Patent Application
20230001541
It is very common for dry sanding operations to generate a significant amount of airborne dust. To minimize this airborne dust, it is common to use abrasive discs on a tool while vacuum is drawn through the abrasive disc, from the abrasive side through the backside of the disc, and into a dust-collection system. For this purpose, many abrasives are available with holes converted into them, to facilitate this dust extraction. As an alternative to converting dust-extraction holes into abrasive discs, commercial products exist in which the abrasive is coated onto fibers of a net-type knit backing in which loops are knit into the backside of the abrasive article. The loops serve as the loop-portion of a hook-and-loop attachment system for attachment to a tool. Net type products are known to provide superior dust extraction and/or anti-loading properties, when used with substrates known to severely load traditional abrasives. However, cut and/or life performance are still lacking. Thus, there is a need for a net type product that provides enhanced cut and/or life performance while demonstrating superior dust extraction.
The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
It should be understood that numerous other modifications and examples can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. Figures may not be drawn to scale.
In general, coated abrasive articles have abrasive particles secured to a backing. Coated abrasive articles can include a backing having two major opposed surfaces and an abrasive layer secured to one of the major surfaces. The abrasive layer typically includes abrasive particles and a binder for securing the abrasive particles to the backing. One common construction is a backing with a resin-based binder.
For example, phenolic resin and polyethylene terephthalate (PET) film are two common materials useful for making abrasive products. However, phenolic resins do not bond well to plain, untreated polyester or PET films.
Embodiments described herein are directed to an abrasive article that not only retains the dust-extraction advantages of an abrasive on a net-type backing, but also demonstrates abrasive performance (cut and/or life) advantages of a conventional coated abrasive article. This combination of benefits (dust extraction and cut and/or life) is possible because the construction of the abrasive articles described herein allows for coating abrasive on a greater variety of backing materials, with better performance, through the application of a laminated layer between the backing material and the resin coat.
The present disclosure provides articles that include a laminate that can serve as a primer layer for a backing, for example, for improving the adhesion to a make resin layer, for example, a phenolic resin layer, in an abrasive article.
The abrasive particles 250 are at least partially embedded in the cured resin composition 240. As used herein, the term “at least partially embedded” generally means that at least a portion of an abrasive particle is embedded in the cured resin composition, such that, the abrasive particle is anchored in the cured resin composition. In some embodiments, abrasive particles 250 are coated onto the laminate 230 together in the form of a slurry composition. In such embodiments, abrasive particles 250 can optionally be oriented by influence of a magnetic field prior to the resin 240A being cured. See, for example, commonly-owned U.S. Pat. Pub. Nos. 2018/080703, 2018/080756, 2018/080704, 2018/080705, 2018/080765, 2018/080784, 2018/136271, 2018/134732, 2018/080755, 2018/080799, 2018/136269, 2018/136268.
As illustrated in
In a first step, laminate 230 is joined to fabric substrate 110 comprising strands 260 forming first void spaces 270 between the strands 260. The laminate 230 can be joined to the fabric substrate 110 by any suitable means, including by first applying a suitable adhesive layer (not shown) onto the substrate 110, followed by applying the laminate 230; by melting the laminate material onto the fabric substrate 110; printing the laminate 230 onto the fabric substrate 110; or combinations of any of the foregoing methods for joining the laminate 230 to the fabric substrate 110. The laminate 230 functions to, among other things, provide a substantially flat landing for uncured (or partially cured) resin composition 240A, such that uncured resin composition 240A that is deposited on the laminate 230 remains on the surface and does not have an opportunity to, e.g., move into the spaces 270 between strands 260 of fabric substrate 110.
In a second step, uncured resin composition 240A is joined to the laminate 230 opposite the fabric substrate 110. The uncured resin composition 240A can be joined to laminate 230 by any suitable means, including by using a (rotary) stencil/screen printing roll, flatbed screen/stencil printing or by directly printing the uncured resin composition 240A onto the laminate 230 or by using combinations of two or more suitable methods (e.g., extrusion die coating, curtain coating, knife coating, gravure coating, and spray coating) for joining the uncured resin composition 240A to the laminate 230 opposite the fabric substrate 110.
In a third step, abrasive particles 250 are joined to the uncured resin composition 240A by any suitable method, including drop, electrostatic, magnetic, and other mechanical methods of mineral coating. For example, abrasive particles 250 can be deposited onto uncured resin composition 240A by simply dropping the abrasive particles 250 onto the uncured resin composition 240A; by electrostatically depositing abrasive particles 250 onto the uncured resin composition 240A; or by using combinations of two or more suitable methods for joining the abrasive particles 250 to the uncured resin composition 240A. In some embodiments, the abrasive particles 250 can optionally be oriented under the influence of a magnetic field prior to the resin 240A being cured, as earlier indicated.
In a fourth step, the uncured resin composition 240A is cured, this way abrasive particles 250 are at least partially embedded in the cured resin composition 240 and are substantially permanently attached. Uncured resin composition 240A can be cured to form cured resin 240 by any applicable curing mechanism, including thermal cure, photochemical cure, moisture-cured or combinations of two or more curing mechanism. But if the uncured resin composition 240A is cured by any means that does not include heating, a fifth step (not shown) may be necessary to effect migration of laminate 230 away from the void spaces 270 between strands 260.
During the curing process, at least a portion of laminate 230 that is not covered by cured resin composition 240 migrates away from the first void spaces 270 between strands 260, thereby opening a plurality of second void spaces 280 extending through the laminate coinciding with first void spaces 270. The laminate 230 therefore avoids the first void spaces 270 when cured resin composition 240 is absent above the first void spaces 270. Moreover, the laminate 230 covers the first void spaces 270 when the cured resin composition 240 is above the first void spaces 270.
Although
The layer configurations described herein are not intended to be exhaustive, and it is to be understood that layers can be added or removed with respect to any of the examples depicted in
Generally speaking, laminate 230 can be any material (for example, a nonwoven or woven web or a film) that provides a landing surface for uncured (or partially cured) resin composition 240A, such that uncured resin composition 240A that is deposited on the laminate 230 remains on the surface and does not have an opportunity to, e.g., move into the void spaces 270 between strands 260 of fabric substrate 110; but at the same time migrates away from the void spaces 270 between strands 260, e.g., during the curing process that forms cured resin composition 240, thereby opening a plurality of second void spaces 280 extending through the laminate coinciding with first void spaces 270. Suitable materials for laminate 230 include hot-meltable materials, including polyester hot-meltable materials (e.g., HM4185 Polyester Hot Melt Adhesive available from Bostik, Wauwatosa, Wis.), polyamide, ethylene and acrylic acid (EAA) copolymer, ethyl methyl acetate or ethyl vinyl acetate. The laminate 230 may be provided, for example, in the form of a continuous non-apertured sheet, or as a continuous apertured sheet whereby apertures are provided in areas adjacent to or surrounding pattern elements.
Laminate 230 should adhere both to the mesh backing layer and to the resin layer. Failure at either layer will cause abrasive particles to delaminate from the backing. This is particularly important for extrusion lamination of a hot melt film, which results in a non-porous laminate that separates the make layer from the backing.
The composition and process for adhering the laminate to the backing layer can affect performance of the abrasive article. Some important parameters include re-opening of the laminate during curing of the make resin, sufficient adhesion of the laminate to a backing, and flatness of the laminate.
As described above with respect to
Adhesion to the mesh backing can reduce delamination of an abrasive article. Adhesion can be increased through extrusion temperature, nip pressure, die position, and the chemistry of the laminate.
Flatness of the laminate layer also improves adhesion of the resin and reduces shelling of abrasive particles from the resulting abrasive article. Previous laminated coated abrasive articles had a roughness above 30 μm Ra. Methods and embodiments described herein can achieve roughness values below about 20 μm Ra, or even as low as 10 μm Ra.
Extrusion can increase laminate re-opening, reduce delamination of abrasive particles and can also reduce the creation of weak points between the laminate and the mesh backing. However, extrusion does not result in a porous laminate. This prevents make resin from penetrating the laminate layer and contacting the mesh web after coating, and also results in a higher surface tension, making the re-opening process for the laminate layer prone to incomplete reopening and delamination if the incorrect conditions are used.
Improving lamination re-opening, adhesion and flatness can provide an abrasive article with better feature resolution and reduce bleed-through of the resin. Improvement in these areas can be achieved by modifying the chemical make-up of the laminate and the process conditions for applying the laminate.
In one embodiment, the laminate comprises a hot-melt polymer resin such as polyamide, polyester, poly[ethylene acrylic acid] copolymer, poly(ethylene-acrylate) copolymer, poly-(ethyl methyl acetate) copolymer, polyolefins, polyurethane polyethyl vinyl acetate, polyethylene acrylate copolymer, ethylene methacrylic acid copolymer, acid-modified ethylene terpolymers, anhydride-modified ethylene acylate, vinyl acetate polymer or a blend thereof. The laminate may also contain an additive, such as ethyl acetoacetate. In one embodiment, the laminate has at least 5% ethyl acetoacetate.
