阅读说明：本技术 一种热敏染料微胶囊材料、制备方法及热敏涂料 (Thermosensitive dye microcapsule material, preparation method and thermosensitive coating ) 是由 莫斌 唐国初 于 2021-09-22 设计创作，主要内容包括：本申请提供一种热敏染料微胶囊材料、制备方法及热敏涂料,属于无墨打印技术领域。该材料包括：包括由囊壁和囊芯组成的微胶囊,所述囊芯包括热敏染料,所述微胶囊的D50范围为1微米至10微米且所述囊壁的厚度在0.2微米至1微米之间的分布均匀程度使所述微胶囊在110℃至120℃、120℃至130℃、130℃至140℃范围内融化的概率相差不超过5％。本发明还提供一种热敏染料微胶囊材料的制备方法及热敏涂料。本发明的热敏染料微胶囊材料,其囊壁的厚度分布均匀程度使所述微胶囊在各温度范围内融化的概率相差不超过5％,使得该热敏染料微胶囊材料在各个温度区域内均能够产生相近的融化概率时,可以有助于热敏打印机根据需要通过改变温度而改变打印出的图案的色阶。(The application provides a thermosensitive dye microcapsule material, a preparation method and a thermosensitive coating, and belongs to the technical field of inkless printing. The material comprises: comprising microcapsules consisting of a wall and a core, the core comprising a thermosensitive dye, the microcapsules having a D50 in the range of 1 to 10 microns and a wall thickness in the range of 0.2 to 1 micron distributed uniformly with a probability of melting of the microcapsules in the range of 110 to 120 ℃, 120 to 130 ℃, 130 to 140 ℃ differing by no more than 5%. The invention also provides a preparation method of the thermosensitive dye microcapsule material and a thermosensitive coating. According to the thermosensitive dye microcapsule material, the thickness distribution uniformity of the microcapsule wall enables the melting probability difference of the microcapsules in each temperature range to be not more than 5%, so that when the thermosensitive dye microcapsule material can generate similar melting probabilities in each temperature region, a thermosensitive printer can be facilitated to change the color gradation of printed patterns by changing the temperature according to needs.)

1. The heat-sensitive dye microcapsule material is characterized by comprising microcapsules consisting of a capsule core and a capsule wall, wherein the capsule core comprises a heat-sensitive dye, and the capsule wall comprises at least one of block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, polyethylene glycol dimethacrylate and polycaprolactam;

the microcapsules have a D50 of 1-10 microns and the wall thickness is distributed uniformly between 0.2-1 microns such that the probability of the microcapsules melting in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃, 130 ℃ to 140 ℃ does not differ by more than 5%.

2. A thermosensitive dye microcapsule material according to claim 1, wherein the D50 of the microcapsule is 5 to 6 μm.

3. A thermosensitive dye microcapsule material according to claim 1, wherein the thermosensitive dye comprises a red thermosensitive dye comprising a benzoate lactone compound and/or a violet lactone compound and a black thermosensitive dye comprising at least a fluoran compound.

4. A preparation method of a thermosensitive dye microcapsule material is characterized by comprising the following steps:

preparing oil phase raw materials: mixing 5-20 parts by mass of thermosensitive dye, 0.1-1 part by mass of initiator and 50-100 parts by mass of organic solvent to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 5-20 parts by mass of prepolymer, 70-90 parts by mass of water and 2-5 parts by mass of dispersant to obtain a water-phase raw material;

shearing and emulsifying: adding the water phase raw material into the oil phase raw material, shearing to obtain an emulsion, and standing until the D50 of the obtained microcapsule is 1-10 microns and the distribution uniformity of the capsule wall thickness is 0.2-1 microns ensures that the probability difference of the microcapsules melting in the ranges of 110-120 ℃, 120-130 ℃ and 130-140 ℃ is not more than 5%;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion until the reaction is completed, and then carrying out reduced pressure distillation to obtain the thermosensitive microcapsule material.

5. A method for preparing a thermosensitive dye microcapsule material according to claim 4, wherein the prepolymer is at least one selected from the group consisting of a block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, polyethylene glycol dimethacrylate, and polycaprolactam, and the dispersant is at least one selected from the group consisting of gum arabic, polyvinyl alcohol, span 20, and Tween 80.

