Environment-friendly printing process

Abstract

According to the technical scheme, the environment-friendly printing process is characterized in that a photosensitive polymer prepared by mixing biodegradable base materials is adopted for plate making, and preparation comprises the steps of preparing a mixed material (containing natural chitosan, starch, a cross-linking agent, a photoinitiator, a natural toughening agent and the like), coating a photosensitive coating, curing a pattern and the like; the preparation method comprises the following steps: firstly, dispersing natural pigment in deionized water, adding a natural solvent to obtain a base solution, then adding an emulsifier, a stabilizer and the like for treatment, and carrying out ultrasonic emulsification and three-stage filtration; and coating a molecular sieve coating on the surface of the printed material, and drying and curing by natural wind. The chemical pollution caused by waste and destruction of the printing plate is avoided, the ink VOCs emission risk is eliminated, energy consumption is reduced, the problem that an existing printing technology pollutes the environment is effectively solved, and the environment friendliness of the printing technology is improved.

Description

Technical Field

[0001] The present invention relates to the field of printing technology, and particularly to an environment-friendly printing process. Background Art

[0002] Printing refers to the process of transferring through a printing machine and special ink onto a printing substrate. It is a unique technology that can batch reproduce the content of the original manuscript such as text, pictures, photos, etc. onto the surfaces of materials such as paper, fabric, leather, etc. after processes such as plate making, inking, and pressing to transfer the ink. In existing printing technologies, according to different printing methods, it is mainly divided into flexographic printing, screen printing, offset printing, and gravure printing.

[0003] Among them, in the process of flexographic printing, first, a printing plate with the required pattern needs to be made for the printing machine to print the pattern. Currently, the commonly used printing plates on the market are usually made of photosensitive polymers with vinyl methyl acrylate or rubber as the monomer. Although the technology is relatively mature, in the actual printing process, when the printing plate is discarded and destroyed, it still needs to be destroyed through chemical treatment, resulting in a large amount of chemical waste during the destruction process, causing environmental pollution; moreover, in the existing printing process, the ink used is usually solvent-based ink, which contains volatile organic compounds (VOCs). The wastewater and waste ink generated during the printing process will pollute the soil and water sources. Although water-based ink has been used to replace solvent-based ink, there is still a risk of a small amount of volatile organic compound emissions in the water-based ink, and it is impossible to completely avoid the environmental pollution caused by printing. Summary of the Invention

[0004] The present invention provides an environment-friendly printing process, which solves the problem that harmful substances will be generated during the printing process of the printing plate and ink in the prior art, polluting the environment.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an environment-friendly printing process, including the following steps: S1. Plate making: Using a photosensitive polymer made of a biodegradable substrate mixture as the printing plate; S2. Prepare the printing machine: Install the printing plate completed in S1 on the printing machine and conduct debugging; S3. Prepare zero-solvent ink: According to the requirements of the printing pattern and color, use plant-extracted natural pigments, disperse them in deionized water, and mix them with additives to obtain zero-solvent ink, and then transport the obtained ink to the ink storage mechanism in the printing machine for use; S4. Printing: The printing machine in S2 transfers the zero-solvent ink prepared in S3 from the printing plate to the surface of the printing material through the printing roller to form a printing pattern; S5, Drying: Apply a molecular sieve coating on the surface of the printed material with the printed pattern already formed, and then dry and cure the printed pattern with natural wind.

[0006] The present invention is further configured such that the preparation steps of the photosensitive polymer in S1 are as follows: A1, Preparation of the mixed material: Select the mixed natural chitosan and starch as the base material, and add a crosslinking agent, a photoinitiator, and a natural toughening agent thereto to obtain the mixed material; A2, Coating of the photosensitive coating: Select a degradable plastic as the plate base, and then coat the mixed material on the plate base to form a photosensitive coating; A3, Pattern curing: Irradiate and expose the photosensitive coating with ultraviolet light to cure the pattern area, and then rinse and remove the unexposed part with an aqueous developer to finally obtain a clear pattern template.

