Green printing process for packaging bottle

Abstract

The invention relates to the technical field of package printing, and discloses a green printing process for a package bottle, which comprises the following steps: S1, pretreatment of a base material: carrying out plasma cleaning on the surface of a pump head to remove impurities and improve the surface energy; s2, environment-friendly ink printing, wherein flexographic printing is conducted on the surface of the pretreated base material through water-based ink or UV curing ink; s3, low-temperature curing is conducted, specifically, sectional hot air drying or UV light curing is conducted at the temperature of 80-100 DEG C, and the curing time is shorter than or equal to 30 seconds; s4, film covering protection is conducted, specifically, a degradable pre-coating film is attached through a solvent-free type adhesive; and S5, post-processing is conducted, specifically, identification printing is completed through laser engraving or digital code spraying. The water-based ink or the UV-cured ink is adopted for flexographic printing, so that the environment-friendly requirement is met, and printed patterns are bright in color and high in definition and the transfer rate of the ink is increased by means of high dispersity of the nanoscale pigment and excellent film-forming property of the bio-based resin.

Description

Technical Field

[0001] The invention relates to the technical field of packaging and printing, in particular to a green printing process for packaging bottles. Background Art

[0002] In the field of packaging and printing technology, with increasingly stringent global environmental regulations and the growing awareness of sustainable development, green printing processes have become a key development direction in the bottle printing industry. This sector not only demands low pollution and low energy consumption, but also the ability to produce high-precision images and text on the bottle surface. In this technological environment, bottle printing is facing a technological revolution, moving from traditional solvent-based ink systems to environmentally friendly ink systems, and from low-resolution printing to high-precision printing.

[0003] Traditional bottle printing processes often face technical bottlenecks, hindering the balance between environmental performance and printing quality. Existing processes often use solvent-based inks, which contain significant amounts of volatile organic compounds (VOCs), often exceeding 50g / L. These inks contribute significantly to air pollution during production and fail to meet current environmental standards for green printing. Furthermore, due to insufficient pigment dispersibility and limited film-forming properties of resins, traditional ink systems often exhibit low color saturation and poor edge definition on printed designs. Printing accuracy errors often exceed 0.1mm, making them difficult to meet the demands for refined graphic printing on high-end bottle packaging. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a green printing process for packaging bottles, which solves the problem that the existing process does not meet the current environmental protection requirements of green printing and the printing accuracy error is generally greater than 0.1mm.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A green printing process for packaging bottles, comprising the following steps:

[0006] S1. Substrate pretreatment: Plasma cleaning of the pump head surface to remove impurities and increase surface energy;

[0007] S2. Environmentally friendly ink printing: Use water-based ink or UV curing ink for flexographic printing on the pre-treated substrate surface;

[0008] S3. Low temperature curing: perform segmented hot air drying or UV light curing at 80-100°C, curing time ≤ 30 seconds;

[0009] S4, film protection: use solvent-free adhesive to stick the degradable pre-coating film;

[0010] S5, post-processing: complete logo printing through laser engraving or digital inkjet coding;

[0011] The VOC content of the ink produced by the process is ≤50 g / L, the curing energy consumption is reduced by more than 40%, and the printing precision error is ≤0.1 mm.

[0012] By adopting the above technical solution, the surface energy of the substrate is increased to ≥50mN / m through plasma cleaning, and the contact angle with water-based ink is reduced to ≤15°, which significantly improves the surface activity, makes the ink spread evenly, and increases the adhesion by more than 3 times, laying the foundation for achieving a printing accuracy of ≤0.1mm; environmentally friendly ink printing uses water-based ink or UV curing ink, among which the water-based ink contains nano-pigment dispersion and bio-based acrylic resin. The high dispersibility of nano-pigments solves the problem of agglomeration of traditional pigment particles, and the bio-based resin ensures uniform and dense film formation, which significantly improves the ink transfer rate and controls the printing accuracy error to ≤0.1mm. At the same time, the VOC content of the ink is ≤50g / L, cutting off VOC pollution at the source; low-temperature curing is achieved through 80-100℃ segmented hot air drying Or UV light curing, curing time ≤ 30 seconds, so that the total energy consumption in the curing stage is reduced by more than 40% compared with the traditional process, and the precise gradient temperature control avoids thermal deformation of the substrate (thermal deformation rate < 0.05%), ensuring the stability of printing accuracy; the lamination protection adopts solvent-free adhesive to bond with degradable pre-coated film, the adhesive has no solvent volatilization, the pre-coated film biodegradation rate ≥ 90%, and the high peel strength and low oxygen permeability effectively resist external erosion, prevent the printing layer from wear, and maintain the integrity of the pattern for a long time; post-processing completes the logo printing through fiber laser engraving or digital inkjet coding. Laser engraving and digital inkjet coding technologies respectively achieve high-precision engraving and printing, which meets the refined needs of high-end packaging bottles for anti-counterfeiting labels and traceability information, and solves the contradiction between "high pollution" and "low precision" of traditional processes.

