Patent Application
20200331118
Provided are abrasive articles, along with related compositions and methods of use. The provided abrasive articles can be useful in, for example, abrading soft materials such as painted automotive surfaces.
Abrasive articles are widely used by consumers, manufacturers, and service providers to perform sanding and finishing operations on almost any given workpiece. Potential workpieces are diverse and can have surfaces made of plastic, wood, metal, or even ceramic materials.
These articles are generally made by affixing abrasive particles onto some sort of backing, which can be either rigid or flexible. In some cases, the abrasive particles are uniformly mixed with a polymeric binder to form a slurry, which is then coated onto the backing and cured to provide the final product. Alternatively, the abrasive particles can be directly adhered to the surface of the backing by partially embedding them in curable resins called “make” and “size” coats. An advantage of the latter approach is that the abrasive particles can be provided in a preferred orientation on the working surface, enabling material to be removed efficiently. Printed flexible abrasives are a particular kind of abrasive product where a graphic image is permanently imparted onto the rough side of the abrasive sheet. Such articles offer unique benefits to both manufacturers and consumers. The ability to place graphics on an abrasive can enhance its appearance and provide branding or promotional information. The inclusion of printed information can also be effective in communicating technical details to the end user, such as its grit size, or safety information. Printing ornamental and functional images directly on the abrasive is generally preferred over placing them on product packaging because abrasive products frequently become separated from their packaging.
Disposing a printed image onto an abrasive article can be technically challenging, because the components of an abrasive article are often opaque or immiscible with each other; in combination, these components tend to show limited translucency. Methods for making abrasive articles that show graphic images visible from the abrasive-side of the article are described, for example, in provisional U.S. Patent Application Ser. No. 62/076,874 (Graham et al.).
When abrading soft materials, performance tends to diminish as debris (also known as swarf) from the sanding fills in the spaces between the abrasive grains. Swarf loading can prevent the abrasive from effectively contacting the work surface and degrade cut performance. This negative effect can be alleviated by applying a “supersize” coat of a soapy composition on top of the abrasive particles. The supersize coat generally includes an amphiphilic salt (or soap) compound, a polymeric binder, and optionally other ingredients such as a defoamer and biocide.
Conventional supersize formulations have been limited by process limitations that prevent use of high temperatures to melt the binder and provide a translucent coating. For example, use of temperatures above the melting point of the binder can significantly dry out the backing, causing brittleness and cracking and also complicate web handling of the abrasive product. While it is possible to prepare a viable coating at lower temperatures by adding significant amounts of a surfactant, this additional component adds costs and incurs associated environmental costs.
A solution to this dilemma is provided by the novel abrasive articles, compositions, and methods herein. The provided abrasive articles are borne from a supersize composition that can be dried to a translucent film at temperatures well below the melting temperature of the binder without need for a surfactant. These abrasives mitigate swarf accumulation in the areas around the abrasive particles thereby enhancing cut performance, while achieving a high degree of optical clarity. Compared with conventional abrasive articles that do not use a surfactant, these articles can provide improved clarity for a given cut performance and expected lifetime of the abrasive product.
In a first aspect, a supersize composition for an abrasive article is provided. The supersize composition comprises: calcium stearate; and an ammonium salt of a modified styrene acrylic polymer.
In a second aspect, an abrasive article is provided. The abrasive article comprises a plurality of layers, in the following order: a backing; an abrasive layer; and a supersize coat comprising the aforementioned supersize composition.
In a third aspect, a method of making an abrasive article is provided, comprising: dispersing in water the following components to provide a dispersion: calcium stearate; an ammonium salt of a modified styrene acrylic polymer; coating the dispersion onto an abrasive layer; and removing the water from the dispersion to provide the abrasive article.
Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments 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.
As used herein:
“particle aspect ratio” refers to the ratio between the longest and the shortest dimension of the particle;
“particle diameter” refers to the longest dimension of the particle;
“surfactant” refers to a water-soluble organic molecule containing both a hydrophobic group and a hydrophilic group used to lower the surface tension of water.
Described in more detail herein are abrasive articles, supersize compositions, and methods of making and using the same.
The words “preferred” and “preferably” refer to embodiments described herein that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” or “the” component may include one or more of the components and equivalents thereof known to those skilled in the art. Further, the term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.
