DE2260039A1 - METHOD OF COATING A SUBSTANTLY FLAT SURFACE WITH A GLASS-LIKE LAYER AND OBJECT, OF WHICH A SURFACE BY THIS METHOD WITH SUCH A LAYER - Google Patents

Description

PHK.6Q62

? a / FF

GDNTHERM-DAVIt)

Father.tasssssor
: NV PHILIPS'GL0EILAMPENFA8RIEKEN

Act ·· PHI- 6062 ν · «· 7. De». 1972

"Method for covering a surface that is generally even a vitreous layer and object, one of which is a surface is coated with such a layer by this process. "

The invention relates to a method for overriding an essentially flat surface with a vitreous layer uniform thickness made by melting a glass-like particle existing layer is obtained by deposition from a suspension is attached, which consists of an organic liquid, in which a vitreous »material in finely dispersed additive - nd in absence a binder suspended. The invention also relates on an object, in particular a flat plate for a gas discharge panel for image reproduction, which is covered by this process with a glass-like layer of the same thickness.

In the published Dutch patent application 7IO42IO vcirde proposed on one at least on the surface a, among others Isolierni & teriävl existing, perforated intermediate plate for image reproduction

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insert panels to attach a layer consisting of glass-like particles, because a variety of strip-shaped conductors can be attached to the Zwieohenplatte. This is done on a solo record a suspension of glass particles sprayed with a binder and heating the plate to remove the binder. Be aware placed the ladder on the layer consisting of glass particles and the Schioht is melted 'so that the conductors are embedded in the glass layer.

However, a layer applied by spraying can be over a relatively large surface no very uniform bead obtained while the layer becomes porous during removal of the binder, which causes the sole to melt when it melts. Air inclusions arise that make the Sohioht cloudy. Such a dull Schioht can probably do so can be used to attach conductors to a perforated intermediate plate of a picture display panel, but this is less suitable for Attachment of ladders to a top plate. Also nuts with one The top and a base plate of such a panel, the conductors are partially exposed, at least on the parts opposite the openings of the intermediate plate. To fully embed the ladder, eat one The normal thickness of the vitreous layer is not particularly important.

It was proposed in an earlier application by the applicant such conductors on the insulating surface of a plate by means of to attach a thin layer of vitreous material such that the spaces between the conductors are not entirely glassy Material to be filled, Su this Zwack ausa a thin glass-like Layer with a very equal and predetermined thickness on the insulating plate, but this cannot be done without further β άίΐχ-ch spraying on or deposition take place in a known manner * ee be

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because that special measurements are taken. At the deposit • ought, for example, to ensure that the particles are in the suspension don't clump together.

Aue "of the published Dutch patent application 283,620 it is known that the agglomeration of glass particles in A suspension can be better avoided, the higher the dielectric constant the liquid is. A large dielectric constant leads to a stronger mutual repulsion of the glass particles. A disadvantage, however, is that a loose layer is formed as a result of this repelling during the deposition, so that the particles when Removing the fluid may wash away or shift whereby the thickness of the layer becomes uneven. Therefore, the electric current becomes constant brought to a value of 5i4 and 20.7, while centrifugation accelerates the deposition and the density of the Layer is enlarged.

Liquids with a dielectric constant greater than 20.7 is, are considered as isht suitable, because the particles are then repel so strongly that despite the centrifugation the obtained Layer is not dense enough. In the German patent specification 1,235,828 j it is stated as known that it consists of glass particles thin layers can be obtained by deposition from a suspension of glass powder in an organic liquid, i.e. without a binder can. A disadvantage is mentioned here that the layer when pouring or when the liquid evaporates, it becomes unequallyrajjssia. In the said German patent this is avoided by using binders be added and the excess suspension by centrifugation is removed from the au coating surface.

The application of external forces by centrifugation or

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However, spinning is less suitable if the objects have a relatively large, rectangular, flat or almost flat surface to be overlooked, because the equipment required is then large and must be costly.

As a method of coating an essentially flat surface with a glass-like layer of equal thickness, obtained by melting a layer of vitreous particles attached by deposition from a suspension, which consists of an organic liquid in which vitreous material is suspended in an infinitely dispersed state in the absence of a binder is, these disadvantages can be completely avoided if, according to the invention, the deposition is continued for at least θ hours, after which removing the liquid and drying and melting the soil. The longer the deposition time, the stronger the layer consisting of deposited parts becomes. A thin organic liquid with a dielectric constant of more than 20 is preferably selected for the suspension. Methanol is particularly suitable, Ethenol and acetone, whose dielectric constants are 32.6, 24.5 and 20.7 are. The absence of a binder gives the advantage that which does not result from decomposition or combustion of the binding agent a porSs is so that afterwards when melting a completely clear, glass-like So it is not obtained. The high dielectric constant results in a uniform layer thickness during the deposition, because the particles in the Do not clump the suspension together. As a result of the long aging period the layer becomes so dense, probably as a result of the discharge of the particles when they touch each other, that the liquid ebgo-

siphoned or vacuumed and the layer can be dried without thea * Irregular sigcoites occur in the layer thickness. After the Gchraelzon

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the layer turns out to be eyeing the variations in thickness on the layer thickness are less than 10 $. The thickness of the 'layer calibrate by calculating the amount of glassy to be suspended Determine the material exactly. In general, the thickness of the layer is determined according to the melting between 20 and 100 / um, depending on the thickness of the strip-shaped conductor, which means the layer on the coated Surface need to be attached. However, it has also proven to be possible proven, completely clear, dense and within the mentioned thickness tolerances lying molten layers of vitreous material with a Thickness of 5 to 8 / µm to be applied to a surface.

