Thermochromic spunlace nonwoven fabric and preparation method thereof

Abstract

The application discloses a temperature-sensitive color-changing spunlace nonwoven fabric and a preparation method thereof, and comprises a spunlace nonwoven fabric substrate and temperature-sensitive color-changing microcapsules loaded on the surface of the spunlace nonwoven fabric substrate through digital printing; the core material of the temperature-sensitive color-changing microcapsules comprises a color former, a color developing agent and a solvent; and the wall material of the temperature-sensitive color-changing microcapsules is melamine resin doped with citrate modified porous carbon. The temperature-sensitive color-changing microcapsules are not easy to be lost, and the temperature-sensitive color-changing spunlace nonwoven fabric is sensitive to color change.

Description

Technical Field

[0001] This invention relates to the field of smart fabric technology, and in particular to a thermosensitive color-changing spunlace nonwoven fabric and its preparation method. Background Technology

[0002] Thermochromic materials are smart materials that respond to temperature changes, representing changes in ambient temperature through their color variations. In the textile industry, when thermochromic materials are applied to fabrics, the treated fabric surface produces color-changing patterns and designs when the ambient temperature changes. This not only adds aesthetic appeal and interest to the textiles but also serves as an indicator, hence the widespread application of thermochromic materials in textiles.

[0003] In existing technologies, thermochromic materials are typically made into microcapsules, which are then bonded to the surface of fabrics using an adhesive to create thermochromic fabrics. For example, the Chinese patent document "A Thermochromic Microcapsule for Use in Fabrics and its Preparation Method" (publication number CN111607972A) discloses a thermochromic microcapsule consisting of a core and a shell. The shell covers the core and is made of melamine resin. The core is a composite material composed of a color-developing agent, a color-developing agent, nano-tourmaline, a thermally conductive material, and a solvent.

[0004] However, when thermochromic microcapsules are applied to the fabric surface using existing technology, their adhesion to the fabric surface is related to the amount of adhesive used. If the amount of adhesive is too small, the adhesion of the thermochromic microcapsules to the fabric surface is poor, and they are easily washed away. On the other hand, if the amount of adhesive is too large, it will affect the color-changing sensitivity of the thermochromic material encapsulated in the microcapsules. Therefore, it is difficult to obtain thermochromic fabrics with firm adhesion of thermochromic materials and sensitive color change. Summary of the Invention

[0005] This invention aims to overcome the aforementioned problems of existing thermochromic materials and provides a thermochromic spunlace nonwoven fabric and its preparation method. By adding citrate-modified porous carbon material to the wall material of the thermochromic microcapsules, the color-changing sensitivity of the microcapsules can be improved, and the adhesion of the microcapsules to the surface of the spunlace nonwoven fabric can be enhanced, resulting in a thermochromic spunlace nonwoven fabric in which the thermochromic microcapsules are not easily lost and the color-changing is sensitive.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A thermochromic spunlace nonwoven fabric includes a spunlace nonwoven fabric substrate and thermochromic microcapsules loaded onto the surface of the spunlace nonwoven fabric substrate by digital printing; the core material of the thermochromic microcapsules includes a color-developing agent, a color-developing agent and a solvent; the wall material of the thermochromic microcapsules is a melamine resin doped with citrate-modified porous carbon.

