Fully integrated digital color management system
11825060 · 2023-11-21
Assignee
Inventors
- Felice Sciscioli (Sidcup, GB)
- Danny Rich (Carlstadt, NJ, US)
- Richard Hayden (Yate, GB)
- Joachim Lachmann (Niederwangen, CH)
- Kurt Klaus (Niederwangen, CH)
- Olga Znamenskaya (Niederwangen, CH)
- Rainer Hauri (Niederwangen, CH)
Cpc classification
B41F33/0045
PERFORMING OPERATIONS; TRANSPORTING
H04N1/54
ELECTRICITY
International classification
H04N1/54
ELECTRICITY
B41F33/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The present invention provides a fully integrated digital workflow for the designing and production of packaging. A designer creates a package design with a special effect ink digitally, using a computer connected to a color database and a special effect ink database. Advantageously, the present workflow minimizes the complexity of the workflow by using transparent color layers printed over plain special effect additive ink layers to develop the special effect inks to be used on press. The present workflow advantageously can also be used to assess match of polychromatic inks.
Claims
1. A method of creating a digital rendering/simulation of a target special effect custom ink color, comprising: (a) providing a 3D digital display computer monitor adapted to display the design, connected to a computer having artwork visualization software installed; (b) providing a digital special effect library comprising a look-up table of special effect additive samples, each sample having luminous reflectance factor Y measured in the specular-included mode (YSPIN), luminous reflectance factor Y measured in the specular-excluded mode (YSPEX), and brilliance index (BI) values, wherein each special effect sample is identified with a unique identifier special effect sample code, and a visual rendering of each special effect sample is configured to be displayed on the 3D digital display; wherein the digital special effect library is produced by creating a series of special effect ink composition samples for each special effect additive, comprising: i. preparing a series of ink compositions at known concentrations of the special effect additive; ii. printing each ink composition on one or more production substrates, and uncoated paper, to produce printed special effect ink composition target prints; iii. assigning a unique identifier special effect sample code to each printed special effect ink composition target print, wherein each special effect ink composition is associated with a group of target prints comprising the ink printed on uncoated paper and the same ink printed on each of the production substrates; iv. measuring luminous reflectance factor Y in the specular-included mode (YSPINtarget) and in the specular-excluded mode (YSPEXtarget) of each special effect ink composition target print using a spherical spectrophotometer; v. calculating the brilliance index (BI.sub.target) of each special effect ink composition target print according to the formula: vi. BItarget=[(YSPINtarget−YSPEXtarget)/YSPINtarget]×1000 vii. storing each special effect sample code with its associated YSPIN, YSPEX, and brilliance index values to the digital special effect library; and viii. repeating steps (i) to (vii) for each special effect additive in the library; (c) providing a digital color library comprising a look-up table of color samples, wherein each color sample is a transparent color, each color sample having associated CIELAB C*.sub.ab spectral reflectance data, wherein each color sample is identified with a unique color sample code, and a visual rendering of each color sample can be displayed on the 3D digital display; (d) wherein the computer is connected to the digital special effect library and the digital color library; (e) using the computer and the 3D digital display, digitally overlaying a selected color sample over a selected special effect sample; and (f) digitally recording the selected color sample code and selected special effect sample code; wherein the combination defines a digital target special effect custom ink color sample.
2. A method of assessing brilliance index match of a special effect ink press print to a special effect ink target print, comprising: (a) selecting a special effect ink target print and related special effect sample code; (b) obtaining a press special effect ink composition being used in a press run or in a laboratory proofing test; (c) printing the press special effect ink composition on uncoated paper; (d) measuring the luminous reflectance factor Y in the specular-included mode (YSPIN.sub.press) and in the specular-excluded mode (YSPEX.sub.press) of the press special effect ink composition printed on uncoated paper using a spherical spectrophotometer; (e) calculating the brilliance index of the press print (BI.sub.press) according to the formula:
BI.sub.press−[(YSPIN.sub.press−YSPEX.sub.press)/YSPIN.sub.press]×1000; (f) determining whether BI.sub.press is within the tolerance limits of +10% of BI.sub.target for matching, by calculating the brilliance index difference (ΔBI) between the press print and the target print using the following formula:
ΔBI=[(BI.sub.press−BI.sub.target)/BI.sub.target]×100 wherein: the target value of ΔBI=0; a tolerance range for ΔBI=0±10%; a negative value, wherein ΔBI<−10%, indicates that the amount of special effect additive in the ink formula must be increased for printing on press; and a positive value, wherein ΔBI>+10%, indicates that the amount of special effect additive in the ink formula must be decreased for printing on press.
3. The method of claim 1, wherein the digital color library is PantoneLIVE/myColorCloud.
4. A method of preparing a target special effect custom color ink, comprising: (a) obtaining the selected color sample code and selected special effect sample code of the target special effect custom ink color using the method of claim 1; (b) preparing the ink color formula matching the color sample code and using the special effect ink composition matching the special effect sample code; and (c) mixing the ink color formula and special effect ink composition to obtain a target special effect custom color ink.
5. A method of creating a digital metric chroma record of the target special effect color sample ink, comprising: (a) printing the target special effect custom color sample ink of claim 4 on a selected production substrate, to obtain a printed target special effect custom color barrel proof; (b) using a sphere spectrophotometer to measure the metric chroma C*.sub.ab in the specular-included mode (CSCI.sub.target), and the C*.sub.ab in the specular-excluded mode (CSCE.sub.target), (c) digitally recording the metric chroma data for the target special effect color barrel proof in a digital look-up table.
