Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/502—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording characterised by structural details, e.g. multilayer materials
  • B41M5/504—Backcoats
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5227—Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

• This invention relates to the decoration of sheeting, and more particularly to the decoration of materials such as standard, light weight, cellulosic sheets (paper).
• This invention also relates to the embossment of sheets or films, and more particularly to the wic ing away of oil from the decorative surface of sheets or films.
• Cellulosic sheets are normally decorated by imprinting. To achieve certain
• the imprinting requires special inks and relatively complex printing procedures.
• some decorative effects can not be realized by imprinting.
• One very desirable decorative effect is the iridescent visual effect created by a diffraction grating. This striking visual effect, attributed to Sir John Barton, Director of the British Royal Mint (circa 1770), occurs when ambient light is diffracted into its color components by reflection from a diffraction grating.
• a diffraction grating is formed when closely and regularly spaced grooves (5,000 to 11,000 grooves per cm.) are embossed on a reflective surface.
• this diffraction grating technology has been employed in the formation of two-dimensional holographic images which create the illusion of a three- dimensional image to an observer.
• This holographic image technology can form very attractive displays.
• the economics of forming holographic images is significantly dependent upon economies of scale, the concept of using holographic images to discourage counterfeiting has found wide application.
• the decorated surface of polymers is normally sufficiently reflective that the optical effect of the diffraction grating occurs without further processing, because the incident light is reflected by the facets of the decorated surface.
• the term diffraction grating includes holographic images that are based on diffraction grating technology.
• the present invention provides for embossing the coating of a substrate, such as paper sheeting.
• the coating is a thermosensitive material which has discernable thermoplastic properties.
• thermoplastic as used hereinafter, shall be construed to include such materials.
• thermoplastic material advantageously is supplied with the coating of thermoplastic material.
• the thermoplastic coating is typically applied in a water base or other suitable liquid by gravure, or reverse roll methods.
• the actual formation of the coating would begin by spreading a pre-membrane composition, formed of a dispersion of polymer spheres in evaporable ' liquid, onto the
• membrane is thermoplastic, it can be embossed to form a diffraction grating or holographic image. This must be done without destroying the porosity of the membrane; best oil wicking characteristics have been observed when the membrane has a cracked or crazed surface after embossing. The resulting optical effect or image will not be destroyed by oil which is deposited on the surface of the coating, because that oil will be ° wicked away from the surface and deposited in the underlying oil-absorbing paper substrate. Furthermore, ink adheres well to the decorative surface and, when lightly applied, does not interfere with the decorative effect produced by the embossment.
• the preferred pre-membrane coating composition is an aqueous dispersion of spheres of an oleophilic polymer such as a styrene polymer. Applicant has observed that 5 dispersions of substantially uniform particle size are preferred, and that generally larger particle sizes yield improved oil wicking characteristics. The most preferred dispersion comprises 0.5 micron diameter spheres of styrene/acrylic copolymer.
• the coating composition would also typically include a primer, a plasticizer, an emulsifier, a dispersant, pigment, and a defo ' amer. The plasticizer would be present in a minimum 0 quantity, sufficient to provide adhesion of the membrane to the substrate, but insufficient to cause the membrane to have blocking qualities.
• FIG. 1 is a schematic drawing which shows a coating operation
• FIG. 2 is a schematic which shows heating of the coated substrate of FIG. 1
• FIG. 3 is a perspective illustration of one form of embossment
• FIG. 4 is a perspective illustration of an alternative form of embossment
• FIG. 5 is a cross-section of a laminate showing the substrate and the pre- membrane layer
• FIG. 6 is a cross-section of the laminate after the pre-membrane coating has been
• FIG. 7 is a cross-sectional view of the laminate after embossing
• FIG. 8 is a cross-sectional view of the laminate after embossing and after a drop of human skin oil has been deposited on the embossed surface;
• FIG. 9 is a cross-sectional view of the laminate showing the oil being wicked away from the embossed surface
• FIG. 10 is a cross-sectional view of the laminate showing the oil having been wicked to and absorbed by the substrate.
• Standard paper sheeting 10 is provided with a thermoplastic pre-membrane coating 11, for example, by pouring the liquid pre-membrane mixture from a feed box 12 onto the upper surface 13 of the paper sheeting 10.
• the thermoplastic coating 11 may also be applied in a solvent or water-base using gravure, or reverse roll methods, represented schematically by the feed box 12.
• Paper sheeting 10 thickness usually varies from about 40 microns to about 100 microns.
• the coating weight of thermoplastic coating 11 should be sufficient to accept and retain the microembossed image; rougher papers require thicker thermoplastic coatings. On the other hand, higher
• thermoplastic coating 11 tend to increase curl of the paper sheeting.
• the preferred range for the coating weight of thermoplastic coating 11 has been determined to be about 3-20 grams per square meter.
• the paper sheeting would provide both the strength for the final product and the oil absorbing property, which, as will be seen, draws oil through the coating. It would be possible to form the substrate from a first, very strong layer (e.g., polymeric film), and a second oil-absorbing paper layer between the first layer and the coating.
• the coated substrate is outer layer of the coating 11 to evaporate the liquid carrier and to fuse or sinter the coating into a porous membrane.
• additional heating can be employed.
• an infrared heater which can be disposed away from the surface that is being softened. Such a heater is operated at heater surface temperatures of about 1,000 C F.
