Polyester/modified polyester blended elastic knitted fabric is dyed with heterochromatic gray. When disperse dyes and cationic dyes are dyed in the same bath, there are problems such as poor color stability, uneven dyeing and color spots. It is hoped to add anti-sedimentation during production. Agent S, cationic dye leveling agent and other auxiliaries are used to solve the problems that exist when two dyes are bathed in the same bath.
The results show that by adding 0.lg/L disperse dye leveling agent C, 1.5g/L anti-sedimentation agent S, and 0.7g/L cationic dye leveling agent OD, it can Improve the levelness of dyeing; the pH value is controlled at 3.5~4.5, the dyeing temperature for disperse dyes is 80~130℃, the dyeing temperature for cationic dyes is 90~120℃, and the heating rate is controlled at 0.5℃/min. Large-scale production results show that the quality of dyed products can meet customer requirements.
Polyester/modified polyester blended elastic knitted fabric has the characteristics of soft hand feeling, moisture absorption and breathability, and good drape, and is quite popular in the market. After being dyed with disperse dyes and cationic dyes, polyester/modified polyester blended elastic knitted fabrics can achieve a fully dyed heterochromatic gray effect, which is visually novel and has become a new type of knitted product.
The heterochromatic gray effect of polyester/modified polyester blended elastic knitted fabrics is obtained by dyeing polyester with disperse dyes and modified polyester with cationic dyes. Certain problems will arise when two dyes with different properties are bathed in the same bath. Therefore, the two-bath and two-step dyeing method is used in production. However, the process consumes high energy and water, which does not meet the requirements of energy conservation and emission reduction. The production efficiency is low and the color stability is poor. , it is difficult to achieve the customer’s expected results.
In order to improve the dyeing production efficiency of polyester/modified polyester blended fabrics, the author conducted research on the one-bath and two-step dyeing process of polyester/modified polyester blended elastic knitted fabrics. The types and types of dyeing auxiliaries were studied. The dosage is optimized to eliminate the problems that arise when two dyes are dyed in the same bath. Practice has shown that the dyeing effect can be improved by controlling the dyeing heating rate and the pH value of the dye bath. The optimized one-bath two-step dyeing process can solve the problems of poor color stability, uneven dyeing, and color spots caused by two dyes in the same bath. Improved production efficiency.
Conventional dyeing process for polyester/modified polyester blended stretch knitted fabrics
To obtain the effect of heterochromatic gray on polyester/modified polyester blended stretch knitted fabrics , two different dyes need to be used for dyeing, namely disperse dyes to dye polyester fibers and cationic dyes to dye modified polyester fibers.
In order to avoid problems when two dyes are dyed in the same bath, dyeing factories often choose a two-bath and two-step dyeing process. The process curve is as follows:
It can be seen from the above process curve that the two-bath and two-step dyeing process has problems such as high energy consumption, large water consumption and long production time. In order to overcome the shortcomings of the two-bath and two-step dyeing process, experiments were conducted on the one-bath and two-step dyeing process.
One-bath two-step dyeing process
1. Fabrics, dyeing materials and instrument fabrics: polyester/modified polyester blended elastic knitted fabric (43% Modified polyester + 44% polyester + 13% spandex).
Dyeing materials: cationic yellow GLB, cationic red FBL, cationic blue XBL, cationic black FDL, disperse yellow WXF, disperse red DW, disperse navy blue WXF, disperse dye leveling agent C, anti-sedimentation agent S , cationic dye leveling agent OD, 98% glacial acetic acid, sodium acetate, caustic soda, insurance powder, citric acid (all commercially available).
Instruments: AK overflow dyeing machine (Taiwan Yaji Co., Ltd.), Datacolor SF 600X spectrophotometer (American Datacolor Company).
2. Dyeing process
2.1 Dyeing process curve The one-bath and two-step dyeing process curve is as follows:
The one-bath two-step dyeing process reduces the number of drains, thereby reducing the water consumption used for dyeing and shortening the production time.
2.2 Dyeing formula and conditions
Prescription for one-bath and two-step dyeing black/smoky gray:
2.3 Test method
2.3.1 Color stability
Use Datacolor SF 600X spectrophotometer to measure the color difference value △E of the head cylinder and the follower cylinder, and test 3 batches continuously to judge the color stability of the finished product.
2.3.2 Color fastness
Color fastness to rubbing: measured with reference to AATCC Test Method 8-2003 “Test Method for Color Fastness to Rubbing”.
Color fastness to soaping: measured according to AATCC Test Method 61-2004 “Test Method for Color Fastness to Soaping”. Color fastness to perspiration: Measured with reference to AATCC Test Method 15-2009 “Test Method for Color Fastness to Perspiration”. Color fastness to light: Measured according to AATCC Test Method 16E (10h) -2008 “Color Fastness to Light”.
