Fluorescent microcapsule and preparation method thereof

Abstract

The invention discloses a fluorescent microcapsule and a preparation method thereof, a polyethylene glycol olefin derivative is used as a wall material of a capsule wall, an oily solvent is used as a core material of a capsule core, an oil-soluble fluorescent dye and an additive are dissolved in the oily solvent, and the additive is an ionic surfactant capable of performing molecular interaction with the oil-soluble fluorescent dye. The fluorescent microcapsule disclosed by the invention has a pressure-sensitive characteristic, is colorless at ordinary times, and displays a specific fluorescent color under the irradiation of an ultraviolet lamp, and when the microcapsule is crushed by external force, the oil-soluble fluorescent dye flows out along with the oily solvent, so that the stress area is subjected to color development, and the copying of invisible handwriting is realized.

Description

Technical Field

[0001] The invention relates to the technical field of microcapsules, and in particular to a fluorescent microcapsule and a preparation method thereof. Background Art

[0002] Fluorescent microcapsules are nanoparticles with a shell-core structure. The encapsulated material is called the capsule core, and the material encapsulating the surface of the capsule core is called the capsule wall. It can show fluorescent color under ultraviolet light and can be applied to traditional carbonless copy paper.

[0003] Carbonless copy paper is a pressure-sensitive paper that is made by coating a coating with a copying function on the base paper and develops color through chemical reactions. It is mainly used in the field of commercial bills. It is divided into upper, middle and lower papers. It looks the same as ordinary white paper, but in fact, it is coated with microcapsule coating made of colorless dye on its surface. Due to different coatings, it is divided into CB paper and CF paper. CF paper is mainly coated with an acidic developer, while CB paper is coated with microcapsules containing colorless dyes. When the microcapsules in the CB paper are broken by the writing pressure, the colorless dye in the core material is transferred to the CF paper, and the color is displayed through chemical reactions.

[0004] In the prior art, based on the purpose of simplifying carbonless copy paper, it is expected to obtain a copy paper that does not require the joint use of upper and lower links, has anti-counterfeiting properties and can produce invisible handwriting. However, the applicant found that there is no commercial paper of this kind at present. One of the technical difficulties is the lack of mature preparation technology for invisible fluorescent microcapsules. The fluorescent material of the existing fluorescent microcapsules is adsorbed on the microcapsules and is not coated in the oil phase in the capsule core. When the microcapsules are ruptured under pressure, the oil phase in the capsule core in the pressurized area flows out, but because there is no fluorescent material flowing out of the oil phase, this fluorescent microcapsule cannot be used in carbonless copy paper to realize the copying of invisible handwriting. Therefore, it is necessary to provide an invisible fluorescent microcapsule with pressure-sensitive properties. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a fluorescent microcapsule for invisible handwriting replication and a preparation method thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A fluorescent microcapsule comprises a capsule wall and a capsule core. The capsule wall is coated on the surface of the capsule core and is formed by a mixed reaction of an aqueous solution and an oily solution. The fluorescent microcapsule uses a polyethylene glycol olefin derivative as the capsule wall material and an oily solvent as the capsule core material. An oil-soluble fluorescent dye and an additive are dissolved in the oily solvent. The additive is an ionic surfactant that can react with the oil-soluble fluorescent dye in molecules.

[0008] As a further improvement to the above technical solution:

[0009] The raw materials of the aqueous phase solution include emulsifier, polyethylene glycol olefin derivative and water, and the mass ratio of the emulsifier, polyethylene glycol olefin derivative and water is 3-10:0.5-3:15-40.

[0010] The emulsifier is one or more of polyvinyl alcohol, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, propylene-maleic anhydride copolymer, and isobutylene-maleic anhydride copolymer. The emulsifier is a surfactant of a polymer chain that stabilizes the oil-water microcapsule, has a large number of hydrophilic groups, and can adhere to the surface of the oil phase droplets to form a stable emulsion.

[0011] The polyethylene glycol olefin derivative is one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol fumarate, and olefin-polyethylene glycol-olefin.

