U.S. patent application number 11/583529 was filed with the patent office on 2007-02-15 for method of manufacturing thermoformed plastic articles and drink cup lid made by such method.
Invention is credited to Ivonis M. Mazzarolo.
Application Number | 20070034629 11/583529 |
Document ID | / |
Family ID | 37741662 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070034629 |
Kind Code |
A1 |
Mazzarolo; Ivonis M. |
February 15, 2007 |
Method of manufacturing thermoformed plastic articles and drink cup
lid made by such method
Abstract
A method and apparatus for vacuum thermoforming disposable drink
cups lids including the step of imparting printing to the lids in
two or more colors while they are in contact with the vacuum
thermoforming platen.
Inventors: |
Mazzarolo; Ivonis M.;
(Vaudreuil, CA) |
Correspondence
Address: |
YOUNG & BASILE, P.C.
3001 WEST BIG BEAVER ROAD
SUITE 624
TROY
MI
48084
US
|
Family ID: |
37741662 |
Appl. No.: |
11/583529 |
Filed: |
October 19, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10691123 |
Oct 22, 2003 |
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11583529 |
Oct 19, 2006 |
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Current U.S.
Class: |
220/254.3 ;
220/712; 220/713; 220/780; 229/404; 229/906.1 |
Current CPC
Class: |
B65D 47/06 20130101;
B65D 2203/00 20130101; G09F 23/08 20130101 |
Class at
Publication: |
220/254.3 ;
220/780; 220/712; 220/713; 229/404; 229/906.1 |
International
Class: |
B65D 51/18 20060101
B65D051/18; A47G 19/22 20060101 A47G019/22; B65D 41/18 20060101
B65D041/18 |
Claims
1. A thermoformed thin plastic lid for drink cups comprising a
raised rim defining a central printable area formed according to
the method comprising the steps of: hot melt extruding a thin web
of plastic material; contacting the web with a vacuum thermoforming
platen configured to form said article and said area within said
article; applying vacuum to said platen; applying inks of at least
two colors to said area after formation thereof but while said
article remains in contact with said platen; and separating said
web and article from said platen.
2. Apparatus for vacuum thermoforming and printing articles in a
substantially continuous fashion comprising: a vacuum thermoforming
drum carrying regularly spaced theromforming dies; at least two
printing cylinders carrying printing plates disposed adjacent said
drum for contacting and imparting ink to said articles as they are
formed over said dies; and means for rotating said printing
cylinders in synchronism with said drum.
3. Apparatus as defined in claim 2 further including an inking
roller contacting said printing cylinder; and means for rotating
said inking roller in synchronism with said printing cylinder.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 10/691,123, filed Oct. 23, 2003 entitled "METHOD OF
MANUFACTURING THERMOFORMED PLASTIC ARTICLES AND DRINK CUP LID MADE
BY SUCH METHOD" and claims priority thereto. The content of the
U.S. patent application Ser. No. 10/691,123 is incorporated herein
by reference.
FIELD OF THE INVENTION
[0002] This invention relates to the vacuum thermoformed plastic
articles and particularly to a vacuum thermoformed disposable drink
cup lid having printed indicia thereon and a method of
manufacturing such an article.
BACKGROUND OF THE INVENTION
[0003] It is well known to manufacture thin plastic articles such
as disposable drink cup lids by vacuum thermoforming. Such articles
are manufactured by causing a web of extruded plastic sheet
material to contact a metal die having the desired shape of the
article formed into a surface thereof. Vacuum is applied to the
platen surface through small holes to draw the plastic material
over the contours of the die. The articles are thereafter cooled,
separated from the web by die cutting, and stacked and/or boxed
using conventional automation devices.
[0004] It is also known to vacuum form logos and other indicia on
the plastic lids. Such indicia are typically formed of raised
surfaces in a central deck area of the lid. Because thermoformed
plastic lids are usually of one color, it is difficult to clearly
see such vacuum embossed indicia. To add definition, the raised
surfaces of the embossed indicia may be colored in a secondary
operation carried out by printing machinery separate from the
thermoforming machinery.
BRIEF SUMMARY OF THE INVENTION
[0005] According to the present invention, vacuum thermoformed
articles such as disposable drink cup lids are thermoformed and
printed; i.e., provided with coloring on embossed surfaces and/or
printed with logos and other indicia on non-embossed surfaces in
what is essentially a single operation. In other words, printing
takes place as the article is being thermoformed. The invention
increases manufacturing efficiency and lowers manufacturing costs
and provides the end user with added value in the form of marketing
and promotional indicia.
