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PET plastic raw material PETG bottle information introduction

PET plastic materials, PETG bottles,Shampoo bottle, Polyethylene terephthalate is the most important variety in the thermoplastic polyester, the English name is Polythylene terephthalate, referred to as PET or PEIT (hereinafter referred to as PET), commonly known as polyester resin. It is a polycondensate of terephthalic acid and ethylene glycol. Together with PBT, it is collectively referred to as thermoplastic polyester, or saturated polyester.

Polyethylene terephthalate (PET)

I. Overview

In 1946, the United Kingdom issued the first patent for preparing PET. In 1949, the British ICI formula completed the pilot test. However, after the United States DuPont purchased the patent, the production facility was established in 1953, which was the first to realize industrialized production in the world. In the early days, almost all PET was used for synthetic fibers (commonly known as polyester in our country, really good). Since the 1980s, PET has made breakthroughs in the development of engineering plastics. Nucleating agents and crystallization accelerators have been developed one after another. PET and PBT together as thermoplastic polyesters have become one of the five major engineering plastics.

PET is divided into fiber-grade polyester chips and non-fiber-grade polyester chips. ① Fiber-grade polyester is used to make polyester staple fiber and polyester filament, and is the raw material for polyester fiber enterprises to process fibers and related products. Polyester is the most productive variety in chemical fiber. ②Non-fiber grade polyester is also used in bottles, films, etc., which are widely used in the packaging industry, electronic appliances, medical and health, construction, automotive and other fields. Among them, packaging is the largest non-fiber application market for polyester, and it is also the most growing PET market. Fast field.

Advantages of PET as a packaging material:

1. It has good mechanical properties, the impact strength is 3~5 times that of other films, and the folding resistance is good.

2. Resistance to oil, fat, enoic acid, dilute alkali, and most solvents.

3. With excellent resistance to high and low temperatures, it can be used for a long time within a temperature range of 120°C, and can withstand high temperatures of 150°C and low temperatures of -70°C in short-term use, and has little effect on its mechanical properties at high and low temperatures.

4. The gas and water vapor permeability is low, and it has excellent gas, water, oil and peculiar smell performance.

5. High transparency, can block ultraviolet rays and good gloss.

6. Non-toxic, tasteless, good hygiene and safety, and can be directly used for food packaging.

Two: feature editing

PET is a milky white or yellowish highly crystalline polymer with a smooth and shiny surface. Creep resistance, fatigue resistance, abrasion resistance, good dimensional stability, low abrasion and high hardness, with the greatest toughness among thermoplastics: good electrical insulation, low temperature influence, but poor corona resistance. It is non-toxic, weather-resistant, chemical-resistant, low water absorption, resistant to weak acids and organic solvents, but not immersed in hot water or alkali.

PET resin has a high glass transition temperature, slow crystallization speed, long molding cycle, long molding cycle, large molding shrinkage, poor dimensional stability, crystallization molding is brittle, and low heat resistance.

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

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

2. Because of its high heat resistance, the reinforced PET is immersed in a solder bath at 250°C for 10S, almost no deformation or discoloration. It is especially suitable for the preparation of electronic and electrical parts for soldering:

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

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

Three: application editing

PET is mainly used for fibers, and a small amount is used for films and engineering plastics. PET fiber is mainly used in the textile industry. PET film is mainly used for electrical insulation materials, such as capacitors, cable insulation, printed circuit wiring substrates, and electrode slot insulation. Another application area of ​​PET film is film base and base tape, such as motion picture film, X-ray film, audio tape, electronic computer tape and so on. PET film is also applied to vacuum aluminum to make metallized film, such as gold and silver wire, micro capacitor film and so on. Another use of PET is blow-molded products, polyester stretch bottles for packaging.

Glass fiber reinforced PET is suitable for electronic, electrical and automotive industries. It is used in various coil bobbins, transformers, televisions, tape recorder parts and shells, automotive lamp holders, lampshades, incandescent lamp holders, relays, rectifiers, etc.

Four: Forming editing

The molding process of PET can be injection molding, extrusion, blow molding, coating, bonding, machining, electroplating, vacuum metal plating, and printing. The following mainly introduces two kinds.

1. Injection level ①Temperature setting: Nozzle: 280~295℃, front section 270~275℃, medium forging section 265~275℃, rear section 250-270℃; screw speed 50~100rpm, mold temperature 30~85℃ , Amorphous mold is below 70℃, back pressure is 5-15KG. ②Try the desiccant dryer, the material tube temperature is 240~280℃, the injection pressure is 500~1400KG, the injection molding temperature is 260~280℃, the drying temperature is 120~140℃, and the time required is 2~5 hours.

2. For the film level, the PET resin chips are pre-dried to hydrolyze, and then the amorphous slabs are extruded through a T-die in an extruder at 280°C, and then quenched by a cooling drum or cooling liquid to keep them Amorphous shape for stretching orientation. The thick film is then biaxially stretched by the tenter to form a PET film. Longitudinal stretching is to preheat the thick sheet to 86~87℃, and stretch it about 3 times along the plane extension direction of the thick sheet at this temperature, so that the orientation can increase the crystallinity and reach a higher temperature: horizontal stretching The stretching preheating temperature is 98~100℃, the stretching temperature is 100~120℃, the stretching ratio is 2.5~4.0, and the heat setting temperature is 230~240℃. The film after stretching in the vertical and horizontal directions needs to be heat-set to eliminate the film deformation caused by stretching and make a film with better thermal stability.

Polyterephthalate plastics mainly include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).

PET has a highly symmetrical molecular structure and a certain crystal orientation ability, so it has high film-forming properties and properties. PET has good optical properties and weather resistance, and amorphous PET has good optical transparency. In addition, PET has excellent wear resistance, friction, dimensional stability and electrical insulation. Bottles made of PET have high strength, good transparency, non-toxic, anti-permeability, light weight, high production efficiency, etc., so they have been widely used. The molecular chain structure of PBT and PET is similar, and most of the properties are the same, except that the main chain of the molecule has changed from two methylene groups to four, so the molecule is more flexible and the processing performance is better. The main uses of polyterephthalic acid plastics are:

Film and sheet materials: all kinds of food, medicine, non-toxic and sterile packaging materials; high-end packaging materials for textiles, precision instruments, electrical components; audio tapes, video tapes, movie films, computer floppy disks, metal coatings and photosensitive films, etc. Substrate; electrical insulation materials, capacitor films, flexible printed circuit boards and membrane switches and other electronic and mechanical fields.

Packaging bottle application: its application has been developed from the initial carbonated beverage to beer bottles, edible oil bottles, condiment bottles, medicine bottles, cosmetic bottles, etc.

Electronic appliances: manufacturing connectors, coil bobbins, integrated circuit shells, capacitor shells, transformer shells, TV accessories, tuners, switches, timer shells, automatic fuses, motor brackets and relays, etc.

Automobile accessories: such as switchboard covers, ignition coils, various valves, exhaust parts, distributor covers, measuring instrument covers, small motor covers, etc., can also make use of PET's excellent paintability, surface gloss and rigidity to manufacture automobiles Exterior parts.

Mechanical equipment: manufacturing gears, cams, pump housings, pulleys, motor frames and watch parts, and can also be used as microwave oven bakeware, various ceilings, outdoor billboards and models, etc.