WO2018185686A1 - Laser-based inkless printing - Google Patents

Abstract

Provided herein are multilayer substrates and related systems and method for use in laser-based inkless printing. The multilayer substrates comprises an upper layer that can include a thermoplastic polymer resin, a lower layer that can include a polymer, and a nanometer-scale intermediate layer that can include a metal. The printing laser can selectively heat the upper layer of the multilayer substrate, causing the ablation, removal, or phase change of targeted regions of the upper layer, exposing the differently colored lower layer thereunder, and thereby producing printed indicia on the substrate.

Description

LASER-BASED INKLESS PRINTING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Application No.

62/481,145 filed April 4, 2017, the full disclosure of which is incorporated herein by reference in its entirety for all purposes.

FIELD

[0002] The present disclosure relates generally to laser-based inkless printing particularly useful for the printing of labels.

BACKGROUND

[0003] Many different technologies currently exist for printing indicia, such as that of a barcode or other label, to a facestock. These technologies include ink jet printing, electrostatic laser printing, electrophotography, and heat transfer printing. The current dominant technology for the printing of labels involves thermal transfer. This is a digital printing process in which material is applied to paper, polyester, or other suitable facestock material by melting a ribbon coating. Material from the melted ribbon affixes to the facestock, creating the desired printing effect. In thermal transfer applications, the label producer is required to supply two different components— the ribbon to supply the transferable ink, and the facestock substrate to which the printing is to be applied. In addition, the thermal printing facestock typically needs to be pre-cut to its final desired size and shape.

[0004] An alternative approach involves laser ablation printing. Some laser ablation references disclose machine-readable coded marking on various surfaces, including for example, a surface of a glass workpiece. Some laser inscribable films are also known. These conventional inscribable films may utilize well known componentry, e.g., acrylate coatings, various monomers/oligomers, and pigments. Other known composite label materials employ various ceramic layers. These conventional laser ablation printing processes and materials can suffer from problems, however, such as reduced contrast, high susceptibility to readability degradation and information loss, and the need for separate equipment and processes to produce cut and shaped labels.

[0005] Even in view of the conventional technologies, the need therefore remains for materials and methods with improved performance in laser-based inkless printing applications.

SUMMARY

[0006] In one embodiment, the disclosure is to a system for laser-based printing. The system comprises a laser and a multilayer substrate. The laser can have an operating wavelength ranging from 0.6 microns to 15 microns. In certain aspects, the laser has an operating power ranging from 0.3 watts to 15 watts. The multilayer substrate comprises an upper layer, a lower layer, and an intermediate layer. The upper layer can comprise a thermoplastic polymer resin and an upper layer pigment. In certain aspects, the thermoplastic polymer resin is polyethylene terephthalate. In some embodiments, the upper layer pigment is barium sulfate. The lower layer can comprise a polymer and a lower layer pigment. In certain aspects, the lower layer polymer is polyolefin. In some embodiments, the polymer is a polyester. In certain aspects, the lower layer polymer is crosslinked. In some embodiments, the lower layer polymer is a melamine polyester matrix. Preferably, the lower layer pigment has a lower absorbance than the upper layer pigment at the operating wavelength of the laser. Preferably, the lower layer pigment has a higher reflectivity than the upper layer pigment at the operating wavelength of the laser. The intermediate layer is disposed between the upper layer and the lower layer. The intermediate layer can comprise a metal. In certain aspects, the metal is aluminum or a chemical compound thereof. Preferably, the intermediate layer has a higher reflectivity than the upper layer at the operating wavelength of the laser. Preferably, the intermediate layer has a thickness less than 10 nm. In certain aspects, the lower layer has a thickness ranging from 2 micron to 100 microns. In some embodiments, the upper layer has a thickness ranging from 12 microns to 175 microns. In certain aspects, the multilayer substrate further comprises an adhesive layer, wherein the lower layer is disposed between intermediate layer and the adhesive layer.

[0007] In another embodiment the disclosure relates to a multilayer substrate. The multilayer substrate comprises an upper layer, a lower layer, and an intermediate layer. The upper layer can comprise a thermoplastic polymer resin and an upper layer pigment. In certain aspects, the thermoplastic polymer resin is polyethylene terephthalate. In some embodiments, the upper layer pigment is barium sulfate. The lower layer can comprise a polymer and a lower layer pigment. In certain aspects, the lower layer polymer is polyolefin. In some embodiments, the polymer is a polyester. In certain aspects, the lower layer polymer is crosslinked. In some embodiments, the lower layer polymer is a melamine polyester matrix. The intermediate layer is disposed between the upper layer and the lower layer. The intermediate layer can comprise a metal. In certain aspects, the metal is aluminum or a chemical compound thereof. Preferably, the intermediate layer has a thickness less than 10 nm. In certain aspects, the lower layer has a thickness ranging from 2 micron to 100 microns. In some embodiments, the upper layer has a thickness ranging from 12 microns to 175 microns. In certain aspects, the multilayer substrate further comprises an adhesive layer, wherein the lower layer is disposed between intermediate layer and the adhesive layer.

[0008] In another embodiment, the disclosure is to a method of printing. The method comprises providing a system as described above. The method further comprises ablating at least a portion of the upper layer of the multilayer substrate, wherein the ablating comprises operating the laser at a first power to remove a portion of the upper layer at a first location on a surface of the multilayer substrate, thereby exposing a portion of the lower layer at the first location. The method further comprises cutting at least a portion of the multilayer substrate, wherein the cutting comprises operating the laser at a second power greater than the first power to remove a portion of the upper layer and a portion of the lower layer at a second location on the surface of the multilayer substrate. In certain aspects, the method further comprises, subsequent to the ablating and prior to the cutting, translating the multilayer substrate relative to the laser. In some embodiments, the method further comprises subsequent to the ablating and prior to the cutting, translating the laser relative to the multilayer substrate.

BRIEF DESCRIPTION OF DRAWINGS

[0009] The disclosure references the appended drawings, wherein like numerals designate similar parts.

[0010] FIG. 1 A presents a side view illustration of a multilayer substrate prior to laser-based printing.

[0011] FIG. IB presents a side view illustration of the multilayer substrate of FIG. IB wherein a portion of the upper layer and intermediate layer have been removed by laser-based printing. [0012] FIG. 2 is an image of laser-based inkless printing on a multilayer substrate including aluminum oxide intermediate layer.

[0013] FIG. 3 is an image of laser-based inkless printing on a multilayer substrate including 50% aluminum intermediate layer.

[0014] FIG. 4 is an image of laser-based inkless printing on a multilayer substrate including nichrome intermediate layer.

[0015] FIG. 5 is an image of laser-based inkless printing on a comparative substrate not including an intermediate layer.

[0016] FIG. 6 is an image of laser-based inkless printing on a comparative substrate having low contrast.

[0017] FIG. 7 is an image of laser-based inkless printing on a comparative substrate having low contrast and poor edge definition.

[0018] FIG. 8 is an image of laser-based inkless printing on a provided multilayer substrate having high contrast and edge definition.

DETAILED DESCRIPTION

[0019] The present disclosure generally relates to systems, multilayer substrates, and methods that, when employed for example in laser-based label printing applications, provide

advantageous improvements in material cost and printing performance. For example, it is beneficial for labels to be printed onto a substrate without the need for a separate supply of ink, toner, or other material to be transferred to the substrate to produce the printing on the label substrate. It is also beneficial for a label substrate to have flexible sizing requirements, such that a web of substrate material can be provided without the need to precut the web into final label configurations prior to printing. The ability of materials and methods to produce high contrast printing and to allow for label cutting in the same process as the label printing, can

advantageously improve the quality and economics of printing processes.

[0020] It is difficult, however, for conventional label printing applications to meet these demands. One reason for this is that label printing typically involves the thermal transfer of ink or toner from separately supplied ribbon to the label substrate.

[0021] In addition, conventional laser ablation processes generally involve layer chemistries in which the upper layer has a black coloration, and the lower layer has a white coloration. As a result, printing produced by selectively removing regions of the upper black layer and exposing the lower white layer has the appearance of a white pattern against a black background. Such white-on-black printing is typically characterized by a lower contrast than can be achieved with the black-on-white printing typical of, for example, thermal transfer label printing processes. As lower contrast is associated with lower readability of print, this type of laser ablation printing can therefore be disadvantageous. Furthermore, the white patterning of this conventional laser ablation has been shown to be more prone to contamination, degradation, and failure. For example, if such a printed surface is contacted with chemicals or abrasive materials, the already low contrast of the printed markings can be further reduced, and the information or image to be communicated with the printing can become obscured

[0022] Another disadvantage associated with conventional laser ablation printing processes is that the use of a laser to ablate an upper layer of a printing surface can negatively impact the structure of the lower layer thereunder. To mitigate these effects on the lower surface, thick protective reflective layers can be incorporated into printing media between the upper and lower layers. These protective layers serve to reflect the laser light away from the lower layer and back towards the upper layer to be ablated. Because these thick protective layers do not permit the laser to significantly penetrate the lower layer, the printed labels must be cut to desired shapes and sizes in a process that is entirely separate from that of printing. For example, the labels may be precut prior to printing, as is often the case with thermal transfer label printing processes. Alternatively, the printed labels may be cut after the laser ablation printing by using another piece of equipment. In either case, the separation of printing and cutting can add complexity and cost to label manufacture.

