Plastic molding products often encounter colorant problems
plastic molding part
The type of plastic colorant types , its physical form is divided into four categories: powdered colorants – Toner; paste Colorants – Colorants; liquid colorants; solid-like coloring agent – masterbatch. Among them, the widely used coloring agent is powdered colorants and solid form. Therefore, for the other two kinds of coloring agents in this article will not discuss.Two characteristics of the characteristics of a variety of colorants 2.1 dye coloring the direct use of dye (pigment or dye) to add the appropriate amount of powdered additives for plastic particles coloring method, also known as dry coloring.The advantage of good dispersion, low cost, small batch operations. Because it obviates the other colorants, such as masterbatch, pigment pastes and process of human and material resources consumption, and thus low cost, buyers and sellers are not subject to limits on the amount. Manufacture of masterbatch can not do 1 ~ 2kg, but the toner according to the needs of any given quality, preparation is very convenient. Resin dye coloring, compared with other granulation coloring, processing less experience a degradation process, helps to reduce the aging of the plastic products, and increase their service life.But the biggest drawback is that the paint will be flying in the transportation, storage, weighing, mixing, resulting in pollution, seriously affecting the work environment.
Plastic molding part and environment protect
With the requirements of environmental protection, corporate ISO 9000 indicators, toner coloring more and more restricted, but the special effects coloring, toner directly mixed coloring with some masterbatch coloring not effect. For example, some of the heat resistance, afraid of the cut made of pigment powder masterbatch, due to its exposure to high temperatures for a long time, in the masterbatch processing equipment by the shear stress in a long time, the coloring effect will be significantly weakened, such as pearl toner, phosphor, luminous powder. Made of pearl toner masterbatch and then coloring plastic, pearl powder mixed with coloring plastics, pearl effect is weakened by about 10%, and plastic molding products are also prone to flow linear scars and seams. We manufacture this kind of masterbatch, are to take appropriate measures to minimize the masterbatch heated during processing temperature, time, and by the shear level (without twin-screw granulator, but made with a single screw granulator, etc.).Dry coloring another user headache problem is difficult to clean the hopper of the extruder. The dye used for coloring in the role of white oil and wetting agents, the buildup of the barrel wall (and even screw). When the need refueling, cleaning the barrel became the site operator problems, time consuming and expensive materials, duplication of efforts, the use of masterbatch coloring not have this problem.In addition, the use of dye coloring pigment powder is evenly distributed in the required coloring of the resin, so its a good dispersion, this conclusion is only for plastic injection molding products, especially the thick-walled products for blown film, spinning products is another matter. Because the toner is generally no pre-treatment, when mixed in the resin alone from the extrusion mouth-feed screw to the discharge port so long and so short a plasticizing mixing time, to make pigment powder Molecular and coloring pigment molecules to join hands – fully integrated, and can not guarantee there will be “cooked” phenomenon. But the phenomenon of this “cooked” in a thick-walled products will be masked out obvious blown film, spinning products. Latter coloring method is still masterbatch based.In addition, different due to the manufacturer’s production date, lot number, the toner, the toner of the same brands of the existence of a certain color, even if the user insists on using the same formula, but difficult to achieve in the process from batch to batch between the injection of color consistency, while the masterbatch in the production process by the middle of sampling, testing, adjustment to make up for each batch of toner color, relatively speaking, much better than color masterbatch color repeatability powder.Precisely because the dye used for coloring plastics limitations, by the challenges of other colorants, but the relatively low production costs, fixed color, the color is not the amount of restriction, for SMEs in developing countries, the private sector , in order to participate in the fierce market competition, economic use toner.Of course, the masterbatch coloring has its limitations, add a small, plastic products, processing time is short, limited by the aspect ratio of the extruder screw, masterbatch dispersion often better to dye. Once the manufacturing process, dyeing costs must be higher than the dye coloring. Masterbatch carrier differences with the need of the performance of the colored resin, the surface of the plastic products often not dispersed points, pigmentation, pattern, so the use of masterbatch because of its compatibility and dispersion is limited.3 universal masterbatch and special masterbatch choice precisely because of the masterbatch coloring dye coloring has many advantages, with the development of the plastics processing industry, especially the establishment of many joint ventures and export products for coloring requirements to improve masterbatch coloring gradually dominated the applicability of classification of the masterbatch, it can be divided into universal masterbatch and dedicated masterbatch.
- special masterbatch manufacturing masterbatch, the choice of For the same colored resin resin as a carrier, by adding a high concentration of pigment (dye), the promotional effect of heating, and plasticizing, mixing , extrusion granulation, made specifically for the dye in the resin, known as special masterbatch. Special masterbatch concentration can be high or low, generally add 1% to 4%.
