Positive charge reactive printing method for all-cotton fabric

Abstract

The invention discloses a positive charge reactive printing method for an all-cotton fabric, and relates to the technical field of textile printing and dyeing, in particular to a reactive printing method for endowing the surface of the all-cotton fabric with positive charges and cooperating with a low-salt / urea-free reaction system. The method comprises the following process steps: S1, fabric cationization pretreatment; s2, construction of a cation enhancement and anchoring layer: padding the fabric obtained in the step S1 with cation enhancement liquid, and performing thermal crosslinking to form an anchored cation enhancement layer; s3, preparing urea-free / low-salt reactive printing paste C; s4, applying the printing paste to the fabric obtained in the step S2, and pre-drying; s5, ageing and color fixing; s6, post-treatment and soaping: carrying out cold washing, warm washing and soaping on the aged fabric to obtain a printed finished product. By constructing a positive charge layer on the surface of the all-cotton fabric and combining an alkaline microcapsule controlled release technology, efficient fixation of the reactive dye is realized, the use amount of urea and salt is remarkably reduced, and the color fastness and environmental protection property are improved.

Description

Technical Field

[0001] This invention relates to the field of textile printing and dyeing technology, specifically to a reactive printing method that imparts a positive charge to the surface of cotton fabric and combines it with a low-salt / urea-free reaction system. Background Technology

[0002] Cotton fabrics are widely used in clothing and home textiles due to their comfortable feel and good breathability. Reactive dyes, as the main dye system for dyeing cotton, offer bright colors and good colorfastness, but traditional printing processes have some prominent problems: First, to improve dye solubility and dyeing rate, traditional processes require the addition of large amounts of urea and inorganic salts, which not only increases printing costs but also results in the discharge of wastewater with high COD and high salinity, causing serious environmental pollution. Second, cotton fibers carry a certain negative charge under neutral or weakly alkaline conditions, which creates electrostatic repulsion with anionic reactive dyes, leading to low dye fixation efficiency. This needs to be overcome by increasing the salt concentration, further increasing the burden on wastewater treatment. In addition, traditional processes are time-consuming and water-intensive in steaming fixation and post-treatment, resulting in low overall process efficiency. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a positive charge reactive printing method for all-cotton fabrics. This method achieves efficient fixation of reactive dyes by constructing a positive charge layer on the surface of the all-cotton fabric and combining it with alkaline microcapsule controlled release technology. This significantly reduces the amount of urea and salt used, and improves color fastness and environmental friendliness.

[0004] To achieve the above objectives, the present invention employs the following process steps: S1. Fabric cationization pretreatment: The cotton fabric is treated with a cationization solution containing a quaternary ammonium salt precursor and baked to fix it, obtaining a cotton fabric with a positively charged surface; S2. Cation reinforcement and anchoring layer construction: The fabric obtained in step S1 is impregnated with a cation reinforcement solution and thermally crosslinked to form an anchored cation reinforcement layer; S3. Preparation of urea-free / low-salt reactive printing paste C: A reactive printing paste is prepared that is urea-free and has a total inorganic salt content not exceeding 5 g / kg. The printing paste includes reactive dyes, thickeners, humectants, and alkaline microcapsules; S4. The printing paste is applied to the fabric from step S2 and pre-dried; S5. Steaming and color fixing; S6. Post-treatment and soaping: The steamed fabric is subjected to cold washing, warm washing, and soaping to obtain the printed finished product.

[0005] Step S1. Fabric cationization pretreatment: The cotton fabric that has undergone conventional descaling and bleaching is padded or impregnated with cationization solution A containing quaternary ammonium salt precursor, baked and fixed, then washed, neutralized and dried to obtain a cotton fabric with a positively charged surface.

[0006] The cationizing solution A comprises the following raw materials in parts by weight: 40–80 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC), 15–20 parts of alkali, 0.5–2 parts of penetrant, 0.5–2 parts of buffer / stabilizer, and the balance being water; the manufacturing process of the cationizing solution A is as follows: padding process with a roll-off rate of 70–90%; reaction at 60–80 °C for 10–20 min, followed by baking and fixation, and then washing with water until neutral.

[0007] Specifically, step S2 involves immersing the fabric obtained in step S1 in cationic reinforcing liquid B and then thermally crosslinking it to make the positively charged layer more stable and washable.

[0008] The reinforcing liquid B contains the following raw materials in parts by weight: 5–20 parts of polydimethyldiallylammonium chloride (PDADMAC), 5–15 parts of polyvinyl alcohol (PVA), 10–25 parts of formaldehyde-free organic acid crosslinking agent (citric acid), and 0.5–1 part of wetting agent; the specific process is as follows: padding to achieve a roll-off rate of 70–85%, baking at a temperature of 120–150°C for 1–3 minutes, and cooling for later use.