[0012] The raw materials of the oil phase solution include oil-soluble fluorescent dye, oil-soluble initiator, additive and oily solvent, the mass ratio of the oil-soluble fluorescent dye, oil-soluble initiator and oily solvent is 5-50:50-300:5000-10000; the mass of the additive is 0.5-2.5 times the mass of the oil-soluble fluorescent dye.

[0013] The ionic surfactant is one or more of sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkyl ammonium bromide, and alkyl pyridinium bromide;

[0014] The oil-soluble fluorescent dye is acetylacetonate europium (III), tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium (III), o-phenanthroline tris(benzoyltrifluoroacetylacetonate) europium (III), bipyridine tris(benzoyltrifluoroacetylacetonate) europium (III), bis(triphenylphosphine oxide) tris(benzoyltrifluoroacetylacetonate) europium (III) Ⅲ), o-phenanthroline tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ), bipyridine tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ), bis(triphenylphosphine oxide) tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ) , o-phenanthroline tris(benzoyltrifluoroacetylacetonate)terbium(III), bipyridine tris(benzoyltrifluoroacetylacetonate)terbium(III), bis(triphenylphosphine oxide) tris(benzoyltrifluoroacetylacetonate)terbium(III), o-phenanthroline tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione)terbium(III), bipyridine tris(4,4, One or more of 4-trifluoro-1-(2-thiophene)-1,3-butanedione)terbium(III), bis(triphenylphosphine oxide)·tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione)terbium(III), bis(triphenylphosphine oxide)·tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione)terbium(III). The fluorescent molecules in the oil-soluble fluorescent dye are invisible fluorescent molecules, which have no effect on the appearance of the action area. The residual fluorescent molecules can be seen in a specific fluorescent color under ultraviolet light, which can achieve invisibility and have anti-counterfeiting function.

[0015] The oily solvent is one or more of hexane, cyclohexane, petroleum ether, heptane, octane, 1-bromooctane, nonane, decane, undecane, dodecane, dimethyl phthalate, diethyl phthalate, propylene carbonate, and caprylic / capric triglyceride; the oily solvent is colorless and odorless, volatile, and has no corrosive effect on common fabrics, paper, metal, wood, plastic and other materials.

[0016] The oil-soluble initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

[0017] As a general inventive concept, the present invention also provides a method for preparing the aforementioned fluorescent microcapsules, comprising the following steps:

[0018] S1. Preparation of raw material aqueous solution A and oil phase solution B:

[0019] The emulsifier and the polyethylene glycol olefin derivative are dissolved in water, and the mixture is stirred to obtain an aqueous phase solution A; the oil-soluble fluorescent dye, the oil-soluble initiator, and the additive are dissolved in an oily solvent, and the mixture is stirred to obtain an oil-phase solution B;

[0020] S2, mixing the aqueous solution A and the oily solution B in a volume ratio of 5:1 to 2:1 and emulsifying to form a uniform emulsion;

[0021] S3, stirring the emulsion at 60-80°C for reaction, filtering, washing and drying to obtain fluorescent microcapsules.

[0022] In step S2, the emulsification time is 10 to 40 minutes.

[0023] In step S2, the stirring reaction time is 3 to 6 hours.

[0024] As a general inventive concept, the present invention also provides an invisible pressure-sensitive carbon paper, on which fluorescent microcapsules are coated. The fluorescent microcapsules are the aforementioned fluorescent microcapsules or fluorescent microcapsules prepared by the aforementioned method for preparing fluorescent microcapsules.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] A fluorescent microcapsule of the present invention uses polyethylene glycol olefin derivatives as the wall material of the capsule wall and an oily solvent as the core material of the capsule core. The oily solvent contains an oil-soluble fluorescent dye and an additive. The additive is an ionic surfactant that can react with the oil-soluble fluorescent dye molecularly. The ionic surfactant can react with the oil-soluble fluorescent dye (fluorescent complex) molecularly to achieve solubilization and uniform dispersion. The oil-soluble fluorescent dye is coated or dissolved in the oily solvent to avoid being wrapped into the capsule wall by the polymer monomer during the later polymerization reaction. The fluorescent microcapsule of the present invention has a pressure-sensitive property, is colorless at ordinary times, and displays a specific fluorescent color under ultraviolet light. When the microcapsule is crushed by external force, the oil-soluble fluorescent dye will flow out with the oily solvent, thereby coloring the force-bearing area and realizing the replication of invisible handwriting.

