Your printing has never looked so good.
You want what you print to stand out. Memorable color quality and a distinctive texture—they’re part of what turns an ordinary print job into something special.
The lightweight, smooth surface, high dimensional stability and opacity, together with the toughness and durability of DuPont™ Tyvek® protective material make it a popular printing substrate. It can be printed using most commercial printing processes. Some digital press applications and most ink-jet printers require a special coating. Tyvek® Brillion® is recommended for bar code thermal transfer printing. It can be printed either sheet or web-fed. Tyvek® has a rough and a smooth side. Always print on the smooth side first.
DESIGN/PREPRESS TIPS
Designer and printer must understand the unique properties and characteristics of printing on Tyvek® Higher basis weight styles are recommended for two-sided printing. Two days should be allowed for two-sided printing due to the need for a 48-hour dry time before printing the second side. It is important to identify critical colors in the planning and design stage. Color matching of ink must be done because a color shift will occur when going from paper to Tyvek®.
Pantone® Matching System (PMS) colors can be specified, but the ink must be matched on Tyvek®. Always refer to PMS colors printed on uncoated paper (U) in the PANTONE® Color Formula Guide when selecting colors.
When a special color, such as a corporate logo color, is to be printed in a four-color process piece, it is highly recommended to print the special colors as a fifth or sixth non-process (PMS) color on a six-color press. This will allow more freedom to correctly color match the four-color subject without shifting the corporate logo colors.
Gold and silver metallic inks can be printed on Tyvek®; however, due to the light scattering effect of the fiber pattern, a bright, shiny metallic effect is not achieved. Foil stamping is a better alternative. When printing white on white, specify that the white be as white as possible. Alternately, a shadow line or border may be added to enhance the separation. Spunbonded olefin has an inherent fiberswirl pattern that cannot be covered up by laying down more ink.
 |
| DuPont™ Tyvek® is an ideal choice for packaging today’s sensitive CDs and DVDs. |
Dark solids accentuate the appearance of fiber swirl; whereas, small, busy patterns using light colors and screens minimize the appearance of fiber swirl. Fiber swirl can sometimes be minimized in large areas of light colors by using opaque colors (e.g., ocean blue on a map).
Tyvek® is not coated paper and does not provide a glossy print surface. Increasing the ink film thickness will not achieve higher gloss, but will cause ink distortion and increased ink drying time. Press varnish does not noticeably improve gloss or ink rub resistance; however, it does accentuate the appearance of fiber swirl. Because of its very bright blue-white surface, most press varnishes appear slightly yellow on Tyvek® and are not recommended. UV cured inks generally appear brighter and more glossy and are recommended. Film laminations on Tyvek® will provide a very glossy, abrasion-resistant surface.
If color is critical, a press proof using Tyvek® is the only sure way to check color. When doing four-color process printing, avoid using fine reverse lines, borders and type of less than 6-point. A two to three dot overlap trap is required.
Whenever very tight register is required the color with the least amount of ink coverage should be printed on the first unit, followed by increasing amounts of ink coverage on subsequent units.
Guidelines for Printing
DuPont™ Tyvek® protective material is printed in much the same way as other synthetic papers. Before production you should conduct ink, material and printing evaluations.
CHARACTERISTICS OF DUPONT™ TYVEK® THAT AFFECT PRINTABILITY
- Properties of DuPont™ Tyvek® are unaffected by water; however, solvents with high VOC’s used in some commercial inks can cause swelling—either immediately or after sheets have been printed. Solvent distortion will cause misregistration and sheet swelling. For this reason, sheet-fed offset lithographic and letterpress inks must be formulated with less than 3% volatile solvents. See pages 32-34 for solvents that are recommended.
- Because Tyvek® is not as absorbent as paper, lithographic/letterpress inks take longer to dry. As with all synthetic papers, you must use inks that dry through oxidation, not absorption.
- Uncoated spunbonded olefin has a unique fiber-swirl pattern that will show through most inks. The appearance of fiber swirl can be minimized by using light colors and a “busy” multi-color pattern. Opaque inks should be used whenever possible. Coated spunbonded olefin is recommended when the end-use application calls for optimum ink “hold-out”; high-gloss, high-fidelity printing; or increased surface abrasion resistance.
- The melting point of Tyvek® is 275°F (135°C). During web handling operations, the web tension should not exceed 0.75 lb/in (1.4 N/cm) width and the sheet temperature should not exceed 175°F (79°C).