[0013] Preferably, the water-based ink comprises a nano-scale pigment dispersion and a bio-based acrylic resin, and the solid content thereof is ≥60%.

[0014] Preferably, the low-temperature curing stage adopts a heating method coupled with infrared radiation and circulating hot air, and the temperature gradient is controlled to be 80°C → 90°C → 100°C, and each stage is maintained for 5-8 seconds.

[0015] Preferably, the process parameters of the plasma cleaning are: power 300-500W, gas is argon-oxygen mixture, and processing time is 30-60 seconds.

[0016] Preferably, the solvent-free adhesive is a composite of polyurethane-modified epoxy resin and starch-based tackifier, and the viscosity is controlled at 2000-3000 cps.

[0017] Preferably, the line count of the anilox roller of the flexographic printing is 200-250 LPI, and the printing pressure is 0.15-0.25 MPa.

[0018] Preferably, the degradable pre-coating film is a PLA / PBAT blend film with a thickness of 12-18 μm and an oxygen permeability of ≤5 cm 3 / (m 2 ·24h·0.1MPa).

[0019] Preferably, the laser engraving adopts a fiber laser, wherein the wavelength is 1064nm, the power is 20-30W, and the engraving depth is 10-20μm.

[0020] Preferably, the method further comprises an online detection step: monitoring the printing color difference and pattern integrity in real time through a CCD visual system.

[0021] Preferably, the process as a whole meets the following synergistic parameters: the surface energy of the substrate after plasma cleaning is ≥50mN / m, the contact angle with the water-based ink is ≤15°, the total energy consumption in the curing stage is ≤0.8kW·h / m2, and the thermal deformation rate of the substrate is <0.05%, the peel strength between the printed layer and the pre-coated film is ≥3.5N / 15mm, and the biodegradation rate is ≥90%.

[0022] The present invention provides a green printing process for packaging bottles, which has the following beneficial effects:

[0023] 1. The present invention adopts water-based ink or UV curable ink for flexographic printing, wherein the water-based ink contains nano-scale pigment dispersion and bio-based acrylic resin. While achieving environmental protection requirements, the high dispersibility of nano-scale pigment and the excellent film-forming properties of bio-based resin make the printed pattern colorful and clear, the ink transfer rate is improved, and the printing accuracy error is ≤0.1mm, taking into account both environmental protection and printing performance.

[0024] 2. The present invention performs segmented hot air drying or UV light curing at 80-100°C during the warm curing stage, with a curing time of ≤30 seconds. The invention adopts a heating method coupled with infrared radiation and circulating hot air, which reduces the curing energy consumption and effectively controls the thermal deformation rate of the substrate to <0.05%. This not only achieves energy saving effects, but also avoids the adverse effects of high temperature on the substrate, ensuring the structural stability of the packaging bottle and the quality of the printed layer.

[0025] 3. The present invention uses a plasma cleaning process to effectively remove impurities on the surface of the pump head and significantly increase the surface energy of the substrate to ≥50mN / m, greatly reducing the contact angle with the water-based ink to ≤15°, significantly improving the surface activity of the substrate, and enhancing the adhesion between the ink and the substrate. This provides ideal surface conditions for subsequent printing processes, ensuring that the ink can adhere evenly and firmly to the substrate surface, thereby improving the stability of printing quality.

