Technical handbook
Contents
1. Non uniform heat transfer due to uneven contact or pressure Material thickness Therefore high platen temperatures and short clamp closed times can produce significant variability in seal strength Longer clamp closed times and lower platen temperatures will produce more uniform seal strengths DuPont Tyvek Protective Packaging Technical Handbook Seal ability of plain Tyvek to itself or to other films can be achieved with heat or with ultrasonic welding technology How ever the processing window and parameters are very narrow and need to be thoroughly defined The seal visual quality is often a critical factor In order to optimize the sealing process and the visual attributes of the seals DuPont introduced the heat sealable Tyvek 2058L This Tyvek style primarily designed for active packaging that is intended to come into contact with foodstuffs is in compli ance with European Parliament and Council Regulation EC No 1935 2004 Commission Regulation EU No 10 2011 Commission Regulation EC No 2023 2006 GMP for food and Federal Food Drug and Cosmetic Act FDA requirements of Title 21 The seal coating is applied at very low quantity and only on one side therefore users have to keep track of the coated side as they handle the product so that coated side to coated side are sealed together facing the inside of the package This coated grade of Tyvek provides a uniform and non peel able seam which al2. n ai DUPONT TYVEK PROTECTIVE PACKAGING Technical Handbook www packaging tyvek com TABLE OF CONTENTS 1 Introduction 3 5 Tyvek An efficient use of resources 14 1 1 What is Tyvek 3 5 1 Resource minimization 14 1 2 A Choice of hard or soft structure types for a wide range 5 2 Recycle reuse 14 of applications 3 5 3 Energy recovery 14 1 3 Availability 3 5 4 Landfill 14 1 4 Product features 3 5 5 Where to recycle Tyvek 14 EEE E 2 1 General 6 Manufacturers of adhesives 15 2 2 Slitting sheeting cutting 6 Solvents 15 2 3 Rotary die punching 6 2 4 Die cutting 6 2 5 Punching 6 2 6 Folding 6 2 7 Perforating 7 2 8 Embossing 7 2 9 Hot Foil stamping 7 2 10 Dyeing 7 2 11 Laminating 4 2 12 Gluing 7 2 13 Sewing 8 8 2 14 Sealing and coating 3 Tyvek for Thermal Sealing 9 4 Printing 10 4 1 General 10 4 2 Precautions 10 4 3 Printing on Tyvek for food contact 10 4 4 Inks 11 4 5 Special notes for adhesive coated Tyvek 11 4 6 Different Printing technologies 11 4 7 Other 11 DuPont Tyvek Protective Packaging Technical Handbook 1 3 AVAILABILITY Tyvek is available in a wide range of rolls and formats Roll width max 3m Please contact us for further details Telephone number 352 3666 5589 Homepage www packaging Tyvek com Roll good supply http www2 dupont com Tyvek_packag ing en_GB contact contact us html Link to contact form on the website
3. 16 96 00 DuPont is committed to the efficient and safe handling of plastics waste and advocates a resource optimization and waste management system with the following priorities 1 Resource minimization 2 Recycle reuse 3 Recover energy 4 Landfill DuPont is certified ISO 14001 2004 5 1 RESOURCE MINIMIZATION Tyvek is very strong and light weight so less material is needed to perform many functions The weight of material in a product made from Tyvek can be much lower than the one made from other materials for the same or superior performance 5 2 RECYCLE REUSE Mechanical recycling Being 100 HDPE Tyvek or products made from Tyvek can be mechanically recycled into products such as underground cable protection piping automotive parts blown film packag ing cores and flowerpots Products made from Tyvek which are printed glued welded or sewn can also be recycled as can Tyvek which has been extrusion coated or laminated with a polymer of the same family Polyethylene can normally be recycled 4 to 5 times before physical properties are substantially affected Chemical feedstock recycling Tyvek can be chemically recycled with other polymers In this process the original material is separated into its chemical com ponents which are then recovered for reuse DuPont Tyvek Protective Packaging Technical Handbook APPENDIX MANUFACTURERS OF ADHESIVES RECOMMENDED FOR TYVEK Pla