6. A method of verifying the metric chroma match of the special effect custom color ink printed on press to the target special effect custom color ink, comprising: (a) taking a printed sample from a press run; (b) using a sphere spectrophotometer to measure the metric chroma C*.sub.ab in the specular-included mode (CSCI.sub.print) and the C*.sub.ab in the specular-excluded mode (CSCE.sub.print); (c) comparing the total color difference ΔE.sub.00 SPIN between the press print and the printed target special effect custom color, wherein: i. wherein a ΔE.sub.00 SPIN of less than or equal to ±2, is an acceptable tolerance and then proceed to step (d); but ii. if ΔE.sub.00 SPIN is greater than 2, the transparent color formula of the press ink must be adjusted; iii. adjusting the color of the press ink formula by repeating steps (i) to (ii) until ΔE.sub.00 SPIN is less than or equal to ±2; (d) comparing the color difference due to diffuse reflectance, AE SPEX, wherein: i. if the AE SPEX is also less than or equal to ±2, then the printed press sample is a match to the printed target special effect custom color and testing is complete; but ii. if ΔE SPEX is greater than 2, then the amount of special effect additive in the press ink must be corrected, wherein the correction required is calculated according to the following Chroma Index (CI) formula:
CI=ΔCSCE−ΔCSCI wherein:
ΔCSCE=CSCE.sub.print−CSCE.sub.target;
ΔCSCI=CSCI.sub.print−CSCI.sub.target the target value of CI=0; a negative value for CI indicates that the amount of special effect additive in the press ink formula must be decreased; and a positive value for CI indicates that the amount of the special effect additive in the press ink formula must be increased; and iii. increasing or decreasing the amount of special effect additive in the press ink formula, and repeating step ii. until ΔCSCE is within ±10% of ΔCSCI, calculated according to:
[(ΔCSCE−ΔCSCI)/ΔCSCI]×100=0±10.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1)
(2)
(3)
(4)
(5)
DETAILED DESCRIPTION OF THE INVENTION
(6) The present invention provides a fully digital workflow that will solve many of the issues involved with the current protocols for achieving acceptable production of packaging. Several of the problems, and the solutions provided by the present invention, are shown in Table A.
(7) TABLE-US-00001 TABLE A Workflow improvements PROBLEM SOLUTION Large investment of money Digital workflow: artwork is and time to produce a physical imported in a 3D simulation and mock-up of the predicted display software, where visual artwork appearances (colors/effects) are specified using digital libraries of special effect inks, achievable color targets, finishing coatings (OPV—over printing varnishes), embellishment effects, and substrates There are many complexities Standardisation of the materials in the processes related to the and a simplification of the printing achievability of the predicted structure allows for exact simulation artwork of the optical properties of the printing Special effect inks comprised Implementation of the Brilliance of multiple layers of inks, Index in the analysis of the total some absorbing and some surface appearance where special appearance modifying can effect inks are printed provides a only be formulated visually factor that has been shown to be and only by having a physical strongly correlated to visual sample of the desired packaging appearance of metal and interference flake pigments. Special effect inks comprised Measurement of the Brilliance of mixtures of absorbing Index of the special effect pigments and goniochromic (metallised flake, pearlescent pigments can be formulated flake or polychromatic mixtures visually and only using a of flaked pigments and physical sample of the desired conventional pigmented) inks, packaging printed on uncoated paper with a specified proofing process, is able to identify the both the appearance and the amount of the special effect pigments. Color approval must be in Use of digital color libraries, made person, using skilled visual by achievable color targets, shared methods, using physical across the full workflow using a samples cloud based system Color approval is in person, Using Measure Brilliance Index visual, using physical samples and SPIN/SPEX readings we can control consistency of the special effect inks and understand how to manage corrections of the special effect ink on press
(8) It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of any subject matter claimed.
(9) Headings are used solely for organizational purposes, and are not intended to limit the invention in any way.
(10) Unless otherwise defined, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which the inventions belong. All patents, patent applications, published applications and publications, websites and other published materials referred to throughout the entire disclosure herein, unless noted otherwise, are incorporated by reference in their entirety for any purpose. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods are described.
Definitions
(11) In this application, the use of the singular includes the plural unless specifically stated otherwise. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
(12) In this application, the use of “or” means “and/or” unless stated otherwise. Also, when it is clear from the context in which it is used, “and” may be interpreted as “or,” such as in a list of alternatives where it is not possible for all to be true or present at once.
(13) As used herein, the terms “comprises” and/or “comprising” specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Furthermore, to the extent that the terms “includes,” “having,” “has,” “with,” “composed,” “comprised” or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”
(14) As used herein, ranges and amounts can be expressed as “about” a particular value or range. “About” is intended to also include the exact amount. Hence “about 5 percent” means “about 5 percent” and also “5 percent.” “About” means within typical experimental error for the application or purpose intended.
(15) It is to be understood that wherein a numerical range is recited, it includes the end points, all values within that range, and all narrower ranges within that range, whether specifically recited or not.
(16) As used herein, “substrate” means any surface or object to which an ink or coating can be applied. Substrates include, but are not limited to, cellulose-based substrates, paper, paperboard, fabric (e.g. cotton), leather, textiles, felt, concrete, masonry, stone, plastic, plastic or polymer film, spunbond non-woven fabrics (e.g. consisting of polypropylene, polyester, and the like) glass, ceramic, metal, wood, composites, combinations thereof, and the like. Substrates may have one or more layers of metals or metal oxides, or other inorganic materials. Particularly preferred are various production substrates and uncoated paper.
(17) As used herein, the term “article” or “articles” means a substrate or product of manufacture. Examples of articles include, but are not limited to: substrates such as cellulose-based substrates, paper, paperboard, plastic, plastic or polymer film, glass, ceramic, metal, composites, and the like; and products of manufacture such as publications (e.g. brochures), labels, and packaging materials (e.g. cardboard sheet or corrugated board), containers (e.g. bottles, cans), a polyolefin (e.g. polyethylene or polypropylene), a polyester (e.g. polyethylene terephthalate), a metalized foil (e.g. laminated aluminum foil), metalized polyester, a metal container, and the like.
(18) As used herein, “inks and coatings,” “inks,” and “coatings” are used interchangeably, and refer to compositions of the invention, or, when specified compositions found in the prior art (comparative). Inks and coatings typically contain resins, solvent, and, optionally, colorants. Coatings are often thought of as being colorless or clear, while inks typically include a colorant.
(19) As used herein, “reflectance” is the amount of radiation reflected from a surface compared to the amount of incoming radiation.
(20) As used herein, “specular reflectance,” “specular reflection,” and the like refer to light reflected from a surface at a definite angle from a surface, generally at an angle equal to but opposite of the angle of the light illuminating the surface.
(21) As used herein “diffuse reflectance,” “diffuse reflection,” and the like refer to when light is scattered in various directions. Diffuse reflection of light occurs more strongly on rough, textured, and irregular surface conditions, making an object appear less saturated and duller in color.
