Spinned CDA (also known as cellulose diacetate flakes) are the core raw materials for producing cellulose acetate fibers, especially acetate bundles used in textiles. It is a chemical derivative made from natural cellulose (usually derived from high-purity wood pulp or cotton wool) through a vinegar reaction. The application process is essentially a "dissolution spinning" chemical fiber manufacturing process.

1. What is spinning cellulose diacetate flakes?

Firstly, it is necessary to distinguish between "cellulose diacetate flakes" and ordinary plastic "acetate esters".

cellulose diacetate flakes:  It is generated by replacing the hydroxyl (- OH) portion on cellulose molecules with acetyl groups. The degree of acetylation is usually between 52% and 56%. This degree of acetylation allows it to dissolve in common solvents such as acetone, which is the key to its use in spinning.

Spinning grade: Not all cellulose diacetate flakes can be used for spinning. Spinning grade cellulose diacetate flakes have extremely strict requirements for purity, molecular weight distribution, color, transparency, and impurity content to ensure the stability of the spinning solution and the quality of the final fibers.

2. Manufacturing process from cellulose diacetate flakes to textile yarn bundles

The entire process can be summarized as the following core steps:

Step 1: Preparation of spinning solution (dissolution and filtration)

Dissolve: Mix the dried spinning cellulose diacetate flakes with acetone in a dissolution kettle with strong stirring. cellulose diacetate flakes will dissolve in acetone to form a viscous, transparent, honey like solution called "spinning solution" or "gel solution". The concentration of the solution is usually controlled at around 20% -25%.

Filtration and deaeration: The spinning solution needs to be subject to multi-stage precision filtration to remove any tiny insoluble impurities and gel particles, so as to prevent blocking the spinneret during the spinning process. Subsequently, defoaming is carried out to remove bubbles from the solution, ensuring the continuity of the spinning process and the uniformity of the fibers.

Step 2: Spinning Forming (Dry Spinning)

Acetate fiber mainly adopts dry spinning technology, which is its process characteristic.

Measurement and transportation: After filtering and defoaming, the pure spinning solution is stably transported to the spinning components through a precision metering pump.

Spinning: The spinning solution passes through the spinning plate on the spinning component under pressure. The spinneret is covered with micrometer sized small holes, from which the spinning solution is extruded, forming countless small streams of liquid.

Solvent evaporation and fiber solidification: These small streams enter a long tube called the spinning channel. In the passage, hot air (usually an inert gas such as nitrogen, as acetone is flammable) is introduced in the opposite or same direction as the liquid flow. Hot air causes the acetone solvent in the liquid flow to evaporate rapidly. As the solvent evaporates, cellulose acetate solidifies and precipitates from the solution, forming solid continuous filaments.

Bundle and oiling: Multiple single filaments coming out from the lower part of the tunnel are integrated into a bundle, known as a "bundle". Subsequently, the tow is oiled to give it smoothness and anti-static properties for subsequent textile processing.

Step 3: Post processing and winding

Stretching: The fiber bundle is stretched (stretched) at a certain speed and tension to arrange the macromolecular chains more neatly along the fiber axis, thereby improving the strength, orientation, and mechanical properties of the fiber.

Winding: Finally, the processed fiber bundle is wound onto a tube to form a yarn drum, which is used for subsequent weaving, twisting, or weaving.

3. Spinning type cellulose diacetate flakes impart characteristics to the fiber bundle

The final performance of acetate tow made from cellulose diacetate flakes is closely related to the quality of the raw material cellulose diacetate flakes, mainly exhibiting the following characteristics:

Silk like feel and luster: Acetate fiber has a unique, smooth touch and elegant luster, and its appearance and feel are closest to natural silk, which is its biggest advantage.

Good drape: The fabric made is soft, elegant, and has excellent drape, making it very suitable for making dresses, gowns, ties, and lining fabrics.

Moisture absorption and breathability: Although not as good as cotton, it is superior to synthetic fibers (such as polyester fibers), comfortable to wear, and less prone to stuffiness.

Excellent dyeing performance: easy to dye, bright colors, good color fastness.

Thermoplastic: capable of softening and shaping upon heating, thus allowing for permanent creasing and texturing.

Not easy to pill: The fiber surface is smooth and not prone to pilling.

Disadvantages: Relatively low strength (especially wet strength), and inferior wear resistance compared to nylon and polyester fibers.

4. Application Fields

Acetate fiber bundles made from spinning type cellulose diacetate flakes are mainly used in the following high-end textile fields:

Clothing field:

Lining: The preferred lining material for high-end suits and jackets, as it is smooth and non stick to the body.

Women's clothing: dresses, shirts, evening gowns, scarves, etc., utilizing their silky texture and drape.

Tie and scarf.

Home textiles: high-end curtains, decorative fabrics.

Spinning vinegar flakes are a key bridge connecting natural cellulose with high-end acetate fiber textiles. By dissolving it in acetone and using a unique dry spinning process, the resulting acetate tow occupies an irreplaceable high-end niche market in textile materials with its excellent silk like feel, luster, and drape. The core of the entire manufacturing process is the precise control and conversion of the chemical raw material, vinegar tablets.