METALLIZATION OF SUPPORT MEMBERS

Abstract: Method and apparatus for the metallization of support members, such as paper sheeting and other cellulosic products. A metallic film (13) is transferred to the paper support (21) from a plastic sheet carrier (11) and adhered to the paper by a thermoplastic material (24). The carrier, typically of stabilized plastic (12) with a releasably adhered film of metal (13) and an overlay of thermoplastic adhesive (24) with the paper support. Separate metallic films may be transferred simultaneously from a plastic sheet carrier to separate paper supports and the transferred metallic films ad ered to the respective paper supports by a thermoplastic material. The carrier therein may typically be of stabilized plastic with an adhered film of metal on opposite surfaces. Pressure and/or heat is applied to the composite which is subsequently cooled and the carrier (12) stripped away to leave the desired metallic layer on the receiving surface of the paper support. This transfer procedure overcomes the objections associated with metal foil laminates and is particularly suitable for metallizing support members, like paper, which are difficult to metallize directly because they release significant amounts of vapor during conventional vacuum metallization. The results are also superior to those realized using an adhesive with dispersed metal particles, and the need for curing of the adhesive is eliminated.

Description: METALLIZATIQN OP SUPPORT MEMBERS BACKGROUND OF THE INVENTION This invention relates to the metallization of support members and, more particularly, to the metallization of cellulosic support members such as paper. Metallization is a process in which a metallic material such as aluminum, is applied to an underlying support mem¬ ber. This can be done by bonding a thin film of metallic foil to the surface of the support member. The bonding takes place using a suitable adhesive and the resulting pro- duct is a laminate of the support material and the foil. Alternatively, metal is vaporized in a high vacuum using resistance, induction or an electron beam and forms a metallic layer on a support member. This procedure is suitable only for support members that do not contain signi- ficant amounts of moisture. When moisture is present, the vacuum draws vapors and other by-products which must be eliminated before subsequent metallizing can take place. Irregularities in the support surface also appear in the final product. As a result, where it is desired to employ a vacuum for the direct metallization of a paper support member, the pap¬ er is first dried to a level where there will be negligible outgassing. This, procedure, however, makes the support material brittle and difficult to process. Additionally, once the vacuum metallization of the dried paper is com¬ pleted, it is necessary to restore its moisture level to near its original value. This is a time consuming and costly procedure that requires the use of appreciable amounts of energy for drying Accordingly, it is an object of the invention to facili¬ tate the metallization of support members, particularly cellulosic products such as paper. A related object is to facilitate the metallization of support members with irregu¬ lar surfaces. Another related object is to achieve suit- able metallization of support members that exhibit outgass¬ ing when subjected to a vacuum. OMPI Another object of the invention is to achieve suitable smoothness and reflectivity for metallized support surfaces. Still another object of the invention is to achieve efficient and high speed metallization of support members. Still other objects of the invention are to overcome the disadvantages associated with metallization by foil lamination and metallization by vacuum. One attempt to overcome the foregoing difficulties involves the -application of an adhesive with dispersed metallic powder to a support surface. This procedure re¬ quires that the metallic laden adhesive be allowed to cure on the support surface. Curing requires that the product be aged for a considerable period of time. The result is a reduction in the efficiency and speed with which the de- sired metallized product can be produced. Furthermore, metallic powder creates environmental dust objections. There can be the further objection that surface irregulari¬ ties in the support member " are not completely compensated. Finally the dispersion of metallic powder in an adhesive prevents the realization of a continuous metallic film and is accompanied by an inevitable reduction in the reflectiv¬ ity of the metallized surface. Much of the metal is deposi¬ ted at an interval level of the adhesive where it is in¬ effective in the desired reflectance of light. Accordingly, it is still another object of the inven¬ tion