KR102562352B1 - Thermochromic micro particles and thermochromic ink composition, writing apparatus and smart window using the same - Google Patents

Abstract

The present invention relates to thermochromic fine particles that can stably implement high color development and decolorization and have improved erasability, heat resistance, and chemical resistance, and a thermochromic ink composition using the same, a writing instrument, and a smart window.

Description

Thermochromic fine particles and thermochromic ink composition using the same, writing instrument and smart window

The present invention relates to thermochromic fine particles and a thermochromic ink composition using the same, a writing instrument and a smart window. More specifically, thermochromic fine particles capable of stably realizing high color development and decolorization in response to temperature changes and improved erasability, heat resistance, and chemical resistance, and thermochromic ink compositions using the same, writing instruments, and smart windows will be.

In general, ink for writing is divided into water-based ink and oil-based ink, and is made to maintain a written state for a long period of time by being absorbed or adhered to and fixed to a writing surface. The water-based ink and the oil-based ink for writing are absorbed or adhered to a writing surface (eg, paper or synthetic resin) to be fixed, and are not easily erased.

In a document prepared using a writing instrument using water-based ink and oil-based ink for writing, if a text correction or a typo needs to be corrected, the written text must be erased, but it is difficult to erase with an eraser for a general pencil. In addition, when erasing with a ballpoint pen eraser, the paper may be torn or deformed because the surface on which the water-based ink and the oil-based ink are fixed is ground and peeled off.

Accordingly, recently, a technique for producing ink using a material having a color change property in which a colorless compound exhibits color due to an external stimulus or, conversely, a colored compound turns colorless has been proposed. Examples of the external stimuli include heat, light, pressure, and the like. In particular, studies are being actively conducted to secure the erasability of ink by using a thermochromic compound that exhibits a color change from color to color when heat is applied. .

However, in the case of a thermochromic material that undergoes discoloration at a relatively high temperature, a heating device such as a hair dryer or hot water is required to erase ink, and thus, there is a limit that does not satisfy portability.

In addition, in the case of using a material capable of thermal discoloration due to body temperature or frictional heat from an eraser, there is a limit in that color development cannot be sufficiently maintained, such as discoloration progressing even at summer temperatures.

Accordingly, there is a need to develop a thermochromic composition having a discoloration temperature range that can be quickly erased by a simple and portable erasing method while maintaining excellent color development.

An object of the present invention is to provide thermochromic fine particles capable of stably implementing high color development and decolorization properties and having improved erasability, heat resistance and chemical resistance.

In addition, the present invention is to provide a thermochromic ink composition, a writing instrument, and a smart window using the thermochromic fine particles.

In the present specification, a phase change material including a phenolic compound containing an aliphatic functional group having 6 or more carbon atoms; And a dye; a core portion containing; and a shell layer including a polymer resin; thermochromic fine particles comprising a are provided.

In the present specification, a thermochromic ink composition including the thermochromic fine particles is also provided.

In the present specification, a thermochromic writing instrument including an ink storage container filled with the thermochromic ink composition is also provided.

In the present specification, a smart window is also provided, including a coating layer in which the thermochromic fine particles are dispersed.

Hereinafter, thermochromic fine particles according to specific embodiments of the present invention, a thermochromic ink composition using the same, a writing instrument, and a smart window will be described in detail.

According to one embodiment of the invention, a phase change material including a phenolic compound containing an aliphatic functional group having 6 or more carbon atoms; And a dye; a core portion containing; and a shell layer including a polymer resin; thermochromic fine particles comprising a may be provided.

When the present inventors use the above-described thermochromic fine particles, it is possible to realize decolorization according to temperature change while exhibiting high color development, and the temperature range in which the thermochromic color progresses is controlled by the phase change material, It is easy to maintain and can be quickly erased by a simple and portable erasing method, and it was confirmed through experiments that the invention was completed.

In addition, the phase change material included in the thermochromic microparticles has a chemical structure that can simultaneously serve as a color developer used for color development of existing dyes, so that a separate color developer is not added to the thermochromic microparticles. You may have the advantage of not having it.

In addition, when the thermochromic fine particles are used, even if they come into contact with chemically active substances such as acidic substances, basic substances, peroxides, or other solvent components, degradation of function can be prevented and heat resistance stability can be secured. there is.

