Prussian blue coated photonic crystal pigment as well as preparation method and application thereof

Abstract

The invention relates to a prussian-blue-coated photonic crystal pigment and a preparation method and application thereof.The prussian-blue-coated photonic crystal pigment comprises photonic crystal pigment particles and a coating layer on the surfaces of the photonic crystal pigment particles, the coating layer comprises prussian blue, the thickness of the coating layer is larger than 10 nm, and the thickness of the coating layer is larger than 10 nm. The reflectivity and covering power of the photonic crystal pigment can be improved.

Description

Technical Field

[0001] The invention relates to the field of materials, and in particular to a Prussian blue-wrapped photonic crystal pigment and a preparation method and application thereof. Background Art

[0002] The colors of substances are mainly divided into chemical colors and structural colors. Chemical colors are produced by pigments in substances through chromophores, while structural colors are achieved through internal microstructures. Structural colors are ubiquitous in nature, such as butterfly wings and peacock feathers. When the internal microstructure of a substance is disordered, light is mainly scattered; when the internal microstructure of a substance is orderly arranged, diffraction or interference (Bragg diffraction) mainly occurs, forming structural colors. Through further design, a refractive index difference is formed in the microstructure, and structural colors that vary with angle can be obtained, which are so-called rainbow colors (colorful).

[0003] The rainbow colors produced by the Bragg diffraction principle are used to make colorful films, which have many advantages such as bright colors and environmental friendliness, and are widely used in the fields of decoration and packaging. The technologies that can be used to make colorful films include multi-layer coating, multi-layer co-extrusion, liquid crystal polymerization, photonic crystals, nanoimprinting, laser, etc.

[0004] Among them, photonic crystals are formed by three-dimensional orderly arrangement of microspheres. When light is incident on photonic crystals, due to the periodic structure of photonic crystals, the light diffracts or interferes, thereby reflecting light of a specific wavelength, which is Bragg reflection. At the same time, as the size of the microspheres and the distance of the lattice change, photonic crystals can reflect light from ultraviolet to infrared bands. When the reflected wavelength is within the visible light range, it can produce dazzling colors as a structural color; as the refractive index of the microsphere material and the number of layers of the periodic structure change, the reflectivity changes. The microspheres are processed onto a film and crystallized through self-assembly, bending-induced oscillation shear and other technologies to form a colorful film (photonic crystal film).

[0005] Adding oligomers and monomers to the microsphere emulsion to fill the gaps between the microspheres, and adding a photoinitiator to initiate polymerization of the oligomers and monomers, the crystallized arrangement of the microspheres is fixed, thereby obtaining a photonic crystal film (e.g., Chinese invention patent CN111363393B). After the photonic crystal film is crushed, a photonic crystal pigment can be obtained, which can be used in the fields of ink, coating, plastic, etc.

[0006] Photonic crystal pigments, due to their internal microsphere material and crystallized arrangement, can form a narrow and deep reflection spectrum curve, thus having high saturation and high transmittance that ordinary pigments or dyes do not have. However, correspondingly, high transmittance also brings the disadvantages of low reflectivity and low hiding power. If photonic crystal pigments are simply mixed with organic pigments and dyes with strong hiding power, the color of the photonic crystal pigment will often be covered by the pigment, thus failing to fully present its colorful appearance.

[0007] In addition, the micronization process of photonic crystal pigments uses a pulverization process, which causes the surface of photonic crystal pigments to have high roughness, which will affect the colorful effect of photonic crystal pigments. In particular, when photonic crystal pigments are mixed into systems such as plastics, inks, and coatings, they basically present irregular dispersion, so some of the photonic crystal pigments observed often appear in a colorless scattered state, affecting the overall appearance.

[0008] Prussian blue is a pigment with excellent performance. In the 18th century, Heinrich Diesbach, a painter in Berlin, Germany, made yellow crystalline potassium ferrocyanide K 4 [Fe(CN) 6 ] Add ferric chloride FeCl 3 The first coordination compound, Prussian blue, was invented in a solution of 200 mg / kg. Prussian blue is a pigment with excellent performance, environmental protection and easy production. It is still widely used in paints, inks, crayons, painted paper and other coloring. 4 [Fe(CN) 6 ] and FeCl 3 After mixing, it has the characteristic of rapid reaction. There is no report on combining Prussian blue with photonic crystal pigments. Summary of the invention

[0009] In view of the deficiencies in the prior art, the first object of the present invention is to provide a Prussian blue-encapsulated photonic crystal pigment, which can improve the reflectivity and hiding power of the pigment.

[0010] The second object of the present invention is to provide a method for preparing a Prussian blue-encapsulated photonic crystal pigment, which has the advantages of high production efficiency, strong controllability, etc.

[0011] The third object of the present invention is to provide an application of Prussian blue encapsulating photonic crystal pigment.

[0012] To achieve the first object of the present invention, the present invention provides a Prussian blue-wrapped photonic crystal pigment, comprising photonic crystal pigment particles and a wrapping layer on the surface of the photonic crystal pigment particles, wherein the wrapping layer comprises Prussian blue and has a thickness greater than 10 nm.

[0013] In some embodiments of the present invention, the thickness of the encapsulating layer is greater than 10 nm and less than or equal to 5000 nm, preferably the thickness of the encapsulating layer is between 50 nm and 1000 nm, and more preferably the thickness of the encapsulating layer is between 50 nm and 500 nm.

