An antiloading composition comprising a first organic compound and a second organic compound, wherein each of the first and second organic compounds independently: has a water contact angle criterion W°g that is less than a water contact angle W°z for zinc stearate; and satisfies at least one condition selected from the group consisting of a melting point Tmelt greater than about 40°C, a dynamic coefficient of friction F less than about 0.4, and an antiloading criterion P greater than about 0.2, and wherein the first and second organic compounds are different, and wherein each of the first and second organic compounds independently is represented by a formula selected from the group consisting of R-OSO&#8323;-M+, RCONH(CH&#8322;)&#8323; N+ (CH&#8323;)&#8322;CH&#8322;COO-,R-CONR’CH&#8322;C0&#8322;-M+, and R-O(CO)CH&#8322;OSO&#8323;-M+, wherein RisC6-C181inearalkyl; R¹ is C1-C4 linear alkyi; and Ml is an alkali metal ion.
SAINT-GOBAIN ABRASIVES, AMERICAN Company 1 NEW BOND STREET BOX NUMBER 1513 8 WORCESTER,MA 01615-0138 U.S.A.
ANTILOADING COMPOSITIONS AND METHODS OF SELECTING SAME BACKGROUND OF THE INVENTION Generally, abrasive products comprise abrasive particles bonded together with a binder to a supporting substrate. For example, an abrasive product can comprise a layer of abrasive particles bound to a substrate, where the substrate can be a flexible substrate such as fabric or paper backing, a non-woven support, and the like. Such products are employed to abrade a variety of work surfaces including metal, metal alloys, glass, wood, paint, plastics, body filler, primer, and the like. It is known in the art that abrasive products are subject to" loading", wherein the "swarf, or abraded material from the work surface, accumulates on the abrasive surface and between the abrasive particles. Loading is undesirable because it typically reduces the performance of the abrasive product. In response,"antiloading"compositions have been developed that reduce the tendency of an abrasive product to accumulate swarf. For example, zinc stearate has long been known as a component of antiloading compositions.
Many classes of compounds have been proposed as components of antiloading compositions. For example, some proposed components of antiloading compositions can include long alkyl chains Attached to polar groups, such as carboxylates, alkylajmmonium salts, borates, phosphates, phosphonates, sulfates, sulfonates, and the like, along with a wide range of counter ions including monovalent and divalent metal cations, organic counterions, such as tetraalkylammonium, and the like.
However, there is no known teaching in the art as to which of this large class of compounds are effective antiloading agents, short of manufacturing an abrasive product with each potential compound and performing a time consuming series of abrasion tests. Many proposed compounds are actually ineffective antiloading agents. Furthermore, some agents known to be effective for antiloading result in unacceptable contamination of the work surface, e. g., commonly leading to defects in a subsequent coating step. For example, use of zinc stearate in finishing abrasives in the auto industry leads to contamination of the primer surface, requiring an additional cleaning step to prepare the primer for a subsequent coat of paint.
Also, some antiloading agents that are known to be effective, such as zinc stearate, are insoluble in water. As a result, manufacturing an abrasive product with a water-insoluble antiloading agent can require organic solvents or additional additives and/or processing steps.
there is a need for a method of selecting effective antiloading compounds.
certain criteria, as demonstrated in Examples 1-5.
about 0.5, and an antiloading criterion P greater than about 0. 2.
proportion of each compound in the composition.
An abrasive product includes the antiloading composition.
contact angle W°p by employing the second organic compound.
in part, to the W°g of each compound and the proportion thereof.
modification and/or multiple products for different temperatures.
methods, and work product produced therefrom.
the measurement of water contact angle.
Figure 2 is a plot of antiloading criterion P versus empirical grinding performance G.
various embodiments of the invention follows.
the chemical structure of the agent.
