Method for preparing special effect pigments using emulsions

Abstract

A method of making pigments, such as special effect pigments, includes forming a first slurry comprising a substrate, a polymer precursor, and a free radical initiator; forming a solution comprising an emulsifier; and combining the first slurry and the solution such that the substrate is encapsulated by a first coating. Special effect pigments formed by the method are also disclosed.

Description

[0001] This case is a divisional application of the patent application filed on April 7, 2020, with application number 2020800279579 and invention title "Method for preparing special effect pigments using emulsion". Technical Field

[0002] This disclosure relates in its entirety to pigments, such as special effects pigments. A method for preparing a pigment, such as a special effects pigment, includes forming a first slurry comprising a substrate, a polymer precursor, and a free radical initiator; forming a solution comprising an emulsifier; and combining the first slurry and the solution such that the substrate is encapsulated by a first coating. Background Technology

[0003] The preparation of special effects pigments generally requires complex vacuum processes, time-consuming step-by-step coating, and expensive post-treatments such as stripping and grinding. The complexity of preparing special effects pigments greatly limits the production volume and requires significant investment in equipment and processes.

[0004] For example, in special effects pigments with organic coatings, reflective flakes are covered by colored coatings on two opposing surfaces. Therefore, a step-by-step process is employed, requiring vacuum deposition of the metallic reflective layer. Summary of the Invention

[0005] In one aspect, a method for preparing a pigment is disclosed, comprising forming a first slurry comprising a substrate, a polymer precursor and a free radical initiator; forming a solution comprising an emulsifier; and combining the first slurry and the solution such that the substrate is encapsulated by a first coating.

[0006] Additional features and advantages of the various implementation schemes will be set forth in part in the following description, and will become apparent in part from the description, or may be learned through practice of the various implementation schemes. The objectives and other advantages of the various implementation schemes will be realized and obtained through the elements and combinations particularly pointed out in the description herein. Detailed Implementation

[0007] It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and are intended to provide an explanation of various embodiments of this teaching. In its broad and varied embodiments, this document discloses a method for manufacturing pigments, such as special effects pigments.

[0008] A method for preparing pigments, such as special effects pigments, may include forming a first slurry comprising a substrate, a polymer precursor, and a free radical initiator; forming a solution comprising an emulsifier; and combining the first slurry and the solution such that the substrate is encapsulated by a first coating. This method is simple and inexpensive, and can produce a colored polymer coating encapsulating the substrate. The method may be performed in one step or in multiple steps. The method can be performed in batch production to achieve high yields.

[0009] The method includes forming a first slurry comprising a substrate, a polymer precursor (e.g., at least one polymer precursor), and a free radical initiator. The first slurry may also optionally contain a first solvent. The first slurry may also optionally contain a colorant.

[0010] The substrate used in the first slurry can comprise a single-layer material or a multi-layer structure, which will be explained in more detail later. In one aspect, the single-layer material can be a reflective layer. The reflective layer can be a broadband reflective agent, such as a spectral and Lambertian reflective agent (e.g., white TiO2). The reflective layer can be a metal, a non-metal, or a metal alloy. In one example, the material used for the reflective layer can comprise any material having reflective properties within the desired spectral range. For example, any material with a reflectivity of 5% to 100% within the desired spectral range. Examples of reflective materials can be aluminum, which has good reflective properties, is inexpensive, and is easy to form or deposit as a thin layer. Other reflective materials can also be used to replace aluminum. For example, copper, silver, gold, platinum, palladium, nickel, cobalt, niobium, chromium, tin, and combinations thereof or alloys thereof, or other metals, can be used as materials in the single-layer material or multi-layer structure. In one aspect, the material used for the reflective layer can be a white or light-colored metal. In other examples, the reflective layer may comprise, but is not limited to, transition metals and lanthanides and combinations thereof; as well as metal carbides, metal oxides, metal nitrides, metal sulfides and combinations thereof, or metals and one or more mixtures of these materials.

[0011] The thickness of the reflective layer can be from about 5 nm to about 5000 nm, although this range should not be considered limiting. For example, a lower limit of thickness can be selected such that the reflective layer provides a maximum transmittance of 0.8. Furthermore, or alternatively, for a reflective layer comprising aluminum, the optical density (OD) at a wavelength of about 550 nm can be from about 0.1 to about 4.

