Design Project Ellinor Grape; Tatjana Karpenja; Sanita Zike

Transcription

1 Design project in Packning Materials Product The product we choose to do a packing design is cat food of the wet sort. The product is jelly-like, fatty and has a strong smell. It has high moisture content (75-78 %) that has to be preserved. Packaging material The primary package will consist of paper board and polymer. The main task for the paper board is mechanical protection. The polymer is used as a barrier. Paperboard As paperboard we could use: KORSNÄS WHITE 65 or KORSNÄS LIGHT 50. Their mechanical properties correspond to our packaging system. Paperboard demanded box compression resistivity (BCR) 170 N. Paperboard MD direction coincide with applied force. In this direction mechanical properties of paperboard are higher. Stacking is vertical. There are primary packages stacked to the top of one another. KORSNÄS WHITE 65: BCR = 10 N Thickness (caliper) = 0,70 mm Basis weight = 65 g/m Compression strength (SCT) MD = 6,5 kn/m Bending stiffness MD = 5,1 mnm; CD = 17,8 mnm Brightness 95 % Roughness (PPS-10)1 μm KORSNÄS LIGHT 50: BCR = 5 N Thickness (caliper) = 0,60 mm Basis weight = 50 g/m Compression strength (SCT) MD = 7,5 kn/m Bending stiffness MD = 8, mnm; CD = 19,4 mnm Brightness 80,5 % Roughness (PPS-10) μm The difference between paperboard thicknesses is very small and doesn t seem important. The paperboard packaging weight for KORSNÄS WHITE 65 (approximately) 10 g and KORSNÄS LIGHT g. m m A = m = m A A, A packaging area, m packaging weight, ma basic weight A A = (90x +60x) x (,5x +8) = 45600mm = 0,456 m

2 So we could approximately save 6 g per primary packaging unit. In a transport unit we could decrease weight to package in first layer about 1 x 6 = 16 g. It doesn t seem important. From given values it is possible to conclude that Korsnas Light has better mechanical properties, Korsnas White printing properties. The brightness and surface roughness of Korsnas White is much better. We prefer material with better mechanical properties. This kind of printing properties would be more preferable to luxurious goods. Korsnas Light could also be cheaper as additional surface treatments make paperboard more expansive. Korsnas Light is made from virgin, unbleached wood fibers. Polymers Polymer layers are used to protect food and paperboard properties strength, stiffness - from external environment. So polymer layers should be made in both sides of paperboard. Inside layer (in interface with food) should mainly protect food from water loss and paper from gain. Choosing inner layer it should be considered that pet food also contains some fats. Mainly in fats are soluble non-polar polymers, but there are the best moisture barrier materials. Solubility of non-polar polymer in fats could be reduced by cross-linking or enhanced crystallinity. The inner layer will be made from cross-linked high density polyethylene what has increased crystallinity. To enhance adhesion between paper and polyethylene maleated polyethylene will be used. Polyethylene is one of the cheapest moisture barriers. HDPE (Chevron Phillips mpact D449 HDPE Blown Film Resin): Density 0,94 g/cm Moisture Vapor Transmission 0,60 cc-mm/m²-4hr-atm 1 Oxygen Transmission 18 cc-mm/m²-4hr-atm (1,57x10 ) Thickness 5,4 microns Glass Temperature -70 C Price (HDPE film) 1,45 Euro/kg

3 As alternative to PE could be polypropylene. It is also pretty cheep material. Polypropylene has higher glass transition temperature, so we could assume its molecules are stiffer and could have better barrier properties. But it is not. It could be referable to a larger side group (CH) of PP, what increases distance between molecules. Comparing PP to PE it has higher oxygen and water permeability. Outside layer (in interface with external environment) should protect paperboard from moisture, food from oxygen and should prevent going out aromas from package. One of most popular barriers is polyethylene-co-vinyl alcohol (EVOH) as it has very low oxygen permeability coefficient because of hydrogen bonds and stiffer molecules (higher glass transition). Drawback, it is very sensitive to moisture. Oxygen permeability and moisture sensitivity depends on ethylene concentration. We could use EVOH with 7 mol% ethylene. For moisture barrier we will need to use an additional outer polyethylene layer. EVOH (EVALCA EVAL LC-L101A): 7 mol % Ethylene Density 1, g/cm Moisture Vapor Transmission,10 cm -mm/m²-4hr-atm (40 C, 90% RH) Oxygen Transmission 0,004 cm -mm/m²-4hr-atm (0 C; 65% RH) (0, x10 ) Glass Temperature 7,0 C Price 5,69 Euro/kg) As EVOH has very low oxygen permeability (oxygen transmission) it would be possible to preserve food quality more than a year. If upper limit of oxygen permeability s needed for preserving food quality is: 1 1 week: 0,0-0,1 Barrer = 0,07-0,1 x year: 0,0004-0,00 Barrer = 0,0005-0,007 x10 EVOH drawback, it is pretty expensive material. That was the reason why we were trying to find another barrier material. Twice cheaper is PVDC. PVDC (Dow Saran 168): Specific gravity 1,70 g/cm Moisture Vapor Transmission 0,157 cm -mm/m²-4hr-atm Oxygen Transmission 0,886 cm 1 -mm/m²-4hr-atm (0,0101x10 ) Price,79 Euro/kg If we use this polymer in outer layer food preservation could be from till 10 weeks. Moisture vapor transmission is even lower than in HDPE case so there won t be need for additional layer. We suppose that preservation time for canned pet food should