- Heat transfer and dye sublimation printing is not recommended because the temperatures used to transfer the dyes exceed the melting point.
- Tyvek® styles with a “D” suffix (e.g., 1073D) and Tyvek® 1079 are treated with an antistatic agent to reduce static during sheet handling operations. Antistatic agents function best at a relative humidity of 50% or more. Below 20% relative humidity, antistatic agents lose their effectiveness and sheet feeding will become noticeably difficult. The above-mentioned styles have also been treated by corona discharge to improve adhesion of inks, coatings and adhesives.
- Tyvek® styles with a “B” suffix (e.g., 1059B) are untreated and are used primarily for medical applications where optimum barrier properties are required. If a printer is uncertain whether Tyvek® is corona treated, a simple “Water Drop” test can be performed as follows:
- Place a drop of water on the unknown sample and on known samples of Tyvek® 1059B and 1073D. Tilt each sheet until the drop rolls off and observe whether wetting has occurred. Water will wet out the treated style, 1073D, whereas the drop of water will remain as a ball and roll off the untreated sheet of 1059B without leaving a wet “track.”
- Unlike polyethylene film and other synthetics, spunbonded olefin does not lose the effectiveness of corona treatment with time. Samples of corona-treated Tyvek® stored for 20 years were found to have the same level of ink adhesion as a newly treated sample.
- DuPont™ Tyvek® is two-sided. The hard structure styles have a rough or “wire” side, and a smooth side. The difference is minor, but can usually be felt, and can be seen easily under a low-power magnifying glass. Where print clarity is most important, the smooth side should be used. Tyvek® 1079 is embossed with a fine cambric pattern. As with the other hard structure styles, the smooth side is preferred for printing and coating. The soft structure styles have a linen and rib side. The linen side is preferred for printing because of better ink hold-out and better surface fiber stability. The linen side is also smoother than the rib side. However, garment fabrication may dictate that the rib side be printed with some sacrifice in print quality.
- To reduce curl or improve the lay-flat after printing, observe the following for Tyvek® hard structure styles:
- For one-sided printing, print the rough or “wire” side.
- For two-sided printing, print minor coverage on the smooth side first, followed by major coverage on the rough side.
- Allow at least 0.5 in (13 mm) unprinted border.
NOTE: Heavy edge-to-edge print coverage on the smooth side, followed by die-cutting into small blanks (for example, in envelopes) can result in curling, therefore, follow the recommendations above.
- Tyvek® is nearly isotropic. Its physical properties are approximately equal in the machine and cross-machine direction. This attribute is unique to Tyvek®.
DuPont™ Tyvek® Can Be Printed by Various Processes
DuPont™ Tyvek® brings greater flexibility to what you print and to the methods you can choose to print them. You can successfully use Tyvek® with practically all of the most commonly employed printing processes.
OFFSET LITHOGRAPHY
Items requiring good quality color and appearance can be printed on Tyvek® spunbonded olefin by the offset lithographic process.
Tyvek® is dimensionally stable and handles well on both large and small, single- and multi-color offset lithographic presses.
Four-color process work should be done using a four-color press. Four-color process printing on a single-color press is not recommended because misregistration can occur due to sheet swelling between colors. Special low-solvent-content inks are required for offset lithographic printing of Tyvek®. These are described in detail on page 15 under “Printing Inks for Tyvek® Spunbonded Olefin”. UV-cure inks are being run routinely on spunbonded olefin by the sheet-fed litho process.
These inks cure instantly and do not distort the product. Wet and dry rub resistance is at least equivalent to conventional oil-based ink.
To further minimize sheet distortion caused by ink, the ink film thickness should be kept to a minimum by using extra strong colors. Tints should be made using opaque white rather than extender, whenever possible.
When printing four or more colors that completely cover a large sheet, the color sequence should be chosen so that the color with the least coverage is laid down first and the color with the greatest amount of coverage is laid down last.
Spunbonded olefin has a pH of 7 (neutral) and does not affect the chemistry of the lithographic dampening system. Because DuPont™ Tyvek® protective material absorbs little water, the dampening solution should be maintained at a minimum level to avoid a pastel or washed-out appearance of the printing; i.e., only enough dampening solution should be added to prevent dryup in the non-image areas.
