CN114989714B

CN114989714B - Preparation method and construction method of pavement low-temperature dynamic early warning coating material

Info

Publication number: CN114989714B
Application number: CN202210785944.9A
Authority: CN
Inventors: 徐慧宁; 王浩达; 冀卫东; 韦赟豪; 张子寒
Original assignee: Daqing Chenke Transportation Technology Co ltd; Harbin Institute of Technology
Current assignee: Daqing Chenke Transportation Technology Co ltd; Harbin Institute of Technology
Priority date: 2022-07-04
Filing date: 2022-07-04
Publication date: 2023-04-21
Anticipated expiration: 2042-07-04
Also published as: CN114989714A

Abstract

A preparation method and a construction method of a pavement low-temperature dynamic early warning coating material belong to the field of road traffic safety. The invention aims to solve the problems that the existing prepared low-temperature color-changing microcapsule has low coating rate, light color changing color and low color changing speed, which cause poor low-temperature warning effect, and the low-temperature color-changing early warning material is not applied to a low-temperature color-changing coating for a road. The method comprises the following steps: 1. preparing a low-temperature color-changing compound; 2. preparing low-temperature color-changing microcapsule powder; 3. and preparing the low-temperature early warning color-changing coating. The invention relates to a preparation method and a construction method of a pavement low-temperature dynamic early warning coating material.

Description

Preparation method and construction method of pavement low-temperature dynamic early warning coating material

Technical Field

The invention belongs to the field of road traffic safety.

Background

The road surface temperature is lower in the early winter to early spring, when the temperature is lower than 0 ℃, road surface moisture is easy to condense into dark ice, the anti-skid capability of the road surface is rapidly reduced, and the ice film is thin and transparent and is not easy to be perceived by a driver, so that the driving safety of the driver is greatly threatened. The existing road traffic coating has single function and fixed mode, can not sense the special road surface conditions such as low temperature, ice slip and the like, and is difficult to realize automatic early warning and adjusting warning grades for the road surface conditions. Based on the related investigation of traffic light colors, the color change is the most intuitive early warning mode, not only can psychologically mobilize the attention of drivers and passengers, but also can physiologically influence the skill response time of the drivers, so that the drivers and the passengers can consciously or instinctively pay attention to unsafe factors existing around and correctly and rapidly respond, and the traffic accident prevention method is an effective means for reducing and avoiding traffic accidents. Therefore, in order to ensure safe driving of a driver, improve the driving safety of a road surface in winter, realize low-temperature dynamic early warning of the road surface, it is necessary to develop road surface coating materials and technologies with low-temperature color change function, and provide technical reserves for safe operation of road traffic in winter.

The temperature-indicating early warning coating is an effective means of early warning the temperature of the environment or object. At present, the early warning coating is widely applied in industry, but limited by the use scene, the color-changing temperature of the temperature indicating coating material is higher, and the research in the low-temperature indicating field is less. The existing low-temperature color-changing early-warning material has low coating rate of low-temperature color-changing microcapsules, poor low-temperature warning effect caused by light color changing and low color changing speed, and the low-temperature color-changing early-warning material is not applied to a low-temperature color-changing coating for a road. Therefore, in order to overcome the defects in the prior art, it is necessary to provide a pavement low-temperature dynamic early warning coating material and a construction method.

Disclosure of Invention

The invention aims to solve the problems that the existing prepared low-temperature color-changing microcapsule has low coating rate, light color changing color and low color changing speed, which cause poor low-temperature warning effect, and the low-temperature color-changing early warning material is not applied to a low-temperature color-changing coating for a road, and further provides a preparation method and a construction method of the road surface low-temperature dynamic early warning coating material.

The preparation method of the pavement low-temperature dynamic early warning coating material comprises the following steps:

1. preparing a low-temperature color-changing compound:

adding a color developing agent into an organic solvent at a speed of 0.5 g/min-4 g/min under the conditions that the stirring rotation speed is 500 rpm-700 rpm and the temperature is 70-80 ℃ to dissolve, adding a leuco agent at a speed of 0.5 g/min-4 g/min to dissolve, and naturally cooling to room temperature to obtain a low-temperature color-changing compound;

the mass ratio of the color developing agent to the leuco agent is (1-6): 1; the mass ratio of the leuco agent to the organic solvent is 1 (20-60);

2. preparing low-temperature color-changing microcapsule powder:

(1) mixing the low-temperature color-changing compound and a sodium salt solution of the styrene maleic anhydride copolymer, then adjusting the pH to 5-6, and dispersing and emulsifying to obtain reversible thermochromic emulsion;

the mass ratio of the low-temperature color-changing compound to the sodium styrene maleic anhydride copolymer in the sodium styrene maleic anhydride copolymer solution is 1 (0.1-0.2);

(2) dropwise adding the wall material prepolymer solution into the reversible thermochromic emulsion at the speed of 1-1.2 mL/min under the conditions that the temperature is 45-55 ℃ and the stirring rotation speed is 300-600 rpm, then adjusting the pH value to 5-6, increasing the temperature from 45-55 ℃ to 75-85 ℃ at the temperature rising speed of 0.2-0.4 ℃/min, preserving heat for 1.5-3 h under the conditions that the temperature is 75-85 ℃, and finally washing and drying to obtain low-temperature thermochromic microcapsule powder;

the volume ratio of the wall material prepolymer solution to the reversible thermochromic emulsion is 1 (0.1-0.15);

3. preparing a low-temperature early warning color-changing coating:

adding low-temperature color-changing microcapsule powder into the adhesive containing the film-forming auxiliary agent under the condition of the rotating speed of 200 rpm-400 rpm, and stirring for 15-30 min to obtain a pavement low-temperature dynamic early warning coating material;

the mass ratio of the adhesive containing the film forming additive to the low-temperature color-changing microcapsule powder is 1 (0.15-0.3).

