WO2018199971A1

WO2018199971A1 - Inks with a near infrared scattering pigment

Info

Publication number: WO2018199971A1
Application number: PCT/US2017/029970
Authority: WO
Inventors: Fred Charles Thomas, Iii; Paul Howard Mazurkiewicz; Steven STEINMARK; Felicia POWERS
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2017-04-27
Filing date: 2017-04-27
Publication date: 2018-11-01

Abstract

According to an example, an ink may include a near infrared scattering pigment coated with a visibly opaque and infrared transparent dye.

Description

INKS WITH A NEAR INFRARED SCATTERING PIGMENT

BACKGROUND

[0001] Users are increasingly demanding functionalities beyond merely recognizing a touch to the surface of a touch-sensitive device. Such other functionalities include handwriting recognition and direct note taking (using, for example, a stylus). Such functionalities are generally provided in so-called digitizing systems. Digitizing systems may have position-dependent indicia defected by an image sensor in a stylus, such as an electro-optical pen or other image reader, where the position-dependent indicia include an ink.

BRIEF DESCRIPTION OF THE DRAWING

[0002] Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:

[0003] FIG. 1 is a simplified diagram of an example ink;

[0004] FIG. 2 is a simplified diagram of an example display;

[0005] FIG. 3 is a flow chart of an example method of making an ink; and

[0006] FIG. 4 is a graph of the reflectance of the ink made in Example 2.

DETAILED DESCRIPTION

[0007] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough

understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure. As used herein, the terms "a" and "an" are intended to denote at least one of a particular element, the term "includes" means includes but not limited to, the term "including" means including but not limited to, and the term "based on" means based at least in part on.

[0008] With reference first to FIG. 1 , there is shown a simplified diagram of an example ink 100. The ink 100 may include near infrared scattering pigment 120 doped or coated with a visibly opaque and infrared transparent dye 130. The ink 100 may also include a carrier 1 10. The near infrared scattering pigment 120 disclosed herein may be reflective in the visible wavelength spectrum. For this reason, the near infrared scattering pigment 120 may be coated or doped with the visibly opaque and infrared transparent dye 130 so that the resultant ink 100 may reduce reflection of the pigment 120 in the visible spectrum relative to the near infrared wavelength spectrum. The ink 100 may not, noticeably, to the human observer, impact color, such as color-shifting, in the visible wavelength spectrum. The ink 100 may have a visibly gray or black color that may reduce a positionally encoded display's ambient light backscatter haze, sparkle, coloration distortion, and may increase the general display image visibility to a user.

[0009] The near infrared scattering pigment 120 may include any metal that has a reflective surface. In an aspect, the metal may be any metal from the periodic table of elements, including but not limited to, aluminum, magnesium, silver, nickel, copper, iron, titanium, chromium, cobalt, tin, indium, gold, lead, platinum, zinc, and the like. The near infrared scattering pigment 120 may include a metal alloy or a metal oxide. Non-limiting examples of metal oxides include aluminum oxide, antimony trioxide, antimony tetroxide, antimony pentoxide, arsenic trioxide, arsenic pentoxide, barium oxide, bismuth(iii) oxide, bismuth(v) oxide, calcium oxide, cerium oxide, chromium(ii) oxide, chromium(iii) oxide, chromium(iv) oxide, chromium(vi) oxide, cobalt(ii) oxide, cobalt(ii,iii) oxide, cobalt(iii) oxide, copper(i) oxide, copper(ii) oxide, indium oxide, iron(ii) oxide, iron(ii,iii) oxide, iron(iii) oxide, lead(ii) oxide, lead(ii.iv) oxide, lead(iv) oxide, lithium oxide, magnesium oxide, manganese(ii) oxide, manganese(iii) oxide,

manganese(iv) oxide, manganese(vii) oxide, mercury(ii) oxide, nickel(ii) oxide, nickel(iii) oxide, rubidium oxide, silicon dioxide, silver(i) oxide, thallium(i) oxide, thallium(iii) oxide, tin(ii) oxide, tin(iv) oxide, zinc oxide, titanium dioxide, or combinations thereof.

[0010] The near infrared scattering pigment 120 may be any pigment that is visibly white-colored. Non-limiting examples of a white-colored pigment 120 for use in the ink 100 include titanium oxides, zinc oxide, zinc sulphides, zirconium oxide, silicon dioxide, aluminum oxides, white lead, basic lead sulfate, barium sulfate, calcium carbonate (precipitated, ground, and treated), calcium silicate, kaolin clay, talc, silica, and combinations thereof. In an aspect, the white-colored inorganic pigment 120 may include sodium aluminosilicate particles,

aluminum-doped zinc oxide, zinc dioxide, titanium dioxide,

polytetrafluoroethylene, or combinations thereof.

