Polyart how to get the best results

Transcription

1 Polyart how to get the best results Polyart is the perfect synthetic paper for offset litho or letterpress printing. Polyart has similar handing and print quality to matt coated papers, having a smooth coated finish which gives excellent ink holdout. It is this coating which allows for reduced inking levels which gives rapid drying without affecting print quality. The following recommendations will help printers achieve the best printing results with Polyart. Sheet fed printing Offset printing In most cases where heavy weight Polyart is used, it is possible to use paper type offset inks. However, when printing onto the lower weights up to 140 g/m² we would recommend the use of oxidising inks which are mineral oil free to avoid printing distortion. It is also suggested, when possible, to use under colour removal (UCR). Where anti set off spray is used, we recommend the use of a non vanishing spray powder with a minimum particle size of 20 micron. Damping should be reduced and maintained as low as possible. Excess damping carried into the printed stack will retard ink drying. The use of drying additives based on cobalt acetate can be advantageous. For printing with alcohol damping systems use a 10% IPA solution. Printing with alcohol substitute damping systems will also perform with good results on Polyart. All types of printing plates can be used. Although small offset plates may occasionally become sensitised in the non image areas, the addition of some acid etch to the fount should resolve this. Printed stacks should be up to 1000 sheets. This quantity can vary depending on subject matter and ink film weight. Polyart should be fully dry before further handling and processing. When printed Polyart is required to withstand long term daylight exposure, light fast inks must be used. Please consult with your ink supplier for correct light fast inks. For varnishing with machine and waterbased systems care should be taken to allow varnish to dry to a hard finish. If using aqueous coating on both sides of the sheet, it is recommended that a coating suitable for double sided working is used. Where Polyart has been pre-printed prior to UV varnish being applied, it is very important to remove all anti set off spray powder to prevent speckling in the finished UV varnish. Where non UV inks are to be varnished, the inks should be wax free to prevent bleed. To prevent material distortion form UV source, only minimal power should be used to cure the varnish. Screen process printing Screen printing will give excellent results on Polyart ; for best results use fine mesh screens and light ink films where possible. When using heat drying systems, avoid overheating the printed Polyart sheets. Inks which contain aromatic solvent thinners may give rise to print distortion and should be avoided.

2 Web fed printing Offset printing Polyart can also be printed on web fed presses for use with forms applications. Producing reel to sheet/fan folding will give very good results. Printing reel to reel will require heat assisted ink drying to allow the inks to be fully dry for rewinding. Flexographic, gravure and rotary letterpress They will also give excellent printing results with Polyart. The temperature of the drying units must be controlled to avoid overheating the web, and the use of aromatic solvents should be avoided. There are a number of waterbased flexo inks which give very good drying and ink adhesion on Polyart. Digital and variable information printing Polyart is HP Indigo certified for both sheets and reel printing, please consult the Polyart Digital product range for the certified substrate range. Polyart is compatible with non-impact printing technologies: thermal transfer (wax or resin). Dot matrix, image transfer, cold fusion toner and some flash fusion machines. Polyart is also compatible with UV ink-jet printers. Converting Cutting Polyart When guillotining Polyart, we recommend that the blade is clean and sharp and light clamping pressure is used. Any slight edge sticking will be alleviated by breaking or knocking up the sheets. For die cutting, hardened single bevel cutters will give the best results. Avoid acute internal angles and sharp radii that may give rise to unnecessary weakness. Retention points must be as small and as few as possible. Polyart can be drilled, punched and cornered; All cutting tools should be sharp and clean to avoid irregular cuts. During drilling and cornering, short dwell times should be used to overcome heat generation and to avoid fusion of the edges. When perforating is carried out we have found that with a smaller tie, the perforations will run in a consistent line. If larger ties are used, the line will be inconsistent and wander from the perforations. We recommend whenever possible to allow the perforation to bleed off the edge of the finished form in order to initiate the separation of the perforation. If sprocket punching ensure that the hole punches are sharp. Folding Polyart can be folded like coated paper on normal sheet folding equipment. On light weight Polyart it is not necessary to carry out scoring. Panel folding as carried out in map production gives very good results without any special folding requirements.

