Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/0004—Preparation of sols
  • B01J13/0047—Preparation of sols containing a metal oxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G23/00—Compounds of titanium
  • C01G23/04—Oxides; Hydroxides

Definitions

• the present invention is directed to methods of making colloidal metal oxide particles.
• the present invention provides new methods of forming colloidal metal oxide particles.
• the disclosed methods of forming colloidal metal oxide particles enable the formation of colloidal metal oxide particles under near optimum process conditions so as to form the colloidal metal oxide particles in a very efficient manner. Further, the disclosed methods of forming colloidal metal oxide particles enable optimum utilization of reaction vessels due to decreased reaction periods needed to form colloidal metal oxide particles.
• the disclosed methods of forming colloidal metal oxide particles comprise a step of adding one or more reactants to a reaction vessel, wherein the step of adding one or more reactants takes into account various in situ reaction conditions including, but not limited to, at least one of (i) a particle nucleation rate within a reaction vessel, (ii) a metal oxide deposition rate onto existing metal oxide particles (e.g., seed metal oxide particles and/or nucleated metal oxide particles) within the reaction vessel, and/or (iii) growth of metal oxide particles (e.g., seed metal oxide particles and/or nucleated metal oxide particles) within the reaction vessel.
• a particle nucleation rate within a reaction vessel e.g., seed metal oxide particles and/or nucleated metal oxide particles
• a metal oxide deposition rate onto existing metal oxide particles e.g., seed metal oxide particles and/or nucleated metal oxide particles
• growth of metal oxide particles e.g., seed metal oxide particles and/or nucleated metal oxide particles
• a method of making colloidal metal oxide particles comprises the step of adding reactive metal oxide to a reaction vessel at a metal oxide mass addition rate that is based on a mathematical model that takes into account at least one of (i) a particle nucleation rate, (ii) a metal oxide deposition rate onto existing metal oxide particles, and/or (iii) growth of metal oxide particles in the reaction vessel, wherein the metal oxide mass addition rate increases as a function of reaction time.
• the addition rate is greater than 10.0 grams of reactive metal oxide per 1000 square meters (m 2 ) of total particle surface area per hour (g/1000 m 2 -hr) during at least a portion of a reaction period.
• m 0 represents a mass of metal oxide particles in the reaction vessel as measured in grams (g);
• Gr represents a metal oxide particle growth rate of the metal oxide particles in the reaction vessel as determined by an increase in particle diameter and as measured in nanometers per hour (nm/hr);
• Dp 0 represents an average metal oxide particle diameter as measured in nanometers (nm).
• the disclosed methods of making colloidal metal oxide particles may comprise a step of forming nucleated metal oxide particles and/or a step of growing metal oxide seed particles.
• the method of making colloidal metal oxide particles comprises the step of adding one or more reactants to a reaction vessel (i) containing water and (ii) being substantially free of any seed metal oxide particles, wherein the one or more reactants are capable of forming nucleated metal oxide particles; forming nucleated metal oxide particles within the reaction vessel; and growing the nucleated metal oxide particles within the reaction vessel so as to form colloidal metal oxide particles, wherein the growing step comprises increasing a feed rate of the one or more reactants over a reaction period.
• the disclosed methods of making colloidal metal oxide particles enable the production of colloidal metal oxide particles in an energy efficient manner with a reaction period significantly less than conventional reaction periods for forming colloidal metal oxide particles.
• the method of making colloidal metal oxide particles comprises the step of adding reactive metal oxide to a reaction vessel at a metal oxide mass addition rate over a reaction period so as to form colloidal metal oxide particles having an average final particle diameter ranging from about 10 nm to about 200 nm, wherein the reaction period is as much as 50% shorter than a similar reaction period using conventional techniques (e.g., a constant reactive metal oxide feed rate).
• colloidal metal oxide particles having an average particle diameter in the range of 20-30 nm may be formed in a reaction period of about 21 -28 minutes, while conventional methods of forming similarly sized colloidal metal oxide particles require reaction periods of at least 30 minutes, typically, from about 31 to 40 minutes.
