The present invention refers to a process for making a product from
artificial rock and a product thus made.
A product of this type can be used in aquarium-building trade and,
in general, in the manufacturing of rocky decorations, and other non-rocky motifs
of medium and large dimensions, for use in aquatic and/or public swimming environments
wherein stringent requirements of non-toxicity are to be met also after decades
of service life.
At present, in the production of artificial rocky environments, use
is made use of cement. Such solution has drawbacks such as the need of colouring,
possible alteration of water's pH, poor resistance of the colour over the time because
of the contact with the water and the effects of shocks and other external agents
Among the objects of the present invention, one is to replace the
cement in the construction of large rocky environments and in the decoration of
facilities that are particularly difficult to reach, thereby overcoming the above
One of the advantage of the present invention lies in that by using
a mixture of resin, aggregates, and a series of auxiliary products for processing
the resin, there is obtained a product which is realistic to the touch and sight,
while eliminating the use of pigments that are likely to discolour and become altered
over the time because of their exposure to heat or light; in particular, the specific
formulation of the mix and the thickness by which it is produced, ensure a long
life of the product in terms of strength and colour.
Besides, the surface exhibited by a product made according to the
invention can be scratched, pierced or abraded and, nevertheless, thanks to its
structural characteristics and the high thickness of the mix by which it is made,
the homogeneity of the same surface is maintained even when the latter is subjected
to mechanical shock or wear.
A further advantage is that the absence of surface's colouring maintains
the product unaltered over the time also when it is fully immersed into the water
or merely subject to a current of running water, either fresh or salt.
Yet another advantage stems from the mechanical resistance to the
abrasion, and to bending and tensile strength, thereby allowing the use of rock
also in cases that imply structural withstanding capacity against any possible mechanical
Moreover, the aggregates of the mix are selected free of impurities
to such a degree that the use of regenerated artificial rock in aquarium construction
- contrary to the cement - does not alter the pool's pH, thereby leaving the physico-chemical
parameters of the water unaltered.
Another important factor to be considered when making rocky decorations
for aquariums is the grow of algae which enrich the aspect of the expository tank:
a careful selection of the quality and physico-chemical proprieties of the aggregates
will favour a better and faster colonization of the regenerated rock by red, calcareous
encrusting algae than with rocks made from cement or painted plastic materials.
In this way, it is possible to build an excellent sublayer for the colonization
of sessile plants and animals.
The other high advantage of using regenerated rock is that it can
be supplied in panels of any dimension and shape to overcome any logistic staging
problem; the relatively light panels allow carrying out any setting in environments
difficult to access; care in the details and shapes will make the product a true
copy of the real environment.
These and other advantages and characteristics of the invention will
be best understood by anyone skilled in the art from a reading of the following
description given as a practical exemplification of the invention, but not to be
considered in a limitative sense.
The present process is substantially based on mixing an isophtalic
or bisphenolic polyester resin with aggregates of various nature and granulometry,
derived from working marble, granite, stone in general, quartz, - selected according
to their colour, strength and intended use in building aquarium and the like - in
order to produce synthetic rock panels to be laid on waterproof rolled sections,
said panels being of any possible modular shape, light-weight, waterproof and constructed
in a manner that allow them to be transported and to withstand high loads, while
being identical to the touch and sight to rocky surfaces of various morphology and
In order to manufacture a product that will best reproduce the characteristics
of a given type of rock, it is necessary to make a careful identification of the
rocks to be imitated. This stage of the process may comprise: localizing the geographical
area of the rock, analyzing the typical morphology of the rock in situ, analysing
the atmospheric and climatic conditions in order to determine the type of wear due
to water and wind erosion, as well as other possible conditions; analyzing the habitat
in general. Samples may also be collected for the analysis of the mineral composition
of the rock in relation to the colour, shape, texture and colour variations.
Afterwards, a mixture is made of the selected aggregates which is
able to imitate said colour, chromatic variations, texture and shape. The material
can be prefereably chosen among those indicated below and resulting from rock crushing:
- raw material, made up of periodite rock reach in olivine minerals, which is
crushed, milled, selected and classified into corns, sands and powders:
- isomorphous mixture of magnesium silicates (phosphorite) and iron silicates
(fayalite) (Mg, Fe)2SiO4;
- marble powder (CaCO3 and MgCO3) in any colour and granulometry,
washed, dried in oven, riddled and divided according to its granulometry.