In one embodiment, the laminate material has a melting temperature between about 50° C. to about 150° C. In another embodiment the laminate material has a melting temperature between about 80° C. to about 110° C.
In one embodiment the coating weight of the laminate is between about 10 and about 60 grams per square meter (gsm). In one embodiment the coating weight of the laminate is between about 15 gsm and about 40 gsm. In one embodiment, the coating weight of the laminate is between about 15 gsm and about 25 gsm. The coating thickness of the laminate, in one embodiment, is between about 10 μm and about 50 μm. In one embodiment the coating thickness of the laminate is between about 10 μm and about 20 μm.
While mesh-based backings are suitable for applications where dust collection is a priority, it is also expressly contemplated that laminates of embodiments described herein may also be suitable for other coated abrasive article constructions used in other applications.
A coated abrasive article generally has a backing with an abrasive layer which includes a make layer, a size layer, and abrasive particles. In making such a coated abrasive article, the make layer, including a first binder precursor, can be applied to a major surface of the backing. Abrasive particles are then at least partially embedded into the make layer (for example, by electrostatic coating), and the first binder precursor is cured (that is, crosslinked) to secure the particles to the make layer. A size layer, including a second binder precursor, can be applied over the make layer and abrasive particles, followed by curing of the second binder precursor and possibly further curing of the first binder precursor.
Another type of coated abrasive article is formed by applying an abrasive layer, provided as a slurry comprised of binder precursor and abrasive particles, onto a major surface of a backing, and then curing the binder precursor.
It is known to pre-treat a backing material with a primer in order to enhance adhesion between the backing and an applied layer, such as a make layer or a laminate layer. It is expressly contemplated that such pretreatments can also be applied to a backing layer of abrasive articles described herein in addition to, or prior to, application of a laminate layer. For example, a plasma or corona treatment may be applied to a backing before the laminate layer is applied. Some examples of primer treatments are described in co-owned pending PCT application IB2019/056300, filed on Jul. 23, 2019, which claims priority to U.S. Provisional 62/702,029, filed on Jul. 23, 2018, which is herein incorporated by reference.
Some examples of typical backing treatments are a backsize layer (that is, a coating on the major surface of the backing opposite the abrasive layer), a presize layer or a tie layer (that is, a coating on the backing disposed between the abrasive layer and the backing), and/or a saturant that saturates the backing. A subsize is similar to a saturant, except that it is applied to a previously treated backing.
Coating of a backing treatment composition can be performed in a variety of ways including brushing, spraying, roll coating, curtain coating, gravure coating, and knife coating. The coated backing may then be processed for a time at a temperature sufficient to dry and at least partially crosslink the coating to form the primer layer on the backing.
In some embodiments, a backing material undergoes a surface treatment. Useful surface treatments include electrical discharge in the presence of a suitable reactive or non-reactive atmosphere (e.g., plasma, glow discharge, corona discharge, dielectric barrier discharge or atmospheric pressure discharge); ultraviolet light exposure, electron beam exposure, flame discharge, and scuffing. The surface treatment can be applied as the polyester film backing is being made or in a separate process. In some embodiments, the polyester film backing is surface-treated using corona discharge. An example of a useful corona discharge process is described in U.S. Pat. No. 5,972,176 (Kirk et al.).
Depending on the choice of abrasive layer and backing (treated or untreated), the abrasive layer may partially separate from the backing during abrading, resulting in the release of abrasive particles. This phenomenon is known in the abrasive art as “shelling”. In most cases, shelling is undesirable because it results in a loss of performance. A tie layer is sometimes disposed between the backing and the abrasive layer. See, for example, U.S. Pat. No. 5,304,224 (Harmon) and U.S. Pat. No. 5,355,636 (Harmon). A tie layer has been used to address the problem of shelling in some coated abrasive articles, for example, U.S. Pat. No. 7,150,770 (Keipert et al.)
The primer layer can include one or more additives, if desired. In some embodiments, the primer layer useful for practicing the present disclosure, includes at least one of an organic solvent, a surfactant, an emulsifier, a dispersant, a catalyst, a rheology modifier, a density modifier, a cure modifier, a diluent, an antioxidant, a heat stabilizer, a flame retardant, a plasticizer, filler, a polishing aid, a pigment, a dye, an adhesion promoter, antistatic additives. In various embodiments, the presence or lack of certain of these additives can reduce cost, control viscosity, or improve physical properties. In some embodiments, the primer layer comprises a surfactant.
It is expressly contemplated that a laminate layer may be applied to a coated abrasive article in addition to, or instead of, a primer layer. Applying a laminate layer to a backing can provide additional functionality to the coated abrasive article. However, as illustrated in the Examples, a laminate can also replace a primer layer or provide a functional improvement to the backing.
As illustrated in
A primer, or pretreatment of a backing, is considered to be different than applying a laminate to a backing. Generally, primers and pretreatments are applied as an aqueous or solvent-based mixture and react to form a film-like coating. They are not usually applied as part of an extruding or coating process, but instead require treatment, then drying and evaporation of the solvent. Additionally, the laminate is visible as a distinct layer, while primers and pretreatments do not result in a continuous film or phase. Primers and pretreatments will not result in a continuous phase on a mesh substrate because the viscosity is too low. The laminate is also formed of a high molecular weight polymer that is self-sealed with definable mechanical strength.
In another embodiment of an abrasive article according to the present disclosure, the abrasive layer may comprise abrasive particles dispersed in a binder, in some embodiments, a phenolic layer. Referring now to
In another embodiment, an abrasive article according to the present disclosure may comprise a structured abrasive article. Referring now to
In making such an abrasive article, a slurry comprising a binder precursor (in some embodiments, phenolic resin) and abrasive particles may be applied to a tool having a plurality of precisely-shaped cavities therein. The slurry is then at least partially polymerized and adhered to the primer layer, for example, by adhesive or polymerization of the slurry. The abrasive composites may have a variety of shapes including, for example, those shapes selected from the group consisting of cubic, block-like, cylindrical, prismatic, pyramidal, truncated pyramidal, conical, truncated conical, cross-shaped, and hemispherical.
The abrasive articles of the various embodiments described herein include a backing substrate 1100. Backing substrate 1100 may be constructed from any of a number of materials known in the art for making coated abrasive articles. For example, backing substrate can be any of fabric, open-weave cloth, knitted fabric, porous cloth, loop materials, unsealed fabrics, open or closed cell foams, a nonwoven fabric, a spun fiber, a film, a perforated film or any other suitable backing material. A fabric backing may include cloth (e.g., cloth made from fibers or yarns comprising polyester, nylon, silk, cotton, and/or rayon, which may be woven, knit or stitch bonded) or scrim. Many of these materials can have an uneven or rough surface. Applying a laminate to a backing material prior to applying a make coat can create a more continuous, flatter and smoother surface for abrasive coating than would be available without a laminate.
A suitable backing substrate 1100 needs to meet criteria for an abrasive application. For example, depending on an application a backing 1100 may need a particular stiffness and/or weight. However, all backings need to have a high adhesion for a make resin. Additionally, backings should be smooth and flat to promote adhesion of abrasive particles and reduce shelling.
Ideally, a backing substrate 1100 should also be a low-cost material. Several potential low-cost backing candidates, such as those with open or porous structures that are not easily sealed or have low adhesion to make resin, are often discarded as potential backing materials. However, application of a laminate may improve adhesion, smoothness and flatness of such backing candidates.
In addition to improving suitability of backing material 1100, a laminate may also provide additional functionality such as anti-static or anti-loading functionality.
Coated abrasive articles such as those described herein can be formed in a variety of ways, but generally involve coating a backing with one or more layers of material.
In step 1210, a backing is provided. The backing may be naturally flexible or stiff. A flexible backing may comprise cloth (e.g., cloth made from fibers or yarns comprising polyester, nylon, silk, cotton, and/or rayon, which may be woven, knit or stitch bonded) and scrim, for example. The flexible backing may have a rough surface and may not be flat. The backing may undergo a pretreatment, such as a plasma pretreatment 1212 or a corona pre-treatment 1214. Additionally, the backing may undergo application of another pretreatment 1216, such as application of a backsize layer, a presize layer, a tie layer, a saturant, and/or a subsize treatment.
In some embodiments of the articles, processes, and methods of the present disclosure, the polyester film backing comprises polyethylene terephthalate (PET). In some embodiments, the polyester film backing has a uniform composition throughout its thickness. In other embodiments, PET or any of the polyesters described above may be included in a layer of a multilayer film backing. In these cases, the polyester layer would be in contact with the laminate layer.
