What Is PET Plastic?

PET plastics are polyterephthalic plastics, mainly including polyethylene terephthalate PET and polybutylene terephthalate PBT. Polyethylene terephthalate is also commonly known as polyester resin. It is a polycondensate of terephthalic acid and ethylene glycol, together with PBT, collectively referred to as a thermoplastic polyester, or a saturated polyester.

The PET plastic molecular structure is highly symmetrical and has a certain crystal orientation ability, so it has high film formation and formation. PET plastics have good optical properties and weather resistance, and amorphous PET plastics have good optical transparency.

In addition, PET plastics have excellent wear resistance, dimensional stability and electrical insulation. PET bottles have been widely used because of their high strength, good transparency, non-toxicity, penetration resistance, light weight and high production efficiency. PBT and PET molecular chain structure is similar, most of the properties are the same, but the molecular backbone is changed from two methylene groups to four, so the molecules are more supple and the processing performance is better.

PET is a milky white or light yellow highly crystalline polymer with a smooth and shiny surface. It is resistant to creep, fatigue and friction, has low abrasion and high hardness, and has toughness in thermoplastics. It has good electrical insulation properties and is less affected by temperature, but has poor corona resistance. Non-toxic, weather-resistant, chemical-resistant, and hygroscopic, and drying before molding is a must. It is resistant to weak acids and organic solvents, but it is not soaked in heat-resistant water and is not resistant to alkali.

The PET resin has a high glass transition temperature, a slow crystallization rate, a long molding cycle, a long molding cycle, a large molding shrinkage ratio, a poor dimensional stability, a brittleness in crystallization, and low heat resistance.

Through the improvement of nucleating agent and crystallization agent and glass fiber reinforcement, in addition to the properties of PBT, PET has the following characteristics:

1. The heat distortion temperature and long-term use temperature are the highest among thermoplastic general engineering plastics;

2. Because of the high heat resistance, the reinforced PET is immersed in a solder bath of 250 ° C for 10 s, and it is hardly deformed or discolored, and is particularly suitable for preparing electronic and electrical parts for soldering;

3. The bending strength is 200MPa, the elastic modulus is up to 4000MPa, the creep resistance and fatigue resistance are also good, the surface hardness is high, and the mechanical properties are similar to those of thermosetting plastics;

4. Since the ethylene glycol used in the production of PET is almost half the price of the butanediol used in the production of PBT, PET resin and reinforced PET are the lowest in engineering plastics and have a high cost performance.

5. PET resin bonding: sili-1706 one-component room temperature vulcanizate, after curing, the elastomer has excellent waterproof, anti-vibration adhesive, high and low temperature resistance, because 泀力科技 is based on the molecular structure of the resin, so special Used to bond engineering plastics.

Use

Glass fiber reinforced PET is suitable for use in the electrical, electronic and automotive industries for a wide range of coil bobbins, transformers, televisions, recorder parts and housings, automotive lamp holders, lampshades, incandescent lamp holders, relays, selenium rectifiers, etc. The current consumption ratio of PET engineering plastics is 26% for electrical appliances, 22% for automobiles, 19% for machinery, 10% for appliances, 10% for consumer goods, and 13% for others. At present, the total consumption of PET engineering plastics is still small, accounting for only 1.6% of the total PET.

1. Film sheet: all kinds of food, medicine, non-toxic and aseptic packaging materials; high-grade packaging materials for textiles, precision instruments and electrical components; audio tapes, video tapes, film films, computer floppy disks, metal coatings and photographic film Substrate; electrical insulation materials, capacitor films, flexible printed circuit boards and membrane switches, and other fields of electronics and machinery.

2. Application of packaging bottles: Its application has been developed from the original carbonated beverages to the current beer bottles, edible oil bottles, condiment bottles, pharmaceutical bottles, cosmetic bottles and so on.

3. Electronics: manufacturing connectors, coil bobbins, integrated circuit housings, capacitor housings, transformer housings, TV accessories, tuners, switches, timer housings, automatic fuses, motor brackets and relays.

4. Auto parts: such as switchboard cover, ignition coil, various valves, exhaust parts, distributor cover, measuring instrument cover, small motor cover, etc., can also use PET excellent coating, surface gloss and rigidity, Manufacture of exterior parts for automobiles.

5. Mechanical equipment: manufacturing gears, cams, pump housings, pulleys, motor frames and clock parts, can also be used as microwave oven baking trays, various ceilings, outdoor billboards and models. .

6. PET plastic molding can be injection molding, extrusion, blow molding, coating, bonding, machining, electroplating, vacuum metallization, printing.

Identification method

1. First taste, PET tastes different from ordinary plastic, burn it with a lighter, and then smell very aromatic and comfortable (just burn a bottle to smell), if the PET contains other ingredients, the taste is very pungent . There is a bottle containing SEBS ingredients that cannot be used.

2, look at the burning part, if the distribution of black or oil droplets is very fast, most of the melting point is not normal, which is often found in PET film.

3, drawing, when burning, pull the wire on the lighter, see the length of the wire is not long, then pull the pulled wire off, see the break point in the middle, the wire is not rolled into a small circle, the more the volume More indicates that the melting point is high.

However, if it is a bottle, it should not be a big problem. The most critical point is to distinguish whether it contains PVC, which is a fatal injury to PET. First sample more, then tiling in a sunny place, PVC is light blue in the sun. If there is a white crease in the fold. The above is the naked eye identification, the accuracy is limited, mainly depends on experience.

There is also a more practical and better way to buy an oven to adjust the temperature to 250 degrees and bake it for half an hour. If the product contains PVC, there will be a lot of yellow spots on the surface; if the melting point is not enough, it will be very fast. melt.