阅读说明：本技术 稳定的化妆品墨组合物 (Stable cosmetic ink composition ) 是由 珍妮特·维拉洛博斯林戈斯 托马斯·埃利奥特·拉比 马修·约瑟夫·琳瑟 阿杰·苏贾 于 2019-02-01 设计创作，主要内容包括：化妆品墨组合物包含颗粒物质、(甲基)丙烯酸均聚物或其盐、以及流变改性剂。所述颗粒物质可具有约100nm至约2,000nm的粒度分布D50。所述(甲基)丙烯酸均聚物或其盐可具有小于约20,000道尔顿的重均分子量。所述流变改性剂可选自碱溶胀性乳液聚合物、疏水改性的碱溶胀性乳液聚合物、以及它们的组合。所述化妆品墨组合物可具有在25℃下测量的在0.1sec<Sup>-1</Sup>的剪切速率下大于约1,100cP的第一动态粘度和在25℃下测量的在1,000sec<Sup>-1</Sup>的剪切速率下小于约100cP的第二动态粘度。(A cosmetic ink composition includes a particulate material, a (meth) acrylic acid homopolymer or salt thereof, and a rheology modifier. The particulate material may have a particle size distribution D50 of about 100nm to about 2,000 nm. The (meth) acrylic acid homopolymer or salt thereof can have a weight average molecular weight of less than about 20,000 daltons. The rheology modifier may be selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof. The cosmetic ink composition may have a temperature at 25 ℃Measured at 0.1sec ‑1 A first dynamic viscosity of greater than about 1,100cP at a shear rate of and 1,000sec measured at 25 ℃ ‑1 A second dynamic viscosity of less than about 100cP at a shear rate of.)

1. A cosmetic ink composition comprising:

1 to 30 effective weight% of a particulate material having a particle size distribution D50 of 100 to 2,000 nm;

a (meth) acrylic acid homopolymer or salt thereof having a weight average molecular weight of less than 20,000 daltons; and

c. a rheology modifier, wherein the rheology modifier is selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof;

wherein the cosmetic ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity at a shear rate of greater than 1,100cP and a viscosity at 1,000sec measured at 25 ℃^-1A second dynamic viscosity of less than 100cP at shear rate.

2. The cosmetic ink composition of claim 1, wherein the particulate matter has a particle size distribution D90 of 700nm to 900 nm.

3. The cosmetic ink composition of any preceding claim, wherein the particulate matter comprises titanium dioxide, preferably wherein the titanium dioxide is substantially coated with a coating ingredient selected from silica, alumina, and combinations thereof.

4. The cosmetic ink composition of any one of the preceding claims, wherein the cosmetic ink composition comprises greater than 0.30 effective weight% rheology modifier.

5. The cosmetic ink composition of any preceding claim, wherein the homopolymer of (meth) acrylic acid or salt thereof has a weight average molecular weight of from 2,000 daltons to 5,000 daltons.

6. The cosmetic ink composition of any one of the preceding claims, further comprising one or more skin care actives selected from niacinamide, inositol, undecylenoyl phenylalanine, and combinations thereof.

7. The cosmetic ink composition of any one of the preceding claims, wherein the ink composition has a tan () of from 0.01 to 1.

8. The cosmetic ink composition of any one of the preceding claims, further comprising a preservative.

9. A cosmetic ink composition comprising:

1 to 30 effective weight% of a particulate material;

a (meth) acrylic acid homopolymer or a salt thereof; and

0.3 to 1 effective weight% of a rheology modifier, wherein the rheology modifier is selected from the group consisting of (meth) acrylate polymers, (meth) acrylate copolymers, and mixtures thereof, preferably wherein the ratio of (meth) acrylic acid homopolymer or salt thereof to rheology modifier is from 0.10 to 0.75;

wherein the cosmetic ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity at a shear rate of greater than 1,100cP and a viscosity at 1,000sec measured at 25 ℃^-1A second dynamic viscosity of less than 100cP at shear rate.

10. The cosmetic ink composition of claim 9, wherein the cosmetic ink composition has a neat pH of 7.5 to 9.0.

11. The cosmetic ink composition of claim 9 or 10, wherein the particulate matter has a particle size distribution D50 of 200nm to 350 nm.

12. A cosmetic ink composition comprising:

1 to 30 effective weight% of a particulate material having a particle size distribution D50 of 100 to 2,000nm, optionally having a particle size distribution D90 of 700 to 900 nm;

a (meth) acrylic acid homopolymer or salt thereof having a weight average molecular weight of less than 20,000 daltons; and

0.3 to 1 effective weight percent of a rheology modifier, wherein the rheology modifier is selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof;

wherein the cosmetic ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of 1,100cP to 10,000cP at a shear rate of (A) and 1,000sec measured at 25 DEG C^-1A second dynamic viscosity of 10cP to 100cP at shear rate.

13. The cosmetic ink composition of claim 12, wherein the cosmetic ink composition comprises from 0.01 to 1 effective weight percent of the (meth) acrylic acid homopolymer or salt thereof, preferably wherein the (meth) acrylic acid homopolymer or salt thereof is sodium polyacrylate.

14. The cosmetic ink composition of claim 12 or 13, wherein the particulate matter comprises a metal oxide.

15. The cosmetic ink composition of any one of claims 9 to 14, further comprising from 10 to 30 effective wt% of a humectant, preferably from 20 to 30 effective wt% of a humectant.

Technical Field

Described herein are ink compositions for inkjet printing applications, and more particularly, cosmetic ink compositions comprising particulate matter that exhibit long-term stability while still being suitable for high frequency printing by thermal and/or piezoelectric inkjet print heads.

Background

Most printing applications are designed for printing onto white substrates for document production or photo printing. For such applications, black ink is mainly used in combination with three or more colored inks. It is well known to formulate stable black and colored inks. For example, it is known that if a molecular dye is soluble in a carrier, it will generally not exhibit sedimentation over time. Furthermore, pigment-based black inks generally utilize particle sizes small enough to be suspended in low viscosity vehicles, and utilize stokes' law and brownian motion to keep the particles suspended. However, these inks exhibit very low opacity because the dyes are transparent in nature and pigment-based black inks use particle sizes small enough to be suspended but much smaller than the particle sizes required to scatter visible light. For shading purposes, optimal light scattering occurs at half the wavelength of light. Since the visible spectrum is in the range of about 400nm to about 700nm, the optimum particle size for light-blocking is about 200nm to about 350 nm. This is significantly larger than the particle size of stable black pigment-based inks used in consumer printing applications, which typically contain particles less than about 50nm in size.

For cosmetic printing applications, it is known that the ink must be sufficiently opaque to cover and/or hide skin imperfections. However, it is difficult to formulate opaque stable inks that can be jetted due to the particle size and content required to achieve opacity and gravity settling of the large and/or dense particles used to form such inks. In particular, it is challenging to formulate stable inks containing titanium dioxide, a common white pigment, that are substantially free of particle settling over the shelf life of the product. While there are several industries that typically use titanium dioxide in products that can exhibit long-term stability, these products generally have very high viscosities. For example, manually applied sunscreens and traditional cosmetic and/or skin care products contain titanium oxide particles and are stable; however, they can only do this by a viscosity that is several orders of magnitude greater than that of typical inkjet compositions and are incompatible with inkjet printers and/or cartridges.

