CN108003368B

CN108003368B - Color-changing sheet

Info

Publication number: CN108003368B
Application number: CN201711353718.9A
Authority: CN
Inventors: 朱顺全; 谢伟
Original assignee: Hubei Dinglong Co ltd
Current assignee: Hubei Dinglong Co ltd
Priority date: 2017-12-15
Filing date: 2017-12-15
Publication date: 2020-07-28
Anticipated expiration: 2037-12-15
Also published as: CN108003368A

Abstract

The invention discloses a color changing sheet, which solves the problem that the color changing capability of the existing color changing sheet needs to be improved. The invention has simple structure, is easy to produce and manufacture, and can effectively improve the color change of the color changing sheet on the premise of not changing the color changing material and the types of the high polymer materials of the color changing sheet.

Description

Color-changing sheet

Technical Field

The invention relates to a photochromic product, in particular to a photochromic sheet.

Background

The photochromic material is changed in color by a mechanism that after the photochromic material absorbs ultraviolet light, the photochromic material is changed in molecular state and exists in another structure or aggregation state. While the absorption of visible light is greatly increased. And then reversibly returns to the original state under the action of heat or other means, while the absorption of visible light is greatly reduced. Certain photochromic devices, such as photochromic eyewear, privacy glasses, are known to be devices that have the ability to change color by dispersing a color-changing material in a polymer, impregnating, coating, casting, etc. (such devices are essentially planar and are therefore referred to herein as color-changing patches). For some reasons, the photochromic material has a lighter color when not changing color, so the initial color (initial color: the color when not changing color) of the color-changing piece needs to be adjusted by adjusting the type of the photochromic material and fixing the color-changing dye. The color-changing sheet is made to look colorless and transparent by these methods.

In fact, the color-changing sheet can obviously absorb light when the color is not changed, and most products are tested to have visible light absorption rate of about 9% -12% when the reflection loss of light is not calculated. In order not to make the absorption rate too high, too much color-changing material must not be added.

On the other hand, in order to ensure the color-changing capability of the color-changing sheet, the addition amount of the color-changing material cannot be too small, otherwise, the color-changing performance is insufficient. The color changing sheet is exposed to sunlight. When the average transmittance of visible light (400 to 650nm) is less than 20%, the discoloration is very good. If the average visible light transmittance is higher than 40%, the discoloration function of the color-changing sheet is perceived to be weak. Especially, when the temperature is high, the performance of the color-changing material is reduced, and the color-changing capability of the color-changing piece is often weakened.

Researchers wish to enhance the color change properties of color change sheets without increasing the initial absorbance of the color change sheets. In order to solve the above problems, most researchers focus on designing a more excellent color-changing material, such as a lighter initial absorbance or a stronger color-changing intensity, better solubility, a better ultraviolet absorption range, etc., or a color-changing sheet polymer material with excellent usability to match with the color-changing material, so as to achieve the purpose that the initial color of the color-changing sheet is lighter and the color-changing property is enhanced.

At present, the structure of the discoloration sheet generally comprises a substrate and a discoloration layer covering the substrate, and it has been reported that a single layer or multiple layers of discoloration layer are covered on the substrate, and as disclosed in publication No. CN101668714A, a multi-layer photochromic sheet comprising an oxygen or moisture protective barrier membrane, and at least two or more layers of photochromic films, which can obtain photochromic glass having excellent durability and appearance by combination of different functional layers and selection of raw materials. And for example, the publication No. CN105017698B discloses a photo-thermal response type intelligent energy-saving composite film which can be used for preparing one or more layers of alternately compounded discoloring films, wherein the raw materials of the composite film are composed of reversible photochromic substances containing spiropyran and reversible photochromic substances containing vanadium dioxide, and the composite film has the advantages of good discoloring effect and good aging resistance. In summary, most of the color change sheets of various structures disclosed in the prior art are based on the research and development of methods for solving the problem of durability or new materials, and no better method is available, so that the color change property of the color change sheet can be effectively improved without changing the types of the color change materials and the polymer materials of the color change sheet.

