Relationship between the Dosage of Quaternary Ammonium Salt Softener and its Properties

Dec 23, 2020

The amount of softener directly affects the thickness of lubricating oil film on the fiber surface. According to the oil film thickness D, the lubrication properties can be divided into fluid lubrication and boundary lubrication.

The strength of lubricating film is inversely proportional to the thickness d of lubricating film. If the viscosity of lubricating layer is too large, the thickness of fluid lubrication layer will increase correspondingly, which will cause the strength of lubricating film to decrease. The friction between fibers will change from fluid friction and semi fluid friction to boundary friction. Too high viscosity will also affect the penetration and spreading of lubricating film on the fiber surface, and finally affect the softening effect. With the increase of softener dosage, both N and viscosity (i.e. increase of lubricating film thickness d) are increased; the former is beneficial to the strength, while the latter is on the contrary, the dosage should be balanced. Therefore, the application of softener should have a certain amount, but it should be appropriate and not too much or too little.

The amount of softener has the following relationship: the oil content of boundary friction is 0.05-0.3% (OWF), the oil film thickness is about 1 μ m (l0-6mm), forming a single molecule adsorption layer; the oil content of fluid lubrication is 0.3-2% (OWF), the oil film thickness is about 100 μ M (10-6mm). The amount of softener is more than 0.3 (OWF), and the lubrication of fiber is mostly fluid lubrication. When the dosage of single or double long chain alkyl (c16-18c) quaternary ammonium salt is 0.1-0.2% (OWF), the oil film with the thickness of 5-10 μ m is formed on the fiber surface, which has enough softness. The problem is that the softener should be spread evenly on all the fiber surfaces to obtain better softening effect.

The thickness of the oil film formed on the surface of the fiber is not only related to the amount of softener, but also to the size and specific surface area of the fiber. The specific surface area of the fiber with smaller size is larger, such as superfine fiber fabric or cashmere. The film with a certain thickness needs more softener, and the amount of softener needs to be increased.

Fabric structure also has a great influence on the softening effect. Loose fabrics such as knitted fabrics, cashmere fabrics, woolen fabrics, woollen fabrics, etc. after being softened, the fibers can be stretched freely, resulting in soft, smooth, fluffy, plump and thickening effects. For compact fabrics such as khaki, canvas and other fibers, it is difficult to stretch and slide, so the soft effect is not as good as the former.

Compounding of quaternary ammonium salt softener
(1) the compound of quaternary salt and silicone softener
Silicone softeners, especially amino silicone oil, have smoothness, elasticity and softness to fibers, and quaternary ammonium softeners have the same properties. However, amino silicone oil makes the fabric smoother, while the softness and fullness of the fabric are not as good as quaternary ammonium softener. Therefore, if two different types of softeners are used at the same time or compounded, satisfactory softening effect can be obtained.
Their compound preparation is to apply quaternary ammonium softeners to amino silicone oil microemulsions. Because of the sufficient emulsifier in the silicone oil emulsion, the emulsion of quaternary ammonium salt and amino silicone oil can be emulsified and a complex emulsion can be obtained.
The surface tension of amino silicone oil is very low, 15-22mn / m, which is not comparable to any other polymers except fluorine-containing polymers, and the solubility parameter is very small, about 7-8cal / cm3, so it is not compatible with many polymers, including quaternary ammonium salts containing long carbon chain aliphatic alkyl softeners. Therefore, when the fabric is finished with the compound amino silicone oil and quaternary ammonium salt softener, the amino silicone oil component always floats on the top layer, and the quaternary ammonium salt softener plays the role of leveling the base layer, so that the methyl groups in the amino silicone oil float on it are arranged more orderly, showing more smoothness, better luster, better elasticity, and the amount can be reduced.
(2) other combinations of quaternary salt
There are many shortcomings in the application of single quaternary ammonium softener, especially dialkyldimethylquaternary ammonium salt. For the hydrophobic fiber, the adsorption capacity of the softener is very small, the surface of the fiber is hardly modified, and the softening effect is not good. In case of anionic whitening agent, the whitening effect will be reduced and the fabric will turn yellow. For hydrophilic fiber, the soft handle is obtained, and the hydrophobicity of the fiber is increased, so that the moisture absorption of the fiber is reduced. Therefore, the quaternary ammonium salt softener is compounded, and the compounding method is introduced;
A. the cationic quaternary ammonium salt softener is pre directionally adsorbed on clay particles or some inorganic salts (clay molecular formula is a1203.2si02, · 2H2O), granulation, resulting in delayed solubility, and then mixed with anionic surfactant. The quaternary ammonium salt keeps a low concentration in the mixed reagent, which is lower than its CMC, and the quaternary ammonium salt softener is gradually released from the clay particles.
B. the quaternary ammonium salt softener is solubilized in anionic and nonionic surfactants, and the nonionic surfactant plays a solubilizing role in the working solution.