(22) In the present invention, reflectance is measured using a spectrophotometer. The reflectance can be measured such that both the specular and the diffuse reflection are included, referred to as “SPIN-mode,” which may be referred to in the art as “d8i”, “di:8°” or “SCI.” Or, the reflectance can be measured such that only the diffuse reflection is included, referred to as “SPEX-mode,” which may be referred to in the art as “d8e”, “de:8°” or “SCE.”
(23) As used herein, “CSCI” refers to the metric chroma, CIELAB C*ab, of a printed ink or coating measured in the SPIN-mode.
(24) As used herein, “CSCE” refers to the metric chroma, CIELAB C*ab, of a printed ink or coating measured in the SPEX-mode.
(25) As used herein, the “chroma index” or “CI” of a printed ink or coating refers to the ratio of the metric chroma that is attributable specular reflection.
(26) As used herein, “brilliance index” or “BI” refers to the amount of reflection of a printed ink or coating containing only special effect additive (i.e. no absorbing pigments) that is attributable to specular reflection.
(27) Color Management System
(28) The present invention provides a digital workflow, in which many of the identified complexities, caused by the subjective perception of the color and appearance of the proofs and the final prints, are simulated digitally. A fully digital definition, at the design level, of what colors and appearances are achievable in the artwork produced by the intended printing conditions are used to guide the designer and to set expectations before leaving the design phase of the workflow. Then, all production approvals, currently made by a person on site, can be made remotely, through the implementation of a fully digital workflow, utilizing visualization software, measurement hardware, and cloud-hosted databases, along with modern color displays (such as 3D graphic monitors), color measurement instruments, color-matching and color control programs.
(29) In a first embodiment of the present invention, the digital workflow will be the simulation of the plain, transparent color ink layer printed over: the appropriate packaging substrate layer, a metal flake pigmented ink layer, a pearlescent flake pigmented ink layer, any interference flake pigmented ink layer, foil layer, foil-like ink layer, or combinations thereof, on the 3D color display. Optionally, the first embodiment will include an overprint varnish layer printed over the plain, transparent color ink layer. Each of the layers are provided as a series of samples with unique identifier codes. The workflow of the present invention gives the ability to identify each of the materials digitally by a qualitative and quantitative perspective. This allows the suppliers of the materials to verify the conformance to requirements prior to shipping the materials to the printing (press or production) factory. Thus, this eliminates the possibility that complexities associated with conventional methods will cause unnecessary costs, and a significant time investment in the process of taking a design-to-press.
(30) In a second embodiment of the present invention, the digital workflow provides a method to determine the composition of blended inks that contain mixtures of traditional absorbing pigments and special effect flaked pigments. The conventional prior art methods require complex and expensive instrumentation, known as goniospectrophotometers, to achieve this step. Goniospectrophotometers utilize multiple angles of illumination and/or viewing of the printed packaging. In contrast, this step is achieved in the present invention by separation of the diffusely reflected light from the specularly reflected light, quantified by a Brilliance Index.
(31) The present invention includes, but is not limited to, the following process improvements in the printing of packaging for brand products: A fully digital workflow in which artwork is imported into a 3D simulation display software, where visual appearances, such as colors and special effects, are specified using digital libraries of colored inks and special effect inks printed on standard packaging materials, along with the list of achievable color targets and any finishing steps, such as coatings or overprint varnishes (OPV), and embellishment effects such as textures, embossments, etc. Standardization of all materials and the simplification of the printing structure by providing a full definition of the processes and resulting effects on the final appearance of the packaging. The ability to control the appearance of special effect printing through the implementation of a brilliance index at all stages of the design and production process for the evaluation and analysis of the printed areas where special effect inks are printed. Brilliance index is not traditionally used at any stage of the design or production process (e.g., including, but not limited to, the press room, proofing, ink room, etc.). The use of digital color libraries with color targets that are produced using achievable color inks on actual product substrates. These libraries, hosted in the cloud-based databases, are shared across the full workflow so that at each step, the expected appearance can be reviewed and confirmed. This maintains the expectations and provides the ability to review and approve the printing job remotely.
(32) To achieve the features described above, the present invention utilizes the implementation of certain processes. In one embodiment, the printing process must be simplified, eliminating the option of mixing colored bases into metallic and pearlescent inks, which mixing produces a nearly infinite number of possible combinations. Rather, according to one embodiment of the present invention, metallic and pearlescent inks are plain, and will be used only as background for transparent inks. This simplification is shown in
(33) The present invention also provides a standardization of the materials used in packaging printing (e.g. tobacco packaging printing). Conventionally, too many materials are used in this workflow. In the packaging industry for tobacco, for example, many different pearlescent, silver, and gold pigments are supplied which may then create many different combinations in the finished inks. This large number of materials makes the use of a cloud-based library inefficient. Without a definition of a restricted set of components, it will never be possible to move the workflow into a simple and effective solution. The present invention limits the number of materials available in cloud-based databases to facilitate the selection and digital simulation of packaging designs. Although this may be considered as limiting the creativity for the designers, it is a clear requirement in support of a fully digital workflow.
(34) In another aspect of the present invention, the fully digital workflow makes it possible to develop new packaging designs using the 3D display where the standardized set of plain transparent colored inks and special effect materials will be available. The transparent ink color samples each have a unique identifier code stored in a digital database. Each special effect additive is presented in a series of concentrations, each of which have a unique identifier code stored in a digital database, enabling the designer to choose a specific special effect additive at a specific concentration. Consequently, it will be possible for the designer to visualize, on a calibrated monitor, what the final appearance of the packaging will be, without the need to produce a physical mock-up.
(35) Physical selection catalogues of the special effect additive compositions are correlated with the digital look-up tables. All of the brilliance index values will be available, giving the designer the option of selecting known special effect additive compositions from the beginning of the workflow. Thus, the designer can identify which material should be used in the special effect ink.
(36) The method of the present invention provides efficient, digital, transmittal of the ink and design information to the pre-press stage of the workflow. Using the information, the pre-press team finalizes the elaboration of the artwork, and gets it ready for printing of a barrel proof. Then, the fingerprint (i.e. color and brilliance index values) will be used as input in the press specifications. The present invention supports the pre-press phase of the workflow with the preparation of all digital colors to implement in the artwork where needed. With a knowledge of which special effect material, and at what concentration, should be used, the press specifications can be easily predicted at this stage. Using real, achievable transparent ink colors will be easy to predict and simulate the final appearance of the packaging.
