|Title of Invention
ARTICLE OF LIGHTWEIGHT INORGANIC AGGLOMERATE IN FORM OF SLAB, PROCESS OF MANUFACTURING THE SAME AND RESULTING PANEL
|In a method for manufacturing conglomerate articles in sheet form, a mix comprising the following is prepared: an expanded inert granular material; a filler consisting of hollow inorganic microspheres and a plasticizer (clay, quartz or other powder mineral, cellulose); an aqueous silicon-containing binder. A layer of mix, where necessary coated with a fibreglass meshwork in order to increase the mechanical strength thereof, is deposited on a temporary support and subjected to vacuum vibrocompression. The resultant rough-formed sheet is heated at a controlled temperature so as to cause evaporation of the water present in the mix. A light, sound-absorbing, heat-insulating sheet, rated in Class 0 in terms of fire reaction, suitable to be plastered or painted superficially and used for forming panels and artitions for internal and external use, is obtained.
The present invention relates to a novel article in sheet form and to a method for the
More specifically the present invention relates to a novel article in sheet form
featuring lightness, heat-insulating and sound-insulating properties.
It is known that for the production of dividing walls, in most cases panels made of
wood or materials generally referred to as "plasterboard" are used.
Wood panels, in addition to the high intrinsic cost of the material, also pose the
problem of their considerable weight in cases where the walls must be of a suitable strength
and robustness and provide good sound insulation; wood is moreover highly combustible and
prone to rot. In addition to these problems there is also the difficulty of manufacturing
panels which have large dimensions.
Plasterboard walls, for their part, have a low mechanical strength and rather poor
heat- and sound-insulating properties.
For many years a technology (which combines a process and a plant) known as
Bretonstone System has been known, this technology being used for the manufacture of
articles made of a stone conglomerate, in particular articles in the form of sheets or blocks,
and composed essentially of the following operations (with reference here to the manufacture
of articles in sheet form):
- preparing an initial mix consisting of a granular material of predefined and selected
particle size and a binder, which in general terms may be cement-based or consist of a
hardening resin, the granular material being chosen from among ground stone materials and
ceramic materials and consisting partly of an inorganic material, preferably very fine marble or
quartz (particle size of about 325-400 mesh), called "filler" in industrial practice;
- depositing the mix on a temporary support in the form of a layer of predetermined
- applying to the layer of mix, kept under a predefined vacuum, a compaction pressure
together with a vibrating movement of predefined frequency (this step will be referred herein
as vacuum vibrocompression);
- hardening the resultant compacted article (subsequently to a setting step in the case
of a cement-based binder).
Recently, the Applicant has developed a variant of the aforementioned technology,
using a silica-based watery substance as binder.
In a first preferred embodiment, said binder consists of an aqueous dispersion of
colloidal silica, also known as "silica sol".
In a second preferred embodiment, said binder consists of an aqueous solution of a
sodium or potassium silicate mixed with zinc oxide.
More specifically, the Applicant has developed a method for manufacturing articles
adopting the Bretonstone system and therefore the steps indicated above, said method being
characterized in that:
(1) the binder used for preparation of the starting mix is silica sol, namely a
dispersion, in the aqueous phase, of particles of colloidal silica with nanometric dimensions,
or, alternatively, an aqueous solution of a mixture formed by a sodium or potassium silicate,
in which the proportion of silica and sodium oxide or potassium oxide, respectively, is
between 2 and 4, and by zinc oxide in a proportion of between 5 and 35% by weight;
(2) after the vacuum vibrocompression step, the resultant rough-formed sheet is
heated with a predefined temperature gradient up to a temperature of 80-120°C for a few
hours, until a substantially complete evaporation of the water present in the sheet is achieved,
resulting in a rough-formed article which is sufficiently strong to allow handling thereof, but
has a porosity corresponding to the empty spaces left by mix water removed by means of
(3) the rough-formed sheet obtained in the predous step is impregnated with a
hardening resin so as to fill the pores, after which the final step of hardening the hardening
resin which has penetrated into the sheet is performed.
In connection with the first characterising feature of the method indicated above,
when an aqueous dispersion of colloidal silica (also known as silica sol) is used as a binder,
this is a binder which is already used in other fields, for example in molding sands, does not
require the use of a solvent and is particularly valued since it is non-polluting.
However, as is well-known, in the case of molding sands, the aggregation of the sand
in order to form articles such as the so-called cores must have only a temporary duration, i.e.
until the metal is cast, following which the sand is recovered in loose form. Therefore, the
mechanical properties of the article are of very limited importance and in particular properties
such as sound insulation, heat insulation and breathability (understood as meaning the
capacity to prevent the passage of liquids, but not that of air and vapours) are of no interest.
It has now been discovered, this forming the object of the present invention, that by
adopting the method of the Bretonstone system, suitably modified both as regards the
composition of the starting mixture and as regards the aplication steps, it is possible to
produce articles in the form of sheets having desired characteristics such as lightness, heat
and sound insulation, breathability and adequate mechanical strength.