[0027] The method for preparing fluorescent microcapsules of the present invention comprises emulsifying an aqueous solution and an oily solution and then stirring and reacting the solution to obtain the fluorescent microcapsules, and the preparation process is simple.

[0028] The invisible pressure-sensitive carbon paper of the present invention can directly form an independently usable invisible pressure-sensitive carbon paper when fluorescent microcapsules are coated on the surface of the paper, and does not need to be used in triplicate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the fluorescent microcapsules prepared in Example 1.

[0030] Figure 2 This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in Example 1.

[0031] Figure 3 This is a fluorescent photograph of the fluorescent microcapsules prepared in Example 1.

[0032] Figure 4 This is an optical photograph of the fluorescent microcapsules prepared in Example 1 after being crushed and the solvent in the microcapsules flowing out.

[0033] Figure 5 This is a fluorescent photograph of the fluorescent microcapsules prepared in Example 1 after being crushed and the solvent in the microcapsules flowing out.

[0034] Figure 6 This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in Comparative Example 1.

[0035] Figure 7 This is a fluorescent photograph of the fluorescent microcapsules prepared in Comparative Example 1 after being crushed and the solvent in the microcapsules flowing out.

[0036] Figure 8 This is a scanning electron microscope photo of the fluorescent microcapsules prepared in Comparative Example 2;

[0037] Fig. 9 This is a fluorescent photograph of the fluorescent microcapsules prepared in Comparative Example 2 after being crushed and the solvent in the microcapsules flowing out.

[0038] Fig.10 This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in Comparative Example 3.

[0039] Fig.11 This is a fluorescent photograph of the fluorescent microcapsules prepared in Comparative Example 3 after being crushed and the solvent in the microcapsules flowing out.

[0040] Fig.12 The optical and fluorescent photographs of the fluorescent microcapsules prepared in Comparative Example 4 after being crushed and the solvent in the microcapsules flowing out are shown in FIG. Fig.12 (a) is an optical photograph, Fig.12 (b) is a fluorescence photograph. DETAILED DESCRIPTION

[0041] The present invention will be described in further detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0042] Embodiment 1:

[0043] like Figure 1As shown, a fluorescent microcapsule of this embodiment includes a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (polyethylene glycol dimethacrylate) is used as the wall material of the capsule wall 1, and an oily solvent (decane) is used as the core material of the capsule core 2. An oil-soluble fluorescent dye (Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide) and an additive (dodecyl ammonium bromide), the additive (dodecyl ammonium bromide) can react with an oil-soluble fluorescent dye (Eu 3+ An ionic surfactant that interacts with a molecule (complex formed by 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide europium).

[0044] A method for preparing fluorescent microcapsules in this embodiment comprises the following steps:

[0045] S1. Dissolve 4 g of polyvinyl alcohol and 2 g of polyethylene glycol dimethacrylate in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous solution A.

[0046] 10 mg of Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide, 50 mg of benzoyl peroxide and 10 mg of dodecylammonium bromide were dissolved in 6 g of decane, completely dissolved and stirred evenly to obtain an oily solution B.

[0047] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0048] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours. After the reaction is completed, filter and wash with water three times, and dry in an oven to obtain fluorescent microcapsules.

[0049] The invisible pressure-sensitive carbon paper of this embodiment is obtained by coating the fluorescent microcapsules prepared in this embodiment on paper using a conventional method.

[0050] Figure 2 This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in this example. The fluorescent microcapsules are spherical as a whole.

[0051] Figure 3 This is a fluorescent photo of the fluorescent microcapsules prepared in this example. The fluorescent microcapsules have a fluorescent effect.