6. The method for preparing a thermosensitive dye microcapsule material according to claim 4, wherein the shear rotation speed is not less than 8000rpm for not less than 1 hour.

7. The method for preparing a thermosensitive dye microcapsule material according to claim 4, wherein the thermosensitive dye comprises a red thermosensitive dye and a black thermosensitive dye, the red thermosensitive dye comprises a benzoic lactone compound and/or a violet lactone compound, the black thermosensitive dye comprises at least a fluoran compound, the organic solvent is butanone, and the initiator is azobisisobutyronitrile and/or diacyl peroxide.

8. The method for preparing a thermosensitive dye microcapsule material according to claim 4, wherein in the step of preparing the oil phase raw material, an anti-UV auxiliary agent is further added, and 5 to 20 parts by mass of the thermosensitive dye, 0.1 to 1 part by mass of the initiator, 50 to 100 parts by mass of the organic solvent, and 0.5 to 1 part by mass of the anti-UV auxiliary agent are mixed to obtain the oil phase raw material.

9. The method for preparing a thermosensitive dye microcapsule material according to claim 8, wherein the anti-UV aid is a benzotriazole-based anti-UV aid.

10. A heat-sensitive paint, characterized in that, it comprises 2-10 parts by mass of heat stabilizer, 1-3 parts by mass of lubricant, 5-10 parts by mass of dispersant, 2-20 parts by mass of color-developing agent and 20-80 parts by mass of heat-sensitive dye microcapsule material as claimed in any one of claims 1 to 3, the heat stabilizer is selected from phosphite ester and/or zinc stearate, the lubricant is selected from at least one of fatty acid amide, oleic acid and polyester compound, the color-developing agent is selected from bisphenol A and/or p-hydroxybenzoic acid, and the dispersant is selected from polysiloxane mixture.

Technical Field

The invention relates to the technical field of inkless printing, in particular to a thermosensitive dye microcapsule material, a preparation method and a thermosensitive coating.

Background

Inkless printing is a simple and convenient printing mode, and provides technical support for miniaturization and portability of the printer. In the prior art, the technical scheme of inkless printing is that a microcapsule wrapping a dye and an initiator initiating color development of the dye are mixed and coated on printing paper, and a printer heats the printing paper to melt the capsule wall of the microcapsule, so that the initiator permeates into the microcapsule and the dye develops color, and an image is displayed on the printing paper.

The heating printing mode is beneficial to simplifying the structure of the printer, and the printing paper can be kept for a long time after being developed, but the defect is that the printed image is actually composed of a plurality of color developing microcapsules, and the colors of the microcapsules are fixed and consistent once being developed, so that the printed image has uniform color and lacks of layering. Therefore, it is desirable to provide a new thermosensitive dye microcapsule material, a preparation method and a thermosensitive coating.

Disclosure of Invention

The invention aims to provide a thermosensitive dye microcapsule material, a preparation method and a thermosensitive coating, which can overcome the defects in the prior art at least partially.

The invention aims to provide a thermosensitive dye microcapsule material.

The technical scheme for solving the technical problems is as follows: a thermosensitive dye microcapsule material comprises a microcapsule consisting of a capsule core and a capsule wall, wherein the capsule core comprises a thermosensitive dye, and the capsule wall comprises at least one of block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, polyethylene glycol dimethacrylate and polycaprolactam; the microcapsules have a D50 of 1-10 microns and the wall thickness is distributed uniformly between 0.2-1 microns such that the probability of the microcapsules melting in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃, 130 ℃ to 140 ℃ does not differ by more than 5%.

The heat-sensitive dye microcapsule material has the beneficial effects that: when the thermosensitive dye microcapsule material can generate similar melting probability in each temperature area, the thermosensitive dye microcapsule material can help a thermosensitive printer to change the color gradation of printed patterns by changing the temperature according to needs.

On the basis of the technical scheme, the invention can be further improved as follows.

Further, the microcapsules have a D50 of 5-6 microns.

The adoption of the further beneficial effects is as follows: the median diameter of the microcapsule adopts the parameters, and a better color development effect can be generated between 110 ℃ and 140 ℃.