[0012] To achieve sufficient optical density and / or the desired effect, a higher or lower minimum thickness may be required, depending on the composition of the reflective layer. In some examples, the upper limit may be about 5000 nm, about 4000 nm, about 3000 nm, about 1500 nm, about 200 nm, and / or about 100 nm. In one aspect, the thickness of the at least one reflective layer may be about 10 nm to about 5000 nm, for example, about 15 nm to about 4000 nm, or about 20 nm to about 3000 nm.

[0013] The first slurry may contain a polymer precursor, such as at least one polymer precursor that can be polymerized to form a first coating around the substrate. The polymer precursor may be any polymerizable monomer or oligomer. Non-limiting examples of the polymer precursor include acrylic monomers, alcohols, allyl monomers, amine monomers, acid anhydride monomers, carboxylic acid monomers, epoxide monomers, isocyanate monomers, organosilicon monomers, styrene monomers, functionalized styrene monomers, vinyl esters, vinyl ethers, vinyl halides, vinylamines, vinyl amides, and combinations thereof. The polymer precursor may be polymerized in a method for forming a polymer (first) coating encapsulating the substrate. The resulting polymer coating will be explained in more detail later.

[0014] The first slurry may contain a free radical initiator that assists in the polymerization of the polymer precursor to form a first (polymer) coating around the substrate. The free radical initiator may be selected from photoinitiators, thermal initiators, and redox initiators. Non-limiting examples of photoinitiators include benzophenone, benzoyl ether, benzoyl monoketal, dialkoxyacetophenone, thioxanthone, hydroxyalkyl acetophenone, and combinations thereof. Representative examples of photoinitiators include benzophenone, benzoyl dimethyl ketal, benzoin methyl ether, benzoin isopropyl ether, diethoxyacetophenone, dibutoxyacetophenone, methyl benzoylformate, 2-chlorothioxanone, 2-ethylthioxanone, 2-isopropylthioxanone, 2,4-diethylthioxanone, phenyl 2-hydroxy-2-propyl ketone, 4-isopropylphenyl 2-hydroxy-2-propyl ketone, 4-n-dodecylphenyl 2-hydroxy-2-propyl ketone, 4-(2-hydroxyethoxy)phenyl 2-hydroxy-2-propyl ketone, 4-(2-acryloyloxyethoxy)phenyl 2-hydroxy-2-propyl ketone, 1-benzoylcyclohexanol, phenyl 2-hydroxy-2-propyl ketone, 1-benzoyl-cyclohexanol, 4-(2-hydroxyethoxy)phenyl 2-hydroxy-2-propyl ketone, isopropylthioxanone, and 2-dimethylaminoethyl benzoate. Commercially available photoinitiators are sold under the following trade names: IRGACURE® 819, DAROCUR® TPO, and IRGACURE® 369.

[0015] Non-limiting examples of thermal initiators include azo initiators, peroxide initiators, persulfate initiators, and combinations thereof. Representative examples of azo initiators include 2,2'-azobisisobutyronitrile; 2,2'-azobis(4-methoxy-2,4-dimethylpentanitrile); 2,2'-azobis(2-amidinylpropane) dihydrochloride; 2,2'-azobis(2,4-dimethylpentanitrile); 2,2'-azobis(isobutyronitrile); 2,2'-azobis-2-methylbutyronitrile; 1,1'-azobis(1-cyclohexanecarboxylonitrile); and 2,2'-azobis(methyl isobutyrate). Representative examples of peroxide initiators include benzoyl peroxide, acetyl peroxide, lauroyl peroxide, decanoyl peroxide, di(hexadecyl)dicarbonate peroxide, bis(4-tert-butylcyclohexyl)dicarbonate peroxide, bis(2-ethylhexyl)dicarbonate peroxide, tert-butyl neopentanoate peroxide, tert-butyl peroxy-2-ethylhexanoate, and dicumyl peroxide. Representative examples of persulfate initiators include potassium persulfate, sodium persulfate, and ammonium persulfate.

[0016] Suitable redox (oxidation-reduction) initiators include, but are not limited to, combinations of the above-mentioned persulfate initiators with reducing agents such as sodium metabisulfite and sodium bisulfite; systems based on organic peroxides and tertiary amines (e.g., benzoyl peroxide and dimethylaniline); and systems based on organic hydroperoxides and transition metals, such as cumene hydroperoxide and cobalt naphthenate. Non-limiting examples of reducing agents that can be used as redox initiators include Fe. 2+ Co 2+ and Cu + .