Abrasive articles according to the present disclosure and/or made by the process of the present disclosure including a polyester backing. For abrasive articles the polyester backing can be a film backing described above. In addition to the dense, monolithic film backing, fibrous backings are also useful in the abrasive articles described herein. In some embodiments, the polyester backing is a nonwoven. Nonwoven abrasive articles, such as a spunbound backing, typically include an open porous lofty polymer filament structure having abrasive particles distributed throughout the structure and adherently bonded therein by an organic binder, in some embodiments, a phenolic resin as described above in any of its embodiments. Examples of filaments include polyester fibers made from any of the polyesters described above in connection with the polyester film backing.
Nonwoven abrasives according to the present disclosure include nonwoven webs suitable for use in abrasives. The term “nonwoven” refers to a material having a structure of individual fibers or threads that are interlaid but not in an identifiable manner such as in a knitted fabric. Typically, the nonwoven web comprises an entangled web of fibers. The fibers may comprise continuous fiber, staple fiber, or a combination thereof. For example, the nonwoven web may comprise staple fibers having a length of at least about 20 mm, at least about 30 mm, or at least about 40 mm, and less than about 110 mm, less than about 85 mm, or less than about 65 mm, although shorter and longer fibers (e.g., continuous filaments) may also be useful. The fibers may have a fineness or linear density of at least about 1.7 decitex (dtex, i.e., grams/10000 meters), at least about 6 dtex, or at least about 17 dtex, and less than about 560 dtex, less than about 280 dtex, or less than about 120 dtex, although fibers having lesser and/or greater linear densities may also be useful. Mixtures of fibers with differing linear densities may be useful, for example, to provide an abrasive article that upon use will result in a specifically preferred surface finish. If a carded or airlaid nonwoven is used, the filaments may be of substantially larger diameter, for example, up to 2 mm or more in diameter. The fibers may be tensilized and crimped but may also be continuous filaments such as those formed by an extrusion process (e.g. spunbond fibers). Combinations of fibers may also be used.
The nonwoven web may be manufactured, for example, by conventional air laid, carded, stitch bonded, spun bonded, wet laid, and/or melt blown procedures. Air laid nonwoven webs may be prepared using equipment such as, for example, that available under the trade designation “RANDO WEBBER” commercially available from Rando Machine Company of Macedon, N.Y. Further details concerning nonwoven abrasive articles, abrasive wheels and methods for their manufacture may be found, for example, in U.S. Pat. No. 2,958,593 (Hoover et al.); U.S. Pat. No. 5,591,239 (Larson et al.); U.S. Pat. No. 6,017,831 (Beardsley et al.); and U.S. Pat. Appln. Publ. 2006/0041065 A1 (Barber, Jr.).
In polyester film backings useful for practicing some aspects the present disclosure, the film backing would be considered monolithic (that is, having a generally uniform film composition) and is not fibrous. Particularly, the film backing is not a nonwoven material. The polyester film backing can be described as a dense film and not an open, lofty, fibrous web.
In general, polyester film backings useful for practicing some aspects of the present disclosure have a Gurley porosity of more than 50 seconds when measured according to FTMS No. 191, Method 5452 (12/31/68) (as referred to in the Wellington Sears Handbook of Industrial Textiles by E. R. Kaswell, 1963 ed., p 575) using a Gurley Permeometer (available from Teledyne Gurley, Inc., Troy, N.Y.). The Gurley Permeometer measures the amount of time, in seconds, required for 100 cubic centimeters of air to pass through the backing material.
Polyester film backings useful for practicing some aspects of the present disclosure can have a variety of thicknesses. In some embodiments, the thickness of the polyester film backing is in a range from 1 micrometer to 500 micrometers, 10 micrometers to 350 micrometers, 25 micrometers to 250 micrometers, or 35 micrometers to 200 micrometers.
The polyester film backing useful for practicing the present disclosure may be oriented, either uniaxially or biaxially. Orientation of a film at a temperature above its glass transition temperature can be useful for enhancing at least one of the stiffness, modulus, or creep resistance of the film. Orientation can conveniently be carried out by conventional methods such as mechanical stretching (drawing) or tubular expansion with heated air or gas. Examples of useful draw ratios are in the range of 2.5 to 6 times in the machine, cross-machine direction, or both the machine and cross-machine directions. Larger draw ratios (for example, up to about 8 times) may also be useful if the film is oriented in only one direction. For biaxially oriented film backings, the film may be stretched equally in the machine and cross-machine directions or unequally in the machine and cross-machine directions.
In step 1220, a laminate is applied to the backing. The laminate may be applied, in one embodiment, as a film. For example, it may be applied as a blown melty film 1222 to a backing. In another embodiment, the laminate is extruded onto a backing 1224. Extrusion may comprise coextrusion of the laminate with the backing as well as extruding a laminate layer onto an existing backing. Other application methods are also envisioned.
The laminate may result in changed properties of the backing, once applied, as indicated in block 1232. For example, the laminate may increase the stiffness of a backing. In another example, the laminate may increase the smoothness and/or flatness of the backing. The laminate may also provide functionality, such as anti-loading properties, as indicated in block 1234, or anti-static properties, as indicated in block 1236. Anti-loading and anti-static properties are achieved by increasing the conductivity of the backing, which is achieved by using a conductive material for the laminate or a conductive additive. The laminate may also promote adhesion, as indicated in block 1238, between the make resin and the backing. The laminate may also directly or indirectly provide other benefits, as indicated in block 1242. For example, the increased flatness of a laminated backing may reduce shelling of abrasive particles during use.
In step 1230, a make coat may be applied. In some embodiments, the make coat is applied under conditions sufficient to cause reopening of the laminate layer to form voids, as described with respect to
A make coat and size coat in the abrasive articles of the present disclosure in any of their embodiments may be made from the same or different materials. Examples of these materials include amino resins, alkylated urea-formaldehyde resins, melamine-formaldehyde resins, and alkylated benzoguanamine-formaldehyde resin, acrylate resins (including acrylates and methacrylates) such as vinyl acrylates, acrylated epoxies, acrylated urethanes, acrylated polyesters, acrylated acrylics, acrylated polyethers, vinyl ethers, acrylated oils, and acrylated silicones, alkyd resins such as urethane alkyd resins, polyester resins, reactive urethane resins, epoxy resins such as bisphenol epoxy resins, isocyanates, isocyanurates, polysiloxane resins (including alkylalkoxysilane resins), reactive vinyl resins, phenolic resins (resole and novolac), and phenolic/latex resins. The resins may be provided as monomers, oligomers, polymers, or combinations thereof. The primer layer improves adhesion between the polyester backing and the make layer. In some embodiments, the make layer is an alkylated urea-formaldehyde resin, and the size layer can be made from any of the resins described above. In some embodiments, the make layer is a phenolic layer as described above in any of its embodiments, and the size layer can be made from any of the resins described above. In some embodiments, both the make layer and the size layer are made from phenolic resins, which may be combined with a latex including any of those described above in any of the ratios described above.
Suitable phenolic resins are generally formed by condensation of phenol or an alkylated phenol (e.g., cresol) and formaldehyde, and are usually categorized as resole or novolac phenolic resins. Novolac phenolic resins are acid-catalyzed and have a molar ratio of formaldehyde to phenol of less than 1:1. Resole (also resol) phenolic resins can be catalyzed by alkaline catalysts, and the molar ratio of formaldehyde to phenol is greater than or equal to one, typically between 1.0 and 3.0, thus presenting pendant methylol groups. Alkaline catalysts suitable for catalyzing the reaction between aldehyde and phenolic components of resole phenolic resins include sodium hydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide, organic amines, and sodium carbonate, all as solutions of the catalyst dissolved in water.
Resole phenolic resins are typically coated as a solution with water and/or organic solvent (e.g., alcohol). Typically, the solution includes about 70 percent to about 85 percent solids by weight, although other concentrations may be used. If the solids content is very low, then more energy is required to remove the water and/or solvent. If the solids content is very high, then the viscosity of the resulting phenolic resin is too high which typically leads to processing problems.
Phenolic resins are well-known and readily available from commercial sources. Examples of commercially available resole phenolic resins useful in practice of the present disclosure include those marketed by Durez Corporation under the trade designation VARCUM (e.g., 29217, 29306, 29318, 29338, 29353); those marketed by Ashland Chemical Co. of Bartow, Fla. under the trade designation AEROFENE (e.g., AEROFENE 295); and those marketed by Kangnam Chemical Company Ltd. of Seoul, South Korea under the trade designation PHENOLITE (e.g., PHENOLITE TD-2207). The uncured or partially cured resin composition 240A that is converted to cured resin composition 240 can comprise additional components, including polyurethane dispersions, such as aliphatic and/or aromatic polyurethane dispersions. For example, polyurethane dispersions can comprise a polycarbonate polyurethane, a polyester polyurethane, or polyether polyurethane. The polyurethane can comprise a homopolymer or a copolymer.
