Color changing particulate compositions for additive manufacturing and related methods

Abstract

To provide thermoplastic particulate compositions suitable for additive manufacturing, which incorporate color-changing materials capable of forming different colors under specific activation conditions.SOLUTION: A particulate composition comprises: a plurality of thermoplastic particulates comprising a thermoplastic polymer, and a color-changing material associated with the thermoplastic particulates, the color-changing material being both photochromic and thermochromic. Conjugated diynes, such as 10,12-pentacosadiynoic acid or a derivative thereof, may be particularly suitable color-changing materials having photochromic and thermochromic properties for forming a range of colors on a printed object. Nanoparticles, particularly silica nanoparticles, associated with an outer surface of the thermoplastic particulates may enhance the brightness of the color obtained under various activation conditions and afford coloration permanence.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure generally relates to additive manufacturing, and more specifically, to an additive manufacturing process that employs powder microparticles capable of color change during or after the formation of a printed matter.

Background Art

[0002] Additive manufacturing, also known as three-dimensional (3-D) printing, is a rapidly growing field of technology. Additive manufacturing has traditionally been used for rapid prototyping operations, but this technology is increasingly being adopted to manufacture commercial and industrial parts (printed matters) of any number of complex shapes. The additive manufacturing process is performed by depositing each layer of either 1) a molten printing material or a flow of a liquid precursor to the printing material, or 2) powder microparticles of the printing material. The deposition of each layer is typically performed under computer control to deposit and solidify the printing material in the exact position based on a digital three-dimensional "blueprint" (computer-aided design model) of the part to be manufactured. In certain embodiments, the consolidation of the powder microparticles may be performed using a three-dimensional printing system that heats the exact position of the powder bed using a laser or an electron beam in the powder bed deposited layer by layer, thereby consolidating specific powder microparticles to form a part having a desired shape. The fusion of the powder microparticles in the powder bed may be performed by selective laser sintering (SLS) using a laser to promote the consolidation of the powder microparticles by local heating.

[0003] Among the powder microparticles that can be used in three-dimensional printing, some contain thermoplastic polymers. Although a wide range of thermoplastic polymers are known, they have relatively few properties suitable for use in current three-dimensional printing technologies, particularly when performing particle consolidation by selective laser sintering. Suitable thermoplastic polymers for consolidation by selective laser sintering include those having a significant difference between the onset of melting and the onset of crystallization, which difference can promote good structural and mechanical integrity.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Laminated manufacturing has been increasingly widely adopted for manufacturing various types of printed matter. Therefore, in many cases, it is desirable to be able to use printed matter having various colors. Although it may be possible to successfully incorporate a colorant into powder microparticles suitable for use in a laminated manufacturing process, this method requires the storage of multiple types of powder microparticles suitable for generating various desired colors. In addition to high costs and inventory management problems, this method may require loading different types of powder microparticles into a three-dimensional printing system at a predetermined time to manufacture a printed matter of a specific color. In the case of printed matter having multiple colors, the problem of supplying the colored powder microparticles to the three-dimensional printing system may be even more complicated.

[0005] The present disclosure provides a particulate composition suitable for laminated manufacturing. The particulate composition includes a plurality of thermoplastic microparticles including a thermoplastic polymer and a discoloring material associated with the thermoplastic microparticles, and the discoloring material is both photochromic and thermochromic.

[0006] The present disclosure also provides a printed matter formed using the particulate composition. The printed matter includes a polymer matrix including a thermoplastic polymer and a discoloring material associated with the polymer matrix, and the discoloring material is both photochromic and thermochromic.

[0007] The present disclosure also provides a method of forming a printed matter by laminated manufacturing. The method includes providing a particulate composition including a plurality of thermoplastic microparticles including a thermoplastic polymer and a discoloring material associated with the thermoplastic microparticles, wherein the discoloring material is both photochromic and thermochromic, and forming a printed matter having a polymer matrix including a thermoplastic polymer and a discoloring material associated with the polymer matrix.

Brief Description of the Drawings

[0008] The following figures are included to illustrate certain aspects of the present disclosure and should not be regarded as exclusive embodiments. Those skilled in the art can conceive of and consider reasonable modifications, changes, combinations, and equivalents in the form and function of the disclosed subject matter that are within the scope of the present disclosure and provide benefits thereof.

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DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure generally relates to additive manufacturing, and more specifically to an additive manufacturing process that employs powder particles capable of changing color during or after the formation of a printed article.

[0017] As described above, printed articles can be formed in a variety of complex shapes by sintering powder particles (e.g., by selective laser sintering and other powder bed fusion processes). In some cases, it may be desirable to form printed articles that have the same shape but different colors, and / or printed articles that have multiple colors within a single printed article. Currently, both approaches require storing multiple types of powder particles having specific colorants (which can be costly and operationally complex from an inventory management perspective), and supplying the suitable powder particles to the three-dimensional printing system at a specific time.

[0018] The present disclosure demonstrates that discoloring materials, particularly those that are both photochromic and thermochromic, can be successfully incorporated within powder microparticles. As used herein, the term "photochromic" refers to a substance that changes color in the presence of a specific type of electromagnetic radiation, and the term "thermochromic" refers to a substance that changes color under thermal activation at a specific temperature. Advantageously, such discoloring materials can be incorporated within powder microparticles after synthesis of the microparticles by suitable techniques, thereby storing the unmodified microparticles and, if desired, loading these microparticles with the discoloring materials. Specific discoloring materials can be incorporated within powder microparticles according to specific coloring requirements. Discoloring materials that are both photochromic and thermochromic will be described in further detail below.

[0019] Advantageous powder microparticles can be formed by melt-emulsification of a thermoplastic polymer in a high-boiling-point inert solvent, particularly in the presence of nanoparticles. U.S. Patent Application No. 16 / 946,622, filed June 30, 2020, and incorporated herein by reference, provides powder microparticles formed by melt-emulsification of a thermoplastic polymer in the presence of nanoparticles, particularly silica nanoparticles or other oxide nanoparticles, which can be particularly advantageous with regard to the narrow particle size distribution of the nanoparticles, ease of sinterability, and good powder flow performance. Further details regarding the preparation of powder microparticles by melt-emulsification in the presence of nanoparticles are provided below.

[0020] Surprisingly, a discoloring material can be incorporated onto powder microparticles formed by melt-emulsification without impairing the aforementioned desirable properties. In particular, after synthesis by melt-emulsification, one or more conjugated diynes (also referred to herein as diacetylenes) can be incorporated into powder microparticles containing a thermoplastic polymer by solution-based treatment of the powder microparticles. Many diynes have characteristic photochromic and thermochromic properties, and in particular, diynedicarboxylic acids can be suitable for use in the disclosure herein. One advantageous diynedicarboxylic acid suitable for use in the disclosure herein is 10,12-pentacosadiynoic acid (Formula 1), [Chemical formula] Upon light irradiation and / or thermal activation, blue, red, or yellow coloring can be provided to the printed matter. Advantageously, these primary colors can be mixed to produce various secondary colors (e.g., orange, purple, and green). Thus, the present disclosure provides the use of a far wider array of colors than can be directly obtained by light irradiation or thermal activation as provided herein.

[0021] The diyne is usually colorless (transparent or white) before being activated by any of light irradiation, heating, or exposure to actinic rays. Without being bound by theory, the photoactivation conditions of the diyne are thought to result in the formation of a polymerization reaction product that is a diacetylene polymer having a conjugated enyne main chain. Formula 2 shows the structure of the diacetylene polymer thought to result from the activation of 10,12-pentacosadiynoic acid (Formula 1) under photoirradiation conditions.

Chemical Formula

[0022] The discoloration performance of conjugated dienes under suitable activation conditions is known, but the present disclosure shows that unexpected performance can occur when conjugated dienes are incorporated onto the surface of thermoplastic microparticles containing silica nanoparticles. Specifically, when conjugated dienes are activated in the presence of silica nanoparticles, the intensity of the color change can become extremely prominent. Some degree of adjustability of the coloring and color intensity can also be achieved by varying the functionalization, loading amount, and / or size of the silica nanoparticles. Different surfactants can also affect the intensity of the color change. In addition, while the conjugated diene coloring obtained under various activation conditions appears to be permanent in the presence of silica nanoparticles, the coloring changes of some dienes may weaken when the activation conditions are removed in the absence of silica nanoparticles.

[0023] The terms used in the description and claims of this specification have their plain and ordinary meaning, unless modified by the following paragraphs.

[0024] As used herein, the term "discoloring material" refers to one or more monomers that form a colored polymer when polymerized under specific conditions, and / or a polymer that changes color from a first colored state to one or more second colored states after exposure under specific conditions. The terms "color" and its grammatical forms refer to any color that does not appear colorless or white to the human eye.

[0025] As used herein, the term "immiscibility" refers to a mixture of two or more components that, when mixed, form two or more phases having less than 5 wt% solubility in each other at atmospheric pressure and at room temperature, or at the melting point of the components if the components are solid at room temperature. For example, polyethylene oxide having a molecular weight of 10,000 g / mol is solid at room temperature and has a melting point of 65°C. Thus, if a material that is liquid at room temperature and the polyethylene oxide have less than 5 wt% solubility in each other at 65°C, the polyethylene oxide is immiscible with the material.

[0026] As used herein, the term "thermoplastic polymer" refers to a polymeric material that can be reversibly softened and hardened by heating and cooling. Thermoplastic polymers include thermoplastic elastomers.

[0027] As used herein, the term "nanoparticle" refers to a particulate material having a particle size in the range of about 1 nm to about 500 nm.

[0028] As used herein, the term "oxide" refers to both metal oxides and non-metal oxides. For the purposes of this disclosure, silicon is considered to be a metal.

[0029] As used herein, the term "oxide nanoparticle" refers to a particulate material having a particle size in the range of about 1 nm to about 500 nm and containing a metal oxide or a non-metal oxide.

[0030] As used herein, the term "associate" refers to a chemical bond, physical admixture of two or more substances, physical adhesion of a substance to a surface, or any combination thereof, and in particular, the substance is an emulsifying stabilizer containing nanoparticles. Without being limited by theory, the association described herein between a polymer and an emulsifying stabilizer is believed to be primarily physical adhesion by hydrogen bonding and / or other mechanisms. However, some degree of chemical bonding may occur. Similarly, a color-changing material may associate with another substance by one or more of the aforementioned mechanisms.

[0031] As used herein, the term "mixed" refers to the dissolution of a first substance in a second substance or the dispersion of a first substance as a solid in a second substance, and the dispersion may be uniform or non-uniform.