Further, the thermosensitive dye comprises a red thermosensitive dye and a black thermosensitive dye, the red thermosensitive dye comprises at least one of a benzoic acid lactone compound and a violet lactone compound, and the black thermosensitive dye at least comprises a fluoran compound.

The adoption of the further beneficial effects is as follows: meanwhile, the dye with red and black colors is included, so that the color development effect is better.

The second purpose of the invention is to provide a preparation method of the thermosensitive dye microcapsule material.

The technical scheme for solving the technical problems is as follows: a preparation method of a thermosensitive dye microcapsule material comprises the following steps:

preparing oil phase raw materials: mixing 5-20 parts by mass of thermosensitive dye, 0.1-1 part by mass of initiator and 50-100 parts by mass of organic solvent to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 5-20 parts by mass of prepolymer, 70-90 parts by mass of water and 2-5 parts by mass of dispersant to obtain a water-phase raw material;

shearing and emulsifying: adding the water phase raw material into the oil phase raw material, shearing to obtain an emulsion, and standing until the D50 of the obtained microcapsule is 1-10 microns and the distribution uniformity of the capsule wall thickness between 0.2 micron and 1 micron ensures that the probability difference of the microcapsule melting in the range of 110-120 ℃, 120-130 ℃ and 130-140 ℃ is not more than 5%;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion until the reaction is completed, and then carrying out reduced pressure distillation to obtain the thermosensitive microcapsule material.

The preparation method of the thermosensitive dye microcapsule material has the beneficial effects that: when the thermosensitive dye microcapsule material can generate similar melting probability in each temperature area, the thermosensitive dye microcapsule material can help a thermosensitive printer to change the color gradation of printed patterns by changing the temperature according to needs.

On the basis of the technical scheme, the invention can be further improved as follows.

Further, the prepolymer is selected from at least one of a block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, polyethylene glycol dimethacrylate and polycaprolactam, and the dispersant is selected from at least one of gum arabic, polyvinyl alcohol, span 20 and tween 80.

The adoption of the further beneficial effects is as follows: the thermosensitive dye microcapsule material with the capsule wall thickness meeting the requirement can be conveniently formed.

Further, the rotating speed of the shearing is more than or equal to 8000rpm, and the time is more than or equal to 1 hour.

The adoption of the further beneficial effects is as follows: can be convenient for forming the thermosensitive dye microcapsule material with the capsule wall thickness meeting the requirement.

Further, the thermal dye comprises a red thermal dye and a black thermal dye, the red thermal dye comprises a benzoic acid lactone compound and/or a violet lactone compound, the black thermal dye at least comprises a fluoran compound, the organic solvent is butanone, and the initiator is azobisisobutyronitrile and/or diacyl peroxide.

The adoption of the further beneficial effects is as follows: improve the color development effect and accelerate the polymerization reaction rate.

Further, in the step of preparing the oil phase raw material, an anti-UV auxiliary agent is added, and 5-20 parts by mass of the thermosensitive dye, 0.1-1 part by mass of the initiator, 50-100 parts by mass of the organic solvent and 0.5-1 part by mass of the anti-UV auxiliary agent are mixed to obtain the oil phase raw material.

The adoption of the further beneficial effects is as follows: the UV resistance of the prepared thermosensitive dye microcapsule material is improved.

Preferably, the anti-UV auxiliary agent is a benzotriazole anti-UV auxiliary agent.

The adoption of the further beneficial effects is as follows: further improving the UV resistance of the prepared thermosensitive dye microcapsule material.

The third purpose of the invention is to provide a heat-sensitive coating.

The technical scheme for solving the technical problems is as follows: a heat-sensitive coating comprises 2-10 parts by mass of a heat stabilizer, 1-3 parts by mass of a lubricant, 5-10 parts by mass of a dispersing agent, 2-20 parts by mass of a color developing agent and 20-80 parts by mass of the heat-sensitive dye microcapsule material, wherein the heat stabilizer is selected from at least one of phosphite ester and zinc stearate, the lubricant is selected from at least one of fatty acid amide, oleic acid and polyester compounds, the color developing agent is selected from at least one of bisphenol A and p-hydroxybenzoic acid, and the dispersing agent is selected from polysiloxane mixtures.

