The working principle and application of finishing agent

The working principle and application of finishing agent
1. Overview
Fabric finishing is the application of a finishing agent on the fabric, which can change the surface properties of the fabric, thus giving the fabric a special function. For example, hydrophobic and oleophobic finishing is a finishing agent with low surface tension to treat the fabric, change the surface characteristics of the fiber, so that the fabric surface is not easy to be wet and spread by water or oil, so as to achieve the purpose of hydrophobic and oleophobic. Antifouling finish and easy decontamination finish is a processing technology that changes the surface performance or surface state of the fiber, so that the fabric is not easy to adhere to dirt under wearing and using conditions, or the dirt that has been attached is easy to wash and no longer stains.
2. How it works
Commonly used are latex, waterborne polyurethane, polyacrylate, polyethylene and other polymer. Among these coating agents, the development of polyacrylates and waterborne polyurethane resins is particularly significant in recent years. Polyacrylate is the copolymerization of different acrylate monomers, which can have different physical and mechanical properties due to the different raw materials used in the monomers. Waterborne polyurethane (WPU) is prepared by addition polymerization of a compound containing diisocyanate group with polyols or other compounds containing active hydrogen, and there is no by-product in the reaction.
In order to improve the performance of the waterborne polyurethane coating, a sealer can be added in the preparation process to make the sealer react with part of the isocyanate group in the prepolymer to form an aminoester bond, and the aminoester bond reacts with the hydroxyl group on the fabric to form polyurethane under the condition of heating, thus increasing the binding force between the polyurethane coating and the fabric. Waterproof and moisture permeable polyurethane films and coatings have become one of the focuses of researchers because they are both waterproof and breathable.
Step 3: Application
Fabrics for a long time to use or after washing, there will be wrinkles, fuzziness and other phenomena, most untreated fabrics poor waterproof and moisture permeability, wear up can not bring a good comfortable experience, through the textile finishing agent can solve these problems. Textile coating finishing agent is a polymer compound uniformly coated on the surface of the fabric, it forms a layer or multiple layers of film on the surface of the fabric through bonding, which can improve the appearance of the fabric, increase the fabric style such as waterproof, moisture permeability, flame retardant, anti-ultraviolet and other special functions, and open up new uses of textiles.
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(1) cationic hydroxyl silicone oil emulsion
The emulsifier used in acionized hydroxyl emulsion polymerization is usually quaternary amine salt (octadecyl trimethyl ammonium chloride is reported in foreign literature), and the catalyst is ammonium hydroxide. The cationic hydroxyl emulsion can be used for finishing all kinds of textiles, which has the properties of improving fabric feel, improving fabric elasticity, smoothness and crispness. Another unique advantage is that it is an ideal waterproof agent for fabrics, and is used with methyl hydrogen-containing silicone oil emulsion, waterproof performance and waterproof durability can reach a very high level, and can be used as a waterproof agent for vinylon cover canvas, and waterproof for polyester cloth.
(2) anionic hydroxyl silicone oil emulsion
The anionic hydroxyl milk is characterized by good compatibility in fabric finishing agents, and the emulsion is very stable. In particular, most of the auxiliaries in textile printing and dyeing are anionic, if the cationic hydroxyl milk is used, it is often easy to cause emulsion breaking and bleaching oil, and the anionic hydroxyl milk can avoid this problem, so it is more popular with users and is widely used.
(3) Complex ionic hydroxyl silicone oil emulsion
Although cationic hydroxyl emulsion is an excellent fabric finishing agent, it is not resistant to hard water and can not be used in the same bath with dimethyl-dihydroxy-ethylene urea resin (2D), catalyst magnesium chloride and anionic whitening agent, so it has certain limitations in use. In addition, due to the poor stability of the emulsion, the silicone polymer is easy to separate from the emulsion and float on the liquid surface, commonly known as "floating oil". If the cationic emulsifier and non-ionic emulsifier are used in the process of emulsion polymerization, the shortcomings of the preparation of hydroxy-silicone oil emulsion can be overcome. The silicone emulsion can withstand hard water, and can be used in the same bath as 2D resin, magnesium chloride and whitening agent VBL, and has good heat resistance and freezing resistance.
(4) Non-ionic hydroxyl silicone oil emulsion
Non-ionic hydroxyl milk has stronger adaptability and better stability than detached hydroxyl milk, so many countries have vigorously studied non-ionic hydroxyl milk. For example, the new UltrateX FSA produced by Ciba Jiaki company in Switzerland is a non-ionic emulsion with a molecular weight of more than 200,000 hydroxyl head polydimethylsiloxane, which is a step forward from the Dc-1111 anionic hydroxyl milk of Tao Corning Company in the United States.
(5) Silicone finishing agents of other active groups
In order to meet the needs of advanced finishing of all kinds of fabrics, improve the anti-oil, anti-static and hydrophilic properties of organosilicon finished fabrics, and make chemical fiber fabrics have many advantages of natural fabrics, organosilicon workers have studied the introduction of other active groups such as amino, amide, ester, cyanide, carboxyl, epoxy and so on. The introduction of these groups makes the silicone fabric finishing agent have special effects. For example, the introduction of amino groups into silicone molecules is suitable for anti-shrinkage and soft finishing of woolen fabrics; The introduction of amide group is suitable for anti-fouling finishing, and the softness is greatly improved. The introduction of cyanide group has good oil resistance, and the copolymer of polyoxyethylene ether and organosilicon has good anti-static effect. The organofluorine-modified silicone has many advantages such as oil repellent, antifouling, antistatic and water repellent.