What is the PFA

I. What is the PFA?

The English name of PFA is Polyfluoroalkoxy, or tetrafluoroethylene perfluoroalkoxyethylene ether copolymer (perfluoroalkylate, soluble polytetrafluoroethylene).PFA resin is relatively new fluoroplastic that can be processed by melting. PFA, FEP and PTFE have similar chemical properties, but FEP can only be used below 200 degrees, and PTFE cannot be injected. 【this resource was first published by China fluoroplastics network.】

1. Specific gravity: 2.13-2.167g/cubic centimeter

2. Molding shrinkage rate :3.1-7.7%

3. Molding temperature: 350-400℃

4. The melting point of PFA is about 580F and the density is 2.13-2.16g /cc (g/ cubic centimeter).

II. Features and main USES of PFA

PFA, commonly known as fusible PTFE, is the crown of fluoroplastics with various properties and USES similar to FEP.Widely used in semiconductor industry, as well as medical, chemical corrosion protection, automotive and other fields.

PFA products include granular products for molding and extrusion, and powdery products for rotating molding and coating.Its semi-finished products are membrane, plate, rod and pipe.PFA resin distributed in the American market includes Teflon of DUPOut, Neoflon of Daikin, Hthen of Ansimont and Hostafl of HOechst Celanese.

1. Main USES of PFA:

(1). Suitable for making corrosion resistant parts, wear - resistant parts, seals, insulation parts and medical equipment parts.

(2). High temperature wire, cable insulation layer, anti-corrosion equipment, sealing materials, pump valve bushing, and chemical containers.

2. Molding performance

(1). Crystallization material, small moisture absorption.Products may be processed by the usual thermoplastic processing method.

(2). Poor liquidity, easy decomposition, decomposition produced corrosion gas.It is advisable to strictly control the molding temperature not to exceed 475 degrees, the mold should be heated to 150-200 degrees, the pouring system should have little resistance to the material flow.

(3). Translucent granule, injection molding, extrusion molding.Forming temperature 350-400 degrees, 475 degrees above easy to cause color or bubble.And notice that it's harder to get out of the mold.

(4). Because the molten material on the metal corrosion effect, long-term production, the mold needs to electroplate chromium treatment.

3. Material performance

1. PFA is a copolymer of a small amount of perfluoropropyl perfluoroethylene ether and polytetrafluoroethylene.The melt bond is increased, the solution viscosity is decreased, and the performance is not changed compared with ptfe.The resin can be processed into products directly by ordinary thermoplastic molding.

2. long-term use temperature -80- 260 degrees, excellent chemical corrosion resistance, corrosion resistance to all chemicals, friction coefficient in the lowest plastic, and very good electrical performance, its electrical insulation is not affected by temperature, "plastic king" said.

3. Its chemical resistance is similar to ptfe and better than vinylidene fluoride.

4. Its creep resistance and compression strength are better than ptfe, with high tensile strength and elongation up to 100-300%.Good dielectric property, excellent radiation resistance.

5. non-toxic: with physiological inertia, can be implanted in the human body.

 

 

The application of UHMWPE material is introduced

In recent years, UHMWPE has been widely used in board, profile, pipe and other main fields.Market research shows that UHMWPE has become a widely used industrial raw material with its excellent abrasion resistance, which is widely used in coal mining, shipbuilding, floor MATS and other occasions and products. These products need certain processing technology, the use of some equipment: for example, UHMWPE/PTFE tube extrusion machine, Polymer/Teflon bar extrusion machine, molding machine, Polymer PTFE sintering furnace, PTFE Gaskets Press moulding machine, etc. In recent years, China's demand for this product is increasing day by day.

UHMWPE separator is basically used in automobile battery manufacturing industry in developed countries in Europe and America.UHMWPE can also be used for viaduct as underrail spacer. UHMWPE film is based on UHMWPE board, which is a film with a thickness of less than 1 mm after cutting.Ninety percent of UHMWPE's customers are electronics floor mat manufacturers, and up to 95 percent of them are used for mouse floor MATS.There are some differences in the use of UHMWPE fiber between Europe and America and Japan. It is mainly used for body armor and weapons and equipment, accounting for 60% ~ 70% of the total consumption, followed by cables, fishing nets and labor protection supplies.Japan is mainly used for cables, fishing nets and labor protection equipment.

