A preparation method of pH indicator label based on hematoxylin as indicator dye

Abstract

The invention belongs to the field of preparation of pH indicator labels, and discloses a preparation method of a pH indicator label based on hematoxylin as an indicator dye, which specifically comprises the following steps: step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, and then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution; step 2, adding hematoxylin powder, propylene glycol and glycerol to the spinning solution, stirring evenly with a magnetic force at room temperature, standing to defoam, and obtaining a spinning solution; step 3, electrostatically spinning the spinning solution to obtain a pH indicator label; the present application uses hematoxylin that can detect volatile amine substances as an indicator dye to prepare a pH indicator label, so as to help consumers understand food quality information more intuitively, and has more advantages than traditional detection methods, with relatively low cost and convenient operation.

Description

Technical Field

[0001] The invention belongs to the field of preparation of pH indicator labels, and in particular relates to a preparation method of a pH indicator label based on hematoxylin as an indicator dye. Background Art

[0002] Meat products are an important part of people's daily diet. They are not only delicious, but also rich in nutrients and play an important role in human health. Compared with conventional meat, aquatic products are deeply loved by consumers because they contain lower fat and calorie density and higher quality protein.

[0003] During the storage and transportation of aquatic products, the quality of the meat is prone to change. Traditional food freshness testing methods need to be carried out in special laboratories, which are complicated to operate and have low efficiency. Food spoilage has a strong timeliness, so it is impossible to accurately judge the freshness of food. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a pH indicator label based on hematoxylin as an indicator dye.

[0005] The present invention adopts the following technical solution:

[0006] A method for preparing a pH indicator label based on hematoxylin as an indicator dye, specifically comprising the following steps:

[0007] Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution;

[0008] Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution;

[0009] Step 3, extracting the spinning solution with a syringe, spinning continuously for 6 hours at a temperature of 30° C., setting the voltage to -2.5 kV and 13 kV, the advancing speed to 0.25 mm / min, the receiving distance to 20 cm, and the receiving roller speed to 100 r / min, to obtain the pH indicator label;

[0010] In the step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone and modified silicone oil is 3.5-4.5:1:2:2.5-3.5, the volume fraction of dilute acetic acid is 70%, and the polymer concentration of the spinning solution is 2-4%;

[0011] In the step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:40-50ml, the addition ratio of propylene glycol to spinning solution is 1ml:90-110ml, and the addition ratio of glycerol to spinning solution is 1ml:110-130ml.

[0012] Preferably, the modification method of the modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyldimethoxysilane, allyl epoxy-terminated polyether, catalyst, and methacrylic polyoxyethylene ether to a reaction kettle in sequence, stirring evenly, heating to 140° C. under nitrogen protection, reacting at a constant temperature for 3 hours, and then distilling under reduced pressure to remove small molecular weight low-boiling substances to obtain the modified silicone oil.

[0013] Preferably, the molar ratio of the hydrogen-containing silicone oil to the allyl epoxy-terminated polyether is 1:0.8-1.2, and the molar ratio of the hydrogen-containing silicone oil to the methacrylic polyoxyethylene ether is 1:0.4-0.5.

[0014] Preferably, the added amount of the γ-aminopropyldimethoxysilane is 600-800 ppm of the mass of the hydrogen-containing silicone oil, and the added amount of the catalyst is 400-500 ppm of the mass of the hydrogen-containing silicone oil.

[0015] Preferably, the allyl epoxy-terminated polyether is active allyl epoxy-terminated polyether KL-91B produced by Liaoning Kelong Fine Chemical Co., Ltd.

[0016] Preferably, the catalyst is a porous ceramic-supported platinum catalyst.

[0017] Preferably, the preparation method of the porous ceramic-supported platinum catalyst is as follows: a tetramethyldivinyldisiloxane chloroplatinate solution is uniformly sprayed on the porous cordierite ceramic, and after natural drying, the operation is repeated 2-3 times, and then vacuum drying is performed to obtain the porous ceramic-supported platinum catalyst.