The thermochromic fine particles of one embodiment described above can be used in various fields requiring thermochromic properties, and can be used, for example, in ink compositions, inks, pens, coating compositions, fibers, building materials, and the like.

In particular, the thermochromic fine particles may include a phase change material. As a material that absorbs and stores latent heat while changing its phase to solid-liquid or liquid-gas according to the phase change temperature, it can store or release heat through chemical bonding.

The phase change material (PCM) may include a phenolic compound including an aliphatic functional group having 6 or more carbon atoms. The phenol-based compound may include a phenol compound or a polyphenol compound and respective derivative compounds. The polyphenol compound may refer to a compound containing two or more hydroxyl groups.

The phenolic compound may include an aliphatic functional group having 6 or more carbon atoms. The aliphatic functional group having 6 or more carbon atoms may include a straight-chain or branched-chain alkyl group having 6 to 50 carbon atoms or 10 to 40 carbon atoms.

The phenolic compound including an aliphatic functional group having 6 or more carbon atoms may include a phenolic compound including an aromatic ring having 6 to 20 carbon atoms and an aliphatic functional group having 6 or more carbon atoms in which one or more hydroxyl groups are substituted. The phenolic compound containing an aliphatic functional group having 6 or more carbon atoms can realize phase transition characteristics by an aliphatic functional group having 6 or more carbon atoms, and can simultaneously implement the color development of lactone-based dyes by an aromatic ring having 6 to 20 carbon atoms substituted with one or more hydroxyl groups. can

That is, since the phenolic compound having an aliphatic functional group having 6 or more carbon atoms is a phase change material and can serve as a color developer at the same time, it may have an advantage of not requiring a separate color developer to be added to the thermochromic fine particles.

The aromatic ring having 6 to 20 carbon atoms substituted with one or more hydroxy groups may include an aromatic ring having 6 to 15 carbon atoms in which one hydroxy group is substituted or an aromatic ring having 6 to 10 carbon atoms in which three hydroxy groups are substituted.

More specifically, the phenolic compound containing an aliphatic functional group having 6 or more carbon atoms may include a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, at least one of R ₁ to R ₅ includes an aliphatic functional group having 6 or more carbon atoms, and the others may each independently be a hydroxyl group or hydrogen.

More specifically, in Formula 1, R ₁ is a carbonyl functional group to which an aliphatic functional group having 6 or more carbon atoms is bonded or an aromatic functional group to which an aliphatic functional group of 6 or more carbon atoms is bonded, and R ₂ to R ₅ may each independently be a hydroxyl group or hydrogen. there is.

The carbonyl functional group to which the aliphatic functional group having 6 or more carbon atoms is bonded may include a functional group represented by Chemical Formula 2 below.

[Formula 2]

In Formula 2, R ₆ is a straight-chain or branched-chain alkyl group having 6 to 20 carbon atoms, and A is a direct bond, oxygen, nitrogen, or sulfur. Specifically, R ₆ may be a straight chain alkyl group having 1 to 20 carbon atoms or a branched chain alkyl group having 4 to 20 carbon atoms, and '*' in Chemical Formula 2 may mean a direct bond.

In addition, the aromatic functional group to which the aliphatic functional group having 6 or more carbon atoms is bonded may include a functional group represented by Formula 3 below.

[Formula 3]

In Formula 3, R ₇ is a straight-chain or branched-chain alkyl group having 6 to 20 carbon atoms, and B is a direct bond, oxygen, nitrogen, or sulfur. Specifically, R ₇ may be a straight chain alkyl group having 1 to 20 carbon atoms or a branched chain alkyl group having 4 to 20 carbon atoms, and '*' in Chemical Formula 3 may mean a direct bond.

Preferably, in Formula 1, R ₁ is a functional group represented by Formula 2, R ₂ to R ₅ may all be hydrogen, R ₁ is an aromatic functional group represented by Formula 3, and R ₂ to R ₃ are hydroxyl groups, and R ₄ to R ₅ may be hydrogen.

Specific examples of the phenolic compound containing an aliphatic functional group having 6 or more carbon atoms include lauryl gallate or 4-alkoxy-4'-hydroxybiphenyl. .

In the thermochromic microparticles, the discoloration temperature range defined by the following general formula 1 may be 50 °C or more. Accordingly, the thermal discoloration of the dye is controlled, and it can be quickly removed by a simple and erasing method while maintaining excellent color development. Specifically, the thermochromic fine particles exhibit a large discoloration temperature range of 50 ° C. or more, defined by the following general formula 1, and the phase transition period in which the solid phase and liquid phase of the phase change material coexist is widened, and the color development or disappearance state before and after discoloration It is easy to maintain each.