90°, equal to 90°, and greater than 90°. This angle can be read by a goniometer.
amount of an antiloading compound, e. g. , the first organic compound. An "effective amount" is an amount of antiloading compound or antiloading composition sufficient to have an antiloading effect when present during grinding of a substrate. W°z is the water contact angle measured for a substrate ground in the presence of an effective amount of zinc stearate. When two such values are compared, e. g., when W°g is less, than W°z, it can mean that the respective water contact angles are measured for identical substrates ground with identical abrasives in the presence of an effective amount of each respective compound, e. g., the first organic compound and zinc stearate.
In various embodiments, W°g for the first compound is less than W°z„ typically less than about 125°, more typically less than about 110°, still more typically less than about 100°, yet more typically less than about 70°, or less than about 50°. In a particular embodiment, W°g for the first compound is about 0°.
In various embodiments, a particular water contact angle W°p, can be desirable, e. g., if it is an angle that can not be easily achieved by employing a single antiloading compound, or it is an angle that can be easily achieved by employing a single compound that is undesirable for other reasons, e. g., cost, toxicity, antiloading performance, and the like.. A composition can contain two or more compounds with different values for W°g, combined in a proportion mat can achieve the particular water contact angle W°p. When two compounds are employed, AT least one compound, e. g., the first organic compound, satisfies the minimum antiloading criteria, e. g., W°g is less than W°z and at least one condition is satisfied from a melting point T,.„ It greater than about 40 °C, a coefficient of friction less than about 0.6, and an antiloading criterion P greater than about 0.3. The second compound can be any effective antiloading compound, for example, the second compound can be zinc stearate. In particular embodiments, both the first and the second organic compound satisfy the minimum antiloading criteria, e. g., W°g is less than W°z and AT least one condition is satisfied from a melting point Tmeit greater than about 40 °C, a coefficient of friction less than about 0.6, and an antiloading criterion P greater than about 0.3.
composition applied to the abrasive, the work surface, or both. In other embodiments, the compounds can be employed separately, e. g, at least one compound can be included in the abrasive product, or applied to the work surface, or the abrasive, and the like. For example, the abrasive can contain at least one compound, and the second compound can be applied to the work surface using, e. g., a solution of an antiloading agent, applied by, for example, a spray gun which can be controlled to apply particular amounts. Thus, a single abrasive can be employed between multiple coatings, and the value of W°p after each grinding operation can be adjusted by the amount of the second compound that is employed. As used herein, the melting point, TMeit, of the compound can be determined by one skilled in the art by the method of differential scanning calorimetry (DSC). Further experimental details are provided in Example 3. One skilled in the art can appreciate that in this context, the term"melting point "refers to a thermal transition in the DSC plot that indicates softening of the compound, i. e., the melting point of a crystalline compound, the softening or liquefaction point of an amorphous compound, and the like. In various embodiments, the melting point of the compound is greater than about 40° C, or more typically greater than about 55° C, or alternatively, greater than about 70° C. In particular embodiments, the melting point is greater than about 90° C.
than about 0.5. Further details for antiloading criterion P are provided in Example 5 and in Figure 2.
In various embodiments, the variable DT is greater than about 20° C, typically greater than about 30° C, more typically greater than about 40° C, or alternatively greater than about 50° C. In a particular embodiment, DT is greater than about 75° C.
One skilled in the art can appreciate that many abrading applications can occur at temperatures above ambient temperature, i. e. , greater than about 20°C, due to frictional heating, workpiece baking, and the like. For example, in the automotive industry, during the painting process, a car body typically goes through a paint coating station. The car body can typically be heated to greater than ambient temperature at a paint station, which can be as high as about 43°C. As it exits the station, operators can inspect the body for defects, and identified defects can be abraded.
One skilled in the art can also appreciate that in testing to select effective antiloading compounds, the particular temperatures employed in the test to calculate P do not limit, per se, the temperatures that a selected compound can be used AT. For example, a compound that, is tested at 45° C can be used at temperatures that are higher or lower than 45° C. One skilled in the art can appreciate that certain antiloading agents, e. g., zinc stearate, can have high values for P. However, one skilled in the art can also appreciate that many applications of abrasive products can be contaminated by an antiloading agent that increases the water contact angle of the substrate. For example, if zinc stearate was employed on a surface to be coated with a water-based coating, residual zinc stearate would probably need to be removed from the abraded surface or the coating can be less effective at adhering to the surface.