[0014] In some embodiments of the present invention, the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is less than 0.89 μm, preferably the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is less than 0.5 μm, and more preferably the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is between 0.1 μm and 0.4 μm.

[0015] In some embodiments of the present invention, the Prussian blue is ferric ferrocyanide (Fe 4 [Fe(CN) 6 ] 3 ferrocyanide (Fe 3 [Fe(CN) 6 ] 2 ) at least one.

[0016] In some embodiments of the present invention, the photonic crystal pigment particles include a polymer and nano-microspheres dispersed in the polymer in a three-dimensional orderly arrangement; preferably, the nano-microspheres are at least one of polymer microspheres, inorganic microspheres and polymer-inorganic composite microspheres, the polymer microspheres are at least one of polystyrene microspheres and core-shell structured polymer microspheres, the inorganic microspheres are at least one of silicon dioxide, titanium dioxide, ferrosoferric oxide and zinc sulfide, the nano-microspheres have an average particle size of 100 to 400 nm, a polydispersity index PDI of less than 0.15, and the polymer includes an acrylate polymer.

[0017] To achieve the second purpose of the present invention, the present invention provides a method for preparing a Prussian blue-encapsulated photonic crystal pigment, comprising the following steps: step one: dispersing photonic crystal pigment particles in a non-polar solvent to form a photonic crystal pigment dispersion; step two: adding an iron salt aqueous solution to the photonic crystal pigment dispersion obtained in step one under stirring; step three: adding a hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in step two under stirring to deposit Prussian blue on the surface of the photonic crystal pigment; step four: separating the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in step three.

[0018] In some embodiments of the present invention, the non-polar solvent is at least one of the alkane solvents having 8 to 20 carbon atoms. Preferably, the non-polar solvent is a normal alkane such as n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane; or at least one of isooctane, isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane. More preferably, the non-polar solvent is an isomeric alkane having a carbon number of 8 to 20 and a boiling point of 60°C <150°C.

[0019] In some embodiments of the present invention, the iron salt is ferric chloride (FeCl 3 ), ferrous chloride (FeCl 2 ), iron nitrate (Fe(NO 3 ) 3 ), ferrous nitrate (Fe(NO 3 ) 2 ), ferrous sulfate (Fe 2 (SO 4 ) 3 ) and ferrous sulfate (FeSO 4 ) at least one.

[0020] In some embodiments of the present invention, the hexacyanoferrate is potassium ferrocyanide (K 4 [Fe(CN) 6 ]), potassium ferrocyanide (K 3 [Fe(CN) 6 ]), sodium ferrocyanide (Na 4 [Fe(CN) 6 ]), sodium ferrocyanide (Na 3 [Fe(CN) 6 ]).

[0021] In some embodiments of the present invention, the molar concentration of the aqueous solution of iron salt is 0.1 to 5 mol / L, preferably the molar concentration of the aqueous solution of iron salt is 0.5 to 1 mol / L.

[0022] In some embodiments of the present invention, the molar concentration of the potassium hexacyanoferrate aqueous solution is 0.1 to 5 mol / L, preferably the molar concentration of the potassium hexacyanoferrate aqueous solution is 0.5 to 1 mol / L.

[0023] In some embodiments of the present invention, the ratio of the photonic crystal pigment particles, the non-polar solvent, the iron salt aqueous solution, and the potassium hexacyanoferrate aqueous solution is 1 g: (1 to 100 g): (0.01 to 1 ml): (0.01 to 1 ml).

[0024] In some embodiments of the present invention, in step 2, adding the iron salt aqueous solution to the photonic crystal pigment dispersion obtained in step 1 includes slowly adding the iron salt aqueous solution to the photonic crystal pigment dispersion obtained in step 1, preferably adding the iron salt aqueous solution dropwise to the photonic crystal pigment dispersion obtained in step 1.

[0025] In some embodiments of the present invention, in step three, adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in step two includes slowly adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in step two, preferably adding the hexacyanoferrate aqueous solution dropwise to the photonic crystal pigment dispersion obtained in step two.

[0026] In some embodiments of the present invention, in step 4, separating the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in step 3 comprises filtering, washing, and drying the Prussian blue-encapsulated photonic crystal pigment.

[0027] In some embodiments of the present invention, in the step 1, dispersing the photonic crystal pigment in the non-polar solvent includes fully dispersing the photonic crystal pigment in the non-polar solvent by stirring.

[0028] In some embodiments of the present invention, in step 1, step 2 and step 3, the stirring speed is not less than 200 r / min.

[0029] In some embodiments of the present invention, in step 2, the stirring time is ≥ 2 min, preferably the stirring time is 5 to 30 min.

[0030] In some embodiments of the present invention, in step 3, the stirring time is ≥ 20 min, or the stirring is performed until the color no longer deepens.

[0031] To achieve the third object of the present invention, the present invention provides an application of a Prussian blue-encapsulated photonic crystal pigment in plastics, inks or coatings.

[0032] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0033] The Prussian blue coated photonic crystal pigment of the present invention is a Prussian blue coating layer with a certain thickness coated on the surface of the photonic crystal pigment particles, thereby improving the reflectivity, hiding power and color brightness of the photonic crystal pigment.

