Blow-molding market

There are three main processes used by the blow-molding industry to supply containers and hollow products to the blow-molding market injection blow molding, extrusion blow molding, and stretch blow molding. 

PET is the second largest volume resin used in the blow-molding industry. HDPE is first, with a 57% share of the blow-molding market today. PET has 33% of the blow-molding market and is growing. Thus, all the other resins combine for 10% of the blow-molding market. 

The HMW-HDPE with a bimodal MWD is primarily used in film applications to fabricate grocery bags (T-shirt bags) and other merchandise bags. However, polyethylene with a bimodal MWD is also used in premium blow-molding markets and high-pressure pipe applications such as natural gas distribution pipe. 

Blow-molded products represent the biggest use of HDPE resins, at around 40%. Packaging appHcations account for by far the greatest share of this market. These include such products as botties (especially for milk, juice, and soap), housewares, toys, pails, dmms, and tanks. Expected aimual average growth rates for these appHcations are about 5—6%. Injection-molding products are the second largest appHcation, with approximately 20% of the HDPE market. These products include housewares, toys, food containers, pails, crates, and cases. 

Some time earlier, Eastman-Kodak has been working on a novel polyester as an entry into the important polyester fiber market and had devised a new ahcychc diol, 1,4-cydohexanedimethanol [105-08-5] effectively made by exhaustive hydrogenation of dimethyl terephthalate. Reaction of the new diol with dimethyl terephthalate gave a crystalline polyester with a higher melting point than PET and it was introduced in the United States in 1954 as a new polyester fiber under the trade name Kodel (5). Much later the same polyester, now called PCT, and a cyclohexanedimethanol—terephthalate/isophthalate copolymer were introduced as mol ding resins and thermoforming materials (6). More recentiy stiU, copolymers of PET with CHDM units have been introduced for blow molded bottie resins (7). 

PEN film for audio- and videotape and various electronic appHcations and blow molded PEN containers for hot-fill appHcations are already being marketed in Japan. NDA is unlikely to ever become as inexpensive as terephthaUc acid but novel NDA-based polyesters will become available if a market need exists. One example could be the experimental polyester PBN (Celanese Corp.) this is the NDA analogue of PBT, poly(l,4-butylene naphthalene-2,6-dicarboxylate) [28779-82-0]. It has a high rate of crystallization, faster even than that of PBT, and its combination of physical properties is weU-suited for injection molding. 

Hot-Fill Applications. A growing market for blow-molded containers is the so-called hot-fill market. This covers such items as tomato ketchup, pasteurized fmit juices, and salad dressings that are packaged while sti11 hot. The PET blow-molded bottie suffers from its relatively low T (70°C) which results in severe bottie distortion if the temperature of the contents approaches T (the maximum fill temperature is 60 65 C). A brief heat... 

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... 

Blow molding is widely used to make polymeric containers of all sorts. In many markets blow molded plastic products have largely displaced such traditional materials as glass, ceramics, or metal. The inherent advantages of polymeric containers include their light weight, clarity, toughness, and versatility. —... 

A significant fraction, more than 25%, of the low-density polyethylene (LDPE) (Sec. 3-14a) produced by radical polymerization consists of various copolymers of ethylene. LDPE has come under increasing economic pressure in recent years because of a combination of factors [Doak, 1986]. High-density polyethylene (HDPE) has displaced LDPE in applications such as blow-molded bottles and thin films where the increased strength of HDPE is preferred over the clarity of LDPE. Linear low-density polyethylene (LLDPE) (Sec. 8-1 lc) competes effectively with LDPE in terms of both cost and properties. New producers of ethylene have entered the LDPE market because of a lack of alternatives for their feedstocks. Many LDPE producers use copolymerization as a strategy to obtain products more resistant to displacement by HDPE and LLDPE. 

Hot-Fill Applications. A growing market for blow-molded containers is the so-called hot-fill market. This covers such items as tomato... 

Molding Applications. Molding is accomplished by three different methods blow molding, injection molding, and rotational molding, although the use of LDPE in these applications has been declining since the introduction of LLDPE on the market. 

LLDPE resins formulated for the blow molding applications have superior environmental stress-cracking resistance and low gas permeability. These features opened new bottle markets where such properties are important. A large variety of molded articles with a complex configuration... 

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