Process for dyeing natural polyurethane sponges based on medicinal plants

Abstract

This invention discloses a dyeing method for polyurethane sponges using natural colors derived from medicinal plants, relating to the field of polyurethane sponge dyeing technology. The dyeing steps are as follows: preparing raw materials; using a purification extraction method when extracting madder pigment, adding alum during the extraction process to avoid residue in the dye solution caused by adding alum during dyeing, thus removing impurities and achieving higher purity and environmental friendliness; controlling the dyeing temperature, time, and pH value. The advantages of this invention are: by utilizing madder-extracted pigments for natural dyeing of polyurethane sponges using medicinal plants, employing specific dye solution ratios and specific dyeing temperatures and times, the polyurethane achieves good coloring results and high color fastness; the dyed polyurethane sponges are environmentally friendly, safer to use, and have brighter and more vibrant colors; utilizing the reversible color change of the dyed sponge, it can be used in the medical field to indicate the healing status of wounds, and can also be used to monitor environmental conditions such as water quality and soil pH; it can be reused repeatedly without causing environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of polyurethane sponge dyeing technology, and more specifically to a dyeing method for natural-colored polyurethane sponges based on medicinal plants. Background Technology

[0002] Polyurethane foam is made by polymerizing and foaming isocyanates and hydroxyl compounds. Polyurethane foam products are characterized by uniform cell size and good gloss, and are widely used in high-end automotive interiors, high-end composite materials, printer consumables, filtration, and medical industries. Currently, most colored polyurethane foams use chemical dyes or pigments, some of which have carcinogenic or other safety concerns. With the improvement of living standards, people are paying more attention to quality of life and health, and have higher requirements for the safety of polyurethane foam products for human skin and health. People also have concerns about allergies and safety issues related to chemical dyes.

[0003] Currently, there is no literature on using natural dyes to color polyurethane foam. Generally, dyed polyurethane foam only has one color. In some specialized fields, such as the medical field, it is necessary to judge the healing progress of a user's injury by observing the color change of the foam during use. Existing dyed polyurethane foam cannot achieve this purpose, and its colorfastness is poor, easily fading. Therefore, there is a need to develop natural-colored polyurethane foam that can change color after dyeing, and is safe, harmless, and has high colorfastness. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a dyeing method for natural-colored polyurethane sponges based on medicinal plants, which can solve the problems of safety, poor color fastness and lack of color-changing properties after dyeing polyurethane sponges in the prior art.

[0005] To solve the above technical problems, the technical solution of the present invention includes the following steps: S1, preparing polyurethane sponge to be dyed, madder root, disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate, wherein disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate are all analytical grade.

[0006] S2. Extraction of madder pigment: First, add 10g of madder to an acidic solution with a pH of 1-2, soak and drain. Then, reflux the soaking solution and boil for 30-60 minutes. Filter to remove the filtrate. Add water to the residue to 100ml, reflux and boil for 30-60 minutes, filter, remove the residue, adjust the pH of the filtrate to neutral, add 1-2 g / L of alum, let stand at room temperature for 1-2 hours, evaporate the water using a rotary evaporator, and dry at 80℃. The acidic solution is selected from one of sulfuric acid aqueous solution, hydrochloric acid aqueous solution, nitric acid aqueous solution, or phosphoric acid aqueous solution, and the volume of the acidic solution is 100ml.

[0007] S3. Preparation of dyeing solution: Adjust the pH to 4-8 with disodium hydrogen phosphate dodecahydrate and citrate monohydrate buffer. Use madder pigment prepared in S2. The amount of madder pigment is 2-5% owf, and the bath ratio is 1:100.

[0008] S4. Dye the polyurethane sponge, controlling the dyeing temperature at 80℃-120℃, the dyeing time at 15min-30min, and the pH value at 4-8.

[0009] S5. Wash the dyed polyurethane sponge with water, and then wash it with soap.