[0034] The preparation method of the Prussian blue-coated photonic crystal pigment of the present invention uses a non-polar solvent as a liquid dispersion medium to disperse the photonic crystal pigment, and utilizes the characteristics that the iron salt aqueous solution has a strong affinity with the photonic crystal pigment and is insoluble in the non-polar solvent, so that the chemical reaction of forming Prussian blue can be carried out on the surface of the photonic crystal, and the surface of the photonic crystal pigment particles is effectively coated with a Prussian blue coating layer with a certain thickness. The preparation method has high production efficiency and strong controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 This is a physical picture of the Prussian blue-wrapped photonic crystal pigment in Example 1 of the present invention.

[0037] Figure 2 This is a physical picture of the photonic crystal pigment in Comparative Example 1 of the present invention.

[0038] Figure 3 This is a physical picture of Prussian blue deposited on the surface of the photonic crystal in step S3 of Example 1 of the present invention.

[0039] Figure 4 This is a physical picture of the Prussian blue-wrapped photonic crystal pigment in Example 1 of the present invention being redispersed in water. DETAILED DESCRIPTION

[0040] An embodiment of the present invention provides a Prussian blue-wrapped photonic crystal pigment, which includes photonic crystal pigment particles and a wrapping layer on the surface of the photonic crystal pigment particles, the wrapping layer includes Prussian blue, wherein the thickness of the wrapping layer is greater than 10nm. The thickness of the wrapping layer can be the average thickness of the wrapping layer. In this embodiment, a more complex Bragg diffraction of the photonic crystal and the absorption color of the dye are superimposed by coating the surface of the photonic crystal pigment particles with a Prussian blue wrapping layer having a certain thickness, thereby realizing the secondary coloring of the photonic crystal pigment. The photonic crystal pigment after the secondary coloring has stronger reflectivity, covering power and richer multi-angle colors. Compared with the scheme of simply mixing and coloring the photonic crystal pigment with an organic pigment or dye with a strong covering power, this embodiment avoids the dazzling color of the photonic crystal pigment from being covered, and while maintaining the structural color of the photonic crystal pigment, the reflectivity, covering power, color brightness and richness of the pigment are improved.

[0041] In some examples, the Prussian blue-wrapped photonic crystal pigment may be mainly composed of photonic crystal pigment particles and a wrapping layer on the surface of the photonic crystal pigment particles, or the Prussian blue-wrapped photonic crystal pigment is composed of photonic crystal pigment particles and a wrapping layer on the surface of the photonic crystal pigment particles. The Prussian blue-wrapped photonic crystal pigment substantially does not contain other structures except the photonic crystal pigment particles and the wrapping layer, making the Prussian blue-wrapped photonic crystal pigment simpler.

[0042] In some examples, the coating layer is composed of Prussian blue, and the coating layer is blue. In other examples, the coating layer may also contain other pigments or dyes to adjust the color of the coating layer. The other pigments or dyes may be coated onto the surface of the photonic crystal pigment by deposition, dye bath method, etc., and mixed with Prussian blue or layered with Prussian blue.

[0043] In some examples, the coating layer has a uniform thickness on the surface of the photonic crystal pigment particle, for example, the coating layer thickness of different photonic crystal pigment particles and / or different positions on the surface of the same photonic crystal pigment particle may not exceed ±50%, ±40%, ±30%, ±20%, ±10%, etc. of the average thickness of the coating layer. The average thickness of the coating layer can be obtained by randomly selecting a plurality of photonic crystal pigment particles and / or different positions on the surface of the same photonic crystal pigment particle for measurement and calculating the average value.

[0044] In some examples, the thickness of the wrapping layer is greater than 10 nm and less than or equal to 5000 nm. The thickness of the wrapping layer may be, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm, etc. When the thickness of the wrapping layer is within the above range, the Prussian blue-wrapped photonic crystal pigment can have a richer color change range with angle-dependent color while improving reflectivity and hiding power. Considering the convenience of the preparation process, reflectivity and color range, the thickness of the wrapping layer is preferably between 50 nm and 1000 nm, and more preferably between 50 nm and 500 nm.

[0045] In some examples, the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is less than 0.89 μm, for example, the average surface roughness of the Prussian blue-wrapped photonic crystal pigment can be less than 0.89 μm and ≥ 0.1 μm, for example, it can be 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.75 μm, etc. When the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is within the above range, the scattering of the pigment dispersion system can be reduced, the colorful effect can be improved, and the overall appearance effect can be improved, which overcomes the problem in the prior art that the photonic crystal pigment crushing process leads to high roughness of the pigment surface, causing some photonic crystal pigments to scatter in the dispersion system and affect the colorful effect. Taking into account the convenience of preparation process and colorful effect, the average surface roughness of the Prussian blue-coated photonic crystal pigment is less than 0.5 μm, for example, less than 0.5 μm and ≥ 0.1 μm. More preferably, the average surface roughness of the coating layer is between 0.1 μm and 0.4 μm.

[0046] In some examples, Prussian blue is ferric ferrocyanide (Fe 4 [Fe(CN) 6 ] 3 ferrocyanide (Fe 3 [Fe(CN) 6 ] 2 ), the Prussian blue can appear blue and is easy to prepare.

