The Key Technologies and Development Trends of Cable Masterbatches
A color masterbatch, also known as a pigment concentrate or a pigment preparation, is a color particle prepared by grinding or extruding a super-constant amount of pigment (proportion 20-80%) into the resin matrix. It is used to color plastics during the manufacturing process. It has the advantages of less addition, stable color, no dust, no pollution, energy saving, easy automatic measurement and transportation, etc. And it is widely used in the coloring process of plastic products.
However, for cable masterbatches with high coloring requirements and large quantities, what is the difference between them and ordinary masterbatches? What are the key technologies worth paying attention to? What is its development trend?
Various Classifications of Color Masterbatches
Depending on the type of pigment, masterbatches are generally classified as white, black and colored. Masterbatches are generally standard-sized particles. Depending on the application, masterbatches can come in various forms, including liquids, granules, beads, and powders. According to the different carriers, masterbatches can be divided into PE masterbatches, PP masterbatches, ABS masterbatches, PVC masterbatches, etc. According to the different uses, masterbatches can also be divided into masterbatches for injection molding, masterbatches for blow molding, masterbatches for extrusion, masterbatches for spinning, etc.
What is the Development Status of Color Masterbatch Technology?
The main raw materials of masterbatches are pigments, dispersants, carrier resins, and stabilizing additives.
Masterbatches are pigment-based, and the quality of pigments determines the grade of masterbatch quality. The masterbatch is developing towards the direction of a high concentration of pigments. The higher the pigment content in the masterbatch, the more difficult it is for the pigment to disperse, so the higher the requirements for the pigment. Pigments for high-concentration masterbatches are pretreated, and dispersants are added. High-concentration masterbatches can be prepared dryly. Pigments are divided into two categories: inorganic and organic. Inorganic pigments are usually metal oxides, sulfides, chromates, molybdenum acids, and other salts, as well as carbon black and titanium dioxide. Organic pigments are colored organic substances.
Dispersants play a role in wetting and coating pigments in the preparation of masterbatches, assisting pigments in good dispersion and distribution in the carrier, and stabilizing pigments. Low molecular weight polyethylene waxes are commonly used in the dispersion process of masterbatch pigments, and micronized waxes are now widely used.
The carrier resin is an important part of the masterbatch. Its role is to enhance the affinity between the pigment and the resin to be colored, and improve the dispersion and mixing of the coloring component and the resin. Intuitively speaking, it is to process the non-sticky and ductile pigments into balls, discs, and cylindrical particles of basically the same size.
Additives such as heat stabilizers, antioxidants, lubricants, light stabilizers, and ultraviolet absorbers must pass through the high temperature, high pressure, and high shear of the internal mixer and screw extruder in the production of masterbatches. Therefore, these additives are used to ensure that the constituent materials of the masterbatches are not subject to high-temperature heat oxygen aging. Although the amount used is small, it is indeed an essential additive to ensure the quality of the masterbatches and the stability and reliability of the overall performance of colored plastic products.
What Are Masterbatches for Cables?
Masterbatches have many applications in plastic products such as packaging materials, automobiles, cables, building materials, home appliances, and films. Among them, the wire and cable industry has high requirements for masterbatch coloring and the amount used is large. Its development has played an important role in promoting the development of the masterbatch industry.
Special masterbatches for wires and cables can be used in the plastic insulation and sheath of various wires and cables such as power cables, communication cables, network cables, signal lines, telephone lines, data lines, etc. They also meet many standards, including RAL (RAL Color Chart), IEC (International Electrotechnical Commission), BS (British Standards Institution), AFNOR (French Standards Association), etc. and so on.
What Are the Characteristics of High-quality Masterbatches for Wires and Cables?
