FEUILLE DE PLASTIQUE NON GLISSANTE ET SON UTILISATION COMME COUVERTURE DE PROTECTION POUR GRUMES

PLASTIC SHEETING WITH ANTISLIPPING MEANS AND USE THEREOF AS A PROTECTIVE COVER FOR TIMBER STACKS

Abrégé anglais

PLASTIC SHEETING WITH ANTISLIPPING MEANS AND USE
THEREOF AS A PROTECTIVE COVER FOR TIMBER STACKS
Abstract of the Disclosure
A plastic sheeting has antislipping means in the
form of a discontinuous surface layer consisting of
a mixture of asphalt, filler and a mixture of an ethylene
butyl acrylate copolymer and bitumen. The sheeting may
be an ethylene or propylene plastic sheeting. The plastic
sheeting is used as a protective cover for stacks of
timber.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A plastic sheeting with antislipping means,
characterized in that the antislipping means (12) consists
of an applied discontinuous layer (12) of a mixture of
asphalt, filler and a mixture of ethylene copolymer and
bitumen.
2. A plastic sheeting as claimed in claim 1, wherein
said sheeting is an ethylene or propylene plastic sheeting.
3. A plastic sheeting as claimed in claim 1 or 2,
wherein the antislipping means (12) has a surface coating
(13) of particulate material.
4. A plastic sheeting as claimed in claim 1 or 2,
wherein the antislipping means (12) has a surface coating
(13) of sand.
5. A plastic sheeting as claimed in claim 1 or 2,
wherein the asphalt is steam-refined asphalt.
6. A plastic sheeting as claimed in claim 1, wherein
the antislipping means (12) has a surface coating (13) of
particulate material, and wherein the asphalt is
steam-refined asphalt.

7. A plastic sheeting as claimed in claim 1, 2 or 6,
wherein the eythylene copolymer is a copolymer of ethylene
and butyl acrylate.
8. A plastic sheeting as claimed in claim 1, 2 or 6,
wherein the antislipping layer consists of a mixture of
about 50% asphalt, about 20% filler and about 30% of said
mixture of ethylene butyl acrylate copolymer and bitumen.
9. A plastic sheeting as claimed in claim 1, 2 or 6,
shaped to provide a protective cover for stacks of timber.

Description

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Nowadays, the stacks of limber in timber yards are
usually covered with plastic covers to prevent the timber
from getting wet. Such timber stacks may have a consider-
able length, for example 6 metros, a width of 5 metros
and a height of 1.5 or 2 metros. Labor safety authorities
require that such protective covers and plastic sheets
be provided with anti slipping means, and great efforts
have been made to provide suitable anti slipping means,
for example by embossing the plastic sheeting or in some
other manner. However, prior art plastic sheetings for
this purpose nevertheless have been unable to prevent
slipping accidents.
It therefore is an object of this invention to
provide a plastic sheeting with improved anti slipping
means. Another object of the invention is to provide
such a plastic sheeting for use as a protective cover
for timber stacks.
In earlier attempts at providing plastic sheetings
with anti slipping means in the form of applied layers
of a material having a higher friction, it was found
difficult to anchor the anti slipping layer to the plastic
sheeting. For timber stacks, use is made in most cases
of a polyethylene sheeting which has adequate strength
characteristics for such purpose. However, it is difficult
to achieve satisfactory adhesion of other materials
to an untreated polypropylene or polyethylene sheeting,
which is only natural because polyethylene and polyp
propylene frequently are used as release layers, for
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example in connection with asphalt products, such as
roofing materials. However, it has now been discovered
that it is possible to provide plastic sheetings with
a strongly adherent material having high anti slipping
ability, if this material is formed of a special type
of asphalt mix, i.e. a mixture of asphalt, filler and
a mixture consisting of an ethylene bottle aerylate co-
polymer and bitumen. Such an asphalt mix may be applied
to a plastic sheeting, even a polyethylene or pulpier-
pylon sheeting, with undiminished adhesive power also
at such low temperature conditions as may occur in con-
notion with protective covers for timber sleeks. The
mixture of copolymer and bitumen preferably is such
a mixture of ethylene bottle aerylate eopolymer and
bitumen as is commercially available from BASS AGO Federal
Republic of Germany, and the trademark LUCOBIT~ 121~.
According to the producer s specifications, this is a
plastic material consisting of a mixture of ethylene bottle
aerylate copolymer and a special bitumen. This material
has the characteristics of a thermoplastic material
and may be extruded, injection mounded and compression
mounded by means of conventional plastic processing
machines. the material is a tough elastic compound having
high tensile strength, a brittleness range of below
-30C, and a softening range of about 80-100C.
If such a eopolymer is mixed with steam-refined
asphalt and a filler, in particular talc, there is obtained
a coating compound which, in the hot state, can be spread

US
on polyethylene or polypropylene sheetings in the form
of individual spots or strips. In connection with such
an application the free surface of the anti slipping
compound may optionally be provided with a rolled-in
layer of a particulate material, especially sand, although
this is not necessary. Suitable mixtures of the asphalt,
the talc and the said compound of ethylene bottle acrylate
copolymer and special bitumen may comprise about 50%
asphalt, about 20% talc and about 30% LUCOBIT~. A compound
that has proved to give a very good anti slipping pro-
section on timber stacks comprises 28% LUCOBIT~, 19%
talc H200 and 53% asphalt B120 (softening point 45 C
and penetration 120 mm/10).
In the accompanying drawing
Fig l is a schematic section of a timber stack
covered with a plastic sheeting according to the in-
mention; and
Fig. 2 is a schematic section on a larger scale
of a portion of the anti slipping parts of the sheeting.
Thus, Fig. l illustrates a timber stack 10, covered
with a sheeting if which, in the embodiment illustrated,
is provided with anti slipping spots 12 at least within
those parts of the sheeting which form the upper walkway
on the stack. Fig. 2 illustrates on a larger scale a
section of the said anti slipping portion of the sheeting.
The sheeting if thus has elongate spots 12 of an anti-
slipping material, and in the embodiment illustrated
the surface of the anti slipping material 12 carries

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a thin layer lo of sand or other particulate material.
However, such a layer is not absolutely necessary, although
i-t may be advantageous because the sheeting is stored
in rolled-up condition.