Chitin / anthocyanin indicator ink and preparation method and application thereof

Abstract

The invention discloses a method for preparing a chitin / anthocyanidin indicator ink, which is characterized in that it comprises the following steps: adding chitin to an organic solvent, mixing evenly, adding anthocyanidin, and continuing to mix to obtain an active ink; drying the active ink and crushing it into powder to obtain a toner; mixing a surfactant, a pH regulator, and deionized water evenly with the toner to obtain the chitin / anthocyanidin indicator ink. The method for preparing the chitin / anthocyanidin indicator ink of the invention uses anthocyanidin as a pH response material, adds environmentally friendly materials such as chitin, and the prepared water-based ink does not volatilize the solvent during the production process to cause pollution, and is non-toxic and harmless to food and human body; a degradable substrate and a fabric to be transferred are used during the cold transfer printing operation, and the prepared transfer printing fabric finished product can be used to detect the freshness and corruption degree of food, and has good application prospects in the field of food packaging.

Description

Technical Field

[0001] The invention relates to the technical field of indicator ink and packaging materials, and in particular to a method for preparing chitin / anthocyanidin indicator ink, the chitin / anthocyanidin indicator ink prepared by the preparation method, and the application of the chitin / anthocyanidin indicator ink in indicator materials such as packaging materials. Background Art

[0002] In the process of food transportation, freshness preservation plays a vital role. When food is spoiled, it will breed the proliferation of microorganisms and produce ammonia, amines, and alcohols, which will lead to changes in the pH of the environment. Anthocyanins can sensitively sense the changes in pH and reflect the freshness of packaged food through color changes.

[0003] Existing industrial food freshness indication methods mostly use freshness indicator films. The production process of freshness indicator films is cumbersome and has a low transfer rate. It is not suitable for large-scale industrial production, which greatly affects production efficiency. At present, most of the production methods that give packaging freshness indication functions use solution casting. For example, patent CN201911071294.6 discloses a chitosan / kojic acid / chlorokojic acid composite antibacterial fresh-keeping film and its preparation method. This method is beneficial to maintaining the stability of anthocyanins, but the solution casting method is difficult to achieve large-scale industrial production due to the long film formation time and small processing volume; at the same time, the film prepared by this method has poor air permeability, and anaerobic bacteria are easy to breed in the package.

[0004] Another industrial production method often uses hot pressing and extrusion to form a film containing an indicator. This method can be used for large-scale production of packaging films, but the indicator is easily decomposed during the high-temperature hot pressing process, reducing its sensitivity or losing its indicating performance; in addition, the active film prepared by this method has good antioxidant and hydrophobic properties, but lacks mechanical and optical properties, and the film surface is easily damaged during stretching. In addition, the existing freshness indicator films are mostly attached to non-degradable packaging materials such as PE, and are not easy to combine with degradable fabrics, which can easily cause environmental pollution.

[0005] Another example is the method disclosed in patent CN202111468651.X that anthocyanins are loaded on nanoparticles and blended with spinning solution to prepare a fiber membrane with a freshness indication function through an electrospinning process. This method ensures the stability of the structure and function of anthocyanins through the form of loading, but due to the requirements of the concentration of the spinning solution, the anthocyanin content should not be too high, the prepared fiber membrane has a weak indication function, the fiber is thicker, and the elongation at break is poor. Summary of the invention

[0006] In view of this, in order to overcome the defects of the prior art, one of the objects of the present invention is to provide a chitin / anthocyanin indicator ink and a preparation method thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing chitin / anthocyanin indicator ink comprises the following steps:

[0009] Add chitin to an organic solvent, mix well, add anthocyanin, continue mixing, and obtain active ink;

[0010] The active ink is dried and the organic solvent is removed, and then crushed into powder to obtain toner;

[0011] The surfactant, pH regulator, deionized water and the ink powder are uniformly mixed, and the pH is adjusted to 6-6.5 to obtain the chitin / anthocyanin indicator ink.