to achieve suitable metallization of support members having irregular surfaces without the disadvantages associ¬ ated with the prior art use of metallic powders. Another object is to achieve the desired metallization without requiring that metallic powder be dispersed in an adhesive which must be allowed to cure. Still another object of the invention is to increase the efficiency of metallization over and above that which can be achieved by a process which requires curing. A further object of the invention is to increase the efficiency with which the metal used in metallization con- tributes to the reflectivity of light from a metallized surface. A related object is to avoid the loss of re¬ flectivity by metallic elements such as powder which becomes embedded below the surface where the reflectiv- ity takes place. Another object is to metallize a plurality of sup¬ port sheets simultaneously. A related object is to re¬ duce the cost of achieving support sheet metallization. StJMMARY OF THE INVENTION In accomplishing the foregoing and related objects, the invention provides a metallization method in which a support member, such as paper sheeting, receives a metal¬ lic film from a plastic sheet carrier. The metallic film carries a water-based thermoplastic adhesive material, and becomes adhered to the paper support thereby. The thermoplastic material serves to compensate for any ir¬ regularities in the support surface, and the transferred metallic film is provided with a suitable degree of smooth- ness by virtue of its contact with a smooth mating surface of the plastic carrier. In accordance with another aspect of the invention, the metallizable member is a support with a thermoplastic layer, and the transfer member is a plastic sheet with a metallic layer. The plastic sheet is selected from the classes of olefins and polyesters. A particularly suit¬ able olefin is biaxially oriented polypropylene. In the case of polyesters the metallic layer is releasably ad¬ hered thereto by a material such as wax. In accordance with another aspect of the invention, release between the metallic film and plastic sheet carrier is promoted by the inclusion of a vapor coating of a release agent, such as Oricury wax, between the car¬ rier and the overlying metallic film. In accordance with a further aspect of the invention, a metallization method is provided in which a plurality of support members, such as paper sheeting, simultaneously receive a metallic film from a plastic sheet carrier. The metallic film becomes adhered to each paper support by a water-based thermoplastic adhesive material. The " latter serves to compensate for any irregularities in the- support surface, and the transferred metallic film is provided with a suitable degree of smoothness by virtue of its con¬ tact with a smooth mating surface of the plastic carrier. In accordance with one aspect of the invention the plastic sheet carrier has metallic layers on opposite surfaces thereof and a composite is formed of the plastic sheet carrier and separate • support members facing oppo¬ site sides of the carrier. In accordance with one aspect of the invention the water-based thermoplastic adhesive layer is applied to the composite of the support member and the metallized plastic carrier. Where there are a plurality of support members, the thermoplastic layer is applied between each support member and the metallized plastic carrier. The thermoplastic layer in the composite is then caused to flow, by, for example, being subjected to pressure and/ or heat. The pressure and/or heating effect is sufficient to produce flow in the thermoplastic layer short of melt- ing. The composite is thereafter cooled and the plastic sheet stripped away to leave the support member with the metallic film adhered to it by the thermoplastic layer. In accordance with another aspect of the invention, the plastic sheet is remetallized and used in the subse- quent metallization of other support members. The number of reuses is governed by the thickness .of the plastic sheet, with a reuse permitted for each 0.1 mil thickness of the sheet. In accordance with still another aspect of the inven- tion the support member is a sheet of cellulosic material which Is prepared from either mechanical or chemical pulp. The cellulosic sheet desirably is size-press coated on at least the receiving surface for metallization with a water dispersion of clay and resin. The resin is advantageously aqueous styrene butadiene. In accordance with a further aspect of the invention the thermoplastic layer is selected from the class con¬ sisting of styrenes, styrene-polyolefin mixtures, poly- amides, nitrostyrenes, vinyl acetate and copolymers includ- ing ethylene vinyl acetates, vinyl chlorides, acrylics, and plas ' ticized nitrocelluloses. A