Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F13/00—Common details of rotary presses or machines
  • B41F13/08—Cylinders
  • B41F13/10—Forme cylinders
  • B41F13/11—Gravure cylinders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/16—Curved printing plates, especially cylinders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/16—Curved printing plates, especially cylinders
  • B41N1/20—Curved printing plates, especially cylinders made of metal or similar inorganic compounds, e.g. plasma coated ceramics, carbides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N6/00—Mounting boards; Sleeves Make-ready devices, e.g. underlays, overlays; Attaching by chemical means, e.g. vulcanising

Definitions

• This invention relates to improvements in gravure printing rollers.
• gravure printing rollers are usually machined to the required size from stainless steel.
• Stainless steel rollers are however extremely heavy which is a major disadvantage, both from the point of view of transportation, and also in changing rollers in a printing machine.
• rollers of a lower weight material such as a composite including a relatively low density synthetic material which retains a durable printing face such as chrome treated copper, yet is light to ease shipping and handling.
• WO 99/32302 proposes a printing roller comprising a body of low density hard foam, and a surface layer comprising a non-foamed polyurethane including 15 - 70% filler such as chalk.
• ROSSINI, EP-A-384,104 describes a roll comprising a stiff inner core, having a shell of rigid expanded polyurethane, which is smoothed and electroplated with a layer of copper.
• BARDIN, EP-A-0038385 forms a roll by moulding a body of plastics material, machines the roll to size and plates the machined surface with copper.
• EP-A-0364,653 describes a roller which comprises a substrate which includes hollow microspheres. The printing surface is produced by grinding and rupturing the microspheres to provide a roughened surface to aid ink retention.
• KINYOSHI EP-A-0,344,332 describes a roller with mineral particles embedded in a surface layer. The surface provides a surface which pits and projects at the particle scale, which again is said to aid ink retention.
• the invention provides a gravure roller comprising a lightweight shell made from a syntatic moulding composition comprising a polyurethane matrix containing hollow microspheres, characterised in that the shell (15) has a non-porous machine surface with a printing face of chrome treated copper deposited on the surface.
• a syntactic moulding composition is defined for the purpose of this specification as being a synthetic matrix including preformed beads providing discrete bubbles. This composition is capable of providing a uniform cellular construction of homogenous and consistent density which can be machined without leaving a porous or void containing surface.
• the syntactic moulding composition preferably comprises a polyurethane composition formed into preformed plastics beads each comprising an individual shell surrounding an interior void and bonded by a polyurethane composition.
• the beads may be in the size range of 20 to 100 ⁇ m (microns) (weight average diameter) and may alternatively comprise other polymers, glass, or ceramic beads.
• the invention also provides a method of manufacturing gravure roller, comprising moulding a roller shell from a syntatic moulding composition comprising a polyurethane matrix containing hollow microspheres, machining the peripheral surface of said roller shell to produce a non-porous machined surface and depositing a layer of chrome treated copper on the surface to provide a printing face.
• the shell may advantageously be mechanically reinforced, to prevent flexure of the roller, by means of a rigid tubular core upon which the shell is moulded.
• the core may be for example of glass reinforced plastics, or a concrete composition.
• the polyurethane used in the moulding composition can be manufactured from a range of ingredients.
• polyether or polyester polyols may be used, with any of the common isocyanates; including methylene diphenyl diisocyanate; toluene diisocyanate; naphthalene diisocyanate; tetramethyl xylidene diisocyanate; isophorone diisocyanate; phenylene diisocyanate; cyclohexyl diisocyanate; xylidene diisocyanate; hexamethylene diisocyanate; as well as biuret, allophanate and prepolymeric adducts of these.
• Diol, triol, polyol or polyamine crosslinkers may be used, with an amine or metal catalyst which is preferably of a type which negates blowing reaction in the moulding step following bead expansion.
• the isocyanate component may be pre-polymerised and contain the expansion agent so that the isocyanate component is a low density liquid whilst the polyol is a standard polyol.
• a suitable composition may be as follow:- Polyol component:- (by weight ) Castor Oil - 46.8 Polyether hexol - 46.8 Antifoam - 0.19 Dessicant - 2.4 Catalysts - 0.25 Expancel 551DE - 3.59
• Isocyanate - Polymeric methylene diphenyl diisocyanate (MDI) - 100% Mix ratio: 60 parts polyol to 50 parts of isocyanate Gel time at 25°C - 10 to 15 minutes Hardness - 70 shore D Density - 0.72 Viscosity polyol - 400 poise at 25°C
• the moulding is carried out at 60°C in a low pressure two component polyurethane dispenser-2KM machine.
• the surface of the syntactic moulding polyurethane composition is, after machining, preferably treated with a conductive coating to provide a host surface for the copper plating.
• the conductive coating is preferably an organic solvent based composition containing one or more conductive agents.
