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What impact does PP masterbatch have on the quality of polypropylene? Let's take a look!
1. Dispersion of PP masterbatch in polypropylene fiber
The PP masterbatch with various colors is caused by the uniform dispersion of the pigment particles in the PP masterbatch. The key point is that the pigment particles are sufficiently refined and uniformly distributed (mixed) in the polypropylene fiber. The refinement dispersion is to break up the agglomerates or round bodies of the pigment to minimize the particles, and the key lies in the uniform dispersion and the dispersion effect on the brilliance, transparency, gloss, fiber strength, elongation and aging resistance of the pigmented polypropylene fibers. , the rate of electricity, etc. have an impact.
In general, pigments with a particle size of less than 1 um can be used for fibers or ultra-thin films, and more than 5 um will result in a matte surface. If it is larger than 10 um, it will cause spots and streaks on the surface of the fiber, and it will increase with particle size. The breaking strength and elongation of the fiber are continuously decreasing. The finer the particle size, the stronger the coloring power, the better the dispersibility, and the smaller the particle size, the larger the surface, resulting in an increase in hiding power.
Since the pigment particle state has three kinds of primary particles, agglomerates, and round bodies, and the general commercial pigment particles are larger than the round body (about 75-250 um), it must be dispersed. The so-called pigment dispersion is to reunite. The process of body pulverization and refinement.
The dispersion of pigments firstly wets the pigment with a wetting agent, coats the surface of the pigment, reduces the cohesive force between the pigments, reduces the energy required to break the round body of the pigment, and secondly, pulverizes and refines the pigment, leading between the pigment particles. The free motion (impact stress) and the round body of the pigment break the round body particles by the shear stress of the surrounding medium. After the pigment is dispersed and refined, the particle size is reduced, the surface area is increased, and the free energy of the pigment surface is also increased to cause refinement of the pigment. Therefore, the pigment surface is further coated to reduce the newly formed interface surface. It is possible to prevent re-agglomeration, and then the pigment is mixed and dispersed in the melt, that is, the wetted and pulverized pigment is uniformly dispersed and distributed to the material to be colored.
Second, PP masterbatch performance and quality requirements
1, PP masterbatch performance requirements
Polypropylene is a kind of pure hydrocarbon. It contains a tertiary carbon atom in the molecular chain. It is heated. After being exposed to light, the molecule is easily cracked at the tertiary carbon atom, which makes the quality of the polypropylene deteriorate. Therefore, the masterbatch is required to be sintered in high temperature. It is easy to spread, does not damage the fiber quality, does not fade the fiber, has excellent light resistance, abrasion resistance, solvent resistance, and can withstand strict spinning drafting.
(1) The pigment selected for the heat-resistant masterbatch, the most basic requirement can withstand the temperature in the production process of polypropylene fiber, and maintain its performance stable. The temperature resistance temperature is generally required to be 270 to 280 ° C or higher.
(2) The pigment for the dispersible masterbatch is excellent in dispersibility, and is uniformly dispersed in the masterbatch, and the dispersant used does not lower the quality of the polypropylene fiber. Otherwise, it is impossible to produce a good quality colored liquid of the raw liquid, and the operation is also unstable, and it is easy to break or generate abnormal fibers when the fiber is drawn.
(3) Brightness The coloring of the polypropylene stock solution has various uses, among which the bed cover base fabric and the knitted fabric require a bright color tone. Since organic pigments are bright and vivid, and are easily colored, organic pigments are used for the above purposes.
(4) Light resistance Some pigments have a photosensitizing effect under the action of light, which causes the colored fibers to fade and be brittle, and the light resistance of the pigment is basically related to its chemical structure, so it is necessary to pay sufficient attention to the light fastness of the pigment when making the masterbatch. When a light-resistant pigment is used, it is conceivable to add a UV absorber.
(5) The pigment used in the stability masterbatch has excellent stability to the colored polypropylene fiber. That is, when the colored fiber polymer is exposed to heat, light or subjected to high temperature for a long time, the pigment does not react with the fiber, and a new chemical group is formed to degrade the polymer performance. Therefore, the color masterbatch should be selected as pure pigment as possible, free of impurities such as iron, copper, lead and the like, to ensure the physical properties of the colored polypropylene fiber is excellent.
(6) Water resistance, dry cleaning resistance, oil resistance, colored polypropylene fiber products are inevitably washed or solvent dry cleaned in use, and should be exposed to oil, especially when used on carpets, the colorants used must have Good washability, dry cleaning resistance and oil resistance.
2, the quality requirements of polypropylene masterbatch
The quality indicators of masterbatch include more content. For example, the apparent size is generally 2 mm × (3 to 4) mm, and the pigment particle size in the masterbatch is ≤ 1 um, which is 90% or more, melting point, DF value, MI value, heat resistance and weather resistance. These indicators are topics of common concern for masterbatch mills and polypropylene fiber mills.
(1) Filtration performance
The fiber-grade color masterbatch uses the filtration performance to characterize the masterbatch mass. The value is called DF value is small. The replacement period of the filter component in the spinning process is relatively long. Generally, the DF value of the polypropylene masterbatch is less than 2.0×105Pa· Cm2/g.
(2) melting point
The PP masterbatch dispersant uses low molecular weight polyethylene wax, so its melting point is between 110 and 120 ° C. The pigment generally has a high melting point and exceeds the polypropylene spinning temperature. Therefore, the masterbatch has two on the thermal analysis spectrum. Endothermic peak. However, the melting point of the masterbatch cannot indicate the quality of the masterbatch. In some enterprise standards, the melting point is 130-160 °C.
(3) Melt activity index (MI value)
The MI of polypropylene chips is mainly used to characterize the molecular weight and determine the processing and finished product properties after slicing. The masterbatch contains pigment, dispersant and carrier low molecular weight polyethylene wax. Therefore, it is not possible to use MI to determine its molecular weight, and it will change depending on the pigment and variety. Therefore, the MI of the masterbatch is not the masterbatch. Control indicators can only be used for reference during spinning. The MI of the masterbatch for spinning is slightly larger than the original color slice, which is beneficial for the similar particle size and mixing. The general requirement is the MI value (15 to 30) g / 30 min.
(4) Heat resistant masterbatch
The heat resistance index refers to the fact that the masterbatch and the polypropylene chip are spun at a certain ratio at a different temperature for 5 to 10 minutes, and the degree of change in color is observed. The change of color can be evaluated by using a gray sample card or a color sample card for assessing discoloration. When the total color difference ⊿E≤3, the temperature is the heat-resistant temperature of the masterbatch, and generally requires heat resistance of 270-300. °C, the brilliance changes to level 4.
(5) Weatherability The weatherability of the pigmented polypropylene is determined by the test method for the light fastness of the textile. The results are evaluated by the blue standard for assessing the light fastness. The light fastness is required to be 5, and the fact is more than 6 Level 8.
Lu'an Qingsong Masterbatch Co., Ltd. was founded in 2008. After several years of development, it has a number of advanced production lines, various testing equipments, and dozens of experienced staff.
The company specializes in the production of non-woven masterbatch, PP masterbatch and other materials spinning, drawing, BCF and other PP masterbatch, also produces a variety of environmentally friendly masterbatch, functional masterbatch, blown film masterbatch , injection masterbatch, engineering plastic modified masterbatch and enhanced masterbatch, is a very strong masterbatch manufacturer!