US 3888711 A
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United States Patent Breitner June 10, 1975 METHOD OF APPLYING METAL  References Cited FILAMENTS T9 SURFACES UNITED STATES PATENTS  Inventor: Wilhelm Breitner, Bopser-strasse 2,439,892 4/1968 l-luck 219 529 Stuttgart, Germany 3,472,289 10/1969 Webber et a1 66/202 I 3,484,584 12/1969 Shaw, Jr. 219/203 [221 Flled- 1973 3,506,526 4/1969 Toyooka 161/93  Appl. No.: 392,247
Primary Examiner-George F. Lesmes Related Apphcauon Data Assistant ExaminerS. S. Silverman  Continuation of Ser. No. 154,586, June 18, 1971,
 ABSTRACT  Foreign Application Priority Data Method of applying metal filaments to a surface com- June 19, 1970 Germany 2030204 pris forming a network composed of metal filaments entwined with non-conducting thermoplastic fila-  US. Cl. 156/93; 156/106; 156/148; ments, stabilizing the network by bonding the fila- 156/177; 156/179; 161/5; 161/50; 161/89; ments at their junctions to form a self-supporting ele- 161/91; 161/92; 161/93; 161/170; 219/203; ment and fusing the element as a whole with a plastic 219/529; 264/104 sheet which is then applied to a surface.  Int. Cl B32b 17/04; B32b 17/10  Field of Search 264/104; 161/DlG. 4, 88,
9 Claims, 5 Drawing Figures 1 METHOD OF APPLYING METAL FILAMENTS TO SURFACES This application is a continuation of my copending application Ser. No. 154,586, filed June 18, 1971 now abandoned.
The present invention relates to a method for applying metal filaments, metal wires or the like to surfaces.
Laminated glass panels are known which comprise two sheets of glass and an intermediate layer of a sheet material such as polyvinyl butyral, PVC, polyethylene, etc., in which the sheet material contains a system of electric conductors, in form of thin metal filaments.
This type of panel is used for heated windows for automobiles, aircraft, apartments, deep-freezing chests or the like, to prevent the formation of ice or frost. Another application of panels of this type are the so-called alarm glasses, which are used for panelling shop windows, show cases or the like. When the glass is broken, for instance in case of a burglary, the current-carrying thin metal wire is cut, thus interrupting the electric circuit in order to start an alarm signal. Finally, it is also possible to arrange electric conductor systems in or on glasses or other surfaces to provide electric shielding, or else to be used as receiving or sending antennas. The invention to be subsequently described relates to all of the above-mentioned embodiments and applications of electric conductor systems arranged in or on a surface. The known methods for embedding or applying thin wires onto flat, particularly transparent, bodies have proven to be complicated, labor consuming and, consequently, expensive. A known method of this type consists in rolling wires, stretched in straight lines or laid out in wavy form, into a plastic sheet. Hitherto known methods only permitted the use of wave forms of the type of the so-called sine wave form, which, however, are so familiar to the human eye that the eye is involuntarily distracted and hampered while looking through the glass.
Therefore, one object of the invention is to apply electric conductor systems to surface-bodies in a simpler way than by means of the hereto known methods, particularly in such a manner that essentially any desired configurations of the single current conductors can be accomplished. The invention preferably relates to the manufacture of heated glass sheets.
Another object of the invention is to mechanically prefabricate the heating conductor system as an independent structure, or element, with the purpose of permitting economical large-scale production, and particularly in such a manner that the prefabricated heating conductor system canbe embedded without excessive manual labor as a separate layer in a glass-plastic laminated structure, or can be inserted into the plastic sheet during the sheet manufacture, or be applied to any other surface, for example a plate, by means of an adhesive.
To realize these objects, the method according to the invention comprises the steps of combining flexible electric conductors, such as metal filaments, with an electrically insulating support structure to form a surface-element, and applying this element is form of a layer to the surface, whereby the support structure preferably comprises filaments made of insulating material which is intermingled, knitted, stitched, stapled or otherwise entwined with the metal filaments to form the surface-element.
Preferably, the metal filaments are'connected with main conductors at the edges of the surface-element, which can be accomplished by knitting, entwining, twisting or the like.
When manufacturing a heating conductor system which is arranged between two glass sheets it is convenient that a support structure, such as a network, consisting of thermoplastic filaments be embedded by fusion in a thermoplastic sheet, together with the simultaneously knitted metal filaments, and that this plastic sheet be integrelly fixed to a glass sheet.
Further features, advantages and applications of the invention will be apparent from the following description in connection with the accompanying drawings, in which:
FIG. 1 shows a network, according to the invention, made of metal filaments and electrically insulating filaments, and a plastic sheet, to which it is to be attached;
FIG. 2 shows the network of FIG. 1 fused into the plastic sheet;
FIG. 3 shows a sheet of laminated glass, combined with the fused sheet of FIG. 2;
FIG. 4 shows a plastic sheet provided with a heating conductor system stitched on it according to the invention; and
FIG. 5 shows a schematic view of the stitching technique used during the manufacture of the sheet of FIG. 4.
