Environment-friendly thermosensitive recording material

文档序号：579269 发布日期：2021-05-25 浏览：40次中文

阅读说明：本技术 一种环保型热敏记录材料 (Environment-friendly thermosensitive recording material ) 是由吴宗泽朱志广王彦辉黄海水赵亮翟清华王晓玲白楠于 2020-12-29 设计创作，主要内容包括：一种环保型热敏记录材料,由上往下依次包括保护层、热敏成像层、支持体和背层；所述热敏成像层包括热敏染料微胶囊,所述热敏染料微胶囊包括囊壁和囊芯,所述囊芯包括热敏染料、助剂、溶剂；所述溶剂选自高沸点溶剂；所述微胶囊制备过程中染料溶解温度为85-100℃；所述囊壁由含有异氰酸酯基的高聚物和有机胺进行缩聚反应制备得到。本发明使用高沸点溶剂,具有较好的环保性；囊壁由末端为异氰酸酯基的聚氨酯与有机胺经缩聚反应得到,该反应速度快、稳定可控,极大地提高了生产效率；同时微胶囊具有较小的粒径,能够提高热敏记录材料的热响应灵敏度。(An environment-friendly thermosensitive recording material comprises a protective layer, a thermosensitive imaging layer, a support and a back layer from top to bottom in sequence; the thermosensitive imaging layer comprises thermosensitive dye microcapsules, the thermosensitive dye microcapsules comprise capsule walls and capsule cores, and the capsule cores comprise thermosensitive dyes, auxiliaries and solvents; the solvent is selected from high boiling point solvents; the dye dissolution temperature in the microcapsule preparation process is 85-100 ℃; the capsule wall is prepared by the polycondensation reaction of high polymer containing isocyanate group and organic amine. The invention uses the high boiling point solvent, and has better environmental protection; the capsule wall is obtained by the polycondensation reaction of polyurethane with isocyanate group at the tail end and organic amine, the reaction speed is high, stable and controllable, and the production efficiency is greatly improved; meanwhile, the microcapsule has smaller particle size, and can improve the thermal response sensitivity of the thermosensitive recording material.)

1. An environment-friendly thermosensitive recording material comprises a protective layer, a thermosensitive imaging layer, a support and a back layer from top to bottom in sequence; the thermosensitive imaging layer comprises thermosensitive dye microcapsules, and the thermosensitive dye microcapsules comprise capsule walls and capsule cores, and are characterized in that the capsule cores comprise thermosensitive dyes, auxiliaries and solvents; the solvent is selected from high boiling point solvents; the dye dissolution temperature in the microcapsule preparation process is 85-100 ℃;

the capsule wall is prepared by carrying out polycondensation reaction on high polymer containing isocyanate groups and organic amine; the high polymer containing isocyanate groups is polyurethane with isocyanate groups at the ends; the organic amine comprises one or more of tetraethylenepentamine, triethylene diamine and diethylenetriamine.

2. The environment-friendly thermosensitive recording material according to claim 1, wherein the average particle diameter of the thermosensitive dye microcapsule is 0.35 to 0.80 μm.

3. The environment-friendly thermosensitive recording material according to claim 1, wherein the mass ratio of the dye to the high-boiling solvent is 1:0.6 to 1.2; the mass ratio of the auxiliary agent to the high-boiling-point solvent is 2-10: 100.

4. The environment-friendly thermosensitive recording material according to claim 3, wherein the high-boiling solvent has a boiling point of 125 to 290 ℃ under normal atmospheric pressure.

5. The environment-friendly thermosensitive recording material according to claim 1, wherein the temperature of the polycondensation reaction is 30 to 70 ℃.

6. The environment-friendly thermosensitive recording material according to claim 1 or 5, wherein the time of the polycondensation reaction is 15 to 80 min.

Technical Field

The invention relates to the field of recording materials, in particular to an environment-friendly thermosensitive recording material.

Background

The traditional information recording uses silver salt information recording material as main carrier, the silver salt information recording material is a high-efficiency information recording material, it integrates information receiving, storing and reproducing into one body, its image resolution is high, and the device for implementing information recording is simple. However, the silver salt information recording material uses precious metal silver as a raw material, the production process is complex, a large amount of waste water containing heavy metal is generated in the production and use processes, the environment is polluted, the technical conditions required in the treatment and transmission are harsh, and the silver salt information recording material is not suitable for the requirements of social development.

