CN111171619A - Photochromic coating and preparation method thereof - Google Patents

Abstract

A photochromic coating and its preparation method, contain polyurethane/compound of formula (III)/zinc sulfide compound multi-layer photochromic material in this coating, its inner core is the mesoporous nanometer microballoons of zinc sulfide, the intermediate layer is the photochromic layer that compound of formula (III) forms, the outer cover is polyurethane; the composite microsphere has the outer diameter of 50-350nm, wherein the diameter of the zinc sulfide mesoporous nano microsphere is 30-250 nm, the thickness of the middle layer is 2-25 nm, and the thickness of the shell is 5-25 nm. The photochromic coating prepared by the method can be used as a surface color changing layer of an optical color changing material or an optical lens, can be changed into a color from a colorless state under the irradiation of ultraviolet rays, can be quickly faded into the colorless state after the ultraviolet rays disappear, and has the advantages of strong fatigue resistance, stabilityGood performance, fast color changing speed and the like.

Description

Photochromic coating and preparation method thereof

The application is a divisional application of a patent application of spiropyran photochromic coating and a preparation method thereof, and has an original application number: 201711110838.6, filing date originally: 11/10/2017.

Technical Field

The invention belongs to the technical field of photochromism, and particularly relates to a photochromism coating containing photochromism nano composite microspheres and a preparation method thereof.

Background

Photochromic refers to a functional material which is a compound, under the action of light with certain wavelength and intensity, and the molecular structure of the material is changed along with the change of an absorption spectrum, so that the absorbance and the color of the material are changed, the change is generally reversible, and the material can automatically recover to the original state after the light is stopped, and the photochromic material is used as a new material in the field of optical material subdivision and has important application value in the technical fields of optical lenses, optical information storage, molecular switches, anti-counterfeiting identification and the like. The phenomenon of photochromism has been found by humans for over a hundred years. The first successful commercial application, starting in the 60's of the 20 th century, two materials scientists, amistod and Stooky, in the Corning studio of the united states, first prepared photochromic materials containing silver halide glasses, and then a great deal of research into their mechanisms and applications, and the development of new photochromic eyewear. However, due to its high cost and complex processing technology, it is not suitable for manufacturing large-area photochromic glass, and thus, its commercial application in the building field is limited. Then, the application center of gravity of photochromism is shifted to polymer-based materials with low price and light weight, and the photochromism compound is added into transparent resin to prepare the photochromic material which can be used for resin spectacle lenses and is applied to photochromic spectacles at home and abroad. Silver halide photochromic materials have been phased out because they are not suitable for use with resin lenses. The application of the organic photochromic compound on the resin lens at present mainly comprises the following types: spiroindoline naphthoxazines, naphthopyrans, fulgide photochromic compounds, and the like. Although important achievements are achieved in the aspect of practical application, the disadvantages of poor light stability, low photochromic response value, insufficient thermal stability and the like of the photochromic compound exist, such as: photochromic compounds are susceptible to the influences of pH value, oxidation, illumination intensity, temperature, matrix environment and the like to cause the deterioration of photochemical fatigue, and are degraded and deteriorated after repeated irradiation for many times to lose reversible photochromic performance, or the conditions of prolonged color change response time, reduced chromaticity, delayed fading recovery time and the like are caused.

The light stability, namely fatigue resistance, of the color-changing compound is one of the important problems of the color-changing compound in practical application. The research on photochromic mechanism shows that the main reason for fatigue is that the compound is photooxidation degraded during the photoisomerization reaction, and the fatigue phenomenon occurs. Therefore, antioxidant research has become a major approach for compounds to improve fatigue resistance. At present, the following methods are mainly utilized to improve the fatigue resistance: firstly, adding a light stabilizer or an antioxidant into a polymer medium containing a color-changing compound; secondly, directly keying antioxidant groups on compound molecules; thirdly, introducing an electricity-rich heteroaryl group into a side chain of a compound molecule; and fourthly, improving the fatigue resistance by adding a single-base peroxy quencher or adopting a spin-trapping agent. Therefore, researchers have improved performance by microencapsulating color-changing compounds, such as: patent ZL200810057392 discloses a preparation method of photochromic microcapsules, which can improve the acid and alkali resistance and fatigue resistance of photochromic materials and prolong the service life. The patent ZL201410195430.3 discloses a preparation method of a polyurethane-chitosan double-shell photochromic microcapsule, and double-layer coating can further improve the coating rate, fatigue resistance and the like of photochromic compounds. Therefore, the development of compounds and composite materials with good photochromic performance has become one of the research hotspots of photochromic materials in recent years, and particularly, the development of the photochromic materials with excellent fatigue resistance, good thermal stability and high spectral response value has higher popularization and application values.