• thermoplastic (thermally deformable) coating 11 should be heated to well above its softening temperature.
• a practical limit to the heating of coating 11 is about 230 ⁇ C (450 ⁇ F). Above that temperature, the paper substrate begins to degrade.
• coating 11 should be heated to a temperature typically between about 120°C to 177°C ( 250 ⁇ F to 350°F), which range represents a preferred range for most thermoplastic coatings to be coalesced and embossed in the process of the present invention.
• the pre-membrane mixture is coalesced.
• the coalescing process involves the evaporation of any water (or other liquid
• the resulting coating is a porous membrane firmly attached to the substrate.
• the resulting laminate After the softened thermoplastic layer has been coalesced to a porous membrane, the resulting laminate would normally be fed directly to the embossing step. However, it would be possible to allow the resulting laminate to be cooled down and stored so that
• the embossing step might take place at some later time.
• an embossing arrangement is employed for decoration .
• the arrangement uses a heated platen 32, an embossing roll 31, and a pressure nip roll 33.
• the embossing roller 31 is a conventional embossing master which has the desired embossing pattern on its surface. This pattern is produced on the roller or rollers by engraving, embossing with a hard material, or mounting patterned plastic films or metal foils on to the surface of the roller 31.
• the embossing roller 31 contacts the softened plastic surface 11, the embossing pattern is transferred to the coating 11 on the paper. Simultaneously, the contact with the relatively cooler roller cools the coating. This cooling action prevents flow of the coating after it is removed from the embossing roller. The result is a decorated, polymer coated paper.
• embossing roller 31 should not be so low as to harden the coating 11 before the embossing is completed. It has been found that the preferred temperature for embossing roller 31 (embossing master) can vary depending on its thermoconductivity and specific heat, the embossing nip pressure, viscoelastic properties, operating speed, and the temperature to which coating is heated immediately prior to contact with the embossing roller 31. Despite the large number of variables, applicant has determined that the embossing master's (roller 31) preferred temperature in the process of the present invention is between about 66°C (150 ⁇ F) to about 93°C (208 ⁇ F) which is below the temperature of the thermoplastic coating 11. It has been determined that, in the context of the present process, this generally places the preferred web temperature between about 100 ' C (212°F) and 200°C (392°F).
• a take-off roller 34 has been added to allow longer contact between the thermoplastic coating 11 and the embossing roll 31.
• the longer contact time allows better cooling of the embossed surface to facilitate easy parting of the web from the embossing roll and to prevent possible re-flow of the coating and loss of the embossed pattern.
• the pressure nip roller 33 may be metal or may be surfaced with a resilient material such as rubber.
• the force applied between the pressure nip roller 33 and the embossing roller 31 should range from about 50 lbs. per lineal inch (PLI) to about 1,000 PLI along the length of the contact between the two rollers.
• PLI lineal inch
• 31 may advantageously be 50-300 PLI, but is more preferably between about 100-200 PLI.
• the surface of the embossing roller (roller 31) should be hard and distortion resistant so that the embossing pattern is preserved during the embossing step.
• nip roller 33 SUBSTITUTE SHEET opposing roller, i.e., nip roller 33, should be firm, but also somewhat resilient. This allows nip roller 33 to apply a nearly uniform distributed pressure to the back of the sheeting being embossed. It has been determined that nip roller 33 can be quite firm.
• ASTM D-444 typically with a Shore A durometer hardness (ASTM D-412) reading of about 70-80, or
• the contact (dwell) time wherein the embossing roller 31 and nip roller 33 contact the sheeting to achieve embossing is generally in the range of about 8 milliseconds (E.G., 300 ft./min. for a 1/2 inch wide contact area) to about 0.2 millisecond (e.g., 300 ft./min. for a 1/8 inch wide contact area).
• embossing can be achieved by the embossing. If the diffraction pattern is not to be continuous, a matte background can be provided by suitable modification of the embossing roller. Alternatively, the embossing pattern can, in parts, be filled in with coating material, such as ink or clear lacquer, in those areas where no embossed decoration is desired.
• coating material such as ink or clear lacquer
• FIG. 5 shows an enlarged cross-sectional view of the substrate 10 which is a paper sheet with a coating 11 of pre-membrane mixture, prior to the fusing of the pre-membrane mixture 11.
• FIG. 5 shows the thermoplastic spheroids 37, 38, 39, and 40 which make up the primary component of the pre-membrane mixture 11. The spheroids form the coating 11 on the substrate 10 prior to fusing of the coating.
• FIG. 5 is figurative in that it shows the interface between the upper surface 13 of the substrate 10 and the lower layer of the uncured coating 11. Typically, the spheres would be piled up more than forty spheres deep on
• FIG. 6 shows a cross-sectional view of the laminate after the coating 11 has been fused to form a porous membrane.
• the spheroids present in FIG. 5 are fused together in such a way that pores 46, 47, 48 and 49 are formed between the spheroids which pores pass from the upper surface 14 of the coating 11 to the lower surface 15 of the coating 11.
• the lower surface of the coating 11 is, of course, in contact with the upper surface
• the microporous membrane coating would be about 20 microns thick (top to bottom) and about 100 microns between pores.
• the pores are about five microns wide and form a mud-crack-like interconnected three- dimensional network which connects the coating surface to the substrate.
• the pores are shown as capillaries which run from the top to the bottom of the coating, but it should be understood that the pore structure may be more complicated, e.g., a series of interconnecting cracks.
• Applicant has observed that the final surface texture depends upon the choice of polymer particle dispersion (see Example 1, below) as well as the drying and embossing conditions. Longer drying times, and higher embossing temperatures, both tend to increase the time required for wicking
• Oil In general, a cracked or crazed surface provides superior oil wicking properties.
