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Application Of Pearlescent Pigments In Plastic Blow Molding
- Jul 18, 2018 -

Application of pearlescent pigments in plastic blow molding


Pearlescent pigment is chemically stable and nonmetallic, and its safety is guaranteed. Therefore, it is widely used in the processing of clinker, such as artificial leather, wallpaper, plastic packaging film, cosmetics, shampoo packaging, household appliances and plastic parts, artificial pearls, plastic buttons and other plastic products, which are widely used to increase the attractiveness of pearlescent pigments. Pearlescent pigment can be applied to almost all thermoplastics and a part of thermosetting plastics. The concentration of pearlescent pigment used in plastics depends on different application conditions. But generally it is 6 per thousand -2% (weight of resin), which has achieved satisfactory pearlescent effect. For some film products, the concentration of 4%-5% pearlescent pigment should be used. In addition, some of the lower transparent plastic should also use higher pearlescent pigment or larger diameter to highlight the effect.


1. Selection of materials


Because pearlescent pigment itself is translucent, it needs to rely on external light reflection to achieve good pearlescent effect. So when choosing plastic, try to use better transparent materials, and the following are more transparent and commonly used plastics, such as polyethylene HDPE, LDPE, polypropylene PP, modified polyethylene EVA, acrylate PMMA, saturated polyester PET, polycarbonate PC, polyvinyl chloride PVC, unsaturated polyester AK, epoxy resin EP. T, polyurethane PU. Low transparency or opaque plastics such as GPPS, HIPS, ABS and so on. These pearlescent effects are not obvious, but they do not mean that pearlescent pigments can not be used. In terms of the selection of mixed pigments, pearlite pigments can not be mixed with conventional opaque pigments such as chromium, cadmium and titanium dioxide. The addition of ordinary metal pigments and ordinary iron oxide pigments will reduce its pearlite effect.


2. Extrusion molding


The extrusion molding is mainly used to produce continuous sections. Such as plastic pipe, rod, wire, cable coating and plastic profile. A lot of cleansing milk, hand cream, styling gel beads packaging hose. It is made by this method. Hollow blow molding is the most widely used and more important field of pearlescent pigment at present. Pearlescent pigments are usually limited to the outer decorative layer of composite membrane when used for extrusion. The thickness of the coloring layer of pearlescent pigment is thinner than that of ordinary extrusion, and the amount of pearlite pigment should be increased in a proper amount, generally 1%-3%. The actual dosage is determined by the thickness of the outer membrane, and the thinner the thinner the amount is. Its processing process is based on general processing conditions, and the pigment lamellae are fixed when squeezing out. This orientation is not affected by the surface defects, the die and the processing equipment. The ideal pearlite effect can be obtained by carefully adjusting the parameters of the process. The pearlescent pigment and the resin can be mixed uniformly in extrusion molding, the extruder extrusion hose is put into the extruder, and the pearlescent color parent can be used to mix the resin raw material in the required proportion. To produce.



3, casting film

There are many methods of producing thin film. In the extruder, cylindrical film can be produced by blow molding with round head, and flake thin film can be produced by T type head with casting. Recently, double or multilayer tubular film is more popular. The demand for pearly film in packaging is increasing, no matter for PET, PVC, PE. PP has a good effect, but pearlescent pigment has certain requirements for film production. The thickness of the thin film is generally very thin, which is easy to be transparent or translucent. It is necessary to add a suitable amount of opaque pigment and titanium dioxide to achieve a certain coverage. In principle, we should avoid adding the above pigment to avoid affecting the pearlescent effect. There seems to be some contradiction. In fact, when the pearlite film is produced, a certain amount of titanium white powder is often used in combination with pearlescent pigment to make up the inadequacy of the thickness of the film. And because the thickness of the film is very thin, the pearlite lamellar crystal is easy to be arranged and neatly arranged, and the pearlite concentration should be increased correspondingly, about 4%-5%, in a word. When producing pearlescent film, we must consider the covering rate and the requirement of pearlescent effect. It is best to use a double layer blowing machine to produce pearlescent film. Pearlescent pigments on the upper layer and ordinary opaque pigments on the lower layer. Thus, pearlite films with ideal effect can be produced without increasing the concentration of pearlescent pigment.


4. Blow molding


It is commonly used in all kinds of plastic bottles, such as shampoo, conditioner, cosmetics, liquid soap bottles, etc. Pearlescent pigment can be directly mixed with resin for blow molding. The general usage is between 1%-3% and the thickness of the bottle wall is adjusted. Double layer or multi-layer blow molding can be used to produce hollow products with double wall products. The bottle wall is double-layer, the outer layer contains pearlite, the inner layer is ordinary plastic, and the cost can be saved.


5. Injection molding


Injection molded products account for 20%-30% of the processing capacity of plastic products. They can form various complex products. With the development of injection molding technology and machinery. The scope of injection molding products has expanded from civil to more areas. The application of pearlescent pigments in injection molding is also developed from various container jewelry and daily necessities to refrigerators, air conditioners, and automotive decorative parts. In recent years, back injection molding technology has been used by some manufacturers at home and abroad. The pearlite decorative film is used to produce large refrigerators, air conditioners and so on, even for automobiles and interior and exterior ornaments, which have successfully replaced many metal parts, and the effect is satisfactory.


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