[0012] According to some preferred embodiments of the present invention, the mass ratio of chitin to anthocyanin is 1:4-5.

[0013] According to some preferred embodiments of the present invention, the deacetylation degree of the chitin is 25-30%.

[0014] According to some preferred implementation aspects of the present invention, the mass proportion of chitin in the chitin / anthocyanin indicator ink is 5-8%; the mass proportion of anthocyanin is 20-25%.

[0015] In some embodiments, based on 100 parts by weight, the chitin / anthocyanin indicator ink includes 20-25 parts of anthocyanin, 5-8 parts of chitin, 0.1-3 parts of surfactant, 0.1-5 parts of pH adjuster, and the balance is deionized water; chitin can be used as a stabilizer and surfactant to promote the dispersion stability of the ink.

[0016] According to some preferred implementation aspects of the present invention, the drying is carried out by supercritical CO2 drying, the drying temperature is 30-40°C, the pressure is 8-16MPa, the drying time is 60-70min, and after the reaction is completed, the valve is opened to discharge the carbon dioxide fluid containing the organic solvent. The use of supercritical CO2 drying can protect the integrity of the original solvent system structure during the drying process and discharge the organic solvent; while the use of freeze drying will destroy the original system structure.

[0017] According to some preferred implementation aspects of the present invention, the organic solvent is 96-98.5% by mass of acetic acid; the surfactant is fatty alcohol polyoxyethylene ether and / or octylphenol polyoxyethylene ether; and the pH regulator is sodium acetate and / or citric acid.

[0018] In some preferred embodiments of the present invention, the method for preparing the chitin / anthocyanin indicator ink specifically comprises the following steps:

[0019] (1) Chitin is added to an organic solvent, mechanically stirred for 30-40 minutes, and then anthocyanin is added and stirred for 10-20 minutes to obtain an active ink.

[0020] (2) Drying the active ink and removing the organic solvent, grinding the dried ink into powder, the grinding time is 10-20 minutes.

[0021] (3) The surfactant, pH adjuster, deionized water and ink are mixed and stirred for 30-40 minutes until fully mixed to prepare chitin / anthocyanin indicator ink.

[0022] The stirring speed in step (1) and step (3) is 300-450 r / s. The grinding speed in step (2) is 400-550 r / s, and the particle size of the toner after grinding is less than 350 nm. The viscosity of the chitin / anthocyanin aqueous indicator ink finally prepared is 2-6 mPa.s (20° C.).

[0023] The present invention also provides a chitin / anthocyanin indicator ink prepared by the above-mentioned preparation method.

[0024] The present invention also provides a method for preparing an indicating material, comprising the following steps:

[0025] The ink is transferred to the nanofiber net by cold transfer printing, and then compounded with the nanofiber film to prepare the indicating material;

[0026] The ink is the chitin / anthocyanin indicator ink prepared by the preparation method described above.

[0027] According to some preferred embodiments of the present invention, the nanofiber web is a polycaprolactone nanofiber web; the nanofiber film is a ramie nanofiber film. The polycaprolactone nanofiber web is the contact surface with food, and polycaprolactone is degradable and more environmentally friendly; the ramie nanofiber film is the barrier surface.

[0028] According to some preferred embodiments of the present invention, the polycaprolactone nanofiber web is formed by overlapping and laying polycaprolactone fibers with a thickness of 4-8 μm. The polycaprolactone fibers are produced by blow-spinning with a spinning solution concentration of 18-32% and a fiber diameter of 200-700 nm.

[0029] According to some preferred embodiments of the present invention, the apocynum venetum nanocellulose fiber film is a translucent film with a light transmittance of 70-80%. It is made of apocynum venetum nanocellulose fibers by wet web forming technology, has a thickness of 80-100 μm, has a spinning solution concentration of 15-25%, and a fiber diameter of 50-180 nm.