In addition, photochromic properties are also often affected by the polymer molecules, other chemical aids in the matrix, the microstructure, the polymerization environment, etc., such as: the color-changing compound is greatly influenced by the ultraviolet absorbent in the polymer, and the color-changing compound is greatly limited by the excitation of ultraviolet spectrum to change color due to the absorption of ultraviolet rays by the ultraviolet absorbent in the polymer, so that the color-changing efficiency is low; meanwhile, the existence of diopter leads to the inconsistency of the edge thickness and the center thickness of the lens, in this case, if the method of adding the color-changing compound in the body is still adopted, the color depth chromatic aberration of different positions of the thickness of the lens can be caused. Therefore, some manufacturers in China use spin coating to produce color-changing lenses. The spin coating method is that after the substrate is made, the prepared color-changing solution is added into a groove of a spin coater, after the color-changing solution is fully mixed, the substrate is fixed on the spin coater to carry out centrifugal rotation movement, and the substrate is solidified to form a product with the color-changing effect.

Disclosure of Invention

The invention aims to provide a photochromic coating and a preparation method thereof, wherein the coating contains a polyurethane/compound of formula (III)/zinc sulfide composite multilayer photochromic material which can be used as an optical photochromic material or a surface color changing layer of an optical lens, the coating can be changed into color from colorless under the irradiation of ultraviolet rays, and the coating can be quickly faded into colorless after the ultraviolet rays disappear, and the coating has the advantages of strong fatigue resistance, good stability, high color changing speed and the like.

In order to achieve the purpose, the invention provides the following technical scheme:

a photochromic coating comprises polyurethane/a compound of formula (III)/zinc sulfide photochromic composite microspheres, wherein the photochromic composite microspheres are of a three-layer composite core-shell structure, the inner core of the photochromic composite microspheres is zinc sulfide mesoporous nano microspheres, the middle layer of the photochromic composite microspheres is a photochromic layer formed by the compound of formula (III), and the outer shell of the photochromic composite microspheres is polyurethane; the composite microsphere has an outer diameter of 50-350nm, wherein the diameter of the zinc sulfide mesoporous nano microsphere is 30-250 nm, the thickness of the middle layer is 5-25 nm, and the thickness of the shell is 5-25 nm

As mentioned above, preferably, the zinc sulfide mesoporous nanospheres are monodisperse zinc sulfide mesoporous nanospheres composed of zinc sulfide nanocrystals, and the intermediate layer is formed by uniformly dispersing the compound nanoparticles of formula (III) on the surface or in the gaps of the zinc sulfide mesoporous nanospheres to form a nanocomposite mesoporous structure.

In the photochromic coating layer, the polyurethane is preferably formed by polymerizing an isocyanate monomer compound containing two or more isocyanate groups and an alcohol compound.

The photochromic coating as described above, preferably, the isocyanate monomer compound is selected from: at least one of toluene diisocyanate, diphenylmethane-4, 4' -diisocyanate, 1, 6-hexamethylene diisocyanate, m-xylylene diisocyanate, naphthalene-1, 5-diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and isophorone diisocyanate;

the alcohol compound is at least one of n-butyl alcohol, polytetrahydrofuran ether glycol, pentaerythritol, ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and trimethylolpropane.

The photochromic coating is preferably prepared by dispersing polyurethane/compound of formula (III)/zinc sulfide photochromic composite microspheres in polythiourethane, wherein the weight ratio of the photochromic composite microspheres to the polythiourethane is 1: 8.6-37.5.

In the photochromic coating layer, the polythiourethane is preferably obtained by polymerizing a polythiourethane monomer, which is at least one of 2, 2 '-dimercaptoethylsulfide, 2' -dimercaptoethylthioethane, 2, 3-dimercaptoethylthiopropanethiol, and 1, 2, 3-trimercaptoethylthiopropane.

In another aspect, the present invention provides a method for preparing a photochromic coating layer as described above, comprising the steps of:

I. coating solutions were prepared with the following two components:

(1) a component A:

uniformly stirring the components according to the proportion at room temperature for 15-30 minutes to obtain a component A;

(2) b, component B:

isocyanate type curing agent 12-17

Catalyst 0-1

Defoaming agent 0-1

Uniformly stirring the components according to the proportion at room temperature for 3-5 minutes to obtain a component B;

II, during coating, uniformly mixing the component A and the component B according to the mass ratio of (70-100) to (12-19), and adding a diluent to adjust the viscosity to obtain photochromic coating liquid; the photochromic coating layer is produced by applying a photochromic coating liquid onto the surface of an optical substrate to form a coating layer and then curing the coating layer by light irradiation or heating.

In the above production method, preferably, the isocyanate-type curing agent is at least one of a toluene diisocyanate curing agent, a diphenylmethane-4, 4' -diisocyanate curing agent, a 1, 6-hexamethylene diisocyanate curing agent, an m-xylylene diisocyanate curing agent, a methylcyclohexyl diisocyanate curing agent, and an isophorone diisocyanate curing agent;

the catalyst is dibutyltin dilaurate;

the diluent is at least one of dichloromethane, butyl acetate, methyl acetate, ethanol, butanol, acetone, toluene, xylene, diethyl ether and polytetrahydrofuran ether glycol;

the wetting dispersant is a BYK polyurethane type special wetting dispersant or an F420 type wetting dispersant;

the leveling agent is an oily F300 type leveling agent, an F309 type leveling agent or an F320 type leveling agent;

the defoaming agent is XPJ01F type modified silicone oil defoaming agent.

In yet another aspect, the present invention provides a photochromic coating layer prepared by the method as described above.

