Method for preventing cohesion between carton blanks

An improved method of preventing cohesion between plastic coated, paperboard, folding carton blanks after they come off a die cutter or cutting section of a press. The method comprises providing different scoring patterns for the carton blanks of alternate rows as the cartons are formed, which results in the creation of air spaces between adjacent cartons to prevent them from sticking to each other.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the manufacturing of paperboard folding cartons, 
and, more particularly, to a method of preventing cohesion between plastic 
coated, paperboard, folding carton blanks when they stacked after coming 
off a web-fed die cutter or cutting section of a press. 
2. Description of the Background Art 
A background art search directed to the subject matter of this invention 
conducted in the United States Patent and Trademark Office disclosed the 
following United States Letters Patent: 
U.S. Pat. Nos. 4,559,259, 4,575,298, 4,761,320, 5,178,377. 
None of the patents found in the search discloses a method of preventing 
cohesion between plastic coated, paperboard, folding carton blanks when 
they come off a die cutter or cutting section of a press by providing 
different scoring patterns for the carton blanks of alternate rows as the 
cartons are formed. 
SUMMARY OF THE INVENTION 
It is a primary object of the invention to provide a method of preventing 
cohesion between plastic coated, paperboard, folding carton blanks when 
they come off a web-fed die cutter or cutting section of a press. 
A more specific object of the invention is the provision of different 
scoring patterns for the carton blanks of alternate rows as the cartons 
are formed on a web-fed die cutter or cutting section of a press.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
When plastic coated, paperboard, folding carton blanks come off a die 
cutter or the die cutting section of a web-fed press, they are 
automatically stacked vertically one atop the other. Unlike uncoated 
blanks, blanks coated on both sides with a plastic film tend to stick to 
each other by cohesion and/or because of a partial vacuum between adjacent 
blanks. 
In FIG. 1 there is illustrated a stack of conventional, plastic coated, 
unscored, paperboard, folding carton blanks identified as CUB. It is 
apparent that there is no space between adjacent blanks. In order to 
overcome the problem of blanks sticking to each other, it has been a 
common practice to apply an offset spray powder between adjacent blanks. 
This requires costly application equipment and is a relatively messy 
operation in the carton manufacturer's plant, as well as in the plant of 
the manufacturer's customer. 
The present invention provides a simple, inexpensive way to overcome the 
sticking problem. This is accomplished by providing special stacking 
scores in the blanks, wherein the patterns of these special stacking 
scores are different for alternate blanks as they come off a press or die 
cutter and are stacked one atop the other, to create air pockets or spaces 
between adjacent blanks. 
In FIG. 2 there is illustrated a stack of carton blanks embodying features 
of the invention. The stack of invention blanks comprises blanks BA, of 
the type illustrated in FIG. 3, and blanks BB, of the type illustrated in 
FIG. 4. The blanks BA and BB are alternately arranged on a stack as 
illustrated in FIG. 2, so that no blank is adjacent an identical blank. 
Thus, it is apparent that spaces are provided between adjacent blanks, by a 
method hereinafter described, so that adjacent blanks will not cohere or 
stick to each other. 
As best seen in FIGS. 3 and 4, while blanks BA and BB are similar to each 
other in that all of the working scores and cut lines are the same, there 
are provided additional special scores in each blank in accordance with 
the teachings of the present invention. The patterns of these special 
scores of alternately formed blanks are different from each other. 
Each of the blanks comprises: a main or bottom wall panel 6; a pair of 
front and rear side wall panels 8, foldably joined to front and rear side 
edges of bottom wall panel 6; a pair of end wall panels 10, foldably 
joined to opposed end edges of bottom wall panel 6; gusset members 12 at 
the corners of the blank, foldably interconnecting each side wall panel to 
a related end wall panel; a top wall panel or cover 14, foldably joined to 
a rear side wall panel; a front dust flap, foldably jointed to a front 
side wall panel; and a pair of end dust flaps, foldably joined to related 
end wall panels. The various panels of each blank are foldably joined to 
each other along fold lines by conventional working scores. 
These conventional working score, as well as necessary cut lines in the 
blanks are not identified by numerals or described in detail, as they are 
not part of the invention. In fact the cartons shown in the drawings are 
for illustrative purposes only, because the invention can be used with 
carton blanks of various shapes and sizes. 
Still referring to FIGS. 3 and 4, it will be seen that blank BA is provided 
with two sets of special stacking scores. Panels 6 and 14 are provided 
with a first set 20 of special stacking scores that are chevron-like or 
V-shaped, and panels 18 are provided with a second set 22 of special 
stacking scores that include a plurality of spaced parallel lines. 
In the case of blank BB, the special V-shaped scores 120 in panels 6 and 12 
are similar to scores 20 in blank BA, except that they run in opposite 
directions from the comparable scores of blank BA. Likewise special scores 
122 in panels 18 are similar to special scores 22 of blanks BA, except 
that they run in opposite directions from those of blank BA. Thus, when a 
blank BA is placed above or below a blank BB, as seen in FIG. 2, spaces 
are provided between adjacent blanks to prevent them from nesting snugly 
and sticking to each other. 
The scores can be formed by standard scoring equipment and can be formed on 
either side of the blanks, so as to be either embossed or debossed. 
The method by which these alternate scoring patters is best understood by 
reference to FIG. 6 of the drawings. As the web Wp of plastic coated 
paperboard moves along the die cutter or the cutting section of a press, 
it travels over a chase or frame 30 containing a pair of adjacent first 
and second rows of dies 32 and 32". Each die row includes a plurality of 
die positions or stations. The dies or die positions of row 32 are 
indicated at DA1, DA2, DA3, DA4, and DA5; whereas the dies or die 
positions of row 32" are indicated at DB1, DB2, DB3, DB4, and DB5. 
The chase and dies may be of any conventional design commonly used in the 
production of paperboard folding cartons. As seen in FIG. 6, chase 30 is a 
rectangular frame adapted to hold a plurality of dies which are generally 
placed in the chase by a diemaker or pressman. Each die usually consists 
of a flat block of wood or plastic within which is inserted a plurality of 
metal strips, such as 42 and 42", which are known as scoring rules or 
cutting bars. 
If necessary, dies can be wedged in position in the chase by the use of a 
plurality of conventional wedges (not shown). After the chase and dies 
have been assembled, the chase can be locked in the bed of a press or 
die-cutter in a conventional manner. 
The important requirement of the present invention is that all of the die 
positions of each row have the same scoring pattern, and that all of the 
die positions of the adjacent row have a different scoring pattern, so 
that, as the finished blanks BA and BB come off the die cutter or press 
and are automatically stacked one atop the other as illustrated at the 
lower part of FIG. 6, no blank of any stack will have exactly the same 
scoring pattern as that of the adjacent blank located above or below it. 
In the arrangement of the present invention, illustrated in FIG. 6, the 
dies of row 32 form the scoring pattern of carton blank BA, shown in FIG. 
3; whereas, the dies of row 32" form the scoring pattern of carton blank 
BB, shown in FIG. 4. 
Thus, it should be appreciated that the invention provides a relatively 
simple and economical method for preventing plastic coated cartons from 
sticking to each other when they are stacked vertically. Also, the method 
can be employed with conventional die cutting equipment, and does not 
require the use of costly powder application equipment. 
Perhaps the most important advantage of the invention is that it eliminates 
the mess, in both the carton manufacturer's plant and the carton packer's 
plant, that results from the application of offset powder.