CN116463044A

CN116463044A - Photonic crystal coating composition, film and preparation method

Info

Publication number: CN116463044A
Application number: CN202310544059.6A
Authority: CN
Inventors: 吴浩松; 田丰
Original assignee: Phomera Technologies Zhuhai Co ltd
Current assignee: Phomera Technologies Zhuhai Co ltd
Priority date: 2023-05-15
Filing date: 2023-05-15
Publication date: 2023-07-21

Abstract

The invention relates to a photonic crystal coating composition, a film and a preparation method thereof, wherein the photonic crystal coating composition comprises 10-40 parts of aqueous polyol, 2-20 parts of aqueous isocyanate curing agent, 50-80 parts of nano-microspheres and 0-2 parts of auxiliary agent, wherein the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent are uniformly dispersed. The photonic crystal film has good mechanical properties.

Description

Photonic crystal coating composition, film and preparation method

Technical Field

The invention relates to the technical field of materials, in particular to a photonic crystal coating composition, a film and a preparation method.

Background

The color of a substance is largely divided into chemical and structural colors. The chemical color is that pigment in the substance is colored through a chromophoric group, and the structural color is realized through a microstructure in the substance. Structural colors such as butterfly wings and peacock feathers are common in nature. Light is mainly scattered when the internal microstructure is disordered; when the internal microstructures are arranged in order, diffraction or interference (bragg diffraction) mainly occurs, forming structural colors. By design, a refractive index difference is formed in the microstructure, and a structural color of effect, so-called iridescence (glare) can be obtained.

The iridescence produced by using the Bragg diffraction principle is used for manufacturing the colorful film, which has the advantages of bright color, environmental friendliness and the like, and is widely applied to the fields of decoration and packaging. The technical principles of the method for manufacturing the colorful film include multilayer coating, multilayer coextrusion, liquid crystal polymerization, photonic crystal, nanoimprint, laser and the like.

The microsphere may be called a photonic crystal after being crystallized through three-dimensional ordered arrangement, and when light is incident to the photonic crystal, the photonic crystal has a periodic structure, and light is diffracted or interfered, so that light with a specific wavelength is reflected, namely Bragg reflection. Meanwhile, along with the size of the microsphere, the distance change of the crystal lattice and the reflection of light in ultraviolet to infrared wave bands by the photonic crystal, when the reflection wavelength is in the visible light range, the light can be used as structural color to generate dazzle color; the reflectivity changes along with the changes of the refractive index of the microsphere material and the layer number of the periodic structure. The microspheres are processed on the film and crystallized by self-assembly, bending induction vibration shearing (normalization) and other technologies to form a colorful film (photonic crystal film). Wherein the normalization technique is the route which can realize the rapid and large-batch crystallization of the microspheres.

Microspheres can be distinguished into organic microspheres and inorganic microspheres. The microspheres currently commercialized are mainly organic microspheres, which are typically dispersed and emulsified in water in an emulsion polymerized form. Patent document CN201610329842 discloses a method for preparing a photonic crystal film by preparing a microsphere emulsion with a transition layer and a core-shell structure by emulsion polymerization, then demulsifying, filtering and drying the emulsion to obtain powder microspheres, then adding a photo-curing monomer and a photo-initiator for dispersion, and then performing coating, normalization and photo-curing to realize crystallization and fixation of the microspheres. However, the method needs to demulsify and dry the emulsion first, has complex process and does not have industrial practicability. Patent document CN201911056709 discloses that by directly adding an auxiliary agent into microsphere emulsion and then directly rectifying crystallization, but the mechanical strength of the crystallized structure is very weak, numerous gaps exist between microspheres, and the structure is easy to be damaged. Patent document CN202010213864 discloses that the crystallization arrangement of microspheres is fixed by adding an oligomer and a monomer to the microsphere emulsion to fill gaps between the microspheres and by adding a photoinitiator to initiate crosslinking (photo-curing system) of the oligomer and the monomer, thereby realizing the practicality of industrialization. However, in the practical application process, it is found that the photonic crystal film produced by using the photocuring system has low double bond conversion rate, and a gap layer with high molecular weight is difficult to obtain, so that the mechanical property of the photonic crystal film is poor.

