A water-free digital printing process and application thereof

Abstract

The application provides a water-free digital printing process and application thereof. The water-free digital printing process comprises the following steps: performing plasma surface modification treatment on polyester fabric to be printed; within 30 minutes after the surface modification treatment is completed, using a disperse dye ink to perform digital inkjet printing on the polyester fabric; and sequentially performing pre-drying and high-temperature heat fixing on the printed polyester fabric. Through the plasma surface modification treatment, high-energy active particles (such as electrons, ions, free radicals, etc.) in the plasma are used to bombard the surface of the polyester fiber, to produce a dual effect of physical etching and chemical oxidation. The physical etching forms micro-pits and rough structures in the nanometer to micrometer range on the fiber surface, increases the mechanical anchoring sites of the ink, and inhibits the spreading of the ink; the chemical oxidation breaks the C-C and C-H bonds on the fiber surface, introduces polar oxygen-containing functional groups such as hydroxyl, carboxyl and carbonyl groups, and changes the hydrophobicity of the fiber surface to hydrophilicity.

Description

Technical Field

[0001] This application relates to the field of textile printing, specifically to a waterless digital printing process and its application. Background Technology

[0002] Polyester (PET) fabrics dominate the textile printing industry due to their excellent mechanical properties, dimensional stability, and low cost. Digital inkjet printing technology, with its advantages of high precision, rapid sampling, and on-demand customization, is gradually replacing traditional flatbed and rotary screen printing processes. However, due to the compact molecular chain structure, high crystallinity, and lack of polar groups on the surface of polyester fibers, they exhibit extremely strong hydrophobicity. This inherent hydrophobicity leads to poor wetting of disperse dye inks on the fabric surface, resulting in problems such as uncontrollable ink spreading, low dye adsorption efficiency, and insufficient color intensity when directly inkjet printing, which seriously restricts the quality of digitally printed polyester fabric products.

[0003] In existing technologies, pretreatment of polyester fabrics is typically required to improve the quality of digital printing. Common pretreatment methods include alkali reduction treatment and chemical paste coating. Alkali reduction treatment hydrolyzes the ester bonds on the PET surface using a high-concentration NaOH aqueous solution, increasing surface roughness and hydrophilicity. However, this method requires extensive washing and acid neutralization steps, resulting in a long process flow, damage to fabric strength, and the generation of large amounts of highly alkaline and difficult-to-treat wastewater. Chemical paste coating involves applying pastes such as sodium alginate and polyvinyl alcohol to the fabric surface. While this can improve printing accuracy, post-printing washing is necessary to remove the paste, similarly leading to water waste and wastewater treatment pressure.

[0004] In summary, existing technologies all suffer from common drawbacks such as numerous wet processing steps, large wastewater discharge, high chemical residue risks, and lengthy process chains. Therefore, providing a pretreatment method for digital printing on polyester fabrics that effectively improves color intensity and printing accuracy while achieving zero wastewater discharge, eliminating chemical residue risks, and significantly shortening the process chain has become a key technical problem that needs to be solved in this field. Summary of the Invention

[0005] To address the problems of complex pretreatment processes, large wastewater discharge, and impact on fabric performance in existing technologies for digital printing of polyester fabrics, this application provides a waterless digital printing process and its application.

[0006] The first aspect of this application provides a waterless digital printing process, comprising the following steps: subjecting the polyester fabric to be printed to plasma surface modification treatment; within 30 minutes after the surface modification treatment is completed, digital inkjet printing is performed on the polyester fabric using disperse dye ink; and the printed polyester fabric is then pre-dried and subjected to high-temperature heat curing in sequence.

