Polycarbonate injection molding

Reinforced Polycarbonate Injection Molding and Extrusion Materials, ASTM D 2848... 

Fig. 5. Polycarbonate injection molding. DSC curves of stressed and relaxed samples.

NUMERCIAL SIMULATIONS OF RESIDUAL STRESSES IN POLYCARBONATE INJECTION MOLD PARTS... 

The effects of replication and molecular orientation on the optical properties of polycarbonates injection molded parts with the microscopic v-groove features have been examined on various injection molding conditions and different cavity shapes. For TD and thinner wall of the injection molded parts, the mold temperature had significant effect on the replication. It was clarified that the optical properties closely depended on the replication in compared with the molecular orientation. 

The major use of 4-cumylphenol is as a chain terminator for polycarbonates. Its use in place of phenol gives a polycarbonate with superior properties (33). Eor a low molecular weight polycarbonate used for injection-molding appHcations, the use of 4-cumylphenol as a chain terminator significantly lowers the volatiHty of the resin. Other uses of 4-cumylphenol include the production of phenoHc resins, some of which have appHcations in the electronics industry (34). Another appHcation of 4-cumylphenol involves its reaction with ethylene oxide to form a specialty surfactant. 

In this section, we examine fibrillation behavior of a polycarbonate (PC)-TLCP blend by injection molding. 

In general, properties of polyether sulfones are similar to those of polycarbonates, but they can be used at higher temperatures. Figure 12-6 shows the maximum use temperature for several thermoplastics. Aromatic polyether sulfones can be extruded into thin films and foil and injection molded into various objects that need high-temperature stability. 

Schmidt, L. B., et al., Injection Molding of Polycarbonate Compact Disks Relationship between Process Conditions, Birefringence, Block Error Rate, SPE-ANTEC, 1992. 

We routinely manufacture polycarbonate products by injection molding, blow molding, extrusion, and thermoforming. Injection molding is the most common processing technique. 

Polycarbonate can be readily injection molded. Polycarbonates typically require only a short injection molding cycle time, because the polymer flows into the mold easily and solidifies rapidly. We injection mold polycarbonate to produce a wide variety of commercial goods, including compact disks, jewel cases, aircraft windows, kitchen utensils, and clear refrigerators drawers. Polycarbonates are also found in a wide range of disposable medical devices, such as the flow locks on intravenous tubes and the hard, disposable components of dialysis machines. Impact resistant polycarbonate is used to manufacture sports and other safety helmets. Glass fiber reinforced polycarbonate is used in the housings for power tools. 

Why are polycarbonate resins easy to process via injection molding ... 

What molecular process creates the birefringence effect seen in some injection molded polycarbonate parts ... 

Several injection-molded polycarbonate (PC) disks used in a consumer product (i.e., a clock face) were analyzed, because the disks contained defects. The defects were analyzed initially and imaged using a stereoscopic microscope fitted with a digital camera. The defects present on the samples were easily identified. It was noticed that the defects were located on different regions of the molded part. This important observation eliminated a systematic problem or an imperfection at a specific site on the mold surface as the cause of the defect. 

The pits are generally embossed into the substrate (polycarbonate or polymethylmethacrylate) layer by an injection-molding process, and are used to indicate whether a data bit is 0 or 1. An aluminum or silver layer provides a reflective surface, and is protected from corrosion and damage by a radiation-cured acrylate (lacquer) layer, onto which a label is usually printed.197... 

The brominated phosphate is an efficient flame retardant for polycarbonate resin. UL-94 ratings of V-0 with oxygen index values of greater than 40 are obtained. Polycarbonate resin containing brominated phosphate processes with greater ease than resin containing brominated polycarbonate as measured by injection molding spiral flow measurements. The heat distortion temperature is reduced... 

The three flame retardants are compared in Table VI. Brominated phosphate disperses readily in the resin presumably due to its high solubility in aromatics. Resin containing brominated polycarbonate is relatively difficult to process as measured by injection molding spiral flow measurements. 

In Table XII are presented data for electroless nickel on injection molded polycarbonate. The coated sample shows slightly more smoke smoldering and somewhat less smoke flaming. A very thin metal coating (< < 1 mm) has minimal effect on polycarbonate. 

Table XII. NBS Smoke Chamber Data for Electroless Nickel on Injection Molded Polycarbonate (1 /8 inch thickness)...

Random copolymerization of one or more additional monomers into the backbone of PET is a traditional approach to reducing crystallinity slightly (to increase dye uptake in textile fibers) or even to render the copolymer completely amorphous under normal processing and use conditions (to compete with polycarbonate, cellulose propionate and acrylics in clear, injection molded or extruded objects). 

Fig. 6.8. Fracture toughness, K, of short glass fiber-thermoplastics injection molded composites as a function of weight fraction of fiber, fVr. (O) and (A) polyethylene terephthalate (PET) matrix ( ) and (A) polycarbonate (PC) matrix. Notches made transverse (O, ) and parallel (A, A) to the mold fill direction,...

For higher throughput applications, injection-molded plastic microtiter plates have served as the formats of choice for automated assay development. Thermoplastics such as polystyrene, polycarbonate, and polypropylene are used for a variety of purposes including storage and assay plates, lids, pipette tips, and Eppendorf PCR tubes. Polystyrene plates are used for cell culture and ELISAs. Polycarbonate reagent bottles are popular, while polypropylene storage plates and PCR tubes are standards. 

Injection molding requires the barrel temperature to be about 350°C with a barrel pressure in excess of 138 MPa. The mold is maintained at 110°C to ensure uniform flow and high definition, and to discourage an uneven index of refraction, birefringence. The CD is about four one-hundredths of an inch (0.5 mm) thick. For prerecorded CDs, the PC is compression-molded on a stamper imprinted with the recorder information. This takes about 4 sec. Once the clear piece of polycarbonate is formed, a thin, reflective aluminum layer is sputtered onto the disc. Then, a thin acrylic layer is sprayed over the aluminum to protect it. The label is then printed onto the acrylic surface and the CD is complete. This process is described later in greater detail. 

Injection molding is employed to stamp out copies of the master discs from polycarbonate. The molded polycarbonate discs are cooled and hardened quickly, within about 4—6 sec, and evenly. The dye layer is then applied. The applied dyes are often proprietary and continually modified in an attempt to get a better dye. The dye must be compatible with the system and adhere to the polycarbonate base. It is applied by spin coating i.e., the disc is spun and the dye is sprayed onto the surface. The dye is then dried and cured. 

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