Relative terms such as left, right, forward, rearward, top, bottom, side, upper, lower, horizontal, vertical, and the like may be used herein and, if so, are from the perspective observed in the particular figure. These terms are used only to simplify the description, however, and not to limit the scope of the invention in any way.
Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.
Further details on abrasive article constructions, backings, abrasive layers, supersize coats, and attachments layers are described in respective subsections below.
An exemplary abrasive article, shown in
Advantageously, the abrasive slurry can be cast between the underlying film and a mold having tiny geometric cavities prior to hardening. After hardening, the resulting abrasive coating is molded into a plurality of tiny, precisely shaped abrasive composite structures affixed to the underlying film. The hardening of the binder can be achieved by a curing reaction triggered by heat or exposure to actinic radiation. Examples of actinic radiation include, for example, an electron beam, ultraviolet light, or visible light.
The layer configurations described above are not intended to be exhaustive, and it is to be understood that one or ordinary skill may add or remove layers with respect to any of the embodiments depicted in
The aforementioned abrasive articles generally include a backing, such as any of backings 110, 210, 310410, 510 above. The backing may be constructed from any of a number of materials known in the art for making coated abrasive articles. Although not necessarily so limited, the backing can have a thickness of at least 0.02 millimeters, at least 0.03 millimeters, 0.05 millimeters, 0.07 millimeters, or 0.1 millimeters. The backing could have a thickness of up to 5 millimeters, up to 4 millimeters, up to 2.5 millimeters, up to 1.5 millimeters, or up to 0.4 millimeters.
The backing is preferably flexible and may be either solid (as shown in
Useful backing materials can be highly conformable. Highly conformable polymers that may be used in the backing include certain polyolefin copolymers, polyurethanes, and polyvinyl chloride. One particularly preferred polyolefin copolymer is an ethylene-acrylic acid resin (available under the trade designation “PRIMACOR 3440” from Dow Chemical Company, Midland, Mich.). Optionally, ethylene-acrylic acid resin is one layer of a bilayer film in which the other layer is a polyethylene terephthalate (“PET”) carrier film. In this embodiment, the PET film is not part of the backing itself and is stripped off prior to using the abrasive article 100. While it is possible to strip the PET from the ethylene-acrylic acid resin surface, the ethylene-acrylic acid resin and the PET can also be bonded such that these two layers stay together during use of the abrasive article.
In some embodiments, the backing has a modulus of at least 10, at least 12, or at least 15 kilogram-force per square centimeter (kgf/cm2). In some embodiments, the backing has a modulus of up to 200, up to 100, or up to 30 kgf/cm2. The backing can have a tensile strength at 100% elongation (double its original length) of at least 200 kgf/cm2, at least 300 kgf/cm2, or at least 350 kgf/cm2. The tensile strength of the backing can be up to 900 kgf/cm2, up to 700 kgf/cm2, or up to 550 kgf/cm2. Backings with these properties can provide various options and advantages, some of which are described in U.S. Pat. No. 6,183,677 (Usui et al.).
Optionally, the backing may have at least one of a saturant, presize layer, or backsize layer. These materials can be used to seal the backing or to protect yarn or fibers present in the backing. If the backing is a cloth material, at least one of these materials is typically used. Advantageously, the addition of the presize layer or backsize layer can provide a smoother surface on either the front and/or the back side of the backing. Other optional layers known in the art may also be used, as described in U.S. Pat. No. 5,700,302 (Stoetzel et al.).
The abrasive layer is a layer containing a hard mineral that serves to abrade the workpiece. In
In the configuration shown in
The abrasive particles 114 are not limited and may be composed of any of a variety of hard minerals known in the art. 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.
There is almost always some range or distribution of abrasive 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.
Optionally, the abrasive slurry is molded onto a suitable backing to form a structured abrasive. Structured abrasives can be made by mixing abrasive particles and a hardenable precursor resin in a suitable binder resin (or binder precursor) to form a slurry, casting the slurry between the underlying film and a mold having tiny geometric cavities, and then hardening the binder. After hardening, the resulting abrasive coating is molded into a plurality of tiny, precisely shaped abrasive composite structures affixed to the underlying film. The hardening of the binder can be achieved by a curing reaction triggered by heat or exposure to actinic radiation. Examples of actinic radiation include, for example, an electron beam, ultraviolet light, or visible light.
