Temperature-induced color-changing vehicle film and preparation method therefor

Abstract

The present invention relates to the field of polyurethane materials and particularly to a temperature-induced color-changing vehicle film and a preparation method therefor. The method of the present invention comprises: firstly, using polyurethane to wrap vanadium dioxide powder to obtain color-changing microcapsules; then using 1,1,1,3,5,5,5-heptamethyltrisiloxane and 3-allyloxy-1,2-propanediol as raw materials to synthesize an organosilicon-modified diol, and enabling trimellitic anhydride to react with toluene diisocyanate to synthesize a dicarboximide compound; enabling the organosilicon-modified diol and the dicarboximide compound to undergo an esterification reaction and a polymerization reaction to obtain an organosilicon-modified imide polyester diol; then mixing the organosilicon-modified imide polyester diol with polytetrahydrofuran ether glycol 2000, and then enabling the mixture to react with toluene diisocyanate to obtain a polyurethane elastomer; and mixing the polyurethane elastomer, the color-changing microcapsules, a silane coupling agent, a plasticizer, an antioxidant, and an ultraviolet light absorber, followed by melt extrusion and blow molding into a film, so as to obtain the temperature-induced color-changing vehicle film.

Description

Temperature discoloration car film and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane materials, in particular to a temperature discoloration car film and a preparation method thereof. BACKGROUND

[0002] The car film is a film-shaped object pasted on the front and rear windshield, side window and sunroof of the vehicle, also known as solar film and heat insulation film. Its main functions include blocking ultraviolet rays, blocking part of heat, preventing glass splashing and causing injury, preventing glare, and protecting personal privacy according to the one-way perspective performance of the solar film. In addition, it can also reduce damage to articles and personnel in the vehicle caused by ultraviolet radiation, reduce the temperature in the vehicle through physical reflection, reduce the use of air conditioning in the vehicle, reduce fuel consumption, and be economic and environmentally friendly.

[0003] Compared with the heat insulation and one-way perspective functions of traditional car films, more and more enterprises are committed to developing temperature discoloration car films. At present, the preparation method of temperature discoloration film is relatively single, which usually involves first preparing temperature discoloration microcapsules, and then directly applying the prepared temperature discoloration microcapsules to the polyurethane film to obtain the temperature discoloration car film. However, in this method, the presence of the wall material of the discoloration microcapsules can easily cause the polyurethane film surface to become white and misty, and the discoloration effect can be poor due to the peeling of the discoloration microcapsule coating. Therefore, it needs to be improved. SUMMARY

[0004] The present application aims to provide a temperature discoloration car film and a preparation method thereof to solve the problems in the background art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: a temperature discoloration car film and a preparation method thereof, comprising the following steps:

[0006] Step 1:

[0007] S11: adding acetic acid dropwise to a 90% ethanol aqueous solution to adjust the pH to 4-4.2, then adding KH550, stirring for 1-2 h, adding vanadium dioxide powder, heating to 60-65 DEG C, and reacting for 3-5 h, then centrifuging and drying to obtain modified vanadium dioxide powder;

[0008] S12: adding gum arabic powder to deionized water, stirring to prepare an emulsifier solution, mixing the modified vanadium dioxide powder with the emulsifier solution, stirring and emulsifying at 60-65 DEG C water bath for 10-15 min at a stirring speed of 10000-12000 rpm to obtain a core material dispersion; mixing polytetrahydrofuran ether diol 2000 and toluene diisocyanate, and reacting at 60-70 DEG C for 2-3 h to obtain a shell material;

[0009] S13: The shell material is mixed with the core material dispersion liquid, a chain extender 1,4-butanediol is added, dibutyltin dilaurate is used as a catalyst, and the reaction is stirred at 60-70℃ for 1-2h to obtain a color-changing microcapsule;

[0010] Step 2:

[0011] S21: 1,1,1,3,5,5,5-heptamethyltrisiloxane, polymerization inhibitor phenothiazine, karstedt catalyst are dispersed in xylene, and a mixed solution of 3-allyloxy-1,2-propanediol in xylene is added dropwise, the dropwise time is controlled to be 1-2h, and the reaction temperature during dropwise is 100-110℃; after dropwise completion, continue to heat for 2-3h to obtain a silicone modified diol;

[0012] S22: In a nitrogen environment, trimellitic anhydride and toluene diisocyanate are mixed and dispersed in N-methyl pyrrolidone, stirred at 75-85℃ for 0.5h, and then heated to 115-125℃ and stirred for 1-2h to obtain a dicarboxylic acid imide compound;

[0013] S23: The dicarboxylic acid imide compound is mixed with the silicone modified diol, a monobutyl tin oxide catalyst is used, and the reaction is carried out at 150-160℃ for 2-3h to obtain a silicone modified imide polyester diol;

[0014] Step 3:

[0015] S31: The silicone modified imide polyester diol and polytetrahydrofuran ether diol 2000 are mixed to obtain a mixed diol; in a nitrogen environment, toluene diisocyanate is added to the mixed diol, heated to 60-70℃, and reacted for 3-4h; cooled to 40-50℃, add chain extender 1,4-butanediol and dibutyltin dilaurate, and react at 60-70℃ for 1-2h to obtain a polyurethane elastomer;

[0016] S32: The polyurethane elastomer, color-changing microcapsule, silane coupling agent, plasticizer, antioxidant, and ultraviolet light absorber are mixed at 60-80℃, melt extruded at 120-140℃, and blown into a film to obtain a temperature color-changing film.