As technology has advanced, heat-sensitive recording materials have been gradually replacing conventional information recording materials, which mainly utilize an electron-donating leuco dye and a color developer of an electron-accepting compound to chemically react in a high-temperature molten state to form a recorded image. The thermosensitive recording material has obvious advantages compared with the traditional information recording material, but the traditional thermosensitive recording material adopts a composite solvent with high and low boiling points for dissolving fuel, and inevitably generates waste gas in the preparation process to influence the environment.

For example, chinese patents CN200510012744.6 and CN200610012671.5 disclose thermosensitive recording materials, in which a thermosensitive dye microcapsule uses a complex solvent with high and low boiling points to dissolve dye during the preparation process, and the mass percentage of the solvent with low boiling point in the complex solvent is large. Meanwhile, chinese patent CN201680026937.3 discloses a thermosensitive recording material and a preparation method thereof, which uses only low-boiling ethyl acetate as a solvent in the preparation process of thermosensitive dye microcapsules. The low boiling point solvent inevitably volatilizes into the air in the process of preparing the existing thermosensitive recording material, and the environment is influenced.

In order to solve the problem of solvent volatilization during dye dissolution, chinese patents CN03821751.1, CN200680030942.8 and CN200880010634.8 disclose thermal recording materials, which do not use a solvent during the preparation of the thermal recording material and directly heat the dye to 150 ℃ for dissolution in order to avoid volatilization of the low boiling point solvent. Therefore, the problem of solvent volatilization can be avoided, but potential safety hazards exist under the operation of a high-temperature environment, and meanwhile, the requirement on equipment is high. In addition, the average particle size of the prepared thermosensitive dye microcapsule is large (0.8-1.0 μm), so that the thermal response sensitivity of the thermosensitive recording material is low, and the widening of the application field of the thermosensitive recording material is greatly limited. In addition, in the preparation of the microcapsules described in the above patent documents, the reaction time of the single wall is as long as 3-10 hours, which severely restricts the improvement of the production efficiency.

Disclosure of Invention

In view of this, the present invention provides an environment-friendly thermosensitive recording material, in which the thermosensitive dye microcapsule dissolves dye with a high-boiling point solvent, thereby avoiding volatilization of the solvent during preparation and having good environmental protection; the polyurethane with the isocyanate group at the tail end is utilized to react with the organic amine, so that the reaction speed is high, the reaction process is stable and controllable, and the production efficiency is greatly improved; meanwhile, the thermosensitive dye microcapsule has a small particle size, and can be applied to thermosensitive recording materials to improve the thermal response sensitivity of the thermosensitive recording materials.

The purpose of the invention is realized by the following technical scheme.

An environment-friendly thermosensitive recording material comprises a protective layer, a thermosensitive imaging layer, a support and a back layer from top to bottom in sequence; the thermosensitive imaging layer comprises thermosensitive dye microcapsules, the thermosensitive dye microcapsules comprise capsule walls and capsule cores, and the capsule cores comprise thermosensitive dyes, auxiliaries and solvents; the solvent is selected from high boiling point solvents; the dye dissolution temperature in the microcapsule preparation process is 85-100 ℃;

In the environment-friendly thermosensitive recording material, the average particle size of the thermosensitive dye microcapsule is 0.35-0.80 μm.

The mass ratio of the dye to the high-boiling-point solvent is 1: 0.6-1.2; the mass ratio of the auxiliary agent to the high-boiling-point solvent is 2-10: 100.

In the environment-friendly thermosensitive recording material, the boiling point of the high-boiling-point solvent is 125-290 ℃ under the standard atmospheric pressure.

In the environment-friendly thermosensitive recording material, the temperature of the polycondensation reaction is 30-70 ℃.

In the environment-friendly thermosensitive recording material, the polycondensation reaction time is 15-80 min.

