Preparation method of thermochromic material

Abstract

The invention relates to a preparation method of a thermochromic material, in particular to a preparation method of a thermochromic material. In order to solve the problem that heat resistance and light aging resistance of an existing thermochromic material cannot meet actual application requirements, o-phenyl phenoxyethyl acrylate, 2-phenoxyethyl acrylate, ionic liquid, a photoinitiator and a cross-linking agent are mixed and subjected to light curing to form the thermochromic material. The thermochromic material provided by the invention realizes a color changing effect through phase structure regulation and control, belongs to a physical process, is not influenced by light, can tolerate ultraviolet aging for more than 1000 hours and multiple high and low temperature cycles, and improves the stability, durability and light resistance of the thermochromic material. The invention is applied to the polymer intelligent response material.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a thermochromic material. BACKGROUND

[0002] The thermochromic material refers to a material which changes color during the change of ambient temperature. The current thermochromic material (commonly known as temperature change powder) is mainly composed of three parts: a thermochromic dye, a color developing agent and a solvent. In a high temperature state, the thermochromic dye and the color developing agent are dissolved and dispersed in the solvent, and the system presents a white state. When the temperature decreases, the solvent gradually solidifies, and the thermochromic dye and the color developing agent are close to each other, and the thermochromic dye changes structure under the action of the color developing agent, so that the system presents color. By adjusting the solidification temperature of the solvent, a temperature change product which changes color at different temperatures can be prepared. At present, the thermochromic material has been widely used in various fields of daily life, such as heat-sensitive dyes, thermochromic porcelain glaze, anti-counterfeiting materials and the like. With the development of new thermochromic materials, its application has gradually expanded to the fields of analysis, sensors and other high-tech fields.

[0003] However, the thermochromic dye is not resistant to ultraviolet radiation and is easily decomposed under ultraviolet radiation, thereby losing the thermochromic function. Moreover, the thermochromic material is easily damaged by chemicals, thereby reducing the thermochromic effect. The light resistance, heat resistance, aging resistance and mechanical properties of the current thermochromic material are difficult to meet the actual application requirements. If it is used outdoors, it needs to be packaged for use. Therefore, it is necessary to improve the current thermochromic material and the preparation method, so that it is suitable for outdoor conditions. SUMMARY

[0004] The present application aims to solve the problem that the heat resistance and light aging resistance of the current thermochromic material cannot meet the actual application requirements, and to provide a preparation method of a thermochromic material.

[0005] The present application relates to a preparation method of a thermochromic material.

[0006] I. mixing o-phenylphenoxyethyl acrylate, a photoinitiator and a crosslinking agent to obtain a prepolymer 1;

[0007] II. mixing 2-phenoxyethyl acrylate, a photoinitiator and a crosslinking agent to obtain a prepolymer 2;

[0008] III. mixing the prepolymer 1 and the prepolymer 2, and ultrasonicating for 30-60s to obtain a prepolymer 3;

[0009] IV. mixing the prepolymer 3 with an ionic liquid, and then performing light curing to obtain a thermochromic material.

[0010] The principle realized by the present application is that the color change effect is realized by the temperature response polymer gel, at normal temperature, the high molecular polymer phase composed of two kinds of acrylates and the phase of ionic liquid are mutually soluble, and are completely fused with each other at the molecular level, so that the ionic liquid gel at normal temperature presents a transparent effect; when the temperature rises, phase separation occurs, the high molecular polymer phase and the ionic liquid phase are separated, and the refractive indexes of the high molecular polymer phase and the ionic liquid phase are different, which produces scattering effect on light, so that the gel presents white color, and because the o-phenylphenoxyethyl acrylate used is a high refractive acrylate, the greater the difference in refractive index after phase change, the whiter the gel presents, and vice versa, and the 2-phenoxyethyl acrylate plays a regulating role, the mixing effect of pure o-phenylphenoxyethyl acrylate and ionic liquid is pure white, and the mixing of pure 2-phenoxyethyl acrylate and ionic liquid is completely transparent, so the two kinds of acrylates are mixed in a certain ratio to regulate the phase structure between transparency and white color.

