01
Definition of silicone oil
Silicone oil is a kind of polyorganosiloxane with different polymerization degree chain structure. It is made by hydrolysis of dimethyl dichlorosilane with water to make the primary polycondensation ring body, and the ring body is cracked and distilled to make the low ring body, and then the ring body, capping agent, and catalyst are put together to adjust the polymerization to obtain various mixtures of different degrees of polymerization, and the silicone oil is made by distillation under reduced pressure to remove the low boiling material.
The most commonly used silicone oil, the organic group is all methyl, called methyl silicone oil. Organic groups can also be used in place of some of the methyl groups to improve the performance of the silicone oil and to apply a variety of different uses. Common other groups are hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl, etc. In recent years, organic modified silicone oil has been developed rapidly, and many organic modified silicone oil with special properties have appeared.
Silicone oil is generally a colorless (or light yellow), odorless, non-toxic, non-volatile liquid. Silicone oil is insoluble in water, methanol, diol and – ethoxyethanol, and is miscible with benzene, dimethyl ether, methyl ethyl ketone, carbon tetrachloride or kerosene, and slightly soluble in acetone, dioxane, ethanol and alcohol. It has a small vapor pressure, high flash point and ignition point, and low freezing point. As the number of chain segments n varies, the molecular weight increases and the viscosity also increases, so this silicone oil can have various viscosities, from 0.65 centistokes to millions of centistokes. For low viscosity silicone oils, acidic white clay can be used as a catalyst and used to blend at 180°C, or sulfuric acid can be used as a catalyst and used to blend at a low temperature, while alkaline catalysts can be used to produce high viscosity silicone oils or viscosities.
02
Classification of silicone oil
According to the chemical structure, there are methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxyl silicone oil, ethyl hydrogen silicone oil, hydroxyl hydrogen silicone oil, cyanide silicone oil, etc.; from the application, there are damping silicone oil, diffusion pump silicone oil, hydraulic oil, insulating oil, heat transfer oil, brake oil, etc. The products are divided into applications such as damping silicone oil, diffusion pump silicone oil, hydraulic oil, insulating oil, heat transfer oil, brake oil, etc.
Silicone fluids have excellent heat resistance, electrical insulation, weather resistance, hydrophobicity, physiological inertness, and low surface tension, as well as low viscosity temperature coefficient and high compression resistance.
03
Silicone emulsions
Silicone emulsion is a form of silicone oil, the following from the silicone oil fabric soft finishing agent and silicone oil emulsion type defoamer two aspects to introduce.
I. Silicone oil fabric soft finishing agent
Silicone emulsions are mainly used as silicone oil fabric soft finishing agent.
The first generation of silicone fabric finishing agent is a mechanical mixture of dimethylsilicone oil and hydrogen-containing silicone oil (and its derivatives); the second generation of silicone fabric finishing agent is hydroxyl capped polydimethylsiloxane emulsion, which is made of octamethylcyclotetrasiloxane monomer, water, emulsifier, catalyst and other raw materials in certain conditions for emulsion polymerization. Since the polymerization and emulsification are done in one step, it has the advantages of short working time, high efficiency, simple equipment and convenient operation, etc. The emulsion obtained is very stable and the particles are very homogeneous, and the polymer made with active groups (hydroxyl groups) at both ends can further react to form a film, which is conducive to improving the application effect of the emulsion, which is inferior to that of mechanical emulsified silicone oil.
Hydroxy silicone oil emulsions can be divided into cationic, anionic, nonionic, complex ionic and other types of emulsions according to the different surfactants used.
1. Cationic hydroxysilicone oil emulsions
The emulsifier used in the polymerization of cationic hydroxyl emulsions is generally a quaternary amine salt (reported in foreign literature as octadecyltrimethylammonium chloride), and the catalyst is ammonium hydroxide. Cationic hydroxyl emulsion can be used for various textile finishing, with improved fabric feel, improve fabric elasticity and smooth, stiff performance; its another unique advantage is the ideal waterproofing agent for fabrics, and methyl hydrogenated silicone oil emulsion with water resistance and waterproof durability can reach a high level, can be used as a waterproofing agent for vinyl canvas, polyester card cloth, etc..
2. Anionic hydroxyl silicone oil emulsions
Anionic hydroxyl emulsions are characterized by good compatibility in fabric finishing agents and very stable emulsions. Especially in textile printing and dyeing, most of the additives are anionic, if the use of cationic hydroxyl emulsion is often prone to cause emulsion bleaching, and anionic hydroxyl emulsion can avoid this drawback, so more popular by the user unit, the use is very wide.
