General finishing technology of cotton type fabrics

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First, fixed amplitude

The width of the fabric is pulled to the standard size, which corrects the shortcomings such as uneven width, slackness, and aurora in the printing and dyeing process. The tentering project is based on the fact that the fabric contains suitable moisture, gradually stretches with a mechanical clamp towards the cloth edge, and slowly dries, so as to obtain a temporary setting. The width of the fabric before and after the stretching is limited, otherwise it will cause Severe shrinkage.

1, hot air curtain tenter

The main structure: It is composed of cloth racks, rolling carts, weft-inserting devices, drying cylinders, hot-air bake and drop cloth racks.

Roller: Two-roller or three-roller, for rolling or padding finishing agent; and some also attached with high-pressure water spray or spray humidifying device.

Hot air drying room: including stretching mechanism and heating air supply device

Extension mechanism: fabric chain, amplitude modulation screw

Heating device: cold air is sent to the heater through the blower → main air duct, branch duct → hot air nozzle → jet cloth

Weft-cutting device: differential gear (up to the end of the extension mechanism) or guide roller (after the locomotive)

Process: Feeding → Dehumidification (padding) → Whole width → Drying → Stretching

Advantages: Wide range of applications, high efficiency, fast speed, and good working conditions

2, needle clip stenter

The basic structure is the same as 1 except that the needle plate is used instead of the fabric, and it has the feature of overfeeding, which is beneficial to stretching and reducing the warp shrinkage rate. It can be used for the heat setting of synthetic fiber fabrics and the curing process of resin finishing.

3, dual-use needle plate cloth tenter

The upper part is equipped with a short-loop hanging type pre-drying room, and the fabric is before tentering; the warp and weft are pre-baked under no tension. Suitable for loose-type finishing of long-length fabrics, knitted fabrics, and resin finishing requiring loose processing. It can also be used for loose-type pre-baking, heat-setting and hot-melt dyeing of synthetic fiber blended fabrics. It has strong adaptability and flexibility.

Second, calendering, electro-optic and embossing

1, calendering:

(1) Principle: The cotton fibre has a certain degree of plasticity under hot and humid conditions. After a certain temperature and moisture, under the mechanical pressure, the yarn is flattened, the fluff is pressed, the fabric becomes smooth and smooth, Gloss increases.

(2) Calender:

The fabric (2-7 pieces) composed of overlapping soft and soft rollers surrounds several rollers and achieves gloss due to the effect of wet heat. The effect of calendering is related to the moisture content, the pressure between the rolls, the roll temperature, and the number of passes.

1) Lamination calender:

Several layers of fabrics pass through the same nip at the same time, and the fabrics are pressed against each other to produce a ripple effect. A soft hand can be obtained and a clear texture can be obtained, which is suitable for poplin.

2) Frictional calendering: soft and hard three rollers, soft and hard roller speed is not, hard roller (friction roller) rotates at a high speed, so that the fabric is subject to friction when passing, and obtain a strong gloss (imitation wax paper gloss).

2, electric light

(1) Principle: similar to calendering

Through the hard rollers engraved with parallel slashes, the surface of the fabric is pressed with many parallel slashes, and the ratio of light diffusion and directional reflection is adjusted, resulting in a bright and silky touch.

(2) Electro-optic machine: a hard and soft two rollers, hard roller steel, hollow, can be heated, the surface is engraved with oblique lines, the soft roller is a heat-resistant paper roller.

(3) When processing, the pressure, temperature, moisture content of the fabric, and the angle of the slash of the roller surface must be properly selected to avoid the drop of strength and the unevenness of shade.

3, embossing

The embossing machine is composed of a steel heatable hard roller and a soft roller. The surfaces of the two are respectively engraved with positive lines and negative lines, and they are in agreement with each other. The fabrics are pressed and embossed to produce embossed patterns. The above arrangement is temporary. If it is combined with resin finishing, it can obtain washing effect.

4. Grinding: After finishing, the fabric can produce suede, feel improved, comfortable to wear, can be done on the brushing machine, the fabric produces suede by repeated friction.

Third, soft finishing

1. Purpose: To improve fabric feel and make it soft and smooth

2, softener finishing: rolling softener → drying → tenter → dry

(1) Softener

a. Glycerol; Lack: prone to mold (excessive)

b, paraffin emulsion; lack: excessive, feel tired, powerful

c. red oil; feel, good gloss, not washable

d. Reactive softeners: The water repellent PF and silicone are both made of long sulfur fatty chains and groups that can react with cellulose. They are washable.