The compound of formula (III) according to the present invention can be synthesized by, but is not limited to, the following method.

Synthesis of photochromic compound (III):

the first step is as follows: heating 4-hydroxy-6, 7-dimethoxy-1-phenyl-2-naphthoic acid, o-xylene and polyphosphoric acid to 120-160 ℃ according to the mass ratio of (0.8-1.2) to (1.5-2.5) to (0.8-1.2), reacting for 1-2H, pouring the reaction liquid into water, filtering, and drying in vacuum to obtain 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ] fluorene-7-ketone;

the second step is that: reacting tetrahydrofuran with 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ]]Mixing fluorene-7-ketone in the mass ratio of 0.6-1 to 1 at-10-20 deg.c and dropping methyl magnesium chloride in the concentration of 3.0MMethyl magnesium chloride and 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ]]The mass ratio of the fluorene-7-ketone is (0.6-1.2) to (0.7-1.2), and the temperature is controlled not to exceed-10 ℃ in the dropping process. After the dropwise addition is finished, the temperature is kept between minus 10 ℃ and minus 15 ℃ for reaction for 90 to 120 minutes, saturated ammonium chloride solution is added for quenching reaction, the mass ratio of ammonium chloride to methyl magnesium chloride is (1-3) to 1, liquid separation is carried out, an aqueous layer is extracted by ethyl acetate, organic layers are combined, and anhydrous Na₂SO₄Drying, vacuum evaporating solvent, and performing column chromatography to obtain 2, 3-dimethoxy-7-methyl-7H-benzo [ c ]]Fluorene-5, 7-diol;

the third step: 2, 3-dimethoxy-7-methyl-7H-benzo [ c ]]Fluorene-5, 7-diol, toluene, 1-di (4-methoxyphenyl) -2-propyn-1-ol and p-toluenesulfonic acid (TsOH) according to the mass ratio: mixing (0.7-1.0) to (4-6) to (0.6-1.0) to (0.1-0.3), heating to 65-95 deg.C for 10-16h, vacuum evaporating toluene, adding saturated sodium bicarbonate solution for quenching reaction, mixing sodium bicarbonate solution and p-toluene at a mass ratio of (0.3-0.6) to 1, separating, extracting with ethyl acetate in water layer, mixing organic layers, and adding anhydrous Na₂SO₄Drying, removing the solvent by evaporation under reduced pressure, and subjecting the crude product to column chromatography (petroleum ether: ethyl acetate: 15: 1 elution) to obtain photochromic compound (III).

The main reaction process is that 4-hydroxy-6, 7-dimethoxy-1-phenyl-2-naphthoic acid is cyclized under the acid condition to obtain an intermediate 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ] fluorene-7-ketone; and reacting with methyl Grignard reagent-magnesium chloride to obtain 2, 3-dimethoxy-7-methyl-7H-benzo [ c ] fluorene-5, 7-diol; then the photochromic compound (III) is generated by the photochromic compound (III) and 1, 1-di (4-methoxyphenyl) -2-propyne-1-alcohol under the catalysis of p-toluenesulfonic acid, and the specific reaction formula is as follows:

the acid in the reaction is acetic acid, trifluoroacetic acid, phosphoric acid, sulfuric acid or polyphosphoric acid, preferably polyphosphoric acid.

The photochromic nano composite microsphere is a polyurethane/compound of formula (III)/zinc sulfide three-layer composite core-shell structure, the inner core of the photochromic nano composite microsphere is a zinc sulfide mesoporous nano microsphere, and in the preferred technical scheme of the invention, the preparation route of the zinc sulfide mesoporous nano microsphere is as follows: condensing ethylene glycol at high temperature to produce acetaldehyde, providing a hydrogen atom, and using the acetaldehyde as a reducing agent to change S into S^2-Followed by release of Zn from zinc nitrate hexahydrate²⁺And S^2-Combining to form ZnS crystal nucleus which grows continuously based on a diffusion mechanism, so that initial particles of the reaction, namely zinc sulfide nanocrystals are gradually aggregated to form secondary particles, namely zinc sulfide nanospheres; when nucleation reaches a certain stage, mercaptoethanol plays an important role in the reaction process, on one hand, the mercaptoethanol effectively prevents the agglomeration of a large number of particles, on the other hand, the continuous growth of the particles is limited, and the nucleation of the nanocrystals is gradually stopped along with the reduction of the ion concentration, wherein the specific nucleation reaction equation is as follows:

HOCH₂CH₂OH→CH₃CHO+H₂O (1)

S+2CH₃CHO→CH₃CO-OCCH₃+S^2-+2H⁺(2)

Zn²⁺+S^2-→ZnS(s) (3)

the prepared zinc sulfide nano microsphere is formed in the nucleation process of zinc sulfide nano crystals, and is a monodisperse zinc sulfide mesoporous nanosphere consisting of a plurality of small nano crystals.

The compound of formula (III) added subsequently is uniformly dispersed on the surface and in the gaps of the zinc sulfide microspheres in the form of nanoparticles. And finally, covering by using polyurethane as a shell to form the nano composite core-shell structure.

