Packaging Insight

UV Coating what is it?

I want to explain what UV coatings are and all the other various coatings.

The two most common reasons for adding a coating over your printed piece are for protection: to avoid scuffing the ink, if you have included areas of heavy ink coverage; and for aesthetic reasons: to draw the reader's eye to particular items, to add depth and interest to your printed piece. First consider why you are coating your job.

When making a decision, keep in mind the following:

1. Dried inks show fingerprints and scuffing, especially in dark solids.

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2. Press coatings (like varnish) cost less than bindery (off-press) coatings (like UV coating and laminates) since bindery coatings are applied over dry ink at slow speeds. Because the chemicals used in aqueous coating damage press rollers, this coating is more expensive for the printer/binder to apply than varnish; therefore, the extra cost is passed on to the client.

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3. Varnish is the least effective way to prevent scuffing, particularly when publications are multiply shrink-wrapped (as opposed to singly shrink-wrapped) prior to shipping. Bindery coatings like UV coating and laminates are far better for protecting loose books in transit. Even aqueous coating is much stronger than varnish and can therefore withstand books shifting around in transit without scuffing.

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4. All printers can apply varnish, but not all printers can apply laminates, UV coating, or aqueous coating.

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5. You cannot print (ink-jet or by hand), glue, or foil stamp over coatings, so you need to leave an uncoated window if you want to do any of these (coatings should be the final finishing step on a printed piece).

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6. You should only varnish coated stock, or the coating will seep into the paper and be lost.

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7. Some coatings deepen the ink color they cover, yellow with age, and/or discolor white paper.

VARNISH
Varnish is essentially ink without pigment. It requires its own printing unit on press. It can be wet-trapped (printed in-line at the same time other inks are laid down), or dry-trapped (run as an additional pass through the press after the initial ink coating has dried). The latter often provides a glossier finish. Varnish comes in gloss, dull, and satin (in-between dull and gloss), and can be tinted by adding pigment to the varnish.

From an artistic standpoint, you can play a dull-varnished portion of the sheet against a portion without varnish or with a gloss varnish. This contrast can give emphasis to certain areas and/or give the impression of depth.

UV COATING
UV Coating is a clear liquid spread over the paper like ink and then cured instantly with ultraviolet light. It can be a gloss or dull coating, and can be used as a spot covering to accent a particular image on the sheet or as an overall (flood) coating. UV coating gives more protection and sheen than either varnish or aqueous coating. Since it is cured with light and not heat, no solvents enter the atmosphere. However, it is more difficult to recycle than the other coatings.

UV coating is applied as a separate finishing operation as a flood coating or (applied by screen printing) as a spot coating. Keep in mind that this thick coating may crack when scored or folded.

AQUEOUS COATING
Aqueous coating is more environmentally friendly than UV coating because it is water based. It has better hold-out than varnish (it does not seep into the press sheet) and does not crack or scuff easily. Aqueous does, however, cost twice as much as varnish.

Since it is applied by an aqueous coating tower at the delivery end of the press, one can only lay down a flood aqueous coating, not a localized "spot" aqueous coating. Aqueous comes in gloss, dull, and satin.

LAMINATE
Laminates come in two types: film and liquid, and can have a gloss or matte finish. As their name suggests, in one case a clear plastic film is laid down over the sheet of paper, and in the other case a clear liquid is spread over the sheet and dries (or cures) like a varnish. Laminates protect the sheet from water (including perspiration from the hands) and are therefore good for coating items like menus and book covers. For more money, one can even specify a porous, lay-flat laminate (the interior of which is covered with numerous "V"-shaped cuts in the plastic that minimize the "curl" one often sees on paperback book covers due to moisture seeping into the uncoated side and causing it to expand). Laminates are slow to apply and costly but provide a strong, washable surface. They are the superior choice for protecting loose books in transit.

What kind of coating you should get depends of course on what you're printing and what that printing is intended for.

