JP2014196493A - Method of forming pigment pseudo-particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a pigment pseudo-particle which enables forming a pigment pseudo-particle retaining desired pigment coloring characteristics, without the inclusion of additives or spray drying, by inducing an attractive bonding force between pigment particles by using static electricity.SOLUTION: A method of forming a pigment pseudo-particle from pigment particles by polarizing pigment particles with a gas and causing the polarized pigment particles to aggregate. An apparatus 150a for forming a pigment pseudo-particle from pigment particles includes a hollow container 210 which has a cylindrical inside surface, a plurality of scoops 215 which extend inward from the cylindrical inside surface and are arranged along the length of the cylindrical inside surface in the axial direction and means of causing the pigment particles to pass through the gas.

Description

Cross-reference of related applications

  This application is a U.S. patent application filed April 7, 2003, each of which is incorporated herein by reference in its entirety for all purposes. No. 10 / 407,334, which is a continuation-in-part of U.S. Pat. Claim the benefits of 60 / 375,115.

  The invention disclosed herein generally relates to an apparatus and method for forming pigment pseudoparticles from pigment particles and pigment pseudoparticles produced therefrom. In particular, the disclosed embodiments of the invention relate to polarizing pigment particles and agglomerating polarized pigment particles to form pigment pseudoparticles.

  Titanium dioxide pigment particles, iron oxide pigment particles, pearlescent pigment particles, other metal oxide pigment particles can be added to cosmetics, detergents, paints, plastics and other products and product colors and / or desired products Often used in industries where it is desired to hide. This is usually done by intense mixing of pigment pellets and / or powders in the liquid medium to be colored. Some desirable properties for pigment pellets are the dispersibility of the pigment in the application system, ease of bulk handling, ease of metering and the amount of dust that contaminates the pigment pellets.

  In order to enhance the dispersibility in the medium to be colored, pigments are often produced, preferably in the form of finely divided powders of inorganic pigment particles. This powder is usually jet milled, sand milled, hammer milled or roller milled as a finishing step in production, contributing to dispersibility and gloss. However, pigments milled in the art generally have the disadvantages of exhibiting poor dry flow characteristics and extremely dusty. When using these powders, costly measures must be employed to reduce the harmful effects of dust (eg workplace safety, ecological concerns, product quality assurance, etc.) In this way, valuable time, money and other resources are consumed. Furthermore, pellets produced from such powders are generally difficult to handle, store, transport and introduce into the production equipment without disrupting the pellets. Thus, products that achieve good pigment dispersibility often fail to provide good pigment stability, and products that achieve good pigment stability often result in good pigment dispersibility I can't.

  Prior art methods have attempted to solve some of these problems by using chemical additives. For example, U.S. Patent No. 6,057,049 transfers a finely pulverized wax composition and a powdered pigment such that the wax absorbs the pigment and a nucleated pigment comprising a spray-quenched wax composition. A method for producing a free-flowing dust-free pigment comprising moving is described. (Patent Document 2) also describes treating particles with solid low molecular weight polymers and liquid polymer materials.

Other problems that are repeatedly experienced in handling large amounts of powder are caking, murine hole formation and bridging. Pigment stability is important for good storage and transport, and avoids aging and / or pigment aggregation into unwanted aggregates when the stored pigments are exposed to heat, humidity and pressure over time It is desirable to do. Along with the dust-related problems associated with finely divided powders, it is often desirable that pigment particles be formed into pigment pellets. However, the pigment particles are easily dispersible in the medium and the pellets are
Pigment pellets must also be formed so as not to clog, and cause pigment flow reduction and other problems.

  Solutions to some of these problems have been attempted in the prior art. For example, U.S. Pat. No. 6,089,097 is free with one or more colorants finely dispersed in an amorphous polyalphaolefin composed of at least two different monomers having a butene-1 content of at least 25% by weight. A colorant composition consisting essentially of a flowable agent is described. (Patent Document 4) is a building material comprising the incorporation of a pigment into the material in the form of granules which are free-flowing and do not form dust, which are produced from granules which have been spray-dried by post-granulation. It describes a method of coloring with inorganic pigments.

  Dispersibility is a measure of the ease with which a pigment can be uniformly and homogeneously mixed into a medium, and poor dispersibility in a medium is a mass, surface imperfection, color fringes, Can cause large agglomerates that can result in uneven coloration and / or incomplete color development. Prior art methods, for example, when dispersing pigments in coatings and / or plastic compositions, provide improved dispersibility or improved dry flow characteristics by pigment surface treatment to obtain improved performance characteristics. Have tried. For example, (Patent Document 5) describes a dispersible composition comprising an inorganic pigment or filler and a hydroxyalkylated alkylenediamine, while (Patent Document 6) describes a pigment in the presence of a nonionic dispersant in water. Describes a pigment composition prepared by milling, mixing the milled pigment dispersion with cellulose ether, and removing water from the resulting mixture.

  (Patent Document 7) describes a method for producing granules by heat tumbling granulation using an additive and a granulation aid, and (Patent Document 8) describes a concentrated pigment formulation containing pigment and ethylene oxide. Says. The pigment was also treated with wax, aqueous solution, polymer and the like. For example, (Patent Document 9) describes the formation of an aqueous slurry of a lead chromate-containing pigment dispersed in a fragile hydrocarbon resin. (Patent Document 10) also describes mixing a long-chain polyester surfactant produced by condensation and adding an essentially non-volatile liquid selected from the group consisting of mineral oil and molten wax. ing.

