Machines in the masterbatch production process
Examining production methods (additive, white, black and colored masterbatches in Armen Polymer Company) along with pre-mixing machines
In the masterbatch production process, a high-speed internal mixer is used in the pre-mixing method to produce a homogeneous mixture of the masterbatch formulation (polymer powder, pigment and dispersing agent). Pre-mixing is done in two types, cold and hot.
In the cold type, only a homogeneous mixture of components is formed. While in the hot type, due to the creation of enough energy and friction, the dispersion agent is melted and the pigments start to get wet.
It is clear that better dispersion occurs in pre-mixing of the warm type, then this homogeneous mixture is sent to the extruder to be weighed. After weighing, the mixture enters the feeding part of the extruder and is melted. The interaction and distribution of pigments takes place in the polymer melt. Finally, the output melt is crushed, cooled in a water bath, homogenized and packaged as granules.
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This method is mainly used due to low investment cost, high product quality, and high speed of product output. The output varies between 100 and 500 kg/h.
Feed distribution method in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
In the production process of masterbatch (additive masterbatch, white masterbatch, black masterbatch and colored masterbatch in Armen Polymer Company) by feed sharing method, polymer powder is fed separately into the tank and weighed there. Then it enters the feeding area of the double spiral extruder and its melting operation begins.
On the other side, wax (dispersion agent) and pigment are pre-mixed in the internal mixer at high speed and a homogeneous mixture is prepared from them. Then it is weighed and added to the polymer melt inside the extruder through the side feed line of the extruder.
The advantage of this method is that the pigment no longer enters the melting zone and does not have to pass through it, reducing the risk of clumping.
Due to the lower heat resistance of the pigments in the previous method, they may no longer have the necessary coloring power or their color quality may decrease, which is solved with this technique.
In this method, the masterbatch (additive masterbatch, white masterbatch, black masterbatch and colored masterbatch in Armen Polymer Company) is usually obtained with excellent quality and higher quality than the pre-mixing method. Mardon extruder for this process has a length to diameter ratio of 40 to 48, which is used to produce carbon black and titanium dioxide masterbatches.
Due to the complexity of the system, the initial investment cost increases. This method is used to produce products in the amount of 500 to 5000 kg/hour.
The role of extruder in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Introduction of extruder – single screw extruder (Mardone) – double screw extruder – piston extruder – extrusion products
Introduction of extruder in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Extruder is a machine that applies force to the decomposed rubber and plastic mixture to pass through a mold with pressure at the end of the machine and produce a strip-shaped product with a specific cross-section.
Extruder machines with various applications are widely used in the rubber and plastic industry.
In the production line, extruder machines are used for the initial shaping of rubber and plastic for subsequent operations and also for shaping the final products.
Classification of extruders in terms of nutrition in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Extruders are divided into two categories based on the temperature of the materials they feed, which is necessary to perform the operation
Hot feeding extruder
Hot feeding extruder
Usually, the feed required for hot extruders used in the rubber industry is already preheated in a separate operation.
In the usual methods of hot extrusion, a mill is usually used for this work. Cold extruders that operate at room temperature using a rubber band or rubber granules. Secondly, extruders can be classified and separated according to their application.
Many factories want a machine that, if not efficient enough, can at least successfully and correctly process a variety of mixtures with different mixing.
Emphasis is placed here on minimizing die change time and returning the machine to proper operating condition and ease of cleaning necessary and sufficient to minimize contamination from compound changes.
When a device is supposed to work for a long time with rubber compounds that have limited flow and silane properties, Serveda spirals can be designed so that both the output rate of the material is high and there is a good control in terms of dimensions. Also, despite minor changes in feeding materials, the feeding part and the tension belt as well as the control system can be selected in such a way that proper dimensional control is achieved.
The major physical difference between hot and cold extruders is the ratio of length to diameter of their spiral. For hot machines, where a significant part of the energy for heating and plasticizing the rubber mixture is done on the shaft, the action of the spiral extruder is only to transfer and apply pressure. This allows the machines to be small and have helical lengths of 3d to 5d in diameter. In addition to the transfer and pressure operations by the spiral, in cold extruders, the spiral must be able to perform the necessary mechanical work in the rubber to raise the temperature and reach the desired temperature and create the softness of the material when exiting. This makes the spirals have longer lengths in the range of 9d to 15d and even larger spirals may be used in some applications. Cold extruders have largely replaced hot ones in production lines. This replacement has mostly been done in lines that have been desired with long-term work or precision in the correct dimensional measurement. This machine has taken the market with significant improvements that are due to the variety of developed designs and knowledge of work techniques. Machines have made a significant contribution.
A brief explanation about the components of the spiral extruder with cold feeding in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Feeding funnel:
It is the place where the mixture (materials) enters the extruder and the shape of the funnel differs depending on the type of feed.