[0023] The inventors have now discovered that low power lasers and particular configurations of multilayer substrates can be used effectively and efficiently to provide laser-based inkless label systems having improved image quality and the ability to print and cut labels using a single system. In particular, it has been found that by utilizing a specific configuration of layers in the printing substrate, e.g., relative thicknesses, compositions, and absorption or reflection qualities, and/or by employing laser light operating at wavelengths and powers within certain ranges, the substrate can beneficially be printed upon at high contrast and optionally cut by this laser light. In this way, by using the disclosed systems and methods, an end user can create high quality labels by using only one consumable component in the form of the multilayer substrate to be printed upon. Because it is not necessary to separately purchase or otherwise provide inks to be transferred to the substrate, costs can be reduced, and supply chains and inventory management can be simplified. Moreover, as the disclosure also provides systems and methods that enable the cutting of labels from the multilayer substrate, further advantages are realized by eliminating the need to provide precut labels prior to printing, which greatly simplifies production.

[0024] Also, it has been discovered that the use of particular laser operation parameters (optionally in conjunction with the disclosed multilayer substrates) surprisingly leads to higher quality printed images. For example and without being bound by theory, the inventors have found that by operating of the laser at the first power to print upon the multilayer substrate involves causing a phase change in portions of the substrate upper layer. In this case, the heat load of the laser may advantageously eliminate the scattering effect of pigment inclusions, e.g., barium sulfate "bubbles", within the upper layer, which leads to the higher quality image.

[0025] In one embodiment, a system for laser-based printing is disclosed. The system includes a multilayer substrate, and a laser configured to carry out the printing on the multilayer substrate. The multilayer substrate comprises an upper layer that can include a thermoplastic polymer resin, a lower layer that can include a polymer, and an intermediate layer that can include a metal. The materials and configurations of the lower layer and the intermediate layer can be selected to have low absorption and high reflectivity at the operating wavelength of the printing laser. In this way, the lower layer is not damaged by the laser during printing. In contrast, the materials and configuration of the upper layer can be selected to have high absorption and low reflectivity at the printing laser operating wavelength. As a result, the printing laser heats this upper layer of the multilayer substrate, and can cause the ablation, removal, or phase change of targeted regions of the upper layer, exposing the differently colored lower layer thereunder, and thereby producing printed indicia on the substrate.

Substrate Upper Layer

[0026] In some embodiments, the upper layer of the multilayer substrate includes a

thermoplastic polymer selected to have a chemical structure susceptible to heating as a result of the laser operations during laser-based printing (and cutting). In some embodiments, the upper layer includes a thermoplastic polymer selected to high good durability against chemical contact, contamination, and abrasion. The thermoplastic polymer can comprise polyethylenes, polypropylenes, polyolefins other than polyethylenes and polypropylenes, alkene-unsaturated carboxylic acid or unsaturated carboxylic acid derivative copolymers, styrene-based polymers or copolymers, polyurethanes, polycarbonates, polyamides, fluoroplastics, poly(meth)acrylates, polyacrylonitriles, polyesters, or a mixture of any of the foregoing polymers. The thermoplastic polymer can include nylons, butadiene rubbers, other extrudable thermoplastics, or combinations thereof. In certain aspects, the thermoplastic polymer comprises polyethylene terephthalate, which can provide good protection against chemical contamination of the substrate. The upper layer can include only one polymer or a blend of two or more polymers.

[0027] The upper layer pigment can be selected to have a high absorption at the operating wavelength of the laser to be used in printing. For example, when a carbon dioxide laser having a specific operating wavelength, e.g., a 10.6-micron operating wavelength, is used, the upper layer can include a barium sulfate pigment. In some embodiments, the upper layer includes a titanium dioxide pigment. The pigment of the upper layer is typically dispersed within the thermoplastic polymer of the upper layer. Although barium sulfate and titanium dioxide pigments are mentioned here, use of other suitable pigments, alone or in combination, is contemplated.

[0028] The thickness of the upper layer can, for example, range from 12 microns to 175 microns, e.g., from 12 microns to 110 microns, from 28 microns to 126 microns, from 45 microns to 142 microns, from 61 microns to 159 microns, or from 77 microns to 175 microns. In terms of upper limits, the upper layer thickness can be less than 175 microns, less than 159 microns, less than 142 microns, less than 126 microns, less than 110 microns, less than 94 microns, less than 77 microns, less than 61 microns, less than 45 microns, or less than 28 microns. In terms of lower limits, the upper layer thickness can be greater than 12 microns, e.g., greater than 28 microns, greater than 45 microns, greater than 61 microns, greater than 77 microns, greater than 94 microns, greater than 110 microns, greater than 126 microns, greater than 142 microns, or greater than 159 microns. Larger thicknesses, e.g., greater than 175 microns, and smaller thicknesses, e.g., less than 12 microns, are also contemplated.

Substrate Lower Layer

[0029] The composition of the lower layer can vary widely. In some cases, the lower layer of the multilayer substrate can include a polymer that is a polyolefin. For example, the lower layer polymer can be a thermoplastic polyolefin such as polyethylene, polypropylene,

polymethylpentene, polybutene, or combinations thereof. The lower layer polymer can be an elastomeric polyolefin such as polyisobutylene, ethylene propylene rubber, ethylene propylene diene monomer rubber, or combinations thereof.

[0030] In some embodiments, the lower layer of the multilayer substrate can include a polymer that is a polyester. For example, the lower layer polymer can be an aliphatic homopolymer polyester such as polyglycolic acid, polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyhydroxybutyrate, or a combination thereof. The lower layer polymer can be an aliphatic copolymer polyester such as polyethylene adipate, polybutylene succinate, poly (3- hydroxybutyrate-co-3 -hydroxy valerate), or a combination thereof. The lower layer polymer can be a semi-aromatic copolymer polyester such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, or a combination thereof. In certain aspects, the lower layer polymer is crosslinked. In some embodiments, the lower layer polymer is a melamine polyester matrix. The lower layer can include only one polymer or a blend of two or more polymers. Combinations of the aforementioned polymers are also within the contemplation of this disclosure.

[0031] The lower layer can in some cases be cured. In certain aspects, the lower layer is dried. In some embodiments, the lower layer is crosslinked. The curing, drying, and/or crosslinking of the lower layer can be through processes involving, but not limited to, radiation or heat treatment.

[0032] The lower layer pigment can be selected to have a high reflectivity at the operating wavelength of the laser to be used for printing. For example, when a carbon dioxide laser having a 10.6-micron operating wavelength is used, the lower layer can include a metal oxide pigment. In certain aspects, the lower layer pigment has a lower absorbance than the upper layer pigment at the laser operating wavelength. For example, the lower layer pigment can have an absorbance that is at least 5% lower than that of the upper layer pigment, e.g., at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 12%, at least 14%, at least 16%, at least 18%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 100% lower than that of the upper layer pigment. In certain aspects, the lower layer pigment has a higher reflectivity than the upper layer pigment at the laser operating wavelength. For example, the lower layer pigment can have a reflectivity that is at least 5% higher than that of the upper layer pigment, e.g., at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 12%, at least 14%, at least 16%, at least 18%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 100% higher than that of the upper layer pigment. In some embodiments, the lower layer pigment has a black, red, blue, or green appearance.

[0033] In certain aspects, the lower layer pigment is a metal oxide, or a chemical compound thereof. For example, the lower layer pigment can be zinc iron chromite, iron chromite, nickel antimony titanate, chrome antimony titanium buff, chromium green, cobalt chromite, cobalt titanate, chromium green-black, copper chromite black, chrome iron nickel black, cobalt aluminate, cobalt chromium aluminate, zinc ferrite, or a combination thereof. In some embodiments, the lower layer pigment is a ferrous oxide, such as magnetite black, burnt umber, iron oxide black, iron oxide brown, iron oxide red, iron oxide yellow, or a combination thereof.