In general, the supersize coat is the outermost coating of the abrasive article and directly contacts the workpiece during an abrading operation. The supersize coat has a composition that acts to reduce the loading of swarf around the abrasive particles and improve the overall cut performance of the abrasive article.
A first major component of the provided supersize coats is a metal salt of a long-chain fatty acid. In preferred embodiments, the metal salt of a long-chain fatty acid is a stearate (i.e., a salt of stearic acid). The conjugate base of stearic acid is C17H35COO− also known as the stearate anion. Useful stearates include calcium stearate, zinc stearate, and combinations thereof.
Of the metal salts above, calcium stearate is especially preferred. Calcium stearate is a white waxy powder that, unlike other stearates, is insoluble in water and thus not a surfactant. When used in combination with certain polymeric binders (as will be discussed further below), calcium stearate can be used to prepare supersize compositions that either contain substantially reduced amounts of surfactants or are essentially free of surfactants.
Surfactants have generally been used to improve the translucency of the supersize coat that are dried at lower temperatures. The provided supersize compositions display a high degree of clarity without need for added surfactants.
In some embodiments, the supersize composition 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, according to the Transmittance Test (as described in the forthcoming Examples).
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 based on the normalized weight of the supersize coat.
A second major component of the supersize composition is the polymeric binder, which enables the composition to form a smooth and continuous film over the abrasive layer. In a preferred embodiment, the polymeric binder is an ammonium salt of a modified styrene-acrylic polymer. 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. 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. Preferably, the ammonium salt of a styrene-acrylic polymer has an MFFT that is up to 90 degrees Celsius, up to 80 degrees Celsius, up to 70 degrees Celsius, up to 65 degrees Celsius, or up to 60 degrees Celsius.
It is preferred that the binder be dried at relatively low temperatures (e.g., at 70 degrees Celsius or less). It is preferred that drying temperatures are below the melting temperature of metal salt component. As mentioned previously, use of excessively high temperatures 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 an 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.
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.
The supersize coats of the present disclosure optionally contain clay particles dispersed in the supersize coat. The clay particles are preferably uniformly mixed with the metal salt of a long chain fatty acid, polymeric binder, and other components of the supersize composition. The clay bestows unique advantageous properties to the abrasive article, such as improved optical clarity and improved cut performance. It was also discovered that the inclusion of clay particles can enable cut performance to be sustained for longer periods of time relative to supersize coats in which the clay additive is absent.
In some embodiments, the clay particles can reduce the CIELAB ΔE* color difference relative to an uncoated abrasive layer by at least 5 percent, at least 7 percent, at least 10 percent, at least 15 percent, or at least 25 percent, compared with the CIELAB ΔE* color difference obtained when the clay particles are absent.
The clay particles 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.
Useful clay particles can have particle sizes that vary over a very wide range. For example, the median particle size can be at least 0.01 micrometers, at least 0.02 micrometers, or at least 0.1 micrometers. The individual clay particles can have a median particle size of up to 100 micrometers, up to 10 micrometers, or up to 1 micrometer.
The unique physical properties of many useful clay materials relate to their layered platelet-like structures. Such particles can have a median aspect ratio of at least 10, at least 15, at least 20, at least 50, at least 75, or at least 100. Further, the median aspect ratio can be up to 10,000, up to 8000, up to 6000, up to 4000, up to 2000, or up to 1000.
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.
Layered clay materials may be either naturally occurring or synthetic. Exemplary clay materials include natural and synthetic hectorites, montmorillonites and bentonites. Examples of montmorillonite and bentonite clays include those clays available from Altana AG, Wesel, Germany, under the trade designations “CLOISITE”, “MINERAL COLLOID”, “NANOFIL”, “GELWHITE”, and “OPTIGEL” (e. g., “MINERAL COLLOID BP”, “CLOISITE NA+”, “NANOFIL 116”, and “OPTIGEL CK”), as well as those clays available from R.T. Vanderbilt, Murray, Ky., under the trade designation “VEEGUM” (e.g., “VEEGUM PRO” and “VEEGUM F”), and clay available from Nanocor, Inc., Hoffman Estates, Ill., under the trade designation “NANOMER.” Examples of hectorite clays include the commercially available clays available from Altana AG under the trade designation “LAPONITE”.
Other clay particles may be composed of vermiculite clays, such as those commercially available from Specialty Vermiculite Corp., Enoree, S.C., under the trade designations “VERMICULITE”, “MICROLITE”, “VERXITE”, and “ZONOLITE.”