[0052] Figure 4This is an optical photograph of the fluorescent microcapsules prepared in this example after being crushed and the oily solvent in the microcapsules flowing out. The shaded area is the range where the oily solvent flows out (the area surrounded by two dotted schematic lines).

[0053] Figure 5 This is a fluorescent photograph of the fluorescent microcapsules prepared in this embodiment after being crushed and the solvent in the microcapsules flowing out. It can be seen that the oily solvent outflow range shows strong fluorescence, indicating that the fluorescent molecules of the fluorescent dye can flow out freely with the oily solvent to achieve the copying of invisible handwriting. The invisible pressure-sensitive carbon paper of this embodiment can be used independently and does not need to be equipped with a triplicate.

[0054] Comparative Example 1:

[0055] The fluorescent microcapsule of the comparative example comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (polyethylene glycol dimethacrylate) is used as the wall material of the capsule wall 1, an oily solvent (decane) is used as the core material of the capsule core 2, and an oil-soluble fluorescent dye (Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide is adsorbed on the capsule wall 1 of the microcapsule.

[0056] A method for preparing fluorescent microcapsules in this comparative example, without adding additives, comprises the following steps:

[0057] S1. Dissolve 4 g of polyvinyl alcohol and 2 g of polyethylene glycol dimethacrylate in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous solution A.

[0058] 10 mg of Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide europium and 50 mg of benzoyl peroxide were dissolved in 6 g of decane, completely dissolved and stirred evenly to obtain an oily solution B.

[0059] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0060] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours, filter after the reaction, wash three times with water, and dry in an oven to obtain microcapsules.

[0061] The carbon paper of this comparative example is obtained by coating the fluorescent microcapsules prepared in this example on paper using a conventional method.

[0062] Figure 6 This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in this comparative example.

[0063] Figure 7 This is a fluorescent photograph of the fluorescent microcapsules prepared in this comparative example after being crushed and the solvent in the microcapsules flowing out. The area surrounded by the dotted schematic line is the outflow range of the oily solvent. It can be seen that the area where the microcapsules are located shows strong fluorescence, but the oily solvent outflow range does not show fluorescence, which indicates that the fluorescent molecules are only adsorbed on the capsule wall 1 of the microcapsule and are not wrapped or dissolved in the oily oil phase of the microcapsule. It can be seen that the carbon paper of this comparative example cannot be used independently.

[0064] Comparative Example 2:

[0065] The fluorescent microcapsule of the comparative example comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. Polyethylene glycol olefin derivatives (methyl methacrylate, 1,4-butanediol diacrylate) are used as the wall material of the capsule wall 1, an oily solvent (decane) is used as the core material of the capsule core 2, and an oil-soluble fluorescent dye (Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide is adsorbed on the capsule wall 1 of the microcapsule.

[0066] A method for preparing a fluorescent microcapsule in this comparative example uses polymer monomers methyl methacrylate and 1,4-butanediol diacrylate as the wall material of the capsule wall 1, comprising the following steps:

[0067] S1. Dissolve 4 g of polyvinyl alcohol in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous phase solution A.

[0068] 10 mg of Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide, 50 mg of benzoyl peroxide, 10 mg of dodecylammonium bromide, 2 g of methyl methacrylate, and 1 g of 1,4-butanediol diacrylate were dissolved in 6 g of decane, completely dissolved and stirred evenly to obtain an oily solution B.

[0069] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0070] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours, filter after the reaction, wash three times with water, and dry in an oven to obtain microcapsules.

[0071] The carbon paper of this comparative example is obtained by coating the fluorescent microcapsules prepared in this example on paper using a conventional method.

[0072] Figure 8This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in this comparative example.

[0073] Fig. 9 This is a fluorescent photograph of the fluorescent microcapsules prepared in this comparative example after being crushed and the solvent in the microcapsules flowing out. The area surrounded by the dotted schematic line is the oily solvent outflow range. It can be seen that the area where the microcapsules are located shows strong fluorescence, but the solvent outflow range does not show fluorescence, which indicates that the fluorescent molecules are only adsorbed on the capsule wall 1 of the microcapsule and are not wrapped or dissolved in the oil phase of the microcapsule. It can be seen that the carbon paper of this comparative example cannot be used independently.