[0032] As used herein, the term "D10" refers to the diameter in which 10% of the sample (by volume unless otherwise specified) is composed of particles having a diameter less than the diameter value. As used herein, the term "D50" refers to the diameter in which 50% of the sample (by volume unless otherwise specified) is composed of particles having a diameter less than the diameter value. D50 may also be referred to as the "average particle size". As used herein, the term "D90" refers to the diameter in which 90% of the sample (by volume unless otherwise specified) is composed of particles having a diameter less than the diameter value.

[0033] As used herein, the term "shearing force" refers to agitation or a similar process that induces mechanical agitation in a fluid.

[0034] As used herein, the term "embed" with respect to the surface of nanoparticles and polymer microparticles means that the nanoparticles extend at least partially into the surface such that the polymer contacts the nanoparticles to a greater extent than if the nanoparticles were simply placed on the surface of the polymer microparticles, thereby making contact in the tangential direction of the surface.

[0035] As used herein, the viscosity of the dispersion medium, unless otherwise specified, refers to the kinematic viscosity at 25 °C and is measured in accordance with ASTM D445-19 unless otherwise specified.

[0036] The melting point of the thermoplastic polymer, unless otherwise specified, is determined by ASTM E794-06(2018) at a heating and cooling rate of 10 °C / min.

[0037] The softening temperature or softening point of the thermoplastic polymer, unless otherwise specified, is determined by ASTM D6090-17. The softening temperature can be measured using a cup and ball apparatus available from Mettler-Toledo with a heating rate of 1 °C / min using a 0.50 g sample.

[0038] As used herein, the term "derivative" refers to a compound made directly or indirectly from another compound, typically in at most two synthetic steps.

[0039] The particulate compositions of the present disclosure may include a plurality of thermoplastic microparticles including a thermoplastic polymer and a color-changing material associated with the thermoplastic microparticles, and the color-changing material is both photochromic and thermochromic. In a specific example, the color-changing material may include one or more conjugated dienes, as described in more detail below. The particulate compositions disclosed herein may be suitable for use in additive manufacturing processes, particularly additive manufacturing processes that employ selective laser sintering and other powder bed fusion processes used to facilitate particle consolidation. Particulate compositions suitable for additive manufacturing may exhibit good flow properties for dispensing into a powder bed using a print head or similar device. Flow aids and modifiers on the thermoplastic microparticles can facilitate the dispensing process. Suitable thermoplastic microparticles may also exhibit melting and crystallization temperatures compatible with specific consolidation techniques in a given additive manufacturing process.

[0040] More specific particulate compositions of the present disclosure suitable for additive manufacturing may include a plurality of microparticles including a thermoplastic polymer, a plurality of nanoparticles disposed on the outer surface of each of the plurality of thermoplastic microparticles, and a color-changing material associated with the thermoplastic microparticles. The color-changing material may be both photochromic and thermochromic, and in particular may be one or more conjugated dienes, specifically one or more conjugated dicarboxylic acids or derivatives thereof. Optionally, at least some of the nanoparticles may be mixed with the thermoplastic polymer such that a first portion of the nanoparticles is located within the thermoplastic microparticle and a second portion of the nanoparticles is disposed on the outer surface of the thermoplastic microparticle. The nanoparticles disposed on the outer surface of the thermoplastic microparticle may be at least partially embedded in and associated with the outer surface. When present, the nanoparticles disposed on the outer surface of the thermoplastic microparticle can facilitate the easy dispensing of the particulate composition during additive manufacturing.

[0041] In some embodiments, the plurality of nanoparticles can include a plurality of oxide nanoparticles. Suitable oxide nanoparticles for use in the present disclosure include, for example, silica nanoparticles, titania nanoparticles, zirconia nanoparticles, alumina nanoparticles, iron oxide nanoparticles, copper oxide nanoparticles, tin oxide nanoparticles, boron oxide nanoparticles, cerium oxide nanoparticles, thallium oxide nanoparticles, tungsten oxide nanoparticles, or any combination thereof. Mixed oxides such as aluminosilicates, borosilicates, and aluminoborosilicates are also included within the term "oxide" and can be suitably used in the disclosure herein. The oxide nanoparticles can be essentially hydrophilic or hydrophobic, which can be a natural property of the nanoparticles or a result of surface treatment of the nanoparticles. For example, silica nanoparticles having a hydrophobic surface treatment such as dimethylsilyl, trimethylsilyl, etc. can be formed by reacting hydrophilic surface hydroxyl groups with a suitable functionalizing agent. Hydrophobically modified oxide nanoparticles may be particularly desirable in the methods and particulate compositions of the present disclosure, although unmodified (non-functionalized) oxide nanoparticles or hydrophilically modified oxide nanoparticles may also be suitable for use.

[0042] Silica nanoparticles, particularly fumed silica nanoparticles having a hydrophobic functionalization thereon, can be particularly suitable for use in the disclosure herein because various functionalized silicas are available with various types of hydrophobic functionalizations and particle sizes. Hydrophilic fumed silica nanoparticles can also be suitably used in the disclosure herein. Silazane and silane hydrophobic functionalizations are included among the hydrophobic functionalizations that can be used in the present disclosure. Thus, the plurality of oxide nanoparticles used in the disclosure herein can include or consist essentially of silica nanoparticles, particularly hydrophobically or hydrophilically modified silica nanoparticles. Any type of conjugated diene can suitably interact with the conjugated diene to provide the effects described herein. The silica nanoparticles can be used in combination with another type of oxide nanoparticle or non-oxide nanoparticle, and the other type of oxide nanoparticle or non-oxide nanoparticle can impart properties not obtained when using silica nanoparticles alone to the thermoplastic microparticles or prints formed therefrom.

[0043] Carbon black is another type of nanoparticle that can be present on the thermoplastic microparticles in the disclosure of this specification. Various grades of carbon black are well known to those skilled in the art, and any of these can be used in the disclosure of this specification. Other nanoparticles that can absorb infrared rays can also be used to facilitate the formation of thermoplastic microparticles. In some cases, carbon black, silica, and other types of oxide nanoparticles can be present in combination with each other. When carbon black is included on the thermoplastic microparticles, the loading can be kept sufficiently low so that the above color change can be observed.

[0044] Polymer nanoparticles are another type of nanoparticle that can be present on the thermoplastic microparticles in the disclosure of this specification. Suitable polymer nanoparticles may include one or more polymers that are thermosetting and / or cross-linked, such that the polymer nanoparticles do not melt when processed by the melt emulsification or similar microparticle formation techniques according to the disclosure of this specification. Nanoparticles containing high molecular weight thermoplastic polymers having high melting points or decomposition points can also be similarly suitable for facilitating microparticle formation from low melting point thermoplastics.

[0045] The filling amount and particle size of silica nanoparticles or similar oxide nanoparticles on the thermoplastic microparticles can vary widely in the disclosure of this specification. The filling amount of silica nanoparticles or similar oxide nanoparticles can be determined by the nanoparticle concentration in the dispersion medium used to promote the formation of thermoplastic microparticles by melt emulsification, as further described below. There may be up to about 50 wt% nanoparticles relative to the thermoplastic polymer, for example up to about 25 wt%, or up to about 10 wt%. In non-limiting examples, the concentration of nanoparticles in the dispersion medium can be about 0.01 wt% to about 10 wt%, or about 0.05 wt% to about 10 wt%, or about 0.05 wt% to about 5 wt%, or about 0.1 wt% to about 2 wt%, or about 0.25 wt% to about 1.5 wt%, or about 0.2 wt% to about 1.0 wt%, or about 0.25 wt% to about 1 wt%, or about 0.25 wt% to about 0.5 wt% relative to the weight of the thermoplastic polymer. The particle size of the nanoparticles can range from about 1 nm to about 100 nm, although nanoparticle sizes up to about 500 nm are also acceptable. In non-limiting examples, the particle size of the nanoparticles can be in the range of about 5 nm to about 75 nm, or about 5 nm to about 50 nm, or about 5 nm to about 10 nm, or about 10 nm to about 20 nm, or about 20 nm to about 30 nm, or about 30 nm to about 40 nm, or about 40 nm to about 50 nm, or about 50 nm to about 60 nm. The nanoparticles, particularly silica nanoparticles and similar oxide nanoparticles, can have a BET surface area of about 10 m 2 / g to about 500 m 2 / g, or about 10 m 2 / g to about 150 m 2 / g, or about 25 m 2 / g to about 100 m 2 / g, or about 100 m 2 / g to about 250 m 2 / g, or about 250 m 2 / g to about 500 m 2 / g.

[0046] Certain silica nanoparticles suitable for use in the disclosure of this specification can be hydrophobically modified. Hydrophobic functionalization can improve the dispersion of silica nanoparticles in a melt-emulsion dispersion medium that can be highly hydrophobic. Hydrophobic functionalization can be non-covalently or covalently bonded to the surface of the silica nanoparticles. Covalent bonding can be effected, for example, by functionalizing the surface hydroxyl groups of the silica nanoparticles. In non-limiting examples, the silica nanoparticles may be treated with dichlorodimethylsilane or hexamethyldisilazane to obtain covalent bonds for hydrophobic modification. Examples of commercially available hydrophobically functionalized silica nanoparticles include, for example, AEROSIL RX50 (Evonik, average particle size = 40 nm, 25 - 45 m 2 / g BET surface area), AEROSIL R812S (Evonik, average particle size = 7 nm, 195 - 245 m 2 / g BET surface area), and AEROSIL R972 (Evonik, average particle size = 16 nm, 90 - 130 m 2 / g BET surface area).

[0047] Suitable conjugated dienes that can be incorporated as discoloring materials in the disclosure of this specification are not considered to be particularly limited. Exemplary conjugated dienes suitable for use in the disclosure of this specification include, for example, those described in U.S. Patent No. 8,063,164, as well as U.S. Patent Application Publication Nos. 2008 / 0293095 and 2020 / 0199392, each of which is incorporated herein by reference in its entirety. Conjugated diene carboxylic acids or their derivatives can be particularly suitable because the long-chain conjugated diene carboxylic acids are amphiphilic and can be organized in micelles. In fact, pre-organization of the conjugated diene carboxylic acids in micelles is usually necessary to promote effective polymerization of these molecules. Surprisingly, pre-organization of the conjugated dienes on the thermoplastic microparticles according to the disclosure of this specification can also be effective in promoting the color-changing polymerization reaction of these types of molecules, including in some cases molecules lacking carboxylic acid head groups. Examples of long-chain conjugated diene carboxylic acids suitable for use in the disclosure of this specification can have a structure represented by Formula 3.

Chemical formula

[0048] Derivative forms of conjugated diene dicarboxylic acids may also be suitable for use in the disclosure herein. Suitable derivative forms of conjugated diene dicarboxylic acids may include, for example, esters and amides having structures represented by the following Formula 4 and Formula 5. Also, salt forms of carboxylic acids may similarly be suitable derivative forms of conjugated diene dicarboxylic acids.