Natural clay minerals often exist as layered silicate minerals. A layered silicate mineral has SiO4 tetrahedral sheets arranged into a two-dimensional network structure. A 2:1 type layered silicate mineral has a laminated structure of several to several tens of silicate sheets having a three layered structure in which a magnesium octahedral sheet or an aluminum octahedral sheet is interposed between a pair of silica tetrahedral sheets.
Particular silicates include hydrous silicate, layered hydrous aluminum silicate, fluorosilicate, mica-montmorillonite, hydrotalcite, lithium magnesium silicate and lithium magnesium fluorosilicate. Substituted variants of lithium magnesium silicate are also possible, where the hydroxyl group is partially substituted with fluorine, for example. Lithium and magnesium may also be partially substituted by aluminum. More broadly, the lithium magnesium silicate may be isomorphically substituted by any member selected from the group consisting of magnesium, aluminum, lithium, iron, chromium, zinc and mixtures thereof.
Synthetic hectorite is commercially available from Altana AG under the trade designation “LAPONITE.” There are many grades or variants and isomorphous substitutions of LAPONITE, including those synthetic hectorites available under the trade designations “LAPONITE B”, “LAPONITE S”, “LAPONITE XLS”, “LAPONITE RD”, “LAPONITE XLG”, “LAPONITE S482”, and “LAPONITE RDS.”
The clay materials can provide particular frictional and static charge accumulation properties that affect both swarf loading and abrasives performance. In regards to friction, the clay particles in the supersize coat can alleviate localized frictional heating known to increase swarf coalescence during an abrading operation. In the latter case, the clay particles can disrupt the electrostatic attraction that normally occurs between the abrasive article 100 and swarf particles.
As an optional additive, abrasive performance may be further enhanced by nanoparticles (i.e., nanoscale particles) interdispersed with the clay particles of 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.
The nanoparticles can have any of a number of different particle size distributions. In some embodiments, the nanoparticles have a D90/D50 particle size ratio of at least 1.1, at least 1.2, at least 1.3, or at least 1.4. In some embodiments, the nanoparticles have a D90/D50 particle size ratio of up to 5, up to 4, up to 3, up to 2, or up to 1.8.
In some embodiments, the nanoparticles are sintered to form nanoparticle agglomerates. For example, the nanoparticles may be comprised of fumed silica in which primary silica particles are sintered to provide silica particles aggregated into chains.
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 embodiments, by providing a supersize composition in which the components are dissolved or otherwise dispersed in a common solvent. Preferably, the solvent is water. After being suitably mixed, the supersize dispersion can be coated onto the underlying layers of the abrasive article and cured (i.e., hardened) either thermally or by exposure to actinic radiation at suitable wavelengths to activate the curing agent.
Any known method can be used to coat the dispersion above onto the supersize coat. In exemplary embodiments, the dispersion 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 could be used.
An attachment layer can be affixed to the backing to help secure the abrasive article to a sanding block, power tool, or even the hand of an operator. In
Additional options and advantages of these abrasive articles are described in U.S. Pat. No. 4,988,554 (Peterson, et al.), U.S. Pat. No. 6,682,574 (Carter, et al.), U.S. Pat. No. 6,773,474 (Koehnle et al.), and U.S. Pat. No. 7,329,175 (Woo et al.).
While not intended to be limiting, the following represent particular embodiments of the abrasive articles and methods described herein:
Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.
The following abbreviations are used to describe the examples:
° C.: degrees Centigrade
cm: centimeter
cm/s: centimeters per second
ctg. wt.: coating weight
g/m2: grams per square meter
in/s: inches per second
Kg: kilogram
lb: pound
MFFT minimum film forming temperature
min: minute
mL: milliliter
micrometer
nm: nanometer
rpm: revolutions per minute
Tg: glass transition temperature
wt. %: weight percent
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.
Abbreviations for materials and reagents used in the examples are as follows:
A stearate/styrene acrylic supersize composition was prepared as follows. 81.47 grams calcium stearate dispersion LS233, 13.81 grams styrene acrylic dispersion J-89, 3.86 grams surfactant DPnP, 0.68 grams anti-foaming agent HL27 and 0.16 grams KATH were homogeneously dispersed by means of a propeller blade mixer at 500 rpm for 5 minutes at 21° C. Approximately 1 mL of this supersize composition was evenly coated onto the corona treated surface of a 15 by 20 cm by 2 mil (50.8 μm) sheet of clear polyester film using a Meyer rod bar coater and dried for 30 seconds at 70° C. in an air-circulating oven. % Transmittance of the dried coating was then measured at 500 nm using a spectrophotometer.