• the method of making colloidal metal oxide particles comprises the step of adding reactive metal oxide to a reaction vessel at a metal oxide mass addition rate over a reaction period so as to form colloidal metal oxide particles having an average final particle diameter ranges from about 20 nm to about 200 nm, the metal oxide mass addition rate increasing at least once during the reaction period.
• the increase in the metal oxide mass addition rate may, for example, be a single step increase or multiple step increases.
• the present invention is further directed to methods of using colloidal metal oxide particles.
• the method comprises applying a colloidal metal oxide particle composition onto a substrate; and drying the colloidal metal oxide particle composition so as to form a coating on the substrate.
• FIG. 1 graphically depicts (i) nucleation rate of reactive metal oxide and (ii) deposition rate of reactive metal oxide onto existing particles as the concentration of reactive metal oxide changes;
• FIG. 2 graphically depicts conditions that favor (i) deposition rate of reactive metal oxide onto existing particles, (ii) nucleation of new colloidal metal oxide particles and (iii) both (i) and (ii) as the concentration of reactive metal oxide changes;
• FIG. 3 graphically depicts the reduction in reaction time needed to form colloidal metal oxide particles having an average particle diameter of 22 nm using (i) the optimized reactive metal oxide feed rate of the present invention and (ii) a constant reactive metal oxide feed rate used in conventional processes;
• FIG. 4 graphically depicts step-wise addition of reactive metal oxide using optimized methods of the present invention so as to closely follow an optimal feed rate
• FIG. 5 graphically depicts particle size and surface area of colloidal silica particles formed via the optimized methods of the present invention versus colloidal silica particles formed via conventional methods (i.e., a constant reactive silica feed rate).
• an oxide includes a plurality of such oxides and reference to “oxide” includes reference to one or more oxides and equivalents thereof known to those skilled in the art, and so forth.
• metal oxides is defined as binary oxygen compounds where the metal is the cation and the oxide is the anion.
• the metals may also include metalloids.
• Metals include those elements on the left of the diagonal line drawn from boron to polonium on the periodic table.
• Metalloids or semi-metals include those elements that are on this line. Examples of metal oxides include silica, alumina, titania, zirconia, etc., and mixtures thereof.
• the present invention is directed to methods of making colloidal metal oxide particles.
• the present invention is further directed to colloidal metal oxide particles, compositions comprising colloidal metal oxide particles, as well as methods of using colloidal metal oxide particles.
• a description of exemplary colloidal metal oxide particles, methods of making colloidal metal oxide particles, and methods of using colloidal metal oxide particles is provided below. /. Methods of Making Colloidal Metal Oxide Particles
• the present invention is directed to methods of making colloidal metal oxide particles.
• Raw materials used to form the colloidal metal oxide particles of the present invention, as well as method steps for forming the colloidal metal oxide particles of the present invention are discussed below.
• the disclosed methods of making colloidal metal oxide particles may utilize one or more of the following raw materials for making colloidal silica particles, but alternative raw materials may be utilized to form other types of colloidal metal oxide materials, such as colloidal alumina particles, colloidal titania particles, colloidal zirconia particles, etc., and combinations thereof.
• the methods of making colloidal silica particles may utilize one or more silicon-containing raw materials.
• Suitable silicon-containing raw materials include, but are not limited to, silicates such as alkali metal silicates. Desirably, one or more alkali metal silicates are used to form colloidal silica particles.
• Suitable alkali metal silicates include, but are not limited to, sodium silicate, potassium silicate, calcium silicate, lithium silicate, magnesium silicate, and combinations thereof.
• Suitable commercially available silicates include, but are not limited to, sodium and potassium silicates commercially available from a number of sources including PQ Corporation (Valley Forge, PA) and Zaclon, Inc. (Cleveland, OH).
• Any single silicate or combination of silicates may be reacted with one or more cation exchange resins to form colloidal silica particles in the disclosed methods.
