A biodegradable ink, its preparation method and use

Abstract

The application relates to the technical field of printing inks, and provides a biodegradable ink as well as a preparation method and application thereof. The ink comprises 25-35 parts of a composite bio-based resin, 15-20 parts of natural pigment, 18-25 parts of degradable solvent, 3-5 parts of bio-based dispersant, 1-2 parts of bio-based defoaming agent, 2-4 parts of crosslinking agent and 1-3 parts of plasticizer; the composite bio-based resin is a compound of polylactic acid and at least one of modified starch, cashew phenol bio-acrylic acid and spiro-acetal bio-resin; and the degradable solvent is a compound of glycerol and 1,3-propanediol. The biodegradation rate of the biodegradable ink provided by the application can reach more than 95%, which is much higher than that of the existing biodegradable ink (usually less than 70%), the adhesion, water resistance and friction resistance of the paint film are good, the printing requirements of substrates such as paper and polylactic acid film are met, no VOCs are released, no heavy metal is contained, and the biodegradable ink can be used for food contact type packaging printing.

Description

Technical Field

[0001] This application relates to the field of printing ink technology, and in particular to a biodegradable ink, its preparation method, and its application. Background Technology

[0002] With the increasing global awareness of environmental protection and the tightening of environmental standards for the printing industry in various countries (such as the EU's REACH regulation and China's "Technical Requirements for Inks for Environmental Labeling Products"), the development of biodegradable and environmentally friendly inks has become an urgent need for the industry's development.

[0003] Currently, most existing biodegradable inks use single plant-based resins (such as rosin resin and starch resin) as film-forming agents, but they suffer from poor film-forming properties, weak adhesion, and insufficient water resistance. At the same time, some products still require the addition of non-degradable chemical additives to ensure printing performance, which makes it difficult to meet the degradation rate (usually less than 70%, which cannot meet the requirement of "biodegradation rate ≥ 90%" in GB / T19277.1-2011 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring the released carbon dioxide".

[0004] Therefore, developing an ink that combines excellent printing performance with a high biodegradability rate is of great significance for promoting the development of the printing industry. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a biodegradable ink with both excellent printing performance and high biodegradability, as well as its preparation method and application, which is of great significance for promoting the development of the printing industry.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a biodegradable ink, comprising, by weight, the following components: 25-35 parts of a composite bio-based resin, 15-20 parts of a natural pigment, 18-25 parts of a biodegradable solvent, 3-5 parts of a bio-based dispersant, 1-2 parts of a bio-based defoamer, 2-4 parts of a crosslinking agent, and 1-3 parts of a plasticizer; the composite bio-based resin is a compound of at least one of polylactic acid and modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin; the biodegradable solvent is a compound of glycerol and 1,3-propanediol.

[0007] In some embodiments, the composite bio-based resin is a compound of polylactic acid and modified starch, wherein the weight ratio of polylactic acid to modified starch is 2~3:1; the modified starch is acetate starch with a degree of substitution of 0.3~0.5; and the weight average molecular weight of polylactic acid is 80,000~120,000.

[0008] In some embodiments, the composite bio-based resin is a compound of polylactic acid, modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bioresin, wherein the weight ratio of polylactic acid to modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bioresin is 7~8:4~5:4~5:1~2.

[0009] In some embodiments, the weight ratio of glycerol to 1,3-propanediol is 2:1.

[0010] In some implementations, the natural pigment is a natural mineral pigment or a plant-derived pigment.

[0011] In some embodiments, the bio-based dispersant is a polyglycerol fatty acid ester with an HLB value of 8 to 10; the bio-based defoamer is polydimethylsiloxane-modified soybean oil with a silicon content of 5% to 8%.

[0012] In some embodiments, the crosslinking agent is citric acid, and the purity of the citric acid is not less than 99%; the plasticizer is epoxidized soybean oil, and the epoxy value of the epoxidized soybean oil is not less than 6%.

[0013] Secondly, embodiments of this application provide a method for preparing a biodegradable ink according to the first aspect, comprising: The biodegradable solvent is split into a first biodegradable solvent and a second biodegradable solvent, wherein the volume ratio of the first biodegradable solvent and the second biodegradable solvent is 5~8:12~15; Natural pigments and bio-based dispersants are added to a first biodegradable solvent and pre-dispersed at a first temperature to obtain a pigment dispersion. The composite bio-based resin is added to a second biodegradable solvent and mixed at a second temperature until the composite bio-based resin is completely dissolved to obtain a resin solution. The pigment dispersion was added to the resin solution and mixed and ground in multiple passes to obtain a mixed solution. Bio-based defoamer, crosslinking agent and plasticizer are added to a mixed solution and mixed and purified at a third temperature to obtain biodegradable ink.

[0014] In some embodiments, the first temperature is 40~50 ℃; the second temperature is 60~70 ℃; and the third temperature is 30~40 ℃.