Compared with teflon (teflon) used in traditional mouse pad, UHMWPE film is more wear-resistant, and its self-lubricity is second only to teflon material.Cost, UHMWPE film density is small, according to square conversion UHMWPE film than fluron 50% lower.Therefore, UHMWPE film has gradually replaced teflon as the preferred raw material for floor MATS in OEM factories.

Keywords: UHMWPE, PTFE, Polymer, Teflon, extrusion, Gaskets,UHMWPE film, extrusion machine, sintering furnace

Introduction to ptfe teflon pipes

Ptfe teflon tube extrusion machine is divided into many kinds, exactly say ptfe tube forming process has push and pressure method, extrusion method, hydraulic method, welding method, winding method, etc., which is mainly push and pressure method.Generally dispersed PTFE resin with particle size of 500 microns and apparent density of 0.45g/ml ~ 0.55g/ml is adopted.The small diameter tube chooses the compression quite big resin, the medium and large diameter tube chooses the compression quite small resin.Extruder usually choose 200 and 260 solvent oil.PTFE thermal shrinkage tube, PTFE spiral tube, PTFE steel wire reinforced hydraulic tube and so on can be produced by the secondary processing of PTFE tube.

 

1.1 common ptfe teflon pipe

Ptfe ordinary tube is made of ptfe dispersion resin at room temperature with organic solvent as extruder, and then through drying and sintering.According to the size of the pipe diameter can be divided into two types of ordinary pipe and micro pipe.Ordinary tube inner diameter > 4mm, micro tube inner diameter ≤4mm.

Typical formula for PTFE tube production:

Dispersed PTFE resin: 100 (weight)

Extruder: 18 ~ 24

Production process:

PTFE, extruder - mixing - pushing - pressing - drying - sintering - cooling - products.

Production process parameters:

Mixing: temperature ≤19 ℃, time 10min ~ 20min, mixed at 25 ℃ ~ 30 ℃ for more than 24h.

Blank: compression rate is about 50mm/ min, pressure is 0 ~ 3MPa.

Pushing pressure: the cavity temperature is 30 ℃ ~ 50 ℃, and the die temperature is 50 ℃ ~ 60 ℃.

Drying: under 210 ℃,2h ~ 3h

Sintering: batch sintering, temperature rise rate of 60 ℃/ h,375 ℃±5 ℃ insulation for 4h.

Continuous sintering, dry area 100 ℃ ~ 250 ℃, preheating area 250 ℃ ~ 330 ℃, sintering area 380 ℃ ~ 420 ℃, cooling area less than 300 ℃.

Main equipment: mixing machine, preforming machine, vertical pushing press, drying and sintering furnace.

USES: as insulation and fluid conduit.

 

1.2 polytetrafluoroethylene heat-shrinkable tube

PTFE thermal shrinkable tube has the property of being heat-shrinkable, so it can be tightly coated on the surface of other workpieces, making the workpieces resistant to corrosion, electrical insulation and viscosity.Widely used in electrical, chemical, mechanical, printing and other industries.The maximum shrinkage of PTFE shrink tubes is reported to be more than 75%.

It is processed by disperse PTFE resin. The principle is that PTFE is subjected to stress during processing and produces forced high-elastic deformation, which is reversible and freezes at low temperature. If the forced high-elastic deformation is reheated, it will gradually disappear and return to the original state.

Typical formula for PTFE thermal shrinkable tube production:

Disperse PTFE resin 100 (weight)

Extruder 20 ~ 22

Production process:

PTFE resin, extrusion aid → mixing → storage → pre-molding → pushing and pressing → drying → sintering → cooling → heat treatment → blowing → cooling → product.

Production process parameters:

The front part is the same as ordinary PTFE tube.

Heat treatment: the quenching process of the dried and sintered pipes after further full sintering at high temperature, the temperature is 390 ℃±2 ℃, and the coolant is -5 ℃.

Blowing: at 310 ℃ or so, fill the compressed gas below 0198MPa, the blowing rate is 200% ~ 400%.

Main equipment: blowing machine, other PTFE tube and the same.

 

1.3 ptfe teflon steel wire reinforced hydraulic pipe

The common PTFE pipe will break under the pressure of about 40kg/ cm2. When it is combined with steel wire, the pressure resistance will be greatly improved. The maximum working pressure abroad reaches 700kg/ cm2.The results show that the compressive strength and pulse strength of the hose are related not only to the steel wire strength but also to the weaving Angle.When the braiding Angle is 54°44 "for single-layer braiding, the steel wire does not extend under internal pressure, the length and diameter of the hose do not change, and the pressure resistance is the best.

