Narrow-web

High-pressure mercury lamps operate at pressures about 10 atmospheres and essentially two types are used in industrial applications. The point source lamp focuses on a small-diameter spot, thus delivering an intense radiation to that spot. The capillary lamp is used for narrow webs up to approximately 20 cm (8 in.) wide.4 They are capable of producing a wider spectrum than the medium-pressure lamps and operate with higher power (150-2880 W/cm). Their disadvantage is a relatively short operating life, typically hundreds of hours. 

Over the years letterpress printing has declined into niche markets, two of which are the printing of plastic self-adhesive labels on narrow-web rotary-offset letterpress machines that are fitted with UV drying and the common-impression rotary-offset letterpress and UV-curing on mandrel of plastic containers such as yoghurt tubs and toothpaste tubes. In uses such as these the most common self-adhesive plastic is PVC and the most usual for tubs and tubes are polystyrene, PVC, ABS, and polypropylene. 

In the context of printing plastics, the Nyloprint photo-polymer plate appears to be the most popular in the areas of narrow-web rotary-letterpress label printing and rotary-offset letterpress printing of plastic tubs and tubes. 

Dirk Aulbert, Pres., Packaging Narrow Web William B. Miller, Pres., Print Media America Craig Foster, Pres., Flint Group Pigments Charles Knott, Chmn. 

Stobbe, B. D., Corona Treatment 101-Understanding the Basics from a Narrow Web Perspective, Label Narrow Web Industry Magazine (Jun. 1996)... 

Spent air should be removed from the web and air-bar interface area quickly, evenly, and at substantially reduced velocity as compared with the air impingement velocity. Spent air velocities usually should not exceed 10% of the air-bar outlet velocities. On narrow webs, spent air is exhausted at the web edges. When dealing with wide web, spent air is removed at the web center to avoid over drying the web edges. 

Chem. Descrip. Aromatic waterborne PU Uses Urethane for coatings for syn. fabric and narrow web Features Super soft coating contains heat reactive crosslinker solv.-free... 

Chem. Descrip. Aliphatic waterborne PU coaling Uses Coaling and impregnant for syn. fabrics, narrow web, cordage, military web... 

Chem. Descrip. Aliphatic waterborne PU coating Uses Coating and impregnant for syn. fabrics binder for narrow web where extra firmness is required Features Very firm contains heat reactive crosslinker Properties Dens. 8.7 Ib/gal vise. < 1000 cps (72 F) pH 7-8.5 100% tens. mod. 3300 psi tens. str. 6000 psi elong. 250% 33 2% solids Solucote 1017 [Soluol]... 

Chem. Descrip. Aliphatic waterborne PU coating Uses Coating for nylon and polyester syn. threads and narrow web, improving slip, antiwicking and ply adhesion Features Contains heat reactive crosslinker... 

These machines are commercially available in sizes from pilot coaters using narrow webs, 6-24 in. wide, and nmning at low speeds, 10-50 ft/min, to production machines using wide webs, over 5 ft wide and coating at 500-5000 ft/min. A t5q>ical pilot coater is shown in Figure 2. 

After preheating, the film is drawn in the transverse or cross direction by the divergence of the tenter chains, annealed, and released. The edges of the film are slit off, ground, and recycled, and the web may be wound full width or split into narrower webs, which are electric discharge or flame treated for enhancing printability and then wound onto rolls for further processing. 

Figure 20.13 (A) Narrow-web pilot-scale DCSBD plasma treater. (B) A customized DCSBD plasma treater consisting of numerous (up to 25) diffuse coplanar surface barrier discharge units. See also [64]. (Reproduced with permission from Masaryk University, Brno).

Narrow-web/self-adhesives Shrink sleeves Stretch sleeves Folding cartons Metal packaging. 

Stobbe BD. Corona treatment 101-imder-standing the basics from a narrow web perspective. Label Narrow Web Industry Magazine, June 1996. 

Slitting (web) Cutting the web in the machine direction to create a narrow web. 

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