For many years, the inkjet printing industry has attempted to produce stable white inks that can exhibit high frequency jetting, nozzle health, and/or drop placement accuracy. Current formulations utilize rheology modifiers and/or particle surface treatments to help slow the settling rate of the particles. However, the time frame for particle suspension in such formulations is only on the order of days or weeks. This may be useful for industrial applications where the printer operator only needs to re-suspend the particles by agitation every few days rather than every few hours. However, this does not enable the product to be sold to consumers in a typical retail environment where the product may need to be stable for months or years as it passes through the supply chain and is used by the consumer. Other formulation approaches have utilized titanium oxide with smaller particle sizes to slow the rate of sedimentation and/or have employed secondary particles such as hollow spheres to help provide some opacity. However, such formulations still settle within weeks and the opacity is much lower than inks using titanium oxide with a particle size of 200nm or more. Even the most stable white inks at present, if left undisturbed, exhibit particle settling over time. Manufacturers of such inks recommend redispersing the particles on a daily or weekly vigorous shaking basis and/or that these inks be recycled during use.

Accordingly, there is a need for opaque ink jet compositions with increased particle suspension stability for consumer cosmetic applications. In particular, there is a need for a cosmetic ink composition that contains particles that are large enough to produce opacity but remain in suspension, and that has a viscosity that is compatible with inkjet printer cartridge and nozzle technology.

Disclosure of Invention

A cosmetic ink composition, comprising: (a) a particulate material having a particle size distribution D50 of about 100nm to about 2,000 nm; (b) (meth) acrylic acid homopolymer or a salt thereof having a weight average molecular weight of less than about 20,000 daltons; and (c) a rheology modifier, wherein the rheology modifier is selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof; wherein the cosmetic ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of greater than about 1,100cP at a shear rate of and 1,000sec measured at 25 ℃^-1A second dynamic viscosity of less than about 100cP at a shear rate of.

A cosmetic ink composition, comprising: (a) about 1 to about 30 effective weight (wt)% of a particulate material; (b) (meth) acrylic acid homopolymer or a salt thereof; and (c) from about 0.3 to about 1 effective weight percent of a rheology modifier, wherein the rheology modifier is selected from the group consisting of (meth) acrylate polymers, (meth) acrylate copolymers, and mixtures thereof; wherein the ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of greater than about 1,100cP at a shear rate of and 1,000sec measured at 25 ℃^-1A second dynamic viscosity of less than about 100cP at a shear rate of.

A cosmetic ink composition, comprising: (a) a particulate material having particles of about 100nm to about 2,000nmDegree distribution D50; (b) (meth) acrylic acid homopolymer or a salt thereof having a weight average molecular weight of less than about 20,000 daltons; and (c) from about 0.3 to about 1 effective weight percent of a rheology modifier, wherein the rheology modifier is selected from the group consisting of alkali-swellable emulsion polymers, hydrophobically-modified alkali-swellable emulsion polymers, and combinations thereof; wherein the ink composition has a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of about 1,100cP to about 10,000cP at a shear rate of and 1,000sec measured at 25 ℃^-1A second dynamic viscosity of about 10cP to about 100cP at a shear rate of (a).

Drawings

While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description when taken in conjunction with the accompanying drawings, wherein:

fig. 1 is an exploded view of a personal care device for depositing a cosmetic ink composition as described herein; and is

Fig. 2 is an exploded view of a cartridge containing a cosmetic ink composition described herein.

Detailed Description

As used herein, "effective weight percent" and "weight% (effective)" refer to the amount of solids of the ingredient dissolved or suspended in water in the composition.

As used herein, "ambient conditions" refers to a temperature of about 23 degrees celsius (c) and a Relative Humidity (RH) of 50%.

As used herein, "particle size distribution D50" refers to a fifty percent distribution having a diameter with a smaller particle size.

As used herein, "particle size distribution D90" refers to a ninety percent distribution having a diameter of smaller particle size.

As used herein, "separation" refers to the formation of a layer of clarified fluid at the top of the sample, regardless of the uniformity of the particles in the sample below the layer of clarified fluid. Separation may include particle settling and/or syneresis.

As used herein, "settling" refers to the particles in the composition falling to the bottom of the container due to gravity (according to stokes' law). Particle settling can be affected by particle size and its agglomeration over time.

As used herein, "static storage" refers to storing a composition in the absence of vigorous or sustained shaking, stirring, or mixing prior to analysis or deposition of the composition.

As used herein, "syneresis" means phase separation, i.e., the extraction or drainage of liquid from a gel (in this case a weak colloidal gel). The particles in the composition exhibiting syneresis are still uniformly suspended below the clear fluid layer.

As used herein, "ratio of (meth) acrylic acid homopolymer or salt thereof to rheology modifier" refers to the ratio of the effective wt% of (meth) acrylic acid homopolymer or salt thereof divided by the effective wt% of rheology modifier.

As used herein, "storage modulus" or "G'" refers to a measure of stored energy that represents the elastic portion of the composition.

As used herein, "loss modulus" or "G" refers to a measure of energy as heat dissipation, which represents the viscous portion of the composition.

As used herein, "weight percent on addition" refers to the amount of total active plus water added to the composition.

As used herein, "zeta potential" refers to the zeta potential of a cosmetic ink composition.

As used herein, the articles "a" and "an" are understood to mean one or more of what is claimed or described, for example, "a rheology modifier" or "an active material".

All weights, measurements, and concentrations herein are measured under ambient conditions, unless otherwise specified.

All percentages, parts and ratios used herein are based on the total weight of the cosmetic ink composition, unless otherwise specified. Unless otherwise indicated, all such weights as they pertain to listed ingredients are based on the level at which they are added to the composition.

Cosmetic inks may require white or light-colored particulate matter containing particles that are large enough to be visually perceived by the human eye in order to produce opacity that masks skin imperfections. However, printing cosmetic ink compositions containing particulate matter of a size large enough to be visually perceptible can be a challenge with current inks, printers, and/or cartridges. These challenges are primarily caused by the settling of large dense particles and secondarily by the accumulation of settled particles in the barrel. Remixing by automatic mixing or hand shaking may be incompatible with the consumer's purpose of home or hand printing due to the vigorous and repeated remixing required to maintain uniform suspension of the particles.

Current opaque ink products may require repeated shaking, agitation, and/or rotation of the device and/or cartridge to keep the particles in uniform suspension. This can be inconvenient for the consumer and an additional step that the consumer may not perform as instructed. If the particles are not re-dispersed, the cosmetic ink composition may be non-uniform and/or the particles may become packed in the cartridge. Sedimentation can be minimized by adding rheology modifiers to the ink. However, if the viscosity of the cosmetic ink composition is not well controlled, clogging and flow rates through the microfluidic channels and nozzles can make printing difficult. The use of dispersants in cosmetic ink compositions can help control agglomeration (i.e., particles adhere to each other) and hard-packing of particles; however, such formulations still require shaking to redisperse the particles and do not exhibit particle suspension stability.

Cosmetic ink compositions and personal care devices for depositing cosmetic ink compositions that can exhibit long term particle suspension stability are described herein. In one aspect, "stable white ink" may refer to an ink that is substantially free of particle settling, wherein no agitation or mixing is required to use the ink for its application.

In one aspect, the cosmetic ink compositions described herein can be sprayed onto any surface, preferably a keratinous surface, including human skin and/or hair.

