A method for dyeing a microfiber synthetic leather coating

Abstract

The application discloses a dyeing method for superfine fiber synthetic leather coating, in particular to a padding method for immersing a coating color paste, wherein the coating color paste contains low-turbidity penetrating agent, superfine particle size pigment and adhesive, and the process of the padding dyeing method is as follows: immersing the coating color paste, drying at 90-100 DEG C, baking at 120-160 DEG C, and obtaining the product. The particle size of the pigment in the coating color paste is 200-500 nm, which is beneficial to the penetration of the pigment into the synthetic leather. The low-turbidity penetrating agent is at least one of straight-chain secondary alcohol E.O. condensate Tergitol 15-S-7 and branched-chain secondary alcohol E.O. condensate Tergitol TMN with a turbidity of 36 DEG C. During the drying after the immersing of the coating color paste, the low-turbidity penetrating agent loses water solubility and precipitates from the water system to form cloudy flocculation, which inhibits the pigment particles in the coating from moving to the surface of the superfine fiber synthetic leather with water, so that the inside and outside colors of the coating-dyed synthetic leather are consistent.

Description

Technical Field

[0001] This invention belongs to the field of microfiber synthetic leather and is a method for dyeing microfiber synthetic leather coatings. Background Technology

[0002] Microfiber synthetic leather mimics the appearance and texture of natural leather. It consists of two parts: microfiber (polyamide, polyester microfiber) and polyurethane. The microfibers are irregularly cross-linked in three dimensions, acting as a skeleton and providing support. The polyurethane is distributed around the microfibers to form the overall synthetic leather. The polyurethane in the leather is not a simple filler, but has many circular and needle-shaped foam structures, which are interwoven to form a fine, transparent, three-dimensional network.

[0003] Microfiber synthetic leather has a wide range of applications and requires a rich variety of colors. Polyamide microfiber synthetic leather is mostly dyed with weakly acidic dyes, neutral dyes, and disperse dyes. Weakly acidic and neutral dyes can dye polyamide microfiber, while neutral and disperse dyes can dye polyurethane. Because the materials composing synthetic leather are selective in their use of dyes, a single dye cannot meet the dyeing requirements of microfiber synthetic leather. Chinese companies mostly use neutral dyes as the primary dye, combined with other dyes to form composite dyes for dyeing polyamide microfiber synthetic leather. Dyeing microfiber synthetic leather with dyes presents several problems, such as poor color depth and evenness. Some dyes require fixing agents to achieve a certain color fastness, and disperse dyes suffer from color migration. Furthermore, dye dyeing involves a long dyeing process and the problem of wastewater discharge.

[0004] Li Jinhua et al. conducted a study on the dyeing process of microfiber nylon PU synthetic leather using coatings (Li Jinhua, Li Xiaoxia, Zhang Yue. Study on coating dyeing process of microfiber nylon PU synthetic leather [J]. Leather and Chemical Industry. 2014, (5): 28-30). They concluded that the samples dyed with coatings achieved good levels in both uniformity and color fastness. Dyeing microfiber synthetic leather with coatings is suitable for various dyeing objects, the dyeing process is simple, and there is no wastewater discharge.

[0005] In fact, dyeing microfiber synthetic leather with coatings has problems such as the penetration of pigments in the coating and the migration of pigment particles with moisture to the surface of the synthetic leather during drying, resulting in inconsistent colors inside and outside the synthetic leather. Summary of the Invention

[0006] This invention relates to a method for dyeing microfiber synthetic leather with a coating. Specifically, the method involves padding a coating paste with a low-turbidity-point penetrant, ultrafine-particle-size pigments, and binders. The padding dyeing process is as follows: padding with the coating paste → drying at 90~100℃ → baking at 120~160℃ → finished product.

[0007] The pigment particle size in the paint paste used in this invention is 200~500nm. Under the action of the penetrant, the ultra-fine pigment particles in the paint paste will penetrate evenly into the interior of the microfiber synthetic leather.