Examples of commercially available polyurethane dispersions include aqueous aliphatic polyurethane emulsions available as NEOREZ R-960, NEOREZ R-966, NEOREZ R-967, NEOREZ R-9036, and NEOREZ R-9699 from DSM Neo Resins, Inc., Wilmington, Mass.; aqueous anionic polyurethane dispersions available as ESSENTIAL CC4520, ESSENTIAL CC4560, ESSENTIAL R4100, and ESSENTIAL R4188 from Essential Industries, Inc., Merton, Wis.; polyester polyurethane dispersions available as SANCURE 843, SANCURE 898, and SANCURE 12929 from Lubrizol, Inc. of Cleveland, Ohio; an aqueous aliphatic self-crosslinking polyurethane dispersion available as TURBOSET 2025 from Lubrizol, Inc.; and an aqueous anionic, co-solvent free, aliphatic self-crosslinking polyurethane dispersion, available as BAYHYDROL PR240 from Bayer Material Science, LLC of Pittsburgh, Pa.
Additional suitable commercially available aqueous polyurethane dispersions include:
1) Alberdingk U 6150, a solvent-free, aliphatic polycarbonate polyurethane dispersion available from Alberdingk Boley GmbH, Krefeld, Germany, having a viscosity ranging from 50-500 mPa·s (according to ISO 1652, Brookfield RVT Spindle 1/rpm 20/factor 5), an elongation at break of about 200%, and a Koenig hardness after curing of about 65-70 s;
2) Alberdingk U 6800, an aqueous, solvent-free, colloidal, low viscosity dispersion of an aliphatic polycarbonate polyurethane without free isocyanate groups available from Alberdingk Boley GmbH, Krefeld, Germany, having a viscosity ranging from 20-200 mPa·s (according to ISO 2555, Brookfield RVT Spindle 1/rpm 50/factor 2), an elongation at break of about 500%, and a Koenig hardness after curing of about 45 seconds;
3) Alberdingk U 6100, an aqueous, colloidal, anionic, low viscosity dispersion of an aliphatic polyester-polyurethane without free isocyanate groups available from Alberdingk Boley GmbH, Krefeld, Germany, having a viscosity of 20-200 mPa·s (according to ISO 1652, Brookfield RVT Spindle 1/rpm 50 factor 2), an elongation at break of about 300%, and a Koenig hardness after curing of about 50 s;
4) Alberdingk U9800—a solvent-free aliphatic polyester polyurethane dispersion available from Alberdingk Boley GmbH, Krefeld, Germany having a viscosity of 20-200 mPa·s (according to ISO 1652, Brookfield RVT Spindle 1/rpm 20/factor 5), and elongation at break of about 20-50%, and a Koenig hardness after curing of about 100-130 s; and
5) Adiprene BL16—a liquid urethane elastomer with blocked isocyanate curing sites available from Chemtura, Middlebury, Conn.
Optional additives for polyurethane dispersions, as well as for curable compositions in general, include rheological modifiers, anti-foaming agents, water-based latexes and crosslinkers may be added to the aqueous polyurethane dispersion. Suitable crosslinkers include, for example, polyfunctional aziridine, methoxymethylolated melamine, urea resin, carbodiimide, polyisocyanate and blocked isocyanate. Additional water may also be added to dilute the formulation of the aqueous polyurethane dispersion, the phenolic resin, or combinations thereof. Curable compositions can be made, for example, from an aqueous polyurethane dispersion and a water-based latex.
The aqueous polyurethane dispersion contains less than about 20%, 10%, 5% or 2% organic solvent. In a specific embodiment, the aqueous polyurethane dispersion is substantially free of organic solvent. In some embodiments, it has been found that the aqueous polyurethane dispersion comprises at least about 7%, 15%, or 20% solids, and no greater than about 50% or 60% solids. The aqueous polyurethane dispersion may comprise no greater than about 80%, 85%, or 93% water. In some embodiments, it has been found that the aqueous polyurethane dispersion forms a film having a Koenig hardness of at least about 30 and no greater than about 200 seconds when measured according to ASTM 4366-16. Further, in some embodiments, it has been found that the aqueous polyurethane dispersion may have a surface tension that is at least about 50% of the surface tension of water and no greater than about 300% of the surface tension of water. And in some embodiments, the aqueous polyurethane dispersion may have a viscosity of at least about 10 mPa·s to no greater than about 600 mPa·s, or at least about 70%, 80% or 90% of the viscosity of water and no greater than about 600%, 500% or 400% of the viscosity of water.
In addition, in some embodiments, the aqueous polyurethane dispersion may comprise at least about 100, 1000, or even at least about 10000 parts per million (ppm) of dimethylolpropionic acid. Optional additives including rheological modifiers, anti-foaming agents, and crosslinkers may be added to the aqueous polyurethane dispersion, for example. Suitable crosslinkers include, for example, polyfunctional aziridine, methoxymethylolated melamine, urea resin, carbodiimide, polyisocyanate and blocked isocyanate. Additional water may be added to reduce viscosity of the aqueous polyurethane dispersion. Likewise, addition of up to 10 percent by weight of organic solvent (e.g., propyl methyl ether or isopropanol) to the aqueous polyurethane dispersion may be used to reduce viscosity and/or improve the miscibility of ingredients.
The dispersed polyurethane can include at least one polycarbonate segment, although this is not a requirement.
The phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 91 to 99 percent by weight phenolic resin to 9 to 1 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 56 to 91 percent by weight phenolic resin to 44 to 9 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 62 to 91 percent by weight phenolic resin to 38 to 9 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 69 to 91 percent by weight phenolic resin to 31 to 9 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 56 to 83 percent by weight phenolic resin to 44 to 17 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 56 to 76 percent by weight phenolic resin to 44 to 24 percent by weight of polyurethane. In some embodiments, the phenolic resin and aqueous polyurethane dispersion components are mixed in a solids weight ratio of 56 to 69 percent by weight phenolic resin to 44 to 31 percent by weight of polyurethane.
The curable compositions of the various embodiments described herein may further contain any of a number of additives. Such additives may be homogeneous or heterogeneous with one or more components in the composition. Heterogenous additives may be discrete (e.g., particulate) or continuous in nature.
Aforementioned additives can include, for example, surfactants (e.g., antifoaming agents such as ethoxylated nonionic surfactants such as DYNOL 604), pigments (e.g., carbon black pigment such as C-SERIES BLACK 7 LCD4115), fillers (e.g. silicon dioxide Cabosil M5), synthetic waxes (e.g., synthetic paraffin MP22), stabilizers, plasticizers, tackifiers, flow control agents, cure rate retarders, adhesion promoters (for example, silanes such as (3-glycidoxypropyl)trimethoxysilane (GPTMS), and titanates), adjuvants, impact modifiers, expandable microspheres, thermally conductive particles, electrically conductive particles, and the like, such as silica, glass, clay, talc, colorants, glass beads or bubbles, and antioxidants, so as to, e.g., reduce the weight and/or cost of the structural layer composition, adjust viscosity, and/or provide additional reinforcement or modify the thermal conductivity of compositions and articles used in the provided methods or so that a more rapid or uniform cure may be achieved.
In some embodiments, the curable compositions can contain one or more fiber reinforcement materials. The use of a fiber reinforcement material can provide an abrasive layer having improved cold flow properties, limited stretchability, and enhanced strength. Preferably, the one or more fiber reinforcement materials can have a certain degree of porosity that enables a photoinitiator, when present, to be dispersed throughout, to be activated by UV light, and properly cured without the need for heat.
The one or more fiber reinforcements may comprise one or more fiber-containing webs including, but not limited to, woven fabrics, nonwoven fabrics, knitted fabrics, and a unidirectional array of fibers. The one or more fiber reinforcements could comprise a nonwoven fabric, such as a scrim.
Materials for making the one or more fiber reinforcements may include any fiber-forming material capable of being formed into one of the above-described webs. Suitable fiber-forming materials include, but are not limited to, polymeric materials such as polyesters, polyolefins, and aramids; organic materials such as wood pulp and cotton; inorganic materials such as glass, carbon, and ceramic; coated fibers having a core component (e.g., any of the above fibers) and a coating thereon; and combinations thereof.
Further options and advantages of the fiber reinforcement materials are described in U.S. Patent Publication No. 2002/0182955 (Weglewski et al.).
In step 1240, abrasive particles are adhered. In some embodiments, abrasive particles are applied simultaneously with the application of make coat resin, such that the abrasive particles are embedded within the make coat.
A wide variety of abrasive particles may be utilized in the various embodiments described herein. The particular type of abrasive particle (e.g. size, shape, chemical composition) is not considered to be particularly significant to the abrasive article, so long as at least a portion of the abrasive particles are suitable for the intended end-use application. Suitable abrasive particles may be formed of, for example, cubic boron nitride, zirconia, alumina, silicon carbide and diamond.
The abrasive particles may be provided in a variety of sizes, shapes and profiles, including, for example, random or crushed shapes, regular (e.g. symmetric) profiles such as square, star-shaped or hexagonal profiles, and irregular (e.g. asymmetric) profiles.
