U.S. patent application number 10/240499 was filed with the patent office on 2003-07-24 for method and apparatus for producing moulded pulp articles with a plastic film laminated thereon.
Invention is credited to Frederiksen, John Hoffmann, Rasmussen, Torben.
Application Number | 20030136537 10/240499 |
Document ID | / |
Family ID | 8168368 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030136537 |
Kind Code |
A1 |
Frederiksen, John Hoffmann ;
et al. |
July 24, 2003 |
Method and apparatus for producing moulded pulp articles with a
plastic film laminated thereon
Abstract
The invention relates to an apparatus and method for producing
articles (5) from moulded pulp material that are laminated with a
plastic film (4). Thus an environmental friendly and
water-resistant package for food products and for other moulded
pulp products such as packages for industrial products is provided.
The apparatus comprises a moulding line 1 and a laminating line
(3). The moulding line (1) comprises a suction moulding station
(20) with a pulp vat (25) and a number of suction moulds (22), a
drying oven (28) and conveying means (26,28) for transporting the
moulded pulp articles through the moulding line (1). The articles
are transported in line by a conveyor 10 from the moulding line (1)
to the laminating line (3), the laminating line (3) comprises a
plastic film supply unit (47), a heating station (69) a laminating
station (80) and conveying means (56) for conveying the articles
(5) through the laminating line (3).
Inventors: |
Frederiksen, John Hoffmann;
(US) ; Rasmussen, Torben; (Smorum, DK) |
Correspondence
Address: |
LARSON & TAYLOR, PLC
1199 NORTH FAIRFAX STREET
SUITE 900
ALEXANDRIA
VA
22314
US
|
Family ID: |
8168368 |
Appl. No.: |
10/240499 |
Filed: |
October 3, 2002 |
PCT Filed: |
April 4, 2001 |
PCT NO: |
PCT/DK01/00228 |
Current U.S.
Class: |
162/224 ;
162/228; 162/230; 162/391; 162/410 |
Current CPC
Class: |
B29C 51/10 20130101;
B29C 2791/001 20130101; D21J 7/00 20130101; B29C 51/261 20130101;
B29C 51/082 20130101; B29C 2791/007 20130101; B29K 2995/0041
20130101; B29C 2791/006 20130101; B29C 51/165 20130101 |
Class at
Publication: |
162/224 ;
162/228; 162/230; 162/391; 162/410 |
International
Class: |
D21J 003/00; D21J
007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 2000 |
EP |
00107270.1 |
Claims
1. Apparatus for producing articles (5) from moulded pulp material
that are laminated with a plastic film (4) comprising a moulding
line (1) and a laminating line (3), the moulding line (1)
comprising a suction moulding station (20) with a pulp vat (25) and
a number of suction moulds (22), a drying oven (28) and conveying
means (26,27) for transporting the moulded pulp articles (5)
through the moulding line (1), the apparatus further comprises
conveying means (10) for transporting the moulded pulp articles (5)
from the moulding line (1) to the laminating line (3) which is
arranged in line with the moulding line (1), thus forming one
continuous production line, the laminating line (3) comprising a
plastic film supply unit (47), a heating station (69), a laminating
station (80) and conveying means (56) for conveying the articles
(5) through the laminating line (3).
2. Apparatus according to claim 1, wherein the moulding line (1) is
adapted to produce a plurality of articles (5) that are mutually
interconnected.
3. Apparatus according to claim 2, wherein the plurality of
interconnected artides (5) are transported together through the
moulding line (1) and the laminating line (3).
4. Apparatus according to any of claims 1 to 3, wherein the
laminating line (3) is located separately from the moulding line
(1) in a clean room (40).
5. Apparatus according to claim 4, characterised in that the
conveying means (10) for transporting the moulded pulp articles (5)
from the moulding line (1) to the laminating line (3) passes
through an opening (43) in a wall (42) separating the laminating
line (3) from the moulding line (1), whereby preferably a tunnel
(45) is extending from the opening (43) towards the moulding line
(1) in which tunnel the conveying means (10) is received.
6. Apparatus according to any of claims 1 to 5, wherein the
laminating line (1) further comprises a hot press station (50) and
a corresponding humidification station (30) before the heating
station (69).