4. 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 De aerate and keep lift height below 7 2cm 3 inches when die cutting to avoid oversizing top blanks 2 5 PUNCHING Tyvek can be punched on tag letterpress and rotary line hole equipment Best results are obtained from sharp well registered and close fitting 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 2 6 FOLDING Tyvek 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 Tyvek soft rubber covered rollers will aid feeding 2 1 GENERAL Although Tyvek brand spun bonded olefin is processed in much the same way as paper or plastic films and on the same equipment it does require different handling techniques for optimum results For this reason we strongly recommend that those who have never before worked with spun bonded olefin conduct a pilot run to fully test each conversion operation before beginning full scale production Here are a few tips to keep in mind Spun bonded olefin cannot be crush cut as easily as paper Its filaments are very strong and each must be completel
5. dupont com DuPont Tyvek Protective Packaging Technical Handbook 4 PRINTING Offset printing Design prepress and printing tips ICC profile can be down loaded from our website www graphics dupont com Tyvek is dimensionally stable and handles well on large or small single and multicolor offset machines and on vertical flatbed or rotary letterpress machines in sheet or web form Use recommended inks Most ink suppliers have offset inks for Tyvek or for synthetic substrate It is important to use low solvent content inks The inks should contain less than 3 volatile solvent since hydrocarbon solvents found in most offset inks will swell and distort Tyvek Add more impression Usually Tyvek will require about 0 08 0 10 mm additional impression compared to a sheet of paper of equivalent thick ness because it is more compressible Reduce level of dampening solution Tyvek does not absorb water as readily as paper for this reason the press should be run with less dampening solution If the printing is dull or washed out the amount of dampening solu tion should be reduced and and its pH 7 is ideal should be verified Do not increase ink volume Print with the minimum ink film thickness This will minimize dot distortion sheet distortion and the appearance of fibre swirl and will also reduce ink drying time Offset inks dry more slowly on Tyvek than on paper When doing full coverage mu
6. properties of spun bonded olefin products are not affected by water Tyvek is equally strong wet or dry under ordinary conditions and ambient temperature Food contact Tyvek styles suitable for direct food contact according to COMMISSION REGULATION EU No 10 2011 on plastic materials and articles intended to come into contact with food and or the requirements of title 21 of the US Code of Federal Regulations 21 CFR 177 1520 FDA are available Details for the certification as well as a copy of the certificate are available upon request Moisture vapor transmission Tyvek resists to water penetration while allowing moisture vapor to pass through thanks to its filament structure Chemical resistance Tyvek is unaffected by most acids bases and salts Prolonged exposure to oxidizing agents such as concentrated nitric acid or sodium persulphate may cause some loss of strength Neutral pH Spun bonded olefin has a neutral pH 7 Therefore it is neither acidic nor basic The styles that are corona treated and antistatic treated also have a pH 7 DuPont Tyvek Protective Packaging Technical Handbook DuPont Tyvek Protective Packaging Technical Handbook 1 INTRODUCTION Corona treatment Most Tyvek styles that will be printed on are corona discharge treated to improve ink and coating adhesion Through corona treatment the surface is oxidized from both sides and the inks as well a
7. 1 4 PRODUCT FEATURES Strength Tyvek is tear resistant whether wet or dry Due to its unique structure it remains strong even when folded High opacity The high opacity of Tyvek is a result of multiple light refraction between the fine filaments and air within the sheet Dimensional stability Between 0 and 100 relative humidity Tyvek remains dimen sionally stable Under these circumstances dimensions change less than 0 01 High flex strength Tyvek can be creased and bent almost indefinitely without los ing its strength Low linting Tyvek is made of continuous fibers and under normal condi tions produces no free lint particles It is therefore suitable for direct contact with sensitive parts DuPont Tyvek Protective Packaging Technical Handbook 1 INTRODUCTION 1 1 WHAT IS TYVEK Tyvek is a registered trademark of DuPont for its family of tough durable sheet products made of high density polyethyl ene HDPE The sheet is formed first by spinning continuous strands of very fine interconnected filaments and then bond ing them together with heat and pressure The result is a bright white spun bonded sheet Tyvek offers all the best characteristics of paper film and fabric in one material This unique balance of properties which can not be found in any other material makes Tyvek lightweight yet strong vapor permeable yet water and chemical resistant as well as puncture
