KR20030091955A - Anti-loading treatments - Google Patents

Abstract

The abrasive is overdimensioned into a layer substantially consisting of an inorganic filler inhibitor selected from the group consisting of metal silicates, silicas, metal carbonates and metal sulfates. The metal silicate may be selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. In one embodiment, the magnesium silicate comprises talc, potassium aluminum silicate comprises mica, aluminum silicate comprises clay, and calcium silicate comprises wollastonite. The silica may be selected from the group consisting of fused silica, fumed silica and amorphous precipitated silica. Metal carbonates may include calcium carbonate. Metal sulfates can include aqueous calcium sulfate or anhydrous calcium sulfate.

Description

Anti-loading treatments

Coated abrasive products are used to polish a variety of substrates that may include soft materials that are difficult to finish, such as coated surfaces. When finishing these soft materials, the coated abrasive product may not be able to achieve their full capacity due to premature filling. Loading is the adhesion of residues that block the space between the abrasive particles and prevent the abrasive product from continuously polishing the working substrate or surface effectively. The abrasive industry method uses chemical compounds such as metal soaps (i.e. zinc stearate, calcium stearate) applied as an oversize coating or introduced into the size coating, which is commonly referred to as a first sizing coating. . Stearate technology provides adequate stock removal and anti-loading properties. However, metal stearate leaves residues of low surface energy material on the working surface, which may lead to post-processing problems such as coating defects in the downward painting process.

Contamination of these materials with low surface energy can be detected by measuring the water contact angle on the polished substrate. Conventional means to solve this problem is to clean the polished surface with solvent abrasive or finish with a nonstearate product, preferably so that all dirt is removed.

Summary of the Invention

Cleaning the polished surface with solvent abrasive may be omitted, as it consumes valuable time and cost in the application process. In addition, non-stearate products typically do not provide long life.

In one embodiment, the abrasive, such as coated abrasive or composite abrasive, is substantially overdimensioned with a layer consisting of an inorganic filler inhibitor selected from the group consisting of metal silicates, silica, metal carbonates, and metal sulfates.

The layer consists essentially of an inorganic charge inhibiting additive, which is an organic component such as that represented by conventional charge inhibiting additives including metal salts of organic acids, organophosphates, organosilicates, organoborates, and the like. It does not include an additive having a. However, this does not preclude the presence of a cured binder component that provides a vehicle to which inorganic fillers are applied.

The metal silicate may be selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. In one embodiment, magnesium silicate includes talc, potassium aluminum silicate includes mica, aluminum silicate includes clay, and calcium silicate includes wollastonite. The silica may be selected from the group consisting of fused silica, fumed silica and amorphous precipitated silica. Metal carbonates may include calcium carbonate. Metal sulfates can include aqueous calcium sulfate or anhydrous calcium sulfate.

The filling inhibitor may have a Mohs hardness value of less than about 7, preferably less than about 3. The charge inhibitor may have an average particle diameter size of less than about 30 μm, preferably in the range of about 1 to about 20 μm. This causes the filler inhibitor to form sufficiently small particles that are combined with the residue from the polished surface, for example the applied metal surface, in order to prevent sufficient coagulation filling of the residue at the surface of the coated abrasive. That is, the particles of the filler inhibitor are sized such that when the coated surface is polished using a coated abrasive to produce worn residue, the particles of the filler inhibitor which bind to these residue particles and inhibit the aggregation of these particles are released. Have

In a further embodiment, the concentration of the filler inhibitor is mainly concentrated in the oversize layer. For example, the concentration may be at least 10% by volume, preferably at least about 60%, by volume of the overdimensioned layer.

The filling inhibitor is preferably dispersed in a binder comprising, for example, a thermoplastic or thermosetting resin. For example, the thermoplastic resin may comprise a latex and the thermosetting resin may be selected from the group consisting of urea formaldehyde, phenolic, epoxy, urethane and radiation curable resin systems.

A coated abrasive or composite abrasive comprising a backing layer having a first surface, an abrasive layer having a plurality of abrasive particles deposited on the first surface of the backing layer, and a layer substantially consisting of an inorganic filler inhibitor deposited over the abrasive layer; Abrasive is also provided. In one embodiment, the filling inhibitor is deposited on a cured size coating.

Also provided is a method of forming an abrasive, such as a coated abrasive or a composite abrasive, comprising attaching a plurality of abrasive particles to a first surface of a backing layer and depositing a layer consisting of a filler inhibitor over the abrasive particles. do.