[0017] Further, in S11, the mass ratio of the ethanol aqueous solution, KH550, and vanadium dioxide powder is 100:1:(2-4).

[0018] Further, in S12, an emulsifier solution with a mass fraction of 3-5% is added; in the core material dispersion liquid, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is (5-8):100; and in the shell material, the isocyanate group content is 27-32% by weight percentage.

[0019] Further, in S13, the chain extension coefficient is 0.88-0.93; the mass ratio of the shell material to the core material dispersion liquid is 1: (12-16).

[0020] Further, in S21, 1,1,1,3,5,5,5-heptamethyltrisiloxane and 3-allyloxy-1,2-propanediol are reacted at a molar ratio of 1:1.

[0021] Further, in S22, trimellitic anhydride and toluene diisocyanate are reacted at a molar ratio of 2:1.

[0022] Further, in S23, the dicarboxylic imide compound and the silicone-modified diol are mixed at a molar ratio of carboxyl to hydroxyl of 1: (1.2-1.5).

[0023] Further, in S31, the mass ratio of the silicone-modified imide polyester diol and the polytetrahydrofuran ether diol 2000 in the mixed diol is 1: (5-10).

[0024] Further, in S31, the amount of each component is 65-85 parts by weight of the mixed diol, 28-43 parts by weight of toluene diisocyanate, 5-8 parts by weight of the chain extender 1,4-butanediol, and 0.3-0.5 parts by weight of dibutyltin dilaurate.

[0025] Further, in S32, the amount of each component is 100-120 parts by weight of the polyurethane elastomer, 5-8 parts by weight of the color-changing microcapsule, 1-2 parts by weight of the silane coupling agent, 1-2 parts by weight of the plasticizer, 0.5-0.8 parts by weight of the antioxidant, and 0.5-0.8 parts by weight of the ultraviolet light absorber.

[0026] Compared with the prior art, the application has the following beneficial effects: the application selects vanadium dioxide as a thermochromic material, which has good near-infrared transmittance at low temperatures, can effectively improve the temperature in the vehicle, and after phase transition, reflects near-infrared radiation to block external heat from entering the vehicle, so that the temperature in the vehicle can be kept lower in hot summer. In the preparation of the vehicle film, vanadium dioxide is added to the polyurethane elastomer, melt-extruded, and blow-molded into a film to obtain the vehicle film. Since the vanadium dioxide powder is easy to agglomerate, the application first modifies it with KH550 and then wraps it with polyurethane to obtain the color-changing microcapsule. Compared with the vanadium dioxide powder, the color-changing microcapsule has better dispersibility, the shell material of the microcapsule is the same as the raw material of the polyurethane elastomer of the vehicle film, and the two have better compatibility after blending.

[0027] In the preparation of the car film base polyurethane elastomer, the present application uses 1,1,1,3,5,5,5-heptamethyltrisiloxane and 3-allyloxy-1,2-propanediol as raw materials, and obtains a silicone-modified diol through a silicon-hydrogen bond addition reaction; obtains a bis-carboxyl imide compound by reacting trimellitic anhydride and toluene diisocyanate; carries out esterification and polymerization of the bis-carboxyl imide compound and the silicone-modified diol to obtain a silicone-modified imide polyester diol; and mixes the silicone-modified imide polyester diol with polytetrahydrofuran ether diol, and reacts with toluene diisocyanate as a soft segment to obtain a polyurethane elastomer. Since the silicone-modified imide polyester diol contains a large number of imide rings and ester groups, the presence of these groups can form intermolecular hydrogen bonds and improve the intermolecular interaction, so that the prepared car film has greater tensile strength and elongation at break; at the same time, the strong intermolecular interaction also makes it difficult for the molecular chain segments to move, so the volume loss is reduced and the wear resistance is improved. In addition, the presence of the silicone-modified imide polyester diol introduces silicone into the side chain of the polyurethane molecule. Compared with the long-chain silicone group in the main chain, the short-chain silicone on the side chain is more likely to migrate and aggregate to the surface of the material, which can improve the hydrophobicity, water resistance and wear resistance of the car film without affecting the mechanical properties of the polyurethane elastomer. It should be noted that the amount of the silicone-modified imide polyester diol is not the more the better, when the amount is too high, the elongation at break of the material decreases and the toughness becomes poor, so the mass ratio of the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 is controlled to be 1: (5-10), and the prepared car film has better performance. The car film prepared by the present application has good quality, is beautiful and practical, can change color after heating, has uniform color distribution without color difference, and has good mechanical properties, wear resistance and surface self-cleaning performance. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] The materials used in the present application and their sources: vanadium dioxide powder from Hangzhou Jihewen New Material Co., Ltd., product number SS-V50; gum arabic powder from Aladdin Reagent (Shanghai) Co., Ltd.; polytetrahydrofuran ether diol 2000 from Jining Baiyi Chemical Co., Ltd.; silane coupling agent is vinyl triethoxysilane, plasticizer is di(2-ethylhexyl) phthalate, antioxidant is antioxidant 1010, and ultraviolet light absorber is UV-531, all from Aladdin Reagent (Shanghai) Co., Ltd.