Disclosure of Invention

In view of the shortcomings of the prior art, a first object of the present invention is to provide a photonic crystal coating composition having excellent mechanical properties.

A second object of the present invention is to provide a photonic crystal thin film having the above photonic crystal coating composition.

A third object of the present invention is to provide a method for preparing the photonic crystal thin film.

In order to achieve the purpose of the invention, the invention provides a photonic crystal coating composition which comprises the following raw materials in parts by mass: 10-40 parts of aqueous polyol, 2-20 parts of aqueous isocyanate curing agent, 50-80 parts of nano-microspheres and 0-2 parts of auxiliary agent, wherein the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent are uniformly dispersed.

In some embodiments of the present invention, the mass parts of each raw material are: 22.5 to 40 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 50 to 70 parts of nano microsphere and 0 to 2 parts of auxiliary agent.

In some embodiments of the present invention, the mass parts of each raw material are: 22.5 to 30 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 55 to 70 parts of nano microsphere and 0.5 to 1 part of auxiliary agent.

In some embodiments of the present invention, the aqueous polyol is selected from at least one of an aqueous hydroxyurethane, an aqueous hydroxyacrylate, an aqueous polyurethane prepolymer containing hydroxyl groups.

In some embodiments of the present invention, the aqueous isocyanate curing agent is selected from at least one of a hydrophilically modified 1, 6-Hexamethylene Diisocyanate (HDI), a hydrophilically modified isophorone diisocyanate (IPDI) polymer or an isocyanate group-containing aqueous polyurethane prepolymer.

In some embodiments of the invention, the aqueous isocyanate curing agent is an isocyanate curing agent bearing sulfonic acid or salt groups thereof.

In some embodiments of the invention, the mass percent of hydroxyl groups in the aqueous polyol is from 0.5% to 6%, preferably from 3% to 5%.

In some embodiments of the invention, the aqueous isocyanate curing agent has an isocyanate group mass percent of 5% to 30%, preferably 9.4% to 20%.

In some embodiments of the invention, the nanoparticle is selected from at least one of a polymeric microsphere, an inorganic microsphere, and a polymer-inorganic composite microsphere; the polymer microsphere is at least one selected from polystyrene microsphere and core-shell structure polymer microsphere, and the inorganic microsphere is at least one selected from silicon dioxide, titanium dioxide, ferroferric oxide and zinc sulfide.

In some embodiments of the invention, the nanoparticle has an average particle size of 100 to 400nm and a polydispersity index PDI of no greater than 0.15.

In some embodiments of the invention, the nanomicrospheres are dispersed three-dimensionally in a mixture comprising the aqueous polyol, the aqueous isocyanate curing agent, and the adjuvant.

To achieve the second object of the present invention, the present invention provides a photonic crystal film, including a substrate, and further including the photonic crystal coating composition according to any one of the above aspects, wherein the photonic crystal coating composition is coated on the substrate.

In some embodiments of the invention, the substrate is selected from at least one of polyethylene terephthalate, polyethylene terephthalate-1, 4-cyclohexanedimethanol ester, polymethacrylate, polyvinyl alcohol, polynaphthalate, polycarbonate, polyurethane, acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, thermoplastic polyurethane elastomer, polyvinylidene fluoride, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyolefin.

In some embodiments of the invention, the photonic crystal film has a light transmittance of not less than 88%, a haze of not more than 2.3%, a pencil hardness of higher than HB, and an impact resistance of higher than 35kg.cm.

In order to achieve the third object of the present invention, the present invention provides a method for preparing the photonic crystal film, comprising the steps of: mixing the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent to obtain an aqueous coating liquid; and coating the aqueous coating liquid on the substrate, drying, and carrying out vibration shearing regularization treatment and curing to obtain the photonic crystal film.

In some embodiments of the invention, the aqueous polyol and the aqueous isocyanate curing agent are used in the form of an aqueous dispersion; the curing step comprises heating at 50-65 ℃ for 20-30 hours.