[Formula 1]

Discoloration temperature range (T) = absolute value of the difference between the melting point and crystallization temperature of the material

The melting point (melting temperature, Tm) is a temperature at which a state change occurs from a solid to a liquid, and specifically means the lowest temperature at which the phase change material can exist in a complete liquid state. In addition, the crystallization temperature (Tc) means a temperature at which crystallization occurs or a heat treatment temperature required for crystallization, and specifically means the highest temperature at which the phase change material can exist in a complete solid state.

The phase change material may have a crystallization temperature of -20 °C to 0 °C, or -10 °C to 5 °C. In addition, the phase change material may have a melting point of 30 °C or higher, or 40 °C or higher, or 50 °C or higher.

In addition, the thermochromic fine particles may include a dye. The dye may be a lactone-based dye, and the lactone-based dye is a leuco dye and may exhibit thermochromic property. Examples of the lactone-based dye include a phthalide-based compound or fluoran system compounds etc. are mentioned.

The phthalide-based compound may include a phthalide compound or a derivative compound thereof, and the fluoran-based compound may also include a fluoran-based compound or a derivative compound thereof. there is.

Examples of the phthalide-based compound include a diphenylmethane phthalide-based compound, a phenyl indolyl phthalide-based compound, an indolyl phthalide-based compound, and a diphenylmethane azaphthalide-based compound.

More specifically, for example, 3,3-bis (p-dimethylamino phenyl) -6-dimethylamino phthalide, 3- (4-diethyl amino phenyl) -3- (1-ethyl- 2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3-bis (2-ethoxy-4-di Ethyl aminophenyl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethyl anilino)phenyl]-3-(1-ethyl-2-methylindol-3-yl)-4- Azaphthalide, 3,6-diphenyl amino fluoran, 3,6-dimethoxy fluoran, 3,6-di-n-butoxy fluoran, 2-methyl-6-(N-ethyl-N-p-tril amino) fluoran, 3-chloro-6-cyclohexylamino fluoran, 2-methyl-6-cyclohexylamino fluoran, 2-(2-chloro anilino)-6-di-n-butyl amino fluoran, 2-(3-trifluoromethyl anilino)-6-diethyl amino fluoran, 2-(N-methylanilino)-6-(N-ethyl-N-p-triyl amino) fluoran, 1,3- Dimethyl-6-diethyl amino fluoran, 2-chloro-3-methyl-6-diethyl amino fluoran, 2-anilino-3-methyl-6-diethyl amino fluoran, 2-anilino-3- Methyl-6-di-n-butyl amino fluoran, 2-xyrizino 3-methyl-6-diethyl amino fluoran, 1,2-benz-6-diethyl amino fluoran, 1,2-benz- 6-(N-ethyl-N-isobutylamino) fluoran, 1,2-benz-6-(N-ethyl-N-isoamylamino) fluoran, spiro[5H-(1) benzopyrano(2) ,3-d) pyrimidine-5,1'(3'H) isobenzofuran] -3'-one, 2-(diethylamino)-8-(diethylamino)-4-methyl-, spiro[ 5H-(1) benzopyrano (2,3-d) pyrimidine-5,1'(3'H) isobenzofuran] -3'-one,2-(di-n-butylamino)-8- (di-n-butylamino)-4-methyl-, spiro[5H-(1) benzopyrano(2,3-d) pyrimidine-5,1'(3'H) isobenzofuran]-3' -one,2-(di-n-butylamino)-8-(diethylamino)-4-methyl-, spiro[5H-(1) benzopyrano(2,3-d) pyrimidine-5,1 '(3'H)isobenzofuran]-3'-one,2-(di-n-butylamino)-8-(N-ethyl-N-i-amylamino)-4-methyl-, spiro[5H-( 1) Benzopyrano (2,3-d) pyrimidine-5,1' (3'H) isobenzofuran] -3'-one, 2-(di-n-butylamino)-8-(di- n-Butyl amino)-4-phenyl,3-(2-methoxy-4-dimethylamino phenyl)-3-(1-butyl-2-methylindol-3-yl)-4,5,6,7- Tetrachlorophthalide,3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophe Thalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-pentyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, etc. can be heard

In addition, the thermochromic composition may further include a pyridine-based, quinazoline-based, or bisquinazoline-based compound.