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dbanig@prflexbag.com

Plastic Poly Bag / Technical Information

Here is technical information on plastic bags.  Plastic bags are created from plastic resins through polymerization , the process in which a chemical reaction links together monomers to form a polymer. A monomer consists of molecules from the same organic substance. When linked together, monomers create polymers , solid substances composed of repeating units. In the plastics industry, the term polymer is synonymous with plastic. Polyethylene and polypropylene are two plastic resins frequently used in the production of plastic bags. Polyethylene (PE), a light, chemically resistant thermoplastic used in packaging and insulation, represents the most common plastic resin. The polymerization of ethylene, a flammable, gaseous hydrocarbon found in petroleum, results in the production of polyethylene resin. Polyethylene resins used in the production of plastic bags include low density, linear low density, and high density resins. Low Density polyethylene (LDPE) remains the most common and least expensive plastic bag material. The resin is created through the polymerization of ethylene at very high temperatures and pressures. LDPE maintains its durability, flexibility, water resistance, and clarity under low temperatures, and its low melting point make it ideal for heat sealing. Linear Low Density polyethylene (LLDPE) is produced at lower temperatures and pressures than LDPE through copolymerization, the polymerization of two distinct monomers. Copolymerization results in LLDPE’s crystalline structure, which provides LLDPE greater stiffness and a higher melting point than LDPE. Although it is more difficult to process, LLDPE maintains greater tensile strength and a greater resistance to stress cracking than LDPE. High Density polyethylene (HDPE) maintains greater strength, resistance, and stiffness than either LDPE or LLDPE. Polypropylene (PP) is a light, durable thermoplastic often used in packaging. Polypropylene contains polymers of propylene, a colorless, combustible gas found in petroleum. Although more expensive to process than polyethylene, processing of polypropylene remains quite easy. In addition, polypropylene is denser, stiffer, and stronger than polyethylene, and maintains a high melting point. In addition to various resins, we have numerous sizes, shapes, styles, and features from which to choose. Common plastic bag shapes include flat and gusseted. Flat bags provide versatile plastic packaging for items of many shapes and sizes. Flat bags are heat sealed on either the side or the bottom of the bag. Bottom-sealed bags provide extra support for heavier items. Gusseted bags contain folds or pleats called gussets, which allow the bag and the bag opening to expand in order to accommodate large or bulky items. Gusseted bags consist of either bottom sealed, side gusseted bags or side sealed, bottom gusseted bags. STYLES Countless flat bag and gusseted bag styles exist. Some of the most familiar bags include those used in retail, food storage, and waste removal storage. Retail bags include all bags used to store and carry merchandise. Supermarkets, department stores, and specialty shops offer different bag styles for employee and customer convenience. A few of the most common retail bag styles include the following: T-shirt bags , often found in grocery stores, are gusseted bags containing long handles to accommodate shoppers; the material of choice is high density polyethylene. Die-cut bags are flat bags containing a hole at the top of the bag for carrying; die-cut bags are common in retail settings and trade shows. Patch handle bags are flat bags with a die-cut handle reinforced by a heat-sealed patch for added strength; patch handle bags are useful in carrying heavy items like books. Drawstring bags contain either plastic or cotton drawstrings inserted inside the rim of the bag. The drawstrings allow for easy closure and provide handles with which to carry the bags. TERMS Additive – substance added to a polymer to increase the effectiveness, but not the strength, of the polymer. Strength increase is achieved by adding a reinforcement. Examples of additives include flame-retardants, anti-static compounds, pigments, and lubricants.   Blow extrusion – common process of creating plastic bags in which compressed air fills an extruded plastic tube in order to enlarge and thin out the resin.   Copolymer – a polymer made up of two monomers in which each repeating unit in the chain consists of units of both monomers.   Crazing - very thin cracks in a polymeric material caused by chemicals or other agents, such as ultraviolet radiation. Degree of polymerization – the length of the molecular or monomeric units in a polymer chain; this length determines the properties of the polymer. EVA (ethylene vinyl acetate ) – copolymer produced through the chemical reaction of ethylene and vinyl acetate; often added to plastic resins to increase the strength of the resin in temperatures below freezing. Glass transition temperature (Tg )–reflects the temperature when a substance changes from a hard, glass to a rubber consistency; polymers become weak at temperatures below their transition temperature.   Grade – polymers originating from the same chemical family and produced from the same company; however, they vary in weight, additives, reinforcements, and the manner in which they are processed.   Heat sealing – fusing together two or more thermoplastic films, such as low density polyethylene, through the application of heat and pressure.   Light-weighting – the process of decreasing the weight of plastic by using less resin, while retaining the plastic’s strength and effectiveness.   Melting point – the temperature at which a substance converts from a solid into a liquid.   Monomer – the most basic polymeric unit, usually a liquid or a gas, consisting of molecules from the same organic substance; chained together, momomers form solid polymers.   Plasticizer – a chemical additive added to plastic resins to increase the plastic’s flexibility.   Polymer – two or more monomers bonded together through a chemical reaction; each polymer consists of a chain of repeating monomers.   Polyethylene – light, chemically resistant thermoplastic used in packaging and insulation.  Polyethylene contains polymers consisting of ethylene, a colorless, odorless organic gas found in petroleum; ripening fruit also produces ethylene in order to regulate growth.   Polypropylene – light, durable thermoplastic with a high melting point often used in packaging. Polypropylene contains polymers consisting of propylene, a colorless, combustible gas found in petroleum.   “Poly bags” – bags derives from polyethylene or polypropylene, although it usually refers to polyethylene bags.   Reinforcement – substance added to a polymer to increase the strength of the plastic. Examples include clay, mica, and glass fibers.   Resin – a class of polymers, or plastics, chemically different to naturally occurring resin, a sticky substance obtained from certain trees and plants. Examples of resins include polyethylene, polyurethane, and acrylics.   Stress cracking – cracking occurring as a result of mechanical stress. In most cases, tiny cracks caused from exposure of the plastic to chemicals or ultraviolet radiation are already present. When stress is applied to the plastic, the cracks enlarge and spread, creating a greater fracture.   Terpolymer - a polymer made up of three monomers in which each repeating unit in the chain consists of units of all three monomers.   Thermoforming – the process of applying heat, pressure, or suction to create plastic sheets according to certain sizes and shapes.   Thermoplastic - category of plastics that have the potential to soften and reform when heated, and harden again during cooling; during the process, the plastic’s physical makeup does not change.   Thermoset – category of plastics that can not be reformed upon reheating; thermosets remain permanently hard.   UVI (ultraviolet inhibitor ) – plastic additive that increases the plastic’s resistance to the harmful effects of ultraviolet radiation, which include fading of color and strength decrease.   Vapor corrosive inhibitor – thermoplastic coating or film that safeguards sensitive items from harsh environmental conditions through the release of a vapor that forms a protective layer on the surface of the thermoplastic. www.prflexbag.com dbanig@prflexbag.com