[0008] This invention utilizes digital printing to load thermochromic microcapsules onto the surface of spunlace nonwoven fabric, enabling the fabric to acquire a color-changing pattern that adapts to temperature variations. In the thermochromic microcapsules of this invention, a ternary compound of a color-developing agent, a color-developing agent, and a solvent serves as the core material of the organic reversible thermochromic material. The color-developing agent and the color-developing agent act as electron donors and electron acceptors, respectively. Electrons are transferred when the temperature changes, absorbing or radiating light of a specific wavelength during this process, resulting in a color change on the surface. This allows the core material of this invention to reversibly change color with temperature. Simultaneously, this invention uses melamine resin as a wall material to encapsulate the organic reversible thermochromic material, isolating it from the external environment. This resin can be combined with binders and other components to create printing inks, enabling the printing and finishing of spunlace nonwoven fabrics. However, resin coating reduces the color-changing sensitivity of the core material, and the affinity and adhesion between the melamine resin wall material and the spunlace nonwoven fabric surface are poor, requiring a large amount of binder to firmly load the thermosensitive color-changing microcapsules onto the spunlace nonwoven fabric surface, which further reduces the color-changing sensitivity of the core material. Therefore, this invention adds citrate-modified porous carbon to the melamine resin wall material. The addition of porous carbon material facilitates electron transfer during the color-changing process, thereby improving the color-changing sensitivity of the core material. At the same time, the modification of the porous carbon material with citrate can improve the affinity and adhesion between the wall material and the spunlace nonwoven fabric surface, allowing the thermosensitive microcapsules to be firmly loaded onto the spunlace nonwoven fabric surface with a smaller amount of binder, further improving the color-changing sensitivity of the spunlace nonwoven fabric surface pattern.

[0009] Preferably, the color-developing agent in the core material is crystal violet lactone, the color-developing agent is bisphenol A, and the solvent is cetyl alcohol; the mass ratio of the color-developing agent, the color-developing agent, and the solvent is 1:3-5:65-75. This invention uses crystal violet lactone as the color-developing agent, bisphenol A as the color-developing agent, and cetyl alcohol as the solvent, resulting in an organic reversible thermochromic material core material with a low color-changing temperature, reversible color change, and high sensitivity.

[0010] Preferably, the mass ratio of citrate-modified porous carbon to melamine resin in the wall material is 0.1–0.2:10.

[0011] Preferably, the citrate-modified porous carbon in the wall material is prepared by calcining sodium stearate at 700–800°C for 2–3 hours in an inert atmosphere to obtain a porous carbon material; then, the porous carbon material is placed in an aqueous citrate solution, with a mass ratio of porous carbon material to citrate in the solution of 1:8–10, and ultrasonically treated for 2–4 hours. The product is then filtered and dried to obtain the citrate-modified porous carbon. The porous carbon material prepared by calcining sodium stearate in this invention has a rich pore structure and excellent electron transport properties, which can effectively improve the color-changing sensitivity of the core material. Ultrasonic impregnation modification with an aqueous citrate solution can improve its surface polarity, which is beneficial for improving the adhesion between the wall material and the surface of the spunlace nonwoven fabric.

[0012] Preferably, in the thermosensitive color-changing microcapsule, the mass ratio of the wall material to the core material is 4 to 5:1.

[0013] The present invention also provides a method for preparing the above-mentioned thermosensitive color-changing spunlace nonwoven fabric, comprising the following steps:

[0014] (1) Preparation of citrate-modified porous carbon;

[0015] (2) Preparation of prepolymer solution: Melamine is mixed with 35-37 wt% formaldehyde solution, diluted with water, and the pH of the solution is adjusted to 8-9 with triethanolamine. The mixture is reacted at 65-75℃ for 30-60 min to obtain the prepolymer solution. The mass ratio of melamine to 35-37 wt% formaldehyde solution is 1:2-4.

[0016] (3) Preparation of core material emulsion: Dissolve the colorant and color developer in a solvent to obtain core material raw material, add the core material raw material to water containing emulsifier, and shear emulsify at 70-80℃ for 30-60 min to obtain core material emulsion;

[0017] (4) Preparation of thermosensitive color-changing microcapsules: Citrate-modified porous carbon was added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution; the mixed solution was added dropwise to the core material emulsion, stirred and mixed evenly, and then heated to 70-80℃ and kept at the temperature for 30-60 min. Then, the pH of the system was adjusted to 3.5-4.5 with citric acid solution, and the reaction was continued for 2-4 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0018] (5) Preparation of digital printing ink: Thermosensitive color-changing microcapsules are mixed evenly with binder, water-soluble organic solvent, humectant, surfactant and water to obtain digital printing ink;

[0019] (6) Pretreatment of spunlace nonwoven fabric: The surface of the spunlace nonwoven fabric is subjected to low-temperature air plasma treatment to obtain the pretreated spunlace nonwoven fabric.

