Detailed explanation of the types and characteristics of various softeners(2)

6. Cationic softener

There are many varieties of this type of softener, and it is the most commonly used softener at present.

Mainly because most fibers have negative charges in water, cationic softeners are easily adsorbed on the surface of fibers, have strong binding ability, are resistant to high temperature and washing, and the fabrics are plump and smooth after finishing, which can improve the wear resistance of the fabrics. Tear strength, also has a certain antistatic effect on synthetic fibers. Therefore, it is widely used in cotton, nylon, acrylic and other fabrics, and this variety is also suitable for silk. However, some cationic softeners are prone to yellowing at high temperatures, accompanied by a decrease in color fastness to light. Cationic softeners are generally derivatives of octadecylamine or dimethyl octadecylamine or condensates of stearic acid and polyvinylpolyamine. According to its structure, it can be divided into tertiary amine softener, quaternary ammonium salt softener, imidazoline quaternary ammonium salt softener, dialkyldimethyl quaternary ammonium salt softener, etc.

7. Amphoteric softener

Amphoteric softeners are a class of softeners developed to improve cationic softeners. It has a strong affinity for synthetic fibers, and has no disadvantages such as yellowing and discoloration of dyes. It can also be used in the re-training process of silk to make silk feel better. Amphoteric softeners can also be used together with cationic softeners to act synergistically. Such softeners are generally of the alkylamine lactone type structure.

8. Silicone softener

This type of softener is an emulsion or microemulsion of polysiloxane and its derivatives, which can make fabrics have a good soft and smooth hand. The products include emulsion polymerization, polymer silicone oil emulsification, modification, compounding and other production processes. The system has been basically formed, and there are many varieties and brands available. However, the application effect and performance are still very different.

1. Dimethyl silicone emulsion:

This is the earliest product used in silicone softeners. The relative molecular weight of silicone oil used as softeners is generally 60,000-70,000. After finishing, it can give the fabric a smooth, stiff and cool feel, reduce the friction coefficient of the fabric, and improve the wear resistance and seamability of the fabric. However, because there is no reactive group on the molecular chain, it cannot react with the fiber, nor can it be cross-linked by itself, but only adheres to the surface of the fiber by molecular binding, so the washing resistance is poor and the elasticity improvement is limited.

2. Organic silicone hydroxy emulsion (hydroxy silicone oil emulsion):

This is the most widely used silicone softener in my country in the 1980s. Its relative molecular mass is generally 60,000-80,000. The larger the relative molecular mass, the better the softness and smoothness. Due to its molecular chain end and Hong group end cap, under the action of cross-linking agent and catalyst, it can cross-link with the reactive group of the fiber or itself to form a certain elastic polymer film, so it has washing resistance. , and can improve the elasticity of the fabric. Organosilicon hydroxyemulsion is divided into cationic organosilicon hydroxyemulsion and anionic organosilicon hydroxyemulsion according to the ionicity of the emulsifier used. Although there are hydroxyl groups at the end of the molecular chain of silicone hydroxy emulsion, which is helpful to improve its hydrophilicity and emulsion stability, because the emulsion particles of silicone hydroxy emulsion are difficult to control to be small and uniform, the stability of the emulsion is also very high. It is difficult to master, and it is easy to appear oil bleed during application, so that there are oil spots and other defects on the fabric that are difficult to remove. Therefore, the emulsion stability of silicone hydroxy emulsion softener is also an important indicator for evaluating its quality.

3. Hydrophilic soluble silicone (polyether type hydrophilic silicone):

This type of silicone softener is usually polyether and epoxy modified polysiloxane, which is a colorless and transparent thick liquid, which can give the fabric good moisture absorption, air permeability and antistatic properties. Ionic, can be mixed with various additives. When used together with resin, it can reduce the chlorine absorption and formaldehyde release of the resin; in addition to resin finishing and soft finishing, it is also widely used in paint dyeing process, which can not only improve the feel of the fabric affected by the adhesive, but also The disadvantage of adhesive sticking to the roller can also be improved.