Chemical Formula

[0049] Salt form derivatives of conjugated diene carboxylic acids can likewise be employed to promote specific coloring upon activation. Transition metal salts can, for example, attenuate or change the color formed upon activation of the conjugated diene. Also, specific salt form derivatives can be selected to promote solubility or compatibility in a given solvent, for example, when incorporating the conjugated diene onto the thermoplastic microparticles. Suitable salt forms of diene carboxylic acids for use in the disclosure herein include monovalent metal salts such as alkali metal salts, divalent metal salts such as alkaline earth metal salts, trivalent metal salts such as aluminum salts, and transition metal salts (e.g., Zn salts).

[0050] Alternative discoloring materials can be used in place of, or in combination with, conjugated di-carboxylic acids.Suitable alternative thermochromic substances include, for example, bis(2-amino-4-oxo-6-methylpyrimidinium)-tetrachlorocuprate(II), bis(2-amino-4-chloro-6-methylpyrimidinium) hexachlorodocuprate(II), cobalt chloride, 3,5-dinitrosalicylic acid, leuco dyes, spiropyrens, bis(2-amino-4-oxo-6-methylpyrimidinium) tetrachlorocuprate(II) and bis(2-amino-4-chloro-6-methylpyrimidinium) hexachlorodocuprate(II), benzo- and naphthopyrans (chromenes), poly(xylylviologen) dibromide, di-β-naphthospiropyran, ferrocene-modified bis(spiropyridopyran), isomers of 1-isopropylidene-2-[1-(2-methyl-5-phenyl-3-thienyl)ethylidene]-succinic anhydride, infrared dyes, spirop benzopyran, spironaphthoxazine, spiropthiopyran and related compounds, leucoquinone dyes, natural leucoquinones, conventional leucoquinones, synthetic quinones, thiazine leuco dyes, acylated leuco thiazine dyes, non-acylated leuco thiazine dyes, oxazine leuco dyes, acylated oxazine dyes, non-acylated oxazine leuco dyes, catalytic dyes, combinations with dye developers, arylmethane phthalides, diarylmethane phthalides, monoarylmethane phthalides, monoheterocyclic-substituted phthalides, 3-heterocyclic-substituted phthalides, diarylmethylazaphthalides, bisheterocyclic-substituted phthalides, 3,3-heterocyclic-substituted phthalides, 3-heterocyclic-substituted azaphthalides, 3,3-bisheterocyclic-substituted azaphthalides, alkenyl-substituted phthalides, 3-ethenylphthalides, 3,3-bisethenylphthalides, 3-butadienylphthalides, crosslinked phthalides, spirofluorene phthalides, spirobenzanthracene phthalides, bisphthalides, di- and triarylmethanes, diphenylmethane, carbinol bases, fluoran compounds, reaction products of keto acids and phenols, reaction products of keto acids and 4-alkoxydiphenylamines, reaction products of keto acids and 3-alkoxydiphenylamines, reaction products of 2'-aminofluorane and aralkyl halides, reaction products of 3'-chlorofluorane and amines, tetrazolium salts, tetrazolium salts from formazans, tetrazolium salts from tetrazoles, etc. may be mentioned.

[0051] As other discoloring materials for the purpose, for example, leuco dyes, vinylphenylmethane-leuco cyanides and derivatives, fluoran dyes and derivatives, thermochromic pigments, micro pigments and nano pigments, molybdenum compounds, doped or undoped vanadium dioxide, indolinospiropyrans, molten waxes, encapsulated dyes, liquid crystal materials, cholesteric liquid crystal materials, spiropyrans, polybithiophenes, bipyridine materials, mercury chloride dyes, tin complexes, thermoformable materials that change structure based on temperature, natural thermochromic materials such as pigments in beans, [Cu(diethylenetriamine) 2 (BF 4 ) 2 (diethylenetriamine = N,N-diethylethylenediamine), various thermochromic inks sold by Securink Corp. (Springfield, Va.), Matusui Corp., Liquid Crystal Research Crop., or any acceptable thermochromic material having the ability to report temperature changes or being capable of photo-stimulation, etc. can be mentioned.

[0052] The filling amount of the discoloring material on the thermoplastic fine particles can vary widely. Depending on the required coloring intensity, the filling amount of the discoloring material can be up to about 50% by weight based on the thermoplastic fine particles before incorporating the discoloring material onto the thermoplastic fine particles. In certain embodiments, the filling amount of the discoloring material on the thermoplastic fine particles is about 0.1% to about 50% by weight based on the thermoplastic polymer, about 0.5% to about 25% by weight based on the thermoplastic polymer, about 1% to about 15% by weight based on the thermoplastic polymer, about 2% to about 10% by weight based on the thermoplastic polymer, or about 5% to about 25% by weight based on the thermoplastic polymer.

[0053] Examples of thermoplastic polymers suitable for use in the disclosure herein include polyamides (e.g., nylon-6, nylon-12, etc.), polyurethanes, polyethylene, polypropylene, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyesters (e.g., polylactic acid), polyethers, polyethersulfone, polyetheretherketone, polyacrylate, polymethacrylate, polyimide, acrylonitrile butadiene styrene (ABS), polyphenylene sulfide, vinyl polymers, polyarylene ethers, polyarylene sulfides, polysulfone, polyether ketone, polyaryl ether ketone (PAEK), polyamideimide, polyetherimide, polyether ester, copolymers containing polyether blocks and polyamide blocks (PEBA or polyether block amide), grafted or ungrafted thermoplastic polyolefins, functionalized or non-functionalized ethylene / vinyl monomer polymers, functionalized or non-functionalized ethylene / alkyl (meth)acrylate, functionalized or non-functionalized (meth)acrylic acid polymers, functionalized or non-functionalized ethylene / vinyl monomer / alkyl (meth)acrylate terpolymers, ethylene / vinyl monomer / carbonyl terpolymers, ethylene / alkyl (meth)acrylate / carbonyl terpolymers, methyl methacrylate-butadiene-styrene (MBS) type core-shell polymers, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) block terpolymers, chlorinated or chlorosulfonated polyethylene, polyvinylidene fluoride (PVDF), phenolic resins, poly(ethylene / vinyl acetate), polybutadiene, polyisoprene, styrenic block copolymers, polyacrylonitrile, silicone, etc., and any combination thereof, but not limited thereto. Copolymers containing one or more of the foregoing may also be used in the present disclosure.

[0054] Particularly preferred examples of the thermoplastic polymer for use in the disclosure of this specification include polyamides such as nylon 6 or nylon 12, acrylonitrile butadiene styrene, polylactic acid, polyurethane, poly(arylene ether), polyaryl ether ketone, polycarbonate, polyimide, polyphenylene sulfide, poly(arylene sulfone), polyesters such as polyethylene terephthalate or polybutylene terephthalate, copolymers containing polyether blocks and polyamide blocks (PEBA or polyether block amide), and any combination thereof.

[0055] Specific examples of suitable polyamides include polycaproamide (nylon 6, polyamide 6, or PA6), poly(hexamethylene succinamide) (nylon 46, polyamide 46, or PA46), polyhexamethylene adipamide (nylon 66, polyamide 66, or PA66), polypentamethylene adipamide (nylon 56, polyamide 56, or PA56), polyhexamethylene sebacamide (nylon 610, polyamide 610, or PA610), polyundecamide (nylon 11, polyamide 11, or PA11), polydodecamide (nylon 12, polyamide 12, or PA12), and polyhexamethylene terephthalamide (nylon 6T, polyamide 6T, or PA6T), nylon 10.10 (polyamide 10.10 or PA10.10), nylon 10.12 (polyamide 10.12 or PA10.12), nylon 10.14 (polyamide 10.14 or PA10.14), nylon 10.18 (polyamide 10.18 or PA10.18), nylon 6.10 (polyamide 6.10 or PA6.10), nylon 6.18 (polyamide 6.18 or PA6.18), nylon 6.12 (polyamide 6.12 or PA6.12), nylon 6.14 (polyamide 6.14 or PA6.14), semi-aromatic polyamides, etc., and any combinations thereof, but are not limited thereto. Copolymers can also be used. Examples of suitable copolymers include PA11 / 10.10, PA6 / 11, PA6.6 / 6, PA11 / 12, PA10.10 / 10.12, PA10.10 / 10.14, PA11 / 10.36, PA11 / 6.36, PA10.10 / 10.36, etc., and any combinations thereof, but are not limited thereto. It may be elastomeric, and polyester amides, polyether ester amides, polycarbonate-ester amides, and polyether-block-amides can also be used.

[0056] Examples of suitable polyurethanes include, but are not limited to, polyether polyurethanes, polyester polyurethanes, mixed polyethers and polyester polyurethanes, and any combination thereof. Examples of suitable polyurethanes include, but are not limited to, poly[4,4'-methylenebis(phenyl isocyanate)-alt-1,4-butanediol / di(propylene glycol) / polycaprolactone], ELASTOLLAN® 1190A (a polyether polyurethane elastomer available from BASF), ELASTOLLAN® 1190A10 (a polyether polyurethane elastomer available from BASF), and any combination thereof.

[0057] Suitable thermoplastic polymers can be elastomeric or non-elastomeric. Some of the examples of the thermoplastic polymers described above can be elastomeric or non-elastomeric depending on the specific composition of the polymer. For example, polyethylene, which is a copolymer of ethylene and propylene, may be elastomeric or may not depend on the amount of propylene present in the polymer.

[0058] Elastomeric thermoplastic polymers generally fall into one of the following six classes (any of which can be used in the disclosure herein): styrenic block copolymers, thermoplastic polyolefin elastomers, thermoplastic vulcanizates (also called elastomer alloys), thermoplastic polyurethanes, thermoplastic copolyesters, and thermoplastic polyamides (typically block copolymers containing polyamides). Examples of elastomeric thermoplastic polymers can be found in Handbook of Thermoplastic Elastomers, 2nd ed., B.M. Walker and C.P. Rader, eds., Van Nostrand Reinhold, New York, 1988. Examples of elastomeric thermoplastic polymers include, but are not limited to, elastomeric polyamides, polyurethanes, copolymers containing polyether blocks and polyamide blocks (PEBA or polyether block amides), methyl methacrylate-butadiene-styrene (MBS) type core-shell polymers, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) block terpolymers, polybutadiene, polyisoprene, styrenic block copolymers, and polyacrylonitrile), silicones, etc. Examples of elastic styrenic block copolymers can include at least one block selected from the group of isoprene, isobutylene, butylene, ethylene / butylene, ethylene-propylene, and ethylene-ethylene / propylene. More specific examples of elastic styrenic block copolymers include, but are not limited to, poly(styrene-ethylene / butylene), poly(styrene-ethylene / butylene-styrene), poly(styrene-ethylene / propylene), styrene-ethylene / propylene-styrene), poly(styrene-ethylene / propylene-styrene-ethylene-propylene), poly(styrene-butadiene-styrene), poly(styrene-butylene-butadiene-styrene), etc., and any combination thereof.

