Structurally stable structured color material and method of making same

Abstract

The application discloses a structural color-producing material with stable structure and a preparation method thereof, and belongs to the technical field of photonic crystal structure color production. The method comprises the following steps: (1) preparing monodisperse nanometer microspheres with uniform particle size; (2) preparing a binder emulsion; (3) preparing a photonic crystal coating by taking the nanometer microspheres, a dispersing agent, a black light-absorbing substance and the binder as raw materials; (4) spraying the photonic crystal coating on the surface of a base material and drying; and (5) thinly coating the binder emulsion on the surface of the obtained amorphous photonic structure and drying. By introducing the binder, the application strengthens the interaction force between the colloidal microspheres and the base material, and effectively locks the structural array to solve the problem that the structural color is easy to be damaged. Meanwhile, the spraying method is adopted to form the amorphous photonic crystal structure on the surface of the base material, so that the structural color has the characteristics of low angle dependence and no rainbow effect, and the polychromatic structural color can be obtained by adjusting the particle size of the microspheres. The method is simple in process, low in cost and convenient for large-scale popularization.

Description

Technical Field

[0001] This invention belongs to the field of photonic crystal structural color preparation technology, specifically relating to a structurally stable structural color-generating material and its preparation method. Background Technology

[0002] Unlike chemical colors, which are based on selective light absorption, structural colors are physical colors. They are produced by the interaction of the material's periodic micro / nano structure with visible light through interference, diffraction, and scattering. Structural colors exhibit significant advantages, such as excellent lightfastness, iridescent effects, and environmental friendliness, showing broad application prospects in textile printing and dyeing.

[0003] Assembling photonic crystal structures by spraying colloidal nanosphere dispersions is one of the important methods for preparing structural colors. This method has advantages such as high efficiency, simplicity, applicability to large-area preparation and irregular substrates, and is a commonly used industrial preparation method.

[0004] However, the structural colors of photonic crystals prepared by spraying methods face significant shortcomings in practical applications. The colloidal microspheres are mainly connected to each other and to the substrate by weak forces such as van der Waals forces and hydrogen bonds. The integrity of the photonic crystal is easily damaged by external forces, leading to the fading or even disappearance of the structural colors. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a structurally stable color-generating material and its preparation method, which can introduce flexible polymers into the system to fill or encapsulate the photonic crystal structure, thereby improving the mechanical stability of the structural color.

[0006] The technical solution adopted in this invention is as follows: a structurally stable color-generating material, comprising a substrate, a structural color layer, and a polymer outer layer; wherein, the structural color layer is formed by spraying a mixture of nanosphere assembly liquid and binder emulsion onto the surface of the substrate, and the polymer outer layer is a polymer film formed by spraying the binder emulsion onto the surface of the structural color layer;

[0007] The nanospheres are one of SiO2 nanospheres, PS@SiO2 nanospheres, or hollow SiO2 nanospheres, with a particle size of 220-312 nm and a particle size dispersion coefficient of <0.1.

[0008] The mass ratio of the nanosphere assembly solution to the binder emulsion is 100%: (2%-30%).

[0009] One object of the present invention is to provide a method for preparing a structurally stable color-forming material.

[0010] Another object of the present invention is to provide a structurally stable color-forming material prepared by the above method.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] (1) Preparation of monodisperse nanospheres with uniform particle size;

[0013] (2) Preparation of binder emulsion: Emulsifier and deionized water are poured into a three-necked flask equipped with a stirring and condensing device, and nitrogen gas is introduced for protection; when the system temperature rises to 85℃, 10g of monomer is added and emulsified at 85℃ for 30min, then initiator is added, the temperature is maintained, and after 5h of full reaction, binder emulsion is obtained.

