A method for preparing high-fastness, environmentally friendly water-based island microfiber suede.

Abstract

This invention discloses a method for preparing high-fastness, environmentally friendly water-based island microfiber suede, including spinning, needle-punching nonwoven fabric, washing to remove marine phase, drying and shaping, impregnation, and sanding to form suede. This invention proposes a novel "removing marine phase before impregnation" process, successfully producing high-grade water-based island microfiber suede with high color fastness, soft hand feel, excellent wool effect, and extreme environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of microfiber leather manufacturing technology, specifically a method for preparing high-strength, environmentally friendly, water-based island microfiber suede. Background Technology

[0002] Traditional island-type microfiber suede typically employs a "pre-impregnation followed by removal of marine phase" manufacturing process, which involves first impregnating the nonwoven fabric with resin and then removing the marine phase components from the island fibers. This process has the following main drawbacks: 1. Low fiber-resin bonding strength: After the removal of the marine phase, a large gap is generated between the island phase fibers and the resin, resulting in insufficient bonding strength and making it difficult to meet the requirements for dry and wet rubbing fastness. To compensate for this defect, the industry generally uses dry and wet rubbing treatment agents in the later stage, but these will form a covering film on the suede surface, resulting in loss of suede effect and decreased apparent capillary effect.

[0003] 2. Stiff feel: The use of dry and wet friction treatment agents makes the product feel noticeably stiff, affecting comfort and market acceptance.

[0004] 3. Environmental and health hazards: Traditional processes often use solvent-based resins and chemical treatment agents, which may contain harmful substances and pose a risk to the health of operators. In addition, the VOC emissions during the production process are high, making it difficult to meet increasingly stringent environmental regulations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing high-fastness, environmentally friendly water-based island microfiber suede, proposing a novel "first remove marine phase, then impregnate" process that improves product performance while achieving environmentally friendly production throughout the entire process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-fastness, environmentally friendly water-based island microfiber suede, comprising the following steps: S1. Spinning: Preparation of island-island fibers, wherein the marine phase is water-soluble polyvinyl alcohol and the island phase is polyester or polyamide; S2. Needle-punched nonwoven fabric: Nonwoven fabric is made by needle-punching island fibers. S3. Water washing to remove marine phase: The nonwoven fabric is washed to remove the water-soluble polyvinyl alcohol marine phase, forming a base fabric with island phase fibers. S4. Drying and shaping: Drying and shaping the porous substrate; S5. Impregnation: The base fabric is impregnated with an impregnation material containing waterborne polyurethane resin, nano silica and waterborne pigment resin to obtain impregnated base fabric. S6. Smoothing: The impregnated base fabric is buffed to form suede.

[0007] Furthermore, in S1, when preparing colored fibers, it is achieved by adding color masterbatch for blending, wherein the amount of color masterbatch added is 8-10 wt% of the total weight of the fibers.

[0008] Furthermore, in S2, an R100 needle is used, with a needle density of 1200-1800 needles / cm² and a needle depth of 8-12mm.

[0009] Furthermore, in S3, a three-stage countercurrent water washing system is used for washing: the first stage is treatment in hot water at 80°C containing 0.5wt% surfactant for 15-20 minutes; the second stage is treatment in warm water at 60°C containing 0.2wt% citric acid for 15-20 minutes; the third stage is treatment in clean water at room temperature for 15-20 minutes; after washing, the residual amount of the water-soluble polyvinyl alcohol phase is controlled to be ≤0.5wt%.

[0010] Furthermore, in S4, hot air circulation drying is used, with a temperature gradient of 80℃→120℃→150℃, an air velocity of 2-3m / s, and a drying time of 15-20 minutes.

[0011] Furthermore, in S5, the impregnating material comprises 100 parts of waterborne polyurethane resin; 5-8 parts of nano-silica; 13-18 parts of waterborne color paste; and 0.4-0.6 parts of defoamer.

[0012] Furthermore, the process parameters for the impregnation treatment are: impregnation time 2-4 minutes, liquid yield 120-150%, pre-drying temperature 80-100℃, and baking temperature 130-150℃.