Compared with the prior art, the invention has the beneficial effects that:

aiming at the problems that monomer residues exist and odor residues are caused when a photo-curing system is adopted to produce a photonic crystal film at present, the inventor discovers that the photonic crystal film is produced by a two-component polyurethane heat-curing system through innovative research, and the photonic crystal film is heated and cured after regularized treatment, so that the system is completely reacted, and the photonic crystal film with excellent mechanical property is formed. Compared with the method for manufacturing the photonic crystal film by using a photo-curing system, the method improves the monomer conversion rate, forms the photonic crystal film with excellent mechanical property and optical property, and has no odor residue problem.

Drawings

FIG. 1 is a spectrum of photonic crystal thin films of the present invention of examples 1 to 6 and comparative example 1.

Detailed Description

The embodiment of the invention provides a photonic crystal coating composition, which comprises the following raw materials in parts by mass: 10-40 parts of aqueous polyol, 2-20 parts of aqueous isocyanate curing agent, 50-80 parts of nano microsphere, 0-2 parts of auxiliary agent, and uniformly dispersing the aqueous polyol, the aqueous isocyanate curing agent, the nano microsphere and the auxiliary agent. The aqueous polyol and the aqueous isocyanate curing agent form a double-component polyurethane system, the aqueous polyol and the aqueous isocyanate curing agent can react to form a cured product with high mechanical strength, and the aqueous polyol and the aqueous isocyanate curing agent are used as a matrix or a continuous phase of the coating to provide support for the nano-microspheres; the nano-microspheres are uniformly dispersed in a bi-component polyurethane system matrix or a continuous phase, and can be crystallized through three-dimensional ordered arrangement to form photonic crystals, so that the colorful structural color can be obtained; the auxiliary agent can be at least one selected from leveling agents and defoamers, and is uniformly dispersed in the matrix or continuous phase of the two-component polyurethane system, so that the mixing uniformity and the flow processability of the composition can be improved, and foam can be eliminated. When the proportion of the aqueous polyol, the aqueous isocyanate curing agent, the nano-microsphere and the auxiliary agent is adopted, the photonic crystal coating composition which is easy to thermally cure and form can be obtained, the molecular weight of the aqueous polyol and the aqueous isocyanate curing agent before curing is smaller, the viscosity of the system can be reduced, the nano-microsphere and the like are easy to uniformly disperse in a matrix or a continuous phase, the coating process on a substrate is benefited, the system can be completely reacted by heating and curing at a lower temperature during curing, the monomer conversion rate is high, the problem of odor residue does not exist, and the photonic crystal film with excellent mechanical property and optical property can be obtained after curing, and the structural color with wide dazzling color range can be realized in a visible light range.

In some embodiments, the mass parts of the aqueous polyol may be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 40, etc.

In some embodiments, the aqueous isocyanate curing agent may be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.

In some embodiments, the mass parts of the nanoparticle may be 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, etc.

In some embodiments, the mass portion of the adjuvant may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

In some embodiments, the photonic crystal coating composition is composed of the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent, and the composition does not contain other components except the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent. The total mass parts of the aqueous polyol, the aqueous isocyanate curing agent and the nano microsphere are 100 parts. The photonic crystal coating composition of the embodiment can achieve the technical effects of excellent mechanical properties and optical properties by adopting a simpler formula, and is beneficial to simplifying the preparation method and reducing the cost.

In some embodiments, the mass parts of the raw materials are: 22.5 to 40 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 50 to 70 parts of nano microsphere and 0 to 2 parts of auxiliary agent. When the mass parts of the raw materials are in the above range, a photonic crystal film with better mechanical properties and optical properties can be further obtained, the light transmittance of the photonic crystal film can reach more than 88.5, the haze is not higher than 2.1%, the pencil hardness is higher than HB, and the impact resistance is not lower than 40kg.cm.