The construction method of the pavement low-temperature dynamic early warning coating material comprises the following steps: coating a bonding layer on the clean road surface, paving a road surface low-temperature dynamic early warning coating material on the road surface coated with the bonding layer, and spreading glass beads, wherein the total thickness of the bonding layer, the road surface low-temperature dynamic early warning coating material and the glass beads is 2-3 mm; the glass beads account for 5-10% of the total mass of the bonding layer, the pavement low-temperature dynamic early warning coating material and the glass beads; the bonding layer is obtained by coating acrylic emulsion; the diameter of the glass beads is 0.2 mm-0.8 mm.

The beneficial effects of the invention are as follows:

according to the requirements of low-temperature dynamic early warning of a road pavement in winter, preparing a low-temperature reversible thermochromic compound taking a freezing point as a color-changing temperature based on the regulation and control effect of a solvent on the color-changing temperature, and determining the addition sequence of a color-developing agent and a color-changing agent in the low-temperature thermochromic compound by taking the color-changing temperature and the color-changing color difference as evaluation indexes through a differential scanning calorimetric test; on the basis, dynamic low-temperature color-changing microcapsule powder with good wrapping effect and yield is prepared by changing an emulsifier material by utilizing the determined composition proportion of the low-temperature color-changing compound; finally, the color-changing microcapsule powder and the adhesive are combined to prepare a coating, the coating is paved on the road surface through a film forming technology, and the color-changing effect, the road performance and the durability of the low-temperature color-changing coating are verified through an outdoor weather-proof test, an abrasion test, a water-proof test, a stain-resistant test and an anti-skid test. The invention solves the problems of low coating rate, light color and slow color change speed of the low-temperature warning effect of the low-temperature color-changing microcapsule prepared in the prior art, and prepares low-temperature color-changing microcapsule powder with deep color change and fast color change speed; the prepared road surface low-temperature dynamic early warning coating material can dynamically change the road surface color, improve the attention of a driver, furthest reduce the occurrence of traffic accidents, reduce economic loss, and can be used on the road surface for a long time, thereby realizing the road safety early warning intellectualization and providing guarantee for the road traffic safety in ice and snow weather.

Drawings

FIG. 1 is a physical diagram of a low-temperature color-changing compound, a is the low-temperature color-changing compound prepared in the first step of the example, and b is the low-temperature color-changing compound prepared in the first step of the comparative experiment;

fig. 2 is a phase change process diagram of different systems, (a) DA/CVL, (b) DA/BPA, (c) CVL/BPA/DA,1 DA,2 DA/cvl=10:1, 3 DA/cvl=20:1, 4 DA/cvl=30:1, 5 DA/bpa=20:1, 6 DA/bpa=20:2, 7 DA/bpa=20:3, 8 CVL/BPA/da=1:1:20, 9 CVL/BPA/da=1:2:20, 10 CVL/BPA/da=1:3:20;

FIG. 3 is a graph showing the change in enthalpy of phase transition of different systems, (a) DA/CVL (b) DA/BPA, and (c) CVL/BPA/DA;

FIG. 4 is an optical microscope image of the low temperature color-changing microcapsule powder prepared in the first step of the example, with a scale of 1:200;

FIG. 5 is an optical microscope picture of the low temperature color-changing microcapsule powder prepared in the second step of the comparative experiment, with a scale of 1:200;

FIG. 6 is a graph showing the total color difference and the temperature change of the low-temperature color-changing microcapsule powder prepared in the first step of the example, wherein 1 is the process of the multiple color of the total color difference of the low-temperature reversible color-changing microcapsule powder along with the decrease of the temperature, and 2 is the process of the decolorization of the total color difference of the frozen reversible color-changing microcapsule powder along with the increase of the temperature;

FIG. 7 is a graph showing the total color difference of an experimental part coated with the low-temperature dynamic early warning coating material of the road surface according to the embodiment;

FIG. 8 is a graph comparing total color difference of an experimental piece coated with a pavement low-temperature dynamic early warning coating material of the embodiment with abrasion time;

FIG. 9 is a diagram of a water resistance test object of an experimental part coated with a pavement low-temperature dynamic early warning coating material of the embodiment, (a) before soaking, and (b) after soaking for 24 hours;

FIG. 10 is a graph showing the comparative effect of color change of an experimental part coated with the low-temperature dynamic early warning coating material for a road surface at-10 ℃ before and after soaking, wherein 1 is a road sample, 2 is a road marking, 3 is a color-changing coating, (a) before soaking in gasoline, and (b) after soaking in gasoline for 1 h;

fig. 11 is a graph showing the comparison of the swing values, a is a small road sample, b is an experimental piece with the surface coated with the marking material, and c is an experimental piece coated with the low-temperature dynamic early warning coating material of the road surface of the embodiment.