[0017] The first slurry also includes a colorant, such as a pigment or dye.

[0018] Non-limiting examples of suitable dyes may include FD&C dyes, acid dyes, direct dyes, reactive dyes, phthalocyanine dyes, phthalocyanine sulfonic acid derivatives, and combinations thereof. Non-limiting examples of suitable organic dyes include copper phthalocyanine, perylene, anthraquinone, etc.; diarylmethane dyes, triarylmethane dyes, acridine dyes, quinolone dyes, thiazole dyes, indophenol dyes, oxazine dyes, thiazine dyes, natural dyes, azo dyes, and azo metal dyes, such as aluminum red RLW, aluminum copper, aluminum Bordeaux RL, aluminum fire red ML, aluminum red GLW, aluminum violet CLW, etc.; and combinations or mixtures thereof. Suitable dyes may include, but are not limited to, those listed in the Color Index International database, such as CI Acid Red 440, CI Reactive Red 3, CI Reactive Red 13, CI Reactive Red 23, CI Reactive Red 24, CI Reactive Red 33, CI Reactive Red 43, CI Reactive Red 45, CI Reactive Red 120, CI Reactive Red 180, CI Reactive Red 194, CI Reactive Red 220, CI Reactive Violet 4, CI Reactive Blue 19, CI Reactive Blue 5, CI Reactive Blue 49, CI Reactive Yellow 2, CI Reactive Yellow 3, CI Reactive Black 39, and combinations thereof.

[0019] Suitable pigments can be black, white, cyan, magenta, yellow, etc. Furthermore, pigments can be organic or inorganic particles known in the art. Suitable inorganic pigments include, for example, carbon black, titanium dioxide, cobalt blue (CoO-Al2O3), chrome yellow (PbCrO4), and iron oxide. Suitable inorganic colorants include titanium nitride, chromium nitride, chromium oxide, iron oxide, cobalt-doped aluminum oxide, and combinations or mixtures thereof.

[0020] Suitable organic pigments include, for example, azo pigments, including diazo and monoazo pigments, polycyclic pigments (e.g., phthalocyanine pigments, such as phthalocyanine blue and phthalocyanine green, perylene pigments, pyrene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindole pigments, isoindolinone pigments, pyranone pigments, and quinacridone pigments), insoluble dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, etc. Representative examples of phthalocyanine blue include copper phthalocyanine blue and its derivatives (Pigment Blue 15). Representative examples of quinacridones include Pigment Orange 48, Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19, and Pigment Violet 42. Representative examples of anthraquinones include Pigment Red 43, Pigment Red 194 (Perinone Red), Pigment Red 216 (Brominated Pyranone Red), and Pigment Red 226 (Pyranone Red). Representative examples of perylene include Pigment Red 123 (Vermilion), Pigment Red 149 (Scarlet), Pigment Red 179 (Maroon), Pigment Red 190 (Red), Pigment Violet 19, Pigment Red 189 (Yellow Shade Red), and Pigment Red 224. Representative examples of thioindigos include Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181, Pigment Red 198, Pigment Violet 36, and Pigment Violet 38. Representative examples of heterocyclic yellows include Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 151, Pigment Yellow 117, Pigment Yellow 128, and Pigment Yellow 138.

[0021] The first slurry may optionally include a solvent, such as water or an organic solvent. Non-limiting examples of solvents may include acetates, such as ethyl acetate, propyl acetate, and butyl acetate; acetone; water; ketones, such as dimethyl ketone (DMK), methyl ethyl ketone (MEK), sec-butyl methyl ketone (SBMK), tert-butyl methyl ketone (TBMK), methyl isobutyl ketone, cyclopentanone, and anisole; ethylene glycol and ethylene glycol derivatives, such as propylene glycol methyl ether, propylene glycol methyl ether acetate, etc.; alcohols, such as isopropanol and diacetone alcohol; esters, such as malonic acid esters; heterocyclic solvents, such as n-methylpyrrolidone; hydrocarbons, such as toluene and xylene; polymerization solvents, such as ethylene glycol ether; cyclohexanone; chlorobenzene; butanol; and mixtures thereof.

