ITP 341 - Shin - Final Exam

Lamination

- For lamination process, at least two individual webs (rolls) of material are produced→joined together in a subsequent lamination procedure. • Usually involves introducing adhesive to provide the bond between the two webs--> the finished structure may have as little as 3 layers PP/Adhesive/LDPE • Adhesive lamination is divided into wet lamination and dry lamination - Wet lamination - Dry lamination Wet lamination: A solvent or emulsion adhesive is applied to the netting or the nonwoven putting both materials together under pressure and letting the solvent evaporate→drying will be too long and will not be economical Dry lamination: Powder (ex, eva) plastic or hot melt adhesives are applied to one of the substrates visseveral coating techniques: roll coating, spray coating, die coating, etc. and laminated together under pressure. Why we use multilayer film/sheet? There is no perfect, universal packaging material - Laminates assemble materials with individually desirable properties to create an optimum combination →A product made by bonding together two or more materials, whether plastic, paper or foil - Two methods to produce multilayer structure • Lamination • Co-extrusion EXAMPLES: Multilayer Plastic Laminate pouch for Herbs - PP/EVA/PE Laminate pouches for loose tea - PP/al. foil/PE Laminate for Pastes: - PP/AL/PE

Injection Molding

- Melt plastic, fill, and made in the desired shape • Building up enough pressure to quickly fill the mold is important (function of the plastic, its viscosity, and the size/number of cavities in the mold block) • Vents are built to remove trapped air. (usually mold parting line) • Complex design can be used for injection molding (plastic cap, lipstick case, and mostly pre-form) • Cent collapsing cores which can be pulled away from the walls of molded object, permitting release.

Main type of pouches

- Pillow Pouch (Example : chip bags) ▪ Consists of seam at the back ▪The back seal is either a 'fin' or 'lap' seal ▪Has top and bottom seals - Three-side seal Pouch ❖One side folded, other three sides sealed ❖Folded side usually serves as the bottom of the pouch ❖The remaining sides are heat sealed ❖Only the inside needs to be a heat-sealable material - Four-side seal Pouch ❖Two Rolls of web stock, seal all sides ❖May use different materials for sides ❖Not necessarily rectangular (may be any shape) ❖Inner layers must be heat-sealable Example: Pharma, medical devices - Tyvek - Clear plastics is used so the product is visible - Stand-up Pouch ❖Designed to stand vertically when filled with the product. ❖Special bottom design: Use of gussets ❖Currently: Growing demand in industry ❖Display advantages compared to other styles of pouches. TYPICAL DESIGN : - PET or Polyester Is the outside layer. It provides strength and has a high melting point.- Ink is the printing that occurs on the inside of the PET layer and will get sandwiched with the next layer of film. (to protect ink→reverse printing is used)- Aluminum provides a high barrier to light and gasses, microorganism, and odours- LLDPE LDPE, or PP is the inside layer. It provides a moisture barrier and has a low melting point. This is the layer that melts together to form the seal.

What is an 'Extruder' and what does 'Extrusion' mean?

- Processing plastics into products requires the conversion of solid plastic (pellets), usually in granular form, into a melt. This melt can be shaped using heat and pressure into a desired/useful form. - The equipment to do this is called an extruder - part of a blow molder part of injection molding machine. - An extruder is used to make film and sheet, and also new pellets from master batch. - PURPOSE : use heat, pressure and shear to transform solid plastic pellets into a uniform melt for the next step of processing.

Form Fill Seal Machine (FFS)

- Stock in roll form is bought - Pouch is made and filled with the product - (Advantages: Comparatively less expensive especially for high volume applications) • Preformed pouches are bought - Comparatively less capital investment

Coextrusion Film and Sheet

1. Multilayer structures are used in packaging in order to take advantage of the properties of several polymers at once e.g. PET/EVOH/PET 2. Film or sheet- coextruded by melting multiple resin in separate extruders and then carefully combine without mixing the layers. This is enabled by carefully engineered Die Advantage 1.Use thinner layers than lamination 2.Multiple properties obtained with a single operation 3.No solvents required (compared to lamination) 4.Pigmented layers can be buried (heat seal layer) Disadvantage 1.Machinery is expensive 2.Initial set up of coextrusion line is expensive (thus most have long runs)