Detailed Description

The first embodiment is as follows: the preparation method of the pavement low-temperature dynamic early warning coating material comprises the following steps:

1. preparing a low-temperature color-changing compound:

2. preparing low-temperature color-changing microcapsule powder:

3. preparing a low-temperature early warning color-changing coating:

The specific embodiment provides that the color-changing temperature and the color-changing color difference are used as evaluation indexes, and the addition sequence of the color-developing and color-changing agent in the low-temperature color-changing compound is determined through a differential scanning calorimetric test; the low-temperature color-changing microcapsule powder is prepared on the basis, the good wrapping effect of the microcapsule on the color-changing compound is achieved by changing the emulsifier material, and finally the road low-temperature dynamic warning coating with good performance is prepared by combining the adhesive material.

The beneficial effects of this embodiment are:

according to the requirements of low-temperature dynamic early warning of a road pavement in winter, preparing a low-temperature reversible thermochromic compound taking a freezing point as a color-changing temperature based on the regulation and control effect of a solvent on the color-changing temperature, and determining the addition sequence of a color-developing agent and a color-changing agent in the low-temperature thermochromic compound by taking the color-changing temperature and the color-changing color difference as evaluation indexes through a differential scanning calorimetric test; on the basis, dynamic low-temperature color-changing microcapsule powder with good wrapping effect and yield is prepared by changing an emulsifier material by utilizing the determined composition proportion of the low-temperature color-changing compound; finally, the color-changing microcapsule powder and the adhesive are combined to prepare a coating, the coating is paved on the road surface through a film forming technology, and the color-changing effect, the road performance and the durability of the low-temperature color-changing coating are verified through an outdoor weather-proof test, an abrasion test, a water-proof test, a stain-resistant test and an anti-skid test. The method solves the problems of low coating rate, light color and low color changing speed of the low-temperature warning effect of the low-temperature color changing microcapsule prepared in the prior art, and prepares low-temperature color changing microcapsule powder with deep color changing and high color changing speed; the prepared road surface low-temperature dynamic early warning coating material can dynamically change the road surface color, improve the attention of a driver, furthest reduce the occurrence of traffic accidents, reduce economic loss, and can be used on the road surface for a long time, thereby realizing the road safety early warning intellectualization and providing guarantee for the road traffic safety in ice and snow weather.

The second embodiment is as follows: the first difference between this embodiment and the specific embodiment is that: the organic solvent in the first step is n-octanol, n-decanol or dodecanol. The other is the same as in the first embodiment.

And a third specific embodiment: this embodiment differs from one or both of the embodiments in that: the color developing agent in the first step is stearic acid, bisphenol A or p-nitrophenol. The other is the same as the first or second embodiment.

The specific embodiment IV is as follows: this embodiment differs from one of the first to third embodiments in that: the leuco agent in the first step is crystal violet lactone or 6' - (diethylamino) -1'2' -benzofluoran. The other embodiments are the same as those of the first to third embodiments.

Fifth embodiment: this embodiment differs from one to four embodiments in that: step two, adjusting the pH value to 5-6 by using acetic acid aqueous solution with the mass percentage of 99%; the dispersion and emulsification in the step II (1) is carried out for 2 to 3 hours under the conditions that the shearing speed is 1500 to 2000rpm and the temperature is 45 to 55 ℃; and (2) the mass percentage of the sodium salt solution of the styrene maleic anhydride copolymer in the step (1) is 10-15%. The other embodiments are the same as those of the first to fourth embodiments.

Specific embodiment six: this embodiment differs from one of the first to fifth embodiments in that: the wall material prepolymer solution in the step two (2) is prepared according to the following steps: mixing urea, melamine and formaldehyde solution at 70-80 ℃ and stirring speed of 200-400 rpm, regulating pH to 8-9 by using 40-60% sodium carbonate solution by mass percent, stirring for 0.5-1 h to make the solution clear and transparent, and finally diluting with distilled water to obtain wall material prepolymer solution; the mass percentage of the wall material prepolymer solution is 10% -15%; the mass percentage of the formaldehyde solution is 35% -40%; the mass ratio of the urea to the melamine is 1 (8-10); the mass ratio of the urea to the formaldehyde solution is 1 (15-25). The other embodiments are the same as those of the first to fifth embodiments.

Seventh embodiment: this embodiment differs from one of the first to sixth embodiments in that: and step two, adjusting the pH value to 5-6 by using acetic acid aqueous solution with the mass percentage of 99%. The other embodiments are the same as those of the first to sixth embodiments.

Eighth embodiment: this embodiment differs from one of the first to seventh embodiments in that: the adhesive containing the film forming auxiliary agent in the third step is specifically prepared by the following steps: mixing the adhesive and the film forming additive according to the mass ratio of (10-20): 1, and stirring for 3-5 min under the condition that the rotating speed is 200-400 rpm; the adhesive is aqueous polyurethane acrylic ester or bi-component polyurethane; the film forming auxiliary agent is propylene glycol methyl ether or diacetone alcohol. The other is the same as in embodiments one to seven.