[0015] In some embodiments, the pigment dispersion is added to a resin solution for mixing and multiple grinding passes to obtain a mixed solution, including: After adding the pigment dispersion to the resin solution and stirring for 15-20 minutes, transfer it to a three-roll mill. Adjust the gap between the first roller to 50-80 µm, the gap between the second roller to 20-30 µm, and the gap between the third roller to 5-10 µm. Grind 2-3 times until the fineness of the mixed solution is less than or equal to 15 µm.

[0016] Thirdly, embodiments of this application also provide the application of the biodegradable ink of the first aspect in packaging printing.

[0017] Compared with the prior art, the beneficial effects of the technical solution provided in this application embodiment include at least the following: All raw materials in the biodegradable ink provided in this application embodiment are biodegradable components. According to GB / T 19277.1-2011 standard, the biodegradable ink, under controlled composting conditions (temperature 58±2℃, humidity 50%~60%), achieves a biodegradation rate of over 95% within 180 days, far exceeding that of existing biodegradable inks (typically below 70%). It can completely integrate into the natural environment without residual pollution. Secondly, this biodegradable ink uses a composite bio-based resin (a compound of polylactic acid with at least one of modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bioresin), solving the problems of poor film-forming properties, weak adhesion, and insufficient water resistance in existing biodegradable inks that use a single bio-based resin. Furthermore, by combining composite bio-based resins with crosslinking agents and plasticizers, the ink film exhibits adhesion (adhesion grade 1 in cross-cut adhesion test), water resistance (no wrinkling or peeling after 24 hours of immersion in room temperature water), and abrasion resistance (no significant color fading after 50 cycles of rubbing), all reaching the levels of traditional petroleum-based inks. This meets the printing requirements for substrates such as paper and polylactic acid films. Thirdly, this biodegradable ink releases no VOCs (GC-MS testing shows VOC content ≤5g / kg) and contains no heavy metals (lead, cadmium, mercury, and hexavalent chromium content are all <10 mg / kg). It not only complies with EU REACH regulations and China's environmental labeling product requirements but can also be used for food contact packaging printing (such as disposable food bags and beverage labels), thus protecting consumer health. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0019] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0020] As a core material in the printing industry, ink is widely used in printing on substrates such as paper, plastics, and metals. Traditional inks are typically prepared using petroleum-based resins (such as polyurethane resins and acrylic resins) as film-forming substances, combined with mineral oil solvents, inorganic pigments, and chemical additives (such as dispersants and defoamers). However, these traditional inks pose significant environmental problems: on the one hand, petroleum-based resins and mineral oil solvents are difficult to degrade in the natural environment, and after disposal, they tend to remain in soil and water bodies for a long time, causing persistent pollution; on the other hand, some chemical additives (such as pigments containing heavy metals and volatile organic compounds) may volatilize or migrate during use, not only endangering the health of operators but also potentially affecting consumer safety through food packaging and other means.

[0021] Existing biodegradable inks mostly use single plant-based resins (such as rosin resin and starch resin) as film-forming agents, but they have problems such as poor film-forming properties, weak adhesion, and insufficient water resistance. At the same time, some products still need to add non-degradable chemical additives to ensure printing performance, which makes it difficult to meet the degradation rate (usually less than 70%, which cannot meet the requirement of "biodegradation rate ≥90%" in GB / T 19277.1-2011 "Determination of final aerobic biodegradability of materials under controlled composting conditions by measuring the release of carbon dioxide".

[0022] In view of this, this application provides a biodegradable ink, in which all raw materials are biodegradable components, including: a composite bio-based resin (a compound of polylactic acid with at least one of modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin), natural pigments, a biodegradable solvent (a compound of glycerol and 1,3-propanediol), a bio-based dispersant, a bio-based defoamer, a crosslinking agent, and a plasticizer. Under controlled composting conditions (temperature 58±2℃, humidity 50%~60%), this biodegradable ink achieves a biodegradation rate of over 95% within 180 days, far exceeding that of existing biodegradable inks (which typically have a biodegradation rate of less than 70% within 180 days). It can completely integrate into the natural environment without residual pollution. By using a composite bio-based resin (a compound of polylactic acid with at least one of modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin), the film-forming properties, adhesion, and water resistance of the ink can be improved, effectively solving the problems of poor film-forming properties, weak adhesion, and insufficient water resistance in existing biodegradable inks that use a single bio-based resin. Furthermore, by combining the composite bio-based resin with crosslinking agents and plasticizers, the ink film exhibits good adhesion, water resistance, and abrasion resistance, meeting the printing requirements of substrates such as paper and polylactic acid films. Thirdly, this biodegradable ink releases no VOCs and contains no heavy metals (lead, cadmium, mercury, and hexavalent chromium content are all <10 mg / kg), complying not only with EU REACH regulations and China's environmental labeling product requirements, but also allowing its use in food contact packaging printing (such as disposable food bags and beverage labels), thus protecting consumer health.

