Degradable printing ink and preparation method thereof

Abstract

The invention discloses degradable printing ink and a preparation method thereof, and belongs to the technical field of degradable printing ink. The water-based paint is prepared from the following raw materials in parts by weight: 40-60 parts of water-based polyurethane resin, 4-8 parts of an emulsifier, 22-34 parts of polylactic acid, 6-18 parts of modified chitosan, 9-15 parts of natural pigment, 3-5 parts of a defoaming agent, 50-70 parts of deionized water and 5-10 parts of a dispersing agent. The prepared printing ink takes polyurethane resin as a main binder, so that the printing ink is endowed with excellent heat resistance and corrosion resistance; polylactic acid is used as a secondary binder, so that the printing ink is endowed with certain heat resistance and degradability; the pigment is a natural pigment and has degradability; the ink is water-based ink and is more environment-friendly; wherein the modified chitosan can greatly enhance the antibacterial property, ultraviolet resistance and heat resistance of the ink, and the performance is stable; in conclusion, the degradable printing ink has important application value in the technical field of degradable printing ink.

Description

Technical Field

[0001] The present invention belongs to the technical field of degradable ink, and in particular, relates to a degradable ink and a preparation method thereof. Background Art

[0002] With the rapid development of social economy and the enhancement of people's environmental awareness, the concept of green and sustainable development has gradually become the focus of global attention. In the printing industry, ink is one of the important materials, and its production and use have an impact on the environment that cannot be ignored. Traditional inks usually use petroleum-based resins as the main component and add various organic solvents, pigments and additives. Although these inks have good printing properties, they release a large amount of volatile organic compounds (VOCs) during their production and use, which not only pollutes the air but also threatens human health. In addition, the ink in discarded printed materials is difficult to degrade naturally, and secondary pollution may occur during landfill or incineration, further exacerbating environmental problems.

[0003] In recent years, the research and application of degradable materials have provided new ideas for solving the above problems. Developing an ink that meets printing needs and has good biodegradability has become a hot topic in the industry. However, most of the "environmentally friendly" inks currently available on the market often have some technical bottlenecks. For example, when the ink is used outdoors for a long time, such as outdoor advertising, it will be damaged by adverse factors such as ultraviolet rays, acid and alkali, and high temperature weather for a long time. Generally, it cannot exceed one year, and serious yellowing and discoloration will occur. Its heat resistance and anti-aging properties are poor. Not only that, when the ink is printed on the packaging material, the ink layer provides a habitat for the growth and reproduction of microorganisms. When people come into contact with food packaging, they are easily infected with bacteria or microorganisms, which affects people's health. This limits its large-scale promotion and practical application.

[0004] From a technical point of view, the preparation of degradable inks requires comprehensive consideration of multiple factors. First, the selection of base resins is crucial. An ideal resin should have excellent film-forming properties, appropriate flexibility and hardness, and be able to be decomposed into harmless small molecules by microorganisms under specific conditions. Currently commonly used degradable resins include polylactic acid (PLA), polycaprolactone (PCL) and starch-based polymers, but each of them has certain limitations, such as poor heat resistance. Secondly, the selection of pigments and fillers also needs to take into account environmental protection and functionality. Although traditional inorganic pigments are brightly colored and stable, their production process consumes a lot of energy and is not easy to degrade; in summary, it is urgent to invent a heat-resistant and anti-aging degradable ink to meet the higher demands in the field of degradable ink technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a degradable ink and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a degradable ink comprises the following steps: The water-based polyurethane resin, emulsifier, polylactic acid, modified chitosan, natural pigment, defoamer and deionized water are mixed evenly and ground at room temperature. After the grinding, a dispersant is added and stirred to obtain a degradable ink.

[0007] Furthermore, the raw materials are calculated in parts by weight as follows: 40-60 parts of waterborne polyurethane resin, 4-8 parts of emulsifier, 22-34 parts of polylactic acid, 6-18 parts of modified chitosan, 9-15 parts of natural pigment, 3-5 parts of defoamer, 50-70 parts of deionized water and 5-10 parts of dispersant.

[0008] Furthermore, the emulsifier is one of sodium lauryl sulfate and alkylphenol polyoxyethylene ether.

[0009] Furthermore, the natural pigment is one of madder red, indigo, curcumin and monascus red.