(37) The method of the present invention enables the ink supplier to provide the correct materials to the printing factory. Because there are digital definitions of all required appearances, the ink supplier can look up or produce the required recipes of the transparent standard inks, and then use the brilliance index value to identify the correct special effect inks on the substrates being utilized by the printing factory to produce the packaging. Advantageously, by printing on uncoated paper, in addition to identifying the correct special effect additive, the present invention provides a method to define the amount of the special effect additive material. Thus, the evaluation of a test or press print is quantitative.
(38) Colors are communicated digitally via the internet or from a cloud-based database using a standard color exchange formatted (CxF) data file. This part of the present invention then eliminates the need to prepare and share color swatches which may or may not represent the actual printing conditions. This fully digital workflow allows the ink supplier to achieve all desired targets, getting the colors right on the first attempt on press.
(39) Because the inks and the design have all been developed using this digital workflow, the printing factory will be able to use the same digital data to validate the printing at the press-side, and, using the cloud-based databases upload the verification results to the workflow, allowing digital feedback to the packaging buyer and the design teams.
(40) The appearance of a special effect ink, such an ink containing a metal flake pigment, can be assessed by calculating the brilliance index (BI). To determine the BI of a special effect pigment at different concentrations, a series of ink compositions containing only the special effect pigment and vehicle, i.e. no absorbing pigments, is prepared. The inks are printed on a substrate, and the spectral reflectance measured in both specular-included (SPIN) mode, and specular-excluded (SPEX) mode. As explained above, the visual perception of brilliance is correlated with the ratio of reflectance that is due to specular reflection. Using a sphere spectrophotometer, the luminous reflectance factor Y is measured in the specular-included mode (YSPIN) and the specular-excluded mode (YSPEX). The brilliance index (BI) of each print is calculated according to the following formula:
BI=[(YSPIN−YSPEX)/YSPIN]×1000
(41) The inks can be printed on any substrate, such as a production (packaging) substrate, or uncoated paper. Because production substrate features (such as roughness, etc.) can affect specular reflection, the BI of the special effect ink per se can be standardized by measuring the inks printed on uncoated paper. Each series of special effect additive alone inks is printed on one or more production substrates as well as uncoated paper, and the BI for each calculated. Thus, each special effect additive ink (i.e. each concentration of special effect additive) will be associated with a cluster of BI values, one for each of the production substrates and uncoated paper. This enables the BI of the ink on any production substrate to be correlated with its BI printed on uncoated paper. In this way, a test print on uncoated paper can be used to predict the appearance on a production substrate. Each print is assigned a unique special effect sample code. These unique codes and the related data, for example BI, are stored in a “digital special effect library database”. The digital special effect library comprises a look-up table of special effect additive samples, each sample having luminous reflectance factor Y measured in the specular-included mode (YSPIN), luminous reflectance factor Y measured in the specular-excluded mode (YSPEX), and brilliance index (BI) values, wherein each special effect sample is identified with a unique identifier special effect sample code, and a visual rendering of each special effect sample can be displayed on the 3D digital display. Using any known graphic, photo, or other art visualization software, each special effect sample can be displayed as a special effect sample “color” swatch on a 3D display, such as a 3D computer monitor.
(42) To determine the concentration of special effect additive in a press ink, the BI of the press ink can be compared to the BI of the desired concentration determined as described above. The BI of the press ink is calculated as described above. The desired special effect ink target print, with its related special effect sample code is selected. The target print may be a special effect ink composition printed on a production substrate. Because the target print on a production substrate is directly associated with the same ink printed on uncoated paper, the BI of the ink printed on uncoated paper can be used as a comparator. The BI of the target ink printed on uncoated paper is termed BI.sub.target. It is easier to print test runs on uncoated paper as a standard protocol, than to print test runs on production substrates. The only substrate necessary to have available for testing is uncoated paper, simplifying the test process. A sample of the press ink, or the ink being used in a laboratory proofing test, is taken, and printed on uncoated paper. The luminous reflectance factor Y is measured in the specular-included and the specular-excluded modes, to give YSPIN.sub.press and YSPEX.sub.press of the press ink, and the brilliance index (BI.sub.press) calculated, as described above. To determine if the press ink matches the desired target ink, the brilliance index difference (ΔBI) is calculated. Preferably, the BI.sub.press is within about 10% to 20% of BI.sub.target, most preferably within 10%. The ΔBI between the press print and the target is calculated according to the following formula:
ΔBI=[(BI.sub.press−BI.sub.target)/BI.sub.target]×100
wherein: the target value of ΔBI=0; a tolerance range for ΔBI=0±10%; a negative value, wherein ΔBI<−10%, indicates that the amount of special effect additive in the ink formula must be increased for printing on press; and a positive value, wherein ΔBI>+10%, indicates that the amount of special effect additive in the ink formula must be decreased for printing on press.
(43) To design a special effect printed packaging, a designer will use a 3D display computer monitor adapted to display the design, connected to a computer having artwork visualization software installed. The computer will be connected to the digital special effect library comprising a look-up table of special effect additive samples described above. The computer will also be connected a digital color library comprising a look-up table for color samples, wherein each color sample is a transparent color, each color sample having associated CIELAB C*.sub.ab spectral reflectance data, wherein each color sample is identified with a unique color sample code, and a visual rendering of each color sample can be displayed on the 3D digital display. The digital color library used is not limited, and can be any digital color library currently known, or developed in the future. For example, the digital color library includes, but is not limited to, PantoneLIVE/myColorCloud. Using the computer and 3D digital display, the designer will overlay a selected color sample over a selected special effect sample. This is repeated until the designer is satisfied with the appearance of the design. When the designer is satisfied with the design, the selected color sample code and the selected special effect sample code is digitally recorded, wherein the combination defines a target special effect custom ink color sample.
(44) Using the selected color sample code and selected special effect sample code of the target special effect custom color ink, the target special effect custom color ink can be prepared. The ink color formula that matches the color sample code is prepared, and the special effect ink composition that matches the special effect sample code is mixed with the ink color formula. The mixed ink is the target special effect custom color ink. The target special effect custom color ink is printed on the intended production substrate, to produce a barrel proof. A sphere spectrophotometer is used to measure the metric chroma C*.sub.ab in the specular-included mode (CSCI.sub.target), and the C*.sub.ab in the specular-excluded mode (CSCE.sub.target). The metric chroma for the target special effect custom color ink are digitally recorded, and stored in a digital look-up table of special effect custom color inks. Each target special effect custom color ink is assigned a unique custom color ink identification code.