[0074] Comparative Example 3:

[0075] The fluorescent microcapsule of the comparative example comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (methyl methacrylate) is used as the wall material of the capsule wall 1, an oily solvent (decane) is used as the core material of the capsule core 2, and an oil-soluble fluorescent dye (Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide is adsorbed on the capsule wall 1 of the microcapsule.

[0076] A method for preparing a fluorescent microcapsule in this comparative example uses a polymer monomer ethylene glycol dimethacrylate as the wall material of the capsule wall 1, comprising the following steps:

[0077] S1. Dissolve 4 g of polyvinyl alcohol in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous phase solution A.

[0078] 10 mg of Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine europium oxide, 50 mg of benzoyl peroxide, 10 mg of dodecyl ammonium bromide, and 2 g of ethylene glycol dimethacrylate are dissolved in 6 g of decane, completely dissolved and stirred evenly to obtain an oily solution B.

[0079] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0080] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours. After the reaction is completed, filter and wash with water three times, and dry in an oven to obtain fluorescent microcapsules.

[0081] The carbon paper of this comparative example is obtained by coating the fluorescent microcapsules prepared in this example on paper using a conventional method.

[0082] Fig.10This is a scanning electron microscope photograph of the fluorescent microcapsules prepared in this comparative example.

[0083] Fig.11 This is a fluorescent photograph of the fluorescent microcapsules prepared in this comparative example after being crushed and the solvent in the microcapsules flowing out. The area surrounded by the dotted schematic line is the oily solvent outflow range. It can be seen that the area where the microcapsules are located shows strong fluorescence, but the solvent outflow range does not show fluorescence, which indicates that the fluorescent molecules are only adsorbed on the capsule wall 1 of the microcapsule and are not wrapped or dissolved in the oil phase of the microcapsule. It can be seen that the carbon paper of this comparative example cannot be used independently.

[0084] Comparative Example 4:

[0085] The fluorescent microcapsule of the comparative example comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (polyethylene glycol dimethacrylate) is used as the wall material of the capsule wall 1, an oily solvent (decane) is used as the core material of the capsule core 2, and an oil-soluble fluorescent dye (Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide is adsorbed on the capsule wall 1 of the microcapsule.

[0086] A method for preparing fluorescent microcapsules in this comparative example, wherein the additive is dodecylphenol polyoxyethylene ether (OP-10), comprises the following steps:

[0087] S1. Dissolve 4 g of polyvinyl alcohol and 2 g of polyethylene glycol dimethacrylate in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous solution A.

[0088] 10 mg of Eu 3+ The complex formed with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione and triphenylphosphine oxide, 50 mg of benzoyl peroxide, and 10 mg of OP-10 were dissolved in 6 g of decane, completely dissolved and stirred evenly to obtain an oily solution B.

[0089] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0090] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours, filter after the reaction, wash three times with water, and dry in an oven to obtain microcapsules.

[0091] The carbon paper of this comparative example is obtained by coating the fluorescent microcapsules prepared in this example on paper using a conventional method.

[0092] Fig.12These are optical photographs and fluorescent photographs of the fluorescent microcapsules prepared in this comparative example after being crushed and the solvent in the microcapsules flowing out. The area enclosed by the dotted schematic line is the outflow range of the oily solvent. It can be seen that the area where the microcapsules are located shows strong fluorescence, but the solvent outflow range does not show fluorescence, which indicates that the fluorescent molecules are only adsorbed on the capsule wall 1 of the microcapsule and are not wrapped or dissolved in the oil phase of the microcapsule. It can be seen that the carbon paper of this comparative example cannot be used independently.

