Packaging for photographic paper

Daylight loading packaging for photographic paper in the form of rolls comprising lateral, annular flanges and a casing lengthening piece welded to the flanges, which casing lengthening piece is connected at one end to the start of the paper roll and is free at the other end, the flanges presenting a concentric annular hole the edge of which is welded to the edge of the roll tube and which on one side of a paper base has at least one blackened layer forming a light barrier, at least one aluminium layer forming a vapour barrier, at least one layer which increases resistance to puncture, and furthest away from the paper base a layer which permits welding to the casing lengthening piece and the roll tube, and which has on the other side of the paper base a layer of a synthetic polymer applied by extrusion which imparts a tension to the material which prevents an inward collapse of the flange (seen from the roll).

BACKGROUND OF THE INVENTION 
Photographic paper is frequently used in the form of large rolls the width 
of which corresponds to the width of the desired photo format, e.g. 7, 10, 
13 cm etc. The rolls are packed so that they are light-tight. In order to 
be able to use them, they are usually placed in a cassette which is 
attached to the processing machine. In order to prevent any pre-exposure, 
including pre-exposure of the edges of the photograph, the paper roll must 
be placed in the cassette with the packaging material removed in the dark. 
Placing the paper roll in the cassette in the dark is cumbersome, 
error-prone and frequently impossible, for example in so-called minilabs, 
as these processing machines are frequently installed in restricted areas 
where there are no rooms in the immediate vicinity that can be darkened. 
In order to remedy this shortcoming day-light loading packaging (DLL from 
"day-light-loading") has been developed, whereby the roll is placed in the 
cassette together with the packaging material. This packaging is 
structured as follows: 
The photographic paper is wound onto a round paper tube. A round, opaque 
flange, corresponding in size to the size of the roll and with a round 
opening in the centre corresponding to the tube, is attached to the right 
and left respectively and welded to the edge of the tube along its 
opening. An opaque casing lengthening piece is sealed to the end of the 
photographic paper, wound round the photographic paper and welded at its 
edges to the round edges of the flanges. 
The assembly is placed in the cassette in such a way that the free end of 
the casing lengthening piece projects from the opening of the cassette. 
After being placed in the cassette the casing lengthening piece is loosened 
at the weld seams from the flanges by pulling at the end of the casing 
lengthening piece which projects out of the cassette opening and pulled 
out of the cassette. The cassette can then be docked in the printing 
device and printing can commence. 
The material for the flanges is made up of several layers: 
On the outside, for example, a layer of paper about 130 .mu.m thick is 
provided to form the base; there follow at least one blackened layer 
forming a light barrier, at least one aluminium layer forming a vapour 
barrier, at least one layer which increases resistance to puncture and 
furthest away from the paper base a layer which permits welding to the 
casing lengthening piece respectively the paper tube. The subsequent 
layers on the paper have a total thickness of 120 .mu.m for example. 
Even though this packaging meets all the requirements for easy handling, 
light-tightness and resistance to puncture, it has a serious disadvantage 
in that, in the case of some exposure machines (printers), once the 
photographic paper is largely unwound, the outer regions of the flanges 
collapse inward and are wound in with the photographic paper when it is 
re-wound. Apart from the possible damage, the winding diameter of the 
photographic paper rollers becomes larger as a result than the associated 
paper length. Defective residual lengths are then reported in printers 
with residual length definition. 
SUMMARY OF THE INVENTION 
The object of the invention was to avoid this disadvantage. 
This object is achieved in that a layer 20 to 60 .mu.m thick for example of 
synthetic polymer is applied by extrusion externally to the paper base of 
the flanges. This layer, which is preferably of polyethylene, imparts a 
tension to the material which prevents the inward collapse of the flange. 
The plastic layer is preferably 30 to 50 .mu.m thick and is made of HDPE 
(high density polyethylene). 
In a preferred embodiment a heat-resistant paint is also applied to the 
polymer layer, in order to prevent the polymer layer from melting when the 
flange and casing lengthening piece are welded together.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 illustrates photographic paper wound onto a paper tube 4 to thereby 
provide daylight loading packaging 1. The photographic paper is covered by 
a casing lengthening piece 3 commonly called "light-shielding leader". The 
opposite sides of tube 4 include flanges 2. 
FIG. 2 illustrates the cross-section of one embodiment of the flange 
material. Specifically, a paper support 5 is covered on one side by a 
blackened layer forming a light barrier 6, an aluminum layer forming a 
vapor barrier 7, a layer which increases resistance to puncture 8 and a 
layer 9 which permits welding or otherwise securing the flanges 2 to 
casing lengthening piece 3. In this particular embodiment there are two 
additional blackened layers 6. The other side of the paper support 5 
includes a layer 10 of a synthetic polymer. The application of layer 10 
imparts a tension to the flange material which pervents an inward collapse 
of the flange. Layer 10 may be covered by a heat-resistant paint 11 which 
represents the outside 12 of the flange material.