As shown in fig. 7, the appearance of the photochromic nano-composite microsphere is spherical, wherein the dark core is composed of a plurality of uniformly sized and monodisperse zinc sulfide nanospheres, the light-colored outer layer is the compound of formula (III), and the polyurethane outer shell is a colorless transparent material, so that the photochromic nano-composite microsphere cannot be displayed and distinguished in a transmission electron microscope photograph.

The invention has the beneficial effects that: the photochromic coating contains photochromic nano composite microspheres with a polyurethane/compound of formula (III)/zinc sulfide three-layer composite core-shell structure, the compound of formula (III) is positioned between a shell and a core as a photochromic compound, namely a middle layer, the three-dimensional space is in a nanoscale range, and the energy level change and the energy gap widening brought by the quantum size effect are realized. On one hand, the unique structure can ensure that the color-changing compound is protected by a polyurethane shell with relatively stable property, and the color-changing compound is prevented from being influenced by the external environment; on the other hand, due to the stable supporting effect of the core zinc sulfide nano mesoporous structure, the Van der Waals area of the color-changing molecules is enlarged, the conjugated system is enlarged, the space volume of the molecules is enlarged, and the gaps between the molecules are enlarged, so that the space for the molecules to generate isomerization reaction is greatly increased, the activity of the color-changing body is enhanced, the obstruction of conversion between the color-changing open ring body and the colorless closed ring body is reduced, the conversion time is shortened, the speed is accelerated, the spectral response becomes more sensitive, and the color-changing effect is good. In addition, under the illumination condition, the polyurethane shell can absorb part of light, part of incident ultraviolet rays are absorbed by the zinc sulfide core, and the light intensity irradiated on the surface of the compound of the formula (III) is lower than that directly irradiated on the surface of the compound of the formula (III); meanwhile, the irradiation intensity and the irradiation retention time required for exciting the discoloration of the compound of the formula (III) are not influenced, and the residual ultraviolet rays are absorbed by the zinc sulfide core. Therefore, the oxidation resistance and fatigue resistance of the polyurethane/compound shown in the formula (III)/zinc sulfide nano composite microsphere are obviously enhanced.

The photochromic coating can be changed into color from colorless under the irradiation of ultraviolet rays, and can be quickly faded into colorless after the ultraviolet rays disappear, and the photochromic coating has the advantages of strong fatigue resistance, good stability, high color changing speed and the like.

Drawings

FIG. 1 is a normal environmental absorption spectrum chart of polyurethane/compound of formula (III)/zinc sulfide nano-composite microsphere prepared in example 1.

FIG. 2 is a high-temperature environment absorption spectrum diagram of the polyurethane/compound of formula (III)/zinc sulfide nano-composite microsphere prepared in example 1.

FIG. 3 is a normal ambient absorption spectrum of photochromic compound (III).

FIG. 4 is a high-temperature environment absorption spectrum of the photochromic compound (III).

FIG. 5 is a normal environment absorption spectrum of the polyurethane/compound of formula (III) nanocomposite microsphere prepared in comparative example 2.

FIG. 6 is a high-temperature environment absorption spectrum of the polyurethane/compound nano-composite microsphere of formula (III) prepared in comparative example 2.

Fig. 7 is a transmission electron microscope photograph of the photochromic nanocomposite microsphere prepared in example 1.

FIG. 8 is an infrared spectrum of the photochromic nanocomposite microsphere prepared in example 1 with pure zinc sulfide, the compound of formula (III), and polyurethane.

Detailed Description

The invention is further illustrated by the following specific examples, which are not intended to limit the scope of the invention.

The compounds of formula (III) in the following examples and comparative examples were prepared by the following method:

preparing a photochromic compound represented by formula (III):

the first step is as follows: uniformly stirring and mixing 90g of 4-hydroxy-6, 7-dimethoxy-1-phenyl-2-naphthoic acid, 170g of o-xylene and 85g of polyphosphoric acid, heating to 145 ℃, reacting for 90 minutes, pouring the reaction liquid into water, filtering, and drying in vacuum to obtain 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ] fluorene-7-ketone;

the second step is that: taking 75g of tetrahydrofuran and 95g of 5-hydroxy-2, 3-dimethoxy-7H-benzo [ c ]]Mixing fluoren-7-one, cooling to-12 deg.C, adding dropwise methyl magnesium chloride 80g with concentration of 3.0M, reacting at-10 deg.C for 100 min, adding saturated ammonium chloride solution 150g, extracting water layer with ethyl acetate (170mL × 3), combining organic layers, and adding anhydrous Na₂SO₄Drying, vacuum evaporating solvent, and performing column chromatography to obtain 2, 3-dimethoxy-7-methyl-7H-benzo [ c ]]Fluorene-5, 7-diol;

the third step: 40g of 2, 3-dimethoxy-7-methyl-7H-benzo [ c ]]Fluorene-5, 7-diol, 250g toluene, 42g1, 1-bis (4-methoxyphenyl) -2-propyn-1-ol, 9g p-toluenesulfonic acid, stirring and mixing homogeneously, heating to 75 deg.C for reaction for 15 hours, vacuum evaporating toluene, adding 110g saturated sodium bicarbonate solution to quench the reaction, extracting the aqueous layer with ethyl acetate (90 mL. times.3), combining the organic layers, anhydrous Na₂SO₄Drying, decompressing and distilling off the solvent, and carrying out column chromatography on the crude product to obtain the photochromic compound shown in the formula (III).