[0023] In a first aspect, embodiments of this application provide a biodegradable ink, comprising, by weight, the following components: 25-35 parts of a composite bio-based resin, 15-20 parts of a natural pigment, 18-25 parts of a biodegradable solvent, 3-5 parts of a bio-based dispersant, 1-2 parts of a bio-based defoamer, 2-4 parts of a crosslinking agent, and 1-3 parts of a plasticizer; the composite bio-based resin is a compound of at least one of polylactic acid and modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin; the biodegradable solvent is a compound of glycerol and 1,3-propanediol.

[0024] In some embodiments, the composite bio-based resin is a compound of polylactic acid (PLA) and modified starch, wherein the weight ratio of PLA to modified starch is 2 to 3:1, for example, it can be 2:1, 2.5:1 or 3:1, etc.

[0025] Preferably, the modified starch is acetate starch with a degree of substitution of 0.3 to 0.5. Esterification of starch with acetic anhydride can improve its compatibility and hydrophobicity with polylactic acid.

[0026] Preferably, polylactic acid (PLA) with a weight-average molecular weight of 80,000 to 120,000 is used to ensure the mechanical properties and adhesion of the film after it is formed.

[0027] A compound of polylactic acid (PLA) and modified starch is used as a composite bio-based resin. The two components exhibit significant synergistic and complementary properties, resulting in superior overall performance for biodegradable inks. PLA provides the ink system with excellent film-forming properties, high film hardness, excellent gloss, and outstanding biodegradability. Modified starch is widely available, inexpensive, and contains abundant polar groups, which not only further enhance the biodegradation rate and bio-based content of the system but also effectively mitigate the inherent brittleness of PLA, improving the toughness and folding resistance of the cured ink film. Simultaneously, it strengthens the ink's wetting ability and adhesion to packaging substrates such as paper and PLA films. This compound significantly reduces raw material costs and improves system stability and printability while ensuring high biodegradability and compliance with environmental and composting requirements. This comprehensive optimization of biodegradable inks in terms of fineness, color development, abrasion resistance, and environmental friendliness makes them more suitable for industrial applications in packaging material printing.

[0028] In some embodiments, the composite bio-based resin is a compound of polylactic acid with modified starch, cashew phenol bioacrylic acid and spirocyclic acetal bioresin, wherein the weight ratio of polylactic acid to modified starch, cashew phenol bioacrylic acid and spirocyclic acetal bioresin is 7~8:4~5:4~5:1~2.

[0029] A composite bio-based resin, consisting of polylactic acid (PLA), modified starch, cashew phenol bio-acrylic acid resin, and spirocyclic acetal bio-resin, is used as the basis for this biodegradable ink. The components work synergistically to comprehensively improve the ink's environmental friendliness, printability, film-forming properties, and degradation performance. PLA provides excellent film-forming properties, high hardness, and gloss, ensuring the ink film's basic strength and industrial compostability. Modified starch is renewable and inexpensive, significantly increasing the system's bio-based content and degradation rate while addressing PLA's brittleness and insufficient toughness, enhancing the ink film's folding and rubbing resistance, and improving adhesion to polar packaging substrates. Cashew phenol bio-acrylic acid resin improves system compatibility and pigment wetting and dispersion, enhancing the ink film's abrasion resistance, water resistance, and scratch resistance, improving color development and printing smoothness. The spirocyclic acetal bio-resin's molecular structure is easily decomposed by microorganisms, further increasing the overall biodegradation rate and completeness of the ink, while also regulating system viscosity and film density, and improving storage stability. When these four components are combined, the ink achieves a high biodegradability and compostability while also considering film toughness, adhesion, fineness, gloss, and abrasion resistance. The raw material cost is more reasonable, and the environmental attributes are outstanding. It can be well adapted to the printing needs of various packaging substrates such as paper and biodegradable film, and has good prospects for industrial application.

[0030] In some embodiments, the weight ratio of glycerol to 1,3-propanediol is 2:1. Both glycerol and 1,3-propanediol are biodegradable solvents prepared by bio-fermentation, with high boiling points (glycerol has a boiling point of 290°C, and 1,3-propanediol has a boiling point of 214°C), no volatile organic compound (VOC) release, and can adjust the viscosity of the ink, which is beneficial to improving printing smoothness.

[0031] In some embodiments, the natural pigments are natural mineral pigments or plant-derived pigments. For example, natural mineral pigments may be selected from ochre powder (iron oxide); plant-derived pigments may be selected from carbon black (prepared by carbonization of plants), curcumin (extracted from turmeric), and chlorophyll (extracted from algae). These natural pigments not only lack heavy metal pollution but also exhibit excellent compatibility with composite bio-based resins and are less prone to sedimentation.

[0032] In some embodiments, the bio-based dispersant is a polyglycerol fatty acid ester with an HLB value of 8-10. This polyglycerol fatty acid ester is prepared by polymerizing glycerol and then esterifying it with fatty acids. It can effectively disperse natural pigments, prevent pigment aggregation, and thus improve the color uniformity of the ink.