8. 4 3 PRINTING ON TYVEK FOR FOOD PHARMA Styles of Tyvek for food and pharmaceutical packaging can be printed in much the same way as paper using standard commer cial printing equipment However because of the unique require ments of the food and pharmaceutical packaging industries these styles have no antistatic coating and are not corona treated They are often treated with a heat seal adhesive coating Because these factors may adversely affect automatic sheet feeding and ink adhesion special steps must be taken to obtain optimum printing results When printing on Tyvek food and pharmaceu tical packaging styles we recommend testing before proceeding with production operations It is also important to establish the suitability of the ink in those applications where direct contact with food or pharmaceutical products may occur 4 PRINTING Tyvek can be successfully printed by using traditional as well as some digital processes in both sheet and roll form 4 1 GENERAL Tyvek can be printed the same way as paper although some of its physical properties do require special attention Tyvek grades with corona treatement on both sides to improve ink adhesion and is coated with an antistatic agent to facilitate sheet printing and converting are available in the products range Tyvek has no grain direction Tyvek has a smooth and rough side The difference can be felt or viewed using a low power magnifyin
9. 5 4 5 g cm are used for screen volume of 4 5 6 0 g cm are used for full tone For UV curing inks same Anilox rolls can be used but for enough coverage on full tone the transferred volume should be higher than 8 g cm Photo courtesy center 4 PRINTING 4 6 DIFFERENT PRINTING TECHNOLOGIES Flexo printing Low temperature drying is the key to printing Tyvek by flexography Web temperature should be kept below 80 C and tension below 1 4 N cm of width This will help prevent mis registration The use of powered rollers and short unsupported web spans will help to maintain low unwind and processing temperatures Use recommended inks Most ink suppliers have flexo inks for Tyvek in their product selection Some hydrocarbon solvents used in certain flexo inks may cause swelling or cockling Ink suitability should be tested before production Many different flexo inks are suitable for Tyvek like volatile solvent water based and UV curing inks in each case the volume of ink on Anilox roll needs to be adapted to the type of Tyvek and to the print layout Pigmented polyamide alcohol inks increase adhesion and rub resistance Water based inks for PE print well but drying time may be extended due to the low water absorption of Tyvek When printing on Tyvek without corona or and antistatic treatment like the styles which can come in direct contact with food stuff microcrystalline wax is usually add
10. ata are provided as a guide for selecting solvents for inks or coatings 2 Union Carbide Chemicals amp Plastics 3 Union Oil Co of California 4 Magie Bros Oil Co TopCover DuPont Tyvek Product safety information is available upon request This information is based upon technical data that DuPont believes to be reliable It is subject to revision as additional knowledge and experience are gained DuPont makes no guarantee of results and assumes no obligation or liability in connection with this information It is intended for use by persons having technical skill for evaluation under their specific end use conditions at their own discretion and risk Since conditions of use are outside our control WE MAKE NO WARRANTIES EXPRESSED OR IMPLIED INCLUDING WITHOUT LIMITATIONS NO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE AND ASSUME NO LIABILITY IN CONNECTION WITH ANY USE OF THIS INFORMATION This information is not intended as a license to operate under or a recommendation to infringe any patent or technical information of DuPont or others covering any material or its use For further information technical assistance or samples please contact DuPont or your local distributor DuPont de Nemours Luxembourg S r l DuPont Protective Packaging rue General Patton L 2984 Luxembourg Tel 352 3666 5589 Fax 352 3666 5021 www packaging tyvek com The miracles of science Copyright 2014 DuPont All