If printing black colors, sometimes after printing 25 to 50 sheets, the printed image will appear dull or gray. This is due to a build up of dampening solution. Because Tyvek® does not absorb water as readily as paper, the amount of dampening solution must be reduced. It may be necessary to reduce the level several times. This will also prevent ink emulsification and shorten the ink’s drying time.
Because of its extremely high surface area Tyvek® will require approximately 15% more ink to achieve the same color density as uncoated paper. Tyvek® will not take on the gloss of coated paper.
Tyvek® is more compressible than either film or paper. It is necessary to add 3 to 4 mil (0.08 to 0.10 mm) of additional squeeze between the blanket and back cylinder versus paper of equivalent thickness to compensate. Excessive pressure will cause dot gain and result in misregistration. Printing on Tyvek® that has been deeply and sharply embossed should be avoided as it is difficult to obtain adequate ink fill without excessive pressures, which may result in sheet distortion.
Conventional offset blankets of medium hardness are recommended for lithographic printing of uncoated Tyvek® because they afford the best results with large, solid print areas and halftones. Compressible blankets are preferred for printing coated Tyvek® because they improve print uniformity in large halftone-screen areas, particularly when trapping screens with solids.
FOUR-COLOR PROCESS PRINTING OF STYLE 1443R BY SHEET-FED OFFSET LITHOGRAPHY
DuPont™ Tyvek® 1443R spunbonded olefin is used for fabricating promotional apparel. Superior graphics can be obtained using four-color process sheet-fed offset lithography. The advantage that Tyvek® offers over other materials is that four or more colors can be printed on the linen (smooth) side while maintaining precise register, high-fidelity print quality (150 lines/in [60 lines/cm]) screens and good ink hold-out.
The challenge to the printer who chooses to do this on a sheet-fed press is formidable, but it is being done routinely.
Lightweight, fabric-like Tyvek® 1443R is difficult to sheet-feed and requires a considerable amount of patience and feeder adjustment by the press operator. Style 1443R should be sheet-fed with the rib pattern parallel to the direction of sheet travel to obtain optimum register.
Because of its lightweight characteristics, the air used to separate the sheets must be reduced. Sheets up to 28 in. x 40 in. (70 cm x 100 cm) are much easier to feed and deliver than larger sheets. Printing is done on the linen (smooth) side to optimize ink hold-out and surface fiber stability. Because soft structures do not jog well, four-side trimming should be done near the press. Load the sheets into the feeder with as little handling as possible to avoid the need for jogging. Because of the difficulty in jogging sheets after delivery, multi-pass printing of Tyvek® 1443R is not recommended.
Low-solvent-content litho inks are recommended for sheet-fed printing of Tyvek® 1443R. These should be made at as low a tack as possible, generally 14-tack rating. Due to the lack of stiffness in Tyvek® 1443R, small folds or creases will occur in some of the sheets during printing. These creases will appear as narrow white streaks in the finished press sheets. Smaller sheets are less likely to crease than larger sheets.
OFFSET LITHOGRAPHIC PRINTING OF PRESSURE-SENSITIVE DUPONT™ TYVEK®
Most DuPont™ Tyvek® spunbonded olefin that is coated with water-based, pressure-sensitive adhesives for label stock can be printed by any of the commercial printing processes. Occasionally, Tyvek® will be coated with a water-based adhesive that contains an excessive amount of wetting agent. This wetting agent can migrate to the opposite side of the substrate and disrupt the ink/water balance of the offset lithographic press, producing a washed-out appearance in the printing. The effect is most noticeable in the thin areas of the sheet, but may appear over the entire sheet. Sometimes it is mistaken for insufficient impression. Dry-offset, letterpress or flexography processes can print Tyvek‚ with excessive wetting agents in the coating acceptably. If the wetting agent has migrated through to the side to be printed, it can usually be detected by using the “Special Blue R Dye Test.” In this test, an intense violet color is indicative of wetting agent on the surface. An uncoated sheet of Tyvek® 1073D should be tested at the same time as a control.
ENVELOPE IMPRINTING
Tyvek® Envelopes can be imprinted using standard envelope printing equipment. For light ink coverage, such as “corner cards,” standard paper inks can be used. For heavy ink coverage, such as logos, offset inks compatible with Tyvek® are recommended.
Because Tyvek® Envelopes are less rigid than paper envelopes, a “wedge” should be placed under the center of the feed stack to maintain a level feed with horizontal feeders. Printing quality on Tyvek® may be enhanced by using a “patch” blanket with offset presses. The patch blanket allows greater squeeze without interference from the flap ends.
