MXPA00007577A

MXPA00007577A - Heatable mirror, method for producing a heat conductive layer, and the use thereof

Info

Publication number: MXPA00007577A
Application number: MXPA/A/2000/007577A
Authority: MX
Inventors: David Macher; Heinz Zorn; Johann Stark
Original assignee: Magna Reflex Holding Gmbh
Priority date: 1998-02-06
Filing date: 2000-08-02
Publication date: 2002-05-09

Abstract

The invention relates to a heatable mirror with a transparent flat element comprised of a substrate (5) made of an inorganic material, at least one reflective layer, and at least one heat conductive layer. The heat conductive layer is deposited on the substrate and/or on the reflective layer and contains contact elements. The heat conductive layer is formed by conductive particles which are at least partially embedded in the surface of the substrate and/or of the reflective layer (9) and which have an average diameter ranging from 3 to 100&mgr;m. In addition, the heat conductive layer is configured in the form of paths or such that it is completely flat. In the path design, the non-conductive area is an insulating layer (17) which is situated between the paths.

Description

MIRROR ABLE TO BE HEATED AND PROCESSED TO PRODUCE A HEAT DRYING LAYER, AS WELL AS ITS UTILIZATION The invention relates to a mirror capable of being heated having a specially designed heat conduction layer made from conductive particles, a process for the application of heat conduction layers in substrates and the use of this process to produce mirrors. able to be heated.

Mirrors capable of being heated are known to have a heat conduction layer made of a conductive material.

Thus, in US Patent 3 686 437 a mirror capable of being heated is described in which a heat conduction layer has been applied to a glass substrate in vacuum or by electron deposition. This North American Patent proposes the use of a nickel-chromium alloy as the heat conduction layer.

The disadvantage of this mirror is that in the first place, the technologies for the application of the heat conduction layer are very complex. As described in the North American Patent, the application of the nickel-chromium alloy must be carried out either in vacuum or using an electron deposition process. Both stages of the process are very REF .: 122080 complex and very expensive for mass production. Furthermore, it has been shown that a mirror of this type obviously does not possess an adequate heat capacity due to the very thin single layers. This means that the period of time to keep a mirror free of condensation is very long. It is also not possible to use mirrors of this type to heat certain areas specifically with more force than others, which in many cases is required due to the construction of the mirror.

The object of the present invention is therefore to propose a mirror capable of being heated, whose heat conduction layer allows a high heat capacity and any arrangement design of the heat conduction layer. The object of the invention is also to provide a cost-effective and simple process for mass production, whereby a heat conduction layer can be applied to a substrate.

With respect to the mirror capable of being heated, the objective is achieved by means of the features of claim 1 of the patent and with respect to the average process of the characteristics of patent claim 17. The other claims show further advantageous developments of the solution according to the invention.

It is therefore proposed, in accordance with the invention, that the heat conduction layer be formed by conductive particles embedded at least partially on the surface of the substrate and / or the reflection layer. It is therefore essential for the mirror capable of being heated of the invention that the particles have an average diameter of 3 to 100 μm. Figures 4 to 6 show images of the scanning electron microscope with amplification of 30, 100 and 1000 times, from which the formation of particles can be seen. Consequently, the heat conduction layer has a "rough surface". Figure 6 shows in particular that the particles have obviously only changed insignificantly by the application process. Figures 4 to 6 show that the particles have penetrated pareially within the surface of the substrate, now a mirror. Therefore, the adhe of the particles to the substrate is essentially produced by the penetration of the particles into the surface of the substrate. Of course, the sintering of some particles with others and with the surface also takes place. It is important for the mirror capable of being heated that it has the heat conduction layer as described above, that a certain roughness be maintained, ie of an average particle diameter of 3 to ICO μm, and that therefore a Conductive cohe layer. In this way, the heat conduction layer of the mirror of the invention differs from those which until now are known from the state of the art, which have conventionally been applied via electronic deposition processes or evaporation methods. In all these cases, a finely divided homogenous conduction layer consequently has the disadvantages of the state of the art mentioned in the introduction.