[0026] 4. The post-processing of the present invention completes the logo printing through laser engraving or digital inkjet coding. Laser engraving uses a fiber laser, and the parameters such as wavelength, power and engraving depth are reasonably set. It can accurately engrave a clear anti-counterfeiting logo, and the engraving depth is appropriate, which not only ensures the clarity and legibility of the logo, but also does not affect the structural strength of the product; digital inkjet coding is flexible and convenient, and can quickly print batch information and other content. Both methods can meet different logo requirements, improve production efficiency and the accuracy and aesthetics of the logo. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a green printing process flow chart for packaging bottles. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Please see the attached Figure 1 The embodiment of the present invention provides a green printing process for packaging bottles, comprising the following steps:

[0030] S1. Substrate pretreatment: Plasma cleaning of the pump head surface to remove impurities and increase surface energy;

[0031] S2. Environmentally friendly ink printing: Use water-based ink or UV curing ink for flexographic printing on the pre-treated substrate surface;

[0032] S3. Low temperature curing: perform segmented hot air drying or UV light curing at 80-100°C, curing time ≤ 30 seconds;

[0033] S4, film protection: use solvent-free adhesive to stick the degradable pre-coating film;

[0034] S5, post-processing: complete logo printing through laser engraving or digital inkjet coding;

[0035] The VOC content of the ink produced by the process is ≤50 g / L, the curing energy consumption is reduced by more than 40%, and the printing precision error is ≤0.1 mm.

[0036] Specifically, when implementing this process, the cosmetic pump head made of ABS or PP is first plasma cleaned using a radio frequency plasma generator with an operating frequency of 13.56 MHz and an output power of 380 W. A mixed gas of argon and oxygen is introduced with a flow ratio of 3:1 and a total flow of 400 sccm. The treatment is carried out for 45 seconds under a vacuum of 50 Pa. The surface energy of the substrate is increased from 38 mN / m before treatment to 54 mN / m, and the contact angle is reduced from 110° to 12°. XPS testing shows that the surface carbon content is reduced by 82%. Subsequently, customized water-based ink was used for flexographic printing. The ink consists of nano-grade titanium dioxide with an average particle size of 90nm, an addition amount of 28%, bio-based polyurethane resin (solid content of 62%, hydroxyl value of 45mgKOH / g) and an environmentally friendly defoamer (BYK-022, addition amount 0.3%). Printing was carried out under a pressure of 0.22MPa using a high-precision ceramic anilox roller (line count 230LPI, cell depth 28μm). The measured ink transfer rate reached 88%, and the printing line width control accuracy was ±0.07mm.

[0037] The curing stage adopts a modular design. When hot air curing is used, it is executed in sequence in a three-stage gradient temperature control system: the first stage is 80℃ hot air circulation, wind speed 1.2m / s, time 10 seconds, to make the ink initially form a film; the second stage is 95℃ infrared assisted drying, radiation power density 4.5kW / m 2 , time 12 seconds, promote resin cross-linking; the third section 100 ℃ gradient cooling, cooling rate 5 ℃ / s, time 8 seconds, eliminate internal stress, the overall energy consumption 0.68kW·h / m 2 If UV curing is used, a 395nm wavelength LED array with a light intensity of 1500mW / cm 2 The film was irradiated for 8 seconds, with the photoinitiator (TPO-L) concentration controlled at 1.8%. During the lamination process, a solvent-free epoxy-starch composite adhesive (viscosity 2800 cps, solids content 98%) was evenly applied to the surface of the PLA-based biodegradable film using a metered double-roll coater. Lamination was achieved at a pressure of 0.18 MPa and a line speed of 10 m / min. After aging at 50°C for 24 hours, the measured peel strength was 3.6 N / 15 mm.

[0038] In the post-processing stage, laser engraving or digital inkjet coding is selected according to product requirements: a fiber laser (peak power 30W, pulse width 100ns) is used to engrave an anti-counterfeiting mark with a depth of 18μm on the top of the pump head; or a piezoelectric inkjet printer (ink droplet diameter 35μm) is used to print batch information.

[0039] The water-based ink comprises a nano-scale pigment dispersion and a bio-based acrylic resin, and the solid content thereof is greater than or equal to 60%.