[0014] The emulsifier is sodium dodecyl sulfate;

[0015] The monomer is a mixed monomer composed of methyl methacrylate, butyl acrylate and hydroxyethyl acrylate;

[0016] The initiator is potassium persulfate;

[0017] (3) Preparation of photonic crystal coating: Mix nanospheres with carbon black and ultrasonically disperse for 10-24 h to prepare a nanosphere dispersion with a mass fraction of 3-20 wt%; mix the nanosphere dispersion with binder emulsion and ultrasonically disperse for 10-20 min to obtain nanosphere assembly solution;

[0018] (4) Spray the microsphere assembly liquid obtained in step (3) onto the surface of the substrate, and after assembly, obtain an amorphous photonic crystal structure and dry it;

[0019] (5) The binder emulsion obtained in step (2) is compounded into an emulsion with a solid content of 10%, and sprayed onto the surface of the amorphous photonic crystal structure described in step (4), and dried to form a polymer film on the surface of the amorphous photonic structure.

[0020] Preferably, in step (1), the nanospheres are one of SiO2 nanospheres, PS@SiO2 nanospheres or hollow SiO2 nanospheres, with a particle size of 220-312 nm.

[0021] The preparation method of the PS@SiO2 nanospheres is as follows:

[0022] Emulsifier, deionized water and dispersed styrene monomer are mixed, heated to 70-90℃ and then potassium persulfate initiator is added to react and obtain PS microsphere emulsion;

[0023] Deionized water was heated into the microsphere emulsion, and ammonia was added and stirred. Vinyltriethoxysilane was then added to carry out the reaction. After the reaction was completed, the mixture was centrifuged and washed to obtain PS@SiO2 nanospheres.

[0024] Preferably, the mass ratio of the dispersed styrene monomer, emulsifier, and initiator is approximately 100:(5-15):1; wherein the emulsifier is sodium dodecyl sulfate and the initiator is potassium persulfate;

[0025] The volume ratio of PS microsphere emulsion, vinyltriethoxysilane, and ammonia is 6:3:10.

[0026] Preferably, in step (1), the particle size distribution coefficient (PDI) of the nanospheres is <0.1.

[0027] Preferably, in step (2), based on the monomer weight of 100%, the emulsifier accounts for 2% to 6%, the deionized water accounts for 1000% to 1500%, and the initiator accounts for 0.4% to 1%.

[0028] Preferably, in step (2), the hard monomer is methyl methacrylate, the soft monomer is butyl acrylate, and the functional monomer is hydroxyethyl acrylate.

[0029] Preferably, in step (2), the components of the mixed monomers are proportioned as follows by mass: 40-60 parts of methyl methacrylate, 40-60 parts of butyl acrylate, and 2-8 parts of hydroxyethyl acrylate.

[0030] Preferably, in step (2), the glass transition temperature (Tg) of the adhesive is <25°C.

[0031] Preferably, in step (3), the solvent of the nanosphere dispersion is water or ethanol.

[0032] Preferably, in step (3), the nanosphere dispersion contains 0.1% to 0.4% carbon black and 4% to 33% solvent, based on 100% of the weight of the nanospheres.

[0033] Preferably, in step (3), the binder emulsion accounts for 5% to 30% of the photonic crystal coating, based on the weight of the nanosphere dispersion as 100%.

[0034] Preferably, in step (4), the substrate is one of textiles, metals, glass, paper and plastics; textiles include silk fabrics, cotton fabrics, polyester fabrics, nylon fabrics, spandex fabrics and polyester-cotton blended fabrics.

[0035] Preferably, in step (4), the nozzle diameter of the spray gun used in the spraying process is 0.2-0.5 mm, the distance between the spray gun and the substrate surface is 10-30 cm, the output pressure of the air pump connected to the spray gun is 1 bar-2 bar, and the spraying amount of the photonic crystal coating is 15-200 g / m³. 2 .

[0036] In step (4), the interface assembly temperature during spraying is 70-95℃, and the drying temperature of the substrate after spraying is 70-95℃.

[0037] In step (5), the nozzle diameter of the spray gun used in the spraying process is 0.2-0.5 mm, the distance between the spray gun and the substrate surface is 10-30 cm, the output pressure of the air pump connected to the spray gun is 1 bar-2 bar, and the spraying amount of adhesive emulsion is 5-15 g / m³. 2 .

[0038] The beneficial effects of this invention are:

[0039] (1) By introducing polyacrylate emulsion as a binder, the present invention enhances the interaction force between microspheres and between microspheres and substrate, effectively locking the structural array of colloidal microspheres and solving the problem of structural color damage.

