Note: Descriptions are shown in the official language in which they were submitted.
WO93/1098~ 2 i 2 ~1 3 'I 1 PCT/DK92/0036-
A tarpaulin provided with a decoration of a reflecting
material and a method of making it
__________________________________________________________ :
The invention concerns a tarpaulin comprising a fabric
coated with a plastics material, preferably PVC, polyamide
- or polyprene, and provided with a reflecting decoration, as
well as a method of providing a tarpaulin with such a
reflecting decor~tion.
Today tarpaulins usually consist of a fabric coated with a
plastics material, The fabric must be strong and dura~le and
is therefore most frequently made of polyester. The plastics
coating must likewise b~ strong and durable, and it must
moreover have a certain toughness and flexibility. It is
mostly made of PVC or of a polyamide, such as nylon or
aramide, or a polyprene, such as chloroprene rubber.
Tarpaulins are used for many cover purposes, e.g. within the
building industry, and in particular for covering trucks.
They are also used for making larger tents, e.g. for use in
temporary military quarters and refugee camps as well as for
puolic events.
It is common practice to print logos, company names,
slogans, instructions and other decorations on truck
tarpaulins, for informative and for advertising purposes.
I* would be a great advantage, both with respect to the
advertising value and the traffic safety, if such
decorations could be made of a reflectin~ material or could
be combined with reflecting stripes or patterns, e.g. alon~
the edges o~ the tarpaulins. In particular, this could
contribute to making the trucks visible at night when -the
usually ~ark tarpaulins are otherwise difficult to see.
According to UN rules on ~raffic sa~ety, ~rucks and trailers
are to be provided with rear truck planks, i.e. usually
aluminium plates with yellow reflection, downwardly on the
rear end. In yeneral, the ordinary rules are that rearward
WOg3~lo98~2~ Li~ PCT/DK92/003~,
reflectors are to be red, lateral reflectors to be yellow
and forward reflectors to be white. However, reflectors
arranged on the body or chassis of trucks will often be
coated with dirt, and even when visible they do not give a
S sufficient impression of the size of the vehicle.
- Various reflective materials may be considered for appli-
cation on tarpaulins. Paint or inks containing reflPcting
pigments ar~ not suitablè, partly because they are not
durable exposed to wind and weather. The best reflection
effect is obtained with so-called rPtroreflecting films or
sheets, of which substantially two types are known: One is
the glass bead type comprising a large number of fine glass
beads embedded with specular base in a plastics sheet. The
other is the prism (or cube corner) type with a large number
of prism-shaped depressions impressed in one surface of a
plastics sheet so that light from the other side is reflec-
~ed through the sheet. A naked prism type refle~ting sheet
must have free air at th~ rear side in order to reflect. A
more recent form of the prism type refle~ting sheet is
coated with a thin layer of metal such as aluminium on the
impressed surface in order to achieve an even better
reflection which is not dependent on the background. Another
recent form of the prism type reflecting sheet is a multi-
layer sheet provided with a sealin~ layer behind the air-
filled depressions.
.~
It has been attempted to glue a reflective transfer sheet
of the glass bead type on a truck tarpaulin, but it was not
durable, and the reflecting sheet rapidly flaked off.
A reflecting sheet of the naked prism type cannot be applied
at all in this manner, because there must be air on the rear
side (the impressed side) for it to reflect. The normal way
o applying a reflec~ing sheet of the prism type to a base,
e.g. a PVC -~heet, in order to seal the rear side is by high
frequency welding along ~he edge of the desired decora~ion
WO93/109$~ 2 i 2 fs e~ ~ ~ PCT/DK92/0()36-
and, in case of large surfaces, along crisscross lines to
divide the face into reflecting sections. Of course, this
requires that the reflecting sheet and the base are of the
same type or ara at least compatible so that they can be
welded together by fusion. A corresponding method can be
used for fixing a reflecting sheet of the glass bead type
- on a ba-~e if the sheet and the base are compatible. However,
it is not practical to use high frequency welding for fixing
reflecting sheets on tarpaulins, since this would require
that the entire tarpaulin was moved intermîttently through
the high frequency welding machine or the machine moved
intermittently along the tarpaulin carefully positioning the
welding tool in each step, which would be very cumbersome
with existing apparatus~ Further, a reflecting sheet of the
uncoated prism typa shows the highest reflection with a
white or light-coloured background, while tarpaulins often
have a dark colour, and a reflecting sheet of the metallized
prism type cannot be high frequency welded at all, because
the me~al layer reflects the microwaves.