Disclosure of Invention

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a color changing sheet which has a simple structure, is easy to produce and manufacture, and can effectively improve the color changing property of the color changing sheet without changing the kind of a color changing material and a polymer material of the color changing sheet.

The technical scheme is that the outer surface of the base material is at least covered with a lower color changing layer and an upper color changing layer, and the light absorption rate of the upper color changing layer is greater than that of the lower color changing layer.

The initial absorbance of the lower color changing layer is 0-5%, the initial absorbance of the upper color changing layer is 5-25%, and the difference between the initial absorbance of the two color changing sheets is more than 1%. Here, the absorbance is: the average absorption of visible light at a wavelength of 400 to 650nm was measured using the substrate CR39 without the color-changing film layer as a test reference.

The initial light absorption rate of the lower discoloring layer is 1-5%, the initial light absorption rate of the upper discoloring layer is 5-10%, and the difference between the light absorption rates of the upper discoloring layer and the lower discoloring layer is larger than 1%.

The upper and lower color-changing layers are formed by mixing at least a polymer material and an organic photochromic material, wherein the polymer material is polyurethane.

The polyurethane is a-NCO end-capped polymer generated by the reaction of a prepolymer and a chain extender, wherein the chain extender at least comprises one of-OH or-SH groups.

The molar weight of-NCO in the prepolymer is more than or equal to 5 percent relative to the molar weight of-OH or-SH in the chain extender.

The prepolymer is formed by mixing and reacting polyfunctional diisocyanate and polyol;

Wherein the multifunctional diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate and hexamethylene diisocyanate trimer;

Wherein the polyol is one or more of polypropylene glycol, polytetrahydrofuran, polycarbonate polyol, polyester polyol and polyester polyol.

The organic photochromic material is a naphthopyran compound.

The polyurethane has the property of being able to absorb ultraviolet radiation of 320-400nm by less than 50% when coated at a thickness of 30 microns.

The curing film-forming temperature of the upper and lower discoloring layers is 90-120 ℃.

Aiming at the problems existing in the background technology, the inventor changes the thought, and under the condition that the material type is not changed, the factors for analyzing and influencing the color change intensity are respectively as follows: ultraviolet intensity, amount of color change material, distribution of ultraviolet light among different color change materials, temperature, etc. Under the premise of keeping other conditions unchanged, the conclusion that the color-changing effect of the color-changing sheet can be enhanced by reasonably distributing ultraviolet rays to different color-changing materials is obtained. For the purpose of distributing ultraviolet rays by different color-changing materials, a method of covering a color-changing layer with different initial absorbances on a substrate can be considered.

Based on the above studies, the inventors placed a color-changing material having a lower initial absorbance in the lower color-changing layer and a color-changing material having a higher initial absorbance in the upper color-changing layer (contact light-irradiating layer). The purpose is to make the upper color-changing layer obtain more illumination and enhance the color-changing ability, while the initial absorbance of the color-changing material of the lower color-changing layer is low, and the complementary action of the two can make the initial transmittance of the color-changing sheet not decrease, thereby achieving the purpose of increasing the color-changing ability without decreasing the initial transmittance of the color-changing sheet.

Further, in order to improve the discoloration ability as much as possible, the initial absorbances of the upper and lower color-changing plates are preferably maintained within a limited difference, i.e., at least greater than 1% of the initial absorbances are different, preferably greater than 2% of the absorbances are different. Otherwise, the effect of improving the color-changing intensity is difficult to achieve.

The present invention is not particularly limited to the materials and the preparation processes of the respective layers, and can be manufactured by using materials and preparation methods which are generally used in the prior art.