[0034] The concentration of the lower layer pigment within the lower layer can, for example, range from 1 wt% to 50 wt%, e.g., from 1 wt% to 30.4 wt%, from 5.9 wt% to 35.3 wt%, from 10.8 wt% to 40.2 wt%, from 15.7 wt% to 45.1 wt%, or from 20.6 wt% to 50 wt%. In terms of upper limits, the lower layer pigment concentration can be less than 50 wt%, e.g., less than 45.1 wt%, less than 40.2 wt%, less than 35.3 wt%, less than 30.4 wt%, less than 25.5 wt%, less than 20.6 wt%, less than 15.7 wt%, less than 10.8 wt%, or less than 5.9 wt%. In terms of lower limits, the lower layer pigment concentration can be greater than 1 wt%, e.g., greater than 5.9 wt%, greater than 10.8 wt%, greater than 15.7 wt%, greater than 20.6 wt%, greater than 25.5 wt%, greater than 30.4 wt%, greater than 35.3 wt%, greater than 40.2 wt%, or greater than 45.1 wt%. Higher concentrations, e.g., greater than 50 wt%, and lower concentrations, e.g., less than 1 wt%, are also contemplated.

[0035] The thickness of the lower layer can, for example, range from 2 microns to 100 microns, e.g., from 2 microns to 61 microns, from 12 microns to 71 microns, from 22 microns to 80 microns, from 31 microns to 90 microns, or from 41 microns to 100 microns. In terms of upper limits, the upper layer thickness can be less than 100 microns, less than 90 microns, less than 80 microns, less than 71 microns, less than 61 microns, less than 51 microns, less than 41 microns, less than 31 microns, less than 22 microns, or less than 12 microns. In terms of lower limits, the upper layer thickness can be greater than 2 microns, e.g., greater than 12 microns, greater than 22 microns, greater than 31 microns, greater than 41 microns, greater than 51 microns, greater than 61 microns, greater than 71 microns, greater than 81 microns, or greater than 90 microns. Larger thicknesses, e.g., greater than 100 microns, and smaller thicknesses, e.g., less than 2 microns, are also contemplated.

[0036] The ratio of the upper layer thickness to the lower layer thickness can, for example, range from 1 to 88, e.g., from 1 to 53, from 10 to 62, from 18 to 71, from 27 to 79, or from 36 to 88. In terms of upper limits, the ratio of the upper layer thickness to the lower layer thickness can be less than 88, e.g., less than 79, less than 71, less than 62, less than 53, less than 45, less than 36, less than 27, less than 18, or less than 10. In terms of lower limits, the ratio of the upper layer thickness to the lower layer thickness can be greater than 1, e.g., greater than 10, greater than 18, greater than 27, greater than 36, greater than 45, greater than 53, greater than 62, greater than 71, or greater than 79. Higher ratios, e.g., greater than 88, and lower ratios, e.g., less than 1, are also contemplated.

Substrate Intermediate Layer

[0037] In some embodiments, the intermediate layer of the multilayer substrate comprises a metal selected to have reflectivity at the operating wavelength of the laser to be used for printing. In certain aspects, the intermediate layer has a higher reflectivity than the upper layer at the laser operating wavelength. In some embodiments, the intermediate layer materials comprise a metal selected to have absorption at the operating wavelength of the laser to be used for printing. In some embodiments, the intermediate layer materials are selected to have a high heat dissipation. In some embodiments, the intermediate layer materials are selected for suitability to act as a tie layer that joins the dissimilar chemistries of the upper layer and lower layer of the multilayer substrate. The intermediate layer metal can be, for example, copper, aluminum, nickel- chromium, titanium, or chemical compounds thereof. In certain aspects, the intermediate layer comprises aluminum, or a chemical compound thereof. Aluminum can be a particularly useful metal of the intermediate layer when a laser having an operative wavelength in the near infrared range is used, as aluminum can have an absorption in this wavelength range of approximately 15%. In some embodiments, the intermediate layer metal comprises aluminum oxide. In some embodiments, the intermediate layer consists of aluminum oxide.

[0038] For intermediate layers that are relatively thick, e.g., significantly greater than nanometer scale, the reflectivity of the intermediate layer can advantageously function to protect the lower layer thereunder from the laser light used for printing on the multilayer substrate. As the thickness of the intermediate layer decreases, the significance of this reflectivity also decreases. For intermediate layers that are relatively thin, e.g., with thicknesses at the nanometer scale, heat dissipation and laser light absorption become more important in preventing the lower layer from being adversely affected during printing.

[0039] The thickness of the intermediate layer can, for example, range from 0.3 nanometers to 15 nanometers, e.g., from 0.3 nanometers to 3.1 nanometers, from 0.4 nanometers to 4.6 nanometers, from 0.7 nanometers, to 6.9 nanometers, from 1 nanometer to 10 nanometers, or from 1.4 nanometers to 15 nanometers. In terms of upper limits, the intermediate layer thickness can be less than 15 nanometers, e.g., less than 10 nanometers, less than 6.9 nanometers, less than 4.6 nanometers, less than 3.1 nanometers, less than 2.1 nanometers, less than 1.4 nanometers, less than 1 nanometer, less than 0.7 nanometer, or less than 0.4 nanometers. In terms of lower limits, the intermediate layer thickness can be greater than 0.3 nanometers, greater than 0.4 nanometers, greater than 0.7 nanometers, greater than 1 nanometers, greater than 2.1 nanometers, greater than 3.1 nanometers, greater than 4.6 nanometers, greater than 6.9 nanometers, or greater than 10 nanometers. Larger thicknesses, e.g., greater than 15 nanometers, and smaller thicknesses, e.g., less than 0.3 nanometers, are also contemplated.

[0040] The ratio of the lower layer thickness to the intermediate layer thickness can, for example, range from 100 to 100,000, e.g., from 100 to 6300, from 200 to 13,000, from 400 to 25,000, from 800 to 50,000, or from 1600 to 100,000. In terms of upper limits, the ratio of the lower layer thickness to the intermediate layer thickness can be less than 100,000, e.g., less than 50,000, less than 25,000, less than 13,000, less than 6300, less than 3200, less than 1600, less than 800, less than 400, or less than 200. In terms of lower limits, the ratio of the lower layer thickness to the intermediate layer thickness can be greater than 100, e.g., greater than 200, greater than 400, greater than 800, greater than 1600, greater than 3200, greater than 6300, greater than 13,000, greater than 25,000, or greater than 50,000. Higher ratios, e.g., greater than 100,000, and lower ratios, e.g., less than 100, are also contemplated.

[0041] The ratio of the upper layer thickness to the intermediate layer thickness can, for example, range from 10,000 to 1,000,000, e.g., from 10,000 to 160,000, from 16,000 to 250,000, from 25,000 to 400,000, from 40,000 to 630,000, or from 63,000 to 1,000,000. In terms of upper limits, the ratio of the upper layer thickness to the intermediate layer thickness can be less than 1,000,000, e.g., less than 630,000, less than 400,000, less than 250,000, less than 160,000, less than 100,000, less than 63,000, less than 40,000, less than 25,000, or less than 16,000. In terms of lower limits, the ratio of the upper layer thickness to the intermediate layer thickness can be greater than 10,00, e.g., greater than 16,000, greater than 25,000, greater than 40,000, greater than 63,000, greater than 100,000, greater than 160,000, greater than 250,000, greater than 400,000, or greater than 630,000. Higher ratios, e.g., greater than 1,000,000, and lower ratios, e.g., less than 10,000, are also contemplated.

Substrate Adhesive Layer

[0042] In some embodiments, the multilayer substrate includes an adhesive layer. The adhesive layer can be arranged within the multilayer substrate such that the lower layer of the substrate is disposed between the intermediate layer of the substrate and the adhesive layer. The adhesive layer can include one or more silicone adhesives. The silicone adhesives can include

polyorganosiloxane dispersions or gums, such as polydimethylsiloxanes,

polydimethyl/methylvinyl siloxanes, polydimethyl/methylphenyl siloxanes,

polydimethyl/diphenyl siloxanes, and blends thereof. The silicone adhesives can include silicone resins, such as MQ resins or blends of resins. Non-limiting examples of such silicone adhesive compositions which are commercially available include adhesives 7651, 7652, 7657, Q2-7406, Q2-7566, Q2-7735 and 7956, all available from Dow Corning (Midland, MI); SILGRIP™ PSA518, 590, 595, 610, 915, 950 and 6574 available from Momentive Performance Materials (Waterford, NY); and KRT-009 and KRT-026 available from Shin-Etsu Silicone (Akron, OH).