• Suitable cation exchange resins for use in the present invention include, but are not limited to, strong acid cation (SAC) resins, weak acid cation (WAC) resins, and combinations thereof.
• Suitable commercially available cation exchange resins include, but are not limited to, cation exchange resins commercially available from a number of sources including Purolite Corporation (BaIa Cynwyd, PA) such as those sold under the PUROLITE ® trade designation, and Dow Chemical (Midland, Ml) such as those sold under the DOWEX ® trade designation.
• one or more cation exchange resins are added to a reaction vessel at a resin addition rate so as to maintain the pH of the reaction vessel between about 8.0 and about 10.0, desirably, between about 9.2 and about 9.6.
• seed metal oxide particles are utilized as a starting raw material.
• seed colloidal metal oxide particles from a number of suppliers may be used.
• Suitable seed colloidal metal oxide particles for use in the present invention include, but are not limited to, seed colloidal metal oxide particles, such as colloidal silica particles commercially available from Nissan Chemical America Corporation (Houston, TX) and Eka Chemicals, Inc. (Marietta, GA).
• colloidal metal oxide particles comprise a number of steps as discussed below.
• the disclosed methods of making colloidal metal oxide particles enable the production of colloidal metal oxide particles in an energy efficient manner with a reaction period significantly less than conventional reaction periods for forming colloidal metal oxide particles.
• the method of making colloidal metal oxide particles comprises the step of adding one or more reactants to a reaction vessel (i) containing water and (ii) being substantially free of any seed metal oxide particles, wherein the one or more reactants are capable of forming nucleated metal oxide particles.
• the step of preparing a reaction vessel simply comprises adding a desired amount of deionized (Dl) water to the reaction vessel.
• the method of making colloidal metal oxide particles comprises the step of adding one or more reactants to a reaction vessel containing (i) deionized (Dl) water and (ii) seed metal oxide particles, wherein the one or more reactants are capable of forming nucleated metal oxide particles and/or growing the seed metal oxide particles.
• the step of preparing a reaction vessel comprises adding (i) a desired amount of deionized (Dl) water and (ii) a desired amount of seed metal oxide particles to the reaction vessel.
• the seed metal oxide particles typically have an initial average particle size (i.e., largest dimension) ranging from about 5 nm to about 15 nm.
• the disclosed methods of forming colloidal metal oxide particles comprise a step of adding one or more of the above-described reactants to a reaction vessel, wherein the step of adding the one or more reactants takes into account various in situ reaction conditions including, but not limited to, at least one of (i) a particle nucleation rate within the reaction vessel, (ii) a metal oxide deposition rate onto existing metal oxide particles (e.g., seed metal oxide particles and/or nucleated metal oxide particles) within the reaction vessel, and/or (iii) growth of metal oxide particles (e.g., seed metal oxide particles and/or nucleated metal oxide particles) within the reaction vessel.
• a particle nucleation rate within the reaction vessel
• a metal oxide deposition rate onto existing metal oxide particles e.g., seed metal oxide particles and/or nucleated metal oxide particles
• growth of metal oxide particles e.g., seed metal oxide particles and/or nucleated metal oxide particles
• a method of making colloidal metal oxide particles comprises the step of adding reactive metal oxide to a reaction vessel at a metal oxide mass addition rate that is based on a mathematical model that takes into account at least one of (i) a particle nucleation rate, (ii) a metal oxide deposition rate onto existing metal oxide particles, and/or (iii) growth of metal oxide particles in the reaction vessel, wherein the metal oxide mass addition rate increases as a function of reaction time.
• m 0 represents a mass of metal oxide particles in the reaction vessel as measured in grams (g);
• Gr represents a metal oxide particle growth rate of the metal oxide particles in the reaction vessel as determined by an increase in particle diameter and as measured in nanometers per hour (nm/hr);
• Dp 0 represents an average metal oxide particle diameter as measured in nanometers (nm); and (d) t represents time in hours (hr).