4 be longer. The other option is OPET/PVDC (biaxially orientated PET with PVDC). We don t know the precise price of this material, but we assume it could be cheaper than EVOH, as PET costs, - 4,05 Euro/kg. PVDC price is mentioned above. OPET/PVDC (DuPont Teijin Films Mylar OB1AF Polyester Packaging Film, gauge 50) Density 1,4 g/cm Moisture Vapor Transmission 0,14 cc-mm/m²-4hr-atm 1 Oxygen Transmission 0,14 cc-mm/m²-4hr-atm (0,0016 x10 ) In this case food preservation could be from 1 till 6 weeks. Moisture vapor transmission values are very low - no need for additional layers. Also it has very good adhesion to polar substrates, including paper. We will use OPET/PVDC polymer film. PET has low permeability values because of stiff terephtalic unit in flexible chain. Orientation enhances barrier properties as polymer fractional free volume and molecular mobility reduces (due to orientation process molecules are closer packed; there is less free space between them). PVDC barrier properties are explained with its structure symmetry and crystallinity. Polymer crystals decrease penetration of solutes. Design of the primary The shape of the primary package is rectangular with size 90x60x8 mm. The wall thickness is 0.5 mm. The grip width is 60 mm - it user friendly from that aspect. We want to have 400g of cat food in one package. That is sufficient for meals for days. You do not want to have a bigger package because the product will be tainted and dry if an opened package is kept for too long. Communication The printing technique that can be used for this package is Flexographic printing because it s a quick and cheap method. The quality of the print is not that good but as stated earlier this is not a luxurious product so the printing do not have to be perfect. In this case price and speed are more important factors. Front Back The front of the package is a happy healthy cat that shows how happy your cat will be when eating this cat food. In the white square there will be an explanation of the

5 content in the cat food and for how long you can keep an open package and where it should be kept. On the back of package there will be an instruction on how to open and reclose the package. On the side there will be an explanation on how to recycle. The instruction on how to open the package could look something like this: You want to be able to reclose the package because of the disgusting smell from the cat food and to keep the content from drying. That could be done by folding down the top as in the picture and fix it in the folded-down-position with some kind of adhesive that is attached to the package when you get it. Design of secondary packaging The primary package is then packed on trays in groups of 0 and covered with shrink wrap. In this case you don t have to mark the secondary package because you can see trough the shrink wrap to see what product the secondary package contains. The trays are used for stability when put on pallets and to make it easier to put the product up in the stores. The idea is to take the shrink wrap away and put up the entire tray. Design of transport package The secondary packages will be putted on pallets. We chose to take a standard euro pallet (1000 x 800 x 100, 5 kg) as product is going to be distributed in Europe. See the data for that in attached analysis made in Cap pack. Moisture is not going to be a problem during storing and transporting because everything is wrapped twice with plastic.