[0010] S6. Wash and dry the polyurethane sponge after soaping.

[0011] Furthermore, in step S5, the water washing temperature of the polyurethane sponge is 40-50℃, and the water washing time is 20-30 minutes.

[0012] The soaping conditions are: 5g / L of neutral soap flakes, a liquor ratio of 1:50, a soaping temperature of 60℃, and a soaping time of 10 minutes, to remove surface color through soaping.

[0013] Furthermore, in step S6, after the polyurethane sponge is washed with water, it is first dehydrated and then dried. The drying temperature is 80-100℃ and the drying time is 5-10 minutes.

[0014] Furthermore, in step S4, the staining temperature is 110℃ and the staining time is 30min.

[0015] The advantages of this invention are: by using madder extract to dye polyurethane sponge with natural medicinal plant dyes, and by using a specific ratio of dye solution and a specific dyeing temperature and time, the polyurethane has a good coloring effect and high color fastness. Moreover, the dyed polyurethane sponge is environmentally friendly, safer to use, and has a brighter and more vibrant color.

[0016] The extraction of madder pigment uses a purification extraction method. Alum is added during the extraction process to avoid the presence of residual alum in the dye solution when adding alum during dyeing. This method can remove impurities, resulting in higher extraction purity and is more environmentally friendly.

[0017] Because madder pigment has reversible color-changing properties under different pH environments, the hue of polyurethane sponges dyed with madder extract pigment can change, showing yellow or red. In the medical field, the color change of the sponge can be used to judge the specific recovery status of the user's wound. It can also be used to monitor the environment such as water quality and soil acidity and alkalinity without causing environmental pollution. Attached Figure Description

[0018] Figure 1The graph shows the changes in wavelength and K / S value of madder pigment dyed on polyurethane sponges under different pH conditions in Examples 1-5 of the present invention.

[0019] Figure 2 The graph shows the changes in H, a, and b values ​​of polyurethane sponge dyed with madder pigment under different pH conditions in Examples 1-5 of the present invention. Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments will enable those skilled in the art to more fully understand this invention, but do not limit the invention to the scope of the described embodiments.

[0021] The specific implementation method adopts the following technical solution: The dyeing method of natural color polyurethane sponge based on medicinal plants includes the following steps: S1, preparing the polyurethane sponge to be dyed, madder root, disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate, wherein disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate are all analytical grade.

[0022] Instruments prepared: EL303 electronic balance (Mettler-Toledo Instruments (Shanghai) Co., Ltd.), Datacolor 650 computer colorimeter and colorimeter (Datacolor Trading Co., Ltd.), HH-S constant temperature water bath (Yuyao Testing Instrument Factory, Zhejiang Province), DHG-9423A electric thermostatic drying oven (Shanghai Jinghong Experimental Equipment Co., Ltd.), RJ-1108 infrared high temperature and high pressure dyeing machine (Nantong Sansi Electromechanical Technology Co., Ltd.).

[0023] S2. Extraction of madder pigment: First, add 10g of madder to an acidic solution with a pH of 1-2 and soak. Then, reflux the soaking solution and boil for 30-60 minutes. Filter to remove the filtrate. Add water to the residue to 100ml and reflux to boil for 30-60 minutes. Filter to remove the residue. Adjust the pH of the filtrate to neutral, add 1-2g / L of alum, let stand at room temperature for 1-2 hours, evaporate the water using a rotary evaporator, and dry at 80℃. The acidic solution is selected from one of sulfuric acid aqueous solution, hydrochloric acid aqueous solution, nitric acid aqueous solution, or phosphoric acid aqueous solution, and the volume of the acidic solution is 100ml.

[0024] S3. Preparation of dyeing solution: Adjust the pH to 4-8 with disodium hydrogen phosphate dodecahydrate and citrate monohydrate buffer. Use madder pigment prepared in S2. The amount of madder pigment is 2-5% owf, and the bath ratio is 1:100.