7. Apparatus according to any of claims 1 to 6, wherein the
conveying means (10) for transporting the moulded pulp articles (5)
from the moulding line (1) to the laminating line (3) comprises a
buffer of moulded pulp articles (5).
8. Apparatus according to any of claims 1 to 7, further comprising
a means (52,53,54,55) for positioning the moulded pulp articles (5)
with respect to the hot press station (50).
9. Apparatus according to claim 8, wherein the moulded pulp
articles (5) are fixed with respect to the conveying means (56) for
transporting the articles (5) through the laminating line (3) when
the hot press (51) is closed.
10. Apparatus according to any of claims 1 to 9, wherein the
laminating station (3) further comprises a hot tool (85) for
laminating the plastic film (4) to selected areas of the moulded
pulp articles (5) in order to weld the film (4) in these areas to
the moulded pulp articles (5).
11. Apparatus according to any of claims 1 to 10, wherein the
laminating station (3) comprises means for applying underpressure
to the film (4) through the moulded pulp articles (5) and/or a
pressing tool (83) and/or means for applying overpressure to the
film (4) in order to shape the plastic film (4) and press it onto
the moulded pulp articles (5) and secure sufficient bonding of the
film (4) to the articles (5).
12. Apparatus according to any of claims 1 to 11, wherein the
moulded pulp articles (5) or a plurality of interconnected moulded
pulp articles (5) are moulded with laterally protruding tabs or
flanges (6) which are gripped or engaged by the conveying
means.
13. Apparatus according to claim 12, wherein the conveying means
(56) for transporting the articles (5) through the laminating line
(3) engage both the tabs or flanges (6) of moulded articles (5) or
of the plurality of interconnected moulded pulp articles (5) and
the plastic film (4) sheet with a common engagement means.
14. Apparatus according to any of claims 7 to 13 in which the
operation speed of the laminating line (3) depends on the number of
moulded pulp articles (5) in the buffer.
15. Apparatus according to any of claims I to 14, further
comprising a film crystallisation station (90) after the laminating
station (80).
16. Method of producing moulded pulp articles (5) with a plastic
film (4) laminated thereon comprising the steps of, providing a
pulp vat (25), providing at least one suction mould (22),
submerging at least one suction mould (22) in the pulp vat (25),
removing the moulded pulp artides (5) from the suction mould (22)
and conveying the moulded pulp articles (5) through a drying oven
(28) to dry them, transporting the moulded pulp articles (5) in
line from the drying oven (28) to a laminating line (3), supplying
plastic film (4) to the laminating line (3), heating the plastic
film (4) and the moulded pulp articles (5), laminating the film (4)
onto the moulded article (5) and crystallising the plastic film
(4).
17. Method according to claim 16, wherein a plurality of articles
(5) mutually interconnected through bridges are moulded together as
an integral body which is conveyed as one entity through the
moulding line (1) and the laminating line (3).
18. Method according to claim 17, wherein the moulded pulp articles
(5) or a plurality of interconnected moulded pulp articles (5) are
moulded with laterally protruding tabs or flanges (6) which are
gripped or engaged by the conveying means (10).
Description
TECHNICAL FIELD
[0001] The present invention relates to an apparatus for producing
moulded pulp articles that have a plastic film laminated thereon of
the kind set forth in the preamble of claim 1. The invention also
relates to a method of producing moulded pulp articles with a
plastic film laminated thereon of the kind set forth in the
preamble of claim 16.
BACKGROUND ART
[0002] Moulded pulp articles are a desirable form of packaging
since it is an environmental friendly non-expensive alternative to
plastic and other materials for three dimensionally contoured
packages. The use of such moulded pulp articles as food trays and
the like has been desired since several decades. Moulded pulp is
however not resistant to moist and as such thus not suitable for
holding moist food or beverages. Therefore, several techniques have
been developed for coating or laminating the moulded pulp packages
with a moist resistant and preferably to provide them with a gas
barrier. Other types of moulded pulp articles are packages for
industrial products such as mobile phones or print cartridges. Dust
and scratching from the pulp material can be problematic for
certain sensitive industrial products. There exists therefore also
a need for a technique to coat or laminate the moulded pulp
articles from this perspective. None of the known techniques for
this purpose have been able to meet the requirements for a
successful commercial application.
