Polyether ether ketone, PEEK resin (Polyether Ether Ketone, PEEK for short) is a condensation reaction of "difluorobenzophenone" and "hydroquinone" in the presence of alkali metal carbonate, using diphenyl sulfone as a solvent. A new type of semi-crystalline aromatic thermoplastic engineering plastic is prepared.

Compared with other special engineering plastics, PEEK has more significant advantages, such as high temperature resistance of 260 degrees, excellent mechanical properties, good self-lubrication, chemical corrosion resistance, flame retardant, peel resistance, wear resistance, strong nitric acid resistance, radiation resistance , Super mechanical properties can be used for high-end machinery and aviation and other technologies.

Characteristics of PEEK engineering plastics

High temperature resistance

PEEK has a high glass transition temperature and melting point (334°C), which is one of the reasons for its reliable application in applications requiring heat resistance. Its load thermal deformation temperature is as high as 316 °C, and the continuous use temperature is 260 °C.

Mechanical properties

PEEK is a plastic with a balance of toughness and rigidity. In particular, its excellent fatigue resistance to alternating stress is the most outstanding among all plastics and is comparable to alloy materials.

self-lubricating

PEEK has excellent sliding properties among all plastics and is suitable for applications requiring low coefficient of friction and wear resistance. In particular, the self-lubricating performance of PEEK modified with carbon fiber and graphite in a certain proportion is better.

Chemical resistance (corrosion resistance)

PEEK has excellent chemical resistance. Among common chemicals, only concentrated sulfuric acid can dissolve or destroy it. Its corrosion resistance is similar to that of nickel steel.

flame retardancy

PEEK is a very stable polymer, 1.45mm thick sample can reach the highest flame retardant standard without any flame retardant.

Peel resistance

PEEK has good peeling resistance, so it can be made into thinly coated wire or magnet wire, and can be used under harsh conditions.

Fatigue resistance

PEEK has the best fatigue resistance of all resins.

Hydrolysis resistance

PEEK and its composite materials are not chemically affected by water and high-pressure water vapor, and products made of this material can still maintain excellent properties when used continuously in high-temperature and high-pressure water.

Process flow of PEEK injection molding

1. Drying: Granular polymers generally absorb 0.5%w/w atmospheric moisture and for best results should be dried until the moisture is less than 0.02%w/w. The material can be dried in a circulating air oven for at least 3 hours at 150°C, or 2 hours at 160°C. If it is dried in a drying box, the thickness of the raw material in the tray should not exceed 25mm. and prevent contamination.

2. Recycling: Leftovers can be recycled and injected into virgin materials. It is recommended that recycled materials without fillers should not exceed 30% of the total weight, and recycled mixtures containing fillers should not exceed 10% of the total weight.

3. Thermal stability: If the equipment is shut down during the melting process and the polymer residence time does not exceed 1 hour, there is no obvious degradation of the material at a temperature of 360 °C. However, if the shutdown time exceeds 1 hour, the temperature of the barrel should be lowered to 340°C. At this temperature, the material can remain stable for several hours. The temperature of the barrel must be increased when processing continues. If the shutdown time exceeds 3 hours, The barrel should be cleaned. You can use some materials that can maintain performance at 380 °C, such as polyethersulfone or polyetherimide, or low MFI polyethylene for cleaning.

4. Injection machine: The melting point of the polymer is 343°C, which is suitable for traditional machines that can maintain the melt temperature at 360-400°C.

5. Barrel capacity: Due to the high processing temperature of PEEK polymers, the residence time of the material must be as short as possible. The ideal barrel capacity is 2-5 times the total shot weight.

6. Nozzle and locking system: The melting point of the polymer is very high, if the temperature drops below 343°C, the melt will solidify quickly. Therefore, it is necessary to install a large enough heater at the nozzle to prevent the "injection cold material" from cooling down.

7. Screw: It is recommended that the minimum length-diameter ratio L/D of the screw is 16:1, but the L/D ratio between 18:1 and 24:1 should be preferred.

8. Barrel temperature: 360-380℃ for unreinforced grade and 380-400℃ for reinforced grade.

9. Mold temperature: The surface temperature of the mold is 175-205℃.

10. Injection pressure: The general injection pressure is 70-140MPa.

11. Injection speed: medium to high speed.

12. Back pressure: It is recommended to set the back pressure to 0-1.0MPa (0-10 kgf/cm2).

13. Screw speed: Generally, the screw speed is 50-100rpm. For the strengthening grade, it is recommended to use a lower screw speed.

14. Molding shrinkage rate: Different grades of polymers have different shrinkage rates. The unfilled grade is about 1.2-2.4%, and the filled grade is: 0.1-1.1%.

15. Secondary processing: secondary processing such as bonding, tapping, pressing, metal inserting, cutting processing and surface metallization can be performed.