The cosmetic ink composition may comprise a unique combination of a rheology modifier and a homopolymer of (meth) acrylic acid or salt thereof, which combination may suspend a particulate material having particles large enough to be visually perceptible, but which may still be jettable. Careful balancing of particle agglomeration with viscosity of the cosmetic ink composition can be used to inhibit particle settling, thereby providing particle suspension stability beyond that previously reported, but without interfering with the ability of high frequency printing by thermal and/or piezoelectric inkjet printheads. One advantage of this is that the consumer or automated mechanical process requires little or no shaking and/or stirring of the cosmetic ink composition to redisperse the particles prior to and/or during printing. This may make the cosmetic ink composition more user-friendly in that it may not require the consumer to perform the additional step of redispersing the particles and/or may eliminate the need for stirring or rotating systems (including automated systems) within the printing device, cartridge, printer service station, and/or docking station.

Without being limited by theory, it is believed that the cosmetic ink composition may be stabilized using a homopolymer of (meth) acrylic acid or a salt thereof to minimize and/or prevent agglomeration of the particles, and a rheology modifier to introduce secondary structure and build viscosity to suspend the particles in the weak colloidal gel. The colloidal gel may be strong enough to keep the particles in suspension when not printing (thereby inhibiting particle settling), but weak enough to decompose during printing.

In particular, it has been found that cosmetic ink compositions comprise particulate matter, such as TiO₂A rheology modifier selected from the group consisting of alkali swellable emulsion ("ASE") polymers, hydrophobically modified alkali swellable emulsion ("HASE") polymers, and combinations thereof, and a (meth) acrylic acid homopolymer or salt thereof may be stable, yet still jettable in thermal and/or piezoelectric printers using standard cartridges and nozzles.

It was found that the cosmetic ink composition described herein can have a color of 0.1sec measured at 25 ℃^-1A first dynamic viscosity of greater than about 1,100cP at a shear rate, which prevents settling of the particles. It has also been found that a cosmetic ink composition can have a color of 1,000sec measured at 25 deg.C^-1A second dynamic viscosity of less than about 100cP at shear rates that may prevent clogging and flow rate problems through the barrel and/or nozzle. Without being limited by theory, it is believed that 0.1sec^-1The shear rate of (A) may represent storage conditions, however 1,000sec^-1The shear rate of (a) may be representative of the printing conditions.

In one aspect, there is no need to stir or shake the cosmetic ink composition to redisperse the particles before and/or during use, as the particles can remain suspended during the shelf life of the product.

Cosmetic ink composition

In one aspect, the cosmetic ink composition can be a skin care composition. When accurately and substantially only deposited on skin imperfections, the cosmetic ink composition may hide or mask skin imperfections, such as hyperpigmentation.

The cosmetic ink composition may be non-newtonian, meaning that the cosmetic ink composition may have a shear-dependent viscosity and/or viscoelastic properties. The cosmetic ink composition may exhibit a shear thinning effect under fluid ejection conditions in which the ink moves between the cartridge and the printhead of the inkjet device. When the cosmetic ink composition is jetted, the shear rate may increase, resulting in a decrease in viscosity. Thus, the cosmetic ink composition can be stored without particle settling, yet the viscosity and particle size are such that the cosmetic ink composition can still be printed.

The cosmetic ink composition may comprise a particulate material, a (meth) acrylic acid homopolymer or salt thereof, and a rheology modifier.

In one aspect, the particulate matter can be hydrophilic. In one aspect, the particulate matter may be substantially coated with one or more ingredients to render the particulate matter more hydrophilic. As used herein, "substantially coated" may mean a surface coverage of the particulate matter of at least about 25%, preferably greater than about 50%, more preferably greater than about 75%, and most preferably greater than about 90%. Suitable coating ingredients that can render the particulate material inherently hydrophilic can include silica, alumina, polyethylene glycol (PEG)12 polydimethylsiloxane, phytic acid, sodium glycerophosphate, and combinations thereof. The particulate material may be substantially coated with one or more coating ingredients using techniques known in the art. One advantage of using hydrophilic particulate matter is that the hydrophilic particulate matter can be more easily dispersed in water. In one aspect, the particulate matter may be titanium and/or iron oxide that has been substantially coated with silica and/or alumina.

Suitable particulate materials may include pigments; an encapsulated pigment; mica; clay; a mixed metal oxide pigment; metal oxides such as iron oxide, titanium dioxide, zinc oxide, aluminum hydroxide, iron oxide, and combinations thereof; boron nitride; silicon dioxide; talc; basic lead carbonate; magnesium silicate; barite (BaSO)₄) (ii) a Calcium carbonate; a pearlescent agent; colorants, including natural and synthetic monomeric and polymeric colorants; dyes, such as azo, indigo, triphenylmethane, anthraquinone and xanthine dyes, which are referred to as D&C and FD&C blue, brown, green, orange, red, yellow, etc. Insoluble metal salts of certified color additives, known as lakes. And combinations thereof.

In one aspect, the particulate matter can comprise titanium dioxide, iron oxide, and combinations thereof. In one aspect, titanium dioxide and/or iron oxide can be readily dispersed in water. In one aspect, the titanium dioxide and/or iron oxide is not hydrophobically treated prior to use in the cosmetic ink composition, as it may not readily disperse in water. Suitable particulate materials may include slurries or equivalents of titanium dioxide and iron oxide available from KOBO Products Inc (South Plainfield, NJ).

In one aspect, the cosmetic ink composition comprises a white pigment.

In one aspect, the cosmetic ink composition may have a white appearance. Alternatively, the cosmetic ink composition may have a white appearance with a red and/or yellow hue.

For opacity sufficient to mask and/or hide skin imperfections, a typical content of particulate matter may be about 30 effective weight percent. In one aspect, the cosmetic ink composition may comprise greater than about 15, alternatively greater than about 20, alternatively greater than about 30, effective weight percent of the particulate material. In one aspect, the cosmetic ink composition may comprise from about 1 to about 30, alternatively from about 3 to about 25, alternatively from about 5 to about 20, alternatively from about 8 to about 18, effective weight percent of the particulate material.

The particulate matter may comprise particles having a Particle Size Distribution (PSD) D50 of about 100nm to about 2,000nm, alternatively about 150nm to about 1,000nm, alternatively about 200nm to about 450nm, alternatively about 200nm to about 350 nm. In one aspect, the particulate matter may comprise particles having a PSD D90 of less than about 2 μm, alternatively less than about 1 μm. In one aspect, the particulate matter may comprise particles having a PSD D90 of about 700 μm to about 900 μm. Without being limited by theory, it is believed that if the particles are too large, they can clog the microfluidic channels of the cartridge and disrupt printing. Those skilled in the art will appreciate that acceptable particle sizes may vary depending on the printhead die configuration. In one aspect, the particulate matter may comprise any PSD as long as the particles can move through the microfluidic channels of the cartridge and/or printhead without causing clogging. The particle size distribution can be measured according to the particle size distribution method described below.

The particulate matter may have a refractive index between about 1.1 and about 5.0, alternatively about 1.5 to about 4, alternatively about 2 to about 3.

The particulate material may have a density range of about 1.5g/mL to about 6g/mL, or about 2g/mL to about 4 g/mL.

The cosmetic ink composition may comprise a rheology modifier. The rheology modifier may help prevent settling by keeping the particles in uniform suspension so that little or no agitation of the cosmetic ink composition is required.