[0013] Furthermore, in the S6, a double-sided sanding process is adopted, wherein: the front sanding uses 180 / 240 grit sandpaper, the pressure is 3kg / cm², and the sanding is performed 3 times; the back sanding uses 180 / 240 grit sandpaper, the pressure is 2kg / cm², and the sanding is performed 3 times; the sanding speed is 8-10m / min.

[0014] Furthermore, following S6, S7 includes dyeing: dyeing the suede with reactive dyes at a temperature of 60-80°C for 30-45 minutes, and using a color-fixing agent.

[0015] Further, post-treatment is performed after staining, including: first, acidic reduction washing under the conditions of pH=4.5, temperature 50-60℃, and time 20-30 minutes; then, alkaline reduction washing under the conditions of pH=9.5, temperature 70-80℃, and time 20-30 minutes.

[0016] This invention provides a method for preparing high-fastness, environmentally friendly water-based island microfiber suede. Through a revolutionary process route of "first removing the marine phase and then impregnating," it offers the following advantages compared to existing technologies: 1. Extremely high physical and chemical fastness: Without the use of any additional dry or wet rubbing agents, the product can achieve an excellent level of color fastness of grade 4 or above in multiple aspects such as dry / wet rubbing resistance, water washing resistance, and light exposure resistance.

[0017] 2. Superior sensory quality: Completely avoids the surface coating caused by traditional treatment agents, the product has a soft and full feel, and the apparent nap effect (the fineness and texture of the nap) is significantly improved, meeting the market demand for high-end suede.

[0018] 3. Excellent environmental protection and health safety: The entire production process uses water as a medium, which basically eliminates VOCs emissions. The products have been tested and do not contain harmful substances such as APEO and formaldehyde, and meet international ecological textile standards, making them friendly to production personnel and consumers. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of suede leather that has been first treated with marine phase and then impregnated with resin, showing a tight bond between the resin and the fibers.

[0020] Figure 2 This is a surface diagram of suede after the marine phase has been removed and the suede has been impregnated with resin, showing a tight bond between the resin and the fibers.

[0021] Figure 3 This is a cross-sectional view of suede that has been impregnated with resin and then the sea phase removed, showing a loose bond between the resin and fibers.

[0022] Figure 4 This is a surface view of suede where the resin was first impregnated and then the sea phase was removed, resulting in a loose bond between the resin and the fibers. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1-4 As shown, this invention provides a method for preparing high-strength, environmentally friendly water-based island microfiber suede, comprising the following steps: S1. Spinning: Preparation of island-sea fibers, wherein the marine phase is water-soluble polyvinyl alcohol (PVA) and the island phase is polyester (PET) or polyamide (PA). S2. Needle-punched nonwoven fabric: Nonwoven fabric is made by needle-punching island fibers. S3. Water washing to remove marine phase: The nonwoven fabric is washed to remove the water-soluble polyvinyl alcohol marine phase, forming a base fabric with island phase fibers. S4. Drying and shaping: Drying and shaping the porous substrate; S5. Impregnation: The base fabric is impregnated with an impregnation material containing waterborne polyurethane resin, nano silica and waterborne pigment resin to obtain impregnated base fabric. S6. Smoothing: The impregnated base fabric is buffed to form suede.

[0025] The present invention provides a method for preparing high-fastness, environmentally friendly water-based island microfiber suede, which establishes a core process route of "removing the marine phase first and then impregnating". After removing the marine phase, a porous and clean fiber substrate is formed, which allows the subsequent water-based resin to fully penetrate and tightly wrap and anchor the single island phase fiber. This fundamentally solves the problem of loose bonding between resin and fiber in traditional processes, laying the foundation for obtaining high color fastness, superior hand feel and environmental performance.

[0026] In S1, when preparing colored fibers, color masterbatch is added for blending, with the amount of masterbatch added being 8-10 wt% of the total fiber weight. By adding masterbatch during the fiber spinning stage, the fiber body is colored, resulting in uniform and durable color. This avoids color difference and uneven coloring issues that may occur during subsequent dyeing processes and helps improve the overall color fastness of the final product, especially its wash fastness and rubbing fastness.