[0011] In addition, another component in the present application uses ionic liquid, which is a very stable, non-volatile liquid state molten salt at normal temperature, and the ionic liquid and the o-phenylphenoxyethyl acrylate cooperate with each other, so that when the gel is used, the overall components remain basically unchanged even under outdoor conditions, compared with other unstable and volatile substances, after volatilization of the substance, the components of the gel change, thereby losing the thermosensitive color change effect. Therefore, the thermosensitive color-changing material proposed in the present application realizes the color change effect through phase structure regulation, and does not use color-changing dyes, so it will not appear that the color-changing dyes are decomposed due to outdoor light irradiation, thereby causing the color change effect to be poor; the stability, durability and light resistance of the present application are improved.

[0012] The present application has the following advantages:

[0013] 1、The material of the present application is formed by mixing o-phenylphenoxyethyl acrylate, 2-phenoxyethyl acrylate, ionic liquid, photoinitiator and crosslinking agent and light curing, and the obtained gel has certain tensile property. Moreover, the temperature regulation of the phase structure is a reversible process, after heating and turning white, the gel will turn from white to transparent again when the temperature decreases to normal temperature, so the present application is a reversible color-changing thermosensitive material and can be recycled.

[0014] 2、The temperature response speed of the present application is relatively fast, and the effect is obvious.

[0015] 3、The existing color-changing material is added with color-changing dyes, which works through dye molecules, and organic dyes are afraid of light and are easily affected by light. But the present application belongs to a physical process and is not affected by light, so it is beneficial to use under outdoor conditions, and the ionic liquid gel of the present application can withstand a temperature of more than 70 DEG C, and the highest temperature can withstand 200 DEG C, basically meeting the relatively harsh outdoor environment.

[0016] 4、The present application responds to different thickness of ion gel with different temperature, and can be selected according to the use environment, 1mm thick gel film completely turns white for about 100℃; and 0.5mm thick gel film completely turns white for about 70℃.

[0017] 5、The preparation method provided by the present application is directly mixing all components in proportion and then performing photocuring, which involves simple preparation process, rapid reaction, convenient operation, and can be prepared in large quantities to realize industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a product forming effect diagram of the present application;

[0019] Figure 2 is a heating effect diagram of 1mm thickness film at 40℃;

[0020] Figure 3 is a heating effect diagram of 1mm thickness film at 50℃;

[0021] Figure 4 is a heating effect diagram of 1mm thickness film at 60℃;

[0022] Figure 5 is a heating effect diagram of 1mm thickness film at 70℃;

[0023] Figure 6 is a heating effect diagram of 1mm thickness film at 80℃;

[0024] Figure 7 is a heating effect diagram of 1mm thickness film at 90℃;

[0025] Figure 8 is a heating effect diagram of 1mm thickness film at 100℃;

[0026] Figure 9 is a heating effect diagram of 0.5mm thickness film at 40℃;

[0027] Figure 10 is a heating effect diagram of 0.5mm thickness film at 50℃;

[0028] Figure 11 is a heating effect diagram of 0.5mm thickness film at 60℃;

[0029] Figure 12 is a heating effect diagram of 0.5mm thickness film at 70℃;

[0030] Figure 13 is a heating effect diagram of 0.5mm thickness film at 80℃;

[0031] Figure 14 Heating effect plot for 0.5 mm thickness film at 90 °C;

[0032] Figure 15 Heating effect plot for 0.5 mm thickness film at 100 °C;

[0033] Figure 16 Heating effect plot for 0.05 mm and 0.2 mm thickness film at 55 °C;

[0034] Figure 17 Heating effect plot for 0.05 mm and 0.2 mm thickness film at 65 °C;

[0035] Figure 18 Heating effect plot for 0.05 mm and 0.2 mm thickness film at 75 °C;

[0036] Figure 19 Heating effect plot for 0.05 mm and 0.2 mm thickness film at 85 °C;

[0037] Figure 20 Heating effect plot for 0.05 mm and 0.2 mm thickness film at 100 °C;

[0038] Figure 21 Heating effect plot for 0.05 mm, 0.2 mm and 0.4 mm thickness film at 50 °C, 55 °C, 60 °C, 65 °C respectively;