This object is achieved by the method in question where the initial mixture comprises
a granular inorganic inert material which is expanded and consequently leightweight, a filler
formed by hollow inorganic microspheres and clayand a binder consisting of the already
mentioned silica sol or, alternatively, the said aqueous solution of a mixture formed by a
sodium or potassium silicate and zinc oxide, having a concentration of 24 degrees Baume,
namely, a relative density of 1,1933 g/cm3.
The mediod is moreover modified in that the step involving impregnation with
hardening resin is omitted, since it has the main aim of making the article resistant to the
penetration of water.
The resultant article in sheet form has distinctive features such as:
- a specific weight of less than 1, usually in the region of 0.8 kg/dm3;
- a mechanical flexural/tensile strength, of about 30 kg/cm2 (3 N/mm2);
- a porosity of about 10% by volume;
- a rating of fire reaction (inflammability) in class 0, when the initial mixture does not
contain organic and therefore inflammable components such as cellulose, replacing - though
partially -the clay.
The resultant sheets may then be used both for dividing walls and as internal panels
and for external use since they may be finished by means of a conventional plastering or
painting which increases the resistance to the action of atmospheric agents.
As regards the components of the starting mixture, about 60% by volume consists of
the expanded lightweight granular inert material, which is preferably glass or ceramic
The materials in question are commercially available (for example, under the name of
Leca, Poraver or Liaver) so that further details are not necessary. The particle size thereof is
chosen to ensure optimum filling of the mixture, for example in accordance with the weE-
known Bolomey's formula (a formula commonly used in the preparation of cement-based
In the application of the formula according to the present invention, the particle size
range of this granular material is between 0.1 and 12 mm and preferabry between 0.5 and 6
mm, divided into a suitable number of fractions, normally four. The quantity of granular
material included in each fraction is chosen precisely taking into account Bolomey's formula.
If we consider now the filler, which forms about 24% by volume of the initial mix, it
is essentially in the form of a fine powder and comprises about 12% of hollow organic
microspheres, preferably fillite, said material consisting of microgranules of expanded
siliceous material obtained from the ashes of coal-fired power stations, with a particle size of
between 90 and 150 microns.
The remaining 12% of the filler phase comprises a clay-like mineral which has the
function of imparting plasticity to the initial mix. Precisely in order to control the degree of
plasticity, part of the clay-like material is normally replaced with quartz powder or other stone
material such as feldspar or marble.
In the practical embodiment of the present invention about 50% of the clay-like
material is replaced with cristobalite in powder form.
If it is required to increase the flexural strength of the articles in sheet form obtained
by the present invention, the two opposite surfaces may be covered, prior to vacuum
vibrocompression, with a fibreglass meshwork which remains incorporated within the
surfaces of the article.
An important feature of the present invention consists in the fact that it is also
possible to produce articles in sheet form of a considerable thickness (about 10-15 cm).
The examples below illustrate the present invention in a non-limiting way.
In a plant for performing vacuum vibrocompression, a mixture comprising the
following components is prepared:
- expanded granular glass material
(0.5-6 mm) 60% by volume
- fillite 12% by volume
- clay and cristobalite (less
than 20 microns) 12% by volume
- silica sol 16% by volume
In the deposition step this mixture is deposited on a support, forming a layer with a
thickness of about 9 cm.
The deposited layer, onto the associated support, is transferred to the vacuum
vibrocompression station, where a pressure of about 1 kg/cm2 for a duration of about 60 s
under a residual pressure of about 20 mbar is applied by means of a pressing plate. At the
same time a vibratory movement at a frequency of about 60 Hz is applied.
The resultant rough-formed sheet is transferred to a drying oven where it undergoes
heating at a temperature of about 90°C for a duration of 10-12 hours.
The resultant article in sheet form, which has a specific weight of about 0.82 kg/dm3
and is therefore very light, has a thickness of 33 mm and a mechanical flexural/tensile
strength of about 3 N/mm3.
Example 1 is repeated except that the following modifications are made.
The quantity of clay is increased by 1% by volume, reducing correspondingly the
quantity of cristobalite, so that the plasticity of the mix increases.
In this way it is possible to produce an article in sheet form of a smaller thickness,
which in this case is 23 mm, while the physical and mechanical properties of the resultant
article remain unchanged.
It is worth noting that, by the method according to the present invention, sheets of
considerable dimensions, about 1.5 x 3.2 m, may be manufactured, so that the formation of
dividing walls and partitions is also made a lot easier.
As mentioned above, the clay-like material may be partly or totally replaced with
cellulose, which has the same effect of imparting plasticity to the initial mix.
However, in the case of cellulose, the presence of this organic component is to the
detriment of the total non-inflammability which instead characterizes those articles in which
only inorganic components such as clay and cristobalite are used in the initial mix.
The invention has been described in connection with a preferred embodiment, it
being understood that conceptually equivalent modifications and variants are possible and
may be envisaged without departing from the scope of protection thereof, as defined in the
In particular, the articles in sheet form according to the present invention may be used
not only for dividing walls and partitions but also for other purposes.