Brief description of the drawings

These and other objects, features and advantages of the present invention will become apparent from the following more detailed description of the preferred embodiments of the present invention. The accompanying drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

The figure illustrates the contact angle θ of solid, liquid and vapor.

Coated abrasives generally include articles having an abrasive grit attached to the backing of the support, which can be used for polishing or otherwise abrasion of the product surface to which they are applied.

The support backing of the coated abrasive may be rigid, but is generally flexible and typically includes a web of material, such as paper, fabric, fibrous pads, polymeric films, vulcanized fibers or combinations of these materials, and the like. In some applications, the backing of the support first includes a collection of flexible fibers to which the abrasive grit is added in the presence or absence of additional binder material to provide an abrasive web with grit everywhere. The flexible aggregate of fibers and grit can be compressed when no adhesive binder is present, or fixed or cured when the binder is present to form a coated abrasive.

Abrasive grit can generally be any material that has the abrasive ability of the workpiece, and is typically sand, flint, corundum, metal oxides (e.g. aluminum oxide), aluminum-zirconia, ceramic alumina, diamond, silicon carbide, garnets, rouges ( rough, crocus, and the like. The grit usually has a sharp edge that acts as a polishing means, but the quality and amount of the sharp edge depends on the application. The grit can be inserted into or mixed with the backing of the support, but more typically is attached to the backing of the support by a suitable binder material. The grit can be applied or blended to the web in a specific pattern or grain, or distributed randomly. Typically, sophisticated means are employed such that the coated abrasive has a fixed grain with an appropriate distribution of granular cutting edges in one or more layers.

The binder material is generally any convenient material that serves to attach the grit to the backing of the support and to tolerate the absence of the polishing process. Typical binder materials include adhesion to phenolic resins, leather glues, varnishes, epoxy resins, acrylates, polyfunctional acrylates, urea-formaldehyde resins, trifunctional urethanes, polyurethane resins, lacquers, enamels, and support backings. Various other materials are included that have the ability to stabilize grit in this regard. In general, the binder material is carefully selected to provide maximum efficiency of the coated abrasive in consideration of the abrasive surface. Care should be taken when selecting binder materials to ensure that they are resistant to softening or combustion due to excessive heating and provide adequate adhesion.

The grit can be sprayed or otherwise coated onto the binder material and deposited on or near the backing of the support, or the backing of the support with the binder material and grit and then deposited thereon. Many other forms of support backing, particulate material, binder material, means for aligning grit on the back of the support, means for attaching the grit, and the like are known in the art, and such variations are contemplated as being within the scope of the present invention.

In general, the backing (with or without pretreatment) is provided when making a coated conventional abrasive and a maker coating of binder resin is applied, while an abrasive grit is applied over the maker coating when the resin is still tacky, The binder is cured to hold the grit in place. Subsequently, a size coating comprising substantially binder resin and optional fillers, polishing aids, and the like is applied on the grit and cured. The main function of the size coating is to hold the grit in place and to polish the workpieces without pulling them out of the coated abrasive structure before their polishing capacity is exhausted. In some cases, the oversize layer is deposited on the size coating. The function of this layer is to place additives on the coated abrasive surface that provide particular properties such as improved polishing performance, surface lubricity, antistatic properties or in this case charge inhibiting properties. Overdimension layers are generally, but not necessarily, involved in securing the grit in position over the coated abrasive.

The additive may be applied as a dispersant in a binder, which may subsequently be cured, or as a liquid dispersant, which simply leaves an additive on the surface when dried. In one embodiment, the binder includes a thermoplastic or thermoset resin. For example, the thermoplastic resin includes latex, and the thermosetting resin may be selected from the group consisting of urea formaldehyde, phenolic, epoxy, urethane, and radiation curable resin systems. With some additives, it is possible to achieve adhesion to the surface without the dispersion medium.

According to the invention, the filling inhibitor applied on the size coating may be selected from the group consisting of metal silicates, silicas, metal carbonates and metal sulfates. The metal silicate may be selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. In one embodiment, magnesium silicate includes talc, potassium aluminum silicate includes mica, aluminum silicate includes clay, and calcium silicate includes wollastonite. The silica may be selected from the group consisting of fused silica, fumed silica and amorphous precipitated silica. Metal carbonates may include calcium carbonate. Metal sulfates can include aqueous calcium sulfate or anhydrous calcium sulfate.