[0039] Figure 22 Heating effect plot for 0.05 mm, 0.2 mm and 0.4 mm thickness film at 70 °C, 75 °C, 80 °C, 85 °C respectively;

[0040] Figure 23 Heating effect plot for 0.05 mm, 0.2 mm and 0.4 mm thickness film at 90 °C, 95 °C, 100 °C respectively;

[0041] Figure 24 Gel film before UV resistance test;

[0042] Figure 25 Gel film after UV resistance test;

[0043] Figure 26 Gel film after UV resistance test;

[0044] Figure 27 Gel film before high-low temperature cycle test;

[0045] Figure 28 Gel film after high-low temperature cycle test;

[0046] Figure 29 The gel film after high and low temperature cycle test. DETAILED DESCRIPTION

[0047] Embodiment I: The preparation method of the thermosensitive color-changing material in this embodiment is carried out according to the following steps:

[0048] I. mixing o-phenylphenoxyethyl acrylate, a photoinitiator and a crosslinking agent to obtain a prepolymer 1;

[0049] II. mixing 2-phenoxyethyl acrylate, a photoinitiator and a crosslinking agent to obtain a prepolymer 2;

[0050] III. mixing the prepolymer 1 and the prepolymer 2, and ultrasonicating for 30-60 s to obtain a prepolymer 3;

[0051] IV. mixing the prepolymer 3 with an ionic liquid, and then performing light curing to obtain the thermosensitive color-changing material.

[0052] The same photoinitiator and crosslinking agent are used in step I and step II

[0053] Embodiment II: The difference between this embodiment and embodiment I is that the molar ratio of o-phenylphenoxyethyl acrylate, the photoinitiator and the crosslinking agent is 1:0.05-0.005:0.01-0.005. The other parts are the same as in embodiment I.

[0054] Embodiment III: The difference between this embodiment and embodiment I or II is that the molar ratio of 2-phenoxyethyl acrylate, the photoinitiator and the crosslinking agent is 1:0.05-0.005:0.01-0.005. The other parts are the same as in embodiment I or II.

[0055] Embodiment IV: The difference between this embodiment and any one of embodiments I to III is that 2-phenoxyethyl acrylate in step II is replaced by tetrahydrofurfuryl acrylate. The other parts are the same as in any one of embodiments I to III.

[0056] Embodiment V: The difference between this embodiment and any one of embodiments I to IV is that the photoinitiator is photoinitiator 819, photoinitiator 1173, photoinitiator 2959, photoinitiator 907, TPO or photoinitiator 184. The other parts are the same as in any one of embodiments I to IV.

[0057] Embodiment VI: The difference between this embodiment and any one of embodiments I to V is that the crosslinking agent is a multifunctional acrylate. The other parts are the same as in any one of embodiments I to V.

[0058] Specific embodiment seven: different from one of the specific embodiments one to six is that the crosslinking agent is hexanediol diacrylate, and the others are the same as one of the specific embodiments one to six.

[0059] Specific embodiment eight: different from one of the specific embodiments one to seven is that the volume ratio of the prepolymer 1 and the prepolymer 2 is 1:1-3. The others are the same as one of the specific embodiments one to seven.

[0060] Specific embodiment nine: different from one of the specific embodiments one to eight is that the ionic liquid is 1-butyl 3-methyl imidazole hexafluorophosphate, 1-butyl 3-methyl imidazole tetrafluoroborate, 1-butyl 3-methyl imidazole ethyl sulfate, 1-butyl 3-methyl imidazole bis-trifluoroacetate or 1-butyl 3-methyl imidazole bis-trifluoromethyl sulfonimide. The others are the same as one of the specific embodiments one to eight.

[0061] Specific embodiment ten: different from one of the specific embodiments one to nine is that the ionic liquid accounts for 50% of the total volume of the thermochromic material. The others are the same as one of the specific embodiments one to nine.

[0062] Specific embodiment eleven: different from one of the specific embodiments one to ten is that after the step four mixing, pour into a forming mold, and then put in a UV light curing machine, and UV light curing for 3-5 min. The others are the same as one of the specific embodiments one to ten.