The heat-sensitive coating has the beneficial effects that: when the thermal sensitive coating can generate similar melting probability in each temperature area, the thermal sensitive coating can help a thermal printer to change the color gradation of printed patterns by changing the temperature according to needs.

According to the embodiment of the invention, when the thermosensitive dye microcapsule material with D50 ranging from 1 micron to 10 microns and the thickness of the capsule wall ranging from 0.2 micron to 1 micron is provided, the thickness distribution of the capsule wall is uniform, so that the probability of melting of the microcapsule in the ranges of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃ and 130 ℃ to 140 ℃ is different by no more than 5%, the thermosensitive dye microcapsule material can generate similar melting probability in each temperature region, and the thermosensitive dye microcapsule material can help a thermosensitive printer to change the color level of a printed pattern by changing the temperature as required.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a flow chart of the preparation of thermosensitive dye microcapsule material according to the embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. For convenience of description, only portions related to the invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The embodiment of the invention provides a thermosensitive dye microcapsule material, which comprises a microcapsule consisting of a microcapsule wall and a microcapsule core, wherein the microcapsule core comprises a thermosensitive dye, the microcapsule wall comprises at least one of block copolymers of polyethylene glycol dimethacrylate, polycaprolactam, poly-N-isopropylacrylamide and polyethylene glycol, the block copolymers can be only one of the block copolymers of the polyethylene glycol dimethacrylate, the polycaprolactam or the poly-N-isopropylacrylamide and the polyethylene glycol, or the block copolymers can be a mixture of two or three of the block copolymers, and preferably, the microcapsule wall consists of the block copolymers of the polyethylene glycol dimethacrylate, the polycaprolactam and the poly-N-isopropylacrylamide and the polyethylene glycol in a ratio of 1:1: 1.

The heat-sensitive dyes in the capsule core preferably comprise red heat-sensitive dyes and black heat-sensitive dyes respectively, so that the red heat-sensitive dyes can emit better red color when heated and printed, wherein the red heat-sensitive dyes are preferably at least one of benzoic acid lactone compounds such as o-hydroxymethylbenzoic acid lactone and crystal violet lactone or ultraviolet lactone compounds, the black heat-sensitive dyes are preferably fluorane, and can be 2-phenylamino-3-methyl-6-diethylamino-phenyl fluorane or the like, so that better color-emitting effect can be achieved.

In order to enable thermal printing paper composed of the thermal dye microcapsule material provided by the embodiments of the present application to show a better color gradation, in the thermal dye microcapsule material, D50 of the microcapsule ranges from 20 micrometers to 30 micrometers, and the thickness of the capsule wall of the microcapsule ranges from 1 micrometer to 2 micrometers and the probability of melting the above-mentioned microcapsule in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃, 130 ℃ to 140 ℃ differs by no more than 5%. The reason is that the working temperature range of the current thermal printer is mostly between 110 ℃ and 140 ℃, and the conventional printer does not consider adjusting the heating temperature to change the color level of the thermal printer paper due to the technical limitation of the thermal printer paper. The inventor of the present invention has found through experimental studies that if the wall material of the microcapsule is adjusted to be at least one of the block copolymers of polyethylene glycol dimethacrylate, polycaprolactam, poly-N-isopropylacrylamide and polyethylene glycol, and the microcapsule D50 is located between 1 micron and 10 microns, and the distribution uniformity of the wall thickness between 0.2 micron and 1 micron is such that the probability of melting of the microcapsule in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃, and 130 ℃ to 140 ℃ is not more than 5%, for example, the absolute uniform distribution of the wall thickness between 0.2 micron and 1 micron, or the substantially uniform distribution, such as the substantially uniform distribution of 24% distribution between 0.2 micron and 0.4 micron, 25% distribution between 0.4 micron and 0.6 micron, 25% distribution between 0.6 micron and 0.8 micron, 26% distribution between 0.8 micron and 1 micron, and the like, and when the similar melting probabilities can be generated in each temperature region, the thermal printer can be helped to change the color gradation of the printed pattern by changing the temperature according to the needs, for example, the heating temperature at the center of the pattern is higher, so that most microcapsules can color to reach a higher color gradation, and the lower heating temperature is used at the edge of the pattern, so that only a small amount of microcapsules can color, the obtained image has proper color gradation distribution, and the better display effect can be realized.

