Direct jet printing method without pretreatment of fabric and printed fabric

Abstract

This invention provides a direct-to-garment printing method and printed fabric without pre-treatment of the fabric. The method involves placing the back of a base fabric tightly against a heated substrate and continuously pre-drying the base fabric with heat. On the printing surface of the base fabric, the following processes are performed sequentially in a single printing stroke: a water-based digital adhesive layer is printed using a first printhead, a white ink layer is printed using a second printhead, and a colored ink layer is printed using a third printhead, resulting in a pre-printed fabric. After printing, the pre-printed fabric is dried and cured to obtain the printed fabric. The resulting printed fabric comprises, along its thickness direction, layers of: base fabric, water-based digital adhesive layer, white ink layer, and colored ink layer; wherein the penetration depth of the water-based digital adhesive layer into the base fabric is less than 20 μm. This method is simple to produce, energy-saving and environmentally friendly, has excellent material versatility, and produces printed fabrics with excellent color performance, high fastness, and a soft hand feel.

Description

Technical Field

[0001] This invention belongs to the field of textile digital printing technology, specifically relating to a direct-to-garment printing method and printed fabric that does not require pre-treatment of the fabric. Background Technology

[0002] While traditional DTG (Direct To Garment) technology achieves digital printing, its biggest technological bottleneck lies in its heavy reliance on fabric pretreatment. Specifically, traditional DTG technology has the following drawbacks: Complex pretreatment process: Existing DTG processes require the fabric (especially dark-colored fabrics) to be sprayed with a special pretreatment solution and then dried and ironed before printing. This not only increases labor costs and equipment investment, but also easily leads to printing defects due to uneven treatment.

[0003] Time constraints: The pretreatment solution has a strict time window after application, and printing must be completed within a short period of time, otherwise it will lead to color deviation or failure to fix the color, which limits the flexibility of production.

[0004] Material limitations: For certain special fabrics, conventional pretreatment solutions are difficult to penetrate, resulting in ink failure to adhere and extremely poor print fastness.

[0005] To address the aforementioned issues, this invention proposes a novel "glue-white-color" direct-to-garment printing process, which aims to eliminate pretreatment steps and allow printing directly onto the fabric. Summary of the Invention

[0006] The main objective of this invention is to provide a direct-to-garment printing method and printed fabric that does not require pre-treatment of the fabric, in order to solve the problems of traditional DTG process which must rely on chemical pre-treatment, has limited production time and poor adaptability to special materials. The method of this invention is simple to produce, energy-saving and environmentally friendly, has excellent material versatility, and the printed fabric prepared has excellent color performance, high fastness and soft hand feel.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a direct-to-garment printing method without fabric pretreatment, comprising: The back of the base fabric is pressed tightly against the heating plate, and the base fabric is continuously heated and pre-dried. On the printing surface of the base fabric, the following steps are performed sequentially in a single printing stroke: A pre-printed fabric is obtained by printing a water-based digital adhesive layer using a first printhead, a white ink layer using a second printhead, and a colored ink layer using a third printhead. After printing is completed, the pre-printed fabric is dried and cured to obtain the printed fabric.

[0008] Secondly, the present invention also claims a printed fabric produced by the above-described direct-to-garment printing method, comprising: layers stacked sequentially along the thickness direction. Base fabric, water-based digital adhesive layer, white ink layer, and colored ink layer; The penetration depth of the water-based digital adhesive layer into the base fabric is less than 20 μm.

[0009] Compared with the prior art, the beneficial effects of the present invention include at least the following: This invention provides a method for direct printing without chemical pretreatment of the fabric, completely eliminating the need for pretreatment: by directly printing an "adhesive layer" as an isolation and adhesion medium, it replaces the chemical pretreatment solution used in traditional DTG. The adhesive layer acts like "double-sided tape," gripping the fabric on one end and carrying the ink on the other, so that the ink no longer depends on the fabric's absorbency; the production process is extremely simple and flexible: the fabric can be placed and printed immediately, without waiting for the pretreatment solution to dry or worrying about its expiration date; it has excellent material versatility: whether it is cotton, linen, silk, synthetic fibers, or difficult-to-handle waterproof fabrics and leather, as long as the adhesive can adhere, high-quality printing can be achieved; it is energy-saving and environmentally friendly: reducing the drying process and the amount of chemicals used.