[0040] (2) Spraying can make colloidal microspheres form amorphous photonic crystal structures with short-range order and long-range disorder on the substrate surface. It has low angle dependence and no obvious iridescent effect, which is beneficial for its application in the textile printing and dyeing field.

[0041] (3) Multi-colored structural colors can be obtained by adjusting the microsphere size, and color control is convenient and flexible.

[0042] (4) The spraying method used in this invention is simple, efficient, and inexpensive, making it easy to promote and apply on a large scale. Attached Figure Description

[0043] Figure 1 Figure 1 shows SEM images of the PS@SiO2 microspheres prepared in Examples 1-3; Figure (a) shows the microspheres with a particle size of 220 nm described in Example 1, Figure (b) shows the microspheres with a particle size of 243 nm described in Example 2, and Figure (c) shows the microspheres with a particle size of 352 nm described in Example 3.

[0044] Figure 2 This is a DSC diagram of the adhesive described in Example 4.

[0045] Figure 3 This is a DSC diagram of the adhesive described in Example 1.

[0046] Figure 4 This is a DSC diagram of the adhesive described in Example 5.

[0047] Figure 5 This is a digital photograph of the structural color-producing material described in Example 1.

[0048] Figure 6 The image shows the reflectance spectrum of the structural chromogenic material described in Example 1.

[0049] Figure 7 This is a digital photograph of the structural color-producing material described in Example 2.

[0050] Figure 8 The image shows the reflectance spectrum of the structural chromogenic material described in Example 2.

[0051] Figure 9 The image shows the reflectance spectrum of the structural color-producing material described in Example 1 after friction and water washing tests. Detailed Implementation

[0052] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0053] In the following examples, unless otherwise specified, all parts and percentages are by weight; the test methods are conventional methods unless otherwise specified; the equipment, reagents and materials are commercially available or can be prepared by conventional methods.

[0054] Example 1

[0055] A structurally stable chromogenic material and its preparation method include the following steps:

[0056] 1. PS@SiO2 nanospheres with a particle size of 220 nm were prepared. The specific preparation method is as follows:

[0057] (1) Polystyrene microspheres were prepared by soap-free emulsion polymerization, and the particle size of the microspheres was controlled by changing the amount of emulsifier. 0.110 g of sodium dodecyl sulfate (SDS) emulsifier and 135 ml of deionized water were poured into a three-necked flask equipped with a stirrer and condenser and heated. When the temperature reached 50 °C, 1.500 g of pretreated dispersed styrene monomer was added. The temperature was continued to rise to 85 °C, and after 30 min, 0.015 g of potassium persulfate (KPS) initiator was added. After reacting for 5 h, a PS microsphere emulsion was obtained.

[0058] (2) Take 6 ml of PS microsphere emulsion and 114 ml of deionized water and pour them into a three-necked flask equipped with a stirrer. Heat the mixture to 15°C and stir for 30 min. Add 10 ml of ammonia and 50 ml of deionized water, and continue stirring for 10 min. Add 3 ml of vinyltriethoxysilane and react for 5 h. Centrifuge and wash the product at 5000-6000 rpm to obtain PS@SiO2 nanospheres;

[0059] 2. Preparation of the binder emulsion: 0.600 g of emulsifier sodium dodecyl sulfate (SDS) and 110 ml of deionized water were poured into a three-necked flask equipped with a stirrer and condenser, and nitrogen gas was introduced for protection. When the system temperature reached 85℃, 10 g of mixed monomers (3.840 g of methyl methacrylate monomer, 5.760 g of butyl acrylate monomer, and 0.4 g of hydroxyethyl acrylate) were added and emulsified at 85℃ for 30 min. Then, 0.10 g of initiator potassium persulfate (KPS) was added, and the temperature was maintained. After reacting for 5 h, the binder emulsion was obtained.

[0060] 3. Preparation of photonic crystal coating: Based on 100% by weight of nanospheres and 0.2% by weight of carbon black, ethanol was used as solvent. The mixture was ultrasonically dispersed for 20 hours to prepare a nanosphere dispersion with a mass fraction of 8 wt%. The obtained nanosphere dispersion was mixed with the binder emulsion obtained in step 2 (the binder emulsion accounted for 20% of the mass of the nanosphere dispersion), and ultrasonically dispersed for 15 minutes to obtain the photonic crystal coating.