[0010] Furthermore, the defoaming agent is one of pentaerythritol stearate and polyoxypropylene glyceryl ether.

[0011] Furthermore, the dispersant is a sodium polyacrylate dispersant.

[0012] The ink uses polyurethane resin as the main binder, which gives the ink excellent heat resistance and corrosion resistance; polylactic acid is used as the secondary binder, which not only gives the ink certain heat resistance, but also makes it biodegradable; secondly, the added pigment is a natural pigment, which is easier to degrade than organic pigments; finally, the prepared ink is a water-based ink, which uses water as the solvent and has a low VOC content, which reduces pollution to the environment and is more environmentally friendly.

[0013] Furthermore, the modified chitosan is prepared by the following steps: Step 1, adding succinic acid, pentamethylpiperidinol and N,N-dimethylformamide into a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stirring and mixing, then adding dibutyltin oxide and dicyclohexylcarbodiimide into the flask, raising the temperature to 75°C, stirring and reacting for 5 hours, filtering, removing the solvent by reduced pressure distillation, washing with anhydrous ethanol for multiple times, and vacuum drying to obtain an intermediate product 1; Dibutyltin oxide is used as a catalyst and dicyclohexylcarbodiimide is used as a dehydrating agent to cause an esterification reaction. The molar ratio of succinic acid to pentamethylpiperidinol in the reaction is controlled to be 1:1, and the succinic acid is slightly excessive to obtain an intermediate product 1. The specific reaction process is shown below:

[0014] Step 2, the intermediate product 1, 4,4'-diaminodiphenyl sulfone and N,N-dimethylformamide are added to a three-necked flask equipped with a thermometer and an electromagnetic stirrer device, and after stirring and mixing, dicyclohexylcarbodiimide is added to the flask, and the device is placed in a 50°C water bath, and heated in the water bath for 3 hours. After the reaction is completed, part of the solvent is first removed by rotary evaporation, and then purified by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two is 5:1), and the eluent is removed by rotary evaporation to obtain the intermediate product 2; Dicyclohexylcarbodiimide is used as a dehydrating agent, and the amino group of 4,4'-diaminodiphenyl sulfone reacts with the carboxyl group of the intermediate product 1 to undergo an amidation reaction, and the molar ratio of the two is controlled to be close to 1:1, and 4,4'-diaminodiphenyl sulfone is slightly excessive to obtain the intermediate product 2; the specific reaction process is as follows:

[0015] Step 3, glutaraldehyde, intermediate product 2, piperidine and N,N-dimethylformamide are added to a three-necked flask equipped with a thermometer and an electromagnetic stirrer, and after stirring and mixing, the system temperature is raised to 70°C, the temperature is maintained unchanged, and the reaction is stirred for 6 hours. After the reaction is completed, it is naturally cooled, and the solvent is distilled off under reduced pressure, and then purified by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two is 3:2), and the eluent is removed by rotary evaporation to obtain an intermediate product 3; Piperidine is used as a condensation agent, and the amino group on the intermediate product 2 is condensed with the aldehyde group on the glutaraldehyde to form an imine group (C=N Schiff base structure), and the intermediate product 3 is obtained by controlling the molar ratio of the two to be close to 1:1 and a slight excess of glutaraldehyde; the structure of the intermediate product 3 is shown below:

[0016] Step 4, adding acetic acid and chitosan to a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stirring until the solid is completely dissolved, then mixing the intermediate product 3, piperidine and N,N-dimethylformamide, adding them to the flask, stirring and reacting at room temperature for 45 minutes, then dripping sodium hydroxide solution to adjust the pH to 10, and continuing the reaction at 70°C for 2 hours. After the reaction is completed, filtering to obtain a precipitate, washing the precipitate with acetone, ethanol, acetone, and ethanol for multiple times in sequence, and drying in an oven to obtain modified chitosan; Under the action of piperidine, the aldehyde group on the intermediate product 3 condenses with the amino group on chitosan to form an imine group (C=N Schiff base structure) to obtain modified chitosan.

[0017] Furthermore, in step 1, the ratio of succinic acid, pentamethylpiperidinol, N,N-dimethylformamide, dibutyltin oxide, and dicyclohexylcarbodiimide is 12.7 g: 17.1 g: 100 mL: 0.2 g: 20.6 g.

