阅读说明：本技术 一种紫外光激发变色/加热复色的聚氨酯及其合成方法 (Ultraviolet light excited color changing/heating composite color polyurethane and synthesis method thereof ) 是由 张婉 肖沭 于伟东 陈坤林 殷允杰 王潮霞 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种紫外光激发变色/加热复色的聚氨酯及其合成方法,属于化学合成技术领域。本发明的合成方法,包括将荧光黄、烷基二胺化合物及溶剂混合均匀后,于机械搅拌下加热反应,待反应结束后,将产物烘干并通过层析色谱法提纯,获得荧光黄衍生物；将二异氰酸酯、聚二元醇溶解于溶剂中于机械搅拌下加热反应一段时间,然后加入扩链剂并缓慢滴加二月桂酸二丁基锡继续反应,然后在上述反应物中加入荧光黄衍生物,继续加热反应,待反应结束后用溶剂浸泡冲洗以移除未参与反应的单体,随后将上述反应物干燥,得到即得最终产品。目标产物紫外光激发变色/加热复色的聚氨酯在军事、防伪、加密、服装、医药等领域具有重要的应用价值。(The invention discloses ultraviolet light excited color changing/heating composite color polyurethane and a synthesis method thereof, belonging to the technical field of chemical synthesis. The synthesis method comprises the steps of uniformly mixing the fluorescein, the alkyl diamine compound and the solvent, heating and reacting under mechanical stirring, drying the product after the reaction is finished, and purifying the product through chromatography to obtain the fluorescein derivative; dissolving diisocyanate and polydiol in a solvent, heating and reacting for a period of time under mechanical stirring, then adding a chain extender and slowly dropwise adding dibutyltin dilaurate to continue reacting, then adding a fluorescent yellow derivative into the reactant, continuing heating and reacting, soaking and washing with the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and then drying the reactant to obtain the final product. The target product ultraviolet light excited color changing/heating compound color polyurethane has important application value in the fields of military affairs, anti-counterfeiting, encryption, clothing, medicine and the like.)

1. A synthetic method of polyurethane with ultraviolet light excitation color change/heating color compounding is characterized by comprising the following steps:

(1) uniformly mixing the fluorescein, the alkyl diamine compound and the solvent, heating and reacting for a period of time under stirring, and after the reaction is finished, drying and purifying a product to obtain the fluorescein derivative;

(2) dissolving diisocyanate and polyglycol in tetrahydrofuran, heating and reacting for a period of time under stirring, adding a chain extender, dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuing to react, adding the fluorescent yellow derivative obtained in the step (1) into the reactant, continuing to heat and react for a period of time, soaking and washing for multiple times by using a solvent after the reaction is finished to remove monomers which do not participate in the reaction, and drying the reaction product to obtain the ultraviolet light excited color change/heating and decoloring polyurethane.

2. The method of claim 1, wherein the alkyl diamine compound comprises one or a combination of two or more of ethylene diamine, propylene diamine, dodecane diamine, and p-phenylene diamine.

3. The synthesis method according to claim 1 or 2, wherein the solvent in step (1) comprises any one or a combination of two or more of acetone, ethanol, dimethylformamide, isopropanol and tetrahydrofuran.

4. The synthesis method according to any one of claims 1 to 3, wherein in the step (1), the mass ratio of the fluorescein and the alkyl diamine compound to the solvent is 1 (0.15-1.5) to (8-30).

5. The method according to any one of claims 1 to 4, wherein in the step (2), the weight ratio of the diisocyanate, the polyglycol, the solvent, the chain extender and the fluorescein derivative is 1 (2-5): 15-40): 0.15-1): 0.1-1.

6. The synthesis method according to any one of claims 1 to 5, wherein the diisocyanate comprises any one or a combination of two or more of diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; the polyglycol comprises one or a combination of more than two of polycarbonate diol, polyethylene glycol, polytetrahydrofuran diol and polycaprolactone diol; the chain extender comprises one or a composition of more than two of 2, 2-dimethylolpropionic acid, 1, 4-butanediol, 1, 2-propanediol, ethylenediamine, neopentyl glycol and methyl propanediol.