[0025] S4. Dye the polyurethane sponge, controlling the dyeing temperature at 80℃-120℃, the dyeing time at 15min-30min, and the pH value at 4-8.

[0026] S5. Wash the dyed polyurethane sponge with water, and then soap it. The water washing temperature of the polyurethane sponge is 40-50℃ and the water washing time is 20-30min. The soap washing conditions are: 5g / L of neutral soap flakes, liquor ratio of 1:50, soap washing temperature of 60℃, and soap washing time of 10min. The floating color is removed by soap washing.

[0027] S6. After soaping, the polyurethane sponge is washed and dried. After washing, it is first dehydrated and then dried. The drying temperature is 80-100℃ and the drying time is 5-10 minutes.

[0028] Example 1: S1. Prepare polyurethane sponge to be dyed, madder root, disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate. Disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate are all analytical grade. The size of the polyurethane sponge is 5cm×5cm×2cm.

[0029] S2. To extract madder pigment, first add 10g of madder to an acidic solution with a pH of 1-2, the acidic solution being an aqueous sulfuric acid solution, the amount of which is 100ml. After soaking, the soaking solution is refluxed and boiled for 30 minutes, filtered to remove the filtrate, water is added to the residue to 100ml, refluxed and boiled for 30 minutes, filtered, the residue is removed, the pH of the filtrate is adjusted to neutral, 1g / L of alum is added, and the mixture is allowed to stand at room temperature for 2 hours. The water is then evaporated using a rotary evaporator, and the mixture is dried at 80℃ to obtain the extracted madder pigment.

[0030] S3. Preparation of dyeing solution: Adjust the pH to 4 with disodium hydrogen phosphate dodecahydrate and citrate monohydrate buffer. Use madder pigment prepared in S2, with a dosage of 2% owf and a bath ratio of 1:100.

[0031] S4. Dye the polyurethane sponge, controlling the dyeing temperature at 110℃, the dyeing time at 30min, and the pH value at 4. The dyed sponge will be yellow.

[0032] S5. Wash the dyed polyurethane sponge with water, and then soap it. The water washing temperature of the polyurethane sponge is 50℃ and the water washing time is 30min. The soap washing conditions are: 5g / L of neutral soap flakes, liquor ratio of 1:50, soap washing temperature of 60℃ and soap washing time of 10min. The floating color is removed by soap washing.

[0033] S6. The polyurethane sponge after soaping is washed and dried. After washing, it is dehydrated and then dried. The drying temperature is 100℃ and the drying time is 10 minutes.

[0034] Example 2: This example is the same as Example 1 in other steps, except that the dyeing is carried out under the condition of controlling the pH value to 5.

[0035] Example 3: This example is the same as Example 1 in other steps, except that the dyeing is carried out under the condition of controlling the pH value to 6.

[0036] Example 4: This example is the same as Example 1 in other steps, except that the dyeing is carried out under the condition of controlling the pH value to 7.

[0037] Example 5: This example is the same as Example 1 in other steps, except that the dyeing is carried out under the condition of controlling the pH value to 8.

[0038] Color parameters of the polyurethane sponges dyed in Examples 1-5 were tested, and the effect of pH on the color parameters of the polyurethane sponges dyed with madder was analyzed. The effect of pH on the color parameters of the polyurethane sponges dyed with madder pigment is shown in Table 1.

[0039] Table 1. Effect of pH value on color parameters of polyurethane sponge dyed with madder pigment.

[0040]

[0041] Color parameter testing method: The color parameters of the dyed fabric are tested using a Datacolor colorimeter and the CIE (1976) L*a*b* standard colorimetric characterization system is adopted, including the K / S value at the maximum absorption wavelength λmax, the lightness L value (the larger the value, the brighter the color), the red-greenness a value (positive value represents red, negative value represents green), the yellow-blueness b value (positive value represents yellow, negative value represents blue), the saturation c value (the larger the value, the more vivid the color), and the hue h value (which can describe the color, such as reddish or greenish).