The content of the phase change material included in the thermochromic microparticles may be 10 wt% to 70 wt%, or 20 wt% to 70 wt% based on the weight of the thermochromic microparticles. Accordingly, in the thermochromic fine particles, the phase transition period in which the solid phase and the liquid phase of the phase change material coexist is widened, and it is easy to maintain each color development or discoloration state before and after discoloration.

The thermochromic fine particles may have a diameter of 0.1 μm to 10 μm. When the diameter of the thermochromic fine particles is excessively increased to more than 10 μm, dispersion stability may decrease when applied to ink or the like. On the other hand, if the diameter of the thermochromic fine particles is excessively reduced to less than 0.1 μm, it may be difficult to exhibit high-concentration color development.

The core part or the shell layer included in the thermochromic microparticles may further include an expansion agent or a contraction agent. The expander or shrinkage agent refers to a material capable of expanding or contracting by a specific external action, and is included in the core portion, the shell layer, or both the core portion and the shell layer of the thermochromic fine particles. The diameter of can be increased or decreased. In this way, by changing the size of the thermochromic microparticles according to the temperature, it is easy to reversibly or irreversibly control the color concentration of the thermochromic microparticles above a specific temperature, so that excellent color development can be realized.

Examples of the expanding agent are not particularly limited, but, for example, a low boiling point organic solvent may be used. The low boiling point organic solvent is a solvent having a boiling point of 90 ° C or less or 80 ° C or less, for example, isobutane (boiling point: about -11.7 ° C.), pentane (boiling point: about 36 ° C.), petroleum ether (boiling point: about 30 ~ 70° C.), hexane (boiling point: about 69° C.), and the like, and the low boiling point organic solvent easily volatilizes and generates gas when heated, thereby expanding the thermochromic fine particles.

Examples of the contraction agent are not particularly limited, but, for example, a polymer electrolyte (polyelectrolyte) may be used. The polyelectrolyte refers to a polymer having an electric charge, and includes a repeating unit containing an ionic or ionizable functional group, and the shape of the polymer chain can be changed by the degree of dissociation of the dissociation group or the ionic strength of the solvent.

The polymer electrolyte includes both a cationic polymer electrolyte and an anionic polymer electrolyte, and examples of the cationic polymer electrolyte include poly(diallyldimethylammonium chloride) [Poly(diallyldimethylammonium chloride), (PDADMA-Cl)]; Poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride); Poly(ethylenimine) [PEI )]; Poly(vinylamine), (PVAH); Poly(N-methyl vinylamine); Poly(allylamine), (PAH) )]; Poly (4-vinyl-1-methylpyridinium bromide) [Poly (4-vinyl-1-methylpyridinium bromide)]; Poly (allylammonium fluoride) [Poly (allylammonium fluoride)]; Co-epichlorohydrin) [Poly (dimethylamine-co-epichlorohydrin)]; Poly (lysine) [Poly (lysine)]; Methylenediammonium dibromide)[Poly(N,N,N',N′'-tetramethyl-N-trimethylenehexamethylenediammonium dibromide)];Poly(2-(dimethylamino-ethyl)methacrylate)[Poly(2-(Dimethylamino -ethyl)methacrylate)]; Poly(2-methacryloyloxy-ethyl-trimethylammonium chloride); Poly(2-hydroxy-3-methacryloxypropyl) -trimethylammonium chloride)[Poly(2-hydroxy-3-methacryloxypropyl-trimethylammonium chloride)];Poly(3-chloro-2-hydroxypropyl-2-methacryloxyethyl-dimethylammonium chloride)[Poly(3-chloro -2-hydroxypropyl-2-methacryloxyethyl-dimethylammonium chloride), (PCHPMEDMAC)];Poly(N-[3-(dimethylamino)-propyl methacrylamide]) ])}; and poly([3-methacryloylamino-propyl]-trimethylammonium chloride) [Poly([3-methacryloylamino-propyl]-trimethylammonium chloride)]. Examples of the anionic polymer electrolyte include polyacrylic acid. [Poly(acrylic acid), (PAA)]; Poly(methacrylic acid) (PMA); poly(itaconic acid); Poly(4-styrenesulfonic acid) (PSS); poly(vinylphosphonic acid); polyvinylsulfonic acid [Poly(vinylsulphonic acid)]; poly(aspartic acid); poly(glutamic acid); Poly(sodium 4-styrenesulfonate) (NaPSS); poly-anetholesulfonic acid [Poly(anetholesulfonic acid)]; Poly(3-sulfopropyl methacrylate); Poly(1,4-phenylene ether-sulfone sulfonic acid); or poly(1,4-phenylene ether ketone sulfonic acid) [Poly(1,4-phenylene ether ether ketone sulfonic acid)].

