Cationic modification dyeing mechanism

Cationic modification dyeing mechanism

Analysis of cationic modification dyeing mechanism

The full name of cationic polyester yarn: cationic dyed polyester is called cationic dyeable polyester, belonging to denatured/modified polyester, which can be dyed with cationic dye at 110 degrees. Cationic modification dyeing mechanism

The cationic yarn is a modified polyester. The chemical name: polybutylene terephthalate (elastic polyester), abbreviation: PBT, is also indicated by CD in the factory. Because ordinary polyester (polyethylene terephthalate) has low moisture absorption, poor dyeing performance, easy accumulation of static electricity, easy to fluff and other shortcomings, it is usually modified with a sulfonate as a modifier to be dyed with cationic dyes. Polyester, or adding a cationic active agent before spinning or spinning to prepare a modified polyester. Such a yarn is called a cationic yarn. This yarn does not need to be dyed at a high temperature like normal polyester (130-135 ° C), at room temperature. It can be dyed. Cationic modification dyeing mechanism

Cationic modification dyeing mechanism

Polyester fiber is a hydrophobic synthetic fiber lacking a functional group capable of binding to a direct dye, an acid dye, a basic dye or the like. Although it has an ester group capable of forming a hydrogen bond with the disperse dye, the polyester molecular chain structure is tight, and the dye molecules are not easily entered into the fiber interior, resulting in difficulty in dyeing and monotonous color, which directly affects the development of polyester fabric color varieties.

Due to the high crystallinity of polyester, there are only small gaps in the fiber. When the temperature is low, the thermal motion of the molecule changes its position to a small extent. Under humid conditions, the polyester fiber does not pass the violently like cotton fiber. The swelling causes the void to increase, and the dye molecules are hard to penetrate into the inside of the fiber. Polyester dyeing can usually only be dyed with disperse dyes and must be dyed under high temperature and pressure or by means of a carrier. Cationic modification dyeing mechanism

In order to improve the dyeing performance of polyester, from the molecular structure considerations, increasing the degree of looseness of the molecular chain will contribute to the entry of dye molecules. The main methods used to improve dyeing performance are:

(1) copolymerization with a chemical substance having a large molecular volume;

(2) mixing and spinning with a compound having a plasticizing effect;

(3) A group having an affinity for a disperse dye such as an ether bond is introduced.

The polyester resin modified by the copolymerization method has a low melting point and a low crystallinity, and the thermal properties and mechanical properties of the fiber are damaged to some extent. Cationic modification dyeing mechanism

The cationic dye dyeing modification method is to copolymerize a polyester dyeing modifier, such as sodium phthalate-5-sulfonate (commonly known as three monomers, English abbreviation SIPM) with polyester, in the polyester molecular chain after copolymerization. Cationic modification dyeing mechanism

Sulfonic acid groups are introduced, which can be dyed with cationic dyes. The dyed fabrics are brightly colored, the dye exhaustion rate is high, and the discharge of printing and dyeing wastewater is greatly reduced. The copolymerized polyester chips can also increase antistatic, anti-pilling and moisture absorption properties. It is one of the main methods to improve the dyeing performance of polyester in recent years.

Japanese Unijika Company uses 4 parts of cationic dyeable polyester with sulfonic acid group-containing isophthalate unit and 1 part of ethylene glycol/polyethylene glycol/sulfonic acid sodium isophthalate/p-benzene The block copolymer of diformic acid is blended and spun to form a microfiber having a high dyeing depth.

A cationic active agent and a small amount of a denaturant are copolymerized with BHET (hydroxyethyl terephthalate) prior to spinning or during spinning. When it is made into a random linear polymer, its spinnability becomes good. This modified polyester can be dyed not only with cationic dyes, but also with pilling resistance and improved wrinkle recovery.

In addition, while the cationic dyeable fiber was introduced, a modified polyester (PBT) using 1,4 butanediol instead of ethylene glycol as the second monomer also joined the ranks of differentiated polyester. Cationic modification dyeing mechanism

Replacing ethylene glycol with butanediol not only greatly increases the flexibility of the molecular chain, but also greatly improves the dyeing performance of the fiber, reaching atmospheric pressure boiling at 100 °C.

However, since the raw material price of 1,4 butanediol is much higher than that of ethylene glycol, PBT fiber lacks a competitive advantage in price. Therefore, at present, mainly 1,4 butanediol is added as a third monomer in regular PET, so that not only the price of the fiber is lowered, but also the dyeing property is improved, and the thermal stability is much better than that of the cationic dyeable fiber. .

The commonly used cationically modified polyester filament is a new type of polyester product which is spun by introducing dimethyl isophthalate with polar SO3Na into the polyester chip, and its appearance is different from ordinary polyester filament. The difference, but due to the use of ion modification, not only greatly improves the color absorption performance of the fiber, but also reduces the crystallinity and makes the dye molecules easy to permeate, making the fiber easy to dye, the color absorption rate is improved, and the hygroscopicity is also improved;

The fiber not only ensures the cation is easy to dye, but also increases the micropores of the fiber, improves the dyeing rate, gas permeability and hygroscopicity of the fiber, thereby further adapting to the simulated silking of the polyester fiber; the silky fabric can be soft and breathable by simulating the silk. Comfortable, antistatic, normal temperature and pressure can be dyed. Cationic modification dyeing mechanism

By cationically modifying multifunctional hair-like hair, the fabric can be soft, antistatic, anti-pilling, normal temperature and pressure and co-dye. A fabric woven from cationically modified fibers has the following characteristics when dyed with a cationic dye:

  1. The color is bright and the dyeing is good;
  2. High moisture absorption performance;
  3. Good light fastness and color fastness;
  4. When color matching is dyed, the dye compatibility is good;
  5. Good stability in high temperature dye bath;
  6. Small contamination to other fibers including ordinary polyester fibers;
  7. The diffusion rate to the inside of the fiber is fast, no ring dyeing phenomenon;
  8. Dye stability is high when the pH value changes in the dyebath.

The fabric is comparable to natural fabrics in terms of wearing comfort, dyeing, and the like, and is lower in price than natural silk, and can generate high added value.

Cationic modified polyester filaments can not be distinguished from polyester filaments. If you want to distinguish them, you can only use the dyeing method! Cationic materials are generally dark! Cationic modification dyeing mechanism

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