[0007] The present invention is further configured such that the crosslinking agent uses a melamine crosslinking agent, the photoinitiator uses a benzophenone photoinitiator, and the natural toughening agent uses glycerol.

[0008] The present invention is further configured such that the preparation steps of the zero - solvent ink in S3 are as follows: B1, Disperse the natural pigment in deionized water, and then add a natural solvent to obtain the ink base liquid; B2, Add an emulsifier and a stabilizer to the ink base liquid obtained in B1 to obtain the treated ink base liquid; B3, Treat the ink base liquid obtained in B2 with ultrasonic emulsification technology so that the particle size of the pigment particles in the ink base liquid is between 10 - 50 nanometers; B4, Perform three - stage filtration on the ink base liquid treated with ultrasonic emulsification technology in B3 to obtain a pure and uniform zero - solvent ink.

[0009] The present invention is further configured such that the emulsifier used in B2 is lecithin, and the stabilizer uses polyethylene glycol.

[0010] The present invention is further configured such that in step A1, polylactic acid and nanocellulose are further added to the mixed material.

[0011] The present invention is further configured such that in step A1, plant cellulose and lignin are further added to the mixed material.

[0012] The present invention is further configured such that in step B2, natural resin and self - healing polyurethane are further added to the ink base liquid obtained in B1.

[0013] The present invention is further configured such that in step A1, a temperature - responsive crosslinking agent is further added to the mixed material.

[0014] The present invention is further configured such that in step B2, graphene and silver nanocomposites are further added to the ink base liquid obtained in B1.

[0015] In summary, the beneficial effects of the present invention are as follows: Compared with the prior art, in the plate making aspect of the present application, a photosensitive polymer made of a biodegradable substrate mixture is used as the printing plate, avoiding the environmental pollution caused by a large amount of chemical waste generated by chemical treatment when traditional printing plates are discarded and destroyed, being beneficial to environmental protection, and reducing the negative impact of the printing industry on the ecology.

[0016] Secondly, in the ink preparation, by using natural pigments extracted from plants, dispersing them in deionized water, and mixing them with additives to prepare zero-solvent ink, the emission risk of volatile organic compounds (VOCs) is eliminated from the source, greatly reducing the pollution of wastewater and waste ink to the soil and water sources during the printing process, and improving the environmental friendliness of the printing process.

[0017] Furthermore, in the drying link after printing, by coating a molecular sieve coating on the surface of the printing material and using natural wind for drying and curing, the energy consumption is reduced, further reflecting the green environmental protection concept of the process of the present invention. The improved environmentally friendly printing process effectively solves the problems of harmful substances generated by printing plates and inks in the printing process and environmental pollution in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the process diagram of the present invention.

[0019] Figure 2 is the preparation process diagram of the printing plate of the present invention.

[0020] Figure 3 is the preparation process diagram of the zero-solvent ink of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present invention.

[0022] As Figures 1-3 shown, this embodiment discloses an environmentally friendly printing process, including the following steps: S1. Plate making: Using a photosensitive polymer made of a biodegradable substrate mixture as the printing plate; Specifically, the preparation steps of the photosensitive polymer in S1 are as follows: A1. Preparation of composite material: Select the natural chitosan and starch after mixing as the base materials, add a crosslinking agent, a photoinitiator, and a natural toughening agent to obtain the composite material; at the same time, introduce acrylate-based photosensitive monomers and modified epoxy resins to improve the photocuring ability and durability; A2. Coating of photosensitive coating: Select a degradable plastic as the plate base, and then coat the composite material on the plate base to form a photosensitive coating; A3. Pattern curing: Use ultraviolet light to irradiate and expose the photosensitive coating, cure the pattern area, and then use an aqueous developer to wash away the unexposed part, finally obtaining a clear pattern template.

[0023] Through the above process, the printing plate of the present invention selects natural chitosan and starch as the base materials, both of which are biodegradable natural polymers. Chitosan, as a natural polysaccharide, has good biodegradability and strong antibacterial properties; while starch has good film-forming properties and adhesive properties, which can enhance the stability of the printing plate.