[0027] In S2, R100 needles are used with a needle density of 1200-1800 needles / cm² and a needle depth of 8-12mm. This ensures that the nonwoven fabric has a uniform fiber interweaving structure and sufficient physical strength, providing a stable and uniform carrier for subsequent water washing and resin impregnation, and preventing deformation or damage during processing.

[0028] In S3, a three-stage counter-current water washing system is used for washing: First stage: Treat in hot water at 80℃ containing 0.5wt% surfactant for 15-20 minutes; Second stage: Treat in warm water containing 0.2wt% citric acid at 60℃ for 15-20 minutes; Third stage: Treat in room temperature water for 15-20 minutes; After washing, the residual amount of the water-soluble polyvinyl alcohol marine phase is controlled to be ≤0.5 wt%. By designing a water washing system with gradient temperature and functionalized washing, the water-soluble polyvinyl alcohol marine phase (residual amount ≤0.5 wt%) can be removed efficiently and thoroughly. At the same time, through the synergistic effect of surfactants and citric acid, no chemical or physical damage is caused to the island phase fibers during the washing process, ensuring the cleanliness and reactivity of the fiber surface.

[0029] In S4, hot air circulation drying is used, with a temperature gradient of 80℃→120℃→150℃, an air velocity of 2-3 m / s, and a drying time of 15-20 minutes. By designing the temperature and air velocity gradients, the porous base fabric can be gradually dehydrated and shaped under gentle and controlled conditions, effectively controlling the basis weight and dimensional stability (deviation within ±10%), and avoiding the impact of rapid shrinkage or deformation on the subsequent impregnation uniformity.

[0030] In S5, the impregnating material comprises: 100 parts of waterborne polyurethane resin; 5-8 parts of nano-silica; 13-18 parts of waterborne color paste; and 0.4-0.6 parts of defoamer. Nano-silica, as a reinforcing filler, significantly improves the interfacial bonding force and mechanical interlocking effect between the resin and fiber. It is a key material innovation for improving various color fastness properties such as wet and dry rubbing fastness, replacing traditional treatment agents.

[0031] The impregnation process parameters are: impregnation time 2-4 minutes, liquid roll-off rate 120-150%, pre-drying temperature 80-100℃, and baking temperature 130-150℃, to ensure that the impregnating material penetrates the pores and surface of the base fabric in a suitable amount and evenly, and to allow the resin to be completely cured under appropriate baking conditions, forming a strong and continuous bonding layer with the fiber.

[0032] The S6 employs a double-sided sanding process. The front side is sanded with 180 / 240 grit sandpaper at a pressure of 3 kg / cm², for three passes. The back side is sanded with 180 / 240 grit sandpaper at a pressure of 2 kg / cm², also for three passes. The sanding speed is 8-10 m / min. This double-sided sanding process can controllably create a uniform, delicate, and full double-sided suede texture, improving the product's softness and apparent nap (suede quality). Furthermore, the process is stable and highly reproducible.

[0033] Following S6, S7 dyeing is also included: dyeing the suede with reactive dyes at a temperature of 60-80℃ for 30-45 minutes, followed by the use of a color-fixing agent. This dyeing process provides a pathway for producing a wider variety of colors. By selecting reactive dyes and color-fixing agents, products can further meet the colorfastness requirements for darker or special colors, building upon their already high colorfastness.

[0034] Post-dyeing treatment includes: first, acidic reduction cleaning at pH 4.5, temperature 50-60℃, and time 20-30 minutes; followed by alkaline reduction cleaning at pH 9.5, temperature 70-80℃, and time 20-30 minutes. This specific two-step reduction cleaning method (acidic and alkaline) thoroughly removes unfixed dyes and hydrolysis products, maximizing the colorfastness to rubbing and washing after dyeing, ensuring the final product has vibrant and durable colors.