[0047] In some examples, the photonic crystal pigment particles include a polymer and nano-microspheres dispersed in the polymer in a three-dimensional orderly arrangement. The photonic crystal pigment particles include a photonic crystal structure formed by three-dimensional orderly arrangement of nano-microspheres. The gaps between the nano-microspheres are fixed by filling with polymers to obtain photonic crystal pigments with structural colors. In some examples, the nano-microspheres are at least one of polymer microspheres, inorganic microspheres, and polymer-inorganic composite microspheres. The polymer microspheres can be at least one of polystyrene microspheres and core-shell polymer microspheres. The inorganic microspheres can be at least one of silicon dioxide, titanium dioxide, ferroferric oxide, and zinc sulfide. The average particle size of the nano-microspheres can be 100 to 400 nm, and the polydispersity index PDI can be less than 0.15; the polymer includes an acrylate polymer. When the nano-microspheres and polymers are made of the above raw materials, the raw materials are easy to obtain, and the preparation process of the photonic crystal pigment particles is mature. For example, the photonic crystal pigment particles can be prepared by preparing a photonic crystal film or a photonic crystal layer (including a coating) according to the methods described in Chinese patent applications CN118599352A, CN117534796A, CN116463044A, CN115058042A, CN114933894A, CN114384620A, CN114133490A, CN113896925A, CN113103706A, CN112873921A, CN111363393A, CN110908016A, and CN105949379A, and then crushing them.

[0048] An embodiment of the present invention also provides a method for preparing a Prussian blue-encapsulated photonic crystal pigment, which comprises the following steps: step one: dispersing photonic crystal pigment particles in a non-polar solvent to form a photonic crystal pigment dispersion; step two: adding an aqueous solution of iron salt to the photonic crystal pigment dispersion obtained in step one under stirring; step three: adding an aqueous solution of hexacyanoferrate to the photonic crystal pigment dispersion obtained in step two under stirring to deposit Prussian blue on the surface of the photonic crystal pigment; step four: separating the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in step three.

[0049] In the preparation method of this embodiment, a non-polar solvent is used as a liquid dispersion medium to disperse the photonic crystal pigment particles, and an iron salt aqueous solution is added during the stirring process. The iron salt aqueous solution has a strong affinity with the photonic crystal pigment and is insoluble in the non-polar solvent. The iron salt aqueous solution tends to be adsorbed on the surface of the photonic crystal pigment particles and forms a three-phase interface with the non-polar solvent. At this time, a hexacyanoferrate aqueous solution is added to allow the chemical reaction of forming Prussian blue to proceed on the surface of the photonic crystal. The formed Prussian blue will slowly deposit on the surface of the photonic crystal pigment, thereby obtaining a photonic crystal pigment uniformly coated with Prussian blue. Since iron salts and hexacyanoferrates such as K 4[Fe(CN) 6 ] and FeCl 3 The reaction is very rapid. It is difficult to control the uniform growth, deposition and adhesion of pigments or dyes on photonic crystal pigments using conventional dye bath methods. This preparation method solves the above problems and can control the reaction speed and thickness of Prussian blue, effectively depositing Prussian blue uniformly on the surface of photonic crystal pigments. Prussian blue is wrapped around the outer surface of photonic crystal pigment particles to form a wrapping layer, and it is not ruled out that some Prussian blue can penetrate into the gaps between photonic crystal pigment particles.

[0050] This method has the advantages of uniform Prussian blue coating, high production efficiency, industrialized batch production, and strong controllability, so that Prussian blue is effectively coated on the surface of photonic crystal pigment particles, improving the pigment reflectivity and color brightness. This preparation method can obtain a Prussian blue coating layer with a large thickness, and improve the surface roughness of the pigment, so that the pigment has a high color saturation at multiple observation angles, solving the problem that the photonic crystal pigment has a high color saturation when observed at 90° after coloring, but becomes colorless when the observation angle becomes smaller.

[0051] In some examples, the non-polar solvent is at least one of the alkane solvents having 8 to 20 carbon atoms, and the carbon atoms may be, for example, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20. The non-polar solvent has poor compatibility with the aqueous solution of iron salt and the aqueous solution of hexacyanoferrate, and helps the aqueous solution of iron salt and the aqueous solution of hexacyanoferrate to aggregate and react on the surface of the photonic crystal pigment particles to generate Prussian blue and deposit on the surface of the photonic crystal pigment particles. For example, the non-polar solvent may be a normal alkane such as n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane; or at least one of isooctane, isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane. In some examples, the non-polar solvent is an isomeric alkane having 8 to 20 carbon atoms and a boiling point of 60°C < 150°C, which has safety, dryness, and low biological toxicity.

[0052] In some examples, the iron salt is ferric chloride (FeCl 3 ), ferrous chloride (FeCl 2 ), iron nitrate (Fe(NO 3 )3) Ferrous nitrate (Fe(NO 3 ) 2 ), ferrous sulfate (Fe 2 (SO 4 ) 3 ) and ferrous sulfate (FeSO 4In some examples, the hexacyanoferrate is potassium ferrocyanide (K 4 [Fe(CN) 6 ]), potassium ferrocyanide (K 3 [Fe(CN) 6 ]), sodium ferrocyanide (Na 4 [Fe(CN) 6 ]), sodium ferrocyanide (Na 3 [Fe(CN) 6 The reaction of the above iron salt and hexacyanoferrate can produce Prussian blue, ferric ferrocyanide (Fe 4 [Fe(CN) 6 ] 3 ferrocyanide (Fe 3 [Fe(CN) 6 ] 2 ) at least one.