A generally used method of fixing a reflecting sheet of the
glass bead type on a base is ~o provide the sheet with a
heat activatable glue on the rear side to provide a reflec-
tive transfer sheet and adhere it to the base by applying
pressure and heat. However, this method cannot be used on
tarpaulins, since these cannot be inserted into the existing
heat presses for this purpose, and there is no other appa-
ratus by means of which the necessary pressure and the
- necessary temperature and heating time on a tarpaulin can
be achieved.
A last po~sibility might be to sew the reflecting sheet on
the tarpaulin, but this would lead to holes in the tar-
paulin, which would make it leaky and would reduce its
streng~h.
21~il3'~ i
WO93/10~B~ PCT/DK92/003fi-
The object of the invention is to provide a tarpaulin whichis provided with a durable reflecting decoration, without
this reducing its strength in any manner, and to provide a
practicable method of providing a tarpaulin with such a
reflecting decoration.
- The tarpaulin of the invention is uni~ue in that it carries
a piece of reflect~ng sheet anchored to a piece of tarpaulin
cloth, whose plastics coating is of the same type as or is
compatible with that of the tarpaulin, by high fre~uency
welding or heat application, said piece of tarpaulin cloth
provided with reflecting sheet, optionally formed in a
desired shape, being appliad to the tarpaulin by hot air
fusion.
The ~ethod of the invention is uni~ue in that a reflecting
sheet is anchored to a piece of tarpaulin cloth, whose
plastics coating is of the same type as or is compatible
with that of the tarpaulin, by high fre~uency weldin~ or
heat application, and ~hen the piece o~ tarpaulin cloth
provided with reflectin~ sheet, optionally formed in the
desired shape, is applied to the tarpaulin by hot air
fusion.
The tarpaulin on which the reflecting decoration is applied
by the method of the invention, may e.g. be made of the
above-mentioned materials and preferably consists of a
polyester fabric coated with PVC. Such tarpaulins are
manufactured by e.g. Duratex A/S, Norgesvej 49, DK-6100
Haderslev, Denmark, under the trade mark "duralak"; by
~ammersteiner Kunststoffe GmbH, Rheinstrasse 11, D-5142
Huckelhoven, Germany, under the trade mark "Haku", and by
Sattler Textilwerke OHG, Sattlerstrasse 45, A-8041 Graz-
Thondor~, Austria, under the trade mark "Complan PVC". The
heaviness of the tarpaulin cloth will usually be 300-1500
g/m2, but it may also be more.
W093/1098~ ~ 12 ~-~ 3 ~ ~ PCT/DK92/003fi~
The reflecting sheet wnich is applied is expediently a
retroreflecting sheet of the glass bead type comprising a
lar~e number of fine glass beads embedded in a specular base
in a plastics sheet, or of the prism (cube corner) type with
a large number of prism-shaped depressions impressed in the
surface of a plastics sheet so that light is reflected
through ~he sheet and optionally coated with a thin layer
of metal such as aluminium on the impressed surface or
backed by a sealing layer. Retroreflecting sheets of the
glass bead type are manufactured i.a. by Minnesota Mini-ng
and Manufact~ring Company, 2501 Hudson Road, Saint Paul,
Minnesota 55101, U.S.A., under the trade mark "Scotchlite~
8710", and by Unitika Sparklite Co., Ltd., Chiyokawa-Cho,
Kameoka, Kyo~o, Japan, under the trade mark "Unitika MR
3501". Retroreflecting sheets of the naked prism type are
- manufactured i.a. by Reflexite Corp., 315 South Street, PØ
Box 1200, New Britain, CT 06050, U.S.A., under the trade
mark "Reflexite~ Vinyl IRE". Retroreflecting sheets of th2
metallized prism type are manufactured i.a. by Reflexite
Corp. under the trade mark "Reflexite~ AP 1000". Retro-
reflecting sheets of the sealed prism type are prepared i.a.
by Minnesota Mining and Manufacturing Company under the
trade mark "Scotchlite~ Diamond Grade" and ~y Stimsonite
Corp., 7542 N. Natchez Ave., Niles, IL 60648-3804, U.S.A.,
under the trade name "Stimsonite~ Series 4200". Preferably,
the reflecting sheet is a retroreflecting PVC sheet of the
naked prism type.
