Thermal printing ink and preparation method thereof

Abstract

The invention relates to the field of ink, and discloses thermal printing ink and a preparation method thereof.The thermal printing ink is prepared from, by weight, 70 parts of waterborne polyurethane emulsion, 18-25 parts of durable color developing agent, 10-15 parts of isopropanol, 0.05-0.08 part of antioxidant, 0.5-0.9 part of defoaming agent, 0.5-2 parts of flatting agent and 0.8-1.3 parts of dispersing agent; a carbamate structure in the coating modification auxiliary agent and hydroxyl in the fixed color developing agent can form a hydrogen bond, and the coating modification auxiliary agent can be cured under the action of an initiator through unsaturated double bonds in the coating modification auxiliary agent to form an organic protective layer on the surface of the organic thermosensitive dye, so that the organic thermosensitive dye is isolated from the external environment; meanwhile, the hindered amine structure loaded on the organic protective layer can absorb ultraviolet light, so that the damage of the ultraviolet light to the durable color developing agent is reduced, and the durability of the thermal printing ink is further enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of inks, and particularly relates to a color-durable thermal printing ink and a preparation method thereof. Background Art

[0002] Thermal printing, also known as thermal transfer printing, refers to a printing method in which a colorless thermal dye layer is transferred to paper, and when the graphic part is heated, a color is generated. Currently, thermal printing has been widely used in communications, typing, telegraph output, etc. Its advantages are that the thermal printing volume device is small, the structure is compact, there is no noise, the reliability is good, and the adaptability is strong; and the thermal ink is matched with it. The thermal ink contains a thermal dye. When the temperature rises, the thermal dye will undergo a chemical change, thereby changing the color of the thermal ink.

[0003] Organic thermal dyes have the advantages of adjustable discoloration temperature, selectable color, high self-adjustability, low material cost, and good safety performance. The most studied organic thermal dyes are organic ternary complexes composed of lactones / fluorans, bisphenols, and alcohols, among which the complexes of fluorans, bisphenols, and alcohols are the most studied. During the use of organic thermal dyes, their colors will become lighter and lighter due to the self-decomposition of the active ingredients to varying degrees. Moreover, with long storage time, long heating time, and under high temperature and humidity conditions, the loss of their active ingredients will be accelerated, and then the ability to respond to heat will be lost.

[0004] In the prior art, the microcapsule technology is used in organic thermal dyes to improve the influence of the external environment on organic thermal dyes. For example, melamine-formaldehyde resin is used to reduce the influence of the environment on color durability. However, melamine-formaldehyde resin is easily decomposed under strong acid and alkali conditions, and under ultraviolet light irradiation, the unsaturated structure and amino groups in melamine-formaldehyde resin will accelerate the oxidation reaction with oxygen in the air to form oxidation products, causing yellowing and shortening the life of its microcapsules, which limits the further application of thermal printing inks. Summary of the Invention

[0005] In order to solve the technical problems mentioned in the background art, the purpose of the present invention is to provide a color-durable thermal printing ink and a preparation method thereof, which can reduce the damage of ultraviolet light to the durability color former and improve the durability and color rendering effect of the thermal printing ink.

[0006] According to the first aspect of the purpose of the present invention, a thermal printing ink is proposed, which includes 70 parts of an aqueous polyurethane emulsion, 18 - 25 parts of a color former, 10 - 15 parts of isopropanol, 0.05 - 0.08 parts of an antioxidant, 0.5 - 0.9 parts of an antifoaming agent, and 0.8 - 1.3 parts of a dispersant by weight.

[0007] The colorant is an ultraviolet durable colorant, which is obtained by adding an organic thermosensitive dye into a coating liquid mixed with a coating modification auxiliary agent, an initiator and ethanol and compressing the mixture to obtain droplets.

[0008] As an optional implementation, the coating modification auxiliary agent is configured to be obtained by reacting pentaerythritol triallyl ether and chloroethyl isocyanate with 2,2,6,6-tetramethyl-4-piperidinol after a coordinated reaction.

[0009] As an optional implementation, the organic thermosensitive dye is formed by mixing a fixed color former, a fixed color developer and hexadecanol.