particularly suitable thermoplastic layer is a mixture of styrene and vinyl OMΠ resins being, for example, 80 parts styrene butadiene and 20 parts vinyl acetate, or 80 parts styrene and 20 parts ethylene vinyl acetate. In accordance with yet another aspect of the inven- tion, the thermoplastic material that serves as the ad- hesive includes a viscosity modifier selected from the class consisting of amine esters, sulphated oils, col¬ loidal silicas, polyoxyalkylene fatty acid esters, starches, carboxylated cross-linked acrylic emulsions, methyl vinyl ether maleic anhydrides and carboxylated methyl celluloses. One part of the viscosity modifier .Is desirably Included with each 100 parts of thermoplas¬ tics. The viscosity modified thermoplastic is prepared. A coating emulsion that desirably ranges between 20 and 6 " 0 percent solids and is advantageously 38 percent solids. In accordance with a still further aspect of the In¬ vention, the thermoplastic is rendered flowable by being subjected to pressure at the nip of two rollers which pro¬ vide a force In the range from about 200 to 1000 pounds per linear inch, preferably 600 pounds per linear Inch. In accordance with a yet further aspect of the inven¬ tion, the metallizable member is a support with a thermo¬ plastic layer, and the transfer member Is a plastic sheet with two metallic layers. The plastic sheet is selected from the class of olefin and polyesters. A particularly suitable olefin Is biaxially oriented polypropylene. ' If the plastic sheet is formed of polyesters, the metallic layers are advantageously releasably .adhered thereto by a material such as wax. In accordance with still another aspect, the inven¬ tion can be used for the metallization of support members in the form of paper board having a basis weight in the range of from 100 to 400 grams per square meter. This kind of metallization cannot be accomplished by conven- tional techniques. In accordance with yet another aspect of the inven¬ tion, the release agent between the plastic carrier and O FI ■ the overlying metallic film includes waxes and wax-like materials. Natural waxes for the practice of the invention, in addition to Ouricury, which is similar to Carnauba and is obtained from the palm leaf, include Carnauba, which is an exudate from the pores of the leaves of the Brazilian wax palm; condelilla, which is obtained from the Condelilla plant found largely in Mexico; Esparto which is also known as Spanish Grass Wax and is found elsewhere in the Mediterranean region Sugar Cane Wax made by extraction with Heptane in the production of sugar cane Montan, which is obtained by extraction from lignite and peat; Ozocerite, also known as Ozokerite, which is a yellowish brown mineral wax occurring naturally as a mixture of solid hydrocarbons; and Beeswax. The synthetic waxes include those made by purifying Mbntan wax and synthetic paraffin wax. Another suitable synthetic wax is microwax which is characterized by a mierocrystalline structure and is produced in a fashion . similar to that of the synthetic paraffins. Wax-like materials for the practice of the invention include metallic salts of fatty acids of at least eleven carbon atoms and preferably of at least eighteen carbon atoms such as stearates, oleates or linoleates of zinc, calcium, barium, magnesium, aluminum and zirconium. Such wax-like materials are sold in dry or water dispersed form. DESCRIPTION OF THE DRAWINGS Other aspects of the invention will become apparent after considering several illustrative embodiments, taken in conjunction with the drawings in which: FIGURE 1 Is a fragmentary perspective view of a metallization, system in accordance with the Invention; FIGURE 1A is a fragmentary diagrammatic view of a metallization system in accordance with an embodiment of the invention wherein separate metallic films are trans- ferred simultaneously from a plastic sheet carrier to separate paper supports. FIGURE 2 is a portion of a metallized plastic carrier for use in the system of FIGURE 1; FIGURE 2A is a portion of a metallized plastic car- rier for use in the system of FIGURE 1A; FIGURE 3 Is a fragmentary sectional view of a thermo¬ plastic coated receiver or support sheet for use in the system of FIGURE 1; and FIGURE 3A is a fragmentary sectional view of a thermo- plastic coated receiver or support sheet for use in the system of FIGURE 1A; FIGURE 4 is a schematic view of a two-zone direct metallization chamber for preparing the metallized plastic carrier of FIGURE 2; FIGURE 4A is a schematic view of a two-zone direct metallization chamber for preparing the metallized plastic carrier of FIGURE 2A; FIGURE 5A is a schematic view of a two-zone direct metallization chamber for preparing the metallized plastic carrier of FIGURE 2A in a single pass through the