[0033] In some embodiments, the bio-based defoamer is polydimethylsiloxane-modified soybean oil, and the silicon content of the polydimethylsiloxane-modified soybean oil is 5% to 8%. This polydimethylsiloxane-modified soybean oil has both biodegradability and defoaming effect, which can eliminate bubbles generated during ink preparation and avoid defects such as pinholes and missing prints during printing.

[0034] In some embodiments, the crosslinking agent is citric acid, and the purity of the citric acid is not less than 99%. During the high-temperature film formation process, it can undergo a crosslinking reaction with the hydroxyl and carboxyl groups in the composite bio-based resin, thereby improving the water resistance and abrasion resistance of the paint film.

[0035] In some embodiments, the plasticizer is epoxidized soybean oil, and the epoxy value of the epoxidized soybean oil is not less than 6%, which can reduce the glass transition temperature of the composite bio-based resin, improve the flexibility of the coating film, and prevent the coating film from cracking when the substrate is bent after printing.

[0036] Secondly, embodiments of this application provide a method for preparing a biodegradable ink according to the first aspect, comprising: S1. The biodegradable solvent is split into a first biodegradable solvent and a second biodegradable solvent, wherein the volume ratio of the first biodegradable solvent and the second biodegradable solvent is 5~8:12~15; S2. Natural pigments and bio-based dispersants are added to a first biodegradable solvent and pre-dispersed at a first temperature to obtain a pigment dispersion. S3. Add the composite bio-based resin to the second biodegradable solvent and mix at the second temperature until the composite bio-based resin is completely dissolved to obtain a resin solution. S4. Add the pigment dispersion to the resin solution and mix and grind multiple times to obtain a mixed solution; S5. Add bio-based defoamer, crosslinking agent and plasticizer to the mixed solution and mix and remove impurities at the third temperature to obtain biodegradable ink.

[0037] The preparation method provided in this application uses conventional high-speed dispersers, three-roll mills and other equipment. It does not require special processes or expensive equipment. The operation steps are simple and the production cycle is short (about 4 to 6 hours). It is suitable for large-scale industrial production. The production cost is 15% to 20% lower than that of existing biodegradable inks. It has certain market promotion and application value.

[0038] In some embodiments, in step S1, the natural pigment, bio-based dispersant, and first biodegradable solvent are added to a high-speed disperser and dispersed for 30-40 minutes at a rotation speed of 1500-2000 r / min and a first temperature of 40-50 ℃ to obtain a pigment dispersion. This step can initially break up pigment agglomerates, laying the foundation for subsequent grinding.

[0039] In some embodiments, in step S2, the composite bio-based resin is added to a second biodegradable solvent and stirred for 60-90 minutes at a stirring speed of 800-1000 r / min and a second temperature of 60-70 °C until the composite bio-based resin is completely dissolved, thus obtaining a resin solution. By controlling the second temperature of 60-70 °C in this step, excessively rapid solvent evaporation can be avoided, while ensuring sufficient resin dissolution and improving film uniformity.

[0040] In some embodiments, in step S3, after adding the pigment dispersion to the resin solution and stirring for 15-20 minutes, the mixture is transferred to a three-roll mill. The gap between the first roller is adjusted to 50-80 µm, the gap between the second roller is 20-30 µm, and the gap between the third roller is 5-10 µm. The mill is then milled 2-3 times until the fineness of the mixed solution is less than or equal to 15 µm. Through the above-mentioned multi-milling process, the pigment particle size can be further reduced, thereby improving the tinting strength and hiding power of the ink.

[0041] In some embodiments, in step S4, a bio-based defoamer, crosslinking agent, and plasticizer are added to a mixed solution and stirred for 20 to 30 minutes at a rotation speed of 500 to 800 r / min and a third temperature of 30 to 40 °C. The mixture is then filtered through a 100 to 120 mesh filter to remove impurities, thereby obtaining biodegradable ink.

[0042] Thirdly, embodiments of this application also provide the application of the biodegradable ink of the first aspect in packaging printing.

[0043] Packaging printing includes paper packaging printing and flexible packaging printing, among which paper packaging printing and flexible packaging printing include food contact printing, etc.

[0044] The biodegradable ink provided in this application has a biodegradability of over 95%, can be completely integrated into the natural environment, leaves no residual pollution, is environmentally friendly and highly safe, and also has excellent printing performance. It can be widely used in paper packaging printing, flexible packaging printing, and food contact packaging printing (such as disposable food bags, beverage labels, etc.).