[0040] Specifically, during the ink formulation process, nano-scale titanium dioxide is used as the core pigment component, with an average particle size of 85 nanometers and a maximum particle size of no more than 100 nanometers. The rutile crystal form is selected with a purity of at least 99.8%. The pigment is pre-mixed with a bio-based acrylic resin in a mass ratio of 32:65. The resin is synthesized from a castor oil derivative, has a number-average molecular weight of 15,000, and an acid value strictly controlled below 3 mg KOH / g. To optimize the ink's leveling properties, 0.8% of a non-ionic polyether-modified siloxane wetting agent with a hydrophilic-lipophilic balance of 13.5 is added. Deionized water is used to adjust the system viscosity to 35 to 40 seconds, and the viscosity is measured using the Coating-4 Cup method at 25 degrees Celsius.

[0041] The fine treatment was carried out through sand milling dispersion process, using zirconium oxide beads with a diameter of 0.3 mm as the grinding medium, and the treatment was continued for 120 minutes at a linear speed of 12 meters per second, and finally a water-based ink system with a solid content of 63.5% was obtained.

[0042] The water-based ink comprises a nano-scale pigment dispersion and a bio-based acrylic resin, and the solid content thereof is greater than or equal to 60%.

[0043] Specifically, the water-based ink uses nano-scale titanium dioxide as a pigment dispersion, with an average particle size controlled within the range of 80-90 nanometers, a D90 particle size distribution not exceeding 100 nanometers, a preferred rutile crystal structure, and a purity of not less than 99.5%. This nano-scale pigment undergoes a special surface treatment process to achieve a surface hydroxyl content of 2.5-3.0 per nm. 2 , ensuring good compatibility with the resin system. The bio-based acrylic resin is an environmentally friendly resin synthesized from renewable castor oil. Its number average molecular weight is controlled within the range of 12,000-18,000, its acid value does not exceed 5 mgKOH / g, and its glass transition temperature is set between 45-55°C. A controlled free radical polymerization process is used during the resin synthesis process to ensure a molecular weight distribution index (PDI) ≤ 1.5. The mass ratio of nano-pigment to bio-based resin in the ink formula is controlled within the range of 30-35:60-65, and 0.5-1.0% of a polyether-modified silicone wetting agent is added, with an HLB value controlled between 12-14. Through high-speed dispersion and sand grinding process, using 0.3-0.5mm zirconium oxide beads as grinding media, processing at a linear speed of 10-15m / s for 90-150 minutes, the final ink solid content reaches 60-65%, fineness ≤5μm, and Stormer viscosity is controlled in the range of 9000-11000cP.

[0044] The low-temperature curing stage adopts a heating method coupled with infrared radiation and circulating hot air, and the temperature gradient is controlled to be 80°C → 90°C → 100°C, and each stage is maintained for 5-8 seconds.

[0045] Specifically, a special multi-mode coupled heating system is used in the low-temperature curing stage. The system consists of a medium-wave infrared radiation unit and a circulating hot air unit. The infrared radiation unit uses a silicon carbide radiation tube with a wavelength of 2.5-4μm and an adjustable power density of 3-6kW / m 2 The hot air circulation unit is equipped with a centrifugal fan, and the wind speed can be precisely adjusted within the range of 1-3m / s. The curing process adopts a three-stage gradient temperature control: the first stage is set at 80±2℃, and 70% hot air and 30% infrared composite heating are maintained for 6±1 seconds to make the ink surface initially form a film; the second stage is heated to 90±1℃, and 50% hot air and 50% infrared collaborative heating are used, and maintained for 7±0.5 seconds to promote the orderly arrangement of the resin molecular chains; the third stage reaches 100±1℃, and switches to 30% hot air and 70% infrared combined heating, and maintains for 6±0.5 seconds to complete the final cross-linking. The entire curing process adopts a PID intelligent temperature control system, and the temperature fluctuation is controlled within ±1.5℃. The conveyor belt speed is matched to 1.2-1.5m / min to ensure the effective processing time of each temperature zone.

[0046] The process parameters of the plasma cleaning are: power 300-500W, gas is argon-oxygen mixed gas, and processing time is 30-60 seconds.