[0053] In some examples, when the iron in the iron salt is divalent, hexacyanoferrate with trivalent iron can be selected; when the iron in the iron salt is trivalent, hexacyanoferrate with divalent iron can be selected. Divalent iron, trivalent iron and cyanide form a Prussian blue coordination compound. Prussian blue can have the following two chemical reaction mechanisms:

[0054] 4Fe 3+ +3[Fe(CN) 6 ] 4- →Fe 4 [Fe(CN) 6 ] 3 ↓;

[0055] 3Fe 2+ +2[Fe(CN) 6 ] 3- →Fe 3 [Fe(CN) 6 ] 2 ↓.

[0056] In other examples, when the iron in the iron salt is trivalent, hexacyanoferrate with trivalent iron can be selected to obtain a green or brown-green precipitate. The chemical reaction mechanism is as follows:

[0057] Fe 3+ +[Fe(CN) 6 ] 3- →Fe[Fe(CN) 6 ]↓.

[0058] In some examples, the iron salt is ferric chloride (FeCl 3 ), hexacyanoferrate uses potassium ferrocyanide (K 4[Fe(CN) 6 ]), the above raw materials are easily available, and the reaction rate is highly controllable, which is conducive to obtaining pigments with lower surface roughness.

[0059] In some examples, the molar concentration of the aqueous solution of iron salt is 0.1 to 5 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, etc. The molar concentration of the potassium hexacyanoferrate aqueous solution is 0.1 to 5 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, etc. By controlling the concentration of the iron salt aqueous solution and the hexacyanoferrate aqueous solution, the speed of the Prussian blue reaction and the thickness of the coating can be controlled. Preferably, the molar concentration of the aqueous solution of iron salt is 0.5 to 1 mol / L, and the molar concentration of the aqueous solution of potassium hexacyanoferrate is 0.5 to 1 mol / L, so that the reaction speed is moderate and the formed Prussian blue coating layer has a suitable uniform thickness, which can enrich the angular color variation of the photonic crystal pigment, enhance the color concentration at different observation angles, and not cover the structural color too much.

[0060] In some examples, the ratio of photonic crystal pigment particles, non-polar solvent, iron salt aqueous solution, and potassium hexacyanoferrate aqueous solution is 1g: (1 to 100g): (0.01 to 1ml): (0.01 to 1ml), which helps to form a coating layer with sufficient thickness and avoids waste of raw materials. Considering the cost of raw materials and other aspects, the ratio of photonic crystal pigment particles, non-polar solvent, iron salt aqueous solution, and potassium hexacyanoferrate aqueous solution is 1g: (1 to 20g): (0.01 to 0.1ml): (0.01 to 0.1ml).

[0061] In some examples, in step 2, adding an aqueous solution of iron salt to the photonic crystal pigment dispersion obtained in step 1 includes slowly adding an aqueous solution of iron salt to the photonic crystal pigment dispersion obtained in step 1, such as dropping an aqueous solution of iron salt to the photonic crystal pigment dispersion obtained in step 1. In step 3, adding an aqueous solution of hexacyanoferrate to the photonic crystal pigment dispersion obtained in step 2 includes slowly adding an aqueous solution of hexacyanoferrate to the photonic crystal pigment dispersion obtained in step 2, such as dropping an aqueous solution of hexacyanoferrate to the photonic crystal pigment dispersion obtained in step 2. By slowly adding, for example, dropping an aqueous solution of iron salt and hexacyanoferrate, the reaction rate can be further controlled, and the thickness uniformity of the Prussian blue coating layer can be improved.

[0062] In some examples, in step 4, separating the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in step 3 includes filtering, washing, and drying the Prussian blue-encapsulated photonic crystal pigment to reduce impurities attached to the Prussian blue-encapsulated photonic crystal pigment.

[0063] In some examples, in step one, dispersing the photonic crystal pigment particles in the non-polar solvent includes fully dispersing the photonic crystal pigment particles in the non-polar solvent by stirring, so as to facilitate uniform deposition of Prussian blue on the surface of the photonic crystal pigment particles.

[0064] In some examples, in step 1, step 2 and step 3, the stirring speed is not less than 200 r / min, so that the photonic crystal pigment particles and the Prussian blue reaction raw materials are evenly dispersed. The stirring speed can be, for example, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, etc.

[0065] In some examples, in step 2, the stirring time is ≥ 2 min, for example, the stirring time is 5 to 30 min, so that the iron salt aqueous solution can be evenly dispersed on the surface of the photonic crystal pigment particles.

[0066] In some examples, in step three, the stirring time is ≥ 20 min, for example, the stirring time is 20 to 50 min, or the stirring is performed until the color no longer deepens, so that the hexacyanoferrate aqueous solution is evenly dispersed and the hexacyanoferrate reacts fully with the iron salt.

[0067] This embodiment also provides an application of the above-mentioned Prussian blue-encapsulated photonic crystal pigment in plastics, inks or coatings. The Prussian blue-encapsulated photonic crystal pigment is distributed in the plastics, inks or coatings, including uniform distribution or uneven distribution, so that the plastic, ink or coating product has both structural color and absorption color, thereby improving the reflectivity, hiding power, color brightness and color richness of the product at different angles.

