WO2021214576A1

WO2021214576A1 - Surface-modified nanoparticle additives in printable particle-containing compositions

Info

Publication number: WO2021214576A1
Application number: PCT/IB2021/052819
Authority: WO
Inventors: Wimonwan KLINKAJON; Jr. Jimmie R. Baran; Craig R. Sykora
Original assignee: 3M Innovative Properties Company
Priority date: 2020-04-21
Filing date: 2021-04-05
Publication date: 2021-10-28

Abstract

Curable compositions include a curable latex, polymeric, precision shaped-grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles. The surface-modified metal oxide nanoparticles are present at a loading of 0.1 – 5.0 weight % based on the total weight of the curable composition. The curable composition is printable at room temperature and can be used to form abrasive articles.

Description

SURFACE-MODIFIED NANOPARTICLE ADDITIVES IN PRINTABLE PARTICLE-CONTAINING COMPOSITIONS

Field of the Disclosure

The current disclosure relates to printable compositions that contain particles and include surface-modified nanoparticle additives, to abrasive articles prepared from these printable compositions, and mehods of preparring abrasive articles.

Background

The development of printing techniques has facilitated the use of printing to form a wide array of articles. For example, in the electronics industry, printing methods have been used to create electrical devices on various substrates. Such uses require the printing of larger amounts of material without losing the precise placement of material that is the hallmark of printing. The use of printing to apply materials in relatively large quantities of material in a precise and controlled way has expanded beyond the electronics industry and is being explored to form a wide range of articles.

Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. These methods are relatively low-cost processes. The selection of the printing method used is determined by requirements concerning printed layers, by the properties of printed materials as well as economic and technical considerations of the final printed products.

Printing technologies divide between sheet-based and roll-to-roll-based approaches. Sheet-based inkjet and screen printing are best for low-volume, high- precision work. Gravure, offset and flexographic printing are more common for high- volume production.

Summary

In some embodiments, the curable compositions comprise a curable latex, polymeric, precision shaped-grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles, where the curable composition is printable at room temperature. The surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition.

Also disclosed are abrasive articles. In some embodiments, the abrasive articles comprise a non-woven substrate layer with a first major surface and a second major surface, and an array of a plurality of abrasive dots. The abrasive dots comprise a dried and cured polymeric latex, polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles. The surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition used to form the abrasive dots.

Also disclosed are methods of preparing abrasive articles. In some embodiments, the method comprises providing a non-woven substrate layer with a first major surface and a second major surface, providing a curable and printable composition, printing the curable and printable composition onto the second major surface of the non-woven substrate layer in an array of dots, and drying and curing the curable and printable composition dots. The curable and printable composition has been described.

Brief Description of the Drawings

The present application may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings.

Figure 1 show TEM images of NP-3 nanoparticles (NALCO 2329K) at 6300 magnification (left side) and 8900 magnification (right side).

Figure 2 is a cumulative histogram showing the ratio of maximum diameter to minimum diameter for the dots of Example 1 and Comparative Example CE1.

Figure 3 is a cumulative histogram of the circularity of the dots for Example 1 and Comparative Example CEE]

Figure 4 shows microscope pictures for Example 1.

Figure 5 shows microscope pictures for Comparative Example CE1.

Figure 6 shows microscope pictures for the acrylic disc scratch test samples for Example 1 (left side picture) and Comparative Example CE1 (right side picture). In the following description of the illustrated embodiments, reference is made to the accompanying drawings, in which is shown by way of illustration, various embodiments in which the disclosure may be practiced. It is to be understood that the embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.

Detailed Description

The development of printing techniques has facilitated the use of printing to form a wide array of articles. For example, in the electronics industry, printing methods have been used to create electrical devices on various substrates. Such uses require the printing of larger amounts of material without losing the precise placement of material that is the hallmark of printing. The use of printing to apply materials in relatively large quantities of material in a precise and controlled way has expanded beyond the electronics industry and is being explored to form a wide range of articles. In some cases, a printable material is applied to a surface and then cured to form a structure on the surface. The structure can have a wide range of shapes such as being a dot, a pattern such as indicia, and the like.