One preferred group of rheology modifiers are ASE polymers. ASE polymers contain a balance of hydrophilic (meth) acrylic monomers and hydrophobic (meth) acrylate monomers and can be supplied as a liquid as a high volume solid. ASE polymers rely on a change from low pH to high pH (neutralization) to trigger thickening. The "trigger" is built into the polymer by producing a ratio of water-soluble (meth) acrylic acid and water-insoluble (meth) acrylate of about 50: 50. When the acid is not neutralized (low pH), the polymer is insoluble in water and does not thicken. When the acid is fully neutralized (high pH), the polymer becomes soluble and thickens. ASE polymers are supplied at low pH (<5) and maintain low viscosity at supply (<100cP) at up to 35% solids. ASE polymers solubilize, swell and thicken the composition by size exclusion when subjected to a pH of about 7 or higher. Thickening can be related to the molecular weight of the polymer. Since their properties depend on water absorption and swelling, the molecular weight of ASE polymers tends to be very high, which makes them effectively thickened. The resulting rheological behavior of ASE polymers is usually sharp shear thinning (pseudoplasticity), and ASE polymers are therefore well suited to build high viscosities at very low shear rates. Different rheological properties can be achieved by manipulating the molecular weight of the polymer, as well as the type and amount of acid and ester monomers.

In one aspect, the hydrophilic monomer of the ASE polymer may include (meth) acrylic acid and maleic acid. In one aspect, the hydrophobic monomers of the ASE polymer may include (meth) acrylic acid and C₁-to C₄Esters of alcohols, in particular ethyl acrylate, butyl acrylate and methyl methacrylate.

In one aspect, the ASE polymer may be synthesized from 10 to 90 wt% of the hydrophilic monomer a and 10 to 90 wt% of the hydrophobic monomer B. The structures of the hydrophilic monomer a and the hydrophobic monomer B are shown below.

Hydrophilic monomer A

Hydrophobic monomers B

Wherein R is₁And R₂Independently hydrogen or methyl;

wherein R is₃Is C₁To C₄An alkyl group.

Another group of rheology modifiers suitable for use in the cosmetic ink compositions described herein are HASE polymers. These are terpolymers based on ASE polymer chemistry by adding hydrophobic acrylate and/or vinyl ester monomers to the polymer composition. HASE polymers retain the pH-dependent behavior of their ASE counterparts, but in addition to absorbing water, they are also thickened by hydrophobic associations. This mechanism, known as associative thickening (i.e., association with any hydrophobic moiety in the composition), provides performance characteristics over a wider range of shear levels and enables a wider range of rheological characteristics than is available with size exclusion thickeners, such as ASE and cellulose compositions.

The hydrophilic and hydrophobic monomers of the HASE polymer may be the same as described with respect to the ASE polymer. The associating monomer of the HASE polymer may be a monomer showing strong hydrophobic properties. Preferred associative monomers are (meth) acrylic acid and C₈To C₂₂Esters of alcohols.

In one aspect, the HASE polymer may be synthesized from 10 to 90 wt% of hydrophilic monomer a, 10 to 90 wt% of hydrophobic monomer B, and 0.01 to 2 wt% of associative monomer C. The structure of the associating monomer C is shown below.

Associative monomer C

Wherein R is₄Is hydrogen or methyl;

wherein R is₅Is C₈To C₂₂An alkyl group;

wherein n is an integer of 0 to 50.

Alternatively, the HASE polymer may be synthesized from 10 to 90 wt% of hydrophilic monomer a, 10 to 90 wt% of hydrophobic monomer B, and 0.01 to 2 wt% of associative monomer D. The structure of the associating monomer D is shown below.

Associative monomer D

Wherein R is₆Is hydrogen or methyl;

wherein R is₇Is C₈To C₂₂An alkyl group.

In one aspect, the associative monomer may be selected from the group consisting of stearyl polyether-20 methacrylate, behenyl polyether-25 methacrylate, vinyl neodecanoate, and combinations thereof. In one aspect, more than one associative monomer may be used to synthesize the HASE polymer.

In one aspect, the ASE and HASE polymers may comprise a crosslinker. The crosslinking agent may contain at least two ethylenically unsaturated moieties, or at least three ethylenically unsaturated moieties. Suitable crosslinking agents may include divinyl benzene, tetra allyl ammonium chloride, allyl acrylates, methacrylates, diacrylates and dimethacrylates of diols and polyglycols, butadiene, 1, 7-octadiene, allyl-acrylamide, allyl-methacrylamide, bisacrylamidoacetic acid, N' -methylene-bisacrylamide, polyol polyallyl ethers such as polyallyl sucrose and pentaerythritol triallyl ether, and mixtures thereof.

In one aspect, the crosslinking agent can be present at a level of from about 25ppm to about 5,000ppm, alternatively from about 50ppm to about 1,000ppm, alternatively from about 100ppm to about 500 ppm.

Another group of rheology modifiers are hydrophobically modified ethylene oxide based urethane (HEUR) polymers. Unlike ASE or HASE-type rheology modifiers, HEUR polymers are nonionic and soluble at any pH. This solubility is due to the ethylene oxide backbone of the polymer, which is water soluble and constitutes the majority of the polymer structure. Thus, HEUR polymers require the hydrophobic moieties in the composition to interact with the ethylene oxide backbone to impart structure. The cosmetic ink composition may comprise a HEUR polymer. Alternatively, the cosmetic ink composition contains little or no hydrophobic moieties and no HEUR polymer.

The rheology modifier can be a (meth) acrylate polymer, a (meth) acrylate copolymer, and mixtures thereof. The rheology modifier may be selected from ASE polymers, HASE polymers, and combinations thereof. Suitable HASE polymers may include ACULYN^TMExcel；ACRYSOL^TMTT615；ACULYN^TM22；ACULYN^TM88; (all available from The DOW chemical company, Lake Zurich, IL); and combinations thereof. Suitable ASE polymers may include1125 (available from BASF Corporation, Charlotte, NC), ACULYN^TM33、ACULYN^TM38 (both available from The dow chemical Company, Lake Zurich, IL), and combinations thereof. The cosmetic ink composition may comprise an ASE polymer. Alternatively, the cosmetic ink composition may comprise a HASE polymer.

The rheology modifier does not consist of a surfactant, amine oxide and/or cellulose ether.

The cosmetic ink composition may comprise any amount of rheology modifier as long as it is measured at 25 ℃ for 0.1sec^-1At a shear rate of greater than about 1,100 cP. The cosmetic ink composition may comprise greater than about 0.30, alternatively greater than about 0.40, alternatively greater than about 0.50, effective weight percent of the rheology modifier. The cosmetic ink composition may comprise from about 0.30 to about 1, alternatively from about 0.30 to about 0.80, alternatively from about 0.40 to about 0.50 effective weight percent of a rheology modifier. Effective wt% can be measured using standard high performance liquid chromatography-mass spectrometry (HPLC-MS) techniques. One advantage of maintaining the level of rheology modifier within this range is that the viscosity of the cosmetic ink composition can be configured such that the particles can be suspended in the composition. The particles may be suspended at 25 ℃ for about 11 days or more, or at 25 ℃ for about 30 days or more, or at 25 ℃ for about 90 days or more, or at 25 ℃ for about 300 days or more. Without being limited by theory, it is believed that at levels of rheology modifier below this range, the particles may not be adequately suspended and settling may occur. If the level of rheology modifier is too high, the viscosity of the cosmetic ink composition may increase to a point where jetting may be affected (i.e., the cosmetic ink composition may not shear thinning enough to print effectively).

In one aspect, the cosmetic ink composition can be substantially free of neutral inorganic salts (e.g., as compared to alkali metal salt bases such as NaOH). Without being limited by theory, it is believed that neutral inorganic salts, such as calcium chloride or sodium chloride, can increase the ionic strength of the cosmetic ink composition and can disrupt the internal structure, thereby affecting stability. HASE and/or ASE polymers are known to become polyelectrolytes at high pH. As the pH increases, the carboxylic acid on the HASE and/or ASE polymer may be neutralized, thereby creating ionic groups on the polymer chains that may create electrostatic repulsion. These electrostatic repulsion can cause the polymer to swell and form internal structures in the composition. It is believed that inorganic neutral salts can shield this electrostatic repulsion and can cause HASE and/or ASE polymers to change structure and thus their effectiveness in promoting stability.

