Information on Tyvek by du Pont

 

 

Du Pont's web page TyvekŪ for Graphics features a description of TyvekŪ's properties and possible uses for that material. There is no suggestion for the use of TyvekŪ in the production of bank notes. Nevertheless, the web page gives a general idea about TyvekŪ that had been used for printing banknotes in 1980s. Below are some excerpts from that web page.

 

TyvekŪ—creating new dimensions in graphics

 

It isn't paper, fabric or film—but the best combination of all three: TyvekŪ is very fine polyethylene fibers, seven times finer than human hair, spun in a random pattern. Bonded by heat and pressure, it's a printing substrate with exceptional strength, a natural look, and an original texture that's ideal for endless graphic challenges—industrial to household, for indoors and out. Take a look at how others are using this versatile material. Fine fibers bonded under heat and pressure, TyvekŪ makes for an incredibly durable printing surface. Here you can find an image of Tyvek, magnified 200 times.

 

TyvekŪ is ...

 

TyvekŪ brand protective material is a miracle of science from DuPont. It is a family of tough durable sheet products of high-density polyethylene fibers. The sheet is formed first by spinning continuous strands of very fine interconnected fibers, and then bonding them together with heat and pressure.

 

TyvekŪ is white, non-toxic, chemically inert and contains no binders. The non-woven sheet, after bonding, combines a good printing or coating surface, high opacity and toughness to a degree unique among sheet products of similar weight and price.

 

TyvekŪ is produced in three different types, namely 10, 14 and 16. The fibers in Type 10 Style are bonded to form a tough, dense, opaque sheet. The dense packing of the fine, interconnected fibers produces a smooth surface, high opacity and whiteness. The large number of bonds per unit area results in a stable and abrasion resistant surface with a stiffness similar to paper. Fiber bonding of Types 14 and 16 is restricted to discrete points in the non-woven sheet, producing a high degree of fiber mobility, and giving the non-woven a fabric-like drape.

 

Made by bonding webs of fine fibers with heat & pressure, nonwovens are an incredibly durable printing surface.

 

A unique, proprietary manufacturing process perfected by DuPont over 24 years ago makes TyvekŪ ideal for a variety of applications.

 

Working with TyvekŪ

 

TyvekŪ is a unique nonwoven printing medium. It's not paper. It looks different from paper. Its not like synthetic films. It feels more natural, with flat, precision folding qualities. Its not a fabric, although it can be used like fabric.

 

Made by bonding webs of fine fibers with heat and pressure, nonwovens are an incredibly durable substrate. TyvekŪ blends the best traits of fabric, film and paper. Account for the differences TyvekŪ brings and get reliable printing results every time.

 

Prepress—planning for success

 

  • TyvekŪ with antistatic and corona treatment is strongly recommended for improved adhesion of inks, coatings and adhesives.

  • Pretest ink and TyvekŪ interaction before the production run.

  • For a reasonable color match, select PantoneŪ colors from the uncoated color set. For an exact color match, prepare a sample using the match ink directly on TyvekŪ.

  • Depending on the style of TyvekŪ, dot gain will increase 15 to 20% compared to coated paper.

  • Dot gain is more prevalent from the 35% to 50% dot area. This is different from paper where dot gain is normally maximized at the 50% dot

  • Adjust the reproduction curve for 80% in the maximum areas. Allow for corresponding lightening in the other tonal areas.

  • Minimize the highlight dot. Allow specular highlights to go to zero.

  • UCR and GCR should be used as much as possible.

  • Opaque inks are best for tints.

  • Fiber swirl is an artifact of the strength of TyvekŪ. This should be kept in mind when designing artwork for printing on TyvekŪ.

  • In general, you will need 15% more ink to achieve color densities similar to uncoated paper.

  • Test the compatibility of solvents in inks, coatings and adhesives by placing two or three drops on TyvekŪ. Check for any distortion after 20 minutes.

  • Because TyvekŪ absorbs little or no moisture, plan on longer drying times than paper. As with any printing, allow more drying time with heavier ink coverage.

  • During any phase of processing do not expose TyvekŪ to temperatures above 175°F. In general, the higher the temperature the more TyvekŪ will distort.

  • To avoid static, maintain a relative humidity of 50% or greater.

  • For critical print clarity, print on the smoother side of TyvekŪ.

Printing

 

TyvekŪ can be printed by all conventional printing processes—letterpress, offset lithography, heat-set web offset, flexography, gravure, and screenprinting.

 

TyvekŪ is also thermal transfer printable. For best thermal transfer results, printing on the smooth side of TyvekŪ Brillion™ styles is recommended.

 

For wide format ink jet printing, a TyvekŪ with an ink jet receptive coating is required in order to achieve acceptable results. Numerous companies offer ink jet compatible TyvekŪ based products.

 

Hot process laser printing and photocopying are not suitable with TyvekŪ.

 

Converting

 

DuPont TyvekŪ is composed of 100% high density polyethylene fibre. It is a tough, durable, tear-resistant material that is unaffected by water. TyvekŪ retains its flexibility to -73°C (-100°F) but being a thermoplastic material it melts at 135°C (275°F). TyvekŪ can be converted in much the same way as paper or plastic films and on the same equipment. If you understand the properties of TyvekŪ , you will find converting to be much easier.

