Crosstalk reduction for microcapsule imaging systems

Abstract

A microcapsule is provided for a microcapsule imaging sheet comprising a color filtering shell and a core material comprising a leuco dye or dye precursor, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material. An imaging sheet including such microcapsules reduces undesirable crosstalk between microcapsules of various colors and significantly improves the color fidelity of an image reproduced thereby.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 18,074,412, filed December 2, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to the field of microcapsule imaging systems, and more particularly to microcapsules having color filtering shells for use in microcapsule imaging systems. Background Art

[0004] Since the 1980s, single-page, self-contained, full-color microcapsule imaging systems have been developed (e.g., manufactured by Mead Corporation of Miamisburg, Ohio). ). In these imaging systems, the imaging sheet includes a layer of microcapsules containing a photohardenable or photosoftenable material or composition and a leuco dye in an internal phase, and the imaging sheet is exposed to actinic radiation image by image. Typically, the photosensitive composition comprises a photopolymerizable multifunctional acrylate, a photoinitiator, and a color former. Typically, the microcapsules are hardened image by image by actinic radiation, and when the exposed imaging sheet passes through a pressure roller, the microcapsules can be broken image by image to release the internal phase encapsulated therein. The leuco dye thus released migrates to the developer material and reacts to form a continuous tone full-color image whose color density (or grayscale) is modulated by the exposure energy (time or pulse width), intensity (pulse amplitude), and / or pulse frequency. Such self-contained single-sheet imaging systems can be used for lightweight, portable, high-speed printing applications.

[0005] Positive images are typically obtained with such photohardening microcapsule imaging systems. Conversely, negative images can be obtained with photosoftening microcapsule imaging systems or via alternative techniques.

[0006] In addition to single-sheet, self-contained systems, microcapsule imaging systems can also consist of two separate sheets: a microcapsule sheet and a dye developer sheet. Positive images can also be obtained by image-wise exposing the microcapsule sheet to form a latent image, and then rupturing the microcapsules and transferring the released leuco dye to the developer sheet to develop the image thereon. Summary of the Invention

[0007] The image quality of a photosensitive imaging system, including the aforementioned microcapsule imaging system, depends significantly on the spectral sensitivity of the three microcapsules and the emission spectrum of the light source used. For example, in a full-color microcapsule imaging system using red (R), green (G), and blue (B) sensitive photoinitiators, such as cyanine borate initiators, and R, G, and B light sources (e.g., R-, G-, and B-LEDs or OLEDs used in LED or OLED displays, or R-, G-, and B-light passing through color filters in LCD displays), the absorption spectra of the B and G photoinitiators overlap significantly in the 440-500 nm range. Similarly, the absorption spectra of the G and R photoinitiators overlap significantly in the 540-600 nm range. Furthermore, the R, G, and B emission spectra of the light source used in an OLED or LCD display also overlap significantly. Therefore, exposing an imaging sheet to light with wavelengths within this overlapping range can cause crosstalk by curing more than one type of capsule.

[0008] If any photoreactive crosstalk occurs—for example, if more than one type of microcapsule is hardened, or one type of microcapsule is hardened by more than one light source when the system is written by only one light source—the fidelity of the color reproduction process can degrade. The colors of the printed image can then be contaminated with unwanted colors, and the color gamut can be significantly degraded. Therefore, photosensitizers / initiators with narrow, well-separated spectral sensitivities and light sources with narrow, well-separated emission spectra that are appropriately matched to the spectral sensitivities of the corresponding photosensitizers / initiators are highly desirable for high-quality color reproduction.

[0009] Unfortunately, most photoinitiators or photosensitizers exhibit very broad spectral sensitivities, and most modulatable light sources, including self-luminous OLEDs and backlit LCDs with R-, G-, and B color filters, exhibit very broad emission spectra. When such broadband light sources are used to print microencapsulated imaging media with typical spectral sensitivities, severe crosstalk is observed. Semiconductor light-emitting devices, including LEDs and lasers, exhibit relatively narrow emission spectra. Unfortunately, there are very limited commercially available devices with acceptable λ max , size and power efficiency of LED or laser to choose from, and the cost of printing applications is usually very high.

[0010] On the other hand, it is also difficult to find a set of R-, G-, and B-photoinitiators with narrow-band absorption spectra. In fact, cyanine borate photoinitiators were chosen for microencapsulated imaging systems primarily due to their high thermal stability and quantum efficiency, as well as their relatively narrow absorption spectra. However, even with cyanine borate photoinitiators, severe crosstalk was still observed. Most other known photosensitizers or photoinitiators exhibit much broader absorption spectra and poorer quantum efficiencies than the commonly used cyanine borate photoinitiators.

[0011] Even if all three pairs of well-matched photoinitiators and light sources are identified, the requirements for high quantum efficiency of the photosensitizer / initiator and high power output of the light source for high-speed printing applications further make the task extremely difficult and expensive, or even impossible. Therefore, there remains an unmet need for an effective and low-cost solution to reduce or eliminate crosstalk to achieve high-quality printing.

[0012] The present disclosure relates to an improved full-color microcapsule imaging system that uses photosensitive microcapsules that include a color filter housing or a housing that can filter out undesirable wavelengths of primary light. The color filter housing greatly reduces undesirable crosstalk between microcapsules of various colors and significantly improves the color fidelity of the image reproduced thereby. This is particularly advantageous for digital imaging systems because the microcapsules described herein greatly reduce the need to select a light source whose emission wavelength perfectly matches the spectral sensitivity of the photosensitizer / initiator used in the microcapsule. Fine-tuning the emission spectrum of a light source such as an LED or OLED or the absorption spectrum of a photosensitizer / initiator while maintaining their quantum efficiency is difficult or even impossible. The present disclosure provides an effective and low-cost solution to greatly reduce undesirable crosstalk and improve the color image fidelity of a microcapsule imaging system.

[0013] In one aspect that may be combined with any other aspect or embodiment, the present disclosure is directed to a photosensitive microcapsule for microcapsule imaging sheeting, comprising a color filtering shell; and a core material comprising a leuco dye or dye precursor, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material.

[0014] In some embodiments, the photohardenable material comprises a photopolymerizable or crosslinkable monomer or oligomer. In some embodiments, the polymerizable or crosslinkable monomer or oligomer is selected from multifunctional acrylates or methacrylates, multifunctional vinyl ethers, multifunctional allyl or vinyl benzenes, oligomers, dendrimers, or blends thereof.

[0015] In some embodiments, the multifunctional acrylate is pentaerythritol triacrylate (PETA-3), pentaerythritol tetraacrylate (PETA-4), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), or neopentyl glycol diacrylate (NPGDA).

[0016] In some embodiments, the photosoftenable material comprises a photodegradable or photodepolymerizable polymer.

[0017] In some embodiments, the leuco dye is a cyan, magenta, yellow, black leuco dye or any combination thereof. In some embodiments, the photoinitiator is a red-sensitive, green-sensitive or blue-sensitive cyanine borate, hemicyanine borate or ketocoumarin. In some embodiments, the photoinitiator is a cyanine borate, hemicyanine borate, triarylmethane, squarylium or thiopyrylium dye. In some embodiments, the photoinitiator or photosensitizer comprises a UV-sensitive, blue-sensitive, green-sensitive, red-sensitive or near-IR-sensitive photoinitiator or sensitizer.

[0018] In some embodiments, the photosensitive microcapsules are sensitive to a specific color or a specific range of radiation spectrum, and the shell comprises one or more color filter dyes or pigments that allow wavelengths corresponding to the color or radiation spectrum range to pass through to the core material, but selectively absorb or filter out all or part of the radiation outside the specific color or range. In some embodiments, the one or more color filter dyes or pigments are bleachable. In some embodiments, the one or more color filter dyes or pigments are thermally bleachable or photobleachable.

[0019] In some embodiments, the particular color or range is red, green, blue, cyan, magenta, or yellow. In some embodiments, the radiation spectrum ranges from about 330 nm to about 900 nm.

[0020] In some embodiments, one or more filter dyes or pigments comprise functional groups that react with one or more shell-forming materials. In some embodiments, the functional groups are selected from the group comprising: -OH, -SH, -NH2, -N-HR, -CH2OH, -CH2OR, -CHO, -CONH2, -CONHR, urea, thiourea, isocyanate, thioisocyanate, epoxide, and precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl, or heteroatom derivatives thereof, particularly those with shorter chain lengths. In some embodiments, the functional groups are selected from the group comprising: -OH, -SH, -NH2, -N-HR, -CONH2, -NCO, -NCS-, -CH2OH, -CH2OR, -CHO, and precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl, or heteroatom derivatives thereof.

[0021] In some embodiments, one or more shell-forming materials are included in the internal phase or the oil phase and form an outer shell by interfacial polymerization or crosslinking during microencapsulation. In some embodiments, one or more shell-forming materials are included in the internal phase and / or the external phase and form an outer shell by interfacial polymerization or crosslinking during microencapsulation. In some embodiments, the one or more shell-forming materials included in the oil phase or the internal phase are selected from the group consisting of polyfunctional isocyanates, thioisocyanates, and epoxides or their precursors.

[0022] In some embodiments, one or more shell-forming materials are included in the external phase or aqueous phase and form the shell during the microencapsulation process by interfacial or in situ polymerization or crosslinking, phase separation or coagulation. In some embodiments, the one or more shell-forming materials in the external phase or aqueous phase comprise water-soluble compounds with reactive functional groups, including but not limited to -OH, -SH, -NH2, -N-HR, -COOH, -CH2OR, -CHO, or precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl, or heteroatom derivatives thereof, particularly those with shorter chain lengths (e.g., those with alkyl chains containing one to four carbons). In some embodiments, the one or more shell-forming materials are selected from the group comprising urea, amines, urea formaldehyde, melamine formaldehyde, poly(N-hydroxymethyl acrylamide), gelatin, gum arabic, pectin, carboxymethyl cellulose, and oligomers, copolymers, or blends thereof.

[0023] In some embodiments, the color filter housing comprises one or more color filter dyes or pigments. In some embodiments, the color filter dyes are thermally bleachable or photobleachable.

[0024] In some embodiments, the photoinitiator or photosensitizer is red-sensitive and the color of the color filter housing is magenta, yellow, or a combination thereof. In some embodiments, the photoinitiator or photosensitizer is green-sensitive and the color of the color filter housing is cyan, yellow, or any combination thereof. In some embodiments, the photoinitiator or photosensitizer is blue-sensitive and the color of the color filter housing is magenta, cyan, or any combination thereof. In some embodiments, the photoinitiator or photosensitizer is IR-sensitive and the color of the color filter housing is cyan, magenta, yellow, or any combination thereof.

[0025] In some embodiments, the color filter dye or pigment is a magenta (green-absorbing) and / or cyan (red-absorbing) dye or pigment for blue-sensitive microcapsules.

[0026] In some embodiments, the color filter dye or pigment is a yellow (blue-absorbing) and / or cyan (red-absorbing) dye or pigment for green-sensitive microcapsules. In some embodiments, the color filter dye or pigment is yellow pigment 155 or CI Direct Yellow 86.

[0027] In some embodiments, the color filter dye or pigment is a yellow (blue-absorbing) and / or magenta (green-absorbing) dye or pigment for red-sensitive microcapsules. In some embodiments, the color filter dye or pigment is Pigment Violet 19 or CI Disperse Red 60.