Benefits Of Using Batch Inclusion Bags To Help The Environment

Batch Inclusion film or bags derive their name from the fact the bag itself,along with contents,is actually included in the production batch or during rubber compounding. The bag, once melted and dispersed, becomes part of the product being made. Batch inclusion bags typically hold chemical additives for large scale industries, such as synthetic rubber and plastic compounding. Often the additives involved are difficult to handle, weigh to little or are used to hard to dispense automatically. These could include colorants, fillers, resins and even some polymers for large scale mixing. Because the bag and its contents become part of the batch, the user will realize a cleaner environment, along with other benefits such as reduce labor cost, reduce disposal cost and clean up cost, better hygiene. The bags or film has a number of benefits like more efficient use of raw materials and a more consistent mixtures of compounds. Also, you will find the use of material in a sealed bag allows for a reduction in storage space when compared to an open container, such as metal containers or plastic and sometimes paper bags. As sealed bags can pile in a bin, cardboard boxes, tubs, or carts.

Benefits of using Batch Inclusion Bags are they improve quality and batch uniformity insures 100% compound ingredients go into the mixing of the material when doing in house weighing, batch inclusion bags eliminate the risk of cross-contamination due to chemical residue in tubs and weighing containers. Will increases productivity and eliminates the need to weigh ingredients in-house through the use of having the product weighed and ready to be thrown into a batch of rubber also eliminates the need to clean out tubs and weighing containers. Reduces the amount of solid waste disposal going into the land fills. You will have less product loss due to spillage and minimizes the accumulation of costly additives in the dust collectors. The idea is to minimizes worker exposure to hazardous materials.

dbanig@prflexbag.com http://www.prflexbag.com

What is slip and how does it work in manufacturing plastic film and bags.