When the reflecting sheet consists of PVC or another thermo-
plastic material, which is compatible with the plastics
coating of the tarpaulin cloth, it is anchored to a piece,
e.g. a ~and, of tarpaulin cloth by high frequency welding.
' This is done most conveniently in an automatic high frequen-
cy welding machine, where a band o the reflecting sheet put
together with a band of tarpaulin cloth is moved intermit-
tently through and welded by means of a band tool, which
welds the reflecting sheet in narrow stripes longitudinally
~ ~ h~ L~
WO93/1098~ PCT/DK92/003
and transversely so that reflecting sections are formed. If
reflecting lo~os are to be applied, use is made of another
welding tool which welds along the contour of the logo and
is provided with a cutting edge which simultaneously cuts
out the welded logo. It is most practical that the machine
yields a power of 7-12 kW. Such high frequency welding
machines are available from e.g. Kif Parechoc S.A., l9 Rue
G.-H. Piguet, CH-1347 Le Sentier, Kanton Vaud~ Switzerland,
under the trade mark "Kifel"~, and from Evald A. Nyborg A/S,
Industriskellet 2, Vas~inger~d, DK-3540 Lynge, Denmark under
the trade mark "Weldan"~.
`:~
Retroreflecting sheets of the glass bead type or the metal-
lized or sealed prism ~ype may be difficult or impossible
to weld by hi~h fr~quency. Instead they can be applied to
a piece of tarpaulin cloth by means of an adhesive and
anchored to said piece and protected by placing a trans-
parent flexible film of a polymeric material compatible with
the plastics coating of said piece on top Qf the reflecting
sheet with its edges extending beyond those of the reflec-
ting sheet and high fre~uency welding it to the piece of
~arpaulin cloth along the edges. Then the piece of tarpaulin
cloth provided with reflecting sheet is applied to the
tarpaulin by hot air fusion.
Thus an embodiment of the tarpaulin of the invention
incorporating thPse types of reflecting sheet showing the
highest reflection is unique in that it carries a reflecting
sheet of the glass bead type or the metallized or sealed
prism type applied to a piece of tarpaulin cloth by adhesion
and anchored to said piece and protected by an overlying
-
transparent flexible film of a polymeric material compatible
with the plastics coating of said piece, the edges of said
ilm ex~ending beyond ~hose of the reflecting sheet and
being high frequency welded to the piece of tarpaulin cloth,
said piece being in ~urn applied to the tarpaulin by hot air
fusion.
-
WO93/109X~ 2 L ~ -~13 ~ 1 PCT/DK92/00~fi-
When the reflecting sheet is of the glass bead type with a
heat-activatable adhesive on the rear side, it can be
anchored to a piece of tarpaulin cloth by heat application.
This is done most conveniently in a conventional heat presse
for transfer of transfers, a piece of reflecting sheet put
together with a piece of tarpaulin cloth being heated to
120-180 C at a pressure of e.g. 276-310 kPa for 5-20 s.
Where reflecting bands are to be manufactured, the band of
reflecting sheet and tarpaulin cloth may be moved con-
tinuously through a heat presse with pressure bands, e.g.of the mark "Reliant", where they are subjected to the
above-mentioned temperature and pressure conditions with a
corresponding period of residence.
According to the invention, it is particularly expedient
that the piece of tarpaulin cloth provided with reflecting
sheet is applied to the tarpaulin by means of a hot air ap-
paratus, whose hot air jet is introduced between the under-
side of the tarpaulin cloth and the surface of the tarpaulin
so that the tarpaulin clsth is fused to the tarpaulin, with-
out the reflecting sheet being damaged. In this connection
it is best that the temperature of the hot air jet is 400 -
600 C, and the heating time and the pressure to be applieddepend upon the temperature and the type of thickness of the
material.