[0028] In some embodiments, the amount of one or more color filter dyes or pigments present in the microcapsules is from about 0.01 to about 3 phi (parts by weight per hundred parts of the internal phase or per hundred parts of the core material). In some embodiments, the amount of one or more color filter dyes or pigments present in the microcapsules is from about 0.05 to about 1.0 phi.

[0029] In some embodiments, when the photosensitive microcapsules are green-sensitive or red-sensitive microcapsules and the one or more filter dyes or pigments include yellow (blue-absorbing) filter dyes or pigments, the total absorption optical density is from about 0.005 to about 0.3, preferably from about 0.05 to about 0.2, in the range of about 450 to about 500 nm. Based on the extinction coefficient, the concentration of the dye or pigment used in the shell is from about 0.05 to about 2 phi, preferably from about 0.1 to about 1 phi.

[0030] In some embodiments, when the photosensitive microcapsules are blue-sensitive or red-sensitive microcapsules and the one or more filter dyes or pigments are magenta (green-absorbing) filter dyes or pigments, the absorption optical density is from about 0.005 to about 0.3, preferably from about 0.05 to about 0.2, in the range of about 550 to about 600 nm. Based on the extinction coefficient, the concentration of the dye or pigment used in the shell is from about 0.05 to about 2 phi, preferably from about 0.1 to about 1 phi.

[0031] In some embodiments, the photosensitive microcapsules have an average diameter or D of about 4.0 μm to about 9.0 μm. 50 In some embodiments, the photosensitive microcapsules have an average diameter or D of about 5.0 μm to about 6.5 μm. 50 In some embodiments, the core material does not contain any color filter dyes or pigments.

[0032] In some embodiments, the core material further comprises a free radical inhibitor, retardant or antioxidant. In some embodiments, the free radical inhibitor, antioxidant or retardant is selected from the group comprising phenols, anilines, N-oxides of hindered amines, CuO, copper dithiocarbamates, copper carboxylates or manganese carboxylates and thiuram (thiocarbamoyl) derivatives, such as

[0033] where R 1 、R 2 、R 3 and R 4 Each of the groups is independently an alkyl group having 1 to 8 carbon atoms or a phenyl group.

[0034] In some embodiments, the free radical inhibitor is selected from the group consisting of phenol free radical inhibitors: alkyl gallates, butylated hydroxyanisole, 3,5-di-tert-butylbutyl-4-hydroxytoluene, vitamin E, 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-ol ( E201), triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ( 245), 3-{[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]oxy}-2,2-bis({[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]-oxy}methyl)-propyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate ( 1010), 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine ( MD 1024, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene ( 1076), 2,2'-thiobis(6-tert-butyl-p-cresol) 1081), N,N'-hexane-1,6-diylbis(3-3,5-di-tert-butyl-4-hydroxyphenyl-propionamide)( 1098), 3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropionic acid thiodi-2,1-ethanediyl ester ( 1035), phenylpropionic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-C7-C9 branched chain alkyl ester ( 1135), 3,3',3',5,5',5'-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl)tri-p-cresol ( 1330), (1,1-di-tert-butyl)-4-hydroxyphenyl)methyl)ethylphosphonate) 1425), 1,3,5-tris[4-hydroxy-3,5-bis(2-methyl-2-propyl)benzyl]-1,3,5-triazinane-2,4,6-trione ( 3114), 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol ( 565) and others Primary antioxidant.

[0035] In some embodiments, the free radical inhibitor is an N-oxide of a hindered amine, wherein the hindered amine is selected from the list comprising bis(2,2,6,6,-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770DF), bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (ADK STAB LA-72), tetrakis(2,2,6,6-tetramethyl-4-piperidinyl)butane-1,2,3,4-tetracarboxylate (ADK STAB LA-57), and bis(1-undecanyloxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate (ADKSTAB LA-81).

[0036] In some embodiments, the free radical inhibitor, retarder, or antioxidant is present in the internal phase at a concentration of about 0.1 to about 1.0 parts by weight per hundred parts of monomer. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present in the internal phase at a concentration of about 0.05 to 0.8 parts by weight per hundred parts of monomer. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present at a concentration of about 0.3 to about 0.8 phi. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present at a concentration of about 0.1 to 0.6 phi.

[0037] In some embodiments, the core material further comprises a co-initiator, an oxygen scavenger, or an autoxidant.

[0038] In another aspect, a microcapsule imaging sheet is provided, comprising: a first substrate; and a photosensitive microcapsule layer comprising photosensitive microcapsules in contact with a first surface of the first substrate, wherein the photosensitive microcapsules comprise: a color filter shell, which may further comprise a color filter dye or pigment; and a core material comprising a leuco dye, a photoinitiator or a photosensitizer, and a photohardenable or photosoftenable material.

[0039] In some embodiments, the photohardenable material comprises a photopolymerizable or crosslinkable monomer or oligomer. In some embodiments, the polymerizable or crosslinkable monomer or oligomer is selected from a multifunctional acrylate or methacrylate, a multifunctional vinyl ether, a multifunctional allyl or vinyl benzene, an oligomer, a dendrimer, or a blend thereof. In some embodiments, the multifunctional acrylate is pentaerythritol triacrylate (PETA-3), pentaerythritol tetraacrylate (PETA-4), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), or neopentyl glycol diacrylate (NPGDA).

[0040] In some embodiments, the photosoftenable material comprises a photodegradable or photodepolymerizable polymer.

[0041] In some embodiments, the microcapsule imaging sheet is a full-color imaging sheet containing photosensitive microcapsules, including red-sensitive microcapsules, green-sensitive microcapsules, and blue-sensitive microcapsules.

[0042] In some embodiments, the photosensitive microcapsule sheet further comprises a developer. In some embodiments, the photosensitive microcapsule sheet further comprises a separate developer layer. In some embodiments, the separate developer layer is coated or laminated onto the photosensitive microcapsule layer.

[0043] In some embodiments, any of the microcapsule imaging sheets described herein further comprises a developer layer in contact with: (i) the microcapsule layer; and / or (ii) the developer substrate.

[0044] In some embodiments, any of the microcapsule imaging sheets described herein further comprises an adhesive layer positioned between the developer layer and the microcapsule layer.

[0045] In some embodiments, any of the microcapsule imaging sheets described herein further comprises a primer layer positioned between the microcapsule layer and the first substrate.

[0046] In some embodiments, the developer substrate is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polyolefin, cyclic olefin copolymer (COC), cellulose acetate, or copolymers, blends, or composites thereof.

[0047] In some embodiments, the developer layer comprises a Lewis acid, an acidic clay, or one or more compounds comprising a phenolic group or a carboxylic acid group, or a metal complex thereof. In some embodiments, the developer layer comprises a novolac resin, a salicylic acid derivative, a zincate derivative thereof, or a combination, copolymer, blend, or composite thereof.

[0048] In some embodiments, the first substrate is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polyolefin, cyclic olefin copolymer (COC), cellulose acetate, or copolymers, blends, or composites thereof.

[0049] In some embodiments, the microcapsule imaged sheeting has an increased or improved color gamut and / or fidelity of color reproduction of the original image.

[0050] In another aspect, provided is a method of making an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a microcapsule layer to produce a microcapsule-coated first substrate; and (ii) contacting the microcapsule-coated first substrate with a developer layer to produce the imaging sheeting.

[0051] In another aspect, provided is a method of making an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a developer layer to produce a developer-coated first substrate; and (ii) contacting the developer-coated first substrate with a microcapsule layer to produce the imaging sheeting.

[0052] In another aspect, a method of preparing an imaging sheeting according to any of the imaging sheetings described herein is provided, the method comprising coating a first surface of a first substrate with a mixture of a developer and photosensitive microcapsules to produce the imaging sheeting. In some embodiments, the method further comprises contacting the first substrate coated with the microcapsule / developer mixture with a second substrate.

[0053] In another aspect, provided is a method of preparing an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a microcapsule layer to produce a microcapsule-coated first substrate; (ii) coating a second substrate with a developer layer to produce a developer-coated second substrate; and (iii) contacting the developer layer of the developer-coated second substrate with the microcapsule layer of the microcapsule-coated first substrate to produce the imaging sheeting.

[0054] In another aspect, a method of imaging or printing is provided, comprising: exposing an imaged sheeting according to any of the imaged sheetings described herein to heat or radiation imagewise, wherein the exposure is sufficient to selectively fix the leuco dye in the exposed or hardened microcapsules in the microcapsule layer to produce a latent image; and developing the latent image by pressure and / or heat, thereby releasing the leuco dye to react with a developer and form an image. In some embodiments, the radiation is UV, visible light, near IR, or IR light.

[0055] In another aspect, a method of imaging or printing is provided, comprising: exposing an imaged sheeting according to any of the imaged sheetings described herein to heat or radiation imagewise, wherein the exposure is sufficient to harden or soften the microcapsules in the microcapsule layer to produce a latent image; and developing the latent image by pressure and / or heat, thereby releasing the leuco dye or dye precursor and forming an image. In some embodiments, the radiation is UV, visible light, near IR, or IR light.

[0056] Other aspects and / or embodiments of the present invention will be provided in the embodiments of the present technology described below, but are not limited thereto. The following embodiments are illustrative and explanatory, but not intended to be limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Various objects, aspects, features and advantages of the present disclosure will become more apparent and better understood by referring to the embodiments in conjunction with the accompanying drawings.

[0058] Figure 1A and 1B Shown are absorption spectra of illustrative examples of the color filter pigments / dyes described herein. Figure 1A Shown are the absorption spectra of a representative green photoinitiator and a yellow filter (blue absorbing) pigment, Pigment Yellow 155. Figure 1BThe absorption spectra of a representative red photoinitiator and a magenta / violet filter (blue- and green-absorbing) pigment, Pigment Violet 19, are shown.

[0059] Figure 2A and 2B Schematic diagram of an imaging sheet containing green-sensitive microcapsules containing a color filter sheet. Figure 2A The sheet before development is shown, and Figure 2B The developed sheet is shown.

[0060] Figures 3A-3B The pigment used in Example 2, Pigment Yellow 155 ( Figure 3A ) and Pigment Violet 19 ( Figure 3B )'s chemical structure.

[0061] Figure 4 The normalized reflected optical density (OD) of the developed image as a function of blue light energy is shown. 1-1 is the yellow OD curve for the blue-sensitive imaging sheet of Example 1-1 (Control-B), which contains a yellow leuco dye (CAS: 123521-47-1) in the microcapsule core. 1-2 is the magenta OD curve for the green-sensitive imaging sheet of Example 1-2 (Control-G), which contains a magenta leuco dye (CAS: 50292-95-0) in the microcapsule core. 2-1, 2-2, and 2-3 are the magenta OD curves for the green-sensitive imaging sheet of Examples 2-1, 2-2, and 2-3, which contain a magenta leuco dye in the core and 0.244 phi, 0.488 phi, and 0.733 phi Yellow Pigment 155 in the shell, respectively.

