SAC DE SECURITE

SECURITY SACK

Abrégé anglais

A security sack comprising at least one kraft paper ply and at least one light-
proof
paper ply impregnated with carbon and used either on its own or as part of a
lamination.

Revendications

4
Claims
1. A security sack comprising at least one kraft paper ply and at least one
light-
proof ply, characterized in that the light-proof layer comprises at least one
paper
ply impregnated with carbon.
2. A sack according to claim 1, characterised in that the material comprises
two
kraft paper plies.
3. A sack according to claims 2, characterised in that it comprises the light-
proof ply between the kraft paper plies.
4. A sack according to any of the foregoing claims, characterised in that the
light-proof ply comprises two paper layers and a carbon layer between them.
5. A sack according to any of the foregoing claims, characterised in that the
light-proof ply is provided with an earthing probe.
6. Use of a sack according to any of claims 1 to 5 for light sensitive or
photosensitive materials, or for products sensitive to static electricity.

Description

CA 02352922 2001-09-25
1
SECURITY SACK
Field of the invention
This invention relates to light-proof security sacks comprising at least one
kraft
paper ply and at least one ply impervious to light. The sacks can be used e.g.
for
storing and transporting materials which have to be protected from light.
Background of the invention
Many materials need to be protected from light during storing, transport or
handling. Such materials are e.g. light sensitive and photosensitive papers
and films,
many food products, and also many sensitive products of high technology.
In light-proof paper-based sacks, a black plastic film is usually used. Also
papers
with aluminium foils are used. One drawback of these materials is that they
cannot
be comfortably destroyed or recycled with paper material.
Summary of the invention
The main object of the invention is to provide a paper sack which has good
light-
proof properties but which is also easy to recycle or destroy. The invention
and
some embodiments thereof are defined in the patent claims.
According to the invention, the sack comprises at least one kraft paper ply
and at
least one paper ply impregnated with carbon. The carbon impregnated ply
provides
imperviousness to light, and the kraft paper ply provides especially
mechanical
strength.
The sacks can be manufactured from paper webs by applying conventional
techniques. The sacks can be used for the storing and transport of any goods
which
need to be protected from light or from unauthorised scanning.
Alternatively, the carbon impregnated paper ply can be used as part of a
laminate
comprising at least one paper layer and at least one carbon impregnated layer
laminated on one of the paper layers. The ply may comprise e.g. paper layer
and
one carbon impregnated layer, or two paper layers and a carbon impregnated
layer
between them. The carbon impregnated ply may also be coated on one or both
sides
to form a carbon-cored ply. Carbon impregnated papers are commercially
available.

CA 02352922 2001-09-25
2
The sack may comprise several kraft paper plies. The sack may comprise e.g.
two
kraft paper plies and a carbon impregnated ply or laminated paper ply between
them.
The sack can be easily recycled, if desired. The carbon can be removed in a
similar
way as the carbon black of printing inks. The sack can also be easily burnt or
composted with other paper waste, if desired.
The carbon laminated paper ply will also aid the dissipation of static
electricity.
This will enable the sacks to be more safely used for materials which have a
risk of
self combustion due static discharge or which may be damaged by static
electricity.
The carbon impregnated ply or laminate can be earthed by a suitable probe to
equipments with sufficient conductivity: Such discharges may especially occur
when the sacks are filled with powder or granular material.
The sack can be made permeable to air. This may be necessary e.g. when storing
certain food products like vegetables.
The sack can also be made permeable to moisture. Thus water condensed inside
the
sack can be removed through the sack.
The sack can be scanned by security type X-ray equipment to prevent misuse.
The sacks will also have a tamper-evident feature as any attempt to gain
access
cannot be repaired or disguised, especially when the carbon impregnated paper
ply
is used as a lamination or a carbon-cored ply. This is an additional property
that
could assist on the proffered security. However these packing materials can be
in
certain circumstances too dense or light protection is not efficient enough;
e.g. when
storing vegetables a packing material must be at same time breathable and
light
proofing.
Brief description of the drawing
Fig. 1 is a general view illustrating the security sack in accordance with
this
invention.
Description of the preferred embodiments
Referring to the drawing, there is shown a general view of the security sack
in
accordance with this invention. The security sack of the embodiment of the
present
invention comprises of one kraft paper ply (1) and one carbon impregnated
paper

CA 02352922 2001-09-25
3
ply (2). These two plies of paper are laminated together to form a light-proof
and
strong paper ply.
To manufacture the security sack according this invention, first the laminated
paper
ply is cut in a shape of a horizontal rectangle. This horizontal rectangle is
then
S folded inwards along the vertical corner folds (3) 'and outwards along the
vertical
center folds (4)~. These vertical center folds (4) allow the security sack to
be stored
flat, and when the security sack is used, they allow the body of the security
sack to
expand in volume. After the folding of the vertical folds, the vertical edges
of the
laminated paper ply are joined together along the vertical seam (5) to form
the body
of the security sack. Vertical edges are joined together preferably with glue
or other
adhesive material.
After the body of the security sack is formed, the bottom of the security sack
is
formed by folding the bottom part of the body along the horizontal bottom fold
(6).
The bottom fold (6) can consist of several horizontal folds to increase the
durability
of the security sack. After the folding of the bottom part, the lower
horizontal edge
of the body is joined together with the body of the sack along the horizontal
seam
(7) with glue or other adhesive material.
In the upper part of the security sack there is left an opening (8) for
inserting objects
in to the security sack. The edges of this opening can also be provided with
glue or
other adhesive material to ease the sealing of the security sack.
It is evident for one skilled in art that the present invention is not limited
to the
foregoing description, but includes that contained in the claims. For example
the
security sack of the present invention can vary in shape and in size. It can
have
several or none center folds and the bottom of the security sack can be formed
by
glueing the edges of the bottom part of the body together.

Dessin représentatif