3. Compound ionic hydroxyl silicone oil emulsion
Although the cationic hydroxyl emulsion is an excellent fabric soft finishing agent, but this emulsion is not resistant to hard water, but also can not be used with two hydroxymethyl dihydroxyethylene urea resin (2D) resin, catalyst magnesium chloride and anionic whitening agent in the same bath, so there are certain limitations in the use. In addition, due to the poor stability of the emulsion, silicone polymers are easy to separate from the emulsion, floating on the liquid surface, commonly known as “oil bleaching”. If the emulsion polymerization process, the use of cationic and non-ionic emulsifiers for compounding, it can overcome the shortcomings of cationic emulsifiers for the preparation of hydroxy silicone oil emulsion, the resulting silicone emulsion can be resistant to hard water, with 2D resin, magnesium chloride and whitening agent VBL is used in the same bath, and has good heat resistance and freezing resistance.
4. Non-ionic hydroxyl silicone oil emulsion
Non-ionic hydroxyl emulsions are more adaptable and more stable than non-ionic hydroxyl emulsions, so many countries are vigorously studying non-ionic hydroxyl emulsions.
5、Other active groups of silicone finishing agent
In order to adapt to the needs of various types of advanced finishing fabrics, silicone finishing fabrics to improve the anti-oil, anti-static and hydrophilic properties, and make the chemical fiber fabrics with many advantages of natural fabrics, silicone workers have studied the introduction of other active groups on the silicone molecule such as amino, amide, ester, cyano, carboxyl, epoxy, etc.. The introduction of these groups make silicone fabric finishing agent with special effects, for example, the introduction of amino silicone molecules suitable for woolen fabrics and soft finishing; the introduction of amide groups suitable for anti-fouling finishing, softness is also greatly improved: the introduction of cyano oil resistance, polyethylene oxide ether and silicone copolymer anti-static effect is good; organofluorine modified silicone with oil repellent, anti-fouling, anti-static, water repellent and many other advantages. .
Second, silicone oil emulsion type defoamer
Silicone oil emulsion type defoamer is generally an oil-in-water (O/W) emulsion, that is, water is the continuous phase, silicone oil is the discontinuous phase. It is the silicone oil, emulsifiers and thickeners, such as premix, and then gradually add water and stir, and finally in the colloid mill repeatedly grinding until the emulsion meets the requirements.
Silicone oil emulsion type defoamer is the most widely used silicone defoamer, the largest amount of antifoaming agent. It is characterized by easy dispersion in the water system, and can be widely used as antifoaming agent for the water phase system. When using, the emulsion will be added directly into the foaming system, you can get a good defoaming effect. In order to improve the defoaming effect of emulsion and the accuracy of measurement, generally do not use more than 10% of concentrated silicone oil emulsion directly: instead, dilute it with cool water or directly with foaming solution to less than 10%. It is forbidden to use too hot or too cold liquid dilution, otherwise it will cause emulsion breaking. The stability of the emulsion will deteriorate after dilution, and stratification (oil bleaching) may also occur during storage, i.e., emulsion breakage. Therefore, it is advisable to use up the diluted emulsion as soon as possible. If necessary, thickeners can be added to improve the stability of the emulsion. For the intermittent operation process, silicone oil emulsion can be added once before the system operation, but also can be added in batches; for the continuous operation process, silicone oil emulsion should be added continuously or intermittently in the appropriate part of the system.
When using emulsion-type defoamer, especially consider the temperature of the foaming system and acid, alkaline and other conditions, because the silicone oil emulsion is more delicate, more than its range of use, the emulsion will prematurely break the emulsion, become inefficient or ineffective (the amount of silicone oil emulsion, generally 10 to 10Oppm of the weight of the foaming solution (according to the silicone oil). Of course, in special cases, there are less than 10ppm and more than 100ppm. The most appropriate dosage is mainly determined by test.
Most of the general silicone oil emulsion type defoamer is oil-in-water type. According to the different types of silicone oil, silicone oil emulsion type defoamer has the following types: 1.
1. silicone oil emulsion with dimethyl silicone oil as the main body
This type of defoamer is made of dimethylsilicone oil plus emulsifier and water, etc., can be widely used in fermentation, food, paper, fiber, pharmaceuticals, synthetic resins and other aspects.
