Patent Description:
This disclosure generally relates to ink formulations, and associated methods and writing instruments, and more specifically relates to dry erase inks, and methods and writing instruments for using the same.

Dry erase ink formulations are known, and can be made in a wide variety of colors. However, different color pigments have different chemical and physical properties, and thus different dry erase ink formulations are required for different colorants. These different formulations often result in different colors of dry erase inks having different properties. For example, some colors erase better than others, dry more quickly than others, have better cap-off time, etc. These varying properties often frustrate users. As relevant prior art <CIT> and <CIT> may be cited.

Accordingly, improved dry erase ink formulations and associated methods and writing instruments are needed.

In one aspect, an ink formulation is provided, including a colorant encapsulated in a plurality of capsules, wherein the plurality of capsules include a release agent. The release agent is covalently bonded to the plurality of capsules and is a component according to claim <NUM>.

In another aspect, a method of erasing ink is provided, including erasing an ink formulation from a whiteboard or other dry erase surface, wherein the ink formulation includes a colorant encapsulated in a plurality of capsules, wherein the plurality of capsules include a release agent as defined in claim <NUM>.

In yet another aspect, writing instruments are provided, including a writing tip portion connected to a tubular member or refill, and an ink formulation including a colorant encapsulated in a plurality of capsules, wherein the plurality of capsules include a release agent as defined in claim <NUM>.

<FIG> illustrates a writing instrument according to an embodiment of the present disclosure.

Dry erase ink formulations, methods of using (e.g., erasing) dry erase ink formulations, and writing instruments including dry erase ink formulations are provided herein.

As used herein, the term "colorant" is used broadly to refer to a substance which imparts a desired color to an ink formulation. For example, a colorant may be a dye or pigment.

As used herein, "dry erase" when used to modify an ink formulation or portion thereof is used broadly to indicate that the ink formulation or portion thereof is configured to be applied to a whiteboard or dry erase board, and then later erased by rubbing or wiping without the need to apply any solvent.

As used herein, the term "erased" is used broadly to indicate that at least a portion of the colored components of an ink formulation has been removed from a substrate, or have been rendered colorless or transparent. As used herein, the phrase "substantially erased" is used broadly to indicate that substantially all of the colored components of an ink formulation have been removed from a substrate, or have been rendered colorless or transparent.

As used herein, "encapsulated" is used broadly to refer to a substance or core which is surrounded by a shell. For example, encapsulated materials include, but are not limited to, materials which are completely surrounded by an acrylic shell, such that the materials are isolated from any surrounding environment by the acrylic shell.

As used herein, "nanocapsules" is used broadly to refer to capsules having a maximum diameter of less than <NUM> nanometers.

As used herein, "microcapsules" is used broadly to refer to capsules having a maximum diameter of from <NUM> nanometers to about <NUM> micrometers.

Dry erase ink formulations are disclosed herein. In some embodiments, the ink formulation may contain one or more colorants encapsulated in a plurality of capsules. In some embodiments, the ink formulations disclosed herein have a longer dry time than conventional dry erase markers. That is, when disposed on a surface, the ink formulations disclosed herein take longer to dry than comparative ink formulations wherein the colorant is not encapsulated in a plurality of capsules as described herein. In some embodiments, the ink formulations have described herein have a dry time of from about <NUM> seconds to about <NUM> seconds, for example about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, about <NUM> seconds, and any ranges therebetween.

In some embodiments, the ink formulations disclosed herein have a longer cap off time when disposed in a marker type writing instrument than conventional dry erase markers. That is, when disposed in a dry erase marker and the marker tip is left uncapped, the ink formulations disclosed herein will have a longer cap off time than dry erase markers containing comparative ink formulations wherein the colorant is not encapsulated in a plurality of capsules as described herein. For example, in some embodiments, the ink formulations when disposed in a writing instrument having a marker tip, have an off cap time of more than <NUM> minutes, for example about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, or any ranges therebetween.

In some embodiments, the colorants may include a solvent dye dissolved in an organic solvent. For example, the colorants may include Solvent <NUM> dissolved in Magiesol Oil <NUM>, leucodyes dissolved in a fluid with an activator and a solid state wax, for example Crystal Violet dissolved in a phenolic resin and bees wax. In some embodiments, the colorants may include hydrophobically-treated colored pigments, such as hydrophobic carbon black, available from Degussa. The ink formulation may contain the colorant in an amount of from about <NUM> wt. % to about <NUM> wt. %, for example about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, or <NUM> wt. %, about <NUM> wt. %, or any ranges therebetween. According to dependent claim <NUM>, the ink formulation contains the colorant in an amount of from <NUM> wt. % to <NUM> wt.

