Pretreatment-fluid-free ink for direct injection of cloth and preparation method of pretreatment-fluid-free ink

Abstract

The invention discloses pretreatment-fluid-free ink for direct injection of cloth and a preparation method of the pretreatment-fluid-free ink. The viscosity of the pretreatment-fluid-free ink for direct injection of the cloth is 3.5-4.5 mPa.s, and the surface tension of the pretreatment-fluid-free ink for direct injection of the cloth is 32-36 mN / m. The water-based nano polyurethane resin adopted by the invention is superfine and uniform in particle size, excellent in film-forming property and almost zero in VOC (volatile organic compound) content, and has a synergistic effect with the color paste and the fastness improver in the ink, so that the problems of blooming, interpenetration, fading and the like caused by no use of a pretreatment solution can be avoided to a great extent, and bright color and washing resistance can be kept as far as possible; and the environment-friendly requirement is considered. The printing ink has good color expression capability, can be directly printed under the condition that a fabric is not treated by a pretreatment liquid, and achieves a color expression effect similar to that of the pretreatment liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of printing of textiles, in particular to a pretreatment-free liquid ink for direct printing of cloth and a preparation method thereof. BACKGROUND

[0002] Textiles using direct printing ink technology usually need to be pretreated before printing. The pretreatment liquid is cationic, and the direct printing ink is anionic. After direct printing, the ink is combined and locked to prevent the ink from penetrating into the fiber and forming bright colors. However, the pretreatment process before direct printing is complicated, so it is crucial to develop a direct printing ink that does not require a pretreatment process and relies solely on the direct printing ink process to achieve the effect of pretreatment.

[0003] Chinese patent CN102558959B discloses a pretreatment-free direct printing reactive dye ink, which mixes 5% sodium bicarbonate with 95% fresh water as a steam liquid and places it in a color fixing steam oven at 102-105℃ for color fixing. This eliminates the use of sodium alginate, alkali and urea in the pretreatment and sizing components of the fabric, and also solves the technical problem of color enhancement with a large amount of urea in the fabric fiber and the wastewater discharge problem when removing urea, but increases the complexity of the process during color development. Chinese patent application CN110591448A discloses a high pigment concentration digital direct printing textile coating ink and a preparation method thereof. The water-based polyurethane resin uses polyol segments to give the resin good flexibility, avoiding ink breakage during printing, and making the ink have good printing smoothness. However, the textile still needs to be pretreated, and the printing process of the textile has not been optimized. SUMMARY

[0004] In order to develop a direct printing ink that does not require a pretreatment process and relies solely on the direct printing ink process to achieve the effect of pretreatment, the first aspect of the present application provides a pretreatment-free liquid ink for direct printing of cloth, the viscosity of the pretreatment-free liquid ink for direct printing of cloth is 3.5-4.5 mPa·s, and the surface tension of the pretreatment-free liquid ink for direct printing of cloth is 32-36 mN / m.

[0005] As an implementation, the viscosity of the pretreatment-free liquid ink for direct printing of cloth is 3.8-4.2 mPa·s, and the surface tension of the pretreatment-free liquid ink for direct printing of cloth is 32-35.5 mN / m.

[0006] The viscosity of the ink is controlled to be 3.8-4.2 mPa·s and the surface tension is controlled to be 32-35.5 mN / m in the present application, which ensures good flow performance of the ink in the pipeline and the formation of uniform and stable droplet shape when the ink is sprayed out of the nozzle. The ink exhibits good flow performance, standby performance, color effect, dry / wet rub fastness and washing fastness during printing, which can meet the printing needs of industrial nozzles and adapt to many pre-treatment liquid-free use scenarios.

[0007] As an embodiment, the preparation raw material of the fabric direct-jet pre-treatment liquid-free ink includes, in terms of weight percentage, 15%-40% of polyol, 2%-21% of auxiliary agent, 10%-20% of water-based nano polyurethane resin, 30%-45% of water-based nano colorant, and deionized water supplemented to 100%.

[0008] As an embodiment, the polyol includes at least one of glycerol, pentaerythritol, neopentyl glycol, ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, diethylene glycol, trimethylolpropane or glycerol.