[0018] Furthermore, in step 2, the ratio of the amount of the intermediate product 1, 4,4'-diaminodiphenyl sulfone, N,N-dimethylformamide, and dicyclohexylcarbodiimide is 27.1 g: 25.6 g: 120 mL: 20.6 g.

[0019] Furthermore, in step 3, the ratio of glutaraldehyde, intermediate product 2, piperidine and N,N-dimethylformamide is 11.2 g:50.1 g:15 mL:100 mL.

[0020] Furthermore, in step 4, the ratio of the amount of acetic acid, chitosan, intermediate product 3, piperidine, and N,N-dimethylformamide is 10mL:1g:13.7g:5mL:30mL.

[0021] Chitosan is a natural biodegradable material with good film-forming, antibacterial and stability properties. By modifying chitosan and connecting it to the organic molecular chain through C=N, this Schiff base structure can interact with bacterial proteins and enzymes, hindering the synthesis of bacterial nucleotides and amino acids, and playing a synergistic role with chitosan, greatly improving the antibacterial properties of the matrix. In addition, the modified chitosan molecule also contains hindered amines and diphenyl sulfone structures, among which the hindered amines can capture free radicals and inhibit photooxidation, and can improve the anti-ultraviolet properties of the matrix. The diphenyl sulfone structure contains benzene rings and sulfonic acid groups. The benzene ring is an aromatic group. The π-π conjugated system in the aromatic compound has a high thermal stability and can effectively disperse heat. The sulfonic acid group has a high bond energy and can further enhance the thermal stability of the matrix. Finally, the organic chain is connected to the inorganic chitosan, which can improve the migration resistance of organic small molecules and make the performance of the modified chitosan more durable.

[0022] Beneficial effects of the present invention: 1. The ink prepared by the present invention uses polyurethane resin as the main connecting material, which gives the ink excellent heat resistance and corrosion resistance; 2. Using polylactic acid as the secondary connecting material gives the ink certain heat resistance and degradability; 3. The pigment is natural and biodegradable; 4. The ink produced is water-based ink with low VOC content, which is more environmentally friendly; 5. Modified chitosan is obtained through a series of reactions. Compared with ordinary chitosan, it has better hydrophobicity and is easier to exert its performance, which greatly enhances the antibacterial, UV resistance and heat resistance of the ink to a certain extent; Therefore, the ink prepared by the present invention has excellent heat resistance, UV resistance and antibacterial properties, is environmentally friendly, and is degradable, and has important application value in the field of degradable ink technology. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0024] Embodiment 1 Preparation of modified chitosan: Step 1, add 12.7g succinic acid, 17.1g pentamethylpiperidinol and 100mL N,N-dimethylformamide into a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir and mix, then add 0.2g dibutyltin oxide and 20.6g dicyclohexylcarbodiimide into the flask, raise the temperature to 75°C, stir and react for 5h, filter, remove the solvent by vacuum distillation, wash with anhydrous ethanol for several times, and vacuum dry to obtain intermediate 1; Step 2, add 27.1g of intermediate product 1, 25.6g of 4,4'-diaminodiphenyl sulfone and 120mL of N,N-dimethylformamide to a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir and mix, then add 20.6g of dicyclohexylcarbodiimide to the flask, place the device in a 50°C water bath, heat in the water bath for 3h, and complete the reaction. First, remove part of the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 5:1), and remove the eluent by rotary evaporation to obtain intermediate product 2; Step 3, 11.2 g of glutaraldehyde, 50.1 g of intermediate product 2, 15 mL of piperidine and 100 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a thermometer and an electromagnetic stirrer. After stirring and mixing, the system temperature was raised to 70 ° C., the temperature was maintained unchanged, and the reaction was stirred for 6 hours. After the reaction was completed, it was naturally cooled, and the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:2), and the eluent was removed by rotary evaporation to obtain an intermediate product 3; Step 4, add 10mL acetic acid and 1g chitosan into a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir until the solid is completely dissolved, then mix 13.7g intermediate product 3, 5mL piperidine and 30mL N,N-dimethylformamide, add to the flask, stir and react at room temperature for 45min, then add sodium hydroxide solution dropwise to adjust the pH to 10, continue to react at 70°C for 2h, the reaction is completed, filter to obtain a precipitate, wash the precipitate with acetone, ethanol, acetone, and ethanol several times in turn, and dry in an oven to obtain modified chitosan.