The cosmetic ink composition may comprise a (meth) acrylic acid homopolymer or a salt thereof. Non-limiting examples of acceptable salts can include sodium ions, potassium ions, ammonium ions, and mixtures thereof. The (meth) acrylic acid homopolymer or salt thereof may be a low molecular weight material that may be used to control particle size and may help maintain low viscosity of the cosmetic ink composition. The (meth) acrylic acid homopolymer or a salt thereof does not greatly increase the viscosity of the cosmetic ink composition. Non-limiting examples of suitable (meth) acrylic acid homopolymers or salts thereof may include sodium polyacrylates such as811D (available from RT Vanderbilt Holding company Inc., Norwalk, CT), ammonium polyacrylate having a weight average molecular weight of about 3,500 daltons, such as821A (available from RT Vanderbilt Holding Company Inc.), and combinations thereof. The (meth) acrylic acid homopolymer or salt thereof has a weight average molecular weight of less than about 20,000 daltons, preferably less than about 10,000 daltons, more preferably less than about 5,000 daltons. The cosmetic ink composition may comprise a composition having from about 1,000 daltons to about 20,000 daltons, or from about 1,000 daltons to about 10,000 daltons(meth) acrylic acid homopolymers of weight average molecular weight of about 2,000 daltons to about 5,000 daltons, or about 2,500 daltons to about 4,000 daltons, or salts thereof. Weight average molecular weight can be measured by standard high performance size exclusion chromatography according to ASTM method D5296-11 (9/1/2011).

In one aspect, the (meth) acrylic acid homopolymer or salt thereof is not a film-forming polymer. Without being limited by theory, it is believed that due to the low molecular weight, the (meth) acrylic acid homopolymer or salt thereof will not form a film.

The cosmetic ink composition may comprise from about 0.01 to about 1, alternatively from about 0.10 to about 0.85, alternatively from about 0.20 to about 0.75, alternatively from about 0.30 to about 0.65, effective weight percent of the (meth) acrylic acid homopolymer or salt thereof. Without being limited by theory, it is believed that the (meth) acrylic acid homopolymer or salt thereof can control the agglomeration of the particulate material by creating a negative surface charge around the particles, thereby controlling the particle size of the particulate material. Thus, the (meth) acrylic acid homopolymer or salt thereof can help maintain a particle size that is compatible with printer barrels and nozzles. Without being limited by theory, it is believed that cosmetic ink compositions comprising less than 0.01 effective weight% of a (meth) acrylic acid homopolymer or salt thereof may not have sufficient particle size control and/or the viscoelastic modulus may be too high to allow reliable refilling of the microfluidics.

The ratio of (meth) acrylic acid homopolymer or salt thereof to rheology modifier can be less than about 1. The ratio of (meth) acrylic homopolymer or salt thereof to rheology modifier can be from about 0.10 to about 0.75, alternatively from about 0.30 to about 0.65. Without being limited by theory, it is believed that if the content of the (meth) acrylic acid homopolymer or salt thereof is greater than the content of the rheology modifier, the rheology modifier may not be able to build the desired internal structure of the suspended particles. If the ratio of (meth) acrylic homopolymer or salt thereof to rheology modifier is too low, agglomeration may not be well controlled and the particle size may become too large to fit through a printer nozzle, resulting in printing difficulties.

Stability is believed to be inversely proportional to the amount of (meth) acrylic acid homopolymer or salt thereof and proportional to the amount of rheology modifier.

The cosmetic ink composition can have a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of greater than about 1,100cP at a shear rate of and 1,000sec measured at 25 ℃^-1A second dynamic viscosity of less than about 100cP at a shear rate of. The cosmetic ink composition can have a color of at 0.1sec measured at 25 ℃^-1A first dynamic viscosity of about 1,100cP to about 10,000cP, alternatively about 1,500cP to about 8,000cP, alternatively about 2,000cP to about 5,000cP at a shear rate of (a). The cosmetic ink composition can have a color of 1,000sec measured at 25 ℃^-1A second dynamic viscosity of about 10cP to about 100cP, or about 20cP to about 80cP at a shear rate of (a). Viscosity can be measured according to the viscosity test method described below. One advantage of having the first and second dynamic viscosities within this range is that at high shear rates, the cosmetic ink composition may decrease to a viscosity similar to that of a newtonian ink, but may still maintain a viscosity sufficient to suspend particles when not printing.

The cosmetic ink composition may have a color at 0.1sec^-1And a first dynamic viscosity ratio measured at 25 ℃ of 1,000sec^-1And a second dynamic viscosity of the cosmetic ink composition as measured at 25 ℃ of about 70% higher, alternatively about 80% higher, alternatively about 90% higher, alternatively about 95% higher. The cosmetic ink composition may have a color at 0.1sec^-1And a first dynamic viscosity ratio measured at 25 ℃ of 1,000sec^-1And a second dynamic viscosity of the cosmetic ink composition measured at 25 ℃ of about 25 times, or about 35 times, or about 50 times, or about 80 times.

The cosmetic ink composition may have a temperature-dependent viscosity. At an elevated temperature of about 70 ℃ for 1000sec^-1A lower viscosity is observed at shear rates of (a).

The cosmetic ink composition may have a storage modulus (G') of from about 2 to about 10, alternatively from about 3 to about 8, alternatively from about 4 to about 6. Without being limited by theory, it is believed that if the cosmetic ink composition has a G' greater than about 10, unsealing or starting after idle time in the print head may be difficult without intervention because the composition is too elastic. The storage modulus may be measured according to the oscillatory strain sweep method described below.

The cosmetic ink composition may have a loss modulus (G ") of from about 1 to about 5, alternatively from about 1.5 to about 4, alternatively from about 2 to about 3. The loss modulus can be measured according to the oscillatory strain sweep method described below.

The ratio of loss modulus to storage modulus, or tan (), is a useful indication of the degree of elasticity in a fluid. In this case, it may be a measure of the inherent stability of the cosmetic ink composition. When G "is higher than G', tan () is greater than about 1 and indicates viscosity dominated fluid behavior. When G' is higher than G ", tan () is less than about 1 and indicates elastic dominated fluid behavior.

The cosmetic ink composition may have a tan () of about 1. Alternatively, the cosmetic ink composition may have a tan () of less than about 1, or less than about 0.6. Without being limited by theory, it is believed that when tan () is less than about 0.6, particle settling can be minimized and/or prevented. The cosmetic ink composition may have a tan () of from about 0.2 to about 1, alternatively from about 0.4 to about 0.9, alternatively from about 0.6 to about 0.8.

The cosmetic ink composition may have a zeta potential of about negative 20 or less, or about negative 30 or less, or greater than about positive 20, or greater than about positive 30. The cosmetic ink composition may have a zeta potential of about negative 20 or less, or greater than about positive 20. One advantage of having a zeta potential in this range is that the surface charge of the particles can be increased, thereby preventing agglomeration of the particles. The zeta potential can be measured according to the zeta potential test method described below.