[0035] As attached Figure 1 and attached Figure 2 As shown, using the "first remove marine phase, then impregnate" process of this invention, the resin can fully penetrate and tightly wrap the fibers, resulting in a tight cross-section and a uniform surface feel. In contrast, the traditional process corresponding to Comparative Example 1 (as shown in the attached figure) Figure 3 and attached Figure 4 As shown in the figure, the resin and fiber are loosely bonded, there are gaps in the cross section, and the surface texture is relatively poor.

[0036] The following examples and comparative examples illustrate the beneficial technical effects of the high-fastness, environmentally friendly water-based island microfiber suede preparation method of the present invention. Example 1

[0037] This example provides a method for preparing a high-strength, environmentally friendly, water-based island microfiber suede, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0038] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0039] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 60℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is controlled to be about 0.3wt%, forming a base fabric with island phase fibers.

[0040] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0041] S5: Impregnation; The base fabric is impregnated with an impregnation material for 3 minutes, with a liquid roll-off rate of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes) to ensure complete cross-linking and curing of the resin, thereby obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 8 parts of nano silica (20nm particle size), 15 parts of waterborne color paste (42% solid content), and 0.5 parts of defoamer.

[0042] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain colored microfiber suede with a uniform and delicate velvet texture on both sides. Example 2

[0043] This example provides a method for preparing a high-strength, environmentally friendly, water-based island microfiber suede, including the following steps: S1: Spinning; preparing island-island fibers, comprising 50% marine phase (water-soluble polyvinyl alcohol PVA) and 50% island phase (polyester PET), and obtaining white island-island fibers by melt spinning.

[0044] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0045] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 60℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is controlled to be about 0.3wt%, forming a base fabric with island phase fibers.

[0046] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0047] S5: Impregnation; The base fabric is impregnated with an impregnation material for 3 minutes, with a liquid-to-liquid ratio of 130%, a pre-drying temperature of 90°C (3 minutes), and a baking temperature of 140°C (5 minutes) to allow the resin to fully cross-link and cure, thereby obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 8 parts of nano silica (20nm particle size), 15 parts of waterborne color paste (42% solid content) of the same color as in Example 1, and 0.5 parts of defoamer.

[0048] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain a white suede semi-finished product with a uniform and delicate velvet texture on both sides.

[0049] S7: Dyeing: Immerse the white suede in the dye bath. The dye bath formula is: 2% (owf) reactive brilliant blue KN-R dye, 50g / L sodium sulfate, and 15g / L soda ash. Increase the temperature to 70℃ at 2℃ / min and maintain the temperature for 40 minutes. After dyeing, rinse thoroughly with water to remove excess dye. Post-dyeing treatment: First, perform acidic reduction cleaning under the following conditions: pH=4.5 (adjusted with acetic acid), temperature 55℃, time 25 minutes; then perform alkaline reduction cleaning under the following conditions: pH=9.5 (adjusted with soda ash), temperature 75℃, time 25 minutes. After treatment, rinse thoroughly with warm water, dry and set, to obtain blue microfiber suede with a uniform and delicate velvet texture on both sides.

[0050] Comparative Example 1 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0051] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0052] S3: Impregnation; The nonwoven fabric is impregnated with impregnation material for 3 minutes, with a liquid-to-liquid ratio of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes) to fully cross-link and cure the resin, thus obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 8 parts of nano silica (20nm particle size), 15 parts of waterborne color paste (42% solid content), and 0.5 parts of defoamer.

[0053] S4: Washing removes the PVA marine phase; the impregnated base fabric is then sent to a three-stage countercurrent washing tank: first stage: treated for 18 minutes in hot water at 80°C containing 0.5wt% surfactant (alkyl glycoside APG); second stage: treated for 18 minutes in warm water at 60°C containing 0.2wt% citric acid; third stage: treated for 18 minutes in clean water at room temperature (25°C); forming a base fabric with island phase fibers.

[0054] S5: Drying and shaping; The base fabric is dried and shaped using hot air circulation drying; The drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), and the air velocity is 3m / s.

