Pretreatment process for digital printing of polyester shoe material

Abstract

The invention relates to a pretreatment process for digital printing of a polyester shoe material. The pretreatment process comprises the following steps: (1) carrying out surface modification on a fabric by using sodium hydroxide; (2) mixing and stirring a polyacrylic acid solution, sodium alginate and deionized water at normal temperature, and standing to prepare a pretreatment solution; (3) adjusting the pH value of the pretreatment solution to 3-4 by using an acetic acid solution; (4) immersing the polyester shoe material into the pretreatment liquid at room temperature for sizing, and then putting the polyester shoe material on a padder for extrusion rolling; and (5) after the sizing is finished, drying the polyester shoe material. According to the method, the surface performance of the textile fabric is modified through pretreatment, on the basis, the fabric is endowed with the performance of moisture absorption, seepage prevention, coating bonding and the like for digital printing, and the color performance and fastness of printing are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of printing and dyeing technology, and specifically relates to a pretreatment process for digital printing on polyester shoe materials. Background Technology

[0002] Currently, shoe material printing and dyeing processes still rely on traditional screen printing, which generates significant wastewater, greatly increasing wastewater treatment costs and contradicting current environmental protection principles. Furthermore, the rapid development of fast fashion has led to increasing consumer demand for small-batch, personalized, and diverse products, requiring shoe material printing and dyeing companies to provide timely updates on available designs. In terms of cost, digital printing offers simple operation and on-demand production, reducing labor and inventory costs. The shoe material printing and dyeing industry is facing a transformation and upgrade. Digital printing eliminates the need for steaming and washing, significantly reducing wastewater pollution and energy consumption. It also eliminates traditional processes such as color separation, plate making, and paste preparation, resulting in shorter production cycles that meet current consumer preferences. Therefore, digital printing technology has advantages over traditional screen printing technology in terms of consumer demand, cost, and environmental protection.

[0003] Polyester is widely used in shoe upper materials due to its high strength, abrasion resistance, and low cost. However, due to its poor moisture absorption, digital printing still faces many problems in practical applications. For example, during the printing process, liquid ink droplets have difficulty penetrating and diffusing, resulting in lower color yield, lower depth, and poor color fastness; furthermore, the pigment molecules cannot directly bond with the fiber through chemical bonds. Therefore, effective pretreatment of the fabric to adjust the ink droplet penetration effect and improve the printing effect and color fastness of the pattern is an indispensable step in the digital printing production process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pretreatment process for digital printing on polyester shoe materials, so as to adjust the penetration effect of ink droplets, improve the printing effect and color fastness of the pattern.

[0005] This invention provides a pretreatment process for digital printing on polyester shoe materials, comprising the following steps:

[0006] (1) Use sodium hydroxide to modify the surface of the fabric to improve its surface wettability;

[0007] (2) Mix and stir 9% polyacrylic acid solution, 0.5% sodium alginate and deionized water at room temperature, let stand, and prepare pretreatment solution;

[0008] (3) Adjust the pH of the pretreatment solution to 3-4 using acetic acid solution;

[0009] (4) The polyester shoe material is immersed in the pretreatment solution at room temperature for sizing, and then the polyester shoe material is placed on a rolling mill for extrusion.

[0010] (5) After the sizing is completed, the polyester shoe material is dried.

[0011] Preferably, the sodium hydroxide concentration in step (1) is 8% to 18% by weight.

[0012] Preferably, the pretreatment solution in step (2) contains 3% to 17% polyacrylic acid, 0.2% to 0.9% sodium alginate, and the remainder is deionized water.

[0013] Preferably, the pretreatment liquid in step (2) is a transparent liquid.

[0014] Preferably, the concentration of the acetic acid solution in step (3) is 1 to 5 ml / L.

[0015] Preferably, the sizing time in step (4) is 8 to 20 minutes.

[0016] Preferably, the rolling speed in step (4) is set to 15-30 r / min and the pressure is set to 0.1-0.3 MPa.

[0017] Preferably, the drying temperature in step (5) is 90-110°C.

[0018] In this invention, sodium hydroxide, an alkaline agent, is used for surface modification during pretreatment to improve the hygroscopicity of polyester, accelerate color fixing, and prevent bleeding. Polyacrylic acid, a binder, is added to the pretreatment solution to improve color fastness. Sodium alginate, a thickener, is added to increase the amount and clarity of color.