[0018] Preferably, the spraying amount of the tetramethyldivinyldisiloxane chloroplatinate solution is 18-22% of the mass of the porous cordierite ceramic.

[0019] Preferably, the vacuum drying conditions are 80-150° C. and 0.08-0.096 MPa.

[0020] From the above description of the present invention, it can be seen that compared with the prior art, the beneficial effects of the present invention are as follows: the present application uses hematoxylin pigments that can detect volatile amine substances as indicator dyes to prepare pH indicator labels to help consumers understand food quality information more intuitively, which is more advantageous than traditional detection methods, with relatively low cost and convenient operation, and the freshness of aquatic products can be directly monitored by observing the color change of the pH indicator label with the naked eye. Putting it into the market for application will bring great convenience to consumers, while also reducing food waste and reducing food safety risks, and to a certain extent promoting the development of the field of smart packaging materials; wherein, polyvinyl pyrrolidone and modified silicone oil are introduced into the spinning solution, and combined with other raw materials, the surface defects of the prepared pH indicator label can be reduced, and the damage of water vapor and solvent to the pH indicator label can be reduced, and the stability of the prepared pH indicator label can be increased; in addition, propylene glycol and glycerin are introduced to cooperate with hematoxylin pigment powder, so that the hematoxylin pigment powder is uniformly infiltrated into the spinning solution to form a spinning solution, ensuring the overall uniformity of the prepared pH indicator label, and thus ensuring the accuracy of the test results;

[0021] The modification method of modified silicone oil is specifically limited, and γ-aminopropyldimethoxysilane, allyl epoxy-terminated polyether and methyl methacrylate polyoxyethylene ether are introduced as modifiers, and the hydrogen-containing silicone oil is modified in combination with a catalyst, so that the obtained modified silicone oil can reduce the defects on the surface of the fiber membrane obtained by spinning and enhance the stability during the pH indicator label detection process. DETAILED DESCRIPTION

[0022] The present invention is further described below through specific implementation modes.

[0023] A method for preparing a pH indicator label based on hematoxylin as an indicator dye, specifically comprising the following steps:

[0024] Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution;

[0025] Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution;

[0026] Step 3, extract the spinning solution with a syringe, and continuously spin for 6 hours at a temperature of 30°C, set voltages of -2.5 kV and 13 kV, a propulsion speed of 0.25 mm / min, a receiving distance of 20 cm, and a receiving roller speed of 100 r / min to obtain the pH indicator label.

[0027] Wherein, in step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone and modified silicone oil is 3.5-4.5:1:2:2.5-3.5, the volume fraction of dilute acetic acid is 70%, and the polymer concentration of the spinning solution is 2-4%;

[0028] In step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:40-50ml, the addition ratio of propylene glycol to spinning solution is 1ml:90-110ml, and the addition ratio of glycerol to spinning solution is 1ml:110-130ml.

[0029] The modification method of modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyl dimethoxysilane, allyl epoxy-terminated polyether, porous ceramic-supported platinum catalyst, and methyl propylene polyoxyethylene ether into a reaction kettle in sequence, stirring evenly, heating to 140° C. under nitrogen protection, reacting at a constant temperature for 3 hours, and then removing small molecular low-boiling substances by reduced pressure distillation to obtain modified silicone oil; wherein, the feeding molar ratio of hydrogen-containing silicone oil to allyl epoxy-terminated polyether is 1:0.8-1.2, the feeding molar ratio of hydrogen-containing silicone oil to methyl propylene polyoxyethylene ether is 1:0.4-0.5, the addition amount of γ-aminopropyl dimethoxysilane is 600-800ppm of the mass of hydrogen-containing silicone oil, and the addition amount of catalyst is 400-500ppm of the mass of hydrogen-containing silicone oil; specifically, the allyl epoxy-terminated polyether is the active allyl epoxy-terminated polyether KL-91B produced by Liaoning Kelong Fine Chemical Co., Ltd.