2. Silicone oil emulsion with methyl ethoxy silicone oil as the main body
This kind of defoamer is made of methyl ethoxy silicone oil and matching agent.
3、Ethyl silicone oil as the main silicone oil emulsion
Silicone defoamer is moving toward the development of silicone a polyether block copolymer (or graft copolymer) direction. This type of defoamer due to both silicone and polyether properties, thus making the defoaming power greatly improved; silicone a polyether copolymer type defoamer can also be called self-emulsifying silicone defoamer, it is in the silicone molecular chain block (or graft) hydrophilic ethylene oxide chain or ethylene oxide propylene oxide chain, so that the hydrophobic siloxane part and hydrophilic polyether combined together, so the molecule has a large polarity. As antifoaming agent, the spreading coefficient is large, can be dispersed evenly in the foaming medium, high defoaming effectiveness, is a new type of high-efficiency defoamer. This kind of self-emulsifying silicone oil without the use of emulsifier, defoaming effect for some systems is quite satisfactory, it is particularly suitable for those who are not suitable for the use of general silicone oil emulsion and general silicone oil emulsion is difficult to perform the occasion.
04
Silicone oil in soft finishing points to note
There are many varieties of silicone oil emulsion finishing agents, and the quality varies. There are cationic, anionic, non-ionic, etc., there are a variety of modified amino silicone oil and linear silicone oil. General silicone oil in the use of soft finishing should pay attention to the following points.
1. control the amount
Such as 20% solid amino silicone oil, the amount of 1.5-3% (O.W.F) is sufficient, increase the amount does not increase the softness.
2. Shaping speed problem
When doing some thin fabrics (such as chiffon, silk simulation, Bali yarn), the shaping speed is very fast, sometimes it can reach 60m/min, the ordinary silicone oil is not good permeability, silicone oil backflow on the rolls can easily cause sticky rolls. When using, we should pay attention to change the working fluid in the groove and clean the rolls frequently.
3. Dipping cylinder problem
When the factory is doing impregnation soft, common silicone oil will be stained on the cylinder wall, and after a long time, some black oil spots will be formed on the cylinder wall and stained on the cloth surface to form silicone oil spots.
4. Coalescence problem
In the fabric containing short fibers (such as cotton, viscose, velvet type), in the process will inevitably have part of the short fibers fall off, the cloth fall off the short fiber in the rolling trough accumulation, and ordinary silicone oil to produce cohesion, with the finishing fluid up to the roll, and the silicone oil is squeezed to break the emulsion stick together, easy to form a sticky roll or silicone spot. Do a good job of cleaning before driving, and find loose hair to clean up in time.
5. Hand feeling problem
As the market now requires more and more fabric feel, and a variety of fabrics due to different seasons, different customer requirements, need to show a variety of different style requirements, there are requirements for a smooth drape, slippery and lively, fluffy and soft, pure elasticity, etc.. One kind of silicone oil can only reflect one kind of style in general. Therefore, many factories have to use many kinds of silicone oil, which causes confusion in production, and sometimes they cannot find the right silicone oil for customers’ requirements, so they have to give up their business and cause losses. We can choose different ammonia value, different kinds of silicone oil to control the molecular weight and molecular distribution to synthesize ammonia value viscosity and reaction with different silicone oil to meet the requirements of various fibers in terms of softness, smoothness and elasticity.
6. Concentration problem
Can not be more than 20% (solids) high concentration of amino silicone oil emulsion directly into the fabric in operation, should be thinned beforehand amino silicone oil into the container after pouring and stirring, to prevent rapid adsorption, resulting in silicone oil spots.
7. Temperature problem
Use the temperature to 30-40 ℃ is appropriate, generally should not exceed 50-60 ℃. Although the temperature has no obvious effect on the softness and smoothness of the hands, but the temperature is too high, the elasticity changes greatly, and the amino silicone oil is easy to produce sticky rollers and broken milk.
8. PH value problem
When impregnating or dipping working fluid, the PH value should be controlled at about 5.5-6, which is conducive to improving the softness, drapability and elasticity of the fabric feel.
9. Use time problem
Silicone oil emulsion used for too long will produce the phenomenon of sticky rollers, especially the poor quality, and even crust on the rollers, affecting driving. Cleaning should be strengthened, generally available with de-greasing agent or cleaning agent, dissolved in a certain proportion and scrubbed on the roller.