The base material is a base material which can receive the photochromic coating, and the raw material can be reasonably selected according to different application fields and environmental conditions, and comprises at least one of PET, polythiourethane, PC, nylon and CR-39. The color-changing material can be prepared by a die casting method, for example, the curing and film-forming temperatures of the upper and lower color-changing layers are preferably 90-120 ℃, and the color-changing material is decomposed when the temperature is too high, and the edge is shrunk when the temperature is too low because the color-changing material is not cured for a long time. The color changing layer comprising the upper color changing layer and the lower color changing layer contains a polymer material and an organic photochromic material, the polymer material is preferably polyurethane, and further preferably the performance that the absorptivity of the ultraviolet ray of 320-400nm is less than 50% when the color changing layer is coated with the color changing layer with the thickness of 30 microns is met. Specifically, the polyurethane is an isocyanate-terminated polymer generated by the reaction of a prepolymer and a chain extender, wherein the chain extender at least comprises one of-OH or-SH groups. The chain extender may be exemplified by: 2, 2-dimethylolbutanol, 1, 2-propanediol, mercaptoethanol, trithiodiglycol, 2, 3-dithio (2-mercapto) -1-propanethiol, pentaerythritol mercaptopropionate, propanedithiol, butanedithiol, etc.

The molar weight of-NCO in the prepolymer is more than or equal to 5 percent relative to the molar weight of-OH in the polyalcohol. Wherein the prepolymer is prepared by mixing and reacting polyfunctional diisocyanate and polyol. The polyfunctional diisocyanate may be exemplified by: isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate trimer, etc.; isophorone diisocyanate is preferred because isophorone diisocyanate has a unique chemical structure, which is different from other aliphatic/cycloaliphatic diisocyanates, isophorone diisocyanate has a cyclohexanone system, three methyl groups, which make isophorone diisocyanate almost miscible with various resin solvents, and two different isocyanate groups, and the color chips prepared using isophorone diisocyanate have good fullness and strong that chemical properties.

Examples of the polyhydric alcohol include: polypropylene glycol, polytetrahydrofuran, polycarbonate polyol, polyester polyol, and the like; polypropylene glycol and polytetrahydrofuran are preferred, polypropylene glycol is most preferred because polypropylene glycol has a significant effect on the stability of polyurethane, and discoloration sheets prepared using polypropylene glycol as the polyol do not suffer from the undesirable phenomena such as shrinkage, black spots, white fog, water marks, crystal spots, pocking spots, sagging, and liquid accumulation.

The organic photochromic material is a naphthopyran compound, preferably spiropyran, fulgide, spiropyrazine and the like, and a solvent may be added to dissolve the raw material when the upper and lower photochromic layers are prepared, wherein the solvent may be dimethylformamide, N-methylpyrrolidone, ethyl acetate, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, butyl acetate, dichloroethane, propylene glycol dimethyl ether and the like, and the photochromic material: polyurethane material: the mass ratio of the solvent to the solvent is preferably 2-10: 100: 10-30. Various additives such as an antioxidant, a light aging inhibitor, a catalyst or a surfactant may be added as required. The color-changing layer can be coated on the substrate by means of infiltration, coating, casting and the like. In addition to the upper color changing layer and the lower color changing layer, an isolation layer, an adhesive layer, a protective layer, a color changing layer, a dyeing layer, etc. may be added to the substrate as required, which is prior art and will not be described in detail herein. The present invention also does not limit the possibility of adding a new color shifting layer between the upper and lower color shifting layers. The specific colors of the upper and lower color-changing layers can be reasonably set according to the product requirements under the condition of meeting the above light absorption rate so as to meet the requirements of different product functions and appearances.

The photochromic lens has the advantages of extremely simple structure, ingenious conception, easy production and manufacture, and capability of effectively improving the color change property of the photochromic lens by completely utilizing the existing materials and process methods on the premise of not changing the types of the photochromic materials and the high polymer materials of the photochromic lens, achieving the purpose of increasing the color change capability without reducing the initial light transmittance of the photochromic lens, being applicable to photochromic glasses, light-adjusting glass and other devices which need to have the color change capability, and having wide market application prospect.

Drawings

FIG. 1 is a schematic view of the structure of the present invention.

Wherein, 1-substrate, 2-lower color changing layer and 3-upper color changing layer.