Calculation of permeability coefficient Sample question

1. Oxygen Transmission rate through a 0.1 mil PE film, OTR= 3.5 x 10-2cc/m2·day. When the partial pressure difference (∆p) through the film Δp is 0.21atm. Calculate the permeability coefficient. 2. Oxygen Transmission rate through a film is 1 x 10-6 cc/m2.sec at 10oC, and that the thickness of film is 0.2 mil. When the partial pressure difference (∆p) through the film Δp is 0.21 atm. Calculate the permeability coefficient. 3. The oxygen transmission rate of PET pouche with 0.1 mil thickness is 0.41 cm3·m -2·s -1. Inside oxygen concentration was 0% at ambient temperature. Calculate the oxygen permeability coefficient of the film

Calculation of permeability coefficientSample question

1. The Water Vapor Transmission Rate of PE film with 1 mil thick is 0.21 g/m2·day. Relative humidity was 23 °C and the vapor pressure difference was 21.068 mmHg. Calculate water vapor permeability of the PE film. 2. The Water Vapor Transmission Rate of PE film with 1 mil thick measured by ASTM dish method is 0.1 g/m2·day. The testing temperature was 38°C, and relative humidity was 90% RH (po), and relative humidity inside of PE film (pi) was 0%RH. Calculate water vapor permeability coefficientHint: The saturate vapor pressure of water at 38°C is 49.7 mmHg. The table at the end of slide contain saturation water vapor pressure at various temperature. The pressure in outside (po) is 49.7 mmHg x 0.9=44.73 mmHg and inside of film (pi) is 0 mmHg (because of the 0% RH). Thus, ∆p = po -pi= 44.73 mmHg- 0 mmHg=44.73 mmHg 3. The Water Vapor Transmission Rate of PET film with 1.5 mil thick is 0.025 g/m2·day. The testing temperature was 25°C, and relative humidity was 80% RH (po), and relative humidity inside of PE film (pi) was 0%RH. Calculate water vapor permeability coefficient

Can we recycle multilayer packaging?

Currently, USA does not recycle multilayer package. However, some innovative recycle program and technologies will make possible multilayer pouch to recycle. Approaches to reduce multilayer package waste -Delamination -Mechanical aluminum and plastic separation : currently→more economical and sustainable. • Hefty's EnergBag program: The program collects recycle plastics (such as candy wrappers, juice pouches, etc.) which are not collected at curbside and converts them into useful resource (energy recovery). https://youtu.be/yJ1RUrQcRsk • Hefty extend their collaboration with other companies including Dow chemical, Reynolds, consumer product, and First star recycling. • Dow also did pilot project (called Purple bag) at Citrus Heights, CA.

Name and describe the function of the three main sections of an extruder Two primary heating source of the extrusion barrel - study all extruder components

Extruder components: ❖Hopper: This serves as a reservoir to feed plastic pellets from storage to the extruder. The resin passes from the hopper through the feed port into the barrel. ❖Barrel: This is the main body of the extruder. It is a hollow tube which is heated. (2 main heating sources!!) - electric heater bands - friction within the barrel, as the plastic is conveyed. ❖Screw: This is the main working part and it is housed inside the barrel. This has helical channels which melt and convey the plastic

Meaning of 'Fin'/'Lap' seal

FIN Seal ➢Inner layer must be heat sealable ➢Strong seams ➢Extra material is required LAP Seal ➢Both the inner and outer layers must be heat sealable ➢Seams are not as strong as fin seal ➢Less material is required

Estimate the shelf life of products

In case of oxygen-sensitive or moisture sensitive products (pharmaceuticals, dry food, electronic parts, etc)→Permeability coefficient can be used to determine shelf life or to select optimum packaging material

Steady-state and unsteady state

In steady-state behavior, permeation rate do not change with time In unsteady-state, permeation rate do change with time.Steady-state mass transfer refers to a situation where the mass of a substance moving across the plastic per unit time does not change over time.