Hot air devices that may be used are known within the field
for applying reinforcing bands and edges in the manufacture
of tarpaulins and for application of patches and joints in
the repair of tarpaulins. However, in the past it was not
possible to apply reflecting sheets by means of such hot air
devices, ,~-,ince they would melt the sheet and destroy the
reflection effec~.
35 Such hot air devices are manufactured by Karl Leister Elek-
troger~tebau, CH-6056 K~giswil, Kanton Obwa}den, Switzer-
land, under the trade mark "Leister", both as hand devices,
WO93/l098~ 212 ~ 3 '~1 PCT/DK92/nO3~,
where the piece of tarpaulin cloth provided with reflecting
sheet is pressed firmly against the tarpaulin with a hand
roller af~er heating, and as rolling devicPs for applying
long bands of tarpaulin cloth, where the band provided with
5 reflecting sheet is adhered to the tarpaulin at each end, -:
the mouthpiece of the hot air device is inserted below the
- edge of the band, and the device is rolled along the band,
while a roller mounted on the device moves on top of the
band after the mouthpiece and presses the heated band firmly
10 against the tarpaulin. ~-
~ :
Although as men~ioned previously it is a very cumbersome
procedure to weld a compatible reflecting sheet directly to
a tarpaulin with existing high frequency welding apparatus,
and for some types of reflecting sheet it is in fact unfea-
sible, it has now been found according to the invention that
it is possible to apply a reflecting sheet of the glass bead
type or the metallized or sealed prism type directly to a
tarpaulin by means of an adhesive and anchor it to the
tarpaulin and at the same time protect it by placing a
tr~nsparent flexible film of a polymeric material compatible
with the plastics coating -of the tarpaulin on top of the
reflecting sheet with its edges extending beyond ~hose of
the reflecting sheet and hiyh frequency welding it to the
tarpaulin along the edges.
Therefore, another tarpaulin according to the invention is
unique in that it carries a piece of reflecting sheet of the
ylass bead type or the metallized or sealed prism type
applied directly to the tarpaulin by adhesion and anchored
to the tarpaulin and protected by an overlying ~ransparent
flexible~film of a polymeric material compatible with the
plastics coating of the tarpaulin, the edges of said film
extending beyond those of the reflecting sheet and being
high frequency welded to the tarpaulin.
W093/l098~ 2 ~ ~ 13 ~ 1 PCTtDK92/003fi-
~he transparent flexible film tO be used in the last men-
tioned embodiments of the tarpaulin of the invention must
be made of a polymeric material compatible with the plastics
coating of the piece of tarpaulin cloth and the tarpaulin,
respectively, and it should be tough, weather resistant and
UV stabilized and have a smooth surface. The transparent
flexible film may be colourless, or it may be coloured e.g.
yellow, red or other desired colour to produce coloured
reflections. ~
' . :
The invention also provides a piece of tarpaulin cloth to
which a reflecting sheet is anchored by high frequency
welding or heat application to be applied as a reflective
decoration to a tarpaulin by hot air fusion.
The previously mentioned types of reflecting sheet may be
used in this piece of tarpaulin cloth, the preferred type
being a retroreflecting PYC sheet of the naked prism type.
A special embodiment of this piece of tarpaulin cloth has
a reflecting sheet of the glass bead type or the metallized
or sealed prism type applied to it by adhesion and anchored
to it and protected by an overlying transparent flexible
film of a polymeric material compatible with the plastics
coating of said piece, the edges of said film ex~ending
beyond those of the reflecting sheet and being high frequen-
cy welded to said piece.
The piece of tarpaulin cloth furnished according to the
invention is advantageously in the form of a narrow band
which may be wound up in a roll and unwound during the
applicat~on to the tarpaulin by hot air fusion.
In the drawings, Figure 1 shows how a band of reflecting
shee~ 2 and a band of tarpaulin cloth 3 from their respec-
tive rolls are moved together through a high frequency
welding machine 1 and emerge as a reflec~ive band of
W093/l098~ 2 ~ 2 4 3 l~ 1 PCT/DK92/00367
iO
tarpaulin cloth 4 and wound in a roll. The machine is also
provided with a cutting tool 5 cutting suitable lengths of
~he reflective band, preferably in a weld.