chamber. FIGURE 6 is a schematic view of a two-zone direct metallization chamber for preparing a metallized plastic carrier in accordance with the invention; and FIGURE 7 is a portion of a metallized plastic carrier produced by the chamber of FIGURE 6. ■DETAILED DESCRIPTION With reference to the • rawings, a metallization sys¬ tem S In accordance with the Invention is shown in frag¬ mentary outline in Figure 1. The system S makes use of 5 two supply rolls 1 and 2, a heated drum 3, a contacting resilient drum k t a water cooled drum 6 and rewind rolls 7 and 8. The supply roll 1 carries a wound carrier sheet 11 of a metallized plastic sheet. The metallic side of the 0 sheet 11 carries a thermoplastic coating and faces a re¬ ceiving or support sheet 21 that is supplied from the lower supply drum 2. The specific structure of the carrier sheet 11 on the supply drum 1 is shown in detail in Figure 2. Si i- 5 larly, the specific structure of the coated receiving sheet 21 is shown in detail In Figure 3. The metallized carrier 11 on the upper supply drum 1 is unrolled and extended over an Intervening idler roll 9-1 to the lower surface of the heated drum 3« 0 The receiving or support sheet 21 from the lower supply drum 2 also extends to the intervening idler roll 9-1 where It makes contact with the thermoplastic surface of the carrier 11. The two sheets 11 and 21 then extend in contact with one another to the heated drum 3 where 5 pressure is applied by the resilient drum k at a nip 5- The drum can be of any suitable construction as long as its surface provides suitable resiliency. The composite of the carrier 11 and the support 21 extends from the nip 5 to the lower surface of the water cooled drum 6. The C purpose of the drum 6 is to lower the temperature of the composite tc a suitable level before separation of the two sheets 11 and 21 which takes place at the upper sur¬ face of a second idler roll 9-2. The separated sheets are wound on respective takeup rolls 7 and 8 with the sheet 11' on the upper roll 8 being devoid of its metallic layer which has been transferred to the metallized sheet 21' that is wound on the lower roll 7. The resulting metallized sheeting 21' is subsequently ?ι -10- re oved with the'lower roll 7- It will be understood that the various rolls 1, 2, 9-1, 9-2, 7 and 8 are supported in conventional fashion. The various rolls are also of a diameter that is appro- 5 priate for the stock being processed. As the basis weight of the stock increases,- the diameters of the associ¬ ated rolls are increased correspondingly. In addition, heating of the drum 3 and water cooling of the drum 6 are accomplished conventionally. Heating of the drum 3 is 0 unnecessary when the pressure between the drums 3 and 4 is sufficient to render the thermoplastic flowable. The combination of heat and pressure, however, is desirable to accentuate this result. As can be seen from the detailed fragment in Figure 5 2, the metallized plastic carrier 11 includes a plastic substrate 12, a metallic coating 13, and a thermoplastic layer 14. Similar details for the receiver support 21 are shown In Figure 3- The coated paper sheet 21 is con¬ stituted by a base paper layer 22, a size press coating 0 24, and a bonding layer 23 between the coating 24 and the base paper 22. It is to be noted that the thermoplastic layer 14 faces the coating 24 of the sheet 11 In Figure 1. Metallization of the plastic substrate 12 of the com¬ posite 11 in Figure 2 can be achieved in a chamber C as 5 illustrated in Figure 4. A supply drum wound with a plastic sheet 12- has Its sheet extended over an idler roll I around the periphery of a water cooled drum, and then about a second Idler roll I to a rewind drum. The chamber f 'C n is divided into two .zones; the first zone, 0 which is semicylindrical, is at a pressure P.. and the remaining semicylindrical zone is at a pressure P ? , where the pressure P is lower than pressure P... Consequently, conventional seals S, and S p are used to retain the pressure differential between the two portions of the 5 chamber C where the sheet 12 from the supply drum enters and then leaves as metallized sheet 11. In the metal¬ lizing portion, metal, for example aluminum, is ' vaporized as represented by the symbol Δ AL and allowed to accumu- late on the plastic sheet 12 as the layer 13. In another embodiment of the invention as illus¬ trated best by Figures 1A to 5A, separate metallic films are transferred simult-aneously to separate paper supports from a plastic sheet carrier and adhered to the respective paper supports by a thermoplastic material. With reference to the drawings, a metallization system S in accordance with the invention is shown in fragmentary outline in Figure 1A. The system S makes use of three supply rolls 1, 2 and 3 » a heated drum 