HEAT-SET WEB OFFSET
Tyvek® prints nicely using the heat-set web offset lithographic process. Since it is composed of continuous fiber, it is nearly lint-free and reduces the downtime required for blanket/plate wash-up. In addition, the high tear strength virtually eliminates web breaks. Because of the heat and solvent sensitivity of Tyvek®, low-energy heat-set inks are required to print by this process. These inks contain low-boiling hydrocarbon solvents that flash-off at web temperatures of 175°F to 200°F (79°C to 93°C) and press speeds of 22,000 impressions/hour. Although the drying oven may operate at a temperature higher than 175°F (79°C), the temperature Tyvek® reaches should not exceed 175°F to 200°F (79°C to 93°C). It is a good practice to measure the web temperature with a surface pyrometer. In the case of sudden press shutdowns, provisions must be made to prevent it from melting in the dryer.
Tyvek® has been run successfully on web offset presses roll/roll, roll/sheet and roll/folded signature. Adjustment of the sheeter is crucial and requires a sharp blade set to a close tolerance. To avoid sheet size variation, web tension going into the sheeter must be at a minimum. Sheet cutoff has been maintained at ±1⁄32 in. (±0.8 mm) on a 239⁄16 in. (0.6 mm) sheet throughout production runs.
Both UV and electron beam ink-curing systems have been used successfully with Tyvek® on web offset presses. Because the inks used are 100% solids and cure almost instantly, higher color density and gloss can be achieved. UV-cured inks do not distort Tyvek®. Infrared drying is not recommended because of the heat generated.
FLEXOGRAPHY
DuPont™ Tyvek® spunbonded olefin is often printed using the flexographic process for a wide variety of applications, ranging from envelopes, tags and labels for commercial and industrial applications, and wristbands. Equipment used for single or multi-color web printing of flexible packaging materials is best suited to spunbonded olefin because it permits processing at low temperatures and tensions.
Web temperature should be kept below 175°F (79°C) and tensions kept below 0.75 lb/lineal in (1.4 N/cm) of width, to prevent sheet distortion and print misregister in multi-color work. Generally speaking, a floppy web should enter and exit from the printing nip. High-velocity, low-temperature drying air should be thoroughly mixed by the diffusers to avoid oven hot spots. Gas-fired driers should be carefully controlled because of the very high burner outlet temperatures. Powered rollers and short, unsupported web spans will help maintain the recommended low-unwind and processing tensions. Bowed rolls ahead of printing and windup stations are very effective in eliminating wrinkles and are required for printing soft structure. A chill roll prior to windup is helpful in reducing sheet temperature, thus helping to prevent ink blocking and minimizing sheet distortion. Chill rolls are essential for flexo printing on Tyvek® used for medical packaging, which is often coated with a heat seal coating on the back side. If this coating is softened, it will block and cause ink pickoff.
 |
| Flexo printing on DuPont™ Tyvek® is one of the most popular ways to produce everything from envelopes to tags and labels to wristbands. |
Resiliency is needed in flexographic plates to help offset the inherent thickness variations of spunbonded olefin. Photopolymer plates (such as DuPontTM Cyrel®) with a 50 Durometer hardness (Shore A) mounted with closed-cell foam sticky back will produce the best overall print uniformity.
GRAVURE
Tyvek® can be printed by the gravure process on equipment used for single- and/or multi-color printing of paper and films. Materials designed for use in packaging, book covering and apparel are currently being printed by this method. Gravure cylinders with 100 lines/in. (40 lines/cm) or more are preferred for printing both the uncoated and coated styles of Tyvek®.
As in flexography, the web temperature should be maintained below 175°F (79°C), with tensions below 0.75 lb/lineal in (1.4 N/cm) to avoid web neck-down and misregistration. The same precautions for web handling described for flexography apply to gravure printing.
INK-JET PRINTING
DuPont™ Tyvek® spunbonded olefin can be ink-jet printed for addressing and bar coding. For optimum performance, solvent-, oil-and wax-based inks are recommended. Selected, pigmented water-based inks can provide satisfactory performance by using special settings. When doing high-quality graphics, an ink-jet coated Tyvek® must be used.
SCREEN PROCESS
Tyvek® can be printed on hand, automatic and rotary screen presses in sheet and web form for signs, banners and other decorative uses.