[0010] As an optional embodiment, the carbamate structure in the coating modification auxiliary agent can form hydrogen bonds with the hydroxyl groups in the fixed color developer, thereby fixing the organic thermosensitive dye on the coating modification auxiliary agent molecules through adsorption, and can be cured through the unsaturated double bonds in the coating modification auxiliary agent under the action of an initiator to form a stable organic protective layer on the surface of the organic thermosensitive dye.

[0011] As an optional embodiment, the durable coloring agent is prepared by the following method:

[0012] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0013] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0014] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0015] Step A4: Mix the coating modification aid, initiator and ethanol, stir for 0.5 hours to obtain a coating liquid; then add the organic thermosensitive dye to the coating liquid, stir for 20 minutes, and then compress it into tiny droplets, then put it into a drying chamber for drying, and finally collect it to obtain a durable colorant.

[0016] As an optional implementation, in the step A1, the usage ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol is 1 mol: 1 mol: 0.2-0.5 g: 70 mL.

[0017] As an optional embodiment, in step A2, the usage ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1 mol: 1 mol: 0.3-0.5 g: 80 mL.

[0018] As an optional embodiment, in the step A3, the usage ratio of the fixed color forming agent, the fixed color developing agent and hexadecanol is 1g:2g:5g.

[0019] As an optional embodiment, in step A4, the amount ratio of the coating modification auxiliary agent, the initiator, the ethanol and the organic thermosensitive dye is 12-15 g: 0.05 g: 20 mL: 6 g;

[0020] The initiator is dibenzoyl peroxide.

[0021] According to a second aspect of the present invention, a method for preparing a thermal printing ink is also provided, comprising the following steps:

[0022] Step S1: preparing a durable coloring agent, specifically comprising the following steps A1-A4:

[0023] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0024] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0025] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0026] Step A4: Mix the coating modification auxiliary agent, initiator and ethanol, stir for 0.5 hours to obtain a coating solution; then add the organic thermosensitive dye to the coating solution, stir for 20 minutes, and then compress it into tiny droplets, and then put it into a drying room for drying, and finally collect the durable colorant, and seal and store it in a cool and dry place for future use;

[0027] Step S2: taking a durable colorant, a dispersant, a defoamer, an aqueous polyurethane emulsion, isopropyl alcohol, and an antioxidant in parts by weight, mixing and adding the mixture, dispersing the mixture in a disperser for 0.5-4 hours, and fully stirring and dispersing the mixture to obtain a thermal printing ink.

[0028] In order to further improve the dispersibility of the pigment, according to the third aspect of the present invention, a method for preparing a thermal printing ink is also provided, comprising the following steps:

[0029] Step S1: preparing a durable coloring agent, specifically comprising the following steps A1-A4:

[0030] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0031] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0032] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0033] Step A4: Mix the coating modification auxiliary agent, initiator and ethanol, stir for 0.5 hours to obtain a coating solution; then add the organic thermosensitive dye to the coating solution, stir for 20 minutes, and then compress it into tiny droplets, and then put it into a drying room for drying, and finally collect the durable colorant, and seal and store it in a cool and dry place for future use;

[0034] Step S2: taking a durable colorant, a dispersant and a defoamer according to the weight parts, mixing and adding the materials, dispersing them in a disperser for 0.5-2h, and fully stirring and dispersing to obtain a pigment dispersion;

[0035] Step S3: taking the aqueous polyurethane emulsion, isopropyl alcohol and antioxidant according to the weight parts, mixing them with the pigment dispersion and feeding them into a reactor, mixing for 1-4 hours, and obtaining a thermal printing ink.

[0036] Wherein, in step S2 and step S3, the stirring rate is controlled to be 1000-1500 r / min.

[0037] Furthermore, the antioxidant is preferably antioxidant 1010, the dispersant is preferably sodium dodecylbenzene sulfonate, and the defoaming agent is preferably an organosilicon defoaming agent or polydimethylsiloxane.

[0038] Combined with the thermosensitive printing ink and its preparation method proposed by the present invention above, by compounding and blending with a durable color former, it has higher durability under ultraviolet light irradiation compared with the existing thermosensitive printing ink. Among them, the coating modification assistant in the durable color former is obtained by reacting pentaerythritol triallyl ether with chloroethyl isocyanate and then reacting with 2,2,6,6-tetramethyl-4-piperidinol; the organic thermosensitive dye is composed of a fixed chromogen, a fixed developer and cetyl alcohol; the carbamate structure in the coating modification assistant can form a hydrogen bond with the hydroxyl group in the fixed developer, and fix the organic thermosensitive dye on the coating modification assistant molecule through "adsorption", and can be cured under the action of an initiator through the unsaturated double bond in the coating modification assistant to form a chemically stable organic protective layer on the surface of the organic thermosensitive dye. In this way, the organic thermosensitive dye is isolated from the external environment through the organic protective layer, improving the stability of the organic thermosensitive dye, and thus improving the durability of the thermosensitive printing ink.