4, a contacting resilient drum 5, a water cooled drum 7 and rewind rolls 8, 9 and 10. The supply roll 2 carries a wound carrier sheet 11 of a plastic sheet that is metallized on opposite sides. Each metallic side of the sheet 11 faces a thermoplastic coating on receiving and support sheets 21 and 31 that is supplied from drums 1 and 3- The specific structure of the carrier sheet 11 on the supply drum 2 is shown in detail in Figure 2A. Similarly, the specific structure of the coated receiving sheets 21 and 31 are shown in detail in Figure 3A. The metallized carrier 11 on the intermediate supply drum is unrolled and ' .extended to the lower surface of the heated drum . The receiving or support sheets 21 and 31 from the upper and lower supply drums 1 and 3 also extend into contact with the respective metallized surfaces of the carrier 11. The three sheets 11, 21, and 31 are subjected to pressure by the resilient drum 5 and then extend in contact with one another to the cooled drum 7. The drum 5 can be of any suitable construction as long as -its sur¬ face provides suitable resiliency. The composite of the carrier 11 and the supports 21 and 31 extend from the nip of the drums 4 and 5 to the lower surface of the water cooled drum 7. The purpose of the drum 7 is to lower the temperature of the composite to a suitable level before O ?I separatlon of the sheets 11, 21 and 31 takes place at the upper surfaee of an idler roll 6. The separated sheets are wound on respective takeup rolls 8, 9 and 10 with the sheet 11' on the central roll 9 being devoid of its metallic layers, which have been transferred to the metallized " sheets 21* and 31* that are wound on the respective upper and lower rolls 8 and 10. The resulting metallized sheetings 21* and 31' are subsequently removed with the upper and lower rolls 8 and 10. It will be understood that the various rolls 1-10 are supported in conventional fashion. The various rolls are also of a diameter that is appropriate for the stock being processed. As the basis weight of the stock in- creases, the diameters of the associated rolls are In¬ creased correspondingly. In addition, heating of the drum 4 and water cooling of the drum 7 are accomplished conventionally. Heating of the drum 4 is unnecessary when the pressure between the drums 4 and 5 is sufficient to render the thermoplastic flowable. The combination of heat and pressure, however, Is desirable to accentuate this result. As can be seen from the detailed fragment in Figure 2A, the metallized plastic --carrier 11 includes a plastic substrate 12 and opposed metallic coatings 13 and 14. Similar details for the identical receiver supports 21 and 31 are shown in Figure 3 5 for the illustrative sup¬ port 21. The coated paper sheet 21 is constituted by a base paper layer 22, a thermoplastic coating 24, and dif- fusion bonding layer 23 between the thermoplastic coating 24 and the base paper 22. It is to be noted that the thermoplastic layer 24 faces the metallic coating 13 (or 14) of the sheet 21 (or 3D in Figure 1A. Metallization of the plastic substrate 12 of the composite 11 in Figure 2A can be achieved using a chamber C illustrated in Figure 4A. A supply drum wound with a plastic sheet 12 has its sheet extended over an GI^F idler roll I around the periphery of a water cooled drum, and then about a second idler roll I_ to a rewind drum. The chamber "C" Is divided into two zones; the first zone, which is semicylindrical, Is at a pressure P, and the remaining semicylindrical zone. is at a pressure P 2, ' where the pressure P p is lower than pressure P, . Conse¬ quently, conventional seals S, and S ? are used to retain the pressure differential between the two portions of the chamber C.where the sheet 12 from the supply drum enters and then leaves as metallized sheet 11. In the metallizing portion, metal, for examples aluminum is vapor¬ ized as represented by the symbol Δ AL and allowed to accumulate on one surface of the plastic sheet 12 to form the layer 13- The rewind drum is then removed and sub- stituted for the supply drum, and the metallized sheet 11, with the metallic coating 13 is extended into the remaining semicylindrical section with the metallic layer 13 facing the water cooled drum. The subsequent metal¬ lization that occurs then creates the remaining metal- lized layer 14. Alternatively, the metallized plastic carrier 11 of Figure 2 can be prepared with metallic layers 13 and 14 deposited on opposite sides of the carrier in a single pass using the metallization chamber C illustrated in Figure 5A. As in the case of Figure 4A the chamber C is divided into two semicylindrical zones at respective pressures P η and P ? , with the pressure P ? being lower than the pressure P, . By contrast with Figure 4A the chamber C of Figure 5A includes two