[0059] In a non-limiting example, the thermoplastic microparticles of the disclosure herein can be formed by melt emulsification. Such a method for producing thermoplastic microparticles involves mixing a thermoplastic polymer in a dispersion medium at a heating temperature above the melting point or softening temperature of the thermoplastic polymer, wherein the thermoplastic polymer and the dispersion medium are substantially immiscible at the heating temperature, applying a shear force sufficient to disperse the thermoplastic polymer as liquefied droplets in the dispersion medium at the heating temperature, cooling the dispersion medium after the liquefied droplets are formed to at least the temperature at which solidified thermoplastic microparticles containing the thermoplastic polymer are produced, and separating the thermoplastic microparticles from the dispersion medium. A specific example of such a method involves mixing a thermoplastic polymer and nanoparticles in a dispersion medium at a heating temperature above the melting point or softening temperature of the thermoplastic polymer, wherein the thermoplastic polymer and the dispersion medium are substantially immiscible at the heating temperature, applying a shear force sufficient to disperse the thermoplastic polymer as liquefied droplets in the dispersion medium at the heating temperature, and cooling the dispersion medium after the liquefied droplets are formed to at least the temperature at which solidified thermoplastic microparticles are produced, wherein the thermoplastic microparticles contain the thermoplastic polymer and at least a portion of the nanoparticles is associated with the respective outer surfaces of the thermoplastic microparticles, and separating the thermoplastic microparticles from the dispersion medium. Suitable examples of the thermoplastic polymer and the nanoparticles are provided above, and any of them can be used for the formation of the thermoplastic microparticles according to the disclosure herein. When formed by melt emulsification, the thermoplastic microparticles can be further processed to introduce a discoloring material, as described in more detail below.

[0060] Figure 1 is a flowchart of a non-limiting exemplary method 100 for manufacturing thermoplastic microparticles according to the present disclosure, where microparticle formation occurs in the presence of nanoparticles. As shown, a thermoplastic polymer 105, a dispersion medium 104, and nanoparticles 106 are mixed 108 to produce a mixture 110. One or more surfactants, such as one or more sulfonate surfactants, may also be present in the mixture 110. If present, up to about 25 wt% surfactant, based on the thermoplastic polymer 105, may be present in the mixture 110. The thermoplastic polymer 105, the dispersion medium 104, and the nanoparticles 106 may be mixed 108 in any order while performing mixing and / or heating. In a specific example, the dispersion medium 104 may be heated above the melting point or softening temperature of the thermoplastic polymer 105 before being mixed with the other components.

[0061] Heating above the melting point or softening temperature of the thermoplastic polymer 105 may be at any temperature below the decomposition temperature or boiling point of any of the components in the melt emulsion. In non-limiting examples, heating may be performed at a temperature above the melting point or softening temperature of the thermoplastic polymer 105 by about 1°C to about 50°C, or about 1°C to about 25°C, or about 5°C to about 30°C, or about 20°C to about 50°C. In the disclosure herein, the melting point may be determined by ASTM E794-06(2018) at a heating and cooling rate of 10°C / min. Unless otherwise specified, the softening temperature or softening point of a polymer is determined by ASTM D6090-17. The softening temperature may be measured using a cup and ball apparatus available from Mettler-Toledo, using a 0.50 g sample at a heating rate of 1°C / min. The melting point or softening temperature in the present disclosure may be in the range of about 50°C to about 400°C, or about 60°C to about 300°C.

[0062] Next, the mixture 110 is processed 112 by applying a shear force sufficient to produce liquefied droplets of the thermoplastic polymer 105 at a temperature higher than the melting point or softening temperature of the thermoplastic polymer 105, thereby forming a melt emulsion 114. Without being limited by theory, it is believed that increasing the shear force can decrease the size of the liquefied droplets in the dispersion medium 104, all other factors being the same. At some point, it should be understood that there may be a benefit in terms of increased shear force and decreased droplet size, and / or decreased benefit in terms of splitting into the droplet contents at a higher shear rate. Examples of suitable mixing devices for producing the melt emulsion 114 include, but are not limited to, extruders (e.g., continuous extruders, batch extruders, etc.), stirred reactors, blenders, reactors equipped with in-line homogenizer systems, and devices derived therefrom.

[0063] In non-limiting examples, the liquefied droplets can have a size of from about 1 μm to about 1,000 μm, or from about 1 μm to about 500 μm, or from about 1 μm to about 200 μm, or from about 1 μm to about 150 μm, or from about 1 μm to about 130 μm, or from about 1 μm to about 100 μm, or from about 10 μm to about 150 μm, or from about 10 μm to about 100 μm, or from about 20 μm to about 80 μm, or from about 20 μm to about 50 μm, or from about 50 μm to about 90 μm. The thermoplastic microparticles formed after solidification can be within a similar size range. That is, the thermoplastic microparticles in the microparticle compositions and methods of the present disclosure can have a size of from about 1 μm to about 1,000 μm, or from about 1 μm to about 500 μm, or from about 1 μm to about 200 μm, or from about 1 μm to about 150 μm, or from about 1 μm to about 130 μm, or from about 1 μm to about 100 μm, or from about 1 μm to about 200 μm, or from about 10 μm to about 100 μm, or from about 20 μm to about 80 μm, or from about 20 μm to about 50 μm, or from about 50 μm to about 90 μm. Particle size measurements can be performed by analysis of optical images or by using the built-in software of a Malvern Mastersizer 3000 Aero S device using light scattering techniques for particle size measurement. The aforementioned particle sizes may be maintained after incorporating the color-changing material onto the thermoplastic microparticles.

[0064] Regarding the light scattering technique, a glass bead control sample having a diameter in the range of 15 μm to 150 μm can be used with the trademarked name Quality Audit Standards QAS4002 (trademark) obtained from Malvern Analytical Ltd. The sample can be analyzed as a dry powder dispersed in air using the dry powder dispersion module of the Mastersizer 3000 Aero S. The particle size can be derived using the instrument software from a plot of volume density as a function of size.

[0065] Next, the molten emulsion 114 is cooled 116 to solidify the liquefied droplets into thermoplastic microparticles in a solid state. The cooling rate may be in the range of about 100 °C / second to about 10 °C / hour or about 10 °C / second to about 10 °C / hour, including any cooling rate therebetween. Shearing can be interrupted during cooling or maintained at the same or different rates during cooling. The cooled mixture 118 can then be processed 120 to separate the thermoplastic microparticles 126 from the other components 124 (e.g., dispersion medium 104, excess nanoparticles 106, etc.). To further purify the thermoplastic microparticles 122, washing, filtering, and / or the like may be performed at this stage, and the thermoplastic microparticles 122 include the thermoplastic polymer 105 and at least a portion of the nanoparticles 106 that coat the outer surface of the thermoplastic microparticles 122 as at least a partial coating. Depending on non-limiting factors such as temperature (including cooling rate), the type of thermoplastic polymer 105, and the type and size of the nanoparticles 106, the nanoparticles 106 can be at least partially embedded within the outer surface of the thermoplastic microparticles 122 during the process of being disposed on the thermoplastic microparticles 122. Even if embedding does not occur, the nanoparticles 106 can remain strongly associated with the thermoplastic microparticles 122, facilitating their further use.

[0066] As described above, the thermoplastic polymer 105 and the dispersion medium 104 are selected such that these components are immiscible or substantially immiscible (solubility less than 5% by weight), particularly solubility less than 1% by weight, at various processing temperatures (e.g., from room temperature to the temperature at which liquefied droplets are formed and maintained as two or more phases).

[0067] After separating the thermoplastic microparticles 122 from the other components 124, further processing 126 of the thermoplastic microparticles 122 can be performed. In non-limiting examples, the further processing 126 may include, for example, sieving the thermoplastic microparticles 122 and / or blending the thermoplastic microparticles 122 with other substances to form processed thermoplastic microparticles 128. The processed thermoplastic microparticles 128 can be formulated for use in desired applications such as, for example, additive manufacturing in non-limiting examples.

[0068] In another non-limiting example, the further processing 126 may include incorporating a color-changing material, such as one or more conjugated dienes, onto the thermoplastic microparticles 122. Optionally, during the further processing 126, a surfactant (e.g., an anionic surfactant, a cationic surfactant, a neutral surfactant, or an amphoteric surfactant) may be incorporated onto the thermoplastic microparticles 122. Further details regarding the incorporation of the color-changing material onto the thermoplastic microparticles 122 are provided below.

[0069] The thermoplastic microparticles of the present disclosure have a bulk density of about 0.3 g / cm 3 ~ about 0.8 g / cm 3 、 or about 0.3 g / cm 3 ~ about 0.6 g / cm 3 、 or about 0.4 g / cm 3 ~ about 0.7 g / cm 3 、 or about 0.5 g / cm 3 ~ about 0.6 g / cm 3 、 or about 0.5 g / cm 3 ~ about 0.8 g / cm 3 and may have.

[0070] Shearing force sufficient to form liquefied droplets can be applied by agitating the dispersion medium in certain embodiments of the present disclosure. In non-limiting examples, the agitation speed can range from about 50 revolutions per minute (rpm) to about 1500 rpm, or from about 250 rpm to about 1000 rpm, or from about 225 rpm to about 500 rpm. The agitation speed during melting or softening of the thermoplastic polymer may be the same as or different from the agitation speed used when the liquefied droplets are formed. The liquefied droplets can be agitated for an agitation time ranging from about 30 seconds to about 18 hours or more, or from about 1 minute to about 180 minutes, or from about 1 minute to about 60 minutes, or from about 5 minutes to about 6 minutes, or from about 5 minutes to about 30 minutes, or from about 10 minutes to about 30 minutes, or from about 30 minutes to about 60 minutes.

[0071] The filling amount (concentration) of the thermoplastic polymer in the dispersion medium can vary over a wide range. In non-limiting examples, the filling amount of the thermoplastic polymer in the dispersion medium may range from about 1 wt% to about 99 wt% based on the weight of the dispersion medium. In more specific examples, the filling amount of the thermoplastic polymer may range from about 5 wt% to about 75 wt%, or from about 10 wt% to about 60 wt%, or from about 20 wt% to about 50 wt%, or from about 20 wt% to about 30 wt%, or from about 30 wt% to about 40 wt%, or from about 40 wt% to about 50 wt%, or from about 50 wt% to about 60 wt%. The thermoplastic polymer can be present in an amount ranging from about 5 wt% to about 60 wt%, or from about 5 wt% to about 25 wt%, or from about 10 wt% to about 30 wt%, or from about 20 wt% to about 45 wt%, or from about 25 wt% to about 50 wt%, or from about 40 wt% to about 60 wt% based on the combined amount of the thermoplastic polymer and the dispersion medium.