The thermochromic fine particles may include a core portion including a phase change material and a dye. In addition, the thermochromic fine particles may include a shell layer including a polymer resin. That is, the thermochromic fine particles may have a core-shell structure, and may have a form in which a mixture of a phase change material and a dye is impregnated into a polymer resin.

Examples of the polymer resin are not particularly limited, and various resins widely used in the field of manufacturing beads or microcapsules may be used without limitation, but, for example, melamine resin, urea resin, phenol resin, melamine-urea copolymer, and melamine - A phenol copolymer, an epoxy resin, or a mixture of two or more thereof may be used.

Examples of the method for producing the thermochromic fine particles are not particularly limited, but, for example, a known interface polymerization method, an in situ polymerization method such as a melamine-formalin method, a curing coating method in liquid, a phase separation method from an aqueous solution, A phase separation method from an organic solvent, a fusion dispersion cooling method, a suspension coating method in air, a spray drying method, and the like can be used without limitation.

Meanwhile, according to another embodiment of the present invention, a thermochromic ink composition including the thermochromic fine particles of the other embodiment may be provided.

The thermochromic ink composition may be prepared by using the thermochromic fine particles prepared in the above embodiment as a pigment and mixing solvents, resins, and other additives widely used in the conventional ink composition manufacturing field.

Information regarding the thermochromic fine particles includes the above-described information regarding the one embodiment.

Examples of the solvent include water, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether Acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, etc. are mentioned.

Examples of the resin include ketone resins, ketone formalaldehyde resins, amide resins, alkyd resins, rosin-modified resins, rosin-modified phenolic resins, phenolic resins, xylene resins, polyvinylpyrrolidone, α- and β-pinene phenols, polycondensation resins, polyvinyl butyral resins, acrylic resins, styrene maleic acid copolymers, cellulose derivatives, polyvinyl pyrrolidone, polyvinyl alcohol, dextrin and the like.

In addition, as other additives, a moisturizer, a thickener, a surfactant, a preservative, or a mixture of two or more thereof may be used.

Examples of the humectant include urea, glycerin, nonionic surfactant, reduced or non-reduced starch hydrolysate, oligosaccharides such as trehalose, sucrose, cyclodextrin, glucose, dextrin, sorbit, mannite, sodium pyrophosphate, and the like. can

As the thickener (or shear-sensing viscosity imparting agent), xanthan gum, welan gum, succinoglycan whose constituent monosaccharides are organic acid-modified heteropolysaccharides of glucose and galactose (average molecular weight of about 1 million to 8 million), arcagam, guar gum, locust Bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers with a molecular weight of 100,000 to 150,000 mainly composed of methacrylic acid alkyl esters, glucomannan, agar, carrageenan, etc. A thickener with the ability to change into a gel extracted from seaweed Polysaccharides, benzylidenesorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymers, inorganic microparticles, polyglycerin fatty acid esters, polyoxyethylenesorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene lanolin Nonionic surfactants with an HLB value of 8 to 12, such as lanolin alcohol, beeswax derivatives, polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, fatty acid amides, dialkyl or dialkenyl sulfosuccinic acids Clothing salts, a mixture of N-alkyl-2-pyrrolidone and anionic surfactant, and a mixture of polyvinyl alcohol and acrylic resin can be exemplified.

In addition, examples of the surfactant include higher fatty acids such as oleic acid, nonionic surfactants having long-chain alkyl groups, polyether-modified silicone oil, thiophosphorous acid tri(alkoxycarbonylmethyl ester) or thiophosphorous acid tri(alkoxycarbonylethyl ester) ), etc., phosphoric acid monoesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, phosphoric acid diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, and the like.

Examples of the preservative include phenolic acid, sodium salt of 1,2-benzthiazoline 3-one, sodium benzoate, sodium dihydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4 -(methylsulfonyl) pyridine etc. are mentioned.