The compounds, e. g., organic compounds that can be effective antiloading agents typically include surfactants or molecules with surfactant-like properties, i.e., molecules with a large hydrophobic group coupled to a hydrophilic group, e. g., anionic surfactants. Typical hydrophobic groups include branched or linear, typically linear aliphatic groups of between about 6 and about 18 carbons. Hydrophobic groups can also include cycloaliphatic groups, aryl groups, and optional heteroatom substitutions. Typical hydrophilic groups include polar or easily ionized groups, for example: anions such as carboxylate, sulfate, sulfonate, sulfite, phosphate, phosphonate, phosphate, thiosulfates, thiosulfite, borate, and the like. For example, an anionic surfactant includes a molecule with a long alkyl chain Attached to an anionic group, e. g., the C12 alkyl group Attached to the sulfate anion group in sodium dodecyl sulfate.
valences, e. g., (R-A-) 2M++, R-A-(M+) 2, R-A-H+M+, R-A~M++, and the like.
heteroaryl groups, heterocyclic groups, and the like.
aralkyl group, e. g., phenyl, benzyl, and the like.
Counterion M+ can form a salt with the compound and can be, for example, a metal cation, e.
imidazolinium, and the like. In one embodiment, M+ can be a metal ion.
particular embodiment, M+ is Na+.
another embodiment, the anionic group can be sulfate.
alkyl ; and M+ is an alkali metal ion. In other embodiments, the compound can include sodium lauryl sulfate, sodium decyl sulfate, sodium octyl sulfate, lauramidopropyl betaine, and sodium lauryl sulfoacetate. In a particular embodiment, the compound can be sodium lauryl sulfate.
As used herein, an abrasive material is any particulate ceramic, mineral, or metallic substance known to one skilled in the art that is employed to grind workpieces. For example, abrasive materials can include alpha alumina (fused or sintered ceramic), silicon carbide, fused alumina/zirconia, cubic boron nitride, diamond and the like as well as combinations thereof. Abrasive materials are typically affixed to a support substrate, (e.g., a fabric, paper, metal, wood, ceramic, or polymeric backing); a solid support, (e. g., a grinding wheel, an "emery board"), and the like. The material is affixed by combining a binder, e. g., natural or synthetic glues or polymers, and the like with the abrasive material and the support substrate, and the combination is then cured and dried. The antiloading composition can be combined with these elements at any stage of fabricating the abrasive product. In one embodiment, the antiloading composition is combined with the binder and abrasive material during manufacture of the abrasive product. In other embodiments, the antiloading composition is at the interface between the abrasive surface of the final product and the work surface swarf, e. g., by applying the antiloading composition to the abrasive surface DT manufacture, applying the antiloading composition to the abrasive surface, applying the compound to the work surface, combinations thereof, and the like. The abrasive product, . e. g. , in the form of nowoven abrasives, or coated abrasives, e. g. , sandpaper, a grinding wheel, a disc, a strip, a sheet, a sanding belt, a compressed grinding tool, and the like, can be employed by applying it to the work surface in a grinding motion, e. g., manually, mechanically, or automatically applying the abrasive, with pressure, to the work surface in a linear, circular, elliptical, or random motion, and the like. A particular embodiment includes an organic surfactant. The water contact angle criterion W°g, for a test substrate ground with an abrasive in the presence of an effective amount of the composition is less than about 20°. Also, the antiloading criterion P for the surfactant is greater than about 0.3. Typically, the organic surfactant is selected from a group consisting of sodium lauryl sulfate, sodium decyl sulfate, sodium octyl sulfate, lauramidopropyl betaine, and sodium lauryl sulfoacetate. In a particular embodiment, the surfactant is sodium lauryl sulfate.