[0030] The preparation method of porous ceramic-supported platinum catalyst is as follows: 10000ppm tetramethyl divinyl disiloxane chloroplatinate solution is evenly sprayed on porous cordierite ceramic, and after natural drying, the operation is repeated 2-3 times, and then vacuum drying is performed to obtain porous ceramic-supported platinum catalyst; wherein the spraying amount of tetramethyl divinyl disiloxane chloroplatinate solution is 18-22% of the mass of the porous cordierite ceramic; the vacuum drying conditions are 80-150°C and 0.08-0.096MPa. Example 1

[0031] A method for preparing a pH indicator label based on hematoxylin as an indicator dye, specifically comprising the following steps:

[0032] Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution;

[0033] Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution;

[0034] Step 3, extract the spinning solution with a syringe, and continuously spin for 6 hours at a temperature of 30°C, set voltages of -2.5 kV and 13 kV, a propulsion speed of 0.25 mm / min, a receiving distance of 20 cm, and a receiving roller speed of 100 r / min to obtain the pH indicator label.

[0035] Wherein, in step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone and modified silicone oil is 3.5:1:2:3.5, and the polymer concentration of the spinning solution is 2%.

[0036] In step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:40ml, the addition ratio of propylene glycol to spinning solution is 1ml:90ml, and the addition ratio of glycerol to spinning solution is 1ml:130ml.

[0037] The modification method of modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyl dimethoxysilane, allyl epoxy-terminated polyether, porous ceramic-supported platinum catalyst, and methyl propylene polyoxyethylene ether into a reaction kettle in sequence, stirring evenly, heating to 140°C under nitrogen protection, reacting at a constant temperature for 3 hours, and then removing small molecular low-boiling substances by reduced pressure distillation to obtain modified silicone oil; wherein, the molar ratio of hydrogen-containing silicone oil to allyl epoxy-terminated polyether is 1:0.8, the molar ratio of hydrogen-containing silicone oil to methyl propylene polyoxyethylene ether is 1:0.4, the amount of γ-aminopropyl dimethoxysilane added is 600ppm of the mass of hydrogen-containing silicone oil, and the amount of catalyst added is 500ppm of the mass of hydrogen-containing silicone oil.

[0038] The preparation method of porous ceramic-supported platinum catalyst is as follows: 10000ppm tetramethyl divinyl disiloxane chloroplatinate solution is evenly sprayed on the porous cordierite ceramic, and after natural drying, the operation is repeated twice, and then vacuum drying is performed to obtain a porous ceramic-supported platinum catalyst; wherein the spraying amount of tetramethyl divinyl disiloxane chloroplatinate solution is 22% of the mass of the porous cordierite ceramic; the vacuum drying conditions are 80°C and 0.096MPa. Example 2

[0039] A method for preparing a pH indicator label based on hematoxylin as an indicator dye, specifically comprising the following steps:

[0040] Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution;

[0041] Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution;

[0042] Step 3, extract the spinning solution with a syringe, and continuously spin for 6 hours at a temperature of 30°C, set voltages of -2.5 kV and 13 kV, a propulsion speed of 0.25 mm / min, a receiving distance of 20 cm, and a receiving roller speed of 100 r / min to obtain the pH indicator label.

[0043] Wherein, in step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone, and modified silicone oil is 4.5:1:2:2.5, and the polymer concentration of the spinning solution is 4%;

[0044] In step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:40ml, the addition ratio of propylene glycol to spinning solution is 1ml:90ml, and the addition ratio of glycerol to spinning solution is 1ml:130ml.