[0010] The printed fabrics prepared using the method of this invention exhibit excellent color performance: the sandwich structure of "glue-white-color" ensures extremely high white background coverage and color saturation, especially effective on dark or black fabrics; high fastness: dry rubbing fastness ≥ 4, wet rubbing fastness ≥ 4, and washing fastness ≥ 4; soft hand feel: the glass transition temperature of the film-forming agent is controllable, avoiding the hardening caused by traditional pretreatment.

[0011] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a photograph of the fabric obtained in a typical embodiment of the present invention; Figure 2 These are photographs of the fabrics obtained in a proportional manner according to the present invention. Detailed Implementation

[0014] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0015] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0016] In a specific embodiment of the present invention, the present invention provides a direct-to-garment printing method without fabric pretreatment, comprising: The back of the base fabric is pressed tightly against the heating plate, and the base fabric is continuously heated and pre-dried. On the printing surface of the base fabric, the following steps are performed sequentially in a single printing stroke: A pre-printed fabric is obtained by printing a water-based digital adhesive layer using a first printhead, a white ink layer using a second printhead, and a colored ink layer using a third printhead. After printing is completed, the pre-printed fabric is dried and cured to obtain the printed fabric.

[0017] In the aforementioned direct-to-garment printing method, during a single printing stroke, a liquid hot-melt water-based digital adhesive layer is first sprayed onto the surface of the base fabric. Then, a white ink layer is directly sprayed onto the not-yet-completely-dry water-based digital adhesive layer, followed by a colored ink layer. The printing of the three inks is completed continuously in a single printing stroke, with the heating plate continuously providing heat during the printing process. After the entire pattern is printed, the pre-printed fabric is placed in an oven for overall drying, allowing the adhesive to cross-link and cure, thus completing the printing. The purpose of spraying the digital adhesive layer onto the base fabric surface is not for pre-treatment, but rather to directly generate adhesion. It bonds to both the fabric and the ink layer on it, serving as a bridging and bonding agent in this process.

[0018] Furthermore, the temperature of the heating plate is set to 50℃~80℃. The heating plate pre-dries the base fabric, and the adhesive layer forms a barrier layer under pre-drying conditions to isolate the fabric's base color and carry subsequent ink, thereby inhibiting adhesive penetration. During the printing of the digital adhesive layer, heating the plate quickly evaporates the moisture in the digital adhesive, which reduces the downward penetration of the adhesive onto the fabric and better prepares the surface for the next step of printing the white ink layer, increasing the ink's load-bearing capacity.

[0019] Furthermore, the printing amount of the water-based digital adhesive layer is 100~200g / m2; the printing feel and penetration can be controlled by adjusting the printing amount.

[0020] Furthermore, the drying and curing temperature is 140~170℃, and the curing time is 3~5 minutes.

[0021] Furthermore, the time interval between printing the water-based digital adhesive layer and the white ink layer is 0.05 to 0.3 seconds; The time interval between printing the white ink layer and the colored ink layer is 0.05 to 0.3 seconds.

[0022] In particular, the interval between printing the water-based digital adhesive layer and the white ink layer needs to be reasonably set according to the running speed of the print head, and the print head cannot be overlapped for printing, as this method results in too short an interval between printing the two materials.

[0023] Furthermore, the water-based digital adhesive layer is printed using water-based digital adhesive, which includes water-based polyurethane-acrylate emulsion and self-crosslinking acrylate emulsion.