What is slip and how does it work in manufacturing plastic film and bags. Slip is an organic chemical that is added to the blend during film extrusion process to modify the coefficient of friction (COF). COF is a measurement of the amount of friction between two surfaces as they begin to slide and as they continue to drag against one another.

The amount of energy it takes to put an object in motion is always greater than the amount of energy that it takes to keep it moving while it is in motion.

Although there are a number of chemicals that are used to modify the COF the two main ones used in Polyethylene and Polypropylene are Erucamide (which is considered a slow bloom) and Oleamide ( which is a fast bloom. The materials are sometimes called primary amides.

Slip is a very efficient molecule it has been added to a plastic film in very low concentrations typically 500 to 1500 parts per million (PPM). The slip additive can be let down at the levels of 1 to 3% by weight in blending while extruding the plastic film.

Slip molecules are very low in molecular weight as compared to the polymer in which they are used. These molecules are somewhat incompatible because of their nature. This means the material is bi-polar and has one end that has a positive charge and the other has a neutral charge. This incompatibility causes the molecule to migrate referred to as bloom through the polymer to the surface of the plastic film.  The more slip that migrates on the surface the lower the COF and the more slippery the plastic film becomes.

The COF relates to packaging because the substrates used to package objects always come in contact with other surfaces or themselves. As most packaging operations are very high speed, COF plays a very large role. The packaging material must have just the right COF in order to track properly on the packaging machines. If a material is too slippery the film will not track properly and may cause issues such as bad sealing or cause a powder substance that builds up on the tracking rolls which will cause packaging failures. If a material becomes to sticky can have the opposite effect. It may not allow the film to un-wind properly and cause web brakes or other tracking problems. Either scenario can shut a packaging line down.

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dbanig@prflexbag.com

Flexible Pouches Stand Up To Maximize Shelf Appeal

Flexible Pouches Stand Up to Maximize Shelf Appeal

Today’s retail markets are finding endless benefits to using stand up pouches as they have maximized how products can be displayed at retail stores. With the different types of material structures available you can package food products, liquids, chemicals, etc.

Pouches use much less material than other traditional packaging methods like corrugated cartons or laminated boxes. Pouches can be customized to fit any of your needs but you need to understand why stand up pouches can be so beneficial to your business. Once you really understand how they are made, as they can be cheaper and run more efficiently than you may think.

The first thing to remember stand up pouches is that they are made up of co-extruded material from 3- layer, 5-layer, 7-layer, 9-layer or the material can be a single mono layer and laminated with a number of other film structures from p.e.t., nylon, metalized p.e.t., foil etc. They can be printed any color up to 10 color line print to 10 color process print with your logo or design, so the potential to really make an impact on retail shelves is very high.

Pouches are made from a continuous web of material where the first step in manufacturing process of a stand up pouch happens when it goes through a set of plows that folds the material into a w-shape guesset into the bottom so the pouch will be able to stand up. Now if you want a re-closable zipper as part of your pouch it is sealed on the inside of the face of the web near the top edge of the material. Re-closable zippers are the most common method, but spouts, perforations, and other re-closable openings are also available.

Once the gusset is formed vertical seals are then made along the pouches side and the re-closable zipper is pressed into the same area to seal the ends and flattens out. The laminated pouch is then cut apart vertically through the center of the of the side seals to create the finished stand up pouch.

After the product is dispensed into the pouch it travels thru the filling station where the re-closable zipper is closed and the pouch is sealed above the zipper.

Stand up pouches are becoming more and more popular options for liquids, dry chemicals, pet foods, personal care products, granular products like cereal, sugar, salt.

The stand up pouch is very user friendly both for consumers and to help reduce packaging cost.

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dbanig@prflexbag.com

Understanding Flexographic Printing

Flexographic printing is defined as a method of direct rotary printing that uses special rubber or photopolymer material. The printing plates are affixed to plate cylinders of various repeat lengths, which are inked by a cell structure (anolox roll) which is used to meter the flow of the ink on roll. It carries a fast drying fluid ink to the plates that print on a variety of substrates (paper / plastic / nylon / polypropylene / cellophane / LDPE / LLDPE / etc.).

