HU182747B - Method for producing electrically heatable glass panes and ceramic materials - Google Patents

Abstract

The invention relates to a method for producing heatable glass and ceramic materials, in particular for ice and fog-free panes in motor vehicles, rail vehicles, ships u.a. as well as for ceramic heater warm holder plates and the like. The aim of the invention is to provide an economically effective method. The invention solves the problem of reducing the measuring equipment and labor force requirements, the range of resistance values and thus the reject rate, as well as prolonging the screen printing stencil service life, the ability to adapt to higher electrically-conductive glass panes with higher final voltage values and continuous production with a high degree of automation , The essence of the invention consists in the deliberate use of screen printing stencils with mesh crossing layers and in that after firing without prior measurement of the initial resistance in a Vorgalvanisierung the reinforcement is carried out under uniform conditions that after the Vorgalvanisieren the resistance with subsequent assignment of the glass or ceramic Body to uniform Galvanisierungsprogramme granting groups of these items with almost the same resistances measured and thus the use of galvanizing machines is possible. If the resistance value is too low, the layer is selectively anodically removed until the setpoint is reached. The corrosion protection layer is applied under uniform conditions, in particular with a constant exposure time, electroplatively or chemically reductively.

Description

The present invention relates to a process for making electrically heated glass panes and ceramic materials, in particular to ice and antifog windows of motor vehicles and the like, by screen printing electrically conductive metallic silver-containing narrow resistance strips onto the glass pan, by burning the strips and by burning them. Enhance.

The essence of the process according to the invention is the use of a screen printing template with a cross-linked layer, without prior measurement of the output resistance after firing, and under uniform conditions during pre-galvanizing.

According to a preferred embodiment of the invention, after the pre-galvanization, the resistance value above the final value is between 13 and 17% in the case of a rear window motor vehicle with a 12 V connection voltage.

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The present invention relates to a process for the production of electrically heated glass panes and ceramic materials, in particular for ice and antifreeze panes of motor vehicles, track vehicles, ships and the like.

Are there methods for producing heated glass panes, especially for rear windows of motor vehicles? in which, by screen printing, at least one side of the board is placed, at a distance of a few cm, parallel resistance paws of width of 0,11,0 mm and of desired length; with a collector rail on each side, approximately 10 mm wide. Resistance foils generated by the addition of metal powder, preferably silver powder, and low temperature melting glassfibers to organic binders are burnt after the imprint has dried during the bending and / or stiffening process of the glass pane. The so-called "blank" resistor strips are galvanically and / or chemically reductively coupled to the desired electrical conductivity with defined output resistors. The electrical rails are finally placed on the rails. Do metal reinforcements that have been galvanically or electrically dripped onto burnt resistance foals need to have a high uniformity? to ensure that electrical output in series production only fluctuates within narrow limits.

In addition, different conductivity values for each resistance foil, as well as reductions and thus local firing, should be avoided in order to achieve uniform heating of the glass pane. The unevenness of the individual resistance foals and the tolerances of the electrical conductivity associated with it are due in particular to screen printing. In the conventional screen printing process, to produce heated glass panes from a single-layer safety glass, the so-called direct photo template, the screen printing fabric is coated with a photosensitive copying solution, such as polyvinyl alcohol, and then, after illumination, the layer hardens. and disappears from unlit places.

Resistance foals are not straight in a table that is not curved to the lateral limit, because different angles are formed at different points between the resistance foals and the webs of the screen printing template. At these points, the lateral delimitation of the resistance foals jumps to a certain extent from one fiber to the adjacent one, resulting in a non-uniform stair formation that can be traced back to the aforementioned angles, associated with a latitude change. Forced in conjunction with screen printing technology, this effect leads to unwanted narrowing and widening of the resistance foals and is therefore a major cause of the dispersion of electrical resistors. It has been suggested that the screen printing template should be designed with diagonal web tension so that the resistance foils and webs form angles between 14 and 7θ, which deliberately delivers more uniformity through sawtooth confinement, resulting in a smoother galvanic bonding and spreading.

To further reduce the variance in resistance values, it was also suggested that the resistance values of the raw materials should be determined prior to electroplating and should be grouped according to their respective resistances. Then they get it together

-2182,747 discs having approximately the same total resistance to be treated under the same conditions during subsequent galvanization.

The total resistance of the raw parts is measured by the galvanizing time and / or by galvanizing! is used to control current. It has also been proposed to automate this process by measuring the galvanizing current that increases with increasing metal deposition at constant galvanizing voltage and automatically switching off the galvanizing when it reaches one of the desired end resistances.

It is also known to electroplate multiple glass panes with different output resistances by switching on the respective resistances to the respective disc circuit so that the same galvanizing time can be achieved for each disc.

In addition, it is known that after each resistance pin is fired, the current flow in each pin can be controlled by conducting current through the conductor system, and that any electromagnetic field formed around their resistors can be scanned with an inductive probe. Boards with faulty resistances, such as the finest hairline cracks that lead to the interruption of the measuring current in the respective pin, are thus sorted out before galvanizing.

