A force-induced color-changing polyester polyol, and a preparation method and use thereof

Abstract

This invention mainly provides a mechanochromic polyester polyol, its preparation method, and its uses. The mechanochromic polyester polyol is prepared by esterification and polycondensation reactions of raw materials comprising 100 moles of a diacid / anhydride, 110-400 moles of a polyol, and 5-30 moles of a trihydroxyrhodamine derivative. The polyester polyol prepared by this invention contains mechanosensitive groups, aromatic rings, and a bialicyclic structure. The resulting polyurethane material exhibits excellent mechanochromic properties and high wear resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polyester polyol preparation, and relates to a mechanochromic polyester polyol, a preparation method and use thereof, and the obtained polyester polyol has high wear resistance. BACKGROUND

[0002] Mechanochromic materials are a class of materials whose optical properties change significantly under external stress, i.e. mechanical changes can be converted into optical changes visible to the naked eye. Such materials have wide application prospects in the fields of color-changing fibers, anti-counterfeiting devices, stress sensors and intelligent wearable devices. Polyurethane materials are a class of multi-purpose synthetic resins with diverse product forms, and their performance is affected by the types and proportions of soft and hard segments in the structure. At the same time, the structure of polyurethane can be adjusted, and the mechanical properties are excellent, the raw materials are diverse and the synthesis is relatively simple, which makes it widely used in the fields of textile materials, sensors and self-repairing materials, etc. Therefore, it is naturally advantageous to use polyurethane as the base material of mechanochromic materials.

[0003] Currently, there are mainly two types of mechanochromic polyurethane materials: blended and covalently connected. The blended type is mainly to add mechanochromic reagents to polyurethane materials, but the mechanochromic reagents in this type of material tend to aggregate and are unevenly distributed, ultimately resulting in poor sensitivity, contrast and reversibility of the material color change, and affecting the mechanical properties of the material. The covalently connected type is mainly to connect mechanochromic molecules to the polyurethane molecular chain through covalent bonds. Currently, the main method is to use mechanochromic molecules as chain extenders. In this type of material, the amount of mechanochromic molecules added is small, and the distribution is large. The color change performance of the material is poor. CN113354789A uses a hydroxyl rhodamine molecule as a chain extender to prepare a polyurethane material. This type of material has certain color change properties, but the color change effect and the mechanical properties of the material still need to be further improved.

[0004] Polyester polyol is a raw material for polyurethane, which is prepared by esterification and polycondensation of polybasic acid / anhydride and polyol. Introducing a mechanochromic small molecule with a specific structure into the polyester polyol can not only endow the polyurethane material with color change properties, but also improve the mechanical properties and wear resistance of the product. Therefore, it is particularly important to prepare a mechanochromic polyester polyol. SUMMARY

[0005] In view of the problems existing in the current mechanochromic polyurethane materials, the purpose of the present application is to provide a mechanochromic polyester polyol. The mechanochromic small molecule containing a double aliphatic ring is introduced into the polyester polyol, which can improve the color change sensitivity, contrast, reversibility and wear resistance of the polyurethane material.

[0006] Another purpose of the present application is to provide a preparation method of the mechanochromic polyester polyol. The method is simple, and the color change groups in the prepared polyester polyol are uniformly distributed.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] On one hand, the present invention provides a mechanochromic polyester polyol, which is prepared from raw materials comprising the following components:

[0009] Component A: Dicarboxylic acid or diacid anhydride, 100 molar parts;

[0010] Component B: Polyol, 110-400 molar parts, preferably 110-200 molar parts;

[0011] Component C: Trihydroxyrhodamine derivative, 5-30 moles, preferably 10-25 moles.

[0012] In component A of the color-changing polyester polyol of the present invention, the dicarboxylic acid is selected from aliphatic dicarboxylic acids with 2-20 carbon atoms and aromatic dicarboxylic acids with 6-20 carbon atoms; the dicarboxylic acid anhydride is selected from aliphatic anhydrides with 4-20 carbon atoms or aromatic anhydrides with 6-20 carbon atoms; preferably, the aliphatic or aromatic dicarboxylic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, furanyl dicarboxylic acid, phthalic acid, isophthalic acid, or terephthalic acid, more preferably succinic acid and / or adipic acid; the aliphatic or aromatic anhydride is preferably selected from one or more of succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, or phthalic anhydride, more preferably succinic anhydride.

