PC plastic, scientific name is polycarbonate, is a molecular chain containing carbonate ester group of polymer, according to the structure of the ester group can be divided into aliphatic, aromatic, aliphatic-aromatic and other types. Among them, the mechanical properties of aliphatic and aliphatic-aromatic polycarbonates are low, thus limiting their application in engineering plastics. At present, only aromatic polycarbonates have been industrially produced. Due to the structural peculiarities of polycarbonate, it has now become the five major engineering plastics in the fastest growing general engineering plastics.
pc plastic characteristics of what pc plastic performance introduction
Chemical properties/PC plastic
Polycarbonate resistance to weak acids, resistance to neutral oil.
Polycarbonate is not resistant to ultraviolet light, not resistant to strong alkali.
Physical Properties/PC Plastic
Specific Gravity:1.18-1.20g/cc Molding Shrinkage:0.5-0.8% Molding Temperature:230-320°C Drying Condition:110-120°C for 8hrs Can be used for a long time under -60~120°C.
Material properties of high impact strength, good dimensional stability, colorless and transparent, good coloring, electrical insulation, corrosion resistance, good abrasion resistance, but poor self-lubrication, stress cracking tendency, high temperature hydrolysis, poor compatibility with other resins. Suitable for the production of instrumentation small parts, insulation and transparent parts and impact parts
Material properties 1. Amorphous material, good thermal stability, wide range of molding temperature, poor fluidity. Moisture absorption is small, but sensitive to water, must be dried. Molding shrinkage is small, easy to melt cracking and stress concentration, so the molding conditions should be strictly controlled, the plastic parts must be annealed.
2. High melting temperature, high viscosity, greater than 200g of plastic parts, it is appropriate to use heated extension nozzle.
3. Poor plastic fluidity, mold pouring system to coarse, short for the principle, it is appropriate to set up a cold material well, the gate should be taken large, the mold should be heated.
4. Material temperature is too low will cause the lack of material, plastic parts without luster, material temperature is too high easy to overflow edge, blistering plastic parts. Mold temperature is low when the shrinkage rate is small, elongation is small, impact strength is low, bending, compression, tensile strength is low. Mold temperature exceeds 120 degrees Celsius when the plastic parts cooling slow, easy to deformation sticky mold
5. Plastic wall should not be too thick, should be uniform, to avoid sharp corners and gaps in the material characteristics / PC plastic
①high strength, tensile strength of 69MPa, bending strength of 96MPa.
②high-temperature resistance, long-term use of the temperature can be resistant to 130 degrees Celsius temperature environment.
②Good transparency, non-toxic.
④Raw material color matching and surface coating is not as good as ABs.
⑤Pc should be selected high fluidity grade. It is suitable for flip-flop and cell phones used in harsh environments.
Pc plastic processing technology
Plastic processing
PC has a large water absorption rate, must be preheated and dried before processing, pure PC drying 120 ℃, modified PC is generally dried at a temperature of 110 ℃ for more than 4 hours. Drying time should not exceed 10 hours. Generally available hollow extrusion method to determine whether the drying is sufficient.
Recycled material can be used up to 20%. In some cases, 100% of the recycled material can be used, the actual amount depends on the quality of the product requirements. Recycled materials should not be mixed with different masterbatches at the same time, otherwise the nature of the finished product will be seriously damaged.
Selection of injection molding machine
Nowadays, due to the cost of PC products and other reasons, more modified materials, especially electrical products, but also to increase the fire performance, in the flame-retardant PC and other plastic alloys product molding, the injection molding machine plasticizing system is required to be mixed with a good corrosion-resistant, the conventional plasticizing screw is difficult to do, when purchasing, be sure to explain in advance. Huameida has special PC screws for customers to choose.
Mold and gate design
The common mold temperature is 80-100℃, plus fiberglass is 100-130℃, small products can be used for needle gate, the depth of the gate should be 70% of the thickest part, and other gates are ring and rectangle.
The bigger the gate, the better, in order to reduce the plastic is excessive shear and cause defects. The depth of the vent hole should be less than 0.03-0.06mm, and the runner should be as short and round as possible. The demolding slope is generally about 30′-1°.
Melt temperature
The processing temperature can be determined by the air injection method. General PC processing temperature is 270-320 ℃, some modified or low molecular weight PC for 230-270 ℃.
Injection speed
More often seen with fast injection speed molding, such as playing electrical switch parts. Commonly slow → fast molding.
Back pressure
Back pressure of about 10 bar, which can be lowered if there is no gas pattern and color mixing.
Staying time
Staying too long at high temperature, the material will degrade, put also CO2 and become yellow. Do not use LDPE, POM, abs or PA to clean the barrel. Use PS to clean the barrel.