[0020] (7) Digital printing: Digital printing ink is sprayed onto the surface of the pretreated spunlace nonwoven fabric through digital printing, and the thermosensitive color-changing spunlace nonwoven fabric is obtained after drying.

[0021] This invention first prepares thermosensitive color-changing microcapsules doped with citrate-modified porous carbon in wall materials through in-situ polymerization of melamine and formaldehyde. Then, it mixes these microcapsules with adhesives and other additives to prepare digital printing ink. Before digital printing, the surface of the spunlace nonwoven fabric is treated with low-temperature plasma in air, which can improve the surface roughness of the spunlace nonwoven fabric and introduce polar groups on its surface. After the thermosensitive color-changing microcapsules are applied to its surface through digital printing, it is beneficial to improve the bonding force between the spunlace nonwoven fabric and the thermosensitive color-changing microcapsules. With less adhesive added, the thermosensitive color-changing microcapsules can be firmly attached, thereby improving its color-changing sensitivity.

[0022] Preferably, the emulsifier in step (3) is SMA, and the amount of emulsifier added is 0.5 to 1.5% of the mass of the core material emulsion.

[0023] Preferably, the digital printing ink in step (5) comprises, by weight, 30-50 parts of thermosensitive color-changing microcapsules, 10-20 parts of binder, 8-12 parts of water-soluble organic solvent, 8-12 parts of humectant, 0.5-1 part of surfactant and 5-15 parts of water.

[0024] Preferably, the adhesive is a polyurethane emulsion and / or a polyacrylate emulsion; the water-soluble organic solvent is ethanol and / or isopropanol; the humectant is ethylene glycol and / or glycerol; and the surfactant is at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, Tween 60, and Tween 80.

[0025] Preferably, the pressure of the air low-temperature plasma treatment in step (6) is 30-50 Pa, the power is 50-150 W, and the treatment time is 3-5 min.

[0026] Therefore, the present invention has the following beneficial effects:

[0027] (1) Adding citrate-modified porous carbon to melamine resin wall material can improve the color change sensitivity of the core material and enhance the affinity and adhesion between the wall material and the surface of spunlace nonwoven fabric.

[0028] (2) Before digital printing, the surface of the spunlace nonwoven fabric is treated with low-temperature plasma in air, which helps to improve the bonding force between the spunlace nonwoven fabric and the thermosensitive color-changing microcapsules. With less adhesive added, the thermosensitive color-changing microcapsules can be firmly attached, thereby improving their color-changing sensitivity. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] In this invention, unless otherwise specified, all equipment and raw materials are available from the market or commonly used in the industry. The methods in the following embodiments are conventional methods in the field unless otherwise specified.

[0031] Example 1:

[0032] A method for preparing a thermosensitive color-changing spunlace nonwoven fabric includes the following steps:

[0033] (1) Preparation of citrate-modified porous carbon: Sodium stearate was calcined at 750°C for 2.5 h in N2 atmosphere to obtain porous carbon material; then the porous carbon material was placed in 0.5 mol / L sodium citrate aqueous solution, the mass ratio of porous carbon material to citrate in solution was 1:9, ultrasonic treatment was performed for 3 h, and the product was filtered and dried to obtain the citrate-modified porous carbon.

[0034] (2) Preparation of prepolymer solution: Melamine and 37wt% formaldehyde solution are mixed evenly at a mass ratio of 1:3, diluted with 3 times the volume of water, and the pH of the solution is adjusted to 8.5 with triethanolamine. The reaction is carried out at 70℃ for 40 min to obtain the prepolymer solution.

[0035] (3) Preparation of core material emulsion: The color-developing agent crystal violet lactone and the color-developing agent bisphenol A are dissolved in cetyl alcohol in a water bath at 80°C. The mass ratio of crystal violet lactone, bisphenol A and cetyl alcohol is 1:4:70 to obtain core material raw material. The core material raw material is added to water containing emulsifier SMA. The mass-volume ratio of core material raw material to water is 1g:50mL. The emulsifier is sheared and emulsified at 75°C for 40min to obtain core material emulsion. The amount of emulsifier added is 1% of the mass of core material emulsion.