  Another method for producing low dust, free flowing powders is available by spray drying. These products generally exhibit poor colorability, and end users generally have low color free flow, low dust spray-dried pigments and poor flow characteristics dusty Had to choose between milled pigments. For example, U.S. Patent No. 6,057,049 describes coating a titanium oxide pigment with a hydrated oxide and sanding and drying the pigment. This results in small particle sizes that contain a high proportion of fine particles that are not directly usable pellets. This hydrophobic spray-drying post-treatment also has somewhat better flow properties but produces particles that produce exceptionally large amounts of dust.

  Other patents related to spray drying include the above-mentioned Krockert patent and (US Pat. No. 6,089,097), which describe the use of organosiloxanes. Furthermore, (Patent Document 14) describes aqueous milling, surface treatment and spray drying of inorganic pigments. (Patent Document 15) describes spray drying and agglomeration, and (Patent Document 16) forms a dispersion slurry of pigment and water, mills this slurry, and on the slurryed milled pigment. Describes that the treatment agent is deposited.

Each of the prior art methods and products lacks at least one of the desired properties of the pigment as the quality of the other properties improves. The prior art has a quality that is extremely friable, highly dispersible, and smooth discharge at the same time, can reduce the formation of bridges and rat holes, is substantially free of dust, is easy to measure, The problem of forming pigment pellets that are dense and resistant to consolidation cannot be solved.

  For example, pigment particles such as titanium dioxide generally have harmful agglomeration due to the high agglomeration of the pigment, which particles agglomerate and caking during storage during movement. However, in use, titanium dioxide forms a fine powder or dust that spreads in the air and sticks further to the surrounding area. Any reduction in dust has significant health benefits and other benefits related to the concerns of the National Institute of Occupational Health (NIOSH), the Department of Labor and / or the US Environmental Protection Agency. If these masses are incorporated into powder coating and plastic applications, there may be a loss of optical properties.

U.S. Pat. No. 4,285,984 ("Pearce") U.S. Pat. No. 4,375,520 ("Pennnie") US Pat. No. 5,604,279 (“Bernhardt”) US Pat. No. 5,199,986 (“Krockert”) U.S. Pat. No. 3,925,095 ("Bockmann") U.S. Pat. No. 4,056,402 ("Guzi") US Pat. No. 4,310,483 (“Dorfel”) US Pat. No. 4,464,203 US Pat. No. 4,127,421 (“Ferrill”) U.S. Pat. No. 4,762,523 US Pat. No. 3,660,129 (“Luginsland”) US Pat. No. 4,810,305 (“Braun”) US Pat. No. 5,035,748 (“Burrow”) US Pat. No. 5,733,365 (“Halko”) US Pat. No. 6,132,505 US Pat. No. 5,908,498 (“Kauffman”)

  To overcome the difficulties existing in the prior art, the embodiments of the invention disclosed herein utilize static electricity to induce attractive binding forces between pigment particles. The disclosed embodiments of the invention retain the desired pigmentation properties without the inclusion of additives and without the need for spray drying.

  A method for forming pigment pseudoparticles from pigment particles is disclosed herein. The method includes polarizing the pigment particles with a gas and aggregating the polarized pigment particles to form pigment pseudoparticles. In a preferred embodiment, the term “aggregates” is used herein to refer to a method of increasing particle size. Small fine particles are collected into a cluster of particles for use as the final product. Here, this cluster is preferably substantially spherical. The term “pigment pseudoparticle” is used herein to refer to a frangible cluster of pigment particles, and the pigment pseudoparticles have a greater density than an aggregate of non-aggregated pigment particles (eg, powder). Is a feature. Pigment pseudoparticles are similar to conventional pellets in that both are composed of a plurality of particles.

The pigment particles preferably comprise titanium dioxide particles. However, the pigment particles comprise any suitable particles, including, by way of non-limiting example, suitable metal oxide particles. In a preferred embodiment of the present invention, “pigment particles” are particulate in nature, non-volatile during use, and / or are commonly referred to as inert materials, fillers, extenders, and the like.

  The terms “polarize”, “polarized” and the like generally refer to a shift in magnitude and / or spatial position of a molecule (and / or particle) charge density, thereby (1) a molecule (and / or Or a more negatively charged part of the particle) and (2) a more positively charged part of the molecule (and / or particle). In a preferred embodiment, the polarized pigment particles have a sufficiently large charge shift to increase van der Waals bonds between the pigment particle molecules. In certain aspects, the polarization of the pigment particles includes inducing at least temporary dipoles in each of the pigment particles. In certain aspects, polarizing the pigment particles comprises inducing fewer molecules than all of the pigment particles. In some embodiments, the pigment particles are preferably charged by stripping electrons from the gas.

  This method preferably involves passing the pigment particles through a gas stream in a hollow vessel. In a preferred embodiment, this stream also carries away excess heat after passing between the pigment particles. Preferably, the flow characteristics are such that the flow carries away only a negligible amount of pigment particles.

  In some embodiments, aggregating polarized pigment particles to form pigment pseudoparticles deposits a portion of the polarized pigment particles on a deposit of polarized pigment particles having an inclination angle greater than the repose angle of the deposit. Comprising that. “Repose angle” refers to the maximum angle of inclination of a surface at which pigment particles placed on the surface remain in rest. In certain embodiments, the pigment particles are substantially agglomerated and each shape preferably has a diameter between about 0.1 millimeters and about 5.0 millimeters. Aggregating the pigment particles preferably comprises nucleating the pigment particles. In one aspect, impact consolidation occurs when the particles land after falling in the gas.

  In some embodiments, the pigment particles are degassed. The pigment particles are preferably agglomerated by axially rotating a hollow container having a cylindrical inner surface containing polarized pigment particles, thereby inducing repetitive avalanching of the polarized particles. In one aspect, the hollow vessel inlet feed is vibrated to degas the pigment particles. Here, the vibration is preferably of a frequency between about 60 vibrations per minute and about 20000 vibrations per minute.