W°g is less than W°z, Tmeit is greater than about 40° C, and F is less than about 0.5; W°g is about equal to W°, Tmeit is greater than about 40'C, and F is less than about 0.5; and AT is greater than about 5° C, F is less than about 0.5, and W°g is about equal to W°. Exemplification The following examples are provided to illustrate the principles of the embodiments, and are not intended to be limiting in any way.
Example 1: Measurement of Empirical Grinding Performance A commercial abrasive product that contained no initial antiloading composition, Norton A270 P500 sandpaper (Norton Abrasives, Worcester, Massachusetts), was employed for all tests. The experimental anti-loading agents (listed in Table 1; obtained from Stepan Company, Northfield, Illinois ; except Arquad 2HT-75, Akzo-Nobel, Chicago, Illinois; and Rhodapon LM and Rhodapex PM 603, Rhodia, Cranbury, New Jersey) were prepared as 30% solutions by weight in water and coated onto 5 inch (12.7 cm) diameter discs of sandpaper with a sponge brush. A back surface of the discs includes a mating surface comprising hook and loop fastening material. The experimental workpieces were steel panels prepared by painting the steel panels with a paint selected to be representative of a typical primer in the automotive industry, e. g., BASF U28 (BASF Corporation, Mount Olive, New Jersey). The workpieces were ground by hand using a hand-held foam pad to which the abrasive disc was attached via the hook and loop fastening material. The downward force exerted on the abrasive against the workpiece was monitored using a single-point load cell (LCAE-45kg load cell, Omega Engineering, 51C, Stamford, Connecticut) mounted underneath a 50 cm x 50 cm metal plate. The grinding was performed with the workpiece clamped on top of the metal plate. The downward force was maintained at 11 N ±1N by monitoring the output from the load cell. The foam pad was held at an approximately 60° angle relative to an axis projecting normal to the steel panels so that only approximately 1/3 of the abrasive disc's surface was in contact with the workpiece. The resulting pressure at the abrading interface was therefore approximately 2.6 KN/m2. An approximately 5 cm diameter area of the workpiece was ground with the abrasive. Sanding was performed by back-and-forth motion of the abrasive across the surface of the workpiece that was not previously ground. A rate of sanding of approximately 3 strokes per second was used. The stroke length was approximately 4 cm.
The test was performed in 5-second increments for a total of 150 seconds, or to the point where the cut rate dropped to zero, whichever occurred first. Cut rate for each increment was reported using an empirical scale of 4 through zero, where 4 represented a very aggressive cut rate and zero denoted that the product had ceased to cut altogether. The ratings were a result of visual evaluation of the amount of material removed and swarf generated combined with the amount of resistance to lateral motion felt by the operator. A high cut rate was reflected in large amounts of swarf generation and low resistance to lateral motion. Empirical performance G in the test was expressed as the sum of all the cut-rate numbers over the duration of the test. The highest G value that can be achieved in this test can be defined by 4 (maximum cut rate increment) * 30 (number of test increments) = 120. In Table 1, the empirical performance results were normalized resulting in values for G ranging from 0 to 1. The grinding tests were carried out at three values of substrate temperature Tsub, e. g., at about 21 °C, 32°C, and 43°C. The results are provided in Table 1 under G, normalized to the best performance at about 21 °C. The parameters F, AT, and P are discussed in Examples 2,3, and 5, respectively.
Table 2 shows the performance of sandpaper coated with sodium lauryl sulfate (Stepanol VA-100) versus zinc stearate and versus no coating. The total performance of each material is equal to the sum of all ratings over the 150 second test. The values for G, obtained by normalizing relative to the best-performing product in Table 1, are also shown in Table 2. The sandpaper coated with sodium lauryl sulfate performed better than the sandpaper coated with zinc stearate, which in turn performed better than uncoated sandpaper. Example 2: Measurement of Coefficient of Friction.
and then coated onto the film following the former procedure. The coated material was placed inside an oven at 145°C for 30 minutes to fuse the stearate powder onto the film. After drying in the oven, all coated samples were conditioned at room temperature for at least 40 hours prior to testing.
