PROCESS FOR FABRICATING A WRITING BOARD, AND WRITING BOARD OBTAINED WITH SUCH PROCESS

Abstract: A tempered glass sheet (1), with at least one of its faces (2) matted to determine the writing surface of the corresponding writing board, preventing reflections and allowing to view slides on said surface (2) of the glass sheet (1) which makes up the board. On the opposite surface (2'), which may be matted or not, is applied a serigraphy layer (3) of vitrifiable enamel, which layer (3) determines the required opacity. The board may also comprise a tempered glass sheet and another normal glass sheet, and between these the opacity layer, which may consist of the means of attachment of the glass sheets, such as polyvinyl butyral, which will preferably be white in colour, or of by serigraphy of the surface behind the writing surface, in which case the attachment layer will be transparent.

Description: OBJECT OF THE INVENTION The invention relates to a procedure for obtaining a glass writing board, in which writing is performed by means of a marker or a similar tool, with its main characteristic being that said surface is matted or dulled in order to prevent reflections or glare, allowing said surface to be complementarily used for viewing slides. A further object of the invention is the make up or structure of the board obtained according to said procedure, which board is mainly composed of a tempered glass sheet with its writing surface matted and provided on the opposite side with an opaque layer, which may be of a different nature or even be complemented by more different boards or layers. BACKGROUND OF THE INVENTION The advantages offered by plastic boards, normally white in colour, are well known, on the surface of which characters may be written using a specific marker, with such characters easily removed by a suitable eraser. However, said type of boards show a number of disadvantages, among which are the following: with time and use, they normally suffer a degradation which normally ends in the board resulting useless. writing must always be performed using a specific marker. the writing surface, as it is made of plastic materials, does not withstand certain solvents such as acetone, alcohol, etc. and obviously even less certain acids. as a result of the above, elimination of marks or stains caused by an unspecific marker or by any other means is difficult. the board surface causes glare or reflections which make it unsuitable for use, for example, as a projection screen for slides. GB 500 443 A discloses a glass writing board with a roughened front surface and a rear surface coated with a dark pigment. DESCRIPTION OF THE INVENTION The invention relates to a manufacturing procedure for a writing board, as well as to the structure of the board thus obtained, which shows all advantages of this type of boards but none of their disadvantages, as it does not reflect light nor therefore images, and withstands any solvent except hydrofluoric acid, being highly durable and practically undegradable over time and use, and which can be used as a projection screen for slides without glare or reflections, all of this due to said board being obtained from a matted tempered glass sheet as will be described throughout the present description. The procedure for obtaining or manufacturing the board is based on the following operative stages: A glass sheet of a thickness which allows tempering and of a size conforming to the writing board to be obtained is subjected to a matting process on at least one of its two faces, this matting performed using any known means, whether by acid (using hydrofluoric acid), sand (by blasting sand on the surface to be matted) or mechanically in hot during the rolling lamination process of the glass. The matting creates a roughness or porosity of the surface which reduces or even eliminates reflections, such that the treated surface does not reflect images nor cause glare. The most effective matting is achieved using acid, as this method results in a fine and evenly distributed porosity or roughness throughout the entire surface. The coarsest matting and also the cheapest is obtained with suitable rollers in the rolling lamination process of the glass. Sand matting is an intermediate solution as regards quality and price. Afterwards the glass edges are polished to eliminate any sharp edges. Then a vitrifiable paint is applied, or an opaque layer applied by serigraphy or any other means on the opposite surface to the matted writing surface. Finally, the glass is tempered so that in this tempering a double effect is achieved; on one hand the enamel is vitrified, so that it is permanently attached to the glass, and the tempering itself is achieved. The board thus obtained is of tempered glass, so that in the event of breaking it shatters into many particles. In this procedure a matting or dulling process may be performed on both faces of the tempered glass sheet, with the opaque layer applied to either face, said layer consisting of a vitrifiable enamel applied with serigraphy. Likewise, the procedure may employ two glass sheets, one tempered and the other of normal glass, so that the first one is matted to form the writing surface, with the two surfaces joined as usual by a suitable layer of plastic, preferably polyvinyl butyral (PVB), which layer in turn determines the board's opacity, for which purpose it shall be coloured, preferably in white. According to the procedure of the invention, it is also possible for the tempered and matted glass sheet to be serigraphed on the face opposite the writing surface and the union to the normal glass sheet to be performed using transparent PVB, which in this case will act as a union between the two glass sheets, as the opacity will be provided by serigraphy. DESCRIPTION OF THE DRAWINGS As a complement of the present description and in order to aid a better understanding of the characteristics of the invention, according to a preferred embodiment of the same, the description is accompanied by a set of drawings where, for purposes of illustration only and not meant as a definition of the limits of the invention, different construction forms for the board are shown obtained according to the procedure of the invention. Figure 1 shows a specific embodiment of a glass board obtained in accordance with a preferred embodiment of the invention, which in this case consists of a tempered glass sheet tempered on both faces, with the opacity layer applied to one face by serigraphy with a vitrifiable enamel. Figure 2 shows a sectional enlarged view of part of the board consisting of a tempered glass sheet, a sheet of normal glass and between them a layer of plastic such as polyvinyl butyral (PVB), which in addition to joining both glass sheets determines the opacity of the board as it is coloured, preferably white. Figure 3 shows, finally, a sectional enlarged view of a portion of the board consisting of a tempered glass sheet and a normal glass sheet, with the tempered glass sheet serigraphed on the side opposite the writing surface, with the two glass sheets joined by a PVB layer. PREFERRED EMBODIMENT OF THE INVENTION As seen in the figures and more specifically in figure 1, a section of part of a board can be seen comprising a tempered glass sheet (1) whose two surfaces (2, 2') have been matted to prevent glare or reflection on the surface of faces (2, 2'), with one of these surfaces provided with a vitrifiable enamel layer (3) applied by serigraphy, all of this such that face (2) comprises the writing surface and layer (3) applied to the opposite face (2') determines the opacity of the board. In an alternative embodiment of the board (figure 2), it may consist of a tempered glass sheet (1) and a normal glass sheet (1'), with the tempered glass sheet (1) provided with the corresponding matting on its surface (2) which makes up the writing surface, while between the two glass sheets (1, 1') is provided a plastic layer (4), preferably of polyvinyl butyral which acts as a junction element and also provides the required degree of opacity for which said PVB layer shall be coloured, preferably white. The board obtained according to the embodiment of figure 2 will have the properties of tempered glass, so that in the event of breaking the glass segments will not become loose but will remain joined to the junction element or PVB layer. As indicated above, the opacity is obtained by colouring the plastic layer (4), preferably white. In a third alternative embodiment shown in figure 3, the board includes as in the above cases two glass sheets (1, 1'), the first tempered and the second normal. Tempered glass sheet (1) is matted on writing surface (2) and is provided with a serigraphed surface (3') on the opposite surface. The two glass sheets are joined by means of a suitable plastic layer (4'), such as PVB, which in this case will be transparent as it functions solely as a junction of the two glass sheets.