[0009] As an embodiment, the glass transition temperature of the water-based nano polyurethane resin is ≤90℃; and the solid content of the water-based nano polyurethane resin is 30wt%-40wt%.

[0010] As an embodiment, the glass transition temperature of the water-based nano polyurethane resin is ≤25℃.

[0011] As an embodiment, the elongation at break of the water-based nano polyurethane resin is ≥200%, and the tensile strength is ≥10 MPa.

[0012] As an embodiment, the water-based nano polyurethane resin includes TAKELAC TM W-6061, TAKELAC TM W-6110, UW-1005E of UBE, ST-013, WH-1030 of Guangzhou Haoyi New Material Technology Co., Ltd. WH-1030, WH-2098, PU-310, UC-1381, P-2071 of Guangzhou Zhongyuli New Material Technology Co., Ltd., or SUNPLEX PUE813 of Japan Muramatsu Chemical.

[0013] This application utilizes a water-based nano-polyurethane resin with a glass transition temperature ≤25℃, elongation at break ≥200%, and tensile strength ≥10MPa. This effectively encapsulates pigment particles, resulting in uniform film formation and lifelike colors, thus enhancing printing color. The reason may be that polyurethane resins with low glass transition temperatures have better flexibility, providing a good encapsulation effect for pigment particles. Furthermore, water-based nano-polyurethane resins with a solid content of 30wt%-40wt% form dense films with excellent film-forming effects. Under optimized mechanical properties, the water-based nano-polyurethane resin of this application can give textile printing products good dry / wet rubbing fastness and wash fastness. Due to the adhesive properties of the resin itself, its inherent adhesion after film formation can play a certain role in color blocking on the textile surface, better "locking in" the ink and ensuring that the ink does not penetrate into the fiber interior, resulting in higher color saturation and thus vibrant colors. In addition, the resin can also act as a dispersion medium; the hydrophilic groups of the resin (such as carboxylic acid groups) can be adsorbed on the surface of pigment particles, forming steric hindrance or charge stabilization, preventing pigment aggregation and improving dispersion uniformity.

[0014] In one embodiment, the solid content of the aqueous nano-color paste is 15wt%-22wt%, and the particle size of the aqueous nano-color paste is 20-90nm.

[0015] In one embodiment, the water-based nano-pigment contains 35%-45% of the ink by mass.

[0016] As one embodiment, the aqueous nano-colorant comprises CAB-O- from Cabot Corporation, USA. 740Y, CAB-O- At least one of the following: 470Y series or Kao LUNAJETA series Y, LUNAJET B series Y, LUNAJET S special color series Y from Xingtianwai Chemical (Shanghai) Co., Ltd., or COSMOS COLORWHD0185A YELLOW and COSMOS COLOR WHD0190B YELLOW from Zhuhai Dongyang Color Materials Co., Ltd.

[0017] This application uses water-based nano-pigment pastes with a solid content of 15wt%-22wt% and a particle size of 20-90nm, which can achieve highly saturated and vibrant printing results. This is likely because the small-particle-size water-based nano-pigment paste ink exhibits better uniformity and stability, and the pigment is more compatible with the resin in the ink system, resulting in better aging resistance and ensuring long-term stability. This achieves better coloring performance while meeting the requirements for formulation stability and other printing performance requirements.

[0018] In one embodiment, the additives comprise, by weight percentage of the ink: 2%-10% solid humectant, 0.1%-5% surfactant, 0.1%-2% defoamer, 0.1%-2% bactericide, 0.1%-1.5% pH buffer, and 0.001%-0.5% fastness enhancer.

[0019] In one embodiment, the solid humectant includes at least one of betaine, trehalose, erythritol, or urea.

[0020] In one embodiment, the defoamer includes at least one of alkoxy defoamers, silicone defoamers, sulfosuccinate defoamers, or modified alkoxy defoamers.

[0021] In one embodiment, the defoamer includes Evonik's... Foamex 825 defoamer, BYK-018, BYK-1616, BYK-8820 silicone defoamers from BYK Chemicals, or BASF's... WE3120 WE3240 WE3488 At least one of the WE3650 type high-efficiency low-foaming wetting agents.