[0072] When forming thermoplastic microparticles in the presence of nanoparticles according to the disclosure of this specification, at least a portion of the nanoparticles, such as silica nanoparticles or other oxide nanoparticles, can be arranged as a coating or partial coating on the outer surface of the thermoplastic microparticles. The coating can be arranged substantially uniformly on the outer surface. When used herein with respect to the coating, the term "substantially uniform" refers to a uniform coating thickness at the surface positions covered by the nanoparticles, particularly over the entire outer surface. The coating coverage rate on the thermoplastic microparticles can range from about 5% to about 100%, or about 5% to about 25%, or about 20% to about 50%, or about 40% to about 70%, or about 50% to about 80%, or about 60% to about 90%, or about 70% to about 100% of the surface area of the particles. The coverage rate can be determined by image analysis of SEM micrographs.

[0073] Suitable dispersion media for use in the disclosure of this specification include those in which the thermoplastic polymer is substantially immiscible with the dispersion medium, the dispersion medium has a boiling point above the melting point or softening temperature of the thermoplastic polymer, and the dispersion medium has a viscosity sufficient to form substantially spherical liquefied droplets when the thermoplastic polymer is melted therein. Suitable dispersion media include, for example, silicone oil, fluorinated silicone oil, perfluorinated silicone oil, polyethylene glycol, alkyl-terminated polyethylene glycol (e.g., C1-C4 terminal alkyl groups such as tetraethylene glycol dimethyl ether (TDG)), paraffin, liquid petroleum jelly, mink oil, turtle oil, soybean oil, perhydrosqualene, sweet almond oil, carophyllum oil, palm oil, pearl rim oil, grape seed oil, sesame oil, corn oil, rapeseed oil, sunflower oil, cottonseed oil, almond oil, castor oil, avocado oil, jojoba oil, olive oil, cereal germ oil, esters of lanolinic acid, esters of oleic acid, esters of lauric acid, esters of stearic acid, aliphatic esters, higher fatty acids, aliphatic alcohols, polysiloxanes modified with fatty acids, polysiloxanes modified with aliphatic alcohols, polysiloxanes modified with polyoxyalkylene, etc., and any combination thereof.

[0074] A suitable dispersion medium may have a density of about 0.6 g / cm 3 to about 1.5 g / cm 3 and the thermoplastic polymer may have a density of about 0.7 g / cm 3 to about 1.7 g / cm 3 and the thermoplastic polymer may have the same density as, lower than, or higher than the dispersion medium.

[0075] Particularly suitable silicone oils are polysiloxanes. Exemplary silicone oils suitable for use in the disclosure herein include, for example, polydimethylsiloxane (PDMS), methylphenylpolysiloxane, alkyl-modified polydimethylsiloxane, alkyl-modified methylphenylpolysiloxane, amino-modified polydimethylsiloxane, amino-modified methylphenylpolysiloxane, fluorine-modified polydimethylsiloxane, fluorine-modified methylphenylpolysiloxane, polyether-modified polydimethylsiloxane, polyether-modified methylphenylpolysiloxane, etc., and any combination thereof.

[0076] In a non-limiting example, the dispersion medium and the thermoplastic polymer can be heated at a temperature of about 200 °C or higher. Suitable heating temperatures can be selected based on the melting point or softening temperature of the thermoplastic polymer and the boiling point of the dispersion medium. The maximum heating temperature can be limited by the decomposition point of the dispersion medium and / or the thermoplastic polymer, but in many cases, the maximum heating temperature can be up to about 300 °C, preferably up to about 260 °C. The cooling rate after the formation of the liquefied polymer droplets can be various as desired. In some cases, cooling can occur with heat dissipation to the ambient environment at a natural (uncontrolled) rate after heating is interrupted. In other cases, cooling can be carried out at a controlled rate (for example, by gradually decreasing the heating temperature and / or by using jacketed temperature control to increase or decrease the cooling rate).

[0077] Suitable dispersion media such as polysiloxanes containing PDMS can have viscosities of about 1,000 cSt to about 150,000 cSt, or about 1,000 cSt to about 60,000 cSt, or about 40,000 cSt to about 100,000 cSt, or about 75,000 cSt to about 150,000 cSt at 25°C. The viscosity of the dispersion medium can be obtained from commercial suppliers or, if desired, measured by techniques known to those skilled in the art.

[0078] Separation of the thermoplastic microparticles from the dispersion medium can be carried out by any of a variety of known separation techniques. Gravity sedimentation and filtration, decantation, centrifugation, etc. can be used to separate the thermoplastic microparticles from the dispersion medium. The thermoplastic microparticles can then be washed with a solvent in which the dispersion medium is soluble and the thermoplastic microparticles are insoluble during the separation process. In addition, a solvent in which the dispersion medium is soluble and the thermoplastic microparticles are insoluble can be mixed with the dispersion medium and the thermoplastic microparticles before the elastomeric particles are first separated from the dispersion medium. The solvent and / or the dispersion medium can be recycled, if necessary, to process subsequent batches of thermoplastic microparticles.

[0079] Suitable solvents for washing the thermoplastic microparticles or mixing with the dispersion medium include aromatic hydrocarbons (e.g., toluene and / or xylene), aliphatic hydrocarbons (e.g., heptane, n - hexane, and / or n - octane), cyclic hydrocarbons (e.g., cyclopentane, cyclohexane, and / or cyclooctane), ethers (e.g., diethyl ether, tetrahydrofuran, diisopropyl ether, and / or dioxane), halogenated hydrocarbons (e.g., dichloroethane, trichloroethane, dichloromethane, chloroform, and / or carbon tetrachloride), alcohols (e.g., methanol, ethanol, isopropanol, and / or n - propanol), ketones (e.g., methyl ethyl ketone and / or acetone); esters (e.g., ethyl acetate, etc.), water, etc., and any combination thereof can be mentioned, but not limited thereto. After washing the thermoplastic microparticles, heating, vacuum drying, air drying, or any combination thereof can be carried out to remove the residual solvent.

[0080] At least most of the thermoplastic microparticles obtained according to the present disclosure may be substantially spherical in shape. More typically, about 90% or more, or about 95% or more, or about 99% or more of the thermoplastic microparticles produced by melt emulsification according to the present disclosure may be substantially spherical in shape. In other non-limiting examples, the thermoplastic microparticles of the present disclosure may have a sphericity (circularity) of about 0.9 or more, including from about 0.90 to about 1.0, or from about 0.93 to about 0.99, or from about 0.95 to about 0.99, or from about 0.97 to about 0.99, or from about 0.98 to 1.0. The circularity can be measured using a Sysmex FPIA-2100 Flow Particle Image Analyzer. To determine the circularity, an optical microscope image of the microparticle is taken. The perimeter (P) and area (A) of the microparticle in the plane of the microscope image are calculated (for example, using the SYSMEX FPIA 3000 Particle Shape and Particle Size Analyzer available from Malvern Instruments). The circularity of the microparticle is C EA / P, where C EA is the circumference of a circle having an area equivalent to the area (A) of the actual microparticle.

[0081] The thermoplastic microparticles of the present disclosure may have an angle of repose of about 25° to about 45°, or about 25° to about 35°, or about 30° to about 40°, or about 35° to about 45°. The angle of repose can be determined using a Hosokawa Micron Powder Characteristics Tester PT-R in accordance with ASTM D6393-14, "Standard Test Method for Bulk Solids Characterized by Carr Indices".

[0082] The thermoplastic microparticles separated from the dispersion medium according to the above disclosure may be further processed to produce thermoplastic microparticles suitable for the intended use. In one example, the thermoplastic microparticles may be passed through a sieve or similar structure having an effective screening size larger than the average particle size of the thermoplastic microparticles. For example, an exemplary screening size for processing thermoplastic microparticles suitable for use in three-dimensional printing may have an effective screening size of about 150 μm. Referring to sieving, the pore / screen size is described in U.S.A. Standard Sieve (ASTM E11-17). Other screening sizes, larger or smaller, may be more suitable for thermoplastic microparticles intended for use in other applications. Sieving can remove larger microparticles that may form during the melt emulsification process and / or lumpy microparticles that may have insufficient flow characteristics. Generally, a sieve having an effective screening size in the range of about 10 μm to about 250 μm may be used.

[0083] In another specific example, further processing of the thermoplastic microparticles may, as described above, include associating a color-changing material with the thermoplastic microparticles under melt emulsification conditions after its formation. A color-changing material such as a conjugated diene may be dissolved or suspended in a solvent and then contacted with the thermoplastic microparticles. Suitable solvents may be selected so as not to expand the thermoplastic microparticles appreciably or otherwise affect their powder flow performance. In non-limiting examples, the color-changing material may be dissolved or suspended in the same solvent used to wash the thermoplastic microparticles after synthesis by melt emulsification or in a similar type of solvent such as heptane or a similar saturated hydrocarbon solvent.

[0084] The contact between the thermoplastic microparticles and the discoloring material in the solvent may be carried out at a temperature in the range from about 0 °C to the reflux temperature of the solvent under static or non-static conditions. Preferably, the contact may be carried out at room temperature. Examples of non-static contact conditions include stirring, sonication, or any combination thereof. The contact time for incorporating the discoloring material onto the thermoplastic microparticles can range from about 1 minute to about 24 hours, or from about 10 minutes to about 12 hours, or from about 30 minutes to about 6 hours, or from about 1 hour to about 4 hours, or from about 6 hours to about 12 hours.

[0085] After the discoloring material has suitably associated with the thermoplastic microparticles, the thermoplastic microparticles can be separated from the solvent by filtration, decantation, centrifugation, or any combination thereof. Then, drying of the thermoplastic microparticles can be carried out prior to use.

[0086] In addition, after the discoloring material has associated with the thermoplastic microparticles, the thermoplastic microparticles can be mixed with one or more additional constituents such as flow aids, fillers, or other substances, which are intended to adjust the properties of the thermoplastic microparticles for the intended use. The mixing of the additional constituents with the thermoplastic microparticles can be carried out by dry blending techniques. The additional constituents may be included in an amount that can maintain the above-described observable discoloration. Suitable examples of flow aids (e.g., carbon black, graphite, silica, etc.) and similar substances are well known to those skilled in the art. Further sieving of the thermoplastic microparticles may also be carried out at this stage and / or after association with the discoloring material, if necessary.