Blown vs Cast Film

In terms of transparency: Blown film shows lower quality than cast film. One reason: Slower cooling of blown film NOTE: In general; blown film shows better barrier properties than cast film

Injection Blow Molding

Injection blow molding • Manufactured the parison (called preform) by injection molding. • preform tube is reheated →hot preform is placed into the container mold and air pressure is used to stretch it into the mold shape. • The mark left on the cent of the preform by the injection mold. • Used primarily for applications where high quality finish (treaded area) are important for seal integrity. Ex) bottle for prescripsion and over-the-counter drug, flavor sensitive juice, etc • Preferred for materials with limited melt strength such as PET, PS

Injection Blow Molding vs Injection Molding

Injection blow molding is more expensive than injection molding alone as well as extrusion blow molding. WHY ? Because injection blow molding requires TWO sets of molds and TWO molding processes. ❖However Injection blow molding is capable of producing shapes that can not be produced by injection molding. ❖It also produces very little scrap. ❖It is used for most PET bottles, as well as for most bottles used for pharmaceutical products.

permeability coefficient

Look at slide 7 CH 7. ** in order to calculate P, we must assume that permeation is at a steady state.

Important terminology

Permeation: The movement of gases, vapors, or liquids (called permeant) across a homogeneous packaging ((without perforation, cracks, or other defects )material.→highly impact the shelf life of product. Migration: The transfer of substances originally present in the plastic material into a packaged product. The compounds that transfer are called migrants. Ex) water sensory quality change in water bottle (due to acetadehyde) Sorption: The uptake of product components, such as flavor, aroma, odor, or colorant compounds by the package Solubility: The properties of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent (= dissolution of water or gas into or out of the polymer at entry and exit points) Diffusion: Movement of water or gas within the polymer (inside the polymer)

What is permeation?

Permeation: the movement of gases, vapors, or liquids across a homogeneous packaging material, excludes flow through defects

Application of the permeability equation

Step 1: select package materials. Together with mechanical properties, permeability values for O2, CO2, N2, H2O and organic vapors, as applicable, should be used to determine the best performance/cost ratio for specific pkg materials. Step 2: Calculate the amount of gas or vapor (=q) taken up or eliminated by the packaged product, for specific conditions of temperature, pressure, time →This is also called "critical limit" Step 3: Estimate the shelf life if the quantify q (=critical limit) of permeanttransferred through the package is known or is set as a target value. The permeantmay be amount of water lost or gained by the product, or total amount of oxygen reached for a specific packaged product.

Permeation through plastic film

The mass transfer rate (or permeation rate) depends on both the solubility of the compound (influencing how much is in the plastic) and its diffusivity (how readily it can diffuse, move through the plastic) Permeability Coefficient (developed by Fick and Henry) P = (D)*(S) Where, P=Permeability coefficient D=Diffusion coefficient S=Solubility coefficient

single screw extruder

The standard single screw extruder has a right-hand helix in the screw and the screw rotates in counterclockwise direction. The screw is generally divided into 3 sections: 1. Solids Conveying or feed section (main purpose is to convey the plastic pellets forward) : This smoothens the unevenness in the feed rate and compacts the pellets. Friction between the screw and barrel conveys the plastic forward. 2. Compression or melting section (main function is to melt the plastic): The depth of the screw channels decreases and builds up pressure on the plastic and forces the solid against the barrel wall.External heating + Internal heating (from friction of plastic and barrel and from shearing of plastic): causes softening and melting of plastic. 3. Metering section (main function is to convey the melted polymer): This delivers the molten polymer to the shaping device.

Oxygen permeability coefficient

There are two important reasons why we can make this assumption with reasonable accuracy, most of the time • The concentration of oxygen outside the package, in normal air, is essentially constant at 0.21 atm partial pressure • Expect that the oxygen concentration would rise as permeation occurs, allowing oxygen to enter the package. • the concentration inside the package remains at a low level, near zero • It commonly model this situation as steady state, with 0 oxygen inside the package throughout the product shelf life. (or products generally ruined easily even if we use higher barrier material) Ex)Peanut bugger in PET jar (2 lb), allowable oxygen gain -100 ppm

Single Screw vs. Twin Screw

Two types of extruders: 1.Single screw extruder: higher output than twin screw 2.Twin screw extruder: High shear force in extruder, better mixing, blending

What is flexible packaging?