[0047] Specifically, the plasma cleaning process uses a radio frequency glow discharge plasma treatment system, which is equipped with a 13.56MHz radio frequency power supply. The output power is continuously adjustable in the range of 300-500W. During the treatment process, a mixture of high-purity argon and oxygen is introduced, where the argon flow rate is controlled at 300-450sccm, and the oxygen flow rate is correspondingly 100-150sccm. The volume ratio of the two is strictly maintained at a ratio of 3:1. The working pressure of the vacuum reaction chamber is maintained in the range of 50-100Pa, and the distance between the substrate and the electrode is set to 50-80mm. The treatment time is adjusted between 30-60 seconds according to the material of the substrate and the initial degree of contamination. It is recommended to treat ABS material for 40-45 seconds and PP material for 50-55 seconds. The treated substrate can maintain an effective activation state for more than 120 minutes at room temperature, meeting the process requirements of subsequent printing processes.

[0048] The solvent-free adhesive is a compound of polyurethane-modified epoxy resin and starch-based tackifier, and the viscosity is controlled at 2000-3000 cps.

[0049] Specifically, the solvent-free adhesive uses a special polyurethane-modified epoxy resin as a matrix material. The resin is prepared by a block copolymerization process of bisphenol A epoxy resin and an isocyanate-terminated polyurethane prepolymer. Its epoxy value is 0.45-0.55eq / 100g, and the NCO content is controlled at 1.8-2.2wt%. The starch-based thickener is prepared by acid hydrolysis modification of cassava starch, with a molecular weight distribution of 5000-8000Da and a degree of substitution of 0.02-0.05. The addition amount is 15-20wt% of the total system. During compounding, a high-speed dispersion process is adopted, and the mixture is stirred at a speed of 800-1000rpm at 60-70°C for 45-60 minutes. The viscosity of the final adhesive is measured at 25°C using a Brookfield DV-II+ viscometer, and the viscosity is stable within the range of 2500±200cps (rotor model LV-3, speed 30rpm).

[0050] The line count of the anilox roller of the flexographic printing is 200-250 LPI, and the printing pressure is 0.15-0.25 MPa.

[0051] Specifically, the flexographic printing process utilizes a high-precision laser-engraved ceramic anilox roller with a 60-degree hexagonal cell structure. The anilox line count is controlled within the range of 220-240 lines per inch, the cell volume is 5.5-6.0 BCM, and the cell depth is 18-22 μm. The printing unit is equipped with an electronic pressure control system, which stabilizes the printing pressure between 0.18 and 0.22 MPa, driven by a servo motor with an adjustment accuracy of ±0.01 MPa. A photosensitive resin plate with a hardness of 72-75 Shore A is used, the plate thickness is 1.14 mm, and the relief depth is 0.45-0.50 mm. During the actual printing process, the scraper angle is set at 55-60 degrees, and the contact pressure with the anilox roller is maintained at 0.10-0.12 MPa, achieving an ink transfer rate of 85-92%. Printing speed is controlled at 60-80 m / min, and a constant temperature circulation system maintains the ink temperature at 25±1°C.

[0052] The degradable pre-coating film is a PLA / PBAT blend film with a thickness of 12-18 μm and an oxygen permeability of ≤5 cm 3 / (m 2 ·24h·0.1MPa)

[0053] Specifically, the biodegradable pre-coating film utilizes a blend of polylactic acid (PLA) and polybutylene adipate (PBAT). PLA is L-polylactic acid (LA) with an optical purity of ≥96% and a weight-average molecular weight of 150,000-180,000 Daltons; PBAT is a modified copolyester with a degree of esterification of ≥99% and a melt index of 3.5-4.5 g / 10 min (190°C, 2.16 kg). The film is prepared via a twin-screw extrusion casting process, where PLA and PBAT are blended in a 70:30 mass ratio, with the addition of 0.5-1.0% epoxy chain extender and 0.3-0.5% nano-silica nucleating agent. The film is then molded at a processing temperature of 170-185°C. An online thickness gauge monitors the film's thickness in real time, precisely controlling it to within 15±1.5 μm. Electron microscopy reveals a surface roughness Ra ≤0.05 μm.