Advantageous effects

The thermosensitive dye microcapsule provided by the invention dissolves dye by using a high-boiling-point solvent, avoids volatilization of the solvent in the preparation process, and has better environmental protection property; the polyurethane with the terminal isocyanate group is adopted to react with organic amine, so that the reaction speed is high, the reaction process is stable and controllable, and the production efficiency is greatly improved. Meanwhile, the thermosensitive dye microcapsule has smaller particle size, and can improve the thermal response sensitivity of the thermosensitive recording material when being applied to the thermosensitive recording material.

Detailed Description

The thermosensitive recording material comprises a protective layer, a thermosensitive imaging layer, a support and a back layer from top to bottom in sequence; the thermosensitive imaging layer comprises thermosensitive dye microcapsules, the thermosensitive dye microcapsules comprise capsule walls and capsule cores, and the capsule cores comprise thermosensitive dyes, auxiliaries and solvents; the solvent is not a low boiling point solvent; the dye dissolution temperature in the microcapsule preparation process is 85-100 ℃.

In the present invention, the dye is preferably a fluoran-type dye, a triarylmethane-type dye, or a spiro compound-type dye; the fluoran-type dye is preferably 2-phenylamino-3-methyl-6-diethylaminofluoran, 2-phenylamino-3-methyl-6-dibutylaminofluoran, 2- (2-4-dimethylanilino) -3-methyl-6-diethylaminofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-cyclopentylamino) -6-methyl-7-anilinofluoran, 2-phenylamino-3-methyl-6-diethylaminofluoran, 2-diethylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclopentylamino) -6-methyl-7-anilinofluoran, 3-dibutylamino-7-o-fluoroanilino fluoran or 3-diethylamino-7- (3, 4-dichloroanilino) fluoran, more preferably 2-phenylamino-3-methyl-6-diethylaminofluoran.

In the present invention, the auxiliary preferably includes a sensitizer and/or an ultraviolet absorber. In the present invention, the sensitizer is mainly used for improving the image density and the heat sensitivity of the recording material, and is preferably bis-ethane, 2-benzylnaphthyl ether, 1, 2-bis- (3-phenoxy) ethane, 4-benzylbiphenyl or benzyl paraben. In the present invention, the ultraviolet absorber mainly functions to improve the light stability of the thermosensitive recording material, and the ultraviolet absorber is preferably UV8515, UV384-2 or UV-1577. In the present invention, the adjuvant may be included as a component of the core.

In the invention, the boiling point of the high-boiling-point solvent at the standard atmospheric pressure is preferably 125-290 ℃; the high boiling point solvent is preferably one or more of tributyl phosphate, dicyclohexyl phthalate, butyl acetate, chlorobenzene, xylene, m-xylene, o-xylene, N-dimethylformamide, cyclohexanone, N-dimethylacetamide, ethylene glycol, N-dimethylaniline, 2-4-di-t-amyl-phenol, dibutyl phthalate, ethylene glycol carbonate, acetamide, xylene phosphate, tricresyl phosphate, alkylbiphenyl and ethyl acetoacetate, and more preferably one or more of tricresyl phosphate, ethyl acetoacetate and butyl acetate. The invention requires a solvent with a higher boiling point, and can avoid the volatilization of the solvent in the preparation process, thereby improving the environmental protection property.

In the invention, the mass ratio of the dye to the high-boiling point solvent is preferably 1: 0.6-1.2, and more preferably 1: 0.8-1; the dye dissolution effect is poor due to the fact that the dosage of the high-boiling-point organic solvent is too small, the cost is increased due to the fact that the dosage of the high-boiling-point organic solvent is too large, and the storage stability of the prepared microcapsule emulsion is poor due to the fact that the dosage of the high-boiling-point organic solvent is too large. The amount of the auxiliary is not particularly limited, and the purpose of the present invention is not affected after the addition.

In the invention, the capsule wall is prepared by condensation polymerization of polyurethane with isocyanate group at the end and organic amine. In the present invention, the isocyanate group-terminated polyurethane is preferably XD-1580N polyurethane available from Hangzhou treasure light processing chemical Co., Ltd, and has a viscosity (25 ℃) of 8 mPas and an isocyanate content of 37 to 47% in the polyurethane.

In the present invention, the organic amine is selected from one or more of tetraethylenepentamine, triethylene diamine and diethylene triamine, and preferably tetraethylenepentamine.