[0030] In some preferred embodiments of the present invention, the method for preparing the indicator material specifically comprises the following steps:

[0031] (1) A release agent is coated on a cold transfer printing substrate, and then the chitin / anthocyanin indicator ink is printed on the substrate having the coating according to a predetermined pattern using a digital printer.

[0032] (2) The substrate with the ink pattern and the polycaprolactone nanofiber web are sent into a cold transfer printing machine, and after being sealed, they are transferred by the cold transfer printing machine to obtain a printed fabric.

[0033] (3) The printed fabric is fixed by steaming at 35-45°C for 2-3 hours to obtain a semi-finished printed fabric.

[0034] (4) The printed surface of the semi-finished printed fabric is laminated with the apocynum venetum nanocellulose fiber film and combined together by thermal bonding to obtain a finished printed fabric with a freshness-keeping indicator function, i.e., an indicator material.

[0035] The cold transfer printing substrate in step (1) is PBAT with a thickness of 200-300 μm. During the transfer process in step (2), the transfer roller pressure is 5×10 3 -8×10 3 Pa. The thermal bonding in step (4) is performed at 40-45°C.

[0036] The present invention also provides an indicating material prepared by the above preparation method.

[0037] Due to the adoption of the above technical scheme, compared with the prior art, the advantages of the present invention are: the preparation method of the chitin / anthocyanin indicator ink of the present invention uses anthocyanin as a pH response material, and chitin and other environmentally friendly materials are added. The prepared aqueous ink will not cause pollution by solvent volatilization during the production process, and is non-toxic and harmless to food and human body; a degradable substrate and a fabric to be transferred are used during the cold transfer printing operation, and the prepared transfer printing fabric product can be used to detect the freshness and corruption degree of food, and has good application prospects in the field of food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0039] Figure 1 It is a schematic diagram of the structure of the indicating material in a specific embodiment of the present invention;

[0040] Among them, 1 is a polycaprolactone nanofiber web, 2 is a sample printed pattern, and 3 is a rhubarb nanofiber film. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0042] In one aspect, the present invention provides a chitin / anthocyanidin indicator ink and a preparation method thereof. The preparation method of the chitin / anthocyanidin indicator ink comprises the following steps:

[0043] Step 1), prepare active ink

[0044] Add chitin to an organic solvent, stir mechanically for 30-40 minutes, then add anthocyanin, stir for 10-20 minutes to obtain active ink. The organic solvent is 96-98.5% acetic acid. The deacetylation degree of chitin is 25-30%. The mass ratio of chitin to anthocyanin is 1:4-5.

[0045] Step 2), preparing toner

[0046] The active ink is dried and ground into powder, the grinding time being 10-20 minutes.

[0047] The drying is carried out by supercritical CO2 drying, the drying temperature is 30-40°C, the pressure is 8-16MPa, the drying time is 60-70min, and after the reaction is completed, the valve is opened to discharge the carbon dioxide fluid containing the organic solvent.

[0048] Step 3), preparing chitin / anthocyanin indicator ink

[0049] The surfactant, pH regulator, deionized water and ink powder are mixed, stirred for 30-40 minutes until fully mixed, and the pH is adjusted to 6-6.5 to prepare chitin / anthocyanin indicator ink.

[0050] The surfactant is fatty alcohol polyoxyethylene ether and / or octylphenol polyoxyethylene ether; and the pH regulator is sodium acetate and / or citric acid.

[0051] The mass proportion of chitin in the chitin / anthocyanin indicator ink is 5-8%; the mass proportion of anthocyanin is 20-25%.

[0052] Preferably, based on 100 parts by weight, the chitin / anthocyanin indicator ink includes 20-25 parts of anthocyanin, 5-8 parts of chitin, 0.1-3 parts of surfactant, 0.1-5 parts of pH regulator, and the balance is deionized water.

