U.S. patent number 3,644,159 [Application Number 04/645,673] was granted by the patent office on 1972-02-22 for methods for manufacturing corrugated board.
This patent grant is currently assigned to Palson Corporation AB. Invention is credited to Ake Evald Edkvist.
United States Patent |
3,644,159 |
Edkvist |
February 22, 1972 |
METHODS FOR MANUFACTURING CORRUGATED BOARD
Abstract
A method and an apparatus for manufacturing corrugated board in
which layers of material for the corrugated board are coated with a
mixture of a thermoplastic and a wax which can be brought into
liquid form and which after melting and setting on the layers keeps
said layers together.
Inventors: |
Edkvist; Ake Evald (Lockarp,
SW) |
Assignee: |
Palson Corporation AB (Malmo S,
SW)
|
Family
ID: |
20273890 |
Appl.
No.: |
04/645,673 |
Filed: |
June 13, 1967 |
Foreign Application Priority Data
Current U.S.
Class: |
156/210; 156/82;
156/470 |
Current CPC
Class: |
B31F
1/2804 (20130101); Y10T 156/1025 (20150115) |
Current International
Class: |
B31F
1/20 (20060101); B31F 1/28 (20060101); B31f
001/28 () |
Field of
Search: |
;156/196,210,205,208,470-473 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Engle; Samuel W.
Claims
I claim:
1. A method of manufacturing corrugated paper board having at least
a first even layer of paper and a second, corrugated layer of paper
attached to said first layer by means of an adhesive binder; the
method comprising the steps of supplying said first and second
layers with one layer having on one of its surfaces an adhesive
coating comprised of a mixture of thermoplastic and wax having a
melting point of about 65.degree. to 85.degree. C. which coating
may be melted into a liquid by application of heat, moving said
first and second layers towards each other at an acute angle into
initial overlying contact at a certain station with the apex of the
acute angle coinciding with said certain station and with the
coating on said one layer facing the other layer, and applying a
stream of hot air to said coating precisely at said station through
a nozzle located between said layers adjacent and in alignment with
said apex to melt said coating into a liquid immediately prior to
bringing the layers into initial overlying contact with each other
at said station, the said one layer including the coating thereon
being supplied from a supply source, the claimed method excluding
application of the coating to said one layer.
2. The method defined in claim 1 further including the step of
preheating said coating at a second station prior to bringing said
layers into contact with each other at said first defined
station.
3. The method defined in claim 2 wherein said one layer having the
coating is said second layer, the method further including the step
of corrugating said second layer at said second station by heated
cylinders prior to bringing the layers into said overlying contact
to thus effect said preheating step defined in claim 2 while said
second layer is being corrugated.
4. The method defined in claim 1 further including the step of
passing the formed corrugated board through a heated area at a
third station to be heated further after the layers are moved into
overlying contact.
5. The method defined in claim 4 further including the step of
subjecting the formed corrugated board to inward pressure exerted
on the opposite sides thereof on said layers generally at right
angles to the main plane of the formed corrugated board during
passage of the corrugated board through said heated area at said
third station.
6. The method defined in claim 5 further including the step of
cooling the formed corrugated board at a fourth station after it
leaves said heated area at said third station and while cooling,
exerting inward pressure on the opposite sides of the corrugated
board in a direction generally at right angles to the main
plane.
7. The method defined in claim 1 further including the step of
cooling the formed corrugated board after it leaves said station
and simultaneously applying inward pressure to opposite sides of
the formed corrugated board in directions extending generally at
right angles to the main plane of the corrugated board.
Description
This invention relates to a method and an apparatus for
manufacturing corrugated board having at least one layer with
alternating ridges and grooves and at least one smooth layer
interconnecting the ridge crests of said ridged and grooved layer
with the aid of a binder, and for carrying the method into effect
the apparatus includes supply rolls of starting materials for the
layers of corrugated board, cylinders for producing the ridged and
grooved layer, and cylinders for compressing all layers, webs of
the starting materials being caused to run together at an angle
between the cylinders.