[0043] The adhesive layer, in some cases, can comprise an acrylic-based or silicone-based monomer. In some embodiments, the adhesive layer comprises one or more acrylic-based monomers selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2- ethylhexyl acrylate, isooctyl acrylate, isobornyl acrylate, isononyl acrylate, isodecyl acrylate, methylacrylate, methyl methacrylate, methylbutyl acrylate, 4-methyl-2-pentyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate. Useful alkyl acrylate esters include n-butyl acrylate, 2-ethyl hexyl acrylate, isooctyl acrylate. In one embodiment, the acrylic ester monomer is polymerized in the presence of a vinyl ester such as vinyl acetate, vinyl butyrate, vinyl propionate, vinyl isobutyrate, vinyl valerate, vinyl versitate, and the like. The vinyl ester can be present in a total amount of up to about 35 wt%, based on total weight of the monomers forming the acrylate main chain. In one embodiment, an acrylic ester monomer is copolymerized with an unsaturated carboxylic acid. The unsaturated carboxylic acid can include, among others, acrylic acid, methacrylic acid, itaconic acid, beta carboxy ethyl acrylate and the like.

[0044] In some embodiments, the adhesive layer comprises one or more silicone-based monomers selected from the group consisting of siloxanes, silane, and silatrane glycol. In some embodiments, the adhesive layer comprises one or more silicone-based monomers selected from the group consisting of l,4-bis[dimethyl[2-(5-norbornen-2-yl)ethyl]silyl]benzene; 1,3- dicyclohexyl-l,l,3,3-tetrakis(dimethylsilyloxy)disiloxane; 1,3-dicyclohexyl-l, 1,3, 3- tetrakis(dimethylvinylsilyloxy)disiloxane; 1,3-dicyclohexyl-l, 1,3, 3-tetrakis[(norbornen-2- yl)ethyldimethylsilyloxy]disiloxane; 1 ,3-divinyltetramethyldisiloxane; 1 , 1 , 3,3,5, 5-hexamethyl- l,5-bis[2-(5-norbornen-2-yl)ethyl]trisiloxane; l,l,3,3-tetramethyl-l,3-bis[2-(5-norbornen-2- yl)ethyl]disiloxane; 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane; N-[3- (trimethoxysilyl)propyl]-N'-(4-vinylbenzyl)ethylenediamine; and 3- [tris(trimethylsiloxy)silyl]propyl vinyl carbamate.

[0045] The adhesive layer, in some cases, can comprise a silicone polymer, an acrylic polymer, or a methacrylic polymer. Suitable acrylic polymers include, but are not limited to, S2000N, S692N, AT20N, XPE 1043, and XPE 1045, all available from Avery Dennison (Glendale, CA); and H9232 available from BASF (Florham Park, NJ). In one embodiment, the acrylic polymer composition is blended with multiblock copolymers such as styreneisoprene-styrene (SIS), styrene-ethylenebutylene-styrene (SEBS) and the like in an amount of up to 30% by dry weight of the polymer. Examples of useful triblocks are available from Kraton Polymer Inc. (Houston, TX).

[0046] A wide array of functional groups can be incorporated in a polymer of adhesive layer. The functional groups can be incorporated into the polymer formed from the acrylic-based monomer or the silicon-based monomer, for example as end segments. Representative functional groups include, without limitation, hydroxy, epoxy, cyano, isocyanate, amino, aryloxy, aryalkoxy, oxime, aceto, epoxyether and vinyl ether, alkoxymethylol, cyclic ethers, thiols, benzophenone, acetophenone, acyl phosphine, thioxanthone, and derivatives of benzophenone, acetophenone, acyl phosphine, and thioxanthone.

[0047] Functional groups that have hydrogen-bonding capability are well known and include carboxyl, amide, hydroxyl, amino, pyridyl, oxy, carbamoyl and mixtures thereof. In some embodiments, an acrylic polymer backbone of an adhesive layer polymer includes the polar comonomers vinyl pyrrolidone and acrylic acid. Examples of other monomers with hydrogen- bonding functionality include methacrylic acid, vinyl alcohol, caprolactone, ethylene oxide, ethylene glycol, propylene glycol, 2-hydroxyethyl acrylate, N-vinyl caprolactam,

acetoacetoxy ethyl methacrylate and others.

[0048] In some embodiments, the adhesive layer comprises one or more co-monomers bearing a functionality that can be further crosslinked. Examples of crosslinkable co-monomers include (meth) acrylic acid, 2-hydroxyethyl acrylate, glycidyl methacrylate, itaconic acid, allyl glycidyl ether and the like, and mixtures thereof. Functional moieties, such as those described above, can be used to crosslink polymer chains, to attach the high side chains to the backbone, or both.

[0049] The adhesive layer can further comprises a crosslinker, which can vary widely.

Examples of suitable crosslinkers include multifunctional acrylates and methacrylates, such as diacrylates (ethylene glycol diacrylate, propylene glycol diacrylate, polyethylene glycol diacrylate, and hexanediol diacrylate), dimethacrylates (ethylene glycol diacrylate, diethylene glycol dimethacrylate, and 1,3 butane glycol dimethacrylate), triacrylates (trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, and pentaerythritol triacrylate), and trimethacrylates (pentaerythritol trimethacrylate and trimethylolpropane trimethacrylate), as well as divinyl esters, such as divinylbenzene, divinyl succinate, divinyl adipate, divinyl maleate, divinyl oxalate, and divinyl malonate.

[0050] Additional crosslinkers can be employed to form crosslinks in a silicone-based matrix. In some embodiments, a peroxide crosslinker, such as dibenzoylperoxide, is suitable. In some embodiments, the crosslinker is a compound that contains silicon-hydride functionality. Non- limiting examples of such crosslinkers include PEROXAN BP 50W, PEROXAN BIC, and PEROXAN Bu, all available from Pergan (Bocholt, Germany); LUPEROX® A75 and A98 commercially available from Arkema (King of Prussia, PA); and PERKADOX® CH-50 and PD 50SPS from Akzo Nobel (Chicago, IL). Crosslinking can be facilitated and/or promoted by heating or other techniques generally depending upon the chemical system employed.

[0051] Other exemplary chemical crosslinkers that can be used in the adhesive layer include, but are not limited to, di-, tri- or poly-isocyanates with or without a catalyst (such as dibutyltin dilaureate); ionic crosslinkers; and di-, tri- or poly-functional aziridines. Illustrative, non-limiting examples of commercially available chemical crosslinkers include aluminum acetyl acetonate (AAA) available from NOAH Technologies (San Antonio, TX); TYZOR® available from DuPont (Wilmington, DE); XAMA® available from Bayer (Pittsburgh, PA); and PAPI™ and VORONATE™, available from Dow Chemical.

[0052] The adhesive layer can optionally comprise one or more tackifiers or resins, and these tackifiers (when employed) can vary widely. In some cases, the tackifier of the adhesive layer includes a single tackifier. In other cases, the tackifier comprises a mixture of multiple tackifier products. Suitable commercial tackifiers include (but are not limited to), for example, hydrogenated DCPD resins such as HD1100, HD1120 from Luhua (China), and E5400 from Exxon Mobil (Houston, TX). Other suitable hydrogenated resins include fully hydrogenated resins such as REGALITE™ SI 100, R1090, Rl 100, CIOOR, and CIOOW from Eastman

(Kingsport, TN); and fully hydrogenated C9 resins QM-100A and QM-115A from Hebei Qiming (China).

[0053] The adhesive layer can also optionally comprise one or more plasticizers, and these plasticizers (when employed) can vary widely. In some embodiments, the plasticizer has a high molecular weight and/or a high viscosity. In some cases, the plasticizer includes a single plasticizer. In other cases, the plasticizer comprises a mixture of multiple plasticizer products. Suitable commercial plasticizers include (but are not limited to), for example, KN 4010 and KP 6030 from Sinopec (Beijing, China); Claire F55 from Tianjin (China); F550 from Formosa Petrochemical (China), and various polyisobutene products.

[0054] The adhesive layer can optionally comprise one or more waxes, and these waxes (when employed) can vary widely. In some cases, the wax includes a single wax. In other cases, the wax comprises a mixture of multiple wax products. The wax can have a higher molecular weight so as to advantageously improve oil migration. Exemplary waxes include microcrystalline waxes, paraffin waxes, hydrocarbon waxes, and combinations thereof. Suitable commercial waxes include (but are not limited to), for example, Sasol wax 3971, 7835, 6403, 6805, and 1800 from Sasol (Houston, TX); A-C1702, A-C6702, A-C5180 from Honeywell (Mornstown, NJ); and MICROWAX™ FG 7730 and MICROWAX™ FG 8113 from Paramelt (Muskegon, MI).