7. A synthesis process according to any one of claims 1 to 6, characterised in that it comprises:

(A) adding 1 part by weight of fluorescein and 0.15-1.5 parts by weight of alkyl diamine compound into 8-30 parts by weight of solvent, heating the mixture to 60-95 ℃, reacting at the speed of 300-1000rpm for 8-15h, cooling, drying the product, and purifying by chromatography to obtain a fluorescein derivative;

(B) dissolving 1 part by weight of diisocyanate and 2-5 parts by weight of polyglycol in 15-40 parts by weight of solvent, heating the mixture to 50-90 ℃, reacting for 1-5h at a stirring speed of 400-1500rpm, adding 0.15-1 part by weight of chain extender, slowly dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuing to react for 1-10h, adding 0.1-1 part by weight of fluorescent yellow derivative into the reactant, continuing to react for 0.1-3h by heating, soaking and washing for 3 times by using the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and then drying the reactant for 2-24h to obtain the ultraviolet light excited color change/heating composite color polyurethane.

8. The ultraviolet light excited color change/heating composite color polyurethane synthesized according to the synthesis method of any one of claims 1 to 7.

9. A garment, security device, or military article comprising the uv-activated color change/thermochromic polyurethane of claim 8.

10. The synthetic method of any one of claims 1 to 7 or the ultraviolet light excited color change/heating composite color polyurethane of claim 8 is applied to the fields of military affairs, anti-counterfeiting, encryption, clothing and medicine.

Technical Field

The invention relates to polyurethane with ultraviolet light excited color change/heating compound color and a synthesis method thereof, belonging to the technical field of chemical synthesis.

Background

The stimulus response material is an intelligent material which can greatly change the structure or state of the stimulus response material by receiving stimulus signals of external environment, such as pH value, light, temperature, electricity, magnetism and the like, thereby influencing the physical and chemical properties of the stimulus response material, further embodying corresponding functions, and having very wide application prospect. Among them, the optical stimulus responsive color-changing material and the thermal stimulus responsive color-changing material are one of the most potential materials at present, and have a wide market in the fields of military affairs, clothing, industry and the like.

In the existing products, the materials can be divided into two categories according to the compound color performance, namely reversible color change category and irreversible color change category. The irreversible color-changing material only has disposable use value and can only be suitable for certain special fields, so the irreversible color-changing material has obvious defect. The reversible color change type has a characteristic of being capable of changing color repeatedly, and thus is a current hot spot. The defects in the beauty are that common reversible color-changing materials also have two remarkable defects, 1. the color of the materials in the stimulus response state can not be preserved for a long time, and is easy to fade, and the materials can not be artificially controlled to exist for a long time in a certain state in a normal environment, so that the monitoring, the indication and the like in the actual production process are adversely affected; 2. the preparation conditions are also relatively complicated because most reversible color-changing materials are composed of multi-component substances and need to be encapsulated in microcapsules to prevent the loss of the components.

At present, a single-component intelligent response material with controllable light/thermal response reversible color change is urgently needed.

Disclosure of Invention

Aiming at the technical problems, the invention provides ultraviolet light excited color change/heating color compounding polyurethane and a synthesis method thereof, namely a color change material with double stimulation synergistic effect, which can excite color development through ultraviolet light irradiation, keep the color state for a long time within the full wavelength of room temperature and compound color under the action of an external heat source.

The technical scheme adopted by the invention is as follows:

a synthetic method of polyurethane with ultraviolet light excitation color change/heating color compounding comprises the following steps:

(1) uniformly mixing the fluorescein, the alkyl diamine compound and the solvent, heating and reacting for a period of time under stirring, and after the reaction is finished, drying and purifying a product to obtain the fluorescein derivative;

(2) dissolving diisocyanate and polyglycol in a solvent, heating and reacting for a period of time under stirring, adding a chain extender, dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuing to react, adding the fluorescent yellow derivative obtained in the step (1) into the reactant, continuing to heat and react for a period of time, soaking and washing for multiple times by using the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and then drying the reaction product to obtain the ultraviolet light excited color change/heating and decoloring polyurethane.

In one embodiment of the present invention, the alkyl diamine compound includes any one or a combination of two or more of ethylenediamine, propylenediamine, dodecylenediamine, and p-phenylenediamine.

In one embodiment of the present invention, the heating reaction in step (1) for a certain period of time means a reaction at 60-95 ℃ for 8-15 hours.

In one embodiment of the present invention, the solvent in step (1) comprises any one or a combination of two or more of acetone, ethanol, dimethylformamide, isopropanol, and tetrahydrofuran.

In one embodiment of the present invention, in the step (1), the mass ratio of the fluorescein and the alkyl diamine compound to the solvent is 1 (0.15-1.5) to (8-30).