  The method of forming pigment pseudoparticles from pigment particles is preferably performed at a temperature between about 0 ° C. and about 100 ° C. and under electrically insulated conditions for a time between about 0.25 minutes and about 15 minutes. Repeatedly. In some embodiments, the pigment pseudoparticles are post-treated, such as by applying a layer of chemical additive to the surface of the pigment pseudoparticles. Aspects of the invention include pigment pseudoparticles produced according to a method of forming pigment pseudoparticles from pigment particles, a paint formulation comprising pigment pseudoparticles and / or a masterbatch comprising pigment pseudoparticles. Become.

  A method for forming pigment pseudoparticles from titanium dioxide particles is also disclosed herein. This method involves passing a flow of pigment particles through a gas in a hollow container, thereby inducing electrostatic attraction between the pigment particles. This method also induces repetitive avalanche formation of polarized particles that axially rotate the hollow container as the flow occurs, thereby aggregating charged pigment particles into pigment pseudoparticles, together with electrostatic attraction. To include. This method preferably rotates the hollow vessel axially as flow occurs, thereby inducing a scoop attached to the inner surface of the hollow tube to scoop up some of the pigment particles, In the axial direction and part of it into the flow. The method also preferably comprises oscillating the inlet feed of the hollow vessel to degas the pigment particles. In one aspect, embodiments of the present invention include pigment pseudoparticles produced according to this method.

  Preferred embodiments of the present invention include pigment pseudoparticles that comprise pigment particles that are bound primarily by an induced level of intermolecular electrostatic attraction and are substantially free of dust. Other embodiments include pigment pseudoparticles consisting essentially of pigment particles that are bound together by an induced level of intermolecular electrostatic attraction. In certain embodiments, the present invention comprises pigment pseudoparticles consisting essentially of pigment particles that are bound by an induced level of intermolecular electrostatic attraction, wherein at least a portion of the surface of the pigment pseudoparticles is post-treated with a chemical. Post-processed pigment pseudoparticles.

  Preparing a tilted hollow container having a cylindrical inner surface, a high inlet and a low outlet, and extending inwardly from the cylindrical inner surface and arranged along an axial length of the tilted hollow container Also disclosed herein is a method for producing pigment pseudoparticles from pigment particles comprising providing a scoop. In a preferred embodiment, the pigment particles are disposed on a portion of the cylindrical inner surface near the inlet end and the gas stream is passed in a direction toward the lower outlet end in the inclined hollow vessel. This inclined hollow container is rotated to scoop up the pigment particles by the scoop, and the pigment particles are distributed from the scoop by axially rotating the cylindrical inner surface so that the pigment particles are polarized while being polarized by the gas. It is possible to drop towards a part of the cylindrical inner surface closer to the outlet. The inclined hollow container is also rotated axially to cause avalanche of the pigment particles, thereby aggregating the pigment particles into pigment pseudo particles.

  The present invention preferably includes an apparatus for making pigment pseudoparticles from pigment particles comprising means for polarizing the pigment particles and aggregating the polarized pigment particles into pigment pseudoparticles. The apparatus preferably also includes means for degassing the pigment particles.

  An apparatus for producing pigment pseudoparticles from pigment particles, comprising a hollow container, a plurality of scoops and blowing means is also disclosed herein. The hollow container preferably has a cylindrical inner surface, a high inlet and a low outlet, and is arranged in an inclined position with a high inlet end and a low outlet end. The plurality of scoops extend inwardly from the inner surface and are disposed along the axial length of the hollow container, and the blow-off means is directed toward the lower outlet end in the hollow container inclined to the gas flow. Used to pass through. A preferred embodiment of this device also includes a vibrating means for vibrating the hollow container, thereby degassing the pigment particles. The apparatus preferably includes means for minimizing adhesion between the cylindrical inner surface and at least one of the pigment particles and the polarized pigment particles.

  There are a number of advantages of aggregating polarized pigment particles into pigment pseudoparticles. By way of non-limiting example, these benefits include increased bulk density, reduced package size and requirements, improved flow, reduced agglomeration and caking, increased flow control, reduced dusting, uniform composition Including increased stability, consistent size and shape, ease of metering, dispersibility (even after exposure to high temperatures and high humidity during storage), consistent product performance and reduced internal and surface dust.

  These and other features and objects of the invention will be more fully understood from the following detailed description of the preferred embodiments, which should be read in light of the accompanying drawings.

  The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a flow diagram illustrating an embodiment of a method using a rotating cylindrical agglomerator. FIG. 2 is a right cross-sectional side view showing an embodiment of a rotating cylindrical aggregator. FIG. 3 is a left sectional side view showing another embodiment of the rotating cylindrical aggregator. 4a is a cross-sectional front view showing an embodiment of the rotating cylinder aggregator of FIG. 3 taken along line AA. 4b is an enlarged cross-sectional front view showing an embodiment of the rotating cylinder aggregator of FIG. 3 taken along line AA. FIG. 5a is a top view showing a paddle embodiment. FIG. 5b is a front view showing the paddle embodiment shown in FIG. 5a. FIG. 6 is a cross-sectional front view showing an embodiment of a method using a rotating cylindrical aggregator.

  In describing the preferred embodiments of the invention illustrated in the drawings, specific terminology is used for the sake of clarity. However, the present invention is not intended to be limited to the specific terms thus selected, and any specific term may function in a similar manner to achieve a similar purpose. It should be understood that it includes equivalents.

  A preferred processing unit, referred to herein as a rotating cylinder agglomerator, and generally designated 150, agglomerates powdered titanium dioxide particles in the presence of a small natural draft air stream with electrostatic charge. This rotating cylinder agglomerator is designed to make use of van der Waals attraction, preferably all the titanium dioxide particles are preferably spherical ersatz particles Aggregate.