[0053] The stirring speed in step (1) and step (3) is 300-450 r / s. The grinding speed in step (2) is 400-550 r / s, and the particle size of the toner after grinding is less than 350 nm. The viscosity of the chitin / anthocyanin aqueous indicator ink finally prepared is 2-6 mPa.s (20° C.).

[0054] Another aspect of the present invention provides a freshness-keeping indicator material based on the chitin / anthocyanin indicator ink and a preparation method thereof. The preparation method of the indicator material specifically comprises the following steps:

[0055] Step 1), coating the release agent on the cold transfer printing substrate, and then using a digital printer to print the chitin / anthocyanin indicator ink on the substrate with the coating according to a predetermined pattern.

[0056] Among them, the cold transfer printing substrate is PBAT with a thickness of 200-300μm.

[0057] Step 2), the substrate with the ink pattern and the polycaprolactone nanofiber web are sent to a cold transfer printing machine, and after being sealed, the cold transfer printing machine is used for transfer printing to obtain a printed fabric. During the transfer process, the transfer roller pressure is 5×10 3 -8×10 3 Pa.

[0058] The polycaprolactone nanofiber web is formed by overlapping and laying polycaprolactone fibers, with a thickness of 4-8 μm. The polycaprolactone fibers are made by blow-spinning, with a spinning solution concentration of 18-32% and a fiber diameter of 200-700 nm.

[0059] Step 3), the printed fabric is steamed and fixed at 35-45° C. for 2-3 hours to obtain a semi-finished printed fabric.

[0060] Step 4), the printed surface of the semi-finished printed fabric is laminated with the apocynum venetum nanocellulose fiber film, and they are combined together by thermal bonding at 40-45° C. to obtain a finished printed fabric with a freshness indication function, namely, an indication material.

[0061] The apocynum venetum nanocellulose fiber film is a semi-transparent film with a light transmittance of 70-80%. It is made from apocynum venetum nanocellulose fibers by wet web forming technology, has a thickness of 80-100 μm, apocynum venetum nanocellulose fiber spinning solution concentration of 15-25%, and a fiber diameter of 50-180 nm.

[0062] The anthocyanins used in the following examples were purchased from Xi'an Best Biotechnology Co., Ltd. (item number BH0031), the chitin used was purchased from Xi'an Zelon Biotechnology Co., Ltd. (item number 20222554), the acetic acid used was purchased from Jiangsu Yiheyuan Biotechnology Co., Ltd., the fatty alcohol polyoxyethylene ether used was purchased from Zhengzhou Xiangdong Chemical Products Co., Ltd. (model AEO-9), and the sodium acetate used was purchased from Anhui Xinrun Biotechnology Co., Ltd. (item number CSN001).

[0063] Example 1

[0064] Based on 100 parts by weight, the chitin / anthocyanin indicator ink in this embodiment is composed of 25 parts of anthocyanin, 6 parts of chitin, 0.5 parts of surfactant, 0.2 parts of pH regulator, and the balance of deionized water.

[0065] The deacetylation degree of the chitin is 25%; the organic solvent is acetic acid solution, and its mass fraction is 98.5%; the surfactant is fatty alcohol polyoxyethylene ether; and the pH regulator is sodium acetate.

[0066] The method for preparing chitin / anthocyanin indicator ink comprises the following steps:

[0067] Step (1), adding chitin to an organic solvent, mechanically stirring for 35 minutes, then adding anthocyanin, stirring for 15 minutes, to obtain active ink.

[0068] Step (2), drying the active ink obtained in step (1) and removing the organic solvent, grinding the dried ink into powder, grinding time is 12 minutes, grinding speed is 550r / s, and the particle size of the toner after grinding is 200-250nm. Drying is supercritical CO2 drying, drying temperature is 35°C, pressure is 16MPa, and drying time is 60min.

[0069] Step (3), stirring the surfactant, pH adjuster, deionized water and the toner obtained by grinding in step (2) for 30 minutes until fully mixed, and adjusting the pH to 6 to obtain a chitin / anthocyanin indicator.