[0045] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0046] Example 1 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 25 parts of composite bio-based resin (a compound of PLA with a weight average molecular weight of 120,000 and starch acetate in a weight ratio of 3:1), 15 parts of natural pigment (ochre powder), 18 parts of biodegradable solvent (a compound of glycerol and 1,3-propanediol in a weight ratio of 2:1), 3 parts of polyglycerol fatty acid ester (HLB value of 8), 1 part of polydimethylsiloxane modified soybean oil (silicon content of 5%), 2 parts of citric acid, and 1 part of epoxidized soybean oil.

[0047] The preparation steps of the biodegradable ink provided in this embodiment are as follows: S1. Pre-dispersion: Add 15 parts of ochre powder, 3 parts of polyglycerol fatty acid ester and 6 parts of biodegradable solvent to a high-speed disperser and disperse for 40 min at a speed of 1500 r / min and a first temperature of 40 ℃ to obtain a pigment dispersion.

[0048] S2. Resin Dissolution: Add 25 parts of composite bio-based resin to 12 parts of biodegradable solvent, stir for 90 min at a stirring speed of 800 r / min and a second temperature of 60 ℃, until the composite bio-based resin is completely dissolved to obtain a resin solution.

[0049] S3. Mixing and grinding: Add the pigment dispersion to the resin solution and stir for 20 min. Then transfer it to a three-roll mill and adjust the gap between the first roller to 80 µm, the gap between the second roller to 30 µm, and the gap between the third roller to 10 µm. Grind for 3 passes to obtain a mixed solution with a fineness of ≤15 µm.

[0050] S4. Post-processing: Add 1 part defoamer, 2 parts citric acid, and 1 part epoxidized soybean oil to the mixed solution obtained in step S3 above. Stir for 30 min at a speed of 500 r / min and a third temperature of 30 ℃. Then filter through a 100-mesh filter to obtain biodegradable ink.

[0051] Example 2 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 35 parts of composite bio-based resin (a compound of PLA with a weight average molecular weight of 100,000 and starch acetate in a weight ratio of 2:1), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound of glycerol and 1,3-propanediol in a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0052] The preparation steps of the biodegradable ink provided in this embodiment are as follows: S1. Pre-dispersion: Add 20 parts curcumin, 5 parts polyglycerol fatty acid ester and 8.3 parts biodegradable solvent to a high-speed disperser and disperse for 30 min at a speed of 2000 r / min and a first temperature of 50 ℃ to obtain pigment dispersion.

[0053] S2. Resin Dissolution: Add 35 parts of composite bio-based resin to 16.7 parts of biodegradable solvent, and stir for 60 min at a stirring speed of 1000 r / min and a second temperature of 70 ℃ until the composite bio-based resin is completely dissolved to obtain a resin solution.

[0054] S3. Mixing and grinding: Add the pigment dispersion to the resin solution and stir for 15 min. Then transfer it to a three-roll mill and adjust the gap between the first roller to 50 µm, the gap between the second roller to 20 µm, and the gap between the third roller to 5 µm. Grind twice to obtain a mixed solution with a fineness of ≤10 µm.

[0055] S4. Post-processing: Add 2 parts of defoamer, 4 parts of citric acid, and 3 parts of epoxidized soybean oil to the mixed solution obtained in step S3 above. Stir for 20 min at a speed of 800 r / min and a third temperature of 40 ℃. Then filter through a 120-mesh filter to obtain biodegradable ink.

[0056] Example 3 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 30 parts of composite bio-based resin (a compound of PLA with a weight average molecular weight of 90,000 and starch acetate in a weight ratio of 2:1), 18 parts of natural pigment (chlorophyll), 20 parts of biodegradable solvent (a compound of glycerol and 1,3-propanediol in a weight ratio of 2:1), 4 parts of polyglycerol fatty acid ester (HLB value of 9), 1.5 parts of polydimethylsiloxane modified soybean oil (silicon content of 8%), 3 parts of citric acid, and 2 parts of epoxidized soybean oil.

[0057] The preparation steps of the biodegradable ink provided in this embodiment are as follows: S1. Pre-dispersion: Add 18 parts of chlorophyll, 4 parts of polyglycerol fatty acid ester and 6.7 parts of biodegradable solvent to a high-speed disperser and disperse for 30 min at a speed of 1500 r / min and a first temperature of 45 ℃ to obtain a pigment dispersion.

[0058] S2. Resin Dissolution: Add 30 parts of composite bio-based resin to 13.3 parts of biodegradable solvent, and stir for 80 min at a stirring speed of 900 r / min and a second temperature of 65 ℃ until the composite bio-based resin is completely dissolved to obtain a resin solution.

[0059] S3. Mixing and grinding: Add the pigment dispersion to the resin solution and stir for 20 min. Then transfer it to a three-roll mill and adjust the gap between the first roller to 60 µm, the gap between the second roller to 30 µm, and the gap between the third roller to 5 µm. Grind twice to obtain a mixed solution with a fineness of ≤15 µm.