[0022] In one embodiment, the surfactant includes at least two of the following: an amine-containing wetting and dispersing agent, an organosilicon surface aid, or an ethylene oxide series surfactant.

[0023] In one embodiment, the surfactant includes BYKJET-9131, BYKJET-9177, and DISPERBYK-184TF wetting and dispersing agents from BYK Chemicals, and BYK-345, BYK-3481, and BYK-3754 silicone surface additives from BYK Chemicals, or Evonik's... 104PA 440 465. At least two of the 485.

[0024] As one embodiment, the pH buffer includes at least one of dimethylethanolamine, neutralizing amine Alpamine N41, or industrial amine AMP-95.

[0025] As one implementation, the bactericide includes at least one of BASF's Protectol™ HT and Protectol™ PE, Lonza's ZINC OMADINE™ FPS, and Guangzhou Shenyue Trading Co., Ltd.'s Aisjia S+AM908.

[0026] As one embodiment, the fastness enhancer includes at least one of ASUKD GT, ASUKD 1616, ASUKD 1605, ASUKD MS from Assud (Spain) or Trixene BI 201, Trixene BI 220, Trixene DP9C / 323, Trixene DP9C / 537 from Lanxess (Germany).

[0027] A second aspect of the present invention provides a method for preparing the aforementioned fabric direct-to-garment ink without pretreatment, comprising the following steps:

[0028] Mix deionized water, polyol, additives, and water-based nano polyurethane resin, grind them, add water-based nano color paste, grind and stir for 20-40 minutes to obtain a mixture;

[0029] The mixture is filtered under negative pressure to eliminate air bubbles, resulting in a pretreatment-free ink for direct fabric printing.

[0030] As one embodiment, the preparation method of the fabric direct-to-garment ink without pretreatment includes the following steps:

[0031] Mix deionized water, polyol, solid humectant, surfactant, defoamer, bactericide, and pH buffer, grind at 150 rpm for 5-10 min, add fastness enhancer and water-based nano polyurethane resin, grind at 300 rpm for 5-10 min, add water-based nano color paste, grind and stir for 20-40 min to obtain a mixture.

[0032] The mixture is filtered under negative pressure to eliminate air bubbles, resulting in a pretreatment-free liquid ink for direct fabric printing.

[0033] In one embodiment, after adding the aqueous nano-color paste, the grinding and stirring rate is 400-800 rpm.

[0034] In one embodiment, after adding the aqueous nano-color paste, the grinding and stirring rate is 600 rpm.

[0035] In one embodiment, the pore size of the filter membrane used in the negative pressure filtration is 0.22-0.45 μm.

[0036] The negative pressure suction filtration process involves first passing the filter through a 0.45μm pore size membrane, and then through a 0.22μm pore size membrane.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The fabric direct-jet ink of the present invention, by controlling the viscosity of the ink to be 3.8-4.2 mPa·s and the surface tension to be 32-35.5 mN / m, ensures good flow performance of the ink in the pipeline and that the ink can form a uniform and stable droplet shape when it is ejected from the nozzle.

[0039] (2) The fabric direct-to-garment ink without pretreatment liquid described in this invention uses water-based nano polyurethane resin with a glass transition temperature ≤25℃, elongation at break ≥200%, and tensile strength ≥10MPa, which can effectively encapsulate pigment particles, resulting in uniform film formation and realistic colors, thus helping to improve printing color.

[0040] (3) The fabric direct-to-garment ink of the present invention uses water-based nano-color paste with a solid content of 15wt%-22wt% and a particle size of 20-90nm, which can print a high-saturation and bright color printing effect.

[0041] (4) The fabric direct-to-garment ink of the present invention uses water-based nano polyurethane resin with ultra-fine and uniform particle size, excellent film-forming performance, and almost zero VOC content. It works synergistically with the color paste and fastness enhancer in the ink, which can largely avoid problems such as smudging, mutual penetration and fading caused by not using pretreatment liquid. It can maintain the color as bright as possible and be washable, while also taking into account environmental protection requirements.