In some embodiments, the plurality of capsules are acrylic capsules, melamine formaldehyde capsules, urea formaldehyde, ethyl cellulose, polyvinyl alcohol, gelatin, sodium alginate, or any combination thereof. In some embodiments, the capsules are nanocapsules or microcapsules.

In some embodiments, the encapsulated colorant is formed by the methods disclosed in <CIT>, entitled "Encapsulation,". In some embodiments, the encapsulated colorant is formed by the methods disclosed in <CIT>, entitled "Microencapsulation process,". In some embodiments, to facilitate the formation of an insoluble wall, complementary catalytic curing agents such as tertiary amines, mercaptans, isocyanates, and phenols are used. In some embodiments, the encapsulation process involves cation chain polymerization, and complementary catalytic curing agents such as boron trifluoride complexes, complex aromatic salts of Lewis acids such as diaryl iodonium, triarylsulfonium, or arene diazonium are used. In embodiments in which the interfacial polymerization results in polar functionalities such as hydroxyl or amine groups, these functional groups may be further reacted with alkoxysilanes with long chain carbons to attach the long alkyl functionalities covalently onto the surface of the capsules.

The plurality of capsules comprise a release agent, and may comprise more than one release agent. The release agent is covalently bonded to the plurality of capsules, and may be covalently bonded to a standard encapsulation material. The release agent comprises epoxy acrylate, polyester acrylate, polyether acrylate, urethane acrylate, <NUM>-(<NUM>-ethoxyethoxy) ethylacrylate, <NUM>-phenoxy ethyl acrylate, tetrahydrofurfuryl methacylate, ortho-phenoxy ethyl acrylate, pentaerythriol acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, benzyl acrylate, <NUM>,<NUM>,<NUM>-trimethylcyclohexyl acrylate, or any combinations thereof. In certain embodiments, the release agent is selected from: epoxy acrylate, polyester acrylate, polyether acrylate, and urethane acrylate release agents. For example, a suitable release agent may be selected based on the hardness, elasticity, toughness, abrasion resistance, adhesion, viscosity range, chemical resistance, and reactivity of the release agent for the specific application.

In some embodiments, the release agents identified above may be further modified to be compatible with the encapsulation process. For example, if the interfacial polymerization involves an anionic polymerization step, the release agent may include epoxy acrylate, polyester acrylate, polyether acrylate, or urethane acrylate modified with terminal epoxide functionalities.

In some embodiments, the ink formulation includes a resin. In some embodiments, the resin may include a variety of synthetic resin emulsions, such as aqueous dispersions of polyacrylic acid esters, styrene-acrylate copolymers, polyvinyl acetate, ethylenevinyl acetate copolymers, ethylene methacrylic acid copolymers, α-olefin-maleic acid copolymers, silicone resins, polyester and polyurethane, water-soluble resins such as polyvinyl alcohols, polyvinyl pyrrolidone and polyvinyl butyral, alkali-soluble resins such as styrenemaleic acid copolymers, ethylene-maleic acid copolymers and styrene-acrylate copolymers, oil-soluble resins such as ketone resins, ketone-formaldehyde resins, amide resins, alkyd resins, rosin-modified resins, rosin-modified phenol resins, phenol resins, xylene resins, polyvinyl pyrrolidone, α- and β-pinene-phenol polycondensation resins, polyvinyl butyral resins and acrylic resins.

In some embodiments, the resin is an acrylic resin. In some embodiments, the acrylic resin is a water-based acrylic resin, for example Joncryl® <NUM>, Joncryl® <NUM>, Joncryl® <NUM>, Joncryl® <NUM>, or combinations thereof, which are all available from BASF®.

In some embodiments, the ink formulation includes the resin in an amount of from about <NUM> wt. % to about <NUM> wt. %, for example about <NUM> wt. %, about <NUM> wt. %, about 20wt. %, about <NUM> wt. %, about <NUM> wt. %, or about <NUM> wt.

