• The formation factor of water-borne coating
    The formation factor of water-borne coating

    2018-01-29

    With the progress of water-based resin technology, water-based paint technology has been recognized by more and more industries and applications. In promoting environmental protection at the same time, water-based paint its special hydrophilic structure may also lead to premature failure of the coating. We usually attribute the cause of failure to resin performance defects, while ignoring the water-based paint and the bonding between the substrate. The binding force can be understood as a good connection between the coating and the substrate. The experimenter has obtained the connection between the coating and the substrate by various methods, but the coating does not completely wet the substrate to form a solid-liquid interface Before the discussion of mechanical anchoring, van der Waals force or chemical bond and other factors will become unrealistic. Therefore, "wetting spread" has become a prerequisite for the combination of factors. In everyday applications, it is generally believed that relatively rough substrates are more conducive to the formation of binding forces. Theoretically, the surface of the rough substrate has a larger surface area than the flat substrate, and when the substrate is wetted with the coating, the air is removed and both have a larger contact area to obtain the bonding force. However, for waterborne coatings, the surface tension of 40-50 dyn / cm is higher than that of most substrates, and the contact area of the aqueous coating with the substrate is often reduced due to the inability to wetting, resulting in loss of the binding force. For example, Figure 1 shows that the formation of liquid-solid interface is conducive to the formation of binding force. The water-based coating is in contact with the substrate. The gas-solid interface SG and the gas-liquid interface SL are replaced by the liquid-solid interface SG. The coating and the substrate begin to establish a part of the connection relationship. When this phenomenon is rapidly diffused to a certain extent, Into the drying curing stage, and finally complete the mechanical anchoring or chemical reaction. The angle of contact is related to the surface tension of the substrate and the coating. The angle is directly related to the degree of wetting and spreading of the aqueous coating to the substrate. When the contact angle θ> 90, it is considered that no wetting occurs, and the contact angle θ <90, the paint can quickly spread and penetrate the pores. When the ideal liquid-solid interface is formed, the increase of the contact area between the coating and the substrate must promote the formation of the binding force. However, due to the surface pressure difference, the complete wetting may only be achieved in large pore size pores, and for pores with small pore size, the wetting process becomes rather slow and tends to complete wetting before curing. When the tiny pores are sufficiently dense, a thin layer of air film is formed between the surface of the non...

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  • Classification and quality requirements of BOPP sealing tape (including ordinary sealing tape, printing tape, high-viscosity antifreeze tape)
    Classification and quality requirements of BOPP sealing tape (including ordinary sealing tape, printing tape, high-viscosity antifreeze tape)

    2018-01-16

    Classification and quality requirements of BOPP sealing tape (including ordinary sealing tape, printing tape, high-viscosity antifreeze tape):The series of products mainly to polypropylene film, special polypropylene film, acrylic and water-based acrylic plastic as raw materials and has the characteristics of posting smooth. It is suitable for general packaging and fixed and packaging and fixed in ultra-low temperature environment. Widely used in the packaging of food, beverages and packaging business product in supermarkets, professional image packaging of quality and gifts, the closure in developed countries or environmental control areas.

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  • The main factors affecting the curing of paint
    The main factors affecting the curing of paint