[0055] In some embodiments, the adhesive layer includes one or more high surface area inorganic fillers or combinations of fillers and pigments such as carbon black, calcium carbonate, titanium dioxide, silica (hydrophilic and hydrophobic modified), mica, talc, kaolin, clay, diatomaceous earth, barium sulfate, aluminum sulfate, or mixtures of two or more thereof.

Examples of commercially available high surface area inorganic fillers include those available from Evonik Degussa GmbH (Essen, Germany). In certain aspects, a useful filler combination includes an anti-blocking agent which is chosen depending on the processing and/or use conditions. Examples of such agents include, for example, silica, talc, diatomaceous earth, and any mixtures thereof. The filler particles can be finely divided substantially water-insoluble inorganic filler particles.

[0056] The finely divided substantially water-insoluble inorganic filler particles can include particles of metal oxides. The metal oxide constituting the particles can be a simple metal oxide, e.g., the oxide of a single metal, or it can be a complex metal oxide, e.g., the oxide of two or more metals. The particles of metal oxide can be particles of a single metal oxide or they can be a mixture of different particles of different metal oxides. Examples of suitable metal oxides include alumina, silica, and titania. Other oxides can optionally be present in minor amount. Examples of such optional oxides include, but are not limited to, zirconia, hafnia, and yttria. Other metal oxides that can optionally be present are those that are ordinarily present as impurities such as for example, iron oxide. For purposes of the present specification and claims, silicon is considered to be a metal. When the particles are particles of alumina, most often the alumina is alumina monohydroxide. Particles of alumina monohydroxide, AIO(OH), and their preparation are known.

[0057] Additives, such as carbon black and other pigments, ultraviolet light absorbers, ultraviolet stabilizers, antioxidants, fire retardant agents, thermally or electrically conductive agents, post curing agents, and the like can be blended into the adhesive layer to modify its properties. These additives can also include, for example, one or more inhibitors, defoamers, colorants, luminescents, buffer agents, anti-blocking agents, wetting agents, matting agents, antistatic agents, acid scavengers, processing aids, extrusion aids, and others. Ultraviolet light absorbers include hydroxyphenyl benzotriazoles and hydrobenzophenones. Antioxidants include, for example, hindered phenols, amines, and sulfur and phosphorus hydroxide decomposers, such as Irganox 1520L.

[0058] The adhesive layer can also comprise one or more solvents. Nonlimiting examples of suitable solvents include toluene, xylene, tetrahydrofuran, hexane, heptane, cyclohexane, cyclohexanone, methylene chloride, isopropanol, ethanol, ethyl acetate, butyl acetate, isopropyl acetate, and combinations thereof. It will be appreciated that the present subject matter adhesive layer not limited to such solvents and can utilize a wide array of other solvents, additives, and/or viscosity adjusting agents, such as reactive diluents.

Release Liner

[0059] In some embodiments, the multilayer substrate includes a release liner connected to the adhesive layer. One face of the liner layer can be directly adjacent to the adhesive layer, or there can be one or more intervening layers between the adhesive layer and the liner layer. The releasable liner can function as a protective cover such that the release liner remains in place until the printed label is ready for attachment to an object or surface. If a liner or release liner is included in the multilayer substrate, a wide array of materials and configurations can be used for the liner. In many embodiments, the liner is a paper or paper-based material. In many other embodiments, the liner is a polymeric film of one or more polymeric materials. Typically, at least one face of the liner is coated with a release material such as a silicone or silicone-based material. As will be appreciated, the release coated face of the liner is placed in contact with the otherwise exposed face of the adhesive layer. Prior to application of the label to a surface of interest, the liner is removed to thereby expose the adhesive layer of the laminate. The liner can be in the form of a single sheet. Alternatively, the liner can be in the form of multiple sections or panels.

Low Power Laser

[0060] The synergy of the multilayer substrate and the laser contributes, at least in part, to the surprising improvements discussed herein. Without being bound by theory, it is believed that selection of the laser, in combination with the use of the aforementioned multilayer substrate provides an unexpected result due to the ability of the nanometer-scale intermediate layer to at least partially absorb the laser light and protect the lower layer thereunder. The particular features of the laser and the upper layer also allow the substrate to include a white upper layer above a black lower layer to produce high contrast black-on white printing upon laser-based printing.

[0061] For example, in some case, the laser of the printing system can be selected to have a low power, e.g., less than 100 watts, to advantageously provide the system with a reduced size as well as a reduced manufacturing and operating cost. The operating power of the laser can, for example, range from 10 watts to 100 watts, e.g., from 10 watts to 64 watts, from 19 watts to 73 watts, from 28 watts to 82 watts, from 37 watts to 91 watts, or from 46 watts to 100 watts. In terms of upper limits, the laser operating power can be less than 100 watts, e.g., less than 91 watts, less than 82 watts, less than 73 watts, less than 64 watts, less than 55 watts, less than 46 watts, less than 37 watts, less than 28 watts, or less than 19 watts. In terms of lower limits, the laser operating power can be greater than 10 watts, e.g., greater than 19 watts, greater than 28 watts, greater than 37 watts, greater than 46 watts, greater than 55 watts, greater than 64 watts, greater than 73 watts, greater than 82 watts, or greater than 91 watts. Higher powers, e.g., greater than 100 watts, are also contemplated.

[0062] In some embodiments, the operating power of the laser ranges from 0.3 watts to 15 watts, e.g., from 0.3 watts, to 3.1 watts, from 0.4 watts to 4.6 watts, from 0.7 watts, to 6.9 watts, from 1 watt to 10 watts, or from 1.4 watts to 15 watts. In terms of upper limits, the laser operating power can be less than 15 watts, e.g., less than 10 watts, less than 6.9 watts, less than 4.6 watts, less than 3.1 watts, less than 2.1 watts, less than 1.4 watts, less than 1 watt, less than 0.7 watts, or less than 0.4 watts. In terms of lower limits, the laser operating power can be greater than 0.3 watts, greater than 0.4 watts, greater than 0.7 watts, greater than 1 watt, greater than 2.1 watts, greater than 3.1 watts, greater than 4.6 watts, greater than 6.9 watts, or greater than 10 watts. Lower powers, e.g., less than 0.3 watts, are also contemplated.

[0063] In some embodiments, the laser operates in the long- wavelength infrared range, e.g., at a wavelength ranging from 8 microns to 15 microns. For example, the long-wavelength laser can be a carbon dioxide laser having a 9.4-micron wavelength, or a carbon dioxide laser having a 10.6-micron wavelength. In some embodiments, the laser operates in the mid- wavelength infrared range, e.g., at a wavelength ranging from 3 microns to 8 microns. For example, the mid- wavelength laser can be a carbon monoxide laser having a 5-micron wavelength. Commercial carbon monoxide lasers suitable for use in the systems of the present disclosure are available, for example, from Coherent (Santa Clara, CA). In some embodiments, the laser operates in the short-wavelength infrared range, e.g., at a wavelength ranging from 1.4 microns to 3 microns. For example, the short-wavelength laser can be a diode laser having a 905-nanometer wavelength, a diode laser having a 980-nanometer wavelength, an ytterbium-doped laser having a 1030-nanometer wavelength, an ytterbium-doped fiber laser having a 1030-nanometer wavelength, a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser having a 1064- nanometer wavelength, or a neodymium-doped yttrium orthovanadate (Nd:YV0₄) laser having a 1064-nanometer wavelength. Of these short- wavelength lasers, the diode lasers and the ytterbium-doped laser are generally preferred over solid state lasers such as the Nd: YAG laser and the Nd:YV0₄ laser due to the advantageous smaller size and cost of the diode and ytterbium- doped lasers.

[0064] The operating wavelength of the laser can, for example, range from 0.6 microns to 15 microns, e.g., from 0.6 microns to 4.1 microns, from 0.8 microns to 5.7 microns, from 1.1 microns to 7.9 microns, from 1.6 microns to 11 microns, or from 2.2 microns to 15 microns. In terms of upper limits, the laser operative wavelength can be less than 15 microns, e.g., less than 11 microns, less than 7.9 microns, less than 5.7 microns, less than 4.1 microns, less than 3 microns, less than 2.2 microns, less than 1.6 microns, less than 1.1 microns, or less than 0.8 microns. In terms of lower limits, the laser operating wavelength can be greater than 0.6 microns, e.g., greater than 0.8 microns, greater than 1.1 microns, greater than 1.6 microns, greater than 2.2 microns, greater than 3 microns, greater than 4.1 microns, greater than 5.7 microns, greater than 7.9 microns, or greater than 11 microns. Longer wavelengths, e.g., greater than 15 microns, and shorter wavelengths, e.g., less than 0.6 microns, are also contemplated.

