PET bottle

In 1992, PET has progressively completely replaced another synthetic pol5oner - polyvinylchloride (PVC) used since 1958 instead of glass - for the packaging of mineral water. 

PET plastic has good barrier properties against oxygen and carbon dioxide. Therefore, it is utilized in bottles for mineral water. PET is commonly used to package soft drinks, water, juice. 

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Economic Aspects. The total world market for PET botde resia is growing at a rapid rate. One survey iadicates that the aimual growth rate worldwide exceeded 15% per annum over the years 1990—1995. Another article (124) states that the global consumption of PET grew at 19% duriag 1992 to a world total of 1,720,000 t. Much of this growth is due to the demand for PET bottle resia. Table 1 shows the world PET consumption by end use ia 1992. 

Vinylidene Chloride Copolymer Latex. Vinyhdene chloride polymers are often made in emulsion, but usuaUy are isolated, dried, and used as conventional resins. Stable latices have been prepared and can be used direcdy for coatings (171—176). The principal apphcations for these materials are as barrier coatings on paper products and, more recently, on plastic films. The heat-seal characteristics of VDC copolymer coatings are equaUy valuable in many apphcations. They are also used as binders for paints and nonwoven fabrics (177). The use of special VDC copolymer latices for barrier laminating adhesives is growing, and the use of vinyhdene chloride copolymers in flame-resistant carpet backing is weU known (178—181). VDC latices can also be used to coat poly(ethylene terephthalate) (PET) bottles to retain carbon dioxide (182). 

Poly(ethylene terephthalate) (PET) bottles have been used for some time as an alternative to glass and aluminum. At first one-way bottles ia different sizes were used returnable PET-botfles of reasonable quaUty have been marketed. In the future, returnable PET-botfles will be used. The first examples of total production lines have been exhibited, ie, blow-form-fill-seal ia an extra superblock constmction. 

In the late 1970s several developments occurred causing renewed interest in poly(ethylene terephthalate) as a plastics material. These included the development of a new mouldable grade by ICI (Melinar) and the development of a blow moulding technique to produce biaxially oriented PET bottles. In addition there appeared a glass-fibre filled, ionomer nucleated, dibenzoate plasticised material by Du Pont (Rynite) (see Chapter 26). 

Other estimates placed the film and bottle market to be of a similar size in Japan while globally the bottle market was about 20% of the total. Together with other data this suggests that the fibre and filament market absorbs about 72% of PET capacity, containers about 19%, film about 7% and mouldings 2%. Considerable quantities of PET bottles are, however, recycled into fibres for use, for example, in outdoor clothing. 

PET has the second highest scrap value for recycled materials, second only to that of aluminum.1 A typical PET beverage bottle consists of PET (60 g), polyethylene (1 g), and label and glue (5 g). Therefore, the PET bottle scrap must be separated before the PET can be recycled. The bottles are sorted at a material recovery facility and compressed. The compressed PET bottles are then washed and converted to flake by grinding. The flakes may be converted to pellets in an extruder. The pellets are more suitable for material handling. Currently recycled PET is being used to make food and nonfood containers, straps, sheeting, and... 

Collection costs are quite high because of the low bulk density of PET bottles. 

The principal solvolysis reactions for PET are methanolysis with dimethyl terephthalate and ethylene glycol as products, glycolysis with a mixture of polyols and BHET as products, and hydrolysis to form terephthalic acid and ethylene glycol. The preferred route is methanolysis because the DMT is easily purified by distillation for subsequent repolymerization. However, because PET bottles are copolyesters, the products of the methanolysis of postconsumer PET are often a mixture of glycols, alcohols, and phthalate derivatives. The separation and purification of the various products make methanolysis a cosdy process. In addition to the major product DMT, methanol, ethylene glycol, diethylene glycol, and 1,4-cyclohexane dimethanol have to be recovered to make the process economical.1... 

Contamination problems act as a barrier to the recycling of PET bottle waste. The presence of impurities that generate acid compounds at the high temperatures reached during the extrusion process prior to blow molding is a major problem in the reprocessing of PET because chain cleavage reactions are acid catalyzed. EVA... 

Polybutylene terephdialate (PBT) has been produced from PET scrap by transesterification widi 1,4-butanediol.1 In die process, classified and cleaned polymer Bake from postconsumer PET bottles is reacted witit 1,4-butanediol in an extruder. PBT is used as an engineering plastic. Ethylene glycol and tetrahydrol uran produced as by-products are recovered by distillation. 