Detailed description nine: the construction method of the pavement low-temperature dynamic early warning coating material comprises the following steps: coating a bonding layer on the clean road surface, paving a road surface low-temperature dynamic early warning coating material on the road surface coated with the bonding layer, and spreading glass beads, wherein the total thickness of the bonding layer, the road surface low-temperature dynamic early warning coating material and the glass beads is 2-3 mm; the glass beads account for 5-10% of the total mass of the bonding layer, the pavement low-temperature dynamic early warning coating material and the glass beads; the bonding layer is obtained by coating acrylic emulsion; the diameter of the glass beads is 0.2 mm-0.8 mm.

Detailed description ten: this embodiment differs from the ninth embodiment in that: the clean road surface is coated with a bonding layer with the thickness of 0.1-0.3 mm, then the road surface low-temperature dynamic early warning coating material is paved on the road surface coated with the bonding layer within 1-3 min, and glass beads are spread. The other is the same as in the ninth embodiment.

The following examples are used to verify the benefits of the present invention:

embodiment one:

1. preparing a low-temperature color-changing compound:

adding a color developing agent into an organic solvent at a speed of 1g/min under the conditions of stirring at 600rpm and a temperature of 75 ℃ to dissolve, adding a leuco agent at a speed of 1g/min to dissolve, and naturally cooling to room temperature to obtain a low-temperature color-changing compound;

the organic solvent in the first step is n-Decyl Alcohol (DA);

the color reagent in the first step is bisphenol A (BPA);

the leuco agent in the first step is Crystal Violet Lactone (CVL);

the mass ratio of the color developing agent to the leuco agent is 1:1; the mass ratio of the leuco agent to the organic solvent is 1:20;

2. preparing low-temperature color-changing microcapsule powder:

(1) mixing the low-temperature color-changing compound and a sodium salt solution of the styrene maleic anhydride copolymer, and then adjusting the pH value to 6, and dispersing and emulsifying to obtain reversible thermochromic emulsion;

the mass ratio of the low-temperature color-changing compound to the sodium styrene maleic anhydride copolymer in the sodium styrene maleic anhydride copolymer solution is 1:0.13;

(2) dropwise adding the wall material prepolymer solution into the reversible thermochromic emulsion at the speed of 1.2mL/min under the conditions that the temperature is 50 ℃ and the stirring rotation speed is 500rpm, then adjusting the pH to 6, increasing the temperature from 50 ℃ to 80 ℃ at the heating speed of 0.3 ℃/min, preserving heat for 2 hours under the conditions that the temperature is 80 ℃, and finally washing and drying to obtain low-temperature thermochromic microcapsule powder;

the volume ratio of the wall material prepolymer solution to the reversible thermochromic emulsion is 1:0.13;

3. preparing a low-temperature early warning color-changing coating:

adding low-temperature color-changing microcapsule powder into the adhesive containing the film-forming auxiliary agent under the condition of the rotating speed of 300rpm, and stirring for 20min to obtain a pavement low-temperature dynamic early warning coating material;

the mass ratio of the adhesive containing the film forming additive to the low-temperature color-changing microcapsule powder is 1:0.2.

Step two, adjusting the pH value to 6 by using an acetic acid aqueous solution with the mass percentage of 99%; the dispersion and emulsification in the step two (1) is carried out for 2 hours under the conditions that the shearing speed is 1500rpm and the temperature is 50 ℃; the mass percentage of the sodium salt solution of the styrene maleic anhydride copolymer in the step two (1) is 13 percent.

The wall material prepolymer solution in the step two (2) is prepared according to the following steps: mixing urea, melamine and formaldehyde solution at 75 ℃ and stirring speed of 300rpm, adjusting pH to 9 by using 53 mass percent sodium carbonate solution, stirring for 1h to make the solution clear and transparent, and finally diluting with distilled water to obtain wall material prepolymer solution; the mass percentage of the wall material prepolymer solution is 10%; the mass percentage of the formaldehyde solution is 37%; the mass ratio of the urea to the melamine is 1:8.4; the mass ratio of the urea to the formaldehyde solution is 1:20.2.

In the second step (2), the pH value is regulated to 6 by using acetic acid aqueous solution with the mass percentage of 99 percent;

the adhesive containing the film forming auxiliary agent in the third step is specifically prepared by the following steps: mixing the adhesive and the film forming additive according to the mass ratio of 15:1, and stirring for 4min under the condition of the rotating speed of 300 rpm; the adhesive is bi-component polyurethane; the film forming auxiliary agent is diacetone alcohol.

Embodiment two: the first difference between this embodiment and the first embodiment is that: the mass ratio of the color developing agent to the leuco agent in the first step is 2:1. The other is the same as in the first embodiment.

Embodiment III: the first difference between this embodiment and the first embodiment is that: the mass ratio of the color developing agent to the leuco agent in the first step is 3:1. The other is the same as in the first embodiment.

Comparative experiment one: the first difference between this comparative experiment and the example is: in the first step, the color developing agent and the leuco agent are thrown in at one time. The other is the same as in the first embodiment.

Comparison experiment II: the first difference between this comparative experiment and the example is: and step two (1), replacing the sodium salt solution of the styrene maleic anhydride copolymer with a polycarboxylate dispersant solution. The other is the same as in the first embodiment.

