What is the production process of polypropylene colored filament?

There are mainly two production methods for polypropylene colored filaments, namely the masterbatch addition method and the dyeing method. Their production processes are different. The following is a detailed introduction:

Masterbatch addition method

Raw material preparation: Select high-purity polypropylene chips as the basic raw material and choose the corresponding color masterbatch according to the required color. Masterbatch is a granular product made from pigments, carrier resins and additives through special processing, featuring excellent dispersibility and tinting strength.

Mixing: Add polypropylene chips and color masterbatches in a certain proportion to the mixing equipment, and ensure thorough and uniform mixing through stirring or vibration, etc. The determination of the proportion needs to be precisely calculated based on the depth of the target color and the coloring intensity of the color masterbatch to ensure that the final product achieves the desired color effect.

Melt extrusion: The well-mixed raw materials are fed into a screw extruder, where polypropylene chips and masterbatches are melted into a uniform melt at high temperatures (generally 160-220 ℃). The rotation of the screw pushes the melt forward and extrudes it through the spinneret at the die head of the extruder, forming a filamentous fluid.

Spinning forming: The filamentous melt extruded from the spinneret rapidly cools and solidifies in the air to form primary fibers. During the cooling process, the molecular structure of the fibers gradually orientations and crystallizes, endowing the fibers with certain strength and physical properties. Meanwhile, by controlling parameters such as spinning speed and cooling conditions, the fineness and performance of the fibers can be adjusted.

Stretching: The strength of primary fibers is relatively low, and a stretching process is needed to enhance their strength and orientation. The spun fibers are stretched through multiple stretching rollers, with the stretching ratio generally ranging from 3 to 10 times. During the stretching process, the molecular chains in the fibers are arranged more neatly along the fiber axis, and the crystallinity is increased, thereby significantly enhancing the strength, wear resistance and other properties of the fibers.

Heat setting: After stretching, the fibers undergo heat setting treatment at a certain temperature (usually 120-150 ℃) to eliminate internal stress within the fibers and stabilize their size and structure. Heat setting can be achieved through methods such as hot air circulation and steam heating, keeping the fibers in a heated state for a certain period of time, and then slowly cooling them to room temperature.

Winding: After heat setting, the polypropylene colored filament meets the final product performance requirements. It is wound into a certain specification of filament drum or filament cake through winding equipment, which is convenient for storage, transportation and subsequent processing.

Dyeing method

Spinning: Firstly, polypropylene raw materials are processed through melt spinning to produce polypropylene filaments. This process is similar to the melt extrusion and spinning forming steps in the masterbatch addition method, resulting in white or light-colored polypropylene primary fibers. Then, through stretching and other treatments, they are given certain strength and physical properties.

Pretreatment: To enhance the dyeing performance of the fibers, polypropylene filaments need to be pretreated before dyeing. Usually, methods such as alkali reduction treatment or plasma treatment are adopted to remove oils, impurities and other substances on the surface of the fibers, and to modify the surface of the fibers to increase their hydrophilicity and surface activity, so that dyes can better adsorb and diffuse into the interior of the fibers.

Dyeing: After the pretreatment, the polypropylene filament is placed in a dyeing VAT, and an appropriate amount of dye, auxiliaries and water are added. The dyeing is carried out through methods such as immersion dyeing, pad dyeing or high-temperature and high-pressure dyeing. During the dyeing process, it is necessary to strictly control parameters such as dyeing temperature, time and pH value to ensure that the dye is evenly adsorbed on the fibers and achieves the required color depth and color fastness. For instance, for some dark-colored varieties, dyeing may be required at a higher temperature (120-130 ℃) and for a longer period of time (30-60 minutes).

Post-treatment: After dyeing, the polypropylene filament undergoes post-treatment processes such as water washing and soap washing to remove excess dyes and auxiliaries on the fiber surface, thereby enhancing color fastness and brightness. Then, drying treatment is carried out to make the fibers reach a certain moisture content for subsequent processing and use.

Finishing: Depending on the final use of the product, it may be necessary to carry out some finishing processing on the dyed polypropylene colored filament, such as adding softeners, antistatic agents, etc., to improve the hand feel and performance of the fiber. Finally, the polypropylene colored filaments are made into finished products through processes such as winding.

Ningbo Dazhong Chemical Fiber Industry Co., Ltd. has been engaged in the long-term production and operation of: polypropylene filament, polypropylene filament, polypropylene FDY filament, polyester staple fiber, polypropylene fully drawn filament, polypropylene POY filament, and polyester POY filament.

Ningbo Dazhong Chemical Fiber Industry Co., Ltd. has an annual production capacity of 15,000 tons of polypropylene filament, polypropylene POY filament, polypropylene common strength filament and polypropylene FDY filament in various colors ranging from 68 to 1800D, and 120,000 tons of melt direct-spun polyester staple fiber annually. The products include 1.2D to 15D silicon-containing, silicon-free and down imitation staple fiber products. The annual output of melt direct-spun polyester POY filament is 100,000 tons.