The abrasive article may include a mixture of abrasive particles that are inclined on the backing (i.e. stand upright and extend outwardly from the backing) as well as abrasive particles that lie flat on their side (i.e. they do not stand upright and extend outwardly from the backing).
The abrasive article may include a mixture of different types of abrasive particles. For example, the abrasive article may include mixtures of platey and non-platey particles, crushed, agglomerated, and shaped particles (which may be discrete abrasive particles that do not contain a binder or agglomerate abrasive particles that contain a binder), conventional non-shaped and non-platey abrasive particles (e.g. filler material) and abrasive particles of different sizes.
Examples of suitable shaped abrasive particles can be found in, for example, U.S. Pat. No. 5,201,916 (Berg) and U.S. Pat. No. 8,142,531 (Adefris et al.) A material from which the shaped abrasive particles may be formed comprises alpha alumina. Alpha alumina shaped abrasive particles can be made from a dispersion of aluminum oxide monohydrate that is gelled, molded to shape, dried to retain the shape, calcined, and sintered according to techniques known in the art.
Examples of suitable shaped abrasive particles can also be found in Published U.S. Appl. No. 2015/0267097, which is incorporated herein by reference. Published U.S. Appl. No. 2015/0267097 generally describes abrasive particles comprising alpha alumina having an average crystal grain size of 0.8 to 8 microns and an apparent density that is at least 92 percent of the true density. Each shaped abrasive particle can have a respective surface comprising a plurality of smooth sides that form at least four vertexes.
U.S. Pat. No. 8,034,137 (Erickson et al.) describes alumina abrasive particles that have been formed in a specific shape, then crushed to form shards that retain a portion of their original shape features. In some embodiments, shaped alpha alumina particles are precisely-shaped (i.e., the particles have shapes that are at least partially determined by the shapes of cavities in a production tool used to make them). Details concerning such shaped abrasive particles and methods for their preparation can be found, for example, in U.S. Pat. No. 8,142,531 (Adefris et al.); U.S. Pat. No. 8,142,891 (Culler et al.); and U.S. Pat. No. 8,142,532 (Erickson et al.); and in U.S. Pat. Appl. Publ. Nos. 2012/0227333 (Adefris et al.); 2013/0040537 (Schwabel et al.); and 2013/0125477 (Adefris).
Examples of suitable crushed abrasive particles include crushed abrasive particles comprising fused aluminum oxide, heat-treated aluminum oxide, white fused aluminum oxide, ceramic aluminum oxide materials such as those commercially available as 3M CERAMIC ABRASIVE GRAIN from 3M Company, St. Paul, Minn., brown aluminum oxide, blue aluminum oxide, silicon carbide (including green silicon carbide), titanium diboride, boron carbide, tungsten carbide, titanium carbide, diamond, cubic boron nitride, garnet, fused alumina zirconia, iron oxide, chromia, zirconia, titania, tin oxide, quartz, feldspar, flint, emery, sol-gel-derived ceramic (e.g., alpha alumina), and combinations thereof. Further examples include crushed abrasive composites of abrasive particles (which may be platey or not) in a binder matrix, such as those described in U.S. Pat. No. 5,152,917 (Pieper et al.).
Examples of sol-gel-derived abrasive particles from which crushed abrasive particles can be isolated, and methods for their preparation can be found in U.S. Pat. No. 4,314,827 (Leitheiser et al.); U.S. Pat. No. 4,623,364 (Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel), U.S. Pat. No. 4,770,671 (Monroe et al.); and U.S. Pat. No. 4,881,951 (Monroe et al.). It is also contemplated that the crushed abrasive particles could comprise abrasive agglomerates such as, for example, those described in U.S. Pat. No. 4,652,275 (Bloecher et al.) or U.S. Pat. No. 4,799,939 (Bloecher et al.).
The crushed abrasive particles comprise ceramic crushed abrasive particles such as, for example, sol-gel-derived polycrystalline alpha alumina particles. Ceramic crushed abrasive particles composed of crystallites of alpha alumina, magnesium alumina spinel, and a rare earth hexagonal aluminate may be prepared using sol-gel precursor alpha alumina particles according to methods described in, for example, U.S. Pat. No. 5,213,591 (Celikkaya et al.) and U.S. Publ. Pat. Appln. Nos. 2009/0165394 A1 (Culler et al.) and 2009/0169816 A1 (Erickson et al.).
Further details concerning methods of making sol-gel-derived abrasive particles can be found in, for example, U.S. Pat. No. 4,314,827 (Leitheiser); U.S. Pat. No. 5,152,917 (Pieper et al.); U.S. Pat. No. 5,435,816 (Spurgeon et al.); U.S. Pat. No. 5,672,097 (Hoopman et al.); U.S. Pat. No. 5,946,991 (Hoopman et al.); U.S. Pat. No. 5,975,987 (Hoopman et al.); and U.S. Pat. No. 6,129,540 (Hoopman et al.); and in U.S. Patent Publication No. 2009/0165394 A1 (Culler et al.). Examples of suitable platey crushed abrasive particles can be found in, for example, U.S. Pat. No. 4,848,041 (Kruschke).
The abrasive particles may be surface-treated with a coupling agent (e.g., an organosilane coupling agent) or other physical treatment (e.g., iron oxide or titanium oxide) to enhance adhesion of the crushed abrasive particles to the binder.
The abrasive layer, in some embodiments, includes a particulate mixture comprising a plurality of formed abrasive particles (e.g., precision shaped grain (PSG) mineral particles available from 3M, St. Paul, Minn., which are described in greater detail herein; not shown in
In some embodiment, the abrasive particles may be formed abrasive particles. As used herein, the term “formed abrasive particles” generally refers to abrasive particles (e.g., formed ceramic abrasive particles) having at least a partially replicated shape. Non-limiting examples of formed abrasive particles are disclosed in Published U.S. Patent Appl. No. 2013/0344786, which is incorporated by reference as if fully set forth herein. Non-limiting examples of formed abrasive particles include shaped abrasive particles formed in a mold, such as triangular plates as disclosed in U.S. Pat. Nos. RE 35,570; 5,201,916, and 5,984,998 all of which are incorporated by reference as if fully set forth herein; or extruded elongated ceramic rods/filaments often having a circular cross section produced by Saint-Gobain Abrasives an example of which is disclosed in U.S. Pat. No. 5,372,620, which is incorporated by reference as if fully set forth herein. Formed abrasive particle as used herein excludes randomly sized abrasive particles obtained by a mechanical crushing operation.
Formed abrasive particles also include shaped abrasive particles. As used herein, the term “shaped abrasive particle,” generally refers to abrasive particles with at least a portion of the abrasive particles having a predetermined shape that is replicated from a mold cavity used to form the shaped precursor abrasive particle. Except in the case of abrasive shards (e.g. as described in U.S. patent publication US 2009/0169816), the shaped abrasive particle will generally have a predetermined geometric shape that substantially replicates the mold cavity that was used to form the shaped abrasive particle. Shaped abrasive particle as used herein excludes randomly sized abrasive particles obtained by a mechanical crushing operation.
Formed abrasive particles also include precision-shaped grain (PSG) mineral particles, such as those described in Published U.S. Appl. No. 2015/267097, which is incorporated by reference as if fully set forth herein.
Examples of suitable abrasive particles include, for example, fused aluminum oxide, heat treated aluminum oxide, white fused aluminum oxide, black silicon carbide, green silicon carbide, titanium diboride, boron carbide, silicon nitride, tungsten carbide, titanium carbide, diamond, cubic boron nitride, hexagonal boron nitride, garnet, fused alumina zirconia, alumina-based sol gel derived abrasive particles, silica, iron oxide, chromia, ceria, zirconia, titania, tin oxide, gamma alumina, and mixtures thereof. The alumina abrasive particles may contain a metal oxide modifier. The diamond and cubic boron nitride abrasive particles may be monocrystalline or polycrystalline.
In some examples, the formed abrasive particles have a substantially monodisperse particle size of from about 1 micrometers to about 5000 micrometers, from about 1 micrometers to about 2500, from about 1 micrometers to about 1000, from about 10 micrometers to about 5000, from about 10 micrometers to about 2500, from about 10 micrometers to about 1000, from about 50 micrometers to about 5000, from about 50 micrometers to about 2500, from about 50 micrometers to about 1000. As used herein, the term “substantially monodisperse particle size” is used to describe formed abrasive particles having a size that does not vary substantially. Thus, for example, when referring to formed abrasive particles (e.g., a PSG mineral particles) having a particle size of 100 micrometers, greater than 90%, greater than 95% or greater than 99% of the formed abrasive particles will have a particle having its largest dimension be 100 micrometers.