[0024] Furthermore, the water-based digital adhesive specifically comprises, by mass fraction: Waterborne polyurethane-acrylate emulsion, 20%–35%; Self-crosslinking acrylic emulsion, 10%–25%; Moisturizer, 5%–12%; Wetting agent, 0.1%–0.5%; Defoamer, 0.1%–0.5%; Leveling agent selection: 0.05-0.2%; pH adjuster, 0.1%–0.5%; Fungicide, 0.2%–1%; Crosslinking accelerator, 0.1%–0.5%; Deionized water, balance.

[0025] Among the above-mentioned water-based digital adhesives, the water-based polyurethane-acrylate emulsion combines flexibility and adhesion, and undertakes the film-forming function of the pretreatment solution; the self-crosslinking acrylate emulsion provides water resistance and abrasion resistance; the crosslinking accelerator is used to improve the interfacial bonding strength of fibers, and can form coordination crosslinking or chemical crosslinking with polyurethane and acrylic emulsion to improve dry and wet fastness.

[0026] The aforementioned water-based digital adhesive, through the compounding of specific components, combines fabric adhesion, ink carrying capacity, and film-forming barrier properties, completely replacing the traditional DTG chemical pretreatment solution. It eliminates cumbersome processes such as pressing, leveling, and time-controlled aging, and solves the problems of color spots, poor material adaptability, and color fading that are common in traditional processes.

[0027] Furthermore, the water-based digital adhesive has a pH value of 7.5~8.5, a viscosity of 5-15 mPa•s at 25℃, and a surface tension of 32~38 mN / m.

[0028] Furthermore, the solid content of the waterborne polyurethane-acrylate emulsion is 30-40%, wherein the mass ratio of polyurethane to acrylate is 1.0-2.0:1, the molecular weight of polyurethane is 25,000-35,000 g / mol, and the molecular weight of acrylate is 100,000-150,000 g / mol. Preferably, the waterborne polyurethane-acrylate emulsion is an anionic waterborne PUA emulsion; its glass transition temperature (Tg) is 10℃~30℃; its particle size is 50~150nm; it has both flexibility and high adhesion to cotton fibers, and its film has high transparency and does not fog, and can replace traditional pretreatment adhesives.

[0029] More preferably, the waterborne polyurethane-acrylate emulsion is selected from Alberdingk U9150 (anionic, Tg≈10℃) or DSM Meorez R-9669.

[0030] Furthermore, the solid content of the self-crosslinking acrylate emulsion is 40-60%, and the molecular weight of the acrylate is 100,000-150,000 g / mol.

[0031] Preferably, the self-crosslinking acrylate emulsion is an acrylate copolymer containing carboxyl and hydroxyl functional groups; the minimum film-forming temperature (MFFT) is ≤40℃; and it can undergo self-crosslinking during the thermosetting process, thereby improving water resistance and abrasion resistance.

[0032] More preferably, the MFFT of the self-crosslinking acrylate emulsion is ≤35°C, and a three-dimensional network structure is formed after thermosetting.

[0033] More preferably, the self-crosslinking acrylate emulsion is selected from BASFAcronal 2967D or Celanese Eco-501.

[0034] Furthermore, the moisturizer is preferably one or a combination of glycerin, 1,3-propanediol, and diethylene glycol.

[0035] More preferably, the moisturizer is selected from Cargill USP grade glycerin and DuPont Zemea 1,3-propanediol, and the mass ratio of Cargill USP grade glycerin to DuPont Zemea 1,3-propanediol is preferably 1:0.5–1:1.

[0036] Furthermore, the wetting agent is selected from wet245.

[0037] Furthermore, the defoamer is selected from 104E.

[0038] Furthermore, the leveling agent is selected from byk348.

[0039] Furthermore, the pH adjuster is preferably triethylamine, ammonia, or sodium hydroxide.

[0040] More preferably, the pH adjuster is selected from Dow triethylamine (TEA) or ammonia. The pH adjuster can control the pH of the water-based digital adhesive system at 7.5~8.5, ensuring the long-term storage stability of the ink.