Two things are important about the feeding funnel
Funnel size
uniformity of nutrition
Uniform feeding leads to uniform product production
Extruder shell or body in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
It is a metal cylinder that surrounds the helix. Holes are installed inside this cylinder so that we can control the temperature of the extruder by passing hot and cold water. If the temperature of the mixture is not controlled, the mixture becomes hot, which causes the output product to come out as roasted or burnt (or actually scorched).
spiral
In a cold-fed extruder, as the name implies, the rubber mixture is fed at ambient temperature. The feed may be in the form of strips or grains. The spiral must transmit a sufficient amount of mechanical energy. In the design of the spirals used in the extruder with cold feeding, special checks are necessary. In order for mastication to take place, the height of the spiral blade should be low and the length of the spiral should be high.
The spiral of a simple extruder has three feeding parts, transfer part or measuring part and compression part. Each part of the spiral has a separate role. The feeding part transfers the material from the feeding hopper. The transfer part heats and mixes the materials.
The compression part is uniform and the necessary pressure is created to drive the material from inside the die.
There is also temperature control inside the spiral. Inside the spiral there are channels through which water can pass to control the temperature. The screw speed has a great effect on the temperature of the extruder. In the constant feeding amount, increasing the screw speed increases the temperature of the product coming out of the extruder.
Ideal speed in spiral extruders for production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
It is the speed limit that can receive the rubber from the feed and prevent it from collecting in the feed hopper.
head
The purpose of using the head for production (additive masterbatch, white masterbatch, black masterbatch and colored masterbatch in Armen Polymer Company) is to balance and even out the pressure and transfer the mixture to the mold.
The shape of the head should be designed so that it can meet the needs that are required
Providing maximum product output without any problem and disorder
Deformation compensation due to the elastic recovery properties of the mixture
Elimination of static and static areas that may be created in the mixing path.
The mold is an object that is placed on the head and makes the mixture take the desired shape when it comes out. In general, designing requires a lot of skill and experience.
Types of extruders in production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Piston extruder
The simplest extruder is a piston extruder for production (additive masterbatch, white masterbatch, black masterbatch and colored masterbatch in Armen Polymer Company). The heat melts the material inside the body and reduces the viscosity.
With the correct combination of pressure and temperature, the product of the extruder is pushed out of the die in the desired and designed form.
This type of extruder has problems
- First, the process is discontinuous
- Secondly, due to the insulating nature of plastic, it takes a long time to uniformly heat the material from the surface of the shell to the center, and on the other hand, if the temperature of the shell is too high, it will destroy the resin in the wall.
- Also, in the piston extruder, the amount of shear heating caused by the movement of the extruder is minimal.
Single screw extruder (Mardone) for production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
The key components of the single screw extruder are divided into 5 main parts for production (additive masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company).
Drive system
feed system
Spiral, shell (cylinder) and heating systems
Diehead collection
Control system
The drive system includes the engine, gearbox, ball bearings and bearing assembly.
The feeding system includes the feed hopper, the feed throat and the spiral feed part.
After that, there are the spiral, cylinder and heating systems where the solid resin part is transferred, melted and mixed and returned to the die pump.
The extruder product is formed after being transferred from the screw in the adapter and die.
Extruders are classified and sold according to the diameter of the spiral or cylinder and the ratio of length to diameter (L/D).
The L/D of the extruder describes the length ratio of the screw to the cylinder.
The definition of L/D including the axial length L depends on the equipment manufacturer.
In some factories, the length of the feeding section is the length of the cylinder, and some are not included.
Performance is directly related to the L/D of the extrudate.
Two extruders with the same diameter but different L/Ds have different performance and capacities. A longer extruder (more L/D) has more mixing and melting capabilities.
Advantages of small L/D extruders in production
(Additional masterbatches, white masterbatches, black masterbatches and colored masterbatches in Armen Polymer Company)
Need less area for installation
Less initial capital
Lower handling costs for spirals and cylinders
Shorter shelf life in extruders, especially when processing temperature-sensitive materials
Requires less crack torque
Less power and therefore the need for a smaller engine
Extruders with longer L/D for production
(Additional, white, black and colored masterbatches in Armen Polymer Company) also have these advantages
- Has more output
- Ability to mix with greater capacity
- They can be pumped at higher pressures
- More melt capacity with less shear heat
- Increased heat transfer from the cylinder
- L/D of some extruders are 18:1, 20:1, 24:1, 30:1, 36:1, 40:1
feeding
It includes two feeding systems, which work by gravity, two types of flood and starve. Both feed systems have a hopper directly on the feed throat of the extruder. The feeding throat part is directly connected to the extruder cylinder, and they use water flow to cool and heat it. Water flow can be measured with a flow meter. The temperature of the feeding throat should be such that it feels warm to the touch, but not hot.
The purpose of cooling by water is to prevent the fed materials from softening, becoming sticky and sticking together in the feeding throat, which causes a barrier and quick melting in the feeding funnel.
An insulating barrier is attached between the cylinder and the feed section to minimize heat transfer. The geometrical shape of the funnel and feeding throat causes the material to flow inside the extruder with the least restrictions.
Grooved feeding throats are used in the production of blown films and other applications to increase the output of the extruder.
Note that the grooves are deep under the funnel at the beginning of the feeding section and disappear before the entrance of the cylinder section.
The cooling channels around the feeding part neutralize the heat caused by the friction produced by the spiral rotation and grain density inside the spiral channels and prevent premature melting.