Example 1: preparation of photochromic nano composite microspheres, photochromic coating liquid and photochromic lens

Preparing photochromic nano composite microspheres:

(1) adding 9.7g of zinc nitrate hexahydrate into 1600g of ethylene glycol, stirring uniformly, adding 1.6g of sublimed sulfur powder, heating to 150 ℃, keeping the temperature, reacting for 24 hours, cooling to 55 ℃, dropwise adding 85g of mercaptoethanol, and stirring; then adding 6.7g of photochromic compound shown in the formula III, stirring vigorously for 30 minutes, continuing cooling to room temperature, filtering and washing the precipitate, and drying in a vacuum drying oven at 65 ℃ for 8 hours to obtain the compound-coated zinc sulfide nanosphere shown in the formula (III);

(2) adding 8g of compound-coated zinc sulfide nanosphere of formula (III), 8.2g of diphenylmethane-4, 4' -diisocyanate (MDI) into 1000g of butyl acetate solvent, stirring uniformly, adding 7g of mixed reactants (1.2g of n-butyl alcohol, 5.8g of polytetrahydrofuran ether glycol) and 18g of Tween80 respectively, keeping the temperature at 20 ℃, carrying out prepolymerization reaction at the rotating speed of 500r/min for 60min, adding 9.2g of chain extender (6 g of ethylene glycol and 3.2g of ethylenediamine) and 0.1g of catalyst dibutyltin Dilaurate (DBTL), heating to 60 ℃ for carrying out polymerization chain extension reaction for 15min, stirring at the speed of 1200r/min, filtering, washing and drying solid substances to obtain the polyurethane/compound-coated zinc sulfide nanocomposite microsphere of formula (III). The yield was 75%.

(3) observing the product prepared in the step (2) by using a JEM-2100 type transmission electron microscope, as shown in fig. 7, showing that the appearance is spherical, wherein the darker inner core is composed of a plurality of uniformly sized and monodisperse zinc sulfide nanospheres, the lighter outer layer is a shell formed by the compound of the formula (III) and polyurethane, the composite microsphere with a core-shell structure can be formed by adsorbing the compound of the formula (III) by the zinc sulfide nanospheres with larger specific surface area and pore volume and coating the compound of the formula (III) by the polyurethane, and the polyurethane outer shell is a colorless transparent material, so that the composite microsphere with the core-shell structure cannot be displayed and distinguished in a transmission electron microscope picture.

(4) The product prepared in step (2) was tested for Fourier transform Infrared Spectroscopy (FT-IR) and the spectrogram was compared with the IR spectrogram of pure zinc sulphide, compound of formula (III) and polyurethane. The results are detailed in FIG. 8, in which curve a is an infrared spectrum of zinc sulfide; b is the infrared spectrogram of the compound III; the curve c is an infrared spectrogram of the polyurethane material; the d curve is the infrared spectrum of the photochromic nanocomposite microsphere prepared in example 1.

From the curve a analysis in the figure, 3421Gm^-1The wider absorption peak is O-H stretching vibration peak, 1620cm^-1The absorption peak is the bending vibration peak of H-O-H, which is the characteristic absorption peak of water and can be attributed to the water adsorption on the surface of ZnS powder at 900-4000cm^-1There was substantially no absorption peak in the range, indicating that the ZnS powder has a good infrared transmittance.

From the analysis of the b curve in the figure, 3430cm^-1Absorption peak of stretching vibration at-OH, 2960Gm^-1Is represented by-CH₃Absorption peak of expansion vibration, 1640-1477cm^-1Vibration absorption peak ascribed to benzene ring, 1366cm^-1is-CH₃Flexural vibration absorption Peak, 960cm^-1Is represented by-CH₃Absorption peak of stretching vibration, 820cm^-1Vibrations ortho-disubstituted with benzene ringsAbsorption peak.

From the curve analysis of c in the figure, the absorption peak at 3251-3480 is the stretching vibration peak of polyurethane hydroxyl-OH; 2270cm^-1The strong absorption peak is generated by the stretching vibration of the-NCO group, other groups do not generate absorption at the peak, and the peak is the characteristic absorption peak of the isocyanate.

From the d curve analysis in the figure, 3430cm^-1Stretching vibration absorption peak at-OH, 2270cm^-1The disappearance of the vibration absorption peak indicates the absence of-NCO groups because the MDI monomer is completely reacted and the isocyanate has reacted with the compound containing weak active hydrogen atoms to form carbamate, 1706cm^-1The absorption peak at (a) represents the vibration absorption peak of-C ═ O in the polyurethane; 1460cm^-1The absorption peak at is CH₂Vibration absorption peak or CH of group (methylene)₃Despite the wave number (1366 cm) absorbed by the compound of formula (III) molecule^-1) The inconsistency is probably caused by that after the compound molecule of the formula (III) is adsorbed on the ZnS nano particle, the absorption spectrum is shifted due to the interaction between different molecules; 1224cm^-1The absorption peak at (A) is a vibration absorption peak of the ether bond-C-O-C-.