Stearate/styrene acrylic supersize compositions were prepared and coated onto the clear polyester film according to the procedure generally described in Comparative A, wherein the styrene acrylic emulsion J-89 was replaced with J-7051 according to the quantities listed in Table 1.
Three batches of the LS-233 stearate, having differing levels of translucency, were coated onto clear polyester sheets, dried and the % transmittance measured. Stearate/styrene acrylic supersize compositions as listed in Table 2 were then prepared and coated onto clear polyester film according to the procedure generally described in Comparative A. With respect to Comparative D, the nanoparticle clay was pre-dispersed before homogeneously blending into the stearate suspension by means of the high speed propeller mixer. % transmittance values are listed in Table 2.
Stearate/styrene acrylic supersize compositions as listed in Table 3 were prepared and coated onto clear polyester film according to the procedure generally described in Comparative A, and the % transmittance and Tg measured.
Stearate/styrene acrylic supersize compositions listed in Table 4 were prepared, coated onto clear polyester film according to the procedure generally described above, and evaluated for % transmittance.
A grade P320 coated abrasive obtained under the trade designation “3M 216U P320 GOLD” obtained from 3M Company, St. Paul, Minn., was manufactured without the stearate supersize, and converted into 12 by 25 inch (30.48 by 63.50 cm) sheets. It is to be understood that, to one of ordinary skill in the art, the stearate supersize on a commercially available coated abrasive sheet could be removed merely by gently brushing off said supersize using a dilute aqueous soap solution. Comparatives L-M and Example 8 were applied to the coated abrasive sheets by means of a laboratory coater and dried at 70° C. for 30 seconds. A pressure sensitive adhesive was then laminated to the backside of the coated abrasive sheet, the sheet converted into 6 inch (15.24 cm) diameter discs, and evaluated for cut performance as follows. The abrasive disc was mounted on a 6 inch (15.24 cm) diameter “STIKIT” backup pad, part no. 05576, obtained from 3M Company. This assembly was then attached to the dual action axis of a servo controlled motor, disposed over an X-Y table, with a cellulose acetate butyrate test panel secured to the table. The servo controlled motor was run at 7200 rpm, and the abrasive article urged at an angle of 2.5 degrees against the test panel at a load of 13 lbs (5.90 Kg). The tool was then set to traverse at a rate of 20 in/s (50.80 cm/s) along the width of the panel and traverse along the length of the panel at a rate of 5 in/s (12.70 cm/s). Seven such passes along the length of the panel were completed in each cycle, over a one minute interval, for a total of 5 cycles. The mass of the panel was measured before and after each cycle to determine the total mass lost in grams for each cycle, as well as a cumulative mass loss at the end of 5 cycles. Three abrasive discs were tested per each sample. Results are listed in Table 4.
Stearate/styrene acrylic supersize compositions listed in Table 5 were prepared and then coated onto clear polyester film, and grade P320 coated abrasive sheets, according to the procedures generally described above. Table 5 lists the % transmittance and total cut after 5, one-minute, cycles, from an average of 4 discs per sample.
A urea-urea-formaldehyde coated abrasive having a grade P180 alumina mineral, obtained under the trade designation “3M GOLD ABRASIVE STIKIT, 236U P180” from 3M Company.
A coated abrasive as described in Comparative O, wherein 5% by weight of the P180 alumina mineral was substituted with an equal weight of a P180+ equilateral triangular shaped alumina abrasive grain having a length of 0.198 mm, a thickness of 0.047 mm and a sidewall angle of 8 degrees, was manufactured without the stearate supersize. It is to be understood that, to one of ordinary skill in the art, the stearate supersize on a commercially available coated abrasive sheet could be removed merely by gently brushing off said supersize using a dilute aqueous soap solution. The coated abrasive was converted into 12 by 25 inch (30.48 by 63.50 cm) sheets and the supersize composition Example 9 then applied by means of a laboratory coater and dried at 70° C. for 30 seconds. The cut performance of both the Comparative and Example were determined and the results are listed in Table 6.
All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/069266 | 12/29/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62321985 | Apr 2016 | US |