[0054] The laser engraving adopts a fiber laser, wherein the wavelength is 1064nm, the power is 20-30W, and the engraving depth is 10-20μm.

[0055] Specifically, a 1064nm near-infrared wavelength laser is used, and this wavelength characteristic enables it to be effectively absorbed by most plastic materials; the output power is precisely controlled within the range of 20-30W, ensuring sufficient energy density to achieve material vaporization while avoiding thermal damage to the substrate caused by excessive power; the engraving depth is set to a reasonable range of 10-20μm, which ensures the clarity and legibility of the logo without affecting the structural strength of the product.

[0056] It also includes an online inspection step: real-time monitoring of printing color difference (ΔE≤1.5) and pattern integrity through a CCD vision system.

[0057] Specifically, the online inspection system utilizes a high-resolution CCD industrial camera and a multispectral lighting unit as a visual inspection platform. Equipped with a 5-megapixel global shutter CMOS sensor and a telecentric lens, it achieves positioning accuracy of ±0.01mm and a field of view covering 150×200mm at a working distance of 600mm. The inspection light source utilizes a combination of an RGB LED array and an infrared auxiliary light source, with an adjustable brightness range of 3,000-10,000 lux, ensuring stable image contrast across various printing backgrounds.

[0058] The system uses machine vision algorithms to analyze captured images in real time. For color difference detection, it employs CIELab color space conversion technology, using standard samples as a benchmark to calculate the L, a, and b* values ​​of the printed pattern in milliseconds. Its ΔE value detection accuracy reaches ±0.1, and the detection frequency is 300-500 samples per minute. Pattern integrity detection combines edge extraction with template matching, using the Sobel operator to detect pattern outlines. Combined with sub-pixel positioning technology, it can identify printing defects as small as 0.05mm, including broken lines, burrs, dirty spots, and other anomalies.

[0059] Inspection data is uploaded to the MES system in real time via industrial Ethernet. When the ΔE value exceeds 1.5 or the pattern integrity falls below 99.5%, the system automatically triggers an audible and visual alarm and records the defect location. Simultaneously, inspection results are fed back to the printing press control system, enabling closed-loop adjustments to parameters such as ink viscosity and printing pressure.

[0060] The overall process meets the following synergistic parameters: substrate surface energy after plasma cleaning ≥ 50 mN / m, contact angle with water-based ink ≤ 15°, total energy consumption during curing ≤ 0.8 kW·h / m 2 , and the thermal deformation rate of the substrate is less than 0.05%, the peel strength between the printing layer and the pre-coating film is ≥3.5N / 15mm, and the biodegradation rate is ≥90%.

[0061] Specifically, plasma cleaning can achieve an activation effect of surface energy ≥50mN / m, combined with the ink contact angle characteristic of ≤15°, which increases the spreading speed of water-based ink by 40% and the adhesion by more than 3 times.

[0062] Example 1

[0063] Cosmetic pump head printing with medium parameter configuration

[0064] Substrate Pretreatment: An ABS cosmetic pump head was treated using a radio frequency plasma device. The operating frequency was set at 13.56 MHz, the output power was 380 W, and argon and oxygen were introduced (at a flow ratio of 3:1, for a total flow rate of 400 sccm) under a vacuum of 50 Pa for 45 seconds. After treatment, the substrate's surface energy increased to 54 mN / m, and the contact angle decreased to 12°.

[0065] Environmentally friendly ink printing: Customized water-based ink is used, consisting of nano-titanium dioxide (average particle size 90nm, 28% addition), bio-based polyurethane resin (62% solids content), and 0.3% BYK-022 defoamer. Flexographic printing is performed using a 230 LPI ceramic anilox roller at a printing pressure of 0.22 MPa, achieving an ink transfer rate of 88% and a line width control accuracy of ±0.07 mm.

[0066] Low-temperature curing: A three-stage gradient temperature control system is used. In the first stage, hot air circulation is carried out at 80°C (wind speed 1.2m / s) for 10 seconds; in the second stage, infrared assisted drying is used at 95°C (radiation power density 4.5kW / m2) for 12 seconds; in the third stage, gradient cooling is carried out at 100°C (cooling rate 5°C / s) for 8 seconds. The overall energy consumption is 0.68kW·h / m 2 .