The particles by themselves are preferably selected from the metals Al, Zn, Sn, Cu, Ni and / or their alloys. It is preferred more particularly for the mirror capable of being heated of the invention if the particles consist of aluminum and / or an aluminum alloy having at least 96% aluminum. A further preferred embodiment of the mirror of the invention is characterized in that the substrate for the mirror capable of being heated is glass. The material formed by glass and aluminum and / or aluminum alloy in particular as particles has proved to be particularly superior in its properties with respect to mechanical adhesion and electrical heat capacity. For the mirror of the invention, the heat conducting layer can designed to be on the entire surface or in the form of stripes. For the mode in which a heat conduction layer in the form of strips is present, it is therefore important that the regions between the heat conduction strips consist of an insulating separation layer. This insulating separation layer is preferably a thin film having a width of 0.2 to 1 mm. The minimum width is important because otherwise bridging may occur during spraying. The separation layer is produced from a formulation containing resins and solvents. The preferred resins are lacquer, gum arabic or rosin. The insulating separation layer may therefore contain additional ditivs, as are known per se from the state of the art. This separation layer is applied in the required form by spreading, spraying or brushing.

It has also been found to be advantageous] if the layer thickness of the heat conducting layer falls within the range of 10 μm to 100 μm, preferably in the range of 40 to 60 μm. A particular advantage of the mirror capable of being heated of the invention is that the layer thickness of the heat conduction layer can be selected to be different so as to obtain an increased heat capacity at particularly critical points in the area of the mirror, in such a way that condensation is also prevented there. For the case where strip-like heat conduction layers are used, the width of the heat conduction layers is from 2 to 20 mm. Also, the layer width of the heat conduction layer can be selected to correspond to the width such that a wider range is selected at particularly critical points where dehumidification of the mirror is only possible with difficulty. Of course, the invention also includes all the modalities in which both the layer thickness of the layer and the width of the strip vary.

The heat conduction layer of the mirror capable! The invention also shows a considerable improvement compared to the state of the art in addition to the advantages described above. The expert has also been shown in a manner that could not be foreseen, namely that the heat conduction layer as defined in claim 1 of the patent may be provided with a polymer coating that serves as chip protection, for thermal and electrical insulation as well as adhesive to fix the structure of the mirror.

Until now, it had been specifically conventional in the state of the art to apply a protection against chips that appeared in the form of adhesive films or sheets and that had to be produced in a separate work stage and subsequently adhered to the mirror. In the mirror of the invention it is now possible to apply a polymer coating in a very simple manner, for example, by spraying, particularly due to the surface formed by the particles. It has therefore been proven to be particularly advantageous if the coverage of the selected polymer is such as one that consists of a modified self-curing silane polymer. This now has the advantage that the mirror is covered on the entire surface with the polymer on the side where the heat conduction layer is applied in a single working step and that simple air curing then takes place. Modified silane alkyd resin systems are preferably used as polymers of this type. They are particularly characterized in that they are single-component systems and that in humid air they give rise to a cross-link for, give a flexible product. An additional advantage of such coverings is that this cover acts as a vapor barrier and is UV stable and functions as a sealing material with very good handling.

In the mirror capable of being heated of the invention, it is prevented, as is already known from the state of the art, that contact points are present to contact a voltage source. Consequently, these contact points are preferably designed to be connected to the heat conduction layer via an additional metal layer. This additional layer of metal is preferably selected from the metals Zn and / or Sn. This additional layer of metal consequently has a thickness of 50 to 100 μm.

The known layers of the state of the art can be used as the reflection layer for the mirror. Examples of these are dichroic layers or layers of chromium or silver.

The invention relates to a process for producing a heat conduction layer made of electrically conductive particles on a substrate. The process is characterized, according to the invention, because the electrically conductive material is supplied to a heat production device at a temperature of > 5,000 ° K. The conductive particles that are then produced are transported by air to the surface of the substrate. Therefore, it is important in the process of the invention that this application process be conducted in the atmosphere of the environment, that is in ambient air. Hence, the construction of this process is simple and profitable.

It is preferable in the process of the invention if the heat is produced by means of electric arc. The distance between the device and the substrate is preferably 5 to 50 cm, particularly preferably 12 to 25 cm. It should be emphasized in particular for the process of the invention that the particles can be transported using compressed air. As a result of this simple measure, it is now possible to influence the process by varying the pressure. The compressed air can be varied in a range of 2.8 to 7.5 atmospheres.

The process of the invention therefore allows the thickness of the layer of the applied particles to be adjusted by varying the distance of the substrate of the heat producing device and / or by varying the velocity of the particles as well as by the feed by wire and the current level of the electric arc.

The process of the invention offers a wide range of advantages. According to the invention, a separation layer must be produced in the substrate as a first stage of the process for the strip type mode. This separation layer is therefore designed with respect to its structure in such a way that during the application of the heat conduction layer the strip shape is obtained which is required, for example, serpentine or helical.