The mass ratio of the polyurethane with the isocyanate group at the tail end to the organic amine is 2.25-3: 1, preferably 2.5-2.75: 1. Too little organic amine can lead to the formation of microcapsules with thin capsule wall and poor storage stability; excessive organic amine usage can result in microcapsule wall thickness and reduced color development ability during use.

In the invention, the temperature of the polycondensation reaction is preferably 30-70 ℃, and more preferably 45-55 ℃; the time of the polycondensation reaction is preferably 15-80 min, and more preferably 40-60 min. If the polycondensation reaction temperature is too low, the reactivity of the isocyanate group-terminated polyurethane with the organic amine is lowered, and the reaction time is prolonged. The excessive high temperature of the polycondensation reaction can lead to the high reactivity of the polyurethane with the terminal isocyanate group and the organic amine, and the reaction process is not controlled.

The invention can wrap the capsule core material in the capsule wall to form the thermosensitive dye microcapsule while carrying out polycondensation reaction to generate the capsule wall. In the invention, the preparation method of the thermosensitive dye microcapsule comprises the following steps:

carrying out first mixing on a polyvinyl alcohol aqueous solution and an emulsifier to obtain a water phase;

secondly, mixing the dye, the solvent, the auxiliary agent and polyurethane with isocyanate groups at the tail ends to obtain an oil phase;

and slowly adding the oil phase into the water phase stirred at a high speed to form an oil-in-water dispersion, and carrying out third mixing on the oil-in-water dispersion and the organic amine to obtain the thermosensitive dye microcapsule dispersion.

According to the invention, a polyvinyl alcohol aqueous solution and an emulsifier are subjected to first mixing to obtain a water phase. In the present invention, the emulsifier is preferably dodecyl dimethyl aminoethylenolide, p-isooctyl phenol polyoxyethylene ether or 7# (Lecay group Co., Ltd., China), preferably 7 #; the polyvinyl alcohol is preferably PVA-217, PVA-220 or PVA224 from Coly corporation of Japan, and more preferably PVA-224. In the present invention, the first mixing preferably employs an anchor stirrer; the rotation speed of the anchor stirrer is preferably 300r/min, and the time of the first mixing is not particularly limited in the present invention as long as the mixing is uniform.

The method comprises the step of mixing the dye, the high-boiling-point solvent, the auxiliary agent and the polyurethane with the tail end being isocyanate group for the second time to obtain the oil phase. In the invention, the temperature of the second mixing is preferably 85-100 ℃, and more preferably 90-98 ℃.

After the water phase and the oil phase are obtained, the oil phase is slowly added into the water phase which is stirred at a high speed to form oil-in-water dispersion, and then the oil-in-water dispersion and the organic amine are subjected to third mixing to obtain the thermosensitive dye microcapsule dispersion. In the invention, the high-speed stirring is carried out by using a high-speed shearing machine.

In the invention, the rotating speed of the high-speed stirring is preferably 8000-10000 r/min, more preferably 8500-9000 r/min; the time is preferably 8 to 15min, and more preferably 10 to 12 min. In the invention, the temperature for mixing the third mixture is preferably 30-70 ℃, and more preferably 45-55 ℃; the time is preferably 15 to 80min, and more preferably 40 to 60 min. In the invention, the third mixing is preferably carried out by using an anchor stirrer, and the stirring speed of the anchor stirrer is 450 r/min.

Under the mixing condition, the thermosensitive dye microcapsule with the average grain diameter of 0.35-0.80 μm can be obtained.

The thermosensitive recording material comprises a protective layer, a thermosensitive imaging layer, a support and a waterproof back layer from top to bottom in sequence; the thermosensitive imaging layer is obtained by physically mixing thermosensitive dye microcapsule dispersion liquid, developer dispersion liquid and auxiliary reagent and then coating.