[0006] In general, this is accomplished by extruding a thin web of
thermoformable plastic sheet material, contacting the web while hot
with a vacuum thermoforming die configured to form articles such as
disposable drink cup lids having printable areas within the
boundaries of said articles, applying vacuum to form the articles,
immediately thereafter applying ink to the printable areas while
the articles remain in the web and at an elevated temperature and,
thereafter, separating the fully formed and printed articles from
the web. As stated above, the term "printed" is used herein to
refer to both adding color to embossed surfaces and placing indicia
on essentially flat surfaces.
[0007] In the preferred form hereinafter described, the method is
carried out by means of an apparatus which comprises a rotating
thermoforming drum carrying a series of plates with die inserts for
forming articles, and a multi-surface rotatable printing cylinder
which rotates in synchronism with the thermoforming drum. The
printing cylinder rotates in synchronism with the drum and with an
Anilox roller which carries ink from a supply to the plates on the
printing cylinder. Synchronism is preferably maintained by gears to
ensure registration between the ink plates and the thermoformed
articles. Fully formed and printed articles thereafter pass to a
conventional die cutter where they are removed from the web. The
articles may be stacked and excess material from the web returned
to the extruder supply hopper.
[0008] As described herein, it is possible to print in more than
one color on a surface of the article. This is accomplished by
providing two or more printing mechanisms in angular spaced
relationship to the thermoforming systems, one comprising a printer
element which engages a surface of the article at one point in the
thermoforming process and another printing element which contacts
the article for in-registry printing purposes at another angularly
spaced position in the thermoforming process.
[0009] Other applications of the present invention will become
apparent to those skilled in the art when the following description
of the best mode contemplated for practicing the invention is read
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0011] FIG. 1 is a schematic view of a system for carrying out the
method of manufacturing disposable drink cup lids;
[0012] FIG. 2 is a perspective view of a portion of the machine of
FIG. 1;
[0013] FIG. 3 is a plan view of a drink up lid made by the
inventive method;
[0014] FIG. 4 is a sectional view of the FIG. 3 lid;
[0015] FIG. 5 is a plan view of a second lid made by the inventive
method;
[0016] FIG. 6 is a sectional view of the FIG. 5 lid; and
[0017] FIG. 7 is a schematic diagram of a system for carrying out
the method of manufacturing disposable drink cup lids and printing
on said lids in two different colors.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
First Embodiment
[0018] Referring to the drawing, FIG. 1 illustrates in schematic
fashion an apparatus 10 for manufacturing vacuum thermoformed drink
cup lids and simultaneously printing the lids in what is
essentially a single and continuous manufacturing operation. The
apparatus 10 comprises a hot melt extruder 12 for receiving ground
or pelletized plastic material such as polystyrene or polyethylene.
The extruder is equipped to melt the plastic material and force it
through an exit die 14 of convention design to produce a thin web
16 of plastic material. The width of the web may be any desired
width; here approximately 24 inches.
[0019] The web 16 exits the extruder die 14 at approximately
320.degree. F. to 340.degree. F. and passes to a vacuum forming
drum 18 which is suitably mounted for rotation by a drive 22 in
either direction to cause the web to contact forming dies 20
mounted on the drum 18 for the desired time. Coolant and vacuum are
applied to the drum by sources 24 and 26 respectively to control
temperatures and to produce vacuum forming.
[0020] After the desired time of contact with the dies 20 on the
drum 18 the web 16 with the articles formed therein passes to a die
cutter and stacker 28 of conventional design.
[0021] To carry out the printing operation simultaneously and in
synchronism with the thermoforming operation, a printing cylinder
30 is mounted above the drum 18 by means to be described with
reference to FIG. 2. The printing cylinder 30 is equipped with
plates 32 which contact the vacuum formed articles after they have
cooled to a temperature of between about 150.degree.-250.degree.
F., the elevated temperature being effective to rapidly dry the ink
which is applied to the vacuum thermoformed articles by the plates
32 on the printing cylinder 30.
[0022] The plates 32 on the printing cylinder 30 are continuously
inked by an Anilox roller 34 which picks up ink 36 from an ink
fountain 38 having a filler mechanism 40. Seals and proper ink
distribution are provided by Nylon doctor blade 42 and 44 which
form the bottom of the ink fountain 38 and engage the upper
quadrant of the Anilox roller 34.