water cooled drums D, and D„. A plastic carrier 12 from the supply roll is extended from the zone P η around the first water cooled drum D " Into the second zone P ? and then out of the. zone over an idler roll I-,, returning into the second zone P ? over the second water cooled drum D ? . " The metallic layer 13 of Figure 2 is applied to the carrier 12 by vapor deposition of metal as the carrier travels about the first water cooled drum D, in the second zone P ? . Subsequently the remaining metallic layer 14 is deposited on the opposite side of the carrier 12 as the carrier returns to the second zone, with its opposite side already metallized, and travels about the second water cooled drum D ? . The two-sided metallized carrier 11 Is then collected on the rewind roll in the first zone P- . In accordance with another embodiment of the inven¬ tion, a metallization chamber C for use in accordance with the invention is shown in fragmentary outline in Figure 6. With reference to Figure 6, metallization of a -plastic carrier 12 Is achieved In the chamber C. A sup¬ ply drum has its polyester sheet 12 extended over an idler roll I-, around the periphery of a water cooled drum, and then about a second idler roll I ? to a rewind drum. The chamber C Is divided into two zones, the first zone, which is semicylindrical, is at a pressure P.. and the remaining semicylindrical zone is at a pres¬ sure P~, lower than pressure P, . In the first zone, which may be at a pressure as high as 0.1 Torr to 0.01 Torr a naturally occurring Ouricury wax is evaporated (desig¬ nated by the symbol ΔW in Figure 6) and condensed as an invisible layer on the polyester. It will be understood that the wax serves a release function for a subsequently applied aluminum layer which is evaporated and condensed on the wax coated surface in the second section. Any material which provides the desired release function may be employed including both natural and synthetic waxes and wax-like materials. Natural waxes for the practice of the invention in- elude Carnauba, which is an exudate from the pores of the leaves of the Brazilian wax palm; condelilla, which is ob¬ tained from the Condelilla plant found largely in Mexico; Esparto which is also known as Spanish Grass Wax and is found elsewhere in the Mediterranean region; Sugar Cane Wax made by extraction with heptane in the production of sugar cane; Ouricury, which is similar to Carnauba and is obtained from the palm leaf; Montan, which is obtained by extraction from lignite and peat; Ozocerite, also known as Ozokerite, which is a yellowish brown mineral wax occur¬ ring naturally as a mixture of solid hydrocarbons; and Beeswax. The synthetic waxes include those made by purifying Montan wax and synthetic paraffin wax. Another suitable synthetic wax is icrowax which is characterized by a microcrystalline structure and is produced in a fashion similar to that of the synthetic paraffins. Wax-like materials for the practice of the invention include metallic salts of fatty acids of at least eleven carbon atoms and preferably of at least eighteen carbon atoms such as stearates, oleates or linoleates of zinc, calcium, barium, magnesium, aluminum and zirconium. Such wax-like materials are sold in dry or water dispersed form. Conventional seals S-. and S ? are used to retain the pressure differential between the two portions of the cham¬ ber C where the sheet 12 from the supply drum enters and then leaves as metallized sheet 11. In the metallizing portion, metal, for example aluminum is vaporized as repre¬ sented by the symbol Δ AL and allowed to accumulate on the plastic sheet 12 to form the metallic layer 13. As can be seen from the detailed fragment in. Figure 7 s the metallized polyester carrier 11 includes a plastic substrate 12, a metallic coating 13, and a release layer 14. The metallic coating 13 of polyester carrier 11 of Figure 7 is trans¬ ferable to receiver support 21 of Figure 3 by utilization of system S of Figure 1 as described in the foregoing. The invention is further illustrated with reference to the following illustrative examples which are to be taken as nonlimiting. EXAMPLE I Ground wood (mechanical pulp) paper sheeting of stand¬ ard basis weight is size-press coated in conventional fashion. The coated paper sheeting is then provided with a thermoplastic layer having a weight of 4 grams per square meter. f C ?I Plastic sheeting that has a metallic layer with a thickness of about 200 angstroms has its metallic sur¬ face brought Into contact with the thermoplastic layer of the paper sheeting and subjected to pressure and heat to render the thermoplastic flowable. The composite of the thermoplastic layer, the paper sheeting and the metallized plastic sheeting is then cooled and the plastic sheeting peeled away, transferring