[0039] At the same time, the hindered amine structure loaded on the organic protective layer can absorb ultraviolet light, reducing the damage of ultraviolet light to the durable color former and further strengthening the durability of the thermosensitive printing ink.

[0040] It should be understood that all combinations of the foregoing concepts and additional concepts described in more detail below can be regarded as part of the inventive subject matter of the present disclosure as long as such concepts do not contradict each other. In addition, all combinations of the claimed subject matter are regarded as part of the inventive subject matter of the present disclosure.

[0041] The foregoing and other aspects, embodiments and features of the teachings of the present invention can be more fully understood in light of the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent in the following description or will be learned through practice of the specific embodiments according to the teachings of the present invention. Detailed Embodiments

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. It should be understood that the various concepts and implementations disclosed and elaborated in the present invention can be implemented in any of many ways, because the concepts and embodiments disclosed in the present invention are not limited to any implementation manner. In addition, some aspects disclosed in the present invention can be used alone, or in any suitable combination with other aspects disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] The thermal printing ink proposed in the embodiment of the present invention includes, by weight, 70 parts of aqueous polyurethane emulsion, 18-25 parts of colorant, 10-15 parts of isopropyl alcohol, 0.05-0.08 parts of antioxidant, 0.5-0.9 parts of defoaming agent and 0.8-1.3 parts of dispersant.

[0044] The colorant is an ultraviolet durable colorant, which is obtained by adding an organic thermosensitive dye into a coating liquid mixed with a coating modification auxiliary agent, an initiator and ethanol and compressing the mixture to obtain droplets.

[0045] As an optional embodiment, the coating modification auxiliary agent is configured to be obtained by reacting pentaerythritol triallyl ether and chloroethyl isocyanate with 2,2,6,6-tetramethyl-4-piperidinol after a coordinated reaction.

[0046] As an optional embodiment, the organic thermosensitive dye is formed by mixing a fixed color former, a fixed color developer and hexadecanol.

[0047] As an optional implementation, the carbamate structure in the coating modification auxiliary agent can form hydrogen bonds with the hydroxyl groups in the fixed color developer, thereby fixing the organic thermosensitive dye on the coating modification auxiliary agent molecules through adsorption, and can be cured through the unsaturated double bonds in the coating modification auxiliary agent under the action of an initiator to form a stable organic protective layer on the surface of the organic thermosensitive dye.

[0048] As an optional embodiment, the durable coloring agent is prepared by the following method:

[0049] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0050] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0051] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0052] Step A4: Mix the coating modification aid, initiator and ethanol, stir for 0.5 hours to obtain a coating liquid; then add the organic thermosensitive dye to the coating liquid, stir for 20 minutes, and then compress it into tiny droplets, then put it into a drying chamber for drying, and finally collect it to obtain a durable colorant.

[0053] Wherein, in the aforementioned step A2, the hydroxyl group in pentaerythritol triallyl ether reacts with chloroethyl isocyanate to introduce halogen. As an example, the specific reaction process is as follows:

[0054]

[0055] In the aforementioned step A3, the hydroxyl group in 2,2,6,6-tetramethyl-4-piperidinol reacts with the carbamate intermediate to graft 2,2,6,6-tetramethyl-4-piperidinol onto the carbamate intermediate. As an example, the specific reaction process is as follows:

[0056]

[0057] As an optional embodiment, in step A1, the usage ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol is 1 mol: 1 mol: 0.2-0.5 g: 70 mL.

[0058] As an optional embodiment, in step A2, the usage ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1 mol: 1 mol: 0.3-0.5 g: 80 mL.

[0059] As an optional embodiment, in step A3, the usage ratio of the fixed color forming agent, the fixed color developing agent and hexadecanol is 1g:2g:5g.

[0060] As an optional implementation, in step A4, the usage ratio of the coating modification auxiliary agent, the initiator, ethanol and the organic thermosensitive dye is 12-15 g: 0.05 g: 20 mL: 6 g.