[0042] (5) The fabric direct-to-print ink without pretreatment liquid described in this invention has good color performance capabilities and can be printed directly on the fabric without pretreatment liquid treatment, and achieves a color performance effect similar to that of using pretreatment liquid. Detailed Implementation

[0043] The pretreatment-free ink for direct fabric printing of this application can be widely used in the light-colored home textile market and other fields. This solution includes inks in eight colors: BK, C, M, Y, OR, R, B, and G. The following discussion of the technical solution, technical effects, and specific implementation methods will be based on yellow ink (Y) as an example.

[0044] Example 1

[0045] A fabric direct-to-garment ink that requires no pretreatment solution is prepared by means of the following raw materials by weight percentage: 23% polyol, 6.8% additives, 15% water-based nano-polyurethane resin, 35% water-based nano-pigment, and deionized water to bring the total to 100%.

[0046] The waterborne nano-polyurethane resin has a glass transition temperature of 25°C, a solid content of 30 wt%, an elongation at break ≥200%, and a tensile strength ≥10 MPa. It was purchased from Mitsui Chemicals Group, Japan, under the brand name TAKELAC. TMW-6061.

[0047] The aqueous nano-color paste has a solid content of 15wt%-22wt% and a particle size of 70nm. It was purchased from Cabot Corporation, USA, under the brand name CAB-O-. 740Y.

[0048] The polyol is a combination of glycerol and 1,2-propanediol, accounting for 8% of the ink's mass fraction and 15% of the 1,2-propanediol.

[0049] The additives, by weight percentage of the ink, include: 5% solid humectant, 1% surfactant, 0.3% defoamer, 0.1% bactericide, 0.1% pH buffer, and 0.3% fastness enhancer.

[0050] The solid humectant is erythritol;

[0051] The surfactant is a combination of BYK-3481 silicone surface additive and BYKJET-9177 wetting and dispersing agent, both purchased from BYK Chemical, with a weight ratio of 0.5:0.5.

[0052] The defoamer was purchased from BYK Chemicals and its brand name is BYK-1616.

[0053] The bactericide was purchased from BASF and its brand name is Protectol™ HT.

[0054] The pH buffer was purchased from Dow Chemical Company, USA, and its product name is AMP-95 (Multifunctional Additive).

[0055] The fastness enhancer was purchased from Lanxess, Germany, and its brand name is Trixene BI 201.

[0056] A method for preparing a pretreatment-free ink for direct fabric printing includes the following steps:

[0057] Mix deionized water, polyol, solid humectant, surfactant, defoamer, bactericide, and pH buffer, grind at 150 rpm for 10 min, add fastness enhancer and water-based nano polyurethane resin, grind at 300 rpm for 10 min, add water-based nano color paste, grind and stir at 600 rpm for 30 min to obtain a mixture.

[0058] After the mixture meets the standard requirements, it is filtered under negative pressure to eliminate air bubbles, thus obtaining a pretreatment-free liquid ink for direct fabric printing.

[0059] The negative pressure filtration is performed by using a 0.45μm pore size filter membrane and a 0.22μm pore size filter membrane once each under a negative pressure of 0.05MPa.

[0060] The bubble elimination method involves negative pressure defoaming at 0.05 MPa.

[0061] The standard requires that the ink viscosity be 3.8-4.2 mPa·s, the spectral peak position of the yellow ink be 404.00±2.00 nm, and the spectral peak intensity of the yellow ink be in the range of 0.630-0.710 Abs at a dilution ratio of 1:5000.

[0062] Example 2

[0063] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the weight percentage of the water-based nano pigment is 40% and the weight percentage of 1,2-propanediol is 14%.

[0064] Example 3

[0065] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the weight percentage of the water-based nano-polyurethane resin is 20% and the weight percentage of 1,2-propanediol is 9%.

[0066] Example 4

[0067] A pretreatment-free ink for direct-to-garment fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the surfactant is BYK-3481 organosilicon surface additive. The combination of type 440 wetting and dispersing agents has a weight ratio of 0.5:0.5. 440 purchased from WinCreation.

[0068] Example 5

[0069] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the fastness enhancer is purchased from Assut in Spain, with the brand name ASUKD 1616.

[0070] Comparative Example 1

[0071] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the weight percentage of the water-based nano-polyurethane resin is 35% and the weight percentage of 1,2-propanediol is 5%.