[0007] This application utilizes plasma surface modification treatment, employing high-energy active particles (such as electrons, ions, and free radicals) in plasma to bombard the surface of polyester fibers, producing a dual effect of physical etching and chemical oxidation. Physical etching forms nano- to micro-scale micropits and rough structures on the fiber surface, increasing the mechanical anchoring sites for ink and inhibiting ink spreading. Chemical oxidation breaks the C-C and CH bonds on the fiber surface, introducing polar oxygen-containing functional groups such as hydroxyl, carboxyl, and carbonyl groups, transforming the fiber surface from hydrophobic to hydrophilic. This abrupt change in surface properties improves the wetting and penetration ability of disperse dye inks on the fabric surface, thereby significantly enhancing the color intensity (K / S value) and pattern accuracy of printing. In particular, this application specifies that printing should be performed within 30 minutes after the treatment is completed. This is because the active groups introduced by plasma modification are in a high-energy metastable state, and over time, molecular chain rearrangement occurs, with polar groups flipping inward, leading to the restoration of surface hydrophobicity (i.e., the hydrophobic recovery effect). By strictly limiting the printing time, ink deposition is ensured to be completed within the window of optimal surface hydrophilicity, thus guaranteeing the stability of printing quality. Furthermore, this process requires no water washing and no addition of chemical auxiliaries, achieving clean production.

[0008] Furthermore, the plasma surface modification treatment is carried out under atmospheric pressure using dielectric barrier discharge plasma, with air as the working gas. Atmospheric pressure dielectric barrier discharge (DBD) technology does not require an expensive vacuum system, enabling continuous roller-to-roll processing with high production efficiency; it directly uses air as the working gas, eliminating the need for additional purchase and storage of industrial gases, further reducing production costs, and the process generates no waste emissions, aligning with the concept of green manufacturing.

[0009] Furthermore, the power density of the plasma treatment is 0.5-2 W / cm². 2 The processing time is 15-60 seconds, and the electrode spacing is 1-5 mm. Within this range of process parameters, a better surface modification effect can be obtained. If the power density is too low or the time is too short, the number of polar groups introduced to the surface will be insufficient, and the improvement in hydrophilicity will not be obvious; if the power density is too high or the time is too long, it may lead to excessive etching of the fiber surface, damaging the mechanical properties of the fabric. Specifically, the preferred power density of the plasma treatment is 1 W / cm². 2 The preferred processing time is 30-45 seconds, and the preferred electrode spacing is 3mm. Under these preferred parameters, the hydrophilicity of the fabric surface is maximized, and the strength retention rate is highest.

[0010] Furthermore, after the surface modification treatment is completed and before the digital inkjet printing, a post-exposure treatment step is included, in which the polyester fabric is exposed to a water vapor atmosphere for 5-30 seconds. Water vapor molecules can react with the free radical active sites generated on the fiber surface after plasma treatment, further introducing hydrophilic groups such as -OH, increasing the density of oxygen-containing functional groups on the surface, and to some extent delaying the hydrophobic recovery process, thereby providing a wider operating window or a higher color intensity increment for the printing process.

[0011] Furthermore, the pre-drying temperature is 80-120℃, and the time is 1-5 minutes. Pre-drying aims to remove moisture and solvent from the ink to prevent migration during subsequent high-temperature color fixing, thus ensuring the clarity of the pattern.

[0012] Furthermore, the high-temperature heat-setting temperature is 170-210℃, and the time is 30-120 seconds. High-temperature heat-setting causes the disperse dye to sublimate or dissolve and diffuse into the interior of the polyester fiber, achieving dye fixation. Preferably, the high-temperature heat-setting temperature is 185-195℃, and the time is 60-90 seconds. These conditions are conducive to the full dyeing and fixation of high-energy disperse dyes, resulting in optimal color fastness.

[0013] Further, the disperse dye ink comprises a high-energy disperse dye, a dispersant, a wetting agent, an aqueous polymer, and deionized water, wherein the aqueous polymer is present in the disperse dye ink at a content of 0.01-0.5 wt%. The addition of the aqueous polymer helps to adjust the rheological properties of the ink and forms a thin layer on the fiber surface after printing, assisting in dye fixation. Specifically, the aqueous polymer may be selected from at least one of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG); the high-energy disperse dye may be selected from at least one of CI Disperse Blue 79, CI Disperse Blue 359, CI Disperse Yellow 48, and CI Disperse Red 60.

[0014] The second aspect of this application provides an application of the waterless digital printing process described above in the printing of polyester fabrics.

[0015] The present invention has the following beneficial effects: Green and environmentally friendly: The plasma dry pretreatment method completely eliminates wastewater discharge in the pretreatment stage, eliminating the need for water washing and acid neutralization, thus reducing environmental pollution and wastewater treatment costs.