In some embodiments, the abrasive particles can have a range or distribution of particle sizes. Such a distribution can be characterized by its median particle size. For instance, the median particle size of the abrasive particles may be at least 0.001 micrometers, at least 0.005 micrometers, at least 0.01 micrometers, at least 0.015 micrometers, or at least 0.02 micrometers. In some instances, the median particle size of the abrasive particles may be up to 300 micrometers, up to 275 micrometers, up to 250 micrometers, up to 150 micrometers, or up to 100 micrometers. In some examples, the median particle size of the abrasive particles is from about 1 micrometers to about 600 micrometers, from about 1 micrometers to about 300 micrometers, from about 1 micrometers to about 150 micrometers, from about 10 micrometers to about 600 micrometers, from about 10 micrometers to about 300 micrometers, from about 10 micrometers to about 150 micrometers, from about 50 micrometers to about 600 micrometers, from about 50 micrometers to about 300 micrometers, from about 50 micrometers to about 150 micrometers.
In some examples, the abrasive particle of the present disclosure may include formed abrasive particles. The formed abrasive particles may be present from 0.01 wt. percent to 100 wt, percent, from 0.1 wt. percent to 100 wt, percent, from 1 wt. percent to 100 wt, from 10 wt. percent to 100 wt, percent, from 0.01 wt. percent to 90 wt, percent, from 0.1 wt. percent to 90 wt, percent, from 1 wt. percent to 90 wt, from 10 wt. percent to 90 wt, percent, from 0.01 wt. percent to 75 wt, percent, from 0.1 wt. percent to 75 wt, percent, from 1 wt. percent to 75 wt, from 10 wt. percent to 75 wt, percent, based on the total weight of the abrasive particles.
In some examples, the particulate mixture comprises from about greater than 90 wt. % to about 99 wt. % abrasive particles (e.g., from about 91 wt. % to about 97 wt. %; about 92 wt. % to about 97 wt. %; about 95 wt. % to about 97 wt. %; or greater than about 90 wt. % to about 97 wt. %).
Abrasive particles are at least partially embedded (for example, by electrostatic coating) in the make layer precursor, in some embodiments, comprising the phenolic resin, and the make layer precursor is at least partially polymerized.
In step 1250, additional coats are applied, such as a size or supersize coat. Such additional coats may provide additional functionality, such as lubrication or grinding aid. Next, the size layer is prepared by coating at least a portion of the make layer and abrasive particles with a size layer precursor comprising a second resin (which may be the same as, or different from, the make layer precursor), and at least partially curing the size layer precursor. The make and size layers may comprise any binder resin that is suitable for use in abrading applications. In some embodiments, the make layer precursor may be partially polymerized prior to coating with abrasive particles and further polymerized at a later point in the manufacturing process. In some embodiments, a supersize layer may be applied to at least a portion of the size layer. In some aspects articles, processes, and methods of the present disclosure include a polyester film backing. Useful polyester films may be manufactured from various types of thermoplastic polyester resins, including polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-2,6-naphthalate, and poly-1,4-cyclohexylene dimethyl terephthalate. Polyester copolymers (e.g., polyethylene terephthalate/isophthalate, polyethylene terephthalate/adipate, polyethylene terephthalate/sebacate, polyethylene terephthalate/sulfoisophthalate, and polyethylene terephthalate/azelate) may also be useful.
In some embodiments, the abrasive article of the various embodiments described herein include a size coat 510. See
In some embodiments, the abrasive article of the various embodiments described include a supersize coat 610. See
The term “substantially transparent” as used herein refers to a majority of, or mostly, as in at least about 30%, 40%, 50%, 60%, or at least about 70% or more transparent. In some examples, the measure of the transparency of any given coat described herein (e.g., the supersize coat) is the coat's transmittance. In some examples, the supersize coat displays a transmittance of at least 5 percent, at least 20 percent, at least 40 percent, at least 50 percent, or at least 60 percent (e.g., a transmittance from about 40 percent to about 80 percent; about 50 percent to about 70 percent; about 40 percent to about 70 percent; or about 50 percent to about 70 percent), according to a Transmittance Test that measures the transmittance of 500 nm light through a sample of 6 by 12 inch by approximately 1-2 mil (15.24 by 30.48 cm by 25.4-50.8 μm) clear polyester film, having a transmittance of about 98%.
One component of supersize coats can be a metal salt of a long-chain fatty acid (e.g., a C12-C22 fatty acid, a C14-C18 fatty acid, and a C16-C20 fatty acid). In some examples, the metal salt of a long-chain fatty acid is a stearate salt (e.g., a salt of stearic acid). The conjugate base of stearic acid is C17H35COO—, also known as the stearate anion. Useful stearates include, but are not limited to, calcium stearate, zinc stearate, and combinations thereof.
The metal salt of a long-chain fatty acid can be present in an amount of at least 10 percent, at least 50 percent, at least 70 percent, at least 80 percent, or at least 90 percent by weight based on the normalized weight of the supersize coat (i.e., the average weight for a unit surface area of the abrasive article). The metal salt of a long-chain fatty acid can be present in an amount of up to 100 percent, up to 99 percent, up to 98 percent, up to 97 percent, up to 95 percent, up to 90 percent, up to 80 percent, or up to 60 percent by weight (e.g., from about 10 wt. % to about 100 wt. %; about 30 wt. % to about 70 wt. %; about 50 wt. % to about 90 wt. %; or about 50 wt. % to about 100 wt. %) based on the normalized weight of the supersize coat.
Another component of the supersize coat is a polymeric binder, which, in some examples, enables the supersize coat to form a smooth and continuous film over the abrasive layer. In one example, the polymeric binder is a styrene-acrylic polymer binder. In some examples, the styrene-acrylic polymer binder is the ammonium salt of a modified styrene-acrylic polymer, such as, but not limited to, JONCRYL® LMV 7051. The ammonium salt of a styrene-acrylic polymer can have, for example, a weight average molecular weight (Mw) of at least 100,000 g/mol, at least 150,000 g/mol, at least 200,000 g/mol, or at least 250,000 g/mol (e.g., from about 100,000 g/mol to about 2.5×106 g/mol; about 100,000 g/mol to about 500,000 g/mol; or about 250,000 to about 2.5×106 g/mol).
The supersize coat may also have a grinding aid is defined as particulate material, the addition of which to an abrasive article has a significant effect on the chemical and physical processes of abrading. In particular, it is believed that the grinding aid may: (1) decrease the friction between the abrasive particles and the workpiece being abraded; (2) prevent the abrasive particles from “capping”, i.e., prevent metal particles from becoming welded to the tops of the abrasive particles; (3) decrease the interface temperature between the abrasive particles and the workpiece; (4) decrease the grinding forces; and/or (5) have a synergistic effect of the mechanisms mentioned above. In general, the addition of a grinding aid increases the useful life of the coated abrasive article. Grinding aids encompass a wide variety of different materials and can be inorganic or organic.
While grinding aids are described herein as used in the supersize layer, they may also be applied as part of the laminate layer.
Exemplary grinding aids may include inorganic halide salts, halogenated compounds and polymers, and organic and inorganic sulfur-containing materials. Exemplary grinding aids, which may be organic or inorganic, include waxes, halogenated organic compounds such as chlorinated waxes like tetrachloronaphthalene, pentachloronaphthalene, and polyvinyl chloride; halide salts such as sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, magnesium chloride; and metals and their alloys such as tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Examples of other grinding aids include sulfur, organic sulfur compounds, graphite, and metallic sulfides, organic and inorganic phosphate-containing materials. A combination of different grinding aids may be used.
Preferred grinding aids include halide salts, particularly potassium tetrafluoroborate (KBF4), cryolite (Na3AlF6), and ammonium cryolite [(NH4)3AlF6]. Other halide salts that can be used as grinding aids include sodium chloride, potassium cryolite, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride. Other preferred grinding aids are those in U.S. Pat. No. 5,269,821 (Helmin et al.), which describes grinding aid agglomerates comprised of water soluble and water insoluble grinding aid particles. Other useful grinding aid agglomerates are those wherein a plurality of grinding aid particles are bound together into an agglomerate with a binder. Agglomerates of this type are described in U.S. Pat. No. 5,498,268 (Gagliardi et al.).
Examples of halogenated polymers useful as grinding aids include polyvinyl halides (e.g., polyvinyl chloride) and polyvinylidene halides such as those disclosed in U.S. Pat. No. 3,616,580 (Dewell et al.); highly chlorinated paraffin waxes such as those disclosed in U.S. Pat. No. 3,676,092 (Buell); completely chlorinated hydrocarbons resins such as those disclosed in U.S. Pat. No. 3,784,365 (Caserta et al.); and fluorocarbons such as polytetrafluoroethylene and polytrifluorochloroethylene as disclosed in U.S. Pat. No. 3,869,834 (Mullin et al.).
