1、 Post setting and process conditions

Post setting refers to the process of high temperature stretching after finishing bleaching, dyeing and printing. The style of the product (hand feel, flat, anti deformation, anti pilling, etc.) is affected by this process. Shrinkage and ironing fastness are closely related. At present, polyester and its blended fabrics, especially the thin and medium thick fabrics, have undergone the process of high temperature hot air stretching, and the equipment used is the horizontal long heat zone setting machine. Because of the poor uniformity of the heat radiation from the left, middle and right sides of the cloth, the infrared radiation short heat zone setting machine is not suitable for high temperature heat stretching process. Post setting process conditions are as follows

Varieties

process conditions

T / C (65 / 35) t / C (low proportion) t / R (65 / 35) polyester / nitrile

Process project

Box temperature / ℃ 195-200 195-200 190-195 180-185

Time / s 20-30 18 / 25 18-30 20-30

Overfeeding rate /% 1-21-21-21-2

Falling cloth door width / cm > finished product 2.5-3 > finished product 2.5-3 > finished product 2.5-3 > finished product 2.5-3

Note:

1. For fabrics processed with high temperature color sensitive dyes, the temperature can be increased by 5-10 ℃ to ensure the ironing fastness

2. For the fabrics processed with low temperature disperse dyes, in order to ensure the dye sublimation fastness, the temperature should be reduced by 5-10 ℃

3. The post setting process of polyester / nitrile fabric is 10-20 ℃ lower than that of T / C

2、 One step shaping and whitening

There are two processes for bleaching polyester and its blends:

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The one-step process saves the predetermined process, shortens the process flow, saves energy, and is worth popularizing. The following points should be paid attention to when adopting one-step process:

(1) Only by strictly mastering polyester whitening agent and adjusting the hair color, fixation temperature and time of colorant used for coloration, can the fabric get Zui good whiteness. When the dosage of domestic whitening agent DT is 25g / L, the color fixing temperature is 155-160 ℃, and the time is 1.5-2min. However, when the temperature is increased to 190-200 ℃, the color fixing time is greatly shortened, and the required whiteness value can be achieved within 18-30s. When one-step process of setting and whitening is adopted, both whiteness and setting effect should be taken into account when setting temperature and time are determined.

(2) After the polyester whitening agent is dipped and rolled, if the fabric can be pre baked at low temperature in the infrared or hot air drying room first, and the moisture on the fabric can be dried to 30% - 50%, it is easy to control when setting the hair color, the effect is better, and the speed can also be faster. If the drying cylinder is used for drying, the first 3-4 drying cylinders should be sprayed with polytetrafluoroethylene to reduce the starting drying temperature, which can prevent the whitening agent from dyeing the drying cylinder, resulting in defects such as color spots and uneven whiteness.

(3) There should be no serious lamination and wrinkling on the fabric when the polyester whitening agent is being dipped and rolled, otherwise the warp yellow and white streaks will be produced.

3、 Comparison of advantages and disadvantages of different shaping processes

Process program

Advantages and disadvantages

Pre setting (original cloth or setting after desizing)

1. It can eliminate the internal stress caused in the process of spinning and dyeing without serious deformation and wrinkles

2. When the original cloth is set, it is difficult to remove the greasy dirt and chemical slurry on the cloth

3. In the process of printing and dyeing, the polyester blended fabrics with different shrinkage rate yarn have different shrinkage after heat and alkali treatment to form pleated creases. This method is suitable for setting

Intermediate setting (after scouring and bleaching, before printing and dyeing

1. It can eliminate the wrinkles caused by textile and dyeing pretreatment, and make the semi-finished products flat and wrinkle free before dyeing

2. It can avoid the dye with poor sublimation fastness and cause dye sublimation during setting

3. It can reduce the shrinkage of the fabric in the process after printing and dyeing

4. Semi product slightly yellow

5. The high setting temperature will affect the absorption rate of dye in the application of jigging

6. After setting, if the hot melt dyeing process is followed, the pinholes or clip marks left on the cloth edge need to be washed and dried once, or the setting process can be solved one more process in advance

Post setting (after printing and dyeing)

1. When some soluble vat dyes are used to dye light colored cloth, it can improve the color supply and ironing fastness

2. The dimensional stability and flatness of the finished product are good

3. High requirements for flatness of pre dyeing semi-finished products

4. High sublimation fastness is required for the use of dyes, otherwise it is easy to cause defects and mechanical contamination