[0030] Embodiment 1: A temperature-chromic car film and a preparation method thereof, comprising the following steps:

[0031] Step 1:

[0032] S11: Add acetic acid dropwise to an aqueous ethanol solution with a mass concentration of 90% to adjust the pH to 4.2, then add KH550, and after stirring for 1 h, add vanadium dioxide powder, warm to 60 DEG C, and react for 3 h, centrifuge, and dry to obtain modified vanadium dioxide powder; wherein the mass ratio of the aqueous ethanol solution, KH550, and vanadium dioxide powder is 100:1:2;

[0033] S12: Add gum arabic powder to deionized water, stir to obtain a 5% emulsifier solution, mix the modified vanadium dioxide powder with the emulsifier solution, and stir and emulsify under the condition of a 60 DEG C water bath for 10 min at a stirring speed of 10,000 rpm to obtain a core material dispersion; in the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is 5:100; mix polytetrahydrofuran ether diol 2000 and toluene diisocyanate, and react at 60 DEG C for 2 h to obtain a shell material; in the shell material, the isocyanate group content is 30% by weight percentage;

[0034] S13: Mix the shell material with the core material dispersion, add a chain extender 1,4-butanediol with a chain extension coefficient of 0.91, and use dibutyltin dilaurate as a catalyst to stir and react at 60 DEG C for 1 h to obtain a color-changing microcapsule; wherein the mass ratio of the shell material to the core material dispersion is 1:12;

[0035] Step 2:

[0036] S21: Disperse 1,1,1,3,5,5,5-heptamethyltrisiloxane, a polymerization inhibitor phenothiazine, and karstedt catalyst in xylene, add a xylene mixed solution containing 3-allyloxy-1,2-propanediol dropwise, control the dropwise addition time to be 1 h, and control the reaction temperature during the dropwise addition to be 100 DEG C; after the dropwise addition is completed, continue to warm for 2 h to obtain a silicone-modified diol; wherein the molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to 3-allyloxy-1,2-propanediol is 1:1;

[0037] S22: Mix and disperse trimellitic anhydride and toluene diisocyanate in N-methyl pyrrolidone at a molar ratio of 2:1 under a nitrogen environment, stir at 75 DEG C for 0.5 h, warm to 115 DEG C, and stir for 1-2 h to obtain a dicarboxylic imide compound;

[0038] S23: Mix the dicarboxylic imide compound with the silicone-modified diol at a carboxyl to hydroxyl molar ratio of 1:1.2, use monobutyl tin oxide as a catalyst, and react at 150 DEG C for 2 h to obtain a silicone-modified imide polyester diol;

[0039] Step 3:

[0040] S31: Mix the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 in a mass ratio of 1:10 to obtain a mixed diol; under a nitrogen environment, add 36 kg of toluene diisocyanate to 75 kg of the mixed diol, heat to 60°C, and react for 3 h; cool to 40°C, add 5 kg of chain extender 1,4-butanediol and 0.5 kg of dibutyltin dilaurate, and react at 60°C for 1 h to obtain a polyurethane elastomer;

[0041] S32: Mix 100 kg of the polyurethane elastomer, 5 kg of color-changing microcapsules, 1 kg of a silane coupling agent, 1 kg of a plasticizer, 0.5 kg of an antioxidant, and 0.5 kg of an ultraviolet light absorber at 60°C, melt-extrude at 120°C, and blow-mold into a film to obtain a temperature-changing car film.