[0036] (4) Preparation of thermosensitive color-changing microcapsules: Citrate-modified porous carbon was added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution. The mass ratio of citrate-modified porous carbon to the total mass of melamine and formaldehyde was 0.15:10. The mixed solution was added dropwise to the core material emulsion. The mass ratio of the total mass of melamine and formaldehyde to the mass of the core material raw material was 4.5:1. After stirring and mixing evenly, the temperature was raised to 75℃ and kept for 40 min. Then, the pH of the system was adjusted to 4.1 with citric acid solution and kept for 3 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0037] (5) Preparation of digital printing ink: By weight, 40 parts of thermosensitive color-changing microcapsules, 15 parts of polyurethane emulsion (BASF, Joncryl HYB6336), 10 parts of anhydrous ethanol, 10 parts of ethylene glycol, 0.8 parts of sodium dodecyl sulfonate and 10 parts of deionized water are mixed evenly and filtered through a 0.5 μm microporous filter membrane to obtain digital printing ink.

[0038] (6) Pretreatment of spunlace nonwoven fabric: The surface of the spunlace nonwoven fabric is subjected to low-temperature air plasma treatment to obtain the pretreated spunlace nonwoven fabric; the pressure of the low-temperature air plasma treatment is 40Pa, the power is 100W, and the treatment time is 4min.

[0039] (7) Digital printing: Digital printing ink is sprayed onto the surface of the pretreated spunlace nonwoven fabric through digital printing, and the thermosensitive color-changing spunlace nonwoven fabric is obtained after drying.

[0040] Example 2:

[0041] A method for preparing a thermosensitive color-changing spunlace nonwoven fabric includes the following steps:

[0042] (1) Preparation of citrate-modified porous carbon: Sodium stearate was calcined at 700°C for 3 hours in N2 atmosphere to obtain porous carbon material; then the porous carbon material was placed in 0.5 mol / L sodium citrate aqueous solution, the mass ratio of porous carbon material to citrate in solution was 1:8, ultrasonic treatment was performed for 2 hours, and the product was filtered and dried to obtain the citrate-modified porous carbon.

[0043] (2) Preparation of prepolymer solution: Melamine and 37wt% formaldehyde solution are mixed evenly at a mass ratio of 1:2, diluted with 5 times the volume of water, and the pH of the solution is adjusted to 8.1 with triethanolamine. The reaction is carried out at 75℃ for 30 min to obtain the prepolymer solution.

[0044] (3) Preparation of core material emulsion: The color-developing agent crystal violet lactone and the color-developing agent bisphenol A are dissolved in cetyl alcohol in a water bath at 80°C. The mass ratio of crystal violet lactone, bisphenol A and cetyl alcohol is 1:3:65 to obtain core material raw material. The core material raw material is added to water containing emulsifier SMA. The mass-volume ratio of core material raw material to water is 1g:50mL. The emulsifier is sheared and emulsified at 70°C for 60min to obtain core material emulsion. The amount of emulsifier added is 0.5% of the mass of core material emulsion.

[0045] (4) Preparation of thermosensitive color-changing microcapsules: Citrate-modified porous carbon was added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution. The mass ratio of citrate-modified porous carbon to the total mass of melamine and formaldehyde was 0.1:10. The mixed solution was added dropwise to the core material emulsion. The mass ratio of the total mass of melamine and formaldehyde to the mass of the core material raw material was 5:1. After stirring and mixing evenly, the temperature was raised to 70℃ and kept for 60 min. Then, the pH of the system was adjusted to 3.5 with citric acid solution and kept for 4 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0046] (5) Preparation of digital printing ink: By weight, 30 parts of thermosensitive color-changing microcapsules, 10 parts of polyurethane emulsion (BASF, Joncryl HYB6336), 8 parts of anhydrous ethanol, 8 parts of ethylene glycol, 0.5 parts of sodium dodecyl sulfonate and 5 parts of deionized water are mixed evenly and filtered through a 0.5 μm microporous filter membrane to obtain digital printing ink.