In a preferred embodiment, D50 of the microcapsule in the thermosensitive dye microcapsule material provided in the present application is 5 micrometers, and experimental studies show that when the particle size of the microcapsule is too small, the problem of color development by mistake at low temperature is easily caused, and when the particle size is too large, excessive color development is easily caused, and experimental studies show that when D50 of the microcapsule provided in the present application is 5 micrometers, the probability of achieving a good color development effect in each temperature range is high.

The thermosensitive dye microcapsule material provided by the embodiment of the invention can be prepared by a method comprising the following steps:

s101: preparing oil phase raw materials: mixing 5-20 parts by mass of thermosensitive dye, 0.1-1 part by mass of initiator and 50-100 parts by mass of organic solvent to obtain an oil phase raw material;

s102: preparing water-phase raw materials: mixing 5-20 mass of prepolymer, 70-90 mass of water and 2-5 mass parts of dispersant to obtain an aqueous phase raw material, wherein the prepolymer is at least one selected from polyethylene glycol dimethacrylate, polycaprolactam, poly N-isopropylacrylamide and a segmented copolymer of polyethylene glycol, and the dispersant is at least one selected from gum arabic, polyvinyl alcohol, span 20 and tween 80;

s103: shearing and emulsifying: adding the water phase raw material into the oil phase raw material, shearing to obtain emulsion, wherein the shearing rotation speed exceeds 8000rpm, the shearing treatment time exceeds 1 hour, and standing until the obtained microcapsule has D50 range of 1-10 microns and the uniform distribution degree of capsule wall thickness of 0.2-1 micron, so that the probability difference of the microcapsule melting in the ranges of 110-120 ℃, 120-130 ℃ and 130-140 ℃ is not more than 5%;

s104: and (3) reduced pressure distillation: and introducing nitrogen into the emulsion until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Hereinafter, each step will be described in detail.

In the above method, the oil phase raw material is mainly configured to dissolve the thermosensitive dye in the organic solvent, and the initiator is compounded, so that in the shearing process with the water phase raw material dissolved with the prepolymer, a polymer film can be formed on the surface of the oil phase raw material cut into small droplets, and the thermosensitive dye is wrapped in the polymer film to form a microcapsule structure. The organic solvent is preferably butanone, which provides sufficient solubility and viscosity and facilitates the subsequent distillation under reduced pressure. Of course, any organic solvent may be used as the organic solvent without particular limitation so long as it can be used as a medium for dissolution and distillation under reduced pressure. Specifically, the following substances may be used as the organic solvent: ester solvents such as methyl acetate, ethyl acetate, gamma-butyrolactone and epsilon-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; alcohols such as butanol, etc., are not specifically listed herein.

Correspondingly, the water phase raw material is mainly prepared for dissolving the material of the capsule wall of the microcapsule in the water phase, namely the prepolymer of at least one block copolymer selected from polyethylene glycol dimethacrylate, polycaprolactam, poly-N-isopropylacrylamide and polyethylene glycol, in the embodiment of the application, at least one dispersing agent selected from gum arabic, polyvinyl alcohol, span 20 and tween 80 is added, and the mass ratio of the prepolymer, deionized water and the dispersing agent is respectively 5-20, 70-90 and 2-5, so that a transparent polymer can be formed. Preferably, the mixture may be stirred under heating to accelerate the rate of dissolution.

In the step of shear emulsification, the oil phase raw material is added into the water phase raw material, the shear emulsification is carried out at a speed of more than 8000rpm (preferably 10000 to 20000rpm), the treatment time of the shear emulsification is more than 1 hour (preferably 1.5 to 2 hours), then the standing is carried out, the standing time is preferably 0.5 to 1 hour, until the D50 of the microcapsule ranges from 1 micron to 10 microns and the distribution uniformity of the capsule wall thickness ranges from 0.2 micron to 1 micron enables the probability of the microcapsule melting in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃ and 130 ℃ to 140 ℃ to be different by no more than 5%. The purpose of the rest was to allow the droplets formed by the partial shearing to repolymerize while allowing the prepolymer in the aqueous phase to react sufficiently to obtain the desired D50 and a broader wall thickness distribution range.