[0061] Wherein, in the aforementioned step A4, the initiator is dibenzoyl peroxide.

[0062] According to an embodiment of the present invention, a method for preparing a thermal printing ink is also provided, comprising the following steps:

[0063] Step S1: preparing a durable coloring agent, specifically comprising the following steps A1-A4:

[0064] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0065] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0066] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0067] Step A4: Mix the coating modification auxiliary agent, initiator and ethanol, stir for 0.5 hours to obtain a coating solution; then add the organic thermosensitive dye to the coating solution, stir for 20 minutes, and then compress it into tiny droplets, and then put it into a drying room for drying, and finally collect the durable colorant, and seal and store it in a cool and dry place for future use;

[0068] Step S2: taking a durable colorant, a dispersant, a defoamer, an aqueous polyurethane emulsion, isopropyl alcohol, and an antioxidant in parts by weight, mixing and adding the mixture, dispersing the mixture in a disperser for 0.5-4 hours, and fully stirring and dispersing the mixture to obtain a thermal printing ink.

[0069] In order to further improve the dispersibility of pigment coloring, the preparation method of the thermal printing ink according to an embodiment of the present invention comprises the following steps:

[0070] Step S1: preparing a durable coloring agent, specifically comprising the following steps A1-A4:

[0071] Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate;

[0072] Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent;

[0073] Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye;

[0074] Step A4: Mix the coating modification auxiliary agent, initiator and ethanol, stir for 0.5 hours to obtain a coating solution; then add the organic thermosensitive dye to the coating solution, stir for 20 minutes, and then compress it into tiny droplets, and then put it into a drying room for drying, and finally collect the durable colorant, and seal and store it in a cool and dry place for future use;

[0075] Step S2: taking a durable colorant, a dispersant and a defoamer according to weight parts, mixing and adding the materials, dispersing them in a disperser for 0.5-2h, and fully stirring and dispersing to obtain a pigment dispersion;

[0076] Step S3: taking water-based polyurethane emulsion, isopropyl alcohol, antioxidant according to weight parts, mixing them with pigment dispersion, adding them into a reactor, mixing for 1-4 hours, and obtaining thermal printing ink.

[0077] Wherein, in step S2 and step S3, the stirring rate is controlled to be 1000-1500 r / min.

[0078] Among them, in the aforementioned preparation process, the antioxidant is preferably antioxidant 1010, the dispersant is preferably sodium dodecylbenzene sulfonate, and the defoaming agent is preferably silicone defoaming agent or polydimethylsiloxane.

[0079] {Example 1}

[0080] 1) Preparation of durable coloring agent

[0081] a1: Take pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol and mix them into a reactor, control the stirring rate to 400r / min, raise the temperature to 40°C, stir and react for 3h, and then vacuum rotary evaporate to obtain a carbamate intermediate; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol is 1mol:1mol:0.2g:70mL;

[0082] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 300r / min, heat to 30°C, stir and react for 1h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.3g:80mL;

[0083] a3: Mix a fixed color former (CK-16 is used in both the present embodiment and the comparative example), a fixed color developer (bisphenol A is used in both the present embodiment and the comparative example) and hexadecanol and add them into a stirrer, control the stirring rate to 500 r / min, heat to 60°C, stir for 20 min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and hexadecanol is 1g:2g:5g;

[0084] a4: Mix the coating modification auxiliary agent, initiator (dibenzoyl peroxide is used in both the present embodiment and the comparative example) and ethanol and feed them into a stirrer, control the stirring rate to be 1500r / min, and stir for 0.5h to obtain a coating liquid; then add the organic thermosensitive dye into the coating liquid, and then compress it into tiny droplets through the nozzle by compressed air, and then enter the drying chamber, control the temperature of the drying chamber to be 90°C, and finally collect it through a cyclone separator to obtain a durable coloring agent; in the above reaction, the amount ratio of the coating modification auxiliary agent, the initiator, the ethanol and the organic thermosensitive dye is 12g:0.05g:20mL:6g;

[0085] 2) Preparation of thermal printing ink

[0086] 70 parts of aqueous polyurethane emulsion (modified polyurethane emulsion, model FS-7, is used in this embodiment and comparative example), 10 parts of isopropanol, 18 parts of durable colorant, 0.05 parts of antioxidant (antioxidant 1010 is used in this embodiment and comparative example), 0.8 parts of dispersant (sodium dodecylbenzene sulfonate is used in this embodiment and comparative example) and 0.5 parts of defoamer (organic silicon defoamer, model WA-5824 is used in this embodiment and comparative example) are mixed and added into a stirrer, the stirring rate is controlled to be 1000 r / min, and thermal printing ink is obtained after stirring for 1 hour.