(45) Parameters such as total color difference (ΔE00) and/or brilliance index (BI) are archived for traceability and quality control in future printing runs. Spectral reflectance color values are measured by methods well-known in the art, using spectrophotometers, preferably sphere spectrophotometers. As discussed earlier, there is both specular reflection and diffuse reflection. Total color is affected by both specular and diffuse reflectance, and is measured in both the SPIN-mode and the SPEX-mode. The presence of flaked effect pigments, such as metallic or pearlescent pigments, impacts the specular reflection more than the diffuse reflection. For example, when comparing prints of two inks of the same color, if the concentration of metallic flakes is essentially the same, the color values for the two prints will be very similar in both the SPIN- and SPEX-modes. However, if one of the inks has less metallic flake, the inks may be matched when measured in the SPIN-mode, but the ink with less metallic flake will be darker and more chromatic when measured in the SPEX-mode. When the amount of flaked pigment of the test print is correct, the difference between the modes will be diminished, and a visual match will be achieved.
(46) To assess the special effect color match, the CIELAB metric chroma for each of the SPIN- and SPEX-modes are determined. Measurement of color using the CIELAB system is well-known in the art. The metric chroma is given the symbol C*.sub.ab for the CIELAB color reference space, and describes the vividness or dullness of a color—that is, how close the color is to either gray or the pure hue (“a” is the red/green scale, and “b” is the yellow/blue value). Given that all of the computations used herein are based on the CIELAB space, the superscript “*” and the subscript “ab” may be omitted, and notation to identify the measurement used. The term “CSCE” means the metric chroma for the SPEX-mode readings, and the term “CSCI” means the metric chroma for the SPIN-mode readings. As a hypothetical example, a metallic flake containing reference color will have a CSCI of 68.7 and a CSCE of 73.3. The same ink without any metallic flake pigment will have a CSCI of 69.6, nearly identical to the reference metallic color; but, this same ink will have a CSCE of 81.2, a difference of 8 steps in metric chroma to the reference metallic color. As the amount of flake pigment is added to the matching ink recipe, the metric chroma difference between the reference color and the test color under the two conditions decreases. When the concentration has been adjusted correctly, the AC will be small, and the total color difference ΔE.sub.00 will also be small for both measurement modes.
(47) To assess whether the transparent color (i.e. the color without adjustment for metallic pigment) of the test ink (such as a press or print ink) is a match to the target print, the color difference between the test and target print is assessed in the SPIN-mode (ΔE.sub.00 SPIN). A preferred tolerance for the color difference between the test and reference colors is preferably less than 2 color units. If the ΔE.sub.00 SPIN is more than 2 color units, the transparent color must be adjusted until the ΔE.sub.00 SPIN is within 2 color units. The next step is to assess whether the test ink has the correct concentration of special effect additive. To assess whether the test ink has the same concentration of metallic pigment, the metric chroma are measured in the SPEX-mode. If the color difference measured in the SPEX-mode Woo SPEX) is also within 2 color units, then the test ink is an acceptable match to the target ink. However, if ΔE.sub.00 SPEX is greater than 2 color units, then the amount of special effect additive (e.g. metallic pigment) in the test (press) ink must be adjusted. For the purposes of calculation, the metric chroma of the test ink measured in SPEX-mode is termed “CSCE.sub.print”, and the metric chroma of the test ink measured in SPIN-mode is termed “CSCI.sub.print.” The digitally stored metric chroma for the target ink are termed “CSCE.sub.target” and “CSCI.sub.target.” When correction is required, the difference between the test and target inks is calculated as Chroma Index (CI), according to the following formula:
CI=ΔCSCE−ΔCSCI wherein: ΔCSCE=CSCE.sub.print−CSCE.sub.target; ΔCSCI=CSCI.sub.print−CSCI.sub.target the target value of CI=0; a negative value for CI indicates that the amount of special effect additive in the press ink formula must be decreased; and a positive value for CI indicates that the amount of the special effect additive in the press ink formula must be increased; and
increasing or decreasing the amount of special effect additive in the press ink formula, and repeating step ii. until ΔCSCE is within ±10% of ΔCSCI, calculated according to:
[(ΔCSCE−ΔCSCI)/ΔCSCI]×100=0±10.
(48) The methods of the present invention provide a fully digital workflow, by providing a set of digital information from which an ordinarily skilled person can: Successfully run a color match of an ink containing metallic/pearlescent/polychromatic pigments without the need of having a physical sample from the master production batch for a visual approval of the special effect or the use of an expensive goniospectrophotometer. Control the consistency of the printing of the special effect ink during production.
(49) Following the approval of a special effect color, during the first master batch production run for a packaging print, and having the ink used for it containing metallic or pearlescent materials, one can standardize the information related to the ink, and save the information in a digital special effect ink color database. Information such as color appearance (measurement from a spherical or hemi-spherical diffuse spectrophotometer), printing condition, unique custom color ink identifier code, and the BI of the special effect ink printed on uncoated paper with a specified proofer can be stored. The BI and metric chroma data of the target special effect custom color ink printed on the intended packaging substrate can also be archived in a digital cloud database.
(50) To reproduce the special effect ink for all following productions, the press conditions information must be known, as well as the settings needed on the laboratory ink proofer, and the SPIN-mode color measurement in order that one can correctly reproduce the appearance of the color. Printing the predicted ink on the same uncoated paper, and using the same specified proofer used for the standard, one can measure the BI value from the proof, compare to the value recorded for the standard, and control the amount of special effect material in the ink. The formula is optimized step by step, reducing as much as possible the color and BI differences between the digital data recorded for the standard and the new measurements from the produced sample.
(51) Color consistency in production can then be ensured using the BI and SPIN and SPEX digital color measurements taken from the master printed packaging. Utilizing the differences between master and batch information, one can control the production so that it is in tolerance both in terms of the color (using SPIN-mode color measurement) and in the appearance modulated by the amount of special effect material (using a combination of the BI, SPIN-mode and SPEX-mode spectral reflectance measurements), and to understand how to modify the ink on press if needed.
EXAMPLES
(52) The invention is further described by the following non-limiting examples which further illustrate the invention, and are not intended, nor should they be interpreted to, limit the scope of the invention.
(53) A series of special effect inks were printed on production substrate (ICL coated paper) and uncoated paper. Each special effect ink print was compared to a target (master batch or reference) printed ink.