A network I, having a so-called rib stitch is shown in the upper portion of FIG. 1 and comprises electrically insulating transparent thermoplastic and preferably fusible plastic filaments 2 intertwined with electrically conducting metal wires or metal filaments 3. The filaments 2 may also be provided with a core made of metal or of another inorganic material which is coated with a transparent fusible and insulating substance. The metal filaments 3 are generally connected, at the ends of each row, with main conductor wires 4 which are used to supply the current. The network I is preferably stabilized in its surface-configuration, for example by bonding the connecting portions of the loops by means of a slight fusion, so that the wave form of the single metal filaments 3 will be retained.
Network 1 is applied to a sheet 5 of preferably the same transparent thermoplastic material as the filaments 2 such as polyvinyl butyral, PVC or polyethylene.
After placing the network 1 onto sheet 5 the filaments 2 of the network are fused (or bonded) with the sheet 5, so that they become invisible. Simultaneously, the metal filaments 3 are combined with sheet 5 as is shown in FIG. 2. The fusion of the network with sheet 5 can be accomplished, for example, by means of heated rolls, whereby the network and the sheet are fed under pressure between two of such rolls. Optionally, a cover sheet can be laid on top of the network before the operation of hot rolling. The bottom sheet, the
cover sheet, and the network arranged between them result in a solid laminated structure.
The transparent sheet 5, shown in FIG. 2, including the metal filaments 3 embedded in their predetermined and stabilized wave form, can be applied to the front or rear surface of a pane of glass of an automobile, provided it is appropriately shaped to fit. By connecting the main conductors 4 with a current source, the sheet and the pane may be heated, thus preventing the formation of frost or ice.
FIG. 3 shows a heatable sheet of laminated glass manufactured by using the element shown in FIG. 2. The sheet 5, containing the metal filaments 3, is inserted between two glass sheets 6, such as prestressed glass (so-called safety glass). By heating and slightly melting the surface of sheet 5, and under simultaneous compression, a solid bond is achieved between sheet and the glass sheets 6. If the main conductors 4 are connected to a current source, the sheet of laminated glass, according to FIG. 3, can be heated.
Usually, the front and rear panes of automobiles are shaped into special characteristic forms and curvatures. The network I and the sheet 5. can be shaped during its initial stages of manufacture so that it will match with the form of the corresponding pane of the automobile, whereby the previously mentioned stabilization of the network 1 will maintain the desired form. This matching of the form of the network 1 with the pane to be heated represents a considerable advantage over known methods. Another advantageous feature consists in that, according to the invention, any kind of desired wave form of the metal filaments 3 can be chosen. This can easily be achieved by selecting corresponding textile stitches. Such stitches can be, for example, the tuck stitch or the openlap. The resulting configurations of the filament arrangement are less familiar to the eye, so that the view through glass sheets provided with such structures is not obscured.
FIGS. 4 and 5 illustrate a modified form of the invention in which the metal filaments 13 are directly stitched on a transparent thermoplastic plastic-sheet which corresponds to sheet 5 in FIGS. 1-3. Instead of stitching the filaments on the sheet, they can also be stapled or crocheted thereto. The sheet 15 may also be perforated beforehand at the stitching locations. In addition, the sheet 15 may also be replaced by a fabric, wither woven, knitted or randomly formed of transparent thermoplastic filamentary material. FIG. 5 shows that during the operation of stitching or crocheting the electrically conducting metal filament 13 may be used as the bottom thread, while the upper thread 12 consists of a transparent thermoplastic material or glass, which is subsequently fused or bonded to the sheet by heat. Alternatively, the upper thread can be the metal filament and the bottom thread plastic filament. In addition, the metal filaments can be coated with thermoplastic material. Finally, metal filaments coated with plastic can be used as upper and bottom threads.
The application of heat at the same time causes fusion of the metal filament 13 into the sheet 15. In the same manner as in FIGS. 1-3, the single metal filaments 13 are again connected at the edges of sheet 15 with main conductors 14 which supply the current. The further processing of the sheet 15 which is provided with the metal filaments 13 is analogous to the abovedescribed processing of the sheet 5 provided with the wires 3.
The gage of the metal filaments 3 or 13, used according to the invention, depends upon the amount of electric current which will flow through the metal filaments. If for this reason or due to a decrease in visibility it is necessary to use especially fine wires, either partially or wholly, which might break, during the operations of knitting, sewing, connecting netting, etc., it is possible to coat the thin metal filaments with an insulating plastic jacket, which is as transparent as possible, or with a glass coating (glass filaments, or glass film),
which later will invisibly fuse or combine with the material of either sheet 5 or 15. Preferably, the coating of the metal filaments should have the same index of refraction as the surrounding material of the sheet or of the plate. The coating may also consist of the same material as the sheets 5 or 15.
If the electric conductor system which is to be applied to the surface of a body solely to provide heat. or to serve for shielding electric fields, the network 1 may be manufactured entirely of metal filaments, which can be combined in any desired manner to be subsequently fused into a plastic sheet.