Flexographic printing is a rotating method for every revolution of the printing plate cylinder an image is produced. If the image is stepped several times around a cylinder several images may be produced in one revolution.

Due to the nature of the printing process there are factors that don’t exist with other print methods such as offset and gravure. Because flexographic employs a flat but flexible printing plate that is stretched around a curved cylinder and the image on the plate distorts when the plate is mounted on the printing cylinder. A circle shape for example distorts into an egg shape. The amount of distortion depends on many factors including cylinder size, plate size, and the amount of distortion depends on a number of factors, including cylinder size, plate size, and the amount of adhesive mounting tape used to attach the plate cylinder.

Another aspect of flexographic printing is the solids (line art) print differently than screens (dot patterns). That is because the printing plate is relatively soft and the ink on its surface must be pressed against the substrate to print. Thus the amount of pressure applied to the printing plate is critical For example more pressure is needed to print a dense and heavy solid than to print a screen tint.

Whichever method used to set up the printing press, one design implication must remain clear is that you may not be able to successfully print one color screens and solids on the same printing plate or printing station. This is very different from offset printing where the solids and screens of a given color can be printed with a single printing plate.

dbanig@prflexbag.com

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Process of Rotating The Die While Processing Good Quality Film!

By rotation of the extrusion die these gauge bands can be moved around the surface of the film as the bubble is being extruded. The bubble itself does not rotate. In this fashion they are evenly distributed across the face of the roll at an evenly distributed wound as you would reel in fish line on a fishing reel and build a cylindrical roll of plastic film of perfect symmetry. Without rotation these faults would build up in one place on the roll of film it would create a roll of film whose surface would look like something got caught in the roll and make an un-even impression or bulge on the roll.

Unfortunately rotation of the die can introduce problems of its own that the bulge called a gauge band now gradually moves across the face of the collapsing frames. When you have such actions the web moves back and fourth between the two wood or plastic frames and the lay flat begins to wonder back and fourth in the down stream equipment starting at the nip rolls. With out pulling trim off of the both sides of the film a web guide would be required.

Generally gauge bands are caused by drafts of air or a heat rise off of the front of the extruder. As for a consequence the roll of film may be tapered or have a convex or concave face as the different thicknesses of film build up upon themselves in the roll.

Again as the bubble or die diameter is increased so is the transverse speed of the gauge bands across the face of the A-Frames which will also change the rotational speed. This can cause bubble instability, intermittent wrinkling in the nips and web wondering downstream that can be corrected by reducing the rotational speed.

However one rotation should never be less than the time it takes to build a roll of film or the gauge bands will not have time to be uniformly distributed across the entire face of the roll of film.

dbanig@prflexbag.com http://www.prflexbag.com

Plastic Film Extruder Operators can Prevent Defects!

All possible plastic film defects ought to be detected and eliminated by the film extruder before the roll gets shipped to the customer. But in practice, through oversight and inattention to detail defects can slip by that may be all too easily spotted by the customer or the customer's customer. I have found a variety of unrelated faults that fit into this category.

First is the appearance and a good looking finished plastic roll of film this aspect can be half of the battle. Keep in mind is that first impression what you see is what you get! A superficially ugly looking roll which may convert on the filling machine or bag machine can have the operator looking at the roll much closer for the entire lot for real or imaginary defects.

A roll that has a machine cylinder look means no scuff marks, damaged edges, and fuzzy ends, protruding or buried core ends, or crushed cores. The solutions to these problems are self evident. There are other finer detailed defects that can be buried in the roll, and may be if the production line is never approached by the operator except during a roll change. There is no excuse for the customer being the first to see these.

I have a couple of areas for helping prevent roll defects:

How to Tackle Blocking of the Plastic Film - a common reason for blocking is too much winding tension. This maybe over looked unless tension is so great as to crush the core as the film is being wound on the roll. This makes it impossible for the operator to remove the roll from the winder shaft. With a case of crushed cores, the rolls may be hard to get off of the shaft, only to have the customer find them impossible to remount on a un-wind stand.

Just as bad of a problem can arise if the winding tension is too light, no blocking but the film may telescope from one end of the roll, making it impossible to convert into finished product.