[0024] Among them, the crosslinking agent selects melamine crosslinking agent, the photoinitiator selects benzophenone photoinitiator and is combined with a co-initiator, such as triethylamine, so as to ensure that the photosensitive material can be quickly crosslinked and cured under ultraviolet light irradiation; while the natural toughening agent selects glycerol, realizing the crosslinking and curing of the photosensitive polymer, so that when a pattern is formed under ultraviolet light irradiation, the pattern area can be firmly crosslinked, and the unexposed part can be removed by the aqueous developer. These additives not only improve the strength of the photosensitive polymer, but also ensure the biodegradability and environmental protection performance of the material after use.

[0025] Specifically, melamine as a crosslinking agent can form a three-dimensional crosslinked structure with the polymer chain, improving the hardness and stability of the photosensitive polymer and ensuring the durability of the printing plate during long-term use.

[0026] Benzophenone as a photoinitiator, after being irradiated by ultraviolet light, benzophenone can activate the photoinitiation reaction in the photosensitive polymer, promoting the polymerization reaction in the pattern area, thereby forming a stable pattern. The unexposed area is removed by the aqueous developer to form a clear printing template.

[0027] And glycerol as a toughening agent can improve the flexibility of the photosensitive polymer, making the printing plate more ductile during the actual printing process and reducing the risk of cracks or damage during printing.

[0028] S2. Prepare the printing press: Install the printing plate completed in plate making in S1 on the printing press and conduct debugging; Specifically, in this process, the degradable photosensitive polymer printing plate prepared in step S1 is installed on the printing press to ensure that the installation position and adjustment state of the printing plate meet the process requirements. During debugging, ensure the stability of the various parameters of the printing press and the alignment accuracy of the printing plate.

[0029] S3. Prepare zero-solvent ink: According to the printing pattern and color requirements, use plant-extracted natural pigments, disperse them in deionized water, and mix them with additives to obtain zero-solvent ink. Then, transport the prepared ink to the ink storage mechanism in the printing press for use. Specifically, the steps for preparing zero-solvent ink in S3 are as follows: B1. Disperse the natural pigment in deionized water, and then add a natural solvent to obtain an ink base liquid. B2. Add an emulsifier and a stabilizer to the ink base liquid obtained in B1 to obtain a treated ink base liquid. B3. Treat the ink base liquid obtained in B2 using ultrasonic emulsification technology to make the pigment particle size in the ink base liquid range from 10 to 50 nanometers. B4. Perform three-stage filtration on the ink base liquid that has undergone ultrasonic emulsification technology in B3 to obtain pure and uniform zero-solvent ink.

[0030] In order to further improve the environmental protection of the process and reduce the pollution of the environment by wastewater and waste materials generated during the printing process, the present invention uses pigments extracted from natural plants to replace traditional chemical pigments, and uses deionized water as a solvent to avoid the use of harmful solvents. The pigment is first dispersed in deionized water, and after ultrasonic emulsification treatment, it is mixed with a natural solvent and other additives (such as an emulsifier and a stabilizer) to obtain zero-solvent ink; the above zero-solvent ink does not contain volatile organic compounds (VOCs), and this ink will not release polluting gases during use, effectively reducing the pollution of the atmosphere and the environment.

[0031] Among them, the natural pigment is derived from plant extracts, such as chlorophyll, anthocyanin, etc. It is naturally non-toxic and pollution-free, meets the environmental protection requirements, and exhibits good color reducibility and stability in printing.

[0032] The additives include an emulsifier and a stabilizer. The emulsifier uses lecithin, which, as a natural emulsifier, can help the pigment disperse evenly in water, prevent pigment particles from aggregating, and thus improve the stability of the ink.

[0033] The stabilizer uses polyethylene glycol, which can enhance the rheology and stability of the ink, prevent the pigment from precipitating or stratifying during storage, and ensure that the ink always maintains uniformity during use.