When used as hose for hydraulic system in aviation industry, in order to prevent electrostatic breakdown of inner tube caused by hydraulic oil flow, trace conductive carbon black should be added in the manufacture of PTFE inner tube.However, it was found that adding carbon black could not completely prevent electrostatic discharge from passing through the tube wall and increase the gap.

In the 1960s, Attas manufactured composite tubes, in which the inner layer of the tubes was a uniform mixture of conductive carbon black and PTFE, and the outer layer of the tubes was pure PTFE.This form of tube body layer has axial conductivity, so it can not only eliminate static electricity, but also prevent seepage.

The process:

Inner resin (including conductive carbon black), outer resin → blank → pushing → drying → cooling → testing → weaving → fitting joints → testing.

PTFE steel wire composite hose is mainly used in aircraft hydraulic system, air conditioning system, fuel system, lubricating oil system.In civil industry, it is suitable for soft connection of hydraulic pressure, steam pressure and steam transportation in rubber, plastic, pharmacy, clothing, shipbuilding, automobile, machine tool, motor, diesel engine and paper making industries.

 

1.4 ptfe teflon spiral tube

PTFE spiral tube, also known as PTFE flexible hose, has not only all the excellent properties of PTFE, but also flexible properties.At present, there are two kinds of PTFE spiral tube and chemical fiber, stainless steel wire and plastic coated glass fiber woven reinforcement.

It is made of PTFE through secondary processing. The process is that PTFE thin-walled tube continuously rotates forward through a combination mold with a temperature of 270 ℃ ~ 280 ℃ at a certain speed.

It is mainly used for the inlet and outlet pipes of the shock parts such as the soft connection dislocation connection, serpentine pipes, pump engines and so on.Used for shielding cable and protecting cable sleeve of aircraft engine.

 

Keywords: PTFE, Ptfe tube, teflon, tube, ptfe pipe, machine, extrusion, extrusion machine, pushing, sintering, extruder

PLC control system of Polymer extruder

The PLC control system of extruder has been widely used in many fields such as cemented carbide, pharmaceutical, food processing and mechanical processing. Extrusion technology is widely used because it can obtain products with uniform density in the direction of extension and high production efficiency. Currently on the market for some extrusion machine, such as: Polymer Teflon Rod extruder, PTFE UHMWPE tube extruder,etc. extrusion machine while there are almost one hundred years of history, but with the rapid development of information technology, all kinds of information technology in the layer, especially the detection technology, PLC control technology,microelectronics technology and modern control technology development puts forward new challenge on the extrusion machine. It is very important to study the application of PLC control system because the control system is developed in high efficiency, high speed and high precision.

 With the rapid development of manufacturing industry, industrial aluminum profiles have been widely used in various high-tech industries, such as aviation, bullet trains, ships and so on. The forming technology of metal aluminum profile mainly includes extrusion, forging and calendering. According to the extrusion molding process, such as the whole process will use the Polymer Teflon bar extruder, PTFE UHMWPE tube extruder, MouldingMachine, PTFE Gaskets Press Moulding Machine, Cutting Machine, PTFE Skiving Machine, Dry Grinder, cleaning machine, vibration screen, automatic feeding machine. The control system of extruder is emphasized. This set of control system combines PLC, MES and upper computer to realize online intelligent management, visual management, process control, process analysis and product traceability of production process.

 Isothermal extrusion speed control is an important method for high efficiency and high quality production in rare metal processing enterprises. Different raw materials (Polymer, PTFE, Teflon, UHMWPE), extruder extruded products are different, such as color, shape, density, etc. According to the characteristics of the treasure titanium 25M extrusion machine equipment, combined with the actual production condition, titanium simulation of isothermal extrusion speed control system, put forward to simulate the isothermal extrusion speed control system architecture and function of system implementation, is developed based on industrial PC + PLC titanium simulation of isothermal extrusion speed control system, using the prediction algorithm to build the extrusion speed prediction model. The system can achieve isothermal extrusion of titanium, shorten the extrusion time, and operate reliably.

keywords : Extrusion machine, Polymer , PTFE , Teflon ,UHMWPE , extrusion ,extruder ,Automation, Teflon rod, PTFE tube, bar extruder, tube extruder, Gaskets, Machine,Moulding, control

Explanation of main test indicators of PTFE products

PTFE products are a special type of plastic, which is quite different from other plastics. According to the industry standard of the Ministry of Light Industry, the PTFE products produced must meet the requirements of the index. Below we list the definitions of the 13 main test indicators for  for reference.