• the latter may comprise additions of conductive materials such as finely divided metals, or additives which adjust the ionic state of the coating to render it conductive.
• rollers may be manufactured entirely from the syntactic moulding composition ,whilst in other possible embodiments, the roller shells are fitted with steel or aluminum end plates and/or shafts or trunnions.
• rollers according to the invention may be used not only for gravure printing, but also for flexo printing.
• a gravure roller 1 which comprises a roller body or shell 15.
• the roller shell body 15 is made by moulding a syntactic polyurethane foam, which is then machined to achieve the desired diameter and produce a substantially non-porous and void-free outer surface 16, on which a layer of copper 17 is deposited after treatment with a conductive coating which provides adhesion for the copper, and then treated with chrome and processed as required to act as a gravure printing roller.
• the roller also includes a tubular core 12, which acts as a support and reinforcing member to prevent or minimise flexure of the roller, with end caps 13, 14 formed with trunnions 11so that the roller 1 can be mounted in a machine.
• the core is of a suitably strong material, such as glass reinforced plastics, or a concrete composition, particularly a resin bonded concrete.
• the conductive composition is an organic based coating including a conductive agent such as powdered metal or ionic adjusting additives.
• Figure 4 shows, much magnified, the surface 16 of the roller shell 15, wherein the bonded beads or bubbles 18 of polyurethane or other plastics foam are shown in a polyurethane matrix 19 and providing a substantially non-porous surface 16 free of major voids and with only micros-pits caused by the opening or removal of individual beads 18.
• the beads may alternatively be of glass or ceramic material.
• Figure 3 shows a machined surface 116 of a layer 115 of a normal open-celled foam which has, for example, been poured into the mould as liquid and allowed to cure and foam simultaneously in the mould.
• the foam after planarising , has major voids 117 and pores 118 which, by linking of adjacent foam cell, often penetrate well in to the foam body so that the surface 116 is by no means non-porous or free voids.
• the roller shell 15 is made by moulding a syntactic polyurethane foam. This is then machined to the required size, a coat of a special paint applied over the surface, copper deposited and the shell is then assembled into the roller structure for subsequent chromium plating, etching and use in printing.
• the roller may weigh about 5 to 7 kg instead of the weight of 100 kg when steel is used for the roller shell.
• the roller can be refurbished by recoating with copper and rechromium plating and etching.
• the relatively light weight ensures that transportation and handling, including mounting and dismounting the roller is easy and imposes no handling problems.
• a roller formerly requiring use of a 7.5 tonne truck for delivery of a set of rollers can now be delivered using a light weight van.
• the other parts of the roller including the end plates, shaft and trunnions, can be made of reduced weight materials, e. g. lightweight metals such as aluminium alloys, or synthetic materials such as suitable rigid plastic materials including forming all or part of the roller from the syntactic foam material.
• reduced weight materials e. g. lightweight metals such as aluminium alloys, or synthetic materials such as suitable rigid plastic materials including forming all or part of the roller from the syntactic foam material.
• a preferred syntactic foam composition used in manufacture of the shell is preferably as set out above.
• moulding may be carried out with a polyisocyanate composition, using a prepolymer with a polyester or polyether polyol, a friability modifier and an isocyanate catalyst such as DABCO TMR5.
• a polyisocyanate composition using a prepolymer with a polyester or polyether polyol, a friability modifier and an isocyanate catalyst such as DABCO TMR5.
• urethane derivatives can be polyoxazolidone produced by means of epoxy/isocyanate addition compositions.
• the syntactic material can be based on other polymers such as unsaturated polyesters, vinyl esters or polyacrylic systems such as Modar (Trade Mark of ICI) can be used.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Printing Plates And Materials Therefor (AREA)
• Electroplating Methods And Accessories (AREA)
• Inking, Control Or Cleaning Of Printing Machines (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
• Holo Graphy (AREA)
• Polyurethanes Or Polyureas (AREA)
• Confectionery (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Impression-Transfer Materials And Handling Thereof (AREA)

Applications Claiming Priority (5)

Publications (2)

Family

ID=26315383

Family Applications (1)

Country Status (9)

Families Citing this family (4)

Family Cites Families (5)

• 2000
  • 2000-04-06 PT PT00917187T patent/PT1171304E/pt unknown
  • 2000-04-06 DK DK00917187T patent/DK1171304T3/da active
  • 2000-04-06 AU AU38281/00A patent/AU3828100A/en not_active Abandoned
  • 2000-04-06 WO PCT/GB2000/001301 patent/WO2000059727A1/en active IP Right Grant
  • 2000-04-06 EP EP00917187A patent/EP1171304B1/en not_active Expired - Lifetime
  • 2000-04-06 DE DE60005167T patent/DE60005167T2/de not_active Expired - Fee Related
  • 2000-04-06 ES ES00917187T patent/ES2207495T3/es not_active Expired - Lifetime
  • 2000-04-06 AT AT00917187T patent/ATE249339T1/de not_active IP Right Cessation
  • 2000-04-06 JP JP2000609265A patent/JP4179752B2/ja not_active Expired - Lifetime

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