[0062] Figure 5 The normalized reflected optical density (OD) of the developed image is shown as a function of green light energy. 1-2 is the magenta OD curve for the green-sensitive imaging sheet of Example 1-2 (Control-G). 1-3 is the cyan OD curve for the red-sensitive imaging sheet of Example 1-3 (Control-R), which contains a leuco-cyan dye (CAS: 114090-18-5) in the microcapsule core. 2-4, 2-5, and 2-6 are the cyan OD curves for the red-sensitive imaging sheet of Examples 2-4, 2-5, and 2-6, which contain a leuco-cyan dye in the core and 0.188 phi, 0.376 phi, and 0.556 phi of Pigment Violet 19 in the shell, respectively.

[0063] Figure 6The normalized reflected optical density (OD) of the developed image as a function of green light energy is shown. 1-2 is the magenta OD curve for the green-sensitive imaging sheet of Example 1-2 (Control-G). 1-3 is the cyan OD curve for the red-sensitive imaging sheet of Example 1-3 (Control-R). 2-4, 2-5, and 2-6 are the cyan OD curves for the red-sensitive imaging sheets of Examples 2-4, 2-5, and 2-6, which have 0.188 phi, 0.376 phi, and 0.556 phi of Pigment Violet 19, respectively, in the housing. 2-1, 2-2, and 2-3 are the magenta OD curves for the green-sensitive imaging sheets of Examples 2-1, 2-2, and 2-3, which have 0.244 phi, 0.488 phi, and 0.733 phi of Yellow Pigment 155, respectively, in the housing.

[0064] Figure 7A The normalized reflected optical density (OD) of the developed image as a function of blue light energy is shown. 1-1 is the yellow OD curve for the blue-sensitive image sheet of Example 1-1 (Control-B). 2-3, 3-1, and 3-2 are images containing 0.15 phm, 0.3 phm, and 0.6 phm of antioxidant in the core material, respectively. Magenta OD curves for the green-sensitive imaging sheets of Examples 2-3, 3-1, and 3-2 containing 0.733 phi Filter Yellow 155 in the housing.

[0065] Figure 7B The normalized reflected optical density (OD) of the developed image as a function of green light energy is shown. 1-1 is the yellow OD curve for the blue-sensitive image sheet of Example 1-1 (Control-B). Curves 2-3, 3-1, and 3-2 are the magenta OD curves for the green-sensitive image sheet of Examples 2-3, 3-1, and 3-2. Curves 2-6, 3-3, and 3-4 are the magenta OD curves for the green-sensitive image sheet of Examples 2-3, 3-1, and 3-2, respectively. Cyan OD curves for Examples 2-6, 3-3, and 3-4 with a 0.566 phi filter Violet 19 at 1035 and in the housing. DETAILED DESCRIPTION

[0066] In the following description, numerous specific details are set forth to provide a thorough understanding of the present technology. Certain illustrative embodiments of the present technology may be practiced without some or all of these specific details. In other cases, certain process operations are not described in detail, but will be understood by those skilled in the art.

[0067] Disclosed herein is an improved full-color microcapsule imaging system in which the photosensitive microcapsules contain a color-filtering shell or a shell capable of filtering out undesirable wavelengths of primary light.

[0068] In some embodiments, the microcapsule imaging systems described herein may include any or all of the following microcapsule combinations:

[0069] 1. A red (λ1) sensitive microcapsule comprising a cyan leuco dye in a photohardenable core material and a color filtering shell to filter non-red (non-λ1) light, such as UV light, blue light and / or green light.

[0070] 2. A green (λ2) sensitive microcapsule comprising a magenta leuco dye in a photohardenable core material and a color filtering shell to filter non-green (non-λ2) light, such as UV light, blue light and / or red light.

[0071] 3. A blue (λ3) sensitive microcapsule comprising a yellow leuco dye in a photohardenable core material and a color filtering shell to filter non-blue (non-λ3) light, such as UV light, green light and / or red light.

[0072] The red (R), green (G) and blue (B) light / colors and cyan (C), magenta (M) and yellow (Y) colors mentioned above are given as an example because they are commonly used in complementary color imaging systems. In a false color imaging system, various light sources (λ1, λ2 and λ3) including UV and near IR light can be used as long as they are well separated from each other to ensure good color separation.

[0073] Microcapsules containing the color filter shells described herein greatly reduce unwanted crosstalk between microcapsules of various colors and significantly improve the color fidelity of images reproduced thereby. This is particularly advantageous for digital imaging systems because the microcapsules described herein greatly reduce the need to select a light source whose emission wavelength perfectly matches the spectral sensitivity of the photosensitizer / initiator used in the microcapsules. Fine-tuning the emission spectrum of a light source such as an LED or OLED or the absorption spectrum of a photosensitizer / initiator while maintaining its quantum efficiency is challenging. The microcapsules described herein provide an effective and low-cost solution to reduce unwanted crosstalk and improve the color image fidelity of an imaging system.

[0074] The image quality of a photosensitive imaging system depends largely on the spectral sensitivities of the three microcapsules and the emission spectrum of the light source used. As mentioned above, the absorption spectra of commonly used red (R), green (G), and blue (B)-sensitive photoinitiators (such as cyanine borate photoinitiators) overlap significantly. The emission spectra of broadband light sources (for example, the R-, G-, and B-OLEDs used in OLED displays, and the R-, G-, and B-light transmitted through color filters in LCD displays) also overlap. For such photoinitiators, the absorption spectra of B- and G-photoinitiators overlap significantly in the 440-500 nm range. Similarly, the absorption spectra of G- and R-photoinitiators overlap significantly in the 540-600 nm range. Therefore, exposing the imaging sheeting with light of wavelengths within this overlapping range can cause crosstalk by hardening more than one type of capsule.

[0075] To further illustrate the impact of crosstalk on image quality, particularly the fidelity of color reproduction, a microcapsule imaging sheet containing three types of microcapsules, each containing one of three photoinitiators (R-, G-, and B-sensitive) and three complementary cyan (C), magenta (M), and yellow (Y) leuco dyes, was exposed or written using one of three light sources (e.g., R-, G-, or B-OLEDs or LEDs). Ideally, after being written with red (λ1) light, only the R-sensitive microcapsules would harden, and the release of the C-leuco dye encapsulated therein would decrease as the red energy received by the red-sensitive microcapsules. The G- and B-sensitive microcapsules should remain intact and not undergo any photoreactions upon exposure to R light. If the M- and Y-leuco dyes are carefully selected and the ratio of the two dyes is well balanced, the corresponding M- and Y-leuco dyes encapsulated in the G- and B-sensitive microcapsules, respectively, can be freely released into the dye developer layer, thereby reproducing the red image of the source image. Similarly, exposing the imaged sheet to green (λ2) light reproduces only the green portion of the source image, and exposing the imaged sheet to blue λ3 light reproduces only the blue portion of the source image.

[0076] The fidelity of the color reproduction process can be degraded if any crosstalk of the photoreactions occurs, for example, if more than one type of microcapsule is hardened when the system is written by only one light source. The color of the printed image is then contaminated with unwanted colors and the color gamut is significantly degraded.

[0077] As mentioned above, one approach to improving the fidelity of color reproduction processes is to use photosensitizers / initiators with narrow and well-separated spectral sensitivities, and light sources with narrow bandwidths and well-separated emission spectra that are appropriately matched to the spectral sensitivities of the corresponding photosensitizers / initiators. This technique facilitates high-quality color reproduction. However, most photosensitizers / initiators exhibit very broad spectral sensitivities, and the most readily available modulatable light sources exhibit very broad or mismatched emission spectra. There are few commercially available narrowband LEDs or lasers with reasonably acceptable λmax, size, and power efficiency, and the cost is often very high for printing applications, especially portable printing applications. Furthermore, with the exception of cyanine borate photoinitiators, it is extremely difficult, if not impossible, to find a set of R-, G-, and B-photoinitiators with reasonably narrowband absorption spectra. Finally, such systems require high quantum efficiency of the photosensitizer / initiator and high power output of the light source, which tends to make any high-speed printing application difficult and costly to implement.

[0078] Photosensitive microcapsules

[0079] As described herein, the photosensitive microcapsules comprise a color filtering shell; and a core material comprising a leuco dye or dye precursor, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material.

[0080] Specifically, in one or more embodiments, the photosensitive microcapsules are sensitive to a specific color or a specific range of radiation spectrum, and the shell contains one or more color filter dyes or pigments that allow wavelengths corresponding to the color or radiation spectrum range to pass through to the core material, but selectively absorb or filter out all or part of the radiation outside the specific color or range. In some embodiments, the specific color or range is red, green, blue, cyan, magenta, or yellow. In some embodiments, the radiation spectrum ranges from about 330 nm to about 900 nm, including about 330 nm, about 350 nm, about 375 nm, about 400 nm, about 425 nm, about 450 nm, about 475 nm, about 500 nm, about 525 nm, about 550 nm, about 575 nm, about 600 nm, about 625 nm, about 650 nm, about 675 nm, about 700 nm, about 725 nm, about 750 nm, about 775 nm, about 800 nm, about 825 nm, about 850 nm, about 875 nm, and 900 nm.

[0081] Color filter shell can be prepared by adding one or more color filter dyes or pigments during the shell formation step of microencapsulation process.For example, can be in the pre-wall formation process, by adsorption or interfacial polymerization / crosslinking and / or cohesion process, water-soluble or dispersible color filter dye or pigment is introduced into the aqueous phase, so that dye / pigment is grafted or embedded on or in the pre-wall.Perhaps, can be during the second wall formation, by in-situ polymerization and / or phase separation process, introduce dye or pigment.The color filter dye or pigment with reactive functional group such as-NH-,-NH ,-OH ,-SH ,-COOH ,-CONH-,-CONH ,-CSNH-,-CSNH , reacting or grafting with shell material is particularly useful.Unreacted or unembedded color filter dye or pigment in the aqueous phase are removed by for example repeatedly centrifuging and washing gained microcapsules.

[0082] Figure 1A and 1B Spectra of two representative water-based color filter pigment dispersions used in the present invention are shown. Figure 1A As shown, the yellow filter pigment absorbs initial light <500 nm very efficiently, and the absorbance drops rapidly to zero at approximately 550 nm. Incorporating such a yellow pigment into the shell of green-sensitive microcapsules can effectively reduce the risk of unwanted photohardening reactions caused by broadband blue light sources. Depending on the concentration of yellow pigment present in the shell, the photosensitivity to green light exposure may be essentially unchanged or slightly reduced, as evident from the absorption spectrum of the green photoinitiator used. Figure 1B As shown, incorporation of magenta / violet pigments into the shell of red-sensitive microcapsules effectively reduces the risk of unwanted photohardening reactions caused by broadband green and / or blue light sources.

[0083] The color filter housing described herein filters out some or all of the unwanted wavelengths of light, but allows light of the correct wavelength to pass through and trigger the photoreaction in the core material. For example, a green-sensitive microcapsule comprising a magenta leuco dye, a green-sensitive photoinitiator, and a shell comprising a yellow dye or pigment as the color filter material shields the unwanted blue light (the complementary light of yellow) in the shell, and allows green light to pass through and harden the core material. Similarly, by replacing the yellow dye or pigment in the shell with a cyan dye or pigment, the unwanted red light (the complementary light of cyan) is shielded. Furthermore, if both yellow and cyan dyes / pigments are used in the shell of the green-sensitive microcapsule, both the unwanted blue light and the unwanted red light will be shielded.