Once the samples were prepared, the coefficient of friction was measured by sliding coated material across itself. The apparatus used was a Monitor/Slip & Friction Model 32-26 (Testing Machine, Inc., Amityville, New York). A strip of film coated with the antiloading agent was cut and mounted to fit a 6.35 cm square sled weighing 200 grams. The sled was dragged across another strip of coated film according to the standard test method described in ASTM D 1894-01 (American Society for Testing and Materials, West Conshohocken, Pennsylvania). The strips of coated film were oriented such that the two coated surfaces are in contact as they slide past one another. The F values are provided in Table 1.
Example 3: DSC Measurement of Melting Points A sample of approximately 5 mg of each experimental antiloading compound was loaded into a differential scanning calorimeter sample cell (model DSC 2910 TA Instruments New Castle, Delaware), and the temperature was increased until the melting point was observed. The value for each compound is reported in Table 1 as Tmeit, along with AT calculated from Tme]t-TSub.
equal to 90°, and greater than 90°.
angle, e. g., W°g, can be reduced to about 0°.
Example 5: Grinding Model Predicts Variation in Antiloading Performance A regression analysis was performed, employing empirical values F and AT as the independent variables and the relative grinding performance G as the dependent variable.
Using this approach, Eq. 1 for calculated performance P was obtained. Table 1 shows the empirical G values versus the calculated P values. Table 4 shows the statistics of the regression analysis, reflecting the model's ability to account for up to about 75% of the variation in the data. Figure 2 shows a plot of P versus G.
1.	An antiloading composition comprising a first organic compound and a second organic compound, wherein each of the first and second organic compounds independently: has a water contact angle criterion W°g that is less than a water contact angle W°z for zinc stearate; and satisfies at least one condition selected from the group consisting of a melting point Tmeit greater than about 40°C, a dynamic coefficient of friction F less than about 0.4, and an antiloading criterion P greater than about 0.2, and wherein the first and second organic compounds are different, and wherein each of the first and second organic compounds independently is represented by a formula selected from the group consisting of R-OSCVM+, RCONH(CH2)3 N+ (CH3)2CH2COa,R-CONR'CH2C02-M+, and R-0(CO)CH2OS03M+, wherein RisC6-C181inearalkyl; R' is C1-C4 linear alkyi; and Ml is an alkali metal ion.
2.	The composition of Claim 1, wherein the first compound has W°g less than about 100° and satisfies at least one condition selected from the group consisting of Tmeit greater than about 70 °C, F less than about 0.4, and P greater than about 0.2.
90 °C, F less than about 0.3, and P greater than about 0.3.
4.	The composition of Claim 1, wherein W°g for the first compound is about 0°.
Iauroyl sarcoslnate, Iauramidopropyi bctaine, and sodium lauryl sulfoacetate.
6.	The composition of Claim 1, wherein the first compound is sodium lauryl sulfate.
condition selected from the group consisting of a melting point Tmeit greater than about 40 °C, a dynamic coefficient of friction V less than about 0.4, and an antiloading criterion P greater than about 0.2, and wherein the first and second organic compounds are different, and wherein each of the first and second organic compounds independently is represented by a formula selected from the group consisting of R-OSO3. ~M+ , RCONH(CH2)3N+(CH3)2CH2COa, R-CONR'CH2C02-M+, and-R-(CO)CH2OS03M+ wherein R is C6-C18 linear alkyi; R" is Cf-C4 linear alkyi; and Ml' is an alkali metat ion.
8.	The abrasive product of Claim 7, wherein the first compound has W°g less than about 100° and satisfies at least one condition selected from the group consisting of Tmen greater than about 70 °C, F less than about 0.4, and F greater than about 0.2.
9.	The abrasive product of Claim 7, wherein the first compound has W°g less than about 70° and satisfies at least one condition selected from the group consisting of Tmeit greater than about 90 °C, F less than about 0.3, and P greater than about 0.3.