In one embodiment of the present invention, in step (1), the purification is preferably a chromatographic purification.

In one embodiment of the present invention, the prepared fluorescein derivative is white powder.

In one embodiment of the present invention, in the step (2), the weight ratio of the diisocyanate, the polyglycol, the solvent, the chain extender and the fluorescent yellow derivative is 1 (2-5): 15-40): 0.15-1): 0.1-1.

In one embodiment of the present invention, said dropwise addition of 0.1 to 0.15% by weight of dibutyltin dilaurate refers to dropwise addition of 0.1 to 0.15% by weight of dibutyltin dilaurate, based on the total mass of diisocyanate, polyglycol and chain extender.

In one embodiment of the present invention, the diisocyanate includes any one or a combination of two or more of diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

In one embodiment of the present invention, the polyglycol includes any one or a combination of two or more of polycarbonate diol, polyethylene glycol, polytetrahydrofuran diol, and polycaprolactone diol.

In one embodiment of the present invention, the solvent in step (2) is tetrahydrofuran.

In one embodiment of the present invention, the chain extender comprises any one or a combination of two or more of 2, 2-dimethylolpropionic acid, 1, 4-butanediol, 1, 2-propanediol, ethylenediamine, neopentyl glycol and methylpropanediol.

In one embodiment of the present invention, in the step (2), the diisocyanate and the polyglycol are reacted in the solvent at 50-90 ℃ for 1-5 h.

In one embodiment of the invention, in step (2), the chain extender and dibutyltin dilaurate are added to continue the reaction for 1-10 h.

In one embodiment of the present invention, in step (2), the fluorogenic yellow derivative is added to continue the reaction for 0.1 to 3 hours.

In one embodiment of the present invention, the method for synthesizing the ultraviolet light excited color change/heating composite color polyurethane comprises the following steps:

(1) uniformly mixing the fluorescein, the alkyl diamine compound and the solvent, heating to 60-95 ℃ under mechanical stirring for reaction for a period of time, drying the product after the reaction is finished, and purifying by chromatography to obtain the fluorescein derivative;

(2) dissolving diisocyanate and polyglycol in a solvent, heating and reacting under mechanical stirring, adding a chain extender, slowly dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuously reacting for a period of time, adding the fluorescent yellow derivative obtained in the step (1) into the reactant, continuously heating and reacting for a period of time, soaking and washing for many times by using the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and drying the reactant to obtain the ultraviolet light excited color change/heating and color restoration polyurethane.

In one embodiment of the present invention, the preparation method may further comprise:

(1) uniformly mixing the fluorescein, the alkyl diamine compound and the solvent, heating to 60-95 ℃ under mechanical stirring at 300-1000rpm for reacting for 8-15h, drying the product after the reaction is finished, and purifying by chromatography to obtain the fluorescein derivative;

(2) dissolving diisocyanate and polyglycol in a solvent, reacting for 1-5h at 50-90 ℃ under mechanical stirring at 400-1500rpm, adding a chain extender, dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuously reacting for 1-10h, adding the fluorescent yellow derivative obtained in the step (1) into the reactant, continuously heating for 0.1-3h, soaking and washing for many times by using the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and drying the reactant for 2-24h to obtain the ultraviolet light excited color change/heating color recovery polyurethane.

In one embodiment of the present invention, the preparation method may include:

(A) adding 1 part by weight of fluorescein and 0.15-1.5 parts by weight of alkyl diamine compound into 8-30 parts by weight of solvent, heating the mixture to 60-95 ℃, reacting at the speed of 300-1000rpm for 8-15h, cooling, drying the product, and purifying by chromatography to obtain a fluorescein derivative;

(B) dissolving 1 part by weight of diisocyanate and 2-5 parts by weight of polyglycol in 15-40 parts by weight of solvent, heating the mixture to 50-90 ℃, reacting for 1-5h at a stirring speed of 400-1500rpm, adding 0.15-1 part by weight of chain extender, slowly dropwise adding 0.1-0.15 wt% of dibutyltin dilaurate, continuing to react for 1-10h, adding 0.1-1 part by weight of fluorescent yellow derivative into the reactant, continuing to react for 0.1-3h by heating, soaking and washing for 3 times by using the solvent after the reaction is finished to remove monomers which do not participate in the reaction, and then drying the reactant for 2-24h to obtain the ultraviolet light excited color change/heating composite color polyurethane.

The invention also provides the polyurethane with the ultraviolet light excited color change/heating compound color prepared by the preparation method.