[0042] Table 1 shows that, under acidic conditions, the acidity of polyurethane sponges dyed with madder pigment increases as the pH value decreases, along with increases in brightness (L value) and K / S value, little change in value a, increases in value b, increases in value c, increases in vividness, and increases in hue angle (h value). The maximum wavelength is as follows: Figure 1 Between 420nm and 440nm, it exhibits a yellow chromatogram; when the pH value exceeds 7, with increasing pH, the brightness (L value) increases, the K / S value decreases, the a value increases, and the red light increases, resulting in a red color. The changes in a, b, and H values ​​are shown in the graph below. Figure 2 Therefore, by controlling the pH value of madder dye solution, polyurethane sponges with different yellow and red chromatograms can be obtained. Selecting pH=4, 7, and 8 respectively can yield better dyeing results.

[0043] Example 6: This example is the same as Example 1 in other steps, except that the staining temperature is controlled at 80°C.

[0044] Example 7: This example is the same as Example 1 in other steps, except that the staining temperature is controlled at 90°C.

[0045] Example 8: This example is the same as Example 1 in other steps, except that the staining temperature is controlled at 100°C.

[0046] Example 9: This example is the same as Example 1 in other steps, except that the staining temperature is controlled at 120°C.

[0047] Example 10: This example is the same as Example 4 in other steps, except that the staining temperature is controlled at 80°C.

[0048] Example 11: This example is the same as Example 4 in other steps, except that the staining temperature is controlled at 90°C.

[0049] Example 12: This example is the same as Example 4 in other steps, except that the staining temperature is controlled at 100°C.

[0050] Example 13: This example is the same as Example 4 in other steps, except that the staining temperature is controlled at 120°C.

[0051] Example 14: This example is the same as Example 5 in other steps, except that the staining temperature is controlled at 80°C.

[0052] Example 15: This example is the same as Example 5 in other steps, except that the staining temperature is controlled at 90°C.

[0053] Example 16: This example is the same as Example 5 in other steps, except that the staining temperature is controlled at 100°C.

[0054] Example 17: This example is the same as Example 5 in other steps, except that the staining temperature is controlled at 120°C.

[0055] The effects of temperature on the dyeing effect of madder pigment on polyurethane sponges in Examples 6-17 are shown in Table 2.

[0056] Table 2. Effect of temperature on the dyeing effect of madder pigment on polyurethane sponge

[0057]

[0058] As shown in Table 2, at the three pH values, the K / S value increases with increasing temperature, reaching its maximum at 110℃. As the temperature continues to rise to 120℃, the K / S value decreases; therefore, 110℃ is the optimal staining temperature. At the same temperature, the a value and K / S value at pH=8 are both higher than those at pH=7, resulting in better staining performance.

[0059] Therefore, the optimized dyeing process for the two colors is as follows: dyeing time is 30 min, dyeing temperature is 110℃, and a yellow color is obtained at pH=4, while a red color is obtained at pH=8.

[0060] Comparative Example 1: This comparative example is the same as other steps in Example 5, except that potassium aluminum sulfate was not added during extraction.

[0061] Comparative Example 2: This comparative example is the same as the other steps in Example 14, except that potassium aluminum sulfate was not added during extraction.

[0062] Comparative Example 3: This comparative example is the same as the other steps in Example 16, except that potassium aluminum sulfate was not added during extraction.

[0063] Comparative Example 4: This comparative example is the same as the other steps in Example 17, except that potassium aluminum sulfate was not added during extraction.

[0064] The color parameters of the madder pigment-dyed polyurethane sponges in Comparative Examples 1-4 are shown in Table 3.

[0065] Table 3 Color parameters of madder pigment-stained polyurethane sponges in Comparative Examples 1-4

[0066]

[0067] Comparing Table 3 and Table 2, the addition of potassium aluminum sulfate significantly improves the lightness (L) and K / S values, increases red light, and makes the colors brighter and more vibrant, resulting in better color parameters in the dyeing process.