[0072] Comparative Example 2

[0073] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the weight percentage of the water-based nano pigment is 50% and the weight percentage of 1,2-propanediol is 10%.

[0074] Comparative Example 3

[0075] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the weight percentage of 1,2-propanediol is 20%.

[0076] Comparative Example 4

[0077] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the solid humectant is sorbitol.

[0078] Comparative Example 5

[0079] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the pH buffer is ammonia.

[0080] Comparative Example 6

[0081] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the weight percentage of the defoamer is 3%.

[0082] Comparative Example 7

[0083] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the grinding and stirring rate is 200 rpm after adding the water-based nano pigment.

[0084] Comparative Example 8

[0085] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the amount of the fastness enhancer added is 0.

[0086] Comparative Example 9

[0087] A pretreatment-free ink for direct fabric printing and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the surfactant is 1.0 wt%. Superwet-340 surface active agent.

[0088] Comparative Example 10

[0089] A pretreatment-free ink for direct fabric printing and its preparation method are described. The specific implementation method is the same as in Example 1, except that the water-based nano-polyurethane resin has a glass transition temperature of 90°C, a solid content of 30wt%, an elongation at break of ≥200%, and a tensile strength of ≥10MPa. It was purchased from Mitsui Chemicals and its brand name is TAKELACTM W-6010.

[0090] Comparative Example 11

[0091] A pretreatment-free ink for direct inkjet printing on fabrics and its preparation method. The specific implementation is the same as that of Example 1, except that the solid content of the aqueous nano-color paste is 15wt%-22wt%, the particle size of the aqueous nano-color paste is 150nm, which is purchased from Anhui Shaner Chemical Technology Co., Ltd., and the color paste has the brand number SCN-3042.

[0092] Performance Testing

[0093] 1. Fluency: Under the conditions of an ambient temperature of 20-35°C and an ambient humidity of 55-75%, on a Hongmei HM-1800B-K24 machine, with a Kyocera QA print head as the test carrier, the inks prepared in the examples and comparative examples were used to print color blocks for 100 meters on the machine (the specific test conditions are shown in Table 1), and the degree of broken needles was observed and recorded. When printing a pure color block of yellow, if the number of broken needles within 100 meters of printing is within 3 needles (including 3 needles), it is considered qualified; otherwise, it is considered unqualified. The test results of printing fluency are shown in Table 2.

[0094] 2. Standby Performance: Under the conditions of an ambient temperature of 20-35°C and an ambient humidity of 55-75%, on a Hongmei HM-1800B-K24 machine, with a Kyocera QA print head as the test carrier, the inks prepared in the examples and comparative examples were used for standby performance testing. If a complete test strip can still be printed after 60 minutes of flash-free standby, the standby performance is considered qualified; if there is blurring or broken needles after 60 minutes of standby, it is considered unqualified. The test results are shown in Table 2.

[0095] 3. Dry / Wet Rub Fastness: According to the relevant requirements in GB / T 3920-2008 "Textiles - Tests for colour fastness - Colour fastness to rubbing", the dry / wet rub fastness of the yellow color blocks printed with the inks prepared in the examples and comparative examples on woven fabrics was tested, and the test results were evaluated according to the relevant requirements. The test results were compared with the grey scale for staining with 5 grades to judge their grades. The larger the grade value, the better the dry / wet rub fastness. The test results are shown in Table 2.

[0096] 4. Wash Fastness: According to the relevant requirements in GB / T 5713-2013 "Textiles - Tests for colour fastness - Colour fastness to water", the wash fastness of the yellow color blocks printed with the inks prepared in the examples and comparative examples on woven fabrics was tested, and the test results were evaluated according to the relevant requirements. In the test result judgment process, it was based on the color difference between the original sample and the faded sample, and judged with the grey scale according to the color change situation. The larger the value, the better the wash fastness. The test results are shown in Table 2.