[0008] The low-cloud-point penetrant used in this invention is at least one of the following: Tergitol 15-S-7, a linear secondary alcohol EO condensate, and Tergitol TMN, a branched secondary alcohol EO condensate with a cloud point of 36°C. During drying after padding with the paint pigment, the low-cloud-point penetrant loses its water solubility and precipitates from the water system, forming cloud-like flocculent matter. This inhibits the migration of pigment particles in the paint with water to the surface of the microfiber synthetic leather, ensuring uniform color throughout the synthetic leather.

[0009] The adhesive used in this invention is an acrylic or polyurethane adhesive.

[0010] The coating pigment formula of this invention, by mass percentage, is as follows: 0.5%~2% low cloud point penetrant, 0.1%~5% ultrafine pigment pigment, and 3%~10% binder. Attached Figure Description

[0011] Figure 1 shows a comparison of the color uniformity of the cross-section of 1.6mm nylon microfiber polyurethane synthetic leather before and after drying, which has been impregnated with a paint color paste containing 1.2% Tergitol 15-S-7 penetrant.

[0012] Figure 2 shows a comparison of the color uniformity of the cross-section of 1.6mm nylon microfiber polyurethane synthetic leather before and after drying, which has been impregnated with a color paste containing 1.2% fast-penetrating agent T. Detailed Implementation

[0013] Example

[0014] The coating dyeing process for 1.6mm nylon microfiber polyurethane synthetic leather is as follows: microfiber synthetic leather is dipped in coating paste → drying (96℃) → baking (150℃, 1min) → finished product.

[0015] The coating pigment formulation, by mass percentage, is as follows: 2% ultrafine red water-based coating, 1.2% penetrant Tergitol 15-S-7, 7% acrylic binder, and the remainder is water.

[0016] Cut the microfiber synthetic leather in the middle before and after the above-mentioned coating dyeing and drying, and observe the cross-section. It was found that the color was uniform before and after drying, as shown in Figure 1 of the instruction manual.

[0017] According to GB / T3920-2008, the dry and wet rubbing color fastness of the microfiber synthetic leather dyed with the above coatings was tested, and the results were: dry rubbing color fastness grade 4-5, wet rubbing color fastness grade 3-4.

[0018] Comparative Example 1

[0019] The coating dyeing process for 1.6mm nylon microfiber polyurethane synthetic leather is as follows: microfiber synthetic leather is dipped in coating paste → drying (96℃) → baking (150℃, 1min) → finished product.

[0020] The coating pigment formulation, by mass percentage, is as follows: 2% ultrafine red water-based coating, 1.2% rapid penetrant T, 7% acrylic binder, and the remainder is water.

[0021] Cut the microfiber synthetic leather in the middle before and after the above-mentioned coating dyeing and drying, and observe the cross-section. It was found that the color of the cross-section was uniform before drying, but the color of the core of the cross-section became lighter after drying due to pigment migration, as shown in Figure 2 of the instruction manual.

[0022] By comparing with Comparative Example 1, it can be seen that under the action of the low cloud point penetrant, Example 1 not only achieved the penetration of ultrafine pigments into the interior of microfiber leather, but also ensured that the pigments that had penetrated into the leather did not migrate during the drying of the pigment paste.

[0023] This invention provides a method for dyeing microfiber synthetic leather with coatings. The process is simple, produces no dyeing wastewater, and is energy-saving and environmentally friendly.

Claims

1. A method for dyeing microfiber synthetic leather with a coating, characterized in that, A pigment paste is applied using a pad-dyeing method. The pigment paste contains a low-cloud-point penetrant, ultrafine-particle-size pigments, and a binder. The pad-dyeing process is as follows: padding the pigment paste → drying at 90~100℃ → baking at 120~160℃ → finished product; the ultrafine-particle-size pigment has a particle size of 200~500nm; the low-cloud-point penetrant is at least one of the straight-chain secondary alcohol EO condensate Tergitol 15-S-7 and the branched-chain secondary alcohol EO condensate Tergitol TMN with a cloud point of 36℃; the pad-dyeing residue rate of the pigment paste is 70%~90%.

2. The method for dyeing microfiber synthetic leather coating as described in claim 1, characterized in that: The formulation of the paint color paste, by mass percentage, is as follows: 0.5%~2% low cloud point penetrant, 0.1%~5% ultrafine pigment color paste, and 3%~10% binder.

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