Yarn dyeing is no stranger to most people, how familiar are you with cotton cone yarn dyeing?

Cotton cone yarn dyeing,  process mainly consists of the following five steps:

package yarn dyeing machine

PRETREATMENT

This step primarily removes natural impurities (cottonseed hulls, waxy substances, etc.) and pigmentum from the yarn, enhancing its whiteness and capillary effect to create conditions for dyeing processing.

 

DYEING

Each type of fiber has its unique dyeing characteristics, and yarn dyeing process is formulated based on  properties of cotton fibers (cellulose fibers) and reactive dyes. The process of package yarn dyeing involves applying pressure to dye solution in cone yarn dyeing machine using a pump, allowing the dye solution to penetrate from inner layer to outer layer of package yarn, thereby achieving uniform dyeing.

 

SOAPING

After dyeing, a large amount of hydrolyzed and unreacted dye remains on the surface of the yarn, which must be removed by adding soaping agent and washing under high temperature conditions (known as soaping). The role of soaping is to remove the floating dye on the yarn, improve the color brightness, and meet the fastness requirements of customers.

 

COLOR FIXATION

After soaping, for dark and medium color, fixing agent is added to achieve the processing requirements of subsequent finishing. The function of fixing agent is to form a protective film on the surface of the yarn to prevent dye from falling off during subsequent finishing processes.

 

SOFTENING

During the dyeing process, natural waxy substances on the yarn surface are destroyed, making the yarn feel harder. Therefore, after dyeing, a certain compound is added to the yarn to reduce friction between yarns, facilitating winding and subsequent weaving processes.

 

How are textile fibers classified?

Fibre soft and slender substance with length to diameter ratio at least 10:1,  the cross-sectional area less than 0.05mm2. For textile fibers, the ratio of length to diameter is generally greater than 1000:1. 

About textile fibers: Natural fiber, such as cotton, hemp, wool, silk and so on; Chemical fiber refers to natural or synthetic polymers as raw materials, through chemical methods and mechanical processing made as fiber.

 

1) According to the source of raw material: Regenerated fibre and Synthetic fibres

  • Regenerated fibre also be called as synthetic fiber, using natural polymers or lost textile processing value of fiber raw materials through a series of chemical treatment and mechanical processing be fiber again, the chemical composition of the fiber and original polymer is alomost same. Including Regenerated cellulose fibre (such as viscose fiber, copper ammonia fiber), Regenerated protein fiber  (such as soy protein fiber, peanut protein fiber), regenerated inorganic fiber (such as glass fiber, metal fiber)  and regenerated organic fiber (such as chitin fiber, seaweed gum fiber).
  • Synthetic fiber is made of natural low molecular compounds such as petroleum, coal, limestone, natural gas, salt, air, water and some agricultural and sideline products as raw materials, through chemical synthesis and processing be fibers. There are seven common types of synthetic fibers: polyester fiber (polyester), polyamide fiber (nylon), polyacrylonitrile fiber (acrylic fiber), polyvinyl formaldehyde fiber (vinylon), polypropylene fiber (polypropylene), polyvinyl chloride fiber (chlorinated fiber) and polyurethane elastic fiber (spandex), etc. 

     

     

    2) Classification by morphological structure: Continuous filament and Staple fibre

    • Continuous filament 

      During chemical fiber manufacturing process, spinning fluid (fusant or melt) after spinning forming and post-processing, the length of fiber is caiculated in kilometers is called chemical fiber filament. Chemical fiber filaments can be divided into monofil, multifilaments, twisted fibers, double twisted fibers, cord fibers and Textured filament.

      Monofilament: A single continuous fiber of very long length.

      Multifilaments: A filament composed of two or more single filaments joined together. Complex filaments of chemical fibers are generally composed of 8 to 100 single fibers.

      Twist yarn: twist Multifilaments  becomes twist yarn.

      Double twist yarn: Two or more strands of twist yarn are combined to be double twist yarn.

      Cord wire: composed of more than one hundred to several hundred single fibers, used to make tire cord fabric.

      Textured filament yarn: The chemical fiber filament is deformed and processed so that it has the appearance characteristics of curling, spiral, ring and so on, showing fluffy and flexible filament.