(54) Sets of special effect inks were prepared, with a reference ink, and test inks at higher and lower concentrations of special effect additive.
(55) Printing
(56) Each ink was printed on either ICL coated paper (ICL Invercote Lenato paper 240 g/m.sup.2—a production substrate) or uncoated paper. An overprint varnish (OPV) layer was applied to some of the prints on ICL coated paper.
(57) Printing on ICL coated paper was done using a Barrel Proof Machine, using the following specifications:
(58) Cylinder Specification:
(59) Cylinder 1 For Pearls—mechanical engraved 70/0° 120°, 16.2 ml/m.sup.3 For Silvers—laser exposed etched 80/25°, 31 μm, 21.0 ml/m.sup.3
(60) Cylinder 2 For Lacquer (OPV)—mechanical engraved 80/0° 130° (solid)
Printing on uncoated paper was done with a handproofer using a 12 micron K-bar.
Metric Chroma, Brilliance Index, and Opacity
(61) The metric chroma and opacity of each print was measured using a Konica Minolta CM-26d portable sphere spectrophotometer, with the following measurement settings: D50 illuminant, 2 Grad (2° observer), in either SPEX-mode (de:8°) or SPIN-mode (di:8°). The CSCI and CSCE were measured, and the BI and CI data were calculated from these data as described above. The data tables in the examples below show the opacity, and calculated BI and CI data.
Example 1. Sample Press Inks A1 to A4
(62) A high gloss silver special effect ink was prepared with varying concentrations of special effect additive to obtain inks A1 to A4. Ink A1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks A2 to A4 each had decreasing concentrations of special effect additive relative to A1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. A1-ref: 100% relative concentration of special effect additive A2: 80% relative concentration of special effect additive A3: 60% relative concentration of special effect additive A4: 40% relative concentration of special effect additive
(63) Table 1 shows the Brilliance Index (BI) and Chroma Index (CI) data.
(64) TABLE-US-00002 TABLE 1 Metric chroma of inks A1 to A4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 CI A1-ref 260.1 214.7 206.7 99.12 0 0 A2 275.4 230.2 186.6 97.41 0.15 0.5 A3 275.6 237.9 168.0 91.84 0.45 1.7 A4 262.3 223.9 117.3 81.94 1.2 4.6
(65) The data show that ink A2, with the concentration of special effect additive closest to the A1-ref, is the best match.
Example 2. Sample Press Inks B1 to B4
(66) A UV high gloss silver special effect ink was prepared with varying concentrations of special effect additive. Ink B1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks B2 to B4 each had decreasing concentrations of special effect additive relative to B1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. B1-ref: 100% relative concentration of special effect additive B2: 80% relative concentration of special effect additive B3: 60% relative concentration of special effect additive B4: 40% relative concentration of special effect additive
(67) Table 2 shows the calculated BI and CI data.
(68) TABLE-US-00003 TABLE 2 Metric chroma of inks B1 to B4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 CI B1-ref 668.6 554.4 n/a n/a 0 B2 634.4 537.7 n/a n/a 1.3 1.9 B3 467.4 365.7 n/a n/a 3.31 −6.6 B4 314.7 249.4 n/a n/a 4.27 −12.3
(69) The data show that ink B2, having the closest concentration of special effect additive to B1-ref, is the closest match.
Example 3. Sample Press Inks C1 to C4
(70) A standard silver special effect ink was prepared with varying concentrations of special effect additive to obtain inks C1 to C4. Ink C1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks C2 to C4 each had decreasing concentrations of special effect additive relative to in C1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. C1-ref: 100% relative concentration of special effect additive C2: 80% relative concentration of special effect additive C3: 60% relative concentration of special effect additive C4: 40% relative concentration of special effect additive
(71) The data are shown in Table 3.
(72) TABLE-US-00004 TABLE 3 Metric chroma of inks C1 to C4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 CI C1-ref 288.4 248.0 296.0 99.07 0 0 C2 287.1 252.5 218.5 98.56 0.69 0.5 C3 271.3 253.1 160.0 92.85 1.42 1.8 C4 241.1 227.5 110.2 84.66 2.33 4.1
(73) The data show that ink C2, having the closest concentration of special effect additive to C1-ref, is the closest match.
Example 4. Sample Press Inks D1 to D4
(74) A matte silver special effect ink was prepared with varying concentrations of special effect additive to obtain inks D1 to D4. Ink D1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks D2 to D4 each had decreasing concentrations of special effect additive, relative to ink D1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. D1-ref: 100% relative concentration of special effect additive D2: 80% relative concentration of special effect additive D3: 60% relative concentration of special effect additive D4: 40% relative concentration of special effect additive
(75) The data are shown in Table 4.
(76) TABLE-US-00005 TABLE 4 Metric chroma of inks D1 to D4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 CI D1-ref 154.3 130.4 99.8 97.04 0 0 D2 155.5 143.2 94.4 95.98 0.15 0.5 D3 155.6 142.6 90.7 91.08 0.63 0.7 D4 158.3 141.4 78.0 80.28 1.42 2.1
(77) The data show that ink D2, having the closest concentration of special effect additive to D1-ref, is the closest match.
Example 5. Sample Press Inks E1 to E4
(78) A fine pearl special effect ink was prepared with varying concentrations of special effect additive to obtain inks E1 to E4. Ink E1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks E2 to E4 each had decreasing concentrations of special effect additive, relative to ink E1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. E1-ref: 100% relative concentration of special effect additive E2: 80% relative concentration of special effect additive E3: 60% relative concentration of special effect additive E4: 40% relative concentration of special effect additive
(79) The data are shown in Table 5.
(80) TABLE-US-00006 TABLE 5 Metric chroma of inks El to E4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 E1-ref 47.9 69.7 28.9 58.84 0 E2 49.2 75.5 22.6 48.49 1.06 E3 51.0 78.2 17.9 38.84 1.99 E4 51.4 75.5 13.2 27.60 3.06
(81) The data show that ink E2, having the closest concentration of special effect additive to E1-ref, is the closest match.