[0084] Thus, the filter dyes / pigments in the shell protect the core material from being hardened by the wrong light source, even though the photosensitizer / initiator in the core material may be somewhat sensitive to the wrong light. As shown in the examples, this results in a significant reduction in undesirable crosstalk and greatly improves the color fidelity of the color printing process. In addition, the colors of the filter dyes or pigments are barely visible after the imaged sheet is developed, for example, by pressure and / or heat, because they are fixed by the mesh structure of the shell and their colors are effectively hidden beneath the printed image in the developer layer (see Figure 2A and 2B ).

[0085] Figure 2A and 2B Schematic diagram of an imaging sheet containing green-sensitive microcapsules containing a color filter shell. Figure 2A represents the sheet before development, and Figure 2B Shows the film after exposure and development. Figures 2A-2B, depicted are a transparent substrate 1, a developer layer 2, a microcapsule layer 3 having photosensitive microcapsules 3a, an opaque substrate 4, a photosensitive microcapsule shell 5 (depicted using triangular components) comprising a color-filtering yellow and / or cyan dye or pigment, a core material 6 comprising a green-sensitive photoinitiator G, an acrylic monomer A, and a magenta leuco dye M, ruptured microcapsules 7, hardened capsules 8 having the magenta leuco dye immobilized therein, a developer layer 9 having the magenta leuco dye M and the acrylic monomer A transferred or diffused from the ruptured microcapsules 7, and an observer 10. In some embodiments, the microencapsulated imaging sheeting according to the present disclosure includes a photosensitive microcapsule layer 3 comprising photosensitive microcapsules 3a on a substrate 4. The photosensitive microcapsules 3a comprise a shell 5 containing a color filter dye or pigment Δ (e.g., yellow and / or cyan dye / pigment dye) and a hardenable core 6 containing (i) a dye (e.g., a leuco dye, such as a magenta leuco dye) that imparts color to the microencapsulated imaging sheet when released and developed under pressure and / or heat; (ii) a photoinitiator, such as a green-sensitive cyanine borate; and (iii) a multifunctional monomer, such as trimethylolpropane triacrylate (TMPTA). The developer can be present, for example, in a developer layer 9 that is configured to be placed separately in contact with the microcapsule layer 3. Alternatively, the developer can be pre-mixed with the microcapsules and applied as a single layer to the substrate 4. In some embodiments, the microcapsule layer can be placed in contact with the developer layer and developed with it after the image-by-image exposure step. After the image is transferred and developed to the developer layer (two-sheet imaging system), the developed microcapsule layer can be discarded.

[0086] During the image-by-image exposure, the microcapsules are selectively hardened or softened. The dye encapsulated in the microcapsules (e.g., leuco dye) is selectively released from the ruptured microcapsules 7 during the pressure / heat development step and undergoes a chemical transformation from a colorless state to a colored state (e.g., magenta, cyan, or yellow).

[0087] In some embodiments, one or more filter dyes or pigments comprise functional groups that react with one or more shell-forming materials. In some embodiments, the functional groups are selected from the group comprising: -OH, -SH, -NH2, -N-HR, -CH2OH, -CH2OR, -CHO, -CONH2, -CONHR, urea, thiourea, isocyanate, thioisocyanate, epoxide, and precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl, or heteroatom derivatives thereof, particularly those with shorter chain lengths. In some embodiments, the functional groups are selected from the group comprising: -OH, -SH, -NH2, -N-HR, -CONH2, -NCO, -NCS-, -CH2OH, -CH2OR, -CHO, and precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl, or heteroatom derivatives thereof, particularly those with shorter chain lengths. In some embodiments, the color filter dye or pigment comprising a functional group is water-soluble or water-dispersible and is included in the aqueous phase (external phase) and is incorporated into or onto the microcapsule shell by adsorption or interfacial reaction.

[0088] In some embodiments, one or more shell-forming materials are included in the internal phase or the oil phase and form an outer shell by interfacial polymerization or crosslinking during microencapsulation. In some embodiments, one or more shell-forming materials are included in the internal phase and / or the external phase and form an outer shell by interfacial polymerization or crosslinking during microencapsulation. In some embodiments, the one or more shell-forming materials included in the oil phase or the internal phase are selected from the group consisting of polyfunctional isocyanates, thioisocyanates, and epoxides or their precursors.

[0089] In some embodiments, one or more shell-forming materials are included in the external phase or aqueous phase and form the shell during the microencapsulation process by interfacial or in situ polymerization or crosslinking, phase separation or coagulation. In some embodiments, the one or more shell-forming materials in the external phase or aqueous phase are water-soluble compounds containing reactive functional groups, including but not limited to -OH, -SH, -NH2, -N-HR, -COOH, -CH2OR, -CHO or precursors thereof, wherein R is alkyl, aryl, arylalkyl, alkylaryl or heteroatom derivatives thereof, particularly those with shorter chain lengths. In some embodiments, the one or more shell-forming materials are selected from the group consisting of urea, amines, urea formaldehyde, melamine formaldehyde, poly(N-hydroxymethyl acrylamide), gelatin, gum arabic, pectin, carboxymethyl cellulose and oligomers, copolymers or blends thereof.

[0090] In some embodiments, the photoinitiator or photosensitizer is red-sensitive and the color of the color filter housing is magenta, yellow, or a combination thereof. In some embodiments, the photoinitiator or photosensitizer is green-sensitive and the color of the color filter housing is cyan, yellow, or any combination thereof. In some embodiments, the photoinitiator or photosensitizer is blue-sensitive and the color of the color filter housing is magenta, cyan, or any combination thereof. In some embodiments, the photoinitiator or photosensitizer is IR-sensitive and the color of the color filter housing is cyan, magenta, yellow, or any combination thereof.

[0091] In some embodiments, the color filter housing comprises one or more color filter dyes or pigments. In some embodiments, the color filter dye is thermally bleachable or photobleachable. For blue-sensitive microcapsules, the color filter dye or pigment can be a magenta (green-absorbing) and / or cyan (red-absorbing) dye or pigment. For green-sensitive microcapsules, the color filter dye or pigment is a yellow (blue-absorbing) and / or cyan (red-absorbing) dye or pigment. In some embodiments, the color filter dye or pigment is yellow pigment 155 or CI Direct Yellow 86. For red-sensitive microcapsules, the color filter dye or pigment is a yellow (blue-absorbing) and / or magenta (green-absorbing) dye or pigment for red-sensitive microcapsules. In some embodiments, the color filter dye or pigment is Pigment Violet 19 or CI Disperse Red 60.

[0092] Illustrative examples of suitable filter dyes or pigments include, but are not limited to, cyanine or hemicyanine dyes, quinacridone dyes, and perylene dyes. Cyan, magenta, and yellow dyes or pigments used in inkjet printing are particularly suitable. They are readily available from suppliers such as Cabot, Kolorjet Chemicals, Sun Chemicals, and Kao Collins, Inc. Reviews of inkjet printing dyes / pigments include P. Gregory, “High-Technology Applications of Organic Colorants”, Plenum Press, New York, 1991; P. Gregory, “Colorants For Electronic Printers,” in J. A. G. Drake, ed., “Chemical Technology In Printing And Imaging Systems,” Royal Soc. Chem. (1993); W. Bauer, J. Ritter, “Tailoring Dyes for Ink Jet Applications,” American Ink Maker 73, 42-49 (1995); R. W. Kenyon, “Dyes for Ink Jet Printing, Innovations in Modern Color Chemistry,” SCI, London, 1994; W. Bauer, B. Baumgart and W. Zoller, “Magenta Dyes for Inkjet Applications,” in “Recent Progress in Ink Jet Technologies,” ed. II" Chapter 6, IS&T, 1999; R. Senthilkumar, "Dyes for Ink Jet Printing of Textiles" (2016), and DM Marmion, "Handbook of US Colorants For Foods, Drugs And Cosmetics" John Wiley & Sons (1984).

[0093] In some embodiments, the amount of one or more color filter dyes or pigments present in the microcapsules is from about 0.01 to about 3 phi (parts by weight per hundred parts of internal phase or per hundred parts of core material), including about 0.01, about 0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, about 0.10, about 0.20, about 0.30, about 0.40, about 0.50, about 0.60, about 0.70, about 0.80, about 0.90, about 1.0, about 1.5, about 2.0, about 2.5, and about 3.0 parts per hundred parts of core material. In some embodiments, the amount of one or more color filter dyes or pigments present in the microcapsules is from about 0.05 to about 1.0 phi.

[0094] In some embodiments, when the photosensitive microcapsules are green-sensitive or red-sensitive microcapsules and the one or more filter dyes or pigments include yellow (blue-absorbing) filter dyes or pigments, the total absorption optical density of the one or more yellow (blue-absorbing) filter dyes / pigments is from about 0.005 to about 0.3 in the range of about 450 nm to about 500 nm. In some embodiments, the total optical density of the one or more yellow (blue-absorbing) filter dyes / pigments is from about 0.05 to about 0.2 in the range of about 450 nm to about 500 nm.

[0095] In some embodiments, when the photosensitive microcapsules are green-sensitive and the one or more filter dyes or pigments comprise cyan (red-absorbing) filter dyes or pigments, the one or more cyan (red-absorbing) filter dyes / pigments have a total absorption optical density within the range of about 600 nm to about 650 nm of about 0.005 to about 0.3. In some embodiments, the one or more cyan (red-absorbing) filter dyes / pigments have a total optical density within the range of about 600 nm to about 650 nm of about 0.05 to about 0.2.

[0096] In some embodiments, when the photosensitive microcapsules are blue-sensitive or red-sensitive microcapsules and the one or more filter dyes or pigments comprise a magenta (green-absorbing) filter dye or pigment, the one or more magenta (green-absorbing) filter dyes or pigments have a total absorption optical density of about 0.005 to about 0.3 in the range of about 500 nm to about 600 nm. In some embodiments, the one or more magenta (green-absorbing) filter dyes or pigments have a total optical density of about 0.05 to about 0.2 in the range of about 500 nm to about 600 nm.

[0097] It is worth noting that the above-mentioned red (R), green (G) and blue (B) light / colors and cyan (C), magenta (M) and yellow (Y) colors are given as non-limiting examples because they are commonly used in complementary color imaging systems. In false color imaging systems, various light sources (λ1, λ2 and λ3) can be used, including UV and near IR, as long as they are well separated from each other to ensure good color separation.

[0098] In some embodiments, the photosensitive microcapsules have an average diameter or D of about 4.0 μm to about 9.0 μm. 50 , including about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5 and about 9.0 μm. In some embodiments, the photosensitive microcapsules have an average diameter or D of about 5.0 μm to about 6.5 μm. 50 .

[0099] In addition, the inventors of the present disclosure have found that the incorporation of color filter dyes / pigments into the core material of the microcapsules can lead to color contamination. Without wishing to be bound by theory, it is believed that after pressure / heat development of the developer layer, the soluble or dispersed dyes / pigments in the core material are released simultaneously with the leuco dye and the monomer, and unless the color filter dye / pigment can be effectively bleached after development, the observer will see its color. In fact, the presence of color filter dyes or pigments in the core material may also undesirably widen the spectral sensitivity of the microcapsules and cause crosstalk in the microcapsule imaging system, particularly if the color filter dyes or pigments themselves also exhibit a certain degree of photosensitivity in an unwanted wavelength range via, for example, energy or electron transfer mechanisms. In some embodiments, the core material does not contain (i.e., lacks) any color filter dyes or pigments.