[0070] Wherein, in step (1) and step (3), the speed of blending and stirring the solution is 450 r / s.

[0071] The preparation method of the indicating material in this embodiment comprises the following steps:

[0072] (1) Coating a release agent on a cold transfer printing substrate, and then using a digital printer to print the chitin / anthocyanin indicator ink onto the coating substrate according to a predetermined pattern. The cold transfer printing substrate is PBAT with a thickness of 300 μm.

[0073] (2) The substrate and the polycaprolactone nanofiber web are sent to a cold transfer printing machine, and after being sealed, the cold transfer printing machine transfers the printed fabric to obtain an initial printed fabric. During the transfer process, the transfer roller pressure is 6×10 3 Pa.

[0074] The polycaprolactone nanofiber web is formed by overlapping and laying polycaprolactone fibers, and has a thickness of 6 μm. The polycaprolactone fibers are produced by blow-spinning, and the spinning solution concentration is 25%, and the fiber diameter is 500 nm.

[0075] (3) The printed fabric was fixed by steaming at 40°C for 3 hours to obtain the initial printed fabric product.

[0076] (4) The printed surface of the initial printed fabric is laminated with the apocynum venetum nanocellulose fiber film and combined together by thermal bonding at 40° C. to obtain a finished printed fabric with a freshness indication function.

[0077] The apocynum venetum nanocellulose fiber film is made of apocynum venetum nanocellulose fibers by wet web forming technology, has a thickness of 90 μm, a spinning solution concentration of 18%, and a fiber diameter of 130 nm. The prepared apocynum venetum nanocellulose film is a semi-transparent film with a light transmittance of 80%.

[0078] Example 2

[0079] Based on 100 parts by weight, the chitin / anthocyanin indicator ink in this embodiment is composed of 20 parts of anthocyanin, 5 parts of chitin, 0.5 parts of surfactant, 0.2 parts of pH regulator, and the balance of deionized water.

[0080] The deacetylation degree of the chitin is 20%; the organic solvent is acetic acid solution, and its mass fraction is 98.5%; the surfactant is fatty alcohol polyoxyethylene ether; and the pH regulator is sodium acetate.

[0081] The method for preparing chitin / anthocyanin indicator ink comprises the following steps:

[0082] Step (1), adding chitin to an organic solvent, mechanically stirring for 40 minutes, then adding anthocyanin, stirring for 10 minutes, to obtain active ink.

[0083] Step (2), drying the active ink obtained in step (1) and removing the organic solvent, grinding the dried ink into powder, grinding time is 12 minutes, grinding speed is 550r / s, and the particle size of the toner after grinding is 200-250nm. Drying is supercritical CO2 drying, drying temperature is 35°C, pressure is 16MPa, and drying time is 60min.

[0084] Step (3), stirring the surfactant, pH adjuster, deionized water and the toner obtained by grinding in step (2) for 30 minutes until fully mixed, and adjusting the pH to 6.5 to obtain a chitin / anthocyanin indicator.

[0085] Wherein, in step (1) and step (3), the speed of blending and stirring the solution is 450 r / s.

[0086] The preparation method of the indicating material in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0087] Comparative Example 1

[0088] The difference between the chitin / anthocyanidin indicator ink of this comparative example and Example 1 is that the chitin / anthocyanidin indicator ink is ground into powder after freeze drying in the preparation step (2). The freeze drying requires vacuum, a temperature of -40°C, and a pressure of 10Pa. The remaining steps and parameters are basically the same as those of Example 1. Freeze drying will destroy the original system structure, resulting in problems with the performance of the final ink, and all indicators do not meet the requirements of printing ink.

[0089] Comparative Example 2

[0090] The difference between the indicator material of this comparative example and Example 1 is that the cold transfer printing substrate in the preparation step of the indicator material is a PP film. The remaining steps and parameters are basically the same as those in Example 1.