[0087] {Example 2}

[0088] 1) Preparation of durable coloring agent

[0089] a1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol were mixed and added into a reactor, the stirring rate was controlled to 420 r / min, the temperature was raised to 42°C, and the reaction was stirred for 3.5 hours, and then the carbamate intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol was 1 mol: 1 mol: 0.3 g: 70 mL;

[0090] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 350r / min, raise the temperature to 32°C, stir and react for 1.5h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.35g:80mL;

[0091] a3: Mix the fixed color former, the fixed color developer and the hexadecanol and add them into a stirrer, control the stirring rate to 520r / min, heat to 62°C, stir for 20min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and the hexadecanol is 1g:2g:5g;

[0092] a4: The coating modification auxiliary agent, initiator and ethanol are mixed and added into a stirrer, the stirring rate is controlled to be 1500r / min, and the coating liquid is obtained after stirring for 0.5h; then the organic thermosensitive dye is added into the coating liquid, and then compressed into tiny droplets by compressed air through a nozzle, and then enters a drying chamber, the temperature of the drying chamber is controlled to be 92°C, and finally collected by a cyclone separator to obtain a durable colorant; in the above reaction, the amount ratio of the coating modification auxiliary agent, initiator, ethanol and organic thermosensitive dye is 13g:0.05g:20mL:6g;

[0093] 2) Preparation of thermal printing ink

[0094] 70 parts of aqueous polyurethane emulsion, 11 parts of isopropanol, 20 parts of durable colorant, 0.06 parts of antioxidant, 0.9 parts of dispersant and 0.6 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1200 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0095] {Example 3}

[0096] 1) Preparation of durable coloring agent

[0097] a1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol were mixed and added into a reactor, the stirring rate was controlled to be 450 r / min, the temperature was raised to 44°C, and after stirring for 4 hours, the carbamate intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol was 1 mol: 1 mol: 0.4 g: 70 mL;

[0098] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 400r / min, raise the temperature to 34°C, stir and react for 2h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.4g:80mL;

[0099] a3: Mix the fixed color former, the fixed color developer and the hexadecanol and add them into a stirrer, control the stirring rate to 540r / min, heat to 64°C, stir for 20min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and the hexadecanol is 1g:2g:5g;

[0100] a4: The coating modification auxiliary agent, initiator and ethanol are mixed and added into a stirrer, the stirring rate is controlled to be 1700r / min, and the coating liquid is obtained after stirring for 0.5h; then the organic thermosensitive dye is added into the coating liquid, and then compressed into tiny droplets by compressed air through a nozzle, and then enters a drying chamber, the temperature of the drying chamber is controlled to be 94°C, and finally collected by a cyclone separator to obtain a durable colorant; in the above reaction, the amount ratio of the coating modification auxiliary agent, initiator, ethanol and organic thermosensitive dye is 14g:0.05g:20mL:6g;

[0101] 2) Preparation of thermal printing ink

[0102] 70 parts of aqueous polyurethane emulsion, 12 parts of isopropanol, 21 parts of durable colorant, 0.07 parts of antioxidant, 1.0 parts of dispersant and 0.7 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1200 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0103] {Example 4}

[0104] 1) Preparation of durable coloring agent

[0105] a1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol were mixed and added into a reactor, the stirring rate was controlled to be 480 r / min, the temperature was raised to 46°C, and after stirring for 4 hours, the carbamate intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol was 1 mol: 1 mol: 0.5 g: 70 mL;

[0106] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 450r / min, heat to 36°C, stir and react for 2h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.5g:80mL;

[0107] a3: Mix the fixed color former, the fixed color developer and the hexadecanol and add them into a stirrer, control the stirring rate to 560r / min, heat to 66°C, stir for 20min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and the hexadecanol is 1g:2g:5g;