[0013] In component B of the mestichromic polyester polyol of the present invention, the polyol is selected from polyols having 2-20 carbon atoms; preferably, the polyol is selected from one or more of ethylene glycol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, butylethylpropanediol, diethylpentanediol, trimethylpentanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanediol, trimethylolpropane, glycerol, and pentaerythritol; more preferably, the polyol is selected from one or more of ethylene glycol, 1,4-butanediol, and neopentyl glycol.

[0014] The component C structure of the mechanochromic polyester polyol described in this invention is shown below:

[0015]

[0016] Wherein, R1 is a C1-C6 alkyl chain, preferably one of -CH2-, -(CH2)2-, and -(CH2)3-; R2 is an alkyl structure containing 6-10 carbon atoms in a bialicyclic ring, preferably... One of them.

[0017] The synthesis method of component C of the high adhesion polyester polyol described in this invention is referenced in the literature "Novel Reversible Mechanochromic Elastomer with High Sensitivity: Bond Scission and Bending-Induced Multicolor Switching".

[0018] As a preferred embodiment, the preparation method of component C includes the following steps: (1) Rhodamine 6G and ethanolamine are refluxed in acetonitrile solution for 18-30 h, and the product is purified by column chromatography to obtain a grayish-white powdery monohydroxyrhodamine derivative; (2) A bromoalkyl alcohol containing a bialiphatic ring structure is added to the monohydroxyrhodamine derivative, and the mixture is heated for 18-30 h, and the product is purified by column chromatography to obtain component C trihydroxyrhodamine derivative, wherein the bromoalkyl alcohol containing a bialiphatic ring structure is preferably one or both of 5-bromomethylbicyclo[2.2.1]-heptane-2-ol and 7-bromomethylbicyclo[3.2.1]octane-2-ol.

[0019] Preferably, in step (1), the molar ratio of rhodamine 6G to ethanolamine is 1.5:1.0-1.0:1.5, more preferably 1.2:1.0-1.0:1.2; and / or, in step (2), the molar ratio of the monohydroxy rhodamine derivative to the bromoalkyl alcohol containing a bialicyclic structure is 1.0:2.0-1.0:2.5, more preferably 1.0:2.0-1.0:2.2; and / or, the reaction temperature is 90-110℃, more preferably 95-105℃.

[0020] As a preferred embodiment, the preparation method of component C includes the following steps: (1) Rhodamine 6G and ethanolamine are refluxed in acetonitrile solution at a molar ratio of 1:1 for 18-30 h, and the product is purified by column chromatography to obtain a grayish-white powdery monohydroxyrhodamine derivative; (2) Bromoalkyl alcohol containing a bialiphatic ring structure is added to the monohydroxyrhodamine derivative at a molar ratio of 1:2, and the mixture is heated at 95-105℃ for 18-30 h, and the product is purified by column chromatography to obtain component C trihydroxyrhodamine derivative, wherein the bromoalkyl alcohol containing a bialiphatic ring structure is preferably one or more of 5-bromomethylbicyclo[2.2.1]-heptane-2-ol and 7-bromomethylbicyclo[3.2.1]octane-2-ol.

[0021] In this invention, the acid value of the thermochromic polyester polyol is 0.01-5.00 mg KOH / g, and the hydroxyl value is 10-200 mg KOH / g. In some preferred embodiments, the acid value of the polyester polyol is 0.05-1.00 mg KOH / g, and the hydroxyl value is 30-100 mg KOH / g. In some more preferred embodiments, the acid value of the polyester polyol is 0.05-0.50 mg KOH / g, and the hydroxyl value is 50-100 mg KOH / g.

[0022] On the other hand, the present invention also provides a method for preparing a mechanochromic polyester polyol, the method comprising the following steps:

[0023] Under inert gas protection, components A, B, and C are reacted at 140-160℃ for 0.5-1.5 h; then the temperature is raised to 170-180℃ and reacted for another 0.5-1.5 h; finally, the temperature is raised to 210-230℃, a catalyst is optionally added, and the reaction continues under vacuum until the acid value of the system is 0.01-5 mg KOH / g and the hydroxyl value is 10-200 mg KOH / g, to obtain the polyester polyol.