[0068] The technical solution of the present application will be illustrated by specific examples below. In the following examples and comparative examples, unless otherwise specified, the raw materials with the same name have the same type and source, and the same steps are described with the same specific operations.

[0069] Example 1

[0070] The steps of the preparation method of the Prussian blue-encapsulated photonic crystal pigment of this embodiment are as follows:

[0071] S1. Use a stirrer at a speed of 500 r / min to fully disperse 10 g of photonic crystal pigment T99-234 in 100 g of isododecane to form a photonic crystal pigment dispersion;

[0072] S2. While stirring, add 0.4 ml of FeCl 3 The aqueous solution (0.5 mol / L) was slowly added to the photonic crystal pigment dispersion obtained in S1 and stirred for 5 min;

[0073] S3. While stirring, add 0.3 ml of K 4 [Fe(CN) 6 ] aqueous solution (0.5 mol / L) is slowly added to the photonic crystal pigment dispersion obtained in S2 to deposit Prussian blue on the surface of the photonic crystal pigment. Figure 3 As shown, it can be observed that the surface of the photonic crystal pigment slowly changes from transparent to blue, and stirring is continued for 30 min;

[0074] S4. The surface-deposited Prussian blue photonic crystal pigment obtained in S3 is filtered using a 100-mesh filter cloth, washed with deionized water, and dried at 120° C. for 1 h to obtain a Prussian blue-coated photonic crystal pigment.

[0075] The actual picture of the Prussian blue-wrapped photonic crystal pigment prepared in this example is as follows: Figure 1 shown.

[0076] Example 2

[0077] The steps of the preparation method of the Prussian blue-encapsulated photonic crystal pigment of this embodiment are as follows:

[0078] S1. Use a stirrer at a speed of 500 r / min to fully disperse 10 g of photonic crystal pigment T99-234 in 100 g of n-octane to form a photonic crystal pigment dispersion;

[0079] S2. While stirring, add 0.4 ml of FeCl 3 The aqueous solution (0.5 mol / L) was slowly added to the photonic crystal pigment dispersion obtained in S1 and stirred for 5 min;

[0080] S3. While stirring, add 0.3 ml of K 4 [Fe(CN) 6 ] aqueous solution (0.5 mol / L) was slowly added into the photonic crystal pigment dispersion obtained in S2 to deposit Prussian blue on the surface of the photonic crystal pigment. It can be observed that the surface of the photonic crystal pigment slowly changes from transparent to blue. Stirring was continued for 30 min.

[0081] S4. The surface-deposited Prussian blue photonic crystal pigment obtained in S3 is filtered using a 100-mesh filter cloth, washed with deionized water, and dried at 120° C. for 1 h to obtain a Prussian blue-coated photonic crystal pigment.

[0082] Example 3

[0083] The steps of the preparation method of the Prussian blue-encapsulated photonic crystal pigment of this embodiment are as follows:

[0084] S1. Use a stirrer at a speed of 500 r / min to fully disperse 10 g of photonic crystal pigment T99-234 in 100 g of isododecane to form a photonic crystal pigment dispersion;

[0085] S2. While stirring, add 0.3 ml of FeCl 3 The aqueous solution (0.5 mol / L) was slowly added to the photonic crystal pigment dispersion obtained in S1 and stirred for 5 min;

[0086] S3. While stirring, add 0.2 ml of K 3 [Fe(CN) 6 ] aqueous solution (0.5 mol / L) was slowly added into the photonic crystal pigment dispersion obtained in S2 to deposit Prussian blue on the surface of the photonic crystal pigment. It can be observed that the surface of the photonic crystal pigment slowly changes from transparent to green. Stirring was continued for 30 min.

[0087] S4. The surface-deposited Prussian blue photonic crystal pigment obtained in S3 is filtered using a 100-mesh filter cloth, washed with deionized water, and dried at 120° C. for 1 h to obtain a Prussian blue-coated photonic crystal pigment.

[0088] Example 4

[0089] The steps of the preparation method of the Prussian blue-encapsulated photonic crystal pigment of this embodiment are as follows:

[0090] S1. Use a stirrer at a speed of 500 r / min to fully disperse 10 g of photonic crystal pigment T99-234 in 100 g of isododecane to form a photonic crystal pigment dispersion;

[0091] S2. While stirring, add 0.3 ml of FeCl 2 The aqueous solution (0.5 mol / L) was slowly added to the photonic crystal pigment dispersion obtained in S1 and stirred for 30 min;

[0092] S3. While stirring, add 0.2 ml of K 3 [Fe(CN) 6 ] aqueous solution (0.5 mol / L) is slowly added to the photonic crystal pigment dispersion obtained in S2, so that Prussian blue is deposited on the surface of the photonic crystal pigment. It can be observed that the surface of the photonic crystal pigment slowly changes from transparent to blue. Stirring is stopped after the blue color no longer deepens;

[0093] S4. The surface-deposited Prussian blue photonic crystal pigment obtained in S3 is filtered using a 100-mesh filter cloth, washed with deionized water, and dried at 120° C. for 1 h to obtain a Prussian blue-coated photonic crystal pigment.