3 HELPFUL PRINTING TIPS FOR POLYART DIGITAL Polyart Digital is HP certified for the HP 3000, HP 5000, HP7000 & 7500 series sheet fed machines. Polyart Digital is also HP certified for the HP 5600 one shot press. Polyart Digital is also certified by HP reel fed machines, ws3250, ws4050, ws4500 and the ws6000. Polyart Digital has also been given the 3 star rating from HP. Polyart Digital is two-side coated and is a high quality printing media for the HP Indigo press. To obtain the very best results we recommend the following tips. Ensure the sheets are aired before loading into the feeder. Fan all of the sheets. Wherever possible acclimatise the sheets in the pressroom with optimum relative humidity of 50-55% at 21 o C. Set the press with the HP approved media settings for the desired substrate. Polyart Digital is a polyethylene based material and it is normal to carry out the null-cycle mode to obtain optimum register. Depending on subject matter, it maybe necessary to carry out more than one null cycle to obtain optimum register. For more demanding subject matter, it may be necessary to carry out blanket shift separations for correct CPR control. This will allow the operator to make minor adjustments to the image. It is advised to carry out a print test, prior to undertaking full production, to ensure the substrate is suitable for the end use application. Bob King Technical Support Manager Arjobex Synthetic Papers March

4 ANTI SET OFF SPRAY POWDERS FOR USE WITH POLYART The use of anti set off spray Powder when printing Polyart by sheet fed offset is essential, it is important to use the correct type which is a non vanishing grade. These are normally produced from starch and will not disperse into the wet ink film, vanishing grades of powders must be avoided as they are soluble and will not offer any set off protection. Choice of particle size is also very Important with powders from 20 micron and above can be used. The smaller the particle size will require a higher spray setting on the spray unit. It is also very important to take into account if the printed sheets are going to be over printed with a varnish after printing, care should be taken with the amount of spray powder applied to avoid speckling within the varnish. ANCHOR Fine Medium ABC General Purpose BRANCHER Vanesse HYDRO DYNAMIC PRODUCTS (HDP) Super 15C Super 25C HUBER GROUP R Series S Series KSL K4 K4 Plus S5 S5 WL (specific for use with in-line water based coating units) OXY DRY RUSSELL WEBB Standard R Series 88 Series

5 ADHESIVES INFORMATION Adhesives are used in the graphic arts in a number of ways during the finishing process such as binding and envelope production. There are a number of types and they are divided into two groups, natural adhesives and synthetic adhesives. Natural adhesives are based on animal glues, starch and dextrines. The synthetic adhesives are made up of plastic type materials and are divided into Emulsions, Hot Melts and for Pressure sensitive. Polyart can be used with most adhesives but it is very important to follow the advice of the adhesive manufacturer. Water based adhesives can be used, it would be better to use a high solids type of adhesive which will aid the drying process. Drying temperatures should be maintained below 80 C. Hot melt adhesives will give good bond results during binding, for best results it is better to use low temperature high tack adhesives. The following list is a guide only and trials should be carried out before full production takes place. Results will depend on type of applicators for adhesive and the drying process. BIM UK G-MELT 977. EVA Hot Melt adhesive This product is subject to change. BOSTIK THERMOGRIP. Hot Melt Adhesive AQUAGRIP. Water based Adhesive FORBO SWIFT ADHESIVES Swift EVER-LOCK. Hot Melt Adhesive Swift STACOOL. Low Temperature Hot Melt Adhesive HOWMARINE CALVERT DRYFLEX. Pad production adhesive ECO PAD. Pad production adhesive HENKEL ADHESIVES (Includes Croda who are now in Henkel group) PRIMAMELT Hot Melt Adhesive PRIMAGRIP Hot Melt Adhesive PUREMELT QR Hot Melt Adhesive ADHESIN. Water based Envelope adhesive NATIONAL ADHESIVES ETICOL 291. Water based Adhesive NATIONAL 414. Water based Adhesive BONDMASTER. Pressure Sensitive Adhesive PUR-FECT LOK. Hot Melt Adhesive

6 ULTRA PUR. Hot Melt Adhesive COOL-MELT ULTRA. Low Temperature Hot Melt Adhesive SUPERLOK. Good results obtained with Envelope production PAFRA ADHESIVES PAFRA Hot Melt Adhesive SEALOCK ADHESIVES E 502. Pad Production Adhesive E 923. Water based Adhesive H Hot Melt Adhesive