[0041] Furthermore, the bactericide is preferably at least one of PROXELGXL and Rohm and Haas LEX.

[0042] Furthermore, the crosslinking promoter includes any one or a combination of two or more of zinc salts, magnesium salts, and zoline compounds.

[0043] More preferably, the crosslinking accelerator is zinc chloride (ZnCl2), magnesium sulfate, or an azoline compound; more preferably, it is ZnCl2 or Nippon Shokubai Epocros WS-500.

[0044] In another specific embodiment of the present invention, the above method is performed using a direct-to-garment printing system, comprising: A digital direct-to-garment printer is configured with at least three independent printhead channels, including a first printhead for printing a water-based digital adhesive layer, a second printhead for printing a white ink layer, and a third printhead for printing a color ink layer. Heated base plate; it is used to support the base fabric and continuously heat and pre-dry the base fabric. Infrared curing oven.

[0045] In another specific embodiment of the present invention, the present invention provides a printed fabric obtained by the above-described direct-to-garment printing method, comprising: layers stacked sequentially along the thickness direction. Base fabric, water-based digital adhesive layer, white ink layer, and colored ink layer; The penetration depth of the water-based digital adhesive layer into the base fabric is less than 20 μm.

[0046] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0047] Example 1

[0048] This embodiment provides a method for preparing water-based digital adhesive, the specific steps of which are as follows: Start stirring. Add 6% glycerol and 4% 1,3-propanediol (by mass fraction) to the reactor. While stirring, add 28% Alberdingk U9150 and 18% Acronal 2967D. Stir at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 to the reactor. Next, add 0.1% GXL bactericide, 0.5% zinc chloride crosslinking agent, 0.3% triethylamine, and the remainder water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered product is the finished water-based digital adhesive.

[0049] Example 2

[0050] This embodiment provides a method for preparing water-based digital adhesive, the specific steps of which are as follows: Start stirring and add 6% glycerol and 4% 1,3-propanediol (by mass fraction) to the reactor. While stirring, add 32% DSM Neorez R-9669 and 15% Celanese Eco-501. Stir at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 sequentially to the reactor. Next, add 0.1% GXL bactericide, 0.8% magnesium sulfate crosslinking agent, 0.3% triethylamine, and the remainder water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered product is the finished water-based digital adhesive.

[0051] Example 3

[0052] This embodiment provides a method for preparing water-based digital adhesive, the specific steps of which are as follows: Start stirring. Add 6% glycerol and 4% 1,3-propanediol (by mass fraction) to the reactor. While stirring, add 25% Alberdingk U9150 and 20% Acronal 2967D. Stir at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 to the reactor. Next, add 0.1% GXL bactericide, 0.6% Epocros WS-500, and 0.3% triethylamine, with the remainder being water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered product is the finished water-based digital adhesive.

[0053] The water-based digital adhesives prepared in Examples 1-3 were tested according to the following methods, and the test results are shown in Table 1 below: Wash fastness test: According to ISO 105 "Textiles - Tests for color fastness" Part C06, take the fabric with the printed pattern and wash it at 40°C for 45 minutes to test for color staining. Then, use a rubbing fastness tester to test the dry rubbing fastness. Repeat 20 times to check if the pattern comes off. Hand feel stiffness test: The printed fabric is judged by hand feel and compared with the original fabric, and distinguished according to "soft / soft / medium / hard / stiff".