[0024] In the polyester polyol provided by the present invention, the amount of catalyst used is 0-500 ppm, preferably 40-300 ppm, based on the total mass of components A, B and C.

[0025] In some specific embodiments, the catalyst is selected from one or more of titanium catalysts, tin catalysts, or antimony catalysts; preferably, the titanium catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate, or titanium dioxide; the tin catalyst is selected from dibutyltin dilaurate, stannous octoate, or stannous chloride; the antimony catalyst is selected from antimony acetate, antimony trioxide, or antimony glycolate; in some preferred embodiments, the catalyst is a titanium catalyst, more preferably tetrabutyl titanate or tetraisopropyl titanate.

[0026] The present invention also provides the use of the polyester polyol in the preparation of polyurethane elastomers.

[0027] The present invention also provides a polyurethane elastomer, which is obtained by reacting a component comprising the following raw materials: (molar percentage)

[0028] Color-changing polyester polyol: 60%-75%

[0029] Polyisocyanates: 15%-30%

[0030] Chain extender: 1%-10%

[0031] Catalyst: 0-50ppm

[0032] In some specific embodiments, the polyisocyanate monomer is selected from one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), hexanedimethyl diisocyanate (HMDI), naphthalene diisocyanate (NDI), terephthalic diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), phenylmethylene diisocyanate (XDI), or cyclohexanedimethyl diisocyanate (HXDI); in some preferred embodiments, the polyisocyanate monomer is diphenylmethane diisocyanate (MDI).

[0033] In some specific embodiments, the chain extender is selected from polyols having 2-20 carbon atoms; preferably, the chain extender is selected from one or more of ethylene glycol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, and 1,3-butanediol; more preferably, the chain extender is 1,4-butanediol.

[0034] In some specific embodiments, the catalyst is selected from tertiary amines and organometallic compounds, preferably from triethylenediamine, N,N-dimethylcyclohexylamine, dibutyltin dilaurate, stannous octoate, bismuth carboxylate, and more preferably stannous octoate.

[0035] The preparation method of polyurethane elastomer can refer to conventional methods in the art, for example: 1) Dehydrate the methochromic polyester polyol at 110-125℃ under vacuum for 0.5-2h; 2) Then, place the methochromic polyester polyol in a suitable container, add diisocyanate, chain extender and catalyst and stir rapidly until the temperature rises to 90-150℃, preferably 110-130℃, and stop stirring to obtain a gel; 3) Quickly pour the gel obtained in step 2) into a mold to obtain thermoplastic polyurethane elastomer.

[0036] The positive effects of this invention are as follows:

[0037] (1) The high abrasion resistant mechanochromic polyester polyol of the present invention contains a high content of mechanochromic groups, which can give polyurethane materials a better color-changing effect.

[0038] (2) The high wear-resistant mechanochromic polyester polyol of the present invention contains a certain amount of aromatic rings and aliphatic rings, which can give polyurethane materials good wear resistance. Attached Figure Description

[0039] Figure 1 The NMR spectrum of C1 of the trihydroxyrhodamine derivative is shown.

[0040] Figure 2 The NMR spectrum of C2 of the trihydroxyrhodamine derivative is shown.

[0041] Figure 3 The NMR spectrum of C3 of the trihydroxyrhodamine derivative is shown.

[0042] Figure 4 The rRC of TPU-E, TPU-A and TPU-F as a function of pressure is shown. Detailed implementation method:

[0043] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0044] The main raw materials used in the following examples and comparative examples are all commercially available chemicals. 5-bromomethylbicyclo[2.2.1]-heptane-2-ol, 7-bromomethylbicyclo[3.2.1]octane-2-ol and 5-bromoethylbicyclo[2.2.1]-heptane-2-ol were purchased from Shenzhen Aituo Chemical Co., Ltd.; ethanolamine, rhodamine 6G and stannous octoate were purchased from Beijing Bailingwei Technology Co., Ltd.; 1,4-butanediol, neopentyl glycol, ethylene glycol, 1,3-propanediol, adipic acid and terephthalic acid were purchased from Wanhua Chemical.