These printing techniques requires inks, whether curable or not curable, that have specific and often contradictory properties. For example, in order to be readily printable, the ink needs to have a relatively low viscosity which is typically achieved in ink technology through the use of liquid media to dilute the solid components of the ink. However, in many articles where relatively large quantities of materials are to be delivered, the use of dilute inks is unsuitable.

The use of curable inks that have a curable liquid medium and solid particles have been developed for a wide range of applications such as electronic articles. An issue with these inks is that the particle-containing inks can be difficult to deliver by printing techniques as the particles can clump and form agglomerates that can clog printing heads and form non-uniform printed patterns. Disclosed herein are methods for preparing abrasive articles by the printing of inks containing abrasive particles onto a substrate surface. The abrasive particles are polymeric precision shaped grain mineral particles of essentially a uniform shape and size. Such particles are prepared as described in PCT Publication WO 2019/215539. It was discovered that because the polymeric precision shaped grain mineral particles are so uniform in shape and size they tend to clump together when dispersed in a liquid medium to form an ink composition. This is similar to the circumstance with clay materials, where the clay platelet particles tend to agglomerate and require deflocculation to separate the platelets and keep them separated from each other.

It was surprisingly found that inks utilizing polymeric precision shaped grain mineral particles of essentially a uniform shape and size could be prepared by incorporating surface-modified nanoparticles into the ink.

Disclosed herein are curable compositions that are capable of being printed at room temperature that include a curable latex, polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles.

Also disclosed are methods for preparing abrasive articles, where the abrasive articles comprise a non-woven substrate, and an array of abrasive dots, where the abrasive dots are dried and cured dots of the curable composition described above.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. For example, reference to "a layer" encompasses embodiments having one, two or more layers. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

The term “latex” as used herein is consistent with the common understanding in the polymeric arts and refers to a dispersion in water or an aqueous mixture of polymer particles. The latexes disclosed herein are curable materials that form a polymeric matrix upon drying and curing.

The term “(meth)acrylate” refers to monomeric acrylic or methacrylic esters of alcohols. Acrylate and methacrylate monomers or oligomers are referred to collectively herein as "(meth)acrylates”. Materials referred to as “(meth)acrylate functional” are materials that contain one or more (meth)acrylate groups.

The terms "room temperature" and "ambient temperature" are used interchangeably to mean temperatures in the range of 20°C to 25°C.

The term “adjacent” as used herein when referring to two layers means that the two layers are in proximity with one another with no intervening open space between them. They may be in direct contact with one another (e.g. laminated together) or there may be intervening layers.

The terms “polymer” and “macromolecule” are used herein consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeated subunits. As used herein, the term “macromolecule” is used to describe a group attached to a monomer that has multiple repeating units. The term “polymer” is used to describe the resultant material formed from a polymerization reaction.

The term “alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

The term “alkylene” refers to a divalent group that is a radical of an alkane. The alkylene can be straight-chained, branched, cyclic, or combinations thereof. The alkylene often has 1 to 20 carbon atoms. In some embodiments, the alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of the alkylene can be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms. The term “heteroalkylene” refers to a divalent group that includes at least two alkylene groups connected by a thio, oxy, or -NR- where R is alkyl. The heteroalkylene can be linear, branched, cyclic, substituted with alkyl groups, or combinations thereof. Some heteroalkylenes are poloxyyalkylenes where the heteroatom is oxygen such as for example,

-CH₂CH2(OCH2CH2)nOCH₂CH2-.

Disclosed herein are curable compositions. These curable compositions are capable of being printed at room temperature. By capable of being printed it means that the compositions can be printed, but the compositions do not necessarily have be printed, they can be applied in other ways such as coating methods. The terms “curable composition” and “ink” are used interchangeably.

The curable composition comprises a curable latex, polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles. The surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition.