[0016] Quality Improvement: Surface modification enhances the hydrophilicity of polyester fabrics, resulting in a significant increase in printing color intensity (K / S value) and improved line clarity, effectively solving the problem of difficult printing on hydrophobic fabrics.

[0017] Protecting the fabric: Compared with traditional alkali reduction treatment, plasma treatment only acts on the surface layer of the fiber (nanoscale depth), without damaging the mechanical properties of the fabric itself, thus ensuring the hand feel and strength of the finished product.

[0018] High efficiency and energy saving: The process flow is short and the processing time is short (seconds). It is easy to integrate into existing digital printing production lines to achieve continuous production and significantly shorten the production cycle. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of a heat transfer printing process according to an embodiment of this application. Detailed Implementation

[0020] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0021] In some preferred embodiments, the plasma surface modification treatment can take the form of dielectric barrier discharge (DBD), corona discharge, or atmospheric pressure glow discharge. Besides air, the working gas can also be nitrogen, oxygen, argon, or a mixture thereof, and even a small amount of water vapor can be introduced as an activating gas; however, from a cost and environmental perspective, air is the preferred choice. The electrode structure can be a flat plate, coaxial cylindrical, or comb-shaped electrode structure, and the dielectric barrier material can be a high-temperature resistant insulating material such as quartz glass, ceramic, polycarbonate, or polytetrafluoroethylene.

[0022] In some preferred embodiments, the power density of the plasma treatment can be adjusted between 0.1-5 W / cm², and the treatment time can be optimized between 5-120 seconds depending on the fabric running speed. The electrode spacing can be adjusted between 0.5-10 mm depending on the fabric thickness to ensure discharge uniformity and treatment efficiency.

[0023] In some preferred embodiments, the aqueous polymer can be selected from polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), or polyethylene glycol (PEG). Specifically, the degree of polymerization of PVA can be selected between 500 and 2400, and the degree of hydrolysis can be selected between 80% and 99%; the K value of PVP can be selected between K15 and K90; and the molecular weight of PEG can be selected between 200 and 20000. The content of the aqueous polymer in the ink can be adjusted between 0.01 and 1.0 wt% according to the degree of improvement in the hydrophilicity of the fabric.

[0024] In some preferred embodiments, the high-energy disperse dye can be selected from azo or anthraquinone disperse dyes, as long as their sublimation temperature matches the subsequent thermosetting process, such as CI Disperse Red 60, CI Disperse Red 167, CI Disperse Blue 56, etc. The ink viscosity can be adjusted in the range of 2-20 mPa·s, and the surface tension can be adjusted in the range of 25-40 mN / m to adapt to different printhead models.

[0025] In some preferred embodiments, the pre-drying step can be performed using hot air drying, infrared drying, or microwave drying. The high-temperature heat-fixing step can be performed using a hot air tenter frame, a high-temperature steaming machine, or a hot press. The fixing time can be adjusted accordingly for fabrics of different thicknesses; for example, it can be shortened to 15 seconds for thin fabrics and extended to 180 seconds for thick fabrics.

[0026] Example 1 like Figure 1 As shown, this embodiment provides a waterless digital printing process.

[0027] Raw materials for preparation: The polyester fabric is made of 100% polyester plain weave fabric with an areal density of 178 g / m². 2 The spinning oil is removed by pre-washing. The disperse dye ink (cyan channel formulation) comprises: CI Disperse Blue 79 color paste 30wt%, ethylene glycol (EG) 10wt%, butanediol-1,215wt%, polyvinyl alcohol (PVA, degree of polymerization 1700, degree of hydrolysis 88%) 0.075wt%, fatty alcohol polyoxyethylene ether (Laureth-4) 0.50wt%, silicone defoamer 0.05wt%, triethanolamine (TEOA) 0.50wt%, and deionized water to make up to 100wt%. The ink is filtered through a 0.22μm filter membrane.

[0028] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. Following this, a water vapor exposure treatment is performed, with a water vapor exposure zone set at the plasma treatment exit end, water vapor temperature 60-80℃, exposure time 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0029] Example 2 This embodiment provides a waterless digital printing process.