[0045] The product performance was measured in the embodiments and comparative examples of this invention using the following methods:

[0046] Acid value determination: Refer to chemical industry standard HG / T 2708-1995;

[0047] Determination of hydroxyl value: Refer to chemical industry standard HG / T 2709-1995;

[0048] Abrasion resistance test: Refer to international standard ISO 4649-2017.

[0049] Mechanism-induced color change performance determination: Polyurethane films were subjected to different pressures ranging from 0 to 1000 MPa using an ultra-high pressure device (WES-hydraulic universal testing machine, Shanghai Xieqiang Instruments). Canon EOS 70D cameras were used to take pictures under D65 light sources. The RGB values ​​representing color characteristics during the color change and fading processes were read using the color picker tool of Photoshop software. In order to digitally describe the color change, the color coordinates of the sample photos under different pressures were extracted, and the relationship between the red light component rRC at the stress point of the material and the pressure was analyzed. The red light component rRC = R / (R+G+B), where R, G, and B are the average intensities of the red, green, and blue channels, respectively.

[0050] Components C1, C2, and C3 used in the examples were prepared by the following method: Rhodamine 6G and ethanolamine were refluxed in acetonitrile solution at a molar ratio of 1:1 for 24 hours. The product was purified by column chromatography to obtain a grayish-white powder of monohydroxyrhodamine derivative. Then, 5-bromomethylbicyclo[2.2.1]-heptane-2-ol, 7-bromomethylbicyclo[3.2.1]octane-2-ol, or 5-bromoethylbicyclo[2.2.1]-heptane-2-ol was added to the monohydroxyrhodamine derivative at a molar ratio of 1:2. The mixture was heated at 100°C for 24 hours. The product was purified by column chromatography to obtain a powder of trihydroxyrhodamine derivative. The structural diagrams of C1, C2, and C3 are shown below:

[0051]

[0052]

[0053] Example 1

[0054] 9.91 kg of 1,4-butanediol, 22.26 kg of rhodamine derivative C1, and 14.61 kg of adipic acid were mixed evenly and heated to 150 °C and held at that temperature for 1.0 h. The temperature was then further increased to 175 °C and held at that temperature for 1.0 h. Finally, the temperature was raised to 220 °C. When the acid value was less than 10 mg KOH / g, 1.87 g of tetraisopropyl titanate was added, and the reaction was carried out for 1 h. The vacuum was then turned on to -0.090 MPa to remove the water and excess diol from the reaction product. After the acid value and hydroxyl value were qualified, the product was cooled and discharged to obtain metronidazole polyester polyol A, which has an acid value of 0.05 mg KOH / g, a hydroxyl value of 56.1 mg KOH / g, and an average molecular weight of 2000 g / mol.

[0055] Example 2

[0056] 18.62 kg of ethylene glycol, 11.55 kg of rhodamine derivative C2, and 11.81 kg of succinic acid were mixed evenly and heated to 150 °C and held at that temperature for 1.5 h. The temperature was then increased to 170 °C and held at that temperature for 0.75 h. Finally, the temperature was raised to 210 °C. When the acid value was less than 10 mg KOH / g, 4.20 g of tetraisopropyl titanate was added, and the reaction was continued for 3 h. The vacuum was then turned to -0.090 MPa to remove the water and excess diol from the reaction product. After the acid value and hydroxyl value were deemed acceptable, the product was cooled and discharged to obtain metronidazole polyester polyol B, which has an acid value of 0.10 mg KOH / g, a hydroxyl value of 44.88 mg KOH / g, and an average molecular weight of 2500 g / mol.

[0057] Example 3

[0058] 20.83 kg of neopentyl glycol, 14.84 kg of rhodamine derivative C3, and 10.01 kg of succinic anhydride were mixed evenly and heated to 140 °C and held at that temperature for 1.5 h. The temperature was then further increased to 180 °C and held at that temperature for 0.5 h. Finally, the temperature was raised to 230 °C. When the acid value was less than 15 mg KOH / g, 9.14 g of tetrabutyl titanate was added, and the reaction was carried out for 4 h. The vacuum was then turned on to -0.090 MPa to remove the water and excess diol from the reaction product. After the acid value and hydroxyl value were qualified, the product was cooled and discharged to obtain the color-changing polyester polyol C, which has an acid value of 2.50 mg KOH / g, a hydroxyl value of 37.40 mg KOH / g, and an average molecular weight of 3000 g / mol.