[0009] In step S3, the printing paste C is composed of the following raw materials in parts by weight, per kilogram of printing paste: reactive dye (monochlorotriazine / vinyl sulfone type) 10–120g; natural thickener (sodium alginate) 40–60g; humectant (glycerin) 20–30g; alkaline microcapsules D 20–40g (the core of alkaline microcapsules D is... or The wall material is a composite of PVA / calcium alginate / edible polysaccharides, which is released upon contact with temperature or through penetration; 2–6g of flow aid / anti-recurrence agent; and deionized water to bring the total to 1000g.

[0010] Step S4 involves rotary or flat screen printing, applying printing paste C to the fabric, and pre-drying at 80–100°C for 2–5 minutes with a moisture content of 5–10%.

[0011] Step S5 specifically involves: steaming the pre-dried fabric under saturated humid heat conditions at a temperature of 100–105 °C for 6–10 min; or steaming it under low-pressure saturated atomization at a temperature of 98–102 °C for 8–12 min. During steaming, microcapsules D release alkali triggered by temperature and humidity, which, combined with the electrostatic adsorption of the cation layer, allows the reactive dye to rapidly and directionally react and fix on the fiber surface / surface layer.

[0012] Step S6 specifically involves: first rinsing with cold water, then rinsing with warm water at 40–60°C, adding 1–2 g / L of soap and rinsing at 95°C for 10–15 minutes until neutral. Then dehydrate and dry.

[0013] The working principle of this invention is as follows: First, quaternary ammonium salt groups are introduced onto the surface of cotton fibers through cationization pretreatment (step S1), giving the fibers a stable positive charge. Then, through cation reinforcement and anchoring layer construction (step S2), a dense and wash-resistant cation reinforcement layer is formed on the fiber surface using PDADMAC, PVA, and citric acid crosslinking, thereby significantly improving the strength and durability of the positively charged layer. In the printing process, this invention uses a urea-free / low-salt reactive printing paste (step S3), in which a thickener ensures the clarity of the printed pattern, glycerin provides moisturizing, and alkaline microcapsules are gradually released during evaporation triggered by temperature and humidity. or This provides the necessary alkaline conditions for the reaction at the appropriate time. This sequential release design avoids premature action of alkaline substances, which could lead to decreased paste stability and also prevents color floating. After printing and pre-drying (step S4), the fabric undergoes steam fixation in saturated steam or atomized steam (step S5). The cationic layer electrostatically adsorbs the anionic dye molecules, and the alkaline environment released by the microcapsules causes the dye to covalently bond with the hydroxyl groups on the cellulose molecules, thus achieving rapid and efficient color fixation.

[0014] The beneficial effects of this invention, achieved by constructing a stable positively charged layer on the surface of cotton fabrics and combining it with a urea-free, low-salt reactive printing paste system, are as follows: After cationization and cation-enhanced treatment, the fabric exhibits significant electrostatic adsorption of anionic dyes, enriching the dyes on the fiber surface and facilitating their reaction. During steaming, alkaline microcapsules release alkaline substances directionally under temperature and humidity triggering, ensuring a reasonable match between reaction conditions and dye adsorption timing, thereby significantly improving dye utilization and fixation rate. This method not only significantly reduces the use of urea and inorganic salts, lowers COD and salt emissions in wastewater, and improves environmental friendliness, but also shortens steaming time, reduces energy consumption, and improves production efficiency. Simultaneously, due to less floating dye, post-wash water consumption is reduced, alleviating the burden on wastewater treatment. Furthermore, the resulting fabric exhibits bright colors, high color yield, and consistently high fastness to washing and wet / dry rubbing (both grades 4 and above), demonstrating excellent overall performance and significant industrial application value. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1This is a process flow diagram of the present invention. Detailed Implementation

[0017] See Figure 1 As shown, this specific embodiment adopts the following process steps: S1. Fabric cationization pretreatment: The cotton fabric is treated with a cationization solution containing quaternary ammonium salt precursor and baked to fix it, obtaining a cotton fabric with a positively charged surface; S2. Construction of cation reinforcement and anchoring layer: The fabric obtained in step S1 is impregnated with a cation reinforcement solution and thermally crosslinked to form an anchored cation reinforcement layer; S3. Preparation of urea-free / low-salt reactive printing paste C: A reactive printing paste without urea and with a total inorganic salt content not exceeding 5 g / kg is prepared. The printing paste includes reactive dyes, thickeners, humectants, and alkaline microcapsules; S4. The printing paste is applied to the fabric in step S2 and pre-dried; S5. Steaming and fixing; S6. Post-treatment and soaping: The steamed fabric is subjected to cold washing, warm washing, and soaping to obtain the printed finished product.