[0042] Example 2: A temperature-changing car film and a preparation method thereof, comprising the following steps:

[0043] Step 1:

[0044] S11: Add acetic acid dropwise to an aqueous ethanol solution with a mass concentration of 90% to adjust the pH to 4.2, then add KH550, stir for 1.5 h, and then add vanadium dioxide powder. Heat to 65°C and react for 4 h. Centrifuge and dry to obtain modified vanadium dioxide powder. The mass ratio of the aqueous ethanol solution, KH550, and vanadium dioxide powder is 100:1:2;

[0045] S12: Add gum arabic powder to deionized water and stir to prepare a 5% emulsifier solution. Mix the modified vanadium dioxide powder with the emulsifier solution and stir and emulsify at 65°C for 15 min under water bath conditions at a stirring speed of 11,000 rpm to obtain a core material dispersion. In the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is 5:100. Mix polytetrahydrofuran ether diol 2000 and toluene diisocyanate and react at 65°C for 2.5 h to obtain a shell material. In the shell material, the isocyanate group content is 30% by weight percentage;

[0046] S13: Mix the shell material with the core material dispersion, add chain extender 1,4-butanediol with a chain extension coefficient of 0.91, and add dibutyltin dilaurate as a catalyst. Stir and react at 65°C for 1.5 h to obtain color-changing microcapsules. In the color-changing microcapsules, the mass ratio of the shell material to the core material dispersion is 1:12;

[0047] Step 2:

[0048] S21: 1,1,1,3,5,5,5-heptamethyltrisiloxane, polymerization inhibitor phenothiazine, karstedt catalyst were dispersed in xylene, a mixture solution containing 3-allyloxy-1,2-propanediol in xylene was added dropwise, the dropwise time was controlled for 1.5 h, and the reaction temperature was 105 DEG C during the dropwise period; after the dropwise addition was completed, the reaction was continued for 2.5 h, to obtain a silicone-modified diol; wherein the molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to 3-allyloxy-1,2-propanediol was 1:1;

[0049] S22: under nitrogen environment, trimellitic anhydride and toluene diisocyanate were mixed and dispersed in N-methyl pyrrolidone at a molar ratio of 2:1, stirred at 80 DEG C for 0.5 h, and then heated to 120 DEG C and stirred for 1.5 h to obtain a dicarboxylic acid imide compound;

[0050] S23: the dicarboxylic acid imide compound was mixed with the silicone-modified diol at a molar ratio of carboxyl to hydroxyl of 1:1.2, and a single butyl tin oxide was used as a catalyst to react at 155 DEG C for 2.5 h to obtain a silicone-modified imide polyester diol;

[0051] Step 3:

[0052] S31: the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 were mixed at a mass ratio of 1:8 to obtain a mixed diol; under nitrogen environment, 36 kg of toluene diisocyanate was added to 75 kg of the mixed diol, heated to 65 DEG C, and reacted for 3.5 h; cooled to 45 DEG C, and then 5 kg of chain extender 1,4-butanediol and 0.5 kg of dibutyltin dilaurate were added, and reacted at 65 DEG C for 1.5 h to obtain a polyurethane elastomer;

[0053] S32: 100 kg of the polyurethane elastomer, 5 kg of color-changing microcapsules, 1 kg of silane coupling agent, 1 kg of plasticizer, 0.5 kg of antioxidant, and 0.5 kg of ultraviolet light absorber were mixed at 70 DEG C, and then melt-extruded at 130 DEG C to obtain a temperature color-changing car film.

[0054] Example 3: a temperature color-changing car film and a preparation method thereof, comprising the following steps:

[0055] Step 1:

[0056] S11: to an ethanol aqueous solution with a mass concentration of 90%, acetic acid was added dropwise to adjust the pH to 4.2, then KH550 was added, and after stirring for 2 h, vanadium dioxide powder was added, heated to 65 DEG C, and reacted for 5 h, and then centrifuged and dried to obtain modified vanadium dioxide powder; wherein the mass ratio of the ethanol aqueous solution, KH550, and vanadium dioxide powder was 100:1:2;

[0057] S12: Add gum arabic powder in deionized water, stir to prepare a 5% emulsifier solution, mix the modified vanadium dioxide powder with the emulsifier solution, and stir and emulsify under the condition of a 60°C water bath for 10 min at a stirring speed of 12000 rpm to obtain a core material dispersion; in the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is 5:100; mix polytetrahydrofuran ether diol 2000 and toluene diisocyanate, and react at 70°C for 3 h to obtain a shell material; in the shell material, the isocyanate group content is 30% by weight percentage;

[0058] S13: Mix the shell material with the core material dispersion, add a chain extender 1,4-butanediol with a chain extension coefficient of 0.91, and use dibutyltin dilaurate as a catalyst to stir and react at 70°C for 2 h to obtain color-changing microcapsules; in the process, the mass ratio of the shell material to the core material dispersion is 1:12;

[0059] Step 2:

[0060] S21: Disperse 1,1,1,3,5,5,5-heptamethyltrisiloxane, a polymerization inhibitor phenothiazine, and karstedt catalyst in xylene, drop 3-allyloxy-1,2-propanediol-containing xylene mixed solution, control the drop time to be 2 h, and the reaction temperature during the drop is 110°C; after the drop is completed, continue to heat for 3 h to obtain a silicone-modified diol; in the process, the molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to 3-allyloxy-1,2-propanediol is 1:1;

