PANNEAUX EN POLYMERE RESISTANT AUX INTEMPERIES

WEATHER-RESISTANT POLYMERIC CONSTRUCTION BOARDS

Abrégé anglais

Abstract of the Disclosure

Weather-resistant construction board consisting of
a) a basic layer of impact-resistant polystyrene or ABS
b) an elastic intermediate layer made of polyurethene,
polyester, polystyrene-butadiene copolymers, soft poly-
vinyl chloride or ethylene-propylene terpolymer rubber,
and
c) a weather-resistant covering layer of a polyacrylate.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A weather-resistant board comprising a) a base layer of an impact-
resistant polystyrene or acrylonitrile-butadiene-styrene polymer; b) an
elastic intermediate layer of polyurethane, polyester, a polystyrene-
butadiene copolymer, soft polyvinyl chloride or an ethylene-propylene
terpolymer rubber and c) a weather-resistant polyacrylate covering layer.

2. A board as claimed in claim 1 in which the base layer is from
1.8 to 5 mm in thickness.

3. A board as claimed in claim 1 in which the elastic intermediate
layer is from 0.05 to 1 mm in thickness.

4. A board as claimed in claim 1, 2 or 3 in which the weather-resistant
covering layer is from 0.05 to 0.3 mm in thickness.

5. A board as claimed in claim 1, 2 or 3 in which the base layer
comprises a graft polymer consisting of styrene and acrylonitrile, grafted
on a diene rubber.

6. A board as claimed in claim 1, 2 or 3 in which the intermediate
layer comprises a thermoplastic polyurethane which can be extruded.

7. A board as claimed in claim 1, 2 or 3 in which the covering layer
comprises polymethyl methacrylate.

8. A board as claimed in claim 1, 2 or 3 in which the base layer
comprises a graft polymer consisting of styrene and acrylonitrile, grafted
on a diene rubber, the intermediate layer comprises a thermoplastic
polyurethane which can be extruded and the covering layer comprises
polymethyl methacrylate.




9. A board as claimed in claim 1, 2 or 3 which has been prepared by
co-extrusion of the layers.

10. A board as claimed in claim 1, 2 or 3 which has been prepared by
producing the individual layers separately, and pressing them together to
form a composite board.

Description

1053'~20

Construction boards made of synthetic resins which have
high impact strength, e.gO impact-resistant polystyrene and
acrylonitrile-butadiene-styrene polymers, are already known.
They are generally unsuitable for use outdoors because they
are not weather-resistant.
It has therefore already been attempted to cover such
boards with a thin weather-resistant protective coating, e.g.
of a polyacrylate or polymethyl methacrylate. All suitable
weather-resistant protective coatings, however, are brittle.
When a board covered with such a protective coating is
bent so that the coating is put under tension, the coating
cracks and the crack is transmitted to the board itself al-
though it is made of elastic and impact-resistant material.
Boards of this kind are therefore of limited use.
This invention relates to a weather-resistant construc-
tion board comprising
a) a basic layer of high impact polystyrene or acrylonitrile-
butadiene-styrene polymer, preferably 1.8 to 5 mm in
thickness,
b) an elastic intermediate layer, preferably 0.05 to 1 mm
in thickness made of polyurethane, polyester, polystyrene-
butadiene copolymers, soft polyvinyl chloride or ethylene-
propyiene terpolymer rubber and
c) a weather-resistant covering layer of a polyacrylate,
preferably 0.05 to 0.3 mm in thickness.
The basic layer preferably comprises an ABS polymer
(acrylonitrile-butadiene-styrene ~olymer~, most preferably a
graft polymer consisting of styrene and acrylonitrile grafted
on a diene rubber (e.g. polybutadiene or styrene-butadiene co-
polymer). A (graft ABS) styrene-acrylonitrile copolymer may

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be added to this graft polymer if desired.
The intermediate layer preferably comprises a thermopla-
stic polyurethane which can be extrudedO
The top layer preferably comprises polymethyl methacry-
late.
The boards may be produced e.g. by co-extruding the
layers or by producing the individual layers separately and
then pressing them together to form a composite board.




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~xam~le.
1. Moulding materials used
extruded graft ABS boards 4.5 mm
extruded polyurethane resin. 0.15 mm
acrylate film 0.075 mm

2. Manufacturing process
pressed to form boards with a total thickness of 4.4 mm
at a temperature of 150 to 180C and a pressure of 10 to
25 MPa applied for 5 to 9 minutes.

3. Results
3.1 Impact strength test
3,1.1 Acrylate film under pressure, 10 samples tested without
intermediate layer, 8 samples not broken, two samples
broken at an impact of 71
m
with intermediate iayer 9 samples not broken 9 times,
one sample broken at an impact of

3.1.2 Acrylate film under tension, 10 samples tested without
intermediate layer 10 times, all samples broken at
14.47 (average value) k
m
with intermediate layer no sample broken.
3.2 Test for penetration
3.2.1 Acrylate film in pressure zone damaging maximum
energy energy
without intermediate layer
total thickness 4.35 mm 18.6 ~ 24.4 J
with intermediate layer
total thickn~ss 4.39 mm 1807 J 24~0 J
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3.2.2 Acrylate film in tension zone
without intermediate layerdamaging maximum
energy energy
total thickness 4.39 mm 604 J 6.4 J
with intermediate layer
total thickness 4.45 mm 21.5 J 31.8 J

3.3 Test for strength of bond between layers (not determinable
as the bonding strength between the layers is greater than the
strength of the adhesion points necessary for carrying out the
test).




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