3, mechanical softening

In the calender, mechanical pre-shrinking machine to obtain a soft finishing effect. However, the pressure and temperature should be lower and the speed should be faster.

Fourth, rigid finishing

1. Purpose: To obtain a smooth, firm, thick and plump handle, and to increase strength and abrasion resistance, as well as to improve the susceptibility and appearance.

2. Finishing agent:

(1) Slurry: Enhances stiffness, and adhesive filler, itself has a filling effect

(2) Filler: increase weight, thick, smooth feel

(3) Preservatives: easy to store

(4) Colorant: Adjust and improve the color of fabric after sizing

Stiff finishing is usually performed in conjunction with a fixed-width process. Softeners are added to the slurry to improve the overall feel. Similarly, for a soft finish, stiffening agents are added to enhance the body bone.

Fifth, whitening

1. Significance: In order to obtain a higher grade of whiteness, whitening must be performed on the basis of bleaching. There are two concepts of whitening

(1) Blue whitening: absorbs yellow light and removes the brownish color on the fabric.

(2) Fluorescent whitening: The invisible ultraviolet rays are converted into blue or violet visible light rays, which increase the reflectivity of the fabric. The whitened fabric is very white, crystal clear and translucent. It can be printed and dyed by human micro-signals: yinran_ren can exceed the normal whiteness standard of magnesium oxide.

2. Whitening mechanism

1) The color is caused by the reflection of part of the light waves by the object, acting on the senses of the human being. Without light wave sources, there is no color. If a certain object absorbs some part of the visible light wave and reflects other light waves in the daylight, the color appears. If all the seven kinds of light waves are reflected, they appear white, and vice versa.

2) The fluorescent whitening agent not only reflects the seven visible light waves of sunlight into white, but also reflects the ultraviolet rays into blue fluorescence, which is complementary to the yellow light reflected by the fabric, increases the reflection of visible light, and produces crystal clear and translucent white.

In the absence of ultraviolet light, the whitening effect is lower than that of sunlight. Fluorescent brighteners behave like disperse dyes or direct dyes, but differ from the usual dyes in their properties:

1 When the fluorescent whitening agent is used at a low dosage, the depth of coloration is proportional to the amount of dge added; however, when the amount is increased to a certain value, it not only loses the whitening effect, but also becomes dark yellow.

2 The darker the general color of the dye, the more the defect can be covered; however, the better the fluorescent whitening effect, the more obvious the defect.

3 The fluorescent whitening agent itself and the aqueous solution have no obvious whitening effect under sunlight, and only the dyeing with fibre has a strong whitening effect.

3) Blue uses a blue-violet dye (or paint) that can absorb yellow light to color the fabric, so that the wavelength of the light reflected by the fabric is limited to the blue-violet wavelength range, and the yellow-brown color light can be removed. The human micro signal can be printed: yinran_ren can also adjust the fluorescence Brightener shades.

4) Comparison of two whitening effects

Comparison of the reflection curves of daylight bleached fabrics, blue bleached fabrics, fluorescent whitened fabrics and standard white magnesia:

The reflection curve of the bleached fabric is higher in the yellow and red areas than in the violet and blue areas because the bleached fabric is always a yellow-brown shade. The reflectivity of the yellow fabric on the blue fabric was reduced, but the total reflectance was small. After the blue fabric was removed yellow, it was a dark white feeling. Dyeing human micro-signal: yinran_ren fluorescent brightening fabric, the reflectance in the blue-violet area is greatly increased, so the white is significant, but also not pure white, with blue-violet or green light.

3. Polyester whitening

Commonly used varieties of fluorescent brightener DT, the product is a neutral non-ionic light yellow slurry, the active ingredient is more than 1%, can be mixed with water in any ratio, and resistant to 25g/L NaOH solution. DT has good dyeing fastness on polyester. Polyester whitening is often combined with heat setting. Contamination of the fluorescent whitening agent DT with cotton fibers impedes the whitening of the fibers and must be followed by a fluorescent whitening of the cotton fibers. When removed, it can be removed by H2O2 bleaching without additional water washing.

4. Cotton fiber whitening

The whitening agent VBL is used as a pale yellow powder with a bluish-purple color similar to the direct dye. It is soluble in hot water and the aqueous solution is anionic. Therefore, it cannot be mixed with cationic materials. Otherwise, precipitation occurs. Fe compounds have catalytic decomposition. pH 8-9 when used. The amount of fluorescent whitening agent VBL should not exceed 0.5% of the weight of the fabric, otherwise there will be "over-staining" - a yellowish color. In recent years, cotton-type fluorescent brighteners have been commonly used in polyester and cotton.


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