  For a better understanding of the preferred chain of production equipment, and with reference primarily to FIG. 1, a rotating cylinder agglomerator 150 is used to illustrate an embodiment of a sample production method. An attritor 110 is used to form a powder comprising pigment particles (eg, titanium dioxide particles) which is then stored in a feed bin 120. The pigment particles can then be fed to the rotating cylinder aggregator 150 by operating a feed valve 130 that maintains the desired feed rate.

  A rotating cylindrical agglomerator 150, described in further detail below, agglomerates the fed pigment particles into large pseudo particles that are combined using van der Waals attraction. Mechanical bonds (eg, compression) and / or chemical bonds (eg, additives) can be used, but are not required. The agglomeration portion described below oscillates the feed inlet of the rotating cylindrical agglomerator 150 to degas the pigment particles. For this purpose, the compressor 140 feeds dry air to the feed inlet of the rotating cylinder agglomerator 150 and moves a vibrating mechanism that degass the pigment particles on the rotating cylinder agglomerator 150 and / or the inlet feed 205. After aggregating the pigment particles into pigment pseudo-particles, the pigment pseudo-particles are transported to the packaging container 160 where they are packaged for transport.

  Referring primarily to FIG. 2, a sample embodiment of a rotating cylinder agglomerator is shown and is generally designated 150a. Inlet feed 205 delivers pigment particles from feed container 120 at a rate controlled by feed valve 130. The rotating cylindrical agglomerator 150a comprises a hollow inclined hollow container 210 for receiving pigment particles from the inlet feed 205 and rotates along a central axis. The rotating cylindrical aggregator 150a is preferably inclined at an inclination angle α which is preferably less than 20 degrees from the horizontal. The inner surface of the hollow inclined hollow container 210 includes ledges 215. Thus, when the pigment particles are fed into the hollow inclined hollow container 210, the protrusion 215 is caused to lift up some of the pigment particles by rotation. As the hollow inclined hollow container 210 continues to rotate, the pigment particles are dispensed from the ledge as a natural result of gravity and fall through the air and land on the other pigment particles.

As shown, this bulge has a concave curvature, which increases the efficiency of scooping up the pigment particles and increases the degree of dispersion of the pigment as it is dispensed from the ledge. This air polarizes the pigment particles, and the polarized pigment particles are agglomerated by further rotating the hollow inclined hollow vessel 210 to form pigment pseudoparticles such as pigment pellets, for example. The pseudo particles exit from the outlet 220 of the hollow inclined hollow container 210.

  Referring primarily to FIGS. 3-5, another example of a rotating cylinder agglomerator is schematically labeled 150a and will be described in detail. The method of using the embodiment of the rotating cylinder aggregator 150 will be described primarily with reference to FIG.

  Referring mainly to FIG. 3, the rotating cylinder aggregator 150b preferably includes a hollow container having a cylindrical inner surface, and more preferably having a generally cylindrical shape. This hollow container is generally designated 335 and can be of unitary or modular design and of any suitable length. However, the hollow vessel 335 is preferably a module, and in this specification the processing tube 335a in the first zone, the processing tube 335b in the second zone, the processing tube 335c in the third zone, and the processing tube 335d in the fourth zone. It is shown as including a four-zone processing tube. The hollow container 335 can rotate along the central axis in the longitudinal direction. The processing tubes are preferably attached to each other by a flange 325.

  The rotating cylindrical agglomerator 150b has a feed inlet 360 and a feed cone 355 at one end for receiving pigment particles from the feed vessel 120 into the processing tube 335a in the first zone. The rotary cylindrical aggregator 150b has a discharge port 385 at the other end in order to discharge the pigment pseudo particles from the processing tube 335d in the fourth section. The hollow container 335 is preferably angled with respect to the horizontal (not shown in FIGS. 3-5). The inclination angle of the hollow container 335 is preferably equal to up to about 10 degrees, more preferably up to about 7 degrees. When inclined, the end with feed inlet 360 and feed cone 360 is higher than the end with discharge port 385. The tilt angle can be changed to facilitate the transport of pigment particles in the rotating cylinder agglomerator 150b or to increase the retention time in the rotating cylinder agglomerator 150b.

  Continuing with reference to FIG. 3, the hollow container of the rotating cylinder aggregator 150b is connected to drive means 305, preferably a variable speed gear reducer drive, thereby facilitating the rotation of the hollow container 335. The drive means 305 drives the rotation of the hollow container by the connection means 310, which is preferably a flexural drive connection. In a preferred embodiment, drive means 305 is operably connected to drive plates 315 and 320 and flange 325 to process tube 335d in the fourth zone. The rotating cylinder agglomerator 150b preferably comprises a frame 365 that supports the hollow container 335 on the trunnions 370 to facilitate the rotational movement of the hollow container. The striking instrument 330 is also attached to the hollow container 335 to generate vibration. This helps to minimize adhesion between the cylindrical inner surface and at least one of the pigment particles and polarized pigment particles. To the extent that the pigment particles stick to the cylindrical inner surface, the vibrations produced by the impact tool help to prevent the particles from sticking to the cylindrical inner surface.