[0068] The madder pigment-dyed polyurethane sponges obtained in Examples 1 and 5 were subjected to a soap washing fastness test. The test method was as follows: according to GB / 3921-2008 "Textiles - Tests for color fastness - Soap washing fastness", the sponges were soaped at 60°C for 30 min, washed with water, dried and rated. The test results are shown in Table 4.

[0069] Table 4. Wash fastness of the polyurethane sponges dyed with madder pigment in Examples 1 and 5

[0070]

[0071] As can be seen from Table 4, the dyed polyurethane sponge has high soap fastness, especially the dyed polyurethane sponge at pH=8 has significantly improved soap fastness, reaching level 4-5.

[0072] By utilizing madder extract pigments to naturally dye polyurethane sponges using medicinal plants, and employing specific dye solution ratios, dyeing temperatures, and times, the polyurethane achieves excellent coloring results and high colorfastness. Furthermore, the dyed polyurethane sponges are environmentally friendly, safer to use, and exhibit brighter, more vibrant colors. The extraction of madder pigments removes impurities, resulting in higher purity. Due to the reversible color-changing properties of madder pigments under different pH conditions, the hue of the polyurethane sponges dyed with madder extract pigments can change, displaying either yellow or red. In the medical field, the color change of the sponge can be used to determine the specific condition of the user's injury. It can also be used to monitor environmental conditions such as water quality and soil pH levels without causing environmental pollution.

[0073] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A dyeing method for natural-colored polyurethane sponges based on medicinal plants, characterized in that: Includes the following steps: S1. Prepare the polyurethane sponge to be stained, madder root, disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate, wherein the disodium hydrogen phosphate dodecahydrate, citric acid monohydrate, and potassium aluminum sulfate are all analytical grade. S2. Extraction of madder pigment: First, add 10g of madder to an acidic solution with a pH of 1-2, soak and drain. Then, reflux the soaking solution and boil for 30-60 minutes. Filter to remove the filtrate. Add water to the residue to 100mL, reflux and boil for 30-60 minutes, filter, remove the residue, adjust the pH of the filtrate to neutral, add 1-2 g / L of alum, let stand at room temperature for 1-2 hours, evaporate the water using a rotary evaporator, and dry at 80℃. The acidic solution is selected from one of sulfuric acid aqueous solution, hydrochloric acid aqueous solution, nitric acid aqueous solution, or phosphoric acid aqueous solution, and the volume of acidic solution used is 100mL. S3. Preparation of dyeing solution: Adjust the pH to 4-8 with disodium hydrogen phosphate dodecahydrate and citrate monohydrate buffer. Use madder pigment prepared in S2. The amount of madder pigment is 2-5% owf, and the bath ratio is 1:

100. S4. Dye the polyurethane sponge, controlling the dyeing temperature at 80℃-120℃, the dyeing time at 15min-30min, and the pH value at 4-8. S5. Wash the dyed polyurethane sponge with water, and then wash it with soap. The water washing temperature for polyurethane foam is 40-50℃, and the washing time is 20-30 minutes. The soaping conditions are: 5g / L of neutral soap flakes, a liquor ratio of 1:50, a soaping temperature of 60℃, and a soaping time of 10min. The soaping removes the floating color. S6. Wash and dry the polyurethane sponge after soaping.

2. The dyeing method for natural-colored polyurethane sponge based on medicinal plants according to claim 1, characterized in that: In step S6, the polyurethane sponge is washed with water, dehydrated, and then dried. The drying temperature is 80-100℃, and the drying time is 5-10 minutes.

3. The dyeing method for natural-colored polyurethane sponge based on medicinal plants according to claim 1, characterized in that: In step S4, the staining temperature is 110℃ and the staining time is 30 min.

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