In some embodiments, the mass parts of the raw materials are: 22.5 to 30 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 55 to 70 parts of nano microsphere and 0.5 to 1 part of auxiliary agent. When the mass parts of the raw materials are in the above range, a photonic crystal film with better mechanical properties and optical properties can be further obtained, the light transmittance of the photonic crystal film can reach more than 88.7, the haze is not higher than 1.95%, the pencil hardness is higher than H, and the impact resistance is not lower than 40kg.cm.

In some embodiments, the aqueous polyol is selected from at least one of an aqueous hydroxyurethane, an aqueous hydroxyacrylate, an aqueous polyurethane dispersion containing hydroxyl groups. The above aqueous polyol contains a plurality of hydroxyl groups, which can provide water solubility of the aqueous polyol so that the aqueous polyol can be dispersed in water. The aqueous polyurethane dispersion containing hydroxyl groups may be obtained by dispersing an aqueous polyurethane prepolymer containing hydroxyl groups in water, and may be, for example, an aqueous polyester polyurethane dispersion or an aqueous polycarbonate polyurethane dispersion.

In some embodiments, the aqueous isocyanate curing agent is selected from at least one of a hydrophilically modified 1, 6-Hexamethylene Diisocyanate (HDI), a hydrophilically modified isophorone diisocyanate (IPDI) polymer, or an aqueous polyurethane prepolymer containing isocyanate groups. The above aqueous isocyanate curing agent is an aqueous polyurethane prepolymer modified by the hydrophilicity of aliphatic/alicyclic isocyanates or containing isocyanate groups. The hydrophilic groups can provide water solubility of the aqueous isocyanate curing agent so that the aqueous isocyanate curing agent can be dispersed in water and uniformly dispersed with the aqueous polyol.

In some embodiments, the aqueous isocyanate curing agent is an isocyanate curing agent with sulfonic acid or salt groups thereof. The sulfonic acid or salt groups thereof can impart good water solubility to the isocyanate, and the sulfur atoms can also promote isocyanate curing.

In some embodiments, the mass percent of hydroxyl groups in the aqueous polyol is from 0.5% to 6%, preferably from 3% to 5%. The mass percentage of the aqueous polyol may be, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc. The aqueous polyol can have a higher hydroxyl content, improving the water solubility and reactivity of the aqueous polyol. Wherein, the total mass parts of the aqueous polyol, the aqueous isocyanate curing agent and the nano microsphere are taken as 100 parts, and the mass parts of the hydroxyl are 0.5 to 3 parts, such as 0.66 to 1.5 parts, such as 0.5 part, 1 part, 1.5 part, 2 parts, 2.5 parts, 3 parts and the like.

In some embodiments, the aqueous isocyanate curing agent has a mass percent isocyanate group of 5% to 30%, preferably 9.4% to 20%. The isocyanate group percentage of the curable isocyanate curing agent may be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or the like. Wherein the total mass parts of the aqueous polyol, the aqueous isocyanate curing agent and the nano-microspheres are taken as 100 parts, and the mass parts of the isocyanate groups are 0.5-3 parts, such as 1.41-2 parts, such as 0.5 part, 1 part, 1.5 part, 2 parts, 2.5 parts, 3 parts and the like.

In some embodiments, the nanoparticle is selected from at least one of a polymeric microsphere, an inorganic microsphere, and a polymer-inorganic composite microsphere; the polymer microsphere is at least one selected from polystyrene microsphere and core-shell structure polymer microsphere, and the inorganic microsphere is at least one selected from silicon dioxide, titanium dioxide, ferroferric oxide and zinc sulfide. In this embodiment, three-dimensional ordered arrangement of the nano-microspheres is mainly used to form structural colors, the types of the nano-microspheres are not particularly limited, and the nano-microspheres can be selected from the above types.

In some embodiments, the average particle size of the nanoparticle is 100-400 nm and the polydispersity index PDI is no greater than 0.15. When the average particle size and the polydispersity index of the nano microsphere are in the above ranges, the photonic crystal with a larger dazzling range in the visible light range and uniform and stable optical performance can be obtained by matching with a matrix or a continuous matrix. The average particle diameter of the nanoparticle may be, for example, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, or the like. The polydispersity index PDI may be, for example, 0.5, 1, 1.5, etc.