• Flexible packaging is a package whose shape is not rigid and can be easily changed, when filled and during use. • Technically, flexible packaging is defined as a material sold in thicknesses of up to 250 microns (=10 mil). • Structure can be a simple film or complex, which means that it combines thickness from ***10 **** micrometers of different materials such as paper, plastic film, aluminum foil, or combinations of these. Advantages: - less material (economic) - less space utilization (economic) - light weight - versatile (food, pharmaceutical, hardware, etc.) - less environment footprint Disadvantages: - Lack of strength - difficult to open - hard to reseal - Hard to recycling (Both single & multi layer pouch are not acceptable for general recycle system) Solutions: - combined pouch with paperboard carton - easy tear tab or easy peeling - recloseable system - the Wrap Recycling Action Program (WRAP) Mechanical/chemical separation technology

Water vapor permeability coefficient

• In a typical situation involving water vapor permeation, we need to provide a water vapor barrier to prevent something from getting too moist or from drying out. • Unlike oxygen, water vapor pressure is changing frequently due to RH. • The water vapor concentration inside the package depending on product. • Dry product: zero moisture (0% RH)→Vapor pressure = (outside RH -0) • Moisty product (Juice, meatball, water): 100% RH→Vapor pressure = (outside RH -100 RH) →in this case, moisture is move from inside to outside →100RH - outside RH

Extrusion Blow Molding

• Mostly used blow molding process. • Extruded hollow tube is captured by a mold closing→Air pressure inflate the hollow tube into the shape of the container→cutting off at the top and pinched shut at the bottle (Check the bottom mark!) • Fast and economical process. • For the process, plastic has enough melting strength. Good- _______________Bad- _______________- _______________ This consists of 4 steps: 1. A hollow plastic tube is extruded in the downward direction. 2. Two halves of the mold close on the tube and cut it off from the extruder. 3. Blow nozzle or ' blow pin' is inserted into the mouth of the mold and high pressure air is blown into the mold which expands the tube. 4. The bottle is cooled and ejected ❖Extrusion blow molded containers can easily be recognized by the marks left on the container where the excess material is cut off. This is easiest to see on the bottom of the bottle, where it often appears as a very distinct heavy rough line.

Vertical Form Fill Seal Machine

• Product is weighed and it enters through forming tube. • Forming collar shapes the flat film into a round film tube • Longitudinal sealing bars seal the edges of the film tube • Film is pulled down • Cross sealing jaws create top and bottom seal

Injection Stretch Blow Molding

• Similar process to injection blow molding but use a preform that is shorter than the height of the bottle. • Stretch a preform vertically and radially (biaxial orientation) • Commonly used for PET bottle for carbonated beverages, as well as for many other PET containers. • Careful control over the temperature profile in the preform is extremely important for successful stretch blow molding

What is permeability? Importance?

• The molecules of the compound actually move randomly, some desorbing on the high concentration side as well as the low, and some being sorbed on the low concentration side as well as the high • The net result is mass transfer from the high concentration side to the low one. • The rate at which this occurs depends on both the solubility of the compound (influencing how much is in the plastic) and its diffusivity (how readily it can diffuse, move through the plastic). • We can combine these two values into an overall measure of the barrier ability of the plastic, that we call its permeability. IMPORTANCE: Variety of products that need barrier protection • Food • Pharmaceuticals • Medical • Health and Beauty • Military • Chemical • Electronics • 80% of all food products demand barriers to gas, flavors and odors

Bag-in-Box

▪ Sealed plastic bag inside a rigid outer container ▪ May be spouted ▪ Used for liquids and solids ▪ Outer container may be paperboard, corrugated, plastic or wood ▪ Can also serve as a dispenser

calculation for moisture sensitive project shelf life

❖A cracker package is packaged by 1.2 mil PP (WVTR: 2.0g/m2 .day with 23°C and 90% RH). The package area is 1m2 . Mass of the cracker is 100g. Storage condition is 23°C and 90% RH. Critical moisture content is 3.5g. Determine the shelf life of the package. In case of water vapor, we usually use g (instead of cc) Critical limit=3.5g, Area=1m2 WVTR=2.0g mil/1m2 day Vapor pressure (outside)= 21.068 mmHg @23°C x 90/100=18.9612 mmHg Vapor pressure (inside)= 0 mmHg (because it is dry product) Thus, Δp= (outside vapor pressure-inside vapor pressure)=18.9612-0=18.9612 mmHg Permeability coefficient (P) =(2.0g x 1.2 mil)/(m^2 day x 18.9612mmHg) =0.1265 g.mil/m2. day. mmHg) Time (3.5𝑔×1.2𝑚𝑖𝑙) / 𝑚2 × (0.1265𝑔 𝑚𝑖𝑙 /𝑚2.𝑑𝑎𝑦.𝑚𝑚𝐻𝑔) ×18.9612𝑚𝑚𝐻𝑔 =1.75 day