Meanwhile, according to another embodiment of the present invention, a writing instrument including an ink storage container filled with the thermochromic ink composition of another embodiment may be provided. Although the example of the writing instrument is not greatly limited, for example, as shown in FIG. 5 below, the ink storage container 2 and the ballpoint pen tip 3 installed at the front end of the ink storage container 2 and the rear end The thermochromic ink composition 1 is filled, and at the rear end of the thermochromic ink composition 1, a cap type or knock type including an ink storage container 2 composed of a follower 4 that follows like ink It can be used for a writing instrument (7).

In addition, as shown in FIG. 6, a marking pen stores the thermochromic ink composition 1 in an ink occluder and marks it with a pen line, or as shown in FIG. 7, the thermochromic ink composition 1 is directly used as ink. It can also be used for writing instruments of direct-type marking pens stored in the storage container (2).

The thermochromic ink composition may be filled in the ink reservoir of the writing instrument, and an example of a method of filling the writing instrument with the thermochromic ink composition is not particularly limited, and is widely used in the field of manufacturing writing instruments using ink. A variety of methods may be used without limitation.

In addition, the writing instrument may further include a friction body or a heating body. The friction body refers to an object capable of generating frictional heat by generating appropriate friction when rubbed, and may be used to erase handwriting formed by the writing instrument. Examples of the friction body are not particularly limited, but, for example, an elastic body such as an elastomer or a plastic foam body, a plastic molded body, or a metal may be used.

The material of the friction body may include silicone resin or SBS resin (styrene butadiene styrene block copolymer), and the silicone resin is easy to attach to the erased part by abrasion, and the handwriting is not bounced when writing is repeated. Since there is a tendency, SBS resin can be used more preferably.

The heating element refers to an object that generates heat by receiving power from a battery, and may be used to erase handwriting formed by the writing instrument. Examples of the heating element are not particularly limited, and a material capable of generating heat by supplying electricity, for example, nichrome wire, or the like may be used.

The heating element may be used directly or may be used in a form wrapped with a cover. Examples of the cover are not particularly limited, but, for example, rubber or various materials having heat resistance and electrical insulation may be used.

The shape of the writing instrument is not significantly limited to the friction body or the heating element, and may be positioned while being coupled to the writing instrument. Portability can be improved by combining with the writing instrument. More specifically, as shown in FIG. 5 below, the friction body or heating element 5 may be coupled to the front end of the cap 6 of the writing instrument or coupled to the end of the barrel.

Meanwhile, according to another embodiment of the present invention, a smart window including a coating layer in which the thermochromic fine particles of the above embodiment are dispersed may be provided. Accordingly, the smart window can adjust the degree of absorption of light or heat by changing the transparency property of the glass while changing the color according to the external temperature by the coating layer formed on the surface of the glass.

Information regarding the thermochromic fine particles includes the above-described information regarding the one embodiment.

The coating layer may further include a binder resin to facilitate formation of the coating layer through adhesive force while dispersing the thermochromic fine particles. Examples of the binder resin are not particularly limited, but, for example, polyvinyl alcohol-based resins, polyurethane-based resins, polyester-based resins, and acrylic resins may be used. In addition, various polymeric resins widely used in the coating layer manufacturing field may be used without limitation.

As an example of a method of forming a coating layer on the smart window, a method of applying a binder resin in which the thermochromic fine particles are dispersed is applied to a surface of a glass window.

According to the present invention, a thermochromic ink composition that can stably implement high color development and decolorization and has improved erasability, heat resistance, and chemical resistance, and particles, inks, writing instruments, and smart windows using the same can be provided.

1 shows phase transition characteristics of thermochromic fine particles of Examples.
2 shows a SEM image of the surface of the thermochromic fine particles prepared in Example 1.
3 shows the thermochromic properties of the thermochromic ink composition of Example.
Figure 4 shows a schematic structure of a cap-type or knock-type writing instrument containing a thermochromic ink composition of an embodiment.
5 shows a schematic structure of an absorption-type marking pen including a thermochromic ink composition of an embodiment.
6 shows a schematic structure of a direct-type marking pen containing a thermochromic ink composition of an embodiment.