[0003] EP-A-0-196 799 discloses an apparatus for laminating plastic
film onto moulded pulp articles. Preformed articles are taken from
a stack of articles by a destacking apparatus and placed in rows
across a conveyor. The articles are fed by the conveyor and lined
with a superimposed plastic film at a laminating station where the
plastic film is bonded to the interior of the articles. This
apparatus for the laminating of films to moulded pulp articles does
not operate at desirably high speeds that allow successful
commercial application. Further, the off-line mode of operation of
the known prior art laminating line creates problems with handling
and storing large amounts of articles between the production of the
articles and the laminating line.
DISCLOSURE OF THE INVENTION
[0004] On this background, it is the object of the present
invention to provide an apparatus for producing moulded pulp
articles of the kind referred to initially that operates at high
rates. It is another object of the present invention to provide a
method for producing moulded pulp articles that are laminated
laminating a plastic film onto moulded pulp articles of the kind
referred to initially that allows operation at high rates. These
objects are achieved in accordance with claim 1 and 16 respectively
by transporting the moulded pulp articles in line from the moulding
section to the laminating section, thus forming one continuous
production line where the pulp articles are transported through the
various working stations without intermediate storing.
[0005] According to an embodiment of the invention, the moulding
line is adapted to produce a plurality of articles that are
mutually interconnected through bridges.
[0006] According to another embodiment of the invention wherein the
laminating line is located separately from the moulding line in a
dean room, the two lines being connected through an intermediate
conveyor.
[0007] According to another alternative embodiment of the
invention, the laminating line comprises a hot press station before
the heating station.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In the following detailed portion of the present
description, the invention will be explained in more detail with
reference to the exemplary embodiments shown in the drawings, in
which
[0009] FIG. 1 is a diagrammatical side view of the moulding
line,
[0010] FIG. 2 is a diagrammatical side view of the laminating line
according to the invention,
[0011] FIG. 3 is a layout of the production line according to the
invention, and
[0012] FIG. 4a and 4b are elevated views on a plurality of
interconnected moulded pulp articles and on a disconnected moulded
pulp article.
DETAILED DESCRIPTION OF THE INVENTION
[0013] With reference to the FIGS. 1 and 2, a production line for
manufacture of moulded pulp articles 5 laminated by welding of
plastic film sheets comprises a moulding line 1 and a laminating
line 3.
[0014] The articles 5 are typically three dimensionally contoured
moulded pulp packages such as food- or meat trays. These articles 5
have a relatively thin wall of fibre material such as paper pulp or
wood pulp. The articles 5 are intended to be food trays and must
therefore be laminated in a clean (hygienic) area.
[0015] As shown in FIG. 3, the laminating line 3 is located in a
clean room separately from the moulding line 1. The two lines are
separated. The laminating line 3 and the moulding line 1 are
connected by a conveyor 10 that passes through an air lock into the
clean room. The plastic film 4 must be suitable for thermo-forming,
preferable gas impermeable or comprise a barrier against certain
gases and moisture. Multilayer films 4 with an overall thickness of
approximately 50 pm provide sufficient thickness after laminating
to comply with the barrier standards.
[0016] FIG. 1 shows diagrammatically a suction moulding line 1 for
moulding articles 5 from pulp material. The line starts with a
moulding station 20. The moulding station 20 comprises a mould
carrier 21, on the outside of which are placed several
liquid-permeable suction moulds 22 adapted to be connected with a
source of sub-atmospheric and to a source of super-atmospheric
pressure (not shown).
[0017] The mould carrier 21 is with a part of its circumferential
surface immersed in a pulp vat 25 containing a fibre pulp
suspension. This pulp may be made from a fibre-containing raw
material, such as waste paper or cardboard. During the immersion in
the pulp mass, a layer of fibre material is deposited by suction on
the mould surfaces of the suction mould 22. Subsequently, when the
suction moulds 22 are withdrawn from the fibre suspension in the
pulp vat 25, the suction is continued to compact the deposited
fibres while exhausting residual liquid therefrom. After
withdrawing the mould from the pulp vat 25, the mould will follow
the rotary trajectory of the rotatable mould carrier 21 and thereby
suck air through the articles 5 which are thereby partially
dewatered, the moulds 2 are further rotated to the position where
the articles 5 are blown off from the suction moulds 22 and
aspirated onto transfer moulds on the transfer rotor 26. After a
part of a revolution of the transfer rotor 26, the articles 5 are
blown off therefrom onto a carrier system 27 which transports the
articles 5 to a drying oven 28 for a drying procedure. In the
drying oven 28, the articles 5 reach their final dry matter weight
content of at least 90 weight per cent.