- Universal masterbatch Common masterbatch (some call it the “universal masterbatch”) is the main difference with the special masterbatch: Universal masterbatch is also some kind of resin as the carrier, but it can be applied in addition to its carrier resin other than resin coloring, so called universal masterbatch.The so-called universal masterbatch generally take the following measures (some manufacturing plants simply do not use resin as carrier, while all of propylene with high melting point wax as carrier): At first, a low melting point, the resin of high melt index as a universal masterbatch carrier, such as PE or EVA; masterbatch pigment powder in the ratio as high as possible, so universal masterbatch must be a high concentration masterbatch used in plastic molding products are generally 1%. Different media in the masterbatch carrier is very small (less additives factors, usually in about 20%), when it is diluted in the proportion of 1% For the colored resin contained in the plastics resin content : 0.2kg/100 2g/kg universal masterbatch and other types of pigmented resin (affinity), universal masterbatch also adopted other measures, such as multi-join the special role of coupling agent, to extend the mixing time, which are conducive to improving the broad applicability of the universal masterbatch.
- Select the principle of whether the selection of the masterbatch is appropriate? Whether universal masterbatch most properly? Let us from manufacturing plants, distributors, users as well as economic benefits, convenient or not, the products effects.Must be selected from the manufacturing plant in terms of: in order to produce the universal masterbatch high heat levels, suitable for a wide range of pigments, pigment powder temperature levels to a certain extent, each increase of 10 ℃ ~ 20 ℃, the cost of the pigment but To rise from 50% to 100%. Universal masterbatch made with some high-temperature pigments for the coloring of the high melting point resin is material when its used for LDPE such a low melting point resin, to improve the residual value.Another example: some of the dyes can be applied to the ABS, HIPS, hard plastic coloring, tinting strength and does not migrate, low cost, can be used to make it into the masterbatch can not be used in polyethylene products, because it would seriously migration, universal masterbatch will not be able to choose it as a dye.Universal masterbatch is universal, it should be for the sake of other resins, the use of materials is limited by the cost of production is bound to increase the sale of the use of cost increases, but not absolute, sometimes for some users, but will decline in the cost of using a common masterbatch, This is because the use of specific masterbatch ratio of 1:25, and the use of universal masterbatch 1:100, the 1kg Universal masterbatch capable of reaching the 4kg, the dedicated masterbatch , factory production of masterbatch processing cost of a 5 to 10 yuan per kg (device quality of, Color Masterbatch, Color Masterbatch species, management standards vary). 3kg less share of masterbatch processing costs from the factory for the user to save, so even if the universal masterbatch units sold at higher prices, and reduce the amount converted into per ton of resin coloring fee, rather than using a dedicated masterbatch cheap. Distant dealers and users tend to welcome the universal masterbatch, easy to use is also a factor, in addition to the savings of a few thousand dollars / ton of freight. Orders received by some SMEs, the resin varieties, the production process is a continuous need to replace the resin, the coloring is not very strict requirements, then the purchase of the advantages of universal masterbatch, its broad applicability has fully revealed the In addition, less into some varieties of masterbatch, which reduces inventory levels, and ease of sales; standing in the masterbatch manufacturer’s point of view, under the intense market competition, the lack of orders, hoping to produce some special masterbatch, not only can save the cost of raw materials, and can earn more fees.From the coloring effect analysis: the amount of different resin in the coloring process, the “eat the extent of the color” is not the same, the same add in the resin, the coloring effect is not the same, and sometimes differ considerably. Such as ABS, HIPS, “eat color force” is very powerful, and poor mobility. Universal masterbatch is difficult to achieve the intended effect, in turn, the broad applicability of the universal masterbatch carrier resin and the colored resin incompatibility can be ignored, but not equal to non-existent. Production and use of universal masterbatch unit has a certain pressure, all aspects of the slightest mistake, “hidden” problem becomes “dominant”.In addition to the shading cast as described above, the addition of the ratio of small, scattered relatively poor, the plastic surface is easy to pattern, stain, color point, still to the material and cause crackling phenomena, in particular large area, thin-walled shape complex plastic molding parts but also to attract attention, then, as far as possible, with special masterbatch, and select the low concentration of the masterbatch, in order to increase the dosage to improve its dispersion (optional 1:20 1:10 special masterbatch).Through the above analysis we can see that that the masterbatch and dedicated masterbatch is different, but special masterbatch coloring effects and product performance is still better than the universal masterbatch. We recommend the user to determine the type of resin For coloring, the preferred dedicated masterbatch