[0065] The laser can be a continuous wave laser, or a pulsed laser. In embodiments in which the laser is pulsed, the length of the pulses as well as their repetition frequency can be selected to produce a desired printing speed and printing contrast. In certain aspects, the pulsed laser has a pulse duration in the millisecond range, e.g., from 0.1 millisecond to 100 millisecond. The pulse duration can, for example, be from 0.1 milliseconds to 6.3 milliseconds, from 0.2 milliseconds to 13 milliseconds, from 0.4 milliseconds to 25 milliseconds, from 0.8 milliseconds to 50 milliseconds, or from 1.6 milliseconds to 100 milliseconds. In terms of upper limits, the pulse duration can be less than 100 milliseconds, e.g., less than 50 milliseconds, less than 25 milliseconds, less than 13 milliseconds, less than 6.3 milliseconds, less than 3.2 milliseconds, less than 1.6 milliseconds, less than 0.8 milliseconds, less than 0.4 milliseconds, or less than 0.2 milliseconds. In terms of lower limits, the pulse duration can be greater than 0.1 milliseconds, e.g., greater than 0.2 milliseconds, greater than 0.4 milliseconds, greater than 0.8 milliseconds, greater than 1.6 milliseconds, greater than 3.2 milliseconds greater than 6.3 milliseconds, greater than 13 milliseconds, greater than 25 milliseconds, or greater than 50 milliseconds.

[0066] In certain aspects, the pulsed laser has a pulse duration in the microsecond range, e.g., from 0.1 microseconds to 100 microseconds. The pulse duration can, for example, be from 0.1 microseconds to 6.3 microseconds, from 0.2 microseconds to 13 microseconds, from 0.4 microseconds to 25 microseconds, from 0.8 microseconds to 50 microseconds, or from 1.6 microseconds to 100 microseconds. In terms of upper limits, the pulse duration can be less than 100 microseconds, e.g., less than 50 microseconds, less than 25 microseconds, less than 13 microseconds, less than 6.3 microseconds, less than 3.2 microseconds, less than 1.6

microseconds, less than 0.8 microseconds, less than 0.4 microseconds, or less than 0.2 microseconds. In terms of lower limits, the pulse duration can be greater than 0.1 microseconds, e.g., greater than 0.2 microseconds, greater than 0.4 microseconds, greater than 0.8

microseconds, greater than 1.6 microseconds, greater than 3.2 microseconds greater than 6.3 microseconds, greater than 13 microseconds, greater than 25 microseconds, or greater than 50 microseconds.

[0067] In certain aspects, the pulsed laser has a pulse duration in the nanosecond range, e.g., from 0.1 nanoseconds to 100 nanoseconds. The pulse duration can, for example, be from 0.1 nanoseconds to 6.3 nanoseconds, from 0.2 nanoseconds to 13 nanoseconds, from 0.4

nanoseconds to 25 nanoseconds, from 0.8 nanoseconds to 50 nanoseconds, or from 1.6 nanoseconds to 100 nanoseconds. In terms of upper limits, the pulse duration can be less than 100 nanoseconds, e.g., less than 50 nanoseconds, less than 25 nanoseconds, less than 13 nanoseconds, less than 6.3 nanoseconds, less than 3.2 nanoseconds, less than 1.6 nanoseconds, less than 0.8 nanoseconds, less than 0.4 nanoseconds, or less than 0.2 nanoseconds. In terms of lower limits, the pulse duration can be greater than 0.1 nanoseconds, e.g., greater than 0.2 nanoseconds, greater than 0.4 nanoseconds, greater than 0.8 nanoseconds, greater than 1.6 nanoseconds, greater than 3.2 nanoseconds greater than 6.3 nanoseconds, greater than 13 nanoseconds, greater than 25 nanoseconds, or greater than 50 nanoseconds.

[0068] In certain aspects, the pulsed laser has a pulse duration in the picosecond range, e.g., from 0.1 picoseconds to 100 picoseconds. The pulse duration can, for example, be from 0.1 picoseconds to 6.3 picoseconds, from 0.2 picoseconds to 13 picoseconds, from 0.4 picoseconds to 25 picoseconds, from 0.8 picoseconds to 50 picoseconds, or from 1.6 picoseconds to 100 picoseconds. In terms of upper limits, the pulse duration can be less than 100 picoseconds, e.g., less than 50 picoseconds, less than 25 picoseconds, less than 13 picoseconds, less than 6.3 picoseconds, less than 3.2 picoseconds, less than 1.6 picoseconds, less than 0.8 picoseconds, less than 0.4 picoseconds, or less than 0.2 picoseconds. In terms of lower limits, the pulse duration can be greater than 0.1 picoseconds, e.g., greater than 0.2 picoseconds, greater than 0.4 picoseconds, greater than 0.8 picoseconds, greater than 1.6 picoseconds, greater than 3.2 picoseconds greater than 6.3 picoseconds, greater than 13 picoseconds, greater than 25 picoseconds, or greater than 50 picoseconds.

[0069] In certain aspects, the pulsed laser has a frequency in the kilohertz range, e.g., from 0.1 kilohertz to 100 kilohertz. The pulse frequency can, for example, be from 0.1 kilohertz to 6.3 kilohertz, from 0.2 kilohertz to 13 kilohertz, from 0.4 kilohertz to 25 kilohertz, from 0.8 kilohertz to 50 kilohertz, or from 1.6 kilohertz to 100 kilohertz. In terms of upper limits, the pulse frequency can be less than 100 kilohertz, e.g., less than 50 kilohertz, less than 25 kilohertz, less than 13 kilohertz, less than 6.3 kilohertz, less than 3.2 kilohertz, less than 1.6 kilohertz, less than 0.8 kilohertz, less than 0.4 kilohertz, or less than 0.2 kilohertz. In terms of lower limits, the pulse frequency can be greater than 0.1 kilohertz, e.g., greater than 0.2 kilohertz, greater than 0.4 kilohertz, greater than 0.8 kilohertz, greater than 1.6 kilohertz, greater than 3.2 kilohertz greater than 6.3 kilohertz, greater than 13 kilohertz, greater than 25 kilohertz, or greater than 50 kilohertz.

[0070] In certain aspects, the pulsed laser has a frequency in the megahertz range, e.g., from 0.1 megahertz to 100 megahertz. The pulse frequency can, for example, be from 0.1 megahertz to 6.3 megahertz, from 0.2 megahertz to 13 megahertz, from 0.4 megahertz to 25 megahertz, from 0.8 megahertz to 50 megahertz, or from 1.6 megahertz to 100 megahertz. In terms of upper limits, the pulse frequency can be less than 100 megahertz, e.g., less than 50 megahertz, less than 25 megahertz, less than 13 megahertz, less than 6.3 megahertz, less than 3.2 megahertz, less than 1.6 megahertz, less than 0.8 megahertz, less than 0.4 megahertz, or less than 0.2 megahertz. In terms of lower limits, the pulse frequency can be greater than 0.1 megahertz, e.g., greater than 0.2 megahertz, greater than 0.4 megahertz, greater than 0.8 megahertz, greater than 1.6 megahertz, greater than 3.2 megahertz greater than 6.3 megahertz, greater than 13 megahertz, greater than 25 megahertz, or greater than 50 megahertz.

Methods

[0071] The present disclosure also relates to methods of printing using the multilayer substrates and printing systems described above. The methods include providing any of the described systems, and operating the laser at a first power. The laser can be focused on a portion of the upper layer of the multilayer substrate to be printed upon. In certain aspects, the operating of the laser at the first power to print upon the multilayer substrate involves the ablating of portions of the substrate upper layer. In these embodiments, the printed portions of the upper layer are removed by the laser from the multilayer substrate, exposing the lower layer thereunder. This exposed lower layer then becomes the visible print of the substrate. For example, in some embodiments, a white upper layer covers a black layer. Those regions of the upper layer removed by the disclosed laser-based printing then appear black in the printed substrate product. An example of the ablating of the upper layer of a described multilayer substrate is illustrated in FIGS. lA and IB.

[0072] In certain aspects, the inventors have found that by operating of the laser at the first power to print upon the multilayer substrate involves causing a phase change in portions of the substrate upper layer. In these embodiments, the heat load of the laser eliminates the scattering effect of pigment inclusions, e.g., barium sulfate "bubbles", within the upper layer. In this way, the printed portions of the upper layer transition from being opaque to being transparent, exposing the lower layer thereunder. This exposed lower layer then becomes the visible print of the substrate. For example, in some embodiments, a white upper layer covers a black layer. Those regions of the upper layer made transparent by the disclosed laser-based printing then appear black in the printed substrate product. It is appreciated that the upper and lower layers can be colors other than white and black, respectively. In general, the upper and lower layer compositions are selected to have a high visual contrast with one another to enhance the contrast of printing on the substrate.