[0018] Step S1. Fabric cationization pretreatment: The cotton fabric that has undergone conventional descaling and bleaching is padded or impregnated with cationization solution A containing quaternary ammonium salt precursor, baked and fixed, then washed, neutralized and dried to obtain a cotton fabric with a positively charged surface.

[0019] The cationizing solution A comprises the following raw materials in parts by weight: 40–80 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC), 15–20 parts of alkali, 0.5–2 parts of penetrant, 0.5–2 parts of buffer / stabilizer, and the balance being water; the manufacturing process of the cationizing solution A is as follows: padding process with a roll-off rate of 70–90%; reaction at 60–80 °C for 10–20 min, followed by baking and fixation, and then washing with water until neutral.

[0020] Specifically, step S2 involves immersing the fabric obtained in step S1 in cationic reinforcing liquid B and then thermally crosslinking it to make the positively charged layer more stable and washable.

[0021] The reinforcing liquid B contains the following raw materials in parts by weight: 5–20 parts of polydimethyldiallylammonium chloride (PDADMAC), 5–15 parts of polyvinyl alcohol (PVA), 10–25 parts of formaldehyde-free organic acid crosslinking agent (citric acid), and 0.5–1 part of wetting agent; the specific process is as follows: padding to achieve a roll-off rate of 70–85%, baking at a temperature of 120–150°C for 1–3 minutes, and cooling for later use.

[0022] In step S3, the printing paste C is composed of the following raw materials in parts by weight, per kilogram of printing paste: reactive dye (monochlorotriazine / vinyl sulfone type) 10–120g; natural thickener (sodium alginate) 40–60g; humectant (glycerin) 20–30g; alkaline microcapsules D 20–40g (the core of alkaline microcapsules D is... or The wall material is a composite of PVA / calcium alginate / edible polysaccharides, which is released upon contact with temperature or through penetration; 2–6g of flow aid / anti-recurrence agent; and deionized water to bring the total to 1000g.

[0023] Step S4 involves rotary or flat screen printing, applying printing paste C to the fabric, and pre-drying at 80–100°C for 2–5 minutes with a moisture content of 5–10%.

[0024] Step S5 specifically involves: steaming the pre-dried fabric under saturated humid heat conditions at a temperature of 100–105 °C for 6–10 min; or steaming it under low-pressure saturated atomization at a temperature of 98–102 °C for 8–12 min. During steaming, microcapsules D release alkali triggered by temperature and humidity, which, combined with the electrostatic adsorption of the cation layer, allows the reactive dye to rapidly and directionally react and fix on the fiber surface / surface layer.

[0025] Step S6 specifically involves: first rinsing with cold water, then rinsing with warm water at 40–60°C, adding 1–2 g / L of soap and rinsing at 95°C for 10–15 minutes until neutral. Then dehydrate and dry.

[0026] The reactive dye fixation rate of the printed fabric obtained in this specific embodiment is ≥80%, the color fastness to washing is ≥4, and the color fastness to dry / wet rubbing is ≥4 respectively.

[0027] This specific embodiment achieves high fixation rate printing of reactive dyes under urea-free and low-salt conditions.

[0028] First, quaternary ammonium salt groups are introduced onto the surface of cotton fibers through cationization pretreatment (step S1), giving the fibers a stable positive charge. Then, through cation reinforcement and anchoring layer construction (step S2), a dense and wash-resistant cation reinforcement layer is formed on the fiber surface using PDADMAC, PVA, and citric acid crosslinking, significantly improving the strength and durability of the positively charged layer. In the printing process, this invention uses a urea-free / low-salt reactive printing paste (step S3), where a thickener ensures the clarity of the printed pattern, glycerin provides moisturizing, and alkaline microcapsules are gradually released during evaporation triggered by temperature and humidity. or This provides the necessary alkaline conditions for the reaction at the appropriate time. This sequential release design avoids premature action of alkaline substances, which could lead to decreased paste stability and also prevents color floating. After printing and pre-drying (step S4), the fabric undergoes steam fixation in saturated steam or atomized steam (step S5). The cationic layer electrostatically adsorbs the anionic dye molecules, and the alkaline environment released by the microcapsules causes the dye to covalently bond with the hydroxyl groups on the cellulose molecules, thus achieving rapid and efficient color fixation.