The curable composition is thermally curable. The curable composition, upon deposition on a surface is heated to a temperature to dry and cure it. The temperature required to cure the deposited curable composition can vary, typically being in the range of 150-180°C (300-350°F).

The curable composition includes at least one latex. A latex is a dispersion in water or an aqueous mixture of a polymer particles. The latexes disclosed herein are curable materials that form a polymeric matrix upon drying and curing. A wide variety of latexes are suitable. Particularly suitable latexes include styrene-butadiene emulsion polymers and (meth)acrylate emulsion polymers. Examples of suitable latexes include the ROVENE polymers commercially available from Mallard Creek Polymers, Charlotte, NC.

A wide variety of polymeric precision shaped grain mineral particles are suitable for use in the curable compositions. These particles have been incorporated into abrasive cleaning articles that have been found to give excellent scouring properties without scratching, as described in PCT Publication No. 2019/215539. Scratching can be measured in a variety of ways such as Schieffer Scratch performance. In PCT Publication No. 2019/215539, the cleaning articles have a substrate with abrasive particles dispersed on the surface of the substrate. Among the abrasive particles are polymeric precision shaped grain mineral particles.

The polymeric precision shaped grain mineral particles were prepared according to the disclosure of US Patent No. 8,142,531 (Adefris et al.). The polymeric precision shaped grain mineral particles may be any three-dimensional shape such as, but not limited to a pyramid, cone, block, cube, sphere, cylinder, rod, triangle, hexagon, square, and the like. Typically, the organic abrasive particles are precision shaped grains that are triangular in shape.

In some embodiments, the formed abrasive particles were prepared by molding alumina sol gel in equilateral triangle-shaped polypropylene mold cavities. The draft angle between the sidewall and bottom of the mold is typically about 98 degrees. After drying and firing, the resulting formed abrasive particles have an average particle size of 50 - 1000 micrometers. In some embodiments, the average particle size of 200 - 700 micrometers.

The loading of polymeric precision shaped grain mineral particles present in the curable composition of this disclosure can vary depending upon a variety of factors. Typically, the loading of the polymeric precision shaped grain mineral particles is below 5.0 weight % based on the total weight of the curable composition. In some embodiments, the loading of the polymeric precision shaped grain mineral particles is 1.0 - 5.0 weight % based on the total weight of the curable composition.

The curable compositions of this disclosure comprise surface-modified metal oxide nanoparticles. These metal oxide nanoparticles are surface-treated nanoparticles, which means that a surface treatment agent has been applied to the metal oxide nanoparticles to at least partially modify the surface of the metal oxide nanoparticles. The surface treatments are generally adsorbed or otherwise attached to the surface of the metal oxide nanoparticles. In the present disclosure, the surface treatment agents are covalently bonded to the metal oxide nanoparticles.

As was mentioned above, it was discovered that the use of surface-modified metal oxide nanoparticles prevents the agglomeration of the polymeric precision shaped grain mineral particles in the curable compositions of this disclosure. Because the polymeric precision shaped grain mineral particles are of an essentially uniform size and shape, the particles tend to agglomerate in the absence of surface-modified metal oxide nanoparticles.

A wide variety of sizes of metal oxide nanoparticles are suitable. In general, the average particle size is less than 200 nanometers. In some embodiments, the average particle size is 1-125 nanometers.

A variety of metal oxide nanoparticles are suitable. Examples of metal oxide nanoparticles include zirconia, titania, and silica. Silica is particularly suitable metal oxide nanoparticle (silica is considered to typically classified as a metal oxide nanoparticle since silicon is classified as a metaloid). There are a variety of suppliers of silica particles including Nalco Chemical Co., Nissan Chemical Co., and WR Grace. Examples of particularly suitable silicas are those available from Nalco Chemical Co. under the trade designation "Nalco” such as “Nalco 2326”. In some embodiments, the surface-modified metal oxide nanoparticles are silane-modified silica particles.