[0061] 4. Place the silk fabric on an 85℃ heating plate, and introduce the photonic crystal coating into the ink fountain of the spray gun. Use a 0.3mm nozzle spray gun at a pressure of 2 bar to spray from a distance of 10cm from the substrate surface, applying 3 layers. Place the sprayed substrate in an 85℃ oven to dry.

[0062] 5. Place the dried substrate on an 85°C heating plate, and introduce the adhesive emulsion obtained in step 3 into the ink fountain of the spray gun. Use a 0.3mm nozzle spray gun at a pressure of 2 bar to spray from a distance of 10cm from the substrate surface, applying one layer. Place the sprayed substrate in an 85°C oven to dry, obtaining a structurally stable coloring material.

[0063] Example 2

[0064] The only difference between this embodiment and Example 1 is that the amount of emulsifier added in step 1 when preparing the PS microsphere emulsion is 0.080g to prepare PS@SiO2 nanospheres with a particle size of 243nm, and the mass fraction of the nanosphere dispersion in step 3 is 10wt%, with carbon black accounting for 0.3% based on the weight of the nanospheres as 100%.

[0065] Example 3

[0066] The only difference between this embodiment and Example 1 is that the amount of emulsifier added in step 1 when preparing the PS microsphere emulsion is 0.070g to prepare PS@SiO2 nanospheres with a particle size of 352nm, and the mass fraction of the nanosphere dispersion in step 3 is 10wt%.

[0067] Example 4

[0068] The only difference between this embodiment and Example 1 is that, in step 2, when preparing the adhesive emulsion, the amount of methyl methacrylate monomer added is 3.920g, the amount of butyl acrylate monomer added is 5.880g, and the amount of hydroxyethyl acrylate added is 0.200g.

[0069] Example 5

[0070] The only difference between this embodiment and Embodiment 1 is that, in step 2, when preparing the adhesive emulsion, the amount of methyl methacrylate monomer added is 3.760g, the amount of butyl acrylate monomer added is 5.640g, and the amount of hydroxyethyl acrylate added is 0.600g.

[0071] Results and Tests

[0072] (1) Figure 1 The images show SEM images of the PS@SiO2 microspheres prepared in Examples 1-3. It can be seen that the microspheres have regular morphology, uniform particle size, good monodispersity, and high sphericity, making them suitable for the preparation of structural colors.

[0073] (2) Figure 2 , Figure 3 and Figure 4 The images show the DSC diagrams of the binders used in Examples 4, 1, and 5, respectively. It can be seen that the glass transition temperature (Tg) of the three binder ratios is less than 0°C, indicating that the binders have good film-forming properties and flexibility at room temperature, and can effectively lock the amorphous photonic crystal structure and enhance the mechanical stability of the structural color.

[0074] (3) Figure 5 , Figure 6 The image shows a photograph and reflectance spectrum of the material prepared in Example 1. It can be seen from the figure that the prepared material is a blue structural color textile. Figure 7 , Figure 8 The image shows a photograph and reflectance spectrum of the material prepared in Example 2. It can be seen from the figure that the prepared material is a green structural color textile.

[0075] (4) Figure 9 The image shows the reflectance spectrum of the structural color-generating material described in Example 1 after friction and washing tests. The results show that the color of the structural color textile did not change significantly after friction and washing tests, confirming that the introduction of polyacrylate binder can improve the stability of the structural color.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A structurally stable color-generating material, characterized in that, It includes a substrate, a structural color layer, and a polymer outer layer; wherein, the structural color layer is formed by spraying a mixture of nanosphere assembly liquid and binder emulsion onto the surface of the substrate, and the polymer outer layer is a polymer film formed by spraying the binder emulsion onto the surface of the structural color layer; The nanospheres are one of SiO2 nanospheres, PS@SiO2 nanospheres, or hollow SiO2 nanospheres, with a particle size of 220-312 nm and a particle size dispersion coefficient of <0.