Precautions
Some modified PC, due to too much recycling (molecular weight reduction) or uneven mixing of various components, easy to produce dark brown liquid bubbles.
PC plastic market applications
Polycarbonate application development is to high composite, high functionality, specialization, serialization direction, has introduced a variety of products such as optical discs, automobiles, office equipment, boxes, packaging, medicine, lighting, film, and other products of their respective special grade grades.
Used in the building materials industry
Polycarbonate sheet with good light transmission, impact resistance, ultraviolet radiation and its products, dimensional stability and good molding and processing performance, so that it than the traditional use of inorganic glass in the construction industry has obvious technical performance advantages.
Used in the production of medical devices
Because polycarbonate products can be sterilized by steam, detergents, heating and large doses of radiation without yellowing or deterioration of physical properties, they are widely used in artificial kidney hemodialysis equipment and other medical equipment that need to be operated under transparent and intuitive conditions and need to be repeatedly sterilized.
Used in aviation, aerospace
According to statistics, only a Boeing-type aircraft with polycarbonate parts up to 2,500, a single machine consumes about 2 tons of polycarbonate. And in the spacecraft is used in hundreds of different configurations and by the glass fiber reinforced polycarbonate parts and astronauts protective equipment.
Used in the field of packaging
In recent years, in the field of packaging, the emergence of a new growth point is the re-sterilizable and reuse of various models of water bottles. Because polycarbonate products have the advantages of light weight, impact resistance and good transparency, no deformation and transparency when treated with hot water and corrosive solution washing, PC bottles have completely replaced glass bottles in some areas.
Used in the field of electronic and electrical appliances
Because of polycarbonate in a wide range of temperature and humidity with good and constant electrical insulation, is an excellent insulating material. At the same time, its good flame-retardant and dimensional stability, so that it has formed a wide range of applications in the electrical and electronic industry.
Used in the field of optical lenses
Polycarbonate with its unique high transmittance, high refractive index, high impact resistance, dimensional stability and easy processing and molding, etc., in the field occupies an extremely important position. Optical grade polycarbonate with the production of optical lenses can not only be used for cameras, microscopes, telescopes and optical test instruments, etc.
Basic material for optical disks
In recent years, along with the stubbornness of the information industry, optical disks made of optical-grade polycarbonate as a new generation of audio-visual information storage media, is a very rapid speed of rapid development. Polycarbonate with its excellent performance characteristics and thus become the world's main raw materials for optical disk manufacturing.
PC in automotive applications
Polycarbonate can meet the automotive interior parts of the material toughness, strength, heat resistance and other aspects of high-performance requirements. The application of these materials in automotive interior parts, with the following irreplaceable advantages of other types of materials:
1) superior impact resistance, impact strength in the top of the thermoplastics;
2) good paintability and adhesion to the cover film;
3) a high degree of dimensional stability;
4) integration of the components installed as one;
5) design of the parts installed as one;
6) the design of the parts installed as one;
7) the design of the parts installed as one;
8) the design of the parts installed as one;
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5) very flexible application of design and processing;
6) low coefficient of linear expansion and low coefficient of thermal expansion.
AIEPC and its alloy products: Polycarbonate PC1010NH is a high-strength transparent PC material, product engineers in the transparent product design of a commonly used materials, often injected into a variety of transparent or translucent parts, can be applied to automotive lamps and other components.
The high-performance PC/PBT1030 alloy has high impact resistance, excellent weather resistance and strength, and can be used in automotive bumpers, door handles and other parts.
High-performance weathering PC/ASA1025 alloy material has high impact resistance, excellent weatherability and heat resistance, and can be applied to automotive instrument panels, column covers, radiator grills and other parts.
Polycarbonate can meet the high-performance requirements of electronic and electrical shell parts on the toughness, strength, heat resistance and other aspects of the material. These materials in the application of electrical and electronic shell parts, with the following other types of materials irreplaceable advantages:
1) superior impact resistance, impact strength in the thermoplastic among the top;
2) good finishing and adhesion to the cover film;
3) high dimensional stability;
4) will be the installation of the components are integrated into a single unit;
5) the installation of the components are integrated into a single unit;
6) the installation of the components are integrated into a single unit;
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5) very flexible application of design and processing;
6) low coefficient of linear expansion and low coefficient of thermal expansion.
AIEPC and alloy products:
High-performance PC/ABSA2200 alloy material has high impact resistance, excellent weather resistance and matte effect, which can be applied to car audio and DVD systems, automotive instrument panels and other components.
Electroplating grade PC/ABSA2200MP has outstanding plating effect and good low-temperature resistance, which can be applied to plating parts such as automobile handles.