[0094] Example 5

[0095] The steps of the preparation method of the Prussian blue-encapsulated photonic crystal pigment of this embodiment are as follows:

[0096] S1. Use a stirrer at a speed of 500 r / min to fully disperse 10 g of photonic crystal pigment T99-234 in 100 g of isododecane to form a photonic crystal pigment dispersion;

[0097] S2. While stirring, add 0.4 ml of FeCl 3 The aqueous solution (0.5 mol / L) was slowly added to the photonic crystal pigment dispersion obtained in S1 and stirred for 5 min;

[0098] S3, under stirring, add 0.3 ml of Na 4 [Fe(CN) 6 ] aqueous solution (0.5 mol / L) was slowly added into the photonic crystal pigment dispersion obtained in S2 to deposit Prussian blue on the surface of the photonic crystal pigment. It can be observed that the surface of the photonic crystal pigment slowly changes from transparent to blue. Stirring was continued for 30 min.

[0099] S4. The surface-deposited Prussian blue photonic crystal pigment obtained in S3 is filtered using a 100-mesh filter cloth, washed with deionized water, and dried at 120° C. for 1 h to obtain a Prussian blue-coated photonic crystal pigment.

[0100] Example 6

[0101] The preparation method of the Prussian blue-encapsulated photonic crystal pigment in this embodiment is basically the same as that in Example 1, except that the FeCl 3 Aqueous solution (0.5 mol / L) and K 4 [Fe(CN) 6 ]The concentration of aqueous solution (0.5mol / L) was reduced to 0.1mol / L, and the rest remained unchanged.

[0102] Example 7

[0103] The preparation method of the Prussian blue-encapsulated photonic crystal pigment in this embodiment is basically the same as that in Example 1, except that the FeCl 3 Aqueous solution (0.5 mol / L) and K 4 [Fe(CN) 6 ]The concentration of aqueous solution (0.5mol / L) was increased to 2.5mol / L, and the rest remained unchanged.

[0104] Comparative Example 1

[0105] The photonic crystal pigment gold red was prepared by referring to the steps described in Example 1 of Chinese patent application CN117534796A, wherein the nano-microspheres used were polystyrene microspheres with a particle size of 250 nm and a polydispersity index PDI of 0.08.

[0106] Specifically, the preparation steps of the photonic crystal pigment are as follows:

[0107] (1) Preparation of photonic crystal coating composition: 20 g of 1,6-ethylene glycol diacrylate (HDDA), 20 g of triethylene glycol divinyl ether (DVE-3), 0.5 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 0.5 g of 4,4'-dimethyldiphenyliodonium hexafluorophosphate (TTAUV-694) were mixed with an emulsion containing 60 g of nanospheres;

[0108] (2) coating the photonic crystal coating composition on a release substrate and drying it; then performing a regularization treatment and UV curing to obtain a photonic crystal film;

[0109] (3) The photonic crystal film is peeled off and subjected to secondary photocuring, and then crushed using a crusher to obtain the photonic crystal pigment.

[0110] The actual picture of the photonic crystal pigment gold red T99-234 prepared in this comparative example is as follows Figure 2 shown.

[0111] Comparative Example 2

[0112] The preparation method of the pigment in this comparative example is substantially the same as that in Example 1, except that the isododecane in Example 1 is replaced with deionized water, and the rest remains unchanged.

[0113] Test evaluation

[0114] Add 1 g of the photonic crystal pigment of Examples (1 to 7) and Comparative Examples (1 to 2), 10 g of silica gel main agent (PDMS), and 1 g of silica gel curing agent in a container, and stir evenly; use a 250 μm film former to apply a film on a test cardboard, and heat and cure at 80°C for 10 min.

[0115] Use the visual method to observe the color at multiple angles of 90°, 45°, and 15°;

[0116] Use Sanenchi colorimeter (model: NR60C) to test the Lab value on white cardboard;

[0117] The surface roughness of photonic crystal pigments was tested using a Keyence digital microscope system (model: VHX-X1);

[0118] The particles were sliced ​​using a microtome, and then the Prussian blue coating thickness of each coated particle in the slice was measured using a SEM (scanning electron microscope), and the measured values ​​of 10 randomly selected particles were averaged.

[0119] The raw materials used in each embodiment and comparative example and the test results are shown in Table 1 below.

[0120] Table 1 Raw materials and test results of each embodiment and comparative example

[0121]

[0122] As can be seen from the above, in the Prussian blue-coated photonic crystal pigment prepared in the embodiment of the present invention, Prussian blue can be deposited on the surface of the photonic crystal to form a coating layer with a certain thickness, reduce the average surface roughness of the pigment, have a higher color saturation at different observation angles, and improve the reflectivity and hiding power of the pigment. Figure 4 As shown, the Prussian blue-wrapped photonic crystal pigment prepared in the embodiment of the present invention can be redispersed in water to present a dazzling color with high color saturation.

[0123] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A Prussian blue-encapsulated photonic crystal pigment, characterized in that The invention comprises a photonic crystal pigment particle and a wrapping layer on the surface of the photonic crystal pigment particle, wherein the wrapping layer comprises Prussian blue and the thickness of the wrapping layer is greater than 10 nm.