[0022] The first slurry may be formed before, during, or after the formation of a solution containing emulsifiers and / or surfactants. Non-limiting examples of emulsifiers include agar, albumin, alginate, casein, cetyl alcohol, cholic acid, deoxycholic acid, diacetyl tartrate, glycerol, gum, carrageenan, lecithin, monoglycerides, diglycerides, monosodium phosphate, monostearate, propylene glycol, and combinations thereof.

[0023] The surfactant may be, for example, anionic surfactant, cationic surfactant, amphoteric surfactant, and nonionic surfactant. Non-limiting examples of anionic surfactants include sulfates, sulfonates, phosphate esters, carboxylates, and cationic head groups, such as primary, secondary, or tertiary amines. Non-limiting examples of amphoteric surfactants include compounds having a phosphate anion and an amine. Non-limiting examples of nonionic surfactants include ethoxylated fatty alcohol ethoxylates, alkylphenol ethoxylates, ethoxylated amines, ethoxylated fatty acid amides, poloxamer, glycerol fatty acid esters, sorbitol fatty acid esters, sucrose fatty acid esters, alkyl polyglycosides, amine oxides, sulfoxides, phosphine oxides, and combinations thereof. In one aspect, the functional component is a surfactant selected from sodium dodecyl sulfate (anionic surfactant), Triton X-100 (a nonionic surfactant also known as octyl phenol ethoxylated), hexadecyltrimethylammonium chloride (a cationic surfactant), and mixtures thereof.

[0024] The solution may be formed before, during, or after the formation of the first slurry. Furthermore, the formed solution may be stirred before, during, and / or after the formation of the first slurry. In one aspect, the formed solution may be stirred before it is combined with the first slurry. Once the first slurry is combined with the solution, the first slurry can be broken down into droplets dispersed in the solution. Furthermore, the free radical initiator present in the first slurry can be decomposed by at least one of thermal, light, and redox reactions. The decomposition of the free radical initiator during the combination of the first slurry and the solution can initiate the free radical polymerization of the polymer precursor in the first slurry. The free radical polymerization of the polymer precursor can form a first (polymer) coating encapsulating the substrate.

[0025] The free radical polymerization of the polymer precursor can produce a first (polymer) coating. The polymer can be at least one of organic polymers, inorganic polymers, and composite materials. Non-limiting examples of the organic polymer include thermoplastics such as polyesters, polyolefins, polycarbonates, polyamides, polyimides, polyurethanes, acrylics, acrylates, polyethylene esters, polyethers, polythiols, polysilicon, fluorocarbons, and various copolymers thereof; thermosetting resins such as epoxy resins, polyurethanes, acrylates, melamine-formaldehyde, urea-formaldehyde, and phenolic resins; and energy-curing materials such as acrylates, epoxy resins, vinyls, vinyl esters, styrene, and silanes. Non-limiting examples of acrylates used in the oxygen inhibition mitigation compositions may include acrylates; methacrylates; epoxy acrylates, such as modified epoxy acrylates; polyester acrylates, such as acid-functionalized polyester acrylates, tetrafunctionalized polyester acrylates, modified polyester acrylates, and bio-derived polyester acrylates; polyether acrylates, such as amine-modified polyether acrylates, including amine-functionalized acrylate co-initiators and tertiary amine co-initiators; polyurethane acrylates, such as aromatic polyurethane acrylates, modified aliphatic polyurethane acrylates, aliphatic polyurethane acrylates, and polyurethane acrylates based on aliphatic urea carbamates; and monomers and oligomers thereof. Non-limiting examples of inorganic polymers include silanes, siloxanes, titanates, zirconates, aluminates, silicates, phosphazanes, polyborazines, and polythiazoles. In one aspect, the polymer may include cellulose acetate butyrate, polystyrene, polyvinyl acetate, polymethyl methacrylate, and mixtures thereof.

[0026] The first slurry can be combined with the solution and persist for any time period sufficient to form a first (polymer) coating around the substrate. In one aspect, the first slurry can be combined with the solution and persist for 10 seconds to about 10 minutes, for example, about 15 seconds to about 8 minutes, and as a further example, about 20 seconds to about 6 minutes.

[0027] The methods disclosed above prepare pigments having a substrate encapsulated by a first (polymer) coating and an optional colorant. It is envisioned that the process steps can be repeated to provide multiple encapsulations via the polymer to form additional coatings (a second coating, a third coating, a fourth coating, etc.). Each additional coating can be formed from the same or different materials used to form the first coating. In one aspect, the method may further include forming a second slurry having at least one component different from the first slurry. For example, the at least one different component may be a different polymer precursor, a different radical initiator, and optionally a different colorant. The substrate in the second slurry is the formed pigment (the substrate is encapsulated by the polymer to form the first coating).