Excercise Questions

❖A cracker package is packaged by 1.2 mil PP (WVTR: 2.0g/m2 day with 38°C and 100% RH). The package area is 0.25 m2 . Mass of the cracker is 100g. Storage condition is 23°C and 75% RH. Critical moisture content is 1% of the product mass. Determine the shelf life of the package. ❖You're designing a bag for potato chips. This is an oxygen sensitive product that needs protection from air (21% oxygen, and inside of the bag should be 0% oxygen). Assume that the product cannot gain more than 200 ppm of oxygen (56cc). Determine the thickness of the flexible packaging material needed based on the following information• Amount of product: 400 g• Packaging material permeability, P=15.0 cm3.mil/m2.day.atm• Shelf life expected: 6 month (180 days)• Area of the package: 400 in2 (0.258 m2)

Coextruded bottles: Why ?

❖A single polymer may not satisfy the cost and performance attributes of a plastic bottle for a specific application. Thus two or more resins may be used in making coextruded bottles. How a coextruded bottle can be made ? Note: Coextruded bottles may be formed from a virgin polymer and its recycled polymer. ➢Each resin is melted in separate extruders ➢Then the polymer melts are fed into a die ➢A multi-layer tubular parison is formed ➢Then the usual blowing (as discussed earlier) process is followed Note: Coextrusion is different from polymer blending. ❖In coextrusion; the care is taken to avoid blending. ❖In making coextruded bottles where dissimilar polymers are used, there needs a tie (adhesive) layer between coextruded polymer layers - - for adequate adhesion purpose. example 1: PP/EVOH/PP ketchup bottle (1st successful commercial bottle in USA): O2 sensitive food EVOH: Excellent O2 barrier property. Note: PP is nonpolar whereas EVOH is polar. Thus a tie (adhesion) layer is need. Use of Regrind layer (from flash of bottle production): predominantly PP: No additional tie layer: economically favorable

Overall cast film process, characteristics and its orientation process

❖Cast film is generally produced by downward extrusion of the melt onto chilled highly polished rolls. ❖The first chill roll: operating temperature at least 400C: subsequent rolls at low temperature thus to cool the film enough so that it can be trimmed and wound. Orientation: The stretching the film: produces molecular realignment in the direction of the stretch: used to modify cast film properties. Orientation: tends to increase crystallinity, barrier properties and strength in the stretched direction (s). Biaxial orientation: involves stretching the film in both the machine and cross-machine directions. Cast film orientation 1. Uniaxial orientation - Take-off speed significantly higher than rate of extrusion. Stretching can occur prior to initial contact with first chill roll. Usually reheated after first chill roll and stretched in the machine direction 2. Tentering process a) Biaxial orientation ❖The most common die configuration (cast film and sheet production) : 'coat-hanger*' die. Cast film characteristics 1.Relatively unoriented 2.Can be oriented uniaxially or biaxially by adding a step known as tentering prior to winding 3.Cast film generally has uniform film thickness and good clarity (why does it have good clarity?) 4.Quick cooling caused by chill rolls or quench tank prevents rearrangement of the chains in an ordered fashion

Extrusion blow molding vs. Injection blow molding

❖Extrusion blow molding is the simplest and generally the most economical process for making plastic bottles ❖The plastic must have sufficient melt strength to maintain the hollow tube shape and permit it to be formed further. ❖Control over wall thickness is not as good as in injection blow molding. ❖Extrusion blow molding is capable of producing a very wide variety of bottle shapes, including bottles with handles, dual chambers, and more. ❖In this case considerable scrap is produced especially with complex designs. ❖Usually scrap can be reused in the process, but not always

Coextruded bottles in cosmetics packaging

❖In certain cosmetic bottles the out layer is colored unlike inner layer. ❖In making colored plastic the costly color enhancers like metallic flakes, pearlescents etc. are used. ❖In such applications of coextruded bottles the outer layer might constitute around 10-15% of the total wall thickness of the coextruded bottle. ❖In certain cosmetic bottles the out layer is colored unlike inner layer. ❖In making colored plastic the costly color enhancers like metallic flakes, pearlescents etc. are used. ❖In such applications of coextruded bottles the outer layer might constitute around 10-15% of the total wall thickness of the coextruded bottle. ❖In certain cosmetic packaging there is a need for high barrier performance. ❖Thus there is need for multilayers bottle structure. ❖One example of multilayer coextruded bottlefor better performance: HDPE/EVOH/HDPE/EVOH/HDPE