[0093] Embodiment 2:

[0094] A fluorescent microcapsule of the present embodiment comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (polyethylene glycol fumarate) is used as the wall material of the capsule wall 1, and an oily solvent (caprylic acid / capric acid triglyceride) is used as the core material of the capsule core 2. An oil-soluble fluorescent dye (o-phenanthroline tris(benzoyltrifluoroacetylacetonate) terbium (III)) and an additive (hexadecylpyridinium bromide) are dissolved in the oily solvent (caprylic acid / capric acid triglyceride). The additive (hexadecylpyridinium bromide) is an ionic surfactant that can react molecularly with the oil-soluble fluorescent dye (o-phenanthroline tris(benzoyltrifluoroacetylacetonate) terbium (III)).

[0095] A method for preparing fluorescent microcapsules in this embodiment comprises the following steps:

[0096] S1. Dissolve 6 g of polyvinyl alcohol and 2 g of polyethylene glycol fumarate in 30 g of pure water, completely dissolve and stir evenly to obtain an aqueous phase solution A.

[0097] 5 mg of 1,2-phenanthroline tris(benzoyltrifluoroacetylacetonate)terbium(III), 50 mg of azobisisobutyronitrile and 10 mg of cetylpyridinium bromide were dissolved in 6 g of caprylic / capric triglyceride, and the mixture was completely dissolved and stirred to obtain an oily solution B.

[0098] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0099] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours. After the reaction is completed, filter and wash with water three times, and dry in an oven to obtain fluorescent microcapsules.

[0100] The invisible pressure-sensitive carbon paper of this embodiment is obtained by coating the fluorescent microcapsules prepared in this embodiment on paper using a conventional method.

[0101] Embodiment 3:

[0102] A fluorescent microcapsule of the present embodiment comprises a capsule wall 1 and a capsule core 2. The capsule wall 1 is coated on the surface of the capsule core 2 and is formed by a mixed reaction of an oil phase solution and an aqueous phase solution. A polyethylene glycol olefin derivative (polyethylene glycol diacrylate) is used as the wall material of the capsule wall 1, and an oily solvent (1-bromooctane) is used as the core material of the capsule core 2. An oil-soluble fluorescent dye (bipyridine tris (benzoyltrifluoroacetylacetonate) europium (III)) and an additive (sodium dodecyl sulfonate) are dissolved in the oily solvent (1-bromooctane). The additive (sodium dodecyl sulfonate) is an ionic surfactant that can undergo molecular action with the oil-soluble fluorescent dye (bipyridine tris (benzoyltrifluoroacetylacetonate) europium (III)).

[0103] A method for preparing fluorescent microcapsules in this embodiment comprises the following steps:

[0104] S1. Dissolve 3 g of styrene-maleic anhydride copolymer and 3 g of polyethylene glycol diacrylate in 20 g of pure water, completely dissolve and stir evenly to obtain an aqueous solution A.

[0105] 10 mg of bipyridine tris(benzoyltrifluoroacetylacetonate)europium(III), 80 mg of azobisisoheptanenitrile and 20 mg of sodium dodecylsulfonate were dissolved in 6 g of 1-bromooctane, and stirred to obtain an oily solution B after complete dissolution.

[0106] S2. The aqueous solution A and the oily solution B were mixed and emulsified in a homogenizer for 20 min to form a uniform O / W emulsion.

[0107] S3. Pour the emulsion into a round-bottom flask, stir and react at 70°C for 5 hours. After the reaction is completed, filter and wash with water three times, and dry in an oven to obtain fluorescent microcapsules.

[0108] The invisible pressure-sensitive carbon paper of this embodiment is obtained by coating the fluorescent microcapsules prepared in this embodiment on paper using a conventional method.

[0109] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A fluorescent microcapsule, comprising a capsule wall (1) and a capsule core (2), wherein the capsule wall (1) is coated on the surface of the capsule core (2) and is formed by a mixed reaction of an aqueous solution and an oily solution, characterized in that: The fluorescent microcapsule uses polyethylene glycol olefin derivatives as the wall material of the capsule wall (1) and an oily solvent as the core material of the capsule core (2). The oily solvent contains an oil-soluble fluorescent dye and an additive, and the additive is an ionic surfactant that can react with the oil-soluble fluorescent dye in molecules.