1. Conglomerate article in sheet form, obtained from an initial mix comprising a
granular material of selected particle size, a water-based binder and a filler, said mix, after
deposition on a support being subjected to vacuum pressing with simultaneous application of a
vibratory movement and afterwards subjected to drying in order to remove the mix water,
characterized in that:
- said granular material consists of expanded glass or expanded ceramic material, having a
particle size of between 0.1 and 12 mm and preferably 0.5 and 6 mm;
- said filler consists of hollow inorganic microspheres and a plasticizer; and
- in the initial mix said binder being chosen from an aqueous suspension of colloidal silica
(silica sol), or an aqueous solution of a mixture formed by a sodium or potassium silicate and by
2. Conglomerate article in sheet form as claimed in Claim 1, wherein
- said aqueous solution has a concentration of 1,1933 g/cm3;
- in said silicate the proportion of silica (SiO2) and sodium oxide (Na2O) or the proportion of
silica (SiO2) and potassium oxide (K2O), is between 2 and 4 by weight;
- the proportion of zinc oxide (ZnO) in said mixture is between 5 and 35% by weight.
3. Conglomerate article in sheet form as claimed in Claim 2, wherein the proportion of
zinc oxide (ZnO) in said mixture is equivalent to 10% by weight.
4. Conglomerate article in sheet form as claimed in Claim 2, wherein said hollow
inorganic microspheres consist of fillite.
5. Conglomerate article in sheet form as claimed in Claiml, wherein said plasticizer
consists of clay-like mineral.
6. Conglomerate article in sheet form as claimed in Claim 1, wherein at least one part
of said clay-like mineral is replaced by quartz, feldspar or marble powder.
7. Conglomerate article in sheet form as claimed in Claim 5, wherein at least one part
of said clay-like mineral is replaced by cellulose.
8. Conglomerate article in sheet form as claimed in Claim 5, wherein 50% of said clay-
like mineral is replaced by said quartz, feldspar or marble powder.
9. Conglomerate article in sheet form as claimed in Claim 5, wherein 50% of said clay-
like mineral is replaced by cristobalite powder.
10. Conglomerate article in sheet form as claimed in Claim 1, wherein said initial mix
comprises at least 50% by volume of said expanded granulate, at least 10% by volume of hollow
inorganic microspheres and at least 15% by volume of said aqueous suspension of colloidal silica.
11. Conglomerate articles in sheet form as claimed in Claim 1, wherein said initial mix
comprises 60% by volume of said expanded granular glass or ceramic material, 12% by volume of
fillite, 12% by volume of a mixture, 50% of which is formed by clay and 50% by cristobalite
powder, and 16% by volume of an aqueous suspension of colloidal silica.
12. Conglomerate article in sheet form as claimed in Claim 1, which has a specific
weight of less than one, a porosity of 10%, a mechanical flexural/tensile strength of 3 N/mm2 and,
in terms of fire reaction, is rated in Class 0.
13. Conglomerate article in sheet form as claimed in Claim 1, wherein at least one of its
surfaces is covered by a fibreglass mesh work incorporated in the said surface.
14. Panel, in particular for forming walls and partitions, which comprises at least one
article as claimed in any of the preceding claims, with a plastered finish suitable for domestic use.
15. Panel, in particular for forming walls and partitions and for external cladding, which
comprises at least one article as claimed in any of claims 1 to 13,said method comprising: finished
with surface painting.
16. Method for manufacturing articles as claimed in any one of Claims 1 to 13, said
using vacuum vibrocompression technology, characterized in that an expanded granular
material consisting of inorganic inert material, a filler consisting of hollow inorganic micro spheres
and a plasticizer such as a clay-like mineral and a binder which consists of an aqueous suspension
of colloidal silica or, alternatively, of an aqueous solution of a mixture formed by a sodium or
potassium silicate and zinc oxide are used as components of the initial mixture, and that the step
involving impregnation with a hardening resin is omitted.
17. Method as claimed in Claim 16, wherein the drying step following the vacuum
vibrocompression step is performed at a temperature of 90-120°C and for a duration of 12 hours.
(54) Title: ARTICLE OF LIGHTWEIGHT INORGANIC AGGLOMERATE IN FORM OF SLAB, PROCESS OF MANUFACTURING
THE SAME AND RESULTING PANEL
(57) Abstract: In a method for manufacturing conglomerate articles in sheet form, a mix comprising the following is prepared: an
expanded inert granular material; a filler consisting of hollow inorganic microspheres and a plasticizer (clay, quartz or other powder
mineral, cellulose); an aqueous silicon-containing binder. A layer of mix, where necessary coated with a fibreglass meshwork in
order to increase the mechanical strength thereof, is deposited on a temporary support and subjected to vacuum vibrocompression.
The resultant rough-formed sheet is heated at a controlled temperature so as to cause evaporation of the water present in the mix. A
light, sound-absorbing, heat-insulating sheet, rated in Class 0 in terms of fire reaction, suitable to be plastered or painted superficially
and used for forming panels and artitions for internal and external use, is obtained.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|VIALE ASIAGO 34, I-36061 BASSANO DEL GRAPPA
|PCT International Classification Number
|C04B 28/24,F04C 2/04
|PCT International Application Number
|PCT International Filing date