[0030] The raw materials were prepared in the same manner as in Example 1.

[0031] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density adjusted to 0.5 W / cm². 2 (Total power 200W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. Following this, a water vapor exposure treatment is performed, with a water vapor exposure zone set at the plasma treatment exit end, water vapor temperature 60-80℃, exposure time 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0032] Example 3 This embodiment provides a waterless digital printing process.

[0033] The raw materials were prepared in the same manner as in Example 1.

[0034] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric movement speed adjusted to 4m / min, corresponding to a processing time of approximately 22 seconds. Following this, a water vapor exposure treatment is performed. A water vapor exposure zone is set at the plasma treatment outlet, with a water vapor temperature of 60-80℃ and an exposure time of 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0035] Example 4 This embodiment provides a waterless digital printing process.

[0036] The raw materials were prepared in the same manner as in Example 1.

[0037] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. The water vapor exposure step is omitted; printing is performed directly within 15 minutes after plasma treatment using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0038] Example 5 This embodiment provides a waterless digital printing process.

[0039] Raw materials for preparation: The polyester fabric is made of 100% polyester plain weave fabric with an areal density of 178 g / m². 2 The spinning oil is removed by pre-washing. The disperse dye ink (cyan channel formulation) comprises: CI Disperse Blue 79 color paste 30wt%, ethylene glycol (EG) 10wt%, butanediol-1,215wt%, polyvinylpyrrolidone (PVP, K30 grade) 0.075wt%, fatty alcohol polyoxyethylene ether (Laureth-4) 0.50wt%, silicone defoamer 0.05wt%, triethanolamine (TEOA) 0.50wt%, and deionized water to make up to 100wt%. The ink is filtered through a 0.22μm filter membrane.

[0040] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. Following this, a water vapor exposure treatment is performed, with a water vapor exposure zone set at the plasma treatment exit end, water vapor temperature 60-80℃, exposure time 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0041] Example 6 This embodiment provides a waterless digital printing process.

[0042] Raw materials for preparation: The polyester fabric is a 65 / 35 polyester / cotton blend plain weave fabric with an areal density of 200 g / m². 2 The spinning oil is removed by pre-washing. The disperse dye ink is the same as in Example 1.

[0043] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. Following this, a water vapor exposure treatment is performed, with a water vapor exposure zone set at the plasma treatment exit end, water vapor temperature 60-80℃, exposure time 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0044] Example 7 This embodiment provides a waterless digital printing process.

[0045] The raw materials were prepared in the same manner as in Example 1.

[0046] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric passing through at a speed of 2m / min, processing time approximately 45 seconds. Following this, a water vapor exposure treatment is performed, with a water vapor exposure zone set at the plasma treatment exit end, water vapor temperature 60-80℃, exposure time 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, the heat curing temperature is adjusted to 200℃, and high-temperature heat curing is completed in a hot air tenter for 60 seconds.

[0047] Comparative Example 1 This comparative example provides a printing process.

[0048] The raw materials were prepared in the same manner as in Example 1.

[0049] Preparation method: The polyester fabric, without any pretreatment, was printed directly using a piezoelectric digital inkjet printer at a resolution of 720×720 dpi. After printing, the fabric was dried in a 110℃ hot air oven for 3 minutes. Finally, it was heat-cured in a 190℃ hot air tenter for 60 seconds.

[0050] Comparative Example 2 This comparative example provides a printing process.

[0051] Raw materials for preparation: The polyester fabric was the same as in Example 1. The pretreatment reagents included 3 wt% NaOH solution and 1 wt% acetic acid solution.

[0052] Preparation method: First, a traditional alkali reduction pretreatment was performed, immersing the polyester fabric in a 3wt% NaOH solution (liquid ratio 1:20) at 95℃ for 30 minutes. Then, it was washed three times with water, neutralized with a 1wt% acetic acid solution, and finally washed twice with water and dried. Subsequently, printing was performed using a piezoelectric digital inkjet printer at a resolution of 720×720 dpi. After printing, the fabric was dried in a 110℃ hot air oven for 3 minutes. Finally, it was treated in a 190℃ hot air tenter for 60 seconds to complete high-temperature heat curing.