Figure 2 shows fusion of a reflective band 4 on a tarpaulin
6 by mPans of a travelling hot air apparatus 7. The figure
~ shows a fused piece of tarpaulin cloth with reflecting logo
Figure 3 shows how bands of reflection shaet 2 and bands of
transparent PVC film 4 having a slightly lar~er width than
2 are laid down, 4 on top of 2, on bands of tarpaulin cloth
3 h~vi.ng at least the same width as 4 and are pressed
together by rolls with moderate heating 6 whereafter the
aggregatP bands are moved through a high frequency welding
machine l in which the PVC film is welded to the tarpaulin
cloth alon~ the edges extending beyond the edges of the
reflection sheet, and emerge as reflective bands S which are
wound in rolls. The starting bands of reflecting sheet 2 may
be supplied with a protecting band of silicone paper which
is the:n drawn off and wound in rolls 7.
Figure 4 shows how a reflective band 2 of tarpaulin cloth
according to the inven~ion is applied to a tarpaulin 1
mounted on a truck, by means of a hot air device 3 with a
built-in roll of reflective band.
EXAMPLE 1
~ roll of reflecting sheet of the naked prism type, "Reflex-
ite~ Vinyl IRE", was high frequency welded on a roll of
tarpauIin~ cloth with a PVC coating, "duralak", in a high
requency welding machine, "Kifel"~, with a power of 12 kW,
as shown in Fig. 1. The reflecting sheet is usually avai-
lable in rolls with a width of 9" (229 mm) or 27" (686 mm),
and the roll of tarpaulin cloth is cut in the same or
WO93/1098~ 2 ~13 ~1 PCT/DK92/003fi-
slightly greater width from a tarpaulin roll with a normal
width of 1400-2000 mm.
The band of tarpaulin cloth with welded reflecting sheet is
placed on a tarpaulin of the mark "duralak" and fixed at
each end with staples. It is fused on the tarpaulin, as
shown in Fig. 2, by inserting the mouthpiece o~ a travelling
hot air apparatus of the mark "Leister" from the side
inwardly below the edge of the band with the roll on top of
the band, and the apparatus is moved along the band, while
hot air a~ a temperature of 400-600 ~C is blown below it.
The roll presses the fused surfaces together SQ that this
side of the band is welded to the. tarpaulin. Then the
procedure is repealed on the opposite side of the band.
The tarpaulin is thus provided with a reflective band which
works homogeneously with the tarpaulin a~ stretching, tempe-
rature changes, high pressure flushing and the like and
lasts for the life of the tarpaulin.
~0
EXAMPLE 2
A band of polyester metallized prism type reflecting sheet,
"Reflexite~ AP 1000", is applied to a wider band of tar-
paulin cloth with a PVC coating, "duralak", by means of asemiviscous PVC adhesive. On top of the reflecting sheet is
applied a transparent, colourless or coloured, flexible PVC
film of a slightly larger width than the band of reflecting
sheet with its edges extending beyond those of the reflec-
ting sheet, and the film is adhered to the re1ecting sheetby moderat,e heating while pressing out any air bubbles. The
band of tarpaulin cloth is most preferably white when the
transparent film is colourless or else the same colour as
the transparent ilm for "cosmetic" reasons.
WO93/1098~ 2 i 2 ~13 ~ 1 PCT/DK92/003
'2
Thereafter, the aggregate band is moved through a high fre-
quency welding machine, "Kifel"~ in which the transparent
PVC film is welded to the tarpaulin cloth along the edges.
When the resulting reflective band is applied to a tarpaulin
by hot air fusion and is cut off at the ends, the end por-
- ~ions may be sealed by fusing a strip of plain tarpaulin
cloth or transparent PVC film across the end portion.
Another solution may be to stamp out and peel off about 1
cm of reflecting he t from the liner of silicone paper f~r
each standard length of reflecting sheet before it is
applied to the band of tarpaulin cloth, thus preparing
lateral stripes to be welded in the high frequency welding
machine.