Claims: Procedure for obtaining writing boards, designed to obtain a glare free surface in which writing marks or stains of any kind are easily removed, which surface may also be used to project slides, using a glass sheet of a thickness which allows tempering, of a size according to the board to be obtained, said procedure comprising the following operative stages: Matting or dulling of at least the surface to be used for writing; Polishing of the glass sheet edges; Application by serigraphy to the surface opposite the writing surface of a vitrifiable enamel of a suitable thickness, to obtain the required opacity; Tempering of the glass, in which operation the vitrifiable enamel layer is permanently attached. Procedure for obtaining writing boards, as claimed in claim 1, characterised in that both surfaces of the tempered glass sheet are subjected to the matting process. Procedure for obtaining writing boards, as claimed in above claims, characterised in that on either matted surface of the tempered glass sheet is applied a serigraphy using a suitable enamel, in order to obtain the opaque layer. Procedure for obtaining writing boards, as claimed in claim 1, characterised in that on the tempered and matted glass sheet with the opaque serigraphy is provided and attached a second sheet of normal glass. Procedure for obtaining writing boards, as claimed in claim 4, characterised in that between the tempered glass sheet and the normal glass sheet is applied a thin layer of plastic, preferably white in colour, of polyvinyl butyral, which acts as a means of attaching the two glass sheets and provides the required degree of opacity. Writing board obtainable according to the procedure of the above claim 1, characterised in that it comprises a tempered glass sheet (1), of thickness preferably between 3 and 6 mm, with any size and shape, with its writing surface (2) matted and the opposite surface (2') provided with an opaque layer (3) consisting of serigraphy with vitrifiable enamel. Writing board, obtainable according to the procedure of claim 5, characterised in that it comprises two glass sheets (1, 1') the first of which is of tempered glass and the second of normal glass, and between them a layer of plastic (4) which provides the opacity and the attachment means for the two glass sheets (1, 1'), with the outer surface of tempered glass sheet (1) provided with a matting (2) which comprises the writing surface. Writing board, obtainable according to the procedure of claim 5, characterised in that it comprises two glass sheets (1,1') the first of which is of tempered glass and the second of normal glass, and between them two superimposed layers (3', 4') the first of which determines the opacity and consisting of a serigraphy with vitrifiable enamel, and the second one made of a transparent plastic material, acting as a means of attachment of the two glass sheets, so that the outer surface of tempered glass sheet (1) is provided with a matting (2) which determines the writing surface.

Inventors: ALONSO GOROSTIZA JOSE ANTONIO, TORRES SANCHO RAFAEL, ALONSO GOROSTIZA, JOSE ANTONIO, TORRES SANCHO, RAFAEL, ALONSO GOROSTIZA, José Antonio
Applicants: GUARDIAN LLODIO S L, GUARDIAN LLODIO, S.L.
Application year: 1998
Main classification: B43L1
IPC codes: B43L1