[0034] During the ink preparation process, the ultrasonic emulsification technology is adopted. After mixing the ink base liquid prepared in B2 and placing it in an ultrasonic reaction vessel, the ultrasonic reaction vessel is started. When ultrasonic waves propagate in the liquid, alternating high-pressure and low-pressure regions will be generated. When the low-pressure region forms, the tiny bubbles in the liquid will rapidly expand; while in the high-pressure region, these bubbles will violently contract and collapse, which is the cavitation effect. Under the strong mechanical force generated by the cavitation effect, the pigment particles are continuously impacted and sheared, and thus gradually broken into smaller particle sizes, finally reaching the range of 10 - 50 nanometers. The whole process needs to last for a certain period of time, usually 10 - 15 minutes, to ensure that the pigment particles are fully refined.

[0035] Reducing the pigment particles to between 10 - 50 nanometers through the ultrasonic emulsification technology ensures the uniformity of the pigment particles, improves the dispersion of the pigment in the ink, avoids the problems of particle precipitation or uneven dispersion existing in traditional water-based inks, enables the ink to have a higher color surface force and adhesion, improves the fluidity and adhesion of the ink, and improves the quality of the ink.

[0036] S4. Printing: The printing press in S2 transfers the zero-solvent ink prepared in S3 from the printing plate to the surface of the printing material through the printing cylinder, forming a printed pattern. Specifically, in this step, the debugged printing press uses the freshly prepared zero-solvent ink for printing. Through the printing cylinder, the ink is transferred from the photosensitive printing plate to the surface of the substrate, forming the required pattern.

[0037] S5. Drying: Apply a molecular sieve coating on the surface of the printing material where the printed pattern has been formed, and then dry and cure the printed pattern through natural wind.

[0038] Specifically, after printing, the molecular sieve coating technology is used to dry and cure the surface of the printed pattern. The molecular sieve coating can effectively absorb moisture, help accelerate the curing process of the printed pattern, and reduce the pollution caused by ink volatilization. Then, the pattern is further cured by natural air drying.

[0039] Among them, the molecular sieve can adsorb moisture or solvents, helping to cure the moisture or residual solvents in the ink. This process not only improves the curing efficiency but also reduces the emission of volatile organic compounds; while the natural air drying method reduces energy consumption and the use of chemical desiccants, which is more environmentally friendly.

[0040] At the same time, on the basis of the effects achieved by the above process steps, there is also a synergistic effect among the various components: among them, as the components for preparing the printing plate, The amino groups in chitosan and the hydroxyl groups in starch can bind through hydrogen bonds. This strong intermolecular interaction increases the binding force between the two, enabling the coating applied on the printing plate base to have good mechanical strength. At the same time, the combination of the natural antibacterial property of chitosan and the film-forming property of starch can also prevent the growth of microorganisms on the printing plate, improving the cleanliness and stability of the printing plate.

[0041] Benzophenone can efficiently absorb ultraviolet light and generate free radicals, thereby promoting the cross-linking reaction to increase the cross-linking density and mechanical strength of the photosensitive coating. Among them, the benzophenone photoinitiator and the melamine cross-linking agent effectively improve the response ability of the photosensitive material to ultraviolet light, enhance the curing efficiency, shorten the exposure time, and ensure the fineness and stability of the pattern area.

[0042] Furthermore, in the components of the printing plate, polylactic acid and nanocellulose are additionally added. Specifically, polylactic acid is a biodegradable plastic extracted from renewable resources such as corn starch, with high biocompatibility and thermal stability; while nanocellulose is a natural material with an extremely high specific surface area and mechanical strength. It can effectively enhance the rigidity and strength of the material, and due to its nanoscale structure, it can form a tight cross-linked structure with other polymers at the molecular level. Moreover, nanocellulose provides a significant strengthening effect. It undergoes molecular-level cross-linking with polylactic acid molecules through its high surface area, significantly improving the strength and rigidity of the composite material. Its nanostructure enables the photosensitive coating to have better tensile strength and abrasion resistance, while the thermal stability of polylactic acid enables the composite material to still maintain good performance in high-temperature environments. This synergistic effect makes the photosensitive printing plate more stable during high-temperature and high-force printing processes. And because nanocellulose also has very good optical properties, it can effectively improve the transparency of the material, thereby enhancing the light transmittance of the photosensitive material, improving the transparency of the material, ensuring high-precision exposure when irradiated with ultraviolet light, and enhancing its photoreaction efficiency. At the same time, polylactic acid has good melt fluidity and processability, which helps to form a uniform coating during the preparation process. Due to its high specific surface area and surface activity, nanocellulose can play a good dispersion and stabilization role in the polylactic acid matrix, preventing the aggregation and phase separation of polylactic acid molecules, thereby further improving the uniformity of the coating.