[0011] The near infrared scattering pigment 120 may be in any form or shape, such as a particle, a nanoparticle, a flake, a crystal, a powder, and the like.

[0012] The near infrared scattering pigment 120 may be doped or coated with a visibly opaque and infrared transparent dye 130 in order to reduce the pigment's 120 visible spectrum reflectance while only marginally reducing the near infrared reflectance.

[0013] The visibly opaque and infrared transparent dye 130 (VOIRT) may block or absorb light in the visible wavelengths and may allow transmission of light in the infrared, such as the near infrared, wavelength. To the extent that absorbance information is not generally published or available for specific dyes, it may be readily determined by measurement with a spectrophotometer. [0014] A suitable VOIRT dye 130 may be available, for example, from HW Sands (ADA6212, SDA4549, SDB5984, SDA5989 and ADA 4827), Bayer Chemical (Makrolon 2407 971000, Makrolon 2407 970401 , Makrolon AX2477 900346 and Makrolon 2407 770359) Epolin (Spectre 100, Spectre 1 10 and Spectre 120), and QRC Solutions (VOD675S, VOD695S and VOD835S).

Combinations of VOIRT dyes 130 may also be used.

[0015] The VOIRT dye 130 may be present in the ink 100 in a minor amount. In an aspect, the VOIRT dye 130 may be present in an amount ranging from about 0.5 wt.% to about 30 wt.%, for example, from about 10 wt.% to about 17 wt.%, and as a further example, from about 12 wt.% to about 25 wt.%, relative to the total weight of the ink 100.

[0016] In an aspect, any amount of VOIRT dye 130 may be used so long as the ink 100 has a neutral gray coloration and the ink 100 has significantly reduced reflect light in the visible wavelength spectrum (400-700 nm). For example, a near infrared scattering pigment 120 having a native white color, such as zinc oxide, may be doped with a VOIRT dye 130, such as ADA6212 (HW Sands), having a native black color so that the resultant ink 100 has a gray color. In another aspect, a near infrared scattering pigment 120 having a native silver metallic color, such as silver oxide flakes, may be coated with a VOIRT dye 130, such asADA6212 (HW Sands) , having a native black color so that the resultant ink 100 has a gray color. A colorimeter such as an X-Rite may be used to tune the neutral gray coloration to a black coloration, if necessary. In particular, additional amounts of the VOIRT dye 130 may be combined with the near infrared scattering pigment 120 until the selected gray color has been achieved.

[0017] The ink 100 may further include a carrier 1 10, such as a clear carrier or clear resin. By way of non-limiting examples, the carrier 1 10 may be polyvinyl alcohol, polyvinyl acetate polyvinylpyrrolidone, poly(ethoxyethylene), poly(methoxyethylene), poly(acrylic) acid, poly(acrylamide), poly(oxyethylene), poly(maleic anhydride), hydroxyethyl cellulose, cellulose acetate,

poly(saccharides) such as gum arabic and pectin, poly(acetals) such as polyvinylbutyral, polyvinyl halides) such as polyvinyl chloride and polyvinylene chloride, poly(dienes) such as polybutadiene, poly(alkenes) such as

polyethylene, poly(acrylates) such as polymethyl acrylate, poly(methacrylates) such as poly methylmethacrylate, poly(carbonates) such as poly(oxycarbonyl oxyhexamethylene, poly(esters) such as polyethylene terephthalate,

poly(urethanes), poly(siloxanes), poly(sulphides), poly(sulphones),

poly(vinylnitriles), poly(acrylonitriles), poly(styrene), poly(phenylenes) such as poly(2,5 dihydroxy-1 ,4-phenyleneethylene), poly(amides), natural rubbers, formaldehyde resins, other polymers and mixtures of polymers and polymers with solvents.

[0018] The carrier 1 10 may be present in an amount ranging from about 60 wt. % to about 95 wt. % by weight relative to the total weight of the ink 100. In an aspect, the carrier 1 10 may be present in an amount ranging from about 65 wt. % to about 90 wt. % by weight relative to the total weight of the ink 100.