 

All styles of TyvekŪ with a "D" or a "R" suffix are antistated and permanently corona treated.

 

TyvekŪ will stretch up to 30% before breaking. To minimize distortion or neck down during roll fed converting, keep tension less than 1.4 N/cm (0.75 pounds/inch.) A floppy web is recommended. This is particularly true when die cutting TyvekŪ business forms with rotary punched sprocket holes.

 

Slitting, Sheeting, Cutting

Because TyvekŪ fibres are very strong, each must be completely severed; hangers will not break off. Knives, dies and punches must be set to close tolerances. A sharp, slightly rounded edge gives longer service than a pointed edge for crush cutting, but a sharp edge is preferred for other slitting methods.

 

Rotary Die Punching

Because soft steel male/female rotary dies dull quickly when Set to the close tolerances required to punch TyvekŪ cleanly, the use of rotary dies made of hardened tool steel or tungsten carbide is recommended. A list of manufacturers of these dies for TyvekŪ is available from your TyvekŪ Technical Specialist.

 

Die Cutting

TyvekŪ can be die-cut using either steel rule, male/female or closed dies. TyvekŪ fibres must be completely cut and dies must be in good condition with sharp, nick-free edges. Dull dies cause edges to curl. When using closed dies, the use of a side cutter with internal relief is recommended. Deaerate and keep lift height below 7.6 cm (3 inches) when die cutting to avoid oversizing to blanks.

 

Punching

TyvekŪ can be punched on tag, letterpress and rotary line-hole equipment. Best results are obtained for sharp, well registered and closely fit punches. Punches may be either smooth or serrated and cut best if ground concave on the ends. A soft self-honing male punch in a hardened female die is recommended.

 

Folding

TyvekŪ will take a dead fold and can be folded on conventional bindery folders. An increase in roller and spring tension will produce sharper creases. Due to the inherent slippery surface of TyvekŪ, soft, rubber-covered rollers will aid feeding.

 

Perforating

For clean-tearing perforations, use the maximum practical number of cuts with the smallest land (reserve) between them. An 8:1 ratio (1/4” [6.4mm] cut with 1/32” [0.8mm] reserve) is recommended.

 

Embossing

TyvekŪ can be embossed with either high or low pressure equipment. Cold embossing does not significantly reduce the strength of TyvekŪ. It does, however, reduce opacity. Embossing cylinders used for TyvekŪ usually are very shallow, having a depth of only 0.13-0.65 mm (5-25 mils.). A Shore "D" hardness of 70-80 for the rubber back-up cylinder is preferred.

 

Foil stamping

This is readily accomplished on TyvekŪ due to its thermoplastic nature. A variety of foils is available from suppliers for label and book cover applications. A foil that will transfer cleanly to TyvekŪ between 135-160°C (275-325°F) should be chosen. Large, solid foil-stamped areas tend to pucker and distort TyvekŪ and should be avoided.

 

Coating

When coating or laminating TyvekŪ, the web temperature should not exceed 79°C (175°F). Coatings are used to color, improve print fidelity, add gloss or mask the fibre pattern of TyvekŪ. Air-knife coating is preferred for aqueous coating because it applies a uniform thickness of coating on TyvekŪ. Usually an increase in binder content is needed to achieve acceptable coating adhesion to TyvekŪ. The air knife also produces a very smooth surface which is ideal for printing. Gravure coating is preferred for solvent-based systems, particularly where deep coloration is required.

 

Dyeing

Conventional textile dyeing processes do not impart permanent color to TyvekŪ. For this reason, Type 14/16 TyvekŪ is usually printed by the flexographic or gravure process using either solvent or water base inks. Sublistatic printing of TyvekŪ is not recommended because of the high temperatures used.

 

Laminating

TyvekŪ can be extrusion, adhesive and calender laminated. Extruded, branched polyethylene is an excellent adhesive for laminating foil and film to TyvekŪ. Polyurethane adhesives can be used to adhere a variety of films and fabrics to TyvekŪ. When laminating TyvekŪ to paper or board, it is important to completely cover TyvekŪ with adhesive to prevent bubble formation.

 

Heat Sealing/Dielectric Sealing/Ultrasonic Sealing

Heat sealing TyvekŪ to itself or other films is usually accomplished by applying a heat seal coating such a branched polyethylene to one of the materials. High seal strength can be achieved using hot-bar or impulse techniques. TyvekŪ cannot be dielectrically sealed under ordinary conditions because it is non-polar. Recent developments in ultrasonic sealing have demonstrated seals almost equivalent to heat seals.

 

Gluing

Natural product adhesives based on dextrin, casein or animal byproducts can be used to adhere TyvekŪ to itself and a variety of paper materials. Water based synthetic lattices such as the ethylene/vinyl acetate adhesives form fibre tearing bonds with TyvekŪ. Hot melt polyamide adhesives are available which form good bonds to TyvekŪ with a variety of materials. Acrylic pressure sensitive adhesives are commonly used with a release liner.