[0091] Comparative Example 3

[0092] The difference between the indicator material of this comparative example and Example 1 is that in the preparation step of the indicator material, a conventional transfer printing method is used, and the transfer temperature is 190° C. The remaining steps and parameters are basically the same as those of Example 1.

[0093] Comparative Example 4

[0094] The difference between the indicating material of this comparative example and Example 1 is that in the preparation step of the indicating material Electrospinning Preparation of nanofiber freshness indicator film by silk method The nanofiber freshness indicator film was prepared by electrospinning, wherein the spinning solution was mixed with 25 parts of anthocyanin, 6 parts of chitin and 98.5% of acetic acid, an organic solvent, the electrospinning voltage was 8 kV, and the propulsion pump flow rate was 1.2 mL / h. The remaining steps and parameters were basically the same as those in Example 1.

[0095] In Comparative Example 4, due to the requirement of spinning solution concentration, the anthocyanin content should not be too high, the prepared fiber membrane has weak indication function, the fiber is thicker, and the elongation at break is poor.

[0096] Performance Study

[0097] 1) The viscosity, conductivity, pH value (25°C), and surface tension of the chitin / anthocyanin indicator ink obtained in Examples 1-2 and Comparative Example 1 were tested respectively. The test standards for each index are as follows: viscosity index: GB / T22235-2008 (20°C); conductivity index: SL78-1994; pH value (25°C) index: GB / T9724-2007; surface tension index: GB / T22237-2008. The performance test parameters are shown in Table 1 below:

[0098] Table 1 Test results

[0099] Viscosity / mpa·s <![CDATA[Conductivity / ms·cm -1 > pH value (20℃) <![CDATA[Surface tension / mN·m -1 > Example 1 3.5 2.9 5.5 33.6 Example 2 2.8 3.3 6.1 35.4 Comparative Example 1 6.3 5.1 7.6 42.9

[0100] The results in Table 1 show that when the ratio of anthocyanin to chitin content decreases, the viscosity decreases, and the conductivity, pH value and surface tension increase; Comparative Example 1 adopts freeze-drying method, which destroys the system structure of the solvent. Compared with Example 1, the test results of several indicators have changed significantly, and each indicator does not meet the requirements of printing ink.

[0101] 2) Test the dry friction fastness, initial K / S value, and K / S value of the finished fabrics of Examples 1-2 and Comparative Examples 1-4 when the environmental pH is 9. Among them, the dry friction fastness test index is: GB / T3920-2008; the apparent color depth K / S determination method is: measured using Datacolor test color matching instrument, and the test conditions are: D 65 Light source, observation angle 10° (the darker the red light band, the smaller the value, the darker the blue light band, the larger the value). Test results are shown in Table 2:

[0102] Table 2 Test results

[0103] Dry rubbing fastness / grade Initial K / S value K / S value when environmental pH=9 Example 1 5 3.52 7.66 Example 2 5 3.89 7.32 Comparative Example 1 3 4.81 6.14 Comparative Example 2 4 4.21 6.76 Comparative Example 3 1 5.45 6.10 Comparative Example 4 2 4.99 6.45

[0104] The results in Table 2 show that the finished fabrics prepared in Examples 1-2 have better strength and stronger dry friction fastness; the finished fabrics prepared in Comparative Examples 1-4 show different degrees of decline in the dry friction fastness test. At the same time, the finished fabrics prepared in Examples 1-2 are more sensitive to changes in environmental pH, and the K / S value changes greatly, among which the finished fabric of Example 1 has a better response; the K / S value of the finished fabrics prepared in Comparative Examples 1-4 changes less, indicating that they are not sensitive to changes in external pH and are not sufficient to indicate the freshness of food.