The nanoparticles are surface treated to improve compatibility with the composition components and to keep the nanoparticles non-associated, non-agglomerated, or a combination thereof in the coatable, curable composition. The surface treatment aids the compatibility of nanoparticles with the latex composition. The surface treatment used to generate the surface-treated nanoparticles is a silane surface treatment agent. The silane surface treatment agent covalently bonds with the surface of the metal oxide particle.

Silane surface treatment agents are well known and readily available. A wide variety of silane surface treatment agents are suitable. The silane surface treatment agents are of the general structure: R^aR^bR^cSi-X where each R^a, R^b, R^c, is independently an alky or alkoxy group with the proviso that at least one of R^a, R^b, and R^c, is an alkoxy group with 1-3 carbon atoms. Many commercially available silane treatment agents have R^a, R^b, and R^c as the same alkoxy group, typically methoxy or ethoxy. The X group is typically a polyether group (an alkyl terminated heteroalkyl ene group). Examples of polyether groups include polyethylene oxide (-(O-CEh-CEh T) and polypropylene oxide (-(O-CEh- CHMe)_r-T) groups, where r is an integer of one or greater, and T is a terminal group, typically a hydrogen atom or an alkyl group. Among the suitable silane surface treatment agents is the commercially available surface treatment agent SILQUEST A-1230 (a polyether-functional silane) from Momentive Performance Materials Inc., Waterford, NY. The amount of surface-modified metal oxide nanoparticles present in the curable composition can vary but is generally a minor component in the total composition. In some embodiments, the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition.

Additionally, it has been found that not all metal oxide nanoparticles are suitable for use in the curable compositions of this disclosure. In particular, the class of materials known as “fumed silica” are not suitable for use in the curable compositions of this disclosure.

Fumed silica, also known as “pyrogenic silica” because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three- dimensional secondary particles which then agglomerate into tertiary particles. While not wishing to be bound by theory, it is believed that the agglomeration and formation of three-dimensional paticles makes fumed silica different from the surface-modified metal oxide nanoparticles of the present disclosure, and therefore fumed silica behaves differently. When fumed silica was tried in curable compositions of this disclosure, it was found that the advantages observed with the use of surface-modified metal oxide nanoparticles were not obtained.

Also disclosed are abrasive articles that are prepared from the curable compositions described above. The abrasive articles comprise a non-woven substrate layer with a first major surface and a second major surface, and an array of a plurality of abrasive dots. The abrasive dots comprise a dried and cured polymeric latex comprising polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles. The surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition that forms the abrasive dots.

The abrasive articles of the current disclosure comprise a non-woven substrate. Although the substrate primarily is described as being a nonwoven, the substrate can be other suitable materials known in the art, including, a film or a foam. In some embodiments, the substrate is a nonwoven web constituted of a network of synthetic fibers or filaments.

In some embodiments, the nonwoven web is first impregnated with a binder resin. The substrate can be impregnated with the binder resin by any means known in the art. In some embodiments, the binder resin is roll-coated onto the substrate. The coated substrate is then dried and the binder resin is cured.

The abrasive articles also comprise an array of a plurality of abrasive dots. The abrasive dots comprise a dried and cured polymeric latex comprising polymeric precision shaped grain mineral particles of essentially a uniform shape and size; and surface- modified metal oxide nanoparticles. The abrasive dots are dots of the curable compositions described above that have been deposited on the substrate surface and have then been dried and cured. The dots comprise a dried and cured latex comprising polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles.

The dried and cured latex comprises a styrene-butadiene emulsion polymer latex or a (meth)acrylate emulsion polymer latex that has been cured and dried. Suitable latexes have been described above.

The polymeric precision shaped grain mineral particles have been described above. Typically, the particles have an average particle size of 50 - 1000 micrometers. In some embodiments, the average particle size of 200 - 700 micrometers. Typically, the loading of the polymeric precision shaped grain mineral particles is below 5.0 weight % based on the total weight of the curable composition used to form the abrasive dots. In some embodiments, the loading of the polymeric precision shaped grain mineral particles is 1.0 - 5.0 weight % based on the total weight of the curable composition used to form the abrasive dots.