[0061] S22: Mix and disperse trimellitic anhydride and toluene diisocyanate in N-methyl pyrrolidone at a molar ratio of 2:1 under a nitrogen environment, stir at 85°C for 0.5 h, and then heat to 125°C and stir for 2 h to obtain a dicarboxylic imide compound;

[0062] S23: Mix the dicarboxylic imide compound with the silicone-modified diol at a molar ratio of carboxyl to hydroxyl of 1:1.2, and use monobutyl tin oxide as a catalyst to react at 160°C for 3 h to obtain a silicone-modified imide polyester diol;

[0063] Step 3:

[0064] S31: Mix the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 at a mass ratio of 1:7 to obtain a mixed diol; under a nitrogen environment, add 36 kg of toluene diisocyanate to 75 kg of the mixed diol, heat to 70°C, and react for 4 h; cool to 50°C, add 5 kg of chain extender 1,4-butanediol and 0.5 kg of dibutyltin dilaurate, and react at 70°C for 2 h to obtain a polyurethane elastomer;

[0065] S32: 100 kg of polyurethane elastomer, 5 kg of color-changing microcapsules, 1 kg of silane coupling agent, 1 kg of plasticizer, 0.5 kg of antioxidant, and 0.5 kg of ultraviolet light absorber are mixed at 80°C, melt-extruded at 140°C, and blown into a film to obtain a temperature-changing car film.

[0066] Example 4: A temperature-changing car film and a method for preparing the same, comprising the following steps:

[0067] Step 1:

[0068] S11: Add acetic acid to an aqueous ethanol solution with a mass concentration of 90% to adjust the pH to 4.2, then add KH550, stir for 2 h, and then add vanadium dioxide powder. Heat to 65°C and react for 5 h. Centrifuge and dry to obtain modified vanadium dioxide powder. The mass ratio of the aqueous ethanol solution, KH550, and vanadium dioxide powder is 100:1:2;

[0069] S12: Add gum arabic powder to deionized water and stir to prepare a 5% emulsifier solution. Mix the modified vanadium dioxide powder with the emulsifier solution and stir and emulsify in a 65°C water bath for 15 min at a stirring speed of 12000 rpm to obtain a core material dispersion. In the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is 5:100. Mix polytetrahydrofuran ether diol 2000 and toluene diisocyanate and react at 70°C for 3 h to obtain a shell material. In the shell material, the isocyanate group content is 30% by weight percentage;

[0070] S13: Mix the shell material with the core material dispersion, add a chain extender 1,4-butanediol with a chain extension coefficient of 0.91, and use dibutyltin dilaurate as a catalyst to stir and react at 70°C for 2 h to obtain color-changing microcapsules. The mass ratio of the shell material to the core material dispersion is 1:12;

[0071] Step 2:

[0072] S21: Disperse 1,1,1,3,5,5,5-heptamethyltrisiloxane, a polymerization inhibitor phenothiazine, and karstedt catalyst in xylene, and dropwise add a xylene mixed solution containing 3-allyloxy-1,2-propanediol. Control the dropwise addition time to be 2 h, and the reaction temperature during dropwise addition is 110°C. After dropwise addition is complete, continue to heat for 3 h to obtain a silicone-modified diol. The molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to 3-allyloxy-1,2-propanediol is 1:1;

[0073] S22: under nitrogen environment, trimellitic anhydride and toluene diisocyanate were mixed and dispersed in N-methyl pyrrolidone at a molar ratio of 2:1, stirred at 85℃ for 0.5h, and then heated to 125℃ and stirred for 2h to obtain a dicarboxylic imide compound;

[0074] S23: the dicarboxylic imide compound was mixed with the silicone-modified diol at a molar ratio of carboxyl to hydroxyl of 1:1.2, and a single butyl tin oxide was used as a catalyst to react at 160℃ for 3h to obtain a silicone-modified imide polyester diol;

[0075] Step 3:

[0076] S31: the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 were mixed at a mass ratio of 1:5 to obtain a mixed diol; under nitrogen environment, 36kg of toluene diisocyanate was added to 75kg of the mixed diol, heated to 70℃, and reacted for 4h; cooled to 50℃, and 5kg of chain extender 1,4-butanediol and 0.5kg of dibutyltin dilaurate were added, and reacted at 70℃ for 2h to obtain a polyurethane elastomer;

[0077] S32: 100kg of the polyurethane elastomer, 5kg of color-changing microcapsules, 1kg of silane coupling agent, 1kg of plasticizer, 0.5kg of antioxidant, and 0.5kg of ultraviolet light absorber were mixed at 80℃, and then melt-extruded at 140℃ to obtain a temperature-changing film.