[0028] The method may further include forming a second solution that is the same as or different from the solution used to form the pigment. The second solution may be formed before, during, or after the formation of the second slurry. Furthermore, the second solution may be stirred before, during, and / or after its combination with the second slurry. Similarly, a free radical initiator present in the second slurry may decompose to cause free radical polymerization of the polymer precursor present in the second slurry. In this way, the first coating may be encapsulated by a second coating of polymer precursors polymerized from the second slurry.

[0029] A special effects pigment can be formed having a substrate (e.g., a reflective layer), a first coating of polymer, and optionally a colorant. Multiple coatings can be applied such that each additional coating (second coating, third coating, etc.) can contain different polymers and / or different colorants to provide different physical and optical properties to the special effects pigment.

[0030] Based on the foregoing description, those skilled in the art will understand that the present invention can be embodied in various forms. Therefore, although these teachings have been described in conjunction with specific embodiments and examples, the true scope of these teachings should not be limited thereto. Various changes and modifications can be made without departing from the scope of the invention.

[0031] This disclosure should be interpreted broadly. This disclosure aims to disclose equivalents, methods, systems, and approaches for implementing the apparatus, activities, and mechanical actions disclosed herein. For each disclosed apparatus, article, method, approach, mechanical element, or mechanism, this disclosure aims to also include and teach equivalents, apparatus, systems, and methods for practicing the many aspects, mechanisms, and apparatuses disclosed herein. Furthermore, this disclosure relates to coatings and many aspects, features, and elements thereof. Such apparatus can be dynamic in its use and operation, and this disclosure aims to include equivalents, apparatus, systems, and methods for using said apparatus and / or fabricated optical devices, as well as many aspects consistent with the description and spirit of the operation and function of this disclosure. The claims of this application should also be interpreted broadly. The description of the invention in its many embodiments is merely exemplary in nature, and therefore, variations without departing from the essential points of the invention are intended to fall within the scope of the invention. Such variations should not be considered as departing from the spirit and scope of the invention.

[0032] The embodiments of the present invention also include: Project 1. A method for preparing a pigment, comprising: A first slurry comprising a substrate, a polymer precursor, and a free radical initiator is formed; To form a solution containing an emulsifier; The first slurry and the solution are combined such that the substrate is encapsulated by the first coating.

[0033] Project 2. The method according to Project 1, wherein the substrate comprises a single-layer material or a multi-layer structure.

[0034] Project 3. According to the method of Project 2, the single-layer material may comprise a material selected from aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, niobium, chromium, tin, combinations thereof, and alloys thereof.

[0035] Project 4. The method according to Project 1, wherein the polymer precursor is selected from acrylic monomers, alcohols, allyl monomers, amine monomers, acid anhydride monomers, carboxylic acid monomers, epoxide monomers, isocyanate monomers, organosilicon monomers, styrene monomers, functionalized styrene monomers, vinyl esters, vinyl ethers, vinyl halides, vinylamines, vinyl amides, and combinations thereof.

[0036] Project 5. The method according to Project 1, wherein the free radical initiator is selected from photoinitiators, thermal initiators, and redox initiators.

[0037] Project 6. The method according to Project 5, wherein the photoinitiator is selected from benzophenone, benzoyl ether, benzoyl monoketone, dialkoxyacetophenone, thioxanthone, hydroxyalkyl acetophenone, and combinations thereof.

[0038] Project 7. The method according to Project 5, wherein the thermal initiator is selected from azo initiators, peroxide initiators, persulfate initiators, and combinations thereof.

[0039] Item 8. The method of Item 1, wherein the first slurry further comprises a colorant.

[0040] Item 9. The method according to Item 8, wherein the colorant is a dye or pigment.

[0041] Item 10. The method according to Item 1, wherein the first slurry further comprises a solvent selected from acetates, water, ketones, acetone, ethylene glycol, ethylene glycol derivatives, alcohols, esters, hydrocarbons, cyclohexanone, chlorobenzene, and combinations thereof.

[0042] Item 11. The method according to Item 1, wherein the solution further comprises a surfactant.