A wide variety of sizes of surface-modified metal oxide nanoparticles are suitable. In general, the average particle size is less than 200 nanometers. In some embodiments, the average particle size is 1-125 nanometers. In some embodiments, the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition that forms the abrasive dots. In some embodiments, the surface-modified metal oxide nanoparticles are silane-modified silica particles. Particle size can be determined in a variety of ways, including Transmission Electron Microscopy (TEM).

A wide varierty of dot sizes for the abrasive dots are suitable. Typically, the dot size is 0.50-8.0 millimeter in diameter. In some embodiments, the dots are 1.0-5.0 millimeters in diameter. Also disclosed herein are methods of preparing abrasive articles. In some embodiments, the method of preparing an abrasive article comprises providing a non- woven substrate layer with a first major surface and a second major surface, providing a curable and printable composition, printing the curable and printable composition onto the second major surface of the non-woven substrate layer in an array of dots, drying and curing the curable and printable composition dots.

Non-woven substrates are described above. The curable and printable composition has been described in detail above. In some embodiments, the curable and printable composition comprises a curable latex, polymeric precision shaped grain mineral particles of essentially a uniform shape and size, and surface-modified metal oxide nanoparticles, where the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition. The curable composition is printable at room temperature, and curable at a temperature of 150-180°C (300-350°F).

A wide variety of printing techniques are suitable. Among the suitable printing techniques are screen printing and inkjet printing. Screen printing is particularly suitable for preparing the dots of curable composition on a non-woven substrate.

The formed abrasive articles can be tested by a wide range of techniques. One particularly suitable test is the measurement of scratching. Scratching can be measured in a variety of ways such as Schieffer Scratch performance. In the Examples Section below, a comparison of the exemplary articles versus comparative articles are presented. These examples demonstrate that the use of surface-modified metal oxide nanoparticles in the curable compositions provides printed abrasive dots that have superior consistency and also give superior scratch performance.

Examples

Surface modified nanoparticles were used to improve the flow and visual appearance of polymeric based shaped abrasive particle slurries without the addition of surfactants and/or lubricants in making screen-printed articles.

These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise. The following abbreviations are used herein: nm = nanometers; pm = micrometers; kg = kilograms; cm = centimeters; g = grams; °C = degrees Centigrade; °F = degrees Fahrenheit; mm = millimeters; m/min = meters per minute; dPa.s = decipascal second.

Materials:

TEST METHODS

Transmission Electron Microscopy (TEM) measurement of modified nanoparticles equivalent diameters

Sample preparation- Both a diluted and stock (original) solution were prepared for TEM analysis. The diluted sample was prepared by sonicating the stock solution for 15 minutes and dropping 3 drops into 20 mL of distilled, deionized water using a glass pipet. From this solution, 5 pL drops were each deposited on the light side of 200M Cu/UA TEM grids using an Eppendorf pipet. These grids were stored in open tins in a desiccator to dry before imaging.

Images were acquired on a FEI Osiris TEM (FEI Company, Hillsboro, OR) operating at 200 kV. Magnifications of 2300x, 3600x, 6300x, and 8900x were used. The 2300x images did not resolve the particles well enough for accurate measurement. Image processing was performed using the NIH ImageJ software program (Public Domain). A total of 37 images were processed; 6 of the 3600x diluted sample, 21 of the 6300x diluted sample, 10 of the 8900x diluted sample, and 10 of the 8900x original sample.

The generated equivalent area can be utilized to calculate an equivalent particle diameter with the following equation: d_eq

Schiefer Scratch test This test method was used to determine/differentiate the relative scratch pattern of different mineral blends the coated nonwoven scouring materials according to disclosure of U.S. No. 5,626,512 (Palaikis et al.). The nonwoven scouring materials tested were cut into a circular pad (8.25 cm in diameter). The test was carried out using Frazier Schiefer testing machine (available from Frasier Precision Company of Gaithersburg, Maryland). The machine was set up with 6.8 kg head weight and set to stop after 1000 revolutions with water applied to the surface of the circular acrylic work piece (10.16 cm in diameter) at a rate of 40-60 drops per minute. Scratch patterns on the disc were observed and reported using the Schiefer scratch acceptance criteria in Table 1. Table 1

Optical Microscopy

An image of the printed particles for each example was capturing using an optical microscope Keyence VHX-7000 microscope with VH-ZST lens (available from Keyence, Osaka, Japan). The magnification was 200X.