Overall Blown film process, characteristics and its orientation process

❖Most Blown film: extruded upward. ❖The molten polymer from the extruder is forced through an annular die. ❖The resulting tube is inflated internally by air into a bubble and cooled. NOTE** The blown film is stretched biaxially due to internal air and winding. When the film is cool enough, the bubble is collapsed by plates and rollers and wound up. ❖Blown films are generally less transparent as relatively slow air cooling increases crystallinity to the polymer. ❖Blown film lines are complex to start-upbut once running then require minimal work. Hence these are used for high volume production. ❖Blown films do not require trimming and hence scrap is also minimized About Blown film 1.Width of the end roll and the thickness if the plastic are controlled by the volume of air, rate of extension and the temperature of the plastic 2.Blown film are hazier than cast film as they have longer time to crystallize. 3.Blown film process stretch films both side during process (inherently biaxially oriented) 4.Less expensive for long runs 5.Polymers with low melt strength cannot be run e.g. PET 6.Bubble usually vertically upward ; can be downward Principal polymers in blown film production: Polyolefins Major applications: Bags; construction film; agricultural film. Coextruded films: Three to five layers or more. Coextruded films: Food Packaging. Major markets: Cereal, snacks, meat and frozen foods.

Special Packaging: Retort Pouches

❖Retort pouches: Designed to be filled, usually with food product and then retorted (heat sterilized) ➢ Does not require refrigeration ❖Retort packages have replaced cans in U.S. military (meals ready to eat or MRE) program. ❖Multilayer lamination: From outside layer, it consists of polyester, (w/wo) Nylon, aluminium foil and Polypropylene. An important advantage: ➢Product/container interaction: much less than in metal. Some disadvantages: ➢Poor consumer acceptance (for consumer products: food cannot be heated within the pouch in a microwave oven). ➢Retort pouch is not easy to seal.

Film and Sheet

❖The molten plastic leaves the extruder through a slit shaped die producing films or sheets. ❖Films are differentiated from sheets on the basis of thickness and flexibility: materials with thickness less than 0.010 are considered film vs. 0.010 inch or greater are considered sheets. Films are relatively more flexible. ❖Both films and sheets can be made through extrusion process.

Dies, Melt Filters, Drive mechanism and Screw speeds

❖The molten polymer exits the barrel through a die which has been designed to impart desired shape to the melt stream.Dies, Melt Filters, Drive mechanism and Screw speeds ❖Melt Filters: Screens for filtering impurities out of the melt. ❖Drive mechanism and screw speeds: The speed of rotation of screw is generally controlled by a variable speed motor. A speed reducer is also needed between motor and screw.

Calculation for oxygen sensitive project shelf life

❖We are storing 2lbs of peanut butter in a PET jar, 8 mil in average thickness, with a surface area of 100 in2. We determine through taste testing that the allowable oxygen gain (CL) is 100 ppm of oxygen gain. ❖What is the shelf life of the peanut butter? (O2 Permeability coeff. Of PET = 5 cc mil/100 in2 d atm). The 100 ppm of oxygen gain means = 0.000100 x 2 lb =0.0002 lb of of oxygen → It will be no longer acceptable with > 0.0002 lbs of oxygen Thus, volume of oxygen (q) = 0.002 lb (454 g/lb) (mole/32 g) (22.4 x 103 cc/mole) = 63.56 cc Pressure difference (Δp)= 0.21 atm - 0 atm = 0.21 atm. 63.56𝑐𝑐×8𝑚𝑖𝑙 / 100𝑖𝑛2 × (5𝑐𝑐𝑚𝑖𝑙 / 100𝑖𝑛2.𝑑𝑎𝑦.𝑎𝑡𝑚) ×0.21𝑎𝑡𝑚 =488 days

Flexible Packaging: Various forms

❖__________ ▪ Stretch type ▪ Shrink type ❖___________Three sides are formed by two methods ▪Extrude a tube and then seal the bottom ▪Web stock, seal the sides and the bottom ❖Bags have some overlap with pouches Note: Pouches (smaller packages); Bags (large bulk packages)