Thereafter, an analysis is made of the final setting of the regenerated
rock, that is, of the load that the rock is to withstand, by evaluating the mechanical
stress in tension and bending, and the degree of erosion caused by chemical agents,
while observing the animals or persons usually present in the environment, the water
nature and any other factor that makes integral part of the design.
Then the mixtures are formulated by selecting the aggregates, resins
and resin's additives, thixotropic agents, operating temperatures, type of glass
fibers, while considering the general working conditions and assembly problems.
The chosen resins are of polyester, and can be prefereably identified
in the following types: bisphenolic polyester resin and unsaturated isophtalic resin.
The bisphenolic polyester resin is a styrene solution of flexible
polyester resin composed of bisphenol A fumarate propoxilate and pre-accelerating
agent for polimerization at ambient temperature. The resin combines an exceptional
resistance against a plurality of corrosive agents in aqueous solution, with good
properties of mechanical resistance versus temperature, high flexibility and improved
shock-resistance characteristics. The rolled sections based on isophtalic resin
are approved for applications with drinking water to food stuff in general. Common
applications are for the construction of any type of product in glass-fiber reinforced
plastics for chemical facilities such as, storing tanks, process equipment, tubing,
conduits, chimneys, and for coatings on steel and concrete. The use of the above
said resin for rock-supporting stratifications ensures, besides an excellent resistance
of the same stratifications against the chemical agents present especially in sea
water, a reduced structural thickness. with respect to common resins, while maintaining
the same mechanical resistance properties in bending and compression. The special
composition of the resin makes it particularly suited for moulding processes with
The isophtalic resin is an unsaturated isophtalic, thixotropic, stirene-processed,
pre-accelerated resin which the presence of a color-changer additive. It exhibits
glass fibers of optimal wettability, excellent hardening also on thin layers, and
its thixotropic nature allows it to be easily worked also in a vertical plane. The
high strength, increased HDT (High Deflection Temperature) and the excellent resistance
to water, make this kind of resins suitable for naval constructions and for swimming
pools and sanitary facilities; accordingly, these resins show to be suited for making
products that are plunged in salt water and are formed with considerable inert fillers.
The good wetting power allows the obtainment of rolled sections with high content
Following the formulation of the mixtures, a cast of the original is made, that
is, a silicon cast in situ of the rocks to be imitated. A form is made in resin
for moulds, which resin is reinforced with unsaturated polyester resin, such as
for naval constructions, and whose formulation is suited for reinforced plastics
sections requiring an easy workability and glass fibers with optimal wettability
and low marking.
A mould is then made for the production of panels in synthetic and
The mould is provided with a first coat of about 3-4 cm (thickness) of a mixture
consisting of: aggregates of various granulometries (0, 00, 000: in practice, the
powders are of different granes and up to 1-2 mm in diameter); a resin (selected
on the base of its chemical properties and capacity of being filled with aggregates);
additives (selected according to the catalysis proportion, presence of silica powder
to make the mix thixotropic; glass fibers to make it structural, etc.). The laying
of the coat is a single, hand-made operation which is carried out by the operator
who, on the base of his/her chromatic perception and according to the shape of the
cast, causes the mixtures to result variously shaded so that the surface will appear
non homogeneous and with a realistic aspect of chromatic variation, likewise a real
rock: many colours and minimum or evident variations of tone and colour).
Afterwards, the esothermic step of the catalysis is allowed to complete,
followed by a first cooling, for a total of 120 minutes approximately. The whole
surface is then covered by a film of pure isophtalic or bisphenolic polyester resin
to ensure the setting of the subsequent mix.
A second coat of about 3-4 cm of a mixture on powdered aggregates,
resin and additives is then laid in a single deposition to ensure a perfect adherence
of the waterproof and structural stratification.
The next step is the stratification of two successive layers of glass
fiber (450 gr/cm2) and a deposition of glass C and pure resin. With glass
C is meant a film of glass fiber very light but compact, having a waterproofing
function. To this end, the known product designated M524-C64 can be used.
