Application technology for the flow of coatings, leveling and related additives (2)

(3) organic modified: by introducing organic groups on the side base of the main chain. Such as benzene or alkyl to make changes, through these groups to improve the compatible with the coating system. Benzene-modified polydymodisiloxyne leveling agent also has better heat resistance, in high temperature baking coatings also have a wide range of use. Such as: Deqian's DC56AD is such a leveling agent. The structure of organic modified polymethylsiloxane is as follows: (4) Reactive hydrogenic group modified: modified by connecting reactive hydrometric groups to the side-based access of the main chain, which are essential groups that can be cross-linked with resins or curing agents, such as hydroxyl, ammonia, carboxyl, epoxy, isocyanate, etc. These leveling agents can be cross-linked to the film resin reaction and can be present in the coating film during the curing process. General modified polysilicae leveling agents migrate to the surface of the coating film during the curing process to form a very thin single molecular layer. Make its surface stress consistent to form a smooth coating film, but over time, if this layer of single molecule layer is worn, then the leveling agent will fail, which is also some coating surface over time. The reason why the feel will get worse and worse. The polydymethylene silica leveling agent with reactive errands will not produce the above phenomenon. This class of leveling agents are: BYK 1370, 371:EFKA 186: Deqian 435, PA,30, PA.31.structure is as follows: 2. 3 Polyacrylate leveling agentsthe composition of such leveling agents is some polyacrylate co-polymers or ionizers. The ideal polyacrylate leveling agent should have a narrow relative molecular mass distribution, lower surface tensor, lower glassing temperature, appropriate relative molecular mass, and limited compatible with film-forming resins, so that it can be partially migrated to the coating surface with lower surface tensor pressure and incomplete mixing than coatings. The formation of a single-molecule film on the wet film surface, weakening the surface flow, promoting the coating surface pressure homogenization, inhibiting the speed of solvent volatilization, giving the wet film more run-flat time, thus playing a role in reducing or eliminating orange brush marks, roller marks, floating color, hair flowers and other surface defects, so that the coating film flat and smooth. The compatible between polyacrylate leveling agent and film-forming material is very important, and if the compatible is too good, it will not form a single molecular layer on the coating surface and affect the leveling effect. However, poor compatible leveling agent will lead to film fog, gloss reduction, loss of light and other undesirable phenomena. Acrylic polymers are less soluble than some resins. So use acrylic co-polymers. By using different acrylic monomers to participate in co-fusion to regulate its solubility with the coating and glacification humidity to maintain good fluidity at room temperature.
, polyacrylate leveling agents are relatively safe compared with modified polymethylsiloxane leveling agents. Even if you add too much, it doesn't affect recoating and layering adhesion. With the increase of dosing, the surface tension decreases, the shrink hole decreases, the gloss and freshness increase, but the dosing continues to increase but does not help to further improve the leveling. On the contrary, there are side effects. Such as paint film fog, loss of light, etc. In addition, the amount of leveling agent is related to the type of film resin, for different resins its dosage is different, usually the maximum dosage does not exceed 2% of the total amount of paint. Therefore, the optimal dosage of the leveling agent is best determined by testing.. Polyacrylate leveling agents can be used in solvent-based coatings, water-based coatings and powder coatings. According to reactive polypropyleneate can be divided into non -reactive and reactive two types. Water-based coatings generally use non-reactive. Solvent-based coatings and powder coatings are non-reactive and reactive. However, at present, more non-reactive varieties of leveling agents are used in China.domestic and foreign companies have polyacrylate leveling agents such products. Such as: CYTEC Cyant acrylic co-polymer or modified varieties MODAFLOW 2100, 9200. MODA van oW-RESIN. ADDITOL XL 425, 480, 490 leveling agents; BYK's BYK 352, 354, 357, 358, etc. TEGO's Tego flow300; CIBA's EFKA I 3778, EFKA-S022, etc.; Deqian's 491, 495, 835, 896, etc.