Prior art methods and apparatus of these types suffer from serious
deficiencies. The apparatus employed take up a very large space
mainly because the binders hitherto utilized, which are deposited
on one or more of the different layers of the corrugated board,
must be hard and dry before the board can be allowed to leave the
apparatus. The binder being enclosed in the interior of the
corrugated board, it is very difficult to influence and accelerate
the setting and drying of the binder and therefore the setting and
drying can take place only extremely slowly, thus necessitating the
provision of an apparatus that takes up a great deal of room.
Moreover, prior art methods and apparatus do not give the
possibility of individually shaping the corrugated board for
various purposes and various uses. Decorative or informative print
can be applied to the corrugated board only in a very primitive
form without any sales-promoting properties. Therefore, advanced
one-color print and multicolor print cannot be used in connection
with corrugated board.
The present invention has for its object to eliminate the above and
further deficiencies of the prior art methods and apparatus. To
this end, the method according to the invention is characterized by
using as starting material for one or more of the corrugated board
layers paper having applied to it a coating which can be melted
into liquid form by application of heat, and directly subjecting
said coating to streams of hot air from a source of hot air through
nozzles, whereby the coating is brought into liquid form in
connection with the ridged and grooved layer being produced and/or
the smooth layers being united with the ridge crests of the ridged
and grooved layer produced.
The apparatus for carrying the method of the invention into effect
is characterized in that the nozzles connected to a suitable source
of hot air are located between the cylinders for producing the
ridged and grooved layer and the cylinders for compressing the
layers, and more precisely in the angle between two of the webs of
material supplied from the supply rolls and caused to run together
at the compression cylinders, said nozzles being directed toward
the apex of said angle.
The above features of the invention and the advantages gained
thereby will appear from the following description in which
reference is made to the accompanying drawings illustrating in
FIGS. 1 and 2 two embodiments of apparatus for carrying the method
of the invention into effect.
The apparatus in the two embodiments thereof illustrated in FIGS. 1
and 2 comprises supply rolls 1, 2, 3 of starting materials for the
different layers 4, 5, 6 of the corrugated board produced by the
apparatus illustrated. The apparatus also has toothed cylinders 7
between which the web of material 8 taken from the supply roll 1 is
passed for providing, in the known manner, the alternating ridges
and grooves in said web which is to form the ridged and grooved
layer 4. The apparatus further has nozzles 9 which are connected to
a suitable source of hot air having a temperature of 400.degree. to
600.degree. C. and which are disposed in the angle formed between
two of the webs of material 8, 11 and 12 supplied from the supply
rolls 1, 2, 3 and caused to run together at compression cylinders
10. More precisely, the nozzles 9 are located between the toothed
cylinders 7 and the compression cylinders 10. As will appear from
the drawing figures, the nozzles 9 have their mouths directed
toward the apex of said angle and thus toward the nip of the pair
of cylinders 10 closest to the nozzles. The toothed cylinders 7 are
adapted to be heated by means (not shown) for a purpose that will
appear from the following.
The embodiment of the apparatus illustrated in FIG. 2 differs from
that in FIG. 1 by an electronic oven 13 being arranged between the
nozzles 9 and the cylinders 10 for a purpose that will also appear
from the following. The compression cylinders preferably are
cooling cylinders that are cooled by any suitable coolants.
In the manufacture of the corrugated board by the method of the
invention at least one layer 4 with alternating ridges and grooves
is produced and at least one smooth layer 5 or 6 is united with the
ridge crests of said ridged and grooved layer 4 with the aid of a
binder. As starting material in the method of the invention use is
made of such a paper for one or more of the layers 4, 5, 6 as has a
coating which can be melted into liquid form by application of heat
and which is directly subjected to the action of streams of hot air
whereby said coating is brought into liquid form in connection with
the ridged and grooved layer 4 being produced and/or the smooth
layers 5, 6 being united with the ridge crests of the ridged and
grooved layer 4. Such paper can have the desired advanced print
applied to it in connection with the manufacture. Use is made, for
the meltable coating on such paper, of mixtures of thermoplastics
and waxes, having a melting point of about 65.degree. to 85.degree.