According to the present invention, the inorganic filler suppresses the fine particles during use, and these fine particles cover the residual fine particles produced by the polishing process so that they do not agglomerate and form cumbersome larger particles trapped on the coated abrasive surface ( Known as “filling”) to reduce their effects. Thus, the filling of the coated abrasive is reduced without causing problems associated with the use of conventional stearate charge inhibiting layers. With such additives, a fine coating of low energy material soils the worn surface, which makes it very difficult to subsequently apply or polish the surface unless such coating is removed.

In one embodiment, the charge inhibitors of the present invention are relatively soft, for example, having a Mohs hardness of less than about 7, preferably less than about 3. In one embodiment, the filler has an average particle diameter size range of less than about 30 μm, preferably in the range of about 1 to about 20 μm, with finer material having a finer particle size that acts better as a filling inhibitor.

One mechanism of providing charge inhibiting properties is believed to be to reduce charge by preventing residual particles from adhering to each other in the case of charge inhibitors. This method generates fine dust during polishing, whereas in the absence of an inorganic filling inhibitor, the residue tends to form balls or large chips, which balls or chips stay between particles and prevent effective polishing and are coated abrasive Decreases its lifespan. Differences in appearance of residues polished using stearated and non-stearate products are evident.

According to the invention, the concentration of the filler inhibitor at the abrasive surface of the oversize layer is greater than about 10% by volume, preferably greater than about 60% by volume. This ensures that the filling inhibitor is sufficiently present to effectively produce fine dust that prevents the aggregation of the residue.

Fill inhibitors can be used with other abrasives, such as composite (nonwoven) abrasives.

Example 1 Aqueous Magnesium Silicate (Talc) with Different Median Particle Sizes

In the following and subsequent examples, a reference abrasive coated conventional abrasive is used. The backing material is an A-weight paper and the maker coating and the size coating include a urea-formaldehyde binder. In each case, the abrasive particles are P320 aluminum oxide. An oversize coating comprising a charge inhibiting additive is applied to this base coated abrasive. In one case no additives are applied for comparison. In the second case an oversize coating containing zinc stearate is applied, and in three other cases the coating applied is aqueous magnesium silicate (talc) with different particle sizes. The additive is applied as a dispersant in latex or water.

Subsequently, the coated abrasive is used to polish the acrylic panel using a double action sanding machine for six contacts each two minutes apart. Grinding is performed with a 4.5 kg (10-lb) load on a 12.7 cm (5 in) disc. The amount of cutting after a total polishing time of 12 minutes is recorded and the polishing performance is measured as the cutting percentage of the control. Average surface roughness (Ra; arithmetic mean of roughness) is also measured. The results are listed in Table 1 below, demonstrating that talc is as effective as the more common zinc stearate.

Filling inhibitor none Zinc stearate Aqueous magnesium silicate (talc) Aqueous magnesium silicate (talc) Aqueous magnesium silicate (talc) Item Base control Zinc stearate Bertal 1500 Supreme HT Arctic Dust Charge Suppression Medium Particle Size N / A 5.6μ 15μ 7μ 1.9μ Anhydrous coating weight (g / cm ² ) N / A 14.80 Approximately 13.32 Approximately 13.32 Approximately 13.32 Filler Volume% (Charge Inhibitor) N / A 90 81 81 81 Binder volume% N / A 9.05 11 11 11 Cutting (% of control) 100% 136% 121% 134% 137% Surface finish, Ra (μm) 0.46 0.41 0.46 0.46 0.46

Vertal 1500, Supreme HT and Artic Dust are talc marketed by Luzenac-America, Inc.

Example 2: Aqueous Magnesium Silicate (Talc), Supreme HT with Different Grit Sizes

The following table compares the polishing performance of the control without Supreme Inhibitors HT talc with zinc stearate and the filler inhibitors for aluminum oxide coated abrasives in grit P80, P180 and P320 (Tables 2, 3 and 4, respectively). Explain what you did. This result indicates that cutting in particularly finer grit compared to the base control is higher with the introduction of the filling inhibitor of the present invention.