[0097] 5. Color Performance: Using the Hongmei HM-1800B-K24 printer and a Kyocera QA printhead as the test medium, the inks prepared in the examples and comparative examples were printed on untreated woven fabric. The printed pattern was a solid yellow block (printing size 0.26m × 0.20m, ink volume 100%, other settings were the same as in Table 1). The pattern was compared with that printed on a pretreated fabric sample with ordinary ink under the same conditions. The test was conducted using a Sanenshi SR-66 dual-aperture colorimeter. The color deviation was evaluated based on the Lab value and total color difference ΔE obtained from the test to determine the color difference. The judgment criteria are as follows: A solid yellow patch printed on a pre-treated fabric sample using ordinary conveyor ink (sourced from the machine itself, supplied by Huizhou Hanhong Industrial Co., Ltd.) suitable for Kyocera QA printheads, is used as the standard sample. Definition A: The total color difference ΔE < 1 when tested with the colorimeter; Definition B: The total color difference ΔE < 1.5 when tested with the colorimeter; Definition C: The total color difference ΔE < 2 when tested with the colorimeter; Definition D: The total color difference ΔE ≥ 2 when tested with the colorimeter. The test results are shown in Table 2.

[0098] Table 1

[0099]

[0100]

[0101] Table 2

[0102]

[0103] Comparative Example 1 changed the resin content in the ink. Due to the excessive resin content, the ink viscosity was too high, resulting in poor printing quality.

[0104] Comparative Example 2 changed the content of pigment in the ink. Because the proportion of pigment in the ink was too high, the entire formula system was not coordinated and the printhead cleaning condition was poor. Therefore, the smoothness and standby performance of Comparative Example 2 were both poor.

[0105] Comparative Example 3 altered the viscosity of the ink. Since the increased viscosity affected the ink droplet ejection speed, the printed pattern in Comparative Example 3 had poorer color.

[0106] Comparative Example 4 changed the type of solid humectant in the ink. Since erythritol is not hygroscopic, is stable at high temperatures, and is also stable in a wider pH range (good compatibility, which can avoid possible crystallization problems), the humectant of Comparative Example 4 was replaced with sorbitol (which has relatively poor compatibility with organic solvents). The ink's humectant performance decreased, and its smoothness and standby performance were relatively poor.

[0107] Comparative Example 5 changed the type of pH buffer in the ink. Compared with AMP-95, ammonia is more volatile, and the pH stability of the system it adjusts is relatively poor. A stable alkaline pH environment is of great significance for the dispersibility, stability and viscosity stability of pigment particles in the ink system. In addition to the advantages of high alkalinity, high buffering capacity, low odor, low volatility and non-yellowing, AMP-95 also has the advantages of sterilization and improving the dispersibility of pigment particles. Therefore, after replacing the pH buffer with ammonia, the pH fluctuation of the ink is relatively large, which causes a certain degree of deterioration in its performance. As a result, the dry / wet rubbing fastness and water wash fastness of the pattern printed in Comparative Example 5 are poor, and the color performance is also relatively average.

[0108] Comparative Example 6 altered the proportion of the defoamer "BYK-1616" in the paint ink. Excessive addition of the defoamer can easily lead to printing defects, affect ink flow (damages the viscosity and rheological properties of the ink system), and adversely affect the dry / wet rubbing fastness and wash fastness of the printed ink products. Therefore, Comparative Example 6 has poor flow and standby performance, and its dry / wet rubbing fastness and wash fastness are also relatively average.

[0109] Comparative Example 7 changed the parameter "stirring speed after adding pigment paste" in the ink preparation process. Reducing the stirring speed is not conducive to the full dispersion of pigment particles, which prevents them from being evenly combined with the resin. This is very detrimental to color fastness and color performance. Therefore, the dry / wet rubbing fastness, water wash fastness and color performance of Comparative Example 7 are all poor.

[0110] Comparative Example 8 altered the ink composition. The fastness enhancer plays a crucial role in "locking in" pigment particles on the fabric surface. Without the fastness enhancer, the dry / wet rubbing fastness and wash fastness of the printed pattern in Comparative Example 8 were significantly poor.

[0111] Comparative Example 9 changed the type of surfactant in the ink, changing the "surfactant compound system of organosilicon surface additive + wetting and dispersing agent" in Example 1 to the "single wetting surfactant" in Comparative Example 9. A suitable surfactant can adjust the surface tension of the ink to a level that meets the printing requirements of the printhead (which is conducive to the formation of ink droplets, otherwise oblique spraying will occur), and at the same time help the dispersion and uniform distribution of pigment particles, making the system more stable. The smoothness and standby performance of Comparative Example 9 using a single surfactant are both poor.