C. The heated toothed cylinders 7 preheat the web 8 at the
formation of the alternating ridges and grooves therein, and one or
both faces of the resulting ridged and grooved layer 4 as well as
the face or faces of the smooth layers 5, 6 turned toward the layer
4 are subjected to a final heating by the hot air projected through
the nozzles immediately before the smooth layers 5, 6 are united
with the ridge crests of the layer 4. As a result of the preheating
performed by the cylinders 7 the thermoplastic coatings on the web
of material 8 will be flexible and will retain their original
continuous character without any breaks at the bending points, the
ridge crests. The web of material 8 can therefore be subjected
without disadvantage to very sharp bendings, and the bends formed
by the cylinders 7 are fixed in shape because the coats are given a
certain time in which to set before the further steps of the
manufacturing method are performed, as will become apparent from
the following. For the final heating and for the melting of the
thermoplastic coating into liquid form the hot air is projected
through the nozzles 9 into the angles of the webs of material 8,
11, 12 caused to run together in the junction area at the cylinders
10 in FIG. 1. The compression cylinders 10, which preferably are
cooling cylinders, determine the thickness of the forming
corrugated board and provide a reliable connection between the webs
of material 8, 11, 12 because the melted coating or coatings
set.
As it is expedient in certain cases, after the layers 4, 5, 6 have
been united with each other, to provide a still more reliable
connection between the different layers and simultaneously a more
exact calibration of the thickness of the corrugated board, the
electronic oven 13 is suitably arranged after the nozzles 9 and
between the latter and the compression cylinders 10, as will appear
from FIG. 2. Further compression cylinders 14 are provided in the
electronic oven 13, the purpose of these cylinders being on the one
hand to keep the layers 4, 5, 6 together during the heating thereof
in the electronic oven to cause the thermoplastic layers to melt
again, and on the other hand in certain cases to exert such a
pressure on the corrugated board in a direction at right angles to
the main plane thereof that the ridge crests are compressed to a
certain extent, whereby a larger contact surface is obtained
between the ridged and grooved layer 4 and the smooth layers 5, 6.
As a consequence, the ridges and grooves of the layer 4 will have
an approximately rectangular shape in cross section, resulting in
an extremely resistant corrugated board with excellent
shock-absorbing properties for heavy articles.
It will readily be seen that all webs of material 8, 11 and 12 need
not be provided with coatings which can be melted by application of
heat, and that such a coating can be applied only to one surface of
one of the webs of material. In the latter case but one smooth
layer is combined with the ridged and grooved layer. However, by
providing all layers of the corrugated board with coatings meltable
by application of heat and thus being weldable, the corrugated
board will be extremely resistant to liquids and quite naturally be
of increased usefulness. The smooth layers or any other layers
whatever can readily be provided with the most advanced print
whereby the corrugated board will have the same effective
sales-promoting properties as other packaging materials. Further,
it will be readily understood that the number of ridged and grooved
layers and smooth layers can be varied and that the method of the
invention and the apparatus for carrying it into effect can thus
yield corrugated boards having an optional number of ridged and
grooved layers 4 as well as smooth layers 5, 6.
The cylinders 10 may be adjustable toward and away from the main
plane of the formed corrugated board to allow regulation of the
thickness of the board.
Coatings formed by mixtures of thermoplastics and waxes and having
been brought into liquid form imply the advantage that the
materials having such coatings practically need only be brought
together without essential pressure and but momentarily to ensure a
reliable interconnection of these materials after the mixtures have
set. As distinguished from the previously known methods it is not
necessary, when making use of the present invention, to exert a
prolonged and relatively high pressure on the corrugated board.
Further modifications are conceivable within the scope of the
invention defined in the appended claims.
* * * * *