making+plastic

__Making Plastics__ James Powers, Alexandra Serino, Irene Carrozza, Melanie Collins and Sean Rider



There are a few different materials that can be used to produce plastic bottles. These are polyethylene, polypropylene, and polyvinyl chloride. For the production of large cold drink bottles, polyethylene terephthalate (PET) is used. These bottles are designed so that the carbonation in a soft drink cannot escape. Millions of gallons of water are used in the production of water bottles.

Introduction

Plastic bottles aren't made immediatly into their final forms. They are first made into little bottle-like containers that sort of look like test tubes, called preforms. the PET particles and the rest of the ingriedients of plastic combined with some recycled plastic are mixed and melted in a oven that heats to 600 degrees fahrenheit making liquid plastic that is put into molds to make the preforms. This whole process takes a matter of minutes because there are built-in cooling systems in the molds that hold the preforms for a second before shooting them onto a conveyor belt that takes them on to the next step. The preforms are put into a different machine that heats them and then uses a metal bar and air pressure shooting into the preform to form it into the bottles final shape, cold water is used to cool and almost instantaneously set the bottles before they are filled and packaged and all that. Here's an interesting fact, the only recycled plastic that is used to make new plastic bottles is plastic from leftover bottles that were unused. This is for hygene purposes, and since there isn't that much left over ususally 10% of the plastic is recycled materials. Plastic films can make a large category of materials that can be simple or complex depending on the particular product or pakage being made. Also, different film can be made with different resins. Plastic film also can be clear or colored, printed or plain, single- or multilayered. It can be combined with other materials like aluminum or paper. Many studies prove that it can be safer to drink tap water rather than bottled water. This is because there are more harmful toxins used in the production of plastic bottles such as styrene and benzene, which not only increase pollution in the air, but can cause respiratory problems and even cancer. Plastic is made of petroleum, which is a non-renewable resource that requires the constant extractions of fossils. By decreasing the amount of water bottles we use, we can limit our dependence on oil. Oil distributors, such as Exxon, ConocoPhillips, and British petroleum, are directly linked to the production of PET plastic water bottles. About 80% of the PET (Polyethylene terephthalate) produced in the US ends up in Nestle, Coca-Cola, or Pepsi plastic bottles. There are multiple steps to the production of PET bottles. The supply chain for PET plastic bottles begins with two streams which produce PET's primary raw materials, terephthalic acid (PTA) and monoethylene glycol (MEG). These two streams come together when PET is actually produced in a factory through the chemical reaction between MEG and PTA. Terephthalic acid is produced using paraxylene, which is very similar to oil and is derived from crude oil through a refining process at oil and petrochemical refineries. Monoethylene glycol is also derived from crude oil, although its main raw material is ethylene. Ethylene is more widely produced than ethylene. Once the PTA and MEG have been produced, they are used to make polyethylene terephthalate. The bottle grade PET resin is then sold to companies than convert the resin into plastic bottles. Companies that buy PET resin and then turn it into plastic bottles are known in the industry as converters. This category of companies include companies that make the plastic bottles then sell them and the beverage companies themselves who make their own bottles. Few people realize that plastic bottles are composed of chemicals and fossil fuels. Plastic is made from non-renewable resources and when they are produced, a large amount of toxic chemicals are released into the water supply and air. The industry that produces the plastic is a dirty one and is ranked as a top polluter. Approxiamately 1.5 million barrels of oil- enough to run 100,000 cars for a full year- are used to make plastic bottles, whiile transporting these bottles uses even more oil. As previously mentioned, drinking out of plastic water bottles can be unsafe because of the BPA and other contaminants. Until an environmentaly "force field" is invented to contain water or other drinks, we will need to stick with glass and stainless steel such as kanteens or sport type water bottles. These bottles are certified to be safe without any chemical coating. (Alternatives for plastic bottles.) Certain plastics (numbered 3,6, and 7) contain BPA that can be linked to cancer when heated. Many plastic bottles have one of these numbers on the bottom. (Mostly sports type bottles aside from Poland Spring or Aquafina.) 