2. The Prussian blue-encapsulated photonic crystal pigment according to claim 1, characterized in that: The thickness of the encapsulation layer is greater than 10 nm and less than or equal to 5000 nm, preferably the thickness of the encapsulation layer is between 50 nm and 1000 nm, and more preferably the thickness of the encapsulation layer is between 50 nm and 500 nm; And / or, the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is less than 0.89 μm, preferably the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is less than 0.5 μm, and more preferably the average surface roughness of the Prussian blue-wrapped photonic crystal pigment is between 0.1 μm and 0.4 μm; And / or, the Prussian blue is at least one of ferric ferrocyanide (Fe4[Fe(CN)6]3) and ferrous ferrocyanide (Fe3[Fe(CN)6]2); And / or, the photonic crystal pigment particles include a polymer and nano-microspheres dispersed in the polymer in a three-dimensional orderly arrangement. Preferably, the nano-microspheres are at least one of polymer microspheres, inorganic microspheres and polymer-inorganic composite microspheres. The polymer microspheres are at least one of polystyrene microspheres and core-shell structured polymer microspheres. The inorganic microspheres are at least one of silicon dioxide, titanium dioxide, ferrosoferric oxide and zinc sulfide. The average particle size of the nano-microspheres is 100 to 400 nm, the polydispersity index PDI is less than 0.15, and the polymer includes an acrylate polymer.

3. A method for preparing a Prussian blue-encapsulated photonic crystal pigment according to claim 1 or 2, characterized in that The following steps are involved: Step 1: dispersing photonic crystal pigment particles in a non-polar solvent to form a photonic crystal pigment dispersion; Step 2: adding an aqueous solution of iron salt to the photonic crystal pigment dispersion obtained in step 1 under stirring; Step 3: under stirring, adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in step 2, so that Prussian blue is deposited on the surface of the photonic crystal pigment; Step 4: Separate the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in step 3.

4. The preparation method according to claim 3, characterized in that: The non-polar solvent is at least one of the alkane solvents having 8 to 20 carbon atoms. Preferably, the non-polar solvent is a normal alkane such as n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane; or at least one of isooctane, isononane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane. More preferably, the non-polar solvent is an isomeric alkane having a carbon number of 8 to 20 and a boiling point of 60°C <150°C.

5. The preparation method according to claim 3 or 4, characterized in that: The iron salt is at least one of ferric chloride (FeCl3), ferrous chloride (FeCl2), ferric nitrate (Fe(NO3)3), ferrous nitrate (Fe(NO3)2), ferric sulfate (Fe2(SO4)3) and ferrous sulfate (FeSO4); And / or, the hexacyanoferrate is at least one of potassium ferrocyanide (K4[Fe(CN)6]), potassium ferrocyanide (K3[Fe(CN)6]), sodium ferrocyanide (Na4[Fe(CN)6]), and sodium ferrocyanide (Na3[Fe(CN)6]).

6. The preparation method according to claim 3 or 4, characterized in that: The molar concentration of the iron salt aqueous solution is 0.1 to 5 mol / L, preferably the molar concentration of the iron salt aqueous solution is 0.5 to 1 mol / L; and / or, the molar concentration of the potassium hexacyanoferrate aqueous solution is 0.1 to 5 mol / L, preferably the molar concentration of the potassium hexacyanoferrate aqueous solution is 0.5 to 1 mol / L; And / or, the usage ratio of the photonic crystal pigment particles, the non-polar solvent, the iron salt aqueous solution, and the potassium hexacyanoferrate aqueous solution is 1 g: (1 to 100 g): (0.01 to 1 ml): (0.01 to 1 ml).

7. The preparation method according to claim 3 or 4, characterized in that: In the step 2, adding the iron salt aqueous solution to the photonic crystal pigment dispersion obtained in the step 1 comprises slowly adding the iron salt aqueous solution to the photonic crystal pigment dispersion obtained in the step 1, preferably dropping the iron salt aqueous solution into the photonic crystal pigment dispersion obtained in the step 1; And / or, in the step three, adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in the step two comprises slowly adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in the step two, preferably dropwise adding the hexacyanoferrate aqueous solution to the photonic crystal pigment dispersion obtained in the step two.

8. The preparation method according to claim 3 or 4, characterized in that: In the step 4, separating the Prussian blue-encapsulated photonic crystal pigment from the photonic crystal pigment dispersion obtained in the step 3 comprises performing at least one of filtering, washing and drying the Prussian blue-encapsulated photonic crystal pigment.

9. The preparation method according to claim 3 or 4, characterized in that: In the step 1, dispersing the photonic crystal pigment particles in the non-polar solvent includes fully dispersing the photonic crystal pigment particles in the non-polar solvent by stirring; In the step 1, the step 2 and the step 3, the stirring speed is not less than 200 r / min; In the step 2, the stirring time is ≥ 2 min, preferably the stirring time is 5 to 30 min; In step 3, the stirring time is ≥ 20 min, or the mixture is stirred until the color no longer deepens.

10. Application of Prussian blue-encapsulated photonic crystal pigment in plastics, inks or coatings, characterized in that The Prussian blue-encapsulated photonic crystal pigment is a Prussian blue-encapsulated photonic crystal pigment as described in claim 1 or 2, or a Prussian blue-encapsulated photonic crystal pigment obtained by the preparation method as described in any one of claims 3 to 9.

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