[0100] As described herein, the photosensitive microcapsules comprise a color filtering shell; and a core material comprising a leuco dye, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material.

[0101] Each photosensitive microcapsule encapsulated by one or more color filter shells comprises a core material comprising a leuco dye, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material. In some embodiments, the leuco dye is a cyan, magenta, yellow, black leuco dye, or any combination thereof. As a non-limiting example, a representative magenta leuco dye may include Red 16B (CAS: 50292-95-0, Synamedia-chem); COPIKEM 35 (CAS: 50292-91-6), Blue 1-2G and Blue-63 from BASF, Blue 220, Blue 203, Red 500, Red 40 or Black 305 from Yamada, JYDY-1, JYDR-2, JYDR-3, JYDB-1 or JYDB-2 from WuXi Jiayida New Materials, Red-16, O-C6 or O-C8 from Synmedia Chemicals, or ODB-2 from Anyang General Chemicals. Other suitable examples of leuco dyes are disclosed in, for example, Chemistry and Applications of Leuco Dyes (R. Muthyala, ed., 1997).

[0102] Suitable photoinitiators or photosensitizers include borate complexes, which can be represented by the following general formula:

[0103]

[0104] Among them D + is a cationic chromophore such as a cyanine, hemicyanine, squarylium (e.g., squarylium), thiopyrylium, or triarylmethane. 1 、R 2 、R 3 and R 4 Each is independently substituted or unsubstituted alkyl, arylalkyl or aryl. In some embodiments, R 1 is an alkyl group or an arylalkyl group, and R 2 、R 3 and R 4 In some embodiments, the one or more photoinitiators include one or more of the following: ketocoumarins, benzylidene ketones, benzophenones, thioxanthones, acryloylphosphine oxides, metallocene derivatives, and other Norrish type I, II, and III photoinitiators, and combinations thereof.

[0105] The photoinitiator can be a red-sensitive, green-sensitive, or blue-sensitive cyanine borate, hemicyanine borate, or ketocoumarin. In some embodiments, the photoinitiator is a cyanine borate, hemicyanine borate, triarylmethane, squarylium, or thiopyrylium dye. In some embodiments, the photoinitiator or photosensitizer comprises a UV-sensitive, blue-sensitive, green-sensitive, red-sensitive, or near-IR-sensitive photoinitiator or sensitizer.

[0106] The photohardenable material may include a photopolymerizable or crosslinkable monomer or oligomer. In some embodiments, the polymerizable or crosslinkable monomer or oligomer is selected from multifunctional acrylates or methacrylates, multifunctional vinyl ethers, multifunctional allyl or vinylbenzenes, and oligomers, dendrimers, or blends thereof. The multifunctional acrylate may be pentaerythritol triacrylate (PETA-3), pentaerythritol tetraacrylate (PETA-4), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), or neopentyl glycol diacrylate (NPGDA). The photosoftenable material may include a photodegradable or photodepolymerizable polymer.

[0107] In some embodiments, the core material further comprises a free radical inhibitor, a retardant, or an antioxidant. In some cases, the retardant or free radical inhibitor is used to slow down the photosensitivity of a specific type of R-, G-, or B-photosensitive microcapsules to further reduce the degree of crosstalk between the microcapsules and the color filter housing.

[0108] The free radical inhibitor, antioxidant or retardant may be selected from the group comprising phenols, anilines, N-oxides of hindered amines, CuO, copper dithiocarbamates, copper or manganese carboxylates and thiuram (thiocarbamoyl) derivatives or combinations thereof, such as

[0109]

[0110] where R 1 、R 2 、R 3 and R 4 and are independently an alkyl group having 1 to 8 carbon atoms or a phenyl group.

[0111] The free radical inhibitor may be a phenol free radical inhibitor selected from the list comprising alkyl gallates, butylated hydroxyanisole, 3,5-di-tert-butylbutyl-4-hydroxytoluene, vitamin E, 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-ol ( E201), triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ( 245), 3-{[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]oxy}-2,2-bis({[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]-oxy}methyl)-propyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate ( 1010), 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine ( MD 1024, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene ( 1076), 2,2'-thiobis(6-tert-butyl-p-cresol) 1081), N,N'-hexane-1,6-diylbis(3-3,5-di-tert-butyl-4-hydroxyphenyl-propionamide)( 1098), 3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropionic acid thiodi-2,1-ethanediyl ester ( 1035), phenylpropionic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-C7-C9 branched chain alkyl ester ( 1135), 3,3',3',5,5',5'-hexa-tert-butyl-a,a',a'-(mesitylene-2,4,6-triyl)tri-p-cresol ( 1330), (1,1-di-tert-butyl)-4-hydroxyphenyl)methyl)ethylphosphonate) 1425), 1,3,5-tris[4-hydroxy-3,5-bis(2-methyl-2-propyl)benzyl]-1,3,5-triazinane-2,4,6-trione ( 3114), 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol ( 565) and others Primary antioxidant.

[0112] The free radical inhibitor can be an N-oxide of a hindered amine, wherein the hindered amine is selected from the list comprising bis(2,2,6,6,-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770DF), bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (ADK STAB LA-72), tetrakis(2,2,6,6-tetramethyl-4-piperidinyl)butane-1,2,3,4-tetracarboxylate (ADKSTAB LA-57), and bis(1-undecanyloxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate (ADK STAB LA-81).

[0113] The free radical inhibitor, retardant, or antioxidant may be present in a concentration of about 0.01 to about 1 part by weight per hundred parts of the core material, including about 0.01, about 0.05, about 0.10, about 0.2, about 0.3, about 0.4, about 0.54, about 0.6, about 0.7, about 0.8, about 0.9, and about 1.0 parts by weight per hundred parts of monomer in the internal phase. In some embodiments, the free radical inhibitor, retardant, or antioxidant is present in the internal phase at a concentration of about 0.3 to 0.5 parts by weight per hundred parts of monomer.

[0114] In some embodiments, the free radical inhibitor, retarder, or antioxidant is present in the internal phase at a concentration of about 0.1 to about 1.0 parts by weight per hundred parts of monomer. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present in the internal phase at a concentration of about 0.05 to 0.8 parts by weight per hundred parts of monomer. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present at a concentration of about 0.3 to about 0.8 phi. In some embodiments, the free radical inhibitor, retarder, or antioxidant is present at a concentration of about 0.1 to 0.6 phi.

[0115] The core material may further comprise one or more of a coinitiator, an oxygen scavenger, or an auto-oxidant, either alone or in any combination. For example, a coinitiator, an oxygen scavenger, or an auto-oxidant may be used to accelerate the photosensitive speed of a particular type of R-, G-, or B-photosensitive microcapsule to further reduce the degree of crosstalk between the microcapsules and the color filter housing.

[0116] Microcapsule imaging sheet

[0117] The present invention also describes a microcapsule imaging sheet comprising: a first substrate; and a photosensitive microcapsule layer comprising photosensitive microcapsules in contact with a first surface of the first substrate, wherein the photosensitive microcapsules comprise: a color filter shell and a core material, the core material comprising a leuco dye, a photoinitiator or a photosensitizer, a photohardenable or photosoftenable material.

[0118] The photosensitive microcapsule layer can contain one or more types of microcapsules. For example, the microcapsules may be sensitive to red visible light, green visible light, or blue visible light. The photosensitive microcapsule layer can contain red-sensitive, green-sensitive, or blue-sensitive microcapsules, in which case the microencapsulated imaging sheeting is considered a "full color" imaging sheeting.

[0119] In some embodiments, the photosensitive microcapsule layer or sheet further comprises a developer. In some embodiments, the photosensitive microcapsule layer or sheet further comprises a separate developer layer. In some embodiments, the separate developer layer is coated or laminated onto the photosensitive microcapsule layer.

[0120] In some embodiments, any of the microcapsule imaging sheets described herein further comprises an adhesive layer positioned between the developer layer and the microcapsule layer.

[0121] In some embodiments, any of the microcapsule imaging sheets described herein further comprises a primer layer positioned between the microcapsule layer and the first substrate.

[0122] The microcapsule imaged sheeting described herein has an increased or improved color gamut and / or fidelity of color reproduction of the original image.

[0123] substrate

[0124] The microcapsules described herein can be coated onto a substrate (e.g., a first or second substrate). The substrate can be any suitable material having sufficient thickness, flexibility, reflectivity (e.g., hiding power), and durability to record the printed medium (e.g., image). In some embodiments, the substrate is white or transparent. The substrate can be polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polyolefin, cyclic olefin copolymer (COC), cellulose acetate, or a copolymer, blend, or composite thereof. For example, commercially available PET substrates are manufactured by Dupont Teijin Films. 339 ("PET339"). Other useful commercially available PET films include, but are not limited to Polyester film (MitsubishiPolyester Film), (DuPont Teijin Films TM )and Polyester film (DuPont Teijin Films TM ). The substrate may be in contact with the microcapsule layer, the developer layer, or both.

[0125] The substrate can have any suitable thickness. In some embodiments, the substrate has a thickness of about 10 μm, about 20 μm, about 30 μm, about 40 μm, about 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, about 100 μm, about 150 μm, about 200 μm, about 250 μm, about 300 μm, about 350 μm, about 400 μm, about 450 μm, about 500 μm, or any range or value therebetween.

[0126] Developer layer

[0127] In some embodiments, imaging sheets according to the present disclosure include a developer layer in contact with a microcapsule layer and / or a developer substrate. The developer layer can be contacted with the microcapsule layer after application to the second substrate, for example, by lamination. In some embodiments, the developer layer can be coated onto the microcapsule layer, and the resulting coated sheet can be used without the second substrate. In some embodiments, the coated developer / microcapsule sheet can be further coated with a durable protective coating or laminated with the second substrate. In some embodiments, the composition of the developer layer can be premixed with the composition of the microcapsule layer and applied as a single layer to the first substrate.

[0128] In some embodiments, imaging systems according to the present disclosure comprise two separate sheets: a photosensitive microcapsule sheet and a developer sheet. The microcapsule sheet is image-wise exposed, contacted with the developer sheet, and subsequently developed using pressure / heat. After the leuco dye is transferred to the developer sheet, the microcapsule sheet is discarded.

[0129] In some embodiments, the developer substrate is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polyolefin, cyclic olefin copolymer (COC), cellulose acetate, or copolymers, blends, or composites thereof.

[0130] In some embodiments, the developer layer comprises one or more leuco dye developers. As non-limiting examples, the developer can include Lewis acids, silicic acid, salicylic acid derivatives, benzoic acid derivatives, novolac resins and metal complexes thereof, particularly zinc complexes, or blends, composites, copolymers, including graft and block copolymers, or combinations thereof. For example, the developer can include: acidic clay, 3,5-bis(α-methylbenzyl) zinc salicylate (e.g., N-054-W, SANKO Co., Ltd.), 3,5-di-tert-butyl zinc salicylate, 3,5-dioctyl zinc salicylate, HRJ 4542 (Schenectady Chemical), or phenolic resin developers such as RD9870, RD9870A, RD9880, RD9880U, RF-118, etc. (Xinxiang Richful Lube Additive Co., Ltd.). In some embodiments, the developer layer comprises a Lewis acid, an acidic clay, or one or more compounds comprising a phenolic group or a carboxylic acid group, or a metal complex thereof. In some embodiments, the developer layer comprises a novolac resin, a salicylic acid derivative, a zincate derivative thereof, or a combination, copolymer, blend, or composite thereof.