 Blow Molding Processes

There are 4 types of blow molding processes used to create plastic containers including plastic bottles. These processes are extrusion blow molding, injection blow molding, stretch blow molding and reheat and blow molding. Extrusion blow molding is the simplest type of molding used. A hot tube of plastic material is dropped from a extruder and then caught in a water cooled mold. The molds are closed and air is blown through an opening in the mold (the neck). When the injected plastic touches the mold, it freezes into the shape of the container. Many shapes, sizes and necks are available through this process. A variety of shuttle, reciprocating and wheel style machines are used in this process. The type of machine used depends on the volume of the production. This particular process can produce containers in many materials including HDPE, LDPE, PP, PVC, BAREX, P.E.T., K resin, P.E.T.G. and polycarbonate. In injection blow molding, the hot plastic material is first injected into a cavity where it encircles the blow stem. This is how the neck of a bottle/ jar or jug is created.The gram weight is also established here. This material is then carried to the next station on the machine. It is formed into the finished product by extrusion blow molding. The materials used in injection blow molding include HDPE, LDPE, PP, PVC and BAREX.     <span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">      <span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">There are two different stretch blow molding processes. In one of the processes the machinery that makes the entire container uses injection molding to mold a preform. The preform is transferrred to another station on the same machine. There it is blown and ejected from the machine. This way of blow molding is only reasonable for extremely high volume runs of items, including narrow mouth water bottles. The second stretch blow process is also called reheat and blow. A preform is produced through injection molding by an company outside of the company producing the bottle rather than the preform and final product being molded during one process. In both methods of stretch blow molding the preform is mechanically stretched with a "stretch rod" during the molding. This allows the production of containers that are lightweight with very high impact resistance and sometimes superior chemical resistance. Also, materials that can be stretch blown include P.E.T, polypropylene etc. There are several factors that help decide which process to use when making plastic containers such as bottles. The appearance, type of resistance, and cost/benefit relationship desired are all considered. In addition, the cost of the tooling and size of the production runs are important in the decision. For the most part, extrusion blow molding seems to be the easiest, most efficient and least expensive type of production. The other processes can be very costly and are generally only reasonable for high volume production.

Dangerous Chemicals

<span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif"> <span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">Make sure to drink out of a bottle that does not leach; check the recycling symbol on the bottle. If it is a #2 HDPE (high density polyethylene), or a #4 LDPE (low density polyethylene), or a #5 PP (polypropylene), your bottle is fine. The type of plastic bottle in which water is usually sold is usually a #1, and is only recommended for one time use. Do not refill it. It is better to use a reusable water bottle, and fill it with your own filtered water from home. This will also keep these single-use bottles out of the landfill. Colored, hard plastic lexan bottles made with polycarbonate plastics and identified by the #7 recycling symbol, may leach BPA. Bisphenol A is a xenoestrogen, a known endocrine disruptor, meaning it disturbs the hormonal messaging in our bodies. Synthetic xenoestrogens are linked to breast cancer and uterine cancer in women, decreased testosterone levels in men, and are particularly devastating to babies and young children. BPA has even been linked to insulin resistance and Type 2 Diabetes. most plastic baby bottles and drinking cups are made with plastics containing Bisphenol A. BPA is a common chemical used to strengthen polycarbonate plastics in the water bottles. ( There has been harm done to babies caused by drinking out of baby bottles and sippy cups containing BPA.) Many water bottles are now being made without the use of BPA, such as Nalgene. An alternative copolyester is being used called Tritan. More on BPA…

