Blow-molding bottle

Molding includes bottle blow molding, and the continued move toward PET for use in soft drink and water bottles depresses growth slightly, although the trend remains positive. 

Polystyrene was the first synthetic polymer used for blow molding during World War II and polyethylene was the first material to be implemented in commercial applications. Until the late 1950s, the main application for blow molding was the manufacture of PE-LD articles such as squeeze bottles. Blow molding produces hollow articles that do not require a homogeneous thickness distribution. Today, PE-HD, PE-LD, PP, PET, and PVC are the most common materials used for blow molding. 

Form/Fill/Seal Machine Targets Bottle Blow Molding, MP, June 2003. 

Example of injection molding production bottle blow molding plant... 

Polybutadiene Polypropylene bottles, blow molded squeeze Polyethylene, low-density bottles, break-resistant lonomer resin bottles, hydrofluoric acid Ceres n... 

Figure 4.12. Distribution of energy use in HDPE bottle blow molding [29].

FIGURE 4.8 A diagram of the bottle blow molding process. 1. Heated parison, 2. Mold closing. 3. Blowing air into mold 4. Cooling and opening mold. 5. Molded bottle. 

In injection blow molding, the rtielt is injected into a parison cavity around a core rod (Figure 1.4). The test-tube shaped parison, while still hot, is transferred on the core rod to the bottle blow mold cavity where the bottle is blown and cooled. Injection blow molding is generally used for bottles less than 0.5 liter in size. This type of blow molding allows for a scrap free product and for design of intricate shapes such as tamperproof closures. It is impractical for containers with handles. 

Poly(vinyl chloride) + poly(vinyl chloride-co-acrylate), PVC + VC/A poly(vinyl chloride) + chlorinated polyethylene, PVC + PE- C, poly( vinyl chloride) + poly(acrylonitrile-co-butadiene-co-acrylester), PVC + ASA. Applications semifinished goods, foils, plates, profiles, pipes, fittings, gutters, window frames, door frames, panels, housings, bottles, blow molding, disks, blocking layers, fibers, fleeces, nets. 

In bottle blow molds, there will be a hardened steel insert with a land of 0.076-0.13 mm (0.003-0.005 in.), a relief angle of 20° with a total depth of 0.76 mm (0.030 in.) measured from the inside bottom of the blow mold, and then a 45° cut to the bottom of the relief section in the pinch-off area. Normally, the total of this relief section will be 90% of the parison wall thickness to be pinched (see Fig. 31). This design will also minimize residual flash. It is best to design the pinch land at 0.25-0.4 mm (0.010-0.015 in.) and have metal to remove, if the pinch is not adequate. 

Polylactic acid resin pellets should be dried 4-6 hours to less than 400 ppm prior to blow molding into bottles. Blow molded preforms are injection molded with standard PLA injection molding conditions. 

Polyethylene terephthalate (PET) bottles were commercially introduced to the market place for the first time in 1976, by Pepsi Cola. The bottles were supplied by Amoco from their Seymour, IN plant, blown on Cincinnati Milacron machines, from preforms molded in molds supplied by Broadway Mold in Dayton, OH. The PET bottle introduction coincided with the FDA-forced withdrawal of the Monsanto supplied Coca Cola ANS bottles, making it the only plastic carbonated soft drink (CSD) bottle on the market. Fig. 33.3 shows a Continental Can Company (CCC) bottle produced in the company s first PET bottle blow molding plant in 1977. A second important milestone was the introduction in Japan by Yo-shino in 1982 and in the United States by Monsanto in 1985, of bottles suitable for hot filling, a typical filling method for perishable beverages like juices. The Yoshino and the Monsanto bottles are shown in Eig. 33.4 and Fig. 33.5, respectively. 

This method is slow because of the multiple operations on a shuttle machine. The heat of extmsion sterilizes the bottle, which is not readily achieved after molding. Blow-mold/fill/seal systems are used commercially for beverages and for pharmaceutical packaging. 

In injection blow mol ding, a parison is injection molded onto a core pin the parison is then rapidly transferred via the core pin to a blow mold, where it is blown by air into an article. This process is appHed to smad and intricate bottles. 

Soft-drink bottles made from poly(ethylene terephthalate) (PET) are usuady made by stretch-blow mol ding in a two-step process. Eirst, a test-tube-shaped preform is molded, which is then reheated to just above its glass-transition temperature, stretched, and blown. Stretching the PET produces biaxial orientation, which improves transparency, strength, and toughness of the botde (54,56). A one-step process is used for many custom containers that are injection stretch-blow molded. 

Styrene-based plastics are used somewhat in blow mol ding but not as much as linear polyethylene and PVC. HIPS and ABS are used in specialty botdes, containers, and furniture parts. ABS is also used as one of the impact modifiers for PVC. Clear, tough bottles with good barrier properties are blow-molded from these formulations. 

Polyvinyl Chloride (PVC) 1940 M-H VG G G G Extrusion, injection, rotational, slush, transfer, compression, blow mold Pipe conduit and fittings, cable insulation, downspouts, bottles, film... 

HDPE is important for producing bottles and hollow objects by blow molding. Approximately 64% of all plastic bottles are made from HDPE. Injection molding is used to produce solid objects. Another important market for HDPE is irrigation pipes. Pipes made from HDPE... 

Polyvinyl chloride (PVC) is one of the most widely used thermoplastics. It can be extruded into sheets and film and blow molded into bottles. It is used in many common items such as garden hoses, shower curtains, irrigation pipes, and paint formulations. 

There are also bellows-style collapsible plastic containers such as blow molded bottles (jars) that are foldable. As shown in Figs. 3-16 and 3-17, the technology of foldable... 

Thin wall plastics are used to hot fill (injection and blow molded bottles, thermoformed containers, etc.) without sagging during filling and maintaining mechanical properties such as impact strength and stiffness in temperatures from at least —40°F to 250°F (—40°C to 120°C). Plastic used includes special grades of PEN, PET, PP, PS, and PVC. 

A similar problem is presented by vehicle tires and certain blow molded bottles, which must be virtually impermeable to air and other gases. An example of the use of a very impermeable elastomers is butyl rubber. Because of its impermeability to gases, butyl rubber is used as a roof coating. With plastic bottles, different layers of both coinjected and coextruded plastics (Chapter 8) can be used to fabricate the bottle to make it impermeable to different vapors and gases depending on the barrier plastic included. 

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