In one embodiment of the present invention, the molecular weight of the uv-excited color change/heat discoloration polyurethane is 5000-30000.

In one embodiment of the present invention, the uv-excited color change/thermal discoloration polyurethane is colorless and transparent at room temperature.

The invention also provides clothing, an anti-counterfeiting device, an encryption device or military supplies containing the ultraviolet excited color-changing/heating compound color polyurethane.

Finally, the invention also provides the preparation method and the application of the ultraviolet light excited color change/heating compound color polyurethane in the fields of military affairs, anti-counterfeiting, encryption, clothing, medicine and the like.

The invention has the beneficial effects that:

(1) according to the invention, the alkyl diamine compound is firmly grafted on the fluorescent yellow molecule through a grafting reaction, so that the modified fluorescent yellow compound has the color development performance of opening and closing a lactone ring, and the initial color development and fluorescence emission performance of the modified fluorescent yellow compound are changed. The prepared fluorescent yellow derivative has a primary amine structure and is very easy to react with unsaturated bonds in isocyanate, so that the fluorescent yellow derivative can be used as a blocking agent of polyurethane to greatly improve the grafting rate of the fluorescent yellow derivative on the polyurethane.

(2) The product prepared by the invention has turn-on type fluorescence and color-emitting performance excited by ultraviolet light, can be excited from a basically non-fluorescence transparent state to a strong fluorescence yellow state, and the state can be stored for a long time, however, after being stimulated by an external heat source, the material can be quickly restored to the non-fluorescence transparent state, compared with the conventional reversible color-changing material and irreversible color-changing material, the material has the advantage of obvious controllable color-emitting state, has the advantages of stable property and the like, can be subjected to heating and cooling reversible color-changing circulation for more than 1000 times, and can be used as a multifunctional novel intelligent material to be applied to the fields of military affairs, anti-counterfeiting, encryption, clothing, medicine and the like, thereby overcoming the defects of the current light/heat stimulation response color-changing material in the aspect.

(3) Through tests, the material also has the functions of pH response visible light color change and pH response fluorescence change, is in a colorless, transparent and non-fluorescent state under the condition that the pH value is more than or equal to 7, gradually emits yellow fluorescence and is in yellow along with the reduction of the pH value, and the property has great application value in certain probe indication fields.

Drawings

FIG. 1 is a 1H NMR spectrum of modified lucifer yellow obtained in example 1;

FIG. 2 is a photograph showing the effects of the UV-activated color-change/heat-discoloration polyurethane obtained in example 1 before and after heating under UV light and visible light.

Detailed Description

The method for measuring the molecular weight of the polyurethane with ultraviolet light excitation color change/heating color compounding comprises the following steps: tetrahydrofuran is used as an eluent, gel permeation chromatography is adopted to test the molecular weight of the prepared polyurethane, the scanning wavelength is 190-800 nm, and the flow rate is 0-20 cm³ min^-1。

Example 1: synthesis of polyurethane with ultraviolet light excited color change/heating color compounding

Adding 1g of fluorescein and 0.15g of propylenediamine to 8g of acetone, after which the mixture is heated to 95 ℃ and reacted at a speed of 300rpm for 8h, after cooling the product is dried and purified by chromatography to give a white fluorescein derivative which is obtained¹H NMR test results are shown in the following figure 1, and the significant absorption peaks at chemical shifts of 1.7-1.9, 2.25-2.5 and 3.15-3.3 can be found from the figure, and are characteristic peaks of hydrogen on a propane diamine carbon chain, and the absorption peaks at chemical shifts of 4.15-4.3, 6.15, 6.24, 6.78, 7.15, 7.3, 7.4-7.5 and 7.8 are characteristic peaks of hydrogen on a fluorescence yellow carbon chain, which indicates that propane diamine is successfully grafted on fluorescence yellow;

1g of toluene diisocyanate and 2g of polycarbonate diol are dissolved in 15g of tetrahydrofuran, then the mixture is heated to 90 ℃ and reacted for 5h at a stirring speed of 400rpm, then 0.075g of 2, 2-dimethylolpropionic acid and 0.075g of 1, 4-butanediol are added, 0.1 wt% of dibutyltin dilaurate is slowly added dropwise to continue the reaction for 10h, then 0.1g of a fluorescent yellow derivative is added into the reactant, the reaction is continued for 1h, after the reaction is finished, dimethylformamide is used for soaking and washing for 3 times to remove monomers which do not participate in the reaction, and then the reactant is placed in a vacuum oven for drying treatment for 24h to obtain the ultraviolet light-excited color changing/heating double color polyurethane.