1. The coefficient of linear expansion indicates the degree of expansion or contraction of the material. It refers to the expansion ratio of the finished polytetrafluoroethylene plastic at a temperature of 1 ° C under a certain pressure, expressed as the coefficient of linear expansion relative to the unit length. This coefficient is one of the important indicators for understanding the degree of change in product size with increasing temperature of PTFE products, expressed in units of 1/°C or 1/K. The coefficient of linear expansion coefficient is α = ΔL / (L * ΔT), where ΔL is the change in the length of the object at the given temperature change ΔT, and L is the initial length. The linear expansion coefficient of PTFE is about 10-12*10-5/°C (ambient temperature 25-250°C), ie (0.01-0.012)%, and the linear expansion coefficient of PTFE is 10~20 times that of iron, which is larger than most plastics. 

2. Thermal conductivity: Also called thermal conductivity, it reflects the thermal conductivity of the material. It is defined as two parallel planes with an area of 1 m2 perpendicular to the direction of heat conduction inside the object. If the temperatures of the two planes differ by 1 K, the heat is transferred from one plane to the other in 1 second. The unit is defined as the thermal conductivity of the substance, and its unit is watt·m-1·open-1 (W·m-1·K-1). It is a reference indicator for studying the thermal insulation of target products when designing products.

3. The tensile strain at break is the tensile strain corresponding to the tensile fracture stress when the sample of the polytetrafluoroethylene product is not fractured under the tensile load, and the tensile strain is just when the sample material is plastically shaped. The ratio of the difference between the length to the original length and the original length, expressed as a percentage (%).

4. Tensile strength: In the test of tensile specimens, the critical value of the transition from uniform plastic deformation to local concentrated plastic deformation, characterizing the resistance of the material to the maximum uniform plastic deformation, is also the maximum load carrying capacity of plastic under static tensile conditions ( Maximum tensile stress). The unit is MPa. 

5. Elongation at break: It is the increment of the index from the original unit length (ie the rate of change of length), which is the ratio of the difference between the length of the pull-off and the original length to the original length, expressed as a percentage (%).

6. Electrical strength: A parameter indicating the breakdown of equipment insulation at a certain rated voltage, indicating the degree of insulation of the product withstand voltage. It means that under certain conditions, the ratio of the breakdown voltage to the thickness of the sample to be broken is the electrical strength of the product.

7. Breakdown voltage: The voltage at which the test piece breaks down is the highest voltage before being penetrated. That is, the sample does not break down at this voltage. The breakdown is usually caused by a partial discharge in the gas or liquid medium surrounding the sample and the electrode, and the sample at the edge of the smaller electrode (or equal-diameter two electrodes) is destroyed.

8. Density The ratio of the mass of a substance to its volume, that is, the mass of a substance per unit volume, is called the density of this substance. Kilograms/meter 3 or 1 gram per cubic centimeter 1.0 x 103 kg/m3 of polytetrafluoroethylene plastic products are usually tested by dipping, liquid pycnometer and titration.

9. Withstand voltage is the sample between the electrodes, the power frequency AC voltage rises to the voltage before the breakdown is the withstand voltage of the sample.

10. Fracture Nominal strain refers to the tensile strain corresponding to the fracture stress when the tensile specimen is not yielded and the fracture specimen is subjected to the specified specimen size, and the % is expressed by a dimensionless ratio or percentage.

11. The longitudinal dimensional change rate means that the pipe (100 ± 1) with a certain length is placed in a (260 ± 2 ° C) oven for 3 hours, and taken out at a normal temperature of 23 ± 2 ° C for 4 hours. The length of the treated sample is The percentage of the difference between the original size and the original size.

12. Dielectric strength is a measure of the electrical strength of a material as an insulator. It is defined as the maximum voltage per unit thickness that a unit is subjected to when it is broken down, in volts per unit thickness. The ratio of breakdown voltage to sample thickness. The breakdown voltage is tested according to GB/T1408.1-2006. The dielectric strength is in kilovolts per millimeter (KV/mm).