[0025] Embodiment 2 Preparation of modified chitosan: Step 1, add 25.4g succinic acid, 34.2g pentamethylpiperidinol and 200mL N,N-dimethylformamide into a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir and mix, then add 0.4g dibutyltin oxide and 41.2g dicyclohexylcarbodiimide into the flask, raise the temperature to 75°C, stir and react for 5h, filter, remove the solvent by reduced pressure distillation, wash with anhydrous ethanol for several times, and vacuum dry to obtain intermediate 1; Step 2, add 54.2g of intermediate product 1, 51.2g of 4,4'-diaminodiphenyl sulfone and 240mL of N,N-dimethylformamide to a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir and mix, then add 41.2g of dicyclohexylcarbodiimide to the flask, place the device in a 50°C water bath, heat in the water bath for 3h, and complete the reaction. First, remove part of the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 5:1), and remove the eluent by rotary evaporation to obtain intermediate product 2; Step 3, 22.4 g of glutaraldehyde, 100.2 g of intermediate product 2, 30 mL of piperidine and 200 mL of N, N-dimethylformamide were added to a three-necked flask equipped with a thermometer and an electromagnetic stirrer. After stirring and mixing, the system temperature was raised to 70 ° C., the temperature was maintained unchanged, and the reaction was stirred for 6 hours. After the reaction was completed, it was naturally cooled, and the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:2), and the eluent was removed by rotary evaporation to obtain an intermediate product 3; Step 4, add 20mL acetic acid and 2g chitosan into a three-necked flask equipped with a thermometer and an electromagnetic stirrer, stir until the solid is completely dissolved, then mix 27.4g intermediate product 3, 10mL piperidine and 60mL N,N-dimethylformamide, add to the flask, stir and react at room temperature for 45min, then add sodium hydroxide solution dropwise to adjust the pH to 10, continue to react at 70°C for 2h, the reaction is completed, filter to obtain a precipitate, wash the precipitate with acetone, ethanol, acetone, and ethanol for multiple times, and dry in an oven to obtain modified chitosan.

[0026] Embodiment 3 40 g of waterborne polyurethane resin, 4 g of sodium dodecyl sulfate, 22 g of polylactic acid, 6 g of modified chitosan prepared in Example 1, 9 g of madder red, 3 g of pentaerythritol stearate and 50 g of deionized water were mixed evenly and ground at room temperature. After the grinding, 5 g of sodium polyacrylate dispersant was added and stirred to obtain a degradable ink.

[0027] Embodiment 4 50 g of waterborne polyurethane resin, 6 g of alkylphenol polyoxyethylene ether, 28 g of polylactic acid, 12 g of modified chitosan prepared in Example 2, 12 g of indigo, 4 g of polyoxypropylene glycerol ether and 60 g of deionized water were mixed evenly and ground at room temperature. After grinding, 7 g of sodium polyacrylate dispersant was added and stirred to obtain a degradable ink.

[0028] Embodiment 5 60 g of waterborne polyurethane resin, 8 g of alkylphenol polyoxyethylene ether, 34 g of polylactic acid, 18 g of modified chitosan prepared in Example 2, 15 g of curcumin, 5 g of polyoxypropylene glycerol ether and 70 g of deionized water were mixed evenly and ground at room temperature. After grinding, 10 g of sodium polyacrylate dispersant was added and stirred to obtain a degradable ink.

[0029] Comparative Example 1 Ordinary chitosan of the same mass was used to replace the modified chitosan in Example 5, and the remaining steps were the same as in Example 5 to prepare a degradable ink.

[0030] Comparative Example 2 Use commercially available antimicrobial ink.

[0031] The following performance tests were performed on Examples 3, 4, 5 and Comparative Examples 1 and 2 according to different test standards: The biodegradation rate was determined using the national standard GB / T 21801-2008 "Chemicals: Respirometric test for rapid biodegradability"; The antibacterial properties were determined using the national standard GB / T 21866-2008 “Determination of antibacterial properties and antibacterial effects of antibacterial coatings (paint films)”; The samples were placed in a 160°C environment for 72 hours to measure the antibacterial performance retention rate after heat aging in Examples 3, 4, 5 and Comparative Example 2 (using the national standard GB / T 21866-2008); the antibacterial rate retention rate = antibacterial rate after test / antibacterial rate before test × 100%; The sample was coated on a square plastic sheet with a side length of 5 cm. After UV curing, the sample was aged according to the national standard GB / T1865-2009 "Artificial weathering and artificial radiation exposure of paints and varnishes to filtered xenon arc radiation" and the changes in the sample were observed. The measured results are shown in the following table:

[0032] It can be seen from the above table that the ink prepared in the embodiment of the present invention has higher heat resistance, UV resistance and antibacterial properties than the control example, and is degradable, and has important application value in the field of degradable ink technology.