[0078] Comparative Example 1: vanadium dioxide powder was directly blended with the polyurethane elastomer, and the remaining parameters were the same as those in Example 1.

[0079] Step 1:

[0080] S11: 1,1,1,3,5,5,5-heptamethyltrisiloxane, a polymerization inhibitor phenothiazine, and karstedt catalyst were dispersed in xylene, and a xylene mixed solution containing 3-allyloxy-1,2-propanediol was added dropwise, the dropwise addition time was controlled to be 1h, and the reaction temperature during dropwise addition was 100℃; after the dropwise addition was completed, the reaction was continued for 2h to obtain a silicone-modified diol; wherein the molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to 3-allyloxy-1,2-propanediol was 1:1;

[0081] S12: under nitrogen environment, trimellitic anhydride and toluene diisocyanate were mixed and dispersed in N-methyl pyrrolidone at a molar ratio of 2:1, stirred at 75℃ for 0.5h, and then heated to 115℃ and stirred for 1~2h to obtain a dicarboxylic imide compound;

[0082] S13: The dicarboxylic acid imide compound and the silicone-modified diol were mixed at a molar ratio of carboxyl to hydroxyl of 1:1.2, a single butyl tin oxide was used as a catalyst, and the reaction was carried out at 150°C for 2h to obtain a silicone-modified imide polyester diol;

[0083] Step 2:

[0084] S21: The silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 were mixed at a mass ratio of 1:10 to obtain a mixed diol; under a nitrogen environment, 36kg of toluene diisocyanate was added to 75kg of the mixed diol, and the temperature was raised to 60°C for 3h; the temperature was lowered to 40°C, 5kg of chain extender 1,4-butanediol and 0.5kg of dibutyltin dilaurate were added, and the reaction was carried out at 60°C for 1h to obtain a polyurethane elastomer;

[0085] S22: 100kg of the polyurethane elastomer, 5kg of vanadium dioxide powder, 1kg of silane coupling agent, 1kg of plasticizer, 0.5kg of antioxidant, and 0.5kg of ultraviolet light absorber were mixed at 60°C, and then melt extruded at 120°C to form a film by blow molding to obtain a temperature color-changing film.

[0086] Comparative Example 2: No silicone-modified imide polyester diol was added, and the other parameters were the same as those in Example 2.

[0087] Step 1:

[0088] S11: The pH of an ethanol aqueous solution with a mass concentration of 90% was adjusted to 4.2 by adding acetic acid, then KH550 was added, and after stirring for 1.5h, vanadium dioxide powder was added, the temperature was raised to 65°C, and the reaction was carried out for 4h; centrifugation and drying were carried out to obtain modified vanadium dioxide powder; the mass ratio of the ethanol aqueous solution, KH550, and vanadium dioxide powder was 100:1:2;

[0089] S12: In deionized water, gum arabic powder was added and stirred to prepare an emulsifier solution with a mass fraction of 5%; the modified vanadium dioxide powder was mixed with the emulsifier solution, and under the condition of a 65°C water bath, the mixture was stirred and emulsified for 15min at a stirring speed of 11000rpm to obtain a core material dispersion; in the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution was 5:100; polytetrahydrofuran ether diol 2000 and toluene diisocyanate were mixed, and the reaction was carried out at 65°C for 2.5h to obtain a shell material; in the shell material, the isocyanate group content was 30% by weight percentage;

[0090] S13: The shell material was mixed with the core material dispersion, 1,4-butanediol was added as a chain extender with a chain extension coefficient of 0.91, and dibutyltin dilaurate was used as a catalyst, and the reaction was carried out at 65°C for 1.5h to obtain color-changing microcapsules; the mass ratio of the shell material to the core material dispersion was 1:12;

[0091] Step 2:

[0092] S21: 75 kg of polytetrahydrofuran ether glycol 2000 was added with 36 kg of toluene diisocyanate under a nitrogen environment, and the temperature was raised to 65 DEG C, and reacted for 3.5 h; the temperature was lowered to 45 DEG C, 5 kg of chain extender 1,4-butanediol and 0.5 kg of dibutyltin dilaurate were added, and reacted for 1.5 h at 65 DEG C to obtain a polyurethane elastomer;

[0093] S22: 100 kg of polyurethane elastomer, 5 kg of color-changing microcapsule, 1 kg of silane coupling agent, 1 kg of plasticizer, 0.5 kg of antioxidant, and 0.5 kg of ultraviolet light absorber were mixed at 70 DEG C, and melt-extruded at 130 DEG C to form a film by blow molding to obtain a temperature-changing film.

[0094] Comparative Example 3: The amount of silicone-modified imide polyester diol was increased, and the other parameters were the same as those in Example 3.