[0018] A group of articles 5 may be moulded in the form of a common
continuous body with bridges interconnecting the articles 5, said
bridges for the sake of simplicity being shown in the form of a
common bridge sheet in the drawing (cf. FIG. 4a). Instead of a
common plate, the bridge connection may also be formed by ribs (cf.
FIG. 4b), and the bridge connection may also comprise a directly
abutting connection between the mutually facing sides of two
adjacent articles 5. The articles 5 are provided with lateral tabs
or flanges 6 for engagement or gripping by transport means.
[0019] From the drying oven 28, a conveyor 10 transports the
moulded pulp articles 5 through a humidification station 30 to the
laminating line 3. The conveyor 10 comprises a buffer of articles 5
between the moulding line 1 and the laminating line 3 in order to
avoid gaps in the supply of moulded pulp articles 5 to the
laminating line 3. The operation speed of the laminating line 3
depends on the number of articles 5 in the buffer, i.e. less
articles 5 in the buffer, the lower result in a low operation
speed.
[0020] The articles 5 leaving the drying oven 28 are too dry for a
hot press operation. Therefore, a controlled humidification takes
place in the humidification station 30 to obtain a smooth surface
of the product with exact dimensions after the hot pressing in the
heated tools which create a steam pressure.
[0021] The laminating line 3 is arranged in a clean room 40 that is
separated from the moulding line 1 and the humidification station
30 in order to avoid contamination. In the clean room 40, an
overpressure is maintained in order to avoid unclean air coming in.
A wall 42 separating the clean room 40 from the moulding line
environment is provided with an opening 43 with a tunnel 45
extending therefrom into the moulding line environment. The tunnel
45 increases the flow restriction for the air flowing out through
the opening thereby reducing the amount of lost pressurised
air.
[0022] The laminating line 3 comprises a hot press station 50, a
heating station 69, a laminating station 80, a crystallisation
station 90, a cutting station 93, a stacking station 99 and a
conveying apparatus 56 which serves to guide and transport the
moulded articles 5 and the plastic film 4 through the stations.
[0023] At the start of the laminating line 3, the moulded pulp
articles 5 or the plurality of moulded pulp articles 5 are
positioned in the hot press station 50 by means of two transversely
spaced sets of actuators 52,53 receiving a closed loop control
signal from two transversely spaced photo cells 54,55 in order to
position the front edge of the article or plurality of articles 5
exactly perpendicular to transport direction.
[0024] The hot press 51 comprises an upper 57 and a lower 58 tool
complementary shaped in accordance with the article 5 to be
laminated. The upper tool 57 and the lower tool 58 both move
towards the article 5 when the hot press 51 is closed. Both tools
57,58 are heated by conventional means. The hot press action heats
the moulded pulp article 5 extremely fast to a temperature of about
50 to 100 degrees Celsius. When the hot press 51 is closed, the
lateral tabs or flanges 6 on the articles 5 or plurality of
interconnected articles 5 extend out of the tools 57,58 so that
they can be engaged by the conveyor apparatus 56.
[0025] A conventional conveying apparatus 56 comprises two
transversely spaced rails 59 extending along the longitudinal axis
of the laminating line 3. The distance between the rails 59 can be
adjusted in accordance with the width of the articles 5 or the
width of the plurality of interconnected articles 5. Each rail 59
defines two channels, an upper and a lower channel in which a
spiked chain is guided (not shown). In the upper channel, the
spiked chain moves forward through the laminating line 3 while in
the lower channel the spiked chain returns to the start of the
laminating line 3. The upper channel also defines a surface for
guiding the tabs or flanges 6 of the articles 5 and is provided
with a groove in which the spikes partially extend. Thus, the
spikes extend through the tabs or flanges 6 and positively engage
the flanges or tabs 6. The spikes penetrate the tabs or flanges 6
when the article 5 or the plurality of interconnected articles 5 is
positively fixed in the closed hot press 51. When the hot press 51
opens, the chain is driven to transport the articles 5 to the next
station.