P80 Base control Witco Zn-St Dispersant Supreme HT Talc Anhydrous coating weight (g / m ² ) N / A 14.80 Approximately 13.32 Filler Volume% (Charge Inhibitor) N / A 90 81 Binder volume% N / A 9.05 11 Cumulative cutting (g) 21.61 24.43 22.54 % Of control 100% 113% 104% Ra (μm) 1.88 1.96 2.05

P180 Base control Witco Zn-St Dispersant Supreme HT Talc Anhydrous coating weight (g / m ² ) N / A 14.80 Approximately 13.32 Filler Volume% (Charge Inhibitor) N / A 90 81 Binder volume% N / A 9.05 11 Cumulative cutting (g) 15.87 23.5 19.76 % Of control 100% 148% 125% Ra (μm) 0.84 0.89 0.89

P320 Base control Witco Zn-St Dispersant Supreme HT Talc Anhydrous coating weight (g / m ² ) N / A 14.80 Approximately 13.32 Filler Volume% (Charge Inhibitor) N / A 90 81 Binder volume% N / A 9.05 11 Cumulative cutting (g) 7.75 13.51 12.93 % Of control 100% 174% 167% Ra (μm) 0.46 0.41 0.43

Example 3: amorphous silica, calcium silicate (wollastonite), aluminum silicate (clay) and potassium aluminum silicate (mica)

Conventional abrasives coated with aluminum oxide on a standard P320 grit A-weight paper are used. To this base coated abrasive, an oversize coating comprising an amorphous filler, a silicate calcium silicate (wollastonite), an aluminum silicate (clay) or an aluminum silicate potassium mica (charge suppressing additive) is applied. The polishing results described in Table 5 below indicate that cutting was higher at the introduction of the filler inhibitors of the present invention compared to the base control.

Filling inhibitor N / A Amorphous silica Calcium silicate Anhydrous aluminum silicate (clay) Water-based aluminum silicate (clay) Aqueous potassium aluminum silicate (mica) Item Control MN-23 Wollastonite Optiwhite Burgess 17 Mica 325 Anhydrous coating weight (g / m ² ) N / A 4.44 51.80 7.40 16.28 2.96 Filler Volume% (Charge Inhibitor) N / A 81 83 80 79 79 Binder volume% N / A 12 10 12 12 12 % Of control 100% 161% 113% 179% 113% 149% Surface roughness, Ra (㎛) 0.61 0.51 0.43 0.53 0.61 0.38

MN-23 is an amorphous silica commercially available from Eagle Pitcher.

Wollastonite 325 is calcium silicate sold by NYCO Minerals, Inc.

Optiwhite is clay sold by Burges Pigment Company.

Burgess 17 is a clay marketed by Burgess Pigment Company.

Mica 325 is a mica marketed by Oglebay Norton Specialty Minerals.

Example 4: calcium sulfate (anhydrous and aqueous)

Conventional abrasives coated with aluminum oxide on a standard P320 grit A-weight paper are used. To this base coated abrasive is applied an oversize coating comprising a charge inhibiting additive of calcium sulfate (anhydrous or aqueous). The results listed in Table 6 below show that the cutting is higher in the introduction of the filling inhibitors of the present invention compared to the base control.

Filling inhibitor Anhydrous calcium sulfate Aqueous calcium sulfate Item Base control Snow white (SNOW WHITE) TERRA ALBA Anhydrous coating weight (g / m ² ) N / A 34.04 29.60 Filler Volume% (Charge Inhibitor) N / A 76 82 Binder volume% N / A 14 9 % Of control 100% 153% 141% Surface Roughness, Ra (μm) 0.51 0.41 0.43

SNOW WHITE is anhydrous calcium sulfate marketed by United States Gypsum Company.

TERRA ALBA is an aqueous calcium sulfate marketed by United State Gibsom Company.

Example 5 Water Contact Angle of an Abrasive Paint Panel After Polishing

The primer panel is polished with a P320 grit coated abrasive having an oversize coating described in Examples 1-4. The same polishing process is used for each coated abrasive. Subsequently, a drop of water is placed on each freshly polished panel and also on the unpolished panel, and the contact angle θ is recorded as described in the figure. The contact angle is the angle between the surface of the liquid and the surface of the solid plane in the contact line. Higher contact angles indicate less wettability. These results are shown in Table 7, which indicates that the contact angle of the panel polished with the coated abrasive according to the invention is substantially the same or lower compared to the panel polished with the coated abrasive without the charge inhibiting layer. It is clearly shown. Coated abrasives with conventional zinc stearate charge inhibiting layers have apparently deposited residues with low surface energy, the presence of which is manifested by very high water contact angles. The result is that the paint applied to such a surface does not easily wet the surface, leading to surface defects.