The technical scheme that this application provided and the technical scheme of current preparation microcapsule main difference lie in, increased the step of stewing, cut in the prior art scheme and expect to obtain the microcapsule that distributes comparatively evenly, and this application sets up the step of stewing in order to solve the problem that microcapsule color development lacks the color gradation, utilizes the oil phase liquid drop to have the tendency of repolymerization in aqueous phase, makes the little drop that part was cut to form repolymerize through stewing to make the prepolymer in aqueous phase can fully react, obtain broad and even cyst wall thickness distribution range.

In the reduced pressure distillation step, the temperature of the emulsion can be controlled to be 40 ℃ to 60 ℃, so that the capsule wall of the microcapsule is not damaged while the reduced pressure distillation speed is accelerated.

Preferably, in the step of preparing the oil phase raw material, the initiator is at least one of azobisisobutyronitrile or diacyl peroxide corresponding to the water phase raw material. Since the prepolymer used in the present application includes at least one of polyethylene glycol dimethacrylate, polycaprolactam, poly-N-isopropylacrylamide and a block copolymer of polyethylene glycol, the above-mentioned prepolymer can be more efficiently initiated to be polymerized using azobisisobutyronitrile or diacyl peroxide as an initiator.

Preferably, in the step of preparing the oil phase raw material, an anti-UV auxiliary agent is further added, and 5-20 parts by mass of the thermosensitive dye, 0.1-1 part by mass of the initiator, 50-100 parts by mass of the organic solvent and 0.5-1 part by mass of the anti-UV auxiliary agent are mixed to obtain the oil phase raw material. The anti-UV auxiliary agent can be selected from one or a mixture of a BASF ultraviolet absorbent and a brand of tinuvin460 and tinuvin 152. The anti-UV auxiliary agent can be other anti-UV auxiliary agents such as UV-77, UV531 and UV-1130, and the probability of the thermal sensitive dye microcapsule provided by the application being denatured by illumination can be reduced after the anti-UV auxiliary agent is added.

The embodiment of the application also provides a heat-sensitive coating, which comprises 2-10 parts by mass of a heat stabilizer, 1-3 parts by mass of a lubricant, 5-10 parts by mass of a dispersing agent, 2-20 parts by mass of a color developing agent and 20-80 parts by mass of the heat-sensitive dye microcapsule material, wherein the heat stabilizer is selected from at least one of phosphite ester and zinc stearate, the lubricant is selected from at least one of fatty acid amide, oleic acid and polyester compounds, the color developing agent is selected from at least one of bisphenol A and p-hydroxybenzoic acid, and the dispersing agent is selected from a polysiloxane mixture and preferably can be at least one of BYK019 or BYK 2102. The mixing mass ratio of the heat stabilizer, the lubricant, the dispersant, the color developing agent and the thermosensitive dye microcapsule material can be 2: 1: 5: 1: 20, may be 10: 3: 10: 20: 80, etc. in other proportions. The preparation method of the heat-sensitive coating can be that a heat stabilizer, a lubricant, a dispersant and a color developing agent are mixed with the heat-sensitive dye microcapsule material and stirred uniformly, and the heat-sensitive coating can be used for preparing heat-sensitive printing paper by means of coating.

The following are specific examples of the method for preparing a heat-sensitive coating provided herein. The starting materials referred to in the following examples and comparative examples were all in analytical purity unless otherwise specified.