FIG. 1 is a physical diagram of a low-temperature color-changing compound, a is the low-temperature color-changing compound prepared in the first step of the example, and b is the low-temperature color-changing compound prepared in the first step of the comparative experiment; the graph shows that the low-temperature color-changing compound prepared in the embodiment I is clear and transparent and has better quality. And the low-temperature color-changing compound solution prepared by the comparison experiment turns blue, which affects the final quality of the color-changing compound.

Therefore, the final color-changing compound is clear and transparent by adopting a batch and sequential feeding mode, and the color-changing compound performance is prevented from being influenced by the reaction of the leuco agent and the undissolved color-developing agent.

The interaction of the leuco agent Crystal Violet Lactone (CVL), the developer bisphenol A (BPA) and the organic solvent n-Decyl Alcohol (DA) is determined by a differential scanning calorimetric test, and the method specifically comprises the following steps of: (1) adding a leuco agent into an organic solvent at a speed of 1g/min under the conditions of a stirring rotating speed of 600rpm and a temperature of 75 ℃ and dissolving, wherein the mass ratio of the leuco agent to the organic solvent is 1:10, 1:20 and 1:30, and the obtained products are named as DA/CVL=10:1, DA/CVL=20:1 and DA/CVL=30:1; (2) adding a color developing agent into an organic solvent at a speed of 1g/min under the conditions of a stirring rotating speed of 600rpm and a temperature of 75 ℃ and dissolving, wherein the mass ratio of the color developing agent to the organic solvent is 1:20, 2:20 and 3:20, and the obtained products are named as DA/BPA=20:1, DA/BPA=20:2 and DA/BPA=20:3; (3) the low temperature color change compound prepared in one to three steps one of the examples was named CVL/BPA/da=1:1:20, CVL/BPA/da=1:2:20, and CVL/BPA/da=1:3:20;

fig. 2 is a phase change process diagram of different systems, (a) DA/CVL, (b) DA/BPA, (c) CVL/BPA/DA,1 DA,2 DA/cvl=10:1, 3 DA/cvl=20:1, 4 DA/cvl=30:1, 5 DA/bpa=20:1, 6 DA/bpa=20:2, 7 DA/bpa=20:3, 8 CVL/BPA/da=1:1:20, 9 CVL/BPA/da=1:2:20, 10 CVL/BPA/da=1:3:20; FIG. 3 is a graph showing the change in enthalpy of phase transition of different systems, (a) DA/CVL (b) DA/BPA, and (c) CVL/BPA/DA;

as is clear from the phase transition process of the binary system of Crystal Violet Lactone (CVL) and n-Decanol (DA) in fig. 2 (a), the addition of crystal violet lactone and the variation of the amount of crystal violet lactone added have less influence on the phase transition temperature of n-decanol. When the proportion of crystal violet lactone in the system is increased, the phase transition ending temperature of the system in the temperature rising stage is stabilized at 14.7-17.2 ℃, and the fluctuation value is less than 3 ℃. From fig. 3 (a), it is clear that the enthalpy change of the binary system of crystal violet lactone and n-decanol has little influence on the phase change enthalpy of n-decanol due to the addition of crystal violet lactone and the change in the addition amount thereof. When the proportion of crystal violet lactone is increased, the phase transition enthalpy of the system is reduced from 300.4J/g to 291.1J/g, and the change amplitude is smaller than 10J/g. This demonstrates that there is no significant interaction between n-decanol and crystal violet lactone.

As is clear from fig. 2 (b), the binary system phase transition process of n-Decanol (DA) and bisphenol a (BPA), the addition of bisphenol a and the variation of the amount of bisphenol a added have a large influence on the phase transition temperature of n-decanol. When the proportion of bisphenol A is increased from 0 to 3, the phase transition end temperature of the system in the temperature rising stage is reduced from 15.9 ℃ to 10.7 ℃ and the amplitude is reduced by more than 5 ℃. From fig. 3 (b), it can be seen that the change in enthalpy of the binary system of bisphenol a and n-decanol has a large effect on the phase transition enthalpy of n-decanol by the addition of bisphenol a and the change in the amount of bisphenol a added. When the proportion of bisphenol A is increased from 0 to 3, the phase transition enthalpy of the system is reduced from 300.4J/g to 229.4J/g, and the change amplitude reaches 70J/g. This demonstrates that there is a significant interaction between bisphenol a and n-decanol, thereby affecting the phase change process of n-decanol.

From the phase transition process of the ternary color change compound system of Crystal Violet Lactone (CVL), bisphenol A (BPA) and n-Decanol (DA) in FIG. 2 (c), it is known that the addition of crystal violet lactone does not alleviate the effect of bisphenol A on the reduction of the phase transition temperature of n-decanol. When the dosage of the color developing agent is increased from 0 to 3, the phase transition end temperature of the system in the temperature rising stage is reduced from 15.9 ℃ to 10.3 ℃ and the amplitude is reduced by more than 5 ℃. However, as can be seen from the change in enthalpy of the ternary system of crystal violet lactone, bisphenol a and n-decanol in fig. 3 (c), the addition of crystal violet lactone significantly slows down the effect of bisphenol a on the decrease in enthalpy of n-decanol. When the amount of the color-developing agent is increased from 0 to 3, the phase transition enthalpy of the ternary system is reduced from 300.4J/g to 251.6J/g, and the amplitude reduction is 50J/g, which is obviously smaller than 70J/g of the bisphenol A and the n-decyl alcohol system. This demonstrates that the interaction between the late-added crystal violet lactone and bisphenol a releases some of the n-decanol, resulting in an increase in the enthalpy change of the color-changing system.