[0047] (6) Pretreatment of spunlace nonwoven fabric: The surface of the spunlace nonwoven fabric is subjected to low-temperature air plasma treatment to obtain the pretreated spunlace nonwoven fabric; the pressure of the low-temperature air plasma treatment is 30Pa, the power is 50W, and the treatment time is 5min.

[0048] (7) Digital printing: Digital printing ink is sprayed onto the surface of the pretreated spunlace nonwoven fabric through digital printing, and the thermosensitive color-changing spunlace nonwoven fabric is obtained after drying.

[0049] Example 3:

[0050] A method for preparing a thermosensitive color-changing spunlace nonwoven fabric includes the following steps:

[0051] (1) Preparation of citrate-modified porous carbon: Sodium stearate was calcined at 800°C for 2 hours in N2 atmosphere to obtain porous carbon material; then the porous carbon material was placed in 0.5 mol / L sodium citrate aqueous solution, the mass ratio of porous carbon material to citrate in solution was 1:10, ultrasonic treatment was performed for 4 hours, and the product was filtered and dried to obtain the citrate-modified porous carbon.

[0052] (2) Preparation of prepolymer solution: Melamine and 37wt% formaldehyde solution are mixed evenly at a mass ratio of 1:4, diluted with 3 times the volume of water, and the pH of the solution is adjusted to 9.0 with triethanolamine. The mixture is reacted at 70℃ for 60 min to obtain the prepolymer solution.

[0053] (3) Preparation of core material emulsion: The color-developing agent crystal violet lactone and the color-developing agent bisphenol A are dissolved in cetyl alcohol in a water bath at 80°C. The mass ratio of crystal violet lactone, bisphenol A and cetyl alcohol is 1:5:75 to obtain core material raw material. The core material raw material is added to water containing emulsifier SMA. The mass-volume ratio of core material raw material to water is 1g:50mL. The emulsifier is sheared and emulsified at 80°C for 30min to obtain core material emulsion. The amount of emulsifier added is 1.5% of the mass of core material emulsion.

[0054] (4) Preparation of thermosensitive color-changing microcapsules: Citrate-modified porous carbon was added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution. The mass ratio of citrate-modified porous carbon to the total mass of melamine and formaldehyde was 0.2:10. The mixed solution was added dropwise to the core material emulsion. The mass ratio of the total mass of melamine and formaldehyde to the mass of the core material raw material was 4:1. After stirring and mixing evenly, the temperature was raised to 80℃ and kept for 30 min. Then, the pH of the system was adjusted to 4.5 with citric acid solution and kept for 2 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0055] (5) Preparation of digital printing ink: By weight, 50 parts of thermosensitive color-changing microcapsules, 20 parts of polyurethane emulsion (BASF, Joncryl HYB6336), 12 parts of anhydrous ethanol, 12 parts of ethylene glycol, 1 part of sodium dodecyl sulfonate and 15 parts of deionized water are mixed evenly and filtered through a 0.5 μm microporous filter membrane to obtain digital printing ink.

[0056] (6) Pretreatment of spunlace nonwoven fabric: The surface of the spunlace nonwoven fabric is subjected to low-temperature air plasma treatment to obtain the pretreated spunlace nonwoven fabric; the pressure of the low-temperature air plasma treatment is 50Pa, the power is 150W, and the treatment time is 3min.

[0057] (7) Digital printing: Digital printing ink is sprayed onto the surface of the pretreated spunlace nonwoven fabric through digital printing, and the thermosensitive color-changing spunlace nonwoven fabric is obtained after drying.

[0058] Comparative Example 1 (wall material without citrate-modified porous carbon):

[0059] A method for preparing a thermosensitive color-changing spunlace nonwoven fabric includes the following steps:

[0060] (1) Preparation of prepolymer solution: The method is the same as in Example 1;

[0061] (2) Preparation of core material emulsion: The method is the same as in Example 1;

[0062] (3) Preparation of thermosensitive color-changing microcapsules: The prepolymer solution was added to the core material emulsion. The total mass ratio of melamine and formaldehyde to the core material raw material was 4.5:1. After stirring and mixing evenly, the temperature was raised to 75℃ and kept for 40 min. Then, the pH of the system was adjusted to 4.1 with citric acid solution and kept for 3 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0063] The subsequent steps for preparing digital printing ink, pre-treating spunlace nonwoven fabric, and digital printing are the same as in Example 1.