• FIG. 7 shows an enlarged cross-sectional view of the laminate of the present invention after the embossing of the upper or decorative surface of the coating 11 has been accomplished.
• the embossing is shown as grooves 51.
• the grooves are one micron peak-to-peak and one-half micron deep.
• FIG.- 8 shows an enlarged cross-sectional view of the laminate of the present invention with a drop of human skin oil 50 deposited on the upper surface 14 of the coating 11.
• the oil has penetrated the grooves 51 in the embossed surface and, because the index of refraction of the oil and of the thermoplastic from which the coating 11 is formed are not vastly different, the visual effect of the grooves beneath the oil is effectively extinguished.
• FIG. 9 shows an enlarged cross-sectional view of the laminate of the present invention in which the oil has wetted and been attracted to the internal surface of the pore 46 so that the oil is drawn down into the pore and toward the substrate 10.
• FIG. 10 shows an enlarged cross-sectional view of the laminate of the present
• the key element of the present invention is the microporous coating which is adapted to absorb, into its pores, any oil which is deposited on its decorative or embossed surface.
• the polymer from which the membrane is formed must form pores which have pore surfaces which are oleophilic, that is, they must attract or be wetted by human skin oil.
• the membrane would be formed by the fusion of thermoplastic polymeric particles of uniform size into the membrane skin populated with pores or micrOcracks capable of absorbing oil. As seen in Example 1, below, a particle diameter of about 0.5 microns is preferred.
• the microporous coating has the ability to also transmit gasses, but repel water (hydrophobic).
• the pre-membrane mixture consists of uniform 0.5 micron diameter polystyrene spheroids dispersed in water with a plasticizer, colored pigment dispersions (if desired for appearance) and certain other processing aids.
• this coating is applied to the paper substrate and dried at 130°C (266°F), the polystyrene particles fuse together, leaving a clear film containing interconnecting microcracks. These cracks are capable of wicking away any surface oils into the membrane and thereafter into the paper substrate below.
• the coating can be stored after fusing or thermally embossed immediately after fusing.
• the pre-membrane mixture of the present invention would typically involve the following ingredients.
• the binder an aqueous dispersion of uniform polystyrene particles (Lytron 2502 from Morton International), is 48% solids in the aqueous carrier.
• the Lytron alone has good oil absorption and dries to a clear membrane. However, it exhibits curl when applied to the paper. Greater cohesive and adhesive strengths are also preferred.
• the binder (and its aqueous carrier) are approximately 80% by weight of the total dry coating weight. Within the Lytron series, applicants have observed that particles should preferably be at least 0.1 micron in diameter, with 0.5 micron diameter most preferred.
• a plasticizer e.g. butyl benzyl phthalate is needed to soften the coating. This reduces curl, reduces the glass transition temperature, (which also lowers the embossing temperature) and adds gloss to the coating.
• the plasticizer is less than 5% by weight of the dried coating and is kept to a minimum to allow the coating to adhere to the paper without causing blocking in the finished product.
• An emulsifying agent e.g., nonionic alkylphenyl polyether alcohol (Triton X-100 from Rohm and Haas), is needed to compatibilize the plasticizer with the polystyrene dispersion.
• the emulsifying agent can be 5% of the plasticizer weight or 0.2% of the total mix.
• Pigment dispersions e.g., toluidene red (AIT 222 Day Glo Color Conp.)
• a dispersing agent (e.g., DISPERSE AYD W-28 from Daniel Products) should be added to the plasticizer/polystyrene mix to compatibilize the pigment dispersion with the polystyrene mix.
• a Defoamer (e.g.,Bubble Breaker 748 from Witco Corp.) is incorporated into
• the plasticizer should be charged with the emulsifying agent.
• the binder is then added to the plasticizer under gentle agitation.
• Half of the defoamer should be added to the mix, followed by the dispersing agent.
• the pigment dispersion can be slowly added to the mix, followed by the balance of the defoamer.
• a carboxylated acrylic copolymer latex (Hycar 26315 from BF Goodrich) had slower oil absorption than Lytron.
• the primer addition in formulation D adds adhesive strength to the coating.
• Paper bonds are enhanced if dried at a low temperature (110°C as opposed to 130°C). Reduced gloss and embossed definition result, however.
• Formulation B Oil Absorbing Embossable Coating (Red transparent) % by weight
• Pigment dispersion (Phthalo Green) ATT 544 from Day Glo Color Corp. 16.2
• Formulation E with appropriate choice of color pigment, provides the best combination of properties. It can be fused by heating to 110°C (230 ⁇ F) to form a very effective membrane.
• the preferred paper is high-wet-strength, clay-coated paper.
• the dispersions were coated on 35 grams per sq. meter Sibille Stenay clay- coated stock (One Newbury St., Peabody, Massachusetts 01960), using a #12 wire-wound rod.
• the samples were dried in a 130°C oven for twenty seconds, then embossed at 120°C using a diffraction embossed metallized mylar master. The quality of embossing was evaluated in terms of release of the master from the embossed coating.
• the embossed coated papers were tested for oil wicking by smearing skin oil across the surface and measuring the time for the diffraction pattern to reappear. Adhesion of the coating to the paper was determined using 3M MAGIC tape (Minnesota Mining & Mfg.
• ADCOTE 61 JH61 A is a styrene/acrylic copolymer dispersion of Morton Chemical Co., Chicago, Illinois.
• 37R345 is a high molecular weight ethylene interpolymer dispersion from Morton Chemical Co.
• UNOCAL 3512 is an acrylic polymer dispersion from B. F. Goodrich Chemical Co., Cleveland, Ohio.
• SUBSTITUTE SHEET EXAMPLE 2 The binders of Table 2, below, were coated onto paper, dried, and embossed as in Example 1. All of the resulting embossed media were observed to lack oil absorbancy.
• PVB with Di-n hexyl Adipate (Santicizer 367/Monsanto) 5. Vinyl Chloride/Vinyl Acetate TerPolymer solution (VAGH/Union Carbide)
• Blends of Styrene acrylic CoPolymer emulsion and Poly Styrene dispersion (Nat- 78 NationalaL/Lytron 2502 Morton) 14.
• Acrylic CoPolymer emulsion (Neocryl Bt-24/ici) 15.
• Poly Styrene Solution (18-210/Amoco)
• This technique may also be used to produce