In some embodiments, the nanomicrospheres are dispersed three-dimensionally in an ordered manner in a mixture comprising an aqueous polyol, an aqueous isocyanate curing agent, and an adjuvant. The nanometer microspheres in the photonic crystal coating composition are arranged in a three-dimensional order, so that the photonic crystal coating with a colorful effect can be obtained.

Embodiments of the present invention also provide a photonic crystal film comprising a substrate and the photonic crystal coating composition described above, the photonic crystal coating composition being coated on the substrate, the substrate providing support for the photonic crystal coating, which helps to reduce the thickness of the photonic crystal coating.

In some embodiments, the substrate is selected from the group consisting of polyethylene terephthalate (PET), polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG), polymethacrylate (PMMA), polyvinyl alcohol (PVA), polyethylene naphthalate (PEN), polycarbonate (PC), polyurethane (PU), acrylonitrile butadiene styrene copolymer (ABS), polyvinyl chloride (PVC), thermoplastic polyurethane elastomer (TPU), polyvinylidene fluoride (PVDF), ethylene vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), polyolefin (POE), and the like. The substrate may be a flexible plastic sheet, and the resulting photonic crystal film can be conveniently applied to different objects by means of attachment or the like, for example, attached to the surface of an object as a decoration.

In some embodiments, the photonic crystal film has a light transmittance of not less than 88%, a haze of not more than 2.3%, a pencil hardness of higher than HB, and an impact resistance of higher than 35kg.cm. The photonic crystal film of the embodiment is a photonic crystal film with high light transmittance, low haze, high hardness and impact resistance, and has better mechanical properties and optical properties compared with the UV light curing photonic crystal film in the related art.

The embodiment of the invention also provides a preparation method of the photonic crystal film, which comprises the following steps: mixing aqueous polyol, aqueous isocyanate curing agent, nano microspheres and auxiliary agent to obtain aqueous coating liquid; and (3) coating the aqueous coating liquid on a substrate, drying, and carrying out vibration, shearing and regularization treatment and curing to obtain the photonic crystal film. According to the embodiment of the invention, the materials of the coating composition are mixed, then the coating composition is coated on a substrate, and then the nano particles are subjected to vibration, shearing and regularization treatment to enable the nano particles to be arranged in a three-dimensional order in a matrix or a continuous phase, and curing is carried out to enable a bi-component polyurethane system to be cured, so that the photonic crystal film with good optical performance and mechanical performance can be obtained, and the preparation method is simple, low in cost and suitable for large-scale production.

In some embodiments, the aqueous polyol and aqueous isocyanate curing agent are used in the form of an aqueous dispersion, which can improve the dispersibility of the components, use water as a solvent, are safe and environmentally friendly, and are easy to remove.

In some embodiments, the step of curing includes heating at 50-65 ℃ for 20-30 hours. The curing step of the embodiment has lower heating temperature and mild reaction condition, the obtained photonic crystal coating can have better morphology, the photonic crystal coating can be completely cured, monomer residues are avoided, and the mechanical property and the optical property are improved. The heating temperature may be, for example, 50 ℃, 51 ℃, 52 ℃, 53 ℃, 54 ℃, 55 ℃, 56 ℃, 57 ℃, 58 ℃, 59 ℃, 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, 65 ℃, or the like. The heating time may be, for example, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, or the like.

The present invention will be described in further detail with reference to specific examples. It is to be understood that the following embodiments are merely illustrative or examples of the application of the principles of the present invention. Numerous variations and alternative compositions, methods, and systems may be devised by those skilled in the art without departing from the spirit and scope of the present invention and fall within the scope of the appended claims.

Some of the raw materials used in the examples of the present invention are shown in table 1 below. The OH, NCO group percentages in table 1 are the mass percentages of the corresponding groups in the corresponding aqueous polyol (solids) and aqueous isocyanate curing agent (solids).