[0026] Alternatively clamps, belts or other fixating means (not
shown) can substitute the spiked chain.
[0027] Directly after the hot press station 50, the plastic film 4
is fed from a film reel 47 into the rails 59 through a slot in the
guiding surface of the upper channels. The spikes of the chain also
penetrate the plastic film 4 and the plastic film 4 and the
articles 5 are moved in unison by the spiked chain to the heating
station 69.
[0028] The heating station 69 comprises a heating element above 70
and one under 71 the moulded pulp articles 5 and the plastic film
4. The plastic film 4 only absorbs a part of the radiation from the
upper heating element 70 and the rest can be absorbed by the
moulded pulp articles 5. The plastic film 4 is heated to above the
glass temperature and the moulded pulp artides 5 have a temperature
less than 200 degrees Celsius when they leave the heating station
69.
[0029] The next station is a conventional laminating 80 station
which comprises an upper 81 and a lower table 82. The upper table
81 is provided with die press tool 83 whereas the lower table 82 is
provided with a heated suction mould 84. Both the upper and lower
table move towards the film 4 and the moulded pulp article 5. A
partial vacuum is applied to the suction mould 84. The film 4 is
bonded to the moulded pulp articles 5 by being drawn downwardly by
the partial vacuum applied to the suction mould 84 through the
moulded pulp article 5 and/or by the press tool 83. The upper table
81 may also be provided with means (not shown) to apply compressed
air to the upper side of the plastic sheet 4.
[0030] Further, the laminating station 80 comprises a separately
movable hot tool 85 for laminating the plastic film 4 to selected
(flange) areas of the moulded pulp articles 5 in order to
positively weld the film 4 to these areas of the moulded pulp
articles 5.
[0031] The articles 5 with the film 4 laminated thereon are then
transported by the conveyor 56 to the crystallisation station 90.
This station comprises an upper heating element 91. By exposing the
plastic film 4 to the heat, a crystallisation from amorphous to
crystalline can take place if desired. In the case of food trays,
this renders the laminated moulded pulp article 5 resistant to the
heat of a domestic oven.
[0032] Next, a conventional cutting station 93 comprising an upper
94 and a lower movable tool 95 for die cuffing separates the
plurality of interconnected articles 5 and for removing superfluous
flange material such as the tabs or flanges 6 for gripping by the
conveyor 56. Either the upper or the lower tool is provided with a
knife 96 to cut of the flange areas. The articles 5 remain
connected to the "waste" material by narrow bridges in order to
allow further transport to a stacking station 99.
[0033] After the cuffing station 93, a conventional stacking
station 99 stacks the laminated moulded pulp articles 5 so that
they may be removed batch-wise from the laminating line 3.
[0034] According to a not shown embodiment, a filling and sealing
line is arranged in line/off line with the laminating line for
filling the trays with food or other products and then sealing the
filled tray with a plastic top sheet. Thus, the laminating line
does not comprise a stacking station.
[0035] List of Reference Numerals
[0036] 1 moulding line
[0037] 3 laminating line
[0038] 4 plastic film
[0039] 5 article
[0040] 6 tab or flange
[0041] 10 conveyor
[0042] 20 moulding station
[0043] 21 mould carrier
[0044] 22 suction mould
[0045] 25 pulp vat
[0046] 26 transfer
[0047] 27 carrier system
[0048] 28 drying oven
[0049] 30 humidification station
[0050] 40 clean room
[0051] 42 wall
[0052] 43 opening
[0053] 45 tunnel
[0054] 47 film reel
[0055] 50 hot press station
[0056] 51 hot press
[0057] 52 actuator
[0058] 53 actuator
[0059] 54 photocell
[0060] 55 photo cell
[0061] 56 conveyor
[0062] 57 upper tool
[0063] 58 lower tool
[0064] 59 rail
[0065] 69 heating station
[0066] 70 upper heating element
[0067] 71 lower heating element
[0068] 80 laminating station
[0069] 81 upper table
[0070] 82 lower table
[0071] 83 press tool
[0072] 84 suction mould
[0073] 85 hot tool
[0074] 90 crystallisation station
[0075] 91 upper heating element
[0076] 93 cutting station
[0077] 94 uppertool
[0078] 95 lower tool
[0079] 96 knife
[0080] 99 stacking station
* * * * *