[0043] At the same time, the interaction between nanocellulose and polylactic acid enhances the binding force inside the coating, making the coating more stable during use and less likely to show phenomena such as delamination or local damage, thus ensuring the accuracy of the printed pattern.

[0044] Furthermore, in the materials of the printing plate, plant cellulose and lignin are also added.

[0045] Plant cellulose is a natural polymer material with strong film-forming properties and tensile strength. Its addition can enhance the crystallinity and strength of the photosensitive polymer, strengthen the rigidity and anti-aging properties of the photosensitive polymer, and the hydrogen bonds in the cellulose and the cross-linking of molecular chains in the polymer can improve the toughness and stability of the material, thereby improving the mechanical properties of the material.

[0046] Lignin, as a natural organic polymer, has strong mechanical properties. When added to the photosensitive polymer, it can improve the heat resistance and strength of the material, and at the same time has the property of resisting ultraviolet rays, which can effectively improve the ultraviolet resistance of the photosensitive polymer, thereby increasing the durability of the printing plate, especially maintaining good stability during multiple uses.

[0047] Moreover, since plant cellulose is a linear macromolecule formed by glucose molecules connected by β-1,4-glycosidic bonds, it has a high degree of crystallinity and mechanical strength. In the photosensitive polymer, the presence of plant cellulose enhances the crystallinity of the material. This crystallinity makes the molecular arrangement of the material more regular and compact, forming a crystalline region in the photosensitive coating, which not only improves the overall strength and stability of the material, but also this compact structure can, to a certain extent, hinder the penetration of ultraviolet rays into the material, reducing the direct attack of ultraviolet rays on the internal structure. Acting synergistically with the ultraviolet resistance of lignocellulose, it can maintain good performance and stability when exposed to ultraviolet light, extend the service life of the printing plate, and reduce the cost and resource waste caused by frequent replacement of the printing plate due to aging.

[0048] In addition, the above-mentioned chitosan, starch, polylactic acid, plant cellulose and lignin all have good biodegradability, which significantly improves the environmental friendliness of the photosensitive polymer and can be naturally degraded when discarded, reducing the burden on the environment.

[0049] Furthermore, there are a large number of hydroxyl groups and amino groups in the chitosan molecule, and starch molecules also contain abundant hydroxyl groups, while plant cellulose has numerous hydroxyl groups. Hydrogen bonds can be formed between these hydroxyl groups and amino groups. Hydrogen bond is a relatively strong intermolecular force. When chitosan contacts with starch and plant cellulose, the hydroxyl groups and amino groups between their molecules are connected to each other through hydrogen bonds, forming an intertwined network structure. This intertwined hydrogen bond network tightly binds the various components in the coating together, enhancing the overall cohesion and adhesion of the coating. When the coating is affected by external forces or environmental factors, due to the presence of hydrogen bonds, the stress can be dispersed and transmitted in this network instead of concentrating locally and causing cracking, thereby further enhancing the structural stability of the photosensitive coating and avoiding cracking or peeling.

[0050] Furthermore, a temperature-responsive crosslinking agent is added to the printed material. This crosslinking agent is inactive at room temperature, but when the temperature reaches a certain threshold, it can crosslink with the base material physically or chemically, thereby enhancing the strength and stability of the photosensitive polymer. Through this temperature-responsive mechanism, the printing plate can maintain good stability and strength during the printing process and can be appropriately repaired and strengthened under appropriate conditions.