The results of the differential scanning calorimetric test show that there is no interaction between the crystal violet lactone and the n-decanol, but that there is a significant interaction between both with bisphenol a. Therefore, in the ternary color change compound system, crystal violet lactone and n-decanol compete with each other to compete for bisphenol a. For the color development effect and purity of the color-changing compound, the addition sequence is solvent n-decanol, color-developing agent bisphenol A and leuco agent crystal violet lactone.

The low-temperature dynamic early warning coating material is prepared by uniformly mixing microcapsule powder prepared from a color-changing compound and an adhesive by taking the color-changing temperature and the color-changing color difference as evaluation indexes.

In the evaluation index, the color change temperature is based on 0 ℃ color change; placing the sample in a low-temperature environment box, setting the initial temperature to-10 ℃, performing constant temperature treatment for 10min, testing the colorimetry parameters of the surface of the sample by using a colorimeter, and repeating the test. And then after the temperature is increased by 2 ℃, the colorimetry parameters of the surface of the test piece are tested after the constant temperature treatment is carried out for 10 minutes until the temperature reaches 10 ℃. And setting the initial temperature of the cooling process to be 10 ℃, performing constant temperature treatment for 10 minutes, testing colorimetry parameters of the surface of the test piece by adopting a colorimeter, and repeating the test. And then testing colorimetry parameters of the surface of the test piece after the temperature is reduced by 2 ℃ and the constant temperature is carried out for 10min until the temperature reaches-10 ℃, and repeating the test until the color difference value of two adjacent times is smaller than 1.5, wherein the calculation formula of the color difference is shown as (1):

wherein ΔE is ^* For color difference, Δl is the brightness index difference, Δa is the red-green axis chromaticity index difference, positive values represent red, and negative values represent green. Δb is yellow Lan Zhou chromaticity index difference, positive value indicates yellow, and negative value indicates blue. Δl, Δa, Δb are all measured by a color difference meter.

In the aspect of determining the total color-changing color difference, defining the difference value of the color-changing color difference corresponding to the color-changing ending temperature and the starting temperature as the total color-changing color difference, and the calculation formula is shown in (2):

ΔE＝ΔE ^* ₁ -ΔE ^* ₂ (2)

wherein, delta E is the total color difference,

for the color difference corresponding to the end temperature of the color change, +.>

The color difference corresponding to the color change starting temperature.

FIG. 4 is an optical microscope image of the low temperature color-changing microcapsule powder prepared in the first step of the example, with a scale of 1:200; the figure shows that the microcapsule has good appearance, high forming rate, good wrapping effect, average particle diameter of 10-20 microns, no impurity generation, yield of 50% and total chromatic aberration of 40-50.

FIG. 5 is an optical microscope picture of the low temperature color-changing microcapsule powder prepared in the second step of the comparative experiment, with a scale of 1:200; the graph shows that the apparent appearance of the microcapsule is poor, part of the microcapsule has surface cracking phenomenon, and a large amount of impurities are generated, which is caused by the failure of the wrapping of the wall material, the yield is about 20%, and the total color difference is 20-30.

FIG. 6 is a graph showing the total color difference and the temperature change of the low-temperature color-changing microcapsule powder prepared in the first step of the example, wherein 1 is the process of the multiple color of the total color difference of the low-temperature reversible color-changing microcapsule powder along with the decrease of the temperature, and 2 is the process of the decolorization of the total color difference of the frozen reversible color-changing microcapsule powder along with the increase of the temperature; as is clear from the graph, the color change of the sample surface was slightly perceived at the initial stage of the temperature increase. As the test temperature increases, the total color difference value deltae of the color-changing material sample gradually increases, and the surface color of the sample is obviously perceived to completely disappear. During the cooling process, the change of the surface color of the sample is exactly opposite to the change. When the temperature drops to a certain extent, the surface color of the sample returns to the original temperature-rising color. As can be seen from the graph, the color-changing material has a color-changing temperature interval of-2 to 2 ℃ and a compound color temperature interval of-4 to 2 ℃ and the total color difference of the color change reaches 45. Compared with the existing low-temperature color-changing early-warning material, the color-changing interval is narrowed, the color difference is increased, namely the color-changing speed is faster under the same time. Therefore, the low-temperature color-changing microcapsule prepared by the embodiment has smaller color-changing temperature interval, darker color and quicker color-changing speed, and is more beneficial to traffic safety early warning of frozen pavement.

Therefore, the color-changing microcapsule prepared by taking the sodium salt solution of the styrene maleic anhydride copolymer as the emulsifier has the characteristics of good appearance, good wrapping effect, uniform particle size, high yield and obvious color change.