[0095] Step 1:

[0096] S11: The pH of an aqueous ethanol solution with a mass concentration of 90% was adjusted to 4.2 by adding acetic acid, then KH550 was added, and after stirring for 2 h, vanadium dioxide powder was added, and the temperature was raised to 65 DEG C and reacted for 5 h, and then centrifuged and dried to obtain modified vanadium dioxide powder; wherein the mass ratio of the aqueous ethanol solution, KH550, and vanadium dioxide powder was 100:1:2;

[0097] S12: In deionized water, gum arabic powder was added and stirred to prepare a 5% emulsifier solution, and the modified vanadium dioxide powder was mixed with the emulsifier solution and stirred and emulsified at 60 DEG C for 10 min under water bath conditions at a stirring speed of 12000 rpm to obtain a core material dispersion; in the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution was 5:100; polytetrahydrofuran ether glycol 2000 and toluene diisocyanate were mixed and reacted at 70 DEG C for 3 h to obtain a shell material; in the shell material, the isocyanate group content was 30% by weight percentage;

[0098] S13: The shell material was mixed with the core material dispersion, and chain extender 1,4-butanediol was added with a chain extension coefficient of 0.91, and dibutyltin dilaurate was used as a catalyst to stir and react at 70 DEG C for 2 h to obtain a color-changing microcapsule; wherein the mass ratio of the shell material to the core material dispersion was 1:12;

[0099] Step 2:

[0100] S21: 1,1,1,3,5,5,5-heptamethyltrisiloxane, a polymerization inhibitor phenothiazine, and karstedt catalyst dispersed in xylene, drop 3-allyloxy-1,2-propanediol-containing xylene mixed solution, control the drop time for 2h, the reaction temperature during drop is 110℃; after drop is completed, continue to keep warm for 3h, to obtain silicone modified diol; wherein, the molar ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane and 3-allyloxy-1,2-propanediol is 1:1;

[0101] S22: under nitrogen environment, trimellitic anhydride and toluene diisocyanate are mixed and dispersed in N-methyl pyrrolidone at a molar ratio of 2:1, stirred at 85℃ for 0.5h, and then heated to 125℃ and stirred for 2h to obtain a dicarboxylic acid imide compound;

[0102] S23: the dicarboxylic acid imide compound is mixed with the silicone modified diol at a molar ratio of carboxyl to hydroxyl of 1:1.2, and a single butyl tin oxide is used as a catalyst to react at 160℃ for 3h to obtain a silicone modified imide polyester diol;

[0103] Step 3:

[0104] S31: the silicone modified imide polyester diol and polytetrahydrofuran ether diol 2000 are mixed at a mass ratio of 1:3 to obtain a mixed diol; under nitrogen environment, 36kg of toluene diisocyanate is added to 75kg of the mixed diol, heated to 70℃, and reacted for 4h; cooled to 50℃, 5kg of chain extender 1,4-butanediol and 0.5kg of dibutyltin dilaurate are added, and reacted at 70℃ for 2h to obtain a polyurethane elastomer;

[0105] S32: 100kg of the polyurethane elastomer, 5kg of color-changing microcapsules, 1kg of silane coupling agent, 1kg of plasticizer, 0.5kg of antioxidant, and 0.5kg of ultraviolet light absorber are mixed at 80℃, and then melt extruded at 140℃ to obtain a temperature color-changing film.

[0106] Experiment: the temperature color-changing films in examples 1-4 and comparative examples 1-3 are tested for performance, wherein:

[0107] Color change performance: the sample is placed in an oven, heated from room temperature to 50℃, the heating time is 30min, and the sample is taken out after keeping warm for 60min, and the color change effect of the sample is observed.

[0108] Mechanical properties: the tensile strength and elongation at break are tested by a tensile testing machine according to standard GB / T 528-2009; wherein, the sample gauge length is 10mm, and the tensile rate is 100mm / min.

[0109] Wear resistance: the wear resistance of the sample was characterized by the rotating roller abrasion machine method according to the standard GB / T 9867-2008, and the density A (g / cm3) of the measured sample, the three-time average mass loss AV (g) of the test piece, the three-time average wear AW (g) of the standard glue were measured respectively, and the volume loss value of the sample Δ (mm 3 ) was calculated according to the following formula:

[0110] Δ= (AV x 200) / (AW x A).

[0111] Hydrophobic property: the contact angle between the sample and water surface was tested by a contact angle analyzer.

[0112]

[0113] Conclusion: the data of examples 1-4 show that the car film prepared by the application can change color after heating, the color distribution is uniform without color difference, and the car film has good mechanical properties, wear resistance and surface self-cleaning property. The data of example 1 and comparative example 1 show that compared with directly adding modified vanadium dioxide powder, the color-changing microcapsule has better dispersibility in the car film; the data of example 2 and comparative example 2 show that the car film in example 2 has better mechanical properties, better wear resistance and certain self-cleaning function; the data of example 3 and comparative example 3 show that after increasing the amount of organosilicon modified imide polyester dihydric alcohol, the elongation at break of the car film material is obviously reduced.