Referring primarily to FIGS. 4 a and 4 b, the internal structure of the hollow container 335 preferably includes a plurality of paddles 375. Each of the paddles 375 extends inwardly from the cylindrical inner surface and is preferably grouped into sets (three sets of paddles 375 are shown in the drawings). The set of paddles 375 are arranged in a substantially helical shape along the cylindrical inner surface. The internal structure of the hollow container 335 preferably also includes a lift device 380 for operating the impact device 330. The pick-up device 380 is started by rotating the hollow container 335 and is staggered around the circumference of the hollow container 335. Thus, the striking action is continuous (as long as the rotation is continuous) and periodic (according to the spacing between the pick-up devices). The pick-up device 380 and the striking device 330 are preferably pneumatic and are compressors, preferably compressors that also operate a vibratory mechanism that feeds dry air to the feed inlet 205 of the rotating cylindrical agglomerator 150 to degas the pigment particles. Operated by dry air fed by 140 (shown in FIG. 1).

  A preferred embodiment of the paddle 375 will be described primarily with reference to FIGS. 5a and 5b. From the top view, FIG. 5 a shows that the curvature of the paddle end is related to the width w of the paddle 375 and that the radius R 1 is preferably equal to half the width w of the paddle 375. From the front view, FIG. 5b shows that the paddle length curvature is proportional to the straight line segment l from one end of the paddle 375 to the other. The radius of curvature R2 is preferably defined by measuring the distance from the farthest point of an equilateral triangle having a straight line segment l as one of the sides of the triangle. Thus, in a preferred embodiment, this radius of curvature is equal to the straight line segment l.

  The structure of any given paddle 375 is carefully designed to maximize the amount of air between the pigment particles as the paddle 375 dispenses the pigment particles. During rotation of the cylindrical inner surface (eg, during rotation of the hollow container 335), the paddle 375 scoops up the pigment particles and then as the angle of the paddle 375 increases with respect to the ground as rotation continues, Distribute. As the rotation of the hollow container 335 occurs, the angle of the paddle 375 relative to the ground increases and the pigment particles begin to fall downward from the paddle 375 due to gravity. The spoon-shaped shape of the paddle 375 takes advantage of the angle of repose associated with the pigment particles and allows a large amount of pigment particles to stay with the paddle 375 for a longer time when the angle of the paddle 375 relative to the ground changes.

  The paddle 375 and the cylindrical inner surface of the hollow container 335 are preferably made of stainless steel so as not to contaminate the pigment pseudoparticles. If iron contamination or contact is not a meaningful result, a lower grade material such as steel may be used.

  A preferred embodiment of the method using the rotating cylindrical aggregator 150b will be described mainly with reference to FIG. Pigment particles, preferably titanium dioxide, are fed into the hollow container 335 through a feed inlet 360. In a preferred embodiment, the natural draft 605 can be passed through the hollow vessel 335 at or near the feed inlet 360 and discharged by the discharge port 385. In the preferred embodiment, this ventilation is created by feeding the pigment particles into the feed inlet 360 with a flow of hot air. The pigment particles are advanced forward by the inclination of the feed cone 360 and the rotating cylinder aggregator 150.

  The pigment particles are then subjected to polarization and agglomeration within the hollow container 335, where a type of pigment particle motion is induced that is ideal for particle size increase. The pigment particles are lifted by paddle 375 and then distributed into a gas (eg, air), flowing in a cascade and coalescing. The pigment particles are preferably passed through the natural draft 605 of the air as the pigment particles flow downward in a cascade, thereby cooling and in some cases charging. Ventilation 605 has the effect of reducing the temperature of the pigment particles. In one aspect, impact consolidation occurs when the particles land after falling through the gas.

The shape of the paddle 375 facilitates the stochastic movement of the pigment particles that descend within the hollow container 335. As the pigment particles fall through the gas, the electron density of the molecules in the pigment particles shifts, creating dipoles within the molecules and within the pigment particles. The presence of a dipole in each molecule induces an increased van der Waals attraction between the pigment particles. Embodiments of the present invention do not require that the pigment particles be sprayed with a binder or other chemical. Instead, the paddle 375 embodiment is preferably designed with reference to the angle of repose of the pigment particles. The curved end of the paddle 375 has a distribution at the starting point before the pigment particles descend.
). Further, the paddle 375 is installed in a substantially spiral shape on the cylindrical inner surface of the hollow container 335 to provide a continuous and uniform falling curtain of titanium dioxide or other pigment particles while rotating axially.

  The shape of the paddle 375 increases the surface area and number of pigment particles that are directly exposed to a gas (eg, air), thereby increasing the number of pigment particles that are polarized by the gas that moves the pigment particles. This is similar to rain falling in the atmosphere and enhances the already existing natural electrostatic attraction present in titanium dioxide or other pigment particles. The polarization of the molecular charge distribution ultimately causes particle coalescence.

  Polarized pigment particles fall onto other pigment particle deposits, including polarized pigment particles and / or unpolarized pigment particles. Contact with the deposit reduces the impact and contributes to compaction of the powder. As the cylindrical inner surface rotates, the deposit climbs the side of the cylindrical inner surface and eventually falls onto itself. This avalanche formation and “snowman formation” has the effect of aggregating the polarized pigment particles to form smooth, substantially spherical pigment pseudoparticles without any compression. Rolling growth, avalanche formation and / or snowman formation are one of the aggregation mechanisms. In rolling growth agglomeration, the small particles move randomly and collide randomly in the material bed, causing them to adhere to each other due to the van der Waals attraction that the pigment particles exhibit (particularly the particles If the size is less than 1 micron). The rotating cylinder agglomerator 150 is designed for this type of agglomeration and densification method.

  The structural aspects of the pigment pseudoparticles also depend on several other factors, including the amount of degassing that affects the density of the deposit, the height imparted to the deposit, the bonding mechanism, the processing time, and the like. Particles adhering to the surface of other particles can be peeled off again or degassed, such as in a rotating cylinder agglomerator 150, to be moved elsewhere on the surface during the contact section of this process. This deposit produces high density, low porosity pigment pseudoparticles. In some embodiments, the pigment pseudoparticles continue to grow as they form the pigment pseudoparticle nuclei as they rebound to the surface and thus continue to form aggregates.