The main components of the protective layer of the invention are various additives and adhesives. In the present invention, the binder is a water-soluble polymer resin, and may be a fully alcoholyzed, an intermediate alcoholyzed, a partially alcoholyzed or modified polyvinyl alcohol. The various auxiliary agents comprise a cross-linking agent, a lubricating agent, an ultraviolet absorbent, a flatting agent, a surfactant, an antistatic agent and the like. The crosslinking agent should be capable of forming a crosslinking reaction with the polyvinyl alcohol described above, such as: paraformaldehyde compounds such as glyoxal, glutaraldehyde; silane coupling agents, water-soluble primary polycondensates such as boric acid, borax, urea-formaldehyde, etc., layered silicates, nano-dioxides, nano-calcium carbonate, etc.; the lubricant comprises higher fatty acid or its metal salt, higher fatty acid amide, higher fatty acid ester, animal wax, vegetable wax or polyethylene wax; the leveling agent comprises silicone oil, polydimethylsiloxane, polyether polyester modified organic siloxane, alkyl modified organic siloxane, end group modified organic silicon or fluorine modified acrylic resin; the surfactant comprises alkali metal salt of sulfosuccinic acid, fluorine-containing surfactant or sulfonate; the ultraviolet absorbing agent and the antistatic agent are not particularly limited herein. Mixing various required additives and adhesives, and then extruding and coating by utilizing a slide flow to finally form a protective layer.

The thermosensitive imaging layer is obtained by uniformly mixing and coating thermosensitive dye microcapsule dispersion liquid, developer dispersion liquid and auxiliary reagent. In the present invention, the developer is selected from 3, 3-diallyl-4, 4-dihydroxydiphenyl sulfone, 4-dihydroxydiphenyl sulfone or 4-hydroxy-4-isopropoxydiphenyl sulfone, preferably 4-hydroxy-4-isopropoxydiphenyl sulfone. In the present invention, the auxiliary agents are a binder and a surfactant. The adhesive comprises starch and derivatives thereof, carboxylic styrene-butadiene latex, polyvinyl alcohol and the like, and preferably the carboxylic styrene-butadiene latex provided by Nissan chemical industry Co., Ltd has the solid content of 50 +/-2%, the pH value of 7.0-9.0 and the viscosity (25 ℃) of less than or equal to 200mPa. The surfactant is not particularly limited in the present invention as long as it satisfies the absence of nonwetting points during coating, and a fluorinated surfactant is preferred.

The thermosensitive recording material provided by the invention comprises a support, and the support used as the thermosensitive recording material has the advantages of good thermal stability, no deformation and stretching when being heated, small hygroscopicity and high flatness. In the present invention, the support includes a polyethylene film (PE) transparent support, a polypropylene film (PP) transparent support, a polyvinyl chloride film (PVC) transparent support, a polyester film (PET) transparent support, a polystyrene film (PS) transparent support, or a polyvinylidene chloride film (PVDC) transparent support, and master batches may be added thereto to form different colorations. In the invention, the thickness of the support body is preferably 80-300 μm, and more preferably 175 μm; the black-and-white density is preferably 0.16 to 0.24, more preferably 0.20, as measured by a densitometer type X-Rite 310T.

In the invention, the two surfaces of the support comprise bottom layers which are water-soluble environment-friendly resin layers and mainly have the function of endowing the surface of the support with hydrophilicity so as to ensure that other thermosensitive imaging layers and back layers can be coated smoothly.

The thermosensitive recording material of the present invention further comprises a back layer, and the main component of the back layer is one or both of an aqueous polyurethane emulsion and an aqueous acrylic resin. The primary function of the backing layer is to impart a certain roughness to the surface of the support. Therefore, a dispersion of polymethyl methacrylate may be further added to the back layer coating liquid to improve the roughness of the back layer.

The preparation method of the thermosensitive recording material comprises the following steps:

coating a backing layer on either surface of the support;

and coating a thermosensitive imaging layer and a protective layer on the other surface of the support in sequence.

The technical solutions of the present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following examples, "parts" means "parts by mass", and the value of the average particle diameter is measured by a malvern laser particle size meter.

Example 1

Preparation of thermosensitive recording Material

Preparation of heat-sensitive dye microcapsule dispersion liquid

1. Preparation of thermosensitive dye microcapsule dispersion liquid A

10 parts of ODB-2 (Shandong Ruikang essence Co., Ltd.), 5g of GN-2 (Tokyo chemical Co., Ltd., Japan), 9 parts of ethyl acetoacetate (boiling point: 180.8 ℃ C. under standard atmospheric pressure), and 15g of isocyanate group-terminated polyurethane (product model XD-1580N) were dissolved by heating at 95 ℃ to obtain an oil phase.