10.	The abrasive product of Claim 7, wherein W°g for the first compound is about O".
11.	The abrasive product Claim 7, wherein the first compound is selected from the group consisting of sodium lauryl sulfate, sodium decyi sulfate, sodium octyl sulfate, sodium lauroyl sarcosinate, lauramidopropyi betaine, and sodium lauryl sulfoacetate.
12.	The abrasive product of Claim 7, wherein the first compound is sodium lauryl sulfate.
about 0.4, and an antiloading criterion P greater than about 0.2.
14.	The method of Claim 13. wherein the first compound satisfies at least one condition selected from the group consisting of W°g less than about 100°, Tmeit greater than about 70°C, F less than about 0.4, and P greater than about 0.2.
15.	The method of Claim 13, wherein the first compound satisfies at least one condition selected from the group consisting of W°g less than about 70°, Tmeit greater than about 90°C. F less than about 0.3, and P greater than about 0.3.
M+ is an alkali metal ion.
17- The method of Claim 13, wherein W°g for the first compound is about 0°.
18.	The method of Claim 13, wherein the first compound is selected from the group consisting of sodium Iauryl sulfate, sodium decyi sulfate, sodium octyl sulfate, sodium lauroyl sarcosinate, lauramidopropyi betaine, and sodium Iauryl sulfoacctatc.
19.	The method of Claim 13, further comprising grinding the surface lo a particular water contact angle W°p by employing a second organic compound having a W°g different from that of the first compound, wherein W°p is determined, at least in part, by the independent W°g of each compound and the proportion of each compound employed.
20.	The method of Claim 19, further comprising selecting W°p for compatibility with a coating to be applied to the ground work surface.
21.	The method of Claim 19, wherein the step of providing the anti loading composition comprises applying at least one compound to the abrasive product or the work surface.
22.	The method of Claim 19, wherein the abrasive product comprises at least one of the compounds.
23.	A method of selecting an antiloading compound, comprising selecting an organic compound, wherein the compound: has a water contact angle criterion W°gthat is less than a water contact angle W°z for zinc stearate; and satisfies at least one condition selected from the group consisting of a melting point Tmelt greater than about 40°C, a dynamic coefficient of friction F less than about 0.4, and an antiloading criterion P greater than about 0-2.
24.	The method of Claim 23, wherein the first compound satisfies at least one condition selected from the group consisting of W°g less than about 100° Tmelt greater than about 70°C, F less than about 0.4, and P greater than about 0.2.
25.	The method of Claim 23, wherein the first compound satisfies at least one condition selected from the group consisting of W°g less than about 70°, Tmelt greater than about 90°C, F less than about 0.3, and P greater than about 0.3.
26.	The method of Claim 23, wherein the first compound satisfies each condition for Tmelt, F, and P.
27.	The method of Claim 24, wherein the first compound satisfies at least two conditions selected from W°g/ Tmeltt, F, and P in Claim 28.
28.	The method of Claim 25, wherein the first compound satisfies at least three conditions selected from W° g 1 melt , F, and P in Claim 29.
29.	The method of Claim 23, wherein W°g is about 0°.
30.	The method of Claim 23, further comprising: selecting a second organic compound, wherein the second compound has a W°g different from that of the first compound; determining a proportion for each compound, whereby a composition comprising the compounds in the proportions has a particular water contact angle W°P that is due, at least in part, to the W°g of each compound and the proportion thereof.
31.	The method of Claim 25, further comprising selecting a W°p for compatibility with a particular coating.
a binder; an abrasive material affixed to the support substrate by the binder; and an antiloading composition comprising a lauryl sulfate in an amount that reduces the accumulation of swarf during grinding.
33.	The abrasive product of Claim 32, wherein the lauryl sulfalc is sodium lauryl sulfale.
compound included in the antiloading composition.
35.	The abrasive product of Claim 34, wherein the lauryl sulfate is sodium lauryl sulfate.
AGENT FOR SAINT GOBAIN ABRASIVES INC.