[0087] For certain applications, the particulate compositions disclosed herein may be used in additive manufacturing processes, particularly selective laser sintering or other powder bed fusion processes that promote particulate consolidation. Depending on how particulate consolidation is carried out, prints formed by particulate consolidation of thermoplastic particulates carrying a color-changing material may be colorless (i.e., having a color determined primarily by the thermoplastic polymer), or may be in a first colored state determined primarily by the color-changing material and enhanced by the presence of the nanoparticles. For example, in the case of a conjugated diene such as 10,12-pentacosadiynoic acid, a print obtained by particulate consolidation using an infrared laser (e.g., a CO 2 laser or a similar infrared or near-infrared laser) may not initially activate the conjugated diene and may leave the print in a substantially colorless state. The conjugated diene may then be activated by ultraviolet light irradiation to promote polymerization of the conjugated diene to a diacetylene polymer, thereby bringing the print into the first colored state. In the case of 10,12-pentacosaidynoic acid and similar conjugated diynoic acids, the first colored state may be blue or a blue color tone. The completed print may be converted to the first colored state by irradiating the entire outer surface of the print, or the first coloring may be selectively introduced onto the print by local UV irradiation at specific locations on the surface of the print.

[0088] After forming the first coloring state, the second coloring state may be introduced into the printed matter by heat treatment. The second coloring state can be achieved by heating the printed matter to a temperature in the range of about 30°C to about 200°C. In the case of 10,12-pentacosanedioic acid, the second coloring state may be a red to magenta color obtained by heating the printed matter to about 50°C, or the second coloring state may be a yellow or yellowish color tone by heating the printed matter to about 150°C. The entire outer surface of the printed matter may be converted to the second coloring state, or the second coloring state may be selectively introduced by local heating. Alternatively, after generating the second coloring state, any of the conjugated dienes that have not been previously converted to the first coloring state may be converted to the first coloring state by UV irradiation. Thus, in some cases, the first coloring state and the second coloring state can coexist in combination with each other in the printed matter, in addition to the colorless regions where the discoloring material is not activated. Also, for any region that is generated to the first coloring state after the second coloring state has already been generated, the newly generated first coloring state may be converted to the same or a different second coloring state as the previously generated one. For example, a printed matter having a yellow second coloring state may be generated in combination with a blue first coloring state by subsequent activation of the conjugated diene. Thereafter, the blue first coloring state can be activated to generate a red or magenta second coloring state. Thus, depending on the needs of a particular application, a wide range of color combinations may be achievable.

[0089] Thus, the additive manufacturing process of the present disclosure can obtain a printed article having a polymer matrix comprising a thermoplastic polymer and a discoloring material associated with the polymer matrix, the discoloring material being both photochromic and thermochromic. The discoloring material may include one or more conjugated dienes or polymerized forms thereof, and the polymerized forms may provide a first colored state and / or a second colored state different from the first colored state to at least a portion of the printed article. For example, in at least a portion of the printed article, at least a majority of one or more conjugated dienes may be present in a polymerized form, and the first colored state may be imparted to a portion of the printed article. The polymerized form may be modified by heating such that a portion of the printed article has a second colored state different from the first colored state in at least a portion of the printed article.

[0090] A plurality of nanoparticles, such as a plurality of silica nanoparticles or other types of oxide nanoparticles, may also be present within the polymer matrix. Advantageously, the silica nanoparticles may enhance the coloring obtained from the first colored state and / or the second colored state. A surfactant may also be present within the polymer matrix.

[0091] The additive manufacturing process of the present disclosure is to provide a particulate composition comprising a plurality of thermoplastic particles comprising a thermoplastic polymer and a discoloring material associated with the thermoplastic particles, the discoloring material being both photochromic and thermochromic, and forming a printed article having a polymer matrix comprising a thermoplastic polymer and a discoloring material associated with the polymer matrix. Preferably, the thermoplastic particles have a plurality of nanoparticles, such as silica nanoparticles or other oxide nanoparticles, disposed on an outer surface of the thermoplastic particles, whereby the silica nanoparticles or other oxide nanoparticles are present within the polymer matrix when forming the printed article. In a specific embodiment, the method of forming a printed article according to the present disclosure may include depositing the particulate composition on a powder bed and consolidating a portion of the thermoplastic particles within the powder bed.

[0092] A method of forming a printed matter according to the present disclosure may include introducing coloration into the printed matter. Specifically, the method of the present disclosure may include exposing at least a portion of the printed matter to a first activation condition such as light irradiation (e.g., UV irradiation) sufficient to convert a discoloring material into a polymerized form of the discoloring material having a first coloring state. Thereafter, if necessary, the method of the present disclosure may include exposing at least a portion of the printed matter to a second activation condition such as heat activation sufficient to convert the polymerized form of the discoloring material into a second coloring state different from the first coloring state. The first coloring state and the second coloring state may coexist within a given printed matter by local application of the first and second activation conditions.

[0093] Conditions suitable for performing selective laser sintering or other powder bed particle consolidation processes for forming a printed matter are not considered to be particularly limited. Depending on the desired result, the particle consolidation process may or may not promote the polymerization of the conjugated diene to produce the first coloring state. That is, depending on how the particle consolidation is performed, the printed matter or a portion of the printed matter may be in an initial coloring state determined mainly by a thermoplastic polymer (e.g., white or colorless), and then converted to a first coloring state determined by the polymerized form of the conjugated diene. Lasers suitable for performing selective laser sintering without activating the conjugated diene may include both continuous wave lasers and pulsed wave lasers, either of which may provide the energy necessary to promote the consolidation of the thermoplastic particles. CO 2 The laser is CO 2 Due to the high absorbability of the polymer for the laser emission wavelength, it is generally used to promote the consolidation of thermoplastic particles during selective laser sintering. CO 2The operating conditions of the laser can be selected such that particle consolidation occurs preferentially over the activation of the conjugated diene. Standard laser settings (e.g., power, scanning speed, bed temperature, etc.) for promoting the consolidation of the thermoplastic particles are selected based on the particular thermoplastic polymer present, and suitable laser settings can be selected by those skilled in the art. The selection of specific conditions for performing selective laser sintering or similar powder consolidation techniques can be influenced by non-limiting factors such as, for example, the type of thermoplastic polymer used, the particle size and composition of the thermoplastic particles, the type of printed article being manufactured, and the intended use conditions of the printed article.

[0094] Heating of at least a portion of the printed article may be conducted radiatively substantially across the entire surface of the printed article, or the heating may be localized by directed heating such as a laser or a heated air stream. Other techniques for generating localized heating are also suitable and will be recognizable to those skilled in the art.

[0095] Examples of formable printed articles using the particulate compositions disclosed herein are not particularly limiting, but include, for example, containers (e.g., for food, beverages, cosmetics, personal care compositions, pharmaceuticals, etc.), shoe soles, toys, furniture parts, decorative household items, plastic gears, screws, nuts, bolts, cable ties, medical supplies, prostheses, orthopedic implants, learning aids, 3D anatomical models, robots, biomedical devices (orthotic devices), household appliances, dental fillings, automotive and aircraft / aerospace parts, electronic devices, sports equipment, etc. As will be described below, the ability to produce these and other types of printed articles in a variety of colors can be advantageous.

[0096] In certain embodiments, the particulate compositions disclosed herein may include at least a portion of an autonomous temperature sensor. Specifically, the print may include a patterned location of a color-changing material activated in a first coloring state (e.g., blue in the case of a conjugated diene). Alternatively, a decal or similar label including a patterned mark of a thermoplastic polymer and a color-changing material activated in a first coloring state may be applied to an existing object, whether printed or not. Subsequently, further thermal activation of the color-changing material to a second coloring state may indicate the state to which the object has been exposed.

[0097] The embodiments disclosed herein include the following.

[0098] A. A particulate composition comprising powder particulates. The particulate composition includes a plurality of thermoplastic particulates comprising a thermoplastic polymer and a color-changing material associated with the thermoplastic particulates, the color-changing material being both photochromic and thermochromic.

[0099] B. A print. The print includes a polymer matrix comprising a thermoplastic polymer and a color-changing material associated with the polymer matrix, the color-changing material being both photochromic and thermochromic.

[0100] C. A method for forming a print by particulate consolidation. The method includes providing a particulate composition including a plurality of thermoplastic particulates comprising a thermoplastic polymer and a color-changing material associated with the thermoplastic particulates, the color-changing material being both photochromic and thermochromic, and forming a print having a polymer matrix comprising a thermoplastic polymer and a color-changing material associated with the polymer matrix.

[0101] Each of embodiments A-C may optionally have one or more of the following additional elements in any combination.

[0102] Element 1: The color-changing material includes one or more conjugated dienes.

[0103] Element 2: One or more conjugated dienes include a conjugated diene carboxylic acid or a derivative thereof.

[0104] Element 3: The conjugated diene carboxylic acid includes 10,12-pentacosadienoic acid.

[0105] Element 4: The particulate composition further includes a plurality of nanoparticles disposed on the outer surface of each of the plurality of thermoplastic particles, and the plurality of nanoparticles include a plurality of oxide nanoparticles.

[0106] Element 5: The plurality of oxide nanoparticles include a plurality of silica nanoparticles.

[0107] Element 6: The silica nanoparticles are hydrophobically modified.

[0108] Element 7: The particulate composition further includes a surfactant that associates with the outer surface of the thermoplastic particles.

[0109] Element 8: The color-changing material includes one or more conjugated dienes or a polymerized form thereof.

[0110] Element 9: At least most of the one or more conjugated dienes are present in a polymerized form, and the printed matter has a first coloring state.

[0111] Element 10: The polymerized form is modified by heating, and the printed matter has a second coloring state different from the first coloring state.

[0112] Element 11: The printed matter further includes a plurality of nanoparticles present in the polymer matrix, and the plurality of nanoparticles include a plurality of oxide nanoparticles.

[0113] Element 12: The printed matter further includes a surfactant present in the polymer matrix.

[0114] Element 13: Forming the printed matter includes depositing the particulate composition in a powder bed and consolidating a portion of the thermoplastic particles in the powder bed.

[0115] Element 14: The method further includes exposing at least a portion of the printed matter to first activation conditions sufficient to convert the discoloring material into a polymerized form of the discoloring material having a first coloring state. Element 15: The first activation conditions include light irradiation of the printed matter.

[0116] Element 16: The method further includes exposing at least a portion of the printed matter to second activation conditions sufficient to convert the polymerized form of the discoloring material into a second coloring state different from the first coloring state.

[0117] Element 17: The second activation conditions include heat treatment of the printed matter.

[0118] Element 18: The plurality of thermoplastic microparticles further includes a plurality of nanoparticles disposed on the outer surface of each of the plurality of thermoplastic microparticles, and the plurality of nanoparticles includes a plurality of oxide nanoparticles.