 

Sewing

TyvekŪ can be sewn on conventional sewing machines. Best results are obtained with machines equipped with puller or drop-feed. Smooth, rubber covered rolls should be used rather than knurled metal rolls which tend to leave impressions on TyvekŪ.

 

Stitching

When stitching the Type 10 styles of TyvekŪ, 2-3 stitches/cm (4-5/in.) and the smallest needle practical should be used to avoid postage stamp tears. On soft type 14/16 TyvekŪ, it is recommended to sew rough side to rough side.

 

Finishing

  • Keep cutting parts clean and sharp, with true, well supported, nick-free edges.  

  • For crush cutting, a sharp, slightly rounded edge gives longer service than a pointed edge.  

  • When using non-antistatic styles of TyvekŪ, use conductive tinsel or ionized air.  

  • Die-cut with either steel rule (sharp edge) of male/female dies. Dies must be set up to completely cut the TyvekŪ fibers. An incomplete cut will not allow the die-cut TyvekŪ to release properly.  

  • A soft, self-honing male punch in hardened female die is recommended for punching.  

  • For clean-tearing perforations, use the maximum practical number of cuts with the smallest land (reserve) between them. An 8:1 ratio (1/4" [6.4mm] reserve) is recommended.  

  • Use conventional bindery folders. Increase roller and spring tension for sharper creases.  

  • TyvekŪ can be extrusion, adhesive and calender-laminated.  

  • For gluing TyvekŪ, water-based adhesives that provide quick tack and fast drying are best. 

  • Embossing cylinders for TyvekŪ should be very shallow. 5 to 25 mil (0.13 to 0.65mm) is recommended.

  • Keep foil stamping area under 2" x 2" (50mm x 50mm) to avoid distortion.  

  • When stitching TyvekŪ, use the least number of stitches per inch and the smallest needle practical for maximum tear resistance.

Recycling

 

Reduce.

TyvekŪ offers superior strength and durability relative to its light weight. TyvekŪ typically weighs half as much as other printing substrates. TyvekŪ provides significant source reduction opportunities, helping to meet resource conservation goals. It simply takes less material to make TyvekŪ when compared to other film and paper substrates. The reduced weight offered by TyvekŪ can result in fuel savings during the transportation of roll and sheet deliveries.

 

Reuse.

If reuse or recycling is not an option, TyvekŪ can be cleanly incinerated, and the high energy value can be utilized. Also, because TyvekŪ is chemically inert without binders, it can be safely disposed of in landfills.

 

Recycle.

TyvekŪ is made entirely of high-density polyethylene (HDPE), one of today's most commonly recycled plastics. More than 70 facilities in North America are available to recycle TyvekŪ. TyvekŪ can be recycled into durable goods, such as drainage pipes, plastic lumber, park benches and even fishing lures—continuing a cycle of resource conservation.

   

FAQ

 

Q:  Does TyvekŪ require special printing inks?

A: Yes. TyvekŪ normally requires inks that are of a different formulation. This is not necessarily a problem since the majority of ink manufacturers can supply this ink. This ink sensitivity is also true of other synthetic materials. In offset printing, TyvekŪ requires an ink with a low VOC content (volatile organic compound). Ask your printer or ink supplier for inks that are compatible with TyvekŪ and have a VOC content of 3% or less. For flexography, most of these inks are water-based and normally cause no problems when printing on TyvekŪ. Screen printing inks should be formulated specially for printing on TyvekŪ. Any major ink supplier has these formulations in their manufacturing process. The best rule of thumb is to communicate with your printer or ink supplier that you will be printing on TyvekŪ. Another good tip is to supply the ink supplier with a small sample of the style of TyvekŪ you will be using. The ink supplier can then test their inks on TyvekŪ and adjust the formulation, if necessary. This also gives you a good look at the final color of the inks when applied to TyvekŪ.

 

Q: Does TyvekŪ come in pressure sensitive grades?

A: DuPont relies on pressure sensitive coating companies to coat TyvekŪ for pressure sensitive label applications. TyvekŪ is compatible with a wide variety of pressure sensitive adhesives.

 

Q: Which printing processes are compatible with TyvekŪ?

A: TyvekŪ can be printed using the following methods: offset (sheetfed & web), flexography, letterpress, gravure, thermal transfer, and dot matrix. In general, if the temperatures of the process stay below 175 degrees F, then TyvekŪ can be imaged. Keep in mind that part of the process is drying and the dryer temperatures must adhere to the 175 degree rule. TyvekŪ does not produce acceptable results when imaged with a wide format inkjet printer. For wide format inkjet printing, a TyvekŪ with an inkjet coating is required. Numerous companies offer inkjet compatible TyvekŪ.

 

Q: Will a die last as long on TyvekŪ as on paper?

A: Because of the superior strength and durability of TyvekŪ over paper, certain considerations should be made when cutting TyvekŪ. Hardened dies in good, sharp condition provide the best optimum performance for cutting TyvekŪ.

 

Copyright information

 

Copyright Đ 1995, 1996, 1997, 1998, 1999, 2000 E. I. du Pont de Nemours and Company
1007 Market Street, Wilmington, Delaware 19898, USA
All Rights Reserved