[0043] Item 12. The method according to Item 1, further comprising stirring the solution before combining the first slurry and the solution.

[0044] Project 13. The method according to Project 1, wherein the combination of the first slurry and the solution comprises at least one decomposition of the free radical initiator by heat, light and redox reactions.

[0045] Project 14. The method of Project 1, wherein the combination of the first slurry and the solution comprising the polymer precursor is subjected to free radical polymerization to form a first coating encapsulating the substrate.

[0046] Item 15. The method according to Item 1, further comprising forming a second slurry having at least one component different from the first slurry.

[0047] Item 16. The method according to Item 15, wherein the at least one different component comprises different polymer precursors, different free radical initiators, and different colorants.

[0048] Item 17. The method of Item 15, further comprising combining the second slurry and the solution such that the first coating is encapsulated by the second coating.

Claims

1. A method for preparing special effects pigments, comprising: A first slurry comprising a substrate, a polymer precursor, and a free radical initiator is formed, wherein the substrate includes a reflective layer; To form a solution containing an emulsifier; The first slurry and the solution are combined such that the substrate is encapsulated by a first coating, wherein the first slurry is broken into droplets dispersed in the solution; The free radical initiator is decomposed by at least one of heat, light and redox reactions during the combination of the first slurry and the solution to initiate the free radical polymerization of the polymer precursor in the first slurry, thereby forming the first coating. A second slurry comprising a substrate encapsulated by the first coating is formed, the second slurry comprising at least one polymer precursor different from the polymer precursor in the first slurry, or a free radical initiator different from the free radical initiator in the first slurry; Forming a second solution containing a second emulsifier; and The second slurry and the second solution are combined such that the substrate encapsulated by the first coating is further encapsulated by a second coating, the second coating providing the optical properties of the special effect pigment.

2. The method of claim 1, wherein the substrate comprises a single-layer material or a multi-layer structure, and wherein the single-layer material may comprise a material selected from aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, niobium, chromium, tin, combinations thereof, and alloys thereof.

3. The method according to claim 1, wherein the polymer precursor is selected from acrylic acid monomers, alcohols, allyl monomers, amine monomers, acid anhydride monomers, carboxylic acid monomers, epoxide monomers, isocyanate monomers, organosilicon monomers, styrene monomers, functionalized styrene monomers, vinyl esters, vinyl ethers, vinyl halides, vinylamines, vinyl amides, and combinations thereof.

4. The method according to claim 1, wherein the free radical initiator is a photoinitiator selected from benzophenone, benzoyl ether, benzoyl monoketone, dialkoxyacetophenone, thioxanthone, hydroxyalkyl benzophenone, and combinations thereof.

5. The method according to claim 1, wherein the free radical initiator is a thermal initiator selected from azo initiators, peroxide initiators, persulfate initiators, and combinations thereof.

6. The method of claim 1, wherein the first slurry further comprises a colorant, wherein the colorant is a dye or pigment.

7. The method according to claim 1, wherein the first slurry further comprises a solvent selected from acetates, water, ketones, acetone, ethylene glycol, ethylene glycol derivatives, alcohols, esters, hydrocarbons, cyclohexanone, chlorobenzene, and combinations thereof.

8. The method of claim 1, wherein the solution further comprises a surfactant.

9. The method of claim 1, further comprising stirring the solution before combining the first slurry and the solution.

10. A special effects pigment, comprising: A substrate comprising a reflective layer, a first coating of a polymer, and a second coating comprising another polymer, the other polymer being different from the polymer of the first coating; in, The first coating is formed by encapsulating the substrate with a combination of a first slurry and a solution, wherein the first slurry comprises the substrate, a polymer precursor and a free radical initiator, wherein the solution comprises an emulsifier, and wherein the first slurry is broken into droplets dispersed in the solution; The free radical initiator is decomposed by at least one of heat, light, and redox reactions during the combination of the first slurry and the solution to initiate the free radical polymerization of the polymer precursor in the first slurry, thereby forming the first coating; and The second coating further encapsulates the substrate encapsulated by the first coating through a combination of a second slurry and a second solution, wherein the second slurry contains at least one polymer precursor different from the polymer precursor in the first slurry, or a free radical initiator different from the free radical initiator in the first slurry, wherein the second solution contains a second emulsifier, and wherein the second coating imparts optical properties to the special effect pigment.