[0019] The near infrared scattering pigment 120 coated or doped with the VOIRT dye 130 may be present in the carrier 1 10 in any loading amount so long as the dye 130 coated/doped pigment 120 may randomly orient within the carrier 1 10. In an aspect, the ink 100 may include from about 0.5% by volume to about 90%, for example, from about 5% to about 85%, and as a further example, from about 10% to about 80%, by volume of the near infrared scattering pigment 120coated or doped with the VOI RT dye 130 in the ink 100.

[0020] The ink 100 may further include other additives including, but not limited to, anti-clumping agents, anti-curl agents, binders, charge directors, corrosion inhibitors, dispersants, light stabilizers, optical brighteners, polymers, resins, rheology modifiers, UV curable materials, surface-active agents or combinations thereof.

[0021] The ink 100 may be applied to a clear substrate 210, such as a plastic film, to form the display 200 as shown in FIG. 2. In an aspect, the ink 100 may be applied to the clear substrate 210 in a pattern of indicia 220 that may be substantially invisible to the human eye when printed as small elements or features (<200 um maximum dimension). The pattern of indicia 220 may be a dot array. A user may utilize an electrical-optical reader, such as an electro-optical pen to read the pattern of indicia 220 on the clear substrate 210 shown in FIG. 2. The ink 100 may be present on the clear substrate 210 in any amount so long as a pattern of indicia 220 is formed. In an aspect, the ink 100 may be present at a thickness ranging from about 2 μιη to about 5 μιη, such as from about 3 μιη to about 5 μιη. In an aspect, the indicia may have a diameter ranging from about 40 μιη to about 140 μιη, for example, about 60 μιη to about 135 μιη. The printed indicia 220 should be as transparent as possible in the visible wavelength.

[0022] The display 200 may be used in a liquid crystal module (LCM) display or an organic light-emitting diode (OLED) display, which have their light emitting elements on a black background matrix or field. If the pattern of indicia 220 is printed with a black or grey visibly colored ink 100, the printed indicia 220 will blend with this colored background and appear invisible to the human eye. Additionally, a neutral gray color may not impart a color hue distortion to the display 200 and may be neutral to all colors being transmitted through the display 200. In an aspect, the ink 100 applied to a clear substrate 210 may have a neutral gray color.

[0023] The ink 100 may be cured using ultraviolet light, visible light, infrared, electron beam, or the like. Curing may proceed in an inert or ambient atmosphere. In an aspect, the curing step may utilize an ultraviolet light source having a wavelength of about 395 nm. The ultraviolet light source may be applied to the ink 100 at a dose ranging from about 200 mJ to about 1000 mJ, for example ranging from about 250 mJ to about 900 m J, and as a further example from about 300 mJ to about 850 mJ. In an aspect, the ink 100, may be cured in a short period of time, for example substantially instantaneously, in order to decrease the possibility of the near infrared scattering pigment 120 coated or doped with the VOIRT dye 130 reorienting in the carrier 1 10, in a flat orientation due to the effect of gravity, which would provide for a less scattered irradiance when subjected to an electronic reader.

[0024] The ink 100 may not impart a noticeable color shift when applied in a pattern of indicia 220 to a substrate 210, such as on the display 200. A color shift of C* <= 2.0 is considered invisible to the eye, referring to the L*a*b* color space. The indicia may occupy about 8.9% of the display at 100 micron diameter. The aggregate color shift for such a display 200 may be about C* 0.35, which is negligible.

[0025] With reference now to FIG. 3, there is shown a flow diagram of an example method 300 of making an ink 100. In the method 300, at block 310, a visibly opaque and infrared transparent dye 130 may be dissolved in a solvent to form a solution. In addition, at block 320, a near infrared scattering pigment 120 may be added to the solution. Moreover, at block 330, the solution may be mixed to coat or dope the near infrared scattering pigment 120 with the visibly opaque and infrared transparent dye 130. At block 340, the pigment may be removed from the solution. At block 350, the pigment may be combined with a carrier, such as a clear carrier.

[0026] The VOIRT dye 130 may be placed into a solvent or solvent mixture. The solvent may include water, alcohol, tetrahydrofuran, methyl ethyl ketone, methanol, isooctane, hexanes, toluene, dichloromethane, ethylene chloride, dimethylsulfoxide, diethyl ether, ethyl acetate, dioxane,

hexachlorobenzene, N-methyl-2-pyrrolidone, dimethyl formamide, nitrobenzene, carbon disulfide, or the like. The VOIRT dye 130 may partially or may completely dissolve in the solvent.