    2018-01-08

    Factors affecting the curing speed are the main types of paint, coating thickness, curing methods, curing conditions, curing equipment and specific curing procedures. 1.The type of paint Under the same curing conditions, the type of paint is different, the curing speed is very different. Generally speaking, the volatile paint curing fast, oily paint curing is slow. Polymeric paint is very different. Polymeric paint in the light-cured paint the fastest curing, and other polymer-based paint is more than between the volatile paint and oily paint. When use mechanized lines for finishing, the volatile paint, acid-cured amino acid alkyd paint is more commonly used. 2.Coating thickness In the coating process, the coating is basically not formed once, usually using many times thin coating method (such as oil paint generally coated about 35μm, nitro paint 15μm, etc.). Under the same curing conditions, the thin coating in the curing, the internal stress is small, the formation of less coating defects; and the coating is too thick, the internal stress is large, easy to produce wrinkles and other defects, and because of solvent evaporation , Coating shrinkage, resulting in uneven gloss, the internal non-curing and so on.    Practice has proved that, in addition to polyester paint, the other paint through the formation of multiple paint film, and a coating formed by the same thickness of the film compared to its physical properties is better. 3.Curing conditions 1)The curing temperature plays a decisive role in the curing rate of most coating coatings. When the curing temperature is too low, the solvent evaporation and chemical reaction is slow, the coating is difficult to cure. Improve the temperature, can accelerate the evaporation of solvents and water evaporation, accelerated coating oxidation and thermal chemical reaction, coating curing speed. It cannot increase the temperature indefinitely, because the temperature and curing speed is not directly proportional relationship. Curing temperature is too high, the curing speed is not significantly improved, but will make the film yellow or darker color. Not only that, the temperature in the coating curing process also has an impact on the substrate.  Such as substrate heat, causing moisture content changes, the substrate shrinkage deformation, and even warping, cracking. Volatile paint coating, curing temperature exceeds 60 ℃, the solvent is volatile, the surface quickly dry, the internal solvent vapor to reach the surface when prone to bubbles. Therefore, the use of artificial curing method, the surface temperature is generally not more than 60 ℃. 2)Air humidity should be appropriate The temperature is too high, the evaporation rate of the water in the coating decreases, the solvent evaporation rate slows down, which will slow down the curing speed of the coating. Most of the coating in the relative humidity of 45% to 60% of the air curing is most suitable. If the drying and curing sites are ...

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  • Water-based wood paint recipe composition
    Water-based wood paint recipe composition

    2017-12-28

    Water-based wood paint is a dispersion of water and diluent paint, and commonly used solvent-based paint is different from the formula system is a more complex system. Formulation design, not only to pay attention to the type of polymer, emulsion and dispersion properties, but also a reasonable choice of various additives and taking into account the interaction between the various components of a reasonable match. Sometimes for the special requirements of the selection of some special additives, and ultimately become the appropriate formula. The basic composition of waterborne wood paint is as follows: 1. Tater Water as the main solvent, uphold the concept of environmental protection. 2. The emulsion This is the base material for film formation, which determines the main properties of the film. 3. Film forming aids After the water is volatilized, the emulsion is formed into a uniform and dense film, and the film-forming property at a low temperature is improved. 4. Suds suppressors and defoamers Inhibit the bubble of the paint generated during the production process, and can eliminate the bubble has been generated. 5. Leveling agent The paint to provide a good flow leveling, improve the performance of the paint to form a smooth coating. 6. Wetting agent Improve the wetting performance of the paint on the substrate, improve leveling, increase the adhesion of the film on the substrate. 7. Dispersant Promote the dispersion of pigments and fillers in paint. 8. Thickener Increase the viscosity of the paint and improve the thickness of a coating wet film, and putty and solid paint with anti-precipitation and anti-stratification effect. 9. Antiseptic fungicide Prevent the mold in the storage process mildew. 10.Essence So that the paint has a pleasant smell 11.Colorant It is mainly for color paint, making the water-based paint with the desired color. The colorants include pigments and dyes. Pigments are used for solid coloring (no painting of wood grain), and dyes are used for transparent paint (showing the painting of wood grain). 12.Filler It is mainly used for putty and solid paint, increase the solid. 13.PH adjusters Adjust the pH value of the lacquer solution, so that the lacquer solution is stable 14.Wax emulsion or wax powder Improve the scratch resistance of the paint film and improve its feel. 15.Special additives In addition to the special requirements of water-based paint additives, such as rust inhibitors (tin packaging to prevent premature rust), hardening agent (to improve the film hardness), matting agent (reduce paint luster), anti- (To improve the overall performance), hydrophobic agent (so that the coating has a lotus effect), anti-adhesion agent (to prevent coating adhesion), cross-linking agent (made of two-component paint, improve overall performance) , Wear agent (to increase the wear resistance of the coating), UV absorber (outdoor paint anti-aging, to prevent yellowing) and so on.

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