A further advantage of the invention resides in the fact that, by selecting corresponding wave forms, patterns may be produced which can be exactly adapted to the conditions of each case, with respect to the electric heating capacity to be achieved, because a practically unlimited variation in the wire length per course is possible. In the presently known art of manufacturing heating panels, the lack of such an additional variable represents a considerable drawback which results in the fact that not every desired shape can be produced which will also produce the desired heating capacity. In addition, according to the invention, it is possible to arrange the metal filaments in a closer manner than heretofore, so that a more concentrated conductor arrangement per unit of surface area can be obtained. Again, this results in the advantage of a smaller specific heat energy per conductor in the heating panel.
The network 1, shown in FIG. 1, or the like, used according to the invention, can be economically manufactured, in any desired width, on machines which are known and which permit the desired form and size of the stitches to be achieved. The network or the like can be rolled up for transport to the site of processing, in which case a paper sheet can be used as a temporary protective separator layer. The stabilization of the network, which is preferably accomplished before being rolled up, may be simply achieved by a short heating process during which the plastic filaments 2 are fixed to the metal filaments 3 by self-bonding at the junctions of the loops. The filaments 2 can also consist of inorganic materials. In this case, however, these filaments should be provided with a thermoplastic coating to permit the stabilization to be accomplished. This same effect can also be attained if the electrically conducting metal filament is provided with a thermoplastic coating or is twisted with, or surrounded by, a plastic filament.
The metal filament 3, or 13, can also be twisted with one or more filaments made of transparent organix or inorganic materials if the metal filaments are so thin that they cannot be mechanically processed, due to their low tensile strength. In this case the material used for the secondary filaments is intended to increase the tensile strength.
In most cases, the electric conductor systems embedded in laminated glasses or generally applied to surfaces are connected in parallel, in order to accomplish the objects mentioned above. However, it is also possible to connect the metal filaments 3, or 13, in series, which can be done by applying suitable knitting or entwining techniques. In case the single metal filaments 3, or 13, are connected in parallel it is convenient to knit, sew, entwine or set the main conductors 4, or 14, at the lateral edges and, eventually, to conform them as marginal wire. This also represents a considerable advantage with respect to conventional methods which require the main conductor to be applied as special metal strips in a labor consuming process.
According to the invention, predetermined surface patterns of the conductor systems, providing variable area concentration of the metal filaments, can be obtained by means of a programmed control of the knitting, entwining or stitching machines. These patterns can either be connected in a series, or parallel system, or combinations of the two.
The separation between the courses of current conducting filaments 3 in FIGS. 1-3 can also be increased by interposing more than one course of insulating filament 2. On the other hand, two or more current conducting courses can be arranged side-by-side, whereby one or more electrically insulating courses can follow a group of such conducting courses.
Additionally, a variably directioned current flow can be obtained by using metal filaments of variable conductivity, which represents a considerable advantage in the form of a surface-resistance if a network or the like is used which consists only of metal filaments. In FIG. 1 the filaments 2 would consist, in this case, of a metal with a smaller conductivity than the filaments 3, resulting in a variation in the heating capacity of successive areas of the surface.
1. A method for producing a transparent glass sheet of a predetermined shape having an open transparent network of metallic filaments combined therewith, comprising the steps:
a. intertwining a plurality of metallic filaments in a transparent wavy pattern with electrically insulating fusible filaments by a technique other than weaving;
b. connecting said metallic filaments with a main electrical conductor;
c. stabilizing the metallic and insulating filaments by joining them together by means of a slight fusion of the insulating filaments with the metallic filaments at their junctions to form an open transparent stabilized self-supporting network;
d. shaping the stabilized self-supporting network to match with the shape of said glass sheet;
e. applying said network to a transparent plastic sheet and fusing the network into said plastic sheet to render said insulating filaments invisible;
f. fastening said plastic sheet containing the fused network to the surface of said sheet of glass.
2. The method as defined in claim 1 in which the insulating filaments are fusible thermoplastic filaments.
3. The method as defined in claim 1 in which the insulating filaments consist of inorganic materials, especially glass, and are provided with a thermoplastic coatmg.
4. The method as defined in claim 1 in which the metallic filaments are provided with a thermoplastic or glass coating.
5. The method as defined in claim 4 which includes the steps of employing metallic filaments having different conductivities, and arranging said filaments to define areas in the network having differing heating capacities.
6. The method as defined in claim 4 which includes the steps of knitting a course of electrically insulating filament with at least one course of metallic filament to form said network.
7. The method as defined in claim 4 which includes the steps of stitching the metallic and insulating filaments to a supporting sheet to form said network.
8. The method as defined in claim 7 which includes the steps of employing a plastic supporting sheet and perforating said sheet at spaced intervals for said stitchmg.
9. The method as defined in claim 7 which includes the steps of stitching the metallic filaments to a plastic sheet and applying the plastic sheet including the filaments to a surface.