[0023] The drum 18, printing cylinder 30 and Anilox roller 34 all
rotate in precise synchronism as a result of means hereinafter
described in detail with reference to FIG. 2. In addition the
printing cylinder 30, Anilox roller 34 and ink fountain 38 adapt
for vertical movement by means to be described in order to
accommodate the angular surface of the octagonal thermoforming drum
18.
[0024] Referring now to FIGS. 3 and 4 a specific thermoformed
article 50 is shown to comprise a thin plastic drink cup lid of
approximately 31/2 inches in diameter and configured to be applied
to the upper rim of a standard plastic or paper disposable drink
cup 52. The specific article 50 shown in FIGS. 3 and 4 is a hot
drink cup lid producing what is known in the trade as a plug fit by
means of a 300.degree. channel 54 which is vacuum thermoformed into
the material of the lid 50. A skirt 56 is also vacuum formed around
the periphery of the lid and finally formed by the die cutting
operation carried out by device 28 shown in FIG. 1.
[0025] The lid 50 is shown to comprise a drink-through tear-back
tab 58 defined by a partially die cut area near the periphery of
the lid and within the discontinuity of the plug fit channel 54. A
raised feature 60 is formed in the lid 50 adjacent a shallow hinge
64 such that the raised operating feature 60 may be folded back and
locked back into a receiver cavity 62 formed immediately behind the
hinge 64. The details of the tear-back/lock-back features of the
lid 50 are more fully described in the co-pending application for
U.S. patent application Ser. No. 09/952,154 filed Sep. 14, 2001,
the entire disclosure of which is incorporated herein by
reference.
[0026] The lid 50 is shown to comprise a large flat central deck
area 66 in which there is embossed during the thermoforming
operation a raised logo 68 the features of which have relatively
flat raised surfaces. In accordance with the invention coloring is
imparted to the raised surfaces of the logo 68 by the printing
cylinder 30 and the apparatus of FIG. 1. FIGS. 5 and 6 illustrate a
second lid 50' of a configuration which is slightly different from
the configuration of lid 50. Specifically, the lid 50' has no
embossed logo. Accordingly, the plates 32 of the printing cylinder
30 must be formed, like conventional rubber stamps, to carry the
desired lettering on other indicia.
[0027] Referring now to FIG. 2, the octagonal drum 18, the printing
cylinder 30, the Anilox roller 34 and the ink fountain 38 are shown
in greater detail. A continuous gear surface 74 is formed around
the left peripheral end of the drum 18 with teeth extending
parallel to the axis of rotation of the drum 18. The gear surface
74 is in constant contact with a print cylinder gear 76 which is
mechanically attached to the printing cylinder 30 to rotate the
printing cylinder 30 and the ink plate 32 in precise synchronism
with the rotation of the drum 18 thereby to ensure continuous
registry of the ink plate 32 with the locations of the mold inserts
or dies 20 which are carried by plates 21 attached by machine
screws to the flat surfaces of the drum 18. In this instance there
are three lid forming dies 20 across each of the plates 21 but this
number is merely illustrative. The molding features of the inserts
20 may differ from insert to insert but it is desirable that all of
the inserts be male dies and have essentially the same height so as
to be properly engaged by the printing surfaces of the plates 32.
The feature 60 shown in FIGS. 3 and 4 of the drawings requires that
the ink plates be sized and located to clear the feature 60 as they
engage the top surfaces of the logo 68 during the printing
operation.
[0028] The printing cylinder 30 with the associated gear 76 is
mounted on a print head frame 70 which is adapted for pivotal
rotation about an axle 72. Cam rollers 78 mounted on both sides of
the frame 70 for rotation relative thereto contact cam surfaces 84
formed on the drum 18. The cam surfaces are continuous, and,
although essentially octagonal, have machined corners to permit
smooth and continuous contact between the cam surfaces and the
associated roller 78. The clearance between the rollers 78 and the
cam surfaces 84 may be adjusted by means of adjustment screws 88
shown in FIG. 2 to vary the pressure of the ink plates 32 on the
molded plastic articles during the printing operation.
[0029] To ensure a synchronous drive relationship between the
printing cylinder 30 and the Anilox roller 34, the gear 90 is
mounted on the printing cylinder 30 inboard of the gear 76 and
meshes with a gear 92 mounted on the left end of the Anilox inking
roller 34 as shown in FIG. 2. The Anilox roller 34 is mounted on
the frame 70 by conventional bearings.