11. cover applications A foil that will transfer cleanly to Tyvek between 135 160 C should be chosen Large solid foil stamped areas tend to pucker and distort Tyvek and should be avoided To avoid pucker and distortion Tyvek 105g m or self adhesive coated Tyvek is recommended 2 10 DYEING Conventional textile dyeing processes do not impart permanent color to Tyvek However Tyvek can be printed on by flexo graphic or gravure processes 2 HOW CONVERT TYVEK 2 13 SEWING Tyvek can be sewn on conventional sewing machines Best re sults 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 Tyvek When stitching Tyvek lowest possible stitch frequency 2 3 stitches cm with low tension and the smallest needle should be used The needle should have a flat point to produce perforating slits It can be recommended to use chain and aligned stitches 3 especially 2 5 cm chain stitch 2 14 SEALING AND COATING Coatings are used to color improve print fidelity add gloss or mask the fiber pattern in Tyvek Air knife coating is preferred for aqueous coating because it applies a uniform thickness Usu ally an increase in binder content is needed to achieve accept able coating adhesion to Tyvek The air knife also produces a very smooth surface which is ideal for pr
12. e EO gamma electron beam steam under con trolled conditions or newer methods such as low temperature oxidative sterilization processes Tyvek will retain its protective properties color and flexibility Temperature range Tyvek retains its toughness and flexibility until 75 C Tyvek begins to shrink at 118 C and melts at 135 C When processing Tyvek web under tension the temperature should not exceed 80 C Flammability A strip of clean untreated Tyvek When first exposed to an open flame shrinks away from it If the flame follows the strip it will catch fire burn slowly and drip molten polymer Aging UV resistance Physical properties of spun bonded olefin are degraded with extended exposure to direct sunlight ultraviolet rays although at least one to three months of useful outdoor life can be expected in many applications UV resistance can be improved with opaque coatings Styles of spun bonded Olefin containing UV inhibitors are available for applications requiring higher UV resistance 1 INTRODUCTION Lightweight Other materials need more than double basis weight to achieve similar strength as Tyvek The density of Tyvek is 0 38 g cm Water resistance DuPont Tyvek is highly resistant to penetration by water In fact water in contact with Tyvek does not wet its surface which means that water does not spread but remains as droplets on the surface The physical
13. ed to inks to reduce set off Reduce the web temperatures prior to wind up on a chill roller This helps to prevent blocking and minimizes distortion and is essential for printing on Tyvek styles without corona and antistatic treatment To help overcome the inherent thickness variation of Tyvek mount plates with 0 38 0 55 mm of sticky back closed cell foam tape DuPont Tyvek Protective Packaging Technical Handbook Either side of Tyvek can be printed Generally the smooth side is recommended Conventional blankets of medium hardness are recommended It is recommended that 4 colors work is conducted only on 4 colors machines because Tyvek is subject to stretching Gravure Tyvek is suitable for printing on equipment used for single multi color printing of paper films and fabrics The same techniques involved in flexo printing should also be applied to gravure with the following additions Cylinders with 39 lines cm or more are preferred Type C nitrocellulose gravure inks are most widely used and they are often modified by the addition of an alkyd resin to improve ink hardness and adhesion Other printing technologies Screen printing thermal transfer printing and some digital printing are also technologies which can be used to print on Tyvek For additional information about printing on Tyvek refer to the DuPont Tyvek Users Manual or the technical handbook on www graphics