Table 1 example raw materials

Raw material name	Specific substances and Properties
		Bayhydrol A 2695	Aqueous acrylic dispersion, OH% = 5%
Bayhydrol A 145	Aqueous acrylic dispersion, OH% = 3.3%
		Bayhydrol U 2755	Aqueous polyester polyurethane dispersion, OH% = 3%
Bayhydrol U 2766	Aqueous polycarbonate polyurethane dispersion, OH% = 4%
		Bayhydur 2655	Sulfonate modified HDI trimer, NCO% = 20%
Bayhydur 401-70	Hydrophilically modified IPDI trimer, NCO% = 9.4%

The nano-microspheres, the auxiliary agent and the base material used in the examples and the comparative examples of the present invention are the same.

Example 1

The preparation method of the photonic crystal film of the embodiment comprises the following steps:

step (1): preparation of photonic crystal coating composition: uniformly mixing 60g of nano microspheres, 30g Bayhydrol A2695, 10g Bayhydur 2655 and 0.5g of auxiliary agent to obtain a photonic crystal coating composition;

step (2): coating the coating composition of the photonic crystal film on a PET substrate, drying at a low temperature of 60 ℃ for 60 seconds, and compounding the PET substrate to obtain a compound film;

step (3): carrying out regularization treatment on the composite film for 5min to obtain a microsphere crystallized composite film;

step (4): and heating the crystallized composite film to 60 ℃ and curing for 24 hours to obtain the photonic crystal film with fixed microsphere crystallization.

Examples 2 to 6

Photonic crystal films of examples 2 to 6 were prepared in the same manner as in example 1, except that the raw material formulation was changed according to Table 2.

Comparative example 1

According to the same procedures (1) to (3) as in example 1 except that the raw material formulation was changed in accordance with Table 2, a microsphere crystallized composite film was prepared, and after the procedure (3), UV oligomer+monomer polymerization was initiated by irradiation with a high-pressure mercury lamp with an accumulated light amount of 1000mJ/cm by the photo-curing method disclosed in patent document CN202010213864 ² 。

Each of examples and comparative example 1 was subjected to performance tests of reflection wavelength, barrier property, light transmittance, haze, pencil hardness, impact resistance, and the like. The formulations and performance test results of each example and comparative example 1 are shown in fig. 1 and table 2 below. The amounts of the components in each formulation in Table 2 are parts by mass, and the amounts of the aqueous polyol, aqueous isocyanate, and UV oligomer+monomer are all amounts of solids (excluding solvents).

Table 2 formulation and performance test results for example and comparative example 1

As is clear from the above-mentioned performance test results, the thermal initiator solutions of examples 1 to 6 of the present invention have higher barrier and light transmittance and lower haze, and have higher hardness and impact resistance, and better comprehensive mechanical properties, compared to comparative example 1 using a photo-curing system.

Comparative example 2

The preparation method of the photonic crystal film of the comparative example has the following steps:

step (1): preparation of photonic crystal coating composition: uniformly mixing 60g of nano microspheres, 40g of aqueous polyurethane emulsion (40 g is the solid content of the aqueous polyurethane) and 0.5g of flatting agent to obtain a photonic crystal coating composition;

step (4): and heating the crystallized composite film to 60 ℃ for 24 hours to obtain the photonic crystal film with immobilized microsphere crystallization.

In comparative example 2, the photonic crystal film is prepared by adopting aqueous polyurethane emulsion, the aqueous polyurethane has large molecular weight, can prevent microspheres from being orderly arranged, causes poor structural color effect, cannot obtain a large-area orderly photonic crystal structure, and test results show that the reflection peak reflectivity of the reflection spectrum of the obtained coating is low, the light transmittance is lower than 80%, and the haze is higher than 4%.

Comparative example 3

step (1): preparation of photonic crystal coating composition: uniformly mixing 60g of nano microspheres, 30g of polyethylene glycol, 10g of aliphatic isocyanate and 0.5g of flatting agent to obtain a photonic crystal coating composition;

In comparative example 3, aliphatic isocyanate was used as the isocyanate component, and the pencil hardness of the obtained photonic crystal film was HB, and the impact resistance test result was 30kg.cm, and the mechanical properties were inferior to those of examples 1 to 6.