[0055] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather was sanded three times at a speed of 9 m / min to obtain colored microfiber suede.

[0056] Comparative Example 2 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparing island-island fibers, comprising 50% marine phase (water-soluble polyvinyl alcohol PVA) and 50% island phase (polyester PET), and obtaining white island-island fibers by melt spinning.

[0057] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0058] S3: Impregnation; The nonwoven fabric is impregnated with impregnation material for 3 minutes, with a liquid-to-liquid ratio of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes). The DMF solvent is removed by water extraction in a closed device to obtain the impregnated base fabric. The impregnation material includes: 100 parts of solvent-based polyurethane resin (dissolved in DMF) and 5 parts of solvent-based carbon black paste.

[0059] S4: Washing removes the PVA marine phase; the impregnated base fabric is then sent to a three-stage countercurrent washing tank: first stage: treated for 18 minutes in hot water at 80°C containing 0.5wt% surfactant (alkyl glycoside APG); second stage: treated for 18 minutes in warm water at 60°C containing 0.2wt% citric acid; third stage: treated for 18 minutes in clean water at room temperature (25°C); forming a base fabric with island phase fibers.

[0060] S5: Applying a wet and dry rubbing treatment agent: The base fabric is impregnated in a commercially available acrylic wet and dry rubbing fastness enhancer (solvent type), rolled in and dried to form a treatment film on the surface.

[0061] S6: Skin smoothing; Skin smoothing is performed, but the presence of surface treatment agents has a certain impact on the formation of the suede effect.

[0062] Comparative Example 3 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0063] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0064] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 60℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is controlled to be about 0.3wt%, forming a base fabric with island phase fibers.

[0065] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0066] S5: Impregnation; The nonwoven fabric is impregnated with impregnation material for 3 minutes, with a liquid-to-liquid ratio of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes). The DMF solvent is removed by water extraction in a closed device to obtain the impregnated base fabric. The impregnation material includes: 100 parts of solvent-based polyurethane resin (dissolved in DMF), 5 parts of solvent-based color paste, and 0.5 parts of defoamer.

[0067] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain colored microfiber suede with a uniform and delicate velvet texture on both sides.

[0068] Comparative Example 4 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0069] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0070] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 60℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is controlled to be about 0.3wt%, forming a base fabric with island phase fibers.

[0071] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0072] S5: Impregnation; The base fabric is impregnated with an impregnation material for 3 minutes, with a liquid roll-off rate of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes) to ensure complete cross-linking and curing of the resin, thereby obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 15 parts of waterborne color paste (42% solid content), and 0.5 parts of defoamer.

[0073] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain colored microfiber suede with a uniform and delicate velvet texture on both sides.

[0074] Comparative Example 5 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0075] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2 The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0076] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 60℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is controlled to be about 0.3wt%, forming a base fabric with island phase fibers.

[0077] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0078] S5: Impregnation; The base fabric is impregnated with an impregnation material for 3 minutes, with a liquid roll-off rate of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes) to ensure complete cross-linking and curing of the resin, thereby obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 3 parts of nano silica (20nm particle size), 15 parts of waterborne color paste (42% solid content), and 0.5 parts of defoamer.

[0079] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain colored microfiber suede with a uniform and delicate velvet texture on both sides.

[0080] Comparative Example 6 This example provides a method for preparing suede leather, including the following steps: S1: Spinning; preparation of island-island fibers, including 50% marine phase (water-soluble polyvinyl alcohol PVA), 50% island phase (polyester PET), 9 wt% blue masterbatch is added to PET chips, and colored island-island fibers are obtained by melt spinning.

[0081] S2: Needle-punched nonwoven fabric; the above fibers are carded and laid into a web, and R100 needles are used to punch the fabric at a density of 1500 needles / cm. 2The needle penetration depth is 10mm, and the resulting product has a weight of approximately 450g / m³. 2 Non-woven fabric.