[0054] Table 1. Formulations and test results of Examples 1-3 AlberdingkU9150 28% / 25% DSMNeorezR-9669 / 32% / BASFAcronal2967D 18% / 20% CelaneseEco-501 / 15% / glycerin 6% 6% 6% 1,3-Propanediol 4% 4% 4% wetting agent wet245 0.3% 0.3% 0.3% Defoamer 104E 0.3% 0.3% 0.3% Leveling agent byk348 0.1% 0.1% 0.1% Triethylamine 0.3% 0.3% 0.3% fungicide GXL 0.1% 0.1% 0.1% <![CDATA[Zinc chloride ZnCl₂ crosslinking agent]]> 0.5% / / <![CDATA[Magnesium sulfate MgSO4 crosslinking agent]]> / 0.8% / Epocros WS-500, a zoline crosslinking agent / / 0.6% Viscosity (mPa·s) 30.5 28.7 25.8 Surface tension mN / m 29.5 29.7 29.7 Printing continuity performance One needle breaks in 30 minutes Two needles broke in 30 minutes. One needle breaks in 30 minutes Wash fastness Level 4-5 Level 4 Level 5 Friction strength Level 4-5 Level 4 Level 5 feel soft Soft soft As can be seen from Table 1, Examples 1–3 demonstrate that the water-based digital adhesive of the present invention firmly adheres to the fabric and can successfully replace the traditional pretreatment process.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing ink, the specific steps of which are as follows: Start stirring and add 6% glycerol and 4% 1,3-propanediol to the reactor. While stirring, add 50% Acronal 2967D and stir at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 sequentially to the reactor, followed by 0.1% GXL bactericide, 0.6% Epocros WS-500, 0.3% triethylamine, and the remainder water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered solution is the finished ink.

[0057] Comparative Example 2

[0058] This comparative example provides a method for preparing ink, the specific steps of which are as follows: Start stirring and add 6% glycerol and 4% 1,3-propanediol to the reactor. While stirring, add 25% Alberdingk U9150 and 20% Acronal 2967D, and stir at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 to the reactor, followed by 0.1% GXL bactericide, 0.3% triethylamine, and the remainder water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered solution is the finished ink.

[0059] Comparative Example 3

[0060] This comparative example provides a method for preparing ink, the specific steps of which are as follows: Start stirring and add 10% glycerol to the reactor. While stirring, add 28% Alberdingk U9150 and 18% Acronal 2967D, stirring at 500 rpm for 30 minutes. Then, add 0.3% WET245, 0.3% 104E, and 0.1% BYK348 to the reactor, followed by 0.1% of the bactericide GXL, 0.3% triethylamine, and the remainder water. Stir at 800 rpm for 120 minutes. Filter the solution sequentially using a 0.45µm GF column filter and a 1.0µm nylon 66 column filter. The filtered solution is the finished ink.

[0061] The water-based digital adhesives prepared in Example 1 and Comparative Examples 1-3 were tested, and the test results are shown in Table 2 below: Table 2. Formulations and test results of Examples 1 and Comparative Examples 1-3 AlberdingkU9150 28.00% / 28.00% 28.00% DSMNeorezR-9669 / / / / BASFAcronal2967D 18.00% 50.00% 18.00% 18.00% CelaneseEco-501 / / / / glycerin 6.00% 6.00% 6.00% 10.00% 1,3-Propanediol 4.00% 4.00% 4.00% / wetting agent wet245 0.30% 0.30% 0.30% 0.30% Defoamer 104E 0.30% 0.30% 0.30% 0.30% Leveling agent byk348 0.10% 0.10% 0.10% 0.10% Triethylamine 0.3% 0.3% 0.3% 0.3% fungicide GXL 0.10% 0.10% 0.10% 0.10% <![CDATA[Zinc chloride ZnCl₂ crosslinking agent]]> 0.50% 0.50% / 0.50% <![CDATA[Magnesium sulfate MgSO4 crosslinking agent]]> / / / / Epocros WS-500, a zoline crosslinking agent / / / / Viscosity (mPa·s) 30.5 30 29.5 30.2 Surface tension mN / m 29.5 29.2 29.7 29.6 Printing continuity performance One needle breaks in 30 minutes Two needles broke in 30 minutes. Two needles broke in 30 minutes. 5 needles broke in 30 minutes Dry friction fastness 4–5 2 3 2 wet friction fastness 4 2-3 2-3 2 Wash fastness 4–5 2-3 2–3 2-3 feel soft hard Hard medium The results above show that in Comparative Example 1, using only acrylic emulsion cannot replace the traditional pretreatment solution; in Comparative Example 2, the crosslinking agent can significantly improve the abrasion resistance and water resistance of the adhesive film after it is formed with PUA and acrylic polymer; in Comparative Example 3, although using a single glycerin humectant can provide a certain moisturizing effect, the lack of fast-drying components will cause the ink in the printhead dwell area to become excessively thickened; while the combination of glycerin and 1,3-propanediol in a specific ratio can achieve a balance between moisturizing and moderate fast-drying properties, effectively preventing printhead clogging and improving printhead adaptability.