[0053] Comparative Example 3 This comparative example provides a printing process.

[0054] The raw materials were prepared in the same manner as in Example 1.

[0055] Preparation method: First, DBD plasma surface modification treatment is performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes, each with an electrode area of ​​8×50cm. 2 It is covered with polycarbonate dielectric layers on both sides, uses air as the working gas, and has a power density of 1W / cm³. 2 (Total power 400W), electrode spacing 3mm, fabric movement speed adjusted to 1m / min, corresponding to a processing time of approximately 90 seconds. Following this, a water vapor exposure treatment is performed. A water vapor exposure zone is set at the plasma treatment outlet, with a water vapor temperature of 60-80℃ and an exposure time of 10 seconds. Then, within 15 minutes after treatment, printing is performed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric is dried in a 110℃ hot air oven for 3 minutes. Finally, it undergoes high-temperature heat curing in a 190℃ hot air tenter for 60 seconds.

[0056] Comparative Example 4 This comparative example provides a printing process.

[0057] The raw materials were prepared in the same manner as in Example 1.

[0058] Preparation method: First, DBD plasma surface modification treatment was performed using an atmospheric pressure roller-to-roller DBD plasma device with parallel plate electrodes. The electrode area was 8×50cm², and both sides were covered with polycarbonate dielectric layers. The working gas was air, with a power density of 1W / cm² (total power 400W). The electrode spacing was 3mm, and the fabric passed through at a speed of 2m / min for approximately 45 seconds. Following this, a water vapor exposure treatment was performed. A water vapor exposure zone was set at the plasma treatment exit, with a water vapor temperature of 60-80℃ and an exposure time of 10 seconds. After the treated fabric was left at room temperature for 24 hours, it was then printed using a piezoelectric digital inkjet printer at a resolution of 720×720dpi. After printing, the fabric was dried in a 110℃ hot air oven for 3 minutes. Finally, it was treated in a 190℃ hot air tenter for 60 seconds to complete high-temperature heat curing.

[0059] The finished products of the above embodiments and comparative examples were subjected to the following tests: Color intensity (K / S value): Refer to GB / T8424.2-2001, use a spectrophotometer to measure the reflectance R at the maximum absorption wavelength, and calculate according to the Kubelka-Munk formula.

[0060] Wash fastness: Refer to GB / T3921-2008, treat at 40℃ for 30 minutes, and evaluate the color change and staining grades (1-5).

[0061] Color fastness to rubbing: Refer to GB / T3920-2008, conduct dry and wet rubbing tests respectively, and evaluate the staining grade.

[0062] Sublimation fastness: According to AATCC™ 117, test at 180℃ / 210℃ for 30 seconds to assess the staining and color change grades.

[0063] Printing accuracy (line width test): Print a straight line with a nominal width of 353μm, measure the actual line width under a microscope, and calculate the percentage deviation.

[0064] Water contact angle: The static contact angle is measured using an optical contact angle meter.

[0065] Tensile strength: The longitudinal breaking strength was tested in accordance with GB / T3923.1-2013.

[0066] Capillary absorbency: Refer to AATCC™ 197 to measure the height of water rising along the fabric within 30 minutes.

[0067] Table 1 shows the performance test results of the examples and comparative examples.

[0068]