[0059] Example 4

[0060] 36.05 kg of 1,4-butanediol, 3.85 kg of rhodamine derivative C2, and 14.61 kg of adipic acid were mixed evenly and heated to 160 °C and held at that temperature for 0.5 h. The temperature was then increased to 180 °C and held at that temperature for 1.5 h. Finally, the temperature was raised to 220 °C. When the acid value was less than 15 mg KOH / g, 16.35 g of tetrabutyl titanate was added, and the reaction was carried out for 4 h. The vacuum was then turned on to -0.090 MPa to remove water and excess diol from the reaction product. After the acid value and hydroxyl value were qualified, the product was cooled and discharged to obtain the color-changing polyester polyol D, which has an acid value of 5 mg KOH / g, a hydroxyl value of 112 mg KOH / g, and an average molecular weight of 1000 g / mol.

[0061] Comparative Example 1

[0062] 9.91 kg of 1,4-butanediol and 14.61 kg of adipic acid were mixed evenly and heated to 150 °C and held at that temperature for 1.0 h. The temperature was then increased to 175 °C and held at that temperature for 1.0 h. Finally, the temperature was raised to 220 °C. When the acid value was less than 10 mg KOH / g, 1.87 g of tetraisopropyl titanate was added and the mixture was reacted for 1 h. The vacuum was then turned to -0.090 MPa to remove the water and excess diol from the reaction product. After the acid value and hydroxyl value were deemed acceptable, the mixture was cooled and discharged to obtain the color-changing polyester polyol E, which has an acid value of 0.05 mg KOH / g, a hydroxyl value of 56.1 mg KOH / g, and an average molecular weight of 2000 g / mol.

[0063] Application Examples 1-6 illustrate the preparation of polyurethane elastomers TPU-A to TPU-G.

[0064] Application Examples 1-6

[0065] According to the following formula, polyurethane elastomer materials can be prepared by following these steps: Dehydrate and dry the measured polyester polyol at 120°C under vacuum for 1 hour, then add MDI, chain extender and catalyst stannous octoate (T9) according to the measured ratio, stir rapidly, and stop stirring when the material temperature reaches 120°C. Pour the material into a container coated with a release agent and let it stand in an oven at 130°C for 3 hours to obtain the polyurethane elastomer material.

[0066] Table 1-5 shows the synthesis formulations (molar parts) for polyurethane elastomers used in application examples 1-5.

[0067]

[0068] Performance testing

[0069] The mechanochromic properties of polyurethane materials prepared from high-abrasion-resistant mechanochromic polyester polyols were determined according to the above method, and the results are as follows: Figure 3 As shown in the figure, the rRC of TPU-E prepared using conventional polyester polyols remains essentially unchanged under different pressure conditions, indicating that this polyurethane material has no mechanochromic properties. In contrast, the rRC value of TPU-A, a polyurethane elastomer prepared using the high-abrasion-resistant mechanochromic polyester polyol of this invention, remains essentially unchanged when the pressure is less than 200 MPa, but increases rapidly when the pressure exceeds 200 MPa, indicating that this material has good mechanochromic properties, with a critical pressure of 200 MPa. Meanwhile, the TPU-F polyurethane elastomer prepared using rhodamine derivatives as chain extenders exhibits mechanochromic properties, but its mechanochromic sensitivity and color intensity are relatively weak.

[0070] Meanwhile, the wear resistance of the polyurethane materials prepared in the embodiments and comparative examples of this invention was tested using ISO 4969, and the results are shown in the table below. It can be seen from the table that the wear resistance of the polyurethane material prepared using the embodiments of this invention is significantly better than that of the polyurethane material prepared using PBA2000. This is mainly because the polyester polyol prepared in the embodiments of this invention contains a large number of aliphatic ring structures, which can improve the wear resistance of the polyurethane material.

[0071] Table comparing the performance of high-adhesion polyurethanes prepared from polyester polyols in the examples and comparative examples.

[0072]

Claims

1. A mechanochromic polyester polyol, prepared from raw materials comprising the following components: Component A: Dicarboxylic acid or diacid anhydride, 100 molar parts; Component B: Polyol, 110-400 molar parts; Component C: Trihydroxyrhodamine derivative, 5-30 moles; in, Component C has a structure as shown in C1 or C2:

2. The polyester polyol as described in claim 1, characterized in that, Component B is 110-200 moles and component C is 10-25 moles.