When conveyor ovens are used instead of room-temperature drying, high-velocity air will aid drying and carry away the solvents. Sheet temperature should be kept below 175°F (79°C), with tensions below 0.75 lb/lineal in (1.4 N/cm) to avoid shrinking and misregistration in multi-color web printing. When using UV-cured screen inks, cooling is required to prevent sheet distortion or shrinking due to the heat generated. Screen process inks for Tyvek® are discussed on page 17.
LASER PRINTING (NON-IMPACT)
Conventional laser printing is not recommended on Tyvek® because of the temperatures involved in the printing units. For the same reason, Tyvek® should not be used in electrostatic copiers. However, Tyvek® can be used with the newer cold lasers (which generally have a fusing temperature below 200°F [93°C]).
THERMAL TRANSFER
All hard structure styles of Tyvek® are compatible with thermal transfer printing. Tyvek® Brillion® is recommended for bar code printing. All three types of ribbons can be used; however, under harsh conditions or in outdoor applications a wax/resin ribbon is recommended.
DIRECT THERMAL PRINTING
Currently, we do not have a product that will work with a direct thermal printer. A product for this application is under development.
DOT MATRIX PRINTING
A fade-resistant-non-bleeding ribbon is required for printing. This will allow the image to withstand a harsh environment. This is recommended as dot matrix printing is being used to imprint a variety of labels and business forms, especially those used for chemical drum labeling that require variable information, and in some cases, bar codes.
DIGITAL (ON-DEMAND) PRINTING
The Printing Applications Laboratory at the Rochester Institute of Technology (RIT) has certified DuPont™ Tyvek® Graphics styles for use with the Indigo Omnius® WebStream™, a web-fed digital color press.
Indigo presses represent a fast and cost-effective way to produce short-run work and incorporate variable information. As on-demand printing grows and printers continue to incorporate new digital technologies into their operations, DuPont™ Tyvek® provides the Indigo printer with a solution to a wide range of strength
and durability issues.
This certification applies to the following Tyvek® styles: 1056D, 8740D, 1073D, 1079, 1085D and 4173D. Other “D” styles of Tyvek® within the thickness range of 6 to 10 mils also are compatible with the Omnius® WebStream™. In addition, these styles are corona and antistat treated, therefore no coating is required.
Tyvek® meets the following application requirements:
- Superior strength-to-weight ratio and soft hand (race numbers, wrist tickets)
- Exposure to frequent liquid or chemical spills (drum labels, licenses)
- Protection of critical information for instruction sheets and directions (poison charts,
safety guidelines, trail guides, manuals)
- Excessive handling or folding (menus, brochures, maps)
- Outdoor exposure to extreme temperatures, inclement weather, heavy wind (signage, tags)
- A unique design element or texture (invitations, announcements)
Printing Inks for DuPont™ Tyvek® Spunbonded Olefin
There are many inks that are compatible for use with Tyvek®.
OFFSET LITHOGRAPHIC INKS
Tyvek® is largely unaffected by water or highly polar solvents (alcohols, glycols, esters). However, non-polar, volatile, kerosene-type hydrocarbon solvents used in some commercial inks will cause it to swell or pucker.
If Tyvek® swells, buckles or puckers within 20 minutes after printing, the ink probably contains a residual solvent that is incompatible with it.
The typical offset lithographic ink for use with Tyvek® is formulated from rosin esters and long oil alkyds. These can be diluted with drying oils, such as tung (chinawood oil) or linseed oil. In addition, 100% solid soy-based resins are also compatible. High-boiling, “quick-dry” petroleum solvents should not be used in sheet-fed offset-litho ink formulations. Likewise, aliphatic hydrocarbon resins should be avoided because they can also cause distortion and sheet swelling. “Dry pigment grinds” should be used to avoid the residual solvent in pigments made from flushes. Magie® oils should be avoided.