PET powder was prepared from commercial PET bottles and had a number-average molecular weight of 30,000. PET powder (0.2 g) was placed in 30 mL of relatively dilute sulfuric acid (10 M) in a sealed Pyrex tube and heated to 150°C for 1-6 h in an oven. After the reaction mixture was allowed to cool, the precipitate of TPA and PET residue deposited was filtered through a 1G-5 glass filter. TPA was separated as the ammonium salt by dissolving it in 12 mL of 5 M NH3. The TPA was reprecipitated by sulfuric acid solution. The yield of TPA was 100% in 10 M sulfuric acid solution. 

In a continuous process, ground PET bottles (830 parts) in an aqueous slurry were pumped into an autoclave equipped with a stirrer and maintained at 450-550 psig pressure and 191-232°C. Ammonium hydroxide (300 parts) solution consisting of water (7857 parts), ethylene glycol (493 parts), and ammonium sulfate (918 parts) was introduced into the reactor. The retention time in the reactor varied from 5 to 45 min. The aqueous diammonium terephthalate and edtylene glycol solution was withdrawn from the reactor and filtered while hot to remove solid impurities such as pigments, pieces of metal caps, labels, and cap liners. Hie filtrate was acidified widi sulfuric acid solution to liberate the TPA product. Hie recovered TPA usually had a purity of 99% or higher. 

In a joint project between the Waste and Resources Action Programme (WRAP) and Coca Cola Enterprises in the UK it proved possible by redesigning bottle production to reduce the weight of 500 ml PET bottles by 8%. These lighter bottles meet all of the required performance standards, and when production reaches the full scale of 700 million p.a. will save 1400 tonnes of PET. This may seem to be a small improvement, but lightweighting of drinks bottles has been a continuous process for many years, and yet progress is still possible. 

Identify how a product could become a feedstock for another industry at end of life. Producing thermal fleeces from PET bottles and resilient playground surfaces from used tyres are examples. 

As an example, Cooper and coworkers have used polarized ATR spectroscopy to characterize the surface orientation of PET bottles [35]. They first confirmed the quantitative agreement between ATR and X-ray diffraction results, and then studied the molecular orientation of the bottles at 2 cm intervals. 

Figure 6 Chain orientation along the hoop, length, and thickness directions measured at different positions along the length of a standard PET bottle. Polarized ATR spectra were recorded for (a) the outer and (b) the inner surfaces of the bottle, respectively. Reproduced with permission from Smith et al. [35]. Copyright Elsevier 2006.

Specular reflection IR spectroscopy has been used by Cole and coworkers to study the orientation and structure in PET films [36,37]. It has allowed characterizing directly very highly absorbing bands in thick samples, in particular the carbonyl band that can show saturation in transmission spectra for thickness as low as 2 pm. The orientation of different conformers could be determined independently. Specular reflection is normally limited to uniaxial samples because the near-normal incident light does not allow measuring Ay. However, it was shown that the orientation parameter along the ND can be indirectly determined for PET by using the ratio of specifically selected bands [38]. This approach was applied to the study of biaxially oriented PET bottles [39]. 

All water samples were collected in amber-polyethylene terephtalate (PET) bottles and were kept at 4°C during shipment. Upon reception in the laboratory, samples were vacuum filtered through 1 pm glass fiber filters, followed by 0.45 pm nylon membrane filters, and were stored in the dark at —20°C until analysis. 

Terephthalic acid manufacture, platinum-group metal catalysts in, 29 622 Terephthalic acid PET bottle resin process, 20 48-50... 

The lower investment and running costs of the continuous SSP process, which does not require the high temperatures and vacuums associated with the melt phase. The cost splits for a 600 t/d continuous PET bottle grade plant are shown in Figures 4.2 and 4.3. The investment costs are some five times lower and the process costs approximately half for the SSP process when compared to the melt phase. 

Degradation and side reactions are limited in the solid state due to the lower processing temperatures used. PET, for use in bottle applications, is a notable example. Small concentrations of acetaldehyde (AA), a by-product of degradation and side reactions in PET, can affect the taste of carbonated soft drinks and mineral water. The SSP process is the best means of achieving PET bottles with acceptable levels of AA. 

Indeed, the increasing industrial significance of the SSP process can be directly related to the success of the PET bottle. PET was introduced for use in drinking bottle applications in the mid 1970s and the SSP process was required to reduce the AA level below that achievable in the melt phase while increasing... 

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