Hot weather can bring its share of blocking problems. Plastic Film is insufficiently cooled and the inner surface blocks as they pass through the nip rolls. For a cure you must reduce the output, raise the tower height or nip rolls, or use refrigerated air or other means of improving cooling efficiency. It also can be an inefficient air ring.

An entirely different cause of blocking can be using a resin to produce 1 mil film that has a slip and anti-block additive level designed for heavier gauges like 4 mil. There just isn't enough additive to do the proper job. Over-treatment and or high gloss can aggravate if not cause blocking with any of the above conditions.

Tendency to

Split

- Plastic Film with splits tendencies can also be overlooked unless samples are taken to examine, or actually tested. Insufficient cooling, a high frost line or to low of a blow up ratio, separately or a combination can accentuate the machine direction or orientation of the film causing the film to become splits. Also your nips in the tower maybe to tight particularly with an old and hardening nip roll which can deform the plastic film in the edge crease and make it splits. Die lines or another name is weld lines from the extrusion die make splits film as can scratches from the collapsing frame in the extrusion tower or a bur that has developed if using wooden collapsing frames. But not so readily detected are the fine weld lines caused by degraded particles of resin or dirt lodged under or in the die lips that make the film extremely split at the weld.

Good operator observations to equipment maintenance, quality testing of roll samples and putting the proper procedures in place will help in building customer loyalty.

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dbanig@prflexbag.com

Stretch Hooder Films

Stretch Hooder Films

Stretch Hooder film allow for an environmentally safe, cost effective, energy saving and convenient way to palletized materials. Stretch Hooder Films combine the weather protection and load stability advantage of pallet covers with the economy of stretch film.

Stretch Hooder films make use of co-polymers to stretch a film without permanent deformation. The film stretches in the elastic region of a typical engineering stress strain curve, and never reaches the plastic region of permanent deformation. This allows the film to snugly form around the dimensions of the pallet, which limits movement and protects the contents from dirt and water contamination.

A one piece hood is made in the machine from a continuous roll of lay flat tubing or gusseted film. The hood is stretched over the load and secured under the pallet. Stretch Hooder Films are ideally suited for applications where pallet loads require five sided protection, encounter stress during shipping or where products are sensitive to heat.

Benefits of Using Stretch Hooder Films

Pallet loads that have been packaged using stretch hooder films are secured for transportation. You get great tension in both horizontal and vertical directions which mean that the finished goods are pressed downwards on the pallet preventing the load from shifting.

The unbroken stretch hooder film utilizes packaging film without the use of any heat or glue. This method minimizes energy usage that is usually used by a heat gun to shrink the material. Improves safety in the workplace of a potential fire.

Pallets packaged with stretch hooder films are better than your standard shrink pallet covers or stretch film.

Stretch Hooder Film is well suited for printing a logo or company name which allows for promotion during distribution of finished pallets.

Stretch Hooder technology has the opportunity to increase the process of securing and palletizing of your load over stretch film or shrink film.

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dbanig@prflexbag.com

Sustainable Packaging

Sustainable packaging addresses performance and cost along with maximizing the use of renewable types of plastic materials or the use of recycling of other various materials like paper or cardboard. I figure the following factors would contribute to cost savings. The use of renewable or recycled source materials; able to manufactured using clean production technologies and best practices; make products from materials healthy in all end-of-life scenarios; designed to optimize materials and energy; effectively recover and utilized in biological or industrial cycles.

If we look at improving packaging sustainability it will result in less waste and will allow for fewer materials going into the land fill. Looking at the entire life cycle of packaging, the definition gives us a vision for the packaging industry all of which must be addressed if sustainable packaging is to become a major factor. It presents a challenge to those that stay status-quo but will offer guidance to identify the opportunities and the strategies to help us move forward. One of the key strategies is to challenge the product design, as it stands to point out we can prevent waste, if we optimize our use of resources, select safer materials and plan for the recycle process or some recoverability of our packaging.

However, even the most well designed packaging does not meet the sustainability test the real challenge is to be able to put effective systems into recoverability of the value of the materials. Building effective and closed-loop recycling and composting systems for packaging materials will be one of the biggest challenges to the creation of the sustainable packaging industry, but is one from which everyone stands to gain from personal use and manufacturing.

www.prflexbag.com dbanig@prflexbag.com