4. Amino-modified silicone:

The introduction of amino groups into the macromolecular chain of polysiloxane can greatly improve the performance of silicone. The introduction of amino groups can not only form a firm orientation and adsorption with fibers, reduce the friction coefficient between fibers, but also chemically react with epoxy groups, carboxyl groups and hydroxyl groups, so it can be applied to cotton, wool, silk, viscose Fiber, polyester, nylon, acrylic and other fibers and their blended fabrics. After the fabric is finished, it can obtain excellent softness and resilience, and its hand feels soft and plump, smooth and delicate. Generally speaking, the higher the amino content, the better the softness. But higher amino content also means greater yellowing.

This is mainly due to the fact that -(CH2)NH(CH2)2NH2 on its side chain has two amine groups (primary and secondary), a total of three active hydrogen atoms, which are easily oxidized to form chromophores, and this double The amine structure has a more synergistic effect of accelerating oxidation. Therefore, there must be an optimal balance between amino content and yellowing. The preparation of amino-modified silicones into microemulsions has developed rapidly in the past decade. Due to the introduction of amino groups into the siloxane molecules, its hydrophilicity is improved, so by selecting appropriate emulsifiers and preparation techniques, it can be made into a microemulsion with a particle size of less than 0.15 μm.

Since its particle size is smaller than the wavelength of visible light, it has no resistance to visible light, thus making the emulsion transparent. It is the particle size of its particles that is only 1/10 of the particle size of the ordinary emulsion, which increases the number of effective particles in the microemulsion by 103 times (if the concentration is the same), and greatly increases the contact opportunity between the microemulsion and the fabric. The surface has good spreadability and can easily penetrate into the fiber. This product thus imparts a good internal softness to the fabric, which is also more durable. The water solubility, storage stability, thermal stability, and shear stability of microemulsion products are generally better.

Although the commonly used bisamino silicone softener has a good softening effect, its whiteness, water absorption and easy decontamination are all poor, and it becomes serious with the increase of amino functional groups in the polymer. To ameliorate these drawbacks, changes in the type and number of amino functional groups can be achieved. Changing the type of amino functional group is mainly to change the primary amino group into a secondary or tertiary amino group, such as N-propylcyclohexylamine (secondary amine) and N-propylpiperazine (tertiary amine) modified silicone softener It has been developed for fabric finishing. These softeners reduce yellowing during baking and are less hydrophobic than primary amine-functional silicone softeners, but impart a somewhat dry hand to the fabric. Mainly used for soft finishing of bleached woven and light-colored fabrics.

In addition, in order to obtain an ultra-smooth hand, the two ends of the dimethylsiloxane macromolecules are modified with amino groups, which can form a very neat orientation on the fabric, so as to obtain an excellent smooth hand; if the polymer Part of the side chain groups and both end groups of siloxane are modified and substituted with amino groups, and it can be used as a fabric finishing agent, which can make the fabric obtain better softness. Now the silicone softener is developing rapidly, with more and more varieties, the price has also dropped, and the number of applications using silicone softener has increased significantly. In addition to the above-mentioned various silicone softeners, there are also silicone softeners such as epoxy group modification, amide group modification, and carboxyl group modification. Because there should be less at present, I will not introduce them one by one here.

9. Low molecular weight polyethylene emulsion

This type of softener is the product of emulsification of low molecular weight polyethylene after oxidation treatment. It has a certain affinity for fibers, so that the fabric has a smooth hand, can be applied in the same bath with resin, and can improve the tearing strength and wear resistance reduced by resin finishing. It is a cheap fabric before the popularization and application of silicone softener. Soft and slip additive. At present, this type of softener is generally not used alone, and can be used as a compound component of various softeners, and can also be used as a stabilizer in hydroxysilicone emulsions.