[0060] S4. Post-treatment: Add 1.5 parts of defoamer, 3 parts of citric acid, and 2 parts of epoxidized soybean oil to the mixed solution obtained in step S3 above. Stir for 30 min at a speed of 600 r / min and a third temperature of 40 ℃. Then filter through a 100-mesh filter to obtain biodegradable ink.

[0061] Example 4 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 28 parts of composite bio-based resin (a compound of PLA with a weight average molecular weight of 80,000 and starch acetate in a weight ratio of 2.5:1), 15 parts of natural pigment (carbon black), 22 parts of biodegradable solvent (a compound of glycerol and 1,3-propanediol in a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 1 part of polydimethylsiloxane modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0062] The preparation steps of the biodegradable ink provided in this embodiment are as follows: S1. Pre-dispersion: Add 15 parts carbon black, 5 parts polyglycerol fatty acid ester and 7.3 parts biodegradable solvent to a high-speed disperser and disperse for 35 min at a speed of 2000 r / min and a first temperature of 40 ℃ to obtain a pigment dispersion.

[0063] S2. Resin Dissolution: Add 28 parts of composite bio-based resin to 14.7 parts of biodegradable solvent, and stir for 90 min at a stirring speed of 1000 r / min and a second temperature of 60 ℃ until the composite bio-based resin is completely dissolved to obtain a resin solution.

[0064] S3. Mixing and grinding: Add the pigment dispersion to the resin solution and stir for 20 min. Then transfer it to a three-roll mill and adjust the gap between the first roller to 70 µm, the gap between the second roller to 25 µm, and the gap between the third roller to 8 µm. Grind for 3 passes to obtain a mixed solution with a fineness of ≤15 µm.

[0065] S4. Post-treatment: Add 1 part defoamer, 4 parts citric acid, and 3 parts epoxidized soybean oil to the mixed solution obtained in step S3 above. Stir for 25 minutes at a speed of 700 r / min and a third temperature of 40 ℃. Then filter through a 120-mesh filter to obtain biodegradable ink.

[0066] Example 5 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 35 parts of composite bio-based resin (a compound composed of PLA, acetate starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin with a weight average molecular weight of 100,000 in a weight ratio of 8:5:5:2), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound composed of glycerol and 1,3-propanediol in a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0067] The preparation steps of the biodegradable ink provided in this embodiment are the same as those in Example 2.

[0068] Comparative Example 1 The biodegradable ink provided in this comparative example comprises the following components (raw materials) by weight: 35 parts of composite bio-based resin (a compound obtained by blending PLA and starch acetate in a weight ratio of 2:1), 20 parts of natural pigment (curcumin), 25 parts of mineral oil, 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0069] The preparation steps of the biodegradable ink provided in this comparative example are the same as those in Example 2.

[0070] Comparative Example 2 The biodegradable ink provided in this comparative example comprises the following components (raw materials) by weight: 35 parts starch resin, 20 parts natural pigment (curcumin), 25 parts biodegradable solvent (a compound obtained by blending glycerol and 1,3-propanediol in a weight ratio of 2:1), 5 parts polyglycerol fatty acid ester (HLB value of 10), 2 parts polydimethylsiloxane modified soybean oil (silicon content of 8%), 4 parts citric acid, and 3 parts epoxidized soybean oil.

[0071] The preparation steps of the biodegradable ink provided in this comparative example are the same as those in Example 2.

[0072] Comparative Example 3 The biodegradable ink provided in this comparative example comprises, by weight, the following components (raw materials): 35 parts of composite bio-based resin (a compound obtained by blending PLA and unmodified ordinary starch in a weight ratio of 2:1), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol and 1,3-propanediol in a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0073] The preparation steps of the biodegradable ink provided in this comparative example are the same as those in Example 2.

[0074] Comparative Example 4 The biodegradable ink provided in this comparative example comprises, by weight, the following components (raw materials): 35 parts of composite bio-based resin (a compound obtained by blending PLA with unmodified ordinary starch at a weight ratio of 2:1 with a weight average molecular weight of 50,000), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol with 1,3-propanediol at a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0075] The preparation steps of the biodegradable ink provided in this comparative example are the same as those in Example 2.

[0076] Comparative Example 5 The biodegradable ink provided in this comparative example comprises, by weight, the following components (raw materials): 35 parts of composite bio-based resin (a compound obtained by blending PLA with unmodified ordinary starch at a weight ratio of 2:1 with a weight average molecular weight of 130,000), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol with 1,3-propanediol at a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0077] The preparation steps of the biodegradable ink provided in this comparative example are the same as those in Example 2.