In some embodiments, the ink formulation includes a solvent. In some embodiments, the solvent is water. In some embodiments, the solvent is one or more alcohols, for example, benzyl alcohol, ethanol, n-propanol, n-butanol, diacetone alcohol, or combinations thereof. In some embodiments, the solvent is a water-soluble organic solvent, for example, 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 ethers propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, <NUM>-pyrrolidone, N-methyl-<NUM>-pyrrolidone and the like. In some embodiments, the solvent is an organic solvent, for example, naphtha, VM&P naphtha, refined solvent naphtha, petroleum sprit, xylene, methylisobutyl ketone, or butyl propionate.

In some embodiments, the ink formulation contains the solvent in an amount of from about <NUM> wt. % to about <NUM> wt. %, for example about <NUM> wt. %, about <NUM> wt. % solvent, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, about <NUM> wt. %, or any ranges therebetween.

In some embodiments, the ink formulation includes shear-thinning imparting agents, for example, nonionic surfactants having a specific HLB value, xanthan gum, welan gum, succinoglycan (organic acid-modified heteroglycan composed of glucose unit and galactose unit, having an average molecular weight of about <NUM> to <NUM>,<NUM>,<NUM>), guar gum, locust bean gum, hydroxyethyl cellulose, alkyl alginates, polymers mainly composed of alkyl methacrylate and having a molecular weight of <NUM>,<NUM> to <NUM>,<NUM>, glycomannan, hydrocarbons having a gelling ability and extracted from seaweed such as agar or carrageenan, benzylidenesorbitol or derivatives thereof, crosslinking acrylic acid polymers and the like, hydrophobically-modified ethoxylated urethane (HEUR) thickeners, alkalai-swellable emulsion (ASE) thickeners, hydrophobically-modified alkali-swellable emulsion (HASE) thickeners, associative thickeners, and non-associative thickeners are used alone or mixed in combination. In some embodiments, the ink formulation only includes shear-thinning imparting agents in an amount small enough to avoid affecting the Newtonian nature of the ink formulation. For example, in some embodiments, the ink formulation only includes shear-thinning imparting agents in an amount suitable to perform as a wetting agent.

In some embodiments, the ink formulation includes other additives such as pigments, binders, viscosity modifiers, thixotropic agents, preservatives, lubricants, pH adjustors, antiseptics or fungicides, wetting agents, defoamers, dispersants, surfactants, humectants, biocides, and the like.

In some embodiments, the ink formulation may be configured to be delivered from a marker type writing instrument, such as an Expo® marker.

In some embodiments, methods of using and erasing dry erase ink formulations are provided. In some embodiments, any of the ink formulations described above is disposed on a whiteboard or dry erase surface (e.g., via contacting a writing instrument containing the ink formulation to the surface such that the ink is delivered from the instrument to the surface), and then the ink is removed by the surface by rubbing or wiping with an erasing instrument. In some embodiments, the erasing instrument comprises dry cloth or felt.

In some embodiments, the ink formulations may be considered erased when each formulation would be considered erased by an average consumer. Thus, in some embodiments, determining whether an ink formulation has been erased may involve a qualitative determination.

In some embodiments, the erasure of the ink formulations described herein may be evaluated using the Likert scale, wherein write test samples may be evaluated before and after attempted erasing on a <NUM>-point scale. According to the Likert scale, <NUM> represents no color change, <NUM> represents slight discoloration, <NUM> represents moderate discoloration, <NUM> represents severe discoloration, and <NUM> represents complete color elimination. In some embodiments, the ink formulations may be considered erased when they are rated with a moderate discoloration, severe discoloration, or complete color elimination according to the Likert scale.

In some embodiments, the color of a surface with an ink formulation disposed thereon before and after erasure may be quantitatively evaluated with a color measurement instrument. In some embodiments the color measurement instrument may be a spectrophotometer, while in some embodiments the color measurement instrument may be a spectrodensitometer.

In some embodiments, color differences may be identified using the Commission Internationale de l'Eclairage (CIE) L*a*b* coordinates, wherein L* indicates lightness, a* is the red/green coordinate, and b* is the yellow/blue coordinate. The larger the L* value, the lighter the color, and the smaller the L* value, the darker the color. The larger the a* value, the redder the color, the smaller the a* value the greener the color. The larger the b* value, the yellower the b* value, and the smaller the b* value, the bluer the color. The color change of the ink formulation from its state before erasure (L*<NUM>, a* <NUM>, and b*<NUM>) and after erasure L*<NUM>, a* <NUM>, and b*<NUM> can be indicated by calculating ΔL*, Δa*, and Δb*, according to the formulas below: <MAT> <MAT> <MAT>.