Surprisingly, it has been shown that such an insulating separation layer can be produced very simply by applying a formulation containing a resin and a solvent. It has been shown that if such an insulating layer is applied to the surface of the substrate by means of an application propella which is itself conveniently, the particles supplied to the substrate by the evaporation method at the points where the separation layer is applied. adheres to the substrate, prevents the penetration of the particles to the substrate. Then, the particles that are poured out of these regions where the separation layer is applied and only adhere, that is, penetrate the surface of the substrate at the points where the separation layer does not exist. Figures 4 to 6 now show, by way of example on a glass substrate, an applied aluminum alloy in which a separation layer is also present. Figures 4 to 6 illustrate that at the points where the separation layer has been applied by the subsequent application process, adhesion of the particles does not take place. In the example of Figures 4 to 6, a marking pen having a resin and ink formulation was used as the separation layer.

This opens a wide range of possibilities with respect to the arrangement of the heat conduction layer to be applied Consequently, using the process of the invention it is not only possible to vary the thickness and width of the band, but also the control of the band can be controlled. arrangement of the heat conduction layer to be applied specifically by means of a simple application of the separation layer to the substrate.

A crucial advantage of the invention process is that the polymer coating can be applied over the entire surface of the heat conduction layer which subsequently serves as chip protection, as thermal and electrical insulator as well as adhesive for fixing the structure of the mirror. Obviously it is possible] that the polymer coating can be applied by means of a simple process, for example by rolling, by spraying or by another conventional application process, particularly due to the roughness of the surface produced by the process of the invention which has the particle formation described above. A further advantage is that this polymer coating has an excellent adhesion I with the base, that is, with the conductive layer and / or with the separation layer. Preferably, a modified silane polymer, in particular a modified silane alkyd resin, is used as the polymer layer. The advantage of this system is that it is self-curable in air. As a result of this measure, a very simple and cost-effective application of the chip protection and optionally as an adhesive for the mirror structure is possible.

With respect to the selection of the material for the particles to be applied and for the substrates, reference is made to the above statements for the mirror capable of being heated. Accordingly, it is particularly preferred if a material that collects glass and aluminum and / or aluminum alloy is used for the particles. Therefore, for the insulating separation layer it has been proven that it is advantageous by itself if a state-of-the-art marking pen is used, for example an Eddingmarker®.

As a result of the excellent possibilities of controlling the process with respect to the thickness of the layer, the width of the strip and the arrangement, the process of the invention described above in greater detail is particularly suitable for producing layers of heat conduction for mirrors capable of to be heated in the motor vehicle industry i, as described in claims 1 to 16.

The invention is described in more detail below using Figures 1 to 7.

Figure 1 shows a mirror having a heat conduction layer designed according to the invention; Figure 2 shows the mirror, sectioned along lines II-II in Figure 1; Figure 3 shows a partial area of the mirror of the invention having a moisture sensor and power supply and a control device shown schematically; Figure 4 shows an image of the electron microscope in a 30-fold amplification of the heat conduction layer of the invention; Figure 5 shows the same heat conduction layer in a 100-fold amplification; Figure 6 shows the heat conduction layer in a 1,000-fold amplification.

By way of introduction it should be remembered that the same parts are provided with the same reference symbols or the same designations of components in the different described modes, where the exposures present in the entire description can be transferred analogously to the same parts with the same reference symbols or the same component designations. Likewise, the details of position, for example, such as superior, bottom, side, etc., selected in the description, are related to the figure that is described at that moment, and must be transferred analogously to the new position for a change of. position. In addition, the individual characteristics combinations of characteristics of the different example embodiments shown and described by themselves can be independent inventive solutions or solutions according to the invention.

In Figures 1 to 3 described together, there is shown a mirror capable of being heated 1 having a heating element 2 in an enclosure 3 for an external mirror 4, for example for motorized vehicles. It consists) of a substrate 5 made of an inorganic material, for example glass, ceramic, with a low thermal conductivity, preferably with grounded and covered surfaces 6, 7. The substrate 5 having a reflective layer 9, for example a chrome layer , it is applied, for example, on the surface 7 opposite the direction of vision according to the arrow The heating element 2 having a layer applied to at least one surface 6, 7 of the substrate 5 and / or the reflection layer 9 and made of an electrically conductive material that provides a resistance to the flow of the stream, essentially forms a fringe of conduction 10, wherein the electrically conductive material is arranged on the surface 6, 7 as a strip or. over the entire surface. The strip-like path of the driving strip 10 is helical or serpentine, the surface 7 is preferably designed to cover a large area, wherein an interruption-free path is provided for the driving strip 10 by means of a terminal position located approximately in the center of an end longitudinal edge 11 to an additional extreme position disposed immediately adjacent thereto. However, it is also possible to design the conductive strip 10 as a full-surface heating layer. The contact elements 12, 13 are arranged in the extreme positions of the driving strip 10.