The invention is described below for an embodiment explained in more detail on the basis of the accompanying drawing. Show it

1 shows an uncoated glass plate for a gas discharge image display panel,

Fig. 2 schematically shows a cross section through a deposition bath

Pig, 3 a panel board with a melted layer made of glass-like material and a ladder attached to it before they are attached to the panel plate »,

FIG. 4 shows a cross section through the pair plate according to FIG. 5 after the ladder has been attached to the panel plate, and '

5 shows a cross section through part of a picture display panel.

One or more cleaned glass plates 1 of the type shown in FIG. 1 are placed on the bottom of a bucket 9 with the covering surface facing upwards. Then the suspension 11 is poured into the bucket 9. The suspension II consists of pure methanol and a calculated amount of powder of a light weight: ßlaeart, the * n particles smaller than 16 / um bind, while 50 " foiose particles

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and 50 % smaller than β ^ ι let. As a result of the high dielectric constant of methanol (namely 3?, 6), the glass parts receive a comparatively large charge and they eject strongly from each other, so that no clumping of glass parts occurs for a relatively long time. For a layer 12 to be formed on the surface of the plate 1, which after melting has a thickness of 20 μm, 5 mg / cm * glass powder must be applied to the surface of the plate 1. As a result of the high dielectric constant, the layer 12 has a very uniform thickness, but has a loose structure. However, it turns out that this structure becomes sufficiently dense if a storage time of longer than 8 hours is chosen. In general, it is advantageous to leave the suspension 11 to stand overnight, which corresponds to a deposition time of about 14 to 16 hours. It turns out that the sleeve 12 has then become sufficient to allow the liquid 11 to be removed by siphoning or suction using a device 10.

The glass plate 1 with the substrate 12 consisting of vitreous particles is then dried, after which the layer 12 is melted. After cooling, the conductors 4 or 5 (see Figures 3 and 5) are placed on the layer 12 and the whole thing is heated in an oven, where the sohioht 12 melts again and the conductors 4 and 5 are partially embedded in it (see Fig 4) · Duroh fitting Vahl the Dick? the layer 12 can be achieved that two άβη conductors 4 * 5 channels 8 are held, via which the cavities 7 of the Swlacfciniplat te 5 are evacuated and filled with the desired gas. Since the Sue [harvest contains 11 kilograms of binder, the Sr-hinht 1? Getrcoknot, clri that Z-jroetsung a> s Blndeui t tcI'J needs to take place * Laduivih i ti t Λ J. f fatrockfj «t ■? fi. ^ iii ^ iit 1? benorulero foat 'j * iJ Of ₁ ^ h tion Sohnol ϊοϋ

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non-porous, while a layer thickness to be precisely determined beforehand is obtained; whose deviations are only 5 to 10 ^. In general In the production of panels of large dimensions, the layer thickness is not made greater than lOOyum, among other things to avoid the glass-like material flowing away during the melting process. Thickness of less than 100 / µm affects the surface tension towards the layer that flows away.

The surface to be covered can also be something instead of flat concave to be convex. The permissible radius of curvature is from the Tolerance in the thickness of the layer 12 depends, because with such Surface the layer thickness at the edge will deviate from that in the middle, since the layer thickness depends on the liquid column above the surface. Because the layer 12 does not have any pores as a result the decomposition of a binder «, it turns out that this layer 12 is completely dark and clear after melting.

In Fig. 5, the top plate 2 is the same with the conductors 5 Made like the base plate 1.

Besides the mentioned liquids you can use it for the suspension 11 also mixtures of these substances with s.B. Recycled alcohols are used to get about a lower dielectric constant ssu, as described in said Dutch patent application 285.620. However, there is then the danger that the particles in outer Suspension 11 vthrar-d the long-depositu & goseit clump together.

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Claims (1)

- 8 - PHH.6062 1. Process eum redrawing a substantially flat surface old a flail-like layer of uniform thickness, which through Melting a layer consisting of vitreous particles obtained that is attached by deposition from a suspension that is made up of an organic liquid in which a vitreous material is suspended in a finely divided state in the absence of a binder is, characterized in that the deposition time is at least 8 Hours after which the liquid is removed and the layer is dried and melted. 2. The method according to claim 1, characterized in that the liquid has a dielectric constant of more than 20. 3. The method according to claims 1 and 2, characterized in that the liquid consists of methanol. 4. The method according to claims 1 and 2, characterized in that the liquid consists of ethanol. 5. The method according to claim 1 and 2, characterized in that the liquid consists of acetone. 6. Oegenetand, in particular an insulating plate for a .Ga β-discharge image display panel, bit of a relatively large, im substantial flat surface covered with a layer of vitreous Material according to the method according to claims 1, 2, 3, 4 or 5 is covered. 3033.27 / 0729