The polyurethane which is in a transparent non-fluorescent color development state and is subjected to ultraviolet light excitation color change/heating color compounding is detected to have the average molecular weight of 10000.

The effects of the prepared ultraviolet light excited color change/heating composite color polyurethane before and after heating under ultraviolet light and visible light are shown in fig. 2, and it can be found that after the ultraviolet lamp at room temperature irradiates for 30s, the material emits yellow fluorescence, and after the ultraviolet lamp is removed, the material is yellow and has no macroscopic color change within 12 h; and then, under visible light, heating for 3s by using an external heat source at 70 ℃, and then recovering the transparent and non-fluorescent state of the material.

The fluorescence-color compounding process is repeated for 1000 times, and the polyurethane is always in a transparent non-fluorescence emission state in a heating state, and is always in yellow and emits yellow fluorescence after being irradiated by room-temperature UV light, so that the ultraviolet excited color-changing/heating color-compounding polyurethane prepared by the method can be circularly and repeatedly discolored, and has very stable performance.

In addition, the fluorescent material is colorless, transparent and non-fluorescent under the condition that the pH value is more than or equal to 7, gradually emits yellow fluorescence and yellow along with the reduction of the pH value, and when the pH value is 1, the fluorescent material is yellow and emits bright yellow fluorescence.

Example 2: synthesis of polyurethane with ultraviolet light excited color change/heating color compounding

Adding 1g of fluorescein and 1.5g of dodecanediamine to a mixture of 15g of ethanol and 15g of isopropanol, heating the mixture to 60 ℃ and reacting at 1000rpm for 15h, drying the product after cooling and purifying it by chromatography to obtain a white fluorescein derivative which is obtained¹The H NMR measurement results were substantially the same as in example 1;

1g of hexamethylene diisocyanate and 5g of polytetrahydrofuran glycol are dissolved in 40g of tetrahydrofuran, then the mixture is heated to 50 ℃ and is stirred at 1500rpm for 1 hour, then 1g of 1, 2-propylene glycol is added, 0.15 wt% of dibutyltin dilaurate is slowly and dropwise added for continuous reaction for 1 hour, then 0.1g of a fluorescent yellow derivative is added into the reactant, the heating reaction is continued for 3 hours, after the reaction is finished, acetone is used for soaking and washing for 3 times to remove monomers which do not participate in the reaction, and then the reactant is placed in a vacuum oven for drying treatment for 2 hours to obtain the ultraviolet light excited color change/heating color change polyurethane which is in a transparent non-fluorescent color development state and has the molecular weight of 5000.

The luminescence test performed in the manner of example 1 shows that the effect before and after heating under ultraviolet light and visible light is substantially the same as that of example 1, that is, the material can be excited from the substantially non-fluorescent transparent state to the strong-fluorescent yellow state by ultraviolet light, and the state can be stored for a long time, but after being stimulated by an external heat source, the material can be rapidly restored to the non-fluorescent transparent state, and the material can maintain stable performance and has pH response performance after 1000 times of color change.

Example 3: synthesis of polyurethane with ultraviolet light excited color change/heating color compounding

1g of lucifer yellow and 0.75g of ethylenediamine are added to 15g of dimethylformamide, after which the mixture is heated to 80 ℃ and reacted at a speed of 500rpm for 10h, after cooling the product is dried and purified by chromatography to obtain a white lucifer yellow derivative which is obtained¹The H NMR measurement results were substantially the same as in example 1;

1g of isophorone diisocyanate and 3g of polycaprolactone diol are dissolved in 30g of tetrahydrofuran, then the mixture is heated to 80 ℃ and is stirred at 800rpm for reaction for 3h, then 0.5g of ethylenediamine and 0.5g of neopentyl glycol are added, 0.13 wt% of dibutyltin dilaurate is slowly and dropwise added for further reaction for 5h, then 0.5g of fluorescent yellow derivative is added into the reactant, the reaction is further heated for 2h, after the reaction is finished, isopropanol is used for soaking and washing for 3 times to remove monomers which do not participate in the reaction, and then the reactant is placed in a vacuum oven for drying treatment for 12h to obtain the ultraviolet light excited color change/heating double color polyurethane which is in a transparent non-fluorescent color development state and has the molecular weight of 23000.