A positive ΔL* will indicate that the sample became lighter after erasure while a negative ΔL* will indicate that the sample became darker after erasure. For example, a positive ΔL* when measuring the effect erasure on a colored dry erase ink on a white substrate may indicate that the dry erase ink was lightened by erasure.

A positive Δa* will indicate that the sample became redder erasure, while a negative Δa* will indicate that the sample became greener after erasure. For example, a positive Δa* when measuring the effect of erasure on a green dry erase ink on a white substrate may indicate that the green color of the dry erase ink was at least partially removed by erasure.

A positive Δb* will indicate that the sample became yellower after erasure, while a negative Δb* will indicate that the sample became bluer after erasure. For example, a positive Δa* when measuring the effect of erasure on a blue colored dry erase ink on a white substrate may indicate that the blue color of the dry erase ink was at least partially removed by erasure. As would be readily understood by one of skill in the art, measuring Δa* and Δb* may be particularly useful in evaluating the erasability of dry erase inks which are initially red or blue in color.

The total color difference between all three coordinates L*, a*, and b* can be evaluated by calculating the total color difference, ΔE*, according to the formula below: <MAT>.

In some embodiments, the ink formulations may be considered erased when write test samples of the ink on a white substrate exhibit a ΔE* value of from about <NUM> to about <NUM>, a ΔL* value of from about <NUM> to about <NUM>, a Δa* value of from about +/-<NUM> to about +/-<NUM>, a Δb* value of from about +/-<NUM> to about +/-<NUM>, or any combination thereof, including any ranges therebetween. For example, in some embodiments, the ink formulations may be considered erased when write test samples of the ink on a white substrate exhibit a ΔE* value of from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween. In some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a ΔL* value of from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween. In some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a Δa* value of from about -<NUM> to about <NUM>, from about -<NUM> to about -<NUM>, from about <NUM> to about <NUM>, from about -<NUM> to about -<NUM>, from about <NUM> to about <NUM>, from about -<NUM> to about -<NUM>, from about <NUM> to about <NUM>, for example about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween. In some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a Δb* value of from about-<NUM> to about -<NUM>, about <NUM> to about <NUM>, about -<NUM> to about -<NUM>, about <NUM> to about <NUM>, about -<NUM> to about -<NUM>, about <NUM> to about <NUM>, about -<NUM>, about - <NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about -<NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween.

In some embodiments, the color of an ink formulation before and after erasure may be evaluated using the CIE L*C*h coordinates, where L* indicates lightness, C* indicates chroma, and h is the hue angle. The color change of the ink formulation from its state before erasure (L*<NUM>, C* <NUM>, and h<NUM>) and after erasure L*<NUM>, C* <NUM>, and h<NUM> can be indicated by calculating ΔL*, ΔC*, and Δh, according to the formulas below: <MAT> <MAT> <MAT>.

In some embodiments, the ink formulations may be considered erased when the ink disposed on a substrate before and after erasure exhibits a ΔL* value of from about <NUM> to about <NUM>, ΔC* value of from about <NUM> to about <NUM>, a Δh value of from about <NUM>° to about <NUM>°, or any combination thereof, including any ranges therebetween. For example, in some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a ΔL* value of from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween. In some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a ΔC* value of <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or any ranges therebetween. In some embodiments, the ink formulations may be considered erased when the write test samples of the ink on a white substrate exhibit a Δh value of about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, or any ranges therebetween.

In some embodiments, writing instruments are provided. In some embodiments, the writing instruments include a writing tip portion connected to a tubular member or refill, and any of the ink formulations described above. In some embodiments, the writing tip portion is a marker.

Claim 1:
An ink formulation comprising a colorant encapsulated in a plurality of capsules, wherein the plurality of capsules comprises a release agent which is covalently bonded to the plurality of capsules, and wherein the release agent comprises epoxy acrylate, polyester acrylate, polyether acrylate, urethane acrylate, <NUM>-(<NUM>-ethoxyethoxy) ethylacrylate, <NUM>-phenoxy ethyl acrylate, tetrahydrofurfuryl methacrylate, ortho-phenoxy ethyl acrylate, pentaerythriol acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, benzyl acrylate, <NUM>,<NUM>,<NUM>-trimethylcyclohexyl acrylate, or any combination thereof.