[0051] The introduction of the temperature-responsive crosslinking agent enables the photosensitive material to adaptively adjust its crosslinking density according to changes in the ambient temperature. At high temperatures, the structure of the crosslinking agent becomes more compact, thereby enhancing the hardness and stability of the material; while at low temperatures, the molecular chains of the crosslinking agent relax, making the material more flexible. This adaptive property enables the photosensitive material to optimize its mechanical properties in different temperature environments, improve the curing accuracy, and avoid problems such as insufficient or excessive curing caused by temperature fluctuations; the above effects enable the printing plate, during the curing process, if the temperature rises, the crosslinking agent automatically strengthens the crosslinking to ensure the curing accuracy; while when the temperature drops, the crosslinking agent relaxes the crosslinking to avoid the material from becoming overly hardened and brittle.

[0052] Moreover, the temperature-responsive crosslinking agent can change its own structure and activity according to temperature changes. At a specific temperature, it will be activated to initiate a crosslinking reaction. For polylactic acid, its molecular chains are relatively regular and have a high degree of crystallinity, but there is still room for improvement in its thermal stability and mechanical strength. When the temperature-responsive crosslinking agent initiates a crosslinking reaction, new chemical bond connections will be formed between the polylactic acid molecular chains to construct a crosslinking network; this crosslinking network can restrict the movement of the polylactic acid molecular chains and reduce the amplitude of thermal movement of the molecular chains at high temperatures, thereby improving the thermal stability of polylactic acid. At the same time, the crosslinking network enhances the interaction between the molecular chains, enabling the material to better resist external forces and further strengthening the mechanical strength.

[0053] As a preparation material for zero-solvent inks, natural pigments are derived from plants and have good water solubility and natural environmental friendliness. They can provide bright colors for the ink while avoiding potential environmental pollution caused by chemical pigments; deionized water is a kind of pure water that has removed all ions and impurities and can help the pigments disperse better; among them. The molecular structure of natural pigments usually has hydrophilicity, and deionized water can better interact with these pigment molecules, enabling the pigments to be evenly dispersed in water, avoiding the aggregation and precipitation of pigment particles, and thus making the pigments evenly dispersed in deionized water, enhancing the stability of the ink and the color vividness of the printed pattern.

[0054] Lecithin, as a natural emulsifier, has both hydrophilic and hydrophobic groups in its molecular structure. The hydrophilic group can interact with the aqueous phase, while the hydrophobic group can bind to the surface of pigment particles. In this way, lecithin can wrap around the surface of pigment particles to form an emulsifying film, thereby reducing the interfacial tension between pigment particles, enabling them to be uniformly dispersed in the ink and preventing them from aggregating with each other.

[0055] Polyethylene glycol is a water-soluble polymer compound, and its molecular chain can form a steric hindrance effect in the ink. This means that polyethylene glycol molecules can occupy a certain space to prevent pigment particles from approaching and aggregating with each other. At the same time, polyethylene glycol can also increase the stability of the ink system through hydrogen bonding with water molecules, preventing the ink from stratifying or precipitating during storage.

[0056] Moreover, lecithin initially achieves the uniform dispersion of pigments, and polyethylene glycol further enhances the stability of this dispersed state on this basis. The combined action of the two enables pigment particles to remain uniformly dispersed in the ink for a long time and not aggregate, stratify or precipitate due to gravity, intermolecular interactions or environmental changes. This synergistic effect ensures the long-term stability of the ink during storage, enabling the ink to always maintain good performance during use, thereby providing a reliable basis for achieving excellent printing quality. During the printing process, the uniform and stable ink can accurately transfer colors and patterns, ensuring the color vividness, clarity and consistency of printed products.

[0057] Furthermore, natural resin and self-healing polyurethane are also added to the zero-solvent ink.

[0058] Natural resin has good adhesiveness and transparency, which can improve the adhesion and fluidity of the ink, enhance the stability and antioxidant capacity of the ink. Moreover, by interacting with pigments and other components in the ink base liquid, it enhances the adhesiveness and covering power of the ink, making the printed pattern more uniform and durable.