Detailed Description

Referring to fig. 1, the color-changing sheet of the present invention includes at least a substrate 1 to which a color-changing layer is attached, a lower color-changing layer 2 covering an upper surface of the substrate 1, and an upper color-changing layer covering the lower color-changing layer 2. Wherein the initial absorbance of the lower color-changing layer is 0-5%, the initial absorbance of the upper color-changing layer is 5-25%, and the initial absorbance of the upper color-changing layer minus the initial absorbance of the lower color-changing layer is more than 1%. Preferably, the lower color-changing layer has an initial absorbance of 1 to 5%, the upper color-changing layer has an initial absorbance of 5 to 10%, and the initial absorbance of the upper color-changing layer minus the initial absorbance of the lower color-changing layer is greater than 1%.

The manufacturing embodiment of the color changing sheet is provided as an example, but the embodiment does not limit the manufacturing of the color changing sheet of the present invention, and one skilled in the art can select other suitable manufacturing methods according to the need.

Example 1 (the percentages are mass percentages, and the ratios are mass ratios):

The CR-39 wafer was used as a substrate, and was washed by soaking in a 5% aqueous solution of potassium hydroxide at 60 ℃ for 10 minutes, then washed with soap water and deionized water, and dried with compressed air. Cleaning the substrate with a plasma cleaner: the treatment was carried out for 60 seconds at an oxygen flow of 50 ml/min, a pressure of less than 0.5mm Hg. Then, a coating solution of a lower color-changing layer was spin-coated on the substrate, the thickness of the coating layer was made 18 μm by controlling the rotation speed, and after the film was formed by spin coating, the wafer was placed in a nitrogen oven and dried at 100 ℃ for 4 hours. And taking out the wafer, cooling, spin-coating the second photochromic layer coating solution to a coating thickness of 12 microns, and after spin-coating to form a film, putting the wafer in a nitrogen oven to dry for 4 hours at 100 ℃ to obtain the photochromic sheet 1.

The preparation method of the color-changing layer coating liquid comprises the steps of mixing a photochromic material, a polyurethane material and a solvent to prepare a polyurethane solution, and then adding 1% of an antioxidant 245, 0.5% of an anti-light aging agent 622, 0.05% of a catalyst dibutyl tin dichloride and 0.1% of a siloxane surfactant DC-57 by mass (100%) of the polyurethane solution.

The polyurethane material in the coating liquid is generated by the reaction of a prepolymer and a chain extender, wherein the prepolymer is prepared by mixing isophorone diisocyanate (IPDI) and polypropylene glycol (PPG1000) in a molar ratio of 2: 1, the chain extender is 2, 2-dimethylol butanol (TMP), and the hydroxyl of-NCO in the prepolymer is 5 percent excessive relative to the molar weight of-OH in the chain extender TMP. The organic photochromic material in the coating liquid is a naphthopyran compound.

The preparation method of the upper and lower color-changing layers is the same as that described above, except that: when the upper color changing layer is prepared, the color changing material in the polyurethane solution: polyurethane material: solvent 1: 22: 5, the color-changing material used in the upper color-changing layer has high initial light absorption rate. The color-changing material in the polyurethane solution is prepared by the following steps: polyurethane material: solvent 1: 22: 5, the lower color-changing layer uses a color-changing material with low initial absorbance. It should be noted that the amount of color-changing material in the lower color-changing layer is preferably such that a neutral color is obtained after color change. Neutral color here means that in the CI E color system the color has CIE coordinates (x, y) with x values of 0.2 to 0.5 and y values of 0.2 to 0.4, and appears gray, brown and colors similar to gray or brown.

placing the sample on an optical bench, testing the sample transmittance (400-650nm) with an F L AME fiber spectrometer to 85%, using a simulated daylight xenon lamp provided by a Miao gold source, adjusting UVA intensity to 3W/m ²(UV intensity was ensured using a UVA photometer). When the sample was irradiated at 22 degrees centigrade, the sample turned dark gray and the light transmittance decreased. When the transmittance is reduced to a constant value, the transmittance of the fiber spectrometer is read and is taken as the saturated transmittance.

The processes of examples 2-6 are the same as in example 1, except for the differences shown in tables 1 and 2.