Finally, it should be emphasized that the above description is merely of a preferred embodiment of the invention, and is not intended to limit the invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The photonic crystal coating composition is characterized by comprising the following raw materials in parts by mass: 10-40 parts of aqueous polyol, 2-20 parts of aqueous isocyanate curing agent, 50-80 parts of nano-microspheres and 0-2 parts of auxiliary agent, wherein the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent are uniformly dispersed.

2. The photonic crystal coating composition according to claim 1, characterized in that the mass parts of the raw materials are: 22.5 to 40 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 50 to 70 parts of nano microsphere and 0 to 2 parts of auxiliary agent;

preferably, the weight parts of the raw materials are as follows: 22.5 to 30 parts of aqueous polyol, 7.5 to 15 parts of aqueous isocyanate curing agent, 55 to 70 parts of nano microsphere and 0.5 to 1 part of auxiliary agent.

3. A photonic crystal coating composition according to claim 1, characterized in that the aqueous polyol is selected from at least one of aqueous hydroxyurethane, aqueous hydroxyacrylate, aqueous polyurethane dispersion containing hydroxyl groups; and/or

The aqueous isocyanate curing agent is at least one selected from hydrophilically modified 1, 6-hexamethylene diisocyanate, hydrophilically modified isophorone diisocyanate polymer or aqueous polyurethane prepolymer containing isocyanate groups.

4. A photonic crystal coating composition according to claim 2, characterized in that said aqueous isocyanate curing agent is an isocyanate curing agent with sulfonic acid or salt groups thereof.

5. A photonic crystal coating composition according to any one of claims 1 to 3, characterized in that the mass percentage of hydroxyl groups in the aqueous polyol is 0.5-6%, preferably 3-5%; and/or

The weight percentage of isocyanate groups of the aqueous isocyanate curing agent is 5% -30%, preferably 9.4% -20%.

6. A photonic crystal coating composition according to any one of claims 1 to 3, characterized in that said nano-microspheres are selected from at least one of polymer microspheres, inorganic microspheres and polymer-inorganic composite microspheres; the polymer microsphere is at least one selected from polystyrene microsphere and core-shell structure polymer microsphere, and the inorganic microsphere is at least one selected from silicon dioxide, titanium dioxide, ferroferric oxide and zinc sulfide; and/or

The average particle diameter of the nano microsphere is 100-400 nm, and the polydispersity index PDI is not more than 0.15.

7. A photonic crystal coating composition according to claim 5, characterized in that said nanomicrospheres are dispersed three-dimensionally in an ordered manner in a mixture comprising said aqueous polyol, said aqueous isocyanate curing agent and said auxiliary agent.

8. A photonic crystal film comprising a substrate, characterized by further comprising the photonic crystal coating composition according to any one of claims 1 to 6, said photonic crystal coating composition being coated on said substrate;

preferably, the substrate is selected from at least one of polyethylene terephthalate, polyethylene terephthalate-1, 4-cyclohexanedimethanol ester, polymethacrylate, polyvinyl alcohol, polynaphthalate, polycarbonate, polyurethane, acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, thermoplastic polyurethane elastomer, polyvinylidene fluoride, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyolefin.

9. The photonic crystal film according to claim 8, wherein the photonic crystal film has a light transmittance of not less than 88%, a haze of not more than 2.3%, a pencil hardness of higher than HB, and an impact resistance of higher than 35kg.cm.

10. The method for producing a photonic crystal film according to claim 8 or 9, characterized by comprising the steps of:

mixing the aqueous polyol, the aqueous isocyanate curing agent, the nano-microspheres and the auxiliary agent to obtain an aqueous coating liquid;

coating the aqueous coating liquid on the substrate, drying, and carrying out vibration shearing regularization treatment and curing to obtain the photonic crystal film;

preferably, the aqueous polyol and the aqueous isocyanate curing agent are used in the form of an aqueous dispersion; the curing step comprises heating at 50-65 ℃ for 20-30 hours.