[0064] Comparative Example 2 (no citrate modification of porous carbon):

[0065] A method for preparing a thermosensitive color-changing spunlace nonwoven fabric includes the following steps:

[0066] (1) Preparation of porous carbon materials: Sodium stearate was calcined at 750°C for 2.5 h in N2 atmosphere to obtain porous carbon materials;

[0067] (2) Preparation of prepolymer solution: The method is the same as in Example 1;

[0068] (3) Preparation of core material emulsion: The method is the same as in Example 1;

[0069] (4) Preparation of thermosensitive color-changing microcapsules: Porous carbon material was added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution. The mass ratio of the porous carbon material to the total mass of melamine and formaldehyde was 0.15:10. The mixed solution was added dropwise to the core material emulsion. The mass ratio of the total mass of melamine and formaldehyde to the mass of the core material raw material was 4.5:1. After stirring and mixing evenly, the temperature was raised to 75℃ and kept for 40 min. Then, the pH of the system was adjusted to 4.1 with citric acid solution and kept for 3 h. The product was washed and dried to obtain thermosensitive color-changing microcapsules.

[0070] The subsequent steps for preparing digital printing ink, pre-treating spunlace nonwoven fabric, and digital printing are the same as in Example 1.

[0071] Comparative Example 3 (no pretreatment of the spunlace nonwoven fabric surface):

[0072] The difference between Comparative Example 3 and Example 1 is that the surface of the spunlace nonwoven fabric is not subjected to low-temperature plasma treatment, but digital printing is performed directly. All other aspects are the same as in Example 1.

[0073] The thermochromic properties and color fastness to soap washing of the thermochromic spunlace nonwoven fabrics prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0074] The test method for color fastness to soap washing refers to GB / T 3921-2008;

[0075] Color change time T c The test method is as follows: heat the thermosensitive color-changing spunlace nonwoven fabric to 40°C and record the time required for all the surface patterns to change from purple to colorless.

[0076] Recolor Time T f The test method is as follows: after the spunlace nonwoven fabric has changed color, heating is stopped, and it is cooled at room temperature. The time required for the surface pattern to change completely from colorless to purple is recorded.

[0077] Table 1: Performance test results of thermosensitive color-changing spunlace nonwoven fabric.

[0078]

[0079] As shown in Table 1, the thermochromic spunlace nonwoven fabrics prepared by the method of this invention in Examples 1-3 have shorter color-changing and recoloring times, higher color-changing sensitivity, and good color fastness to washing. In Comparative Example 1, without adding citrate-modified porous carbon to the wall material of the thermochromic microcapsules, the color-changing and recoloring times of the thermochromic spunlace nonwoven fabric were significantly prolonged, the color-changing sensitivity decreased, and the color fastness to washing was also lower than in Example 1. In Comparative Example 2, without modifying the porous carbon material with citrate, the color fastness to washing of the thermochromic spunlace nonwoven fabric was further reduced. This may be because the surface properties of the porous carbon material affect the microcapsule forming process, influencing its surface morphology and properties, thereby affecting its bonding force with the surface of the spunlace nonwoven fabric. In Comparative Example 3, the surface of the spunlace nonwoven fabric was not subjected to low-temperature plasma treatment before digital printing. The washing fastness of the resulting thermochromic spunlace nonwoven fabric was also lower than that in Example 1. This indicates that the low-temperature plasma treatment of the spunlace nonwoven fabric surface can improve its bonding force with the thermochromic microcapsules.

