Stretched injection blow molding

PET s broad range of properties make them ideal replacements in certain applications for such metals as die-cast aluminum or zinc also in thermoset switches, relays, sensors, etc. Applications include packaging (particularly stretched injection blow molded beverage bottles and film), appliances, electrical/electronics, etc. PET finds applications in such diverse end uses as fibers for clothing, films, botdes, food containers, and engineering plastics for precision molded parts.118-120 A wide range of applications is possible because of the excellent balance of properties PET possesses and because the degree of crystallinity and the level of orientation in the finished product can be controlled. 

Hgure 8.11 Example of stretched injection blow molding using a rod (left) and example of stretched injection blow molding by gripping and stretching the preform... 

Example of stretched injection blow molding using a... 

Barex The trade name for BP Chemical International s (Sohia Division) family of acrylonitrile (AN) copolymerized styrene plastic. It was the first technically and commercially successful carbonated beverage bottle to be produced and was used in producing the first Coca-Cola stretched injection blow-molded bottles. See Coca-Cola bottle, barium oxide (BaO) A white to yellow powder that melts at 192°C. It forms a hydroxide with water and is used as a dehydrating agent. Also called barium monoxide or barium protoxide. 

Coca-Cola bottle Acrylonitrile-styrene (AN) plastic was used in 1958 to produce the first commercial stretched Coca-Cola carbonated beverage bottles (two-liters). The glass pinch bottle debuted in 1915 was resurrected out of plastics. Production was by Monsanto Co. using Barex plastic from Sohia of BP Chemical International and DuPont s stretched injection blow-molding process. After production started in about eight plants on the East Coast, AN was banned by the U.S. Food and Dmg Administration because of possible food contamination, even though... 

Coor s beer bottle During the mid-1950s, Coor sBeer Company in Colorado almost used commercially stretched, injection blow-molded bottles. It would have used the blow-molding injection with rotation process. Unfortunately, it was using acrylonitrile-styrene plastic (AN-styrene from Barex plastic from Sohia of BP Chemical International) (DVR project), which was banned by the FDA. Many years later it was approved for use. See acrylonitrile-styrene plastic blow molding, injec-tion-with-rotation blow molding, stretched Coca-Cola bottle. 

PETs are extensively used in such products as bottles and films. Stretched-injection blow-molded bottles are used for nearly all two-liter carbonated beverage containers. PET is also used for packaging foods, cosmetics, and household chemicals (see Figs. 6-7 and 6-8). With changes in formulation, surface treatment, and processing— from unoriented to bioriented— PET films can produce variations in optical, mechanical, physical, and surface properties. They are used in liquid-crystal displays, metalized photocopier belts, motor and wire insulation, for holographic reproduction, in magnetic tapes and discs, and other uses. Aluminized PET film with nylon fabric set the world s record for altitude in a manned hot-air balloon at 59,500 m (65,(KX) ft.), in 1988. 

Figure 6-7. Different-shaped PET stretched-injection, blow-molded bottles.

Figure 7-64. A schematic of stretch injection blow molding.

How is orientation introduced into an injection blow molded part Compare this to orientation in a stretch blow part ... 

The multilayer film is formed by injection molding, co-injection blow molding, co-injection stretch-blow molding or co-extrusion blow molding techniques. 

There are four different blow molding processes extmsion blow molding, injection blow molding, stretch blow molding and the less frequent dip blow molding. 

Films can be produced using chill roll casting. Injection blow molding and stretch blow molding are used to produce bottles. PET is also used in extrusion coating, and PET sheet is often thermoformed. 

An alternative approach is to cool the parison completely after the injection molding step, and remove it from the core rod. The parison can then be stored or shipped elsewhere before blow molding. In this case, it is necessary to reheat the parison to the desired temperature before the blow-molding step. This approach is seldom used for ordinary injection blow molding, but is not uncommon for stretch blow molding, which is discussed in Section 12.4. 

In either extrusion or injection blow molding, the polymers in the containers are oriented because of the radial stretching that takes place in the blowing step. If desired, the mechanical or barrier properties of the material can be maximized by producing biaxial orientation, stretching the preform vertically as well as horizontally, using stretch blow molding. 

Technology to successfully produce multilayer injection blow molded bottles is much newer than that to produce multilayer extrusion blow molded bottles. Heinz Inc. s ketchup bottle was the first U.S. example (Fig. 12.22). The use of PET bottles made by coinjection blow molding has grown rapidly. As is the case for coextrusion blow molding, the key is production of the parison. Once the multilayer parison is produced, the remainder of the process is essentially the same as for single layer materials. Even stretch blow molding can be used. 

Br onns are molded in a special machine and immediately, while still hot and without losing orientation, transferred first to a heat conditioning station and d en to a blowing stmion where the preforms are stretched (optional) and blown. main difference between this method and injection blow molding is that the... 

Injection stretch blow molding (ISBM) is an extension of injection blow molding with two modifications (a) the preform is significantly shorter than the bottle and (b) a stretch rod is used to stretch the preform in the axial direction. This process became known in the blow molding industry with the introduction of plastic or PET soft drink bottles. 

This is the primaiy processing technique used to fabricate hollow plastic objects, particularly bottles, which do not need a very uniform distribution of wall thickness. It is a secondary shaping technique that inflates the preprocessed plastic (usually extruded) against the inside walls of the mold with a blow pin. In addition to extrusion blow molding, injection blow molding and stretch blow molding are commonly employed. With most polymers, especially when the product size is... 

In blow molding, bottles or jars are produced by blowing, with air, a molten previously formed part. There are three types of blow molding extrusion blow molding (EBM), injection blow molding (IBM), and injection stretch blow molding (ISBM). 

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