The invention is explained in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Examples 1 and 2: Preparation of thermochromic fine particles and ink composition>

Example 1

(1) Preparation of thermochromic fine particles

Using lauryl gallate, a phase change material, as a solvent, 1 g of lactone dye (Crystal violet lactone) was mixed, and an epoxy compound as a wall film material was emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution to form minute water droplets. After adding ethylenetriamine (Diethylenetriamine), stirring was continued at 70° C. for about 5 hours to obtain a suspension. Thereafter, the suspension was centrifuged to obtain thermochromic fine particles.

(2) Preparation of thermochromic ink composition

10% by weight of the thermochromic microparticles, 10% by weight of glycerin as a moisturizing agent, 0.5% by weight of Xanthan gum as a thickener, 1% by weight of a phosphate ester-based surfactant (trade name: PHOSPHANOL RS-410, manufactured by Toho Chemical Industry Co., Ltd., Japan), 65% by weight of water and 0.3% by weight of Proxel XL-2 as a preservative were mixed, dissolved and dispersed to obtain a thermochromic ink composition.

Example 2

(1) Preparation of thermochromic fine particles

Using phase change material 4-alkoxy-4'-hydroxybiphenyl as a solvent, 1 g of lactone dye (Crystal violet lactone) was mixed, and KER 828 (Epoxy resin, Kumho P&B Chemicals) was emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution to form fine water droplets, and after adding A-053 (manufactured by Kukdo Chemical Co., Ltd.) as a curing agent, stirring was continued at 70°C for about 5 hours to obtain a suspension. Thereafter, the suspension was centrifuged to obtain thermochromic fine particles.

(2) Preparation of thermochromic ink composition

10% by weight of the thermochromic microparticles, 10% by weight of glycerin as a moisturizing agent, 0.5% by weight of Xanthan gum as a thickener, 1% by weight of a phosphate ester-based surfactant (trade name: PHOSPHANOL RS-410, manufactured by Toho Chemical Industry Co., Ltd., Japan), 65% by weight of water and 0.3% by weight of Proxel XL-2 as a preservative were mixed, dissolved and dispersed to obtain a thermochromic ink composition.

<Comparative Examples 1 to 3: Preparation of thermochromic fine particles and ink composition>

Comparative Example 1

(1) Preparation of thermochromic fine particles

Thermochromic fine particles were obtained in the same manner as in Example 1, except that only 1-Hexanol was used as a solvent without a phase change material.

(2) Preparation of thermochromic ink composition

A thermochromic ink composition was obtained in the same manner as in Example 1.

Comparative Example 2

(1) Preparation of thermochromic fine particles

Thermochromic fine particles were obtained in the same manner as in Example 1, except that myristyl stearate was used as a solvent without a phase change material.

(2) Preparation of thermochromic ink composition

A thermochromic ink composition was obtained in the same manner as in Example 1.

Comparative Example 3

(1) Preparation of thermochromic fine particles

Thermochromic fine particles were obtained in the same manner as in Example 1, except that butyl stearate was used as a solvent without a phase change material.

(2) Preparation of thermochromic ink composition

A thermochromic ink composition was obtained in the same manner as in Example 1.

<Experimental example>

1. Crystallization temperature and melting temperature

For the thermochromic fine particles obtained in the above Examples and Comparative Examples, the crystallization temperature and melting temperature were measured using differential scanning calorimetry (DSC), and the results are shown in Table 1 below.

2. Phase transition characteristics

With respect to the thermochromic fine particles obtained in Examples 1 and 2, the phase composition according to the fraction of the phase change material (X _pha ) was measured, and the results are shown in FIG. 1.

As shown in FIG. 1, the thermochromic microparticles of Example have a crystallization temperature between -10 °C and -5 °C and a melting point above 50 °C. Accordingly, it can be confirmed that at 50 ° C. or higher, the color development of the thermochromic fine particles disappears and becomes colorless. This phase change characteristic is due to the phase change material included in the thermochromic fine particles, and it was confirmed that the color change temperature range of the dye is controlled by the phase change material.

In addition, it was confirmed that two phases consisting of a solid and a liquid coexist on the basis _of the boundary surface indicated by the curve in the graph of FIG. It was confirmed that the effect of maintaining the over-coloring property was increased.

3. Surface morphology

The surface morphology of the thermochromic microparticles obtained in Example 1 was confirmed through FE-SEM, and the results are shown in FIG. 2 below.

As shown in FIG. 2 below, it was confirmed that the thermochromic fine particles obtained in Example 1 were in the form of spherical particles having a diameter of 0.1 μm to 10 μm.