Inorganic sulfur-containing materials useful as grinding aids include elemental sulfur, iron(II) sulfide, cupric sulfide, molybdenum sulfide, potassium sulfate, and the like, as variously disclosed in U.S. Pat. No. 3,833,346 (Wirth), U.S. Pat. No. 3,868,232 (Sioui et al.), and U.S. Pat. No. 4,475,926 (Hickory). Organic sulfur-containing materials (e.g., thiourea) for use in the invention include those mentioned in U.S. Pat. No. 3,058,819 (Paulson).
It is also within the scope of this disclosure to use a combination of different grinding aids and, in some instances, this may produce a synergistic effect. The above-mentioned examples of grinding aids are meant to be a representative showing of grinding aids, and they are not meant to encompass all grinding aids.
The supersize layer may also comprise other components and/or additives, such as abrasive particles, fillers, diluents, fibers, lubricants, wetting agents, surfactants, pigments, dyes, coupling agents, resin curatives, plasticizers, antistatic agents, and suspending agents. Examples of fillers suitable for this invention include wood pulp, vermiculite, and combinations thereof, metal carbonates, such as calcium carbonate, e.g., chalk, calcite, marl, travertine, marble, and limestone, calcium magnesium carbonate, sodium carbonate, magnesium carbonate; silica, such as amorphous silica, quartz, glass beads, glass bubbles, and glass fibers; silicates, such as talc, clays (montmorillonite), feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate; metal sulfates, such as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate; gypsum; vermiculite; wood flour; aluminum trihydrate; metal oxides, such as calcium oxide (lime), aluminum oxide, titanium dioxide, and metal sulfites, such as calcium sulfite.
The minimum film-forming temperature, also referred to as MFFT, is the lowest temperature at which a polymer self-coalesces in a semi-dry state to form a continuous polymer film. In the context of the present disclosure, this polymer film can then function as a binder for the remaining solids present in the supersize coat. In some examples, the styrene-acrylic polymer binder (e.g., the ammonium salt of a styrene-acrylic polymer) has an MFFT that is up to 90° C., up to 80° C., up to 70° C., up to 65° C., or up to 60° C.
In some examples, the binder is dried at relatively low temperatures (e.g., at 70° C. or less). The drying temperatures are, in some examples, below the melting temperature of the metal salt of a long-chain fatty acid component of the supersize coat. Use of excessively high temperatures (e.g., temperatures above 80° C.) to dry the supersize coat is undesirable because it can induce brittleness and cracking in the backing, complicate web handling, and increase manufacturing costs. By virtue of its low MFFT, a binder comprised of, e.g., the ammonium salt of a styrene-acrylic polymer allows the supersize coat to achieve better film formation at lower binder levels and at lower temperatures without need for added surfactants such as DOWANOL® DPnP.
The polymeric binder can be present in an amount of at least 0.1 percent, at least 1 percent, or at least 3 percent by weight, based on the normalized weight of the supersize coat. The polymeric binder can be present in an amount of up to 20 percent, up to 12 percent, up to 10 percent, or up to 8 percent by weight, based on the normalized weight of the supersize coat. Advantageously, when the ammonium salt of a modified styrene acrylic copolymer is used as a binder, the haziness normally associated with a stearate coating is substantially reduced.
The supersize coats of the present disclosure optionally contain clay particles dispersed in the supersize coat. The clay particles, when present, can be uniformly mixed with the metal salt of a long chain fatty acid, polymeric binder, and other components of the supersize composition. The clay can bestow unique advantageous properties to the abrasive article, such as improved optical clarity and improved cut performance. The inclusion of clay particles can also enable cut performance to be sustained for longer periods of time relative to supersize coats in which the clay additive is absent.
The clay particles, when present, can be present in an amount of at least 0.01 percent, at least 0.05 percent, at least 0.1 percent, at least 0.15 percent, or at least 0.2 percent by weight based on the normalized weight of the supersize coat. Further, the clay particles can be present in an amount of up to 99 percent, up to 50 percent, up to 25 percent, up to 10 percent, or up to 5 percent by weight based on the normalized weight of the supersize coat.
The clay particles may include particles of any known clay material. Such clay materials include those in the geological classes of the smectites, kaolins, illites, chlorites, serpentines, attapulgites, palygorskites, vermiculites, glauconites, sepiolites, and mixed layer clays. Smectites in particular include montmorillonite (e.g., a sodium montmorillonite or calcium montmorillonite), bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, and volchonskoite. Specific kaolins include kaolinite, dickite, nacrite, antigorite, anauxite, halloysite, indellite and chrysotile. Illites include bravaisite, muscovite, paragonite, phlogopite and biotite. Chlorites can include, for example, corrensite, penninite, donbassite, sudoite, pennine and clinochlore. Mixed layer clays can include allevardite and vermiculitebiotite. Variants and isomorphic substitutions of these layered clays may also be used.
As an optional additive, abrasive performance may be further enhanced by nanoparticles (i.e., nanoscale particles) interdispersed (e.g., in the clay particles) in the supersize coat. Useful nanoparticles include, for example, nanoparticles of metal oxides, such as zirconia, titania, silica, ceria, alumina, iron oxide, vanadia, zinc oxide, antimony oxide, tin oxide, and alumina-silica. The nanoparticles can have a median particle size of at least 1 nanometer, at least 1.5 nanometers, or at least 2 nanometers. The median particle size can be up to 200 nanometers, up to 150 nanometers, up to 100 nanometers, up to 50 nanometers, or up to 30 nanometers.
Other optional components of the supersize composition include curing agents, surfactants, antifoaming agents, biocides, and other particulate additives known in the art for use in supersize compositions.
The supersize coat can be formed, in some examples, by providing a supersize composition in which the components are dissolved or otherwise dispersed in a common solvent. In some examples, the solvent is water. After being suitably mixed, the supersize dispersion can be coated onto the underlying layers of the abrasive article and dried to provide the finished supersize coat. If a curing agent is present, the supersize composition can be cured (e.g., hardened) either thermally or by exposure to actinic radiation at suitable wavelengths to activate the curing agent.
The coating of the supersize composition onto, e.g., the abrasive layer can be carried out using any known process. In some examples, the supersize composition is applied by spray coating at a constant pressure to achieve a pre-determined coating weight. Alternatively, a knife coating method where the coating thickness is controlled by the gap height of the knife coater can be used.
Abrasive articles according to the present disclosure may be converted, for example, into a belt, roll (e.g., tape roll), disc (e.g., perforated disc), or sheet. They may be used by hand or in combination with a machine such as a belt grinder. For belt applications, the two free ends of an abrasive sheet are joined together and spliced, thus forming an endless belt.
The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range.
Unless specified otherwise herein, the term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more.
Unless specified otherwise herein, the term “substantially no” as used herein refers to a minority of, or mostly no, as in less than about 10%, 5%, 2%, 1%, 0.5%, 0.01%, 0.001%, or less than about 0.0001% or less.
Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range were explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.
In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting. Further, information that is relevant to a section heading may occur within or outside of that particular section. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
In the methods described herein, the steps can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified steps can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed step of doing X and a claimed step of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.
An abrasive article is disclosed. The article includes a backing substrate and a laminate joined to the backing substrate. The laminate comprises a hot melt polymer. The article includes a cured resin composition joined to the laminate opposite the backing substrate. The article also includes abrasive particles joined to the cured resin composition.
The abrasive article may be implemented such that the laminate at least partially wraps around the strands to leave open the first and second void spaces.
The abrasive article may be implemented such that the laminate is joined to the backing substrate as a continuous sheet, an extruded film or a coating layer.
The abrasive article may be implemented such that the laminate is extruded on to the backing substrate.
The abrasive article may be implemented such that the substrate is treated with a primer treatment before or after the lamination.
The abrasive article may be implemented such that the primer treatment is one of: a backsize layer, a presize layer, a tie layer, a saturant, a subsize treatment, a plasma treatment, a corona treatment, ultraviolet light exposure, electron beam exposure, a flame discharge, or a combination thereof.
The abrasive article may be implemented such that the fabric substrate has a first stiffness and a second stiffness after the laminate is joined to the fabric stiffness, and wherein the second stiffness is equal to or higher than the first stiffness.
The abrasive article may be implemented such that the backing comprises a woven material.
The abrasive article may be implemented such that the backing comprises a nonwoven material.
The abrasive article may be implemented such that the backing comprises a perforated film.
The abrasive article may be implemented such that the backing substrate comprises a fabric comprising strands that form first void spaces between the strands, and wherein a plurality of second void spaces extend through the laminate and coincide with first void spaces in the fabric substrate.
The abrasive article may be implemented such that the second void spaces are formed when the cured resin is joined to the laminate.
The abrasive article may be implemented such that the hot melt polymer includes polyester.
The abrasive article may be implemented such that the hot melt polymer includes polyamide, polyester, poly[ethylene acrylic acid] copolymer, poly(ethylene-acrylate) copolymer, poly-(ethyl methyl acetate) copolymer, polyolefins, polyurethanes polyethyl vinyl acetate, polyethylene acrylate copolymer, ethylene methacrylic acid copolymer, acid-modified ethylene terpolymers, anhydride-modified ethylene acylate, vinyl acetate polymer or a blend thereof.