By comparison, the infrared spectrogram of the photochromic nanocomposite microsphere prepared in example 1 not only has the characteristic absorption peak of the photochromic compound shown in formula (III), but also comprises the characteristic absorption peak of polyurethane, which indicates that the photochromic nanocomposite microsphere prepared in example 1 is not a single zinc sulfide substance, and also comprises the photochromic compound shown in formula (III) and a polyurethane substance.

(II) preparing a photochromic coating liquid:

1. preparing a polyurethane component A: 675g of 2, 3-dimercaptoethyl thiopropanethiol (BES) monomer, 120g of dichloromethane, 35g of polyurethane/compound of formula (III)/zinc sulfide nano-composite microspheres, 15g F420 wetting dispersant (product of Orner Polymer Co., Ltd., Fushan City), and 5g F300 leveling agent (product of Orner Polymer Co., Ltd., Fushan City) are added into a container, and the mixture is uniformly stirred at room temperature for 25min to obtain a component A;

2. preparing a polyurethane component B: adding 145g of m-xylylene diisocyanate curing agent, 4g of XPJ01F defoamer (product of Jiangsu Sail Xinyue defoamer Co., Ltd.), and 1g of DBTL catalyst into a container, and uniformly stirring for 5 minutes at room temperature to obtain a component B;

3. preparing a photochromic coating liquid: uniformly mixing the component A and the component B, and subpackaging in A, B containers, wherein the container A is 600g and is a first photochromic coating solution; 400g of container B, and 26g of methylene chloride was added to container B to obtain a second photochromic coating solution.

(III) preparing a photochromic lens:

soaking the polyurethane optical lens base material cleaned by NaOH into the first photochromic coating liquid for 3 minutes at room temperature, then slowly pulling the lens at the speed of 1.0mm/s, raising the speed to 1.3mm/s after 85 seconds, moving the lens into an oven, setting the temperature at 45 ℃, and baking for 80 minutes; and spraying the lens by using a second photochromic liquid, and curing to obtain the photochromic lens. Wherein the thickness of the coating was 45 μm.

Example 2:

preparing photochromic nano composite microspheres:

(1) adding 8g of zinc nitrate hexahydrate into 1600g of ethylene glycol, uniformly stirring, adding 2.5g of sublimed sulfur powder, heating to 150 ℃, reacting for 23 hours while keeping the temperature, cooling to 50 ℃, dropwise adding 82g of mercaptoethanol, and stirring; then adding 5.2g of the compound shown in the formula (III), stirring vigorously for 35 minutes, cooling to room temperature, filtering and washing the precipitate, and drying in a vacuum drying oven at 60 ℃ for 9 hours to obtain the compound shown in the formula (III) coated zinc sulfide nanospheres;

(2) adding 6.6g of compound-coated zinc sulfide nanosphere of formula (III), 5.6g of Toluene Diisocyanate (TDI) into 1000g of butyl acetate solvent, stirring uniformly, sequentially adding 6.3g of mixed reactants (0.9g of n-butyl alcohol, 5.4g of polytetrahydrofuran ether glycol) and 14g of Tween80, keeping the temperature at 25 ℃, carrying out prepolymerization reaction at the rotating speed of 700r/min for 60min, adding 5.5g of chain extender (4.5 g of ethylene glycol, 1g of ethylenediamine) and 0.1g of DBTL, heating to 60 ℃, carrying out polymerization chain extension reaction for 15min, stirring at the speed of 1500r/min, filtering, washing and drying solid substances, thus obtaining the polyurethane/compound-zinc sulfide nanocomposite microsphere of formula (III). The yield was 74%.

The JEM-2100 type TEM photograph of the product is similar to that of FIG. 7.

(II) preparing a photochromic coating liquid:

1. preparing a polyurethane component A: adding 640g of BES monomer, 110g of dichloromethane, 25g of polyurethane/compound of formula (III)/zinc sulfide nano composite microspheres, 17g F420 wetting dispersant and 5g F309 flatting agent into a container, and uniformly stirring at room temperature for 25min to obtain a component A;

2. preparing a polyurethane component B: adding 110g of m-xylylene diisocyanate curing agent, 9g of XPJ01F defoaming agent and 7g of DBTL catalyst into a container, and uniformly stirring for 5 minutes at room temperature to obtain a component B;

3. preparing a photochromic coating liquid: uniformly mixing the component A and the component B, and subpackaging in A, B containers, wherein the container A is 700g and is a first photochromic coating solution; in the B vessel 223g, 15g of methylene chloride was added to the B vessel to obtain a second photochromic coating solution.

(III) preparing a photochromic lens:

soaking the hardened polyurethane optical lens base material into the first photochromic coating liquid for 3 minutes at room temperature, then slowly lifting the lens, wherein the lifting speed is 1.1mm/s, the speed is increased to 1.34mm/s after 85 seconds, moving the lens into an oven, setting the temperature at 45 ℃, and baking for 70 minutes; and spraying the lens by using a second photochromic liquid, and curing to obtain the photochromic lens. Wherein the coating thickness was 43 μm.