14. g glass or exposing to reflective light Although Tyvek is printable on both sides it is recommended to use the smooth side for one sided or full coverage printing Tyvek has a unique filament swirl pattern which is used to great effect in certain applications This will show through most inks It may be minimized by using light colors or a busy pattern 4 2 PRECAUTIONS Tyvek is not as absorbent as paper and therefore inks may take longer to dry The open nature of the Tyvek surface however allows faster drying than other plastic film substrates In the timeline three days should be allowed for two sides printing due to the need of min 24 hours dry time before printing the second side Tyvek has an inherent thickness variation which can be com pensated by adding more pressure DuPont Tyvek Protective Packaging Technical Handbook 4 5 SPECIAL NOTES FOR ADHESIVE COATED TYVEK When selecting offset inks it is important to advise the ink sup plier if the Tyvek style has an adhesive coating because special ink formulations may be required to prevent ink set off to the coated surface In some cases printing is done on the adhesive side This also should be discussed with the ink supplier to ensure optimum compatibility between the ink and the coating 4 PRINTING 4 4 INKS In general we recommend using inks developed for printing on synthetic material It is possible to use standard pa
15. inting Gravure coating is preferred for solvent based systems particularly where deep coloration is required Tyvek can be extrusion coated using special polymers When coating or laminating Tyvek the web temperature should not exceed 80 C High seal strength can be achieved using hot bar or impulse techniques sealing Tyvek to Tyvek Heat sealing Tyvek to itself or other films is usually accomplished by applying a heat seal coating such as branched low density polyethylene LDPE to one of the materials please consult chapter 3 Tyvek cannot be dielectrically sealed under ordinary conditions because it is non polar Ultrasonic sealing can be used to create fiber tearing seals with most of Tyvek styles and without the puckering that is often associated with heat seals g DuPont Tyvek Protective Packaging Technical Handbook 3 TYVEK FOR THERMAL SEALING Sealing dwell time refers to the clamp closed time during which the interface between the two webs is raised to a temperature that is high enough to either melt or activate the sealant Some manufacturers operate at very high platen temperatures to achieve shorter clamp closed times which leave only very little time for the seal to form With that short of a sealing time anything that can affect the rate of temperature increase at the sealing surface can have a significant effect Common factors include Variation in platen temperature
16. lows obtaining good results in drop test ing This test is required for powder bags such as desiccants or oxygen scavengers which usually are produced on vertical form fill seal machines It would be wise to validate production parameters before going into full production Setting sealing parameters The seal strength developed during a heat sealing process de pends upon several factors including Sealing dwell time e Sealing temperature Sealing pressure Characteristics of the sealant Test method used to determine the seal strength seal integrity and visual criteria Tyvek is more elastic than paper and should be handled under the lowest tension possible to avoid distortion and mis regis tration Heavy edge to edge ink coverage and subsequent die cutting to smaller sizes may cause curling This effect can be avoided by leaving a 1 2 cm border on all sides Solvents certain solvents used in some inks paints and adhe sives may cause swelling of Tyvek This effect is often reversible after evaporation of the solvent If a binder or vehicle is present in the solvent the distortion may be permanent Tyvek may also be swollen or cockled by some plasticizers and aliphatic hydrocarbon resins used in inks and low molecular weight adhesives This effect is generally permanent and may not be apparent for some time after application Please refer to page 15 list of solvents and their effects on Tyvek