According to the characteristics of the application and the molding process, the requirements of wires and cables for masterbatches are as follows:
l Color - The standard color and error value of various cables in the wire and cable industry must comply with certain standards, which is a very important indicator.
l Electrical Properties - To ensure the safe and normal use of wires and cables, the masterbatches used needs to maintain the electrical conductivity of the plastic coating materials.
l Heat Resistance - When the masterbatch for the wire and cable is used in the molding process, it must have good temperature resistance without discoloration. It must pass the temperature resistance test and the temperature and environment test of the actual application. According to the difference of resins used, for example, the temperature applied to PVC resin is lower, and the temperature applied to HDPE and LDPE resin is higher. Generally, the temperature resistance needs to reach 170-220℃.
l Dispersibility - The insulating layer of the wire and cable is very thin, the extrusion speed is very fast, and the quality requirement is high, so the dispersibility requirement of the masterbatch is also very high. If the masterbatch is not well dispersed in the extruded insulating layer, there will be colored spots, and it will cause sparks when used, which will be a big security risk.
l Impurity Content - If the masterbatch for the wire and cable contains some salts and metal particles, it may cause the breakdown of the wire and cable when used after making the wire and cable. Therefore, it is necessary to control these impurities, especially conductive impurities.
l Migration Resistance - Good migration resistance makes the colors between the made wires and cables will not migrate and stain each other. It will not reduce the recognition of wires and cables due to color problems. Of course, it will not cause trouble with the installation and use.
l Safety - Heavy metals, halogens, and other chemical components in masterbatches for wires and cables are controlled in limited quantities, especially in electrical and electronic applications.
How Are Masterbatches Produced?
In general, the production of masterbatches follows the following process:
1. To identify and weigh pigments and additives, the pre-mixing process is generally carried out in a mixer;
2. These pigments and additives (masterbatches) are then mixed into the carrier resin or polymer by heat treatment and the usual twin screw extrusion;
3. After cooling, the concentrated mixture is made into the final particles, powders, and other masterbatch carriers.
Development Trends
China has become the largest producer and demand country for masterbatches in Asia and will also become the fastest-growing market in terms of demand for masterbatches. In recent years, China has invested heavily in renovating rural and urban power grids. The focus of power construction will shift from the construction of power stations to the construction of power grids, and the power supply structure will be transformed and optimized. In addition, China will simultaneously accelerate the transformation of urban networks to promote electricity consumption. Coupled with the demand for overhead cables, it will also drive the rapid development of the cable masterbatch industry.
In the future, cable masterbatches will show the following development trends.
Development of Multifunctional Masterbatches
Cable products often need to have multiple properties simultaneously, and the integration of coloring and other functions into masterbatches is of great significance to improving the performance of cable products and simplifying their production process. Multifunctional masterbatches include colored and toughened masterbatches, etc.
Development of High-performance Engineering Plastics and Thermoplastic Elastomer Masterbatches
High-performance engineering plastics and thermoplastic elastomers are developing rapidly, such as thermoplastic fluoroplastics and thermoplastic polyurethanes, and their products also need to be colored with masterbatches. For example, polytetrafluoroethylene propylene masterbatches, polyvinylidene fluoride masterbatches, and thermoplastic polyurethane masterbatches has posed new challenges to the masterbatch industry. The preparation of these masterbatches is very different from traditional masterbatches in the selection of raw materials, processing technology, and conditions of use.
How to adapt to the ultra-high temperature processing performance of high-performance engineering plastics and the special processing rheological characteristics of thermoplastic elastomers will be the technical problems faced.
Development of High-volume Masterbatches for Dedicated Grades
With the rapid development of the cable industry, the output of masterbatches will increase significantly than in the past. Some masterbatches will no longer be directly supplied to downstream cable manufacturers, but directly to upstream petrochemical enterprises, and masterbatches and resins will be directly made into color-modifier materials. The formation of this production method has led to the partial transformation of the masterbatch production model, which has always been characterized by small batches and multiple varieties, into a single-variety and large-scale production model. The change in production mode will also pose challenges to the masterbatch technology. How to ensure the uniformity of the masterbatch produced for a long time and how to adapt to the large-scale screw granulation technology will be the technical problems to be solved for this kind of masterbatch.
Source: https://mp.weixin.qq.com/s/Pw3RUS6p_-b7KKeAGKcnFw