In the known process variants, during the first electroplating, preferably during the copper plating of the fused guide system, an endurance value close to the target value is sought. Subsequently, the total resistance value of the copper-coated resistors is repeatedly measured and, depending on the value being measured, a corrosion protection layer is deposited in the second galvanizing treatment step until the desired final resistance is achieved.

At present, the production of electrically heated glass panes with a resistance value within narrow limits is very uneconomical and involves a great deal of measuring equipment and time.

Despite the heavy technical effort, the guiding systems of the iveit and straight-line resistance stubs, which always end up in the collector rail, have quite different electrical conductivity after injection. These differences cannot be significantly reduced by the diagonal tensioning of the screen printing frame under the manufacturing conditions to achieve an angular area between 14 and 76® between the resistance stitches and the weft direction and to achieve a more even galvanic separation of the lateral fins and teeth. it cannot be avoided at all. In addition, diagonal stretching necessitates tissue loop distortion due to uneven surface tension of the tissue, resulting in uncontrollable line widening of the imprint.

In addition, compliance with the aforementioned angle range for diffracted resistance foals, even when changing templates, is problematic. In addition, under manufacturing conditions, the significant reduction in template stall time for diagonal strain should be avoided.

A further defect of the described process variants is the necessary selection of defective raw parts prior to galvanization based on the control measurements of each resistance foal and the determined output resistances of the guide system. In this way, boards whose resistance lines each have the smallest interruptions in the nanometer range, such as hairline cracks and the like, are often sorted out.

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It is known; The methods further require the simultaneous measurement of the resistivity and the subsequent categorization according to the resistivity values after the first galvanic or chemically separated metal layer is applied to determine the galvanizing conditions during the application of the corrosion barrier according to the magnitude of the values found. The standard deviation of the resistance values can thus be kept lower; however, the expenditure required is extremely high. This method prevents continuous production for control purposes due to permanent interruptions.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome these disadvantages and to provide an economically more efficient process for the manufacture of electrically heated glass panes.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the known process for the manufacture of electrically heated glass panes by reducing the cost of measuring and labor, reducing the variation in resistance, reducing strain on resistance foils, i.e., reducing waste time, it must be capable of being applied continuously to suit the higher connection values of the electrically heated glass panes to be manufactured and to a high degree of automation.

According to a first embodiment of the invention, a slurry of low-melting frit and screen printing oil of metal powder, preferably silver, is known to be applied to the flat glass panes after the screen printing process is carried out using the known screen printing process but deliberately using screen printing templates with cross-linked layers. / or burned during the stiffening process.

By using screen printing templates known in the art having cross-linked layers, smooth fencing of the resistance foils is achieved, even for strongly bent foils, regardless of the angle between the resistance foils and the filaments.

By deliberately avoiding the 'sawmill effect', such a screen printing template can achieve the desired length resistances without extensive sky change, which results in a significant reduction in the dispersion of the resistance values of the blanks. This advantage of cross-linked layers is particularly significant in conductive systems with very thin resistance strips. Because the use of cross-linked layers eliminates the need for diagonal tensioning of the screen printing frame, it significantly extends the template usability time. The resultant blanks, without considering the output resistances, are one in high power electrolytes under uniform galvanizing conditions. a first metal layer, for example copper, is obtained. It is desirable to determine here an exposure time which is approximately 15 percent of the resistance above the desired end resistor at the 12V connector voltage of the vehicle's rear windows. Following the first galvanization step, the guiding systems of each board are automatically weighed and grouped according to the resistance values. In the second galvanizing step, which consists of the same electrolyte system as the first, the panels divided into groups based on the measured resistance values are galvanized to a uniform resistance value in the known activation solutions, which ensures the application of a corrosion protection layer to each group. conditions. In this

-4182,747, the uniform resistance value for each board is achieved only by varying the exposure time in the second galvanizing step. Experimentally proved to be the first galvanizing! stepwise resistance values close to the desired end value, according to the invention, by deliberately using a screen printing template with cross-linked layers and bridging the cracks of the raw pieces by screen printing, are pre-galvanized under the same conditions and have only slight differences between groups. Resistance values close to the desired end value, which differ only slightly within each group and within the group, allow for some fine-tuning of the exposure times in the second galvanizing step. In this way, only a very small dispersion of the resistance values is produced.

The process according to the invention, wherein the second galvanizing! except for stepping plating! conditions are constant, allow a high degree of mechanization, and thus manufacture on a fully automated galvanizing line, whereby only the second electroplating is treated step by step by adjusting the exposure time either by programming the dryer or by switching off the time programmed galvanizing current. This allows for a much more rational production. By shortening the time of electrolysis through baths, the bottleneck in the overall process of heating glass panels is virtually eliminated.

Each glass pane, whose conductive fins are traceable in the nanometer range due to screen printing, is bridged by the galvanic layer only in the second galvanizing step, so that its resistance lies below the desired end value by guided, selective dissolution of the galvanized layer. , can be reused.

With the second embodiment of the present invention, a simple opportunity has been created to transfer the repaired process to the manufacture of high-voltage glass panes while maintaining a uniform technology.