[0045] The modification method of modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyl dimethoxysilane, allyl epoxy-terminated polyether, porous ceramic-supported platinum catalyst, and methyl propylene polyoxyethylene ether into a reaction kettle in sequence, stirring evenly, heating to 140°C under nitrogen protection, reacting at a constant temperature for 3 hours, and then removing small molecular low-boiling substances by reduced pressure distillation to obtain modified silicone oil; wherein, the molar ratio of hydrogen-containing silicone oil to allyl epoxy-terminated polyether is 1:1.2, the molar ratio of hydrogen-containing silicone oil to methyl propylene polyoxyethylene ether is 1:0.5, the amount of γ-aminopropyl dimethoxysilane added is 800ppm of the mass of hydrogen-containing silicone oil, and the amount of catalyst added is 400ppm of the mass of hydrogen-containing silicone oil.

[0046] The preparation method of porous ceramic-supported platinum catalyst is as follows: 10000ppm tetramethyl divinyl disiloxane chloroplatinate solution is evenly sprayed on the porous cordierite ceramic, and after natural drying, the operation is repeated 3 times, and then vacuum drying is performed to obtain a porous ceramic-supported platinum catalyst; wherein the spraying amount of the tetramethyl divinyl disiloxane chloroplatinate solution is 18% of the mass of the porous cordierite ceramic; the vacuum drying conditions are 150°C and 0.08MPa. Example 3

[0047] A method for preparing a pH indicator label based on hematoxylin as an indicator dye, specifically comprising the following steps:

[0048] Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution;

[0049] Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution;

[0050] Step 3, extract the spinning solution with a syringe, and continuously spin for 6 hours at a temperature of 30°C, set voltages of -2.5 kV and 13 kV, a propulsion speed of 0.25 mm / min, a receiving distance of 20 cm, and a receiving roller speed of 100 r / min to obtain the pH indicator label.

[0051] Wherein, in step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone and modified silicone oil is 4:1:2:3, and the polymer concentration of the spinning solution is 3%;

[0052] In step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:45ml, the addition ratio of propylene glycol to spinning solution is 1ml:100ml, and the addition ratio of glycerol to spinning solution is 1ml:120ml.

[0053] The modification method of modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyl dimethoxysilane, allyl epoxy-terminated polyether, porous ceramic-supported platinum catalyst, and methyl propylene polyoxyethylene ether into a reaction kettle in sequence, stirring evenly, heating to 140°C under nitrogen protection, reacting at a constant temperature for 3 hours, and then removing small molecular low-boiling substances by reduced pressure distillation to obtain modified silicone oil; wherein, the molar ratio of hydrogen-containing silicone oil to allyl epoxy-terminated polyether is 1:1.0, the molar ratio of hydrogen-containing silicone oil to methyl propylene polyoxyethylene ether is 1:0.45, the amount of γ-aminopropyl dimethoxysilane added is 700ppm of the mass of hydrogen-containing silicone oil, and the amount of catalyst added is 450ppm of the mass of hydrogen-containing silicone oil.

[0054] The preparation method of porous ceramic-supported platinum catalyst is as follows: 10000ppm tetramethyl divinyl disiloxane chloroplatinate solution is evenly sprayed on the porous cordierite ceramic, and after natural drying, the operation is repeated twice, and then vacuum drying is performed to obtain a porous ceramic-supported platinum catalyst; wherein the spraying amount of the tetramethyl divinyl disiloxane chloroplatinate solution is 20% of the mass of the porous cordierite ceramic; and the vacuum drying conditions are 120°C and 0.088MPa.

[0055] The present application uses hematoxylin which can detect volatile amine substances as an indicator dye to prepare pH indicator labels, so as to help consumers understand food quality information more intuitively. Compared with traditional detection methods, it has more advantages, such as relatively low cost and convenient operation. Moreover, the freshness of aquatic products can be directly monitored by observing the color change of the pH indicator label with the naked eye. Putting it into market application will bring great convenience to consumers, and at the same time can also reduce food waste and reduce food safety risks, and to a certain extent promote the development of the field of smart packaging materials. Among them, polyvinyl pyrrolidone and modified silicone oil are introduced into the spinning solution, and combined with other raw materials, the defects on the surface of the prepared pH indicator label can be reduced, and the damage of water vapor and solvent to the pH indicator label can be reduced, and the stability of the prepared pH indicator label can be increased. In addition, propylene glycol and glycerin are introduced to cooperate with hematoxylin powder, so that the hematoxylin powder is evenly infiltrated into the spinning solution to form a spinning solution, thereby ensuring the overall uniformity of the prepared pH indicator label and thus ensuring the accuracy of the test results.