Asphalt, crushed stone and mineral powder are used for preparing a road sample, and a double-component marking material mainly comprising methyl methacrylate is coated on the surface of the road sample to obtain an experimental part.

The construction method of the pavement low-temperature dynamic early warning coating material prepared in the first embodiment comprises the following steps: coating an adhesive layer with the thickness of 0.2mm on the surface of a road marking of an experimental part, then spreading a road low-temperature dynamic early warning coating material on the road coated with the adhesive layer and spreading glass beads within 1min to obtain the experimental part coated with the road low-temperature dynamic early warning coating material, wherein the total thickness of the adhesive layer, the road low-temperature dynamic early warning coating material and the glass beads is 3mm; the glass beads account for 7% of the total mass of the bonding layer, the pavement low-temperature dynamic early warning coating material and the glass beads; the bonding layer is obtained by coating acrylic emulsion; the diameter of the glass beads is 0.45mm.

Durability test of color-changing coating: and placing the experimental part coated with the pavement low-temperature dynamic early warning coating material in an outdoor environment to undergo the ageing and oxidization actions of natural environment and the natural climate actions of rainfall, snowfall and the like, and evaluating the color-changing color difference value by comparison.

The color-changing coating is applied to road mark lines and is inevitably influenced by direct sunlight, photooxidation, microbial degradation and the like, so that the color-changing effect of the coating material is reduced. In order to verify the durability of the color-changing coating material, an experimental piece coated with the pavement low-temperature dynamic early warning coating is placed in an outdoor roof environment, subjected to natural environment action (the temperature is 8-15 ℃, the relative humidity is 35%, the wind speed is 15 km/h), naturally aged for 60 days, subjected to color difference measurement once every 5 days, placed in an environment of minus 10 ℃ firstly, and then heated to 10 ℃ to measure the total color difference, and the color-changing effect of the color-changing coating is related to the number of days as follows: FIG. 7 is a graph comparing total color difference of an experimental part coated with a road surface low-temperature dynamic early warning coating material of the embodiment with the number of days. The graph shows that the color-changing color difference of the color-changing coating does not greatly fluctuate within the natural aging time of 60 days, the total color difference value is stabilized within the range of 40-45, and the color-changing effect is obvious. This means that the color-changing effect of the color-changing coating is not affected by ultraviolet aging, oxidation, rain wash and biodegradation, and the color-changing coating has good weather-proof durability.

Abrasion resistance test of color-changing coating: the experimental piece coated with the low-temperature dynamic early warning coating material of the road surface of the embodiment is rolled by a wet wheel abrasion instrument or an outdoor automobile, and the evaluation is carried out by measuring the quality change and the color change effect of the test piece before and after abrasion.

The color-changing coating is applied to road mark lines, is subjected to repeated rolling and abrasion of automobile load, and is researched in order to ensure the long-term service performance of the color-changing coating material. According to the asphalt mixture wet wheel abrasion test (JT/T708-2008), a wet wheel abrasion instrument is adopted to carry out abrasion resistance test, and after abrasion is carried out for 0 times, 1000 times, 2000 times, 3000 times, 4000 times, 5000 times and 11000 times respectively, the asphalt mixture wet wheel abrasion test is firstly placed in an environment of minus 10 ℃, then the temperature is increased to 10 ℃, the total color difference is measured, and the abrasion resistance evaluation is carried out by measuring the quality change and the color change effect of a test piece before and after abrasion. The test results are as follows: the test shows that the quality of the test piece is not changed before and after the wet wheel is worn, which indicates that the coating material has good wear resistance. FIG. 8 is a graph comparing total color difference of an experimental piece coated with a pavement low-temperature dynamic early warning coating material of the embodiment with abrasion time. As can be seen from the graph of the change of the total color difference with the abrasion frequency in FIG. 8, the total color difference of the color change shows a slow descending trend with the increase of the abrasion frequency, the total color difference value is reduced by 12.7% after 11000 abrasion actions, the coating still has a good color change effect, the influence of the abrasion actions on the color change performance is smaller, and the coating has good abrasion resistance.

Water resistance test of color-changing coating: and (3) adopting a soaking test method, placing an experimental piece coated with the low-temperature dynamic early warning coating material of the road surface of the embodiment in an iron pan filled with deionized water with the coating surface facing downwards, taking out the test piece after the water surface is soaked in the test piece and the water temperature is 20 ℃, sucking the surface moisture by using filter paper, and evaluating by observing whether the surface of the test piece is discolored, foamed, peeled off, wrinkled and light-lost.

The pavement is subjected to rain wash outdoors, and the coating is required to have certain water resistance. According to the requirements of the specification road marking paint, the water resistance of the color-changing coating is discussed by adopting a water immersion test method, and the test result of the water resistance test is that: fig. 9 is a water resistance test object diagram of an experimental part coated with the low-temperature dynamic early warning coating material of the pavement of the embodiment, (a) before soaking, and (b) after soaking for 24 hours. The graph shows that after 24 hours of soaking, the surface of the test piece has no phenomena of color change, bubbling, peeling, wrinkling and light loss, and the color-changing coating has good water resistance.

