 parts of 75 percent solids phenolic resin (RP1) (48 parts phenolic resin), 52 parts non-agglomerated calcium carbonate filler (dry weight basis), and 4.5 parts water to form a make coating which was
• coated abrasive articles were single flexed, that is, passed over a one inch diameter (2.54 centimeters) roller at an angle of 90 ° to allow a controlled cracking of the make and size coatings.
• the coated abrasive articles were then converted into coated abrasive belts using commonly known methods.
• Test Methods 90 Peel Test The coated abrasive sheet to be tested was converted into a sample about 8 centimeters wide by 25 centimeters long. One-half the length of a wooden board (17.78 centimeters by 7.62 centimeters by 0.64 centimeters thick) was coated with an adhesive. The entire width of, but only the first 15 centimeters of the length of, the coated abrasive sample was coated with an adhesive on the side bearing the abrasive material. The adhesive was 3M JET MELT Adhesive #3779 applied with a POLYGUNTM II glue applicator, both available from Minnesota Mining and Manufacturing Co, St. Paul, MN.
• the side of the sample bearing the abrasive material was attached to the side of the board containing the adhesive coating in such a manner that the 10 centimeters of the coated abrasive sample not bearing the adhesive overhung from the board. Pressure was applied such that the board and the sample were intimately bonded and sufficient time was allowed for the adhesive to cure.
• a filled phenolic adhesive such as that described in "General Procedure 2 for Making Coated Abrasive Articles” was utilized and cured for 6 hours at 100 °C.
• the sample to be tested was scored along a straight line such that the width of the coated abrasive test specimen was reduced to 5.1 centimeters.
• the resulting coated abrasive sample/board composite was mounted horizontally in the lower jaw of a tensile testing machine having the trade designation SINTECH, and approximately 1 centimeter of the overhanging portion of the coated abrasive sample was mounted into the upper jaw of the machine such that the distance between jaws was 12.7 centimeters.
• the machine separated the jaws at a rate of 0.5 cm/sec, with the coated abrasive sample being pulled at an angle of 90 ° away from the wooden board so that a portion of the sample separated from the board.
• separation occurs between the cloth treatments and the cloth.
• the force required to separate the treatment was expressed in lbF/in-width. It is preferred that the force value be at least 10.2 lbF/in (17.8 N/cm), more preferably at least 11.2 lbF/in (19.6 N/cm), and even more preferably at least 16.8 lbF/in (29.4 N/cm), because inadequate adhesion and weakness at the make coat-backing interface will result in inferior performance particularly under use conditions.
• TABLE 1 shows the formulations of the presize compositions used in making the tested articles.
• TABLE 2 shows the formulations of the abrasive-binder slurries used to make the tested articles.
• TABLE 3 shows the presize formulation, slurry formulations, and cloth type used to make the tested articles.
• TABLE 4 shows the results of the stripback adhesion test performed on the articles described in TABLE 3.
• Examples 1 - 4 and the comparative examples were prepared according to General procedure 1 and Examples 5 - 8 were prepared according to General Procedure 2.
• Examples 1 - 3 and 5 - 8 showed adhesion failure between the presize and the cloth backing material, which is preferred.

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Citations (5)

• 1999
  • 1999-11-09 EP EP99960250A patent/EP1144515A1/de not_active Withdrawn
  • 1999-11-09 JP JP2000589631A patent/JP2002533520A/ja active Pending
  • 1999-11-09 WO PCT/US1999/026426 patent/WO2000037569A1/en not_active Application Discontinuation

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