[0108] a4: The coating modification auxiliary agent, initiator and ethanol are mixed and added into a stirrer, the stirring rate is controlled to be 1700r / min, and the coating liquid is obtained after stirring for 0.5h; then the organic thermosensitive dye is added into the coating liquid, and then compressed into tiny droplets by compressed air through a nozzle, and then enters a drying chamber, the temperature of the drying chamber is controlled to be 96°C, and finally collected by a cyclone separator to obtain a durable colorant; in the above reaction, the amount ratio of the coating modification auxiliary agent, initiator, ethanol and organic thermosensitive dye is 15g:0.05g:20mL:6g;

[0109] 2) Preparation of thermal printing ink

[0110] 70 parts of aqueous polyurethane emulsion, 13 parts of isopropanol, 22 parts of organic thermosensitive dye microcapsules, 0.08 parts of antioxidant, 1.1 parts of dispersant and 0.8 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1400 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0111] {Example 5}

[0112] 1) Preparation of durable coloring agent

[0113] a1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol were mixed and added into a reactor, the stirring rate was controlled to be 500 r / min, the temperature was raised to 46°C, and after stirring for 4 hours, the carbamate intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol was 1 mol: 1 mol: 0.5 g: 70 mL;

[0114] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 450r / min, heat to 40°C, stir and react for 2h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.5g:80mL;

[0115] a3: Mix the fixed color former, the fixed color developer and the hexadecanol and add them into a stirrer, control the stirring rate to 560r / min, heat to 68°C, stir for 20min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and the hexadecanol is 1g:2g:5g;

[0116] a4: The coating modification auxiliary agent, initiator and ethanol are mixed and added into a stirrer, the stirring rate is controlled to be 2000r / min, and the coating liquid is obtained after stirring for 0.5h; then the organic thermosensitive dye is added into the coating liquid, and then compressed into tiny droplets by compressed air through a nozzle, and then enters a drying chamber, the temperature of the drying chamber is controlled to be 98°C, and finally collected by a cyclone separator to obtain a durable colorant; in the above reaction, the amount ratio of the coating modification auxiliary agent, initiator, ethanol and organic thermosensitive dye is 15g:0.05g:20mL:6g;

[0117] 2) Preparation of thermal printing ink

[0118] 70 parts of aqueous polyurethane emulsion, 14 parts of isopropanol, 23 parts of durable colorant, 0.08 parts of antioxidant, 1.3 parts of dispersant and 0.8 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1500 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0119] {Example 6}

[0120] 1) Preparation of durable coloring agent

[0121] a1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol were mixed and added into a reactor, the stirring rate was controlled to be 500 r / min, the temperature was raised to 50°C, and after stirring for 4 hours, the carbamate intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyl tin dilaurate and ethanol was 1 mol: 1 mol: 0.5 g: 70 mL;

[0122] a2: Take the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene and mix them into a reactor, control the stirring rate to 500r / min, heat to 40°C, stir and react for 2h, and then vacuum evaporate to obtain the coating modification auxiliary agent; in the above reaction, the amount ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1mol:1mol:0.5g:80mL;

[0123] a3: Mix the fixed color former, the fixed color developer and the hexadecanol and add them into a stirrer, control the stirring rate to 560r / min, heat to 68°C, stir for 20min, and then cool to room temperature to obtain an organic thermosensitive dye; in the above reaction, the amount ratio of the fixed color former, the fixed color developer and the hexadecanol is 1g:2g:5g;

[0124] a4: The coating modification auxiliary agent, initiator and ethanol are mixed and added into a stirrer, the stirring rate is controlled to be 2000r / min, and the coating liquid is obtained after stirring for 0.5h; then the organic thermosensitive dye is added into the coating liquid, and then compressed into tiny droplets by compressed air through a nozzle, and then enters a drying chamber, the temperature of the drying chamber is controlled to be 98°C, and finally collected by a cyclone separator to obtain a durable colorant; in the above reaction, the amount ratio of the coating modification auxiliary agent, initiator, ethanol and organic thermosensitive dye is 15g:0.05g:20mL:6g;

[0125] 2) Preparation of thermal printing ink

[0126] 70 parts of aqueous polyurethane emulsion, 15 parts of isopropanol, 25 parts of durable colorant, 0.08 parts of antioxidant, 1.2 parts of dispersant and 0.8 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1500 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0127] {Comparative Example 1}