<span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif"><span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">  For years, some of the most popular reusable water bottles have been made from a hard, clear plastic called polycarbonate. The problem is that one of the key components of polycarbonate is the endocrine-disrupting chemical bisphenol-A (BPA). A growing body of research has shown that polycarbonate bottles can leach bisphenol-A into the liquid they contain, making the hard plastic containers toxic water bottles. Bisphenol-A mimics the female hormone estrogen and has been shown to cause defective cell division during development, even at extremely low doses. A growing number of studies have linked bisphenol-A to other kinds of reproductive and developmental damage, as well as breast cancer in women and prostate cancer in men. Recent research has also suggested it may play a role in the development of Alzheimer's disease and even diabetes, because of its effect in causing insulin resistance. The demand from consumer health and environmental groups for regulatory action against BPA prompted the federal government to fast-track a screening assessment of BPA in 2007. That assessment was finally released April 18, 2008 and declared that BPA was CEPA-toxic under the provisions of the Canadian Environmental Protection Act. BPA was declared to be a substance posing a danger to both human health and the environment. Health Minister Tony Clement also announced that following a 60-day comment period, the government would introduce legislation to ban the sale and importation of polycarbonate baby bottles in Canada. Even before the announcement, several retail chains, led by Mountain Equipment Co-op, had taken polycarbonate water bottles off their shelves because of health concerns over BPA. Retailers also removed polycarbonate baby bottles. In addition, the biggest manufacturer of polycarbonate water bottles, whose products are sold under the Nalgene name, announced that it would no longer be making polycarbonate bottles, opting for a new plastic polymer instead. However, the government has not taken any action to limit the sal e of polycarbonate water bottles and has not offered any advice to consumers other than to suggest that pregnant women should not put hot water or other liquids in their polycarbonate water bottles. Making it even more confusing for consumers, at least one outdoor equipment store in Manitoba announced that it was putting the toxic water bottles bottles back on store shelves. Even though major retailers won’t be carrying them, it’s likely that some stores will still stock polycarbonate bottles, especially if cheap imported bottles move in to replace those Nalgene used to make. The best choice for a re-useable water bottle is one made from stainless steel. They can handle most liquids, can be cleaned easily and, most important, don’t leach any chemicals. Aluminum bottles are also an option but not just any aluminum bottles. Some aluminum bottles have an epoxy resin lining, which can also leach chemicals, including BPA. Two bottles that have shown no leaching in independent tests are Laken and Sigg. Both use proprietary formulas for their coatings. If you want a plastic bottle, the safest bottles to use are made of high-density polyethylene, or HDPE (identified by the number 2 in the recycling triangle symbol on the bottom), low-density polyethylene, or LDPE (#4) or polypropylene (#5). Nalgene makes a number of styles and sizes of bottles made from UVPE, which is a version of HDPE designed to withstand UV radiation from sunlight, which can cause plastic to deteriorate over time. Nalgene and another major manufacturer, Camelbak, are both planning to bring out a new line of bottles made of a plastic polymer from Eastman called Tritan copolyester. It’s designed to replace polycarbonate and will be similar, providing hard plastic bottles that can be clear or coloured. It also claims to be BPA- and phthalate free. <span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">However Tritan copolyester hasn’t been independently tested yet to verify the claims or rule out any other chemical leaching. <span style="COLOR: #003ff0; FONT-FAMILY: 'Trebuchet MS', Helvetica, sans-serif">The new plastic, expected to be on the market this year, will also make it a bit trickier for consumers to navigate the recycling numbers on the bottom of the bottle. Like polycarbonate, it will carry the number 7 in the recycling triangle (#7 is a catch-all category for a number of plastics not otherwise identified). So potential buyers will have to make sure they’re buying the new material and not polycarbonate. Nalgene and Camelbak will undoubtedly be marketing the new bottles as BPA-free, making that job a little easier.

<span style="FONT-SIZE: 26pt; COLOR: blue; FONT-FAMILY: 'Eras Light ITC'; mso-bidi-font-family: Gautami; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">Bibliography 1. http://www.wisedude.com/science_engineering/bottles.htm 2. http://www.youtube.com/watch?v=T01i_vp2mJE 3. http://www.packagemachinery.com/film_choices.html 4. http://www.thegreenguide.com/reports/product.mhtml?id=49 5. http://www.polarisinstitute.org/oil_in_my_water 6. [|BPA] 7. http://www.kitchentablemedicine.com/plastic-water-bottles-healthy-alternatives/ 8. http://www.sciencedaily.com/releases/2008/04/080422114734.htm- 9. http://www.plasticbottle.com/techinfo/article.html 10. http://trusted.md/blog/vreni_gurd/2007/03/29/plastic_water_bottles 11. [|frequently asked questions] 12. [|water quality report] 13. http://www.treehugger.com/files/2007/07/reasons_to_ditch_bottled_water.php 14. http://www.consumersearch.com/water-bottles 15. [|http://www.waterbottlers.com/] 16. http://www.leas.ca/On-the-Trail-of-Water-Bottle-Toxins.htm