[0019] Beneficial effects

[0020] (1) The method of the present invention is simple, low in cost, and suitable for industrial production.

[0021] (2) This invention modifies the surface properties of textile fabrics through pretreatment, thereby endowing the fabrics with properties such as moisture absorption, anti-seepage, and adhesive coatings for digital printing, which greatly improves the color performance and fastness of the print. Compared with traditional shoe material printing and dyeing methods, it eliminates the washing process of printing and dyeing enterprises, and allows for direct printing after pretreatment, which helps to shorten the processing flow, reduce production costs, and increase economic benefits. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0023] The color performance and color fastness of the polyester shoe material in the examples were tested:

[0024] Color saturation (K / S value): Under the D65 standard illuminator and d / 8 illumination / observation conditions specified in GB / T 3978, and the measurement conditions of the CIE1964 supplementary standard colorimetric observer and dual-path spectrophotometric method specified in GB / T3979, a Datacolor850 colorimeter conforming to GB / T19437-2004 should be selected to measure the K / S values ​​of C, M, Y, and K respectively. Each color saturation patch should be measured twice along both the longitude and latitude lines, for a total of 4 points. The K / S value of the sample is the arithmetic mean of these 4 points.

[0025] Color characteristic values: According to GB / T 17644-2008, a Datacolor 650 colorimeter was selected, with the light source set to D65, viewing angle to 10°, and aperture selected as medium (20mm). The CIE L*a*b* values ​​of C, M, Y, and K were measured respectively.

[0026] Fastness to dry and wet rubbing: It shall comply with GB / T 3920-2008 "Textiles - Tests for color fastness to rubbing". This test method uses the degree of staining of the rubbing cover as the evaluation standard. The specific test is divided into dry rubbing test and wet rubbing test. In the dry rubbing test, the sample is fixed at both ends of the testing instrument, and the rubbing stroke is set to 10 times. After rubbing, the dry rubbing cover is compared with the standard staining gray card for staining rating. In the wet rubbing test, the rubbing cover is immersed in pure water to make the moisture content of the rubbing cover 95% to 100%, and the dry rubbing test steps are repeated.

[0027] Example 1

[0028] This embodiment provides a pretreatment process for digital printing on polyester shoe materials, including the following steps:

[0029] (1) Surface modification of fabric with 15% sodium hydroxide to improve its surface wettability;

[0030] (2) The polyacrylic acid solution, sodium alginate and deionized water are mixed and stirred at room temperature and allowed to stand to obtain a pretreatment solution. The pretreatment solution contains 9% polyacrylic acid, 0.5% sodium alginate and the remainder is water.

[0031] (3) Adjust the pH of the pretreatment solution to 3-4 using 3 ml / L acetic acid solution;

[0032] (4) Immerse 100% polyester single-sided perforated sandwich mesh in the pretreatment solution at room temperature for sizing for 10 minutes. After sizing, place 100% polyester single-sided perforated sandwich mesh on a rolling mill and squeeze it. The rolling mill speed is set to 20 r / min and the pressure is set to 0.2 MPa.

[0033] (5) After the sizing is completed, the polyester shoe material is dried at a temperature of 100℃.

[0034] Example 2

[0035] This embodiment provides a pretreatment process for digital printing on polyester shoe materials, including the following steps:

[0036] (1) Surface modification of fabric with 15% sodium hydroxide;

[0037] (2) The polyacrylic acid solution, sodium alginate and deionized water are mixed and stirred at room temperature and allowed to stand to obtain a pretreatment solution. The pretreatment solution contains 9% polyacrylic acid, 0.5% sodium alginate and the remainder is water.

[0038] (3) Adjust the pH of the pretreatment solution to 3-4 using 3 ml / L acetic acid solution;

[0039] (4) Immerse 100% polyester perforated mesh in the pretreatment solution at room temperature for sizing for 10 minutes. After sizing, place 100% polyester perforated mesh on a rolling mill and squeeze it. The rolling mill speed is set to 20 r / min and the pressure is set to 0.2 MPa.

[0040] (5) After the sizing is completed, the polyester shoe material is dried at a temperature of 100℃.