3. The polyester polyol as described in claim 1, characterized in that, In component A, the dicarboxylic acid is selected from aliphatic dicarboxylic acids with 2-20 carbon atoms or aromatic dicarboxylic acids with 6-20 carbon atoms, and the dicarboxylic acid anhydride is selected from aliphatic acid anhydrides with 4-20 carbon atoms or aromatic acid anhydrides with 6-20 carbon atoms.

4. The polyester polyol as described in claim 3, characterized in that, The aliphatic or aromatic dicarboxylic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, furanyl dicarboxylic acid, phthalic acid, isophthalic acid, or terephthalic acid; the aliphatic or aromatic anhydride is selected from one or more of succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, or phthalic anhydride.

5. The polyester polyol as described in claim 1, characterized in that, In component B, the polyol is selected from polyols with 2-20 carbon atoms.

6. The polyester polyol as described in claim 5, characterized in that, The polyol is selected from one or more of ethylene glycol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, butyl ethyl propylene glycol, diethylpentanediol, trimethylpentanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanediol, trimethylolpropane, glycerol, and pentaerythritol.

7. The polyester polyol according to claim 1, characterized in that, The preparation method of component C includes the following steps: (1) Rhodamine 6G and ethanolamine are refluxed in solution for 18-30 h, the product is purified, and a grayish-white powdery monohydroxyrhodamine derivative is obtained; (2) a bromoalkyl alcohol containing a bialiphatic ring structure is added to the monohydroxyrhodamine derivative, the reaction is heated for 18-30 h, the product is purified, and component C trihydroxyrhodamine derivative is obtained.

8. The polyester polyol as described in claim 7, characterized in that, In step (2), the bromoalkyl alcohol containing a bialicyclic structure is one of 5-bromomethylbicyclo[2.2.1]-heptane-2-ol and 7-bromomethylbicyclo[3.2.1]octane-2-ol.

9. The polyester polyol as described in claim 7 or 8, characterized in that, In step (1), the molar ratio of rhodamine 6G to ethanolamine is 1.5:1.0-1.0:1.5; and / or, in step (2), the molar ratio of the monohydroxy rhodamine derivative to the bromoalkyl alcohol containing a bialicyclic structure is 1.0:2.0-1.0:2.5; and / or, the reaction temperature is 90-110℃.

10. The polyester polyol according to claim 9, characterized in that, In step (1), the molar ratio of rhodamine 6G to ethanolamine is 1.2:1.0-1.0:1.2; and / or the molar ratio of monohydroxyrhodamine derivative to bromoalkyl alcohol containing a bialicyclic structure is 1.0:2.0-1.0:2.2; and / or the reaction temperature is 95-105℃.

11. The method for preparing polyester polyol according to any one of claims 1-10, wherein the method comprises the following steps: Under inert gas protection, components A, B, and C are mixed and reacted at 140-160°C for 0.5-1.5 hours; then the temperature is raised to 170-180°C and reacted for another 0.5-1.5 hours; finally, the temperature is raised to 210-230°C, a catalyst is optionally added, and the reaction continues under vacuum until the acid value of the system is 0.01-5 mg KOH / g and the hydroxyl value is 10-200 mg KOH / g, thus obtaining the polyester polyol.

12. The preparation method according to claim 11, characterized in that, The amount of catalyst used is 0-500 ppm based on the total mass of components A, B and C.

13. The preparation method according to claim 12, characterized in that, The amount of catalyst used is 40-300 ppm based on the total mass of components A, B and C.

14. The preparation method according to claim 11, characterized in that, The catalyst is selected from one or more of titanium catalysts, tin catalysts, or antimony catalysts.

15. The preparation method according to claim 14, characterized in that, The titanium catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate, or titanium dioxide; the tin catalyst is selected from dibutyltin dilaurate, stannous octoate, or stannous chloride; and the antimony catalyst is selected from antimony acetate, antimony trioxide, or antimony glycol.

16. Use of the polyester polyol according to any one of claims 1-10 or the polyester polyol prepared by the preparation method according to any one of claims 11-15 in the preparation of polyurethane elastomers.

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