[0067] Lamination protection: A solvent-free epoxy-starch composite adhesive with a viscosity of 2800 cps was evenly coated on the surface of a 15μm-thick PLA-based biodegradable film. Lamination was completed at a pressure of 0.18 MPa and a line speed of 10 m / min. After aging at 50°C for 24 hours, the peel strength was measured to be 3.6 N / 15 mm.

[0068] Post-processing: A fiber laser (peak power 30W, pulse width 100ns) was used to engrave an anti-counterfeiting mark with a depth of 18μm on the top of the pump head.

[0069] Online detection: Real-time monitoring through CCD visual system, printing color difference ΔE≤1.5, pattern integrity ≥99.5%.

[0070] The synergistic parameters meet the standards: surface energy is 54mN / m, contact angle is 12°, substrate thermal deformation rate is less than 0.05%, and biodegradation rate is ≥90%.

[0071] Example 2

[0072] Low-energy and environmentally friendly printing process

[0073] Substrate pretreatment: For PP material substrates, plasma cleaning with a power of 300W is used, and an argon-oxygen mixed gas (flow ratio 3:1, total flow rate 300sccm) is introduced. The treatment is carried out at a vacuum degree of 80Pa for 60 seconds. After treatment, the surface energy can reach 50mN / m.

[0074] Environmentally friendly ink printing: A water-based ink with a 60% solids content was used. The nano-titanium dioxide with an average particle size of 80 nm was placed in a 30:65 mass ratio with bio-based acrylic resin. A 0.5% polyether-modified silicone wetting agent was added. Printing was performed using a 200 LPI anilox roller at a pressure of 0.15 MPa, achieving an ink transfer efficiency of 85%.

[0075] Low temperature curing: infrared and hot air coupled heating method is used, the temperature gradient is 80℃ (hold for 8 seconds) → 90℃ (hold for 5 seconds) → 100℃ (hold for 7 seconds), the total curing time is 20 seconds, and the energy consumption is 0.75kW·h / m 2 .

[0076] Coating protection: Use polyurethane modified epoxy resin adhesive with a viscosity of 2000cps, and a composite PLA / PBAT blend film with a thickness of 12μm (oxygen permeability ≤5cm 3 / (m 2 ·24h·0.1MPa)), the peel strength after aging is 3.5N / 15mm.

[0077] Post-processing: Use a digital inkjet printer (ink droplet diameter 35μm) to print batch information.

[0078] The synergistic parameters met the standards: contact angle 15°, curing energy consumption reduced by 45%, printing accuracy error 0.08mm, and biodegradation rate 92%.

[0079] Example 3

[0080] Low-energy and environmentally friendly printing process

[0081] Substrate pretreatment: For PP material substrates, plasma cleaning with a power of 300W is used, and an argon-oxygen mixed gas (flow ratio 3:1, total flow rate 300sccm) is introduced. The treatment is carried out at a vacuum degree of 80Pa for 60 seconds. After treatment, the surface energy can reach 50mN / m.

[0082] Environmentally friendly ink printing: A water-based ink with a 60% solids content was used. The nano-titanium dioxide with an average particle size of 80 nm was placed in a 30:65 mass ratio with bio-based acrylic resin. A 0.5% polyether-modified silicone wetting agent was added. Printing was performed using a 200 LPI anilox roller at a pressure of 0.15 MPa, achieving an ink transfer efficiency of 85%.

[0083] Low temperature curing: infrared and hot air coupled heating method is used, the temperature gradient is 80℃ (hold for 8 seconds) → 90℃ (hold for 5 seconds) → 100℃ (hold for 7 seconds), the total curing time is 20 seconds, and the energy consumption is 0.75kW·h / m 2 .

[0084] Coating protection: Use polyurethane modified epoxy resin adhesive with a viscosity of 2000cps, and a composite PLA / PBAT blend film with a thickness of 12μm (oxygen permeability ≤5cm 3 / (m 2 ·24h·0.1MPa)), the peel strength after aging is 3.5N / 15mm.

[0085] Post-processing: Use a digital inkjet printer (ink droplet diameter 35μm) to print batch information.

