OBJECT OF THE INVENTION
[0001] 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.
[0002] 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
[0003] 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.
[0004] 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.
DESCRIPTION OF THE INVENTION
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] The board thus obtained is of tempered glass, so that in the event of breaking it
shatters into many particles.
[0012] 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.
[0013] 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.
[0014] 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
[0015] 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
[0016] 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.
[0017] 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.
[0018] 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.
[0019] As indicated above, the opacity is obtained by colouring the plastic layer (4), preferably
white.
[0020] 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.
1. 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, characterised in that, using a glass sheet of a thickness
which allows tempering, of a size according to the board to be obtained, comprises
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.
2. 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.
3. 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.
4. 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.
5. 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.
6. Writing board obtained according to the procedure of the above claims, 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.
7. Writing board, as claimed in claim 7, 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.
8. Writing board, as claimed in claim 7, 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.