[0119] Element 19: The surfactant associates with the outer surface of the thermoplastic microparticles.

[0120] As non-limiting examples, exemplary combinations applicable to A include, but are not limited to, 1 and 4, 1, 2 or 3, and 4, 1 to 4 and 5, 1, 2 or 3, and 4 or 5, 1 and 7, 1, 4 and 7, 1, 2 or 3, 4 and 7, 1 to 4, 5 and 7, 4 and 7, 4, 5 and 7. Further exemplary combinations applicable to B include, but are not limited to, 8 and 9, 8 to 10, 8 and 11, 8, 5 and 11, 8 and 12, 8, 11 and 12, 8, 5, 11 and 12, 5 and 11, 5, 11 and 12, 11 and 12. Exemplary combinations applicable to C include, but are not limited to, 13 and 14, 13 to 15, 13 and 16, 13, 14 and 16, 13 to 16, 13, 16 and 17, 13 to 17, any of the foregoing in further combination with 1, 1, and 2 or 3, 18, 19, 18 and 19, 18 and 5, 18, 5, and 19.

[0121] To facilitate a better understanding of the present disclosure, the following examples of preferred or representative embodiments are provided. The following examples should not be read to limit or define the scope of the present invention.

Example

[0122] Polyether block amide (PEBA, VESTAMID E40S3, polyamide-12, Evonik) was processed into powder microparticles by melt emulsification in the following examples. Notably, silica nanoparticles were included during the melt emulsification process.

[0123] UV irradiation was performed using a 254 nm short-wavelength irradiation lamp (Spectroline Model ENF-260C, Spectronics Corporation). The irradiation was carried out 7 cm away from the sample.

[0124] Heating was carried out using an IKA RCT basic hot plate set at a specific temperature.

[0125] The coloring of the sample was measured using an XRITE 528 spectrophotometer.

[0126] Synthesis Sample 1: A 500 mL glass reactor was filled with 160 g of silicone oil (PSF 10,000, Clearco) and heated to 200°C under nitrogen at a stirring speed of 500 rpm. VESTAMID E40S3 polymer microparticles (40 g) were added to the reactor and stirring was continued for an additional 30 minutes. The mixture was then cooled to room temperature and the resulting polymer microparticles were separated by vacuum filtration on Whatman filter paper. The polymer microparticles were washed three times with heptane on the filter paper.

[0127] Next, 10,12 - pentacosa - diynoic acid was incorporated into the polymer microparticles. 0.8 g of polymer microparticles and 0.2 g of 10,12 - pentacosa - diynoic acid were mixed in 9 g of ethanol, and the mixture was stirred at 1000 rpm for 2 hours at room temperature. Then, sonication was performed for 1 hour, and the mixture was stored at 4°C for 12 hours. Then, the polymer microparticles were recovered by filtration and dried for 24 hours.

[0128] Sample 2: Sample 1 was repeated except that 0.05 g of an anionic surfactant (sodium dodecylbenzene sulfonate - SDBS) was mixed with the polymer microparticles and 10,12 - pentacosa - diynoic acid in ethanol.

[0129] Sample 3: Sample 1 was repeated except that 0.05 g of a cationic surfactant (cetyltrimethylammonium bromide - CTAB) was mixed with the polymer microparticles and 10,12 - pentacosa - diynoic acid in ethanol.

[0130] Sample 4: During melt - emulsification, Sample 1 was repeated except that 0.4 g of hydrophobic modified silica nanoparticles (AEROSIL R972, modified with dimethyldichlorosilane, surface area by BET 90 - 130 m 2 / g) was included in the silicone oil. Separation of the polymer microparticles and incorporation of 10,12 - pentacosa - diynoic acid were carried out as described above.

[0131] Sample 5: During melt - emulsification, Sample 1 was repeated except that 0.4 g of hydrophobic modified silica nanoparticles (AEROSIL RX50, modified with hexamethyldisilazane, surface area by BET 25 - 45 m 2 / g) was included in the silicone oil. Separation of the polymer microparticles and incorporation of 10,12 - pentacosa - diynoic acid were carried out as described above.

[0132] Sample 6: During melt - emulsification, Sample 1 was repeated except that 0.4 g of hydrophobic modified silica nanoparticles (AEROSIL R812S, modified with hexamethyldisilazane, surface area by BET 195 - 245 m 2Sample 1 was repeated except that ( / g) was included in silicone oil. Separation of polymer microparticles and incorporation of 10,12-pentacosadiynoic acid were carried out as described above.

[0133] Sample 7: During melt emulsification, except that 0.4 g of hydrophobically modified silica nanoparticles (AEROSIL R812S, hexamethyldisilazane modified, surface area by BET 195 - 245 m 2 / g) was included in silicone oil and 0.05 g of anionic surfactant (sodium dodecylbenzenesulfonate - SDBS) was mixed with 10,12-pentacosadiynoic acid and polymer microparticles in ethanol, Sample 1 was repeated. Separation of polymer microparticles and incorporation of 10,12-pentacosadiynoic acid were carried out as described above.

[0134] Sample 8: During melt emulsification, except that 0.4 g of hydrophobically modified silica nanoparticles (AEROSIL R812S, hexamethyldisilazane modified, surface area by BET 195 - 245 m 2 / g) was included in silicone oil and 0.05 g of cationic surfactant (cetyltrimethylammonium bromide - CTAB) was mixed with 10,12-pentacosadiynoic acid and polymer microparticles in ethanol, Sample 1 was repeated. Separation of polymer microparticles and incorporation of 10,12-pentacosadiynoic acid were carried out as described above.

[0135] Sample 9: During melt emulsification, except that 0.4 g of hydrophilic fumed silica nanoparticles (AEROSIL 380, surface area by BET 350 - 410 m 2 / g) was included in silicone oil, Sample 1 was repeated. Separation of polymer microparticles and incorporation of 10,12-pentacosadiynoic acid were carried out as described above.

[0136] Sample 10: Sample 1 was repeated except that ethanol was replaced with heptane when incorporating 10,12-pentacosadiynoic acid.

[0137] Sample 11: Sample 2 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0138] Sample 12: Sample 3 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0139] Sample 13: Sample 4 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0140] Sample 14: Sample 5 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0141] Sample 15: Sample 6 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0142] Sample 16: Sample 7 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0143] Sample 17: Sample 8 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0144] Sample 18: Sample 9 was repeated except that ethanol was replaced with heptane when 10,12 - pentacosa - diynoic acid was incorporated.

[0145] The following Table 1 summarizes the compositions of Samples 1 - 18 prepared as described above. The average particle size (D of Samples 1 - 9 50) was 82 microns and the span was 1.865. For Samples 10 - 18, the average particle size was 72 microns and the span was 2.182. The average particle size measurements were made by light scattering using a Malvern Mastersizer 3000 Aero S particle size analyzer. A glass bead control sample with diameters in the range of 15 μm to 150 μm under the trade name Quality Audit Standards QAS 4002 (trademark) obtained from Malvern Analytical Ltd. was used. The sample was analyzed as a dry powder dispersed in air using the dry powder dispersion module of the Mastersizer 3000 Aero S. The particle size was derived from a plot of volume density as a function of size using the instrument software.

Table 1

[0146] Samples obtained by mixing ethanol with 10,12 - pentacosanedioic acid (Samples 1 - 9) had significant swelling and aggregation, thereby preventing the formation of free - flowing powders of polymer microparticles. In contrast, the mixing of heptane with 10,12 - pentacosanedioic acid (Samples 10 - 18) resulted in free - flowing powders of polymer microparticles. Color activation

[0147] Samples 1 - 18 were essentially white after synthesis. Subsequently, thin layers of the samples deposited on filter paper were activated by UV irradiation at 254 nm or continuous UV irradiation at 254 nm, followed by heating at 50°C or 150°C. The UV irradiation rapidly turned the samples blue (in less than 10 seconds). As shown in Figures 2A, 2B, 3A, and 3B below, heating at 50°C after UV irradiation formed red - magenta colors, and heating at 150°C formed yellow colors. After stopping the heating and returning the samples to room temperature, both the red / magenta and yellow colors persisted.

[0148] Figure 2A shows photographs of Samples 1-9 after UV irradiation at 254 nm. Figure 2B shows corresponding photographs of Samples 1-9 after UV irradiation and heat treatment at 50 °C. As shown, blue is obtained from the UV irradiation (grayscale image in Figure 2A and left side of the samples in Figure 2B). Heating a part of the sample on the filter paper formed red to magenta colors (grayscale image on the right side of the samples in Figure 2B). The variation in the color tone of the image is due to the non-uniformity of coverage caused by the non-uniform drying of the sample on the filter paper.

[0149] Similarly, Figure 3A shows photographs of Samples 10-18 after UV irradiation at 254 nm. Figure 3B shows corresponding photographs of Samples 10-18 after heat treatment at 50 °C or 150 °C after UV irradiation. As shown, blue is again obtained from the UV irradiation (grayscale image in Figure 3A and right side of the samples in Figure 3B). Heating a part of the sample on the filter paper to 50 °C formed red to magenta colors (grayscale image at the lower left side of the samples in Figure 3B). Further heating a part of the sample that had already been heated at 50 °C to 150 °C formed yellow (grayscale image at the upper left side of the samples in Figure 3B). Neither color changed when the sample was cooled. The variation in the color tone of the image is due to the non-uniformity of coverage caused by the non-uniform drying of the sample on the filter paper.

[0150] Among Samples 1-9, the brightest blue was obtained in the absence of silica nanoparticles and surfactant (Sample 1). Both anionic and cationic surfactants increased the intensity of the blue when silica was absent (Samples 2 and 3). When silica nanoparticles were present, the intensity of the blue further increased, and the strongest blue was obtained in the presence of AEROSIL R812S silica (Sample 6). In the presence of silica nanoparticles, anionic and cationic surfactants had a minimal effect on the intensity of the blue. After UV irradiation for various times, color space measurements for Samples 1-9 obtained using an XRITE 528 spectrophotometer are summarized in Table 2 below. For each irradiation time, L * (lightness), a * (green / yellow), and b* The (cyan / yellow) value was obtained. The color space measurements were in general agreement with qualitative visual observations. [Table 2]

[0151] Figure 4A is a plot of the color space lightness (L * ) of Samples 1, 2, and 3 as a function of irradiation time. Figure 4B is a plot of the color space lightness (L * ) of Samples 6, 7, and 8 as a function of irradiation time. Figures 5A and 5B are the corresponding plots of the color space cyan / yellow value (b * ) as a function of irradiation time. As shown, consistent color space lightness and color space cyan / yellow values were reached only after short irradiation times, and the presence of anionic or cationic surfactants had only a minimal effect on the values.