4. Thermochromic

Using the thermochromic ink compositions obtained in the above Examples and Comparative Examples, after drawing an image on paper at room temperature as shown in FIG. 3, the change in the image was observed by heating at a temperature of 50 ° C. Evaluated under the standard, it is shown in Table 1 below.

О: After heating to 50 ℃ temperature, the image is completely erased

△: After heating to a temperature of 50 ° C., the image remains without being partially erased.

X: Image not erased after heating to 50 ℃ temperature

division Crystallization temperature (℃) Melting temperature (℃) thermochromic Discoloration temperature range Example 1 -10 65 О 75 Example 2 -15 75 О 90 Comparative Example 1 - 30 to 35 X - Comparative Example 2 50 55 △ 5 Comparative Example 3 - 30 to 35 X -

As shown in Table 1, it was confirmed that the image drawn at room temperature using the thermochromic ink composition obtained in the above example was completely erased after heating at 50 ° C., indicating excellent thermochromic property.

On the other hand, in the case of Comparative Examples in which no phase change material was used, in Comparative Examples 1 and 3, crystallization temperature or melting temperature was not measured, so thermochromic property itself was not implemented, and in Comparative Example 2, the discoloration temperature range was less than 50 ° C. appeared, and it was confirmed that sufficient thermochromic property was not implemented.

Through this, it can be confirmed that the thermochromic ink composition of the above embodiment maintains excellent color development at room temperature, and discoloration occurs between room temperature and 50 ° C.

1: thermochromic ink composition
2: ink storage container
3: Ballpoint pen tip or pen line
4: followers
5: friction element or heating element
6: cap
7: writing instrument or applicator

Claims (18)

a core portion including a dye and a phase change material including a phenolic compound containing an aliphatic functional group having 6 or more carbon atoms; And a shell layer including a polymer resin;
The thermochromic microparticles comprising the phenolic compound having an aliphatic functional group having 6 or more carbon atoms include a compound represented by Formula 1 below:
[Formula 1]

In Formula 1, R ₁ is an aromatic functional group to which an aliphatic functional group having 6 or more carbon atoms is bonded, R ₂ to R ₅ are each independently a hydroxy group or hydrogen,
The aromatic functional group to which the aliphatic functional group having 6 or more carbon atoms is bonded includes a functional group represented by Formula 3 below,
[Formula 3]

In Formula 3,
R ₇ is a straight-chain or branched-chain alkyl group having 6 to 20 carbon atoms;
B is a direct bond, oxygen, nitrogen or sulfur.
According to claim 1,
Thermochromic fine particles having a discoloration temperature range of 50 ° C. or more, defined by the following general formula 1:
[Formula 1]
Discoloration temperature range (T) = absolute value of the difference between the melting point and crystallization temperature of a phase change material.
According to claim 2,
The crystallization temperature of the phase change material is -20 ℃ to 0 ℃, thermochromic fine particles.
According to claim 2,
The melting point of the phase change material is 30 ℃ or more, thermochromic fine particles.
According to claim 1,
The phenolic compound containing an aliphatic functional group having 6 or more carbon atoms includes a phenolic compound including an aromatic ring having 6 to 20 carbon atoms and an aliphatic functional group having 6 or more carbon atoms in which one or more hydroxyl groups are substituted.
delete delete delete delete According to claim 1,
The content of the phase change material is 10% to 70% by weight, thermochromic fine particles.
According to claim 1,
The dye is a lactone-based dye, thermochromic fine particles.
According to claim 11,
The lactone-based dye includes a phthalide-based compound or a fluoran-based compound, thermochromic fine particles.
According to claim 1,
The thermochromic fine particles have a diameter of 0.1 μm to 10 μm, thermochromic fine particles.
According to claim 1,
The polymer resin comprises at least one selected from the group consisting of melamine resin, urea resin, phenol resin, melamine-urea copolymer, melamine-phenol copolymer and epoxy resin, thermochromic fine particles.
According to claim 1,
The thermochromic fine particles, wherein the core portion or the shell layer included in the thermochromic fine particles further includes an expanding agent or a shrinking agent.
A thermochromic ink composition comprising the thermochromic fine particles of claim 1.
A writing instrument comprising an ink storage container filled with the thermochromic ink composition of claim 16.
A smart window comprising a coating layer in which the thermochromic fine particles of claim 1 are dispersed.