17. lti color printing keep the pile height below 50 cm Winding the sheets will accelerate drying Tyvek is unaffected by alcohol and alcohol substitute dampening solution additives 5 AN EFFICIENT USE OF RESOURCES 5 3 ENERGY RECOVERY When incinerated in excess oxygen Tyvek yields only water and CO It is excellent in fuel yielding two or more times the energy of coal and is equal to oil in generating heat Incinera tion of HDPE does not contribute to acid rain 5 4 LANDFILL Whilst DuPont does not encourage landfill Tyvek can as a last resort be safely disposed of in this way It will not leach into groundwater because it is chemical inert and doesn t contain binders fillers and plasticizers 5 5 WHERE TO RECYCLE TYVEK At the end of their useful life products made from Tyvek can be recycled via your local recycler for polyethylene waste Additionally DuPont has set up a network of recyclers who have agreed to take back items made from Tyvek for mechanical recycling into other products The items sent for recycling must not have been in contact with any hazardous substance Ravago Plastics Luxembourg S A Rue des Ateliers Zoning industriel de Latour B 6761 Virton Tel 32 63 581 736 Fax 32 63 581 738 B Plast 2000 D 26605 Aurich Tel 49 4941 60020 Paprec Plastiques 44 5 7 rue Piliers de la Chauviniere BP 60195 F 44802 Saint Herblain cedex Tel 33 0 2 40
18. natol Klebetechnik GmbH http www planatol adhesive com Solvents to be avoided n Butyl acetate Sun spirits Pine oil 99 3 Lactol spirits SDW turpentine Dichloromethane Tetrahydrofuran Mineral spirits T Pentane Petroleum ether Pinene Rubber solvent VM P naphtha Toluene Naphthol spirits Xylene Kerosene Magie Oil DuPont Tyvek Protective Packaging Technical Handbook Henkel http www henkel com H B Fuller http www hbfuller com eimea about us SOLVENTS Order of increasing swelling effect of solvents on Tyvek Solvents to be used sparingly Raw linseed oil Dibutyl phthlate iso Butyl alcohol Methyl Cellosolve acetate Propylene glycol methylether Acetone Butyl Cellosolve Cellosolve acetate n Butyl alcohol n Propyl alcohol n Hexyl alcohol n Pentyl alcohol iso Propyl acetate Butyl Cellosolve acetate 2 Octyl alcohol Butyl Carbitol acetate n Decyl alcohol Ethyl acetate iso Butyl acetate Methyl ethyl ketone n Propyl acetate Methyl iso butyl ketone Cyclohexanone Diethyl ketone Preferred solvents Glycerol Diethylene glycol Propylene glycol Triethylene glycol Ethylene glycol Methyl alcohol Ethyl alcohol Diacetone alcohol Carbitol Carbitol acetate Dipropylene glycol Methyl Cellosolve Dipropylene glycol methylether Methyl iso butyl carbinol Cellosolve iso Propyl alcohol 1 These d
19. p in choosing an adhesive is to determine how it will react Natural product adhesives based on dextrin casein or animal by products can be used to adhere Tyvek to itself and a variety of paper materials Water based synthetic lattices such as the ethylene vinyl acetate adhesives form fiber tearing bonds with Tyvek Hot melt polyamide adhesives are available which form good bonds to Tyvek with a variety of materials Acrylic pres sure sensitive adhesives are commonly used with a release liner Please refer to the solvents list before using your adhesive Some of the components may interact with Tyvek DuPont Tyvek Protective Packaging Technical Handbook 2 7 PERFORATING To make clean tearing perforations a 10 1 cut to reserve ratio is recommended e g 8 0 mm cut 0 8 mm reserve 5 16 in 1 32 in Tear initiation can be assured by positioning a cut at the edge of the sheet 2 8 EMBOSSING Tyvek can be embossed with either high or low pressure equipment Cold embossing does not significantly reduce the strength of Tyvek It does however reduce opacity Emboss ing cylinders used for Tyvek 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 backup cylinder is preferred 2 9 HOT FOIL STAMPING This is readily accomplished on Tyvek due to its thermoplastic nature A variety of foils is available from suppliers for label and book
20. per inks on Tyvek with satisfac tory results but this will depend generally on the ink formula tion and the amount of ink coverage Always do a test and wait one day We do recommend however that inks developed for use on PE synthetic are chosen Please ask your ink manufacturer for the right ink for Tyvek Some hydrocarbon solvents used in certain commercial inks may cause swelling or cockling It is suggested that inks con taining less than 3 residual solvents are used on Tyvek If Tyvek swells or cockles within 30 minutes of printing the ink probably contains a residual solvent or plasticizer Aniline dye inks are not recommended for use on Tyvek DuPont Tyvek Protective Packaging Technical Handbook Cyrel Photopolymer plates produce the best overall print quality Thin plates with thickness of 45 1 14mm can be used without any problem The hardness of these plates should be 75 C Shore A Harder plates at thickness of 67 1 7mm or 100 2 54mm can be used when mounted with sticky back closed cell foam tape to compensate the thickness variation with the foam and not with the plate There is no difference for digital or analog plates Multi color process printing is best accomplished with Cyrel Photopolymer plates with 48 lines cm screen same require ments are valid for screen and full tone areas Guidelines For water and solvent based inks Anilox rolls with 260 340 L cm and a volume of 3