[0128] s1: 4 parts of a fixed color former, 8 parts of a fixed color developer and 20 parts of hexadecanol were mixed and added into a stirrer, the stirring rate was controlled to be 600 r / min, the temperature was raised to 70°C, stirred for 20 minutes, and then cooled to room temperature to obtain an organic thermosensitive dye;

[0129] s2: 15 parts of urea solution and 15 parts of formaldehyde solution were mixed and added into a stirring tank, the stirring rate was controlled to be 2000 r / min, and after stirring for 0.5 h, sodium hydroxide solution was added to adjust the pH to 9, and then the temperature was raised to 75°C, and after stirring for 1 h, 15 parts of deionized water were added to form a urea-formaldehyde prepolymer solution;

[0130] s3: The organic thermosensitive dye and urea-formaldehyde prepolymer solution are mixed and added into a stirrer, and then acetic acid is added to adjust the pH to 2.5, and then the reaction rate is controlled to 1000 r / min, the temperature is raised to 60°C, and the reaction is stirred for 3 hours, and then washed with distilled water twice, and then dried to obtain a coloring agent;

[0131] s4: 70 parts of aqueous polyurethane emulsion, 10 parts of isopropanol, 18 parts of colorant, 0.08 parts of antioxidant, 1.2 parts of dispersant and 0.8 parts of defoamer were mixed and added into a stirrer. The stirring rate was controlled to be 1500 r / min. After stirring for 1 hour, a thermal printing ink was obtained.

[0132] {Comparative Example 2}

[0133] This comparative example uses a commercially available thermal ink produced by Guangzhou Chongyu Industrial Materials Technology Co., Ltd., which is red in color.

[0134] Acid and alkali resistance test:

[0135] The thermal printing inks of Examples 1-6 and Comparative Examples 1-2 were printed on a 250 g / m 2 The coated paper was then immersed in 30% HCl solution and 15% NaOH solution for 120 hours respectively, and the color changes were observed. The specific test results are shown in Table 1 below:

[0136] Table 1- Comparison of acid and alkali resistance tests

[0137] Test items 30% HCl solution 15% NaOH Example 1 No discoloration, no wrinkling No discoloration, no wrinkling Example 2 No discoloration, no wrinkling No discoloration, no wrinkling Example 3 No discoloration, no wrinkling No discoloration, no wrinkling Example 4 No discoloration, no wrinkling No discoloration, no wrinkling Example 5 No discoloration, no wrinkling No discoloration, no wrinkling Example 6 No discoloration, no wrinkling No discoloration, no wrinkling Comparative Example 1 No discoloration, no wrinkles No discoloration, no wrinkles Comparative Example 2 Discoloration, wrinkles Discoloration, wrinkles

[0138] It can be seen from the data in Table 1 that the thermal printing inks prepared in Examples 1-6 have basically no discoloration and wrinkling after being immersed in 30% HCl solution and 15% NaOH for 120 hours, respectively. However, the thermal printing inks in Comparative Examples 1-2 have discoloration and wrinkling after being immersed in 30% HCl solution and 15% NaOH for 120 hours, respectively, indicating that the thermal printing inks prepared in Examples 1-6 have good acid and alkali resistance.

[0139] Aging color difference test:

[0140] The thermal printing inks of Examples 1-6 and Comparative Examples 1-2 were printed on a 250 g / m 2 On the coated paper surface, the coated paper was then placed in an oven at 55°C and 65% relative humidity. After aging for 3 months, a color difference test was performed in accordance with GB / T3979-2008.

[0141] UV resistance test:

[0142] The thermal printing inks of Examples 1-6 and Comparative Examples 1-2 were printed on a 250 g / m 2 On the coated paper surface, after being irradiated with 30W ultraviolet light for 168h and 720h respectively, the color difference test was carried out according to GB / T3979-2008; the specific test data are shown in Table 2.

[0143] Table 2- Comparison of aging color difference and UV resistance test

[0144]

[0145] From the data in Table 2, it can be seen that the original color difference of the thermal printing ink prepared in Examples 1-6 is 0.41-0.56, which is slightly better than the thermal printing ink of Comparative Examples 1-2. However, after 3 months of aging, 168h and 720h of ultraviolet irradiation, the color difference values ​​of the thermal printing ink prepared in Examples 1-6 are 1.55-1.74, 1.49-1.62 and 5.62-5.83, respectively, which are significantly better than the thermal printing ink of Comparative Examples 1-2. This shows that the thermal printing ink prepared in the present invention still maintains good durability under ultraviolet irradiation.