  In some embodiments, vibration is applied to the rotating cylinder agglomerator 150 to reduce particle accumulation on internal components. Particle build-up on the wall is removed and further densification is performed by a strike device 330 that is activated by rotating the lift device 380, thereby imparting vibrational energy and any initial build-up falls. As a result, the entrained air from the dry pigment is vibrated.

  The pigment pseudo particles exit from the discharge port 385 of the rotating cylindrical agglomerator 150. The quasi-particles produced are round smooth beads of +12 to +100 mesh size, preferably insubstantial hardness and macroscopically similar to table salt or granulated sugar.

  Preferred pigment pseudoparticles are characterized by the fact that the constituent pigment particles are bonded primarily by an induced level of intermolecular electrostatic attraction, and the pigment pseudoparticles are substantially free of internal dust. A preferred embodiment of this pseudoparticle comprises pigment pseudoparticles consisting essentially of pigment particles that are bound together by an induced level of intermolecular electrostatic attraction, with only a negligible amount of dust present.

This bond is preferably a van der Waals bond resulting from at least a temporary dipole-dipole condition in each pigment particle induced by the presence of an electrostatically charged gas. Van der Waals bonds usually occur when the electronic configuration of atoms in a molecule loses a symmetrical electronic configuration. This polarizes the molecule and the entire pigment particle of the molecule. More pigment particles than the naturally occurring amount are preferably polarized. As the pigment particles fall out of the gas, they can strip electrons from the gas, thereby charging the pigment particles.

  The pigment pseudoparticles are preferably smooth discharge, low dust generation, high bulk density and easy dispersibility; only a negligible amount (if any) of murine pores upon storage, bridging, There is caking or solid compaction. It is common in the art that the pigment particles that are constituents of the pigment pseudo-particles are pre-subjected to grinding (eg, attritor 110) or atomization such as by jet milling, sand milling, hammer milling, etc. Regardless of the fact that it is. Preferred embodiments of the pigment pseudo-particles include foods to be pigmented, cosmetics, detergents, paints and plastics, inks, elastomers, cements, fly ash, powdered foods, cements, cosmetics, polytetrafluoroethylene, powders, talc, clays. And other suitable media coloration.

  The pigment pseudoparticles preferably have a larger bulk density (preferably about 20% greater) and a smaller bulk volume than the pigment particles, thereby reducing packaging requirements. In this regard, large amounts of pigment can be stored in the packaging by using pigment pseudoparticles rather than powdered pigment particles, thereby reducing the cost without the dispersion problems normally associated with conventional pigment pellets. Bring about a reduction. The pigment pseudoparticles preferably have a defined shape and are particularly suitable for use with metering and feed devices.

  As mentioned above, a preferred embodiment of this pigment pseudoparticle consists essentially of pigment particles. No chemicals are required to bind the pigment particles. Thus, the final product (eg, pigment pseudoparticle) is preferably not a chemical composite or other mixture, but a characteristic hardness and low dispersibility common to chemical-bonded pigment pellet composites. Does not have. Preferred pseudoparticles are smooth, round, homogeneously agglomerated pigments with high bulk density, low dust generation, high free flowability and dispersibility. The round shape substantially increases fluidity and reduces or eliminates the generation of fine powder or dust in the process and exhibits resistance to compaction, agglomeration and aging in storage and shipping.

  Preferred pigment pseudoparticles have minimal inter-adhesion after molding primarily due to the round shape and utilization of van der Waals forces. Thus, when the preferred pigment pseudoparticles reach the final size, there is no significant attraction with other large particles. Nevertheless, the preferred pigment pseudoparticles retain the beneficial properties of extremely high brittleness and good dispersion due to the absence of mechanical and chemical bonds. Increased density also means that the pigment pseudo-particles use less volume and packaging on an equal weight basis, for example, than conventional untreated pigment.

A comparative example was attempted, and a comparative example showing an effective embodiment of the present invention is described below. The flow was determined by measuring the discharge time in seconds from a defined hole (generally 10 mm) of a cylindrical hollow container (volume 50 or 100 g) with a 60 degree conical base. The dust value was evaluated as the weight compared to the powder weight. A Heubach dust meter can be used to measure the dust characteristics of a powder or pellet. The fine dust discharged from the rotating drum where the airflow flows at a specified speed is obtained by a gravimetric method on a glass fiber filter. By measuring after different exposure times, the dust generation profile can be plotted as a function of mechanical load. The dust value is evaluated as the weight compared to the powder weight. Visual observation of dust when moving between containers is also used as a comparison. Comparison of dispersibility in the Brabender extruder and in this polymer film is consistent with the untreated code standard pigment.

Comparative Example No. 1
100 parts by weight of finely ground red iron oxide pigment was mixed with the seed pigment together with 0.5 to 1.5 parts by weight of propylene glycol. This mixture was placed in a rotating cylindrical agglomerator 150 and blended. Continued this way. Complete quasi-particle formation occurred within about 0.10-15 minutes and a smooth-ejecting product was obtained.

  The increase in bulk density of this treated pigment was about 36%. The angle of repose decreased from 55.6 degrees to 41.6 degrees, a decrease of 25%. The increase in the flow rate of the treated powder was 0.8 gram / second to 5.0 gram / second. A 48 hour compression test between 4 and 6 psi produced a fully pulverized pigment discharge upon discharge from the rotating cylinder agglomerator 150. The untreated pigment was a hard, unique mass that did not break when discharged. The resulting reduction in dust was about 60%.