Comparative example 1:

photochromic coating liquids and photochromic lenses were prepared using the same operating conditions as in the steps (two) and (three) of example 1, except that the compound of formula (III) was used instead of the polyurethane/compound of formula (III)/zinc sulfide nanocomposite microspheres in the preparation of the photochromic coating liquids.

Comparative example 2:

(1) the same operating conditions as in steps (one) - (2) of example 1 were adopted, except that the compound of formula (III) was used instead of the compound of formula (III) to coat the zinc sulfide nanospheres, to obtain polyurethane/compound of formula (III) nanocomposite microspheres.

(2) And (2) preparing photochromic coating liquid and photochromic lenses by adopting the same operation conditions as the steps (II) and (III) of the example 1, except that the polyurethane/compound of the formula (III) nano composite microspheres obtained in the step (1) are used for replacing the polyurethane/compound of the formula (III)/zinc sulfide nano composite microspheres in the preparation process of the photochromic coating liquid.

Example 3: the photochromic materials prepared in example 1 and comparative examples 1 to 2 were respectively subjected to oxidation resistance tests

Respectively carrying out absorption spectrum detection on the polyurethane/compound shown in the formula (III)/zinc sulfide nano composite microspheres prepared in the example 1, the compound shown in the formula (III) and the polyurethane/compound shown in the formula (III) nano composite microspheres prepared in the comparative example 2;

(1) a detection step: taking 5g of the materials, dissolving the materials in 9mL of tetrahydrofuran, subpackaging and pouring the materials into a plurality of glass beakers, respectively placing one marked part into a sunlight simulation box for irradiation detection, irradiating for 15min at normal temperature, wherein the distance between the solution and a light source is 16CM, the radiation quantity hv is 2Eg, recording the difference between the absorption spectra of the solution before irradiation and after irradiation, and the detection result is shown in figure 1, figure 3, figure 5 and a table I.

TABLE-absorption spectrum Difference (. DELTA.OD) of solution in Normal Environment

(2) A detection step: respectively putting 5g of polyurethane/compound of formula (III)/zinc sulfide nano-composite microspheres prepared in example 1, 5g of compound of formula (III) and 5g of polyurethane/compound of formula (III) nano-composite microspheres prepared in comparative example 2 into three crucibles, transferring the crucibles into a muffle furnace, uniformly heating to 200 ℃, and standing for 28 hours at the temperature; and taking out the photochromic compounds, respectively dissolving the photochromic compounds in 9mL of tetrahydrofuran, subpackaging and pouring the mixture into a plurality of glass beakers, respectively placing one marked part into a sunlight simulation box for irradiation detection, irradiating for 15min at normal temperature, wherein the distance between the solution and a light source is 16CM, the radiation quantity hv is 2Eg, and recording the difference between the absorption spectra of the solution before and after irradiation, wherein the detection results are shown in figure 2, figure 4, figure 6 and table two.

TABLE II absorption spectrum difference (Delta OD) of solution under high temperature environment

(II) anti-aging tests were performed on the photochromic lenses prepared in examples 1 and 2 and comparative examples 1 to 2, respectively

The detection steps and the method are as follows: the photochromic lenses prepared in the examples 1 and 2 and the comparative examples 1 to 2 are respectively subjected to irradiation ageing resistance experiments, the experimental equipment adopts a ZN-P type ultraviolet light ageing test box of a tin-free middle-day engineering technology Limited company, the temperature is set to be 60 ℃, the irradiation intensity selects the extreme irradiation condition, after identification, the irradiation is respectively carried out for 15 minutes and 48 hours, the transmittance data before and after irradiation are recorded, and the detection results are shown in the third table.

Table three photochromic lens transmittance (%)

And (4) test conclusion: the absorption spectrum of a solution containing polyurethane/compound of formula (III)/zinc sulfide nano composite microspheres is not changed (no difference) in normal environment and high temperature environment; the absorption spectrum of the photochromic solution prepared in the comparative example 1-2 is changed under normal environment and high temperature environment, the change value at 550nm reaches 0.9, and the change value at 750nm reaches 1; and (II) the transmittance data before and after irradiation of the photochromic lens containing the polyurethane/compound of formula (III)/zinc sulfide nano-composite microsphere coating have no difference, while the transmittance data before and after irradiation of the photochromic lens prepared in the comparative example 1-2 have larger difference, and the change values respectively reach 15 and 16.

The fatigue resistance of the photochromic material is mostly reflected by the change of absorbance or transmittance after discoloration, so the fatigue resistance is measured by the change of the absorbance before and after irradiation and the change of the transmittance, and the following conclusion is obtained by comparing test data: the optical material containing the polyurethane/compound of formula (III)/zinc sulfide nano composite microspheres has stronger fatigue resistance.

Example 4: photochromic response test was performed on the resin lenses prepared in examples 1 and 2 and comparative examples 1 and 2, respectively

Photochromic response value test

The detection steps and the method are as follows: the ratio between the light transmittance tV (0) of the tested sample in the faded state and the light transmittance tV (1) of the discolored state after different illumination times (1-15min), namely: the spectral response value is tV (0) ÷ tV (1) to determine the photochromic response value of the tested sample at different temperatures. After the radiation intensity of the solar simulator is attenuated by 25%, the sample is irradiated with medium illumination intensity, the temperature is set to be 23 ℃, and the detection result is shown in the fourth table.