To minimize the tendency of spunbonded olefin to curl or pucker, the least possible ink film thickness should be applied, with a goal of 0.3 mil (0.0076 mm). In some cases, using a 60% screen will beneficially reduce ink coverage. When tints are used, the ink should be made with opaque white rather than transparent extender. This will minimize the swelling effect the extender might have. Opaque ink will also reduce the appearance of the fiber-swirl pattern. Offset/letterpress inks dry more slowly than conventional paper inks. To minimize offsetting, pile height should not exceed 20 in. (0.5 meter). Winding is recommended after 6, 12 and 18 hours for sheets with heavy ink coverage. To shorten the drying time of inks, contact the ink supplier for the amount of ink drier that can be added. Excessive ink drier can hinder drying and may cause distortion. Offset powders are seldom needed. When excessive ink drying time is required, it is usually caused by too much ink and excessive dampening solution, resulting in ink emulsification. Fountain stimulators used to increase the rate of drying are only marginally beneficial, but can be used if desired.
Most commercial dampening systems work well with Tyvek®, but only enough dampening solution should be used to prevent dry-up in non-image areas. Because Tyvek® absorbs less water than paper, it requires less dampening solution. If the printed image is dull or has a washed-out appearance, the amount of dampening solution should be reduced. For optimum drying, the fountain solution should be maintained at a pH between 4 and 5. Litho inks with more than 3% volatile solvent can cause swelling, puckering, curling and misregistration. Solvent content of as-supplied resins should also be checked prior to use to ensure that the volatile solvent content of the finished ink remains below the recommended 3% maximum.
If it is necessary to reduce the tack of an ink, “000” varnish, tung oil or a reducer recommended by the ink supplier should be used. It is important that volatile materials, such as aliphatic hydrocarbon solvents, not be added indiscriminately to offset-litho inks. For this reason, it is strongly recommended that ink suppliers be consulted before any attempt is made to modify ink for use with Tyvek®.
METALLIC LITHOGRAPHIC INKS
It is difficult to print metallic inks on DuPont™ Tyvek® spunbonded olefin because they tend to pile on the plate and/or blanket (as with paper). Aluminum (silver) looks best because the fiber swirl enhances the metallic look.
Gold is usually a two-component ink and should be mixed just before using. Two light passes will reduce the tendency to pile. Gold usually looks dull on Tyvek®. In some cases, aluminum overprinted with yellow will produce an attractive “gold” color. Wet trapping of metallic inks should be avoided when possible. An alternative would be either dry trap or reverse out the metallic color.
If Tyvek® is printed with a metallic ink and will later be glued (e.g., an envelope), the glue must be compatible with metallic inks, otherwise, the metallic effect will be lost and the color may shift. Adhesives containing acetic acid should not be used if metallic inks have been used.
UV-CURE INKS
 |
| For colors that stand up to the elements as well as the DuPont™ Tyvek® banners and signs they’re printed on, use screen inks with fade-resistant pigments. |
UV-cure inks work well with Tyvek® and can be used for offset, flexo, ink-jet, and screenprinting. These inks are 100% solid systems that are instantly cured, eliminating the risk of solvent distortion and provide a means of getting high-density dark colors with improved gloss compared to conventional linseed/alkyd inks.
Although short exposure to UV radiation has no effect on the physical properties of Tyvek®, a cooling system to reduce heat buildup is recommended because of its thermoplastic nature. It is difficult to achieve a high level of ink gloss and a reduction in fiber swirl on uncoated Tyvek® without first putting down a heavy base coating. However, a reasonably high level of gloss has been achieved on uncoated Tyvek® via electron beam top coating. Heavy, clear top coatings can be applied in-line with printing and instantly cured via the electron beam process.
INFRARED-CURE INKS
Infrared (IR) drying is not recommended for sheet-fed litho printing of Tyvek®. IR-cure inks dry rapidly by “flashing off” solvent under an IR heat unit near the delivery end of the press. Because offset inks for Tyvek® are formulated with little or no solvent, they do not respond well to IR drying. Special high-solvent-content IR inks distort spunbonded olefin and, at slow running speeds, the heat generated by the IR dryer can cause it to shrink.
SCREEN PROCESS INKS
A variety of screen process inks are available for printing DuPont™ Tyvek® spunbonded olefin. Lacquer-type inks are preferred because they produce a minimum amount of distortion. Screen “poster inks,” and enamels that contain a high percentage of mineral spirits, should be avoided. Water-based inks are compatible with Tyvek® because they minimize sheet distortion, even with heavy ink-film thicknesses. If Tyvek® is to be used outdoors, screen inks with fade-resistant pigments should be requested from the ink supplier to avoid loss of color.