Stain resistance test of color-changing coating: and (3) adopting a gasoline pollution test method, placing an experimental piece coated with the low-temperature dynamic early warning coating material of the road surface of the embodiment in an iron pan filled with gasoline with the coating surface facing downwards, taking out the test piece after placing for 1h at the temperature of 20 ℃, sucking off surface oil, and measuring the change of the color change difference value before and after soaking for evaluation.

Fig. 10 is a graph showing the comparative effect of color change of the experimental part coated with the low-temperature dynamic early warning coating material for a road surface at-10 ℃ before and after soaking, wherein 1 is a road sample, 2 is a road marking, 3 is a color-changing coating, (a) before soaking in gasoline, and (b) after soaking in gasoline for 1 h. The marking material is coated on top of the asphalt mixture and the color-changing coating is coated on the marking, so that it can be seen from figure (b) that the gasoline causes some of the asphalt in the asphalt mixture to dissolve, causing it to adhere to the surface of the marking material, but the color-changing coating remains intact. The coating soaked by gasoline still has good color-changing performance, and the total color difference after soaking is 40.3 measured by a color difference meter, which is reduced by 11.8 percent compared with 45.7 before soaking. It is thus clear that the color-changing coating has good resistance to gasoline staining.

Skid resistance test of color-changing coating: the anti-slip test is performed by means of a pendulum friction meter, and the evaluation is performed by measuring the pendulum value of the test piece.

The anti-skid performance is a main factor affecting the road safety, and the anti-skid performance of the color-changing coating is measured by adopting a pendulum type friction meter according to the on-site test procedure of highway subgrade and road surface. Fig. 11 is a graph showing the comparison of the swing values, a is a small road sample, b is an experimental piece with the surface coated with the marking material, and c is an experimental piece coated with the low-temperature dynamic early warning coating material of the road surface of the embodiment. The test result shows that the swing value of the color-changing coating and the common marking are slightly lower than the swing value of the common road surface, but are higher than the 42BPN required by the specification, which indicates that the anti-skid capability of the color-changing coating is excellent.

Claims

1. The construction method of the pavement low-temperature dynamic early warning coating material is characterized by comprising the following steps of: coating a bonding layer on the clean road surface, paving a road surface low-temperature dynamic early warning coating material on the road surface coated with the bonding layer, and spreading glass beads, wherein the total thickness of the bonding layer, the road surface low-temperature dynamic early warning coating material and the glass beads is 2-3 mm; the glass beads account for 5-10% of the total mass of the bonding layer, the pavement low-temperature dynamic early warning coating material and the glass beads; the bonding layer is obtained by coating acrylic emulsion; the diameter of the glass beads is 0.2 mm-0.8 mm;

the pavement low-temperature dynamic early warning coating material is specifically prepared by the following steps:

1. preparing a low-temperature color-changing compound:

2. preparing low-temperature color-changing microcapsule powder:

3. preparing a low-temperature early warning color-changing coating:

2. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, which is characterized in that the clean pavement surface is coated with the bonding layer with the thickness of 0.1-0.3 mm, and then the pavement low-temperature dynamic early warning coating material is paved on the pavement coated with the bonding layer within 1-3 min, and glass beads are spread.

3. The method for constructing a pavement low-temperature dynamic early warning coating material according to claim 1, wherein the organic solvent in the first step is n-octanol, n-decanol or dodecanol.

4. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, wherein the color developing agent in the step one is stearic acid, bisphenol A or p-nitrophenol.

5. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, wherein the leuco agent in the first step is crystal violet lactone or 6' - (diethylamino) -1'2' -benzofluoran.

6. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, which is characterized in that in the second step (1), the pH is adjusted to 5-6 by using acetic acid aqueous solution with the mass percentage of 99%; the dispersion and emulsification in the step II (1) is carried out for 2 to 3 hours under the conditions that the shearing speed is 1500 to 2000rpm and the temperature is 45 to 55 ℃; and (2) the mass percentage of the sodium salt solution of the styrene maleic anhydride copolymer in the step (1) is 10-15%.

7. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, wherein the wall material prepolymer solution in the step two (2) is prepared by the following steps: mixing urea, melamine and formaldehyde solution at 70-80 ℃ and stirring speed of 200-400 rpm, regulating pH to 8-9 by using 40-60% sodium carbonate solution by mass percent, stirring for 0.5-1 h to make the solution clear and transparent, and finally diluting with distilled water to obtain wall material prepolymer solution; the mass percentage of the wall material prepolymer solution is 10% -15%; the mass percentage of the formaldehyde solution is 35% -40%; the mass ratio of the urea to the melamine is 1 (8-10); the mass ratio of the urea to the formaldehyde solution is 1 (15-25).

8. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, which is characterized in that in the second step (2), the pH is adjusted to 5-6 by using acetic acid aqueous solution with the mass percentage of 99%.

9. The construction method of the pavement low-temperature dynamic early warning coating material according to claim 1, which is characterized in that the adhesive containing the film forming auxiliary agent in the step three is specifically prepared by the following steps: mixing the adhesive and the film forming additive according to the mass ratio of (10-20): 1, and stirring for 3-5 min under the condition that the rotating speed is 200-400 rpm; the adhesive is aqueous polyurethane acrylic ester or bi-component polyurethane; the film forming auxiliary agent is propylene glycol methyl ether or diacetone alcohol.