• G r ranges from about 10 to about 50 nm/hr, and q ranges from about 10.6 to about 52.8 g/1000 m 2 -hr during at least a portion of the reaction period. In other embodiments, G r ranges from about 20 to about 40 nm/hr, and q ranges from about 21.1 to about 42.3 g/1000 m 2 -hr during at least a portion of the reaction period.
• FIG. 1 graphically depicts a plot of (i) nucleation rate, R N , of reactive metal oxide and (ii) deposition rate, D R) of reactive metal oxide onto existing particles as the concentration of reactive metal oxide changes.
• nucleation does not take place until (i) the concentration of reactive metal oxide exceeds a concentration at saturation, C 8 , and (ii) reaches a critical level of supersaturation identified as C c .
• C c concentration at saturation
• nucleation proceeds at an exponential rate, while the deposition rate continues along a linear path as the concentration of reactive metal oxide increases.
• FIG. 2 graphically depicts process conditions that favor (i) deposition rate of reactive metal oxide onto existing particles (i.e., at concentrations of reactive metal oxide less than C c ), (ii) nucleation of new colloidal metal oxide particles (i.e., at concentrations of reactive metal oxide above C c ) and (iii) both (i) and (ii) (i.e., at concentrations of reactive metal oxide above C c and below a concentration C N shown in FIG. 2) as the concentration of reactive metal oxide increases.
• concentration of reactive metal oxide increases above CN shown in FIG. 2
• process conditions significantly favor nucleation of new metal oxide particles over deposition of metal oxide onto existing particles.
• a filtering step (e.g., an ultrafiltration step) may be employed to remove unwanted salts resulting from the reaction of one or more cation exchange resins with one or more metal oxide raw materials.
• the disclosed methods of making colloidal metal oxide particles enable the production of colloidal metal oxide particles while optimizing the utilization of reactor time and energy.
• the method of making colloidal metal oxide particles enables the production of colloidal metal oxide particles having an average final particle diameter ranging from about 30 nm to about 200 nm in a reaction period that represents a 50% reduction in reaction period needed for making the same colloidal metal oxide particles using conventional methods.
• FIG. 3 graphically depicts the reduction in reaction time needed to form colloidal silica particles having an average particle diameter of 22 nm using (i) the optimized reactive silica feed rate of the present invention, and (ii) a constant reactive silica feed rate used in conventional processes.
• FIG. 4 graphically depicts step-wise addition of reactive silica using optimized methods of the present invention so as to closely follow an optimal feed rate.
• the disclosed methods of making colloidal silica particles may comprise one or more stepwise increases in the reactive silica feed rate during a given reaction period. Although only two-step or three-step methods are shown in FIG. 4, any number of step increases in the reactive silica feed, rate may be used in the present invention to closely follow an optimal feed rate depicted by the "optimal" line shown in FIG. 4.
• colloidal metal oxide particles formed in the above-described methods of the present invention have a physical structure and properties similar to colloidal metal oxide particles formed in conventional methods of forming colloidal metal oxide particles as described below.
• the colloidal metal oxide particles of the present invention have a spherical particle shape with an average largest particle dimension (i.e., a largest diameter dimension).
• the colloidal metal oxide particles of the present invention have an average largest particle dimension of less than about 700 ⁇ m, more typically, less than about 100 ⁇ m.
• the colloidal metal oxide particles have an average largest particle dimension of from about 10.0 to about 100 ⁇ m, more desirably, from about 10.0 to about 30 ⁇ m.
• the colloidal metal oxide particles of the present invention typically have an aspect ratio of less than about 1.4 as measured, for example, using Transmission Electron Microscopy (TEM) techniques.
• TEM Transmission Electron Microscopy
• the term "aspect ratio" is used to describe the ratio between (i) the average largest particle dimension of the colloidal metal oxide particles and (ii) the average largest cross- sectional particle dimension of the colloidal metal oxide particles, wherein the cross- sectional particle dimension is substantially perpendicular to the largest particle dimension of the colloidal metal oxide particle.