Landscapes

• Laminated Bodies (AREA)
• Cleaning Implements For Floors, Carpets, Furniture, Walls, And The Like (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Developing Agents For Electrophotography (AREA)
• Stringed Musical Instruments (AREA)
• Stereophonic System (AREA)
• Paper (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Polyurethanes Or Polyureas (AREA)
• Thermotherapy And Cooling Therapy Devices (AREA)
• Holo Graphy (AREA)

Priority Applications (7)

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Publications (1)

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Cited By (7)

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Citations (2)

• 1991
  • 1991-11-01 DE DE69103905T patent/DE69103905T2/de not_active Expired - Fee Related
  • 1991-11-01 WO PCT/US1991/008168 patent/WO1992007723A1/en active IP Right Grant
  • 1991-11-01 EP EP92901236A patent/EP0555398B1/de not_active Expired - Lifetime
  • 1991-11-01 JP JP4502245A patent/JPH06502818A/ja active Pending
  • 1991-11-01 AU AU90575/91A patent/AU651162B2/en not_active Ceased
  • 1991-11-01 BR BR919107019A patent/BR9107019A/pt not_active Application Discontinuation
  • 1991-11-01 DK DK92901236.7T patent/DK0555398T3/da active
  • 1991-11-01 ES ES92901236T patent/ES2059208T3/es not_active Expired - Lifetime
  • 1991-11-01 AT AT92901236T patent/ATE111031T1/de not_active IP Right Cessation
  • 1991-11-01 CA CA002095337A patent/CA2095337A1/en not_active Abandoned
• 1993
  • 1993-04-30 FI FI931974A patent/FI931974A/fi not_active Application Discontinuation
  • 1993-04-30 NO NO93931589A patent/NO931589L/no unknown

Patent Citations (2)

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