[0033] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a degradable ink, characterized in that: The following steps are involved: The water-based polyurethane resin, emulsifier, polylactic acid, modified chitosan, natural pigment, defoamer and deionized water are mixed evenly and ground at room temperature. After the grinding, a dispersant is added and stirred to obtain a degradable ink.

2. The method for preparing a degradable ink according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 40-60 parts of waterborne polyurethane resin, 4-8 parts of emulsifier, 22-34 parts of polylactic acid, 6-18 parts of modified chitosan, 9-15 parts of natural pigment, 3-5 parts of defoamer, 50-70 parts of deionized water and 5-10 parts of dispersant.

3. The method for preparing a degradable ink according to claim 1, characterized in that: The modified chitosan is prepared by the following steps: Step 1, add succinic acid, pentamethylpiperidinol and N,N-dimethylformamide into a flask, stir and mix, then add dibutyltin oxide and dicyclohexylcarbodiimide into the flask, raise the temperature to 75°C, stir and react for 5 hours, filter, distill under reduced pressure, wash and dry to obtain intermediate 1; Step 2, add the intermediate product 1, 4,4'-diaminodiphenyl sulfone and N,N-dimethylformamide into a flask, stir and mix, then add dicyclohexylcarbodiimide into the flask, place the device in a 50°C water bath, heat in the water bath for 3 hours, complete the reaction, perform rotary evaporation, purify by column chromatography, and perform rotary evaporation to obtain the intermediate product 2; Step 3, glutaraldehyde, intermediate product 2, piperidine and N,N-dimethylformamide are added to a flask, stirred and mixed, and the system temperature is raised to 70°C, the temperature is maintained unchanged, and the reaction is stirred for 6 hours. After the reaction is completed, the reaction is naturally cooled, vacuum distilled, purified by column chromatography, and rotary evaporated to obtain intermediate product 3; Step 4: Add acetic acid and chitosan to a flask and stir until the solid is completely dissolved. Then mix the intermediate product 3, piperidine and N,N-dimethylformamide, add them to the flask, stir and react at room temperature for 45 minutes, then add sodium hydroxide solution dropwise to adjust the pH to 10, continue the reaction at 70°C for 2 hours, filter, wash and dry to obtain modified chitosan after the reaction is completed.

4. The method for preparing a degradable ink according to claim 3, characterized in that: In step 1, the ratio of succinic acid, pentamethylpiperidinol, N,N-dimethylformamide, dibutyltin oxide and dicyclohexylcarbodiimide is 12.7 g: 17.1 g: 100 mL: 0.2 g: 20.6 g.

5. The method for preparing a degradable ink according to claim 3, characterized in that: In step 2, the ratio of the amount of the intermediate product 1, 4,4'-diaminodiphenyl sulfone, N,N-dimethylformamide, and dicyclohexylcarbodiimide is 27.1 g: 25.6 g: 120 mL: 20.6 g.

6. The method for preparing a degradable ink according to claim 3, characterized in that: In step 3, the ratio of glutaraldehyde, intermediate 2, piperidine and N,N-dimethylformamide is 11.2 g:50.1 g:15 mL:100 mL.

7. The method for preparing a degradable ink according to claim 3, characterized in that: In step 4, the ratio of the amount of acetic acid, chitosan, intermediate 3, piperidine, and N,N-dimethylformamide is 10mL:1g:13.7g:5mL:30mL.

8. The method for preparing a degradable ink according to claim 1, characterized in that: The natural pigment is one of madder red, indigo, curcumin and monascus red.

9. The method for preparing a degradable ink according to claim 1, characterized in that: The defoaming agent is one of pentaerythritol stearate and polyoxypropylene glyceryl ether.

10. A degradable ink, characterized in that: Prepared according to the method according to any one of claims 1 to 9.

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