[0082] S3: Washing removes PVA marine phase; the nonwoven fabric is sent into a three-stage countercurrent washing tank: first stage: treated in hot water at 80℃ containing 0.5wt% surfactant (alkyl glycoside APG) for 18 minutes; second stage: treated in warm water at 40℃ containing 0.2wt% citric acid for 18 minutes; third stage: treated in clean water at room temperature (25℃) for 18 minutes; after washing, samples are taken for testing, and the residual amount of PVA marine phase is about 1.2wt%, forming a base fabric with island phase fibers.

[0083] S4: Drying and shaping; hot air circulation drying is used to dry and shape the substrate; the drying gradient temperature is 80℃ (5 minutes) → 120℃ (5 minutes) → 150℃ (8 minutes), the air velocity is 3m / s, and the weight of the base fabric is stable after drying, with a dimensional shrinkage rate of <5%.

[0084] S5: Impregnation; The base fabric is impregnated with an impregnation material for 3 minutes, with a liquid roll-off rate of 130%, a pre-drying temperature of 90℃ (3 minutes), and a baking temperature of 140℃ (5 minutes) to ensure complete cross-linking and curing of the resin, thereby obtaining the impregnated base fabric; The impregnation material includes: 100 parts of waterborne polyurethane resin (40% solid content), 8 parts of nano silica (20nm particle size), 15 parts of waterborne color paste (42% solid content), and 0.5 parts of defoamer.

[0085] S6: Abrasion; Abrasion treatment is applied to the impregnated base fabric. Abrasion of the front surface is performed using 240-grit sandpaper with a pressure of 3 kg / cm². 2 Sand the surface three times at a speed of 9 m / min; for the back side, use 240-grit sandpaper with a pressure of 2 kg / cm². 2 The leather is sanded three times at a speed of 9 m / min to obtain colored microfiber suede with a uniform and delicate velvet texture on both sides.

[0086] Table 1 Performance parameters of suede leather obtained in the examples and comparative examples

[0087] Note: The hand feel score and apparent lint score are the average of multiple blind reviews, with 5 points being the best; the color fastness test is conducted in accordance with national standards such as GB / T 3920 and GB / T 3921.

[0088] in conclusion: 1. Examples 1-2 employ a "sea phase removal followed by impregnation" process. Without using any dry or wet rubbing agents, both dry / wet rubbing fastness and wash fastness reach grade 4 or higher, with extremely high hand feel and apparent velour scores (4.5). In contrast, Comparative Example 1, using the traditional "impregnation followed by sea phase removal" process (even with environmentally friendly water-based resin), shows a significant decrease in all fastness properties. Furthermore, the resin clogs the pores, resulting in a stiff hand feel and poor velour. Comparative Example 2 uses solvent-based resin and treatment agents to achieve a certain level of fastness. While this improves the fastness somewhat, the hand feel is extremely stiff, and VOC emissions are severely excessive, completely sacrificing the comfort and environmental friendliness of suede. This fully demonstrates that the innovative "sea phase removal followed by impregnation" process is the fundamental reason and key to simultaneously achieving high fastness and superior hand feel / velour.

[0089] 2. In Comparative Example 4, without the use of nano-silica, the other processes were exactly the same as in Example 1. The results showed significant shortcomings in wet rubbing fastness (grade 2-3) and wash fastness (grade 3). Furthermore, Comparative Example 5, by reducing the amount of nano-SiO2, also experienced a decrease in performance. This demonstrates the crucial role of nano-silica in the system of this invention in enhancing the interfacial bonding between the resin and fiber, thereby ensuring high color fastness. It represents a core material innovation that allows it to replace traditional treatment agents.

[0090] 3. Examples 1-2 and Comparative Examples 1, 5, and 6 all used a fully aqueous formulation, and their VOC emissions were far below the stringent standard of 50 mg / m³. In contrast, Comparative Examples 2 and 3, which used solvent-based resins, had VOC emissions exceeding 500 mg / m³, indicating poor environmental performance. Combined with the poor feel of Comparative Example 2, this demonstrates that simply using a "sea-phase removal first" process without eliminating the solvent system cannot resolve the conflict between environmental protection and feel. Only by combining a "sea-phase removal followed by impregnation" process with a "specifically formulated impregnating material" can high fastness, superior feel, and ultimate environmental friendliness be achieved simultaneously.