[0063] The effect of the present application is verified by the following examples:

[0064] Example 1

[0065] A preparation method of a thermochromic material preparation method includes the following steps:

[0066] I. Add 0.143g of photoinitiator TPO and 0.0463g of crosslinking agent hexanediol diacrylate to 10mL of o-phenylphenoxyethyl acrylate, and ultrasonic for 30-60s to obtain prepolymer 1;

[0067] II. Add 0.195g of photoinitiator TPO and 0.0632g of crosslinking agent hexanediol diacrylate to 10mL of 2-phenoxyethyl acrylate, and ultrasonic for 30-60s to obtain prepolymer 2;

[0068] III. Mix 1mL of prepolymer 1 and 1mL of prepolymer 2, and ultrasonic for 30-60s to obtain prepolymer 3;

[0069] Four, 2mL of prepolymer 3 and 2mL of 1-butyl 3-methyl imidazole hexafluorophosphate were mixed well, poured into a 0.5mm thick mold, placed in a UV light curing machine, light cured for 3-5min, taken out and cooled to room temperature to obtain a thermotropic phase change ionic gel film.

[0070] The prepared sample was transparent at room temperature, and the specific change effect with temperature was shown in the following table: Figures 2-8 As can be seen from the figure, the color gradually turned white with the increase of temperature, and completely turned white at about 100℃.

[0071] Example 2:

[0072] A preparation method of a temperature-sensitive color-changing material includes the following steps:

[0073] One, 0.143g of photoinitiator TPO and 0.0463g of crosslinking agent hexanediol diacrylate were added to 10mL of o-phenylphenoxyethyl acrylate, and ultrasonic treatment was performed for 30-60s to obtain a prepolymer 1;

[0074] Two, 0.195g of photoinitiator TPO and 0.0632g of crosslinking agent hexanediol diacrylate were added to 10mL of 2-phenoxyethyl acrylate, and ultrasonic treatment was performed for 30-60s to obtain a prepolymer 2;

[0075] Three, 1mL of prepolymer 1 and 1mL of prepolymer 2 were mixed, and ultrasonic treatment was performed for 30-60s to obtain a prepolymer 3;

[0076] Four, 2mL of prepolymer 3 and 2mL of 1-butyl 3-methyl imidazole hexafluorophosphate were mixed well, poured into a 0.5mm thick mold, placed in a UV light curing machine, light cured for 3-5min, taken out and cooled to room temperature to obtain a thermotropic phase change ionic gel film.

[0077] The prepared sample was transparent at room temperature, and the specific change effect with temperature was shown in the following table: Figures 9-15 That is, the color gradually turned white with the increase of temperature, and the white color was obvious at about 60℃, and completely turned white at about 70℃ as shown in the following figure: Figure 12 .

[0078] Example 3:

[0079] A preparation method of a temperature-sensitive color-changing material includes the following steps:

[0080] One, 0.143g of photoinitiator TPO and 0.0463g of crosslinking agent hexanediol diacrylate were added to 10mL of o-phenylphenoxyethyl acrylate, and ultrasonic treatment was performed for 30-60s to obtain a prepolymer 1;

[0081] II. To 10 ml of 2-phenoxyethyl acrylate, 0.195 g of photoinitiator TPO and 0.0632 g of crosslinking agent hexanediol diacrylate were added, and ultrasonic was performed for 30-60 s to obtain a prepolymer 2;

[0082] III. 1 mL of the prepolymer 1 and 1 mL of the prepolymer 2 were mixed, and ultrasonic was performed for 30-60 s to obtain a prepolymer 3;

[0083] IV. After 2 mL of the prepolymer 3 and 2 mL of 1-butyl 3-methyl imidazolium hexafluorophosphate were mixed well, they were poured into 0.05 mm, 0.2 mm and 0.4 mm thick molds, and were placed into a UV light curing machine, and light curing was performed for 3-5 min. After being taken out and cooled to room temperature, a thermotropic phase change ionic gel film was obtained.