[0041] Digital printing was performed on polyester shoe materials that were neither pretreated nor pretreated according to Examples 1 and 2. The process involved pretreating the fabric, drying it, and then placing the fabric flat on the guide belt of a digital printing machine. The machine controlled the print head to move precisely on the fabric according to the pattern data transmitted from the computer, and the print head sprayed ink onto the fabric surface. Subsequently, the color performance and color fastness of each polyester shoe material were tested. The test results are shown in Tables 1-4. After pretreatment, the K / S values ​​of all color blocks were improved, with the black color block showing the most significant improvement. The color fastness test results are shown in Table 5. After pretreatment using the process method of this invention, the dry rubbing fastness of the digitally printed polyester shoe material improved from grade 4 to grade 4-5, and the wet rubbing fastness improved from grade 3-4 to grade 4-5.

[0042] Table 1. Color performance of 100% polyester single-sided perforated sandwich mesh shoe material after digital printing (without pretreatment)

[0043] Example 1 Before treatment <![CDATA[CIE a * ]]> <![CDATA[CIE b * ]]> <![CDATA[CIE c * ]]> <![CDATA[CIE L * ]]> K / S black -1 2 2 37 4.76 magenta 37 18 41 51 3.54 yellow 1 69 69 80 4.26 green -16 -22 27 61 2

[0044] Table 2. Color performance of 100% polyester perforated mesh shoe material after digital printing (without pretreatment)

[0045] Example 2 Before treatment <![CDATA[CIE a * ]]> <![CDATA[CIE b * ]]> <![CDATA[CIE c * ]]> <![CDATA[CIE L * ]]> K / S black -1 2 2 39 4.82 magenta 34 16 38 54 3.79 yellow 1 69 69 79 5.18 green -14 -23 27 60 2

[0046] Table 3. Color performance of polyester shoe material pretreated in Example 1 after digital printing.

[0047] After treatment in Example 1 <![CDATA[CIE a * ]]> <![CDATA[CIE b * ]]> <![CDATA[CIE c * ]]> <![CDATA[CIE L * ]]> K / S black -1 2 2 27 9.75 magenta 40 19 44 45 5.77 yellow -1 70 70 76 6.15 green -15 -23 28 61 2.04

[0048] Table 4. Color performance of polyester shoe material pretreated in Example 2 after digital printing.

[0049] After treatment in Example 2 <![CDATA[CIE a * ]]> <![CDATA[CIE b * ]]> <![CDATA[CIE c * ]]> <![CDATA[CIE L * ]]> K / S black -1 2 2 27 9.89 magenta 40 21 45 46 5.97 yellow -1 70 70 77 6.05 green -15 -23 28 61 2.02

[0050] Table 5. Color fastness of untreated polyester shoe materials and polyester shoe materials pretreated in Examples 1-2 after digital printing.

[0051] sample Dry friction fastness wet friction fastness Wash fastness Example 1 Before treatment 4 3-4 4 Example 2 Before treatment 4 4 4 After treatment in Example 1 4-5 4-5 4 After treatment in Example 2 4-5 4-5 4

Claims

1. A pretreatment process for digital printing on polyester shoe materials, comprising the following steps: (1) Surface modification of fabric with sodium hydroxide; (2) Mix and stir the polyacrylic acid solution, sodium alginate and deionized water at room temperature, let stand, and prepare the pretreatment solution; (3) Adjust the pH of the pretreatment solution to 3-4 using acetic acid solution; (4) The polyester shoe material is immersed in the pretreatment solution at room temperature for sizing, and then the polyester shoe material is placed on a rolling mill for extrusion. (5) After the sizing is completed, the polyester shoe material is dried.

2. The pretreatment process according to claim 1, characterized in that, The sodium hydroxide concentration in step (1) is 8% to 18% by weight.

3. The pretreatment process according to claim 1, characterized in that, The pretreatment solution in step (2) contains 3% to 17% polyacrylic acid, 0.2% to 0.9% sodium alginate, and the remainder is deionized water.

4. The pretreatment process according to claim 1, characterized in that, The concentration of the acetic acid solution in step (3) is 1-5 ml / L.

5. The pretreatment process according to claim 1, characterized in that, The sizing time in step (4) is 8 to 20 minutes.

6. The pretreatment process according to claim 1, characterized in that, In step (4), the rolling speed is set to 15-30 r / min and the pressure is set to 0.1-0.3 MPa.

7. The pretreatment process according to claim 1, characterized in that, The drying temperature in step (5) is 90-110℃.