2.4 Selection of dyeing auxiliaries
2.4.1 Disperse dye leveling agent C
One-bath two-step dyeing In the process, the first step is dyeing with disperse dyes. In order to prevent disperse dyes from aggregating and producing color spots under high temperature conditions,�Add a certain amount of disperse dye leveling agent C. The dyeing effects when the dosage of disperse dye leveling agent C is different is shown in Table 1.
Table 1 Effect of the dosage of disperse dye leveling agent C on the dyeing effect
From table 1 It can be seen that the addition of leveling agent C is beneficial to improving the quality of the cloth surface. Considering the cloth surface effect and economic cost, the mass concentration of disperse dye leveling agent C is 0.lg/L.
2.4.2 Anti-sedimentation agent S In the one-bath two-step dyeing process, cationic dyes are added after disperse dye dyeing. Although the dye uptake rate of disperse dyes is high, some residues remain, especially the anionic dispersants in disperse dyes that will remain in the dye bath. Cationic dyes are positively charged when dissolved in water, and their retarder is generally cationic. Therefore, after adding cationic dyes, anionic and cationic interactions will occur, resulting in precipitation and color spots on the cloth surface. To avoid this situation, a nonionic anti-sedimentant S can be added before adding the cationic dye. The effect of anti-sedimentation agent S on the dyeing effect is shown in Table 2.
Table 2 Effect of anti-sedimentation agent S on dyeing effect
As can be seen from Table 2, adding anti- Precipitant S can significantly improve the dyeing quality of cloth. Considering the cloth surface effect and economic cost, the mass concentration of anti-sedimentant S is 1.5g/L.
2.4.3 Cationic dye leveling agent OD Cationic dyes have low dye migration and can easily cause uneven dyeing during the dyeing process. Anionic leveling agent OD can be added for improve.
The leveling agent OD is ionically bonded to the cationic dye, and gradually releases the ionic cationic dye as the temperature changes, achieving the purpose of slow dyeing and reducing the risk of dyeing. Table 3 shows the dyeing results after adding cationic dye leveling agent OD.
Table 3 Effect of cationic dye leveling agent OD on dyeing effect
It can be seen from Table 3 that the leveling agent OD can be improved The cloth effect of the product. Taking comprehensive considerations into account, the OD mass concentration of the cationic dye leveling agent is 0.7g/L.
2.5 pH
2.6 Dyeing heating rate of polyester and modified polyester The dyeing of fibers is carried out under high temperature and high pressure conditions. The dye uptake rate curve of disperse dyes is shown in Figure 1.
Figure 1 Dye uptake rate curve of disperse dyes
It can be seen from Figure 1: When the dyeing temperature is lower than 80°C, disperse The dye uptake rate of polyester fiber is very low, and the dyeing rate is slow; after exceeding 80℃, the dyeing rate increases rapidly with the increase of temperature. Therefore, when the disperse dye is lower than 80℃, the heating rate should be 1℃/min, and the heating rate after exceeding 80℃ should be 0.5℃/min.
The dye uptake rate curve of cationic dyes is shown in Figure 2.
Figure 2 Dye uptake rate curve of cationic dyes
It can be seen from Figure 2: When the dyeing temperature is lower than 90°C, cationic dyes The dyeing rate is slow; above 90°C, the dyeing rate of cationic dyes accelerates as the temperature increases. Therefore, when it is lower than 90°C, the heating rate of the cationic dye is controlled at 1°C/min; when it is higher than 90°C, the heating rate is 0.5°C/min.
2.7 Dyeing results
2.7.1 Color stability
Use Datacolor SF 600X spectrophotometer to test the dyed finished product. Color difference test, the results are shown in Table 4. Table 4 Color difference of dyed finished products
Table 4 shows that the color difference of each batch of products is within the acceptable range.
2.7.2 Color fastness
The color fastness of dyed blended fabrics was tested. The results are shown in Table 5.
Table 5 Color fastness of dyed finished products
Table 5 shows that the optimized step of polyester/modified polyester blended fabrics Two-step dyeing, each color fastness is above level 3.5, which can meet customer requirements.
Afterword
1. Use disperse dyes and cationic dyes to dye polyester/modified polyester blended stretch fabrics to obtain heterochromatic gray texture. Dyeing effect. However, there are certain problems when two dyes are dyed in the same bath. Adding anti-sediment agent S, cationic dye leveling agent and other additives can solve the problems when two dyes are dyed in the same bath.
2. The one-bath and two-step dyeing of polyester/modified polyester blended elastic fabric requires controlling the pH value and heating rate. The optimized process obtained from the experiment is: the pH value is controlled at 3.5~4.5, the dyeing temperature of disperse dyes is 80~130℃, the dyeing temperature of cationic dyes is 90~120℃, and the heating rate is controlled at 0.5℃/min. At this time, the dyeing effect is better. .
3. Large-scale production results show that using the one-bath two-step dyeing process, the color fastness of polyester/modified polyester blended elastic knitted fabrics is above level 3.5, which can meet customer requirements.
The color fastness of modified polyester blended elastic knitted fabrics is above level 3.5, which can meet customer requirements.
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