Example 1:

a method of preparing a heat-sensitive coating, comprising the steps of:

preparing oil phase raw materials: mixing 5 parts by mass of o-hydroxymethylbenzoic acid lactone, 0.1 part by mass of azobisisobutyronitrile and 50 parts by mass of butanone, heating to 50 ℃, and stirring for no less than 25min until the mixture is uniformly stirred to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 5 parts by mass of a 1:1:1 mixture of polyethylene glycol dimethacrylate, polycaprolactam and a block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, 70 parts by mass of deionized water and 2 parts by mass of polyvinyl alcohol in an aqueous phase raw material;

shearing and emulsifying: adding the water-phase raw material into the oil-phase raw material, shearing the mixture of the oil-phase raw material and the water-phase raw material by using a high-speed shearing machine of Shanghai HR500, wherein the shearing rotation speed is 10000rpm, the shearing treatment time is 1.5 hours, and then standing for 30 minutes;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion obtained by shearing and emulsifying until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Mixing the coating: mixing 2 parts by mass of phosphite ester, 1 part by mass of fatty acid amide, 5 parts by mass of BYK019, 2 parts by mass of bisphenol A and 20 parts by mass of a thermosensitive dye microcapsule material to obtain the thermosensitive coating.

Example 2:

preparing oil phase raw materials: mixing 7 parts by mass of crystal violet lactone, 0.5 part by mass of azobisisobutyronitrile and 50 parts by mass of butanone, heating to 50 ℃, and stirring for not less than 25min until the mixture is uniformly stirred to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 10 parts by mass of a 1:1 mixture of polyethylene glycol dimethacrylate and polycaprolactam, 70 parts by mass of deionized water and 4 parts by mass of polyvinyl alcohol in an aqueous phase raw material;

shearing and emulsifying: adding the water-phase raw material into the oil-phase raw material, shearing the mixture of the oil-phase raw material and the water-phase raw material by using a high-speed shearing machine of Shanghai HR500, wherein the shearing rotation speed is 10000rpm, the shearing treatment time is 1.5 hours, and then standing for 30 minutes;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion obtained by shearing and emulsifying until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Mixing the coating: 4 parts by mass of zinc stearate, 2 parts by mass of oleic acid, 6 parts by mass of BYK2102, 4 parts by mass of p-hydroxybenzoic acid and 30 parts by mass of a thermosensitive dye microcapsule material were mixed to obtain a thermosensitive paint.

Example 3:

preparing oil phase raw materials: mixing 15 parts by mass of o-hydroxymethylbenzoic acid lactone, 0.6 part by mass of azobisisobutyronitrile and 100 parts by mass of butanone, heating to 60 ℃, and stirring for no less than 25min until the mixture is uniformly stirred to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 20 parts by mass of polyethylene glycol dimethacrylate, 70 parts by mass of deionized water and 5 parts by mass of polyvinyl alcohol in a water phase raw material;

shearing and emulsifying: adding the water-phase raw material into the oil-phase raw material, shearing the mixture of the oil-phase raw material and the water-phase raw material by using a high-speed shearing machine of Shanghai Han Dynasty HR500, wherein the shearing speed is 15000rpm, the shearing treatment time is 2 hours, and then standing for 1 hour;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion obtained by shearing and emulsifying until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Mixing the coating: mixing 10 parts by mass of zinc stearate, 3 parts by mass of oleic acid, 10 parts by mass of BYK2102, 20 parts by mass of p-hydroxybenzoic acid and 80 parts by mass of a thermosensitive dye microcapsule material to obtain a thermosensitive paint.

Example 4:

preparing oil phase raw materials: mixing 10 parts by mass of o-hydroxymethylbenzoic acid lactone, 0.7 part by mass of azobisisobutyronitrile, 100 parts by mass of butanone and 0.5 part by mass of tinuvin460, heating to 50 ℃, and stirring for no less than 25min until the mixture is uniformly stirred to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 20 parts by mass of a 1:1:1 mixture of polyethylene glycol dimethacrylate, polycaprolactam and a block copolymer of poly-N-isopropylacrylamide and polyethylene glycol, 90 parts by mass of deionized water and 5 parts by mass of polyvinyl alcohol in an aqueous phase raw material;

shearing and emulsifying: adding the water-phase raw material into the oil-phase raw material, shearing the mixture of the oil-phase raw material and the water-phase raw material by using a high-speed shearing machine of Shanghai HR500, wherein the shearing rotation speed is 8000rpm, the shearing treatment time is 1.5 hours, and then standing for 1 hour;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion obtained by shearing and emulsifying until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Mixing the coating: 8 parts by mass of zinc stearate, 2 parts by mass of fatty acid amide, 6 parts by mass of BYK2102, 16 parts by mass of p-hydroxybenzoic acid and 60 parts by mass of a thermosensitive dye microcapsule material were mixed to obtain a thermosensitive paint.