TABLE IV conditions of photochromic response values of test samples

(II) photochromic spectral response time detection

The detection steps and the method are as follows: placing the photochromic lenses prepared in examples 1 and 2 and comparative examples 1-2 into a test box respectively, turning on a solar simulator light source, and recording the time required for the lenses to change from colorless to colored; after 10 minutes of irradiation, the simulated light source is turned off, the time required for the lens to return to the colorless state from the colored state is recorded, and the detection result is shown in table five.

TABLE V detection of spectral response time of samples

In summary, the following steps: the optical material and the lens containing the polyurethane/compound of formula (III)/zinc sulfide nano composite microsphere prepared by the invention have the advantages of short photochromic response time, high spectral response sensitivity and the like.

Claims (9)

1. A photochromic coating is characterized in that the coating contains polyurethane/a compound shown in a formula (III)/zinc sulfide photochromic composite microspheres, the photochromic composite microspheres are of a three-layer composite core-shell structure, the inner core of the photochromic composite microspheres is zinc sulfide mesoporous nano microspheres, the middle layer of the photochromic composite microspheres is a photochromic layer formed by the compound shown in the formula (III), and the shell of the photochromic composite microspheres is polyurethane; the composite microsphere has an outer diameter of 50-350nm, wherein the diameter of the zinc sulfide mesoporous nano microsphere is 30-250 nm, the thickness of the middle layer is 5-25 nm, and the thickness of the shell is 5-25 nm

2. The photochromic coating of claim 1, wherein the mesoporous nanospheres of zinc sulfide are monodisperse mesoporous nanospheres of zinc sulfide consisting of zinc sulfide nanocrystals, and the intermediate layer is a nano composite mesoporous structure formed by uniformly dispersing the compound nanoparticles of formula (III) on the surface or in the gaps of the mesoporous nanospheres of zinc sulfide.

3. The photochromic coating of claim 1 wherein the polyurethane is polymerized from an isocyanate monomer compound containing two or more isocyanate groups and an alcohol compound.

4. The photochromic coating of claim 3 wherein the isocyanate monomer compound is selected from the group consisting of: at least one of toluene diisocyanate, diphenylmethane-4, 4' -diisocyanate, 1, 6-hexamethylene diisocyanate, m-xylylene diisocyanate, naphthalene-1, 5-diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and isophorone diisocyanate;

the alcohol compound is at least one of n-butyl alcohol, polytetrahydrofuran ether glycol, pentaerythritol, ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and trimethylolpropane.

5. The photochromic coating of any one of claims 1 to 4 wherein the coating is a polythiourethane-dispersed polyurethane/compound of formula (III)/zinc sulfide photochromic composite microsphere, wherein the weight ratio of the photochromic composite microsphere to the polythiourethane is 1: 8.6 to 37.5.

6. The photochromic coating of claim 5 wherein the polythiourethane is polymerized from polythiourethane monomers that are at least one of 2, 2 '-dimercaptoethylsulfide, 2' -dimercaptoethylthioethane, 2, 3-dimercaptoethylthiopropanethiol, or 1, 2, 3-trimercaptoethylthiopropane.

7. A process for the preparation of a photochromic coating according to any one of claims 1 to 6 comprising the following steps:

I. coating solutions were prepared with the following two components:

(1) a component A:

uniformly stirring the components according to the proportion at room temperature for 15-30 minutes to obtain a component A;

(2) b, component B:

isocyanate type curing agent 12-17

Catalyst 0-1

Defoaming agent 0-1

Uniformly stirring the components according to the proportion at room temperature for 3-5 minutes to obtain a component B;

II, during coating, uniformly mixing the component A and the component B according to the mass ratio of (70-100) to (12-19), and adding a diluent to adjust the viscosity to obtain photochromic coating liquid; the photochromic coating layer is produced by applying a photochromic coating liquid onto the surface of an optical substrate to form a coating layer and then curing the coating layer by light irradiation or heating.

8. The method according to claim 7, wherein the isocyanate-type curing agent is at least one of a toluene diisocyanate curing agent, a diphenylmethane-4, 4' -diisocyanate curing agent, a 1, 6-hexamethylene diisocyanate curing agent, an m-xylylene diisocyanate curing agent, a methylcyclohexyl diisocyanate curing agent, and an isophorone diisocyanate curing agent;

the catalyst is dibutyltin dilaurate;

the diluent is at least one of dichloromethane, butyl acetate, methyl acetate, ethanol, butanol, acetone, toluene, xylene, diethyl ether and polytetrahydrofuran ether glycol;

the wetting dispersant is a BYK polyurethane type special wetting dispersant or an F420 type wetting dispersant;

the leveling agent is an oily F300 type leveling agent, an F309 type leveling agent or an F320 type leveling agent;

the defoaming agent is XPJ01F type modified silicone oil defoaming agent.

9. A photochromic coating, characterized in that it is prepared by the process according to claim 7 or 8.

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