Image analysis by IMAGEPRO Premier Software

Sample Preparation: A printed sample for each example was placed on a top- illuminated copy stand to be photographed by an Olympus OM-D E-Ml camera (available from Olympus America Inc., PA, USA). The camera was positioned above the example at a distance that would capture the entire printed non-woven. An image of each example was captured using automatic exposure. The images were transferred to a computer and opened with IMAGEPRO Premier software (Media Cybernetics, v. 9.4.1). The maximum and minimum diameters and the circularity were calculated and shown in histogram fig. 2 and fig. 3. Definitions of the parameters calculated by IMAGEPRO Premier

The maximum and minimum diameters are the longest and shortest diameters, respectively, that pass through the centroid of the object. The Circularity was defined as (4*Area) / ^*MaxFeret^A2), where MaxFeret was the maximum diameter that would be measured with a caliper if the adhesive dot was a free-standing 2D object.

Example preparation: The preparation of Silica nanoparticles

The nanoparticle sol was weighed into a 3 -neck round bottom flask that was equipped with an overhead mixer and a water-cooled condenser. The flask was placed in an oil bath and heated with stirring to 50°C overnight. The flask was then removed from the oil bath and allowed to cool to room temperature with stirring. A percent solids determination via drying at 150°C was determined. The modified nanoparticle sol was used without any additional workup. 20nm and 75nm modified nanoparticles were prepared the same way as 5nm but using NP-2 and NP-3 instead of using NP-1 as a reactant. (See Table 2) Table 2

TEM measurement of the NP-3 equivalent diameters was completed using image analysis routines in the NIH ImageJ software program. Each data set was taken at different random locations on the TEM grid. Mean particle size by equivalent diameter was 73.4 nm and maximum particle size measured was 123.6 nm. The representative TEM are shown in Fig. 1.

Table 3 Preparation of premix

Table 4 Example formulations (EX1-6 and CEX1)

Example Preparation

The combination of silica nanoparticles or fumed silica, and shaped abrasive particles (precursor resins) were prepared according to the formulations in Table 4 by pneumatic mixer; the viscosity of the mixers was approximately 65-85 dPa.s. The precursor resins were transferred using peristaltic pump and then printed on the non- woven substrate using a standard rotary screen-printing apparatus. The screen printer used a stencil comprising through-holes which were 2 mm in diameter. The non-woven substrate was sent through the screen printer at speed of 1.7 m/min to deposit respective precursor resins as abrasive dots on the non-woven surface. After printing, the printed non-woven was cured in the oven 280°F (138°C) first for 3 minutes and 350°F (177°C) second for 3 minutes.

Results

The formulation with silica nanoparticles demonstrated no processing issues. The formulation without silica nanoparticles (CEX1) plugged the pump, the formulation was transferred by hand. The sample with fumed silica (CEX2) also plugged the pump. Image analysis was used to calculate two parameters for the collection of abrasive dots on each printed non-woven. Cumulative histograms of these parameters have the potential to distinguish between EX1 and CEX1 For example, the ratio of the max diameter to the minimum diameter in Fig.2 is less than 2 for over 90% of the dots on the EX1, while only about 60% of the abrasive dots on the CEX1 meet that criterion. Visual appearance by Optical Microscopy

The microscope pictures of both EX1 and CEX1 clearly showed the circularity difference. The EX1 showed rounder and taller abrasive dots comparing to CEX1. Also, the full coverage of the latex resin over shaped abrasive particles could be seen in Fig. 4 and Fig. 5. This was one of the main attributes why good sample shown less scratches in Fig. 6.