The luminescence test performed in the manner of example 1 shows that the effect before and after heating under ultraviolet light and visible light is substantially the same as that of example 1, that is, the material can be excited from the substantially non-fluorescent transparent state to the strong-fluorescent yellow state by ultraviolet light, and the state can be stored for a long time, but after being stimulated by an external heat source, the material can be rapidly restored to the non-fluorescent transparent state, and the material can maintain stable performance and has pH response performance after 1000 times of color change.

Example 4: synthesis of polyurethane with ultraviolet light excited color change/heating color compounding

1g of lucifer yellow and 0.5g of p-phenylenediamine are added to 20g of tetrahydrofuran, after which the mixture is heated to 70 ℃ and reacted at a speed of 800rpm for 12h, after cooling the product is dried and purified by chromatography to obtain a white lucifer yellow derivative which is obtained¹The H NMR measurement results were substantially the same as in example 1;

1g of diphenylmethane diisocyanate and 4g of polyethylene glycol are dissolved in 25g of tetrahydrofuran, then the mixture is heated to 70 ℃ and reacted for 4 hours at the stirring speed of 1200rpm, then 0.8g of methyl propylene glycol is added, 0.11 wt% of dibutyltin dilaurate is slowly dropped for continuous reaction for 7 hours, then 0.7g of fluorescent yellow derivative is added into the reactant, the reaction is continuously heated for 1.5 hours, after the reaction is finished, ethanol is used for soaking and washing for 3 times to remove monomers which do not participate in the reaction, and then the reactant is placed in a vacuum oven for drying treatment for 6 hours, so that the ultraviolet light excited color development/heating color restoration polyurethane is obtained, is in a transparent non-fluorescent state and has the molecular weight of 30000.

The luminescence test performed in the manner of example 1 shows that the effect of the material before and after heating under ultraviolet light and visible light is substantially the same as that of example 1, i.e. the material can be excited from the substantially non-fluorescent transparent state to the strong-fluorescent yellow state by ultraviolet light, and the state can be stored for a long time, but after the material is stimulated by an external heat source, the material can be rapidly restored to the non-fluorescent transparent state, and the material can maintain stable performance and have pH response performance after 1000 times of color change.

Comparative example 1

1g of hexamethylene diisocyanate and 5g of polycarbonate diol are dissolved in 40g of tetrahydrofuran, then the mixture is heated to 50 ℃ and is stirred at 1500rpm for 1 hour, then 1g of 1, 2-propylene glycol is added, 0.15 wt% of dibutyltin dilaurate is slowly and dropwise added for further reaction for 1 hour, then 0.1g of fluorescein is added into the reactant, the reaction is further heated for 3 hours, after the reaction is finished, the reactant is soaked and washed for 3 times by acetone to remove monomers which do not participate in the reaction, then the reactant is placed in a vacuum oven for drying treatment for 2 hours, and the obtained polyurethane is colorless and transparent and has the molecular weight of 9000.

The luminescence test was performed in the same manner as in example 1, and it was found that there was no change in color and fluorescence after irradiation with ultraviolet light, and also no change in color and fluorescence after heating under visible light.

Comparative example 2

1g of lucifer yellow and 1.5g of octadecylamine were added to a mixture of 15g of ethanol and 15g of isopropanol, and then the mixture was heated to 60 ℃ and reacted at 1000rpm for 15gh, after cooling the product is dried and purified by chromatography to obtain the white fluorescing yellow derivative, which is obtained¹The H NMR measurement results were substantially the same as in example 1;

1g of hexamethylene diisocyanate and 5g of polytetrahydrofuran glycol are dissolved in 40g of tetrahydrofuran, then the mixture is heated to 50 ℃ and is stirred at 1500rpm for 1 hour, then 1g of 1, 2-propylene glycol is added, 0.15 wt% of dibutyltin dilaurate is slowly and dropwise added for further reaction for 1 hour, then 0.1g of a fluorescent yellow derivative is added into the reactant, the heating reaction is continued for 3 hours, after the reaction is finished, acetone is used for soaking and washing for 3 times to remove monomers which do not participate in the reaction, then the reactant is placed in a vacuum oven for drying treatment for 5 hours, and the obtained polyurethane is colorless and transparent and has the molecular weight of 8000.

The luminescence test was performed in the same manner as in example 1, and it was found that there was no change in color and fluorescence after irradiation with ultraviolet light, and also no change in color and fluorescence after heating under visible light.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.