[0073] In some embodiments, the method also includes operating the laser at a second power greater than the first power. For example, the second power can be at least 5% greater than the first power, e.g., at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 12%, at least 14%, at least 16%, at least 18%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 100% greater than the first power. By thus increasing the operating power of the laser, the beam of the laser can be made capable of penetrating and cutting through the upper layer, intermediate layer, and lower layer of the multilayer substrate. In certain aspects, the laser operating at the higher power does not cut through an adhesive layer of the multilayer substrate. By not cutting through the adhesive layer, the result of the printing and cutting can be a series or pattern of distinct printed and cut labels that are each affixed to a single adhesive web. The first and second power may vary widely, and in some cases may be selected from the ranges and limits discussed above. [0074] In some embodiments, the method also includes operating the laser at a different operating time or speed than during the cutting. By thus increasing the operating time of the laser, or decreasing the operating speed, the beam of the laser can be made capable of penetrating and cutting through the upper layer, intermediate layer, and lower layer of the multilayer substrate. In certain aspects, the laser operating at the longer time or slower speed does not cut through an adhesive layer of the multilayer substrate. By not cutting through the adhesive layer, the result of the printing and cutting can be a series or pattern of distinct printed and cut labels that are each affixed to a single adhesive web.

[0075] In certain aspects, the method includes translating the multilayer substrate relative to the laser, or translating the laser is relative to the multilayer substrate. In some embodiments, the multilayer substrate is translated relative to the laser along a first translation axis, and the laser is translated relative to the multilayer substrate along a second translational axis that is

substantially orthogonal to the first axis. The simultaneous or sequential translations of the multilayer substrate and the laser can be synchronized or otherwise coordinated such that the focal point of the laser is aligned with locations on the surface of the multilayer substrate targeted for printing and/or cutting.

[0076] In some embodiments, the laser remains substantially stationary, while the beam emitted from the laser is deflected or steered to different positions in a controlled fashion via laser scanning. Laser scanning configurations suitable for use with the disclosed methods and systems include those using galvanometers, micro-electromechanical system (MEMS) mirrors, a digital micromirror device (DMD), piezoelectric actuators, magnetostrictive actuators, or a rotating polygon mirror. The laser scanning speed can be synchronized with a translational speed of the multilayer substrate relative to the laser. The laser scanning can include raster scanning or vector scanning. In some embodiments in which the heat load of printed areas need to be adjusted via controlling software and algorithms, vector scanning is preferred. Such scanning control can be particularly useful in enhancing printing contrast and avoiding burning at dense areas of printing.

[0077] The following embodiments are contemplated. All combinations of features and embodiments are contemplated.

[0078] Embodiment 1 : A system for laser-based printing, the system comprising: a laser having an operating wavelength ranging from 0.6 microns to 15 microns; and a multilayer substrate having: an upper layer including a thermoplastic polymer resin and an upper layer pigment; a lower layer including a lower layer polymer and a lower layer pigment, wherein the lower payer pigment has a lower absorbance than the upper layer pigment at the operating wavelength of the laser, and wherein the lower layer pigment has a higher reflectivity than the upper layer pigment at the operating wavelength of the laser; and an intermediate layer including a metal, wherein the intermediate layer is disposed between the upper layer and the lower layer, wherein the intermediate layer has a higher reflectivity than the upper layer at the operating wavelength of the laser, and wherein the intermediate layer has a thickness less than 10 nm.

[0079] Embodiment 2: An embodiment of embodiment 1, wherein the multilayer substrate further comprises: an adhesive layer, wherein the lower layer is disposed between the intermediate layer and the adhesive layer.

[0080] Embodiment 3 : An embodiment of embodiment 1 or 2, wherein the lower layer polymer comprises a polyolefin.

[0081] Embodiment 4: An embodiment of embodiment 1 or 2, wherein the lower layer polymer comprises a polyester.

[0082] Embodiment 5: An embodiment of embodiment 1 or 2, wherein the lower layer polymer comprises crosslinking.

[0083] Embodiment 6: An embodiment of embodiment 5, wherein the lower layer polymer comprises a melamine polyester matrix.

[0084] Embodiment 7: An embodiment of any of the embodiments of embodiment 1-6, wherein the thermoplastic polymer resin comprises polyethylene terephthalate.

[0085] Embodiment 8: An embodiment of any of the embodiments of embodiment 1-7, wherein the upper layer pigment comprises barium sulfate.

[0086] Embodiment 9: An embodiment of any of the embodiments of embodiment 1-8, wherein the metal comprises aluminum or a chemical compound thereof.

[0087] Embodiment 10: An embodiment of any of the embodiments of embodiment 1-9, wherein the lower layer has a thickness ranging from 2 micron to 100 microns.

[0088] Embodiment 11 : An embodiment of any of the embodiments of embodiment 1-10, wherein the upper layer has a thickness ranging from 12 microns to 175 microns.

[0089] Embodiment 12: An embodiment of any of the embodiments of embodiment 1-11, wherein the ratio of the upper layer thickness to the lower layer thickness ranges from 1 to 88. [0090] Embodiment 13: An embodiment of any of the embodiments of embodiment 1-12, wherein the ratio of the lower layer thickness to the intermediate layer thickness ranges from 100 to 100,000.

[0091] Embodiment 14: An embodiment of any of the embodiments of embodiment 1-13, wherein the ratio of the upper layer thickness to the intermediate layer thickness ranges from 10,000 to 1,000,000.

[0092] Embodiment 15: An embodiment of any of the embodiments of embodiment 1-14, wherein the laser is a carbon dioxide laser, a carbon monoxide laser, or a diode laser.

[0093] Embodiment 16: An embodiment of any of the embodiments of embodiment 1-15, wherein the laser has an operating power ranging from 0.3 watts to 15 watts.

[0094] Embodiment 17: A multilayer substrate comprising: an upper layer including a thermoplastic polymer resin and an upper layer pigment; a lower layer including a lower layer polymer and a lower layer pigment; and an intermediate layer including a metal, wherein the intermediate layer is disposed between the upper layer and the lower layer, and wherein the intermediate layer has a thickness less than 10 nm.

[0095] Embodiment 18: An embodiment of embodiment 17, further comprising: an adhesive layer, wherein the lower layer is disposed between the intermediate layer and the adhesive layer.

[0096] Embodiment 19: An embodiment of embodiment 17 or 18, wherein the lower layer polymer comprises a polyolefin.

[0097] Embodiment 20: An embodiment of embodiment 17 or 18, wherein the lower layer polymer comprises a polyester.

[0098] Embodiment 21 : An embodiment of any of the embodiments of embodiment 17 or 18, wherein the lower polymer comprises crosslinking.

[0099] Embodiment 22: An embodiment of embodiment 21, wherein the lower layer polymer comprises a melamine polyester matrix.

[00100] Embodiment 23: An embodiment of any of the embodiments of embodiment 17-22, wherein the thermoplastic polymer resin comprises polyethylene terephthalate.

[00101] Embodiment 24: An embodiment of any of the embodiments of embodiment 17-23, wherein the first pigment comprises barium sulfate.

[00102] Embodiment 25: An embodiment of any of the embodiments of embodiment 17-24, wherein the metal comprises aluminum or a chemical compound thereof. [00103] Embodiment 26: An embodiment of any of the embodiments of embodiment 17-25, wherein the lower layer has a thickness ranging from 2 microns to 100 microns.

[00104] Embodiment 27: An embodiment of any of the embodiments of embodiment 17-26, wherein the upper layer has a thickness ranging from 12 microns to 175 microns.

[00105] Embodiment 28: An embodiment of any of the embodiments of embodiment 17-27, wherein the ratio of the upper layer thickness to the lower layer thickness ranges from 1 to 88.

[00106] Embodiment 29: An embodiment of any of the embodiments of embodiment 17-28, wherein the ratio of the upper layer thickness to the intermediate layer thickness ranges from 100 to 100,000.

[00107] Embodiment 30: An embodiment of any of the embodiments of embodiment 17-29, wherein the ratio of the lower layer thickness to the intermediate layer thickness ranges from 10,000 to 1,000,000.

[00108] Embodiment 31 : A method of printing comprising: providing the system of an embodiment of any of the embodiments of embodiment 1-16; ablating at least a portion of the upper layer of the multilayer substrate, wherein the ablating comprises operating the laser at a first power to remove a portion of the upper layer at a first location on a surface of the multilayer substrate, thereby exposing a portion of the lower layer at the first location; and cutting at least a portion of the multilayer substrate, wherein the cutting comprises operating the laser at a second power greater than the first power to remove a portion of the upper layer and a portion of the lower layer at a second location on the surface of the multilayer substrate.