Comparative Example No. 2
100 parts by weight of finely ground black iron oxide pigment was mixed with the seed pigment along with 0.5-1 part by weight of polydimethylsiloxane, 320 cs. This mixture was blended in a rotating cylindrical agglomerator 150. Continued this way. Complete pseudoparticle formation was completed within about 0.25 to 15 minutes, and a smooth discharge product was obtained.

  The increase in bulk density of this treated pigment was about 29%. The angle of repose decreased from 55.6 degrees to 38 degrees, a decrease of 32%. The increase in the flow rate of the treated powder was from 0.8 gram / second to 5.0 gram / second. A 48 hour compression test between 4 and 6 psi resulted in a fully ground pigment discharge upon discharge from the rotating cylinder agglomerator 150. The untreated pigment was a hard, unique mass that did not break when discharged. The resulting dust reduction was about 55%.

Comparative Example No. 3
100 parts by weight of universal grade rutile titanium dioxide was blended at a temperature in a rotary cylinder agglomerator 150. Continued this way. Complete pseudoparticle formation was completed within about 0.25 to 15 minutes, and a smooth discharge product was obtained.

  The increase in bulk density of this treated pigment was about 15%. The angle of repose decreased from 52 degrees to 38.6 degrees, a decrease of about 26%. The increase in the flow rate of the treated powder was from 1.6 grams / second to 6.2 grams / second. A 48 hour compression test between 4 and 5 psi resulted in a fully ground pigment discharge upon discharge from the rotating cylinder agglomerator 150. The untreated pigment was a hard, unique mass that did not break when discharged. The resulting dust reduction was about 70% and the paint dispersibility comparison on the Hegman scale was consistent with the untreated code standard pigment.

Comparative Example No. 4
100 parts by weight of hydrophobic plastic grade rutile titanium dioxide was blended at a temperature in a rotary cylinder agglomerator 150. Continued this way. Complete pseudoparticle formation was completed within about 0.1 to 15 minutes and a smooth discharge product was obtained.

  The increase in bulk density of this treated pigment was about 16%. The angle of repose decreased from 50.5 degrees to 38.3 degrees, a decrease of about 27%. The increase in the flow rate of the treated powder was 1.9 grams / second to 8.3 grams / second. A 48 hour compression test between 4 and 5 psi resulted in a fully ground pigment discharge upon discharge from the rotating cylinder agglomerator 150. The untreated pigment was a hard, unique mass that did not break when discharged. The resulting reduction in dust was about 80%.

According to a preferred embodiment of the present invention, the smooth discharge pigment pseudo-particles are composed of spherical pseudo-particles, which preferably are at least about 90% by weight pigment particles and up to 99.9 +% by weight pigment particles. It is. This pseudoparticle is preferably used for pigmentation of aqueous and / or non-aqueous systems, where the requirements are low dust, good material flow and accurate metering or feedability.

  Titanium dioxide particles are the preferred pigment particles. Titanium dioxide particles that can be processed by the described method to yield pseudo-particles are examples and include, but are not limited to, any white or suitable for surface coatings (eg, paints) and / or the plastics industry. Also included are pigmented, hiding or non-hiding particulate pigments (or mineral pigments). The titanium dioxide pigment used in the method of the present invention can be either anatase or rutile crystal structure or a combination thereof. This pigment is familiar to those skilled in the art, but can be made by known commercial methods that do not form any part of the present invention. Either the well-known sulfate process or the well-known vapor phase oxidation process of titanium tetrachloride can produce specific pigments.

  Titanium dioxide particles are particularly desirable due to the fact that the molecules are particularly cohesive due to the high electrostatic charge, the bipolar tendency of the particles and the high van der Waals forces present due to the very small particle size. These titanium dioxide particles can include crystal forms of anatase and rutile. In addition to using titanium dioxide particles, other pigment particles, preferably other inorganic oxide pigments such as alumina, magnesia and zirconia can also be used. In some embodiments, the pigment particles preferably have an average diameter of less than about 1 micron, and in some embodiments, the pigment particles and / or seed particles have an average particle size of about 0.01 to about 5.0 microns. Have. In some embodiments, the pseudoparticles are spherical aggregates, preferably about 0.01 millimeters in diameter, and in other embodiments, the pseudoparticles are preferably from about 0.1 millimeters to about 4 millimeters. Diameter.

  The rotating cylinder agglomerator 150 includes titanium dioxide particles and, as non-limiting examples, white basic lead carbonate, white basic lead sulfate, white basic lead silicate, zinc sulfide, zinc oxide, zinc sulfide and barium sulfate. Composite pigments, white hiding pigments such as antimony oxide, white extender pigments such as calcium carbonate, calcium sulfate, porcelain clay, mica, diatomaceous earth, and iron oxide, lead oxide, cadmium sulfide, cadmium selenide, lead chromate, chromic acid Specially designed and optimized for continuous processing of other pigment particles including colored pigments such as zinc, nickel titanate, chromium oxide.

  In some embodiments, the pigment particles can be treated or coated by adding a standard surface treatment to the pigment pseudoparticles. In some embodiments, the surface of the pseudoparticle is post-treated with, for example, one or more metal oxides or hydroxides. This includes, as non-limiting examples, aluminum, antimony, beryllium, cerium, hafnium, lead, magnesium, niobium, silicon, tantalum, titanium, tin, zinc and / or zirconium. The titania or other inorganic oxide pigment may be any suitable, including co-oxidation of titanium (or other metal) and aluminum halides as in the chloride method, or addition of an aluminum compound prior to calcination in the sulfate method. It can contain the aluminum introduced also by a simple method.

  For purposes of illustrating the manner in which the present invention can be used to advantage, an apparatus and method for forming pigment pseudoparticles according to the present invention has been described hereinabove, although the present invention is not limited thereto. Should be recognized. Accordingly, any and all modifications, variations, or equivalent arrangements that may occur to those skilled in the art are within the scope of the present invention as defined in the appended claims. Should be considered.