[0091] 4. In Comparative Example 6, insufficient washing temperature led to an increase in PVA residue (1.2%). Although the effect on fastness was not significant in this system, the apparent capillary effect decreased (4.0%). This indicates that thoroughly removing the marine phase is fundamental to ensuring fiber surface cleanliness and the final nap effect, and also demonstrates the necessity of using a three-stage countercurrent washing process.

[0092] 5. Through systematic comparison of the examples and comparative examples, it is strongly demonstrated that the technical solutions claimed in this invention ("removing marine phase before impregnation", three-stage countercurrent water washing process, and water-based impregnation material with specific formulation) can work synergistically to successfully produce high-grade water-based island microfiber suede with high color fastness, soft hand feel, excellent wool effect and extreme environmental protection.

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

Claims

1. A method for preparing high-fastness, environmentally friendly water-based island microfiber suede, characterized in that: Includes the following steps: S1. Spinning: Preparation of island-island fibers, wherein the marine phase is water-soluble polyvinyl alcohol and the island phase is polyester or polyamide; S2. Needle-punched nonwoven fabric: Nonwoven fabric is made by needle-punching island fibers. S3. Water washing to remove marine phase: The nonwoven fabric is washed to remove the water-soluble polyvinyl alcohol marine phase, forming a base fabric with island phase fibers. S4. Drying and shaping: Drying and shaping the porous substrate; S5. Impregnation: The base fabric is impregnated with an impregnation material containing waterborne polyurethane resin, nano silica and waterborne pigment resin to obtain impregnated base fabric. S6. Smoothing: The impregnated base fabric is buffed to form suede.

2. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In S1, when preparing colored fibers, it is achieved by adding color masterbatch for blending, and the amount of color masterbatch added is 8-10 wt% of the total weight of the fibers.

3. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In S2, R100 needles are used, with a needle density of 1200-1800 needles / cm² and a needle depth of 8-12mm.

4. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In S3, a three-stage counter-current water washing system is used for washing: First stage: Treat in hot water at 80℃ containing 0.5wt% surfactant for 15-20 minutes; Second stage: Treat in warm water containing 0.2wt% citric acid at 60℃ for 15-20 minutes; Third stage: Treat in room temperature water for 15-20 minutes; After washing with water, the residual amount of the water-soluble polyvinyl alcohol marine phase is controlled to be ≤0.5wt%.

5. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In S4, hot air circulation drying is used, with a temperature gradient of 80℃→120℃→150℃, an air velocity of 2-3m / s, and a drying time of 15-20 minutes.

6. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In S5, the impregnating material includes: Waterborne polyurethane resin: 100 parts; Nano-silica: 5-8 parts; Water-based pigment: 13-18 parts; Defoamer: 0.4-0.6 parts.

7. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 6, characterized in that: The process parameters for impregnation treatment are: impregnation time 2-4 minutes, liquid yield 120-150%, pre-drying temperature 80-100℃, and baking temperature 130-150℃.

8. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: In the S6, a double-sided skin smoothing process is used, including: The front surface is sanded using 180 / 240 grit sandpaper at a pressure of 3 kg / cm², and the sanding is performed 3 times. The back surface is sanded with 180 / 240 grit sandpaper at a pressure of 2 kg / cm², and the sanding is done in 3 passes. The skin resurfacing speed is 8-10 m / min.

9. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 1, characterized in that: Following S6, S7 dyeing is also included: dyeing the suede with reactive dyes at a temperature of 60-80℃ for 30-45 minutes, and using a color-fixing agent.

10. The method for preparing high-fastness, environmentally friendly water-based island microfiber suede according to claim 9, characterized in that: Post-staining processing includes: First, perform acidic reduction cleaning under the following conditions: pH=4.5, temperature 50-60℃, time 20-30 minutes; Then perform alkaline reduction cleaning under the following conditions: pH=9.5, temperature 70-80℃, time 20-30 minutes.

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