the metallic layer to the paper sheeting by virtue of the adhesive effect of the thermoplastic layer. The result is a metallized sheet of paper with a high and acceptable degree of reflectivity, with the metallic layer stripped away from the plastic sheeting, which is reusable. This example is repeated with two coated paper sheet¬ ings prepared, each with a thermoplastic layer having a weight of 4 grams per square meter. The plastic sheeting has metallic layers of 200 angstrom thickness on opposed surfaces and has its metallic surfaces brought Into con- tact with thermoplastic layers of the respective paper sheetings and subjected to pressure and- heat to render the thermoplastic flowable. The composite of the thermoplastic layers, the paper sheetings and the metallized plastic sheeting is then cooled and the plastic sheeting peeled away, transferring the metallic layers to the respective paper sheetings by virtue of the adhesive effect of the thermoplastic layer. The result is two metallized sheets of paper, each with a high and acceptable degree of reflectivity provided by metallic layers that have been stripped away from the plastic sheeting, which is reusable. EXAMPLE II Example I is repeated with the plastic sheeting re- metallized on one surface or on opposite surfaces and used to transfer a metallic layer to one or two different paper carriers respectively for each remetallization. Q-.'rl The result in each case is a metallized paper sheet with a high and acceptable degree of reflectivity. EXAMPLE III Example II is repeated according to the thickness of the plastic sheeting, with one reuse per 0.1 mil thickness of the sheeting, so that a 0.5 mil thickness permitted five reuses and a 0.9 mil thickness permitted nine reuses. In each case the metallized paper exhibits suitable re¬ flectivity. EXAMPLE IV The preceding examples are repeated using ground wood paper sheeting having a basis weight in the range from about 40 to 60 grams'per square meter, and preferably about 50 grams per square meter. The results are substan- tially the same as for Example I. EXAMPLE ' V The preceding examples are repeated using paper board having a basis weight in the range from about 100 to 400 grams per square meter. The results are substantially the same as for Example I. EXAMPLE VI The preceding examples are repeated using a size press coating on at least one side with a water dispersion of clay and resin. The results are substantially the same as for Example I. • EXAMPLE VII The preceding examples are repeated using a size press coating In which the resin Is aqueous styrene butadiene.. The -results are substantially the same as for Example I. EXAMPLE VIII The preceding examples are repeated in which the thermoplastic layer is plastic provided by a mixture of styrene and vinyl resins. The results are substantially the same as for Example I. EXAMPLE IX Example VII is repeated using a water-based thermo¬ plastic layer of 80 parts styrene butadiene, for example Dow No. 620, with- 20 parts vinyl acetate, for example Borden No. 2142. The results are substantially the same as in Example I. EXAMPLE X The preceding examples are repeated with a viscosity modifier added to the thermoplastic layer. The results are an improvement over those of Example I. EXAMPLE XI Example X is repeated using a viscosity modifier selected from the class consisting of amine esters, for example "NAPCO DC 133" of the Napco Chemical Co.; sulphated oils, for example "NAPCO CUSTER" of the Napco Chemical Co.; colloidal silicas, for example "CAB-0-SIL" of Cabot Corp.; polyoxyalkylene fatty acid esters, for example "NONISOL 300" of the Ciba-Geigy Chemical Company; starches, for example "NUFILM H" of the National Starch and Chemical Corp.; carboxylated cross-linked, acrylic emulsions, for example "ACRYSOL ASE 60" of the Rohm & Haas Co.; methyl vinyl ether maleic anhydrides, for example "GANTREZ AN-119" of the GAF Corp. Chemical Products; and carboxy methyl celluloses, for example "NATR0S0L 7M, 7L or 7H" of Hercules, Inc. EXAMPLE XII The preceding examples are repeated with the thermo- plastic layer being provided by a coating emulsion in water of ethylene vinyl acetate and styrene. EXAMPLE XIII The preceding examples are repeated with the coated paper sheeting and thermoplastic layer dried to a moisture content in the range from about 2-13 per cent, with 6 per cent being preferred. EXAMPLE XIV The preceding examples are repeated with the plastic sheeting selected from the class of olefins, including in particular polypropylene which has at least a unlaxial orientation, and preferably a biaxial orientation, for example Hercules biaxial polypropylene film sold under the trademark and trade name "B-503 BOP". EXAMPLE XV The preceding examples are repeated with the paper and the plastic