[0105] The present invention provides an active printing ink applicable to cold transfer printing, which can be printed on degradable non-woven fabric packaging and has a food freshness indication function; at the same time, it has excellent mechanical properties and friction fastness, and has strong practical value. The indicator ink first disperses anthocyanin and chitin in an organic solvent to prepare an active ink, then undergoes supercritical CO2 drying and grinds the dried ink into powder, and blends it with a surfactant to prepare a chitin / anthocyanin indicator ink. When used, the indicator ink is printed on a substrate, and cold transfer printing is performed together with a polycaprolactone nanofiber web, and the obtained initial printed fabric is composited with apocynum nanofiber film to prepare a printed fabric product. The preparation method is simple and controllable, and is green and environmentally friendly; the prepared chitin / anthocyanin indicator ink can be applied to the intelligent packaging industry to detect changes in food pH, thereby indicating the freshness of the food.

[0106] Compared with the prior art, the present invention has the following beneficial effects:

[0107] 1. The chitin / anthocyanin indicator ink of the present invention uses anthocyanin as a pH response material and adds environmentally friendly materials such as chitin. The prepared aqueous ink will not volatilize the solvent during the production process to cause pollution, and is non-toxic and harmless to food and human body. A degradable substrate and a fabric to be transferred are used during the cold transfer printing operation. The prepared transfer printing fabric product can be used to detect the freshness and corruption degree of food, and has good application prospects in the field of food packaging.

[0108] 2. The present invention uses supercritical CO2 technology during the drying operation, which is a clean and energy-saving process, and protects the microstructure and physical and chemical properties of the chitin / anthocyanin indicator ink to a great extent. At the same time, particles with smaller particle size and uniform distribution can be obtained, thereby improving the use efficiency of anthocyanins.

[0109] 3. The printed fabric product (indicator material) prepared by the present invention is formed by thermally bonding a polycaprolactone nanofiber web and apocynum venetum nanocellulose film, and is more breathable than the existing fresh-keeping indicator film.

[0110] 4. The printed fabric product prepared in the present invention can effectively improve its friction resistance and enhance the mechanical properties of the fabric by using two layers of nanofibers to wrap the print with indication function. The existing nanofibers directly blended with anthocyanins and prepared by electrospinning have low concentrations, coarse fibers, weak pH indication function, and are easy to break. Compared with them, the present invention has more outstanding advantages in practicality, can quickly undergo a color change reaction, and has excellent elongation at break.

[0111] The above embodiments prepared by the method of the present invention are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing chitin / anthocyanin indicator ink, characterized in that: The steps include: Add chitin to an organic solvent, mix well, add anthocyanin, continue mixing, and obtain active ink; The active ink is dried and the organic solvent is removed, and then crushed into powder to obtain toner; Mixing the surfactant, pH regulator, deionized water and the ink powder evenly to obtain the chitin / anthocyanin indicator ink; The mass ratio of chitin to anthocyanin is 1:4-5; The drying is carried out by supercritical CO2 drying, the drying temperature is 30-40°C, and the pressure is 8-16MPa.

2. The preparation method according to claim 1, characterized in that: The deacetylation degree of the chitin is 25-30%.

3. The preparation method according to claim 1, characterized in that: The mass proportion of chitin in the chitin / anthocyanin indicator ink is 5-8%; the mass proportion of anthocyanin is 20-25%.

4. The preparation method according to claim 1, characterized in that: The organic solvent is acetic acid; the surfactant is fatty alcohol polyoxyethylene ether and / or octylphenol polyoxyethylene ether; and the pH regulator is sodium acetate and / or citric acid.

5. A chitin / anthocyanin indicator ink prepared by the preparation method according to any one of claims 1 to 4.

6. A method for preparing an indicating material, characterized in that: The steps include: The ink is transferred to the nanofiber net by cold transfer printing, and then compounded with the nanofiber film to prepare the indicating material; The ink is a chitin / anthocyanin indicator ink prepared by the preparation method according to any one of claims 1 to 4; The nanofiber net is a polycaprolactone nanofiber net; the nanofiber film is a rhubarb nanofiber film.

7. An indicating material prepared by the preparation method according to claim 6.

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