The abrasive article may be implemented such that the laminate comprises a material with a melting point between about 30° C. to about 220° C.
The abrasive article may be implemented such that the laminate comprises a material with a melting point between about 75° C. to about 115° C.
The abrasive article may be implemented such that the laminate comprises a material with a melting temperature lower than the melting point or the degradation temperature of the resin coated above, but high enough that the laminate will not melt or wash away during resin cure and abrasive use.
The abrasive article may be implemented such that the backing substrate has a first surface roughness, and a second surface roughness after the laminate is joined to the backing substrate, and wherein the second surface roughness is less than the first surface roughness.
The abrasive article may be implemented such that the laminate joined to the backing substrate has a surface roughness value less than about 20 μm.
The abrasive article may be implemented such that the laminate joined to the backing substrate has a surface roughness value less than about 10 μm.
The abrasive article may be implemented such that the laminate has a coating weight between about 10 and about 200 gsm.
The abrasive article may be implemented such the laminate has a coating weight between about 15 and about 40 gsm.
The abrasive article may be implemented such that the laminate has a coating weight between about 25 and about 35 gsm.
The abrasive article may be implemented such that the laminate substantially prevents bleed-through of the resin to the backing substrate, such that the resin does not directly contact the backing substrate.
The abrasive article may be implemented such that the abrasive particles comprise crushed abrasive particles, formed abrasive particles, platey abrasive particles, shaped abrasive particles, or a mixture thereof.
The abrasive article may be implemented such that the abrasive particles comprise particles of similar size.
The abrasive article may be implemented such that it also includes a size coat applied over the abrasive particles.
The abrasive article may be implemented such that it also includes a supersize coat.
The abrasive article may be implemented such that the laminate has antiloading functionality.
The abrasive article may be implemented such that has antistatic functionality.
The abrasive article may be implemented such that the laminate has adhesive promotion functionality with respect to the backing and a resin composition.
The abrasive article may be implemented such that the laminate is configured to bond to a backing substrate material and a resin composition.
The abrasive article may be implemented such that the resin composition comprises a novolac phenolic or a resole-based resin, epoxy-based resin, UF-make reference.
A method of manufacturing a coated abrasive article is presented. The method includes providing a backing substrate. The method also includes applying a thermoplastic laminate. The method also includes applying a make resin. The method also includes applying a plurality of abrasive particles.
The method may also include applying a size layer.
The method may also be implemented such that the backing substrate undergoes a primer treatment, wherein the primer treatment is one of: a backsize layer, a presize layer, a tie layer, a saturant, a subsize treatment, a plasma treatment, a corona treatment, ultraviolet light exposure, electron beam exposure, or a flame discharge.
The method may also include applying the thermoplastic laminate comprises applying the laminate as a continuous sheet, a blown melty film, or an extrusion.
The method may also be implemented such that the laminate is coextruded with the backing substrate.
The method may also be implemented such that the backing substrate comprises: a woven substrate, a nonwoven substrate, a mesh substrate, a fabric substrate, a continuous material, or a perforated film.
The method may also include applying a thermoplastic laminate comprises applying a coating weight of the laminate between about 10 gsm and about 60 gsm.
The method may also include applying a thermoplastic laminate comprises applying a coating weight of the laminate between about 15 gsm and about 40 gsm.
The method may also include applying a thermoplastic laminate comprises applying a coating weight of the laminate between about 15 gsm and about 25 gsm.
The method may also be implemented such that after the laminate is applied the backing substrate has a roughness of less than about 20 μm.
The method may also be implemented such that after the laminate is applied the backing substrate has a roughness of less than about 20 μm.
The method may also be implemented such that the laminate has a coating thickness between about 10 μm and about 50 μm.
The method may also be implemented such that the laminate has a coating thickness between about 10 μm and about 20 μm.
The method may also be implemented such that the resin is a phenolic-based or resole-based resin.
The method may also be implemented such that the hot melt polymer includes polyester.
The method may also be implemented such that the hot melt polymer includes polyamide, ethylene and acrylic acid (EAA) copolymer, ethyl methyl acetate or ethyl vinyl acetate.
The method may also be implemented such that the laminate comprises a material with a melting point between about 50° C. to about 150° C.
The method may also be implemented such that the laminate comprises a material with a melting point between about 80° C. to about 110° C.
The method may also be implemented such that the backing substrate comprises a fabric comprising strands that form first void spaces between the strands, and wherein a plurality of second void spaces extend through the laminate and coincide with first void spaces in the fabric substrate.
The method may also be implemented such that the second void spaces are formed when the resin is applied to the laminate.
The method may also be implemented such that the cured resin substantially only contacts the laminate, such that the resin is substantially not in contact with the backing substrate.
The method may also be implemented such that the laminate has antiloading functionality.
The method may also be implemented such that the laminate has antistatic functionality.
The method may also be implemented such that the laminate has adhesive promotion functionality with respect to the backing and a resin composition.
The examples described herein are intended solely to be illustrative, rather than predictive, and variations in the manufacturing and testing procedures can yield different results. All quantitative values in the Examples section are understood to be approximate in view of the commonly known tolerances involved in the procedures used. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom.
Unless stated otherwise, all reagents were obtained or are available from chemical vendors such as Sigma-Aldrich Company, St. Louis, Mo., or may be synthesized by known methods. Unless otherwise reported, all ratios are by dry weight.
A 2-inch diameter lab extruder with a length to diameter ratio (L/D) of 10, supplied from the Bonnot Co. (Ohio, US), was used to extrude the polymers or the polymer blends and feed to a casting die. A molten polymer film from the casting die was cast onto a chill roll surface with surface temperature in the range of 0° C. and 40° C. The film was cooled and wound up as film sample rolls.
A Steamfast SF-680 Digital Steam Press was used for sample lamination. The equipment was preset at the “silk” mode with the top plate temperature at 130 C-140 C, measured by an IR thermometer. A 120 gsm (gram per square meter) mesh web with loops knit on one face (Sitip, Itay) was cut into 23 cm×28 cm sheet, and put on the bottom plate of the steam press with the loop-face down. A pre-extruded 30 gsm film consisting of 80% of copolyester (HM4185, Bostik, Mass.) and 20% of poly(ethylene acrylic acid) (PRIMACOR 3330, Dow Chemical) was cut into the same size, and aligned on the top of the mesh. A paper release liner with slightly larger size was put on the top to cover the film and mesh with the releasing face down. The top plate of the steam press was pushed down to close the gap until the web reached the preset temperature. The release liner was removed from the top surface after the whole web was cool down to ambient temperature to obtain a film laminated backing sample.
The steam press was preset at the “silk” mode with the top plate temperature at 130 C-140 C, measured by an IR thermometer. A 170 gsm plain-woven cotton cloth (Milliken, S.C.) was cut into 23 cm×28 cm sheet, and put on the bottom plate of the steam press with the loop-face down. A pre-extruded 165 gsm film consisting of 80% of copolyester (HM4185, Bostik, Mass.) and 20% of poly(ethylene acrylic acid) (PRIMACOR 3330, Dow Chemical) was cut into the same size, and aligned on the top of the mesh. A paper release liner with slightly larger size was put on the top to cover the film and mesh with the releasing face down. The top plate of the steam press was pushed down to close the gap until the web reached the preset temperature. The release liner was removed from the top surface after the whole web was cool down to ambient temperature to obtain a film laminated backing sample.
The steam press was preset at the “silk” mode with the top plate temperature at 130 C-140 C, measured by an IR thermometer. A 330 gsm satin-woven polyester cloth (Milliken, S.C.) was cut into 23 cm×28 cm sheet, and put on the bottom plate of the steam press with the loop-face down. A pre-extruded 204 gsm film consisting of 80% of copolyester (HM4185, Bostik, Mass.) and 20% of poly(ethylene acrylic acid) (PRIMACOR 3330, Dow Chemical) was cut into the same size, and aligned on the top of the mesh. A paper release liner with slightly larger size was put on the top to cover the film and mesh with the releasing face down. The top plate of the steam press was pushed down to close the gap until the web reached the preset temperature. The release liner was removed from the top surface after the whole web was cool down to ambient temperature to obtain a film laminated backing sample.
A Keyence VKX1100 confocal 3D measuring microscope is used to scan the surface. The microscope has a 2.5× lens and stitched 2×2, resulting in about an ˜85 mm2 area. Keyence VK Series Analyzer Software was used to acquire Sa and Sdr surface roughness/texture parameters as defined by ISO-21578, where Sa refers to the Arithmetical mean height of the surface, and Sdr refers to the Developed interfacial rea ratio.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/061600 | 12/7/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62945244 | Dec 2019 | US |
