What are the characteristics of amino silicone oil

Amino silicone oil has four important parameters: ammonia value, viscosity, reactivity and particle size. These four parameters basically reflect the quality of amino silicone oil, and will greatly affect the style of the treated fabric. Such as hand feel, whiteness, shade and ease of silicone oil emulsification.

1 Ammonia value

The various properties that amino silicone oil imparts to the fabric, such as softness, smoothness, and fullness, are mostly brought about by the amino groups in the polymer. The amino content can be expressed by the ammonia value, which refers to the number of milliliters of 1 normal concentration of hydrochloric acid required to neutralize 1 g of amino silicone oil. Therefore, the ammonia value is directly proportional to the mole percent of the amino group content in the silicone oil. The higher the amino content, the higher the ammonia value, and the softer and smoother the finished fabric feels. This is because the increase of amino functional groups greatly increases the affinity for the fabric and forms a more regular molecular arrangement, thus giving the fabric a soft and smooth hand.

However, the active hydrogen in the amino group is easily oxidized to form a chromophore, causing the fabric to be yellowed or slightly yellowish. In the case of the same amino group, obviously with the increase of the amino group content (or ammonia value), the probability of oxidation increases, and the yellowing is serious. With the increase of ammonia value, the polarity of amino silicone oil molecules increases, which provides a favorable prerequisite for the emulsification of amino silicone oil, which can be made into microemulsion, and the selection of emulsifier and the size and distribution of particle size in the emulsion are also related to Ammonia value is related.

2 Viscosity

Viscosity is related to polymer molecular weight and molecular weight distribution. Generally speaking, the higher the viscosity, the higher the molecular weight of the amino silicone oil, the better the film-forming property on the surface of the fabric, the softer the hand feel, and the better the smoothness, but the worse the permeability, especially for strong twist tight fabrics and fine denier fabrics. For fabrics, amino silicone oil is difficult to penetrate into the fiber, which affects the performance of the fabric. If the viscosity is too large, the stability of the emulsion will be deteriorated or it will be difficult to make a microemulsion. Generally, the product cannot be adjusted only by the viscosity, and the performance of the product is often balanced by the ammonia value and the viscosity. Usually a low ammonia value requires a high viscosity to balance the softness properties of the fabric.

Therefore, a high-viscosity amino-modified silicone oil is required for a smooth hand. However, during softening and baking, some amino silicone oils cross-link to form films, thereby increasing the molecular weight. Therefore, the initial molecular weight of amino silicone oils is different from the molecular weight of amino silicone oils that eventually form films on fabrics. Therefore, when the same amino silicone oil is processed under different process conditions, the slip properties of the final product can be very different. On the other hand, low-viscosity amino silicone oil can also improve the feel of the fabric by adding a cross-linking agent or adjusting the baking temperature. Low-viscosity amino silicone oil increases the permeability, and then through cross-linking agent and process optimization, the advantages of high and low-viscosity amino silicone oil can be combined. Generally, the viscosity of amino silicone oil ranges from 150 to 5000 centipoise.

But it is worth noting that the molecular weight distribution of amino silicone oil may have a greater impact on product performance. The low molecular weight penetrates into the fiber, while the high molecular weight is distributed on the outer surface of the fiber, so that both the inside and outside of the fiber are wrapped by amino silicone oil, thereby giving the fabric a soft and smooth feeling, but the problem may be that the difference in molecular weight will affect the micro-organism. Emulsion stability.

3 Reactivity

Reactive amino silicone oil can produce self-crosslinking during finishing, and the increase of crosslinking degree will increase the smoothness, softness and fullness of the fabric, especially the elasticity improvement is more obvious. Of course, when a cross-linking agent is used for general amino silicone oil or the baking conditions are increased, the degree of cross-linking can also be increased, and thus the rebound can also be improved. Amino silicone oil with hydroxyl or methylamino end, the higher the ammonia value, the better the degree of crosslinking, and the better the elasticity.

4 Microemulsion particle size and emulsion charge

The particle size of amino silicone oil emulsion is small, generally less than 0.15μ, so the emulsion is completely thermodynamically stable dispersion state, and its storage stability, heat resistance stability and shear resistance stability are excellent, and generally will not break demulsification. At the same time, the small particle size increases the surface area of the particles, thereby greatly improving the contact probability between the amino silicone oil and the fabric, the surface adsorption increases, the uniformity increases, and the permeability increases, so it is easy to form a continuous film and improve the softness and smoothness of the fabric. and fullness, especially on fine denier fabrics. However, if the particle size distribution of amino silicone oil is not uniform, it will greatly affect the stability of the emulsion.

The charge properties of aminosilicone oil microemulsions depend on the emulsifier. In general, anionic fibers are easy to adsorb cationic amino silicone oil, thereby improving the treatment effect. The adsorption of anionic emulsions is not easy, and the adsorption capacity and uniformity of nonionic emulsions are better than that of anionic emulsions. If the negative charge of the fiber is small, the influence on the different charge of the microemulsion is greatly reduced. Therefore, chemical fibers such as polyester absorb various microemulsions with different charges and their uniformity is better than that of cotton fibers.