[0078] Comparative Example 6 The biodegradable ink provided in this embodiment comprises the following components (raw materials) by weight: 35 parts of composite bio-based resin (a compound obtained by blending PLA with acetate starch at a weight ratio of 2:1 with a weight average molecular weight of 100,000), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol with 1,3-propanediol at a weight ratio of 2:1), 5 parts of sodium dodecylbenzenesulfonate, 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0079] Comparative Example 7 The biodegradable ink provided in this comparative example comprises, by weight, the following components (raw materials): 35 parts of composite bio-based resin (a compound obtained by blending PLA with acetate starch at a weight ratio of 2:1 with a weight average molecular weight of 100,000), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol with 1,3-propanediol at a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0080] The preparation steps of the biodegradable ink provided in this comparative example differ from those in Example 2 only in that: S2. Resin Dissolution: Add 35 parts of composite bio-based resin to 16.7 parts of biodegradable solvent, stir for 60 min at a stirring speed of 1000 r / min and a second temperature of 80 ℃, until the composite bio-based resin is completely dissolved to obtain a resin solution.

[0081] Comparative Example 8 The biodegradable ink provided in this comparative example comprises, by weight, the following components (raw materials): 35 parts of composite bio-based resin (a compound obtained by blending PLA with acetate starch at a weight ratio of 2:1 with a weight average molecular weight of 100,000), 20 parts of natural pigment (curcumin), 25 parts of biodegradable solvent (a compound obtained by blending glycerol with 1,3-propanediol at a weight ratio of 2:1), 5 parts of polyglycerol fatty acid ester (HLB value of 10), 2 parts of polydimethylsiloxane-modified soybean oil (silicon content of 8%), 4 parts of citric acid, and 3 parts of epoxidized soybean oil.

[0082] The preparation steps of the biodegradable ink provided in this comparative example differ from those in Example 2 only in that step S3 is omitted and step S4 is replaced by: adding the pigment dispersion to the resin solution and stirring for 15 min, then adding 2 parts of defoamer, 4 parts of citric acid, and 3 parts of epoxidized soybean oil, stirring for 20 min at a speed of 800 r / min and a third temperature of 40 ℃, and then filtering through a 120-mesh filter to obtain the biodegradable ink.

[0083] Comparative Example 9 This comparative example provides a commercially available biodegradable ink, the raw materials of which, by weight, include: 30 parts starch resin, 18 parts carbon black, 20 parts mineral oil, 4 parts chemical dispersant (sodium dodecylbenzenesulfonate), 1.5 parts defoamer (polyether-modified siloxane), and 2 parts plasticizer (dibutyl phthalate).

[0084] The biodegradable inks provided in Examples 1-5 and Comparative Examples 1-9 were subjected to the following performance tests, and the test results are shown in Table 1.

[0085] The performance testing metrics and methods are as follows: 1) Ink biodegradability: The biodegradable inks provided in Examples 1-4 and Comparative Examples 1-9 were tested according to GB / T 19277.1-2011 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring the amount of carbon dioxide released". The controlled composting conditions were: temperature 58±2℃, humidity 50%-60%, 180 days.

[0086] 2) Ink adhesion: Packaging printing was carried out using the biodegradable inks provided in Examples 1-4 and Comparative Examples 1-9 (with the same packaging materials). After the inks dried, the cross-cut adhesion test was performed.

[0087] 3) Water resistance of ink: The biodegradable inks provided in Examples 1-4 and Comparative Examples 1-9 were used for packaging printing (with the same packaging materials). After the ink dried, the packaging materials printed with the ink were soaked in water for 24 hours. The wrinkling and peeling of the ink on the packaging materials were observed and recorded.

[0088] 4) Ink abrasion resistance: The biodegradable inks provided in Examples 1-4 and Comparative Examples 1-9 were used for packaging printing (with the same packaging materials). After the ink dried, the ink was rubbed back and forth 50 times, and the color fading of the ink was observed and recorded.

[0089] Table 1 Performance Test Results As shown in Table 1 above, the biodegradable inks prepared in Examples 1-5 exhibit adhesion grades of 0-1, excellent water resistance (no whitening, wrinkling, or peeling after 24 hours of water resistance testing), and excellent abrasion resistance (no significant color fading after 50 rubs). These inks meet the printing requirements of various packaging substrates such as paper and polylactic acid film. Furthermore, under controlled composting conditions, the biodegradability of these inks reaches over 95% after 180 days, indicating complete degradation without residual pollution and outstanding environmental friendliness. In addition, this series of inks releases no VOCs during use, complying with EU REACH regulations and relevant requirements for Chinese environmental labeling products. They can be applied to food contact packaging printing scenarios such as disposable food bags and beverage labels, offering high safety and effectively protecting consumer health. In comparison, the commercially available biodegradable ink in Comparative Example 9 had a biodegradability rate of only 68.2%, a cross-cut adhesion test result of level 3, and partial peeling of the ink film. It also showed wrinkling after 12 hours of water resistance testing, obvious color fading after 30 rubs, and a VOC content as high as 80g / kg, which is difficult to meet the requirements for food packaging and environmental protection.

[0090] The comparison results between Example 2 and Example 5 show that the composite bio-based resin formed by compounding polylactic acid, acetate starch, cashew phenol bioacrylic resin and spirocyclic acetal bio-resin can further improve the biodegradability and adhesion of the ink, and has better overall performance.