other than polyacrylate leveling agents. Butyric acid cellulose (e.g. EASTMAN CAB) is also a linear resin leveling agent with limited compatible capacity. CAB has many kinds, including different butyl, acetyl and hydroxyl content, so its performance varies greatly, with medium butyl content (e.g. CAB-381) mixed with a variety of resins and also in a variety of plasticizers. It is used in many coatings, including automotive paint, wood paint, plastic and rubber paint, glass coatings, fabric coatings, etc. It can also be used as a medium for dispersing pigments on a double roller grinder. CAB is stable against ultraviolet light and does not react with dyes, fluorescent pigments, or metallic pigments. EASTMAN's CAB-551 is the highest content of cellulose butyl, mainly used in cross-link coatings, in order to shorten finger drying time, reduce shrink holes, increase leveling, provide better pigment dispersion, improve layer adhesion and improve coating performance. As a leveling agent, the higher the butyl content, the better the leveling effect. Butyl content of 35% can be used as polyurethane coating leveling agent, butyl content of 55% can be used as epoxy powder coating leveling agent.. New advances in 3 leveling agents - Fluorocarbon polymers and fluorocarbon modified polymersfluorocarbon additives have high surf activity. High thermal stability, high chemical stability and water and oil repugnence properties. Because the vulvar gravity between the fluorocarbon chains is much lower than the corresponding hydrocarbon chain. As a result, it exhibits strong surf activity on both water and organic solvent media. Such as a small amount of fluorocarbon additives can reduce the surface pressure of water from 73mN/m to 15mN/m, so that benzene, toluene surface pressure from 28mN/m to 1lmN/m, its solution critical beam (CMC) concentration is very low. Up to 10-5 to 10-6mol/L, which greatly reduces its dosing. Sometimes even a few tens of milligrams can produce high surf activity.addition of a small amount of fluorocarbon additives to the coating can improve the smoothness of the coating and increase the finish of the coating. Experiments show that fluorocarbon additives are more effective in coatings than polydymerylsiloxane leveling agents. As mentioned earlier, fish eyes, pinholes, orange peels and other phenomena often appear with silicone-containing coatings, while fluorocarbon additives are not used. The addition of fluorocarbon additives to the coating can improve the wetting and leveling of the coating and prevent cracking, foaming and wrinkled skins.two problems in promoting the use of fluorocarbon additives. First, synthetic fluorocarbon additives are technically difficult, so the price is relatively high, the general customer is difficult to accept; Despite the high cost of fluorocarbon additives, a large number of additives must be added because of the small amount they add and the fact that some properties are not able with silicon or hydrocarbon additives. Therefore, in recent years at home and abroad some professional companies have introduced coatings, inks, adhesives and other applications of some fluorocarbon additives or fluorocarbon modified polymer additives. Its main varieties are as follows: FC-4430 and 4432 fluorocarbon additives (FC-430 replacement varieties) introduced by 3M Corporation of the United States, which is a non-ion polymerized fluorine-containing additive. Almost 100% fluoride adipose polymer esters act as coating aids to achieve very low surface stress in coatings. Fluorocarbon additives for water-based and solvent-based coatings reduce surface stress to about 20dynes/cm, hydrocarbon additives reduce surface stress to about 30dynes/cm, and silicone additives reduce surface stress to about 25dynes/cm. FC-4430 and FC1432 can be used as excellent wetting and leveling agents in water-based, solvent-based and high-solid coatings. The physical properties of FC1430 fluorocarbon additives are shown in Table 1.. EFKA I3600 and EFKA I3650 are very effective fluorocarbon polymer leveling agents that reduce the surface pressure of solvent-based coatings and are resistant to shrinking holes and surface flow control. The EFKA 3500 is a good aid for water-based coatings to reduce surface stress and leveling and wetting of substrates.
fluorocarbon modified polymer leveling agent, especially fluorocarbon modified polyacrylate leveling agent in baking coatings, especially coiled steel coatings, polyurethane coatings, as well as automotive original paint, repair paint coatings, etc. have been widely used. These varieties, such as EFKA 3777, 3277, 3772 and 3570, all belong to this type, and AFCONA has the same products. CYTEC's ADITOL VXL6230 and VXW6396. Taiwan Deqian (Shanghai) chemical 837 and so on belong to fluorocarbon modified polyacrylate leveling agent. Their application in coatings has shown good performance.EFKA 3034, a fluorocarbon-modified polysiloxyane leveling agent used in water-based and solvent-based coatings. It has a very strong ability to reduce surface pressure. The wetting function of the substrate is excellent, which can prevent the paint from floating, flowering and promoting the leveling.
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