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Innovations enhance bottle output, quality

To meet the preferences of two different markets, Semopac's Montreal plant uses a quick mold change technology from Uniloy Milacron that gives it the production flexibility to make polycarbonate bottl...


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February 1, 2001 by Michael Legault

Hormel Foods has begun to package its Chi-Chi's brand salsa in a 64-oz PET container. The salsa, which is filled at 200F, was previously packaged in a multilayer polypropylene/EVOH container.
Hormel Foods has begun to package its Chi-Chi's brand salsa in a 64-oz PET container. The salsa, which is filled at 200F, was previously packaged in a multilayer polypropylene/EVOH container.

To meet the preferences of two different markets, Semopac’s Montreal plant uses a quick mold change technology from Uniloy Milacron that gives it the production flexibility to make polycarbonate bottles with handles, which are preferred in Ontario, and without handles, which are favored in Quebec. The technology, incorporated into the Uniloy Milacron Liberty RSI 3500PC machine, allows molding and tool changeover in under four hours. The machine also provides automated flash removal and neck finishing. A 27 in. x 30 in. platen area and large diameter tie bars makes the machine ideal for higher tonnage needed to mold large polycarbonate containers.

For injection-stretch blow molding, several companies have recently announced services aimed at reducing design and prototyping time for preforms. Schmalbach-Lubeca, Plastic Containers USA (Manchester, MI) has state-of-the-art, prototyping capability for injection-molded PET preforms. The new process enables creation of production quality, prototype preforms in approximately two weeks, significantly reducing turnaround time, which typically runs between six to eight weeks for traditional, non-production quality preforms. The PET preform is used in conjunction with stereolithography (SLA) to produce a container protoytpe. The process allows packagers to produce custom shaped and finished containers in a much shorter time.

Novapak Corporation (Eatontown, NJ) has launched its second generation Universal Preform Program, which allows customers to obtain custom-made bottles and containers at reduced cost. The process uses large cavitation preforms to produce a fully customized bottle or container tool. The estimated cost for a typical custom tooling program, with a minimum production run of 100,000 units, is US$17,500, compared with an US$80,000 tooling investment required by most blow molders with existing preform tooling.

A significantly growing market exists for blow-molded bottles used to package personal-care products such as shampoo, skin-care lotions, perfumes and other toiletries. One major beauty products company estimates that as much as 95 percent of its products are packaged in plastic, compared with 60 percent 10 years ago. HDPE and PET are the two main materials used for personal care packaging. Statistics provided by Freedonia Group show the use of HDPE in personal care bottles has grown 45 percent over the past decade. Use of PET in personal care bottles has jumped nearly 70 percent over the last six years. Growth has been so dramatic that Eastman Chemical Co. has launched a new line of clear, colorable PET resins, Elegante, specifically for the cosmetics market. The main characteristics of Elegante PET are its easy processability and slow crystallization, which permits part ejection from the mold at a higher temperature.

HOT-FILL APPLICATIONS TAKE OFF

Over one-half of all hot-fill food containers are now made in plastic, primarily sports drinks, juices and tea. These products are all filled at temperatures below 185F. The portion of the market that is filled above these temperature–pasta sauces, jams, soups and other products–has remained largely out of the reach of plastic containers, but this is changing.

Container design and innovations are opening up the hot-fill market for plastic. Food processor Hormel Foods has begun selling its Chi-Chi’s brand salsa in a PET container, the first salsa to be packaged in PET. The 64-ounce, 63 mm, wide-mouth container is made by Schmalbach-Lubeca, Plastic Containers USA. The company had been using a multilayer, polypropylene/ethylene vinyl alcohol copolymer container for its 64-ounce club store size, but was not satisfied with the transparency.

“For a long time, a multilayer container was our only plastic option due to hot-fill temperature requirements of approximately 200F,” says Steve Kretschmar, product manager, Chi-Chi’s.

Schmalbach-Lubeca worked with Hormel to develop a clear, single-layer PET container that would meet all of the design, structural and hot-fill requirements. The container is designed with a rounded base that has a rigid circumference and a flexible centre which draws up into the container when the vacuum is pulled. A ridge built into the edge of the circumference prevents the vacuum from creeping up the sides of the container.

A few companies have tinkered with their food formulas in order to allow them to fill in plastic at a lower temperature and avoid such investment costs, but many food processing managers do not like to change long-standing formulas. Nonetheless, it appears time is on the side of plastic in hot-fill applications.