[0062] Example 4

[0063] This embodiment provides a direct-to-garment printing method that eliminates the need for fabric pretreatment. The method employs a direct-to-garment printing system and includes: The digital direct inkjet printer is equipped with three independent printhead channels, including a first printhead for printing water-based digital adhesive layers, a second printhead for printing white ink layers, and a third printhead for printing green ink layers. Heated base plate; it is used to support the base fabric and continuously heat and pre-dry the base fabric. Infrared curing oven.

[0064] The specific steps of the direct-to-garment printing method using the above direct-to-garment printing system are as follows: The base fabric, pure cotton black cloth, is fixed onto the heated base plate of the printing platform, with its back side pressed tightly against the heated base plate. The digital direct-to-garment printer and the heated base plate are started, with the base plate temperature controlled at 50-80℃. The printer is then started, and 100-130 g / m² of water-based digital adhesive from Example 1, 80% white ink, and 100% green ink blocks are sequentially sprayed onto the printing surface of the base fabric to form a layered layer of water-based digital adhesive, white ink, and green ink on the surface of the base fabric, thus obtaining a pre-printed fabric. Finally, the pre-printed fabric is removed and placed in an oven at 150℃ for 3-5 minutes to obtain the printed fabric.

[0065] Comparative Example 4

[0066] The DTG pretreatment solution formulation used in this comparative example is (by mass fraction): Fixative (BASF Basolan F) 5%-15%; Desiccant (Sinopharm analytical grade / industrial grade urea) 3%-8%; Penetrant (BASF Leophen M) 0.5%-2%; Stain remover (BASF Hostapur SAS) 0.5%-1%; The remainder is deionized water.

[0067] The above-mentioned DTG pretreatment solution is strongly cationic, with a pH range of 8.0-9.0 and a viscosity limit of 5-10 mPa·s. It has a surface tension of 30-40 mN / m, a conductivity of 1000-5000 μS / cm, and a solid content of 5%-15%.

[0068] The specific steps of the printing method in this comparative example are as follows: Iron the fabric sample flat, brush away any loose lint from the pure cotton black fabric sample, and use the pre-set program and equipment to evenly cover the printing area with DTG pretreatment solution at a rate of 20-30 ml / ㎡. Smooth out any vertical lint with a brush, and pre-dry with a hot air blower at 80℃-100℃ for 1-2 minutes to ensure it is dry and wrinkle-free before being fed into the DTG printer. Turn on the printer, print an 80% ink layer of white ink, followed by a 100% ink layer of green, leaving a 2-3 cm margin at the edges. Remove the fabric sample and place it in an oven at 150℃ for 5-8 minutes.

[0069] Comparative Example 5

[0070] The DTG pretreatment solution used in this comparative example has the same formulation as that in Comparative Example 4. The specific steps of the printing method are as follows: Iron the fabric sample flat, brush away any loose lint from the pure cotton black fabric sample, and use the pre-set program and equipment to evenly cover the printing area with DTG pretreatment solution at a rate of 20-30 ml / ㎡. Do not brush the lint; leave the water droplets of the treatment solution on the areas with vertical lint. Pre-dry with a hot air blower at 80℃-100℃ for 1-2 minutes to ensure the fabric is dry and wrinkle-free before being sent to the DTG printer. Turn on the printer, print 80% of the ink volume of white ink, then print 100% of the ink volume of green color blocks, leaving a 2-3 cm margin at the edges. Remove the fabric sample and place it in an oven at 150℃ for 5-8 minutes.