[0112] Comparative Example 10 changed the type of water-based nano-polyurethane resin in the ink. The low Tg resin has a lower glass transition temperature, which gives it good flexibility (soft feel) and adhesion (ensuring color fastness). This gives it good film-forming properties (effectively encapsulates pigment particles to ensure color fidelity). In contrast, the pattern printed by Comparative Example 10, which uses high Tg resin, has poor dry / wet rubbing fastness and wash fastness, and the color performance is also less than average.

[0113] Comparative Example 11 altered the type of water-based nano-pigment paste in the ink, due to CAB-O- The 470Y color paste has a relatively small average particle size, finer particles, better dispersibility, and a higher specific surface area (stronger tinting strength). This allows it to interact better with other components in the system, reducing pigment particle aggregation. Therefore, CAB-O- The ink system formulated with 470Y is more stable; however, due to the larger particle size of SCN-3042 pigment, it has stronger hiding power but lower gloss. Therefore, the inkjet color of the ink system formulated with SCN-3042 will be lighter and cannot guarantee the printing effect, so its color performance will be relatively average.

[0114] The inks prepared in Examples 1-5 of this application have better printing smoothness, standby performance, abrasion resistance and color fastness to washing than the comparative examples. The printed patterns adhere more closely to the fabric and have excellent color performance.

Claims

1. A pretreatment-free ink for direct fabric printing, characterized in that, The viscosity of the fabric direct-to-garment ink without pretreatment is 3.5-4.5 mPa·s, and the surface tension of the fabric direct-to-garment ink without pretreatment is 32-36 mN / m.

2. The fabric direct-to-garment ink without pretreatment liquid according to claim 1, characterized in that, The raw materials for preparing the fabric direct-to-garment ink without pretreatment liquid include, by weight percentage: 15%-40% polyol, 2%-21% additives, 10%-20% water-based nano polyurethane resin, 30%-45% water-based nano pigment, and deionized water to make up to 100%.

3. The fabric direct-to-garment ink without pretreatment liquid according to claim 2, characterized in that, The waterborne nano-polyurethane resin has a glass transition temperature of <90℃; the solid content of the waterborne nano-polyurethane resin is 30wt%-40wt%.

4. The fabric direct-to-garment ink without pretreatment liquid according to claim 2, characterized in that, The solid content of the aqueous nano-color paste is 15wt%-22wt%, and the particle size of the aqueous nano-color paste is 20-90nm.

5. The fabric direct-to-garment ink without pretreatment liquid according to claim 2, characterized in that, The additives, by weight percentage of the ink, include: 2%-10% solid humectant, 0.1%-5% surfactant, 0.1%-2% defoamer, 0.1%-2% bactericide, 0.1%-1.5% pH buffer, and 0.001%-0.5% fastness enhancer.

6. The fabric direct-to-garment ink without pretreatment liquid according to claim 5, characterized in that, The solid humectant includes at least one of betaine, trehalose, erythritol, or urea.

7. The fabric direct-to-garment ink without pretreatment liquid according to claim 5, characterized in that, The surfactant includes at least two of the following: amine-containing wetting and dispersing agents, organosilicon surface aids, or ethylene oxide series surfactants.

8. The fabric direct-to-garment ink without pretreatment liquid according to claim 5, characterized in that, The pH buffer includes at least one of dimethylethanolamine, neutralizing amine Alpamine N41, or industrial amine AMP-95.

9. A method for preparing a pretreatment-free ink for direct fabric printing according to any one of claims 2-8, characterized in that, Includes the following steps: Mix deionized water, polyol, additives, and water-based nano polyurethane resin, grind them, add water-based nano color paste, grind and stir for 20-40 minutes to obtain a mixture; The mixture is filtered under negative pressure to eliminate air bubbles, resulting in a pretreatment-free liquid ink for direct fabric printing.

10. The method for preparing the fabric direct-to-garment ink without pretreatment liquid according to claim 9, characterized in that, After adding the water-based nano pigment, the grinding and stirring rate is 400-800 rpm.

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