Filling inhibitor N / A Zinc stearate Aqueous magnesium silicate (talc) Aqueous potassium aluminum silicate (mica) Calcium silicate Anhydrous calcium sulfate Item Base control Zinc stearate Supreme HT Mica 325 Wollastonite Snow white Anhydrous coating weight (g / m ² ) N / A 14.80 About 7.40 to 17.76 2.96 51.80 34.04 Filler Volume% (Charge Inhibitor) N / A 90 81 79 83 76 Binder volume% N / A 9.05 11 12 10 14 Water contact angle (°) 115 140 114 119 86 107

The water contact angle on the unpolished panel is 69 °.

Although the present invention has been particularly shown and described with reference to preferred embodiments thereof, those skilled in the art can not make various changes in form and detail without departing from the scope of the invention as defined in the appended claims. Will understand.

Claims (32)

An abrasive oversize with a layer substantially comprised of an inorganic anti-loading agent selected from the group consisting of metal silicates, silicas, metal carbonates and metal sulfates. The abrasive according to claim 1, wherein the metal silicate is selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. The abrasive according to claim 2, wherein the magnesium silicate comprises talc. The abrasive according to claim 2, wherein the potassium aluminum silicate comprises mica. The abrasive according to claim 2, wherein the aluminum silicate comprises clay. The abrasive according to claim 2, wherein the calcium silicate comprises wollastonite. The abrasive according to claim 1, wherein the silica is selected from the group consisting of fused silica, fumed silica and amorphous precipitated silica. The abrasive according to claim 1, wherein the metal carbonate comprises calcium carbonate. The abrasive according to claim 1, wherein the metal sulfate comprises aqueous calcium sulfate or anhydrous calcium sulfate. The abrasive according to claim 1, wherein the Mohs hardness value of the filling inhibitor is less than about 7. The abrasive of claim 1, wherein the filler inhibitor has an average particle diameter size of less than about 30 μm. 12. The abrasive according to claim 11, wherein the filler inhibitor has an average particle diameter size range of 1-20 [mu] m. The abrasive according to claim 1, wherein the filler inhibitor is mainly concentrated in the oversize layer. The abrasive according to claim 1, wherein the filling inhibitor comprises at least 10% by volume of the oversize layer. 15. The abrasive of claim 14, wherein the filling inhibitor comprises at least 60% by volume of the overdimension layer. The filling inhibitor according to claim 1, wherein the particles of the filling inhibitor are bonded to the coated surface using a coated abrasive to produce a worn swath, which, in turn, binds to these residue particles to inhibit aggregation of these residue particles. An abrasive having a size that allows particles to be released. The abrasive of claim 1 selected from the group consisting of coated abrasive and composite abrasive. The abrasive of claim 1 wherein the filler inhibitor is dispersed in a binder. 19. The abrasive of claim 18, wherein the binder comprises a thermoplastic or thermoset resin. 20. The abrasive of claim 19, wherein the thermoplastic resin comprises a latex. 20. The abrasive of claim 19, wherein the thermosetting resin is selected from the group consisting of formaldehyde, phenolic, epoxy, urethane, and radiation curable resin systems. A back layer having a first surface, An abrasive layer having a plurality of abrasive particles deposited on the first surface of the backing layer and An abrasive comprising a layer substantially comprised of an inorganic filler inhibitor deposited over the abrasive layer. 23. The abrasive of claim 22, wherein the charge inhibitor is selected from the group consisting of metal silicates, silicas, metal carbonates, and metal sulfates. The abrasive according to claim 23, wherein the metal silicate is selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. 23. The filler according to claim 22, wherein the particles of the filler suppressor bind to these residue particles to inhibit agglomeration of these residue particles when the coated surface is polished using a coated abrasive to produce a worn swarf. An abrasive having a size that allows particles to be released. Attaching the plurality of abrasive particles to the first surface of the backing layer, and A method of forming an abrasive comprising the step of depositing on the abrasive particles a layer substantially comprised of a filler inhibitor selected from the group consisting of metal silicates, silica, metal carbonates and metal sulfates. 27. The method of claim 26, wherein the metal silicate is selected from the group consisting of magnesium silicate, potassium aluminum silicate, aluminum silicate and calcium silicate. The method of claim 27, wherein the magnesium silicate comprises talc. 27. The method of claim 26, further comprising forming a charge inhibitor from a material having a Mohs hardness value of less than about 7. The method of claim 26, further comprising forming a filling inhibitor from a material having an average particle size of less than about 30 μm. 27. The method of claim 26, further comprising forming an abrasive surface of the abrasive such that the filler inhibitor is primarily on the abrasive surface of the abrasive. 27. The method of claim 26, further comprising dispersing the filling inhibitor in a binder comprising a thermoplastic or thermosetting resin.