21. rights reserved The DuPont Oval Logo DuPont The miracles of science Tyvek and Cyrel are trademarks or registered trademarks of E I du Pont de Nemours and Company or its affiliates 05 2014
22. s glues or coatings adhere better The fiber structure of Tyvek allows inks to penetrate and therefore increases the abrasion resistance of the print Corona treatment on Tyvek lasts for several years Static To reduce the build up of static electricity during sheet and roll handling operations some styles are also coated with an antistatic agent Spun bonded olefin destined for use in the packaging of food stuff or pharmaceutical products are neither corona nor anti static treated Toxicity Tyvek is classified as non toxic Testing on skin resulted in no irritation swelling or allergic reaction Rot and mildew resistant Tyvek does not degrade after being buried in soil for an ex tended period Clean Tyvek will not promote the formation of mildew or other micro organisms 2 HOW TO CONVERT TYVEK 2 2 SLITTING SHEETING CUTTING 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 2 3 ROTARY DIE PUNCHING Because soft steel male female rotary dies dull quickly when set to the close tolerances required to punch Tyvek cleanly the use of rotary dies made of hardened tool steel or tungsten carbide is recommended 2 4 DIE CUTTING Tyvek can be die cut using either steel rule male female or closed dies Tyvek fibers must be completely cut
23. tear and abrasion resistant Tyvek is also low linting smooth and opaque 1 2 A CHOICE OF HARD OR SOFT STRUCTURE TYPES FORA WIDE RANGE OF APPLICATIONS e Type 10 a hard area bonded product is a smooth stiff non directional substrate with good printability in both sheet and roll form It has high opacity excellent whiteness and good surface stability Types 14 15 and 16 are soft point bonded products with an embossed pattern providing a fabric like flexible substrate with good printability and tear resistance Tyvek is used where barrier durability and breathability are required It offers excellent splash and dry protection against particulates and provides an excellent bacterial barrier The outstanding low linting combined with barrier properties make Tyvek an excellent material in several application fields Resistance to microbial penetration Microbial barrier test data consistently prove that Tyvek holds out bacterial spores and test particles better than other porous packaging materials even under the most rigorous conditions In addition a long term shelf life study proved conclusively that Tyvek can maintain sterility for at least five years if pack age integrity is not compromised Compatibility with a broad range of sterilization methods Only Tyvek is compatible with all of the most commonly used sterilization methods No matter which process you use ethylene oxid
24. y severed hangers will not break off Spun bonded olefin elongates more than paper and will stretch up to 30 before breaking To minimize distortion or neck down keep web tension as low as practical 1 4 N cm during processing Spun bonded olefin is a thermoplastic material and it melts sharply at 135 C When coating or laminating spun bonded olefin the web temperature in the oven should not exceed 80 C DuPont Tyvek Protective Packaging Technical Handbook Sun Spice by 2 HOW TO CONVERT TYVEK 2 11 LAMINATING Tyvek can be extrusion adhesive flame ultrasonic ther mal and calender laminated Extruded low density polyethyl ene LDPE is an excellent adhesive for laminating foil and film to Tyvek Polyurethane adhesives can be used to adhere a vari ety of films and fabrics to Tyvek When laminating Tyvek to paper or board it is important to completely cover Tyvek with adhesive to prevent bubble formation Polyurethane adhesives or hotmelt Euromelt 772 from Henkel or Lunamelt KC2010 from H B Fuller are recommended Recycled board is not recommended since the board can contain remaining solvents or binders which can cause bubble formation 2 12 GLUING A number of adhesives can be used to glue spun bonded olefin either to itself or to other substrates In general water based adhesives that provide quick tack and fast drying are preferred However the first ste
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