[0114] Finally, it should be pointed out that: the above only for the preferred embodiments of the application, and not for limiting the application, although the application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing a thermochromic vehicle film, characterized by: Comprising the following steps: Step 1: S11: add acetic acid to the ethanol aqueous solution dropwise to adjust the pH to 4~4.2, add KH550 and stir for 1~2h, add vanadium dioxide powder, warm up to 60~65℃, react for 3~5h, centrifuge and dry to obtain modified vanadium dioxide powder; S12: add gum arabic powder to deionized water, stir to prepare an emulsifier solution, mix the modified vanadium dioxide powder with the emulsifier solution, stir and emulsify under the condition of a 60~65℃ water bath for 10~15min, the stirring speed is 10000~12000rpm, to obtain a core material dispersion; mix polytetrahydrofuran ether diol 2000 and toluene diisocyanate, react at 60~70℃ for 2~3h to obtain a shell material; S13: mix the shell material with the core material dispersion, add chain extender 1,4-butanediol, and dibutyltin dilaurate as catalyst, stir and react at 60~70℃ for 1~2h to obtain color-changing microcapsules; Step 2: S21: disperse 1,1,1,3,5,5,5-heptamethyltrisiloxane, polymerization inhibitor phenothiazine, and karstedt catalyst in xylene, add dropwise a mixed solution of 3-allyloxy-1,2-propanediol in xylene, control the dropwise addition time to be 1~2h, the reaction temperature during dropwise addition is 100~110℃; after dropwise addition is completed, continue to react for 2~3h to obtain silicone-modified diol; S22: under a nitrogen environment, mix and disperse trimellitic anhydride and toluene diisocyanate in N-methyl pyrrolidone, stir at 75~85℃ for 0.5h, warm up to 115~125℃ and stir for 1~2h to obtain a bis-carboxylic imide compound; S23: mix the bis-carboxylic imide compound with the silicone-modified diol, use monobutyl tin oxide as catalyst, and react at 150~160℃ for 2~3h to obtain silicone-modified imide polyester diol; Step 3: S31: mix the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 to obtain a mixed diol; under a nitrogen environment, add toluene diisocyanate to the mixed diol, warm up to 60~70℃, and react for 3~4h; cool down to 40~50℃, add chain extender 1,4-butanediol and dibutyltin dilaurate, and react at 60~70℃ for 1~2h to obtain a polyurethane elastomer; S32: mix the polyurethane elastomer, color-changing microcapsules, silane coupling agent, plasticizer, antioxidant, and ultraviolet light absorber at 60~80℃, melt extrude at 120~140℃, and blow mold into a film to obtain a temperature color-changing film.

2. The method of claim 1, wherein the temperature changing film is prepared by the steps of: (a) preparing a mixture of a thermochromic material and a polymer; (b) coating the mixture on a substrate; and (c) drying the mixture. In S11, the mass ratio of the ethanol aqueous solution, KH550, and vanadium dioxide powder is 100:1:(2~4).

3. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S12, the mass concentration of the emulsifier solution is 3~5%; in the core material dispersion, the mass ratio of the modified vanadium dioxide powder to the emulsifier solution is (5~8):100; in the shell material, the isocyanate group content is 27~32% by weight percentage.

4. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S13, the chain extension coefficient is 0.88~0.93; the mass ratio of the shell material to the core material dispersion is 1:(12~16).

5. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S21, 1,1,1,3,5,5,5-heptamethyltrisiloxane is reacted with 3-allyloxy-1,2-propanediol at a molar ratio of 1:

1.

6. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S22, trimellitic anhydride is reacted with toluene diisocyanate at a molar ratio of 2:

1.

7. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S23, the dicarboxylic imide compound is mixed with the silicone-modified diol at a molar ratio of carboxyl to hydroxyl of 1:(1.2-1.5).

8. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S31, the amount of each component is 65-85 parts by weight of mixed diol, 28-43 parts by weight of toluene diisocyanate, 5-8 parts by weight of chain extender 1,4-butanediol, and 0.3-0.5 parts by weight of dibutyltin dilaurate; wherein the mass ratio of the silicone-modified imide polyester diol and polytetrahydrofuran ether diol 2000 in the mixed diol is 1:(5-10).

9. The method for preparing a temperature-changing car film according to claim 1, characterized in that: In S32, the amount of each component is 100-120 parts by weight of polyurethane elastomer, 5-8 parts by weight of color-changing microcapsules, 1-2 parts by weight of silane coupling agent, 1-2 parts by weight of plasticizer, 0.5-0.8 parts by weight of antioxidant, and 0.5-0.8 parts by weight of ultraviolet light absorber.

10. The temperature-changing vehicle film prepared according to the preparation method of any one of claims 1-9.

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