      • Staple fibre

        The product of the chemical fiber is cut into few centimeters to dozen centimeters in length, it is called staple fiber. According to the different cut length, staple fibers can be divided into cotton type, wool type and medium long staple fibers.

        The length of Cotton type fibre is 30 ~ 40mm, the linear density is about 1.67dtex, the fiber is fine, similar to cotton. The length of Wool type fibre is 70 ~ 150mm, the linear density is 3.3 ~ 7.7dtex, the fiber is thicker, similar to wool; Mid fibre has a length of 51 ~ 65mm and a linear density of 2.2 ~ 3.3dtex, between cotton type and wool type.

         

        3)  Classification by fiber manufacturing method

        Chemical fibers can be divided into two categories according to the basic manufacturing methods,  melt spinning fibers and solution spinning fibers (i.e. dry spinning fibers and wet spinning fibers).

        • Melt spinning is polymer melt is pressed out of the spinneret hole, melt is solidified into silk in the surrounding air (or water).
        • Dry-spinning is polymer concentrated solution is pressed out from the spinneret hole form as trickle, solvent evaporates rapidly in hot medium and solidifies into silk. 
        • Wet spinning is polymer concentrated solution is pressed out of the spinneret hole and solidified into silk in a coagulation bath.

           

          4) Classification by composition within a single fiber

          • Single-component fibers: Fibers composed of the same polymer are called single-component fibers, and most conventional fibers are single-component fibers, such as polyester.
          • Multicomponent fibers:Fibers composed of two or more polymers are called multicomponent fibers, such as acrylic fibers. 
          • Composite fiber:the components are arranged regularly along the fiber axis and form a continuous interface fiber.
          • Blended fiber: components are randomly dispersed or more evenly mixed fiber

             

            5) Classification by fiber difference

What's the reason causes yarn non-recurrence by package yarn dyeing?2

PRETREATMENT INFLUENCES REPRODUCIBILITY

Many dyeing plants don't pay attention to pre-treatment. Actually, many problems in dyeing processing because of ingnoring do enough pre-treatment. Impurity removal degree, whiteness, pH value after washing, purification of hydrogen peroxide after bleaching, amount of alkali carried by mercerized yarn, different tension affect gloss. When dyeing bobbin yarn, pre-treatment, dyeing and post-treatment are carried out in the same high pressure bobbin dyeing machine, and the pre-treatment effect is also different.

Generally, the dyeing factory pays more attention to force determination and weighing of dyes,but less attention is paid to the force determination and weighing of other chemicals. 

Caustic soda, soda ash, hydrogen peroxide is not analyzed, only calculated according to instructions, dye liquor are rarely titrated. So pre-treatment effect is different, causes difference of color depth and hue.

As mentioned, paying attention to compatibility, compatibility, sensitivity and quality of dyestuff, in order to ensure reproducibility.

 

RATIONALITY OF DYEING TECHNOLOGY INFLUENCES REPRODUCIBILITY

Although selecting appropriate dye, the dyeing process is designed not reasonable, there also be cylinder differences.  Such as temperature design, heating rate, holding time, amount of additives and feeding method scientificity, the rationality of post-treatment process design will affect the dyeing amount of dyestuff resulting in color difference.

Such as adding reactive dye solid alkali, fixation and hydrolysis of reactive dyes have a lot to do with the pH value of dye bath, the scientific feeding method is to maintain the Pu value at a fixed value (such as pH value is 11.5), which is related to the feeding method and feeding rate, if one-time feeding or feeding fast and slow all will cause pH fluctuations, amount of fixation and hydrolyzed dyes is different, finally eflects the different shades of light.

package yarn dyeing machine

 

Why do raw cotton dyeing and its spinning processing?

In order to fully improve the added value of colored product, except add patten, high-count yarn & blended yarn and special dyeing process can also be used to achieve a unique style of colored cloth. Pure cotton blended yarn-dyed fabric: soft feel, breathable, strong water absorption. In recent years, it has been favored by the majority of consumers. Color cotton by mixing cotton, carding cotton, spinning, weaving to eliminate color difference, it is convenient production.

RAW MATERIAL REQUIREMENT

1. Raw cotton requirement

After the raw cotton dyeing, the color cotton should be mixed, combed, spun, and finally wovenhttps://www.yarnfabricdyemachine.comknitted, and the requiements of color difference is not strictly, so it is suitable for any variety of raw cotton.