[00109] Embodiment 32: An embodiment of embodiment 31, further comprising: subsequent to the ablating and prior to the cutting, translating the multilayer substrate relative to the laser.

[00110] Embodiment 33: An embodiment of embodiment 31 further comprising: subsequent to the ablating and prior to the cutting, translating the laser relative to the multilayer substrate.

[00111] The present disclosure will be better understood in view of the following non-limiting examples.

Examples

[00112] A series of multilayer substrates were constructed, each with a 50-micron white upper layer comprising polyethylene terephthalate and barium sulfate filler, and a black lower layer. Example 1 included an intermediate layer comprising aluminum oxide. Example 2 included an intermediate layer comprising 50% aluminum. Example 3 included an intermediate layer comprising nichrome. Comparative Example A did not include an intermediate layer. The multilayer substrates of the examples also included an adhesive layer comprising acrylic adhesive P22, available from Nirotek (Kibbutz Nir-David, Israel), and a liner.

[00113] Examples 1 - 3 and Comparative Example A were tested in a laser-based inkless printing process with a carbon dioxide laser at an operating frequency of 20 kilohertz. During printing with the laser, the beam was operated at a speed of 500 mm/second, and during cutting with the laser, the beam was operated at a speed of 200 mm/second. The results of the testing are shown in FIG. 2 (Example 1), FIG. 3 (Example 2), FIG. 4 (Example 3), and FIG. 5 (Comparative Example A).

[00114] After printing and cutting, the contrast, color homogeneity, linearity, and other print quality characteristics of the substrate was graded according to the ISO 29158:2011 (2011) Direct Part Mark standard protocol quality guidelines. The images of FIGS. 2-5 and the results shown in Table 1 below demonstrate that the multilayer substrates of Examples 1 - 3 achieved superior print qualities that met industrial acceptability standards (a B rating), while Comparative Example A failed to provide acceptable print quality (a D rating).

Table 1. Laser-base inkless printing results

Example 1 Example 2 Example 3 Comparative A

Upper layer PET/BaS0₄ PET/BaS0₄ PET/BaS0₄ PET/BaS0₄

Intermediate layer AlOx Al 50% NiCr None

Laser C0₂ CO2 CO2 CO2

ISO 29158 grade B B B D

[00115] FIGS. 6 and 7 provide images based on Comparative Examples B and C, which utilized laser ablation printing. Comparative Example B was a 3M product that included a black upper layer and a white lower layer, and as a result the printing thereon had the form of a white pattern upon a black background. Although the edges of the printing were suitably well-defined, the contrast between the printed and background regions was unacceptably low. Furthermore, as discussed above, such white-on-black printing is susceptible to additional loss of contrast and readability due to chemical contamination and/or abrasion. [00116] Comparative Example C was a DataLase product that included black-on- white printing. The markings of this printing detrimentally suffered from poor edge definition and low contrast, as can be seen in the image of FIG. 7.

[00117] Example 4 is a multilayer substrate as disclosed herein. The printed substrate of Example 4 is shown in FIG. 8 This printed markings of Example 4 beneficially have a much higher contrast than those of either Comparative Examples B and C, and to have better edge definition than that of Comparative Example C, demonstrating further the advantages in print quality afforded by the particular multilayer substrate properties and features that have been described above.

[00118] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference. In addition, it should be understood that aspects of the invention and portions of various embodiments and various features recited below and/or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims

We claim;

1. A system for laser-based printing, the system comprising:

a laser having an operating wavelength ranging from 0.6 microns to 15 microns; and

a multilayer substrate having:

an upper layer including a thermoplastic polymer resin and an upper layer pigment;

a lower layer including a lower layer polymer and a lower layer pigment, wherein the lower payer pigment has a lower absorbance than the upper layer pigment, and wherein the lower layer pigment has a higher reflectivity than the upper layer pigment; and

an intermediate layer including a metal, wherein the intermediate layer is disposed between the upper layer and the lower layer, wherein the intermediate layer has a higher reflectivity than the upper layer at the operating wavelength of the laser, and wherein the intermediate layer has a thickness less than 10 nm.

2. The system of claim 1, wherein the multilayer substrate further comprises:

an adhesive layer, wherein the lower layer is disposed between the intermediate layer and the adhesive layer.

3. The system of claim 1 or 2, wherein the lower layer polymer comprises a polyolefin.

4. The system of claim 1 or 2, wherein the lower layer polymer comprises a polyester.

5. The system of claim 1 or 2, wherein the lower layer polymer comprises crosslinking.

6. The system of claim 5, wherein the lower layer polymer comprises a melamine polyester matrix.

7. The system of any one of claims 1 -6, wherein the thermoplastic polymer resin polyethylene terephthalate.

8. The system of any one of claims 1-7, wherein the upper layer pigment comprises barium sulfate.

9. The system of any one of claims 1-8, wherein the metal comprises aluminum or a chemical compound thereof.

10. The system of any one of claims 1-9, wherein the lower layer has a thickness ranging from 2 micron to 100 microns.

11. The system of any one of claims 1-10, wherein the upper layer has a thickness ranging from 12 microns to 175 microns.

12. The system of any one of claims 1-11, wherein the ratio of the upper layer thickness to the lower layer thickness ranges from 1 to 88.

13. The system of any one of claims 1-12, wherein the ratio of the lower layer thickness to the intermediate layer thickness ranges from 100 to 100,000.

14. The system of any one of claims 1-13, wherein the ratio of the upper layer thickness to the intermediate layer thickness ranges from 10,000 to 1,000,000.

15. The system of any one of claims 1-14, wherein the laser is a carbon dioxide laser, a carbon monoxide laser, or a diode laser.

16. The system of any one of claims 1-15, wherein the laser has an operating power ranging from 0.3 watts to 15 watts

17. A multilayer substrate comprising:

an upper layer including a thermoplastic polymer resin and an upper layer pigment; a lower layer including a lower layer polymer and a lower layer pigment; and an intermediate layer including a metal, wherein the intermediate layer is disposed between the upper layer and the lower layer, and wherein the intermediate layer has a thickness less than 10 nm.

18. The multilayer substrate of claim 17, further comprising:

an adhesive layer, wherein the lower layer is disposed between the intermediate layer and the adhesive layer.

19. The multilayer substrate of claim 17 or 18, wherein the lower layer polymer is a polyolefin.

20. The multilayer substrate of claim 17 or 18, wherein the lower layer polymer is a polyester.

21. The multilayer substrate of claim 17 or 18, wherein the lower polymer is crosslinked.

22. The multilayer substrate of claim 21, wherein the lower layer polymer is a melamine polyester matrix.

23. The multilayer substrate of any one of claims 17-22, wherein the thermoplastic polymer resin is polyethylene terephthalate.

24. The multilayer substrate of any one of claims 17-23, wherein the first pigment is barium sulfate.

25. The multilayer substrate of any one of claims 17-24, wherein the metal is aluminum or a chemical compound thereof.

26. The multilayer substrate of any one of claims 17-25, wherein the lower layer has a thickness ranging from 2 micron to 100 micron.

27. The multilayer substrate of any one of claims 17-26, wherein the upper layer has a thickness ranging from 12 micron to 175 micron.

28. The multilayer substrate of any one of claims 17-27, wherein the ratio of the upper layer thickness to the lower layer thickness ranges from 1 to 88.

29. The multilayer substrate of any one of claims 17-28, wherein the ratio of the upper layer thickness to the intermediate layer thickness ranges from 100 to 100,000.

30. The multilayer substrate of any one of claims 17-29, wherein the ratio of the lower layer thickness to the intermediate layer thickness ranges from 10,000 to 1,000,000.

31. A method of printing comprising:

providing the system of any one of claims 1-16;

ablating at least a portion of the upper layer of the multilayer substrate, wherein the ablating comprises operating the laser at a first power to remove a portion of the upper layer at a first location on a surface of the multilayer substrate, thereby exposing a portion of the lower layer at the first location; and

cutting at least a portion of the multilayer substrate, wherein the cutting comprises operating the laser at a second power greater than the first power to remove a portion of the upper layer and a portion of the lower layer at a second location on the surface of the multilayer substrate.

32. The method of claim 31, further comprising:

subsequent to the ablating and prior to the cutting, translating the multilayer substrate relative to the laser.

33. The method of claim 31 further comprising:

subsequent to the ablating and prior to the cutting, translating the laser relative to the multilayer substrate.