The cosmetic ink composition may have a neat pH of greater than about 7.5. The cosmetic ink composition may have a neat pH of from about 7.5 to about 9.0, alternatively from about 7.5 to about 8.5. Without being limited by theory, it is believed that syneresis can occur at a faster rate at a pH below about 7.5. It is believed that at lower pH, the equilibrium between the carboxylic acid and the carboxylate salt of the rheology modifier can be pushed towards the protonated acid and therefore not be useful for suspending the particles. It is believed that as the pH increases, the negative zeta potential becomes greater, thereby preventing agglomeration of the particles. The cosmetic ink composition may comprise a buffering agent for adjusting pH conditions. The buffer may be any basic excipient. In one aspect, the buffering agent can be a strong base, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and mixtures thereof. The neat pH of the cosmetic ink composition can be measured by standard methods known to those skilled in the art.

The cosmetic ink composition may have a surface tension of from about 25dyn/cm to about 60dyn/cm, alternatively from about 30dyn/cm to about 55dyn/cm, alternatively from about 40dyn/cm to about 50 dyn/cm.

The cosmetic ink composition may have an opacity of at least 0.2. In one aspect, the cosmetic ink composition may comprise an opacity of from about 0.2 to about 1, alternatively from about 0.25 to about 0.8, alternatively from about 0.3 to about 0.5.

The cosmetic ink composition may be substantially free of particle settling. Substantially free of particle settling may mean that the variation between the weight% solids at the top and bottom of a sample of the cosmetic ink composition is less than 5%, or less than about 3%, or less than about 1% at ambient conditions at 4 days post formulation. Particle sedimentation may be measured according to the particle sedimentation test method described below.

The cosmetic ink composition may be substantially free of particle agglomeration. Substantially free of particle agglomeration may mean that the cosmetic ink composition exhibits particle growth of less than about 25nm, alternatively less than about 15nm, alternatively less than about 10nm, per month at ambient conditions. The agglomeration rate may be determined by measuring the particle size over a period of time according to the particle size distribution method described below.

The cosmetic ink composition may have less than about 10%, alternatively less than about 5%, alternatively less than about 2%, alternatively less than about 1% separation at 11 days post formulation at 25 ℃. In one aspect, the cosmetic ink composition may have a separation of less than about 4mm, alternatively less than about 2mm, alternatively less than about 1mm, alternatively less than about 0.50mm at 11 days post formulation at 25 ℃. Separation can be measured according to the separation test method described below.

The cosmetic ink composition may have a shelf life of about 1 month, or about 3 months, or about 6 months, or about 12 months, or about 18 months, or about 24 months. As used herein, "shelf life" means the amount of time that the particles can remain uniformly suspended in the cosmetic ink composition under ambient conditions without shaking or stirring.

The cosmetic ink composition may also include a humectant as a carrier or base structure for other components in the cosmetic ink composition. One exemplary class of wetting agents can include polyols. Suitable polyols may include polyalkylene glycols and alkylene glycols and their derivatives, including propylene glycol, dipropylene glycol, polypropylene glycol, polyethylene glycol and their derivatives; sorbitol; hydroxypropyl sorbitol; erythritol; threitol; pentaerythritol; xylitol; (ii) a glucitol; mannitol; butanediol (e.g., 1, 3-butanediol); pentanediol; hexanetriol (e.g., 1,2, 6-hexanetriol); glycerol; ethoxylated glycerol; propoxylated glycerol; and mixtures thereof.

Other suitable wetting agents include sodium 2-pyrrolidone-5-carboxylate; guanidine, glycolic acid, and glycolate salts (e.g., ammonium and quaternary alkylammonium); lactic acid and lactate salts (e.g., ammonium and quaternary alkylammonium); aloe in any of a variety of forms (e.g., aloe gel); hyaluronic acid and its derivatives (e.g., salt derivatives such as sodium hyaluronate); lactamide monoethanolamine; acetamide monoethanolamine; urea; sodium pyroglutamate, water-soluble polyglycerol (meth) acrylate lubricants (such as

From BASF, Ludwigshafen, Germany); and mixtures thereof.

The cosmetic ink composition may comprise from about 1% to about 40%, alternatively from about 5% to about 35%, alternatively from about 10% to about 30%, alternatively from about 15% to about 20%, by effective weight of humectant. Alternatively, the cosmetic ink composition may comprise from about 20% to about 30% by effective weight of humectant.

Without being limited by theory, it is believed that at levels of about 20 effective wt% or more, the humectant can help prevent drying and/or clogging of the nozzle and/or cartridge when the cosmetic ink composition is not printed.

In one aspect, the humectant is present in an amount less than about 30% by active weight to promote a fast drying time of the cosmetic ink composition on the skin.

The cosmetic ink composition may be delivered alone or in the presence of a dermatologically acceptable carrier. As used herein, the phrase "dermatologically acceptable carrier" means that the carrier is suitable for topical application to keratinous tissue, has good aesthetic properties, is compatible with any additional components of the cosmetic ink composition, and/or will not pose any undue safety or toxicity concerns. In one aspect, the cosmetic ink composition is safe for use on the skin. In one aspect, the cosmetic ink composition does not comprise alkyd resins, celluloses, formaldehydes, phenolic resins, ketones, rubber resins, and combinations thereof, as such ingredients may not be compatible with use on human skin. In one aspect, the cosmetic ink composition may be hypoallergenic. Water is by far the most common carrier and is usually used in combination with other carriers. The carrier may be in various forms. Non-limiting examples include simple solutions (water or oil based) or emulsions. The dermatologically acceptable carrier may be in the form of an emulsion. Emulsions can generally be classified as having a continuous aqueous phase (e.g., oil-in-water and water-in-oil-in-water) or a continuous oil phase (e.g., water-in-oil and oil-in-water-in-oil). The oil phase may comprise silicone oils, non-silicone oils such as hydrocarbon oils, esters, ethers, and the like, and mixtures thereof. For example, emulsion carriers can include, but are not limited to, continuous aqueous phase emulsions such as silicone-in-water, oil-in-water, and water-in-oil-in-water emulsions, and continuous oil phase emulsions such as water-in-oil and water-in-silicone emulsions, and oil-in-water-in-silicone emulsions.

The cosmetic ink composition may comprise water, preferably deionized water. The cosmetic ink composition may comprise from about 40% to about 75%, alternatively from about 55% to about 70%, alternatively from about 60% to about 68%, by weight of the cosmetic ink composition, of water.

In addition, the cosmetic ink composition may optionally include an antifungal and/or antibacterial component. Examples of antifungal and/or antibacterial components may include isothiazolinones, such as methylisothiazolinone and methylchloroisothiazolinone.

The cosmetic ink composition may optionally include a preservative. Non-limiting examples of suitable preservatives can include phenoxyethanol, 1, 2-hexanediol, 1, 2-octanediol (available under the trade name of

68 commercially available from Symrise, AG, branch burg, NJ), farnesol, 2-methyl-5-cyclohexylpentanol, 1, 2-decanediol, and combinations thereof. The cosmetic ink composition may comprise from about 0.01% to about 10%, alternatively from about 0.1% to about 5%, alternatively from about 1% to about 3%, by weight of the cosmetic ink composition, of a preservative. One advantage of including a preservative is that it can help prevent microbial growth in the cosmetic ink composition, for example, when the cosmetic ink composition is contaminated with bacteria from the skin.

The cosmetic ink composition may comprise a monohydric alcohol. The cosmetic ink composition may comprise about 50ppm or more of the monohydric alcohol. The cosmetic ink composition may comprise from about 50ppm to about 10,000ppm, alternatively from about 100ppm to about 5,000ppm, alternatively from about 100ppm to about 1,000ppm of monohydric alcohols. Suitable monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol and 2-methyl-2-propanol.