[0069] Data from Comparative Example 1 and Comparative Example 1 show that the untreated polyester fabric (Comparative Example 1) has a water contact angle as high as 75°, exhibiting extremely strong hydrophobicity, making it difficult for ink to wet and penetrate, resulting in the lowest K / S value, and a printing linewidth deviation as high as 28%, with blurred pattern edges. After treatment with the plasma process described in this invention (Example 1), the water contact angle decreased to 30°, and the capillary water absorption height increased significantly from 8 mm to 95 mm, indicating a fundamental improvement in the hydrophilicity of the fiber surface. This is attributed to the introduction of polar groups such as hydroxyl and carboxyl groups into the fiber surface by plasma treatment, forming a micro-nano rough structure, thereby improving the ink adsorption efficiency and spreading controllability, ultimately increasing the K / S value by 23%, controlling the linewidth deviation within 8%, and achieving high-precision, clear printing. Comparative Example 1 and Comparative Example 2 (traditional alkali reduction), Example 1 is superior to or equivalent to Comparative Example 2 in terms of color intensity and printing precision, but its greatest advantage lies in the retention rate of tensile strength. Comparative Example 2 suffered from fiber damage due to alkali hydrolysis, resulting in a strength retention rate of only 92%, while Example 1 reached 98%. Furthermore, Example 1 eliminates the need for washing and neutralization processes, offering unparalleled advantages in terms of environmental protection and process flow. Comparative Example 4 demonstrates the consequences of leaving the treated area for 24 hours before printing. The water contact angle recovers to 55°, and the K / S value increase rate drops significantly to 8%, almost reaching the untreated level.

[0070] Comparing Examples 1, 2, and 3, it is evident that plasma treatment power and time directly affect the modification effect. Example 2 used a lower power (0.5 W / cm²). 2Example 3, with its shorter processing time (22 seconds), showed slightly inferior results compared to Example 1. This indicates that within the parameter range defined in the claims, appropriately increasing the energy density helps to obtain better modification effects. Comparative Example 3 demonstrates the consequences of excessively long processing time (90 seconds). Although the K / S value is slightly improved, the tensile strength retention rate decreases to 94%, and there is a risk of yellowing or hardening of the fabric surface. Therefore, the process window needs to be controlled within 60 seconds. Comparing Example 1 and Example 4, Example 1 added a water vapor post-exposure step, and its K / S value improvement rate (23%) was significantly higher than that of Example 4 (15%) without this step, and the water contact angle was lower. This confirms that water vapor can further react with plasma-activated surface free radicals, increasing the density of oxygen-containing functional groups, thereby enhancing the modification effect. Examples 5 and 6 respectively verified the applicability of different ink formulations and substrates. Example 5 used PVP as an aqueous polymer and also obtained excellent printing effects, indicating that the process has good compatibility with ink systems. Example 6 also achieved a good improvement in K / S value on polyester-cotton blended fabrics, proving that the process has a wide range of substrate adaptability.

[0071] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A waterless digital printing process, characterized in that, Includes the following steps: The polyester fabric to be printed is subjected to plasma surface modification treatment; Within 30 minutes of the completion of the surface modification treatment, the polyester fabric is digitally inkjet printed using disperse dye ink; the printed polyester fabric is then pre-dried and heat-cured at high temperature.

2. The waterless digital printing process according to claim 1, characterized in that, The plasma surface modification treatment is carried out under atmospheric pressure using dielectric barrier discharge plasma, with air as the working gas.

3. The waterless digital printing process according to claim 2, characterized in that, The power density of the plasma treatment is 0.5-2 W / cm². 2 The processing time is 15-60 seconds, and the electrode spacing is 1-5 mm.

4. The waterless digital printing process according to claim 3, characterized in that, The power density of the plasma treatment is 1 W / cm². 2 The processing time is 30-45 seconds, and the electrode spacing is 3mm.

5. The waterless digital printing process according to claim 1, characterized in that, After the surface modification treatment is completed and before the digital inkjet printing, the process further includes a post-exposure treatment step of exposing the polyester fabric to a water vapor atmosphere for 5-30 seconds.

6. The waterless digital printing process according to claim 1, characterized in that, The pre-drying temperature is 80-120℃, and the time is 1-5 minutes.

7. The waterless digital printing process according to claim 1, characterized in that, The high-temperature thermosetting temperature is 170-210℃, and the time is 30-120 seconds.

8. The waterless digital printing process according to claim 7, characterized in that, The high-temperature thermosetting temperature is 185-195℃, and the time is 60-90 seconds.

9. The waterless digital printing process according to claim 1, characterized in that, The disperse dye ink comprises high-energy disperse dye, dispersant, wetting agent, aqueous polymer and deionized water, wherein the content of the aqueous polymer in the disperse dye ink is 0.01-0.5 wt%.

10. The application of the waterless digital printing process as described in any one of claims 1-9 in the printing of polyester fabrics.

Images