Example 5:

preparing oil phase raw materials: mixing 20 parts by mass of 2-phenylamino-3-methyl-6-diethylamino-fluorane, 0.7 part by mass of azobisisobutyronitrile, 100 parts by mass of butanone and 0.5 part by mass of tinuvin152, heating to 50 ℃, and stirring for no less than 25min until the mixture is uniformly stirred to obtain an oil phase raw material;

preparing water-phase raw materials: mixing 10 parts by mass of a 1:1 mixture of polyethylene glycol dimethacrylate and polycaprolactam, 90 parts by mass of deionized water and 5 parts by mass of polyvinyl alcohol in an aqueous phase raw material;

shearing and emulsifying: adding the water-phase raw material into the oil-phase raw material, shearing the mixture of the oil-phase raw material and the water-phase raw material by using a high-speed shearing machine of Shanghai HR500, wherein the shearing rotation speed is 8000rpm, the shearing treatment time is 1.5 hours, and then standing for 0.5 hour;

and (3) reduced pressure distillation: and introducing nitrogen into the emulsion obtained by shearing and emulsifying until the reaction is completed, and then carrying out reduced pressure distillation to obtain the heat-sensitive microcapsule material.

Mixing the coating: 8 parts by mass of zinc stearate, 2 parts by mass of fatty acid amide, 6 parts by mass of BYK2102, 16 parts by mass of p-hydroxybenzoic acid and 60 parts by mass of a thermosensitive dye microcapsule material were mixed to obtain a thermosensitive paint.

Comparative example 1:

this comparative example is different from example 1 in that the post-shearing treatment for 30 minutes of standing was not conducted, and the rest was the same.

Comparative example 2:

this comparative example was different from example 1 in the shearing treatment time and the treatment after shearing without leaving it for 30 minutes, and the rest was the same.

Experimental example:

the heat-sensitive paints prepared in examples 1 to 5 and comparative examples 1 to 2 were applied to the positive side of a printing paper, respectively, at a coating thickness XX, and sufficiently dried, and 4 areas, respectively numbered 1 to 4, were circled on the printing paper. The zones 1 to 4 were heated for 5 microseconds using 105 deg.C, 125 deg.C, 135 deg.C, 145 deg.C, respectively. The chromaticity in the region 1 to the region 4 was measured using a YT-ACM colorimeter manufactured by Hangzhou research science and technology Co., Ltd, and the results thereof are shown in the following table:

	region 1 chroma	Region 2 chroma	Region 3 chroma	Region 4 chroma
					Experimental example 1	40.1	78.2	117.5	157.2
Experimental example 2	51.2	99.8	149.8	201.1
					Experimental example 3	55.4	108.1	162.3	218.1
Experimental example 4	45.3	88.2	132.8	178.3
					Experimental example 5	48.2	93.7	141.6	189.4
Comparative example 1	41.5	132.2	143.5	149.2
					Comparative example 2	61.2	189.2	195.3	210.5

From the experimental results, it was confirmed that the chromaticity increase widths of the regions 1 to 4 in the experimental examples 1 to 5 were all around 25%, and the difference from each other was not more than 5%, and therefore, it was confirmed that the probability of melting the microcapsules in the range of 110 ℃ to 120 ℃, 120 ℃ to 130 ℃, and 130 ℃ to 140 ℃ in each region was not more than 5%. In comparative example 1-2, the chromaticity increase range from region 1 to region 2 was about 300% to 350%, the chromaticity increase range from region 2 to region 3 was about 10%, and the chromaticity increase range from region 3 to region 4 was about 5%, which are very different. It was thus confirmed that the thermal sensitive paints manufactured in experimental examples 1 to 5 had better temperature responsiveness in printing and could develop more abundant color levels than in comparative examples 1 to 2.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the invention herein disclosed is not limited to the particular combination of features described above, but also encompasses other arrangements formed by any combination of the above features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.