Scratch Testing using acrylic disc Table 5 Results summary

*Run observation: observation during run time including mixing flow, pump transfer and roll printing

**Visual appearance: Visual appearance observation of each example by optical microscope picture; Uniform is taller and rounder abrasive dots

***Scratch rating: Schiefer scratch rating following Table 1 acceptance criteria ****Sample could not be produced due to resin mineral clumping

Claims

What is claimed is:

1. A curable composition comprising: a curable latex; polymeric, precision shaped-grain mineral particles of essentially a uniform shape and size; and surface-modified metal oxide nanoparticles, wherein the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition, and wherein the curable composition is printable at room temperature.

2. The curable composition of claim 1, wherein the polymeric precision shaped grain mineral particles have an average particle size of 50 - 1000 micrometers.

3. The curable composition of claim 1, wherein the polymeric precision shaped grain mineral particles have an average particle size of 200 - 700 micrometers.

4. The curable composition of claim 1, wherein the loading of the polymeric precision shaped grain mineral particles is below 5.0 weight % based on the total weight of the curable composition.

5. The curable composition of claim 1, wherein the loading of the polymeric precision shaped grain mineral particles is 1.0 - 5.0 weight % based on the total weight of the curable composition.

6. The curable composition of claim 1, wherein the surface-modified metal oxide nanoparticles have an average particle size of 200 nanometers or less.

7. The curable composition of claim 1, wherein the surface-modified metal oxide nanoparticles have an average particle size of 1 - 125 nanometers.

8. The curable composition of claim 1, wherein the surface-modified metal oxide nanoparticles comprise silane-modified silica nanoparticles.

9. The curable composition of claim 1, wherein the curable latex comprises a styrene- butadiene emulsion polymer or a (meth)acrylate emulsion polymer.

10. The curable composition f claim 1, wherein the composition is curable at a temperature of 150-180°C (300-350°F).

11. An abrasive article comprising: a non-woven substrate layer with a first major surface and a second major surface; and an array of a plurality of abrasive dots, wherein the abrasive dots are prepared from a curable composition and comprise: a dried and cured polymeric latex; polymeric precision shaped grain mineral particles of essentially a uniform shape and size; and surface-modified metal oxide nanoparticles, wherein the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition that forms the abrasive dots.

12. The abrasive article of claim 11, wherein the polymeric precision shaped grain mineral particles have an average particle size of 50 - 1000 micrometers.

13. The abrasive article of claim 11, wherein the polymeric precision shaped grain mineral particles have an average particle size of 200 - 700 micrometers.

14. The abrasive article of claim 11, wherein the loading of the polymeric precision shaped grain mineral particles is below 5.0 weight % based on the total weight of the curable composition that forms the abrasive dots.

15. The abrasive article of claim 11, wherein the loading of the polymeric precision shaped grain mineral particles is 1.0 - 5.0 weight % based on the total weight of the curable composition that forms the abrasive dots.

16. The abrasive article of claim 11, wherein the surface-modified metal oxide nanoparticles have an average particle size of 200 nanometers or less.

17. The abrasive article of claim 11, wherein the surface-modified metal oxide nanoparticles have an average particle size of 1 - 125 nanometers.

18. The abrasive article of claim 11, wherein the surface-modified metal oxide nanoparticles comprise silane-modified silica nanoparticles.

19. The abrasive article of claim 11, wherein the dried and cured latex comprises a styrene-butadiene emulsion polymer or a (meth)acrylate emulsion polymer.

20. A method of preparing an abrasive article comprising: providing a non-woven substrate layer with a first major surface and a second major surface; providing a curable and printable composition, wherein the curable and printable composition comprises: a curable latex; polymeric precision shaped grain mineral particles of essentially a uniform shape and size; and surface-modified metal oxide nanoparticles, wherein the surface-modified metal oxide nanoparticles are present at a loading of 0.1 - 5.0 weight % based on the total weight of the curable composition, and wherein the curable composition is printable at room temperature; printing the curable and printable composition onto the second major surface of the non- woven substrate layer in an array of dots; drying and curing the curable and printable composition dots.