sheeting being advanced during pro¬ cessing at a speed ranging between 200 and 1000 fpm with a speed of 600 fpm being preferred. EXAMPLE XVI The preceding examples are repeated with the compos¬ ite of the coated paper sheeting and the metallized plastic sheeting being cooled to about room temperature by a water cooled drum. ' EXAMPLE XVII The preceding examples are repeated with chemical pulp paper, achieving the same degree of reflectivity as Example I with less metal. EXAMPLE XVIII The preceding examples are repeated with a plastic sheeting of polyester which is provided with a release coating before metallization. EXAMPLE XIX Example I is repeated with the plastic sheeting being subjected to corona treatment before metallization. EXAMPLE XX " . The preceding examples are repeated with a metallic thickness in the range from about 100 to 500 angstroms. EXAMPLE XXI The preceding examples are repeated with a metallic thickness having a resistance in the range from about 1/2 ohm per square to about 5 ohms per square, with 2 ohms per square being preferred. EXAMPLE XXII The preceding examples are repeated with the _thermo- plastic layer being selected from the class consisting of styrenes, styrene-polyolefin mixtures, acrylics, poly- amides, nitrostyrenes, vinyl acetates and copolymers, including ethylene vinyl acetate, vinyl chlorides, and plasticized nitrocelluloses or mixtures. EXAMPLE XXIII The preceding examples are repeated with the pre¬ liminary coating of the paper sheeting being made uni¬ formly on opposed surfaces. EXAMPLE XXIV The preceding examples are repeated with the com¬ posite of the coated paper sheeting and the metallized plastic sheeting being heated in the range from about 230°F to about 275°F., with 255°F being preferred. EXAMPLE XXV The preceding examples are repeated with a force applied at the nip of two contacting rollers in the range from about 400 to about 1000 pounds per linear inch, with a force of 600 pounds per linear inch being preferred. While various aspects of the invention have been set forth by the drawings and the specification, it is to be understood that the foregoing detailed description is for illustration only and that various changes in parts, as well as the substitution of equivalent con¬ stituents for those shown and described, may be made without departing from the spirit and scope of the inven¬ tion as set forth In the appended claims.

Claims: 2 ~ — WE CLAIM; 1. The method of metallizing a support member which comprises the steps of: (1) providing a support member; (2) providing a sheet with a metallic layer thereon; (3) forming a composite of the support member and the metallized sheet, with a thermoplastic layer there¬ between facing said metallic layer; (4) rendering said thermoplastic layer flowable; and (5) cooling said composite and stripping said sheet he.r.e from to leave said support member with said metallic layer adhered thereto by said thermoplastic layer. 2. The method of claim 1 wherein said thermoplastic layer is applied to said metallized sheet before said com¬ posite is formed. 3. The method of claim 1 wherein said sheet is re- metallized on opposite surfaces thereof, and said composite includes a second support member with a second thermoplastic layer facing the opposite surface of the metallized sheet. 4. The method of any preceding claim wherein said sheet is of plastic. 5. The method of any preceding claim wherein a release layer is provided between each metallic layer and said sheet. 6. The method of claim 5 wherein said release layer is selected from the class of natural waxes including Ouricury, Carnauba, Condelilla, Esparto, Sugar Cane, Montan, Ozocerite; synthetic waxes made by purifying Montan was and synthetic paraffin wax, microwax characterized by a microcrystalllne structure and wax-like materials Includ¬ ing melatin salts of fatty acids of at least eleven carbon atoms, Including stearates, oleates or linoleates of zinc, calcium, barium, magnesium, aluminum and zirconium. 7. The method of any preceding claim wherein said theremoplastic layer is a water-based adhesive. 8. The method of any preceding claim wherein the plastic sheet is remetallized and reused for the metal¬ lization of other support members. 9. The method of claim 8 wherein the number of reuses of said plastic sheet is proportional to the thickness thereof. 10. The method of claim 9 wherein a reuse of said plastic sheet is permitted for each 0.1 mil thickness thereof.

Inventors: CLOUGH PHILIP J, HUBBARD ROSWELL E, MCDERMOTT JOHN F, MIEKKA RICHARD G, CLOUGH, PHILIP, J., HUBBARD, ROSWELL, E., MCDERMOTT, JOHN, F., MIEKKA, RICHARD, G.
Applicants: DENNISON MFG CO, DENNISON MANUFACTURING COMPANY
Application year: 1982
Main classification: B44C1
IPC codes: B32B15, B32B37, B44C1, C23C14, D21H19, H05K3