6 Runnability We want to have a very efficient packaging that is produced in short time. Runnability of paper is therefore a key performance parameter for us. This is a paperboard s ability to be converted in the following operations: production, conversion (printing, cutting, creasing) and packaging line (filling) without defects and efficiently. It means that we want to maintain good speed of running the material through operations at the same time as we want to keep quality of the packaging parameters. Runnability is a combination of characteristics in paper. Here we base our discussion on the stiffness and flatness properties only. The packaging material that we choose has sufficient stiffness in order to serve us well. Stiffer packaging material can run through the machines in more efficient way than less stiff material, for example avoiding double sheeting to the feed of the processes or, in general, being more stable In the operations. A stiff enough primary packaging will be less subjected to mechanical damage (e.g. no buckling, no cracks) and therefore less food will be wasted. Our paperboard is stacked vertically in MD since the stiffness of the material is higher in this direction. It is strong enough to provide a physical protection to our cat food product when placed one on the top of each other on the pallet, forming our packaging system. In order to increase the strength and stability of our packaging system, we have added trays and wraps thus, the system will be more stable. This is very important during transportation, for example. The shape of our packaging is rectangular what also gives more stability to the packaging system. In the filling operation, our packaging material with enough stiffness will be less subjected to damage and will be properly sealed. Stiffness can diminish dramatically with presence of moisture variations; therefore, as was discussed above, we protect our primary packaging with plastic wrap. The packaging material itself has also polymer barriers against moisture. We choose paperboard made of virgin fibers - the stiffness and strength of such fibers is better compared to recycled fibers due to their shorter size. One of the examples could be printing on paperboard with good stiffness what gives higher print density and greater dot gain. This smaller contact area resulted in a higher external pressure on the ink. In general, the rigid sheet is easier to align perfectly, meaning higher precision and, in effect, a possibility for higher speeds in the operations. The flatness of our packaging material is important in the manufacturing, converting and filling processes because cat food is a product of mass consumption, and therefore it will be processed at high speed. If our material will be curly or twisty, in

7 other words, not flat, this might damage techniques and cause stops in the operations, what would lead to low productivity and high costs of operation. Therefore, we want to manufacture, store and handle our packaging in a proper way. By not letting the moisture in, for instance, we store our packaging material properly cover it with the plastic film (wrap). Moreover, our packaging material itself has inner and outer layers of polymers that serve as a protection for paperboard against moisture and oxygen (we can preserve the mechanical properties of the paper and the food). The smooth passage of our packaging material sheets through the fast speed printing press without concern over flatness will give a consistent print result. But the reason why we didn t choose the paperboard Korsnäs White, which has lower roughness and better brightness than Korsnär Light does have, is that the mechanical properties are more important for our product than fancy printing. As a whole, in all operations the packaging material should be flat and stiff enough among other properties. Environmental properties Below are some issues that we considered in this project basing our discussion on the advantage of our packaging over the usual metal packaging for cat food. There are two aspects on environmental requirements on packaging. One is related to protection and the environmental consequences if the products are destroyed or contaminate the environment in case of inadequate protection: Elimination of hazardous materials and chemicals in the packaging material. Meaning migration of the chemicals contained in the packaging into food or environment thus creating contamination. Metal cans are usually coated with a thin layer of barrier material inside, which content might react with the product. Food storage period (best before data) of closed and opened packaging can be longer if the appropriate packaging is used. The consequence of this aspect is less food spill, hence less food is to be produced and wasted. Metal cans offer the same storage time period as our innovative packaging. The other aspect deals with the packaging itself and related to both the production of packaging and the use of it. Environmentally friendly and efficient use of processes, raw materials including energy and additives is expected in the production of packaging materials and packaging. In the design of the packaging system the goal is minimum use of packaging materials what saves both resources and minimizes the amount of waste. Furthermore the packaging should support reuse or recycling.

8 Optimized weight of the packaging. For example, light-weight paperboardbased packaging weights less if compared to metal or glass packaging. Meaning fuel consumption during transportation will be lower, the consumers will also benefit from the light-weight packaging. Optimized volume of the packaging. That gives more efficient space usage during transportation allows higher filling degree of the vehicle. New packagings are placed more compact on the pallets due to their rectangular shape. Metal cans are round and volume loss percentage is high. Used packaging can be compressed when transported to the waste recovery facility. Metal cans are harder to compress, they have density -6 time higher than our composite material and are they actually are heavier. Saving resources: aluminum used in metal cans for cat food is an expensive raw material. Paper and polymers are cheaper and paper is a renewable raw material, while extraction of aluminum inputs into resource depletion if not recycled properly! Compliance with packaging and packaging waste legislation. For example, proper waste management is required: reuse, recycle (material recycling, incineration, composting) and no landfill. In Sweden, used paper packaging can become a new packaging at Fiskeby pulp and paper mill. Plastic outer and linear layers can be deattached in the repulping process at the mill and go for energy recovery in Sweden, while the paperboard will become a new packaging (materially recycled). It could be interesting to consider a degradable packaging made from renewable resources in our future designing plans. We could use paperboard; which is a renewable material and also biodegradable plastic barriers? This would save our planet resources (if compared to use of the fossil fuel based materials) and minimize the amount of waste occurred. Literature 1. M. Kutz. Handbook of environmental degradation of materials. New York: 005, p Pages/ what-is-runnability.aspx 6. Course material in the binder: C. Söremark, Packaging, and Iggesund, Paperboard reference manual.

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