Example 6. Sample Press Inks F1 to F4
(82) A coarse pearl special effect ink was prepared with varying concentrations of special effect additive to obtain inks F1 to F4. Ink F1-ref is the reference ink, and the relative concentration of special effect additive was set at 100%. Inks F2 to F4 each had decreasing concentrations of special effect additive, relative to ink F1-ref. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above. F1-ref: 100% relative concentration of special effect additive F2: 80% relative concentration of special effect additive F3: 60% relative concentration of special effect additive F4: 40% relative concentration of special effect additive
(83) The data are shown in Table 6.
(84) TABLE-US-00007 TABLE 6 Metric chroma of inks F1 to F4 BI BI BI ICL no ICL with Uncoated Ink OPV OPV paper Opacity ΔE.sub.00 F1-ref 65.2 97.6 93.3 64.28 0 F2 60.9 96.0 80.9 54.80 0.7 F3 69.8 95.3 67.0 44.60 1.18 F4 65.5 85.4 44.5 35.37 1.79
(85) The data show that ink F2, having the closest concentration of special effect additive to F1-ref, is the closest match.
Example 7. Inks G1 to G5
(86) A matte silver light red special effect ink was prepared with varying concentrations of special effect additive to obtain inks G1 to G5. G3 is the reference ink (G3-ref). The order of concentration of special effect additive is low to high, with G1 having the lowest concentration of special effect additive, and G5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(87) The inks were printed as described above. Table 7 shows the metric chroma and opacity for each ink.
(88) TABLE-US-00008 TABLE 7 Metric chroma and opacity of inks G1 to G5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt% OPV OPV paper Opacity G1 5 167.9 190.3 54.2 74.77 G2 8.33 176.7 201.4 71.4 87.68 G3-ref 10 172.4 202.8 78.8 90.29 G4 11.67 161.9 195.6 83.3 93.03 G5 15 152.9 188.4 91.7 96.23
(89) Table 8 shows the comparison of inks G1, G2, G4, and G5 to the reference ink G3-ref.
(90) TABLE-US-00009 TABLE 8 Comparison of inks G1, G2, G4, and G5 to the reference ink G3-ref ΔE.sub.00 ΔE.sub.00 CI Ink ICL no OPV ICL with OPV ICL with OPV G1 1.27 1.37 6.7 G2 0.24 0.58 1.3 G3-ref 0 0 0 G4 0.45 0.33 −2.2 G5 0.56 0.62 −4
(91) As the data show, inks G1 and G2, having a lower concentration of special effect additive than G3-ref, have a positive CI, while inks G4 and G5, having a higher concentration of special effect additive than G3-ref, have a negative CI. The data shows that sample ink G2 is the best match to reference ink G3-ref.
Example 8. Inks H1 to H5
(92) A matte silver champagne special effect ink was prepared with varying concentrations of special effect additive to obtain inks H1 to H5. H3 is the reference ink (H3-ref). The order of concentration of special effect additive is low to high, with H1 having the lowest concentration of special effect additive, and H5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(93) The inks were printed as described above. Table 9 shows the metric chroma and opacity for each ink.
(94) TABLE-US-00010 TABLE 9 Metric chroma and opacity of inks H1 to H5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity H1 5 152.1 158.8 51.0 64.95 H2 8.33 179.8 182.9 81.8 86.56 H3-ref 10 178.0 182.4 85.4 90.34 H4 11.67 174.6 183.5 92.8 88.43 H5 15 168.5 176.1 101.5 97.16
(95) Table 10 shows the comparison of inks H1, H2, H4, and H5 to the reference ink H3-ref.
(96) TABLE-US-00011 TABLE 10 Comparison of inks H1, H2, H4, and H5 to the reference ink H3-ref ΔE.sub.00 ΔE.sub.00 CI Ink ICL no OPV ICL with OPV ICL with OPV H1 2.85 2.47 −1.3 H2 0.14 0.16 0 H3-ref 0 0 0 H4 0.35 0.38 −0.2 H5 0.78 1.03 −0.6
(97) The data shows that sample ink H2 is the best match to reference ink H3-ref. The data also show that if the total color difference ΔE00 (without metallic) is greater than 2 color units, then the evaluation of CI may not be accurate. Therefore, to minimize the chance that the concentration of special effect additive is not accurate, it is important to match the color of the test ink with the color of the reference ink.
Example 9. Inks I1 to I5
(98) A high gloss silver blue special effect ink was prepared with varying concentrations of silver flake pigment to obtain inks I1 to I5. I3 is the reference ink (I3-ref). The order of concentration of special effect additive is low to high, with I1 having the lowest concentration of special effect additive, and I5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(99) The inks were printed as described above. Table 11 shows the metric chroma and opacity for each ink.
(100) TABLE-US-00012 TABLE 11 Metric chroma and opacity of inks I1 to I5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity I1 5 325.0 369.1 70.3 81.26 I2 8.33 340.9 379.0 93.8 90.71 I3-ref 10 327.5 375.2 109.6 87.18 I4 11.67 323.7 379.3 113.6 91.88 I5 15 281.8 345.8 132.7 94.97
(101) Table 12 shows the comparison of inks I1, I2, I4, and I5 to the reference ink I3-ref.
(102) TABLE-US-00013 TABLE 12 Comparison of inks I1, I2, I4, and I5 to the reference ink I3-ref ΔE.sub.00 ΔE.sub.00 CI Ink ICL no OPV ICL with OPV ICL with OPV I1 2.94 3.15 20 I2 0.47 0.76 0.9 I3-ref 0 0 0 I4 1.18 0.62 −0.7 I5 1.08 1 −4.1
(103) The data shows that sample ink I2 is the best match to reference ink I3-ref. Surprisingly, the assessment of CI of high gloss silver did not seem to be affected as much by the total color difference as was the CI assessment of the matte silver.
Example 10. Inks J1 to J5
(104) A high gloss silver green special effect ink was prepared with varying concentrations of silver flake pigment to obtain inks J1 to J5. J3 is the reference ink (J3-ref). The order of concentration of special effect additive is low to high, with J1 having the lowest concentration of special effect additive, and J5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(105) The inks were printed as described above. Table 13 shows the metric chroma and opacity for each ink.
(106) TABLE-US-00014 TABLE 13 Metric chroma and opacity of inks J1 to J5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity J1 5 267.8 228.6 57.8 71.63 J2 8.33 345.3 266.8 94.9 82.04 J3-ref 10 313.5 269.6 103.3 86.5 J4 11.67 330.9 267.0 119.4 91.42 J5 15 307.5 256.1 134.9 91.4
(107) Table 14 shows the comparison of inks J1, J2, J4, and J5 to the reference ink J3-ref.