A "safe and effective amount" means an amount of a compound or composition sufficient to elicit a positive benefit, but low enough to avoid serious side effects (i.e., to provide a reasonable benefit to risk ratio within the scope of sound judgment of the skilled artisan). a safe and effective amount of an active can be about 1 × 10^-6To about 25%, alternatively from about 0.0001 to about 20%, alternatively from about 0.01 to about 10%, alternatively from about 0.1 to about 5%, alternatively from about 0.2 to about 2%, all by weight of the cosmetic ink composition.

Suitable skin care actives include, but are not limited to, vitamins (e.g., B3 compounds such as niacinamide, nicotinic acid and tocopherol nicotinate, B5 compounds such as panthenol, vitamin A compounds and natural and/or synthetic analogs of vitamin A including retinoids, retinol, retinyl acetate, retinyl palmitate, retinoic acid, retinal, retinyl propionate and carotenoids (provitamin A), vitamin E compounds, or tocopherols including tocopherol sorbate and tocopherol acetate, vitamin C compounds including ascorbate salts, ascorbic acid esters and ascorbic acid derivatives of fatty acids such as magnesium ascorbyl phosphate and sodium ascorbyl phosphate, ascorbyl glucoside, and ascorbyl sorbate); peptides (e.g., peptides containing ten or fewer amino acids, their derivatives, isomers, and complexes with other substances such as metal ions); sugar amines (e.g., N-acetyl-glucosamine); a sunscreen agent; controlling an oiling agent; a tanning active; an anti-acne active; a desquamation active; an anti-cellulite active; a chelating agent; a skin lightening agent; a flavonoid; protease inhibitors (e.g., hexamidine and derivatives); non-vitamin antioxidants and free radical scavengers; salicylic acid; a hair growth regulator; an anti-wrinkle active substance; an anti-acne active; a mineral; phytosterols and/or phytohormones; a tyrosinase inhibitor; an N-acyl amino acid compound; inositol; undecylenoyl phenylalanine; a humectant; a plant extract; and derivatives of any of the above active substances; and combinations thereof. As used herein, the term "derivative" refers to a structure that is not shown but is understood by those skilled in the art to be a variation of the basic compound. For example, benzene removes one hydrogen atom and replaces it with a methyl group.

In one aspect, the cosmetic ink composition may comprise a peroxide, which includes hydrogen peroxide and/or benzoyl peroxide.

In one aspect, the cosmetic ink composition may comprise a skin care active selected from niacinamide; inositol; undecylenoyl phenylalanine; and combinations thereof.

In one aspect, the cosmetic ink composition is substantially free of latex polymer binder and/or film-forming polymer. In one aspect, the cosmetic ink composition comprises less than about 10%, alternatively less than about 1%, alternatively less than about 0.1%, of a latex polymer binder and/or a film-forming polymer. Without being limited by theory, it is believed that the latex polymer binder and/or the film-forming polymer can make printing difficult because these polymers can cure after evaporation and irreversibly clog the nozzle.

In one aspect, the cosmetic ink composition comprises from about 10% to about 30% solids. In one aspect, the cosmetic ink composition comprises less than 40% solids. Without being limited by theory, it is believed that at solids levels greater than 40%, such as in pre-painting or painting, printing can be difficult because high solids levels can lead to irreversible nozzle clogging.

In one aspect, the cosmetic ink composition may be removed with water, or with soap and water.

Personal care device

In one aspect, the cosmetic ink compositions described herein can be applied to the skin using a handheld personal care device. The personal care device may analyze the skin, identify skin imperfections, and deposit a cosmetic ink composition onto the identified skin imperfections in order to hide and/or mask the skin imperfections. An exemplary personal care device is described in us patent 9,522,101.

In one aspect, a personal care device may include a sensor configured to acquire at least one skin image and a processor configured to calculate an average background luminance value of the image with respect to a gray scale (the luminance value with respect to the gray scale is referred to herein as an "L value"). In addition, from the same image, local L values for a single pixel or group of pixels may be computed. The processor may then compare the local L value to the background L value to identify a skin blemish. When a skin blemish is identified, the processor may activate one or more nozzles to fire and dispense the cosmetic ink composition onto the skin blemish.

A skin imperfection is one in which the absolute value of the difference between the local L value and the background L is greater than a predetermined set Δ L ("Δ L)_S") is determined, the difference is defined as the measured Δ L (" Δ L_M"). The background L anywhere within the image may be preset or calculated. Will be fired at the nozzleImages were collected of the area of the cosmetic ink composition. The background L may be an arithmetic mean, median or average of a plurality of local ls, which means that the calculation may include all local ls in the image or a subset thereof.

Fig. 1 shows an exploded view of a personal care device 40. The physical spacer 42 of the personal care device 40 is located directly above the skin surface 18. The physical spacer 42 has a predetermined height α set such that when it contacts the skin surface 18, the mechanical and electrical elements are all at a known distance from the skin surface 18. In one aspect, the height α is from about 1mm to about 20mm, alternatively from about 3mm to about 15mm, alternatively from about 4mm to about 10 mm.

The mechanical and electrical elements associated with personal care device 40 may include, but are not limited to, a lamp 44, a sensor 46, a nozzle array 20 embedded on a cartridge die 57 attached to cartridge 52. Barrel die 57 is made of silicon, glass, machinable glass-ceramic, sapphire, alumina, printed wiring board substrate (e.g., liquid crystal polymer, polyimide, etc.), in which nozzle array 20 may be formed. The nozzle array 20 may be in a linear configuration, multiple rows, offset, sinusoidal, curved, annular, or zigzag arrangement, and combinations thereof. All of these elements may be enclosed in an optional equipment enclosure 41.

The light 44 may illuminate an area of the skin surface 18 within the physical spacer 42 such that the sensor 46 has a relatively constant illumination. The background illumination may affect the sensor 46 as portions of the physical spacer 42 lift away from the skin surface 18 and allow background light to enter and illumination from the lamp 44 to escape. If the lamp 44 is provided to provide relatively constant background illumination, small deviations in illumination may be corrected. In one aspect, the physical spacer 42 may be opaque. The lamp 44 may be an LED, incandescent lamp, neon lamp, or any other commercially available illumination source. The light 44 may have constant illumination or may have adjustable illumination. For example, if the background illumination is too bright or too dark, an adjustable light source may be used.

The sensor 46 may be any component capable of obtaining visual characteristics of the skin surface area. Non-limiting examples of sensors may include optical sensors, image capture devices, spectrophotometers, photonic measurement devices for wavelengths within the visible spectrum and those wavelengths above and below the visible spectrum that can measure subsurface features, and combinations thereof. The image capture device can be any of a variety of commercially available devices, such as a simple camera or a digital cmos camera chip. In one aspect, the image capture device may be a camera and may capture the image or convert it to a standard grayscale as is known in the art. It should be understood that any numerical scale measuring lightness to darkness can be considered "grayscale". Further, as used herein, "grayscale" is intended to be a linear scale, or a band or a visual attribute. For example, one "grayscale" visual attribute may be a single wavelength or a narrow wavelength that defines a particular visual color. Another example of a "grayscale" visual attribute may be a mixture of the average of the wavelength values of each pixel making up an image, such as a positive black, gray, or white image from an RGB mixture.

The sensor 46 may measure the L value of the skin surface 18 and/or the image of the skin surface 18 and may send it to the processor 50 via the image acquisition line 48 for analysis. The image may be analyzed for local L values, background L values, or both. The greyscale conversion may occur within the analysis processing capabilities of processor 50. Comparing background L with local L to determine Δ L_MOccurs in the processor 50, which may be a commercially available programmable chip or other commercially available processing unit.