[0027] EXAMPLES

[0028] Example 1 -1000 ppm of a black VOIRT dye (ADA6212, commercially available from HW Sands) was dissolved in methanol (or methyl ethyl ketone) to form a solution. 1000 gm of silver microflakes (commercially available from Tokusen USA, Inc.) was combined with the solution and mixed until the silver microflakes were coated with the black VOIRT dye. 100 gm of dye coated pigment was combined with 300 gm of a ultraviolet light curable clear carrier (FR Force Transparent White, commercially available from FlintGroup) to form an ink 100. The ink 100 was continually mixed to ensure uniform dispersion of the flakes until applied by flexographic printing to a clear substrate.

[0029] Example 2 - 2500 ppm of a black VOIRT dye (ADA6212, commercially available from (HW Sands) was dissolved in methanol (or methyl ethyl ketone) to form a solution. 200 gm of titanium dioxide (commercially available from Huntsman Pigments, Woodlands, Texas USA) was combined with the solution and mixed until the titanium dioxide particles were doped with the black VOI RT dye. 200 gm of dye coated pigment was combined with 200 gm of a ultraviolet light curable clear carrier (FR Force Transparent White, commercially available from FlintGroup) to form an ink 100. The ink 100 was continually mixed to ensure uniform dispersion of the flakes until applied by flexographic printing to a clear substrate. The reflectance of the ink 100 is shown in FIG. 4.

[0030] Although described specifically throughout the entirety of the instant disclosure, representative examples of the present disclosure have utility over a wide range of applications, and the above discussion is not intended and should not be construed to be limiting, but is offered as an illustrative discussion of aspects of the disclosure.

[0031] What has been described and illustrated herein is an example of the disclosure along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the disclosure, which is intended to be defined by the following claims - and their equivalents - in which all terms are meant in their broadest reasonable sense unless otherwise indicated.

Claims

What is claimed is:

1 . An ink, comprising:

a near infrared scattering pigment and a visibly opaque and infrared transparent dye.

2. The ink of claim 1 , wherein the near infrared scattering pigment includes aluminum, magnesium, silver, nickel, copper, iron, titanium, chromium, cobalt, tin, indium, gold, lead, platinum, zinc, alloys thereof, or metal oxides thereof.

3. The ink of claim 1 , wherein the near infrared scattering pigment includes sodium aluminosilicate particles, aluminum-doped zinc oxide, zinc dioxide, titanium dioxide, polytetrafluoroethylene, or combinations thereof.

4. The ink of claim 1 , wherein the visibly opaque and infrared transparent dye includes ADA6212, SDA4549, SDB5984, SDA5989, ADA 4827, Makrolon 2407 971000, Makrolon 2407 970401 , Makrolon AX2477 900346, Makrolon 2407 770359, Spectre 100, Spectre 1 10 and Spectre 120, VOD675S, VOD695S and VOD835S, or combinations thereof.

5. The ink of claim 1 , wherein the carrier is a clear carrier.

6. The ink of claim 1 , wherein the carrier is ultraviolet light curable.

7. The ink of claim 1 , wherein the near infrared scattering pigment is coated with the visibly opaque and infrared transparent dye.

8. The ink of claim 1 , wherein the near infrared scattering pigment is doped with the visibly opaque and infrared transparent dye.

9. The ink of claim 1 , wherein the carrier is present in an amount ranging from about 60 wt.% to about 95 wt.% by weight relative to the total weight of the ink.

10. The ink of claim 1 , wherein the carrier is present in an amount ranging from about 65 wt.% to about 90 wt.% by weight relative to the total weight of the ink.

1 1 . The ink of claim 1 , wherein the ink is not visible to the human eye.

12. A printed medium comprising:

a clear substrate including an ink arranged in a pattern of indicia;

wherein the ink includes a near infrared scattering pigment and a visibly opaque and infrared transparent dye.

13. The display of claim 12, wherein the near infrared scattering pigment includes silver, silver alloy, silver oxide, or titanium dioxide.

14. A method of making an ink composition, comprising:

dissolving a visibly opaque and infrared transparent dye in a solvent to form a solution;

adding a near infrared scattering pigment into the solution;

mixing the solution to evenly coat the near infrared scattering pigment with the visibly opaque and infrared transparent dye; and

removing the coated pigment from the solution.

15. The method of claim 14, further comprising applying the ink to a clear substrate at a thickness of about 2 to about 5 microns.