[0131] The developer layer can have any suitable thickness. For example, the developer layer can have a thickness of at least about 1 μm, at least about 2 μm, at least about 3 μm, at least about 4 μm, at least about 5 μm, at least about 6 μm, at least about 7 μm, at least about 8 μm, at least about 9 μm, at least about 10 μm, at least about 15 μm, at least about 20 μm, at least about 25 μm, at least about 30 μm, at least about 35 μm, at least about 40 μm, at least about 45 μm, at least about 50 μm, or any range or value therein. In some embodiments, the developer layer has a thickness of about 1 μm to about 30 μm, about 2 μm to about 20 μm, or about 3 μm to about 15 μm.

[0132] The developer may be present in the developer layer at a concentration by weight relative to the dry weight of the developer layer of about 50% or greater, about 55% or greater, about 60% or greater, about 65% or greater, about 70% or greater, about 75% or greater, about 80% or greater, about 85% or greater, about 90% or greater, about 95% or greater, about 96% or greater, about 97% or greater, about 98% or greater, about 99% or greater, or any range or value therebetween. In some embodiments, the developer layer may include a polymeric binder and fillers such as silica, acidic clay, CaSO4, BaSO4, and TiO2.

[0133] method

[0134] In another aspect, provided is a method of making an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a microcapsule layer to produce a microcapsule-coated first substrate; and (ii) contacting the microcapsule-coated first substrate with a developer layer to produce the imaging sheeting.

[0135] In another aspect, provided is a method of making an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a developer layer to produce a developer-coated first substrate; and (ii) contacting the developer-coated first substrate with a microcapsule layer to produce the imaging sheeting.

[0136] In another aspect, a method of preparing an imaging sheeting according to any of the imaging sheetings described herein is provided, the method comprising coating a first surface of a first substrate with a mixture of a developer and photosensitive microcapsules to produce the imaging sheeting. In some embodiments, the method further comprises contacting the first substrate coated with the microcapsule / developer mixture with a second substrate. In some embodiments, the method further comprises contacting the first substrate coated with the microcapsule / developer mixture with a protective coating.

[0137] In another aspect, provided is a method of preparing an imaging sheeting according to any of the imaging sheetings described herein, the method comprising: (i) coating a first surface of a first substrate with a microcapsule layer to produce a microcapsule-coated first substrate; (ii) coating a second substrate with a developer layer to produce a developer-coated second substrate; and (iii) contacting the developer layer of the developer-coated second substrate with the microcapsule layer of the microcapsule-coated first substrate to produce the imaging sheeting.

[0138] In another aspect, a method of imaging or printing is provided, comprising: exposing an imaged sheeting according to any of the imaged sheetings described herein to heat or radiation imagewise, wherein the exposure is sufficient to selectively immobilize or mobilize a leuco dye in the microcapsules by hardening or softening the microcapsules, thereby producing a latent image; and developing the latent image by pressure and / or heat, thereby forming an image. In some embodiments, the exposing radiation is UV, visible, near-IR, or IR light. In some embodiments, the exposing radiation is UV, visible, near-IR, or IR light. In some embodiments, the exposing or developing heat is from a thermal print head.

[0139] In some embodiments, a process for making photosensitive microcapsules is provided. Examples provide illustrative embodiments of preparing photosensitive microcapsules. The method comprises providing an aqueous phase, contacting the aqueous phase with an internal phase comprising a leuco dye or dye precursor, a photoinitiator or photosensitizer, and a photohardenable or photosoftenable material to produce a mixture, contacting the mixture with a dispersion comprising a color filter dye or pigment, and forming the photosensitive microcapsules during microencapsulation by interfacial or in situ polymerization or crosslinking, phase separation, or coacervation.

[0140] While the foregoing terms are believed to be well known to those of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0141] The terms "a" or "an" may refer to one or more of the entity, i.e., may refer to plural references. Thus, the terms "a" or "an," "one or more," and "at least one" are used interchangeably herein. Furthermore, reference to an "element" using the indefinite article "a" or "an" does not exclude the possibility that more than one element is present, unless the context clearly requires the presence of one and only one element.

[0142] Reference throughout this specification to "one embodiment," "an embodiment," "one aspect," or "aspect" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0143] As used herein, the term "about" or "approximately" preceding a numerical value means a range of plus or minus 10% of the value.

[0144] As will be understood by those skilled in the art, for any and all purposes, particularly in providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be readily identified as fully describing and capable of resolving the same range into at least equal halves, thirds, quarters, fifths, tenths, etc. As non-limiting examples, each range discussed herein can be readily resolved into a lower third, a middle third, an upper third, etc. As will be understood by those skilled in the art, all language, such as "at most," "at least," "greater than," "less than," etc., includes the enumerated numbers and refers to ranges that can subsequently be resolved into subranges as described above. Finally, as will be understood by those skilled in the art, a range includes each individual member.

[0145] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention belongs. It should be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of this application and the related art, and should not be idealized or overly formally interpreted unless explicitly defined herein. Although not explicitly defined below, such terms should be interpreted according to their common meaning.

[0146] For the purposes of this disclosure, the term "color density" refers to the ability of a dye to absorb light, wherein the greater the light absorption of the dye, the higher the color density (i.e., the more intense the color). The lower the light absorption of the dye, the lower the color density (i.e., the less intense the color).

[0147] For the purposes of this disclosure, the term "maximum color density" (or "D max ”) refers to the maximum color density reached by a dye after a given development time (e.g., after about 1 hour, about 2 hours, about 4 hours, about 8 hours, about 12 hours, about 24 hours, etc.).

[0148] For the purposes of this disclosure, the term "fresh color density" or "fresh D max ” refers to the color density that the dye reaches immediately (e.g., within one second or a few seconds to a few minutes, such as between about 1 second, about 2 seconds, about 5 seconds, or about 10 seconds to about 1 minute, about 2 minutes, about 3 minutes, about 4 minutes, or about 5 minutes) when the microcapsule ruptures (e.g., when color development begins).

[0149] For the purposes of this disclosure, the term "leuco dye" refers to a chemical dye that can alternate between two chemical forms, one of which is colorless. The transition from the colorless to the colored form can be reversible or irreversible and can be caused by changes in temperature, pH, radiation, and / or redox state.

[0150] Unless expressly stated otherwise, all specified embodiments, features, and terms are intended to include the referenced embodiments, features, or terms and their equivalents.

[0151] Reference will now be made in detail to the specific embodiments contemplated by the present disclosure. Although various embodiments are described herein, it should be understood that the present disclosure is not intended to limit the technology to the described embodiments. On the contrary, the present disclosure is intended to cover alternatives, modifications, and equivalents that may be included within the spirit and scope of the technology defined by the appended claims.

[0152] Examples

[0153] Example 1. Preparation of comparative red-sensitive, green-sensitive and blue-sensitive microcapsules and self-contained imaging sheets based on the microcapsules. Table 1 below lists the materials used in the following examples.

[0154] Table 1. Materials used in Example 1

[0155]

[0156] Preparation of photosensitive microcapsules

[0157] Prepare photosensitive microcapsules using the materials in Table 2 according to the following procedure:

[0158] 1. Add 220 parts water and 8 parts Versa TL502 sulfonated polystyrene (dry) to a beaker and mix thoroughly.

[0159] 2. Slowly sift 10 parts of pectin (methyl polygalacturonate) into the mixture and stir at room temperature (500-1000 rpm) overnight.

[0160] 3. Adjust pH to 7.5 with 10% sodium carbonate and increase stirring speed to 1750 rpm.

[0161] 4. Add the internal phase shown in Table 2 over a period of 15-30 seconds. The resulting mixture is stirred for 30 minutes, and 11 parts of a 9.1% diethylenetriamine (DETA) aqueous solution (pH adjusted to 7.0) are added and reacted at 25° C. for 30 minutes and then at 40° C. for one hour.

[0162] 5. Add 19.9 parts 385 parts of acetaldehyde and 40 parts of water (pH adjusted to 6.0), and the mixture was reacted at 70°C for a further 2 hours.

[0163] 6. Add 15.23 parts of 34.3% sodium sulfate aqueous solution and stir the mixture for 10 minutes. 385 and 10 parts of water, and the mixture was reacted at 70°C for another hour.

[0164] 7. The mixing speed was reduced to 600 rpm, the pH was adjusted to 9.5 using 20% ​​NaOH solution, and the resulting reaction mixture was stirred at room temperature overnight.

[0165] Table 2. Internal phase of photosensitive microcapsules control

[0166]

[0167] Preparation of color developer coating

[0168] The developer compositions shown in Table 3 were coated onto 1 mil clear PET film using a Myrad rod and dried in an 80°C oven for 10 minutes with a target dry coating thickness of approximately 8 μm as measured by a Mitutoyo thickness gauge.

[0169] Table 3. Composition of developer coating

[0170]

[0171] Preparation of microcapsule coating

[0172] The coating fluid of the R / G / B photosensitive microcapsules (Examples 1-1, 1-2 and 1-3) shown in Table 4 was adjusted to 33 wt% solids by DI water and coated on 2 mil white PET with a Myrad rod. The target dry coating thickness was about 8 μm as measured by a Mitutoyo thickness gauge. The coating was dried in an 80°C oven for 10 minutes.

[0173] Table 4. Composition of microcapsule coating fluid

[0174]

[0175] Preparation of an imaging sheet comprising a photosensitive microcapsule layer and a developer layer

[0176] The microcapsules and developer films thus prepared were laminated together using a Tamerica roll laminator TCC2700 with the temperature, pressure and speed set to 100° C., 3.621 Kgf / 170 mm and 0.368 m / min, respectively, to form various photosensitive imaging sheets.

[0177] Example 2. Preparation of photosensitive microcapsules with color filter shells and self-contained imaging sheets based on the microcapsules

[0178] Self-contained imaging sheets containing different concentrations of color filter pigments on or in the shell were prepared using the same procedure as in Example 1, except that in step 4 of the microencapsulation procedure: (i) the resulting mixture was stirred for 30 minutes, (ii) the microencapsulation products as shown in Tables 5 and Figure 5 The water-based pigment dispersion shown in is thoroughly mixed with 10 parts of DI water and added to the mixture, and (iii) 11 parts of a 9.1% aqueous solution of diethylenetriamine (DETA) (pH adjusted to 7.0) are added, and the resulting mixture is reacted at 25°C for 30 minutes and then at 40°C for one hour.

[0179] Table 5. Color filter pigments grafted or embedded in or on the microcapsule shell

[0180]

[0181] *phi: parts per hundred parts of internal phase or parts per hundred parts of core material by weight

[0182] The chemical structures of Pigment Yellow 155 and Pigment Violet 19 are as follows Figure 3A and Figure 3B shown.