[0071] Comparative Example 6

[0072] The DTG pretreatment solution used in this comparative example has the same formulation as that in Comparative Example 4. The specific steps of the printing method are as follows: Remove any loose lint from the pure cotton black fabric sample. Fold the sample and scrape it with a hard object to preserve the creases. Using the pre-set program and equipment, evenly cover the printing area with DTG pretreatment solution at a rate of 20-30 ml / ㎡. Smooth out any vertical lint with a brush. Pre-dry the sample at 80℃-100℃ for 1-2 minutes to ensure it is dry before feeding it into the DTG printer. Turn on the printer and print an 80% ink layer of white ink, followed by a 100% ink layer of green ink, leaving a 2-3cm margin at the edges. Remove the fabric sample and place it in an oven at 150℃ for 5-8 minutes.

[0073] Comparative Example 7 The DTG pretreatment solution used in this comparative example has the same formulation as that in Comparative Example 4. The specific steps of the printing method are as follows: Iron the fabric sample flat, brush away any loose lint from the pure cotton black fabric sample, and manually spray DTG pretreatment solution onto the area slightly beyond the printed pattern. Smooth out any vertical lint with a brush, and pre-dry with a hot air blower at 80℃-100℃ for 1-2 minutes to ensure it is dry and wrinkle-free before being fed into the DTG printer. Turn on the printer, print an 80% ink layer of white ink, then print a 100% ink layer of green, leaving a 2-3cm margin at the edges. Remove the fabric sample and place it in an oven at 150℃ for 5-8 minutes.

[0074] The printed fabrics obtained in Example 4 and Comparative Examples 4-7 were tested, and the results are shown in Table 3: Table 3. Process and test results of Example 4 and Comparative Examples 4-7 Printing media pure cotton black cloth pure cotton black cloth pure cotton black cloth pure cotton black cloth pure cotton black cloth White background 80% ink volume 80% ink volume 80% ink volume 80% ink volume 80% ink volume Printed pattern 100% ink volume green color block 100% ink volume green color block 100% ink volume green color block 100% ink volume green color block 100% ink volume green color block Iron flat No need need need No need, leave the creases. need Remove loose hair No need need need need need Pretreatment and spraying methods No need machine spray machine spray machine spray Manual spraying bristles No need need No need need need Post-processing 150℃ for 5 minutes 150℃ for 5 minutes 150℃ for 5 minutes 150℃ for 5 minutes 150℃ for 5 minutes Finished product time 6min 13min 12min 12min 15min Fastness No peeling after scratches No peeling after scratches Peeling off the ridges Peeling off both sides of the crease Peeling off where the treatment fluid was not covered Color expression Even and bright Evenly dark The color of the granules is darker at the ridges. Darken the color at the crease Uneven and mottled color

[0075] Example 5

[0076] The base fabric, pure cotton black cloth, is fixed onto the heated base plate of the printing platform, ensuring its back is in close contact with the heated base plate. The digital direct-to-garment printer and the heated base plate are started, with the base plate temperature controlled at 50-80℃. The printer then directly sprays 100-130g / m² of water-based digital adhesive (Example 1), 80% white ink, and 100% black, yellow, red, and blue color blocks sequentially onto the printing surface of the base fabric. This forms a layered structure of water-based digital adhesive, white ink, and colored ink on the surface of the base fabric, resulting in a pre-printed fabric. Finally, the pre-printed fabric is removed and placed in an oven at 150℃ for 3-5 minutes to obtain the printed fabric. Figure 1 .

