LAUSE SYNTHETIQUE

SYNTHETIC ROOFING SLATE

Abrégé anglais

The present invention is to produce a Synthetic Roofing Slate using heavily
filled
thermoplastic resin. The synthetic roofing slate will be rigid and
manufactured in different sizes
in order to accommodate different exposures. The tile produced will be tapered
from top to
bottom. The tiles will be manufactured with two nail holes at the top allowing
for easy
installation.
The roofing material produce and referred to as Synthetic Roofing Slate will
overcome the problem of heavily filled thermoplastic material having good
mechanical
properties particularly in flexural and impact strength. In addition the
roofing materiel will have
very good weathering characteristics; flame retardancy; good mechanical
performances over a
wide range of temperature; low water absorption and good freeze-thaw
performance.
It will also have the ability to be internally colored.

Revendications

Claims:
The embodiments of the invention in which an exclusive property or privilege
is claimed
are defined as follows:
1. In our invention, we proposed that we would be using 80-85% as a filler
content in
our formulation with the rest of recycled thermoplastic resin to produce
synthetic
roofing slate. Due to variation in the particle size of the different fillers
and high filler
content, thermoplastics along with fillers cannot be extruded through the
conventional
extrusion process, which is used only for melt-processible thermoplastic
resins. By
introduction of the high content fillers into thermoplastic resin make the
process more
complex because of the viscosity difference and as well as the different flow
ability of
the materials. It also makes the process commercially unacceptable. In our
invention
we overcome this problem and made the extrusion feasible by using maleic
anhydride
grafted polyolefin and metallic stearate (calcium and or zinc), a special
processing
stabilizer/ coupling agent.
2. The processing stabilizer/coupling agent mentioned in claim 1 is added at
0.1-5% of
the formulation depending on the particle size of the filler. It will reduce
the
interfacial tension between the mineral and the thermoplastic resin and also
provides
the better surface wetting between the surface of the filler and the
thermoplastic resin.
It also acts as a lubricant to aid in processing of formulation with high
filler content
up to 80-85%.
3. Formulation for producing synthetic roofing slate mentioned in claim 1 has
recycled
thermoplastic resin. Recycled thermoplastic resins are highly prone to
degradation
during reprocessing. In our formulation because of high filler content
thermoplastic
resin is enclosed by filler, which reduces their chances for degradation.
4. Formulation mentioned in claim 1 has significant amount of moisture, which
inhibits
the process to make a smooth synthetic roofing slate. Due to high moisture
content in
the formulation, later on which becomes steam during processing produces too
many
voids on the surface of the synthetic roofing slate. We controlled this in our
process
by adding desiccant/ moisture absorbent. By using this we need not to pre-
condition
the filler before feeding it to extruder.
5. Desiccant mentioned in claim 4 is metallic (calcium and or magnesium)
oxide. It does
not react with any of the ingredients into the formulation but absorbs the
moisture
from the formulation.
6. Synthetic roofing slate mentioned in claim 1 is light in weight making it
potentially
suitable for many construction uses as well as minimizing its transport costs
to
market.

7. Synthetic roofing slate mentioned in claim 1 has demonstrated an excellent
characteristics of durability, impact resistance and flexibility making it
potentially
suitable for many construction uses.

Description

CA 02297608 2000-02-O1
Specifications:
1. This invention relates to the manufacturing of a synthetic roofing slate.
2. Some attempts have been made in the past to simulate roofing slate, however
all previous
attempts have been met with problems. Cost of productions have been high
because of
methodology making the resulting product not commercially viable. The
composition of
the final product were not resilient enough to withhold weather and sun
exposure.
3. I have found that these disadvantages could be overcome by heavily filling
a thermoplastic
resin forcing it through a extruder into a mold and cooling it to ambient
temperature.
This process will mimic almost perfectly a slate roofing tile as defined in
claim 1.
4. Sizes of production will be many, and will duplicate the sizes of roofing
slate for both the
North American and European market. The minimum size in inches will be 8x16"
increasing
to 8x18" 8x20", 8x22", 8x24", 10x18", 10x20", 10x22", lOx 24", 12x20", 12x22",
12X24",
being the maximum size.
For European production the sizes will be as fallow: 20x40 cm., 20x45, 20x50,
20x55,
20x60, 25x40, 25x45, 25x50, 25x55, 25x60, 30x50, 30x55,30x60cm.
Every tile will be perforated at the top on both side 3 inches from the top
and 2" in from
both side.
The tiles will be tapered from the top down, with a starting thickness of 1/8
of an inch at
the top and gradually increasing to 1/4" at the bottom.
The top section of the tile will be slightly wider at the top than at the
bottom as defined in
claim 3. > See drawings #2.
5. The embodiments of the invention in which an exclusive property or
privilege is claimed
are defined as follows: a mixture of products including 50 to 70% of gypsum or
a blend
of gypsum and dolomite, 10 to 25°~ of recycled grounded tires, 5 to 15%
recycled
grounded glass and or a mixture with fiberglass. This aforesaid mixture will
represent 80%
of the total mixture. 15 to 20°~ polyethylene or polyvinylchloride
resin, will be added with
2% carbon black and or other colouring elements to produce the synthetic
roofing tile in a
range of colour similar to the roofing slate colours.
The chemical composition will also allow for added ingredients that will
stabilize the resin
and keep the product stable to UV exposure ,water, acid rain, and freeze and
thaw cycles.
The ingredients added to the mixture could include: Fusabond, Chimasorb,and
Irganox.
The quantities in which these ingredient would be incorporated to the masker
blend would
be less than 5% of the overall recipe. The mixture of all ingredient will be
blend into a
master blender similar to Brabender Prep mixer equiped with roller blades for
blending at
150* C for 30 minutes (temperature and blending time may vary up to 20%
de~nding of
exact composition of the formulation.)
This blend will then be extruded into a mold and compressed in order to fill
the cavity,
cooled until rigid and ejected from the mold for final cooling as defined in
claim 4.

Dessin représentatif