2. The fluorescent microcapsule according to claim 1, characterized in that: The raw materials of the aqueous phase solution include emulsifier, polyethylene glycol olefin derivative and water, and the mass ratio of the emulsifier, polyethylene glycol olefin derivative and water is 3-10:0.5-3:15-40.

3. The fluorescent microcapsule according to claim 2, characterized in that: The emulsifier is one or more of polyvinyl alcohol, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, propylene-maleic anhydride copolymer, and isobutylene-maleic anhydride copolymer; The polyethylene glycol olefin derivative is one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol fumarate, and olefin-polyethylene glycol-olefin.

4. The fluorescent microcapsule according to claim 1, characterized in that: The raw materials of the oil phase solution include oil-soluble fluorescent dye, oil-soluble initiator, additive and oily solvent, the mass ratio of the oil-soluble fluorescent dye, oil-soluble initiator and oily solvent is 5-50:50-300:5000-10000; the mass of the additive is 0.5-2.5 times the mass of the oil-soluble fluorescent dye.

5. The fluorescent microcapsule according to claim 4, characterized in that: The ionic surfactant is one or more of sodium alkyl sulfonate, sodium alkylbenzene sulfonate, alkyl ammonium bromide, and alkyl pyridinium bromide; The oil-soluble fluorescent dye is acetylacetonate europium (III), tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium (III), o-phenanthroline tris(benzoyltrifluoroacetylacetonate) europium (III), bipyridine tris(benzoyltrifluoroacetylacetonate) europium (III), bis(triphenylphosphine oxide) tris(benzoyltrifluoroacetylacetonate) europium (III) Ⅲ), o-phenanthroline tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ), bipyridine tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ), bis(triphenylphosphine oxide) tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione) europium(Ⅲ) , o-phenanthroline tris(benzoyltrifluoroacetylacetonate)terbium(III), bipyridine tris(benzoyltrifluoroacetylacetonate)terbium(III), bis(triphenylphosphine oxide) tris(benzoyltrifluoroacetylacetonate)terbium(III), o-phenanthroline tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione)terbium(III), bipyridine tris(4,4, One or more of terbium (III) complex with 4-trifluoro-1-(2-thiophene)-1,3-butanedione), terbium (III) complex with bis(triphenylphosphine oxide)·tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione), and terbium (III) complex with bis(triphenylphosphine oxide)·tris(4,4,4-trifluoro-1-(2-thiophene)-1,3-butanedione).

6. The fluorescent microcapsule according to claim 4, characterized in that: The oily solvent is one or more of hexane, cyclohexane, petroleum ether, heptane, octane, 1-bromooctane, nonane, decane, undecane, dodecane, dimethyl phthalate, diethyl phthalate, propylene carbonate, caprylic / capric triglyceride; The oil-soluble initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

7. A method for preparing fluorescent microcapsules according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Preparation of raw material aqueous solution A and oil phase solution B: The emulsifier and the polyethylene glycol olefin derivative are dissolved in water, and the mixture is stirred to obtain an aqueous phase solution A; the oil-soluble fluorescent dye, the oil-soluble initiator, and the additive are dissolved in an oily solvent, and the mixture is stirred to obtain an oil-phase solution B; S2, mixing the aqueous solution A and the oily solution B in a volume ratio of 5:1 to 2:1 and emulsifying to form a uniform emulsion; S3, stirring the emulsion at 60-80°C for reaction, filtering, washing and drying to obtain fluorescent microcapsules.

8. The method for preparing fluorescent microcapsules according to claim 7, characterized in that: In step S2, the emulsification time is 10 to 40 minutes.

9. The method for preparing fluorescent microcapsules according to claim 7, characterized in that: In step S2, the stirring reaction time is 3 to 6 hours.

10. An invisible pressure-sensitive carbon paper, on which fluorescent microcapsules are coated, characterized in that: The fluorescent microcapsule is a fluorescent microcapsule according to any one of claims 1 to 6 or a fluorescent microcapsule prepared by the method for preparing the fluorescent microcapsule according to any one of claims 7 to 9.

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