[0183] All of the microcapsules thus prepared were thoroughly washed with water and centrifuged to remove excess water-soluble polymer and additives from the aqueous phase. As can be clearly seen in Table 6, all of the purified / washed microcapsules exhibited similar particle sizes, as measured by a HORIBA LA-960 (laser scattering particle size distribution analyzer). No aggregation of the microcapsules was observed.

[0184] Table 6. Particle size of purified microcapsules

[0185]

[0186] Reducing blue light-induced crosstalk in green-sensitive imaging sheets

[0187] The blue-sensitive imaging sheet of Example 1-1 (Control-B) and the green-sensitive imaging sheet of Example 1-2 (Control-G), as well as Examples 2-1, 2-2, and 2-3 containing yellow filter housings of different concentrations of yellow pigment 155, were placed directly on a Visionox OLED panel (Model G1392FH101GG-003) and exposed to a 0-255 level (0 level is darkest and 255 level is lightest) RGB grayscale image for 20 seconds. The exposed imaging sheet was developed using a pressure device, and the normalized reflected optical density of the developed image as a function of relative blue energy output (blue HD curve) is shown in FIG. Figure 4 middle.

[0188] As from Figure 4 It can be seen that the green-sensitive imaging sheets (Examples 1-2, 2-1, 2-2, and 2-3) can also be hardened by the blue light from the OLED panel, although their photosensitivity is significantly lower than that of the blue-sensitive imaging sheet (Example 1-1, Control-B). Figure 4 It can also be seen that the imaged sheeting of Example 1-2 (Control-G) exhibits significant crosstalk due to blue light exposure. A blue energy level of about 130 is required to fully harden Control B (Example 1-1) to yellow D min At this high blue energy level exposure, the imaged sheeting of Control-G (Example 1-2) also partially hardened, resulting in a decrease in magenta OD of approximately 30%. Figure 4 As can also be seen in the Figure 2, incorporating Yellow Pigment 155 into the outer shell of the green-sensitive microcapsules (Examples 2-1, 2-2, and 2-3) results in a significant increase in the blue energy required to harden the green-sensitive microcapsules. After exposure of the imaged sheeting to a blue energy level of approximately 130, no reduction in magenta density was observed for microcapsules containing Pigment Yellow 155 with a phi of ≥0.488. The color filter outer shell containing Pigment Yellow 155 appears to be very effective in reducing crosstalk caused by the blue color of the green-sensitive microcapsules.

[0189] The sensitivity of yellow filter housings containing different concentrations of yellow pigment 155 to green light (E 10 and E 90 ) and D max and D min The impact is shown in Table 7.

[0190] Table 7. Effect of yellow filter housing on the optical function of green-sensitive imaging sheeting

[0191]

[0192] D min 、D max 、E 10 、E 90 is defined as follows:

[0193] Dmin : Average minimum reflected color (cyan, magenta, or yellow) density of the fully exposed area

[0194] D max : Average maximum color (cyan, magenta, or yellow) density developed in unexposed areas

[0195] E 10 (Level): The total density (D max -D min ) Reduce the energy level required by 10% (0-255)

[0196] E 90 (Level): The total density (D max -D min ) The energy level required to reduce by 90% (0-255).

[0197] All optical densities were measured by a spectrodensitometer FD-5 (Konica Minolta, M0, ISO-E) immediately after exposure, pressure development, and post-heating via a heating roller at 100°C.

[0198] Table 7 shows that the filter housing pairs containing Pigment Yellow 155 ≤ 0.488 phi include Magenta D min Yellow D min , Magenta D max , Green E 10 and E 90 Almost all optical functions including α-D showed no significant effect (or within experimental error). Microcapsules containing high concentration (≥0.733 phi) of Pigment Yellow 155 (a yellow pigment commonly used in inkjet printing) in the shell showed yellow D min and Green-E 10 Without being bound by theory, it is believed that too high a concentration of yellow pigment may lead to degradation of the cross-linking and / or oxygen barrier properties of the shell and result in E 10 Increase (i.e., initial speed decreases).

[0199] Table 7 also shows that no hardening was observed for any of the green-sensitive imaged sheets after full exposure to the highest level of red light. Such effects are attributed to the very limited overlap of the red emission spectrum of the OLED used with the absorption spectrum of the green photoinitiator.

[0200] Reducing green light-induced crosstalk in red-sensitive imaging sheets

[0201] As from Figure 5It can be seen that the red-sensitive imaging sheets (Examples 1-3, 2-4, 2-5, and 2-6) containing a cyan leuco dye (CAS: 114090-18-5) can be hardened by green light from the OLED panel, although their photosensitivity is significantly lower than that of the green-sensitive imaging sheet (Example 1-2, Control-G) containing a magenta leuco dye (CAS: 50292-95-0). Figure 5 It can also be seen that the imaged sheeting of Example 1-3 (Control-R) exhibits significant crosstalk caused by green light exposure. A green energy level of about 130-140 is required to fully harden Control-G (Example 1-2) to achieve a magenta D min However, similar to the cyan crosstalk discussed previously, green light-induced hardening of the red-sensitive microcapsules was also observed at this high green energy level exposure (crosstalk of red-sensitive imaging sheeting caused by green light exposure). When the green exposure energy was high enough to reach the magenta Dmin, the imaging sheeting of Control-R (Examples 1-3) was also partially hardened to cause a decrease in cyan OD by about 30%. Figure 5 It can also be seen that incorporating Pigment Violet 29 (a magenta pigment commonly used in inkjet printing) into the shell of the red-sensitive microcapsules (Examples 2-4, 2-5, and 2-6) results in a significant increase in the green energy required to harden the red-sensitive microcapsules. For microcapsules containing Pigment Violet 29 with a phi of ≥ 0.376 (Examples 2-5 and 2-6), almost no decrease in cyan density was observed even after the imaged sheet was exposed at a green energy level high enough to completely harden the green microcapsules to achieve a magenta Dmin of about 130. The color filter shell containing Pigment Violet 29 also appears to be very effective in reducing crosstalk caused by the green color of the red-sensitive microcapsules.

[0202] Figure 6 OD curves of Examples 1-2 (Control-G), 1-3 (Control-R), and Examples 2-1 to 2-6 are shown as a function of green light exposure. Figure 6 It can be seen that the yellow filter housing (Examples 2-1, 2-2, and 2-3) achieves magenta D for all four green sensitive imaging sheets. min The required green energy had little effect, even at the highest shell loading (0.733 phi) of Pigment Yellow 155. Consequently, incorporation of a yellow pigment into the shell of green-sensitive microcapsules showed no effect on green crosstalk from red-sensitive microcapsules, but, as shown in Figure 4, it effectively reduced blue-induced crosstalk from green-sensitive microcapsules.

[0203] Magenta filter housing for red sensitivity (E 10 and E 90 ) and D max and D minThe effects of are shown in Table 8.

[0204] As can be seen from Table 8, the filter housing pairs containing Pigment Violet 29 with a phi of ≤ 0.556 include Cyan D min , Magenta D min , Cyan D max and Red-E 90 Almost all optical functions including the α-D-type ... min and Red-E 10 There was a slight increase in the amount of pigment, which may be due to the high pigment loading that degrades the crosslinking and / or oxygen barrier properties of the shell. As can be seen in Table 8, no hardening was observed after full exposure to the highest level of blue light for all red-sensitive imaging sheets. This is mainly because the blue emission spectrum of the OLED used does not overlap with the absorption spectrum of the red photoinitiator.

[0205] Table 8. Effect of Magenta Filter Housing on the Photofunctionality of Red-Sensitive Imaging Sheeting

[0206]

[0207] Example 3 Green-sensitive and red-sensitive microcapsules containing color filter pigments in the shell and high concentration of free radical quenchers in the core

[0208] The internal phase compositions of the green-sensitive microcapsules and the red-sensitive microcapsules and the procedures for preparing the microcapsules and the imaging sheet were the same as those described in Examples 1 and 2, except that a high concentration (0.3-0.6 parts per hundred monomer or phm) of an antioxidant from BASF was added. 1035 is added to the core material of microcapsules as a free radical quencher or polymerization retarder / inhibitor. The internal formulations of the green sensitive microcapsules of Examples 3-1 and 3-2 are the same as those of Example 2-3 except that the concentration of The internal phase formulations of the red sensitive microcapsules of Examples 3-3 and 3-4 are the same as those of Example 1-3 except for the concentration of 1035. 50 The differences in particle size are shown in Table 9. Microcapsule-based imaging sheeting was prepared using the procedure described in Example 2, and the characteristic optical functions of the imaging sheeting are shown in Tables 10 and 11 and Figures 7 and 8.

[0209] Table 9. Inclusion of antioxidants in the core material 1035 and containing a microcapsule of color filter pigment in the shell

[0210]

[0211] Table 10. Antioxidants in core materials Effect of 1035 on the optical function of green-sensitive imaging sheeting containing 0.733Phi Yellow 155 in the housing

[0212]

[0213] Table 11. Antioxidants in core materials Effect of 1035 on the photofunctionality of red-sensitive imaging sheeting containing 0.566Phi Violet 19 in the housing

[0214]

[0215] As can be clearly seen from Tables 9, 10 and 11, the free radical quencher in the core material The increase of 1035 concentration from 0.15 phm to 0.60 phm did not show any effect on the particle size of microcapsules. min and D max However, for the green-sensitive microcapsules containing filter yellow 155 with a diameter of 0.733 phi in the shell, a higher contrast HD curve was produced, E 10 The photosensitive speed decreased when the microcapsules began to harden, and E 90 The decrease was 4.5-12.5% ​​(photospeed was increased to reach a state where the microcapsules were almost completely hardened). Similarly, for red-sensitive microcapsules containing 0.566 phi filter violet 19 in the shell, which produced an even significantly higher contrast HD curve, E 10 increased by 5.9-31.4%, and E 90 The decrease was 6.5-14.6%. Figure 7A and 7B As can be clearly seen from the HD curve shown in , the undesirable crosstalk is significantly alleviated.

[0216] The blue-sensitive imaging sheet of Example 1-1 (Control-B) and the sheet containing 0.15, 0.3 and 0.6 phm of The green-sensitive imaging sheets of Examples 2-3, 3-1, and 3-2, containing 1035 as a free radical quencher and 0.733 phi Yellow 155 in the shell, were exposed with blue light from a Visionox OLED panel as described in Example 2. Figure 7A As shown, at a blue energy level of about 130-140, the blue-sensitive control-B (Example 1-1) reached a yellow Dmin. However, at the same level of blue exposure energy, the two green-sensitive imaging sheets of Examples 2-3 and 3-1 showed similar OD reductions, with the highest concentration (0.60 phm) The imaged sheeting of Example 3-2 did not show any OD reduction until the blue energy level was above about 150. From Tables 10 and Figure 7A It is obvious that Increasing the concentration of 1035 from 0.15 phm to 0.60 phm resulted in a significant reduction in blue crosstalk for green-sensitive imaging sheets, while magenta D max and D min There is no obvious trade-off.

[0217] The core material of the red-sensitive imaging sheet (Examples 2-6, 3-3 and 3-4) The effect of 1035 concentration and 0.566 phi filter purple 19 in the microcapsule shell on green crosstalk can also be found in Figure 7B As can be clearly seen in Table 11, 0.60 phm was added to the core material of the red sensitive microcapsule. 1035 also results in a significant reduction in green crosstalk, while cyan D max and D min There are no compromises.