[0029] By constructing a stable positively charged layer on the surface of cotton fabrics and combining it with a urea-free, low-salt reactive printing paste system, efficient fixation of reactive dyes on fibers was achieved. After cationization and cation-enhanced treatment, the fabric exhibits significant electrostatic adsorption of anionic dyes, leading to dye enrichment on the fiber surface and easier reaction. During steaming, alkaline microcapsules release alkaline substances directionally under temperature and humidity triggering, ensuring a reasonable match between reaction conditions and dye adsorption timing, thereby significantly improving dye utilization and fixation rate. This method not only significantly reduces the use of urea and inorganic salts, lowering COD and salt emissions in wastewater and improving environmental friendliness, but also shortens steaming time, reduces energy consumption, and improves production efficiency. Simultaneously, due to less floating dye, post-wash water consumption is reduced, alleviating the burden on wastewater treatment. Furthermore, the resulting fabrics exhibit bright colors, high color yield, and consistently high fastness to washing and wet / dry rubbing (both grades 4 and above), demonstrating excellent overall performance and significant industrial application value.

[0030] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for positive charge reactive printing on all-cotton fabrics, characterized in that: The following process steps are adopted: S1. Fabric cationization pretreatment: The cotton fabric is treated with a cationization solution containing quaternary ammonium salt precursor and baked to fix it, so as to obtain cotton fabric with positive charge on the surface; S2. Construction of cationic reinforcement and anchoring layer: The fabric obtained in step S1 is impregnated with cationic reinforcement solution and thermally crosslinked to form an anchored cationic reinforcement layer; S3. Preparation of urea-free / low-salt reactive printing paste C: A reactive printing paste without urea and with a total inorganic salt content not exceeding 5 g / kg is prepared. The printing paste includes reactive dyes, thickeners, humectants, and alkaline microcapsules; S4. The printing paste is applied to the fabric of step S2 and pre-dried; S5. Steaming and color fixing; S6. Post-treatment and soaping: The steamed fabric is subjected to cold washing, warm washing and soaping to obtain the printed finished product.

2. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: Step S1. Fabric cationization pretreatment: The cotton fabric that has undergone conventional descaling and bleaching is padded or impregnated with cationization solution A containing quaternary ammonium salt precursor, baked and fixed, then washed, neutralized and dried to obtain a cotton fabric with a positively charged surface.

3. The method for positive charge reactive printing on all-cotton fabric according to claim 2, characterized in that: The cationizing solution A comprises the following raw materials in parts by weight: 40–80 parts of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC), 15–20 parts of alkali, 0.5–2 parts of penetrant, 0.5–2 parts of buffer / stabilizer, and the balance being water; the manufacturing process of the cationizing solution A is as follows: padding process with a roll-off rate of 70–90%; reaction at 60–80 °C for 10–20 min, followed by baking and fixation, and then washing with water until neutral.

4. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: Specifically, step S2 involves immersing the fabric obtained in step S1 in cationic reinforcing liquid B and then thermally crosslinking it to make the positively charged layer more stable and washable.

5. The method for positive charge reactive printing on all-cotton fabric according to claim 4, characterized in that: The reinforcing liquid B contains the following raw materials in parts by weight: 5–20 parts of polydimethyldiallylammonium chloride (PDADMAC), 5–15 parts of polyvinyl alcohol (PVA), 10–25 parts of formaldehyde-free organic acid crosslinking agent (citric acid), and 0.5–1 part of wetting agent; the specific process is as follows: padding to achieve a roll-off rate of 70–85%, baking at a temperature of 120–150°C for 1–3 minutes, and cooling for later use.

6. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: In step S3, the printing paste C is composed of the following raw materials in parts by weight, per kilogram of printing paste: reactive dye (monochlorotriazine / vinyl sulfone type) 10–120g; natural thickener (sodium alginate) 40–60g; humectant (glycerin) 20–30g; alkaline microcapsules D 20–40g (the core of alkaline microcapsules D is... or The wall material is a composite of PVA / calcium alginate / edible polysaccharides, which is released upon contact with temperature or through penetration; 2–6g of flow aid / anti-recurrence agent; and deionized water to bring the total to 1000g.

7. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: Step S4 involves rotary or flat screen printing, applying printing paste C to the fabric, and pre-drying at 80–100°C for 2–5 minutes with a moisture content of 5–10%.

8. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: Step S5 specifically involves: steaming the pre-dried fabric under saturated humid heat conditions at a temperature of 100–105 °C for 6–10 min; or steaming it under low-pressure saturated atomization at a temperature of 98–102 °C for 8–12 min. During steaming, microcapsules D release alkali triggered by temperature and humidity, which, combined with the electrostatic adsorption of the cation layer, allows the reactive dye to rapidly and directionally react and fix on the fiber surface / surface layer.

9. The method for positive charge reactive printing on all-cotton fabric according to claim 1, characterized in that: Step S6 specifically involves: first rinsing with cold water, then rinsing with warm water at 40–60°C, adding 1–2 g / L of soap and rinsing at 95°C for 10–15 minutes until neutral. Then dehydrate and dry.

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