• the colloidal metal oxide particles have an aspect ratio of less than about 1.3 (or less than about 1.2, or less than about 1.1 , or less than about 1.05).
• the colloidal metal oxide particles have an aspect ratio of from about 1.0 to about 1.2.
• the colloidal metal oxide particles of the present invention have an average surface area similar to colloidal metal oxide particles formed from conventional methods. Typically, the colloidal metal oxide particles of the present invention have an average surface area ranging from about 90 m 2 /g to about 180 m 2 /g. Desirably, the colloidal metal oxide particles of the present invention have an average surface area ranging from about 100 m 2 /g to about 160 m 2 /g, more desirably, from about 110 m 2 /g to about 150 m 2 /g.
• FIG. 5 graphically compares colloidal metal oxide particles, in this case colloidal silica particles, formed by the optimized process of the present invention with colloidal silica particles formed from conventional methods (i.e., a non-optimized process, namely, a constant metal oxide raw material feed rate).
• colloidal silica particles formed from conventional methods had an average particle size of about 27.6 nm and an average particle surface area of about 136 m 2 /g
• colloidal silica particles formed by the optimized process of the present invention had an average particle size of about 28.7 nm and an average particle surface area of about 142 m 2 /g.
• colloidal metal oxide (e.g., silica) particles formed by the optimized process of the present invention can produce substantially similar colloidal metal oxide particles as formed from conventional methods.
• the colloidal metal oxide particles formed by the optimized process of the present invention can be produced in a much more efficient manner utilizing up to 50% less reactor time and process energy.
• the present invention is further directed to methods of using the colloidal metal oxide particles formed in the above-described methods.
• the method comprises applying a colloidal metal oxide particle composition onto a substrate; and drying the colloidal metal oxide particle composition so as to form a coating on the substrate.
• Suitable substrates include, but are not limited to, paper, polymeric film, polymeric foam, glass, metal, ceramics, and fabrics.
• the method of using colloidal metal oxide particles comprises utilizing the colloidal metal oxide particles as an abrasive/polishing composition for micro-electronics or other articles. In other exemplary embodiments, the method of using colloidal metal oxide particles comprises utilizing the colloidal metal oxide particles as an additive in paints to improve the mechanical properties of a dried paint film.
• Sodium silicate (29 wt% SiO 2 , 9 wt% Na 2 O) and a strong acid ion-exchange resin were then simultaneously added to the vessel at an initial silicate addition rate equivalent to 167.8 grams (g) SiO 2 /min (0.37 Ib SiO 2 /min). After 10 minutes, the silicate addition rate was increased to 317.5 g SiO 2 /min (0.70 Ib SiO 2 /min) and maintained at this higher rate for an additional 11 minutes. [0053] Throughout the process, the resin addition rate was controlled to maintain the pH of the vessel between 9.2 and 9.6. After 21 minutes of silicate addition, both additions were stopped and the reaction quenched by the addition of Dl water.
• Example 1 The procedure in Example 1 was repeated except the silicate addition rate equivalent to 167.8 grams (g) Si ⁇ 2 /min (0.37 Ib SiO 2 /min) was maintained throughout the process. The resin addition rate was controlled to maintain the pH of the vessel between 9.2 and 9.6. This process was continued for 31 minutes after which additions of silicate and ion-exchange resin were stopped and the growth reaction was quenched by addition of Dl water.
• the resulting product was determined to have a particle size of 22+2 nm.
• R L R L + k(Ru -RL), where k is a variable ranging from 1% to 100% with a 1% increment, e.g., k is 1 %, 2%, 3%, 4%, 5%. ... 50%, 51%, 52%. ... 95%, 96%, 97%, 98%, 99%, or 100%.
• any numerical range represented by any two values of R, as calculated above is also specifically disclosed.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Silicon Compounds (AREA)
• Colloid Chemistry (AREA)
• Oxygen, Ozone, And Oxides In General (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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