[0152] Figure 6 is a plot of the color space lightness (L * ) of Samples 1, 4, 5, 6, and 9 as a function of irradiation time. Figure 7 is the corresponding plot of the color space cyan / yellow value (b * ) as a function of irradiation time. As shown, various grades of silica nanoparticles imparted different degrees of lightness to the polymer microparticles, and all of these were more intense in color than the polymer microparticles without silica nanoparticles. The effect of different types of silica nanoparticles on the color space cyan / yellow value was not at all significant. At long irradiation times, the changes in color space lightness and color space cyan / yellow value were minimal.

[0153] Among Samples 10 - 18, the brightest blue was obtained again in the absence of silica nanoparticles and surfactant (Sample 10). In general, samples containing silica nanoparticles (Samples 13 - 18) gave a dark blue. The color space measurements for Samples 10 - 18 obtained using an XRITE 528 spectrophotometer after UV irradiation are summarized in Table 3 below. For each irradiation time, the L * (lightness), a * (green / yellow), and b * (cyan / yellow) values were obtained.

Table 3

[0154] The effects of thermal activation on Samples 10 to 18 are shown in FIGS. 8 to 10. FIG. 8 is a plot of the color space lightness (L * ) of Samples 10 to 18 according to the heating temperature. As shown in the figure, first, the blue samples (generated by UV irradiation) showed a slight decrease in color brightness when heated to 50°C and 150°C. FIGS. 9 and 10 show plots of the color space green / red value (a * ) and the color space blue / yellow value (b * ) of each of Samples 10 to 18 according to the heating temperature. As shown in the figure, the color space green / red value reached a peak at 50°C and then decreased for all samples except Samples 12, 14, and 18 (FIG. 9). The decrease in the color space green / red value (a * ) corresponded to the disappearance of red to magenta colors and the formation of yellow when further heated to 150°C for all samples except Samples 12, 14, and 18. The limited change in a * of Samples 12, 14, and 18 corresponded to the low degree of change in the visible color of these samples when heated to 150°C (FIG. 3B). Similarly, the color space blue / yellow value (b * ) of all samples except Samples 12, 14, and 18 increased during heating from 50°C to 150°C, corresponding to the visually observed internal growth of yellow (FIG. 3B).

[0155] All documents described in this specification are hereby incorporated by reference into this specification for the purposes of all jurisdictions in which such implementation is permitted, and include any priority documents and / or test procedures to the extent that they do not conflict with this text. As is apparent from the foregoing general description and specific embodiments, the forms of the present disclosure have been illustrated and described, but various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, the present disclosure is not intended to be limited thereby. For example, the compositions described herein may not include any components or compositions that are not explicitly listed or disclosed herein. Any method may omit any steps that are not listed or disclosed herein. Similarly, the term "comprising" is considered to be synonymous with the term "including". Whenever a method, composition, element, or group of elements is preceded by the transitional phrase "comprising", it is understood that the inventors also contemplate the same composition or group of elements preceded by the transitional phrases "consisting essentially of", "consisting of", "selected from the group consisting of", or "is" that precede the listing of the composition, element, or elements, and vice versa.

[0156] Unless otherwise indicated, all numbers representing properties such as components, molecular weights, and amounts such as reaction conditions used in this specification and the related claims should be understood to be modified in all cases by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximations that may vary depending on the desired properties sought to be obtained by the embodiments of the present invention. At a minimum, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the reported number of significant digits and by applying ordinary rounding techniques.

[0157] Whenever a numerical range having a lower limit and an upper limit is disclosed, any number and any included range within that range are specifically disclosed. In particular, all ranges of values (in the form of "from about a to about b", or equivalently "approximately a to b", or equivalently "from approximately a - b" as disclosed herein) are to be understood as reciting all numbers and ranges subsumed within the broadest range of values. Also, terms in the claims have their ordinary and customary meaning, unless explicitly and clearly defined by the patent owner. Additionally, when used in the claims, the indefinite articles "a" or "an" are defined herein to mean one or more of the elements they introduce.

[0158] One or more exemplary embodiments are presented herein. For clarity, not all features of a physical implementation are described or shown in this application. It is understood that in developing physical embodiments of the present disclosure, numerous implementation-specific decisions must be made to achieve the developer's goals, which vary by implementation and over time, such as compliance with system-related, business-related, government-related, and other constraints. Although much time may be spent in the developer's efforts, such efforts would be routine work for those of ordinary skill in the art having the benefit of this disclosure.

[0159] Accordingly, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The specific embodiments described above are merely exemplary and the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Further, it is not intended to be limited to the details of construction or design shown herein other than as described in the following claims. Accordingly, it is evident that the specific exemplary embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. Preferably, the embodiments exemplified herein may be practiced in the absence of any element not specifically disclosed herein and / or in the absence of any optional element disclosed herein. Another aspect of the present invention may be as follows. 〔1〕A particulate composition comprising: a plurality of thermoplastic microparticles containing a thermoplastic polymer, and a discoloring material associated with the thermoplastic microparticles, wherein the discoloring material is both photochromic and thermochromic. 〔2〕The particulate composition according to 〔1〕above, wherein the discoloring material contains one or more conjugated dienes. 〔3〕The particulate composition according to 〔1〕above, further comprising a plurality of nanoparticles disposed on the outer surface of each of the plurality of thermoplastic microparticles, the plurality of nanoparticles containing a plurality of oxide nanoparticles. 〔4〕The particulate composition according to 〔3〕above, wherein the plurality of oxide nanoparticles contain a plurality of silica nanoparticles. 〔5〕The particulate composition according to 〔1〕above, further comprising a surfactant associated with the outer surface of the thermoplastic microparticles. 〔6〕A printed matter comprising: a polymer matrix containing a thermoplastic polymer, and a discoloring material associated with the polymer matrix, the discoloring material being both photochromic and thermochromic. 〔7〕The printed matter according to 〔6〕above, wherein the discoloring material contains one or more conjugated dienes or a polymerized form thereof. 〔8〕The printed matter according to 〔7〕above, wherein at least most of the one or more conjugated dienes exist in the polymerized form, and the printed matter has a first colored state. 〔9〕The printed matter according to 〔8〕above, wherein the polymerized form is modified by heating, and the printed matter has a second colored state different from the first colored state. 〔10〕The printed matter according to 〔6〕above, further comprising a plurality of nanoparticles present in the polymer matrix, the plurality of nanoparticles containing a plurality of oxide nanoparticles. 〔11〕The printed matter according to 〔10〕above, wherein the plurality of oxide nanoparticles contain a plurality of silica nanoparticles. 〔12〕A method comprising: providing a particulate composition comprising a plurality of thermoplastic microparticles containing a thermoplastic polymer and a discoloring material associated with the thermoplastic microparticles, wherein the discoloring material is both photochromic and thermochromic. forming a printed matter having a polymer matrix containing the thermoplastic polymer and the discoloring material associated with the polymer matrix; A method comprising.

[13] Forming the printed matter comprises depositing the particulate composition in a powder bed; consolidating a portion of the thermoplastic particulates within the powder bed; The method according to

[12] above, comprising.

[14] The method according to

[12] above, further comprising exposing at least a portion of the printed matter to first activation conditions sufficient to convert the discoloring material to a polymerized form of the discoloring material having a first colored state.

[15] The method according to

[14] above, wherein the first activation conditions include light irradiation of the printed matter.

[16] The method according to

[15] above, further comprising exposing at least a portion of the printed matter to second activation conditions sufficient to convert the polymerized form of the discoloring material to a second colored state different from the first colored state.

[17] The method according to

[16] above, wherein the second activation conditions include heat treatment of the printed matter.

[18] The method according to

[12] above, wherein the discoloring material comprises one or more conjugated dienes.

[19] The method according to

[12] above, wherein the plurality of thermoplastic particulates further comprises a plurality of nanoparticles disposed on an outer surface of each of the plurality of thermoplastic particulates, and the plurality of nanoparticles comprises a plurality of oxide nanoparticles.

[20] The method according to

[19] above, wherein the plurality of oxide nanoparticles comprises a plurality of silica nanoparticles.

Claims

1. 1. A particulate composition comprising: a plurality of thermoplastic particulates comprising a thermoplastic polymer; and a color change material associated with the thermoplastic particulates, the color change material being both photochromic and thermochromic; A particulate composition, wherein said thermoplastic particles have an average particle size in the range of 1 μm to 1,000 μm, and said color change material is incorporated onto the outer surface of the thermoplastic particulate after its formation.

2. The particulate composition of claim 1 , wherein the color change material comprises one or more conjugated diynes.

3. a plurality of nanoparticles disposed on an outer surface of the thermoplastic particulate, the plurality of nanoparticles comprising a plurality of oxide nanoparticles; 2. The particulate composition of claim 1, wherein the oxide nanoparticles have a size ranging from 1 nm to 100 nm.

4. The particulate composition of claim 3 , wherein the plurality of oxide nanoparticles comprises a plurality of silica nanoparticles.

5. 10. The particulate composition of claim 1, further comprising a surfactant associated with the outer surface of said thermoplastic particulate.

6. 1. A method comprising: A particulate composition comprising a plurality of thermoplastic particulates comprising a thermoplastic polymer and a color change material associated with the thermoplastic particulates, the color change material being both photochromic and thermochromic; providing said thermoplastic particulates having an average particle size in the range of 1 μm to 1,000 μm, and said color change material is incorporated onto an outer surface of said thermoplastic particulates after their formation; forming a printed article having a polymer matrix including the thermoplastic polymer and the color change material associated with the polymer matrix; A method comprising:

7. forming the printed matter, depositing the particulate composition in a powder bed; consolidating a portion of the thermoplastic particulate in the powder bed; and The method of claim 6, comprising:

8. 7. The method of claim 6, further comprising exposing at least a portion of the printed article to first activation conditions sufficient to convert the color changing material to a polymerized form of the color changing material having a first colored state.

9. The method of claim 8 , wherein the first activation condition comprises illuminating the printed matter with light.

10. 10. The method of claim 9, further comprising exposing at least a portion of the printed article to second activation conditions sufficient to transform the polymerized form of the color changing material to a second colored state different from the first colored state.

11. The method of claim 10 , wherein the second activation condition comprises a heat treatment of the printed matter.

12. The method of claim 7 , wherein the color change material comprises one or more conjugated diynes.

13. the plurality of thermoplastic particulates further comprising a plurality of nanoparticles disposed on an outer surface of the thermoplastic particulate, the plurality of nanoparticles comprising a plurality of oxide nanoparticles; The method of claim 7, wherein the oxide nanoparticles have a size ranging from 1 nm to 100 nm.

14. The method of claim 13 , wherein the plurality of oxide nanoparticles comprises a plurality of silica nanoparticles.

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