(108) TABLE-US-00015 TABLE 14 Comparison of inks J1, J2, J4, and J5 to the reference ink J3-ref ΔE.sub.00 ΔE.sub.00 CI Ink ICL no OPV ICL with OPV ICL with OPV J1 1.9 1.44 17.2 J2 0.34 0.43 3.8 J3-ref 0 0 0 J4 0.37 0.37 −4.8 J5 0.99 1.14 −12.8
(109) As the data show, inks J1 and J2, having a lower concentration of special effect additive than J3-ref, have a positive CI, while inks J4 and J5, having a higher concentration of special effect additive than J3-ref, have a negative CI. The data shows that sample ink J2 is the best match to reference ink J3-ref.
Example 11. Inks K1 to K5
(110) A fine pearl yellow special effect ink was prepared with varying concentrations of pearlescent flake pigment to obtain inks K1 to K5. K3 is the reference ink (K3-ref). The order of concentration of special effect additive is low to high, with K1 having the lowest concentration of special effect additive, and K5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(111) The inks were printed as described above. Table 15 shows the metric chroma and opacity for each ink.
(112) TABLE-US-00016 TABLE 15 Metric chroma and opacity of inks K1 to K5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity K1 6 50.1 94.0 12.1 30.24 K2 10 55.9 99.2 17.3 40.87 K3-ref 12 57.5 100.7 19.6 46.0 K4 14 57.2 99.5 22.4 48.03 K5 15 57.0 100 28.1 56.96
(113) Table 16 shows the comparison of inks K1, K2, K4, and K5 to the reference ink K3-ref.
(114) TABLE-US-00017 TABLE 16 Comparison of inks K1, K2, K4, and K5 to the reference ink K3-ref ΔE.sub.00 ΔE.sub.00 Ink ICL no OPV ICL with OPV K1 2.36 2.16 K2 0.54 0.53 K3-ref 0 0 K4 0.35 0.3 K5 0.75 0.63
(115) The data shows that sample ink K4 is the best match to reference ink K3-ref.
Example 12. Inks L1 to L5
(116) A fine pearl light blue special effect ink was prepared with varying concentrations of pearlescent flake pigment to obtain inks L1 to L5. L3 is the reference ink (L3-ref). The order of concentration of special effect additive is low to high, with L1 having the lowest concentration of special effect additive, and L5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(117) The inks were printed as described above. Table 17 shows the metric chroma and opacity for each ink.
(118) TABLE-US-00018 TABLE 17 Metric chroma and opacity of inks L1 to L5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity L1 4 68.9 122.9 11.6 32.99 L2 7.67 80.8 139.4 19.7 44.05 L3-ref 9.5 91.5 141.6 24.4 51.24 L4 11.33 90.6 148.8 26.6 56.09 L5 15 97.0 148.5 30.6 66.44
(119) Table 18 shows the comparison of inks L1, L2, L4, and L5 to the reference ink L3-ref.
(120) TABLE-US-00019 TABLE 18 Comparison of inks L1, L2, L4, and L5 to the reference ink L3-ref ΔE.sub.00 ΔE.sub.00 Ink ICL no OPV ICL with OPV L1 1.77 1.56 L2 0.49 0.26 L3-ref 0 0 L4 0.42 0.34 L5 0.6 0.45
(121) The data shows that sample ink L2 and L4 are good matches to reference ink L3-ref.
Example 13. Inks M1 to M5
(122) A coarse pearl beige special effect ink was prepared with varying concentrations of pearlescent flake pigment to obtain inks M1 to M5. M3 is the reference ink (M3-ref). The order of concentration of special effect additive is low to high, with M1 having the lowest concentration of special effect additive, and M5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(123) The inks were printed as described above. Table 19 shows the metric chroma and opacity for each ink.
(124) TABLE-US-00020 TABLE 19 Metric chroma and opacity of inks M1 to M5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity M1 4 55.7 54.5 28.8 26.51 M2 6.67 64.8 98.9 43.1 36.55 M3-ref 8 69.9 101.8 52.4 39.63 M4 9.33 76.9 106.2 59.1 42.79 M5 12 86.4 84.7 75.3 50.02
(125) Table 20 shows the comparison of inks M1, M2, M4, and M5 to the reference ink M3-ref.
(126) TABLE-US-00021 TABLE 20 Comparison of inks M1, M2, M4, and M5 to the reference ink M3-ref ΔE.sub.00 ΔE.sub.00 Ink ICL no OPV ICL with OPV M1 0.74 1.2 M2 0.31 0.24 M3-ref 0 0 M4 0.45 0.36 M5 0.8 0.92
(127) The data shows that sample ink M2 is the best match to reference ink M3-ref.
Example 14. Inks N1 to N5
(128) A coarse pearl violet special effect ink was prepared with varying concentrations of pearlescent flake pigment to obtain inks N1 to N5. N3 is the reference ink (N3-ref). The order of concentration of special effect additive is low to high, with N1 having the lowest concentration of special effect additive, and N5 having the highest concentration. Each ink was printed as described above, and the metric chroma and brilliance index measured as described above.
(129) The inks were printed as described above. Table 21 shows the metric chroma and opacity for each ink.
(130) TABLE-US-00022 TABLE 21 Metric chroma and opacity of inks N1 to N5 Special effect BI BI BI additive ICL no ICL with Uncoated Ink wt % OPV OPV paper Opacity N1 5 111.2 180.7 46.2 47.47 N2 8.33 138.3 215.5 85.7 65.93 N3-ref 10 145.3 225.6 82.0 66.43 N4 11.67 148.6 229.2 97.8 68.94 N5 15 171.8 242.1 126.6 77.46
(131) Table 22 shows the comparison of inks N1, N2, N4, and N5 to the reference ink N3-ref.
(132) TABLE-US-00023 TABLE 22 Comparison of inks N1, N2, N4, and N5 to the reference ink N3-ref ΔE.sub.00 ΔE.sub.00 Ink ICL no OPV ICL with OPV N1 1.84 1.65 N2 0.35 0.22 N3-ref 0 0 N4 0.38 0.64 N5 0.8 1.01
(133) The data shows that sample ink N2 is the best match to reference ink N3-ref
(134) The present invention has been described in detail, including the preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention that fall within the scope and spirit of the invention.