2. Dye compound

The dyestuffs and auxiliaries are used for cotton bleaching and dyeing: with fine particles and soluble in water, good diffusion and permeability.

 

DYEING

In order to obtain better color mixing effect of cotton textiles, pay attention to two important points in raw cotton dyeing: remove natural impurities of loose fiber and spinnability of dyed cotton fiber.

1. Pretreatment

Cotton fibers contain many symbionts, such as waxes, nitrogen, pectin, minerals and natural pigments, cottonseed shells, etc. The existence of these symbionts will seriously affect the wettability of cotton fiber, making it difficult to dyeing, so it must be removed first. The pre-treatment of raw cotton dyeing: boiling and bleaching and related washing. The purpose is to remove cotton impurities, fruit gum and natural pigments that hinder dyeing. After boiling and fully washing, it is necessary to check whether the concentration of alkali, residual hydrogen peroxide and whiteness meet the process requirements or not. Generally, the whiteness of the cotton fiber after pre-treatment are consistent, and the pH value is neutral.

2. Raw cotton dyeing

Using direct dyes and reactive dyes, considering the color fastness and convenience of use, using reactive dyes is better, because reactive dyes with bright color, complete chromatography and a certain wet processing fastness. The process control is stable and appropriate additives, the reproducibility of dyeing is good, cylinder (batch) difference is less. In addition, the use of reactive dyes dyeing, if it is combination of color, it is best to choose a better compatibility of reactive dyes for collocation.

3.  Postprocessing

Post-treatment is an important part of raw cotton dyeing, after dyeing should do fully washed and soaping treatment, in order to remove impurities and residual chemical additives on the cotton fiber. When washing, detergent with strong decontamination ability and good permeability should be used to enhance the cleaning effect of the inner layer of the fiber. After washing, in order to increase the spinnability, softening agent should be added for softening treatment to improve the lubricity of the fiber.

 

DEHYDRATOR AND DRYING

After dehydration , the color cotton treated by softener is easy to loose, after production practice, the moisture return after drying is controlled at 6 to 8, with soft feel and good spinnability.

 

SPINNING TECHNOLOGY

After raw cotton dyeing, the cotton fiber lost  spinnability processing of boiled and bleached, removed wax and oil, feel becomes coarse. In order to improve this situation, one the one hand, adding softener to loosen the cotton and improve its spinnability after full washing. On the other hand, reasonable cotton matching with raw cotton. There are two kinds of cotton matching between colored cotton and raw cotton: One is carried out in the cotton cleaning process, the color cotton and the raw cotton after grabbing cotton, mixing cotton, opening into rolls and  strips, finally spinning and knitted or woven fabric; Another one is processing during combining, the color sliver with the raw cotton sliver, through two strips, so that it is mixed into a strip, finally spinning and weaving or knitting. Through experiment, the former method is better, color cotton and raw cotton through mixing , carding, spinning and weaving, basically eliminate color difference.No matter which one is adopted, the mixing ratio of color cotton and raw cotton is generally controlled at about 0.5-10 percent, spinnability is better, don't  change the original production technology.

 

DYEING INTANCE

9.7tex red cotton using Shin Tong Yunn high pressure dyeing machine, bath ratio 1:15, internal and external cycle time ratio 5:3.

1. Process flow: raw cotton- boiling-washing-dyeing-washing-soft treatment-dehydration-drying - packing

2. pretreatment

Process prescription, (ghttps://www.yarnfabricdyemachine.comL)NaOH(36 'Be) 5 stabilizer FT 2OH202(27.5%) 8,  Temperature 120℃ penetrant JFc 1.0 time 120min.

3. Raw cotton dyeing (bright red) process prescription, (ghttps://www.yarnfabricdyemachine.comL) Peregal O 015 reactive brilliant orange X-Gn 3. 575N a2CO 3 25 Bright Red X一3B 6.i25Na2SO. 70。

4. Soft treatment

Process prescription, (ghttps://www.yarnfabricdyemachine.comL) softener HC-8

5. Dyeing cotton by spinning process

Cotton blending - roll - carding - strip - roving - fine yarn - raw cotton - fine cotton

 

NOTE:

DF241 series high pressure cone yarn dyeing machine is suitable doing pre-treatment, post processing and dyeing of raw cotton(cotton fiber), only need change the carrier form.