Claims

1. A thermosensitive color-changing spunlace nonwoven fabric, characterized in that, The invention comprises a spunlace nonwoven fabric substrate and thermosensitive color-changing microcapsules loaded onto the surface of the spunlace nonwoven fabric substrate by digital printing. The core material of the thermosensitive color-changing microcapsules includes a color-developing agent, a color-developing agent, and a solvent. The wall material of the thermosensitive color-changing microcapsules is a melamine resin doped with citrate-modified porous carbon. The citrate-modified porous carbon is prepared by ultrasonically treating a porous carbon material made by calcining sodium stearate with a citrate aqueous solution for 2-4 hours, filtering and drying the product, wherein the calcination is carried out at 700-800℃ for 2-3 hours in an inert atmosphere, and the mass ratio of the porous carbon material to the citrate in the citrate aqueous solution is 1:8-10.

2. The thermosensitive color-changing spunlace nonwoven fabric according to claim 1, characterized in that, The colorant in the core material is crystal violet lactone, the color developer is bisphenol A, and the solvent is cetyl alcohol; the mass ratio of the colorant, color developer, and solvent is 1:3~5:65~75.

3. The thermosensitive color-changing spunlace nonwoven fabric according to claim 1, characterized in that, The mass ratio of citrate-modified porous carbon to melamine resin in the wall material is 0.1~0.2:

10.

4. The thermosensitive color-changing spunlace nonwoven fabric according to claim 1 or 2, characterized in that, In the thermosensitive color-changing microcapsule, the mass ratio of the wall material to the core material is 4~5:

1.

5. A method for preparing a thermosensitive color-changing spunlace nonwoven fabric as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Preparation of citrate-modified porous carbon; (2) Preparation of prepolymer solution: Melamine is mixed with 35-37 wt% formaldehyde solution, diluted with water, and the pH of the solution is adjusted to 8-9 with triethanolamine. The mixture is reacted at 65-75℃ for 30-60 min to obtain the prepolymer solution. The mass ratio of melamine to 35-37 wt% formaldehyde solution is 1:2-4. (3) Preparation of core material emulsion: Dissolve the colorant and color developer in a solvent to obtain core material raw material, add the core material raw material to water containing emulsifier, and shear emulsify at 70~80℃ for 30~60min to obtain core material emulsion; (4) Preparation of thermosensitive color-changing microcapsules: Citrate-modified porous carbon is added to the prepolymer solution and ultrasonically dispersed to obtain a mixed solution; the mixed solution is added dropwise to the core material emulsion, stirred and mixed evenly, and then heated to 70~80℃ and kept at the temperature for 30~60min. Then, the pH of the system is adjusted to 3.5~4.5 with citric acid solution, and the reaction is continued for 2~4h. The product is washed and dried to obtain thermosensitive color-changing microcapsules. (5) Preparation of digital printing ink: Thermosensitive color-changing microcapsules are mixed evenly with binder, water-soluble organic solvent, humectant, surfactant and water to obtain digital printing ink; (6) Pretreatment of spunlace nonwoven fabric: The surface of the spunlace nonwoven fabric is subjected to low-temperature plasma treatment in air to obtain the pretreated spunlace nonwoven fabric. (7) Digital printing: Digital printing ink is sprayed onto the surface of the pretreated spunlace nonwoven fabric by digital printing, and the thermosensitive color-changing spunlace nonwoven fabric is obtained after drying.

6. The preparation method according to claim 5, characterized in that, The emulsifier in step (3) is SMA, and the amount of emulsifier added is 0.5~1.5% of the mass of the core material emulsion.

7. The preparation method according to claim 5, characterized in that, The digital printing ink in step (5) comprises, by weight, 30-50 parts of thermosensitive color-changing microcapsules, 10-20 parts of binder, 8-12 parts of water-soluble organic solvent, 8-12 parts of humectant, 0.5-1 part of surfactant and 5-15 parts of water.

8. The preparation method according to claim 5 or 7, characterized in that, The adhesive is a polyurethane emulsion and / or a polyacrylate emulsion; the water-soluble organic solvent is ethanol and / or isopropanol; the humectant is ethylene glycol and / or glycerol; and the surfactant is at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, Tween 60, and Tween 80.

9. The preparation method according to claim 5, characterized in that, In step (6), the air low-temperature plasma treatment has a pressure of 30~50Pa, a power of 50~150W, and a treatment time of 3~5min.

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