[0059] Self-healing polyurethane has the property of self-healing after being damaged. Through reversible chemical reactions within the molecule, when the surface or inside of the ink is damaged, it can self-repair, avoiding problems such as precipitation and stratification during long-term storage or transportation, thereby improving the stability and durability of the ink.

[0060] The antioxidant capacity of natural resin delays the aging of the ink, while self-healing polyurethane repairs the physical precipitation or stratification problems caused by aging. The combined action of the two enables the ink to exhibit higher reliability and durability under environmental pressures such as oxidation, light, and high temperature.

[0061] Moreover, the polar groups in natural resin molecules can combine with the hydrophilic groups on natural pigment molecules to form a stable bound state, preventing the aggregation of pigment particles. The natural resin forms a dense adhesion layer on the surface of the printed pattern, which combines with the adsorption of the molecular sieve, enabling the ink to adhere quickly and cure evenly, thereby improving the printing effect.

[0062] Lecithin forms an emulsion layer between the aqueous phase and the pigment, and polyethylene glycol further stabilizes the pigment dispersion system through intermolecular interactions; if aggregation or precipitation occurs later, the self-healing polyurethane restores the uniformity of the system through dynamic reorganization, thereby improving the quality of the ink.

[0063] Furthermore, graphene and silver nanocomposites are also added to the zero-solvent ink.

[0064] Graphene has ultra-high electrical conductivity, mechanical strength, and thermal conductivity. Silver nanomaterials have strong antibacterial properties and can effectively inhibit microbial growth. The combination of the electrical conductivity of graphene and the antibacterial properties of silver nanomaterials endows the ink with multiple functions during application. Graphene enhances the mechanical strength of the ink, while silver nanomaterials provide antibacterial protection, ensuring the stability and safety of the ink during long-term use; graphene and silver nanomaterials form a stable composite structure through physical cross-linking and chemical interactions. This enables the ink to exhibit better mechanical properties during printing and maintain stability during long-term use; at the same time, the surface of graphene provides an efficient carrier to ensure the uniform dispersion of silver nanomaterials and enhance their interaction with other components in the ink. The antibacterial effect of silver nanomaterials extends the shelf life and service life of the ink by preventing bacterial growth.

[0065] At the same time, the polar groups of natural resin can interact with graphene to enhance the adhesion of the ink. The dispersibility of graphene ensures the uniform distribution of resin and pigment in the ink, thereby ensuring the uniformity and durability of the printed pattern.

[0066] The antibacterial effect of silver nanomaterials is enhanced by binding with natural resin. The adhesion of the resin ensures the uniform distribution of silver nanomaterials, while the antibacterial effect of the silver particles themselves effectively prevents the growth of bacteria in the ink, which not only improves the antibacterial property of the ink but also enhances its adhesion and fluidity; the self-healing polyurethane repairs the structural damage in the ink through intermolecular reversible cross-linking reactions, while silver nanomaterials can prevent the growth of microorganisms during ink storage, avoiding ink contamination and ensuring the quality of the ink during long-term use.

[0067] On the basis of the disclosure of the above material components, further, the preferred material ratio is as follows: The following is the printing plate ratio:

[0068]

[0069]

[0070] Through a carefully designed ingredient ratio, the performance of the printing plate and the zero-solvent ink has been significantly optimized while ensuring a high degree of environmental friendliness. In the printing plate, the combination of natural chitosan and starch provides excellent antibacterial properties and film-forming properties, enhancing the stability of the photosensitive coating. The use of polylactic acid and nanocellulose improves the thermal stability and mechanical strength of the material, ensuring that the printing plate maintains good performance during high-temperature and high-strength printing processes. Natural materials such as plant cellulose and lignin enhance the UV resistance and anti-aging characteristics, extending the service life of the printing plate, ensuring the long-term stability and biodegradability of the material, reducing resource waste and environmental burden.