[0084] The prepared samples were transparent at room temperature, and the specific change effects of the 0.05 mm and 0.2 mm thick gel films with temperature were shown in Figures 16-20 , wherein the left gel film had a thickness of 0.2 mm, and the right gel film had a thickness of 0.05 mm. The specific change effects of the 0.05 mm, 0.2 mm and 0.4 mm thick gel films with temperature were shown in Figures 21-23 , and it could be seen that the color gradually turned white with the increase of temperature. The temperature point of turning white was different with different thicknesses, and the temperature point of turning white was low with large thickness. Figures 16-23

[0085] A 4 mm thick gel film was prepared by using the method of the above embodiment and a 4 mm thick mold, and UV resistance aging test and high and low temperature cycle test were performed. The UV resistance aging (1000 h) was detected by using a UV2000 ultraviolet light aging test machine, and the test conditions were as follows: light source: UVA-340 lamp tube, irradiance: 0.76 W / m 2 @ 340 nm, exposure period: 8 h drying / blackboard temperature (60±3) °C, 4 h condensation / blackboard temperature (50±3) °C, detection standard GB / T14522-2008, and the test result was as follows: after the test, the sample had no falling off, had good tackiness, the sample turned white at 60 °C, the sample color recovered to be transparent at room temperature, and the color change was reversible. Figures 24-26 The pictures of the gel film in the process of the UV resistance aging test were shown in

[0086] ​High and low temperature cycle resistance (120℃→-25℃, 6 cycles), using HC-150D constant temperature and humidity test chamber, test conditions: from 120℃, 110min to reduce the temperature to -25℃ and keep 10min, then from -25℃, 110min to increase the temperature to 120℃ and keep 10min, this is 1 cycle, a total of 6 cycles. Test results: after the test, the sample has no falling, good adhesion, the sample becomes white at 60℃, the sample white deepens at 120℃, the sample color restores transparent at room temperature, the color change is reversible. Figures 27-29 The picture of the gel film during the high and low temperature cycle resistance test.

Claims

1. A method for preparing a thermochromic material, characterized in that... This method is performed in the following steps:

1. Prepolymer 1 is obtained by mixing o-phenylphenoxyethyl acrylate, photoinitiator and crosslinking agent; 2. Mix 2-phenoxyethyl acrylate, photoinitiator and crosslinking agent to obtain prepolymer 2; 3. Mix prepolymer 1 and prepolymer 2 and sonicate for 30-60 seconds to obtain prepolymer 3; 4. Prepolymer 3 is mixed with ionic liquid and then photocured to obtain thermochromic material.

2. The method for preparing a thermochromic material according to claim 1, characterized in that, The molar ratio of o-phenylphenoxyethyl acrylate, photoinitiator and crosslinking agent is 1:0.05-0.005:0.01-0.

005.

3. The method for preparing a thermochromic material according to claim 1, characterized in that, The molar ratio of 2-phenoxyethyl acrylate, photoinitiator and crosslinking agent is 1:0.05-0.005:0.01-0.

005.

4. The method for preparing a thermochromic material according to claim 1, characterized in that, In step two, 2-phenoxyethyl acrylate is replaced with tetrahydrofuran acrylate.

5. The method for preparing a thermochromic material according to claim 1, characterized in that, The photoinitiator is photoinitiator 819, photoinitiator 1173, photoinitiator 2959, photoinitiator 907, TPO or photoinitiator 184.

6. The method for preparing a thermochromic material according to claim 1, characterized in that, The crosslinking agent is a multifunctional acrylate.

7. The method for preparing a thermochromic material according to claim 1, characterized in that, In step three, the volume ratio of prepolymer 1 to prepolymer 2 is 1:1 to 3.

8. The method for preparing a thermochromic material according to claim 1, characterized in that, The ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium bis(trifluoroacetate) or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

9. The method for preparing a thermochromic material according to claim 1, characterized in that, Ionic liquids account for 50% of the total volume of the thermochromic material.

10. The method for preparing a thermochromic material according to claim 1, characterized in that, After mixing in step four, pour the mixture into the molding mold and then place it in a UV curing machine for UV curing for 3-5 minutes.

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