[0086] The synergistic parameters met the standards: contact angle 15°, curing energy consumption reduced by 45%, printing accuracy error 0.08mm, and biodegradation rate 92%.

[0087]

[0088] The VOC (Volatile Organic Compound) content of ink refers to the mass percentage of volatile organic compounds in the ink, measured in g / L. Inks with high VOC content release harmful gases during production, polluting the environment and endangering human health.

[0089] Printing accuracy error: The deviation between the actual size of the printed pattern and the designed size, measured in mm. The smaller the error, the higher the clarity and fineness of the printed image.

[0090] Curing energy consumption: The energy consumed during the curing stage (hot air drying or UV curing), measured in kW·h / m². Energy consumption directly affects production costs and carbon emissions.

[0091] Biodegradation rate: The percentage (%) of a material that is broken down into harmless substances by microorganisms in the natural environment. A high biodegradation rate can reduce the long-term environmental pollution caused by plastic waste.

[0092] Summary: The above comparison items can intuitively reflect that the process of the present invention is significantly superior to traditional technologies in terms of environmental protection (low VOC, high degradation rate), printing quality (high precision) and energy efficiency (low temperature and energy saving), achieving a balance between green printing and industrial performance.

[0093] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A green printing process for packaging bottles, characterized in that: The following steps are involved: S1. Substrate pretreatment: Plasma cleaning of the pump head surface to remove impurities and increase surface energy; S2. Environmentally friendly ink printing: Use water-based ink or UV curing ink for flexographic printing on the pre-treated substrate surface; S3. Low temperature curing: perform segmented hot air drying or UV light curing at 80-100°C, curing time ≤ 30 seconds; S4, film protection: use solvent-free adhesive to stick the degradable pre-coating film; S5, post-processing: complete logo printing through laser engraving or digital inkjet coding; The VOC content of the ink produced by the process is ≤50 g / L, the curing energy consumption is reduced by more than 40%, and the printing precision error is ≤0.1 mm.

2. A green printing process for packaging bottles according to claim 1, characterized in that: The water-based ink comprises a nano-scale pigment dispersion and a bio-based acrylic resin, and the solid content thereof is greater than or equal to 60%.

3. A green printing process for packaging bottles according to claim 1, characterized in that: The low-temperature curing stage adopts a heating method coupled with infrared radiation and circulating hot air, and the temperature gradient is controlled to be 80°C → 90°C → 100°C, and each stage is maintained for 5-8 seconds.

4. A green printing process for packaging bottles according to claim 1, characterized in that: The process parameters of the plasma cleaning are: power 300-500W, gas is argon-oxygen mixed gas, and processing time is 30-60 seconds.

5. The green printing process for packaging bottles according to claim 1, characterized in that: The solvent-free adhesive is a compound of polyurethane-modified epoxy resin and starch-based tackifier, and the viscosity is controlled at 2000-3000 cps.

6. A green printing process for packaging bottles according to claim 1, characterized in that: The line count of the anilox roller of the flexographic printing is 200-250 LPI, and the printing pressure is 0.15-0.25 MPa.

7. A green printing process for packaging bottles according to claim 1, characterized in that: The degradable pre-coating film is a PLA / PBAT blend film with a thickness of 12-18 μm and an oxygen permeability of ≤5 cm 3 / (m 2 ·24h·0.1MPa).

8. The green printing process for packaging bottles according to claim 1, characterized in that: The laser engraving adopts a fiber laser, wherein the wavelength is 1064nm, the power is 20-30W, and the engraving depth is 10-20μm.

9. The green printing process for packaging bottles according to claim 1, characterized in that: It also includes an online inspection step: real-time monitoring of printing color difference and pattern integrity through a CCD vision system.

10. A green printing process for packaging bottles according to any one of claims 1 to 9, characterized in that: The overall process meets the following synergistic parameters: substrate surface energy after plasma cleaning ≥ 50 mN / m, contact angle with water-based ink ≤ 15°, total energy consumption during curing ≤ 0.8 kW·h / m 2 , and the thermal deformation rate of the substrate is less than 0.05%, the peel strength between the printing layer and the pre-coating film is ≥3.5N / 15mm, and the biodegradation rate is ≥90%.

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