[0071] The following is the ratio of the zero-solvent ink:

[0072]

[0073] In the zero-solvent ink, natural pigments replace chemical pigments, ensuring the environmental friendliness and color reducibility of the ink. Deionized water as a solvent effectively avoids the use of harmful solvents, reducing VOC emissions and air pollution. The emulsifier lecithin and the stabilizer polyethylene glycol work together to ensure the uniform dispersion of the pigments and the long-term stability of the ink, avoiding precipitation or stratification problems. The addition of graphene and silver nanocomposites not only enhances the conductivity and mechanical strength of the ink but also provides antibacterial protection, extending the service life of the ink. With the support of these natural materials, the ink can meet the requirements of environmental friendliness and sustainable development while maintaining high performance.

[0074]

[0075] Through reasonable ratio and ingredient selection, these materials improve the functions of the printing plate and the ink while minimizing environmental impact, ensuring the efficient use of resources and natural degradability after disposal. This design not only improves the quality and stability of the product but also provides an effective solution for the greening of modern printing processes, achieving a good balance between performance and environmental protection.

[0076] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the design concept of the present invention shall be included in the protection scope of the present invention.

Claims

1. An environmentally friendly printing process, characterized in that: The following steps are involved: S1. Plate making: using a photosensitive polymer mixed with a biodegradable substrate as a printing plate; S2, prepare the printing press: install the printing plate made in S1 on the printing press and debug it; S3, preparing zero-solvent ink: according to the printing pattern and color requirements, using plant-extracted natural pigments, dispersing them in deionized water, and mixing them with additives to prepare zero-solvent ink, and then transporting the prepared ink to the ink storage mechanism in the printing press for use; S4, printing: the printing press in S2 transfers the zero-solvent ink prepared in S3 from the printing plate to the surface of the printing material through the printing roller to form a printed pattern; S5. Drying: Applying a molecular sieve coating on the surface of the printing material on which the printed pattern has been formed, and then drying and curing the printed pattern by natural wind.

2. An environmentally friendly printing process according to claim 1, characterized in that: The steps for preparing the photosensitive polymer described in S1 are as follows: A1. Preparing a mixed material: selecting mixed natural chitosan and starch as base materials, adding a crosslinking agent, a photoinitiator and a natural toughening agent thereto to obtain a mixed material; A2. Photosensitive coating: Use biodegradable plastic as the base, and then coat the mixed material on the base to form a photosensitive coating; A3. Pattern curing: Use ultraviolet light to expose the photosensitive coating to cure the pattern area, and then use an aqueous developer to wash and remove the unexposed part to finally obtain a clear pattern template.

3. An environmentally friendly printing process according to claim 2, characterized in that: The crosslinking agent is melamine crosslinking agent, the photoinitiator is benzophenone photoinitiator, and the natural toughening agent is glycerol.

4. The environmentally friendly printing process according to claim 1, characterized in that: The steps for preparing the zero solvent ink in S3 are as follows: B1, dispersing the natural pigment in deionized water, and then adding a natural solvent to obtain an ink base liquid; B2, adding an emulsifier and a stabilizer to the ink base liquid obtained in B1 to obtain a treated ink base liquid; B3, treating the ink base liquid obtained in B2 by ultrasonic emulsification technology to make the pigment particles in the ink base liquid have a particle size of 10-50 nanometers; B4. Perform three-stage filtration on the ink base liquid in B3 after ultrasonic emulsification technology to obtain pure and uniform zero-solvent ink.

5. An environmentally friendly printing process according to claim 4, characterized in that: The emulsifier used in B2 is lecithin, and the stabilizer is polyethylene glycol.

6. The environmentally friendly printing process according to claim 3, characterized in that: In step A1, polylactic acid and nanocellulose are also added to the mixed material.

7. An environmentally friendly printing process according to claim 6, characterized in that: In step A1, plant cellulose and lignin are also added to the mixed material.

8. The environmentally friendly printing process according to claim 5, characterized in that: In step B2, natural resin and self-healing polyurethane are added to the ink base liquid obtained in step B1.

9. The environmentally friendly printing process according to claim 7, characterized in that: In step A1, a temperature-responsive cross-linking agent is also added to the mixed material.

10. An environmentally friendly printing process according to claim 8, characterized in that: In step B2, graphene and nanosilver composite are added to the ink base liquid obtained in step B1.

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