[0218] Example 4. Green-sensitive and red-sensitive imaging sheets containing color filter pigments in microcapsule cores

[0219] The formulation and procedure for making the self-contained imaging sheets of Examples 3-2 (green sensitive) and 3-4 (red sensitive) were repeated, except that filter pigments Yellow 155 (0.733 phi) and Violet 19 (0.566 phi) were ground and dispersed in the internal phase and encapsulated for use in Examples 4-1 and 4-2, respectively. The results are shown in Table 12.

[0220] Table 12. Effect of filter dyes / pigments in the core material versus in the shell

[0221]

[0222] As can be clearly seen from Table 12, the green-sensitive imaging sheet containing the yellow 155 filter pigment in the shell (Example 3-2) exhibited significantly lower yellow D compared to the imaging sheet containing the same yellow pigment in the core (Example 4-1). min and clearer contrast (smaller E 90 -E 10 ). It is clear that during the development step, a higher concentration of yellow pigment is transferred to the developer layer and results in a higher yellow D when included in the core material. min In addition, the presence of pigments in the core material also leads to slower photospeed (higher E 90 ) reaches D min Without being bound by theory, it is believed that the pigments included in the shell tend to be fixed in the highly cross-linked shell and result in a lower yellow D min, as shown in the schematic diagram of Figure 2. In addition, since the pigment does not contact the monomers in the internal phase, it has little effect on the polymerization or cross-linking of the multifunctional monomers in the core material.

[0223] Lower magenta D values ​​were also observed for the red-sensitive imaging sheet of Example 3-4 incorporating the violet 19 pigment in the shell compared to the imaging sheet of Example 4-2 in which the filter pigment was dispersed in the core. min and clearer contrast.

[0224] The compositions and methods illustratively described herein may be suitably implemented in the absence of any one or more elements or one or more limitations not specifically disclosed herein. Thus, for example, the terms "comprise," "include," "contain," and the like should be understood broadly and not in a restrictive sense. Furthermore, the terms and expressions used herein have been used as descriptive and not restrictive terms, and no equivalents of the features shown and described, or portions thereof, are intended to be excluded when such terms and expressions are used. It should be recognized that various modifications may be made within the scope of the claimed disclosure. Therefore, it should be understood that although the present disclosure has been specifically disclosed through preferred embodiments and optionally selected features, modifications and variations of the disclosure disclosed herein and embodied therein may be adopted by those skilled in the art, and such modifications and variations are considered to be within the scope of the present disclosure.

[0225] Unless the context indicates otherwise, it is specifically intended that the various features of the invention described herein may be used in any combination. Furthermore, the present disclosure contemplates that in some embodiments, any feature or combination of features described herein may be excluded or omitted. For illustration, if the specification states that a compound comprises components A, B, and C, it is specifically intended that any one or combination of A, B, or C may be omitted or disclaimed, individually or in any combination.

[0226] The present disclosure has been described broadly and generally herein. Each narrower class and sub-class group belonging to the general disclosure also forms part of the composition or method. This includes the general description of the composition or method, with the proviso or negative limitation that any subject matter is deleted from the genus, regardless of whether the deleted material is specifically cited herein. The technology is not limited to the specific embodiments described in this application, which are intended as representative illustrations of individual aspects of the technology. Many modifications and variations can be made to the technology without departing from the spirit and scope of the technology, which will be apparent to those skilled in the art. In addition to those listed herein, functionally equivalent compositions, methods and devices within the scope of the technology will be apparent to those skilled in the art based on the foregoing description. Such modifications and variations are intended to fall within the scope of the technology. It should be understood that the technology is not limited to specific methods, compounds or compositions, which can of course vary. It should also be understood that the terms used herein are used only for the purpose of describing specific embodiments and are not intended to be limiting.

[0227] Those skilled in the art will readily appreciate that the present disclosure is well adapted to carry out the objects and obtain the purposes and advantages mentioned, as well as those inherent therein. Modifications and other uses thereof will occur to those skilled in the art. Such modifications are encompassed within the spirit of the present disclosure and are limited by the scope of the claims, which set forth non-limiting embodiments of the present disclosure.

[0228] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

1. A photosensitive microcapsule for a microcapsule imaging sheet, comprising: Color filter housing; and The core material comprises a leuco dye or a dye precursor, a photoinitiator or a photosensitizer, and a photohardenable or photosoftenable material.

2. The photosensitive microcapsule according to claim 1, wherein the photoinitiator or photosensitizer is red-sensitive, and the color of the color filter housing is magenta, yellow, or any combination thereof. 3 . The photosensitive microcapsule according to claim 1 , wherein the photoinitiator or photosensitizer is green-sensitive, and the color of the color filter housing is cyan, yellow, or any combination thereof.

4. The photosensitive microcapsule according to claim 1, wherein the photoinitiator or photosensitizer is blue-sensitive, and the color of the color filter housing is magenta, cyan or any combination thereof. 5 . The photosensitive microcapsule according to claim 1 , wherein the photoinitiator or photosensitizer is IR sensitive, and the color of the color filter housing is cyan, magenta, yellow, or any combination thereof. The photosensitive microcapsule according to claim 1 , wherein the photohardenable material comprises a photopolymerizable or cross-linkable monomer or oligomer.

7. The photosensitive microcapsule according to claim 6, wherein the polymerizable or cross-linkable monomer or oligomer is selected from multifunctional acrylates or methacrylates, multifunctional vinyl ethers, multifunctional allyl or vinyl benzenes, and oligomers, dendrimers or blends thereof. The photosensitive microcapsule according to claim 1 , wherein the photosoftenable material comprises a photodegradable or photodepolymerizable polymer.

9. The photosensitive microcapsule according to claim 1, wherein the leuco dye is cyan, magenta, yellow, black leuco dye or any combination thereof. 10 . The photosensitive microcapsule according to claim 1 , wherein the photoinitiator is a cyanine borate, a hemicyanine borate, a triarylmethane, a squarylium or a thiopyrylium dye. The photosensitive microcapsule according to claim 1 , wherein the photoinitiator or photosensitizer comprises a UV-sensitive, blue-sensitive, green-sensitive, red-sensitive or near-IR-sensitive photoinitiator or photosensitizer.

12. The photosensitive microcapsule according to claim 1, wherein the photosensitive microcapsule is sensitive to a specific color or a specific range of radiation spectrum, and the shell contains one or more color filter dyes or pigments, which allow wavelengths corresponding to the color or radiation spectrum range to pass through to the core material, but selectively absorb or filter out all or part of the radiation outside the specific color or range.

13. The photosensitive microcapsule according to claim 12, wherein the one or more filter dyes or pigments are bleachable, including thermally bleachable or photobleachable.

14. The photosensitive microcapsule according to claim 12, wherein the one or more color filter dyes or pigments comprise functional groups that react with one or more shell-forming materials.

15. The photosensitive microcapsule according to claim 14, wherein the functional group is selected from the group comprising: -OH, -SH, -NH2, -N-HR, -CONH2, -NCO, -NCS-, -CH2OH, -CH2OR, -CHO and precursors thereof, wherein R is an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group or a heteroatom derivative thereof. 16 . The photosensitive microcapsule according to claim 14 , wherein the one or more shell-forming materials are included in the inner phase and / or the outer phase, and form the outer shell by interfacial polymerization or cross-linking during microencapsulation.

17. The photosensitive microcapsule according to claim 14, wherein the one or more shell-forming materials are included in the external phase and form the outer shell by in situ polymerization or cross-linking, phase separation or coacervation during the microencapsulation process.

18. The photosensitive microcapsule of claim 1, wherein the one or more filter dyes or pigments are present in the microcapsule in an amount of about 0.01 to about 3 parts by weight per hundred parts of core material or per hundred parts of internal phase.

19. The photosensitive microcapsule according to claim 1, wherein when the photosensitive microcapsule is a green-sensitive or red-sensitive microcapsule and the one or more filter dyes or pigments are yellow (blue-absorbing) filter dyes or pigments, the absorption optical density of the yellow (blue-absorbing) filter shell is from about 0.005 to about 0.3, preferably from about 0.05 to about 0.2 in the range of 450 to 500 nm.

20. The photosensitive microcapsule according to claim 1, wherein when the photosensitive microcapsule is a blue-sensitive or red-sensitive microcapsule and the one or more filter dyes or pigments are magenta (green-absorbing) filter dyes or pigments, the absorption optical density of the magenta (green-absorbing) filter shell is about 0.005 to 0.3 in the range of 550 to 600 nm, preferably about 0.05 to about 0.

2. The photosensitive microcapsule according to claim 1 , wherein the core material does not contain any color filter dye or pigment. The photosensitive microcapsule according to claim 1 , wherein the core material further comprises a free radical inhibitor, blocker or antioxidant.

23. The photosensitive microcapsule according to claim 22, wherein the free radical inhibitor, antioxidant or retardant is selected from the group consisting of phenols, anilines, N-oxides of hindered amines, CuO, copper dithiocarbamates, copper carboxylates or manganese carboxylates and thiuram (thiocarbamoyl) derivatives, including where R 1 、R 2 、R 3 and R 4 and are independently an alkyl group having 1 to 8 carbon atoms or a phenyl group.

24. The photosensitive microcapsule of claim 1, wherein the free radical inhibitor, retarder or antioxidant is present in the internal phase at a concentration of about 0.1 to about 1.0 parts by weight per hundred parts of monomer.

25. The photosensitive microcapsule of claim 24, wherein the free radical inhibitor, retarder or antioxidant is present in the internal phase at a concentration of about 0.3 to 0.8 parts by weight per hundred parts of monomer. The photosensitive microcapsule according to claim 1 , wherein the core material further comprises a co-initiator, an oxygen scavenger or an auto-oxidant.

27. A microcapsule imaging sheet comprising: a first substrate; and a photosensitive microcapsule layer comprising photosensitive microcapsules in contact with the first surface of the first substrate, The photosensitive microcapsules comprise: Color filter housing; and The core material comprises a leuco dye, a photoinitiator or a photosensitizer, and a photohardenable or photosoftenable material.

28. The microcapsule imaging sheet according to claim 27, wherein the microcapsule imaging sheet is a full-color imaging sheet comprising photosensitive microcapsules, and the photosensitive microcapsules include red-sensitive, green-sensitive and blue-sensitive microcapsules.

29. The microcapsule imaging sheet according to claim 27, wherein the photosensitive microcapsule layer further comprises a developer.

30. The microcapsule imaging sheet according to claim 27, wherein the photosensitive microcapsule layer further comprises a separate developer layer.

31. The microcapsule imaging sheet of claim 27, further comprising a developer layer in contact with: (i) the microcapsule layer; and / or (ii) a developer substrate.

32. The microcapsule imaging sheet of claim 31, wherein the developer substrate is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, polyolefin, cyclic olefin copolymer (COC), cellulose acetate, or copolymers, blends, or composites thereof.

33. A method of imaging or printing, the method comprising: image-wise exposing the imaged sheeting according to claim 27 to heat or radiation, wherein the exposure is sufficient to harden or soften the microcapsules in the microcapsule layer to produce a latent image; and The latent image is developed by pressure and / or heat, thereby releasing the leuco dye or dye precursor and forming an image.

Images