Claims (29)

Providing a hollow container having a cylindrical inner surface and containing pigment particles;
A plurality of paddles extending inward from the cylindrical inner surface, each provided with a paddle having a recess;
Passing a gas stream through the cylindrical inner surface;
Rotating the cylindrical inner surface in an axial direction, thereby causing a plurality of paddles to pick up some pigment particles;
Axial rotation of the cylindrical inner surface, whereby a plurality of paddles distribute pigment particles, so that the distributed particles are polarized by the gas and land on the pigment particle deposit,
From the pigment particles comprising inducing a repetitive avalanche formation of the polarized pigment particles, wherein the cylindrical inner surface is axially rotated thereby aggregating the polarized pigment particles into electrostatically bound pigment pseudoparticles A method of forming pigment pseudo-particles.   The method of claim 1, wherein providing a plurality of paddles comprises providing a plurality of paddles disposed along a cylindrical inner surface in a substantially helical shape.   The method of claim 1, comprising vibrating the inlet feed of the hollow vessel to degas the pigment particles.   Pigment pseudoparticles produced according to the method of claim 1. Providing an inclined hollow container having a cylindrical inner surface, a high inlet and a low outlet;
A plurality of paddles extending inwardly from the inner cylindrical inner surface and arranged in a substantially helical shape along the axial length of the inclined hollow container, each having a recess Providing paddles;
Introducing pigment particles into an inclined hollow container at the high inlet;
Passing a flow of gas in an inclined hollow container in a direction towards the lower outlet;
Lifting pigment particles by paddles by axially rotating the cylindrical inner surface;
Axial rotation of the cylindrical inner surface distributes the pigment particles from the paddle so that the pigment particles fall through the flow towards a portion of the cylindrical inner surface close to the outlet while being polarized by the gas And a method of forming pigment pseudoparticles from pigment particles comprising nucleating polarized pigment particles into pigment pseudoparticles by axially rotating a cylindrical inner surface.   Pigment pseudoparticles produced according to the method of claim 5. A hollow container comprising a cylindrical inner surface, an inlet end and an outlet end, and arranged to be inclined with a high inlet end and a low outlet end;
A pigment pseudoparticle from a pigment particle comprising: a gas in a hollow container; and a plurality of scoops extending inwardly from the cylindrical inner surface and disposed along an axial length of the cylindrical inner surface Forming device.   The apparatus according to claim 7, comprising a ventilation of air in which the gas flows in a direction from the inlet end toward the outlet end.   8. An apparatus according to claim 7, comprising vibration means for degassing the pigment particles. A hollow container adapted to be axially rotated and having a cylindrical inner surface for containing pigment particles;
A plurality of paddles, each comprising a mounting end attached to the cylindrical inner surface, a distal dispensing instrument end at the mounting end and a paddle line segment between the mounting end and the dispensing instrument end; A plurality of paddles having a concave curvature with an axial facing;
An apparatus for inducing electrostatic coupling and aggregation of pigment particles comprising: a gas in the hollow container; and means for driving rotation of the hollow container.   11. The apparatus of claim 10, wherein the attachment end is at least one of attached directly to the cylindrical inner surface and attached to the cylindrical inner surface by an intermediate piece.   11. The device according to claim 10, wherein the hollow cylindrical hollow container is a module.   11. Apparatus according to claim 10, comprising means for supporting the hollow container during rotation.   The apparatus of claim 10, wherein the means for supporting the hollow container comprises a trunnion.   The apparatus of claim 10, wherein each of the plurality of paddles is spoon-shaped.   The apparatus of claim 10, wherein the curvature radius of the line segment is substantially equal to a linear distance measured from the mounting end to the dispensing instrument end.   17. The apparatus of claim 16, wherein the dispensing instrument end comprises a convex curve having a radius of curvature substantially equal to half the width of the line segment.   11. Apparatus according to claim 10, comprising means for degassing the pigment particles.   12. The apparatus of claim 10, comprising means for minimizing adhesion between the cylindrical inner surface and at least one of the pigment particles and polarized pigment particles.   20. The apparatus of claim 19, wherein the means for minimizing adhesion comprises a strike device adapted to strike the hollow container, thereby causing the hollow container to vibrate.   21. The apparatus of claim 20, comprising means for periodically actuating the strike instrument in conjunction with rotation of the hollow container.   The apparatus of claim 10, wherein the hollow ramp is disposed at an angle relative to the ground.   The apparatus of claim 10, comprising an inlet for receiving pigment particles and an outlet for discharging aggregated pigment particles.   24. The apparatus of claim 23, wherein the hollow ramp is disposed at an angle with respect to the ground and the inlet is higher than the outlet.   25. The apparatus of claim 24, wherein the angle is about 20 degrees or less.   25. The apparatus of claim 24, wherein the angle is greater than about 0 degrees and the angle is less than about 10 degrees. The apparatus of claim 10, wherein the mounting ends of the plurality of paddles are arranged in a substantially helical shape along the cylindrical inner surface.   The apparatus of claim 10, wherein the plurality of paddles comprises at least one set of paddles, and the mounting end of each paddle in the set is disposed in a substantially helical form along the cylindrical inner surface.   The plurality of paddles comprises a first set of paddles, a second set of paddles, and a third set of paddles, wherein the mounting end of each paddle of the first set is a first along the cylindrical inner surface Arranged in a substantially helical form, the mounting end of each second set of paddles being arranged in a second substantially helical form along the cylindrical inner surface, and of each third set of paddles The apparatus of claim 10, wherein the attachment end is disposed in a third substantially helical shape along the cylindrical inner surface.

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