Screen printing of Tyvek® 1443R for apparel requires an ink with optimum adhesion, flexibility and wet rub resistance. Solvent-based urethane screen inks are preferred for this type of application. When selecting solvents to adjust the screen open or drying time, refer to Table V on page 34 and choose a solvent as close as possible to the top of the list to minimize swelling and puckering. Methyl and butyl Cellosolve® work well for adjusting screen open-time when compatible with the ink system.
FLEXOGRAPHIC INKS
For flexographic printing, volatile solvent inks and aqueous inks are available for use with Tyvek®. Polyamide/alcohol inks are preferred because of their optimum level of adhesion and rub resistance. Nitrocellulose can be added to produce a harder ink film, but with some sacrifice in adhesion.
Microcrystalline wax is usually added to inks for medical packaging applications to reduce offsetting. Because Tyvek® 1059B is not corona-treated, ink adhesion will not be as good and precautions must be taken to avoid offsetting and blocking. When used on medical packaging styles, inks must have adequate thermal resistance so they do not block when heat-sealed.
GRAVURE INKS
Flexographic inks are very similar to gravure inks. Type C nitrocellulose gravure inks are the most widely used for printing Tyvek® and they are often modified by the addition of an alkyd resin to improve ink hardness and adhesion.
GLOSS AND COLOR MATCHING
Ink gloss and color are important factors in the final appearance of printed Tyvek®. High gloss and darker colors accentuate the unique swirl pattern of uncoated Tyvek®. Conversely, the lower the gloss and the lighter the ink color, the less noticeable the swirl pattern. Ink gloss on uncoated Tyvek® is difficult to achieve. UV-cure inks and electron-beam cure inks and coatings improve ink gloss. Top coating and film lamination can be used to achieve a high gloss effect.
In-line aqueous coating, performed on the last unit of an offset litho press, does not add gloss to the image. This is due to the light scattering caused by the high surface area of Tyvek®. Inks should be formulated using a target color swatch. Colors specified by Pantone® Matching System (PMS) colors should be formulated and matched on the specific Tyvek® style to be used. Inks made with the strongest color pigments will minimize ink film thickness and provide the best color results.
When color matching, the printer should specify which side of Tyvek® is being printed. If more than one side is printed, each color should be matched on the correct surface. Wet-ink densitometry measurements are needed to get the closest color match when both sides must be matched.
Because of the high surface area of Tyvek®, it will usually require approximately 15% more ink than uncoated paper to achieve the same color density.
COLOR STABILITY
 |
| Printing on DuPont™ Tyvek® has a character and a look all its own—rich, soft, highly distinctive. And because it’s DuPont™ Tyvek®, it wears like nothing else. |
DuPont™ Tyvek® spunbonded olefin should not affect the stability of printing ink pigments. However, certain pigments in offset lithographic inks can shift in color or “burn out” after printing. These pigments include Rubine Red #52, Red Lake 2C and Alkali Blue. These pigments are not recommended for use on Tyvek® without preliminary testing, particularly when these pigments are used to make tints. The "burnout" phenomenon occurs very infrequently and is not predictable. High humidity and heat can add to this effect. A test for these pigments can be made as follows:
- Print approximately 100 sheets with excessive fountain solution on the press and immediately seal them in plastic film.
- Compare these sheets with air-dried control sheets after 24 and then 48 hours.
- If no color shift is observed, the ink/pigment compatibility should be acceptable.
LITHO INK TEST
To determine whether a sheet-fed offset lithographic ink is acceptable for use with Tyvek®, the volatile solvent content should be determined. This can be done as follows:
- Coat a 3 in x 5 in (7.6 cm x 12.7 cm) pre-weighed piece of aluminum foil with a thin film of ink—1 mil (0.025 mm) or less.
- Weigh the coated piece of foil immediately and then place it in an oven for two hours at 220°F (105°C).
- Remove from oven and allow to cool.
- Re-weigh and calculate the percentage weight loss.
Experience has shown that inks with 3% or less volatile solvents should give acceptable performance. Many quick-drying offset lithographic inks contain as much as 27% volatile solvents. These inks can cause gross misregistration and sheet distortion or curl.
INK MANUFACTURERS
For a list of some of the companies that have formulated satisfactory inks for printing on spunbonded olefin, please visit our website. Undoubtedly, there are other suppliers capable of producing satisfactory inks for use with Tyvek®. The list we provide is intended only as a guide and is not a recommendation of any specific company.
Return to the User’s Manual Table of Contents
|
Print Page