[0030] The ink fountain 38 may be adjusted in relationship to the
surface of the Anilox roller 34 by means of a plate 96 which lies
between opposite lateral sections of the frame 70 and carries
spacing adjustment screws 98. The drum 18 is mounted on a frame 100
for rotation as previously described.
OPERATION
[0031] In a typical operation plastic material is forced from the
extruder through the die 14 to form the hot web 16, the web being
continuously drawn from the extrusion die 14 by clockwise rotation
of the drum 18. It will be understood that this drum may rotate in
the counter-clockwise direction if desired to extend the web 16
around the bottom of the drum and thereafter to the die cutter
28.
[0032] Substantially as soon as the web 16 encounters the mold
inserts 20 of the drum 18 vacuum is applied and the material of the
web is drawn by vacuum over the contours of the dies 20 to form the
lids 50 or such other articles as it may be desired in any
particular operation to make. The web material cools to between
approximately 140.degree. F. to 250.degree. F. for application of
the ink 36 by way of the plates 32 on the printing cylinder 30. The
web material with the articles now formed therein and printed
remains in contact with the drum 18 and the dies 20 and plates 21
long enough to cool to between about 70.degree. F. and 110.degree.
F. whereupon they are separated from the drum surface and conveyed
to the die cutter apparatus 28. Extra material from the web not
formed into articles 50 may be recovered and ground and returned to
the hot melt extruder 12.
Multi-color Embodiment
[0033] Referring now to FIG. 7, there is shown an apparatus which
is similar to the apparatus of FIG. 1 but which provides the
capability of printing on the surface of the thermoformed articles
in two different colors. Where components of FIG. 7 are identical
to the components of FIG. 1, identical reference numerals are used.
For example, the extruder 12, the die 14, the web 16, the
thermoforming drum 18 with the dies 20, the rotary drive 22, the
coolant source 24 and the vacuum source 26 in FIG. 7 are all
identical to the corresponding components in FIG. 1. Note that,
while an octagonal drum is shown, it is desirable to increase the
size of the drum and increase the number of faces to accommodate
additional colors.
[0034] The apparatus of FIG. 1 further comprises a first ink
reservoir 101 filled with ink 102 of a first color such as red
which supplies red ink to the Anilox roller 104 which is turn
supplies red ink to the plates 107 on the printing roller 106.
Printing roller plates 107 contact the web 16 as it overlies a die
20 on the thermoforming drum 18 at a first angular position. The
first ink reservoir 101 and associated components are, except for
position, identical to the corresponding apparatus shown in FIG.
1.
[0035] A second ink reservoir 108 with ink 110 of a second color
such as blue contacts a second Anilox roller 112 which loads the
ink onto the plates 115 of a second printing roller 114. The plates
115 contact the web 16 at a second angular position on the drum 18
which remains in registry with the printing process carried out at
the first position thereby to add a second color to the indicia on
the articles. The printed articles then proceed to the die cutter
28 in the fashion described with reference to FIG. 1. The second
reservoir 108 and associated components are, except for ink color
and position, identical to corresponding components of reservoir
101.
[0036] The printing apparatus including the reservoirs 101 and 108
may be mechanically interconnected for servicing convenience and to
ensure the maintenance of proper registry between the ink plates
and the articles being printed on. The reservoirs, Anilox rollers
and printing rollers may also be supported by means which permit
them to be lifted and withdrawn individually or in unison from the
surface of the web for various purposes which will be apparent to
those skilled in the plastic article printing arts.
[0037] While the invention has been described with reference to a
specific article and a specific apparatus for carrying out the
manufacturing method of the article, it is to be understood that it
may be carried out using apparatus of different style and design
and also that articles other than molded plastic drink cup lids may
be manufactured and printed in accordance with the teachings of
this patent. While the adjustable cam rollers and gears described
above with reference to the illustrative embodiment are preferred
at this time, it is to be understood that other and equivalent
drive devices such as belts, chains and the like may also be used
to synchronize the rotation of the various components of the
thermoforming and printing system. Alternatively or additionally a
speed control and synchronization may be achieved electronically
using high resolution encoders and variable speed motors and the
like. A key consideration is to avoid slip between the rotating
drum 18 and the inking cylinders as such slip will deregister the
plates from the articles 50 being printed.
* * * * *