1. The mass ratio of the nanosphere assembly solution to the binder emulsion is 100%: (2%-30%).

2. The method for preparing the structurally stable color-forming material according to claim 1, characterized in that: (1) Prepare a nanosphere assembly solution, wherein the nanospheres are one of SiO2 nanospheres, PS@SiO2 nanospheres or hollow SiO2 nanospheres; (2) Preparation of adhesive emulsion; Under an inert atmosphere, emulsifier, deionized water and mixed monomers are emulsified at 70℃-100℃, an initiator is added, and the temperature is maintained to allow for full reaction to obtain an adhesive emulsion. The emulsifier is sodium dodecyl sulfate; the mixed monomers are methyl methacrylate, butyl acrylate, and hydroxyethyl acrylate; the initiator is potassium persulfate. The glass transition temperature Tg of the adhesive is <25℃; (3) Preparation of photonic crystal coating: Nanospheres were mixed with carbon black and ultrasonically dispersed to obtain a nanosphere dispersion with a mass fraction of 3-20 wt%; the nanosphere dispersion was ultrasonically mixed with a binder emulsion to obtain a photonic crystal coating. The dispersant in the nanosphere dispersion is water or ethanol; (4) Spray the photonic crystal coating obtained in step (3) onto the surface of the substrate, assemble it to obtain an amorphous photonic crystal structure, and then dry it; The substrate is one of textiles, metals, glass, paper, and plastics; textiles include silk fabrics, cotton fabrics, polyester fabrics, nylon fabrics, spandex fabrics, and polyester-cotton blended fabrics. (5) Spray the adhesive emulsion obtained in step (2) onto the surface of the amorphous photonic structure described in step (4) and dry it to form a polymer film on the surface of the amorphous photonic structure.

3. The preparation method according to claim 2, characterized in that, The preparation method of the PS@SiO2 nanospheres is as follows: Emulsifier, deionized water and dispersed styrene monomer are mixed, heated to 70-90℃ and then potassium persulfate initiator is added to react and obtain PS microsphere emulsion; Deionized water was heated into the microsphere emulsion, and ammonia was added and stirred. Vinyltriethoxysilane was then added to carry out the reaction. After the reaction was completed, the mixture was centrifuged and washed to obtain PS@SiO2 nanospheres.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the dispersed styrene monomer, emulsifier, and initiator is approximately 100:(5-15):1; wherein the emulsifier is sodium dodecyl sulfate and the initiator is potassium persulfate; The volume ratio of PS microsphere emulsion, vinyltriethoxysilane, and ammonia is 6:3:

10.

5. The preparation method according to claim 2, characterized in that: In step (2), based on the weight of the mixed monomers as 100%, the emulsifier accounts for 2% to 6%, the deionized water accounts for 1000% to 1500%, and the initiator accounts for 0.4% to 1%; The components of the mixed monomers are proportioned as follows by mass: 40-60 parts of methyl methacrylate, 40-60 parts of butyl acrylate, and 2-8 parts of hydroxyethyl acrylate.

6. The preparation method according to claim 2, characterized in that: In step (3), the nanosphere dispersion contains 0.1% to 0.4% carbon black and 4% to 33% solvent, based on 100% of the weight of the nanospheres. In the photonic crystal coating, the binder emulsion accounts for 5% to 30% based on 100% of the weight of the nanosphere dispersion.

7. The preparation method according to claim 2, characterized in that: In step (4), the nozzle diameter of the spray gun used in the spraying process is 0.2-0.5 mm, the distance between the spray gun and the substrate surface is 10-30 cm, the output pressure of the air pump connected to the spray gun is 1 bar-2 bar, and the spraying amount of the photonic crystal coating is 15-200 g / m³. 2 ; The interface assembly temperature during spraying is 70–95°C, and the drying temperature of the substrate after spraying is 70–95°C.

8. The preparation method according to claim 2, characterized in that: In step (5), the nozzle diameter of the spray gun used in the spraying process is 0.2-0.5 mm, the distance between the spray gun and the substrate surface is 10-30 cm, the output pressure of the air pump connected to the spray gun is 1 bar-2 bar, and the spraying amount of adhesive emulsion is 5-15 g / m³. 2 .

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