Table 1 examples 1-6 polyurethane materials preparation starting materials

TABLE 2 examples 1-6 color-changing plate Process parameters and characterization results

Comparative example 1

A CR-39 (refractive index of 1.49) round lens was used as a substrate, and the lens was washed by soaking in a 5% aqueous solution of potassium hydroxide at 60 ℃ for 10 minutes, then washed with soapy water, deionized water, and dried with compressed air. Cleaning the substrate with a plasma cleaner: the treatment was carried out for 60 seconds under an oxygen flow of 50ml/min at a pressure of less than 0.5mm Hg, and then a photochromic layer was spin-coated on the layer to a thickness of 27 μm. After spin coating, the wafer was dried in a nitrogen oven at 100 ℃ for 4 hours.

The photochromic layer was prepared by dissolving the photochromic material (note: the photochromic material was the same type as in example 1, but in a different ratio of 1: 1.2, and the color tone after discoloration was the same as in example 1) in DMF, and then adding 1% of the total mass of the antioxidant 245, 0.5% of the anti-aging agent 622, 0.05% of the catalyst dibutyltin dichloride, 0.1% of the siloxane surfactant DC-57, and the polyurethane material. Wherein, the color-changing material in the polyurethane solution: polyurethane material: solvent 1: 22: 5.

Comparative example 2

Same as comparative example 1 except that: the oven drying temperature was 80 ℃.

Comparative example 3

Same as comparative example 1 except that: the color change layer was thickened to 31 μm in order to expect an increase in color change strength.

The examples and comparative examples were tested for their pass rates and change ability and the results are shown in Table 3.

TABLE 3

Example numbering	Initial transmittance	Saturated transmittance	With or without edge shrinkage
				Comparative example 1	84.3％	25.8％	The shrinkage can be ignored
Comparative example 2	84.3％	25.8％	Obvious edge shrinkage
				Comparative example 3	83.1％	23.9％	The shrinkage can be ignored

Through the test, the initial transmittance of the example 1 is close to that of the comparative examples 1 to 3. After saturated discoloration under simulated daylight conditions, the saturated transmittance of example 1 was 22.1%, while comparative examples 1, 2, 3 were 25.8%, 23.9%, respectively, and significant edge curling occurred with comparative example 2. Compared with the comparative example, the color-changing capability of the color-changing sheet is obviously enhanced, and the problem of edge shrinkage is avoided.

Claims

1. The utility model provides a color-changing piece, includes the substrate, its characterized in that, the surface at the substrate covers down color-changing layer and last color-changing layer at least, lower color-changing layer initial absorbance is 0-5%, and upper color-changing layer initial absorbance is 5-25%, the initial absorbance of upper color-changing layer is greater than lower color-changing layer initial absorbance, and the difference between the initial absorbance of two-layer color-changing layer is greater than 1%.

2. The color-changing sheet according to claim 1, wherein the lower color-changing layer has an initial absorbance of 1 to 5%, the upper color-changing layer has an initial absorbance of 5 to 10%, and the difference between the initial absorbances of the two color-changing layers is more than 1%.

3. The color-changing sheet according to claim 1, wherein the upper and lower color-changing layers are formed by mixing at least a polymer material and an organic photochromic material, wherein the polymer material is polyurethane.

4. The color changing sheet of claim 3, wherein the polyurethane is a-NCO terminated polymer formed by reacting a prepolymer with a chain extender, wherein the chain extender comprises at least one of-OH or-SH groups.

5. A color-changing sheet according to claim 4 wherein the molar amount of-NCO in the prepolymer is not less than 5% relative to the molar amount of-OH or-SH in the chain extender.

6. The color-changing sheet according to claim 4 or 5, wherein the prepolymer is prepared by mixing and reacting a polyfunctional diisocyanate and a polyol;

Wherein the polyol is one or more of polypropylene glycol, polytetrahydrofuran, polycarbonate polyol and polyester polyol.

7. The color changing sheet of claim 3, wherein the organic photochromic material is a naphthopyran-based compound.

8. A color-changing sheet according to claim 3 wherein the polyurethane has the property of having an absorbance of ultraviolet radiation from 320 to 400nm of less than 50% when coated at a thickness of 30 microns.

9. A color-changing sheet according to any one of claims 1 to 3, wherein the upper and lower color-changing layers have a curing film-forming temperature of 90 to 120 ℃.