[0056] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the specification should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for preparing a pH indicator label based on hematoxylin as an indicator dye, characterized in that: The specific steps include: Step 1, first dissolving chitosan and polyethylene oxide powder in dilute acetic acid, then adding polyvinyl pyrrolidone and modified silicone oil to prepare a spinning solution; Step 2, adding hematoxylin powder, propylene glycol and glycerin to the spinning solution, stirring evenly with magnetic force at room temperature, standing to defoam, and obtaining the spinning solution; Step 3, extracting the spinning solution with a syringe, spinning continuously for 6 hours at a temperature of 30° C., setting the voltage to -2.5 kV and 13 kV, the advancing speed to 0.25 mm / min, the receiving distance to 20 cm, and the receiving roller speed to 100 r / min, to obtain the pH indicator label; In the step 1, the mass ratio of chitosan, polyethylene oxide powder, polyvinyl pyrrolidone and modified silicone oil is 3.5-4.5:1:2:2.5-3.5, the volume fraction of dilute acetic acid is 70%, and the polymer concentration of the spinning solution is 2-4%; In the step 2, the addition ratio of hematoxylin pigment powder to spinning solution is 1g:40-50ml, the addition ratio of propylene glycol to spinning solution is 1ml:90-110ml, and the addition ratio of glycerol to spinning solution is 1ml:110-130ml; The modification method of the modified silicone oil comprises: adding hydrogen-containing silicone oil, γ-aminopropyldimethoxysilane, allyl epoxy-terminated polyether, catalyst, and methacrylic polyoxyethylene ether to a reaction kettle in sequence, stirring evenly, heating to 140° C. under nitrogen protection, reacting at a constant temperature for 3 hours, and then removing small molecular weight low-boiling substances by reduced pressure distillation to obtain the modified silicone oil; The molar ratio of the hydrogen-containing silicone oil to the allyl epoxy-terminated polyether is 1:0.8-1.2, and the molar ratio of the hydrogen-containing silicone oil to the methacrylic polyoxyethylene ether is 1:0.4-0.5; The added amount of the γ-aminopropyldimethoxysilane is 600-800ppm of the mass of the hydrogen-containing silicone oil, and the added amount of the catalyst is 400-500ppm of the mass of the hydrogen-containing silicone oil.

2. The method for preparing a pH indicator label based on hematoxylin as an indicator dye according to claim 1, characterized in that: The allyl epoxy terminated polyether is the active allyl epoxy terminated polyether KL-91B produced by Liaoning Kelong Fine Chemical Co., Ltd.

3. The method for preparing a pH indicator label based on hematoxylin as an indicator dye according to claim 1, characterized in that: The catalyst is a porous ceramic-supported platinum catalyst.

4. The method for preparing a pH indicator label based on hematoxylin as an indicator dye according to claim 3, characterized in that: The preparation method of the porous ceramic-supported platinum catalyst is as follows: uniformly spraying a tetramethyldivinyldisiloxane chloroplatinate solution on the porous cordierite ceramic, drying it naturally, repeating the operation 2-3 times, and then vacuum drying to obtain the porous ceramic-supported platinum catalyst.

5. The method for preparing a pH indicator label based on hematoxylin as an indicator dye according to claim 4, characterized in that: The spraying amount of the tetramethyl divinyl disiloxane chloroplatinate solution is 18-22% of the mass of the porous cordierite ceramic.

6. The method for preparing a pH indicator label based on hematoxylin as an indicator dye according to claim 4, characterized in that: The conditions for vacuum drying are 80-150°C and 0.08-0.096MPa.