The regions of the driving strips 14, 15 running immediately adjacent to each other are electrically isolated from one another by means of a separating layer 17 forming a space 16 between the regions of the driving strips 14, 15 and which are They have on the surface 6, 7 of the substrate 5. The contact elements 12, 13, whose conductors 18, 19 are passed through the casing 3 for the electrical supply of the conduction strip 10, are connected to be electrically conductive by means of direct welding with the material 1 of the driving strip 10 and consisting of a layer of zinc and / or tin applied to the driving strip 10.

The heating element 2 is provided with a cover layer 21 of an electrically non-conductive material on the rear surface 20 facing the substrate 5, such that the conduction strip 10 is disposed between the substrate 5 and the cover layer 21. Accordingly, it is preferred that the cover layer 21 be formed by a self-curing polymer cover, for example of a modified silane polymer. The mirror 1 is adhered to the mirror structure 22 using the cover layer 21 and is maintained in the envelope 3 by means of the support 23.

The conduction strip 10 running between the separation layer 17 is formed by particles 24 made of an electrically conductive material applied to adhere to the surface 7 by means of an electric maple process. The particles 24 of Al, Zn, Sn, Cu, Ni and / or their alloys are preferably used, wherein the conduction strip 10 for converting the current energy to heat energy for supplying a low voltage main conductor has a preset resistance value of about 2 O to 20 O, preferably 8 O. The temperature of the conduction band 10 exposed to the current is therefore a maximum of 100 ° C. However, the electrically conductive material or the driving strip 10 can also be designed to be transparent, for example, as a rigid glass covering, which is preferably arranged on a front side of the substrate 5 facing the direction of vision-arrow 8 , in particular on the front side of the mirror capable of being heated 1 confronting the direction of vision-arrow 8.

To achieve different temperature zones distributed over the substrate 5, the heating element 2 is provided with a continuously changing layer thickness 25, with which, for a predetermined strip width 26 of the cross section of the conductor and therefore the resistance of the conductor that opposes the flow of the current, it is possible to adapt to the requirements for the heat capacity in different areas of the mirror 1.i However, even the heating voltages between the adjacent regions in the substrate 5 are effectively prevented by the design of the heating element 2 of the invention having short response times, this is subsequently achieved due to the small amount of mass to be heated Of course, the mirror 1 of the invention can be used not only for the external mirror 4 shown, but also for all current external conventional mirrors, such as, for example, for electrically adjustable external mirrors.

It is also possible to combine the mirror 1, composite with the heating element 2, with one or more sensors, for example heat sensors 28 or humidity sensors 29, which can be arranged on the surface 7 or on a surface 6 opposite the stripe conduit 10 of a surface element preferably formed by the substrate 5 and optionally the reflection layer 9.

A possible design of the humidity sensor 29 consists, for example in the design of a resistive measuring area, as shown in Figure 3. The sensor can be formed by a region that is part of the electrically conductive material arranged to be isolated from the driving strip 10, in particular of the heating layer. However, the electrically conductive contact surfaces 30, 31, due for example to a chrome cover, can also be applied to the surface 6 or 7 in a region of the edge 27 of the mirror 1 or in the region of an extreme longitudinal edge 11 of the substrate 5, and which are isolated from one another, for example, by means of a separation layer 17. An electrical voltage is applied to the contact surfaces 30, 31 via the conductors 32, 33. If moisture is formed in the surface 6, as occurs during condensation or freezing, there is a current flow due to the bridging of the separation layer 17 and, the signal that is derived therefrom can be used as an activation signal to activate the heating element 2 in a corresponding supply and / or control device 34.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, the content of the following is claimed as property.