The processor 50 is commonly referred to as a central processing unit ("CPU"). The CPU may be a single programmable chip such as those found in consumer electronics devices such as laptop computers, mobile phones, shavers, and the like. The CPU may include an Application Specific Integrated Circuit (ASIC), a controller, a Field Programmable Gate Array (FPGA), an integrated circuit, a microcontroller, a microprocessor, a processor, and the like. The CPU may also include memory functionality, either internal to the CPU as cache memory, such as Random Access Memory (RAM), Static Random Access Memory (SRAM), etc., or external to the CPU, such as Dynamic Random Access Memory (DRAM), Read Only Memory (ROM), static RAM, flash memory (e.g., compact flash cards or smart media cards), hard drives, Solid State Drives (SSDs), or internet cloud storage. While it is contemplated that a remote CPU connected to the personal care device or communicating wirelessly may be used, a local CPU within the personal care device is illustrated herein.

The images may be taken sequentially or preferably continuously. The image acquisition device may take images at a speed of at least 4 frames/second, or at least 100 frames/second, or at least 200 frames/second, or at least 600 frames/second.

The CPU processes at a rate of 100 frames/second, or greater than 200 frames/second, or greater than 600 frames/second.

The results of the image analysis, when compared to standards preprogrammed into the processor 50, may result in a desired treatment of the skin surface 18. For example, when calculated Δ L_MExceeding a predetermined Δ L_SAt this point, a signal is sent from the processor 50 to the cartridge 52 via the cartridge line 51 to fire one or more nozzles 21 in the nozzle array 20 and dispense the cosmetic ink composition.

Power for cartridge 52, light 44, sensor 46, processor 50, and other mechanical and electrical components that may be present, is supplied by power element 54 through one or more power lines 55. The power element 54, and thus the personal care device 40, can be turned off and on by a power switch 56, which can be located anywhere on the personal care device 40, but is shown here on the device cover 58. The power element 54 may include an energy storage function implemented by a battery, a rechargeable battery, an electrochemical capacitor, a double layer capacitor, an ultracapacitor, a hybrid battery-capacitor system, and combinations thereof.

Fig. 2 shows an exploded view of cartridge 52 including cartridge cover 62 and cartridge body 64. Cartridge body 64 may include a standpipe 66 generally enclosed within cartridge body 64 and defining a nozzle outlet 68. The optional filter 70 may help to keep oversized particles and other debris out of the nozzle array 20. The filter 70 and nozzle array 20 may be on opposite sides of the nozzle outlet 68. A cosmetic ink composition 74 may be contained within the cartridge body 64. The foam core 72 may at least partially fill the cartridge 64 and help regulate the back pressure of the cosmetic ink composition 74. The back pressure may be regulated by a bladder (not shown) and other methods known in the art. The foam core 72 shown here is just one example of how to help regulate the flow of cosmetic ink composition 74 through the filter 70 to the standpipe 66 and into the nozzle array 20. The connector 78 may provide power and signals to the nozzle array 20. The cosmetic ink composition 74 may be ejected from the cartridge 52 by a piezoelectric device, a thermal device, a mechanical pumping device, or a combination of these devices.

Exemplary cartridges for use herein may include the cartridges described in patent application US 2002/0167566.

There is no technical difference between the image for background L values and the image for local L values, the difference being in the analysis of the images. Thus, the images are continuously sent to the processor to calculate the L value and Δ L_MThe value is obtained. By "send", it is understood that each image preferably conveys at least 4 bits of data per pixel, and each local L value is preferably calculated using the 4-bit (or more) data packets.

It should be understood that the background L may be calculated once during the process, and the value may be reused throughout the process. Alternatively, it may repeat the calculation continuously as long as the process proceeds. Furthermore, there may be pre-programmed triggers to initiate a re-calculation of the background L. In addition, the context L may be retrieved from the processor memory for the current context L.

When Δ L_MBeyond a predetermined value, the cosmetic ink composition may deposit onto at least a portion of the skin blemish. More specifically, the cosmetic ink composition may be deposited by an array of nozzles, and the local L calculated along the length of the array of nozzles and within the firing range of the array of nozzles. A single nozzle may be fired to deposit the cosmetic ink composition, or multiple nozzles may be fired simultaneously. The number of nozzles fired along the nozzle array may be based on Δ L_MAnd the size of the skin blemish. Further, the nozzle firing frequency may be based on Δ L_MTo adjust in response to a larger Δ L_MValue, more drops are fired in succession.

The personal care device may deposit the cosmetic ink composition in the form of droplets having an average diameter of from about 0.1 μm to about 60 μm, alternatively from about 1 μm to about 50 μm, alternatively from about 5 μm to about 40 μm. Preferably, the cosmetic ink composition may be applied to the skin blemish in a discontinuous pattern of discrete droplets.

The cosmetic ink composition may be printed from a cartridge having a micro-electromechanical system (MEMS) that is different from typical consumer printing applications. Typical chamber heights and nozzle plate thicknesses are known to be about 25 μm to about 50 μm, as typical printing inks have a viscosity of less than about 10 cP. In one aspect, the cartridge may comprise a chamber height and nozzle plate thickness of about 10 μm to about 20 μm, preferably about 12 μm to about 17 μm. Without being limited by theory, it is believed that shorter chamber heights and plate thicknesses can help minimize viscous losses. Furthermore, most consumer printing applications are also optimized for printing at 10kHz or higher, and therefore ink formulations and microfluidics are designed to achieve rapid refill. However, operating the cosmetic ink compositions described herein at this frequency range may result in fluidization and/or de-priming due to swallowing of air.

The cosmetic ink composition may be printed using the following start-up sequence: the substrate is heated to about 60 ℃ for less than about 600ms, the nozzle is fired in a burst of about 100 to about 500 firings at a frequency of about 300Hz to about 1000Hz, and then low shear conditions are maintained with successive 4Hz firings. Although the nozzle may be activated with a different algorithm, the cosmetic ink composition may not transition from its viscous resting state to a flowing state.

Also described herein is a method for depositing a cosmetic ink composition onto skin. The method for depositing a cosmetic ink composition onto skin may comprise the steps of:

a. providing a personal care device comprising one or more nozzles and a cartridge operably associated with the one or more nozzles, wherein a cosmetic ink composition is disposed within the cartridge; and

b. depositing the cosmetic ink composition onto a portion of skin, wherein the cosmetic ink composition is deposited in a pattern of discrete droplets.

More specifically, a method for depositing a cosmetic ink composition onto skin may include the steps of:

a. providing a personal care device comprising an array of nozzles;

b. providing a background luminance (L) value;

c. obtaining a processed image of the skin and calculating at least one local L value for a single pixel or group of pixels within the processed image;

d. comparing the local L value to the background L value;

e. identifying a skin deviation in which an absolute value of a difference between the local L value and the background L value is greater than a predetermined set Δ L value; and treating the skin deviation with a cosmetic ink composition;

wherein the ink composition comprises a particulate material having a particle size distribution D50 of about 100nm to about 2,000 nm; (meth) acrylic acid homopolymer or salt thereof having a weight average molecular weight of less than about 20,000 daltons; and a rheology modifier, wherein the rheology modifier is selected from the group consisting of alkali swellable emulsion polymers, hydrophobically modified alkali swellable emulsion polymers, and combinations thereof; and wherein the ink composition has a color of at 0.1sec-¹A first dynamic viscosity at a shear rate of greater than about 1,100cP and a viscosity at 1,000 sec-measured at 25 ℃¹A second dynamic viscosity of less than about 100cP at a shear rate of.