[0077] Comparative Example 7

[0078] The base fabric, pure cotton black cloth, is fixed onto the heated base plate of the printing platform, ensuring its back is in close contact with the heated base plate. The digital direct-to-garment printer and the heated base plate are started, with the base plate temperature controlled at 50-80℃. The printer then directly sprays 100-130g / m² of water-based digital adhesive from Example 1 and 100% ink blocks of black, yellow, red, and blue onto the printing surface of the base fabric, forming a layered structure of water-based digital adhesive, white ink, and colored ink to obtain a pre-printed fabric. Finally, the pre-printed fabric is removed and placed in an oven at 150℃ for 3-5 minutes to obtain the printed fabric. Figure 2 .

[0079] Comparing the above results, it can be found that because the fabric is a colored base fabric, the method in Example 5 can better develop the colored ink layer on the fabric, while the method of directly printing colored ink without printing a white ink layer cannot develop the color well.

[0080] This invention completely skips the chemical pretreatment step by directly constructing a "glue-white-color" physical medium layer. It eliminates deep marks and defects caused by poor manual leveling and breaks the time constraint of pretreatment liquid failure. While relieving the burden of fabric pretreatment, it achieves color saturation and wash fastness far exceeding traditional DTG, realizing direct-to-garment printing with an extremely simplified process.

[0081] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A direct-to-garment printing method without fabric pretreatment, characterized in that, include: The back of the base fabric is pressed tightly against the heating plate, and the base fabric is continuously heated and pre-dried. On the printing surface of the base fabric, the following steps are performed sequentially in a single printing stroke: A pre-printed fabric is obtained by printing a water-based digital adhesive layer using a first printhead, a white ink layer using a second printhead, and a colored ink layer using a third printhead. After printing is completed, the pre-printed fabric is dried and cured to obtain the printed fabric.

2. The direct-to-garment printing method according to claim 1, characterized in that, The temperature of the heating base plate is set to 50℃~80℃.

3. The direct-to-garment printing method according to claim 1, characterized in that, The printing yield of the water-based digital adhesive layer is 100~200g / m³. 2 .

4. The direct-to-garment printing method according to claim 1, characterized in that, The drying and curing temperature is 140~170℃, and the curing time is 3~5 minutes.

5. The direct-to-garment printing method according to claim 1, characterized in that, The interval between printing the water-based digital adhesive layer and the white ink layer is 0.05 to 0.3 seconds; the interval between printing the white ink layer and the colored ink layer is 0.05 to 0.3 seconds.

6. The water-based digital adhesive according to claim 5 specifically comprises, by mass fraction: Waterborne polyurethane-acrylate emulsion, 20%–35%; Self-crosslinking acrylic emulsion, 10%–25%; Moisturizer, 5%–12%; Wetting agent, 0.1%–0.5%; Defoamer, 0.1%–0.5%; Leveling agent, 0.05-0.2%; pH adjuster, 0.1%–0.5%; Fungicide, 0.2%–1%; Crosslinking accelerator, 0.1%–0.5%; Deionized water, balance.

7. The solid content of the waterborne polyurethane-acrylate emulsion according to claim 6 is 30-40%, wherein the mass ratio of polyurethane to acrylate is 1.0-2.0:1, the molecular weight of polyurethane is 25,000-35,000 g / mol, and the molecular weight of acrylate is 100,000-150,000 g / mol. The self-crosslinking acrylate emulsion has a solid content of 40-60%, and the molecular weight of the acrylate is 100,000-150,000 g / mol.

8. The crosslinking accelerator according to claim 7 comprises any one or a combination of two or more of zinc salts, magnesium salts, and zoline compounds.

9. The printed fabric obtained by the direct-to-garment printing method according to any one of claims 1-8, characterized in that, Including those stacked sequentially along the thickness direction: Base fabric, water-based digital adhesive layer, white ink layer, and colored ink layer; The penetration depth of the water-based digital adhesive layer into the base fabric is less than 20 μm.

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