Claims

A mirror capable of being heated having a transparent surface element made from a substrate of inorganic material and at least one reflection layer as well as at least one heat conduction layer applied to the substrate and / or reflection layer and which has contact elements, characterized in that the heat conduction layer is formed by conductive particles having an average diameter of 3 to 100 μm at least partially embedded in the surface of the substrate and / or the reflection layer, the particles being selected from the metals Al, Zn, Sn, Cu, Ni, | and / or its alloys, and whose heat conduction layer is designed to be in the entirety of the. surface or in the form of fringes, wherein the non-conductive region for the fringe-shaped mode is an insulating separation layer between the fringes.
A mirror capable of being heated according to claim 1, characterized in that a polymer coating is applied to the entire surface of the heat conducting layer as a covering layer, which serves as a protection against chips and as an insulator.
A mirror capable of being heated according to claim 1 or 2, characterized in that the polymer coating is a modified silane polymer which is cured with air.
A mirror capable of being heated according to at least one of claims 1 to 3, characterized in that the contact elements are connected to the heat conduction layer via a metal layer.
A mirror capable of being heated according to claim 1, characterized in that the particles are aluminum and / or an aluminum alloy that tlene at least 96% aluminum.
A mirror capable of being heated according to one of claims 1 to 5, characterized in that the substrate is glass.
A mirror capable of being heated according to at least one of claims 1 to 6, characterized in that the insulating separation layer is a film that has been formed from a formulation containing resin, solvent and optionally additives.
A mirror capable of being heated according to claim 7, characterized in that the resin is a natural resin, such as lacquer, gum arabic, or rosin.
9. A mirror capable of being heated according to claim 7 or 8, characterized in that the additives are colorants.
10. A mirror capable of being heated according to at least one of claims 1 to 9, characterized in that the layer thickness of the heat conducting layer falls within the range of 10 to 100 μm.
11. A mirror capable of being heated according to at least one of claims 1 to 10, characterized in that the metal layer for the contact points is selected from Zn, Sn and / or Ag.
12. A mirror capable of being heated according to at least one of claims 1 to 11, characterized in that the heat conduction layer is helical or serpentine.
. A mirror capable of being heated according to claim 12, characterized in that the thickness of the layer and / or width of the shape of the strip of the heat conduction layer is selected as a function of the heat capacity required in the element of particular surface.
. A mirror capable of being heated according to claim 13, characterized in that the width of the shape of the strip of the heat conduction strips fall within the range of 2 to 20 mm.
. A mirror capable of being heated in accordance with at least one of claims 1 to 14, characterized in that a sensor, such as for example a humidity and / or heat sensor connected by a conductor to a supply and / or device control, is arranged on the surface and / or on a surface of the surface element opposite the driving strips.
. A process for producing a heat conduction layer made from electrically conductive particles on a substrate, characterized in that the electrically conductive material selected from the metals Al, Zn, Ni, Sn, Cu and / or their alloys is supplied to a device of production of aalor in the form of wire and then it is exposed to a temperature > 5,000 ° K, and the particles produced are transported in air to the surface of the substrate.
. A process according to claim 16, characterized in that the heat is produced by means of an electric arc and the distance between the device and the substrate falls within the range of 50, preferably between 12 and 25 cm.
. A process according to claim 16 or 17, characterized in that the particles are transported by means of compressed air in the range of 2.8¡ to 7.5 atmospheres.
A process according to at least one of claims 16 to 18, characterized in that the thickness of the layer of the applied particles is adjusted by varying the distance of the substrate of the heat producing device and / or by vailing the compressed air for the particles and / or the wire feed speed to the heat production device.
. A process according to at least one of claims 16 to 19, characterized in that before applying the heat conduction layer to some regions of the substrate, an insulating separation layer is applied which prevents the penetration of the particles that are deposit on the surface of the substrate.
. A process according to claim 20, characterized in that the insulating separation layer is applied in such a way that a layer is produced in the form of fringes, in particular helical or serpentine.
A process according to at least one of claims 16 to 21, characterized in that a covering layer in the form of a plymic covering is applied on the entire surface of the heat conduction panel as protection against chips and as insulation.
A process according to claim 22, characterized in that the polymer coating is sprayed or applied by rolling and consists of a modified self-healing silane polymer.
24. A process according to at least one of claims 16 to 23, characterized in that * the substrate is glass.
25. A process according to at least one of claims 16 to 24, characterized in that the insulating separation layer is formed of a formulation containing resin
26. A process according to at least one of claims 16 to 25, characterized in that the heat conduction layer is used as a mirror capable of being heated, in particular for mirrors of motor vehicles.