[0091] The comparison results between Example 2 and Comparative Example 1 show that the present application uses glycerol and 1,3-propanediol to form a biodegradable solvent, which can synergistically improve the biodegradability, adhesion, water resistance and abrasion resistance of the ink, and the system does not release volatile organic compounds, making it green and environmentally friendly.

[0092] The comparison results between Example 2 and Comparative Examples 2-5 show that using polylactic acid with a weight average molecular weight of 80,000-120,000 and starch acetate as a composite bio-based resin can comprehensively improve the ink in terms of biodegradability, adhesion, water resistance and abrasion resistance.

[0093] The comparison results between Example 2 and Comparative Example 6 show that using polyglycerol fatty acid esters as a bio-based dispersant is beneficial for further optimizing the biodegradability, adhesion, water resistance and abrasion resistance of the ink.

[0094] The comparison results between Example 2 and Comparative Example 7 show that controlling the resin dissolution temperature within the range of 60~70℃ helps to improve the adhesion, water resistance and abrasion resistance of the ink.

[0095] The comparison results between Example 2 and Comparative Example 8 show that using multiple grinding processes for dispersion treatment can significantly improve the adhesion, water resistance, and abrasion resistance of the ink, thereby enhancing its overall performance.

[0096] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A biodegradable ink, characterized in that, By weight, it includes the following components: The composition includes 25-35 parts of composite bio-based resin, 15-20 parts of natural pigment, 18-25 parts of biodegradable solvent, 3-5 parts of bio-based dispersant, 1-2 parts of bio-based defoamer, 2-4 parts of crosslinking agent, and 1-3 parts of plasticizer. The composite bio-based resin is a compound of at least one of polylactic acid and modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bio-resin. The degradable solvent is a mixture of glycerol and 1,3-propanediol.

2. The biodegradable ink according to claim 1, characterized in that, The composite bio-based resin is a compound of polylactic acid and modified starch, wherein the weight ratio of polylactic acid to modified starch is 2~3:1; The modified starch is acetate starch with a degree of substitution of 0.3 to 0.

5. The polylactic acid has a weight-average molecular weight of 80,000 to 120,000.

3. The biodegradable ink according to claim 1, characterized in that, The composite bio-based resin is a compound of polylactic acid, modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bioresin, wherein the weight ratio of polylactic acid to modified starch, cashew phenol bioacrylic acid, and spirocyclic acetal bioresin is 7~8:4~5:4~5:1~2.

4. The biodegradable ink according to claim 1, characterized in that, The weight ratio of glycerol to 1,3-propanediol is 2:

1.

5. The biodegradable ink according to claim 1, characterized in that, The natural pigments are natural mineral pigments or plant-derived pigments; The bio-based dispersant is a polyglycerol fatty acid ester, and the HLB value of the polyglycerol fatty acid ester is 8~10; The bio-based defoamer is polydimethylsiloxane-modified soybean oil, and the silicon content of the polydimethylsiloxane-modified soybean oil is 5%~8%.

6. The biodegradable ink according to claim 1, characterized in that, The crosslinking agent is citric acid, and the purity of the citric acid is not less than 99%. The plasticizer is epoxidized soybean oil, and the epoxy value of the epoxidized soybean oil is not less than 6%.

7. A method for preparing a biodegradable ink as described in any one of claims 1 to 6, characterized in that, include: The biodegradable solvent is split into a first biodegradable solvent and a second biodegradable solvent, wherein the volume ratio of the first biodegradable solvent to the second biodegradable solvent is 5~8:12~15; Natural pigments and bio-based dispersants are added to a first biodegradable solvent and pre-dispersed at a first temperature to obtain a pigment dispersion. The composite bio-based resin is added to a second biodegradable solvent and mixed at a second temperature until the composite bio-based resin is completely dissolved to obtain a resin solution. The pigment dispersion is added to the resin solution and mixed and milled multiple times to obtain a mixed solution; Bio-based defoamer, crosslinking agent and plasticizer are added to the mixed solution and mixed and purified at a third temperature to obtain biodegradable ink.

8. The method for preparing biodegradable ink according to claim 7, characterized in that, The first temperature is 40~50 ℃; the second temperature is 60~70 ℃; and the third temperature is 30~40 ℃.

9. The method for preparing biodegradable ink according to claim 7, characterized in that, The pigment dispersion is added to the resin solution for mixing and multiple grinding processes to obtain a mixed solution comprising: After adding the pigment dispersion to the resin solution and stirring for 15-20 minutes, the mixture is transferred to a three-roll mill. The distance between the first roller is adjusted to 50-80 µm, the distance between the second roller is 20-30 µm, and the distance between the third roller is 5-10 µm. The mixture is then ground 2-3 times until the fineness of the mixed solution is less than or equal to 15 µm.

10. The application of the biodegradable ink as described in claim 1 in packaging printing.

Images