A first, total polimerization of the product, that is, the hardening
of the resin as determined by the chemical reaction of the peroxide with the resin,
is then carried out.
Throughout the whole surface thus obtained a layer of white "Gelcoat"
is laid. By way of example, the product known by the name NEOGE ISY gelcoat ISO-Orto,
can be used.
Throughout the whole surface thus obtained a layer of black "Gelcoat" is laid.
For this operation use can be made of a product similar to the preceding one, with
the addition of paraffin.
A second total polimerization of the product is then carried out,
and the same product is withdrawn from the silicone mould.
Finally, a further polimerization is allowed to complete in about 120 seconds,
before processing the product within an oven for 5 hours, three of which at a temperature
of 100 °C and the others at 60 °C.
The moulding step is completed by a washing of the product with water
at 100 °C and stem.
The panels of regenerated rock thus obtained are assembled so as to
create forms suited for the staging: in this step, the panel can be cut, joined
to other pieces to form new ones, while any other manipulation may be performed
as necessary to give the piece the desired shape.
Once the panels have been given a suitable shape, and being associated
with others, the junctions are plastered with plastic putty made by mixing aggregates
and especially selected resins to be subsequently modeled likewise a rock. The characteristic
of such putty allows the operator to build rock's details of small and medium dimensions
capable of creating a continuity between the material being cast and the one being
modeled: the synthetic rock panel will result perfectly like the desired form and
aesthetically harmonious. The putty being used may be of the same material as that
of the panels, without using fibers. It is understood that panels of different dimensions
and shapes can also be made, either starting, as in the process above described,
from the silicone cast of the original, with portions possibly integrated by lab-modelled
parts, and using the moulds previously built. The panels could be lab-assembled
beforehand according to the shapes, dimensions and characteristics of the general
design, with a preassembly finishing made with malleable paste of the same colour
as the general mix of the rock. After having assembled the work in the laboratory,
the panels can be disassembled and subjected to a post-hardening in oven for an
average time of five hours, with three hour-baking at 100 °C to achieve the final
dispersion of the styrene, and washed with water at 100 °C and steam.
The assembly of the panels at the final location will be carried out
by using also self-bearing panels or, when necessary, a support structure made,
for example, of electro-welded iron, steel, resin or other material depending on
the location and requirements.
On the panels assembled in their final configuration, a joining stratification
is performed. The stratification allows joining the panels by means of a coating
of glass fiber and epoxy resin.
The visible junction lines of the panels can be concealed with a plastic putty
made from a mixture of aggregates, epoxy resin (this for avoiding the use of polyester
resin which, in order to be fully non-toxic, must be subjected to a post-cycle of
hardening, whereas the epoxy allows a polimerization at ambient temperature with
no risk for the health of persons or animals), and resin additives.
It should be pointed out that the formulation of a mixture allowing
the realization of realistic objects, while being extremely resistant, has made
it possible to implement a whole work process able to create small dimensions products
as well as monumental works, by maintaining unchanged the quality of the product
which results a true copy of the original.
By way of example, a product of synthetic rock made according to the
present invention, and having an extension of one square meter, may have the following
With this formulation, the total weight per square meter of product will be of
- gr. 9000 of resin, such as of "SYNOLITE 0280-I-1" type;
- gr. 180 of catalyst, such as of PEREXTER B18" type;
- gr. 14000 of aggregates consisting of calcium and quartz;
- gr. 100 of thixotropic thickening agent, such as of "CAB-O-SIL FUMED SILICA"
- gr. 1350 of glass fibers, such as of "MAT POWDER" 450 gr/m2 type;
- gr. 400 of structural glass fiber for plastics rolled sections, such as of "ROVING
AGIMAT" 800/300GR/M2 type;
- gr. 500 of structural glass fiber for plastics rolled sections, such as of "R63SX1
CHOPPED STRAND" type;
- gr. 1000 of resin filled with fine aggregates and pigment for finishing and
waterproofing applications', such as of "NEOGEL ISI 8378-W-0100" in fabric yarn
- gr 40 of waterproofing agent, such as liquid paraffin.