[0146] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A thermal printing ink, characterized in that: The components include 70 parts of waterborne polyurethane emulsion, 18-25 parts of coloring agent, 10-15 parts of isopropyl alcohol, 0.05-0.08 parts of antioxidant, 0.5-0.9 parts of defoaming agent and 0.8-1.3 parts of dispersant according to weight parts; The colorant is an ultraviolet durable colorant, which is obtained by adding an organic thermosensitive dye into a coating liquid mixed with a coating modification auxiliary agent, an initiator and ethanol and compressing the mixture to obtain droplets.

2. The thermal printing ink according to claim 1, characterized in that: The coating modification auxiliary agent is configured to be obtained by reacting pentaerythritol triallyl ether and chloroethyl isocyanate with 2,2,6,6-tetramethyl-4-piperidinol after a coordinated reaction.

3. The thermal printing ink according to claim 2, characterized in that: The organic thermosensitive dye is prepared by mixing a fixed color former, a fixed color developer and hexadecanol.

4. The thermal printing ink according to claim 3, characterized in that: The carbamate structure in the coating modification auxiliary agent can form a hydrogen bond with the hydroxyl group in the fixed color developer, fix the organic thermosensitive dye on the coating modification auxiliary agent molecule by adsorption, and can be cured by the unsaturated double bonds in the coating modification auxiliary agent under the action of an initiator to form a stable organic protective layer on the surface of the organic thermosensitive dye.

5. The thermal printing ink according to any one of claims 1 to 4, characterized in that: The durable coloring agent is prepared by the following method: Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate; Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent; Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye; Step A4: Mix the coating modification aid, initiator and ethanol, stir for 0.5 hours to obtain a coating liquid; then add the organic thermosensitive dye to the coating liquid, stir for 20 minutes, and then compress it into tiny droplets, then put it into a drying chamber for drying, and finally collect it to obtain a durable colorant.

6. The thermal printing ink according to claim 5, characterized in that: In the step A1, the usage ratio of pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol is 1 mol: 1 mol: 0.2-0.5 g: 70 mL.

7. The thermal printing ink according to claim 5, characterized in that: In the step A2, the usage ratio of the carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene is 1 mol: 1 mol: 0.3-0.5 g: 80 mL.

8. The thermal printing ink according to claim 5, characterized in that: In the step A3, the usage ratio of the fixed color forming agent, the fixed color developing agent and hexadecanol is 1g:2g:5g.

9. The thermal printing ink according to claim 5, characterized in that: In the step A4, the amount ratio of the coating modification auxiliary agent, the initiator, ethanol and the organic thermosensitive dye is 12-15 g: 0.05 g: 20 mL: 6 g; The initiator is dibenzoyl peroxide.

10. The method for preparing a thermal printing ink according to claim 1, characterized in that: The following steps are involved: Step S1: preparing a durable coloring agent, specifically comprising the following steps A1-A4: Step A1: Pentaerythritol triallyl ether, chloroethyl isocyanate, dibutyltin dilaurate and ethanol are mixed and added, the temperature is raised to 40-50° C., and the mixture is stirred for reaction for 3-4 hours to obtain a carbamate intermediate; Step A2: taking a carbamate intermediate, 2,2,6,6-tetramethyl-4-piperidinol, sodium hydroxide and benzene, mixing them, heating them to 30-40° C., stirring and reacting for 1-2 hours to obtain a coating modification auxiliary agent; Step A3: Mix a fixed color forming agent, a fixed color developing agent and hexadecanol, heat to 60-70° C., stir for 20 minutes, and cool to room temperature to obtain an organic thermosensitive dye; Step A4: Mix the coating modification auxiliary agent, initiator and ethanol, stir for 0.5 hours to obtain a coating solution; then add the organic thermosensitive dye to the coating solution, stir for 20 minutes, and then compress it into tiny droplets, and then put it into a drying room for drying, and finally collect the durable colorant, and seal and store it in a cool and dry place for future use; Step S2: taking a durable colorant, a dispersant, a defoamer, an aqueous polyurethane emulsion, isopropyl alcohol, and an antioxidant in parts by weight, mixing and adding the mixture, dispersing the mixture in a disperser for 0.5-4 hours, and fully stirring and dispersing the mixture to obtain a thermal printing ink.

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