According to the invention, conductive systems with different joint voltages burned in glass panels or chemicals can be reinforced under uniform electroplating conditions, without prior measurement of the blank, as in the first embodiment, if one or more deliberate interruptions of the collectors are used to produce the print. depending on the unit, the magnitude of the connected voltage, and the desired heating power, a corresponding output resistance is produced at the first and third galvanizing steps with a uniform exposure time galvanizing. In this way, essentially the same timing of the electroplating machines can be observed.

The interruption or interruptions of the collectors may further increase the output resistance of the guiding systems of the blank pieces, for example, by coarse granulation or higher concentration of the metal powder in the printing paste to increase the conductivity of the resistor precursors to the required value. For example, guiding systems for raw parts using coarse metal powders often are already close to or below the target value

They have a resistance value of -5182.747. Therefore, the exposure times during electroplating are too short for both the metering controller and the removal of a satisfactory corrosion protection layer. Blanks with resistance values below the required specification must also be sorted. In such cases, interruption of the collections and connection of the rails allow the wide concentration and particle size range of the metal powder to be smoothed without difficulty.

In a further embodiment of the invention, interrupts of the busbars can, of course, also be used for multi-stage switching of the heating system by the choice of bypassing one or more of these interrupts by means of switches.

The invention will now be described with reference to two embodiments thereof. It should be noted, however, that the invention is not limited to these examples, but that variations and modifications are possible within the scope of the invention, such as the use of ceramic materials instead of glass,

Example 1

Using a strainer, a suspension of fine silver powder and low temperature soluble glass frit in binder in the form of a thin resin foil is pressed onto the glass pane with two rails and after the imprint has dried, the glass plate is bent or pressed. cured. The crude product thus obtained is immediately electroplated in the precoating stage without prior determination of the output resistance using high-power electrolytes with a constant exposure time of 4.5 minutes and a current of 9 Amps for all the crude units. The electrical resistance thereafter found is 1.1, + 0.15 Ohm, and is approximately 15% above the desired end resistance of 0.9 Ohm. Due to the bridging of hairline cracks in the nanometer-wide range that can be traced back to screen printing, defective glass panes with the first galvanic layer are only marginally produced. As the experiments have shown, the output resistance of the raw material is between 4.2 and 5.2 Ohm. Only on some glass panes, the resistance foils contain hairline-cracked hairline cracks, measuring up to 23 ohms. By bridging these hair cracks in the pre-coating step, the resistance values of these boards can be reduced to the said resistance value of 1.1 + 0.15 Ohm.

Your group is preferably arranged according to a predetermined standard deviation of the resistance values to be achieved. In this example, a gradation of six groups was used for the desired elemental resistance of 0.9 + 0.06 Ohm. For each group, post-subcoating was performed with exposure times of 0.25 to 2 minutes and a current of 9 Amps at the same electrolyte system as the first stage. For all glass pane guiding systems, nickel plating was used at constant conditions without correcting the measurement, with a galvanizing current of 10 Amps and an exposure time of 4 minutes to corrosion protection and round off resistance values.

Example 2

At the heating system with a 12 V supply voltage

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The running power W shall be realized, resulting in a resistor value of 1.6 Ohm to be set. Using a conductor of 8 micron medium grain size metal particles to conduct the current, the resistance of the conductor system of the raw part is 3 to 7 ohms compared to 17 ohms obtained using a 4 micron grain size paste. Because the conductor system is dimensioned and resistance increase with a higher proportion of glass frit is difficult to calculate, the screen printing template is bridged with material covering one of the flasks in such a way that interrupting the collector results in two parallel lines 7 , 4 Ohm-May. Thus, the total resistance of the raw piece is 14.8 ohms, which is four times the previous value.

In this way, similar galvanizing conditions are created as when using a 4 micron granular paste.

Claims (4)

Patent claims 1. A process for making electrically heated glass panels and ceramic materials, in particular for ice and antifreeze heating panels for motor vehicles and the like, by screen printing electrically conductive narrow metallic silver foils onto the glass panel, by burning the foils or by with chemically reductive reinforcement, characterized in that immediately after fattening of the foals all galvanic reinforcements fall regardless of their electrical resistance, uniformly for all foals for a period of 0.5 to 2.0 minutes and uniformly for all foals At a current within the range of 5 to 20 Amps, galvanic drum pre-electroplating is known per se. 2. The method of claim 1, wherein after pre-galvanizing the glass panes are divided into groups providing a uniform galvanizing program by measuring approximately the same resistances. 3. A method according to claim 1 or 2, wherein immediately after galvanizing the group of foals having approximately the same resistance, a corrosion protection coating is applied by a final electroplating applied for a period of 1-3 peic range and uniformly 10-20 Amperes for each foal. current within the range is performed on a galvanic bath of known composition. 4. The method of claim 3, wherein, after application of the anti-corrosion coating, foils having an electrical resistance below the allowable value are corrected so that the galvanized foils are anodized in a manner known per se until the nominal electrical resistance is reached. .